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 ...
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 ...
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 ...
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) ...
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 ...
Static Control Anti-Fatigue Mat, 3M Static Control Anti-Fatigue Mats enable workers to stand comfortably for long periods while minimizing the fatigue associated with stand work. Manufacture from durable rubber, 3M Anti-Fatigue Mats consist of a
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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 ...
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. ...
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
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 ...
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 ...
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 ...
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.. ...
... : Germany. Manufacturer specializing in ionizing devices for wide range of industries. Products include equipment and systems
When I was a kid, my father proved himself a powerful wizard when he magically stuck a balloon to the wall just by rubbing it on his head. Of course, I would later find out not only was it not magic, but the static electricity that was my childhood fascination can be a nightmarish problem for converters. The decision to purchase static control equipment and which equipment to purchase are choices
Superimposition of length fluctuations on contracted ASM have shown to reduce active force and stiffness. This effect is usually attributed to disruption of the actomyosin crossbridge cycle; however no direct experimental data is available to support this hypothesis. This in vitro study investigated the effect of the mechanical strains on 1) the ASM reactivity and 2) on the actin-myosin crossbridges. Experiments were carried out on maximally contracted bovine ASM subjected to length strains at various frequency in the range from 10 to 100Hz, superimposed on normal tidal stretches (frequency 0.33Hz, amplitude 4%). An organ bath system was used to apply strains and measure the force; immunofluorescence technique was performed to assess the crossbridges. The results show that superimposed length strains increase breathing relaxation effect with an optimal effect obtained at 50Hz. The cholinergic stimulation promotes actin-myosin connection, and length stretches promote the detachment of those ...
Ive talked at length on my site about DAVIS LAW of TISSUE DEFORMATION (HERE as well). H.G. Davis was a renowned Civil War-era surgeon who rightly realized, like Dr. Wolf did with bones before him (see links on Davis for info on Wolf), that soft tissues would remodel themselves in response to mechanical stresses put upon them. The problem is, if there arent enough of these mechanical stresses running around (or if the stresses never really change), then the tissues will inevitably shorten --- a common phenomenon that I refer to in my clinic as "TETHERING". What else do we know? If you are putting the kinds of mechanical stresses on MUSCLES and other connective tissues that Donnie and his crew are on a regular basis (LIGAMENTS, FASCIA, TENDONS, etc), said tissues are forced to adapt --- they have no choice. These adaptations are not anything novel and arent much different than the physical adaptations that occur from lifting weights or engaging in other forms of training (its known as getting ...
Authors=NOGUCHI Satoshi ! TORAMARU Atsushi. Journal/Book_names=EOS ! Transactions, American Geophysical Union 2003 AGU Fall Meeting. Publish_Country=United States. volume=84. number=46 supplement. pages=F1615-F1615. Publish_year=2003. Publisher=American Geophysical Union. Language_of_Text=EN. Data_Type=SE!CO. ISSN=00963941. ID=200318352. ...
View 8-Mechanical Behavior from NANO 108 at UCSD. STRESS - STRAIN ! RELATIONSHIPS! IN! MATERIALS! Sequence of Steps to Produce Sheet Metal Giant Forge Press Figure 5.4 Multi-Pass Rolling
This thesis presents an investigation of the thermo / hydro / mechanical behaviour of saturated soils with cryogenic suction effects. The flow relationships accommodate a number of mechanisms: i) heat transfer by conduction, convection, and latent heat transfer and ii) moisture transfer in the liquid phase due to pressure head, elevation head, and thermal gradients. The mechanical behaviour of the soil is modelled by an elasto-plastic work hardening modified Cam- Clay constitutive model. A numerical solution for the theoretical formulation is presented. Standard finite element methods are used for spatial discretisation and finite difference methods are used for temporal discretisation. Verification of the model is achieved by means of programme of tests to check the following cryogenic components i) coupled thermo-hydraulic response, ii) deformation behaviour of the fully coupled thermo-hydro-mechanical model, iii) transient coupled liquid flow and deformation behaviour, and iv) latent heat of ...
Two constitutive relations have been determined from test results that characterize, respectively, the uniaxial and photomechanical behavior of a polyester-styrene copolymer for strain rates from 10−5...
I am a hobbyist and I have designed a radial turbine device for use in a tidal stream. 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). I have been able to find references to Eulers equation but (not being an engineer or physicist) am unable to figure out how to use the formula to show the difference. 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 ...
The acceleration-deceleration associated with external impact to head causes the mechanical deformation of brain tissue, resulting in neuronal
CanmetMATERIALS mechanical testing laboratory performs a variety of standard mechanical tests, including tensile, compression and bending tests; Charpy impact tests; drop-weight tear tests (DWTT); fracture toughness tests; and creep, fatigue and crack growth tests. The lab is dedicated to developing novel test methodologies that meet research and industrial needs. Facilities include creep machines and several universal testing machines equipped with accessories, including a vacuum furnace, non-contact strain measuring devices such as a digital image correlation system and a video extensometer.. Through its state-of-the-art pipeline laboratory, CanmetMATERIALS has developed extensive expertise related to the preparation of artificial flaws, including fatigue pre-cracking, fully instrumented full-scale pipe tests, as well as small-scale specimens to evaluate susceptibility to stress-corrosion cracking.. CanmetMATERIALS mechanical testing laboratory in Calgary also has an X-ray diffractometer for ...
Dielectric ElectroActive Polymers (DEAP) have the potential of converting mechanical energy into electrical energy. DEAP consists of a silicone dielectric film material with a special corrugated surface and a very thin layer of metallic electrodes on both sides of the surface allowing for large mechanical deformations with low operating forces. This work examined the electrical properties of DEAP, in which the capacitance and the electrode resistance were affected by repeated stress relaxation cycles. Three samples of 25% strain DEAP were subjected to 3000 stress relaxation cycles at 4%, 10%, and 20% strain. The capacitance of each sample and the resistance of one electrode layer were measured in both the relaxed position and the stressed position, once per interval. The 4% sample did not indicate any changes up to 3000 stress cycles, but resistance increased uniformly by about 2%. The 10% stress samples capacitance and resistance had an increase of 6% and 4% respectively at 3000 cycles. The increase,
We investigate acute effects of axial stretch, applied by carbon fibers (CFs), on diastolic Ca2+ spark rate in rat isolated cardiomyocytes. CFs were attached either to both cell ends (to maximize the stretched region), or to the center and one end of the cell (to compare responses in stretched and nonstretched half-cells). Sarcomere length was increased by 8.01+/-0.94% in the stretched cell fraction, and time series of XY confocal images were recorded to monitor diastolic Ca2+ spark frequency and dynamics. Whole-cell stretch causes an acute increase of Ca2+ spark rate (to 130.7+/-6.4%) within 5 seconds, followed by a return to near background levels (to 104.4+/-5.1%) within 1 minute of sustained distension. Spark rate increased only in the stretched cell region, without significant differences in spark amplitude, time to peak, and decay time constants of sparks in stretched and nonstretched areas. Block of stretch-activated ion channels (2 micromol/L GsMTx-4), perfusion with Na+/Ca2+-free ...
The results of this study indicate that vagal ileal units are inhibited by SCFAs. Furthermore, the mechanical sensitivity of ileal units was severely impaired after SCFA contact. This desensitization occurred with SCFA concentrations in the range of those occurring during coloileal reflux episodes.. Ileal afferents described in this study are all of the mucosal type because their mechanical sensitivity was reversibly inhibited by topical lignocaine application (20). However, they differed significantly from vagal mucosal afferents described elsewhere in the gut. All units found in our study were slowly adapting to mechanical stimulus, whereas Leek (28) described duodenal mucosal receptors with an on-off response to mechanical distension. In contrast, Cottrell and Iggo (5) showed mucosal afferent fibers in the adult sheep duodenum with persistent responses to mechanical distension. The adaptation time of these duodenal mucosal receptors was within the range of that found for ileal units. More ...
As an example, different mechanical deformations may be generated using different scratch indenter geometries: 1mm spherical ball (hardened stainless or tungsten steel); conical diamond; cube corner; pyramidal; cylinder sectioned at 45° to the axis; 0.8mm diameter helix and the radius edge of a paperclip. Variation can also be introduced by the speed the stylus is drawn across the specimen surface. For scratch testers that provide an adjustable speed, care must be taken to ensure the rate of speed is the same for each test. Another consideration is the length of time a stylus sits on a specimen surface before the test commences, and how deep the stylus "sinks" in. Material properties such as surface roughness, hardness, modulus of elasticity, texture, grain, gloss level, and coating thickness will also influence the severity of scratch damage.. Although scratching appears to be a relatively simple concept, trying to evaluate and describe the results on a polymeric material is not always easy. ...
Bacterial biofilms, while made up of microbial-scale objects, also function as meso- and macroscale materials. In particular, macro-scale material properties determine how biofilms respond to large-scale mechanical stresses, e.g. fluid shear. Viscoelastic and other constitutive properties influence biomass structure (through growth and fluid shear stresses) by erosion and sloughing detachment. In this paper, using the immersed boundary method, biofilm is modelled by a system of viscoelastic, breakable springs embedded in a fluid flow, evolving according to the basic physical laws of conservation of mass and momentum. We demonstrate in the context of computer simulation biofilm deformation and detachment under fluid shear stress ...
I am interested in Arbitrary Lagrangian Eulerian formulation in modeling large strain solid mechanics problems. Can any one recommend some good resource on this topic? Both theoretical and numerical implementation are desired. Thanks in advance.. ...
Chapter 1: Stress. 1.1 Introduction 1. 1.2 Normal Stress Under Axial Loading 2. 1.3 Direct Shear Stress 7. 1.4 Bearing Stress 12. 1.5 Stresses on Inclined Sections 22. 1.6 Equality of Shear Stresses on Perpendicular Planes 24. Chapter 2: Strain. 2.1 Displacement, Deformation, and the Concept of Strain 31. 2.2 Normal Strain 32. 2.3 Shear Strain 39. 2.4 Thermal Strain 43. Chapter 3: Mechanical Properties of Materials. 3.1 The Tension Test 47. 3.2 The Stress-Strain Diagram 50. 3.3 Hookes Law 58. 3.4 Poissons Ratio 58. Chapter 4: Design Concepts. 4.1 Introduction 69. 4.2 Types of Loads 70. 4.3 Safety 71. 4.4 Allowable Stress Design 72. 4.5 Load and Resistance Factor Design 83. Chapter 5: Axial Deformation. 5.1 Introduction 89. 5.2 Saint-Venants Principle 90. 5.3 Deformations in Axially Loaded Bars 92. 5.4 Deformations in a System of Axially Loaded Bars 101. 5.5 Statically Indeterminate Axially Loaded Members 109. 5.6 Thermal Effects on Axial Deformation 128. 5.7 Stress Concentrations 140. Chapter ...
An alignment device for an apparatus. The apparatus is configured to selectively receive a first implement having a first width and a second implement having a second width, the first and second widths extending in a transverse direction generally orthogonal to an insertion axis direction of the first and second implements, the device comprising a pair of generally parallel spaced-apart elongated rails defining at least two channels, the at least two channels comprising a first channel having a first channel width, and a second channel having a second channel width, the first and second channel widths being different, the first channel being configured to centrally hold the first implement in the transverse direction, and the second channel being configured centrally hold the second implement in the transverse direction.
The current standard of care for bone metastasis is therapies targeting the cells that degrade bone. These cells are directed by cancer cells to degrade bone in order to release pro-tumorigenic growth factors stored within the skeletal extracellular matrix. These therapies are not curative and do not halt metastasis-mediated bone degradation, indicating additional factors contribute to bone degradation. My research program focuses on the skeletal mechanical environment and its regulation of cancer. Specifically, I will investigate 1) the skeletons mechanical environment and its regulation of the remodeling process, and 2) the role of osteoblastic cells, which comprise the principal sensor and effector cells of mechanical cues, in metastatic processes. My long-term goal is to identify novel therapeutic targets for treating and preventing bone metastases as well as cancer-associated reductions in bone strength. My experimental approach uses novel in vivo and in vitro mechanical loading model ...
Apart from the prediction of a variable viscosity, generalized Newtonian constitutive models cannot explain other phenomena such as recoil, stress relaxation, stress overshoot and extrudate swell which are commonly observed in polymer processing flows. These effects have a significant impact on the product quality in polymer processing and they should not be ignored. Theoretically, all of these phenomena can be considered as the result of the material having a combination of the properties of elastic solids and viscous fluids. Therefore mathematical modelling of polymer processing flows should, ideally, be based on the use of viscoelastic constitutive equations. Formulation of the constitutive equations for viscoelastic fluids has been the subject of a considerable amount of research over many decades. Details of the derivation of the viscoelastic constitutive equations and their classification are covered in many textbooks and review papers (see Tanner, 1985 Bird et al, 1977 Mitsoulis, 1990). ...
An important implication of the presence of tensile stress in epidermal and epithelial cell layers is that it tends to pull cells apart, thus threatening tissue integrity (Maeda et al., 2014). Thus, robust mechanisms must exist to allow the cells in these layers to remain tightly associated in the presence of such tensile stress, in turn suggesting that tensile stress perception might serve as a cue to consolidate adhesion. Indeed, recent studies have highlighted how various structural cell components contribute to achieving, maintaining and regulating cell-cell adhesion, while also contributing to mechanoperception.. The mechanisms that hold cells together in animal epithelia have been relatively well described (Baum and Georgiou, 2011; Leckband and de Rooij, 2014). Tight and adherens junctions, gap junctions, as well as desmosomes, hemi-desmosomes and focal adhesions are clusters of protein complexes that play key roles in cell adhesion. Some of the proteins that are part of these complexes ...
in Annales de Dermatologie et de Vénéréologie (2001), 128(2), 119-22. BACKGROUND: Cutaneous sensorial perception is complex and proves to be difficult to quantify. Skin sensitivity to mechanical distension is largely unexplored. We have developed an original method aimed at ... [more ▼]. BACKGROUND: Cutaneous sensorial perception is complex and proves to be difficult to quantify. Skin sensitivity to mechanical distension is largely unexplored. We have developed an original method aimed at quantifiying these physiological parameters.VOLUNTEERS AND METHODS: The study was performed on 24 adult volunteers aged 20 to 50 years. A Cutometer SEM 474 equipped with 2 and 4 mm diameter probes was used to exert a progressive or a steep suction on the cheeks. The intensities of both the suction and the skin deformation observed at the earliest moment the traction was perceived by the volunteers were recorded.RESULTS: The liminar sensorial detection under progressive suction force was 1.5 times lower ...
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A high-frequency electrosurgical treatment instrument for operations, includes a pair of forceps pieces, an insulating member, a transmission member, a manipulation rod member, a distal end cover member, a shaft member and a manipulation portion. The instrument, includes a flow channel portion formed between the manipulation rod member and the shaft member, the flow channel portion being disposed along a longitudinal direction of the manipulation rod member to allow liquid to flow; a groove portion that communicates with the flow channel portion to allow the liquid to flow from the flow channel portion; and an opening portion that communicates with the groove portion to supply the liquid near the proximal end portions of the pair of forceps pieces.
The quality of simulation results and their reliability is usually only as good as the agreement of the involved material laws with experimental data. This is especially true in the case of simulations exhibiting plastic strains or even material failure.. In our laboratory in Stuttgart, Germany, we are specialized on the material characterization of metals, polymers and composites. Customers from all over the world send us their material samples and we perform static as well as dynamic tests on them. Thereafter, we can either recommend a suitable material card for LS-DYNA or proceed with your individual choice and determine an optimal set of material parameters using the LS-OPT optimization software. Herein, our new full field calibration method, which is based digital image correlation to identify the material parameters, has been delivering promising results.. Our services include. ...
Most cells undergo complex mechanical interactions with the environment and neighbouring cells through the formation of focal adhesions and other adhesive structures [1-8]. These mechanical interactions provide physical mechanisms for various basic cellular activities, such as adhesion, migration, communication, proliferation and differentiation. Such activities collectively drive embryogenesis, tissue morphogenesis, tumour metastasis, wound healing, etc. [9]. Although cellular adhesion is commonly recognized, only a few mechanical factors thus far have been elucidated in a quantitative manner owing to practical difficulties in both theories and experiments to characterize the interfacial interactions. Among various interactions, surface traction has been shown to be important in cellular functions [10-12]. Such traction is essentially bidirectional, reciprocal and dynamic across the interface between the cell and the extracellular matrix (ECM). Most cells can modulate the traction force ...
In the paper presented, reinforced concrete shells of revolution are analyzed in both meridional and circumferential directions. Taking into account the physical non-linearity of the material, the internal forces and the deflections of the shell as well as the strain distribution at the cross-sections are calculated. The behavior of concrete under compression is described by linear and non-linear stress-strain relations. The description of the behavior of concrete under tension must account for tension stiffening effects. A tri-linear function is used to formulate the material law of reinforcement. The problem cannot be solved analytically due to the physical non-linearity. Thus a numerical solution is formulated by means of the LAGRANGE Principle of the minimum of the total potential energy. The kinematically admissible field of deformation is defined by the displacements u in the meridional and w in the radial direction. These displacements must satisfy the equations of compatibility and the ...
The Canadian Forest Service promotes the sustainable development of Canadas forests and the competitiveness of the Canadian forest sector
1 image Provider Notes:This is a temporary page to hold project related pictures extracted from the 2004 EAC presentation. Related Documents:WSR23a, WSR23b, WSR23c,WSR23d, WSR23e, WSR23f, WSR23g, WSR23h, WSR23i, WSR23j, WSR23k, WSR23l, WSR23m, WSR23o, WSR23p, WSR23q, WSR23r
Project 1: Shear stress-mediated cross talk between endothelial cells and breast cancer cells and its effect on the angiogenic response and metastatic potential of breast tumorsGraduate Student Researcher: Cara Buchanan
This volume by Michael Schutze, a world leader in this area of research, is the first volume to be published in the series. The formation of oxide layers is one of the most important areas of corrosion science and the author brings together for the first time in an English language text, work which has, until now, remained scattered. Contents: Basic Requirements for the Protective Action of Oxide Scales; Development of Oxide Scales in High Temperature Technology; Mechanical Stresses in Oxide Scales and their Causes; Deformation Behaviour and Deformation Mechanisms in Oxides; Damage to the Oxide Scale Resulting from Mechanical Stresses; Healing of Oxide Scale Damage; Depletion by Oxidation and Crack Healing of Alloying Elements forming Protective Scales. This book is invaluable for researchers working on the formation and behaviour of oxide layers, for those working on the storage, transport and use of corrosive materials and for industrial chemists, engineers, defence and materials scientists. ...
A simplified version of the Viscoplasticity Theory Based on Overstress (VBO) is applied to modeling of Alloy 800H at homologous temperatures between 0.6 and 0.8 The present formulation is simplified to the extent that omission of any constant would deprive the model to represent phenomena. Examples of such a phenomenon are tertiary creep and static recovery. The three-dimensional formulation of the simplified model for Alloy 8OOH at high homologous temperature needs a total of 10 constants. The parent theory from which the simplified model is derived has 18 constants that must be determined from experiments. The simplified theory has essentially the same modeling capability as the parent theory. There are differences in the predictions of the two versions for very long-time behaviour for which no test data are available. When material data are available for comparison the modeling of the regular and the simplified versions are very good and show roughly the same amount of deviation. The results ...
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Principal Investigator:TOMITA Yoshihiro, Project Period (FY):1995 - 1996, Research Category:Grant-in-Aid for Scientific Research (A), Section:試験, Research Field:Materials/Mechanics of materials
Overview of High Wall, 1948, directed by Curtis Bernhardt, with Robert Taylor, Audrey Totter, Herbert Marshall, at Turner Classic Movies
Hyperelastic constitutive laws are used to model materials that respond elastically when subjected to very large strains. They account both for nonlinear material behavior and large shape changes. The main applications of the theory are (i) to model the rubbery behavior of a polymeric material, and (ii) to model polymeric foams that can be subjected to large reversible shape changes (e.g. a sponge). In general, the response of a typical polymer is strongly dependent on temperature, strain history and loading rate. The behavior will be described in more detail in the next section, where we present the theory of viscoelasticity. For now, we note that polymers have various regimes of mechanical behavior, referred to as `glassy, `viscoelastic and `rubbery. The various regimes can be identified for a particular polymer by applying a sinusoidal variation of shear stress to the solid and measuring the resulting shear strain amplitude. A typical result is illustrated in the figure, which shows the ...
A) understanding how the lifetime of dielectric electroactive polymer (DEAP) devices is affected by (1) the combination of electrical and mechanical stress, (2) the dynamics of charging processes inside the DEAP material, (3) the presence of microscopic defects, and (4) the design and application of electrodes. Given a set of constraints of DEAP operating regime, DEAP size and required lifetime the maximum value will be determined for the electric field that is allowed. (B) Testing protocol and lifetime statistics. Based partially upon the knowledge obtained in (A), a testing protocol will be designed that provides the link between short duration laboratory testing on small specimens and industrial size DEAP devices that need to operate at a certain reliability for a number of years. In this part of the project, an assessment will be made of how DEAP materials can be exploited in an optimal and sustainable way.. Applications are invited for PhD positions ("Early Stage Researchers" ESR) to be ...
In order to test the effects of 4-NP on banded killifish social recognition by chemical cues, we studied the behaviour of test fish in a flow channel. The flow channel was made of Perspex and measured 71×38×20 cm (L×W×D). Mesh barriers were used to create a central compartment measuring 34×38×20 cm (L×W×D) within the flow channel itself. We distributed a thin layer of sand as a substrate in this central compartment. Water flowed into the channel at two points, the top left and the top right corners, from two 15 l reservoir buckets at a rate of 380±20 ml min−1 at each point. The water drained out of the flow channel at the bottom left and the bottom right corners through holes drilled into the walls. This had the effect of creating two parallel currents within the channel. Baffles placed at right angles to the current served to constrain the two streams. We repeatedly tested the flow patterns using water-borne dye and found that the dye streams remained separate for the full length of ...
By Ahmed H. Zewail. The fashionable electron microscope, due to fresh innovative advancements and plenty of evolutionary ones, now yields a wealth of quantitative wisdom bearing on constitution, dynamics, and serve as slightly matched through the other unmarried clinical tool. its also poised to give a contribution a lot new spatially-resolved and time-resolved insights of vital significance within the exploration of such a lot features of condensed subject, starting from the actual to the organic sciences. while in all traditional EM equipment, imaging, diffraction, and chemical analyses were carried out in a static - time-integrated - demeanour, now it has develop into attainable to unite the time area with the spatial one, thereby developing 4-dimensional (4D) electron microscopy. This improve relies at the primary thought of timed, coherent single-electron packets, or electron pulses, that are liberated with femtosecond intervals. Structural part transitions, mechanical deformations, and ...
Using a unique approach, the researchers induced the differentiation of specific cell types by generating mechanical forces on the surface of the iPSC-derived endothelium mimicking the flow of blood. For example, cells that felt a stronger "flow" became artery cells, while those that felt a weaker "flow" became vein cells. Continue reading. Read the paper in Stem Cell Reports ...
Using a unique single-molecule force measurement tool, a research team has developed a clearer understanding of how platelets sense the mechanical forces they encounter during bleeding to initiate the cascading process that leads to blood clotting. Beyond providing a better understanding of this vi
Small scale, low force material testing (Bose ELF 3200) with a range of load cells and displacement transducers; and axial as well as torsion actuation. This system is pair with long distance microscopes, acoustic emission measurements, and digital image correlation. A range of specimen fixtures are available ...
Authors: Valenta, Jaroslav , Vitek, Karel , Cihak, Radomir , Konvickova, Svatava , Sochor, Miroslav , Horny, Lukas Article Type: Research Article Abstract: An analytical model has been used to simulate the effects of tissue aging on residual strain, constitutive relations and stiffness parameter in the main right and left (ramus circumflexus) human coronary arteries, based on experimental data. The experimental opening angle θ scatters considerably with age. The optimum angle θop ≈70°, which makes the circumferential stress uniform in the arterial wall at a normal blood pressure, is approximately constant throughout aging. Above age of the 15 years the estimated and experimental values of θ are greater than θop and therefore the mechanical load of the inner layers of the media …and the intima decreases and the adventitia is overloaded. On the basis of nonlinear regression analysis, age‐related constitutive laws of arterial wall circumferential stiffness have been determined. Above the ...
This short tutorial video explains how to inspect cameras and lenses for contaminants before capturing images for digital image correlation and what to do if they are found. When contaminants of any kind are present, inaccurate shape and deformation measurements can result. To help prevent lens contaminants from appearing, be sure to use lens caps and camera body covers when your DIC system is not in use. For long-term storage keep lenses and cameras in the protective cases provided by Correlated Solutions.. ...
With this contribution we would like to point to a free MATLAB tool which uses digital image correlation and tracking techniques to measure strain from a series of digital images. The code can be found on the MATLAB central file exchange as well as the documentation, example images and some slides. We use the code on a daily basis for micro- and nanoscale measurements and present it here to be used and further developed by the community. Since it was posted at the end of september the code is now ranked place one or two in google and has been downloaded about 1000 times.. ...
The artist Kenneth Snelson built the first tensegrity structure. Buckminster Fuller coined the word tensegrity from two words, tension and integrity. Tensegrity structures are built of bars and tendons attached to the ends of the bars. The bars can resist compressive force and the strings cannot. Most bar-string configurations which one might conceive are not in equilibrium, and if actually constructed will collapse to a different shape. Only bar-string configurations in a stable equilibrium will be called tensegrity structures. If well designed, the application of forces to a tensegrity structure will deform it into a slightly different shape in a way which supports the applied forces. Tensegrity structures are very special cases of trusses, where members are assigned special functions. Some members are always in tension and others are always in compression. We will adopt the words tendons for the tensile members, and bars for compressive members. A tensegrity structures bars cannot be ...
We present the numerical and experimental study that we carried out to compare the performances of two hybrid stable-unstable resonators for diffusion-cooled CO2 slab lasers. The two resonators are designed to fit a 320 mm × 60 mm × 2 mm rf-discharge channel and are both guided in the narrow transverse direction. They differ in the other transverse direction, consisting of a positive- or a negative-branch unstable resonator scheme. The two solutions have been characterized in terms of modal structure, power extraction, stability, and quality of the extracted beam.. © 1996 Optical Society of America. Full Article , PDF Article ...
Fees. [Statutory Authority: RCW 43.70.250. WSR 91-13-002 (Order 173), § 360-18-020, filed 6/6/91, effective 7/7/91. Statutory Authority: RCW 18.64.005. WSR 89-04-015 (Order 222), § 360-18-020, filed 1/23/89; WSR 88-14-042 (Order 216), § 360-18-020, filed 6/30/88; WSR 88-07-011 (Order 209), § 360-18-020, filed 3/3/88; WSR 87-18-066 (Order 207), § 360-18-020, filed 9/2/87. Statutory Authority: RCW 18.64.005(4). WSR 85-22-033 (Order 196), § 360-18-020, filed 10/31/85; WSR 85-06-010 (Order 193), § 360-18-020, filed 2/22/85. Statutory Authority: RCW 18.64.005. WSR 84-17-142 (Order 189), § 360-18-020, filed 8/22/84; WSR 84-04-030 (Order 184), § 360-18-020, filed 1/25/84; WSR 83-22-034 (Order 177), § 360-18-020, filed 10/26/83. Statutory Authority: RCW 18.64.005 and 18.64A.020. WSR 83-18-021 (Order 175), § 360-18-020, filed 8/30/83. Statutory Authority: RCW 18.64.005(12). WSR 82-12-041 (Order 168), § 360-18-020, filed 5/28/82. Statutory Authority: RCW 18.64.005 (4) and (11). WSR 80-08-035 ...
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Studies of red blood cell deformation have shown that there are a number of membrane material properties that affect the deformation process. In this paper various types of deformation are modeled using geometrical and constitutive simplifications so that the effect of intrinsic elastic and viscous membrane properties and of major geometric constraints is made obvious while other factors are ignored. To this end, numerical solutions are shunned in favor of exact analytical ("closed-form") solutions to simple and basic membrane deformation problems in order to reveal functional dependence. ...
A damping device for use in conjunction with a circulatory pressure measuring system to attenuate resonant pressure waves therein includes a series connector for connection to the pressure measuring system. An integrally connected parallel portion includes a capillary tube fluid resistance element in communication with the series connector. A flexible membrane isolates the capillary tube from a fixed volume gas chamber located adjacent the flexible membrane.
We have hypothesized that collagenous matrix is an intrinsically smart biomaterial which resists enzymatic attack when under tensile strain. Testing this hypothesis requires the ability expose native tissue to low volumes of enzyme (due to their expense) while tracking mechanical response. In this study, we have developed an environmentally-controlled, mechanochemical bioreactor which permits load/strain tracking and direct observation of degrading tissue (polarization pictures) in a very small volume chamber (∼ 500 ul). In the device, the chamber "reaction volume" is formed between two layers of inert immiscible fluids. The device permitted exposure of the native tissue strips (∼6.0 mm × 0.7 mm × 13.5 mm) to small volumes of enzyme solution while it tracked the degradation-induced stress relaxation (to 0.01N accuracy) and provided direct observation of the tissue polarization signal. As expected in this small series, tissue with the higher (4% and 8%) strain degraded much more slowly ...
Characterizing the full range of damage and plastic behaviour of asphalt mixtures under varying strain-rates and stress states is a complex and challenging task. One reason for this is partly due to the strain rate and temperature dependent nature of the material as well as the variation in the properties of the constituent materials that make up the composite asphalt mixture. Existing stress-based models for asphalt concrete materials are developed based on mechanics principles, but these models are, however, limited in their application for actual pavement analysis and design since rate dependency parameters are needed in the constitutive model to account for the influence of the strain rate on the stress-based yield and evolution criteria. Till date, we are yet to arrive at simple and comprehensive constitutive models that can be used to model the behaviour of asphalt mixture over a wide range of strain-rate which is experienced in the actual pavement sections. The aim of this thesis is to ...
A method for operating a peristaltic pump having a molded flow channel contained on an elastomeric sheet that is bonded or mechanically attached to a rigid substrate. The pump head rollers are mounted radially from the axis of rotation of the pump motor and compress the elastomeric flow channels against the rigid substrate. During reflux, the pump head is positioned so that at least one of the rollers compresses the elastomeric flow channel at the input end of the peristaltic pump. Such an operation minimizes the amount of the elastomeric sheet that is exposed to high transient pressures.
GO:0034405. Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a fluid shear stress stimulus. Fluid shear stress is the force acting on an object in a system where the fluid is moving across a solid surface. ...
Coban™ 2 Layer Compression System, Includes Roll 1 - Comfort Layer, 4 inch x 2.9 yd (10cm x 2.7m), unstretched, and Roll 2 - Compression Layer, 4 inch x 5.1 yd (10cm x 4.7m), fully stretched length,1 Box,8 Box/Case
Using a unique single-molecule force measurement tool, a research team has developed a clearer understanding of how platelets sense the me
Shear stresses are known to influence the morphology, and even the fate, of many cell types, including endothelial, smooth muscle, and osteoblast cells. This paper describes a novel shear device for the study of cell mechanics. Unlike all other publi
Edition Size: 100 Total. Embellishing adds rich color and texture to your giclee. The highlights of paint are unique on each piece. Artwork arrives unstretched, rolled in a tube, ready for your custom framing ...
Researchers have for the first time demonstrated that mechanical forces can control the depolymerization of actin, a critical protein that provides the major force-bearing structure in the cytoskeletons of cells. The research suggests that forces applied both externally and internally may play a muc
Statutory Authority: RCW 43.70.250, 43.20B.020, 70.98.080, and 43.70.110. WSR 11-02-012, § 246-254-053, filed 12/28/10, effective 1/31/11; WSR 08-14-118, § 246-254-053, filed 6/30/08, effective 7/31/08. Statutory Authority: RCW 19.02.050, 43.20B.020, 43.70.110, 43.70.250, 70.98.080. WSR 07-14-130, § 246-254-053, filed 7/3/07, effective 8/3/07. Statutory Authority: RCW 70.98.080, 43.20B.020, 43.70.110, and 43.70.250. WSR 05-24-108, § 246-254-053, filed 12/7/05, effective 1/7/06. Statutory Authority: RCW 43.70.250. WSR 04-12-125, § 246-254-053, filed 6/2/04, effective 7/3/04. Statutory Authority: RCW 43.70.250 and 43.70.110. WSR 03-13-122, § 246-254-053, filed 6/18/03, effective 7/19/03. Statutory Authority: RCW 43.70.250 and 2001 2nd sp.s. c 7 § 220. WSR 02-07-085, § 246-254-053, filed 3/19/02, effective 4/19/02. Statutory Authority: RCW 43.70.110. WSR 01-14-048, § 246-254-053, filed 6/29/01, effective 7/30/01; WSR 99-13-085, § 246-254-053, filed 6/14/99, effective 7/15/99; WSR ...
The main contribution of integrating 4D SPIM technique with hemodynamic forces resides in the elucidation of the interplay between shear stress and Notch activation in initiating trabeculation during cardiac morphogenesis. By implementing the nongated 4D synchronization algorithm with SPIM, we have unraveled the trabecular network in association with ventricular contractile function. While the development of trabeculation is conserved between the zebrafish and chick, mouse, and human embryos (3, 23, 37-39), there are numerous layers of cardiomyocytes in mice (23), and there is a thin layer of cardiomyocytes for trabeculation in zebrafish embryos. For this reason, 4D SPIM imaging enables uniform illumination to uncover shear stress-induced endocardial Notch signaling to form a trabecular network for contractile function with high axial, spatial, and temporal resolution. We demonstrated that (a) gata1a MO decreased hematopoiesis to reduce shear stress, (b) tnnt2a MO inhibited ventricular ...
A multi-phase wrinkling model accounts for the radial and circumferential tension and differential expansion between a uniformly proliferating outer fluid-like layer and an incompressible core that together drive cerebellar folding.
Designed for ease of use and general versatility, this printed circuit card provides complete conditioning for any of MicroStrains DVRT sensors. The DEMOD-DVRT is recommended for use with all standard MicroStrain DVRT where the temperature is expected to uniformly change across the sensor itself. If the sensor is expected to be exposed to thermal gradients across its sensing coils (its body), the temperature compensated DEMOD-DVRT -TC is recommended.. Product URL : http://www.microstrain.com/displacement/demod-dvrt. Last Updated : 11/09/2012. Categories : "Transducers, Force" ...
The drying sequence in the manufacturing process for paperboard involves evaporation of water, primarily from within the fibres. The vapour is then transported out of the web by pressure or concentration gradients. As the moisture transport from the paper web to the ambient is quicker than the moisture transport within the fibre network to the surfaces of the web, moisture gradients develop through the thickness of the web. This work concerns effects on the mechanics of paper drying from the variation in moisture through the relatively thin structures of paper and paperboard.. Distributions of inplane residual stresses through paper materials in the unloaded state after drying are believed to be caused by the varying moisture through the thickness during drying. The distributions in general exhibit compressive stress near the board surfaces and tensile stress in the interior of the board. This may be modified after drying and is also affected by structural variation in the material between ...
Statutory Authority: RCW 51.04.020 and 51.04.030. WSR 17-16-133, § 296-20-01002, filed 8/1/17, effective 9/1/17; WSR 15-17-104, § 296-20-01002, filed 8/18/15, effective 10/1/15. Statutory Authority: RCW 51.04.020, 51.04.030, and Title 51 RCW. WSR 08-24-047, § 296-20-01002, filed 11/25/08, effective 12/26/08. Statutory Authority: 2007 c 263, RCW 51.04.020 and 51.04.030. WSR 08-04-095, § 296-20-01002, filed 2/5/08, effective 2/22/08. Statutory Authority: RCW 51.04.020, 51.04.030 and 2007 c 134. WSR 08-02-021, § 296-20-01002, filed 12/21/07, effective 1/21/08. Statutory Authority: RCW 51.04.020, 51.04.030. WSR 07-17-167, § 296-20-01002, filed 8/22/07, effective 9/22/07. Statutory Authority: 2004 c 65 and 2004 c 163. WSR 04-22-085, § 296-20-01002, filed 11/2/04, effective 12/15/04. Statutory Authority: RCW 51.04.020, 70.14.050. WSR 04-08-040, § 296-20-01002, filed 3/30/04, effective 5/1/04. Statutory Authority: RCW 51.04.020. WSR 03-21-069, § 296-20-01002, filed 10/14/03, effective 12/1/03. ...
A study of the mechanical behaviour of networks. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
I do not have studies supporting static stretching pre maximal lifting, however I see that my response was not entirely clear. I did not mean to imply that one should static stretch before the actual maximal lifting session. I intended only to reinforce the importance of a properly guided and stuctured static stretching routine before one begins a maximal lifting periodization. All imbalances should be addressed and corrected with static stretching (and foam rolling) weeks before a maximal lifting regime begins. I think that we can agree that imbalances cannot be corrected in one static stretching session. If imbalances are corrected and proper length-tension relationships are achieved well before maximal training begins - would you agree that you may not need a static stretching routine during this periodization? A light active and mostly dynamic stretching warm up pre workout would seem sufficient, safe and smart. In Health- ...
This solution extends ConceptDraw PRO v.9 mechanical drawing software (or later) with samples of mechanical drawing symbols, templates and libraries of design elements, for help when drafting mechanical engineering drawings, or parts, assembly, pneumatic, Example Of Application Of Technical Drawing For Mechanical Engineer
An interdisciplinary team of researchers has developed a composite material that emits light and heat when exposed to specific wavelengths of radiation and can be customized to have specific mechanical characteristics.