Materials Literature
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The information required from optical assessment of nonlinear organic materials differs widely depending on the application envisaged for the material in question. Accordingly, a suitable assessment scheme must be devised which will give a reliable indication of the promise of these materials in a wide variety of appl…
The quest for more efficient nonlinear optical materials of increased optical quality is being spurred by the development of optical communication systems that require ultrafast broad band optical signal processing functions. Conversely, nonlinear optical phenomena enlarge traditional spectroscopic approaches to encom…
Atomic force microscopy was used to obtain images of lysozyme crystals growing in their native solution environment. The authors growth by both two-dimensional nucleation and screw dislocation mechanisms. Nucleation centres appeared to occur randomly over the surface, and were uncorrelated from layer to layer. Surface…
Phenytoin crystal growth kinetics have been measured in phosphate buffer as a function of pH, supersaturation, and temperature. Incorporation of growth units into the crystal lattice is controlled by surface integration and follows a screw-dislocation mechanism. This mechanism explains the observed dependence of growt…
The underlying crystal-growth theory and structural molecular chemistry important in the understanding of the methodology behind the theoretical prediction of crystal morphology is presented together with its application to the molecular solid benzophenone. Benzophenone crystallizes in the orthorhombic space group P2…
Tailor-made molecular auxiliaries for the control of nucleation and growth of molecular crystals may be classified into two broad categories: inhibitors and promoters. Tailor-made inhibitors of crystal growth can be used for a variety of purposes which include morphological engineering, reduction of crystal symmetry,…
Polymorphism has critical implications in material design of organic crystals for elucidating specific functions in optics, pharmaceuticals, foods, biology etc. This is because diversified properties are revealed in polymorphic modifications. Depending on the selection of the specific polymorphs, one has to deal with…
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…