Materials Literature
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Ferroelectric polymers are reviewed with special interest in the polarization reversal and phase transition behavior of VDF copolymers. The ferroelectric phase consists of all-trans molecules packed in a parallel manner. Its spontaneous polarization is reversed at very high fields by eventual 180° rotations of individ…
The apoenzyme of wild-type (WT) dihydrofolate reductase (DHRF) from Escherichia coli exists in two conformational states, Et and Ew, which differ in affinity for NADPH and in kinetic competence. Dissociation constants for the binary complex of NADPH with the two conformers differ by over 100-fold (KDt = 0.17 microM, K…
A wide aperture liquid crystal polarized light source (LC-PLS) is presented which converts unpolarized-into circular- and/or linearly polarized light with an efficiency better than 80%. Moreover, new operating modes for electro-optical field-effects on which liquid crystal displays (LCDs) are based are shown to increa…
A different approach to study the viscosity of concentrated suspensions is proposed. It is based on percolation theory. It is suggested that at the critical concentration of fillers, ${\mathrm{\ensuremath{\varphi}}}_{\mathit{c}}$ a macroscopic interconnected cluster (secondary structure) of fillers is formed. This clu…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLiquid-crystalline polymers containing heterocycloalkanediyl groups as mesogens. 8. Morphological evidence for microphase separation in poly(methylsiloxane-co-dimethylsiloxane)s containing 2-[4-(2(S)-methyl-1-butoxy)phenyl]-5-(11-undecanyl)-1,3,2-dioxaborinane side groupsV.…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe fractal nature of 1-step highly-branched rigid rodlike macromolecules and their gelled-network progeniesS. M. Aharoni, N. S. Murthy, K. Zero, and S. F. EdwardsCite this: Macromolecules 1990, 23, 9, 2533–2549Publication Date (Print):April 1, 1990Publication History Publis…
The crystallography and atomic structure of inversion twin boundaries were studied in polycrystalline ZnO using conventional transmission electron microscopy and high‐resolution electron microscopy. Inversion twin boundaries. In order to determine the atomic structure of the inversion twin boundary, high‐resolution tr…
The measurement of the longitudinal speed of sound in crystals of ribonuclease-A and in human haemoglobin using laser-generated ultrasound is reported. Average values of 1784 (72) m s-1 and 1828 m s-1 were obtained. As a control the speed of sound transmitted through a compacted disc of lysozyme powder was measured as…
FIT is an interactive computer program for fitting analytical models to powder diffraction patterns and to pair correlation functions. FIT has been written in Turbo C and runs on IBM XT/AT or compatible personal computers.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReaction of hydroxide ion with manganese(III) tetramesitylporphyrin and the oxidation states of manganese tetramesitylporphyrinsRamesh D. Arasasingham and Thomas C. BruiceCite this: Inorg. Chem. 1990, 29, 7, 1422–1427Publication Date (Print):April 1, 1990Publication History…
The approach described by Bricogne & Gilmore [Acta Cryst. (1990). A46, 284-297] (I) is applied to three small organic molecules. Phase extension for sucrose octaacetate (C28H38O19) from a basis set of 300 correctly phased U magnitudes confirms the stability of the exponential modelling and plane-search algorithms unde…
The later-stage spinodal decomposition (SD) of polymer mixtures at deep quenches were investigated by time-resolved light scattering. The scaled structure factor F(x)≡qm (t,T)3I(x) with x≡q/qm (t,T) was analyzed as a function of time t or reduced time τ during the SD at various temperatures T’s, where qm (t,T) is the…
The feasibility of making multilayer optical filters using polymerized solgel solutions was demonstrated. Theoretical modeling was done to determine the expected optical response of multilayer coatings with various index profiles to select a coating design which was achievable using current technology and which would…
Abstract Stable, three-dimensionally ordered complexes were formed from synthetically hydrated, highly ordered kaolinite (d(001) = 8.4 Å) and several organic compounds. Removal of the intercalated organic compound by drying or by water washing recovered the 8.4-Å hydrate with its ordered layer stacking essentially unc…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular encapsulation of transition-metal complexes in cyclodextrins. 1. Synthesis and x-ray crystal structure of [(.eta.5-C5H5)Fe(.eta.6-C6H6)]PF6.cntdot.2.alpha.-CD.cntdot.8H2OBernd Klingert and Grety RihsCite this: Organometallics 1990, 9, 4, 1135–1141Publication Date (…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh-resolution solid-state carbon-13 nuclear magnetic resonance study of polybenzimidazole/polyimide blendsJanusz Grobelny, David M. Rice, Frank E. Karasz, and William J. MacKnightCite this: Macromolecules 1990, 23, 8, 2139–2144Publication Date (Print):April 1, 1990Publicat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT.pi.-Bonding in four-coordinate aluminum aryloxide compoundsMatthew D. Healy, Joseph W. Ziller, and Andrew R. BarronCite this: J. Am. Chem. Soc. 1990, 112, 8, 2949–2954Publication Date (Print):April 1, 1990Publication History Published online1 May 2002Published inissue 1 Apr…
Glasses having the composition (AgI${)}_{\mathit{x}}$-(${\mathrm{Ag}}_{2}$O-n${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$${)}_{1\mathrm{\ensuremath{-}}\mathit{x}}$, where x is in the range from 0 to 0.7 and n is either 1 or 2, have conductivities as high as ${10}^{\mathrm{\ensuremath{-}}2}$ S/cm at room temperature. NMR line-…
Tetraarylporphyrins substituted with nitro groups at beta-pyrrolic positions are potential candidates for electron-accepting pigments in model systems for photosynthesis. The photophysics of 2-nitro-5,10,15,20-tetra-p-tolylporphyrin and its zinc analog have been studied in order to evaluate this potential. The ground…
Several new classes of low polarity, low viscosity and optically weakly anisotropic two and three ring fluorinated liquid crystals with alkenyl side chains are presented. Synergisms which lead to a number of favourable material properties are shown to result from systematic changes of (a) para and lateral fluorination…