Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Protein and virus crystals commonly grown in the laboratory on earth have also been grown in a microgravity environment on the US Space Shuttle. Two techniques for growth of the crystals were investigated: vapour diffusion and direct liquid-liquid diffusion. Crystals produced in microgravity, although generally isomor…
The production of uniform fine crystalline particles is highly desirable for pharmaceutical products in order to enhance stability and dissolution rates and, thereby, to favour high bioavailability. Precipitation under high-supersaturation conditions favours nucleation over growth processes and will result in smaller…
The effect of solvent in crystallization of polymorphs has been studied using the drug sulphathiazole as a model compound. The solubilities of the four polymorphic forms of sulphathiazole were determined as a function of temperature in various solvents. Within the temperature ranges studied, the rank order of solubili…
The light scattering properties of polymer-dispersed liquid crystal (PDLC) films depend on several aspects of the film structure and nematic alignment. In this study we gauge the relative importance of some of these factors by varying the structure and properties of PDLC films in a systematic way, and measuring the va…
Abstract The emulsification and electrodeposition properties of mixtures of polyoxypropylene‐(POP) modified cationic epoxy resin (III) and nonionic trimethylolpropane–toluene diisocyanate–2‐ethylhexanol (TMP–TDI–2EH, V) were investigated and the compositions of their electrodeposited films were obtained by Fourier Tra…
Abstract The development of early colour and the dehydrochlorination rate were compared for poly(vinyl chloride) samples obtained by suspension polymerization using two different initiators, dicetylperoxydicarbonate and butylperoxyneodecanoate. The degree of discolouration was measured on pressed plates and expressed…
The structures of the three phases of DBr and DI were determined using neutron powder profile techniques. The highest temperature phases are cubic, Fm3m, with the deuteriums in twelvefold disordered positions about the halogens. The intermediate temperature phases are orthorhombic, Cmca, with the deuteriums in twofold…
We report on complete wave-front control with amplitude- and phase-modulation liquid-crystal devices (LCD's). A twisted nematic device is used for amplitude modulation, and an electrically controlled birefringent device is used for phase modulation. Because the LCD's are optically coupled with afocal optics and are dr…
Triple-axis X-ray scattering measurements of diffuse scattering in NaNO 3 are described. NaNO 3 undergoes a structural phase transition at 549 K which results in the appearance of a superlattice reflection at the Z-point of the high-temperature Brillouin zone. However, strong diffuse scattering was observed in the low…
We report on the effect of cooling rate on the crystallographic orientation and ferroelectric properties of PbZr0.2Ti0.8O3 (PZT) thin films grown on a lattice matched bottom electrode such as c-axis oriented Y-Ba-Cu-O (YBCO). The cooling rate from deposition temperature influences the crystallographic orientation of t…
Spatially resolved electron energy loss spectroscopy has been performed on single, H-terminated, Si nanocrystals in the size range 25--500 \AA{}. The particles were prepared via the gas-phase photolysis of a dilute ${\mathrm{Si}}_{2}$${\mathrm{H}}_{6}$/He mixture in a gas flow cell, and deposited on a holey carbon gri…
Bulk icosahedral-quasicrystalline aluminum-palladium-rhenium alloys of high structural quality and thermal stability are found to exhibit low-temperature electrical resistivities that are four orders of magnitude larger than those found in disordered metals and metallic glasses. Experiments suggest that these quasiper…
There is increasing interest in the use of metal-containing compounds in medicine. This review describes several therapeutic applications, such as the use of platinum complexes in cancer chemotherapy, gold compounds in the treatment of arthritis, gallium in hypercalcemia, bismuth in anti-ulcer medication, and sodium n…
Abstract A multistage melt polycondensation of bisphenol‐A and carbonate has been studied experimentally using LiOH·H 2 O catalyst. The reaction process consists of batch and semi‐batch periods with different temperature and pressure conditions. It was observed that a small amount of diphenyl carbonate lost from the r…
Abstract A method has been developed for measuring infrared spectra during the mechanical deformation of yarns. This rheooptical technique was applied to study the molecular processes that take place along the stress‐strain curve of PET yarns. The results were combined with data obtained from size exclusion chromatogr…
Abstract Polymer blends of poly(ethylene terephthalate) (PET) and polystyrene (PS) are immiscible and incompatible, which has been well recognized. Styrene–glycidyl methacrylate (SG) copolymer has been synthesized by suspension polymerization and employed in this study as an in situ compatibilizer for the polyblends o…
Abstract Acrylonitrile (AN) was copolymerized with acrylic acid (AA), methacrylic acid (MAA), and itaconic acid (IA) by the aqueous suspension method at 40°C with ammonium persulfate and sodium metabisulfite as the redox initiator. The reactivity ratios for the AN–AA and AN–IA systems were also calculated by the Finem…
Transition state theory is frequently used to describe interstitial diffusion in solids. A basic assumption in this theory is that equilibrium statistical mechanics can be used to characterize the different configurations in the transition state, the region in configuration space which acts as a bottleneck for the mot…
We have observed up to 8 orders (n) in the spectra of parametric x-radiation (PXR) in the range 5--40 keV, produced by the interaction of a 90 MeV electron beam with mosaic graphite and single silicon crystals. The measured yields and intensity ratios, I(n\ensuremath{\ge}2)/I(n=1), in graphite are not in agreement wit…
Using synchrotron radiation and an imaging plate the authors have performed a high-angular-resolution powder X-ray diffraction study of the 'distorted FCC' high-pressure phase of praseodymium. The crystal structure of this phase is identified as the trigonal space group R3m (D 3d 5 ) with eight atoms in the rhombohedr…