Sticking Effect of a Tackifier on the Fibrillation of Acrylic Pressure-Sensitive Adhesives.

In this study, the effect of a tackifier on the viscoelastic and adhesion properties of acrylic pressure-sensitive adhesives (PSAs) was investigated. The intermediate products in the process of PSA synthesis, including an acrylate-based copolymer solution, a cross-linked copolymer, and the final product with a tackifier, were prepared and characterized using dynamic mechanical analysis (DMA). A significant increase in storage and loss moduli at high angular velocities was observed for the final product with the tackifier.

Scaling effect on the detachment of pressure-sensitive adhesives through fibrillation characterized by a probe-tack test.

This study extensively investigates the fibrillation process of a pressure-sensitive adhesive (PSA) using a probe-tack test. It was conducted using a glass sphere at the millimeter scale for various thicknesses of PSA layers laminated on a glass substrate, on various contact areas. A sharp decrease in the adhesion force caused by cavity growth was confirmed in the case of large contact areas, whereas cavities were not generated in the case of small contact areas on the thick PSA layer.

Characterization of Tack Strength Based on Cavity-Growth Criterion.

The adhesive force generated by a small short-term pressure, called tack, is measured by a probe tack test on pressure-sensitive adhesives (PSAs); the maximum force is evaluated by cavity growth at the interface between the PSA layer and the probe surface. As the PSA layer becomes thinner, it is more difficult to measure the tack with a cylindrical probe because of the uneven contact resulting from misalignment. A spherical probe is preferable to obtain reproducible contact on the PSA layer, but the contact area should be taken into account if the contact pressure affects the tack performance.

Requirement of LIM domains for the transient accumulation of paxillin at damaged stress fibres.

Cells recognize and respond to changes in intra- and extracellular mechanical conditions to maintain their mechanical homeostasis. Linear contractile bundles of actin filaments and myosin II known as stress fibres (SFs) mediate mechanical signals. Mechanical cues such as excessive stress driven by myosin II and/or external force may damage SFs and induce the local transient accumulation of SF-repair complexes (zyxin and VASP) at the damaged sites.

Forced extension of delipidated red blood cell cytoskeleton with little indication of spectrin unfolding.

Force-extension curves obtained on intact human red blood cells (RBC) were compared with those of delipidated RBCs to assess the contribution of cytoskeletal flexibility to the extensibility of the intact membrane skeleton. The RBCs were first delipidated by treatment with phospholipase A₂; tensile properties of the exposed cytoskeletal structures were measured using an atomic force microscope (AFM). The AFM probes were modified either with the Band 3 specific lectin, concanavalin A, (Con A) or anti-F-actin antibody, to localize the point of interaction between the probe and the cytoskeleton.

Nonlinear displacement of ventral stress fibers under externally applied lateral force by an atomic force microscope.

Actin-based stress fibers (SFs) have fundamental importance in the maintenance of mechanical stability of living cells. Several in vitro measurements of their elastic properties have therefore been made, but direct mechanical manipulation of individual SFs in vivo for the determination of their mechanical properties has not been attempted. No less important is a search for the possible formation of a global mechanical network involving SFs and other intracellular filamentous components.

Effect of initial stress on Love waves in a piezoelectric structure carrying a functionally graded material layer.

The effect of initial stress on the propagation behavior of Love waves in a piezoelectric half-space of polarized ceramics carrying a functionally graded material (FGM) layer is analytically investigated in this paper from the three-dimensional equations of linear piezoelectricity. The analytical solutions are obtained for the dispersion relations of Love wave propagating in this kind of structure with initial stress for both electrical open case and electrical short case, respectively. One numerical example is given to graphically illustrate the effect of initial stress on dispersive curve, phase velocity and electromechanical coupling factor of the Love wave propagation.

Propagation of thickness-twist waves in a piezoelectric ceramic plate with unattached electrodes.

We analyze the propagation of thickness-twist waves in an unbounded piezoelectric ceramic plate with air gaps between the plate surfaces and two electrodes. These waves are also called anti-plane or shear-horizontal waves with one displacement component only. An exact solution is obtained from the equations of the linear theory of piezoelectricity.

Transverse surface waves in a layered structure with a functionally graded piezoelectric substrate and a hard dielectric layer.

As to an ideally layered structure with a functionally graded piezoelectric substrate (material parameters change continuously along the thickness direction) and a hard dielectric layer, the existence and propagation behavior of transverse surface waves is studied by analytical technique. The dispersion equations for the existence of the transverse surface waves with respect to phase velocity are obtained for electrically open and short circuit conditions, respectively. A detailed investigation of the effect of gradient coefficient on dispersion relation, electromechanical coupling factor and penetration depth is carried out.

Investigation of scattering of elastic waves by cylinders in 1-3 piezocomposites.

The scattering behavior of P-waves in piezoelectric composites with 1-3 connectivity is studied. The method of wave function expansion is adopted for the theoretical derivations. Analytical expressions are obtained for the distributions of mechanical displacement in z-direction along the circumferences of piezoelectric cylinders.