Optical birefringence measurements were used to observe the isothermal relaxation of rubbed polystyrene films on silica substrates below the glass transition temperature. The relaxation dynamics were described by the Kohlrausch–Williams–Watts relaxation function with Arrhenius temperature dependence on relaxation time. The isothermal results were in good agreement with results obtained using a ...

The qualitative effect of nonuniform temperature gradient on the linear stability analysis of the Rayleigh-Benard convection problem in a Boussinesquian, viscoelastic fluid-filled, high-porosity medium is studied numerically using the single-term Galerkin technique. The eigenvalue is obtained for free-free, free-rigid, and rigid-rigid boundary combinations with isothermal temperature conditions...

We report a dynamical-mechanical study of stress relaxation at small deformation in a natural (polyisoprene) rubber well above its glass transition temperature Tg. We find that an almost complete relaxation of stress takes place over very long relaxation periods, even though the elastic network is retained. The relaxation rate and the long-time equilibrium modulus are sensitive functions of tem...

in this study, the effect of nano-silver (ag) treatment on the drying rate and final moisture gradient of poplar wood was investigated. poplar (populous nigra) boards with green dimensions of 100×70×50 and 20 mm were treated with nano-silver (ag) suspension by spraying and immersion method. two concentrations of nano-silver suspension, including 20 and 100 ppm were used. then, the boards were c...

OBJECTIVE To evaluate changes in left ventricular function and the impact of ventricular hypertrophy and pressure gradient early and late after aortic valve replacement in patients with isolated aortic stenosis. DESIGN 41 patients with isolated aortic stenosis and normal systolic function underwent cross sectional and Doppler echocardiography two months before and two weeks and four years aft...

The temperature dependence of the chlorine NQR spin-lattice relaxation time T ^ w a s observed for trimethylsulfonium hexachlorometallates(IV), [(CH3)3S]2MC16 (M = Pt, Sn), trimethylammonium hexachlorostannate(IV), [(CH3)3NH]2SnCl6, and tetramethylphosphonium hexachlorostannate(IV), [(CH3)4P]2SnCl6. The quadrupolar relaxation in [(CH3)3NH]2SnCl6 and [(CH3)4P]2SnCl6 can be described by the usual...

thermo-elasto-plastic analyses of thick-walled spherical tanks made of functionally graded materials are investigated analytically. these tanks are subjected to positive or negative temperature gradient and internal pressure loadings separately or simultaneously. the power law modeling has been used for through-the-thickness variation of mechanical properties. von mises yield criterion and elas...

Molecular dynamics simulation was used to calculate rotational relaxation time, diffusion coefficient, and zero-shear viscosity for a pure aromatic compound (naphthalene) and for aromatic and aliphatic components in model asphalt systems over a temperature range of 298-443 K. The model asphalt systems were chosen previously to represent real asphalt. Green-Kubo and Einstein methods were used to...

Temperature-dependent dynamics of phonon-assisted relaxation of hot carriers, both electrons and holes, is studied in a PbSe nanocrystal using ab initio time-domain density-functional theory. The electronic structure is first calculated, showing that the hole states are denser than the electron states. Fourier transforms of the time-resolved energy levels show that the hot carriers couple to bo...