Materials Literature
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Thirty new asymmetric diphenyl-diacetylene (PTTP) liquid-crystal homologs are synthesized and their physical properties characterized. In addition to the observed high birefringence and relatively low viscosity, several dialkyl PTTP homologs also possess a low melting point, wide nematic range, and low heat of fusion…
We report the formulation of a solid gel network from purely liquid emulsion droplets. The gel remains rigid at droplet volume fractions as low as ${10}^{\mathrm{\ensuremath{-}}3}$. The gelation process is identified as diffusion-limited cluster aggregation. We find a surprising order in the gel structure. This orderi…
Calcium carbonate (CaCO3) minerals are known to be deposited in a wide array of different organisms, ranging from microbes to vertebrates [(1989) On Biomineralization, Oxford University Press, New York]. Calcite, aragonite and vaterite are the major crystalline structural polymorphs of CaCO3 associated with living sys…
The dynamics of phase separation in binary systems containing surfactants is investigated by means of a time-dependent Ginzburg-Landau model. The Langevin equations for two scalar fields are solved numerically in two spatial dimensions. One of these fields is the order parameter representing the local difference in th…
The orientational order in simple systems of dipolar hard-core molecules is determined by Monte Carlo simulations. Dipolar hard spherocylinders are shown to form a monolayer smectic-A phase with unpolarized layers. In the columnar phase of dipolar cut spheres, evidence is given for a transition, with increasing dipole…
A computational method has been developed for generating graphitic carbon structures on an arbitrary smooth surface and with a given number of carbon rings. Using both periodic and random surfaces for constraint, many extended graphitic carbon structures have been generated. The energy relative to graphite and the bul…
The authors present detailed numerical results from a computationally efficient cell dynamical system model of domain growth in binary alloys with quenched disorder. Their numerical results suggest that the domain growth law for the disordered case is compatible with (R)(t) approximately (1nt) x , where x has a weak d…
Abstract Epoxidized natural rubber (ENR) with a 25 mol % epoxide content has been chlorinated or brominated in halogenated solvents. The structures of the resulting polymers have been studied by infrared spectrophotometry, and their thermal behavior, by TGA and DSC, and compared with that of chlorinated and brominated…
The role of water in lipid oxidation is examined. The water activity of a system influences lipid oxidation rates. At both very high and very low water activities, lipid oxidation rates are high compared to the rate at intermediate water activities. Glass transition theory may also be used to understand lipid oxidatio…
Abstract Poly(dimethylsiloxane) elastomers that had been filled with in situ precipitated silica were studied by thermogravimetric analysis, under nitrogen and in air. Both types of measurements indicated that the filler raises the temperature of thermooxidative degradation of the polymer, possibly by inactivating the…
Abstract A procedure is described for preparing fairly uniform spheres of three different nylon polymers by phase separation. The mean diameter and polydisperse index were 5 μm and 1.056 for Griltex nylon, 5.7 μm and 1.046 for nylon 6/6, and 12.9 μm and 1.016 for nylon 6. The phase separation is done by taking a 1 wt…
Abstract Chemical structures of cellulose and chitosan dissolved in trifluoroacetic acid (TFA) and those of cellulose and chitosan films cast from their TFA solutions were studied by 13 C‐NMR and infrared (IR) spectroscopy. Cellulose is trifluoroacetylated selectively at the C6–hydroxyl groups in the TFA solution, and…
Abstract Blend membrane consisting of poly(vinyl alcohol) (PVA) and chitosan was prepared from a solvent‐casting technique and characterized for their intermolecular interactions using infrared and X‐ray diffraction methods. Cross‐linking the blend with glutaraldehyde produces a membrane with lower crystallinity and a…
<div class="htmlview paragraph">Nickel and silver-metal hydride batteries are being developed for aerospace applications by Eagle-Picher. Metal hydride batteries offer a number of advantages over other aerospace battery systems. Nickel-metal hydride batteries have twice the gravimetric energy density of nickel-c…
Using the density-functional theory, norm-conserving pseudopotentials and plane-wave expansions the authors have calculated ab initio the equation of state and the principal phonon modes in boron phosphide, including their pressure dependence and the amplitude of the eigendisplacements. Good agreement with experiment…
The concentration profiles of carboxy-terminated polystyrene chains in the melt grafted onto oxide-covered silicon substrates were measured using secondary-ion mass spectroscopy. The grafting density increased with temperature and an enthalpy of +7.4 kcal/mole was deduced for the grafting reaction, SiOH+R(COOH)\ensure…
<div class="htmlview paragraph">A long-term thermal energy storage system has been implemented at the University of Utrecht campus in the Netherlands. The project will extend co-generation operation into the summer beyond heat demand periods, resulting in increased electricity generation. The stored heat (90 °C)…
We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) on the layered compound 1-T-${\mathrm{TiTe}}_{2}$, whose low-energy properties are those of a normal metal, and analyzed the experimental line shapes in terms of the Fermi-liquid self-energy. We find excellent agreement between the mea…
Magnetization measurements at ambient pressure on \ensuremath{\kappa}-(ET${)}_{2}$Cu[N(CN${)}_{2}$]Cl, an organic salt that is superconducting under pressure (${\mathit{T}}_{\mathit{c}}$=12.8 K at 0.3 kbar), reveal an antiferromagnetic transition near 45 K and, for the first time in this class of materials, a transiti…
We report on micro-Raman spectroscopy studies of porous silicon which show an amorphous silicon Raman line at 480 R cm−1 from regions that emit visible photoluminescence. A Raman line corresponding to microcrystalline silicon at 510 R cm−1 is also observed. X-ray photoelectron spectroscopy data is presented which show…