An increased sensation of pain or discomfort produced by mimimally noxious stimuli due to damage to soft tissue containing NOCICEPTORS or injury to a peripheral nerve.
A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.
The behaviors of materials under force.
The properties, processes, and behavior of biological systems under the action of mechanical forces.
The properties and processes of materials that affect their behavior under force.
Any method of artificial breathing that employs mechanical or non-mechanical means to force the air into and out of the lungs. Artificial respiration or ventilation is used in individuals who have stopped breathing or have RESPIRATORY INSUFFICIENCY to increase their intake of oxygen (O2) and excretion of carbon dioxide (CO2).
The process by which cells convert mechanical stimuli into a chemical response. It can occur in both cells specialized for sensing mechanical cues such as MECHANORECEPTORS, and in parenchymal cells whose primary function is not mechanosensory.
Resistance and recovery from distortion of shape.
Act of eliciting a response from a person or organism through physical contact.
The maximum stress a material subjected to a stretching load can withstand without tearing. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed, p2001)
Numerical expression indicating the measure of stiffness in a material. It is defined by the ratio of stress in a unit area of substance to the resulting deformation (strain). This allows the behavior of a material under load (such as bone) to be calculated.
Mechanical devices used to produce or assist pulmonary ventilation.
A country of eastern Africa, west of the Red Sea, bordered west and northwest by SUDAN, and south by ETHIOPIA. Its capital is Asmara.
Two-wheeled, engine-driven vehicles.
The glyceryl esters of a fatty acid, or of a mixture of fatty acids. They are generally odorless, colorless, and tasteless if pure, but they may be flavored according to origin. Fats are insoluble in water, soluble in most organic solvents. They occur in animal and vegetable tissue and are generally obtained by boiling or by extraction under pressure. They are important in the diet (DIETARY FATS) as a source of energy. (Grant & Hackh's Chemical Dictionary, 5th ed)
Procedures carried out with regard to the teeth or tooth structures preparatory to specified dental therapeutic and surgical measures.
Techniques using energy such as radio frequency, infrared light, laser light, visible light, or acoustic energy to transfer information without the use of wires, over both short and long distances.
Copies of a work or document distributed to the public by sale, rental, lease, or lending. (From ALA Glossary of Library and Information Science, 1983, p181)
A system containing any combination of computers, computer terminals, printers, audio or visual display devices, or telephones interconnected by telecommunications equipment or cables: used to transmit or receive information. (Random House Unabridged Dictionary, 2d ed)
Transmission of the readings of instruments to a remote location by means of wires, radio waves, or other means. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Conferences, conventions or formal meetings usually attended by delegates representing a special field of interest.
A genus that has been reclassified into BACILLALES incertae sedis because of its ambiguous taxonomy. Previously it was considered part of the Staphylococcaceae family.
Damage inflicted on the body as the direct or indirect result of an external force, with or without disruption of structural continuity.
Hemorrhagic and thrombotic disorders that occur as a consequence of abnormalities in blood coagulation due to a variety of factors such as COAGULATION PROTEIN DISORDERS; BLOOD PLATELET DISORDERS; BLOOD PROTEIN DISORDERS or nutritional conditions.
Course of conduct directed at a specific person that involves repeated (two or more occasions) visual or physical proximity, nonconsensual communication, or verbal, written, or implied threats, or a combination thereof, that would cause a reasonable person fear.
A species of nematode that is widely used in biological, biochemical, and genetic studies.
The application of pathology to questions of law.
Materials that have a limited and usually variable electrical conductivity. They are particularly useful for the production of solid-state electronic devices.
It is used as an oxidizing and bleaching agent and as a disinfectant. (From Grant & Hackh's Chemical Dictionary, 5th ed)
Exclusive legal rights or privileges applied to inventions, plants, etc.
Two-phase systems in which one is uniformly dispersed in another as particles small enough so they cannot be filtered or will not settle out. The dispersing or continuous phase or medium envelops the particles of the discontinuous phase. All three states of matter can form colloids among each other.
Transparent, tasteless crystals found in nature as agate, amethyst, chalcedony, cristobalite, flint, sand, QUARTZ, and tridymite. The compound is insoluble in water or acids except hydrofluoric acid.
The formation of crystalline substances from solutions or melts. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Complex of iron atoms chelated with carbonyl ions.
The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.
Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.
A major orthodox system of Hindu philosophy based on Sankhya (metaphysical dualism) but differing from it in being theistic and characterized by the teaching of raja-yoga as a practical method of liberating the self. It includes a system of exercises for attaining bodily or mental control and well-being with liberation of the self and union with the universal spirit. (From Webster, 3d ed)
The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.
The unfavorable effect of environmental factors (stressors) on the physiological functions of an organism. Prolonged unresolved physiological stress can affect HOMEOSTASIS of the organism, and may lead to damaging or pathological conditions.
Stress wherein emotional factors predominate.
Deaths that occur before LIFE EXPECTANCY is reached within a given population.
Use of a device for the purpose of controlling movement of all or part of the body. Splinting and casting are FRACTURE FIXATION.
Extracellular vesicles generated by the shedding of CELL MEMBRANE blebs.
Lung damage that is caused by the adverse effects of PULMONARY VENTILATOR usage. The high frequency and tidal volumes produced by a mechanical ventilator can cause alveolar disruption and PULMONARY EDEMA.
Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.
A condition of lung damage that is characterized by bilateral pulmonary infiltrates (PULMONARY EDEMA) rich in NEUTROPHILS, and in the absence of clinical HEART FAILURE. This can represent a spectrum of pulmonary lesions, endothelial and epithelial, due to numerous factors (physical, chemical, or biological).
Damage to any compartment of the lung caused by physical, chemical, or biological agents which characteristically elicit inflammatory reaction. These inflammatory reactions can either be acute and dominated by NEUTROPHILS, or chronic and dominated by LYMPHOCYTES and MACROPHAGES.
Toxins closely associated with the living cytoplasm or cell wall of certain microorganisms, which do not readily diffuse into the culture medium, but are released upon lysis of the cells.

Insulin-like growth factor-1 induces Mdm2 and down-regulates p53, attenuating the myocyte renin-angiotensin system and stretch-mediated apoptosis. (1/9460)

Insulin-like growth factor (IGF)-1 inhibits apoptosis, but its mechanism is unknown. Myocyte stretching activates p53 and p53-dependent genes, leading to the formation of angiotensin II (Ang II) and apoptosis. Therefore, this in vitro system was used to determine whether IGF-1 interfered with p53 function and the local renin-angiotensin system (RAS), decreasing stretch-induced cell death. A single dose of 200 ng/ml IGF-1 at the time of stretching decreased myocyte apoptosis 43% and 61% at 6 and 20 hours. Ang II concentration was reduced 52% at 20 hours. Additionally, p53 DNA binding to angiotensinogen (Aogen), AT1 receptor, and Bax was markedly down-regulated by IGF-1 via the induction of Mdm2 and the formation of Mdm2-p53 complexes. Concurrently, the quantity of p53, Aogen, renin, AT1 receptor, and Bax was reduced in stretched myocytes exposed to IGF-1. Conversely, Bcl-2 and the Bcl-2-to-Bax protein ratio increased. The effects of IGF-1 on cell death, Ang II synthesis, and Bax protein were the consequence of Mdm2-induced down-regulation of p53 function. In conclusion, the anti-apoptotic impact of IGF-1 on stretched myocytes was mediated by its capacity to depress p53 transcriptional activity, which limited Ang II formation and attenuated the susceptibility of myocytes to trigger their endogenous cell death pathway.  (+info)

Fibrocartilage in tendons and ligaments--an adaptation to compressive load. (2/9460)

Where tendons and ligaments are subject to compression, they are frequently fibrocartilaginous. This occurs at 2 principal sites: where tendons (and sometimes ligaments) wrap around bony or fibrous pulleys, and in the region where they attach to bone, i.e. at their entheses. Wrap-around tendons are most characteristic of the limbs and are commonly wider at their point of bony contact so that the pressure is reduced. The most fibrocartilaginous tendons are heavily loaded and permanently bent around their pulleys. There is often pronounced interweaving of collagen fibres that prevents the tendons from splaying apart under compression. The fibrocartilage can be located within fascicles, or in endo- or epitenon (where it may protect blood vessels from compression or allow fascicles to slide). Fibrocartilage cells are commonly packed with intermediate filaments which could be involved in transducing mechanical load. The ECM often contains aggrecan which allows the tendon to imbibe water and withstand compression. Type II collagen may also be present, particularly in tendons that are heavily loaded. Fibrocartilage is a dynamic tissue that disappears when the tendons are rerouted surgically and can be maintained in vitro when discs of tendon are compressed. Finite element analyses provide a good correlation between its distribution and levels of compressive stress, but at some locations fibrocartilage is a sign of pathology. Enthesis fibrocartilage is most typical of tendons or ligaments that attach to the epiphyses of long bones where it may also be accompanied by sesamoid and periosteal fibrocartilages. It is characteristic of sites where the angle of attachment changes throughout the range of joint movement and it reduces wear and tear by dissipating stress concentration at the bony interface. There is a good correlation between the distribution of fibrocartilage within an enthesis and the levels of compressive stress. The complex interlocking between calcified fibrocartilage and bone contributes to the mechanical strength of the enthesis and cartilage-like molecules (e.g. aggrecan and type II collagen) in the ECM contribute to its ability to withstand compression. Pathological changes are common and are known as enthesopathies.  (+info)

Receptor mechanisms underlying heterogenic reflexes among the triceps surae muscles of the cat. (3/9460)

The soleus (S), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles of the cat are interlinked by rapid spinal reflex pathways. In the decerebrate state, these heterogenic reflexes are either excitatory and length dependent or inhibitory and force dependent. Mechanographic analysis was used to obtain additional evidence that the muscle spindle primary ending and the Golgi tendon organ provide the major contributions to these reflexes, respectively. The tendons of the triceps surae muscles were separated and connected to independent force transducers and servo-controlled torque motors in unanesthetized, decerebrate cats. The muscles were activated as a group using crossed-extension reflexes. Electrical stimulation of the caudal cutaneous sural nerve was used to provide a particularly strong activation of MG and decouple the forces of the triceps surae muscles. During either form of activation, the muscles were stretched either individually or in various combinations to determine the strength and characteristics of autogenic and heterogenic feedback. The corresponding force responses, including both active and passive components, were measured during the changing background tension. During activation of the entire group, the excitatory, heterogenic feedback linking the three muscles was found to be strongest onto LG and weakest onto MG, in agreement with previous results concerning the strengths of heteronymous Ia excitatory postsynaptic potentials among the triceps surae muscles. The inhibition, which is known to affect only the soleus muscle, was dependent on active contractile force and was detected essentially as rapidly as length dependent excitation. The inhibition outlasted the excitation and was blocked by intravenous strychnine. These results indicate that the excitatory and inhibitory effects are dominated by feedback from primary spindle receptors and Golgi tendon organs. The interactions between these two feedback pathways potentially can influence both the mechanical coupling between ankle and knee.  (+info)

Glycoprotein (GP) Ib-IX-transfected cells roll on a von Willebrand factor matrix under flow. Importance of the GPib/actin-binding protein (ABP-280) interaction in maintaining adhesion under high shear. (4/9460)

Adhesion of platelets to sites of vascular injury is critical for hemostasis and thrombosis and is dependent on the binding of the vascular adhesive protein von Willebrand factor (vWf) to the glycoprotein (GP) Ib-V-IX complex on the platelet surface. A unique but poorly defined characteristic of this receptor/ligand interaction is its ability to support platelet adhesion under conditions of high shear stress. To examine the structural domains of the GPIb-V-IX complex involved in mediating cell adhesion under flow, we have expressed partial (GPIb-IX), complete (GPIb-V-IX), and mutant (GPIbalpha cytoplasmic tail mutants) receptor complexes on the surface of Chinese hamster ovary (CHO) cells and examined their ability to adhere to a vWf matrix in flow-based adhesion assays. Our studies demonstrate that the partial receptor complex (GPIb-IX) supports CHO cell tethering and rolling on a bovine or human vWf matrix under flow. The adhesion was specifically inhibited by an anti-GPIbalpha blocking antibody (AK2) and was not observed with CHO cells expressing GPIbbeta and GPIX alone. The velocity of rolling was dependent on the level of shear stress, receptor density, and matrix concentration and was not altered by the presence of GPV. In contrast to selectins, which mediate cell rolling under conditions of low shear (20-200 s-1), GPIb-IX was able to support cell rolling at both venous (150 s-1) and arterial (1500-10,500 s-1) shear rates. Studies with a mutant GPIbalpha receptor subunit lacking the binding domain for actin-binding protein demonstrated that the association of the receptor complex with the membrane skeleton is not essential for cell tethering or rolling under low shear conditions, but is critical for maintaining adhesion at high shear rates (3000-6000 s-1). These studies demonstrate that the GPIb-IX complex is sufficient to mediate cell rolling on a vWf matrix at both venous and arterial levels of shear independent of other platelet adhesion receptors. Furthermore, our results suggest that the association between GPIbalpha and actin-binding protein plays an important role in enabling cells to remain tethered to a vWf matrix under conditions of high shear stress.  (+info)

Cloning of a stretch-inhibitable nonselective cation channel. (5/9460)

A homologue of the capsaicin receptor-nonselective cation channel was cloned from the rat kidney to investigate a mechanosensitive channel. We found this channel to be inactivated by membrane stretch and have designated it stretch-inactivated channel (SIC). SIC encodes a 563-amino acid protein with putative six transmembrane segments. The cDNA was expressed in mammalian cells, and electophysiological studies were performed. SIC-induced large cation currents were found to be regulated by cell volume, with currents being stimulated by cell shrinkage and inhibited by cell swelling. Single channel analysis showed a conductance of 250 pS with cation permeability (PCl/PNa < 0.1), and the channel possessed some of the characteristics of a stretch-inactivated channel in that it was permeable to calcium, sensitive to membrane stretch, and blocked by Gd3+. Therefore, we cloned one of the mechanosensitive cation channels of mammals, which is considered to regulate Ca2+ influx in response to mechanical stress on the cell membrane.  (+info)

Distinct structural attributes regulating von Willebrand factor A1 domain interaction with platelet glycoprotein Ibalpha under flow. (6/9460)

We have used recombinant von Willebrand factor (vWF) fragments to investigate the properties regulating A1 domain interaction with platelet glycoprotein (GP) Ibalpha. One fragment, rvWF508-704, represented the main portion of domain A1 (mature subunit residues 497-716) within the Cys509-Cys695 disulfide loop. The other, rvWF445-733, included the carboxyl-terminal region of domain D3, preceding A1, and corresponded to the proteolytic fragment originally identified as the GP Ibalpha-binding site (residues 449-728). Conformational changes were induced by reduction and alkylation of the Cys509-Cys695 bond and/or exposure to acidic pH. The cyclic rvWF445-733 fragment exhibited the function of native vWF A1 domain. When immobilized onto a surface, it tethered platelets at shear rates up to 6,300 s-1 mediating low velocity translocation but not stable attachment; in solution, it exhibited limited interaction with GP Ibalpha. In contrast, fragments with perturbed conformation could not tether platelets at high shear rates but promoted stable adhesion at lower shear and bound tightly to GP Ibalpha. Only in the presence of the exogenous modulator, botrocetin, did cyclic rvWF445-733 mediate irreversible adhesion. Thus, conformational transitions in the vWF A1 domain may influence differentially the efficiency of bond formation with GP Ibalpha and the stability of binding.  (+info)

Calculation of a Gap restoration in the membrane skeleton of the red blood cell: possible role for myosin II in local repair. (7/9460)

Human red blood cells contain all of the elements involved in the formation of nonmuscle actomyosin II complexes (V. M. Fowler. 1986. J. Cell. Biochem. 31:1-9; 1996. Curr. Opin. Cell Biol. 8:86-96). No clear function has yet been attributed to these complexes. Using a mathematical model for the structure of the red blood cell spectrin skeleton (M. J. Saxton. 1992. J. Theor. Biol. 155:517-536), we have explored a possible role for myosin II bipolar minifilaments in the restoration of the membrane skeleton, which may be locally damaged by major mechanical or chemical stress. We propose that the establishment of stable links between distant antiparallel actin protofilaments after a local myosin II activation may initiate the repair of the disrupted area. We show that it is possible to define conditions in which the calculated number of myosin II minifilaments bound to actin protofilaments is consistent with the estimated number of myosin II minifilaments present in the red blood cells. A clear restoration effect can be observed when more than 50% of the spectrin polymers of a defined area are disrupted. It corresponds to a significant increase in the spectrin density in the protein free region of the membrane. This may be involved in a more complex repair process of the red blood cell membrane, which includes the vesiculation of the bilayer and the compaction of the disassembled spectrin network.  (+info)

The forward rate of binding of surface-tethered reactants: effect of relative motion between two surfaces. (8/9460)

The reaction of molecules confined to two dimensions is of interest in cell adhesion, specifically for the reaction between cell surface receptors and substrate-bound ligand. We have developed a model to describe the overall rate of reaction of species that are bound to surfaces under relative motion, such that the Peclet number is order one or greater. The encounter rate between reactive species is calculated from solution of the two-dimensional convection-diffusion equation. The probability that each encounter will lead to binding depends on the intrinsic rate of reaction and the encounter duration. The encounter duration is obtained from the theory of first passage times. We find that the binding rate increases with relative velocity between the two surfaces, then reaches a plateau. This plateau indicates that the increase in the encounter rate is counterbalanced by the decrease in the encounter duration as the relative velocity increases. The binding rate is fully described by two dimensionless parameters, the Peclet number and the Damkohler number. We use this model to explain data from the cell adhesion literature by incorporating these rate laws into "adhesive dynamics" simulations to model the binding of a cell to a surface under flow. Leukocytes are known to display a "shear threshold effect" when binding selectin-coated surfaces under shear flow, defined as an increase in bind rate with shear; this effect, as calculated here, is due to an increase in collisions between receptor and ligand with increasing shear. The model can be used to explain other published data on the effect of wall shear rate on the binding of cells to surfaces, specifically the mild decrease in binding within a fixed area with increasing shear rate.  (+info)

Studies have demonstrated the role mechanical stress plays in regulating osteoblastic functions, such as cellular proliferation, osteogenic differentiation, signal transduction and apoptosis (14-16,26). Energy metabolism is essential to maintaining the biological activities of osteoblasts (17). In the present study, we revealed a novel mechanism in osteoblastic mechanobiology, through which cyclic stretch promotes osteoblastic energy metabolism by increasing the expression of enzymes associated with energy metabolism, partially through the Akt/mTOR/p70s6k signaling pathway. Firstly, cyclic mechanical stretch promoted energy metabolism in the MG-63 cells, which was evidenced by the increased glucose consumption, and the increased levels of lactate, intracellular ATP, and energy metabolism-related genes (ATP5B, ATP5F1, ATP5J, F1-ATPase α, LDHA and enolase 1), and ATP5B and ATP5J proteins. Secondly, cyclic mechanical stretch stimulated the activation of the Akt/mTOR/p70s6k pathway by prompting the ...
TY - JOUR. T1 - Acoustically detectable cellular-level lung injury induced by fluid mechanical stresses in microfluidic airway systems. AU - Huh, Dongeun. AU - Fujioka, Hideki. AU - Tung, Yi Chung. AU - Futai, Nobuyuki. AU - Paine, Robert. AU - Grotberg, James B.. AU - Takayama, Shuichi. PY - 2007/11/27. Y1 - 2007/11/27. N2 - We describe a microfabricated airway system integrated with computerized air-liquid two-phase microfluidics that enables on-chip engineering of human airway epithelia and precise reproduction of physiologic or pathologic liquid plug flows found in the respiratory system. Using this device, we demonstrate cellular-level lung injury under flow conditions that cause symptoms characteristic of a wide range of pulmonary diseases. Specifically, propagation and rupture of liquid plugs that simulate surfactant-deficient reopening of closed airways lead to significant injury of small airway epithelial cells by generating deleterious fluid mechanical stresses. We also show that the ...
As modern helmets have become quite capable of defeating the penetration capabilities of ballistic threats, Soldiers may experience head injuries due to blunt trauma caused by helmet back face deformation (BFD). Possible resulting injuries include skull fracture, hematoma, concussion, contusion, diffuse axonal injury, etc. Some of these injuries have been associated with traumatic brain injury. In order to assess potential injury mechanisms prior to fielding new helmets, we have developed a means to experimentally replicate and measure helmet BFD that can be correlated to injury criteria. In this study, helmet performance test methodology is developed using a digital image correlation (DIC) technique. DIC provides the capability to measure dynamic displacements, thereby providing the ability to calculate deformation, velocity, and acceleration rates. We have shown that digital image correlation is an experimentation technique that accurately captures BFD area and rate of deformation for impacts ...
TY - JOUR. T1 - Endothelial cell cytoskeletal alignment independent of fluid shear stress on micropatterned surfaces. AU - Vartanian, Keri B.. AU - Kirkpatrick, Sean J.. AU - Hanson, Stephen R.. AU - Hinds, Monica. PY - 2008/7/11. Y1 - 2008/7/11. N2 - Endothelial cells (ECs) in athero-protective regions are elongated with actin and microtubule fibers aligned parallel to the direction of blood flow. Fluid shear stress (FSS) affects EC shape and functions, but little is known about shape-dependent EC properties that are independent of FSS. To evaluate these properties, ECs were elongated on micropatterned (MP) 25 μm wide collagen-coated lanes (MPECs) and characterized by cell shape index, actin and microtubule alignment, and polarization of the microtubule-organizing center (MTOC). ECs on non-patterned surfaces were also exposed to FSS. MPEC elongation was microtubule-dependent (and actin-independent); shape indices and cytoskeletal alignment were comparable to FSS-elongated ECs. Cytoskeletal ...
We showed that arterial remodeling evolutes overtime with an enlargement and a thinning of the carotid artery, leading to an increased carotid circumferential wall stress. This kind of arterial remodeling evolution is unusual in this high cardiovascular risk population. The pathophysiology of increased carotid circumferential wall stress is not obvious. In response to increased BP, in particular, the pulsatile component, degenerative changes, and fractures of the extracellular matrix component occur in the arterial wall, leading to arterial enlargement.14 The response to dilation is a thickening of the arterial wall, generally considered as adaptive, aiming at normalizing circumferential wall stress. We have previously shown in hypertensive patients that local pulse pressure was associated with increased diameter and intima-media thickness; however, circumferential wall stress was not fully normalized.15 In this study, we showed that this response does not occur in CKD patients and instead we ...
The local mechanical environment is a crucial factor in determining cell and tissue differentiation during vertebrate skeletal development and repair. Unlike the basic response of bone to mechanical load, as described in Wolffs law, the mechanobiological relationship between the local mechanical environment and tissue differentiation influences everything from tissue type and molecular architecture to the formation of complex joints. This study tests the hypothesis that precisely controlled mechanical loading can regulate gene expression, tissue differentiation and tissue architecture in the adult skeleton and that precise manipulation of the defects local mechanical environment can initiate a limited recapitulation of joint tissue development. We generated tissue type predictions using finite element models (FEMs) interpreted by published mechanobiological fate maps of tissue differentiation. The experiment included a custom-designed external fixator capable of introducing daily bending, ...
The acute and chronic adaptation to changes in blood flow occur as a result of endothelium-dependent responses that regulate vascular tone and the organization of the blood vessel wall. Among the most rapid responses of vascular endothelial cells to changes in fluid shear stress are K+ channel activation,2 generation of inositol trisphosphate,3 an increase in [Ca2+]i,23 24 and changes in pHi.4 5 The present study shows that an abrupt decrease in fluid shear stress produces cytosolic alkalinization of vascular endothelial cells by affecting membrane ion transporters that contribute to pHi regulation. After a period of exposure to continuous fluid shear stress at 2.7 dyne/cm2, the abrupt reduction of fluid shear stress from 2.7 to 0.3 dyne/cm2 produced a bicarbonate-dependent increase in pHi of 0.27 pH unit, which was not affected by prior inhibition of the Na+-H+ exchanger alone. Recovery from an NH4Cl prepulse-induced acid load occurred more rapidly when fluid shear stress was abruptly reduced ...
Vascular smooth muscle cells (SMCs) populate in the media of the blood vessel, and play an important role in the control of vasoactivity and the remodeling of the vessel wall. Blood vessels are constantly subjected to hemodynamic stresses, and the pulsatile nature of the blood flow results in a cyclic mechanical strain in the vessel walls. Accumulating evidence in the past two decades indicates that mechanical strain regulates vascular SMC phenotype, function and matrix remodeling. Bone marrow mesenchymal stem cell (MSC) is a potential cell source for vascular regeneration therapy, and may be used to generate SMCs to construct tissue-engineered vascular grafts for blood vessel replacements. In this review, we will focus on the effects of mechanical strain on SMCs and MSCs, e.g., cell phenotype, cell morphology, cytoskeleton organization, gene expression, signal transduction and receptor activation. We will compare the responses of SMCs and MSCs to equiaxial strain, uniaxial strain and mechanical strain
TY - JOUR. T1 - Shear stress activation of SREBP1 in endothelial cells is mediated by integrins. AU - Liu, Yi. AU - Chen, Benjamin P C. AU - Lu, Min. AU - Zhu, Yi. AU - Stemerman, Michael B.. AU - Chien, Shu. AU - Shyy, John Y J. PY - 2002/1/29. Y1 - 2002/1/29. N2 - We investigated the effect of shear stress on the sterol regulatory element-binding protein 1 (SREBP1) in vascular endothelial cells (ECs) and the mechanotransduction mechanism involved. Application of a shear stress (12 dyn/cm2) caused the proteolytic cleavage of SREBP1 and the ensuing translocation of its transcription factor domain into the nucleus. As a result, shear stress increased the mRNAs encoding the low density lipoprotein receptor (LDLR), as well as the binding of 125I-LDL. Using a step flow channel, we showed that SREBP1 activation in ECs under laminar flow is transient, but disturbed flow causes sustained activation. In studying the shear stress-elicited molecular signaling that activates SREBP1, we found that blocking ...
TY - JOUR. T1 - Mechanical regulation of macrophage function - Cyclic tensile force inhibits NLRP3 inflammasome-dependent IL-1β secretion in murine macrophages. AU - Maruyama, Kentaro. AU - Nemoto, Eiji. AU - Yamada, Satoru. PY - 2019/2/7. Y1 - 2019/2/7. N2 - Mechanical stress maintains tissue homeostasis by regulating many cellular functions including cell proliferation, differentiation, and inflammation and immune responses. In inflammatory microenvironments, macrophages in mechanosensitive tissues receive mechanical signals that regulate various cellular functions and inflammatory responses. Macrophage function is affected by several types of mechanical stress, but the mechanisms by which mechanical signals influence macrophage function in inflammation, such as the regulation of interleukin-1β by inflammasomes, remain unclear. In this review, we describe the role of mechanical stress in macrophage and monocyte cell function.. AB - Mechanical stress maintains tissue homeostasis by regulating ...
Previous studies have demonstrated that endothelial cells exposed to laminar shear stress are protected from apoptotic stimuli such as tumor necrosis factor (TNF)-alpha. The authors investigated the role of phosphatidylserine (PS) in this phenomenon. Western blot analysis of cleaved caspase 3 was used as an indicator of apoptosis and revealed that in the absence of serine, endothelial cells exposed to laminar shear stress were unable to protect against TNF-alpha-induced apoptosis, in contrast to sheared cells grown in regular medium. It was also found that shear-induced activation of the Akt pathway was significantly decreased in cells grown without serine. In addition, quantitation of PS using a novel isotopic labeling technique involving the use of formalin revealed that stearoyl-oleic PS (18:0/18:1) did not increase during shear treatment. These findings suggest that basal levels of PS are required to activate survival pathways in endothelial cells and thereby contribute to the overall ...
Introduction: Recent studies indicated that plaque rupture may be associated with: a) extreme mechanical stress/strain conditions; b) large lipid-rich necrotic core; c) thin and weakening fibrous cap; d) cap inflammation; e) intraplaque hemorrhage. Fayad et al and others have been developing multi-modality imaging technology using PET/CT (Positron Emission Tomography/ Computed Tomography) and MRI (magnetic resonance imaging) to identify inflammation in arteries. The goal of this paper is to investigate possible impact of cap inflammation on plaque stress/strain and flow shear stress conditions.. Method: An MRI-PET/CT-based modeling approach is proposed to develop fluid-structure interaction (FSI) models for human carotid plaque assessment and quantify the effect of inflammation on plaque stress/strain conditions. The combined PET/CT and MRI data was acquired from a 74 year old male patient (with informed consent) to assess arterial inflammation. The patient was imaged with dark blood ...
With gene expression profiling it was aimed to identify the differentially expressed genes associated with the regulation of the cytoskeleton to investigate the stretch-induced cell alignment mechanism. A whole genome microarray based analysis of the stretch-induced gene expression changes was done. Gene expression was measured at the beginning of the alignment process showing first reoriented cells after 5 h stretching and at the end after 24 h, where nearly all cells are aligned. Cyclic mechanical stretching of cells results in cellular alignment perpendicular to the stretch direction regulating cellular response. This stress response is assumed to be an adaptation mechanism to reduce extensive stretching but also acts as architectural restructuring changing performance and biomechanics of the tissue. Gene expression profiling of control vs. stretched primary human dermal fibroblasts after 5 h and 24 h demonstrated the regulation of differentially expressed genes associated with metabolism,
Ukropec, Jon A., Fluid shear stress-induced reorganization of adherens junctions in human endothelial cells (1999). Theses. 24 ...
Pattie Mathieu, Paul Cahill, Joseph Mackle, James King, Caitriona Lally, Phenotypic Changes in Rat Smooth Muscle Cells Exposed to Varying Amplitudes of Cyclic Equibiaxial Tensile Strain, UK Society of Biomaterials, Belfast, Ireland, 25th-26th June 2015 ...
Mechanical strain on the artery wall is increased up to 30% in hypertension and is postulated to play a role in vascular injury.2-5 Thrombin is concentrated in vivo at sites of vascular injury, and its effects are mediated chiefly through PAR-1.21 PAR-1 is expressed at very low levels in normal arteries but increases after vascular injury12,18,22 and is increased in the arteries of hypertensive rats.11 Thus, we hypothesized that cyclic strain administered to VSMCs in vitro would increase PAR-1 expression.. Cyclic strain increased PAR-1 mRNA and protein levels (Figures 1 and 2⇑), and after 48 hours of cyclic strain, thrombin also produced a 50% increase in cell number (Figure 3). The significance of these findings is based on the opposite responses of PAR-1 expression to cyclic strain and shear stress. PAR-1 expression increases 2-fold under 20% cyclic strain for 24 hours, whereas it decreases by ≈4-fold under shear stress (25 dyne/cm2) for 24 hours.14 Thus, mechanical forces regulate the ...
The angiotensin II (AngII) type 1 (AT1) receptor is a G protein-coupled receptor that plays a crucial role in the development of load-induced cardiac hypertrophy. We previously reported that mechanical stress, the most important stimulus for cardiac hypertrophy, activates the AT1 receptor through an AngII-independent mechanism, and that this activation is inhibited by an inverse agonist candesartan. However, it remains unclear how mechanical stress activates AT1 receptor and how candesartan exerts inverse agonism. By serial studies using substituted cysteine accessibility mapping, we demonstrated that mechanical stress directly activates AT1 receptor by changing the conformation of AT1 receptor. Transmembrane (TM) VII of AT1 receptor showed a counterclockwise rotation and shift into the ligand-binding pocket in response to mechanical stretch, and candesartan suppressed this helical movement induced by stretch. Comparison of the inverse agonist activities of several AT1 receptor blockers (ARBs) ...
TY - JOUR. T1 - Chapter 7 Monitoring Oxidative Stress in Vascular Endothelial Cells in Response to Fluid Shear Stress. T2 - From Biochemical Analyses to Micro- and Nanotechnologies. AU - Rouhanizadeh, Mahsa. AU - Takabe, Wakako. AU - Ai, Lisong. AU - Yu, Hongyu. AU - Hsiai, Tzung. PY - 2008. Y1 - 2008. N2 - Hemodynamics, specifically, fluid shear stress, modulates the focal nature of atherosclerosis. Shear stress induces vascular oxidative stress via the activation of membrane-bound NADPH oxidases present in vascular smooth muscle cells, fibroblasts, and phagocytic mononuclear cells. Shear stress acting on the endothelial cells at arterial bifurcations or branching points regulates both NADPH oxidase and nitric oxide (NO) synthase activities. The former is considered a major source of oxygen-centered radicals (i.e., superoxide anion [O2· -]) that give rise to oxidative stress; the latter is a source of nitrogen-centered radicals (i.e., nitric oxide [NO]) that give rise to nitrative/nitrosative ...
Many phenomena depend on the features of the fine-scale structure of turbulence, including its intermittency. This article discusses the problem of the turbulent shear in biotechnology including the effect of the shear stress on particles (cells, flocs, cells immobilized on microcarriers). Traditionally, the effect of intermittency has not been taken into account in the shear problem and the theory of isotropic turbulence introduced by Kolmogorov (1941) based on average values of the rate of kinetic energy dissipation, velocity fluctuactions, rates of strain, turbulent stresses etc. has been applied. In this paper a multifractal formalism is employed to describe intermittency; the results of multifractal approach are then compared with predictions of other models of intermittent and non-intermittent turbulence. The multifractal model of intermittent turbulence has been used to derive equations describing flow-particle interactions, including: equations describing turbulent stresses acting upon ...
Fingerprint Dive into the research topics of Microtubule dynamics regulate cyclic stretch-induced cell alignment in human airway smooth muscle cells. Together they form a unique fingerprint. ...
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Soft tissue manual therapies are commonly utilized by osteopathic physicians, chiropractors, physical therapists and massage therapists. These techniques are predicated on subjecting tissues to biophysical mechanical stimulation but the cellular and molecular mechanism(s) mediating these effects are poorly understood. Previous studies established an in vitro model system for examining mechanical stimulation of dermal fibroblasts and established that cyclical strain, intended to mimic overuse injury, induces secretion of numerous pro-inflammatory cytokines. Moreover, mechanical strain intended to mimic soft tissue manual therapy reduces strain-induced secretion of pro-inflammatory cytokines. Here, we sought to partially confirm and extend these reports and provide independent corroboration of prior results. Using cultures of primary human dermal fibroblasts, we confirm cyclical mechanical strain increases levels of IL-6 and adding long-duration stretch, intended to mimic therapeutic soft tissue
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Although molecular dynamics (MD) simulation has been widely used to study of physical properties of nanomaterials, it suffers from a well-known time scale limitation where it cannot simulate processes that take longer than about hundreds of nanoseconds. However, many important processes in physics and materials science take place on time scales that cannot be reached by MD, and thus a key limitation of atomistic simulations is the ability to study the mechanical deformation of nanostructures at experimentally-relevant time scales. In this thesis, a new computational technique is proposed to overcome this issue. Specifically, a generic history-penalized self-learning metabasin escape (SLME) algorithm is developed which demonstrated high computational efficiency in potential energy surface exploration. The SLME method is then coupled, via transition state theory, to mechanical deformation, which enables a direct link between the externally applied strain rate and the energy barriers crossed on the ...
Mechanical strain plays a significant role in the regulation of bone matrix turnover, which is mediated in part by matrix metalloproteinase (MMP)-13 and tissue inhibitors of matrix metalloproteinase (TIMP)-1. However, little is known about the correlation between mechanical strain and osteoblastic cell activities, including extracellular matrix (ECM) metabolism. Herein, we determined the effect of different magnitudes of cyclic tensile strain (0%, 6%, 12%, and 18%) on MMP-13 and TIMP-1 mRNA and protein expression in MC3T3-E1 osteoblasts. Furthermore, we employed specific inhibitors to examine the role of distinct signal transduction pathways known to mediate cellular responses to mechanical strain. We identified a magnitude-dependent increase in MMP-13 and TIMP-1 mRNA and protein levels in response to mechanical strains corresponding to 6%, 12%, and 18% elongation. The strain-induced increases in MMP-13 and TIMP-1 mRNA expression were inhibited by PD098059 and cycloheximide, respectively. Our results
1. Elasticity: The tendency of a material to regain its original dimensions (size and shape) upon the removal of load or force. Eg. Steel is more elastic than rubber. The ratio between tensile stress and tensile strain or Compressive stress and compressive strain is called youngs modulus of Elasticity.. Youngs Modulus of elasticity = E = Stress/Strain = σ / ε. Modulus of rigidity or shear modulus is the ratio of shear stress to the shear strain.. Modulus of Rigidity or Shear Modulus = Shear stress/shear strain Bulk or Volume modulus of elasticity is the ratio of normal stress to the volumetric strain.. Bulk Modulus = Normal stress/Volumetric strain 2. Plasticity: The tendency of a material to permanently deform when subjected to external load beyond the elastic limit. 3. Toughness: The ability of a material to absorb energy in plastic deformation till the point of fracture is known as toughness. Toughness is indicated by the total area under the stress strain curve up to the fracture point. ...
In 1975, we started a research project for the development of microexplosion lith-otripsy. In this project, we investigated the mechanical properties of the urinary tract organs to clarify factors to prevent complications from the method. Tension and expansion tests were performed on the middle portion of the normal ureter taken from fresh cadavers in 1983.. A tension test was performed on eleven ureters in the longitudinal direction and seven in the transverse direction using a universal tensile tester. Tensile strength and maximum tensile stress in the transverse direction of the ureter were weaker than those in the longitudinal direction. Accordingly, it was presumed that ureteral injury first occurred in the transverse direction. The maximum tensile stress of the ureter was higher than that of the bladder, which was previously reported in another paper.. Expansive tests were performed on ten ureters. At the leakage point, the tensile strength and elongation ratio of the external diameter ...
This study is the first to analyze the relationship between in vivo measured shear rate and SS and structural and functional properties of a peripheral conduit artery in patients with ESRD. Patients with ESRD were characterized by outward remodeling of BA, with larger inner diameter and increased stiffness. The outward remodeling was not associated with higher blood flow but with an acceleration of age-associated changes. Whereas BA circumferential wall stress did not differ from that in control subjects, SS was reduced significantly in patients with ESRD as a result of lower shear rate and decreased WBV. Hand warming-induced SS augmentation was associated with FMD and enhanced BAC, which were significantly less pronounced in patients with ESRD, but dilation in response to GTN did not differ in control subjects and patients with ESRD. In patients with ESRD, the partial anemia correction increased SS as a result of enhanced WBV and was associated with an increased FMD and improved BAC.. Arterial ...
We investigated the mechanisms that are responsible for the basal release of endothelium-derived relaxing factor (EDRF), which is likely to be identical with nitric oxide, in the intact coronary circulation. The increase in cGMP content of platelets passing through the coronary bed of the isolated rabbit heart was used as an index of EDRF release. Platelet cGMP content after passage through the heart under control conditions (flow rate of 20 ml/min) amounted to 0.50 +/- 0.10 pmol/mg protein. Inhibition of endothelial nitric oxide synthesis by 30 microM NG-nitro-L-arginine (L-NNA) reduced this amount by more than 60%. Increasing flow rate from 20 ml/min to 40 and 60 ml/min led to flow-dependent dilation as reflected by the subsequent drop in perfusion pressure after an initial rise. The flow-dependent dilation was associated with a significant increase in the normalized platelet cGMP content. L-NNA abolished completely both the flow-dependent dilation and the increase in platelet cGMP content. ...
CiteSeerX - Scientific documents that cite the following paper: Focal contacts as mechanosensors: externally applied local mechanical force induces growth of focal contacts by an mDia1-dependent and ROCK-independent mechanism.
TY - JOUR. T1 - Remodeling of blood vessels. T2 - Responses of diameter and wall thickness to hemodynamic and metabolic stimuli. AU - Pries, Axel R.. AU - Reglin, Bettina. AU - Secomb, Timothy W.. PY - 2005/10. Y1 - 2005/10. N2 - Vascular functions, including tissue perfusion and peripheral resistance, reflect continuous structural adaptation (remodeling) of blood vessels in response to several stimuli. Here, a theoretical model is presented that relates the structural and functional properties of microvascular networks to the adaptive responses of individual segments to hemodynamic and metabolic stimuli. All vessels are assumed to respond, according to a common set of adaptation rules, to changes in wall shear stress, circumferential wall stress, and tissue metabolic status (indicated by partial pressure of oxygen). An increase in vessel diameter with increasing wall shear stress and an increase in wall mass with increased circumferential stress are needed to ensure stable vascular adaptation. ...
The importance of fibre reinforced plastics continually increases due to the excellent mechanical properties, low material and manufacturing costs combined with significant weight reduction. Today, components are usually designed and calculated numerically by using finite element methods (FEM) to avoid expensive laboratory tests. These programs are based on material models including material specific deformation characteristics. In this research project, material models for short glass fibre reinforced plastics are presented to simulate the visco-elasto-plastic deformation behaviour. Prior to modelling specimens of the material EMS Grivory HTV-5H1, consisting of a Polyphthalamide matrix reinforced by 50wt.-% of short glass fibres, are characterized experimentally in terms of the highly time dependent deformation behaviour of the matrix material. To minimize the experimental effort, the cyclic deformation behaviour under tensile and compressive loading (R = −1) is characterized by isothermal ...
An expandable stent having end rings with enhanced strength and radiopacity for implantation in a body lumen, such as an artery, is disclosed. The stent consists of a plurality of radially expandable cylindrical elements generally aligned on a common longitudinal stent axis and interconnected by one or more interconnecting members placed so that the stent is flexible in the longitudinal direction. The expandable cylindrical elements have regions which are subject to high stresses and regions subject to low stresses when the cylindrical elements are radially expanded. In order to increase the radiopacity of the stent, the width of the strut in the low stress region of the stent is designed to be wider than the width of the strut in the high stress regions. If a high radiopaque material is utilized and reduced radiopacity is desired, the width of the strut in the low stress region of the stent can be designed to be narrower than the strut width in the high stress regions. The end rings of the stent are
Growing experimental evidence suggests that mechanical tension plays a significant role in determining the growth, guidance, and function of neurons. Mechanical tension in axons contributes to neurotr
TY - JOUR. T1 - Effects of disturbed flow on endothelial cells. AU - Chiu, J. J.. AU - Wang, D. L.. AU - Usami, S.. AU - Chien, S.. AU - Skalak, R.. PY - 1998/2. Y1 - 1998/2. N2 - Atherosclerotic lesions tend to localize at curvatures and branches of the arterial system, where the local flow is often disturbed and irregular (e.g., flow separation, recirculation, complex flow patterns, and nonuniform shear stress distributions). The effects of such flow conditions on cultured human umbilical vein endothelial cells (HUVECs) were studied in vitro by using a vertical-step flow channel (VSF). Detailed shear stress distributions and flow structures have been computed by using the finite volume method in a general curvilinear coordinate system. HUVECs in the reattachment areas with low shear stresses were generally rounded in shape. In contrast, the cells under higher shear stresses were significantly elongated and aligned with the flow direction, even for those in the area with reversed flow. When ...
In biomecanics the influence of mechanical conditions on healing of biological tissues as bones or soft tissues are analysed. In the frame of this work the mechanical behavior of intact and fractured bones with different bone qualities (osteoporotic versus normal) has been examined in a proximal humerus. Therefore a finite element model of the bone was constructed. It was found that the bone quality has a stronger impact on healing than the actual physiological loading condition does. Hence, for a future therapy of osteoporosis the precise density distribution of each individual bone must be considered. In a second step a biphasic, linear-elastic model for tissue differentiation was developed, where osteochondral healing was simulated by iterative calculation of the elastic modulus of Young within the joint region. By using this model it was possible to predict in which order in all regions of the joint the osteochondral healing took place. The stiffnesses of the newly differentiated tissues ...
In biomecanics the influence of mechanical conditions on healing of biological tissues as bones or soft tissues are analysed. In the frame of this work the mechanical behavior of intact and fractured bones with different bone qualities (osteoporotic versus normal) has been examined in a proximal humerus. Therefore a finite element model of the bone was constructed. It was found that the bone quality has a stronger impact on healing than the actual physiological loading condition does. Hence, for a future therapy of osteoporosis the precise density distribution of each individual bone must be considered. In a second step a biphasic, linear-elastic model for tissue differentiation was developed, where osteochondral healing was simulated by iterative calculation of the elastic modulus of Young within the joint region. By using this model it was possible to predict in which order in all regions of the joint the osteochondral healing took place. The stiffnesses of the newly differentiated tissues ...
TY - CONF. T1 - The Detection of Compression-Induced Recrystallisation of Amorphous Indomethacin. AU - Craig, D.Q.M.. AU - Murphy, J.. AU - Kett, Victoria. AU - Reading, M.. PY - 2003/11. Y1 - 2003/11. M3 - Paper. SP - 1199. EP - 1199. T2 - AAPS Annual Meeting. Y2 - 1 November 2004 through 1 November 2004. ER - ...
L.S. Toth. What did we learn about the deformation behavior of polycrystals by texture modelling, during the last 30 years?. Thermec2018 International Conference on PROCESSING & MANUFACTURING OF ADVANCED MATERIALS Processing, Fabrication, Properties, Applications, Jul 2018, Paris, France. ⟨hal-03180687⟩ ...
Using a free-energy approach introduced by Born and Huang in studying crystalline elasticity, molecular constitutive equations isothermal or adiabatic conditions were developed for elastic polymeric solids. The molecular model consists of non-spherical molecules which are dispersed throughout a random network of crosslinked chain molecules. The non-spherical molecules are assumed to possess an intramolecular separation potential involving the mean-square end-to-end chain distance and a torsional oscillation potential. These non-spherical molecules interact with each other and the network chains via physical physical entanglements and orientational-dependent secondary interactions. Explicit relationships for the number of such subchains were developed and depend upon the distribution, number functionality and chemical efficiency of the crosslink sites, and the functionality of the chain ends. The isothermal constitutive equations depend upon the statistical averages involving the various potentials and a
The present study shows that SMC exposure to laminar flow, at arterial levels of shear stress, reduced PDGF-BB-directed cell migration and invasion. A major mechanism for this effect was the decrease in PDGF-Rβ mRNA expression and protein levels, because shear-dependent inhibition of SMC migration was abolished in cells forced to overexpress PDGF-Rβ. It is of interest that diminished PDGF binding10 and mitogenic response to PDGF10 13 have also been observed in SMCs derived from the intima of injured carotid arteries, suggesting the possibility that SMC exposure to hemodynamic shear stress in vivo may be a mechanism for these effects.. A second mechanism that may contribute to the effect of shear stress to diminish SMC invasiveness across Matrigel is the decrease in MMP-2. MMPs are required for SMCs to invade a barrier constituted by ECM components,3 24 and lower MMP-2 levels without a change in TIMP-2, the main MMP-2 inhibitor,29 may account, at least in part, for the results shown in Figure ...
Extension spring calculator to calculate fatigue resistance of ordinary extension springs with full twisted end. The points at extension spring hook where maximum stresses occurred (tensile stress at point A and shear stress at pont B) are shown in the following figure. In addition to these points, high shear stresses are occured at the body of the extension springs. This calculator can be used to check these critical points fatigue resistance against dynamic loading. Gerber and Goodman failure criterias are used in this calculator for the fatigue evaluation of the spring.. For the fatigue resistance calculations of the points where shear stresses occur (body of the spring and point B at extension spring end), Zimmerlis data [Ref 2] are used to calculate shear endurance limit value. Zimmerlis data is based on torsion in spring so it has not been used for the points where tensile stresses occur. See the Definitions section for more information about the Zimmerlis Data. ...
High compressive stresses will be developed in the coatings while substrates will be subjected to very low tensile stresses (Table 2). In principle, compressive stresses would not lead to cracking of the coatings and the expected tensile stresses are not sufficient to originate cracking of the YTZP substrates. The observed delamination in the specimens with the thickest coatings (Fig. 1) can be attributed to the presence of high shear stresses at the interfaces. The non flat faces of the additional transverse and parallel cracks with large openings reveal that they were probably formed during sintering by a combination of stresses due to thermal expansion and sintering rate mismatches.. Cracks were not observed in the specimens with thinnest coatings (Fig. 2). Even though the necessary condition for delamination should be fulfilled due to the high shear stresses expected at the interfaces, the critical relationship to produce cracking between thickness and residual stresses proposed by Evans ...
We calculate low-density lipoprotein (LDL) transport from blood into arterial walls in a three-dimensional, patient-specific model of a human left coronary artery. The in vivo anatomy data are obtained from computed tomography images of a patient with coronary artery disease. Models of the artery anatomy in its healthy and diseased states are derived after segmentation of the vessel lumen, with and without the detected plaque, respectively. Spatial shear stress distribution at the endothelium is determined through the reconstruction of the arterial blood flow field using computational fluid dynamics. The arterial endothelium is represented by a shear stress-dependent, three-pore model, taking into account blood plasma and LDL passage through normal junctions, leaky junctions, and the vesicular pathway. Intraluminal pressures of 70 and 120 mmHg are employed as the normal and hypertensive operating pressures, respectively. By applying our model to both the healthy and diseased states, we show that ...
Hyaluronan (HA), a highly negatively charged unsulfated glycosaminoglycan (GAG), with an extended length of up to 25 μm seems to be a constitutive component of the endothelial surface layer (ESL). It has been shown that the inner blood vessel surface is lined with a gel-like surface structure, measuring at least 0.5 μm thick. This layer is a protection against coagulation and inflammation, and defends the vessel wall from the development of arteriosclerotic plaques. Interestingly, the size of this surface layer is significantly reduced at vessel sites with disturbed blood flow and low shear stress. Removal of hyaluronan by treatment with hyaluronidase results in a reduction of the ESL to less than 0.1 μm thick and impaired vessel dilatation properties. Recently, studies showed that distinct shear stress conditions can increase the incorporation of hyaluronan into the ESL. Therefore, the present study was undertaken to prove the hypothesis that shear stress can increase the amount of ...
was observed. Intercellular adhesion molecule 1, vascular cell adhesion molecule 1, and E-selectin exhibited a sustained increase in protein expression with time. The mRNA levels of these molecules were transiently upregulated and this was followed by a decrease in expression to levels lower than static controls. Regionally, increased inflammatory marker expression was observed in regions of WSS gradients both proximal and distal to the stenosis when compared with the uniform flow regions, whereas the atheroprotective markers were expressed to a greater extent in regions of elevated WSS magnitudes. The results from the straight/tubular model cannot explain the regional variation seen in the stenosis models. This may help explain the localization of inflammatory cells at the shoulders of plaques in vivo.. ...
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Background and Objective: Cell adhesion plays important roles in maintaining the structural integrity of connective tissues and sensing changes in the biomechanical environment of cells. The objective of the present investigation was to extend our understanding of the effect of cyclic mechanical strain on the expression of adhesion-related genes by human periodontal ligament cells. Material and Methods: Cultured periodontal ligament cells were subjected to a cyclic in-plane tensile deformation of 12% for 5s (0.2Hz) every 90s for 6-24h in a Flexercell FX-4000 Strain Unit. The following parameters were measured: (i)cell viability by the MTT assay; (ii)caspase-3 and -7 activity; and (iii)the expression of 84 genes encoding adhesion-related molecules using real-time RT-PCR microarrays. Results: Mechanical stress reduced the metabolic activity of deformed cells at 6h, and caspase-3 and -7 activity at 6 and 12h. Seventy-three genes were detected at critical threshold values <35. Fifteen showed a ...
Many previous biomechanical studies of bone and bone substitutes have estimated strains in these materials using strain gages. The purpose of this study was to compare digital image correlation (DIC) strain measurements to those obtained from strain gages in order to assess the applicability of DIC technology to common biomechanical testing scenarios. Compression and bending tests were conducted on aluminum alloy, polyurethane foam, and laminated polyurethane foam specimens. Results showed no significant differences in the principal strain values (or the variances) between strain gage and DIC measurements on the aluminum alloy and laminated polyurethane foam specimens. There were significance differences between the principal strain measurements of the non-laminated polyurethane foam specimens, but the deviation from the theoretical results was similar for both measurement techniques. In summary, DIC techniques provide similar results to those obtained from strain gages and also provide full ...
To obtain a more detailed description of the stress-free state of the intestinal wall, longitudinal residual strain measurements are needed. Furthermore, data on longitudinal stress-strain relations in visceral organs are scarce. The present study aims to investigate the longitudinal residual strain and the longitudinal stress-strain relationship in the rat small intestine. The longitudinal zero-stress state was obtained by cutting tissue strips parallel to the longitudinal axis of the intestine. The longitudinal residual stress was characterized by a bending angle (unit: degrees per unit length and positive when bending outwards). Residual strain was computed from the change in dimensions between the zero-stress state and the no-load state. Longitudinal stresses and strains were computed from stretch experiments in the distal ileum at luminal pressures ranging from 0-4 cmH2O. Large morphometric variations were found between the duodenum and ileum with the largest wall thickness and wall area in the
TY - JOUR. T1 - Mechanical stress-induced apoptosis of nucleus pulposus cells. T2 - An in vitro and in vivo rat model. AU - Kuo, Yi Jie. AU - Wu, Lien Chen. AU - Sun, Jui Sheng. AU - Chen, Ming Hong. AU - Sun, Man Ger. AU - Tsuang, Yang Hwei. PY - 2014. Y1 - 2014. N2 - Background: Un-physiological loads play an important role in the degenerative process of inter-vertebral discs (IVD). In this study, we used an in vitro and in vivo rat model to investigate the mechanism of nucleus pulposus (NP) cells apoptosis induced by mechanical stress. Methods: Static compressive load to IVDs of rat tails was used as the in vivo model. For the in vitro model, NP cells were tested under the physiological and un-physiological loading. For histological examination, apoptotic index study, and apoptotic gene expression, we also selected cytokines [bone morphogenetic protein (BMP)-2/7, insulin-like growth factor (IGF)-1, platelet-derived growth factor (PDGF)] to be analyzed. Results: Under mechanical loading, ...
In this paper we report the effect of mechanical deformation on space charge dynamics in crosslinked polyethylene. Thin films were peeled from a 66 kV commercial XLPE cable. Space charge measurements under dc electric fields have been monitored using the pulsed electroacoustic (PEA) technique. It has been found that charge dynamics in deformed XLPE are different from that from undeformed XLPE at lower voltages. At low applied electric field, space charge is dominated by heterocharge in the deformed XLPE while homocharge governs charge formation in undeformed XLPE. However, at high electric field, there is no significant difference between them. Space charge is dominated by homocharge in both deformed and undeformed XLPE. The results indicated that through deformation, molecular chains rearrange so small molecules such as crosslinking by-products, initially being trapped, can be released. Under the influence of the applied electric field they can be ionised to form heterocharge in the sample ...
Lu, Yiling and Li, Wei-Qi and Oraifige, I. and Wang, Wen (2014) Converging parallel plate flow chambers for studies on the effect of the spatial gradient of wall shear stress on endothelial cells. Journal of Biosciences and Medicines, 2. pp. 50-56. ISSN 2327-5081 ...
Purpose: : In the presence of ocular pulse (2.7 mmHg/sec), outflow facility of perfused anterior segments decreases. The exact mechanism by which conventional outflow tissues respond to cyclic pressure oscillations is unknown. The aim of the present study was to test the hypothesis that trabecular meshwork (TM) cell contractility mediates outflow facility responses to cyclic mechanical stress. Methods: : We modified an Ussing chamber perfusion system to deliver cyclic pressure oscillations while monitoring intrachamber pressure in real time (an inverse indicator of contraction-mediated changes in hydraulic conductivity). Mature human TM cell monolayers on polycarbonate filters were perfused at a constant flow rate of 2.5 µl/min until reaching a stable baseline pressure (5-20 mmHg). Chamber contents were exchanged using DMEM (control) or compounds known to affect cell contractility (isoproterenol, Y27632, pilocarpine and nifedipine). After reaching a new baseline, monolayers were subjected to ...
The objective of this work was to further our understanding of the influence hemodynamic forces have on the cardiovascular system. Specifically, the effect of shear stress on platelet aggregability under two pathophysiological conditions was studied. Elevated shear stress levels in stenosed vessels induce platelet aggregation. Increased plasma catecholamine concentrations have also been implicated in the onset of acute coronary ischemic syndromes. This first study was designed to examine the synergistic platelet activation by the interaction of shear stress and epinephrine. Platelets suspensions sheared at subthreshold levels in a cone and plate viscometer showed little or no aggregation unless pretreated with subthreshold concentrations of epinephrine. Monoclonal antibody blockade of glycoproteins (Gp) Ib and IIb/IIIa showed that the synergistic platelet aggregation required functional Gp IIb/IIIa but could partially bypass Gp Ib-von Willebrand factor (vWF) interaction. Binding studies ...
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TY - JOUR. T1 - Fluid mechanical shear induces structural transitions in assembly of a peptide-lipid conjugate. AU - Shimada, Tomoko. AU - Megley, Katie. AU - Tirrell, Matthew. AU - Hotta, Atsushi. PY - 2011/10/7. Y1 - 2011/10/7. N2 - Peptide amphiphiles (PA) can self-assemble into both spherical micelles and worm-like micelles. The control of worm-like micelle formation of PA is an area of active research, most often accomplished by modulating the temperature, salt content, or pH of the environment. In this work, we demonstrate the shear-induced formation of worm-like micelles in our designed peptide amphiphile C 16-W3K. Before adding shear, the peptide amphiphiles form spherical micelles in solution and exhibit little to no viscoelasticity. As the solution is subjected to simple shear flow, with increasing shear rate, spherical micelles form rapidly into elongated worm-like micelles up to microns in length. Though it has been reported that some dilute surfactant solutions exhibit shear-induced ...
TY - JOUR. T1 - Association of remodeling with endothelial shear stress, plaque elasticity, and volume in coronary arteries. T2 - A pilot coronary computed tomography angiography study. AU - Katranas, Sotirios A.. AU - Kelekis, Anastasios L.. AU - Antoniadis, Antonios P.. AU - Chatzizisis, Yiannis S.. AU - Giannoglou, George D.. PY - 2014/5. Y1 - 2014/5. N2 - We sought to noninvasively assess the relationship between arterial remodeling, endothelial shear stress (ESS), and wall stiffness in coronary arteries. We studied 28 coronary arteries from 22 patients undergoing coronary computed tomography angiography (CCTA). The ESS was calculated in 2-mm long segments using computational fluid dynamics. Local remodeling, plaque dimensions, and local wall stiffness were assessed in each segment. The ESS was lower in the regions of excessive expansive remodeling versus compensatory expansive versus inadequate expansive versus constrictive remodeling. Areas of decreased wall stiffness more frequently ...
Fluid shear stress is an important factor to consider when studying the behavior of endothelial cells in vascular system. The main focus of this study is to relate the spatial and temporal variations in shear stress with the extent of oxidative stress, specifically in arterial branching points in comparison with straight regions in the vessels. For this purpose, a micro shear stress sensor has been designed and fabricated with the backside wire binding feature. The sensors were flush mounted in a 3-D scaled up model of carotid arterial bifurcation to measure the spatial variations in shear stress. These measurements were validated by computational fluid dynamics simulations. Arteries with complex geometries develop a low profile and bidirectional type of shear stress, namely oscillatory however unidirectional and high profile of shear stress, namely pulsatile shear stress develops at straight regions of the vessels. We compared the extent of oxidative stress for the endothelial cells which were ...
RATIONALE: Mutations in the LMNA gene, which encodes the nuclear lamina proteins lamin A and lamin C, are the most common cause of familial dilated cardiomyopathy (DCM). Mechanical stress-induced apoptosis has been proposed as the mechanism underpinning DCM in lamin A/C-deficient hearts, but supporting in vivo evidence has been lacking. OBJECTIVE: Our aim was to study interventions to modify mechanical stress in heterozygous Lmna knockout (Lmna(+/-)) mice. METHODS AND RESULTS: Cardiac structure and function were evaluated before and after exercise training, thoracic aortic constriction, and carvedilol treatment. Lmna(+/-) mice develop adult-onset DCM with relatively more severe disease in males. Lmna(+/-) cardiomyocytes show altered nuclear morphology and perinuclear desmin organization, with enhanced responses to hypo-osmotic stress indicative of cytoskeletal instability. Despite these structural defects that provide a template for mechanical stress-induced damage, young Lmna(+/-) mice ...
Purpose: To investigate the involvement of miR-146a in the regulation of responses induced by cyclic mechanical stress (CMS) in human trabecular meshwork (HTM) cells and its effects on intraocular pressure in vivo.. Methods: Effects of miR-146a on the responses to CMS were evaluated in cells transfected with miR-146a mimic or controls transfected with scrambled microRNA. Two primary HTM cell culture lines were incubated in triplicate on flexible bottom plates and subjected to cyclic mechanical stress (20% stretching, 1 cycle per second, during 3 hours). Non-stress parallel control cultures were incubated in similar plates under identical conditions. The effects of miR-146 inhibitor were tested in one primary HTM culture. Changes in expression for miR-146a, IL6, IL8, IL1beta, BMP2, MMP3, HSP70, IRAK1, Serpin, COX1 and COX2 were analyzed by quantitative real time PCR. Three Sprague-dawley rats were injected into the anterior chamber with influenza virus (IAV) expressing miR-146a and the ...
Accurate imaging and measurement of hemodynamic forces is vital for investigating how physical forces acting on the embryonic heart are transduced and influence developmental pathways. Of particular importance is blood flow-induced shear stress, which influences gene expression by endothelial cells and potentially leads to congenital heart defects through abnormal heart looping, septation, and valvulogenesis. However no imaging tool has been available to measure shear stress on the endocardium volumetrically and dynamically. Using 4D structural and Doppler OCT imaging, we are able to accurately measure the blood flow in the heart tube in vivo and to map endocardial shear stress throughout the heart cycle under physiological conditions for the first time. These measurements of the shear stress patterns will enable precise titration of experimental perturbations and accurate correlation of shear with the expression of molecules critical to heart development.. ©2012 Optical Society of ...
The mechanical induction of specific cell phenotypes can only be properly controlled if the local stimuli applied to the cells are known as a function of the external applied loads. Finite element analysis of the cell carriers would be one method to calculate these local conditions. Furthermore, the constitutive model of the construct material should be able to describe mechanical events known to be responsible for cell stimulation, such as interstitial fluid flow. The aim of this study was to define a biphasic constitutive model for fibrin, a natural hydrogel often used for tissue engineering but not yet thoroughly characterized. Large strain poroelastic and poroviscoelastic constitutive equations were implemented into a finite element model of a fibrin gel. The parameter values for both formulations were found by either analytically solving equivalent low strain equations, or by optimizing directly the large strain equations based on experimental stress relaxation data. No poroelastic ...
article{181863, author = {Leybaert, Luc and DEHEMPTINNE, A}, issn = {0014-4819}, journal = {EXPERIMENTAL BRAIN RESEARCH}, language = {eng}, number = {3}, pages = {392--402}, title = {Changes of intracellular free calcium following mechanical injury in a spinal cord slice preparation.}, volume = {112}, year = {1996 ...
TY - JOUR. T1 - Transduction of compressive stress by bronchial epithelium. AU - Tschumperlin, D. J.. AU - Drazen, J. M.. PY - 2002/12/1. Y1 - 2002/12/1. N2 - The epithelial lining of the asthmatic airway is exposed to compressive stress as a consequence of smooth muscle constriction. We have shown previously that in vitro compression of bronchial epithelial cells stimulates extracellular signal-regulated kinase (ERK) phosphorylation and downstream gene expression. Here we show that inhibition of signaling through the epidermal growth factor receptor (EGFR) with a tyrosine kinase inhibitor (AG1478) or a neutralizing antibody to the ligand-binding domain of the EGFR blocks compression-induced ERK phosphorylation. A metalloprotease inhibitor (Galardin) and a neutralizing antibody to heparin binding epidermal growth factor (HB-EGF), but not EGF, also attenuates the compression-induced ERK activation. Our results demonstrate that compressive activation of the ERK signaling pathway requires signaling ...
The relationship of Na+K+ATPase and hypertension has been a topic of concentrated study for the past twenty years. During the onset of hypertension, an increase in Na+K+ATPase in the cellular membranes of the aortic smooth muscle cells has been found to occur. The reason for this increased manifestation of Na+K+ATPase during the beginning stages of hypertension and how the cells regulate this mechanism are still unclear. An initial stage of hypertension is the increase in blood pressure, which contracts the aortic smooth muscle cell lining. Previous in vitro studies have shown the contraction of the aortic smooth muscle cells does demonstrate this increased expression of Na+K+ATPase. The objective of this study was to begin to understand the regulation of the increased expression by beginning with mRNAs control and regulation. Using a Flexercell Strain Unit which cyclically stretches cells, the mRNA expression during 20%, 10%, and non-stretch controls were measured by analysis of Northern ...
TY - JOUR. T1 - Mechanical compression induces VEGFA overexpression in breast cancer via DNMT3A-dependent miR-9 downregulation. AU - Kim, Baek Gil. AU - Gao, Ming Qing. AU - Kang, Suki. AU - Choi, Yoon Pyo. AU - Lee, Joo Hyun. AU - Kim, Ji Eun. AU - Han, Hyun Ho. AU - Mun, Seong Gyeong. AU - Cho, Nam Hoon. N1 - Publisher Copyright: © 2017 The Author(s).. PY - 2017/3/2. Y1 - 2017/3/2. N2 - Tumor growth generates mechanical compression, which may trigger mechanotransduction in cancer and stromal cells and promote tumor progression. However, very little is known about how compression stimulates signal transduction and contributes to tumor progression. In the present study, we demonstrated that compression enhances a tumor progression phenotype using an in vitro compression model, and validated the results from the in vitro model with high-and low-compressed breast cancer tissues. Mechanical compression induced miR-9 downregulation by DNMT3A-dependent promoter methylation in the MDA-MB-231 and ...
In this study, we provide a set of model examples for which we compare the values of the shear modulus under increasing compression or tension with experimental data for brain and fat tissues. The viscoelasticity of brain and adipose tissues was measured following the protocol described in [4]. The dynamic shear storage modulus G′ was measured as a function of time for increasing tensile or compressive strain (from 0% to 40%). Details are given in appendix A.. A hyperelastic constitutive material has a unique stress-strain relationship, independent of strain rate. However, the stress-strain response for viscoelastic materials changes with strain rate, and a strain-energy density function does not exist for these materials. Nonetheless, for many soft tissues, the shape of the nonlinear stress-strain curve is typically invariant with respect to strain rate. In this case, at fixed strain rate, the shear modulus may be captured by a nonlinear hyperelastic model (an example of this approach for fat ...
TY - JOUR. T1 - Influence of biomechanical factors on substructure of pointing movements. AU - Dounskaia, Natalia. AU - Wisleder, Deric. AU - Johnson, Travis. N1 - Funding Information: Acknowledgements The study was supported by NSF grant BCS 0213653 awarded to Dr. Natalia Dounskaia.. PY - 2005/7. Y1 - 2005/7. N2 - Irregularities in the velocity profile near the end of pointing movements have been interpreted as corrective submovements whose purpose is to provide accuracy of pointing to the target. The purpose of the present study was to investigate whether two additional factors related to biomechanical properties of the arm also cause submovements. First, motion termination and stabilization of the limb in the final position required by a discrete pointing task may contribute to submovements. Second, inaccurate regulation of interactive torque at the joints may also cause submovements. To investigate the contributions of these two biomechanical factors and the traditionally considered factor ...
TY - CONF. T1 - Investigation of fundamental powder flow properties of fine lactose particles following mechanical surface modification. AU - Zhou, Qi. AU - Roberts, Benjamin Armstrong. AU - Morton, David Alexander Vodden. AU - Stewart, Peter James. PY - 2008. Y1 - 2008. M3 - Other. SP - 49. EP - 51. ER - ...
TY - CHAP. T1 - Role of the plasma membrane in endothelial cell mechanosensation of shear stress. AU - Butler, Peter J.. AU - Chien, Shu. PY - 2013/1/1. Y1 - 2013/1/1. N2 - Mechanotransduction, which is the process by which cells convert mechanical stimuli to biochemical signaling cascades, is involved in the homeostasis of numerous tissues (reviewed in [21] and [56]). The mechanotransduction of hemodynamic shear stress by endothelial cells (ECs) has garnered special attention because of its role in regulating vascular health and disease. In particular, there is intense interest in identifying the primary molecular mechanisms of the EC sensing of shear stress because its (or their) discovery may lead to clinical interventions in atherosclerosis and other diseases related to mechanobiology. In this chapter, we address the hypothesis that the plasma membrane lipid bilayer is one endothelial cell mechanosensor. Here we define mechanosensor as a cellular structure that responds to mechanical ...
Primary among the mechanical factors linked with abdominal aortic aneurysm (AAA) rupture is peak wall stress, frequently quantified as either the maximum principal or Von Mises stress exerted along the diseased arterial wall. Intraluminal pressure, as an impinging normal force on the wall, has been hypothesized as the dominant influence on this stress and thus the majority of numerical modeling studies of AAA mechanics have focused on static computational solid stress (CSS) predictions [1,2]. Unfortunately, retrospective studies comparing the magnitude of wall stress with the failure strength of the aneurysmal wall have yet to consistently predict the outcome for patient-specific AAAs [3,4]. Previous studies have shown that hemodynamics also plays a significant role in both the biological and mechanical factors that exist within AAAs. In the present investigation, partially and fully coupled fluid-structure interaction (p-FSI and f-FSI, respectively) computations of patient-specific AAA models ...
TY - JOUR. T1 - Tensile stress evolution during the early-stage constrained sintering of Gadolinium-doped ceria films. AU - Sheldon,Brian W.. AU - Nicholas,Jason D.. AU - Mandowara,Sunil. PY - 2011/1. Y1 - 2011/1. N2 - In situ measurements during the constrained sintering of Gd-doped ceria reveal tensile stresses up to ∼250 MPa. These large tensile stresses are likely to contribute to the reduced densification (compared with freely sintered material) typically observed during constrained sintering. While existing models postulate that the tensile stress in a densifying constrained film cannot exceed the sintering stress,sigma;S, the observed tensile stresses are significantly larger than the estimated sigma;S for these materials. To explain this observation, we propose that the formation and extension of interparticle grain boundaries induce substantial tensile stresses in constrained films. A model of this phenomenon shows that converting excess surface energy to elastic strain energy can ...
To mimic in vivo vibration of vocal fold cells, we studied the controllability and range of frequency, acceleration, duration, and shear stress in a new bioreactor attachment. The custom multiwell disc appliance fits into a commercially built rheometer, together termed a torsional rheometer bioreactor (TRB). Previous attachments to the TRB were capable of 50-100 Hz vibrations at relatively high strains but were limited to single-sample experiments. The TRB-multiwell disc system accommodates 20 samples in partially fluid-filled wells in an aseptic environment delivering three different acceleration conditions to different samples simultaneously. Frequency and amplitude used to calculate acceleration along with duration and shear stress were controllable and quantifiable using a combination of built-in rheometer sensors, manufacturer software, and smooth particle hydrodynamics (SPH) simulations. Computed shear stresses at the well bottom using SPH in two and three dimensions were verified with analytical
Plants respond to grazing by producing chemical defense compounds such as protease inhibitors and secondary metabolites such as flavonoids, making them less palatable for feeding and negatively affecting the physiology of insects. The purpose of this study was to assess the phytochemical response of soybean cultivars Glycine max resistant (IAC-17, IAC-24) and susceptible (IAC-P1) to insects after mechanical damage. These cultivars were mechanically injured, and after 24 HPLC was used to identify and quantify flavonoids in plant samples for several hours. The flavonoids daidzein, quercetin, and rutin were measured, with daidzin having the highest concentration. soybean cultivars after mechanical damage. Rutin was biosynthesized by IAC-24. The cultivars IACPL1, IAC-17, and IAC-24 did not show a flavonoid response to mechanical damage. Flavonoids are not produced by mechanical damage in soybean cultivars ...
TY - ABST. T1 - Response of mechanical properties of glasses to their chemical, thermal and mechanical histories. AU - Yue, Yuanzheng. N1 - An invited talk. PY - 2012. Y1 - 2012. N2 - Mechanical properties are a key factor to be considered when designing new glass compositions, optimizing glass processing parameters and defining the glass application fields. However, mechanical properties of glasses are complex values since they are influenced by many factors such as structure, surface, thermal history or excess entropy of the final glass state. Here I review recent progresses in understanding of the responses of mechanical properties of oxide glasses to the compositional variation, thermal history and mechanical deformation. The tensile strength, elastic modulus and hardness of glass fibers are dependent on the thermal history (measured as fictive temperature), tension, chemical composition and redox state. However, the fictive temperature affects the hardness of bulk glass in a complicated ...
TY - JOUR. T1 - Endothelial cell respiration is affected by the oxygen tension during shear exposure. T2 - Role of mitochondrial peroxynitrite. AU - Jones, Charles I.. AU - Han, Zhaosheng. AU - Presley, Tennille. AU - Varadharaj, Saradhadevi. AU - Zweier, Jay L.. AU - Ilangovan, Govindasamy. AU - Alevriadou, B. Rita. PY - 2008/7. Y1 - 2008/7. N2 - Cultured vascular endothelial cell (EC) exposure to steady laminar shear stress results in peroxynitrite (ONOO-) formation intramitochondrially and inactivation of the electron transport chain. We examined whether the hyperoxic state of 21% O2, compared with more physiological O2 tensions (PO2), increases the shear-induced nitric oxide (NO) synthesis and mitochondrial superoxide (O 2.-) generation leading to ONOO- formation and suppression of respiration. Electron paramagnetic resonance oximetry was used to measure O2 consumption rates of bovine aortic ECs sheared (10 dyn/cm2, 30 min) at 5%, 10%, or 21% O2 or left static at 5% or 21% O2. Respiration ...
Title:Flow Shear Induced Changes in Membrane Fluidity: Dependence on Cell- Substrate Adhesion Strength. VOLUME: 9 ISSUE: 1. Author(s): Tamal Das, Tapas K. Maiti and Suman Chakraborty. Affiliation:Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur-721302, India.. Keywords:Cell adhesion, Fluidization, Fluorescence recovery after photobleaching, Lipid raft, Membrane fluidity, Traction force microscopy. Abstract:Besides the internal genetic content and the chemical exchanges with external tissue environment, the physical interactions of cancer cells with its microenvironment also provide the guidelines for successful oncogenesis. During its metastatic journey from primary tumor to distant locations of body, a cancer cell is exposed to stresses of diverse origin and kind, of which fluid shear stresses of interstitial and haematogenic nature have been least studied in relation to their impact in cancer progression. Here, we have designed a biomicrofluidic system ...
Background and Aims Because plants protect each other from wind, stand density affects both the light climate and the amount of mechanical stress experienced by plants. But the potential interactive effects of mechanical stress and canopy shading on plant growth have rarely been investigated and never in stoloniferous plants which, due to ... read more their creeping growth form, can be expected to respond differently to these factors than erect plants. † Methods Plants of ten genotypes of the stoloniferous species Potentilla reptans were subjected to two levels of mechanical stress (0 or 40 daily flexures) and two levels of spectral shading (15 % of daylight with a red : far red ratio of 0.3 vs. 50 % daylight and a red : far red ratio of 1.2). † Key Results Mechanically stressed plants produced more leaves with shorter more flexible petioles, more roots, and more but less massive stolons. Responses to spectral shading were mostly in the opposite direction to thigmomorphogenesis, including ...
Overview. Bacterial adhesion and subsequent colonization of surfaces are the first steps toward forming biofilms, which are a major concern for implanted medical devices and in many diseases. Biofilms are resistant to innate host defences, mechanical removal and antibiotic treatments. It is therefore important to understand the physiological environment and mechanisms that lead to the spread of bacteria. Experimental conditions of biofilm formation on cardiovascular stents, tubing, different surfaces and in the intestines can easily be studied using Cellixs microfluidic pumps and biochips. The dimensions of the biochips facilitate both high and low shear stress conditions. The microcapillary walls of Cellixs biochips may be pre-coated with proteins of interest to promote adhesion and culture of biofilms under different shear stress conditions. Once the biofilm is cultured, it is then possible to flow different substances (e.g. antibiotics) over the biofilm to investigate detachment. There are ...
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Morphological and electrophysiological studies have shown that neurons respond to specific mechanical environments. However, studies linking specific neuropeptide release based on changes in the mechanical environment are lacking. To further study the effect of mechanical stress on the cells of the nervous system, DRG cells isolated from Sprague-Dawley rats have been cultured on a mechanical stress platform which is then subjected to 20% tensile strain. To study the chemical peptide profile...
The Author(s) 2020. Published by Oxford University Press on behalf of Nucleic Acids Research. We used coarse-grained molecular dynamics simulations to characterize the global and local mechanical properties of a DNA origami triangle nanostructure. The structure presents two metastable conformations separated by a free energy barrier that is lowered upon omission of four specific DNA staples (defect). In contrast, only one stable conformation is present upon removing eight staples. The metastability is explained in terms of the intrinsic conformations of the three trapezoidal substructures. We computationally modeled the local accessibility to endonucleases, to predict the reactivity of twenty sites, and found good agreement with the experimental data. We showed that global fluctuations affect local reactivity: the removal of the DNA staples increased the computed accessibility to a restriction enzyme, at sites as distant as 40 nm, due to an increase in global fluctuation. These results raise the ...
The corrosion behavior of a 2024 T351 aluminum alloy exposed to a chloride solution was studied in the present paper. The work was focused on the effect of an environmental and thermal cyclic exposure to corrosive media and aimed to identify the main parameters explaining the changes observed between continuous and cyclic immersion tests. Optical and scanning electron microscope observations showed an increase of the intergranular corrosion damage with the extension of the corrosion from the grain boundaries to the subgrain boundaries for samples exposed to cyclic tests. An experimental set-up, including a laser beam, allowed mechanical stresses induced by the solidification of the electrolyte trapped in the corrosion damage during exposure to negative temperatures to be revealed and the chloride concentration of the electrolyte to be determined. Results were helpful in proposing corrosion mechanism during thermal and environmental cyclic exposure to chloride solutions. ...
TY - JOUR. T1 - Disentangling the multifactorial contributions of fibronectin, collagen and cyclic strain on MMP expression and extracellular matrix remodeling by fibroblasts. AU - Zhang, Y.. AU - Lin, Z.. AU - Foolen, J.. AU - Schoen, I.. AU - Santoro, A.. AU - Zenobi-Wong, M.. AU - Vogel, Viola. PY - 2014. Y1 - 2014. N2 - Early wound healing is associated with fibroblasts assembling a provisional fibronectin-rich extracellular matrix (ECM), which is subsequently remodeled and interlaced by type I collagen. This exposes fibroblasts to time-variant sets of matrices during different stages of wound healing. Our goal was thus to gain insight into the ECM-driven functional regulation of human foreskin fibroblasts (HFFs) being either anchored to a fibronectin (Fn) or to a collagen-decorated matrix, in the absence or presence of cyclic mechanical strain. While the cells reoriented in response to the onset of uniaxial cyclic strain, cells assembled exogenously added Fn with a preferential Fn-fiber ...
Mechanical Engineering Assignment Help, Determine equivalent maximum shear stress in spring, Determine equivalent maximum shear stress in spring: A close coiled helical spring contains a stiffness of 10 N/mm. Its length while fully compressed, with adjacent coils touching each other is 400 mm. G = 80 GPa. (a) Find out the wire diamet
The tensile behavior of Grade 2 α-titanium is characterized for static loading and at moderately high strain rates (200-1000 s-1). An experimental method is proposed to introduce sufficiently long tensile pulses to induce fracture in ductile specimens by incorporating a sacrificial fracture piece of adequately large diameter into a pendulum-driven tensile Kolsky bar. It is established that flow stress increases with strain rate. Necking in α-titanium occurs much earlier at high strain rates compared to static loading and results in significantly smaller necking and fracture strains. An equation describing the influence of strain rate and temperature softening on necking (tensile instability) is derived. The true stress-strain response between necking and fracture is estimated by measuring the final reduction in cross-sectional area. Fracture in specimens was observed using an optical microscope, which revealed typical ductile fracture characteristics. © 2001 Elsevier Science Ltd. All rights ...
Horn, R., Peth, S., & Baumgarten, W. 2012. Development of soil structure and functions: How can mechanical and hydraulic approaches contribute to quantify soil structure dynamics? Soil and Tillage Research 125, 1-2. Mordhorst, A., Zimmermann, I., Peth, S., & Horn, R. 2012. Effect of hydraulic and mechanical stresses on cyclic deformation processes of a structured and homogenized silty Luvic Chernozem. Soil and Tillage Research 125, 3-13. Baba, H.O., & Peth, S. 2012. Large scale soil box test to investigate soil deformation and creep movement on slopes by Particle Image Velocimetry (PIV). Soil and Tillage Research 125, 38-43. Holthusen, D., Haas, C., Peth, S., & Horn, R. 2012. Are standard values the best choice? A critical statement on rheological soil fluid properties viscosity and surface tension. Soil and Tillage Research 125, 61-71 Holthusen, D., Peth, S., Horn, R., & Kühn, T. 2012. Flow and deformation behavior at the microscale of soils from several long‐term potassium fertilization ...
We use a 2 dimensional finite element model with heterogeneous elastic strengths in continental areas to model the regional stress field orientation and relative magnitudes in and around India for 33 Ma, 20 Ma and the present day. The large-scale geological structure of India is embedded in our model by using published outlines of cratons, fold belts and basins, associated with estimates of their relative strengths, enabling the modelling of stress field deflections along interfaces between relatively strong and weak tectonic elements through time. … Read more…. ...
Mechanical stimuli initiate adaptive signal transduction pathways, yet exceeding the cellular capacity to withstand physical stress results in death. The molecular mechanisms underlying trauma-induced degeneration remain unclear. In the nematode C. elegans, we have developed a method to study cellular degeneration in response to mechanical stress caused by blunt force trauma. Herein, we report that physical injury activates the c-Jun kinase, KGB-1, which modulates response elements through the AP-1 transcriptional complex. Among these, we have identified a dual-specificity MAPK phosphatase, VHP-1, as a stress-inducible modulator of neurodegeneration. VHP-1 regulates the transcriptional response to mechanical stress and is itself attenuated by KGB-1-mediated inactivation of a deubiquitinase, MATH-33, and proteasomal degradation. Together, we describe an uncharacterized stress response pathway in C. elegans and identify transcriptional and post-translational components comprising a feedback loop on Jun
The results of this study confirm that an empirical relationship exists between the mechanical environment and gene expression, tissue formation and tissue architecture within a mechanically stimulated healing bone defect. The analyses of tissue types and their molecular architecture verify that mechanical intervention influences tissue repair and that some aspects of early development can be recapitulated within a healing adult defect. It also suggests that the repair process for virtually all skeletal tissues can be manipulated towards desirable outcomes based on precise mechanical intervention.. The FEMs accurately predicted the production and persistence of cartilage within the defects and went as far as to predict the presence of fibrous tissues in specific areas of both the bending and shear models. The mechanical stimulations created uniform cartilage bands across the entire defects that persisted well past the timeframe of bony bridging found in the controls. The bending model predicted ...
An automatic injection device includes a drug-filled vessel having a flexible membrane over a first opening thereof and a puncturable seal in a wall thereof, a hollow needle attached at a first end to the flexible membrane and having a sharp end positioned proximate the puncturable seal housing. A pressure source such as a combustible propellant provides a compressed gas above the flexible membrane to force the membrane into the drug-filled vessel, forcing the hollow needle through the puncturable seal and the drug contained in the vessel through the hollow needle. After the drug has been substantially evacuated from the vessel, the membrane is allowed to return to its pre-expanded state thus retracting the hollow needle into the vessel. Preferably, the flexible membrane is an elastomeric material having a plurality of concentrically configured corrugations to allow expansion of the membrane into the vessel. The inner surface of the vessel may have a dome-like shape such that expansion of the membrane
... this anatomy helps the beak absorb mechanical stress.[4] Species of woodpecker and flicker that use their bills in soil or for ...
Stress incontinence, incontinence as a result of external mechanical disturbances. *Urge incontinence, incontinence that occurs ...
Investigation of mechanical properties of nanowires[edit]. Stress-strain curve provides all the relevant mechanical properties ... 3.3 Mechanical properties of nanowires *3.3.1 Investigation of mechanical properties of nanowires ... displacement curve, which can be converted to a stress vs. strain curve if the nanowire dimensions are known. From the stress- ... Such discrete values arise from a quantum mechanical restraint on the number of electrons that can travel through the wire at ...
Levels of arterial pressure put mechanical stress on the arterial walls. Higher pressures increase heart workload and ... The higher the pressure, the more stress that is present and the more atheroma tend to progress and the heart muscle tends to ... emotional stress, consumption of food or liquid, dietary factors, physical activity, changes in posture, such as standing-up, ...
The center metal is often copper; its role is to act as a carrier for the alloy, to absorb mechanical stresses due to e.g. ... are chemical cleaning and abrasive or mechanical cleaning. In the case of mechanical cleaning, it is important to maintain the ... Copper-rich alloys prone to stress cracking by ammonia.. *Ag-Zn. Silver-zinc. Similar to Cu-Zn, used in jewelry due to its high ... Copper-rich alloys sensitive to stress cracking in presence of ammonia. Zinc. structural, melting, wetting volatile. low. cheap ...
A Structural Mechanical Theoretical Analysis. J Cardiovasc Surg (Turin) 2000 Apr;41(2):193-202 (video) ... The peculiar insertion of chords on the leaflet free margin, however, provides systolic stress sharing between chords according ... S Nazari et al.: Patterns Of Systolic Stress Distribution On Mitral Valve Anterior Leaflet Chordal Apparatus. ...
"Patterns of systolic stress distribution on mitral valve anterior leaflet chordal apparatus. A structural mechanical ...
A deformation is a condition arising from mechanical stress to normal tissue.[16] Deformations often occur in the second or ... The compromised stress management skills of animals whose male parent was exposed to alcohol are similar to the exaggerated ... Behavioral and cognitive disorders, including difficulties with learning and memory, hyperactivity, and lowered stress ... oxidative stress, vascular disruption and specific receptor- or enzyme-mediated teratogenesis.[27] ...
Cell wall thickness is strongly affected by mechanical stress upon the plant. The walls of collenchyma in shaken plants (to ... Collenchyma: a versatile mechanical tissue with dynamic cell walls. Annals of Botany 110 (6): 1083-98. ... Collenchyma provides extra mechanical and structural support, particularly in regions of new growth. ...
Of decisive importance for the piezoelectric effect is the change of polarization P when applying a mechanical stress. This ... Drawing on this knowledge, both René Just Haüy and Antoine César Becquerel posited a relationship between mechanical stress and ... But conventionally, because strain and stress are all symmetric tensors, the subscript of strain and stress can be relabeled in ... the applied mechanical stress. The change in P appears as a variation of surface charge density upon the crystal faces, i.e. as ...
2 to mechanical stress.[92] Uranium nitrides obtained by direct exposure of the metal to nitrogen include uranium mononitride ( ...
Therefore, the quantity (F/A) that is the force per unit area is called the stress. The shear stress at the wall that is ... The changes in shape and flexibility affect the mechanical properties of whole blood. A change in plasma osmotic pressure ... In some cases occurring due to blood hammer, shear stress reaches larger values. While the direction of the stress may also ... σ θ {\displaystyle \sigma _{\theta }\!} is the cylinder stress or "hoop stress". For the thin-walled assumption to be valid the ...
The Ramberg-Osgood equation was created to describe the non linear relationship between stress and strain-that is, the stress- ... 1] "Mechanical Properties of Materials , MechaniCalc". mechanicalc.com. Retrieved 2020-05-27. Hollomon, J. R. (1945). "Tensile ... Johnson-Cook flow stress model Ramberg, W., & Osgood, W. R. (1943). Description of stress-strain curves by three parameters. ... The equation is essentially assuming the elastic strain portion of the stress-strain curve, ε e {\displaystyle \varepsilon _{e ...
"Stress Analysis of Cracks Handbook, Third Edition". American Society of Mechanical Engineers. Archived from the original on ... Tada is an affiliate professor of mechanical engineering at Washington University in St. Louis and co-author of Stress Analysis ... Hiroshi Tada is a mechanical engineer with highly notable works in the field of fracture mechanics. He is also well known as a ...
The stress history in Figure 2 is reduced to peaks and valleys in Figure 3. The first half-cycle starts at tensile peak 1 and ... Mechanical Behavior of Materials. 1: 371-380. Sunder, R.; Seetharam, S. A.; Bhaskaran, T. A. (1984). "Cycle counting for ... At the end of the smaller cycle, the material resumes the stress-strain path of the original cycle, as if the interruption had ... The rainflow-counting algorithm is used in the analysis of fatigue data in order to reduce a spectrum of varying stress into an ...
Proportionality limit Up to this amount of stress, stress is proportional to strain (Hooke's law), so the stress-strain graph ... G. Dieter, Mechanical Metallurgy, McGraw-Hill, 1986 Flinn, Richard A.; Trojan, Paul K. (1975). Engineering Materials and their ... The stress displacement curve of a plane of atoms varies sinusoidally as stress peaks when an atom is forced over the atom ... Offset yield point (proof stress) When a yield point is not easily defined on the basis of the shape of the stress-strain curve ...
The stress in this region of the stress-strain curve can be expressed as, σ c ( ϵ c ) = V f σ f ϵ c + V m σ m ( ϵ c ) {\ ... Their mechanical properties are very important to know, therefore the table of their mechanical properties is given below to ... is the parallel stress, and τ {\displaystyle \tau } is the shear stress. This critical angle is important for the design of the ... three stages of the stress-strain curve. The first stage is the region of the stress-strain curve where both fiber and the ...
Stress[edit]. There are few high-quality studies to demonstrate that stress causes or worsens acne.[60] Despite being ... Mechanical obstruction of skin follicles with helmets or chinstraps can worsen pre-existing acne.[63] Several medications can ... Possible secondary contributors include hormones, infections, diet, and stress. Studies investigating the impact of smoking on ... Rodriguez-Vallecillo E, Woodbury-Fariña MA (December 2014). "Dermatological manifestations of stress in normal and psychiatric ...
Mechanical spalling[edit]. Mechanical spalling occurs at high stress contact points, for example, in a ball bearing. Spalling ... In anti-tank warfare, spalling through mechanical stress is an intended effect of high-explosive squash head (HESH) anti-tank ... One of the simplest forms of mechanical spalling is plate impact, in which two waves of compression are reflected on the free- ... Spalling is a common mechanism of rock weathering, and occurs at the surface of a rock when there are large shear stresses ...
The triggers can vary and include infections, minor injuries, mechanical irritation, operations or stress. In most cases, edema ...
This mechanical soldering is similar to a low temperature brazing operation, in that the mechanical characteristics of the ... Plastic or metal mounting clips or holders may be used with large devices to aid heat dissipation and reduce joint stresses. ... Small mechanical parts are often soldered or brazed as well. Soldering is also used to join lead came and copper foil in ... Mechanical and aluminium soldering[edit]. A number of solder materials, primarily zinc alloys, are used for soldering aluminium ...
Secondary Haversian canals are correlated with size and age, mechanical stress and nutrient turnover. The presence of secondary ... Without this repair, microbreaks would build up, leading to stress fractures and ultimately catastrophic bone failure. The size ... ISBN 0-385-27063-1. Carrier, D.R. (1987). "The evolution of locomotor stamina in tetrapods: circumventing a mechanical ... growth and an active life style because they help to recycle bone to facilitate rapid growth and repair damage caused by stress ...
They are an important component of intermediate filaments, which help cells resist mechanical stress.[1] Expression of these ...
alternating stress that provides the maximum number of alternating stress cycles a material will withstand before failing from ... Shigley's Mechanical Engineering Design. The Mc-Graw-Hill Companies. 2011. p. 305. ISBN 9780073529288. Hertzberg, pp. 530-31. ... is the stress amplitude, σ m {\displaystyle \sigma _{\text{m}}} is the mean stress, σ w {\displaystyle \sigma _{\text{w}}} is ... if the coordinate given by the mean stress and the alternating stress lies under the curve given by the relation, then the part ...
These included strength against; chemicals, thermal shift, and mechanical stress. "Volumetric Pipette". Chemistry Glossary. " ...
Differential stresses that develop as a result of non-uniform drying shrinkage are directly related to the rate at which the ... The inclusion of nanoparticles in a solid or liquid medium can substantially change its mechanical properties, such as ... Such stresses have been associated with a plastic-to-brittle transition in consolidated bodies, and can yield to crack ... Differential stresses arising from inhomogeneous densification have also been shown to result in the propagation of internal ...
The associated stresses on the cell can cause damage directly.. Intracellular ice formation. While some organisms and tissues ... Too much extracellular ice can cause mechanical damage to the cell membrane due to crushing.. Dehydration. Migration of water, ... In 1953, he suggested that damage to red blood cells during freezing was due to osmotic stress,[4] and that increasing the salt ... US9314015B2, Stephen Van Sickle, Tanya Jones, "Method and apparatus for prevention of thermo-mechanical fracturing in vitrified ...
Plants respond and adapt to environmental factors, such as light and mechanical stress from wind. Leaves need to support their ... However, horizontal alignment maximizes exposure to bending forces and failure from stresses such as wind, snow, hail, falling ... but they may instead exemplify a pattern formed in a stress tensor field.[32][33][34] ... A Fractal Analysis Approach to Tune Mechanical Rigidity of Scaffolding Matrix in Thin Films". Advanced Materials Research. 1141 ...
2 Mechanical characteristics *2.1 Pseudoelasticity. *2.2 Residual stress. *2.3 Fung-elastic material *2.3.1 Isotropic ... Residual stress[edit]. In physiological state soft tissues usually present residual stress that may be released when the tissue ... Mechanical characteristics[edit]. At small strains, elastin confers stiffness to the tissue and stores most of the strain ... "Vascular adaptation and mechanical homeostasis at tissue, cellular, and sub-cellular levels". Cell Biochemistry and Biophysics ...
This feature cuts down on mechanical stress. An additional feature of the Linerlock is the addition of a ball detent. This ...
Plants respond and adapt to environmental factors, such as light and mechanical stress from wind. Leaves need to support their ... but they may instead exemplify a pattern formed in a stress tensor field.[33][34][35] ... A Fractal Analysis Approach to Tune Mechanical Rigidity of Scaffolding Matrix in Thin Films". Advanced Materials Research. 1141 ... veins form a scaffolding matrix imparting mechanical rigidity to leaves.[30] ...
With regards to listening fatigue, the relevant mechanical and biochemical mechanisms primarily deal with inner ear and cochlea ... rendering them less effective and putting more stress on the inner hair cells.[4] This can lead to fatigue and temporary ...
... is a form of alternative medicine mostly concerned with the diagnosis and treatment of mechanical disorders of the ... experienced different ranges of stress when studying.[187] The chiropractic leaders and colleges have had internal struggles.[ ... and self-reported function in patients with mechanical neck pain: a systematic review". J Orthop Sports Phys Ther. 41 (9): 633- ... stress reduction recommendations, ice pack/cryotherapy, extremity adjusting (also mentioned in previous paragraph), trigger ...
Employers of the time would have rather hired chemists and mechanical engineers.[5] Courses in chemical engineering offered by ... USA the education of chemical engineering graduates from the Baccalaureate programs accredited by ABET do not usually stress ... describing the use of mechanical equipment in the chemical industry, became common vocabulary in England after 1850.[6] By 1910 ...
Some views in Jewish philosophy stress that free will is a product of the intrinsic human soul, using the word neshama (from ... Traditional arguments for incompatibilism are based on an "intuition pump": if a person is like other mechanical things that ... be considered a feature of conscious life that corresponds to functions of the organism that not only evade a causal mechanical ...
Stress incontinence, incontinence as a result of external mechanical disturbances. *Urge incontinence, incontinence that occurs ...
Miscellaneous mechanical failures: parts, particularly moving parts, of any mechanism can break or fail, preventing normal ... since they accurately represent the performance of consumer drives in the enterprise or under extreme stress, but may not ... Head crash: a head may contact the rotating platter due to mechanical shock or other reason. At best this will cause ...
Wachtman, John B. (1996). Mechanical Properties of Ceramics. New York: Wiley-Interscience, John Wiley & Son's. ISBN 978-0-471- ... Engineering ceramics are known for their stiffness and stability under high temperatures, compression and electrical stress. ... This causes many interesting electrical, magnetic, optical, and mechanical properties. In describing nanostructures it is ... The study of polymers combines elements of chemical and statistical thermodynamics to give thermodynamic and mechanical, ...
Increases in mechanical stress tend to produce bones that are thicker and stronger. Disruptions in homeostasis caused by ... Surface hypoplasias record stressors occurring from about one to seven years, or up to 13 years if the third molar is included ... The stress hormone cortisol is deposited in hair as it grows. This has been used successfully to detect fluctuating levels of ... Markers of occupational stress, which include morphological changes to the skeleton and dentition as well as joint changes at ...
The mechanical motion of the micro-structure is sensed either electronically or optically. The mechanical structure is often ... The center shuttle are connected to two clamped-clamped conductors used to change the internal stress of the moving structure ... Direct mechanical displacement is measured by an external laser source and a detector. The resolution of 1 nT can be reached. ... The mechanical structure is actually driven by the heating resistor at its resonance. Lorentz force applying at the U-shape ...
American Society of Mechanical Engineers, 2005. *^ Bureau Veritas: Fatigue of top chain of mooring lines due to in plane and ... ofte brukes forkortelsen HISC fra engelsk hydrogen induced stress cracking). Spesielt for høyfast stål og høye belastninger vil ... American Society of Mechanical Engineers, 2014. *^ Jean P. K. Goessens and D. L'Hostis, 2005, "Failure of Chains by Bending on ... American Society of Mechanical Engineers, 2009. *^ Chaplin, C. R., G. Rebel, og I. M. L. Ridge. "Tension/torsion interactions ...
Mitchell, J.T. & Everly, G.S. (1993). Critical incident stress debriefing: An operations manual for the prevention of traumatic ... Mechanical Ventilation Trainers. Examples of Screen-Based Simulations[37]Edit. *ACLS Simulator ... The aim is to reduce stress, accelerate normal recovery, and assist in both the cognitive and emotional processing of the ... stress among emergency services and disaster workers. Ellicott City, MD: Chevron Publishing. ...
Stress-Corrosion Cracking (SCC)[edit]. Main article: Stress corrosion cracking. SCC is the unexpected sudden failure of a ... Courtney, Thomas H. (2005-12-16). Mechanical Behavior of Materials: Second Edition. Waveland Press. ISBN 9781478608387. .. .mw- ... Wiederhorn, S. M.; Bolz, L. H. (1970-10-01). "Stress Corrosion and Static Fatigue of Glass". Journal of the American Ceramic ... Usually a stress called static fatigue limit is present, representing the boundary below which the material does not fracture, ...
Stress hyperglycemia. *Stress ulcer. Iatrogenesis. *Methicillin-resistant Staphylococcus aureus. *Oxygen toxicity. *Refeeding ...
When the rattles were shaken at night during ceremonies, the friction and mechanical stress of the quartz crystals banging ... The rattle produces flashes of light (mechanoluminescence) created when quartz crystals are subjected to mechanical stress when ...
Greater mechanical stress brought on by eccentric contractions is what leads to hypertrophy in individuals undergoing eccentric ... "produce enough mechanical stress to induce muscle hypertrophy without over-stressing which could produce muscle fiber damage. ... While eccentric stress is related to the injury, high force eccentric exercises are needed to maximize recovery.[23] ... Negative work is the mechanical energy absorbed by the work conducted on a muscle when the force on the muscle is greater than ...
"Mechanical conservation of energy / Maxwell's wheel" (PDF). PHYWE Laboratory Experiments: Physics. Archived (PDF) from the ... which was the temporary double refraction produced in viscous liquids by shear stress.[37] His other paper was "Rolling Curves ... In it he described a mechanical means of drawing mathematical curves with a piece of twine, and the properties of ellipses, ... permeating all space and yet apparently undetectable by mechanical means, proved impossible to reconcile with experiments such ...
Other processes involved with lung damage include oxidative stress produced by high concentrations of free radicals in tobacco ... devices and other mechanical devices, may reduce the need for increased ventilatory assistance, the duration of ventilatory ...
... and endured all the stress and ethical dilemmas that the first use of such a risky but also groundbreaking procedure implied. ... was immobilized by the antiquated mechanical equipment. ...
"Frontiers in Mechanical Engineering. 4. doi:10.3389/fmech.2018.00016.. *^ Varenberg, M. (2013). "Towards a unified ... Causes of wear can be mechanical (e.g., erosion) or chemical (e.g., corrosion). The study of wear and related processes is ... Abrasion (mechanical) - Process of wearing down a surface. *Tribometer - An instrument that measures tribological quantities - ...
Radunovic A, Annane D, Rafiq M, Brassington R, Mustfa N (6 October 2017). "Mechanical ventilation for amyotrophic lateral ... It may work by protecting motor neurons from oxidative stress.[107] The most common side effects are bruising and gait ... Mechanical ventilation can prolong survival but does not stop disease progression.[14] A feeding tube may help.[15] The disease ...
In Finnish music education, as in academics, the stress is fostering in pupils above all a love and enjoyment of the subject ... a smaller number of longer and more complicated questions that are supposed to test more than memorization and quick mechanical ...
"Autophagy in Stress, Development & Disease, 2003, Gordon Research Conference".. *^ "Autophagy in Health and Disease (Z3), 2007 ... Proteins involved in autophagy are reduced with age in both human and mouse articular cartilage.[76] Mechanical injury to ... In cancerous cells, autophagy is used as a way to deal with stress on the cell.[84] Once these autophagy related genes were ... A 2010 French study of nematodes, mice and flies showed that inhibition of autophagy exposed cells to metabolic stress. ...
A motor protein in cells which converts the chemical energy contained in ATP into the mechanical energy of movement.. Contents ... when exposed to some external stress or chemical compound such as a strong acid or base, a concentrated inorganic salt, or an ...
In general, parting is caused by some stress applied to a crystal. The sources of the stresses include deformation (e.g. an ... Other less general tests include fluorescence, phosphorescence, magnetism, radioactivity, tenacity (response to mechanical ...
Process annealing: A process used to relieve stress in a cold-worked carbon steel with less than 0.3% C. The steel is usually ... The purpose of heat treating carbon steel is to change the mechanical properties of steel, usually ductility, hardness, yield ... Not only does this process reduce internal stresses and stress cracks, but it also increases the impact resistance.[17] ... These internal stresses may cause stress cracks on the surface. Quenched steel is approximately three times harder (four with ...
D. Tang, C. Ren, M. Wang, X. Wei, N. Kawamoto, C. Liu, Y. Bando, M. Mitome, N. Fukata and D. Golberg : «Mechanical Properties ... M DEMURA, D GOLBERG and T HIRANO : «An athermal deformation model of the yield stress anomaly in Ni3Al» Intermetallics 15[10] ( ... P. M F J Costa, P. B Cachim, U. K Gautam, Y. Bando and D. Golberg : «The mechanical response of turbostratic carbon nanotubes ... P. M F J Costa, P. B Cachim, U. K Gautam, Y. Bando and D. Golberg : «The mechanical response of turbostratic carbon nanotubes ...
Courtney, Thomas (2000). Mechanical Behavior of Materials. United States of America: Waveland Press, Inc. pp. 247-249. ISBN 1- ... Reinforcement gives CFRP its strength and rigidity, measured by stress and elastic modulus respectively. Unlike isotropic ... For synthetic polymers such as PAN or rayon, the precursor is first spun into filament yarns, using chemical and mechanical ... Precursor compositions and mechanical processes used during spinning filament yarns may vary among manufacturers. After drawing ...
Also add more stress to your abs with 2 second hold. Other versions[edit]. There are some less difficult versions, which reduce ... resulting in much higher mechanical load on the triceps. ... as it poses less stress and requires less effort. ... Raising the hands with the aid of push-up bars or a dumbbell allows for greater range of motion, providing further stress for ...
Mechanical stress plays an essential role in bone homeostasis. Although mechanotransduction-induced de novo gene expression is ... mechanical stress JNK/p38 MAP kinase bone remodeling Fn14 MCP-3 This is a preview of subscription content, log in to check ... Mechanical stress plays an essential role in bone homeostasis. Although mechanotransduction-induced de novo gene expression is ... 2010) Mechanical stress modulates bone remodeling signals. In: Sasano T., Suzuki O. (eds) Interface Oral Health Science 2009. ...
The voltage sensitivity appears to be an ancient property of these channels that protects cells from mechanical stress. ... The Piezo1 and Piezo2 ion channels are known to open up response to the slightest mechanical stimulus. MDC researchers have now ... The mechanism seems to protect blood cells from the mechanical stress they would otherwise be permanently exposed to as they ... How cells protect themselves against mechanical stress Max Delbrück Center for Molecular Medicine in the Helmholtz Association ...
When mechanical pressure is applied to the embryo, ß catenin enters the cell nucleus (on right), whereas to perform its role as ... But on applying mechanical pressure to the Drosophila embryo, Emmanuel Farge noted that the Twist gene was then expressed in ... Significantly, the Twist gene is not expressed in mutant embryos in which this mechanical pressure is absent. This is the first ... "Mechanical Induction of Twist in the Drosophila Foregut/Stomodeal Primordium" Emmanuel Farge Current biology (www.current- ...
Various mechanical stimuli have been studied as in vitro model systems and have been shown to act through numerous signaling ... Here, we examine the various types of stress and the sequential response of transduction pathways that result in changes in ... whereas a lack of mechanical stimulation, as seen during spaceflight or prolonged bed rest, can lead to osteoporosis. Thus, ...
Arrows denote regions of high mechanical stress that branch, and asterisks denote regions of high mechanical stress that do not ... Mechanical stress profiles of tubules surrounded by matrices of different stiffness: (A) Ematrix = 680 Pa, (B) Ematrix = 860 Pa ... Mechanical stress profiles of tubules with increasing contractility: prestress (pt) that yields prestrain (ε0) of (A) 0.2 % (B) ... Endogenous patterns of mechanical stress are required for branching morphogenesis.. Gjorevski N1, Nelson CM. ...
How fat cells respond to mechanical loads can be studied now through a new method developed by researchers at the Tel Aviv ... Stress and the Gender Divide. Stress has become entwined in the current lifestyle of a young working couple and has resulted in ... Gefen, applying mechanical loads on tissues can affect many different cells within our bodies. He believes that, much like bone ... Gefen and his team of researchers can determine how much mechanical load can be tolerated by fat cells, and at what point the ...
A heat cycle test was performed in order to analyze the thermo-mechanical ... This paper describes the thermo-mechanical performance of thermoelectric modules. ...
In the nematode C. elegans, we have developed a method to study cellular degeneration in response to mechanical stress caused ... VHP-1 regulates the transcriptional response to mechanical stress and is itself attenuated by KGB-1-mediated inactivation of a ... authors report that a MAPK phosphatase VHP-1 is induced by trauma and regulates transcriptional responses to mechanical stress ... Among these, we have identified a dual-specificity MAPK phosphatase, VHP-1, as a stress-inducible modulator of ...
The object of this study is to provide evidence for new ways to explore bones functional adaptation to mechanical stress made ... Some factors regarding age, gender and ethnicity and the interplay with mechanical stress influencing bone remodelling are ... This paper presents the main ideas of mechanical stress and bone remodelling from a novels perspective. ... is reviewed to parallel the implications that lead to the incident with the findings on the link between mechanical stress and ...
... colloidal silica and bleach including sodium hypochlorite applied under time and pressure control to achieve chemo-mechanical ... In the present invention Stress-Free Chemo-Mechanical Polishing Agent For II-VI Compound Semiconductor Single Crystals And ... Stress-free chemo-mechanical polishing agent for II-VI compound semiconductor single crystals and method of polishing. US ... The substantially stress-free chemo-mechanical polishing agent for Group II-VI compound crystal semiconductors of the present ...
Here, we review recent advances demonstrating that mechanical stress emanating from the cytoskeleton can activate pathways in ... Cells are constantly adjusting to the mechanical properties of their surroundings, operating a complex mechanochemical feedback ... mechanical stress mechanotransduction; nucleoskeleton; lamina; lamin; LINC; nucleus; mechanical stress ... Belaadi, N.; Aureille, J.; Guilluy, C. Under Pressure: Mechanical Stress Management in the Nucleus. Cells 2016, 5, 27. ...
... we obviously stress our tissues. Our tissues are made up of cell, so we also stress the cells. This study shows how that stress ... Posted: Mon Sep 12, 2016 12:45 am Post subject: Mechanical stress affects our chromatin. ... Mechanical force triggers gene expression by stretching chromatin How genes in our DNA are expressed into traits within a cell ... Unfortunately the study does not vary the nature of the stress nor discuss the effects of duration. That would be very ...
The finite element models of lumbar motion segments were useful in analyzing internal stresses, given segment geometry, ...
... from infectious challenges and from pathologic lung distention produced by excessive tidal volume delivered during mechanical ... Pathologic mechanical stress and endotoxin exposure increases lung endothelial microparticle shedding Am J Respir Cell Mol Biol ... produced from human lung ECs exposed to physiologic or pathologic mechanical stress (5 or 18% cyclic stretch [CS]) or to ... from infectious challenges and from pathologic lung distention produced by excessive tidal volume delivered during mechanical ...
Abstract 10698: Syndecan-4 Regulates Myofibroblast Differentiation Following Mechanical Stress. Kate M Herum, Ida G Lunde, Dina ... Mechanical stress caused by pressure overload of the heart leads to differentiation of cardiac fibroblasts into myofibroblasts ... Abstract 10698: Syndecan-4 Regulates Myofibroblast Differentiation Following Mechanical Stress. Kate M Herum, Ida G Lunde, Dina ... Abstract 10698: Syndecan-4 Regulates Myofibroblast Differentiation Following Mechanical Stress. Kate M Herum, Ida G Lunde, Dina ...
Transmission of mechanical stimuli through the actin cytoskeleton has been proposed as a mechanism for rapid long-distance ... Dynamics of Mechanical Signal Transmission through Prestressed Stress Fibers Alternate Title:Mechanical Signaling through ... Table 1 summarizes the geometric and mechanical charcteristics of the stress fiber considered in the present study. The stress ... We assume that the cytoskeletal filament is an actin stress fiber because stress fibers have been implicated in mechanical ...
This pre-conditioning phenomenon has been documented in many models of protection against oxidative stress, including ... Cells and tissues can be protected against a potentially lethal stress by first exposing them to a brief dose of the same or ... Mechanical and electromagnetic induction of protection against oxidative stress Bioelectrochemistry. 2001 Jan;53(1):87-95. doi ... We report here that constant mechanical vibration pre-conditions chick embryos, protecting them during subsequent stress from ...
This aim of the present narrative review was to illustrate the current evidence on the importance of mechanical stress in the ... Overall, treatment selection should be tailored to counterpart the effects of mechanical stress, which influences inflammation ... 2. Airways Mechanical Stress in Lung Diseases. The role of mechanical stimuli in airway remodelling has been hypothesized by ... This aim of the present narrative review was to illustrate the current evidence on the importance of mechanical stress in the ...
Mechanical stress in Arabidopsis leaves orients microtubules in a continuous supracellular pattern.. Jacques E, Verbelen JP, ... Mechanical stress in Arabidopsis leaves orients microtubules in a continuous supracellular pattern ... Mechanical stress in Arabidopsis leaves orients microtubules in a continuous supracellular pattern ... Mechanical stress in Arabidopsis leaves orients microtubules in a continuous supracellular pattern ...
The cancer and healthy cell populations were treated either with mechanical stress delivered by a micropump (fabricated by deep ... PCA analysis was also performed to distinguish control and stressed cells within different cell lines. These mechanical induced ... Moreover, Raman spectroscopy analysis, after mechanical treatment, in the range between 700-1800 cm−1, indicated a relative ... In this work, we employed two different strategies to mechanically stress cancer cells. ...
EFFECT OF OXIDATION STRESS ON THE MECHANICAL PROPERTY OF HUMAN HAIR. Yoko Akiyama, Yusuke Doi, Yukako Matsue, Fumihito Mishima ... 5] Y. Akiyama, Y. Doi, Y. Matsue, F. Mishima, and S. Nishijima,Effect of Oxidation Stress on the Mechanical Property ofHuman ... 14] F.-J. Wortmann and H. Zahn, The stress/strain curve of α-keratin fibres and the structure of the intermediate filament, ... 10] A.N. Parbhu, W.G. Bryson, and R. Lal, Disulfide bonds in theouter layer of keratin fibres confer higher mechanical rigidity: ...
The mechanical stress levels are significantly increased within the fibrous cap structure at the upstream side of the plaque. ... a thin fibrous cap and a soft lipid core resulted in the highest mechanical stresses calculated at the proximal side of the ... resulting in higher strains and thus higher mechanical stresses in the upstream portion of the plaque cap, potentially ... to quantify their effects on the caps mechanical stress state by performing analyses using computational fluid-structure ...
Stresses in oxidized claddings and mechanical stability of oxide scales. [Helmut Steiner; Forschungszentrum (Karlsruhe);] ... Stresses in oxidized claddings and mechanical stability of oxide scales. Author:. Helmut Steiner; Forschungszentrum (Karlsruhe) ... schema:name "Stresses in oxidized claddings and mechanical stability of oxide scales" ;. schema:productID "179999030" ;. schema ... Stresses in oxidized claddings and mechanical stability of oxide scales/Helmut Steiner; Forschungszentrum (Karlsruhe);; ...
Mechanical stress on hearts triggers β-arrestin-dependent cell survival signaling through the angiotensin receptor. ... Mechanical stress on hearts triggers β-arrestin-dependent cell survival signaling through the angiotensin receptor. ... β-Arrestin-Biased Agonism of the Angiotensin Receptor Induced by Mechanical Stress ... β-Arrestin-Biased Agonism of the Angiotensin Receptor Induced by Mechanical Stress ...
... experimental results on the residual mechanical stress generated during the different steps of the photolithography process of ... The main aim is to investigate the causes and optimise the fabrication process in order to minimise the residual stresses. It ... Therefore, it is important to investigate each process step in relation to the internal stress formulation during the SU-8 ... during the fabrication process considerable internal stress is generated in SU-8 films, which causes the appearance of cracked ...
Electrothermal mechanical stress reference design flow for printed circuit boards. 4th December 2017 4:41 pm 4th December 2017 ... Electrothermal mechanical stress reference design flow for printed circuit boards. Contact Supplier ... This paper presents a reference design flow for solving the electrical, thermal and mechanical challenges of a printed circuit ... thermal and mechanical characteristics of the board - all using ANSYS tools. The multiphysics simulation yields power losses ...
... naturally infected with the parasite Perkinsus marinuswere subjected to a mechanical stress by centrifugation, and immune ... Irrespective of mechanical stress, an increased number of hemocytes were observed in P. marinus-infected oysters that ... Expression of a high-mobility group protein and hemocyte phagocytosis were significantly upregulated upon mechanical stress ... naturally infected with the parasite Perkinsus marinus were subjected to a mechanical stress by centrifugation, and immune ...
Conclusion: Inflammation and mechanical stress trigger expression of osteogenic genes in VICs in a side-specific manner, while ... This process may be triggered by several factors including inflammation, mechanical stress or interaction of cells with certain ... We hypothesize that inflammation and mechanical stress stimulate osteogenic differentiation of human aortic valve interstitial ... We hypothesize that inflammation and mechanical stress stimulate osteogenic differentiation of human aortic valve interstitial ...
Mechanical Stress Effects on the Cardiovascular Adaptations of Peripheral Arterial Calcifications Among Athletes (MediaSport). ... Impact and Consequences of Mechanical Stress on the Cardiovascular Adaptations of Peripheral Arterial Calcifications. ...
  • A key player in this process is an ion channel in the skin's inner cell membranes that was only discovered seven years ago: Piezo2 responds to mechanical stimuli by opening when the cell membrane surrounding it expands. (eurekalert.org)
  • Until now, the assumption was that Piezo1 and Piezo2 reacted solely to mechanical stimuli - perhaps because of the unique structure of the two ion channels, which is fundamentally different to that of classical voltage-gated channels. (eurekalert.org)
  • When the membrane voltage is normal, which in most cells is ?60 mV, around 95 percent of all the Piezo channels are closed and remain closed even when exposed to mechanical stimuli," explains Lewin. (eurekalert.org)
  • This importance of voltage regulation is not only demonstrated by the fact that it has clearly existed for well over 100 million years, but Moroni also discovered a mutation in the Piezo1 channels of human blood cells that alters the voltage dependence of these ion channels, making them far more sensitive to changes in the membrane potential and thus more sensitive to mechanical stimuli. (eurekalert.org)
  • Various mechanical stimuli have been studied as in vitro model systems and have been shown to act through numerous signaling pathways to promote osteoblast activity. (sciencemag.org)
  • His new computer model takes slices of laser confocal microscopy images of cells and reconstructs a whole, virtual version of an individual cell, allowing researchers to evaluate how that cell will respond to different mechanical stimuli. (medindia.net)
  • Mechanical stimuli initiate adaptive signal transduction pathways, yet exceeding the cellular capacity to withstand physical stress results in death. (nature.com)
  • Mechanotransduction, or the conversion of mechanical forces into chemical and electrical signals, enables cellular responsiveness to physical stimuli. (nature.com)
  • This link between EM field exposures and mechanical vibration is consistent with the hypothesis that cells sense these stimuli via a similar mechanism involving counter ion displacement. (nih.gov)
  • The role of mechanical stimuli in airway remodelling has been hypothesized by Tschumperlin and Drazen more than a decade ago [ 2 ]. (hindawi.com)
  • The profibrotic environment produced by mechanical stress applied to the airway epithelial cells, in the absence of any inflammatory response, demonstrated the role of mechanical stimuli in airway remodelling [ 2 ]. (hindawi.com)
  • 1 2 The exact mechanism by which trabecular outflow tissues sense and respond to different types of mechanical stimuli (i.e., elevated intraocular pressure, circadian rhythm, ocular pulse, shear flow) is not well understood. (arvojournals.org)
  • The response of plants to mechanical stimuli can also be more discrete without any apparent overt changes. (biomedcentral.com)
  • This disparity has led to our hypothesis that chondrocyte proliferation is accelerated by mechanical stimuli above natural growth. (semanticscholar.org)
  • Increased endoplasmic reticulum stress in mouse osteocytes with aging alters Cox-2 response to mechanical stimuli. (surrey.ac.uk)
  • Aging reduces bone mass as well as the anabolic response of bone to mechanical stimuli, resulting in osteopenia. (surrey.ac.uk)
  • Endoplasmic reticulum (ER) stress impairs the response of myogenic cells to anabolic stimuli, and is involved in sarcopenia, but whether ER stress also contributes to osteopenia is unknown. (surrey.ac.uk)
  • Although mechanical stimuli are essential for the chondrocyte metabolism, excessive mechanical force contributes to the release of inflammatory mediators leading the cartilage destruction under the arthritic condition. (biomedcentral.com)
  • abstract = "In orthodontic treatment, the role of periodontal ligament is essential for the teeth to move within the alveolar process against the mechanical stress. (elsevier.com)
  • In this paper, experimental results on the residual mechanical stress generated during the different steps of the photolithography process of SU-8 thin films using different photo-initiator percentages are presented. (nsti.org)
  • The main aim is to investigate the causes and optimise the fabrication process in order to minimise the residual stresses. (nsti.org)
  • If local yielding occurs, the tension overload followed by unloading can provide beneficial compressive residual stresses at the hole edge. (highbeam.com)
  • For example cold working of holes is a technique widely used in aircraft structures to induce beneficial residual stresses around the hole. (highbeam.com)
  • This is achieved using a mandrel to apply radial pressure to the hole surface, causing local yielding in tension, so after unloading there are beneficial residual compressive stresses. (highbeam.com)
  • From a perspective of undertaking life assessment of airframe components, an understanding of how the residual stresses and yielded zone effect crack initiation or growth is important. (highbeam.com)
  • Various methods exist for investigating the effect on stress intensity factor, [K.sub.I], in the presence of residual stresses, including finite element methods and weight function methods. (highbeam.com)
  • Moreira et al (2008) used both FEA and the weight function technique to determine residual stress intensity for cracked cold expanded holes, (ie. (highbeam.com)
  • However heat treatment, on 1080 steel was used to induce tensile residual stresses in a notch in a compact tension specimen by Prawoto (2002). (highbeam.com)
  • The effects of residual stress in surface oxide layer and the interaction of stress field of neighboring TSVs are evaluated experimentally. (utexas.edu)
  • Residual stress state plays an important role in the fatigue life of welded structures. (diva-portal.org)
  • The effect can be beneficial or detrimental, depending on the nature of residual stresses. (diva-portal.org)
  • In this research work the behavior of compressive residual stresses induced in welded joints in high strength steels (HSS) by HFMI treatment has been investigated. (diva-portal.org)
  • Residual stresses have been measured at different cycles during fatigue testing using X-ray diffraction technique. (diva-portal.org)
  • It is observed that the induced residual stresses are quite stable with some relaxation in CA and VA loading. (diva-portal.org)
  • Relaxation of residual stresses is more obvious in VA tests. (diva-portal.org)
  • The MSIP technique creates compressive residual stresses at the inside surface of the welded joint while producing a slight permanent deformation of the pipe on one side of the weld. (asme.org)
  • This study uses two and three dimensional finite element models to evaluate the likely residual and operating stress profiles remaining after MSIP for typical dissimilar metal weld configurations, some of which are approved for leak-before-break (LBB) applications in pressurized water reactors. (asme.org)
  • The autofrettage process is used to induce advantageous residual hoop stresses into pressure vessels to enhance their fatigue lifetime. (asme.org)
  • The autofrettage process can be accomplished by applying hydraulic or mechanical pressure or by the pressure of powder gas to the bore of a thick cylinder to induce residual stresses. (asme.org)
  • When the mandrel is removed, the outer elastic portion compresses onto the inner plastic regime, thus causing compressive residual stresses. (asme.org)
  • A computer code based on finite element method is developed to analyze residual stresses including Bauschinger effect duly incorporating failure criteria such as von Mises and Tresca conditions. (asme.org)
  • Malik M, Rashid B, Khan M, Khushnood S. Modeling and Simulation of Residual Stresses in Mechanical Autofrettage. (asme.org)
  • This stress is called residual stress, because it remains in a solid material after the original cause of the stress has been removed. (wikipedia.org)
  • Residual stresses can occur through a variety of mechanisms including inelastic (plastic) deformations, temperature gradients (during thermal cycle), or structural changes (phase transformation). (wikipedia.org)
  • When the finished weldment cools, some areas cool and contract more than others, leaving residual stresses. (wikipedia.org)
  • In extreme cases, residual stress can cause structural failure. (wikipedia.org)
  • If the strain amplitudes were increased to a level sufficient to cause instability in the residual stresses, fatigue damage would occur. (wikipedia.org)
  • For most applications, conventional stress relief methodologies should be applied to components that require the reduction of residual stresses. (wikipedia.org)
  • Conversely compressive overloads followed by unloading can lead to potentially detrimental tensile stresses. (highbeam.com)
  • The purpose of this study was to assess the effects of compressive mechanical stress on interleukin-1 receptor (IL-1R) and matrix-degrading enzyme expression by three-dimensional (3D) cultured ATDC5 cells. (coxa.fi)
  • In addition, the implications of transient receptor potential vanilloid 4 (TRPV4) channel regulation in promoting effects of compressive mechanical loading were elucidated. (coxa.fi)
  • In 3D-cultured ATDC5 cells, ROS was induced by cyclic compressive loading stress. (coxa.fi)
  • The peak stress behavior of the most critical cases (thin fibrous cap and soft lipid core) at various degrees of stenosis was analyzed. (scirp.org)
  • Mechanical behavior in thin films continues to be a growing field of interest in the materials research community. (researchandmarkets.com)
  • This book addresses issues towards improving existing, as well as developing new, mechanical property characterization techniques such as more sensitive ultrasonic methods for elastic behavior determination and low-load indentation methods to investigate yield, creep, and fracture behavior. (researchandmarkets.com)
  • Understanding the mechanical behavior of free standing membranes is a point of common interest for MEMS structures, where a certain distance or deflection of a cantilever or membrane refers directly to the detectors performance. (fraunhofer.de)
  • The mechanisms by which signaling pathways that pattern the embryo impact on the distribution of mechanical stress, and how this determines cell behavior have been the subject of intense focus recently ( Heisenberg and Bellaïche, 2013 ). (biologists.org)
  • In this context, measuring patterns of mechanical stress in developing tissues and assessing their impact on cell behavior is one of the first steps necessary to understand morphogenetic processes. (biologists.org)
  • 10 Although the mechanism(s) responsible for the effect of cyclic biomechanical stress on trabecular tissues is not well understood, contractility has been suggested to play an important role in endothelial cell behavior generally and in outflow facility specifically. (arvojournals.org)
  • We characterized EMPs (annexin V and CD31 immunoreactivity) produced from human lung ECs exposed to physiologic or pathologic mechanical stress (5 or 18% cyclic stretch [CS]) or to endotoxin (LPS). (nih.gov)
  • Here, we show that mechanical shear acts as a cue for surface adhesion and activates cyclic-di-GMP signaling. (aps.org)
  • The aim of the present study was to test the hypothesis that trabecular meshwork (TM) cell contractility mediates outflow facility responses to cyclic mechanical stress. (arvojournals.org)
  • Human TM monolayers respond to cyclic stress by increasing pressure during the pulsation period by 121.30±9.6% (n=8, p=0.002). (arvojournals.org)
  • Human TM cell monolayers respond to cyclic mechanical stress by decreasing hydraulic conductivity. (arvojournals.org)
  • The purpose of the present study was to examine responses of trabecular meshwork (TM) cells to cyclic biomechanical stress in the presence and absence of compounds known to affect cell contractility. (arvojournals.org)
  • Human TM cells respond to cyclic mechanical stress by increasing intrachamber pressure. (arvojournals.org)
  • Publications] Yasu N.: 'Effect of cyclic mechanical stress on attachment and spreading of human periodontal ligament fibroblasts' Bull of Kanagawa Dent Col.20(1). (nii.ac.jp)
  • We examined the effects of cyclic mechanical stress on the gene expression profile of rat chondrocytes, and tested the in vitro effects of recombinant IL-4. (biomedcentral.com)
  • Cyclic mechanical stress was applied on the cultured chondrocytes for 24 hours using Flexercell strain unit (Flexcell International Co., Hillsboro, NC, USA) with 0.5 Hz, 7% elongation, with or without treatment by recombinant IL-4. (biomedcentral.com)
  • These findings suggest that mechanical stress-activated JNK and p38 induce cytokine cross-talks between osteoblasts and bone marrow-derived monocytes and macrophages, which may play key roles in bone remodeling. (springer.com)
  • In conclusion, we show that syndecan-4 activates calcineurin-NFAT signaling in mechanically stressed cardiac fibroblasts and that this signaling pathway could induce the differentiation into myofibroblasts. (ahajournals.org)
  • In contrast, random, inconstant mechanical vibration did not induce protection against subsequent UV exposure. (nih.gov)
  • His research is driven by the theory that fat cells, like bone or muscle cells, are influenced by mechanical loads, defined as the amount of force or deformation placed on a particular area occupied by cells. (medindia.net)
  • Distinct from chronic mechanical loading or direct tissue laceration, blunt force trauma involves the transient application of intense force that causes membrane deformation, organelle rearrangement, and disrupted intercellular interactions without necessarily compromising cellular or tissue integrity. (nature.com)
  • Strength and plasticity of materials of various classes under three-dimensional (triaxial) stress, and three-dimensional compression in particular is discussed which makes it possible to specify and choose with a higher degree of justification the models of deformation and the criteria of strength of quasti-brittle materials used in practical calculations. (begellhouse.com)
  • As a result, it is important to study fundamental issues involved in film-substrate adhesion, the development of intrinsic stresses and the mechanisms of plastic deformation, strain relaxation, and fracture in thin films. (researchandmarkets.com)
  • Mechanical deformation of vessel wall and shear stress determine the basal release of endothelium-derived relaxing factor in the intact rabbit coronary vascular bed. (ahajournals.org)
  • Deformation tests under deviatoric stress with constant confining pressure and temperature show that, for all the lithofacies, the permeability decreases continuously. (lyellcollection.org)
  • In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. (wikipedia.org)
  • Any strain (deformation) of a solid material generates an internal elastic stress, analogous to the reaction force of a spring, that tends to restore the material to its original non-deformed state. (wikipedia.org)
  • However, if the deformation changes gradually with time, even in fluids there will usually be some viscous stress, opposing that change. (wikipedia.org)
  • Significant stress may exist even when deformation is negligible or non-existent (a common assumption when modeling the flow of water). (wikipedia.org)
  • The relation between mechanical stress, deformation, and the rate of change of deformation can be quite complicated, although a linear approximation may be adequate in practice if the quantities are sufficiently small. (wikipedia.org)
  • Stress that exceeds certain strength limits of the material will result in permanent deformation (such as plastic flow, fracture, cavitation) or even change its crystal structure and chemical composition. (wikipedia.org)
  • Unlike the common thinking of the period that considered airway remodelling to be consequent to the inflammatory milieu of the asthmatic setting, the authors indicated cellular stresses in the constricted airway, combined with a responsive cell population, as a plausible explanation of the mechanically responsive nature of the airway. (hindawi.com)
  • Finite element modeling data suggest that mechanically loaded muscles in vivo may experience not only tensile strain but also shear stress. (uva.nl)
  • We used a quantitative approach to analyze the strains and stresses of cells of the wing pouch, and found a global pattern of stress whereby cells in the periphery of the tissue are mechanically stretched and cells in the center are compressed. (biologists.org)
  • The specific objectives were (i) to identify actively transcribed genes through transcriptome analysis, (ii) to identify morphological, biochemical, and transcriptional changes induced by a non-wounding mechanical stress, and (iii) to determine the level of resistance in mechanically stressed A. koa. (hawaii.edu)
  • It forms the physical framework that interconnects most cells and has to bear the tensile stresses within the tissue. (nih.gov)
  • Tissue remodeling often reflects alterations in local mechanical conditions and manifests as an integrated response among the different cell types that share, and thus cooperatively manage, an extracellular matrix. (mendeley.com)
  • We show that (i) mechanical stress can be communicated from stressed to unstressed cells to elicit a remodeling response, and (ii) the integrated response of two cell types to mechanical stress mimics key features of airway remodeling seen in asthma: namely, an increase in production of fibronectin, collagen types III and V, and matrix metalloproteinase type 9 (MMP-9) (relative to tissue inhibitor of metalloproteinase-1, TIMP-1). (mendeley.com)
  • These observations provide a paradigm to use in understanding the management of mechanical forces on the tissue level. (mendeley.com)
  • Stress, FAK activation, and branching were all altered by manipulating cellular contractility, matrix stiffness, intercellular cohesion and tissue geometry. (nih.gov)
  • Since normal articular cartilage is always subjected to mechanical stress in daily activities, mechanical stress has attracted much attention as fourth key factor in cartilage tissue engineering. (ebscohost.com)
  • However, the real impact of mechanical stress on cartilage tissue engineering is farfrom complete understanding. (ebscohost.com)
  • In this review, we summarize the accumulating knowledge of the effect of mechanical stress on cartilage tissue engineering and discuss about the challenges for the future. (ebscohost.com)
  • In this talk, we will discuss how tissues respond to mechanical perturbations, such as stretching or wounding, by altering their actomyosin contractile structures, to change tissue dynamics, and thus preserve tissue shape and patterning. (cam.ac.uk)
  • How these local stresses add up or dissipate as the tissue grows is an unanswered question. (biologists.org)
  • Mechanical interactions differ from biochemical intercellular communication by their non-locality: mechanical perturbation spreads over large distances in a tissue owing to the transmission of tensions through tissue connectedness. (biologists.org)
  • Growth is a mechanical process: each time a cell grows, new matter is being added within the tissue. (biologists.org)
  • Indeed, if the tissue surrounding a growing cell cannot rearrange itself, it will resist this local perturbation, resulting in a local mechanical stress that, in return, constrains the dividing cell. (biologists.org)
  • As more divisions proceed, these local stresses may accumulate and give rise to a macroscopic stress that will affect tissue shape. (biologists.org)
  • however, little is known about the influence of dynamic stress on tissue regulation. (arvojournals.org)
  • In this study, we have further explored ROS and resistance to B. cinerea in leaves of A. thaliana exposed to a soft form of mechanical stimulation without overt tissue damage. (biomedcentral.com)
  • They generate enormous mechanical forces that also affect the cells within the muscle tissue. (idw-online.de)
  • Jan Lammerding, Professor for Cellular Mechanobiology at Cornell University in America, develops fluorescent 'reporter' cells that can indicate mechanical damage in the cell tissue. (idw-online.de)
  • 14] F.-J. Wortmann and H. Zahn, The stress/strain curve of α-keratin fibres and the structure of the intermediate filament,Textile Research Journal, 64(12), 1994, 737-743. (actapress.com)
  • And these proposed equations were applied into stress-strain relation which was developed by previous research. (hindawi.com)
  • Those cells were loaded with intermittent mechanical strain at 5 or 10% elongation for 10 second with the resting for 10 or 50 second using the flexible bottomed culture plates and vacuum system in the presence or absence of retinoic acid (RA), 1,25 dihydroxy vitamin D_3 (D_3) or both of them. (nii.ac.jp)
  • Contribution of PTHrP to mechanical strain-induced fibrochondrogenic differentiation in entheses of Achilles tendon of miniature pigs. (semanticscholar.org)
  • Traditionally, the effect of intermittency has not been taken into account in the shear problem and the theory of isotropic turbulence introduced by Kolmogorov (1941) based on average values of the rate of kinetic energy dissipation, velocity fluctuactions, rates of strain, turbulent stresses etc. has been applied. (asme.org)
  • Strain inside a material may arise by various mechanisms, such as stress as applied by external forces to the bulk material (like gravity) or to its surface (like contact forces, external pressure, or friction). (wikipedia.org)
  • In general, the strain amplitudes achieved during vibratory stress relief are too low to exceed the critical stress required to activate mechanical relaxation during the induced low amplitude high cycle fatigue excitation of the transducer vibrations. (wikipedia.org)
  • However, whether shear stress affects biological pathways involved in muscle fiber size adaptation in response to mechanical loading is unknown. (uva.nl)
  • Therefore, our aim was twofold: (1) to determine whether shear stress affects growth factor expression and nitric oxide (NO) production by myotubes, and (2) to explore the mechanism by which shear stress may affect myotubes in vitro. (uva.nl)
  • Shear stress enhanced NO production in a dose-dependent manner, while CS induced no quantifiable increase in NO production. (uva.nl)
  • Glycocalyx degradation and blocking of SACs ablated the shear stress-stimulated NO production. (uva.nl)
  • In conclusion, shear stress activates signaling pathways involved in muscle fiber size adaptation in myotubes, likely via membrane-bound mechanoreceptors. (uva.nl)
  • These results suggest that shear stress exerted on myofiber extracellular matrix plays an important role in mechanotransduction in muscle. (uva.nl)
  • Increasing shear stress by a strong vasoconstriction (1 nM endothelin-1) at constant flow was also accompanied by a 2.5-fold increase in platelet cGMP content. (ahajournals.org)
  • This article discusses the problem of the turbulent " shear " in biotechnology including the effect of the shear stress on particles (cells, flocs, cells immobilized on microcarriers). (asme.org)
  • Shear stress was continuously increased until peak systole and high turbulent stress was observed at the orifice of the central channel and also around the occluder trailing tips. (vivitrolabs.com)
  • citation needed] The understanding of stress in liquids started with Newton, who provided a differential formula for friction forces (shear stress) in parallel laminar flow. (wikipedia.org)
  • How fat cells respond to mechanical loads can be studied now through a new method developed by researchers at the Tel Aviv University. (medindia.net)
  • In contrast, very little is known about how prokaryotes may respond to mechanical inputs. (aps.org)
  • Whereas the growth of the cranial base cartilage is thought to be regulated solely by genes, epiphyseal growth plates are known to respond to mechanical stresses. (semanticscholar.org)
  • The state of the art shows a substantial knowledge deficit about the influence of the volumetric grinding wheel composition and the resulting grinding wheel topography on the thermo-mechanical stress collective acting on the workpiece external zone. (mdpi.com)
  • Therefore, the aim of the current research is an empirical-analytical model for the prediction of the thermo-mechanical stress collective as a function of the grinding wheel topography. (mdpi.com)
  • The obtained results are summarized and are used to explain the thermo-mechanical stress collective as a function of the grinding wheel topography. (mdpi.com)
  • This research demonstrates that the assessment approach can be successfully applied to the design of a ball grid array package with a more accurate assessment model for fatigue life under mechanical loading. (smta.org)
  • Finally, the primary focus of this research is the issue of how accurately the assessment methodology is able to estimate the fatigue life of the ball grid array solder joint under mechanical loading. (smta.org)
  • The UTS/3.5 requirement may be complete in a practical sense , in that perhaps no available pressure vessel steel will have a low cycle fatigue failure when the applied stress is under UTS/3.5. (eng-tips.com)
  • High frequency mechanical impact (HFMI) treatment is a postweld fatigue improvement technique for welded joints. (diva-portal.org)
  • Therefore, in this work the multiaxial fatigue strength of welded joints failing at the weld root was assessed using experiments and various nominal and local stress based approaches. (diva-portal.org)
  • Butt welded joints with different weld seam inclinations with respect to applied uniaxial loading were designed to assess the root fatigue strength in higher multiaxial stress ratio regime. (diva-portal.org)
  • Stress and fatigue testing are common test methods in mechanical engineering and materials science, but provide limited information on complex structures. (flir.com)
  • Normal stress is imposed on bronchial epithelial cells in the presence of unstimulated lung fibroblasts. (mendeley.com)
  • Mechanical stress caused by pressure overload of the heart leads to differentiation of cardiac fibroblasts into myofibroblasts characterized by the ability to contract and an excessive production of extracellular matrix. (ahajournals.org)
  • Cell Biological Study on the Response Against Mechanical Stress on Periodontal Ligament Fibroblasts Derived from Human Deciduous Teeth. (nii.ac.jp)
  • however, it is not clear how fibroblasts sense and transmit the mechanical signal(s) that promote differentiation into myofibroblasts. (jci.org)
  • Here, we hypothesized that syndecan-4 activates NFAT in response to mechanical stress leading to myofibroblast differentiation. (ahajournals.org)
  • We previously reported that mechanical stress, the most important stimulus for cardiac hypertrophy, activates the AT1 receptor through an AngII-independent mechanism, and that this activation is inhibited by an inverse agonist candesartan. (ahajournals.org)
  • However, it remains unclear how mechanical stress activates AT1 receptor and how candesartan exerts inverse agonism. (ahajournals.org)
  • By serial studies using substituted cysteine accessibility mapping, we demonstrated that mechanical stress directly activates AT1 receptor by changing the conformation of AT1 receptor. (ahajournals.org)
  • The local distribution of near-surface stress in Si has been measured, in comparison with stress analysis of the TSV structure based on a semi-analytic approach and finite element analysis. (utexas.edu)
  • Stress concentration factors have been calculated using finite element analysis (FEA). (diva-portal.org)
  • Our findings suggest that local stresses applied to integrins propagate from the tensed actin cytoskeleton to the LINC complex and then through laminachromatin interactions to directly stretch chromatin and upregulate transcription. (yinyoga.com)
  • The finite element models of lumbar motion segments were useful in analyzing internal stresses, given segment geometry, material properties and applied loads. (cdc.gov)
  • It was found that the major parameters that influence the generation of internal stresses were the exposure time, the post-baking temperature and time and the concentration of the photo-initiator used (Cyracure UVI). (nsti.org)
  • The molecular mechanisms for stress-induced myofibroblast differentiation are likely to involve stress-sensing molecules located in focal adhesions, such as the transmembrane proteoglycan syndecan-4. (ahajournals.org)
  • We hypothesize that inflammation and mechanical stress stimulate osteogenic differentiation of human aortic valve interstitial cells (VICs) and this may depend on the side of the leaflet. (frontiersin.org)
  • We conclude that mechanical stress may play an important role in the cell proliferation and differentiation, and also could regulate the production of extracellular matrix such as CASFs. (nii.ac.jp)
  • The effects of mechanical stress on cell growth and differentiation were studied on HPLF-Y and HPLF in culture. (nii.ac.jp)
  • Shaik Rahaman and colleagues at the Cleveland Clinic demonstrated that the transient receptor potential vanilloid 4 (TRPV4) channel mediates mechanical signals that trigger myofibroblast differentiation. (jci.org)
  • Together, these data reveal that mechanical stress-dependent modulation of TRPV4 activity mediates myofibroblast differentiation and suggest TRPV4 inhibition as potential therapeutic strategy for IPF. (jci.org)
  • These successive deformations exert mechanical pressures on the embryo. (innovations-report.com)
  • In physical terms, stress is the measure of the internal forces within a continuous material where particles standing adjacent to each other exert these forces on one other. (scirp.org)
  • Using these, it should be possible to exert targeted mechanical forces on cells. (idw-online.de)
  • Cells probably use this ability to protect themselves from mechanical overstimulation, as reported in an article published in the journal Nature Communications initiated and carried out by Dr. Mirko Moroni, the lead author, and other members of Lewin's research group. (eurekalert.org)
  • The mechanism seems to protect blood cells from the mechanical stress they would otherwise be permanently exposed to as they travel through narrow blood vessels. (eurekalert.org)
  • Here we examine how two different cell types, one that undergoes the stress and the other that primarily remodels the matrix, might communicate a mechanical stress by using airway cells as a representative in vitro system. (mendeley.com)
  • When mechanical pressure is applied to the embryo, ß catenin enters the cell nucleus (on right), whereas to perform its role as an "adhesive" between cells it must be on the cell surface. (innovations-report.com)
  • But on applying mechanical pressure to the Drosophila embryo, Emmanuel Farge noted that the Twist gene was then expressed in all the embryo's cells. (innovations-report.com)
  • Henceforth it will be necessary to take into account the mechanical sensitivity of living cells. (innovations-report.com)
  • By recreating the structure of fat cells using a newly-developed computer method, Prof. Gefen and his team of researchers can determine how much mechanical load can be tolerated by fat cells, and at what point the cells will begin to disintegrate. (medindia.net)
  • According to Prof. Gefen, applying mechanical loads on tissues can affect many different cells within our bodies. (medindia.net)
  • He believes that, much like bone or muscle cells, fat cells are also affected by mechanical loads. (medindia.net)
  • After assembling their "virtual" fat cells, Prof. Gefen and his group found that fat cells or lipids have a point where mechanical loads can disintegrate them, as well as a point at which they are able to resist disintegration. (medindia.net)
  • Cells are constantly adjusting to the mechanical properties of their surroundings, operating a complex mechanochemical feedback, which hinges on mechanotransduction mechanisms. (mdpi.com)
  • Our tissues are made up of cell, so we also stress the cells. (yinyoga.com)
  • This study shows how that stress on the cells can affect gene expression: turning on or off certain genes depending upon the direction and intensity of the stress. (yinyoga.com)
  • Cells and tissues can be protected against a potentially lethal stress by first exposing them to a brief dose of the same or different stress. (nih.gov)
  • The age-effect is reasonable, since younger cells, which are actively shaping their cell walls, are more vulnerable to altered mechanical stresses while in leaves older than 19 DAS, the walls are more robust and therefore can sustain the applied forces. (nih.gov)
  • This process may be triggered by several factors including inflammation, mechanical stress or interaction of cells with certain components of extracellular matrix. (frontiersin.org)
  • It is well-known that eukaryotic cells can sense and respond to many types of mechanical inputs. (aps.org)
  • The effects of dynamic mechanical stresses on the arachidonic acid (AA) metabolism of human platelets and on the cell growth properties of murine tumor cells were studied. (rice.edu)
  • The cells were stressed by suspending them in laminar simple shear flows. (rice.edu)
  • Stress effects on tumor cells were studied using high and low metastatic sub-lines of the B16 melanoma and the RAW117 large cell lymphoma. (rice.edu)
  • The cells were stressed at 0, 450 and 900 dynes/cm$\sp2$ at 37$\sp\circ$C for 5 min. (rice.edu)
  • The results could by modeled assuming that a subpopulation of stressed cells was lethally damaged and ultimately died while a second group of stressed cells were only sublethally damaged and grew normally after a brief lag-time. (rice.edu)
  • The data indicate that there was not much difference in the damage levels between high and low metastatic sub-lines and that a considerable fraction of stressed cells were not lethally damaged even at bulk shear stresses as high as 900 dynes/cm$\sp2$ for 5 min. (rice.edu)
  • Although the stresses applied were higher than normally seen in vivo, the results are in contrast to the accepted view that mechanical stresses developed in the circulation directly cause the destruction of most of the tumor cells during blood-borne metastasis and that highly metastatic cells can resist these stresses more effectively than poorly metastatic cells. (rice.edu)
  • Mechanical stress, the internal distribution of forces within cells and tissues, is what make cells move, change shape, or exchange neighbors. (biologists.org)
  • The opposite situation is that of loosely connected cells, which can make way for growth, resulting in an effective fluid flow where no mechanical stress is generated, as in cultured multicellular spheroids. (biologists.org)
  • Although mechanical stress appeared to have no effect, Y27632 decreased phosphorylated myosin light chain, filamentous/globular actin ratio, and stress fiber formation in TM cells. (arvojournals.org)
  • Mechanical forces exerted on cells impose stress on the plasma membrane. (semanticscholar.org)
  • Cells sense this stress and elicit a mechanoelectric transduction cascade that initiates compensatory mechanisms. (semanticscholar.org)
  • Effects of transient receptor potential canonical 1 (TRPC1) on the mechanical stretch-induced expression of airway remodeling-associated factors in human bronchial epithelioid cells. (semanticscholar.org)
  • In isolated adherent cells, the orientation of mitotic spindles is sensitive to interphase cell shape and the direction of extrinsic mechanical forces. (pnas.org)
  • Among the bone cells, osteocytes act as a major role in bone remodelling during orthodontic tooth movement against mechanical stress. (elsevier.com)
  • however, is not clear how these cells sense and transmit mechanical signals. (jci.org)
  • A research project by scientists at Kiel University (CAU), the University of Münster (WWU) and Cornell University, USA, is investigating how cells have learned to adapt to mechanical stress to avoid damage during the course of evolution. (idw-online.de)
  • Mechanical pressure on cells also plays a role in illnesses: genetic mutations that alter the mechanical load-bearing capacity of cells can, for example, lead to muscle weakness (muscular dystrophy) and heart disease. (idw-online.de)
  • The fact that cells react to mechanical influences is nothing new in research. (idw-online.de)
  • At the interface between biology and engineering, mechanobiology investigates the mechanical properties of cells and the physical forces at work there. (idw-online.de)
  • In addition to the cellular adaptation strategies that have possibly emerged during the course of evolution, they are also interested in how the mechanical forces in single-celled and multicellular organisms differ and how they are transferred from the surface of the cells to their nucleus. (idw-online.de)
  • Mechanical stress on hearts triggers β-arrestin-dependent cell survival signaling through the angiotensin receptor. (sciencemag.org)
  • This reaction to soft mechanical stress (SMS) was fully independent of jasmonate (JA signaling). (biomedcentral.com)
  • This is the first time that a mechanical constraint has been shown to influence the genetic control of the development of Drosophila embryo. (innovations-report.com)
  • This aim of the present narrative review was to illustrate the current evidence on the importance of mechanical stress in the pathophysiology of lung diseases with a particular focus on chronic obstructive pulmonary disease (COPD) and to discuss how this may influence pharmacological treatment strategies. (hindawi.com)
  • This narrative review describes the current evidence on the importance of mechanical stress in the pathophysiology of lung diseases and chronic obstructive pulmonary disease (COPD) and discusses how this can influence treatment selection. (hindawi.com)
  • Richardson, P., Davies, M. and Born, G. (1989) Influence of plaque configuration and stress distribution of coronary atherosclerotic plaques. (scirp.org)
  • This is the first handbook containing extensive information on the influence of the stress on the material properties. (begellhouse.com)
  • The influence of the stress mode on the crack growth resistance has been covered in detail. (begellhouse.com)
  • The influence of mechanical forces has undergone minimal investigation to date: multicellular organisms are subject to significantly greater stress than single-celled organisms. (idw-online.de)
  • However, the mechanisms underlying channel activation in response to mechanical stress remain incompletely understood. (semanticscholar.org)
  • It is found out, that the mechanical stress of the investigated material systems decreases up to two orders of magnitude due to relaxation between material deposition and releasing membranes from substrate. (fraunhofer.de)
  • We show that divisions orient with the long cell axis rather than with the stress direction, and show how oriented divisions contribute to the restoration of cell packing and stress relaxation. (pnas.org)
  • To do this, we used suspended monolayers devoid of ECM, where divisions become oriented following a stretch, allowing the regulation and function of epithelial division orientation in stress relaxation to be characterized. (pnas.org)
  • Emmanuel Farge, a researcher at the Institut Curie, lecturer at the Paris VII University, and member of the Institut Universitaire de France, has just shown that mechanical pressure applied to a fly embryo influences the expression of its developmental genes. (innovations-report.com)
  • b catenin could be the link between mechanical pressure and genes. (innovations-report.com)
  • Inflammation and mechanical stress trigger expression of osteogenic genes in VICs in a side-specific manner, while inhibiting the myofibroblastic pathway. (frontiersin.org)
  • The results showed that the stressed plants had stronger antifungal activities and were 'primed' for defense with enhanced expression levels of defense-related genes following fungal inoculation. (hawaii.edu)
  • This was preceded by a rapid change in calcium concentration and a release of ROS, accompanied by changes in cuticle permeability, induction of the expression of genes typically associated with mechanical stress and release of biologically active diffusates from the surface. (biomedcentral.com)
  • The cDNA microarray analysis revealed that, of 1080 genes, 37 genes were upregulated and 46 genes were downregulated after mechanical stress. (biomedcentral.com)
  • Space components need a ground characterization based on several solicitations, including mechanical and thermal stress, before their final qualification. (springer.com)
  • Hands on experience with mechanical characterization methods and analysis . (indeed.com)
  • at 25$\sp\circ$C. The stress stimulated AA metabolism above basal levels. (rice.edu)
  • This result indicates that the physical stresses and chemical agonists (like thrombin) affect platelet AA metabolism differently. (rice.edu)
  • The new and improved Second Edition contains additional chapters on APDL Math and APDL in ANSYS Mechanical. (padtinc.com)
  • This post shows how Ansys Mechanical does it and offers an alternative that is considered more accurate for some cases. (padtinc.com)
  • Acute lung injury (ALI) results from infectious challenges and from pathologic lung distention produced by excessive tidal volume delivered during mechanical ventilation (ventilator-induced lung injury [VILI]) and is characterized by extensive alveolar and vascular dysfunction. (nih.gov)
  • Here, we review recent advances demonstrating that mechanical stress emanating from the cytoskeleton can activate pathways in the nucleus which eventually impact both its structure and the transcriptional machinery. (mdpi.com)
  • However, in addition to the aforementioned changes, it is possible that oxidative damage induces critical changes to the erythrocyte cytoskeleton and corresponding bio-mechanical and nano-structural properties of the red cell membrane. (mit.edu)
  • Elastic and viscous stresses are usually combined under the name mechanical stress. (wikipedia.org)
  • More interestingly, we succeeded in the demonstration of novel mechanical stress sensing by the elastic CLC films of crosslinked HPC derivatives, leading to the visualization of external mechanical stress as the changes in Bragg reflection color. (or.jp)
  • However, the line seems to be related to Kirsch's elastic stress distribution since the value of the stress concentration factor approaches 3 when the ratio r/d approaches zero. (stackexchange.com)
  • In liquids and gases, only deformations that change the volume generate persistent elastic stress. (wikipedia.org)
  • Here, we examine the various types of stress and the sequential response of transduction pathways that result in changes in gene expression and the ensuing proliferation of osteoblasts. (sciencemag.org)
  • In the nematode C. elegans , we have developed a method to study cellular degeneration in response to mechanical stress caused by blunt force trauma. (nature.com)
  • VHP-1 regulates the transcriptional response to mechanical stress and is itself attenuated by KGB-1-mediated inactivation of a deubiquitinase, MATH-33, and proteasomal degradation. (nature.com)
  • Together, we describe an uncharacterized stress response pathway in C. elegans and identify transcriptional and post-translational components comprising a feedback loop on Jun kinase and phosphatase activity. (nature.com)
  • To date, perhaps the best understood molecular response to mechanical stressors has been described in the heart. (nature.com)
  • Transmembrane (TM) VII of AT1 receptor showed a counterclockwise rotation and shift into the ligand-binding pocket in response to mechanical stretch, and candesartan suppressed this helical movement induced by stretch. (ahajournals.org)
  • Skeletal muscle fibers have the ability to increase their size in response to a mechanical overload. (uva.nl)
  • The nuclei of oocytes in primordial follicles rotated in response to the mechanical stress. (sciencemag.org)
  • One of the most valuable results that can come from a harmonic response analysis is the predicted alternating stresses in the part. (padtinc.com)
  • Little is known of the dynamics of plant cell wall matrix polysaccharides in response to the impact of mechanical stress on plant organs. (whiterose.ac.uk)
  • The LM13 linear arabinan epitope is specifically detected in epidermal cell walls of the younger, flexible regions of inflorescence stems and increases in abundance at the base of inflorescence stems in response to an imposed mechanical stress. (whiterose.ac.uk)
  • These data demonstrate that there are obvious differences between HPLF-Y and HPLF in terms of the response to RA or mechanical stress. (nii.ac.jp)
  • The stress response involves a reorganization of the microtubule pattern within 3 hours of applied external force. (biomedcentral.com)
  • This response occurs in an age-dependent manner whereby only the younger leaves up to 19 days after sowing (DAS) are susceptible to the stress. (biomedcentral.com)
  • Therefore, we tested whether ER stress exists in bones of aged mice, and whether this impairs the osteocyte response to mechanical stimulation. (surrey.ac.uk)
  • Since ER stress altered the response of osteocytes to mechanical loading, it could be a novel factor contributing to osteopenia. (surrey.ac.uk)
  • Humans could not have survived without such a powerful response to stress . (webmd.com)
  • Mechanical overload applied on the articular cartilage may play an important role in the pathogenesis of osteoarthritis. (coxa.fi)
  • Interestingly, a weak structural support such as a soft lipid pool beneath the fibrous cap allowed for the hemodynamic pressure gradient forces to displace the fibrous cap in the direction of the flow, resulting in higher strains and thus higher mechanical stresses in the upstream portion of the plaque cap, potentially increasing the risk of cap rupture. (scirp.org)
  • Mechanical stress-induced apoptosis has been proposed as the mechanism underpinning DCM in lamin A/C-deficient hearts, but supporting in vivo evidence has been lacking. (garvan.org.au)
  • Chondrocyte proliferation of the cranial base cartilage upon in vivo mechanical stresses. (semanticscholar.org)
  • article{Wang2002ChondrocytePO, title={Chondrocyte proliferation of the cranial base cartilage upon in vivo mechanical stresses. (semanticscholar.org)
  • These results suggested the possible role of IL-4 in the control of mechanical stress-induced inflammatory mediators in vitro and in vivo . (biomedcentral.com)
  • In all this, bone must be as lightweight as possible to decrease the overall body mass yet have the mechanical ability to endure stresses whenever a force is loaded upon them. (scirp.org)
  • however, most modern portable electronic products used in automobiles, personal digital assistants (PDA), and aircraft have to endure extreme environments that involve not only thermal but also mechanical loading conditions. (smta.org)
  • To endure all these stresses, crystalline arrays of cellulose microfibrils are deposited into the wall. (biomedcentral.com)
  • It therefore seems that mechanical pressure exerted on the embryo perturbs essential cellular processes. (innovations-report.com)
  • (A) FEM mesh, showing the cellular (epithelium) and ECM (matrix) portions of the stress model. (nih.gov)
  • 10] A.N. Parbhu, W.G. Bryson, and R. Lal, Disulfide bonds in theouter layer of keratin fibres confer higher mechanical rigidity:Correlative nano-indentation and elasticity measurement withan AFM, Biochemistry, 38, 1999, 11755-11761. (actapress.com)
  • Second, the limitation of conventional Raman measurement is discussed, and two different kinds of innovative Raman measurements have been developed and employed to study the normal stress components separately by taking advantages of different laser polarization configuration. (utexas.edu)
  • Nevertheless, the permeability changes observed during these tests seem to be directly connected to the nature and structure of the material sustains under changes of temperature and stress. (lyellcollection.org)
  • Direct the use of CAEPIPE piping system stress analysis software to determine weight, pressure, temperature, & earthquake. (indeed.com)
  • Direct the use of appropriate piping system stress analysis software (Autopipe, Caesar or similar)to determine weight, pressure, temperature, & earthquake. (indeed.com)
  • Stress may also be imposed on a material without the application of net forces, for example by changes in temperature or chemical composition, or by external electromagnetic fields (as in piezoelectric and magnetostrictive materials). (wikipedia.org)
  • The particle image velocimetry technique was used to study the shear field across a transparent mechanical heart valve model in one cardiac cycle. (vivitrolabs.com)
  • Here, we show that JNK and p38 [two stress-responsible mitogen-activated protein kinases (MAPKs)] are activated via ASK1 (a stress-responsible MAPK kinase) in mechanical stretch loaded MC3T3-E1 preosteoblasts. (springer.com)
  • Mechanical stretch of VICs cultured on collagen augmented the effect of lipopolysaccharide. (frontiersin.org)
  • In conclusion, ARBs with potent inverse agonism prevent the conformational change of AT1 receptor via tight drug-receptor interactions, and thereby, inhibit receptor activation induced by not only AngII but also mechanical stretch. (ahajournals.org)
  • Mechanical stress in Arabidopsis leaves orients microtubules in a 'continuous' supracellular pattern. (nih.gov)
  • Confocal microscopy examination of transgenic plants bearing GFP-tagged TUA6 proteins led to the observation that application of an additional mechanical pressure on growing Arabidopsis leaves triggers an excessive bundling of microtubules within the individual cell. (nih.gov)
  • The capacity of the imposition of a mechanical stress (periodic brushing) to reduce the height of the inflorescence stem of Arabidopsis thaliana seedlings has been used to study the role of pectic arabinans in the mechanical properties and stress responsiveness of a plant organ. (whiterose.ac.uk)
  • Arabidopsis can detect and convert gentle forms of mechanical stimulation into a strong activation of defense against the virulent fungus B. cinerea . (biomedcentral.com)
  • In this paper, RF MEMS switches designed for redundancy logic have been extensively measured with promising results in terms of thermal and mechanical cycles. (springer.com)
  • This paper presents a reference design flow for solving the electrical, thermal and mechanical challenges of a printed circuit board (PCB) using simulation tools from ANSYS. (theengineer.co.uk)
  • The design flow details nearly all aspects of the modeling technique from studying electrical connections in a schematic and setting up the PCB to analyzing the electrical, thermal and mechanical characteristics of the board - all using ANSYS tools. (theengineer.co.uk)
  • By taking advantage of all the features and strengths of each ANSYS product, you can combine them to create a multiphysics solution for all the electrical, thermal and mechanical problems of a PCB. (theengineer.co.uk)
  • However, due to the large CTE mismatch between Silicon and Copper, thermal stresses are induced by various thermal histories from the process, and they have caused serious concerns regarding the thermal-mechanical reliability. (utexas.edu)
  • In this thesis, we mainly used Micro- Raman spectroscopy characterized the thermal-mechanical stress distribution at both near surface and cross-section of Si around TSV. (utexas.edu)
  • Thermal stress mapping provides thousands of stress measurements simultaneously, even on geometrically complex components. (flir.com)
  • Vibratory Stress Relief, often abbreviated VSR, is a non-thermal stress relief method used by the metal working industry to enhance the dimensional stability and mechanical integrity of castings, forgings, and welded components, chiefly for two categories of these metal workpieces: Precision components, which are machined or aligned to tight dimensional or geometric tolerances. (wikipedia.org)
  • The different types of mechanical demands in daily activities are sifted through and any misconceptions found fallible in literature are refined. (scirp.org)
  • Mechanical stress profiles of tubules with increasing contractility: prestress (p t ) that yields prestrain (ε 0 ) of (A) 0.2 % (B) 0.6 % (C) 1% and (D) combined stress profiles. (nih.gov)
  • Significantly, the Twist gene is not expressed in mutant embryos in which this mechanical pressure is absent. (innovations-report.com)
  • We report here that constant mechanical vibration pre-conditions chick embryos, protecting them during subsequent stress from hypoxia or UV light exposure. (nih.gov)
  • As a second set of experiments, embryos were vibrated and then exposed to UV light stress. (nih.gov)
  • Ultimately, mechanical forces shape embryos. (biologists.org)
  • Stress triggers a chemical tsunami in your body. (webmd.com)
  • Mechanical signal transmission is significantly delayed by stress fiber material viscosity, while cytosolic damping becomes important only for longer stress fibers. (biomedsearch.com)
  • For simple networks of stress fibers, mechanical signals are transmitted rapidly to the nucleus when the fibers are oriented largely orthogonal to the applied force, whereas the presence of fibers parallel to the applied force slows down mechanical signal transmission significantly. (biomedsearch.com)
  • The mechanical stress levels are significantly increased within the fibrous cap structure at the upstream side of the plaque. (scirp.org)
  • Therefore, it is important to investigate each process step in relation to the internal stress formulation during the SU-8 fabrication process in order to attenuate stress cracking and distortions without significantly affecting lithography. (nsti.org)
  • the stressed plants had significantly reduced stem length, whereas they had significantly increased stem diameter, and anthocyanin and lignin contents. (hawaii.edu)
  • Consistently, the stressed plants had a significantly higher survival rate following a 100-day F. oxysporum inoculation trial. (hawaii.edu)
  • Here we show that the pattern of branching morphogenesis of three-dimensional (3D) engineered epithelial tissues is controlled in part by gradients of endogenous mechanical stress. (nih.gov)
  • These data suggest that the pattern and magnitude of mechanical stress across epithelial tissues cooperate with biochemical signals to specify branching pattern. (nih.gov)
  • (B, C) FEM stress profile of an epithelial tubule. (nih.gov)
  • This "pre-conditioning" phenomenon has been documented in many models of protection against oxidative stress, including ischemia/reperfusion and ultraviolet (UV) light exposure. (nih.gov)
  • Overall, treatment selection should be tailored to counterpart the effects of mechanical stress, which influences inflammation both in asthma and COPD. (hindawi.com)
  • Endogenous patterns of mechanical stress are required for branching morphogenesis. (nih.gov)
  • The results demonstrate that the dynamics of mechanical signal transmission depend on whether the applied force leads to transverse or axial motion of the stress fiber. (biomedsearch.com)
  • I have conducted a couple of experiments to demonstrate that there is less mechanical stress in the radial approach as compared to the axial approach but I would like to prove this concept mathematically (at a basic level). (physicsforums.com)
  • Can someone out there please explain the basic math principles that show why an axial turbine will have more mechanical stresses than a radial turbine? (physicsforums.com)
  • The hole causes the axial stress along the line of its center to be zero, because it is normal to the free surface of the hole. (stackexchange.com)
  • The object of this study is to provide evidence for new ways to explore bone's functional adaptation to mechanical stress made through the copious interpretation and integration of new and existing literature. (scirp.org)
  • The research team hopes to be able to prove that such mechanical adaptation processes are a central development step for multicellular life. (idw-online.de)
  • Mechanical stress plays an essential role in bone homeostasis. (springer.com)
  • This imaginary transformation from Sméagol to Gollum is a dramatization of the illusive repercussions of mechanical stress affecting bone. (scirp.org)
  • This paper presents the main ideas of mechanical stress and bone remodelling from a novel's perspective. (scirp.org)
  • A personal experience of a stress fracture is reviewed to parallel the implications that lead to the incident with the findings on the link between mechanical stress and bone remodelling. (scirp.org)
  • Some factors regarding age, gender and ethnicity and the interplay with mechanical stress influencing bone remodelling are considered. (scirp.org)
  • Firstly, the different aspects of this essay will be individually discussed beginning with mechanical stress, followed by bone remodelling. (scirp.org)
  • The next part of the essay will focus on the association between the two and the effect that mechanical stress has on bone remodelling. (scirp.org)
  • Here, an account of stress fracture injuries is presented and the implications of mechanical stress on bone remodelling debated. (scirp.org)
  • The main factors affect bone remodelling through mechanical stress such as age, gender and ethnicity where possible. (scirp.org)
  • Ultimately, this insulin- or insulin-resistance-mediated bone growth can be a potential explanation why von-Mises mechanical stress models predict Androgenetic Alopecia hair loss patterns. (hairlosstalk.com)
  • Bone Strength and In-Flight Mechanical Stresses. (dtic.mil)
  • Weight-bearing exercise-which is critical for retaining skeletal integrity-promotes osteoblast function, whereas a lack of mechanical stimulation, as seen during spaceflight or prolonged bed rest, can lead to osteoporosis. (sciencemag.org)
  • In this study, we have further explored the responses of A. thaliana such as ROS and resistance to B. cinerea in leaves that are subjected to more gentle form of mechanical stimulation. (biomedcentral.com)
  • The thickness of the fibrous cap, the percentage of stenosed area, and the stiffness of the core were studied (commonly associated with vulnerable plaque characteristics) to quantify their effects on the cap's mechanical stress state by performing analyses using computational fluid-structure interaction (FSI) methods. (scirp.org)
  • Severe stress conditions of modern structures and strict weight limitations call for continuous refining of the methods of strength and analysis and optimization of the technologies. (begellhouse.com)
  • This will apply less mechanical stress than the other mechanical methods. (altmedicinezone.com)
  • For the case of cold worked holes subject to remote loading, Pinho et al (2005) used 2D analytical and semi-analytical methods to predict stress intensity factors. (highbeam.com)
  • Alternative communication methods should be developed, and health care provider should be aware about the communication difficulties, thereby reducing the stress caused by ineffective communication. (nepjol.info)
  • Ancient and medieval architects did develop some geometrical methods and simple formulas to compute the proper sizes of pillars and beams, but the scientific understanding of stress became possible only after the necessary tools were invented in the 17th and 18th centuries: Galileo Galilei's rigorous experimental method, René Descartes's coordinates and analytic geometry, and Newton's laws of motion and equilibrium and calculus of infinitesimals. (wikipedia.org)
  • The analysis considers both temporally stationary and oscillatory mechanical signals and accounts for cytosolic drag on the stress fibers. (biomedsearch.com)
  • The present results suggest that cytoskeletal prestress mediates rapid mechanical signal transmission and allows temporally oscillatory signals in the physiological frequency range to travel a long distance without significant decay due to material viscosity and/or cytosolic drag. (biomedsearch.com)
  • Mechanosensitive ion channels in the plasma membrane are responsible for transducing the mechanical signals to electrical signals. (semanticscholar.org)
  • The Turbine Stress Evaluator (TSE) calculates and monitors the operational heat stresses of the turbine during every operational phase. (answers.com)
  • Articular cartilage experiences significant mechanical loads during daily activities. (ebscohost.com)
  • For transverse motion, mechanical signal transmission is dominated by prestress while fiber elasticity has a negligible effect. (biomedsearch.com)
  • Effect of selected manual therapy interventions for mechanical neck pain on vertebral and internal carotid arterial blood flow and cerebral inflow. (jaoa.org)
  • The top view Raman measurements utilize so called "High NA effect" to obtain additional information, and can resolve all 3 normal stress components near the top surface of silicon. (utexas.edu)
  • Effect of mechanical stress on magnet. (ugent.be)
  • To assess the baseline condition of the SI joints (SIJs) in healthy individuals without symptoms of back pain and to study the effect of mechanical stress caused by intense physical training on MRI of the SIJs. (ugent.be)