OBJECTIVES To assess the re-hardening potential of enamel matrix derivatives (EMD) and self-assembling peptides in vitro, hypothesizing that these materials may increase the mineralization of artificial carious lesions and improve hardness profiles. MATERIAL AND METHODS Forty-eight enamel samples were prepared from extracted bovine lower central incisors. After embedding and polishing, nail v...

Classical plasticity and damagemodels for porous quasi-brittle media usually suffer from mathematical defects such as non-convergence and nonuniqueness. Yield or damage functions for porous quasi-brittle media often have yield functions with contours so distorted that following those contours to the yield surface in a return algorithm can take the solution to a false elastic domain. A steepest-...

Micro-electro-mechanical systems or MEMS are used in a variety of today’s technology and can be modeled using equations for nonlinear damped harmonic oscillators. Mathematical expressions have been formulated to determine resonance frequency shifts as a result of hardening and softening effects in MEMS devices. In this work we experimentally test the previous theoretical analysis of MEMS resona...

Brillouin scattering experiments are carried out to study the surface acoustic waves in Nd0.5Sr0.5MnO3 as a function of temperature in the range of 40–300 K covering the metal-insulator and charge-ordering phase transitions. The surface modes include surface Rayleigh wave, pseudo-surface acoustic wave (PSAW) and high velocity PSAW. The observed softening of the sound velocities for the surface ...

1.1 Characteristic phase dependance between direct forcing and parametric amplified forcing phase. Plotted is gain vs. phase at resonance for a 2.1 Simulated response of a parametrically resonant system under two driving conditions. The drive signal is shifted by pi-radians. The physical response, displacement is plotted here, is identical as driven by the two signals. Thus, phase shifting the ...

Despite research spanning several decades, the exact value of the shear modulus Gs of the erythrocyte membrane is still ambiguous, and a wealth of studies, using measurements based on micropipette aspirations, ektacytometry systems and other flow chambers, and optical tweezers, as well as application of several models, have found different average values in the range 2-10μN/m. Our study shows t...

The addition of cobalt was experimentally observed to increase the strength and impact toughness of Cu precipitation hardened steel. In order to understand the mechanism of this strengthening, we studied the effect of cobalt in the bulks and surfaces of bcc Fe and bcc Cu, as well as at the Fe/Cu interface by ab initio density-functional approach. We investigated the cobalt distribution between ...

Plane strain transient finite thermomechanical deformations of heat-conducting functionally gradient materials comprised of tungsten and nickel–iron matrix are analyzed to delineate brittle/ductile failures by the nodal release technique. Each material is modeled as strain-hardening, strain-rate-hardening and thermally-softening. Effective properties are derived by the rule of mixtures. At nomi...

There are more and tunnel projects in the karst-developed areas Southwest China. Affected by karst caves water, tunnels often experience geological disasters such as local collapses water inrush. A simplified rock stress hardening-softening model was established based on triaxial compression test results of two kinds carbonatite to accurately analyze deformation inrush characteristics surroundi...