Materials Literature
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We present results of large-scale molecular dynamics simulations of hard sphere systems at values of the volume fraction $\ensuremath{\varphi}$ along the disordered, metastable branch of the phase diagram up to random close-packing ${\ensuremath{\varphi}}_{c}$. By quantifying the degree of local order, we determine th…
The shapes of isolated Bok globules and embedded dense cores of molecular clouds are analyzed using a nonparametric kernel method, assuming the alternate hypotheses that they are randomly oriented prolate objects or that they are randomly oriented oblate objects. In all cases, the prolate hypothesis gives a better fit…
We report here on the size-dependent kinetics of exciton recombination in a III–V quantum dot system, InP. The measurements reported include various frequency dependent quantum yields as a function of temperature, frequency dependent luminescence decay curves, and time-gated emission spectra. This data is fit to a thr…
The coupling model of Ngai et al. [K. L. Ngai, Disorder Effects in Relaxation Processes, edited by R. Richert and A. Blumen (Springer-Verlag, Berlin, 1994)] is applied to treat polymer dynamics in solution. Important dynamic quantities considered here include the zero-shear viscosity η and the light-scattering spectru…
Magnetic materials normally exhibit a smooth response to external fields, but recent experiments reported in Physical Review Letters yield stepwise response curves. In his Perspective, Chudnovsky discusses the results, which may be evidence for quantum behavior on a macroscopic scale.
The interaction of nitric oxide (NO) with an Ir(111) surface has been studied with supersonic molecular beam techniques and electron energy loss spectroscopy. Initial adsorption probability S0, measurements as a function of incident kinetic energy Ei, surface temperature Ts, and angle of incidence θi reveal that separ…
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…