Materials Literature
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A new lattice model for Monte Carlo simulations of dense polymer melts, developed in the spirit of Verdier–Stockmayer algorithm on square and simple cubic lattices, is presented. By introducing diagonals of squares and cubes as bonds, the lattice model acquires a large number of configurations and wiggling local moves…
Two switchable, mesoscopically periodic materials were created by combining crystalline colloidal array (CCA) self-assembly with the temperature-induced volume phase transition of poly(N-isopropylacrylamide) (PNIPAM). Body-centered-cubic CCAs of hydrated, swollen PNIPAM particles Bragg-diffract infrared, visible, and…
This work experimentally and theoretically investigates the use of bifunctional initiators in the synthesis of high-impact polystyrene (HIPS). The experimental design involved a series of nonisothermal bulk polymerizations of styrene (St) in the presence of polybutadiene (PB). The performance of three commercial initi…
Noncompatibilized and compatibilized blends of nylon 1010/PP blends having five different viscosity ratios were prepared by melt extrusion. Glycidyl methacrylate-grafted-polypro-pylene (PP-g-GMA) was used as the compatibilizer to enbance the adhesion between the two polymers and to stabilize the blend morphology. The…
It is now some 15 years since atomic clusters were first produced and investigated in laboratories. Since then, knowledge concerning clusters has enjoyed rapid and sustained growth, and cluster research has become a new branch of science.
We present a theory for the ab-initio computation of NMR chemical shifts (sigma) in condensed matter systems, using periodic boundary conditions. Our approach can be applied to periodic systems such as crystals, surfaces, or polymers and, with a super-cell technique, to non-periodic systems such as amorphous materials…
Langsames Sublimieren von 1, einem Dithiadiazolylradikal, führt zu Kristallen der β‐Phase, dieser Verbindung (Raumgruppe Fdd 2), in der die kettenförmig angeordneten Moleküle durch starke intermolekulare CN … S‐Wechselwirkungen zusammengehalten werden. Unterhalb von 36 K weist die Verbindung ein spontan entstandenes m…
One of main requirements in the design of a thermoelectric module is to determine the optimum module geometry, based upon available thermoelectric material and manufacturing technology, which meets the given application specifications. In order to assist in determining the appropriate module geometry for thermoelectri…
Lattice constants and bulk moduli of eleven cubic III-V semiconductors are calculated using an ab initio scheme. Correlation contributions of the valence electrons, in particular, are determined using increments for localized bonds and for pairs and triples of such bonds; individual increments, in turn, are evaluated…
A model has been developed which describes the process of substrate-temperature-dependent diamond film growth. Detailed calculations were performed for the dependence of the diamond growth rate on the substrate temperature and the flux ration of hydrogen- and carbon-containing species above the surface. The theoretica…
In this letter, we report the results of copper-doped porous silicon. In the photoluminescence spectrum of porous silicon without Cu doping, only one red luminescence band appears with a peak at 676.5 nm; while in the photoluminescence spectrum of Cu-doped porous silicon, red and near infrared luminescence bands appea…
Controlled slow-speed microcutting tests were made on single crystal silicon. Micro-Raman spectroscopy confirmed the presence of amorphous silicon within the microcutting grooves as well as in the debris particles removed from the grooves. These results indicate that pressure-induced transformation to metallic silicon…
The observation of an incommensurate diffraction pattern in urea inclusion compounds by neutron diffraction is reported. It reveals for the first time in these compounds the existence of all kinds of reflections expected for an intermodulated composite. The superspace analysis together with the temperature evolution o…
The principles of operation of a microelectromechanical (MEMS)-based magnetometer designed on the magnetoelastic effect are described. The active transduction element is a commercial (001) silicon microcantilever coated with an amorphous thin film of the giant magnetostrictive alloy Terfenol-D [(Dy0.7Te0.3)Fe2]. In ad…
A computer simulation of amorphous ${\mathrm{SiO}}_{2}$, with a potential which includes formal ionic charges and an explicit account of polarization effects, produces a calculated infrared spectrum in good agreement with experiment. The polarization effects play a crucial role in reproducing the observed network vibr…
Dendritic crystal growth in a pure undercooled melt is simulated quantitatively in three dimensions using a phase-field approach. The classic parameter ${\ensuremath{\sigma}}^{*}$ that characterizes the dynamically selected operating state of the dendrite tip as well as the full nonaxisymmetric tip morphology are dete…
A rigorous connection is established between the local porosity entropy introduced by Boger et al. (Physica A 187, 55 (1992)) and the configurational entropy of Andraud et al. (Physica A 207, 208 (1994)). These entropies were introduced as morphological descriptors derived from local volume fluctuations in arbitrary c…
The domain size and the ac-hysteresis of NiZn-ferrites have been investigated as a function of grain size. It is found that the ac-hysteresis or energy dissipation at MHz frequencies is substantially reduced in fine-grained, monodomain NiZn-ferrites, which is attributed to the absence of intragranular domain walls.
Microfibrillated cellulose (MFC)-collagen composite films were prepared with a dispersion of acid swollen collagen fibers and carboxylated MFC at different ratios in an alkaline homogenous system. The surface topographic results obtained from SEM analyses indicated that the MFC entangled uniformly with collagen in the…
Crosslinked high-density polyethylene piping is currently in use for carrying pressurized hot water, chemicals, and waste. Hot and cold drawing processes, above and below melting, were studied and compared aiming at improving the pipe's toughness, strength, and creep resistance. Initially, the tensile behavior as func…