Shear Strength: The internal resistance of a material to moving some parts of it parallel to a fixed plane, in contrast to stretching (TENSILE STRENGTH) or compression (COMPRESSIVE STRENGTH). Ionic crystals are brittle because, when subjected to shear, ions of the same charge are brought next to each other, which causes repulsion.Materials Testing: The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.Dental Bonding: An adhesion procedure for orthodontic attachments, such as plastic DENTAL CROWNS. This process usually includes the application of an adhesive material (DENTAL CEMENTS) and letting it harden in-place by light or chemical curing.Osseointegration: The growth action of bone tissue as it assimilates surgically implanted devices or prostheses to be used as either replacement parts (e.g., hip) or as anchors (e.g., endosseous dental implants).Stress, Mechanical: 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.Dental Stress Analysis: The description and measurement of the various factors that produce physical stress upon dental restorations, prostheses, or appliances, materials associated with them, or the natural oral structures.Bone Cements: Adhesives used to fix prosthetic devices to bones and to cement bone to bone in difficult fractures. Synthetic resins are commonly used as cements. A mixture of monocalcium phosphate, monohydrate, alpha-tricalcium phosphate, and calcium carbonate with a sodium phosphate solution is also a useful bone paste.Surface Properties: Characteristics or attributes of the outer boundaries of objects, including molecules.Muscle Strength: The amount of force generated by MUSCLE CONTRACTION. Muscle strength can be measured during isometric, isotonic, or isokinetic contraction, either manually or using a device such as a MUSCLE STRENGTH DYNAMOMETER.Tensile Strength: 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)Hand Strength: Force exerted when gripping or grasping.Compressive Strength: The maximum compression a material can withstand without failure. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed, p427)Hemorheology: The deformation and flow behavior of BLOOD and its elements i.e., PLASMA; ERYTHROCYTES; WHITE BLOOD CELLS; and BLOOD PLATELETS.Resin Cements: Dental cements composed either of polymethyl methacrylate or dimethacrylate, produced by mixing an acrylic monomer liquid with acrylic polymers and mineral fillers. The cement is insoluble in water and is thus resistant to fluids in the mouth, but is also irritating to the dental pulp. It is used chiefly as a luting agent for fabricated and temporary restorations. (Jablonski's Dictionary of Dentistry, 1992, p159)Muscle Strength Dynamometer: A device that measures MUSCLE STRENGTH during muscle contraction, such as gripping, pushing, and pulling. It is used to evaluate the health status of muscle in sports medicine or physical therapy.Friction: Surface resistance to the relative motion of one body against the rubbing, sliding, rolling, or flowing of another with which it is in contact.Lubrication: The application of LUBRICANTS to diminish FRICTION between two surfaces.Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Pressure: A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Adhesives: Substances that cause the adherence of two surfaces. They include glues (properly collagen-derived adhesives), mucilages, sticky pastes, gums, resins, or latex.Leuconostocaceae: A family of gram-positive bacteria in the order Lactobacillales. Lactic acid is the main product of their carbohydrate metabolism.Rutin: A flavonol glycoside found in many plants, including BUCKWHEAT; TOBACCO; FORSYTHIA; HYDRANGEA; VIOLA, etc. It has been used therapeutically to decrease capillary fragility.Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.Bacterial Proteins: Proteins found in any species of bacterium.PortugalBibliometrics: The use of statistical methods in the analysis of a body of literature to reveal the historical development of subject fields and patterns of authorship, publication, and use. Formerly called statistical bibliography. (from The ALA Glossary of Library and Information Science, 1983)San FranciscoNew MexicoArgon: Argon. A noble gas with the atomic symbol Ar, atomic number 18, and atomic weight 39.948. It is used in fluorescent tubes and wherever an inert atmosphere is desired and nitrogen cannot be used.Orthodontic Brackets: Small metal or ceramic attachments used to fasten an arch wire. These attachments are soldered or welded to an orthodontic band or cemented directly onto the teeth. Bowles brackets, edgewise brackets, multiphase brackets, ribbon arch brackets, twin-wire brackets, and universal brackets are all types of orthodontic brackets.Laser Therapy: The use of photothermal effects of LASERS to coagulate, incise, vaporize, resect, dissect, or resurface tissue.National Academy of Sciences (U.S.): A United States organization of distinguished scientists and engineers established for the purpose of investigating and reporting upon any subject of art or science as requested by any department of government. The National Research Council organized by NAS serves as the principal operating agency to stimulate and support research.LouisianaBentonite: A colloidal, hydrated aluminum silicate that swells 12 times its dry size when added to water.Photoelectron Spectroscopy: The study of the energy of electrons ejected from matter by the photoelectric effect, i.e., as a direct result of absorption of energy from electromagnetic radiation. As the energies of the electrons are characteristic of a specific element, the measurement of the energy of these electrons is a technique used to determine the chemical composition of surfaces.Research Report: Detailed account or statement or formal record of data resulting from empirical inquiry.Institute of Medicine (U.S.): Identifies, for study and analysis, important issues and problems that relate to health and medicine. The Institute initiates and conducts studies of national policy and planning for health care and health-related education and research; it also responds to requests from the federal government and other agencies for studies and advice.Dental Atraumatic Restorative Treatment: Treatment modality for DENTAL CARIES that uses manual excavation method and GLASS IONOMER CEMENTS. Because of its noninvasiveness and no need for expensive equipment and anesthesia it is promoted as an approach in places where dental care is not readily available.Glass Ionomer Cements: A polymer obtained by reacting polyacrylic acid with a special anion-leachable glass (alumino-silicate). The resulting cement is more durable and tougher than others in that the materials comprising the polymer backbone do not leach out.Dentin: The hard portion of the tooth surrounding the pulp, covered by enamel on the crown and cementum on the root, which is harder and denser than bone but softer than enamel, and is thus readily abraded when left unprotected. (From Jablonski, Dictionary of Dentistry, 1992)Dental Enamel: A hard thin translucent layer of calcified substance which envelops and protects the dentin of the crown of the tooth. It is the hardest substance in the body and is almost entirely composed of calcium salts. Under the microscope, it is composed of thin rods (enamel prisms) held together by cementing substance, and surrounded by an enamel sheath. (From Jablonski, Dictionary of Dentistry, 1992, p286)Nanotubes, Carbon: Nanometer-sized tubes composed mainly of CARBON. Such nanotubes are used as probes for high-resolution structural and chemical imaging of biomolecules with ATOMIC FORCE MICROSCOPY.Nanostructures: Materials which have structured components with at least one dimension in the range of 1 to 100 nanometers. These include NANOCOMPOSITES; NANOPARTICLES; NANOTUBES; and NANOWIRES.Nanotubes: Nanometer-sized tubes composed of various substances including carbon (CARBON NANOTUBES), boron nitride, or nickel vanadate.Nanotechnology: The development and use of techniques to study physical phenomena and construct structures in the nanoscale size range or smaller.Access to Information: Individual's rights to obtain and use information collected or generated by others.Nanocomposites: Nanometer-scale composite structures composed of organic molecules intimately incorporated with inorganic molecules. (Glossary of Biotechnology and Nanobiotechology Terms, 4th ed)Acid Etching, Dental: Preparation of TOOTH surfaces and DENTAL MATERIALS with etching agents, usually phosphoric acid, to roughen the surface to increase adhesion or osteointegration.Dentin-Bonding Agents: Cements that act through infiltration and polymerization within the dentinal matrix and are used for dental restoration. They can be adhesive resins themselves, adhesion-promoting monomers, or polymerization initiators that act in concert with other agents to form a dentin-bonding system.Membrane Fluidity: The motion of phospholipid molecules within the lipid bilayer, dependent on the classes of phospholipids present, their fatty acid composition and degree of unsaturation of the acyl chains, the cholesterol concentration, and temperature.Cell Adhesion: Adherence of cells to surfaces or to other cells.Acacia: A plant genus of the family FABACEAE. The gums and tanning agents obtained from Acacia are called GUM ARABIC. The common name of catechu is more often used for Areca catechu (ARECA).Cell Movement: The movement of cells from one location to another. Distinguish from CYTOKINESIS which is the process of dividing the CYTOPLASM of a cell.Fibronectins: Glycoproteins found on the surfaces of cells, particularly in fibrillar structures. The proteins are lost or reduced when these cells undergo viral or chemical transformation. They are highly susceptible to proteolysis and are substrates for activated blood coagulation factor VIII. The forms present in plasma are called cold-insoluble globulins.

Bacterial swimming strategies and turbulence. (1/1135)

Most bacteria in the ocean can be motile. Chemotaxis allows bacteria to detect nutrient gradients, and hence motility is believed to serve as a method of approaching sources of food. This picture is well established in a stagnant environment. In the ocean a shear microenvironment is associated with turbulence. This shear flow prevents clustering of bacteria around local nutrient sources if they swim in the commonly assumed "run-and-tumble" strategy. Recent observations, however, indicate a "back-and-forth" swimming behavior for marine bacteria. In a theoretical study we compare the two bacterial swimming strategies in a realistic ocean environment. The "back-and-forth" strategy is found to enable the bacteria to stay close to a nutrient source even under high shear. Furthermore, rotational diffusion driven by thermal noise can significantly enhance the efficiency of this strategy. The superiority of the "back-and-forth" strategy suggests that bacterial motility has a control function rather than an approach function under turbulent conditions.  (+info)

In vitro characterization and micromechanics of tumor cell chemotactic protrusion, locomotion, and extravasation. (2/1135)

The objective of this paper is to introduce some novel in vitro applications in characterizing human melanoma cell protrusion and migration in response to soluble extracellular matrix protein stimulation. Specifically, we describe two assay systems: (1) dual-micropipette manipulation and (2) flow-migration chamber. Applications of the dual-micropipet technique provided kinetic measure of cell movement, cyclic pseudopod protrusion, and subsequent cell locomotion governed by chemotactic molecular transport dynamics. Chemotactic concentration gradient was found to influence significantly pseudopod protrusion frequency and locomotion speed, but not the protrusion extension. To further characterize active tumor cell extravasation, a process that involves dynamic tumor cell adhesion to vascular endothelium under flow conditions and subsequent transendothelial migration in response to chemotactic signals from the interstitial space, we developed a flow-migration chemotaxis system. This assay enabled characterization of tumor cell transcellular migration in terms of chemotactic signal gradients, shear forces, and cell-substrate adhesion. Results suggest that shear flow plays significant roles in tumor cell extravasation that is regulated by both tumor cell motility and tumor cell adhesion to endothelial molecules in a cooperative process.  (+info)

Fluid shear stress remodels expression and function of junctional proteins in cultured bone cells. (3/1135)

We tested the hypothesis that fluid shear stress (tau) modifies the expression, function, and distribution of junctional proteins [connexin (Cx)43, Cx45, and zona occludens (ZO)-1] in cultured bone cells. Cell lines with osteoblastic (MC3T3-E1 cells) and osteocytic (MLO-Y4 cells) phenotypes were exposed to tau-values of 5 or 20 dyn/cm(2) for 1-3 h. Immunostaining indicated that at 5 dyn/cm(2), the distribution of Cx43, Cx45, and ZO-1 was moderately disrupted at cell membranes; at 20 dyn/cm(2), disruption was more severe. Intercellular coupling was significantly decreased at both shear stress levels. Western blots showed the downregulation of membrane-bound Cx43 and ZO-1 and the upregulation of cytosolic Cx43 and Cx45 at different levels of shear stress. Similarly, Northern blots revealed that expression of Cx43, Cx45, and ZO-1 was selectively up- and downregulated in response to different shear stress levels. These results indicate that in cultured bone cells, fluid shear stress disrupts junctional communication, rearranges junctional proteins, and determines de novo synthesis of specific connexins to an extent that depends on the magnitude of the shear stress. Such disconnection from the bone cell network may provide part of the signal whereby the disconnected cells or the remaining network initiate focal bone remodeling.  (+info)

Shear bond strength of a new dental adhesive used to bond brackets to unetched enamel. (4/1135)

The aims of the present study were to measure the shear bond strength of a new multipurpose dental adhesive, IntegraCem, for direct bonding of stainless steel and ceramic brackets to unetched enamel, and to determine the mode of bond failure. Both stainless steel and ceramic brackets (GAC) were bonded with IntegraCem to unetched extracted human premolars. After bonding, the teeth were either stored in a water bath at 37 degrees C for 3 days or passed 2500 thermocycles from 6 to 60 degrees C. Debonding was then performed with a shearing force using an Instron universal testing machine. The force was recorded at bond failure. The results showed that the shear bond strength achieved was between 6.7 and 10.8 megapascals (MPa). Bond failure occurred at the enamel-adhesive interface, enabling more efficient enamel clean up. The shear bond strengths measured suggest that IntegraCem adhesive may be effectively used in orthodontic treatment.  (+info)

Shear properties of passive ventricular myocardium. (5/1135)

We examined the shear properties of passive ventricular myocardium in six pig hearts. Samples (3 x 3 x 3 mm) were cut from adjacent regions of the lateral left ventricular midwall, with sides aligned with the principal material axes. Four cycles of sinusoidal simple shear (maximum shear displacements of 0.1-0.5) were applied separately to each specimen in two orthogonal directions. Resulting forces along the three axes were measured. Three specimens from each heart were tested in different orientations to cover all six modes of simple shear deformation. Passive myocardium has nonlinear viscoelastic shear properties with reproducible, directionally dependent softening as strain is increased. Shear properties were clearly anisotropic with respect to the three principal material directions: passive ventricular myocardium is least resistant to simple shear displacements imposed in the plane of the myocardial layers and most resistant to shear deformations that produce extension of the myocyte axis. Comparison of results for the six different shear modes suggests that simple shear deformation is resisted by elastic elements aligned with the microstructural axes of the tissue.  (+info)

Comparative analysis of various platelet glycoprotein IIb/IIIa antagonists on shear-induced platelet activation and adhesion. (6/1135)

Platelet accretion into arterial thrombus in stenotic arterial vessels involves shear-induced platelet activation and adhesion. The Cone and Plate(let) Analyzer (CPA) is designed to simulate such conditions in vitro under a rotating high shear rate in whole blood. In the present study, we evaluated various experimental conditions (including aspirin, temperature, and calcium concentration) and investigated the effects of small molecules along with peptide glycoprotein IIb/IIIa antagonists on platelet adhesion using the CPA system. Concentration-dependent effect of glycoprotein IIb/IIIa antagonists on shear-induced platelet adhesion showed marked differences in potencies: IC50 = 34, 35, 91, 438, and 606 nM for DPC802 (a specific glycoprotein IIb/IIIa antagonist), roxifiban, sibrafiban, lotrafiban, and orbofiban (free acid forms), respectively, and IC50 values of 43, 430, and 5781 nM for abciximab, tirofiban, and eptifibatide, respectively. Parallel study was also conducted to evaluate the effect of glycoprotein IIb/IIIa inhibitors using optical aggregometry. The potency of fibans in blocking shear-induced platelet adhesion correlated well with their binding affinity to the resting and activated glycoprotein IIb/IIIa receptors, as well as their "off-rates". Nevertheless, none of these fibans was able to effectively block shear-induced platelet adhesion at targeted clinical dosing regimens except for abciximab. These data suggest that glycoprotein IIb/IIIa antagonists that show similar efficacy in the inhibition of platelet aggregation in a static in vitro assay may differ substantially in a shear-based system of platelet adhesion. The clinical significance of this phenomenon awaits further investigation.  (+info)

Shear stress magnitude and directionality modulate growth factor gene expression in preconditioned vascular endothelial cells. (7/1135)

OBJECTIVE: The purpose of this study was to simultaneously monitor the transcriptional levels of 12 endothelial growth factor genes in response to alterations in wall shear stress (WSS) under conditions relevant to the development of intimal hyperplasia, a major cause of arterial bypass graft failure. METHODS: Human umbilical vein endothelial cells were preconditioned in vitro under steady flow (WSS, 15 dynes/cm(2)) for 24 hours before being subjected to WSS at 25 (Delta = +10), 15 (Delta = 0), 5 (Delta = -10), 2.5 (Delta = -12.5), and 0 (Delta = -15) dynes/cm(2) or low magnitude WSS reversal (-2.5 dynes/cm(2)) for 6 hours. A focused complementary DNA array was used to simultaneously measure messenger RNA expression levels for END1, endothelial nitric oxide synthase (NOS3), platelet-derived growth factor A, platelet-derived growth factor B (PDGFB), acidic fibroblast growth factor, basic fibroblast growth factor, transforming growth factor-alpha, transforming growth factor-beta, vascular endothelial growth factor, insulin-like growth factor-1, epidermal growth factor, and angiotensin converting enzyme. RESULTS: Preconditioning significantly (P <.05) increased the fold expression of NOS3 (4.1 +/- 1.4), basic fibroblast growth factor (3.90 +/- 1.16), vascular endothelial growth factor (3.39 +/- 1.04), and insulin-like growth factor-1 (2.8 +/- 0.7) but decreased END1 (0.47 +/- 0.05) and PDGFB (0.70 +/- 0.04) messenger RNA expression levels relative to no-flow controls, an effect that was sustained on removal from flow for 6 hours. Notably, the ratio of END1/NOS3 expression was diminished (0.11 +/- 0.03) relative to that of cells maintained in static culture. Although few differences in gene expression from baseline (15 dynes/cm(2)) were measured in cells exposed to either constant (Delta = 0) or step decreases (Delta = -10, -12.5, or -15 dynes/cm(2)) in WSS, marked changes were seen in the group exposed to a step increase in WSS (Delta = +10) or to WSS reversal. Low magnitude retrograde WSS evoked significant (P <.05) transcriptional changes in multiple genes, including elevated END1 (4.1 +/- 0.5), platelet-derived growth factor A (1.5 +/- 0.2), PDGFB (2.3 +/- 0.3), and transforming growth factor-beta (1.5 +/- 0.2) levels, but depressed NOS3 (0.60 +/- 0.17) levels, and a marked increase in END1/NOS3 (6.7 +/- 1.6) when compared with equal magnitude antegrade WSS (2.5 dynes/cm(2)). CONCLUSION: These results support the implementation of a preconditioning phase for in vitro WSS studies to establish a physiologic baseline. Our findings complement previous macroscale findings and are consistent with a cellular mechanism involving increased END1 and PDGFB levels, but decreased NOS3 levels, leading to intimal hyperplasia at regions of low magnitude reversing WSS.  (+info)

Microrheology of human lung epithelial cells measured by atomic force microscopy. (8/1135)

Lung epithelial cells are subjected to large cyclic forces from breathing. However, their response to dynamic stresses is poorly defined. We measured the complex shear modulus (G(*)(omega)) of human alveolar (A549) and bronchial (BEAS-2B) epithelial cells over three frequency decades (0.1-100 Hz) and at different loading forces (0.1-0.9 nN) with atomic force microscopy. G(*)(omega) was computed by correcting force-indentation oscillatory data for the tip-cell contact geometry and for the hydrodynamic viscous drag. Both cell types displayed similar viscoelastic properties. The storage modulus G'(omega) increased with frequency following a power law with exponent approximately 0.2. The loss modulus G"(omega) was approximately 2/3 lower and increased similarly to G'(omega) up to approximately 10 Hz, but exhibited a steeper rise at higher frequencies. The cells showed a weak force dependence of G'(omega) and G"(omega). G(*)(omega) conformed to the power-law model with a structural damping coefficient of approximately 0.3, indicating a coupling of elastic and dissipative processes within the cell. Power-law behavior implies a continuum distribution of stress relaxation time constants. This complex dynamics is consistent with the rheology of soft glassy materials close to a glass transition, thereby suggesting that structural disorder and metastability may be fundamental features of cell architecture.  (+info)

  • This law has also been derived from the hypothesis that the shear force of moving blood on the inner walls of vessels is constant throughout the vascular system. (
  • When a structure consists of walls (or frames) of varying heights tied together by a rigid diaphragm, the impact of the tall wall on the shear in the short wall, and vice versa, can be significant. (
  • The distribution of shear forces among these walls is not simply proportional to the cross-sectional properties at any given level. (
  • This shows that the distribution of the shear is not merely a function of the wall cross section at a level but is also a function of the loading and displacements of the walls above. (
  • Under these conditions the short walls pull shear out of the tall walls. (
  • The discussion of the behavior described above is valid for structures consisting of moment frames or braced frames, as well as for those consisting of shear walls. (
  • Purdue University researchers have produced a new site investigation torque tool, known as SPT-T that can better characterize the soil and provide valuable data on shear strength, particularly for clay soils and glacial till. (
  • The SPT has served as a simple test to estimate the relative density of soils and approximate shear strength parameters for engineers planning geotechnical structures such as foundation design and slope stability checks. (
  • the torque is then related to the shear strength in these soils. (
  • For example, it does not take into account the effects of shear deformation (a 1.2VH/AE term would be added to each side, where V is V A and V B , respectively). (
  • Our high strength materials combined with the new proprietary Process1800 produce an angle bottleneck capillary with superior strength and rigidity, even at very small tip diameters. (
  • If the diaphragm has insufficient strength or insufficient rigidity, the analysis performed by RAM Frame considering a rigid diaphragm is not valid for that structure. (
  • However, the model offsets laboratory-derived strong weakening effects of talc observed in uniform mixtures, implying the governing mechanisms may be the shear localization effect of talc, which is enhanced by its natural platy shape or preimposed layered structure. (
  • Reactivation-induced permeability increase is amplified with increased quartz content before the maturation of shear localization. (
  • We conduct numerical shear experiments on mixtures of quartz and talc gouge using a three-dimensional (3D) distinct element model. (
  • We follow the resulting evolution of ensemble shear strength, slip stability, and permeability of the gouge mixture and explore the mesoscopic mechanisms. (
  • A cellular mechanism that senses shear force at the inner wall of a blood vessel and triggers remodeling that increases the circumference of the wall when a shear force threshold is exceeded would result in the observed scaling of vessel radii described by Murray's Law. (
  • Increased shear strength allows Gaiser Tool Company to produce a more robust, high-strength, small tip diameter, angle-bottleneck capillary. (
  • Simulation results show that talc has a strong weakening effect on shear strength-a thin shear-parallel layer of talc (three particles wide) can induce significant weakening. (
  • The interfacial shear strength between Si microwires and a Nafion membrane has been tailored through surface functionalization of the Si. (
  • The interfacial shear strength between the functionalized Si microwire surfaces and the Nafion matrix was quantified by uniaxial wire pull-out experiments in an in situ nanomechanical instrument that allowed simultaneous collection of mechanical data and visualization of the deformation process. (
  • The shear strength between poly(methyl methacrylate) bone-cement and sand blasted cobalt-chromium and titanium alloy surfaces was measured to investigate the relationship between interfacial shear strength and surface topology. (
  • We found that the interfacial shear strength is directly proportional to the exponent of the surfaces power spectra (P2) and Rdq, but not to Ra and Rr. (
  • The 10%55D sample group had the highest mean bonding shear strength at .5602 MPa, but to observe the aging stability of all sample groups, all combinations were used in Phase II. (
  • The purpose of this study was to evaluate the dentin shear bond strength of four adhesive systems (Adper Single Bond 2, Adper Prompt L-Pop, Magic Bond DE and Self Etch Bond) in regards to buccal and lingual surfaces and dentin depth. (
  • The objective of this study was to compare dentin shear bond strength (DSBS) of dentin bonding agents (DBAs) cured with a plasma arc (PAC) light curing unit (LCU) and those cured with a light emitting diode (LED) LCU. (
  • To evaluate the shear bond strength of brackets fixed with different materials (two light-cured nanofilled low-viscosity resins - Transbond Supreme LV and Flow Tain LV and two light-cured traditional resins - Transbond XT and Transbond Plus Color Change) after 10 min and 24 h, and to evaluate the type of failure. (
  • Thus, the aim of the present study was to evaluate the shear bond strength (SBS) of brackets fixed with different materials (two light-cured nanofilled low viscosity resins - Transbond Supreme LV and Flow Tain LV and two light-cured traditional resins - Transbond XT (control) and Transbond Plus Color Change) after 10 minutes and 24 hours. (
  • In SBS, SD (11.63±2.07MPa) showed statistically lower bond strength than XT (15.16±4.68MPa) but both resins were in the clinically acceptable range. (
  • This system enables us to study the flow induced changes in plasma membrane of a representative cancer cell line HeLa as the function of imparted shear stress and importantly, cell-substrate adhesion strength. (
  • In general: ductile materials (e.g. aluminium) fail in shear, whereas brittle materials (e.g. cast iron) fail in tension. (
  • Then, 4 samples in each sub-group were used to measure shear bond strength using Universal Testing Machine, and 1 sample was examined with Scanning Electron Microscope (SEM). (
  • Furthermore, the hypothesis that the maximum shear force during the cycle of pulsatile flow is constant throughout the arterial system implies that Murray's Law is approximately true. (
  • To determine the implications of the constant shear force hypothesis and to extend Murray's energy cost minimization to the pulsatile arterial system, a model of pulsatile flow in an elastic tube is analyzed. (
  • In order to explore the origins of the invariance of the shear strength with PSD, we analyzed the connectivity, force transmission, and friction mobilization in terms of anisotropies, finding that the constant shear strength is due to a subtle compensation of anisotropies. (
  • Soil shear strength tests are used to determine the load on soil. (
  • The shear strength values obtained by DST and BST were similar, but the differences in the soil effective cohesion intercept parameter were more significant. (
  • A conventional direct shear box was modified to accommodate the testing of an unsaturated soil. (
  • The results illustrate the relationship between suction and shear strength for a glacial till soil. (
  • The shear strength of an unsaturated soil and the soil-water characteristic curve are dependent on soil structure or the aggregation, which in turn is dependent. (
  • The undrained peak and residual strengths are applicable to seismic stability evaluations of slopes comprised of or founded on cohesive soil. (
  • We systematically controlled and varied the size span and the shape of the PSD, and found that the shear strength is independent of both characteristics. (
  • Laboratory and field tests were performed to compare the parameters of shear strength of granite, migmatite, granulite, granitoid, gneiss and rhyolite residual soils from the Brazilian states of Santa Catarina and Rio de Janeiro. (
  • American Society for Testing and Materials: ASTM D3080: Standard Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions. (
  • The paper describes a constant volume ring shear apparatus that allows the measurement of the undrained peak and residual shear strengths of cohesive soils. (
  • No comments were found for Multistage Direct Shear Testing of Unsaturated Soils . (
  • Covers theory, measurement and use of the fundamental properties of unsaturated soils--permeability, shear strength and volume change. (
  • To evaluate, in vitro, the shear bond strength of self-curing (Concise TM - 3M and Alpha Plast - DFL) and light-curing composites (Transbond TM XT - 3M and Natural Ortho - DFL) used in orthodontics bonding, associated to Morelli metal brackets, with further analysis of adhesive remnant index (ARI) and enamel condition in scanning electron microscopy (SEM). (
  • The friction coefficient of thin polymer sheets under high loads can be accounted for by a simple extension of the adhesion theory of friction in which the pressure dependence of the shear strength of the polymer is taken into consideration. (
  • We have shown while transient changes in membrane fluidity depend on the orientation of flow and are largely independent of cellsubstrate adhesion landscape, long term membrane fluidization is controlled by the cell-substrate adhesion strength that is represented by maximum traction stress that cell exerts on the microchannel wall. (
  • Tamal Das, Tapas K. Maiti and Suman Chakraborty, "Flow Shear Induced Changes in Membrane Fluidity: Dependence on Cell- Substrate Adhesion Strength", Current Analytical Chemistry (2013) 9: 9. (
  • Furthermore, most cutting experiments have been conducted using pendulum type apparatus or shearing rig, which may not fully represent the cutting process using reciprocating knives. (
  • A force sufficient to shear the die from its mounting or equal to twice the minimum specified shear strength ( figure 2019-4 ), whichever occurs first, shall be applied to the die using the apparatus of 2 above. (
  • There are a variety of ASTM single-lap-joint shear tests including ASTM D1002 which specifies lap shear for metal to metal, ASTM D3163 for plastics joints, and ASTM D5868 for fiber reinforced plastics (FRP) against itself or metal. (
  • The shear modulus in metals is typically within the range 20 000 to 150 000 MPa indicating a predicted shear stress of 3 000 to 24 000 MPa. (
  • Comparison of Shear Strength Values Derived from Laboratory Triaxial, Borehole Shear, and Cone Penetration Tests. (
  • Evaluation of this body of knowledge has shown that the shear strength gradually increases with increasing percentages of floating particles in unsaturated clays. (
  • Evaluation of Bond Strength of Tack Coat Materials in Field: Development of Pull-Off Test Device and Methodology. (
  • Evaluation of shear bond strength of zirconia-base. (
  • On the other hand, in all the experimental groups in which the chlorhexidine varnish was applied as a layer on the etched enamel surface or over the sealant, shear bond strength values and bracket failure rates were of a magnitude that made them clinically unacceptable. (