Materials Literature
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Abstract Alkali (R)- and (S)-mandelates can change the helical pitch of cholesteric liquid crystals containing steroidal crown ethers in an enantioselective manner. In certain cases the pitch difference between (R)- and (S)-mandelates can be detected visually as a color change in the liquid crystals.
Deep photoresist gratings, slanted as well as unslanted, were produced holographically in clear Shipley 1400 photoresist. The diffraction efficiencies of these gratings were measured as a function of incident angle for three wavelengths with polarization perpendicular to the plane of incidence. It is shown that the re…
Simultaneous measurements of the gyration, birefringence, and rotation angle of the optical indicatrix of Rochelle salt were successfully performed by using high-accuracy universal polarimetry. The three phases of the crystal were found to be optically active. It was revealed that the origin of ferroelectricity of the…
A refinement of a simplified method, based on line-beam response functions, is presented for performing skyshine calculations for shielded and collimated gamma-ray sources. New coefficients for an empirical fit to the line-beam response function are provided and a prescription for making the response function continuo…
We study bond-orientational order in liquid Si via Monte Carlo simulation in conjunction with empirical two- and three-body potentials of the form proposed by Stillinger and Weber. Bond-orientational order (BOO) is described in terms of combinations of spherical harmonic functions. Liquid Si is found to have pronounce…
New polyesters containing thianthrene tetraoxide were synthesized by the interaction of 2,7-dichloroformylthianthrene-5,5′,10, 10′-tetraoxide with 2,5-bis(p-hydroxybenzylidene)cyclopentanone, 2,5-divanillylidenecyclopentanone, 2,6-bis(p-hydroxybenzyiidene)-cyclohexanone, 2,6-divanillylidenecyclohexanone, and 2,7-bis(p…
We compared two different formulations, the electron-field and electron-electron models, for electron-plasmon scattering in bulk semiconducting materials. The calculations employ three different expressions for the plasmon dispersion relation and are made at two different temperatures. It is found that the functional…
Abstract In this work three different techniques were used to determine the crystallinity of polyethylene. After different pretreatment HDPE, LLDPE, and LPDE samples were investigated by density measurements, differential scanning calorimetry, and Raman spectroscopy. The results were compared and relationships were es…
Relatively low-molecular-weight copolyesters of glycolic acid (GA) with lactones such as gamma-butyrolactone (BL), delta-valerolactone (VL), and epsilon-caprolactone (CL) were synthesized by copolycondensation without catalysts. The resulting copolyesters are intended as carriers for drug delivery systems. Copolyester…
Abstract A test methodology was developed for exposing degradable polymer test specimens to a simulated chemical and mechanical body environment and then testing them periodically to detect changes in stress–strain behavior. Poly(ortho ester) specimens were exposed to cyclic loading in aerated tris‐buffered saline (pH…
Abstract Interactions between decyl-, dodecyl-, and tetradecyltrimethylammonium bromide (DeTAB, DTAB, and TTAB) and an anionic porphyrin, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphine (H2TPPS4−), have been studied in water at 298.2 K. Precipitate formation constants between the surfactant cations and the H2TPPS4− ani…
The deposition and dissolution of aluminum in NaAlCl 4 melts saturated with NaCl have been investigated by voltammetry and potentiometry for different electrode materials at 175°C. The tungsten and glassy carbon electrodes are shown to be electrochemically inert in the melts, whereas copper is electrochemically active…
Abstract A quantitative oxygenation of styrene to 1-phenylethanol is realized in a reaction catalyzed by an iron complex of 5,10,15,20-tetrakis(1-methyl-4- pyridinio)porphine tetrachloride (FeTMPyP) in water at pH 12 containing NaBH4. A plausible mechanism involving a styrene carbanion stabilized by Fe(III)TMPyP as an…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTModeling the conformations and mobilities of aliphatic polyamides and polyesters confined to channelsA. E. TonelliCite this: Macromolecules 1991, 24, 6, 1275–1278Publication Date (Print):March 1, 1991Publication History Published online1 May 2002Published inissue 1 March 199…
Abstract The mineralogical and geochemical characteristics of the Tirschenreuth and Kohdachi kaolin deposits, which both occur in granite, are compared and the genesis of the deposits discussed. The Tirschenreuth deposit (Rappauf pit) is considered to have formed by weathering because: (i) the kaolinite has formed by…
For Escherichia coli, growth on acetate requires the induction of the enzymes of the glyoxylate bypass, isocitrate lyase and malate synthase. The branch point between the glyoxylate bypass and the Krebs cycle is controlled by phosphorylation of isocitrate dehydrogenase (IDH), inhibiting that enzyme's activity and thus…
The basic performance requirements for heat-shrinkable components and the compounding and processing techniques that are used to meet these requirements are covered. The emphasis is on the electrical, mechanical, and environmental protection features of components for low-voltage (up to 1 kV) applications. The aim is…
Porous electrodes of Sr‐doped lanthanum manganite in a planar solid oxide fuel cell were made by the plasma spray technique. Spherical carbon particles were utilized as an effective pore former. Spraying a mixture of annealed oxide powders sized between 50 to 200 μm and 15 wt% solid Carbospheres resulted in a uniform…
A treatment based on Badger’s rule is used to estimate symmetric stretching frequencies νs of the nonbridging fluorides of various ZrFn groups in the presence of divalent and monovalent countercations. New vibrational spectra of MgZrF6, Ba2ZrF8, and β-BaZr2F10 are presented and incorporated into the method. The factor…
Previous studies have shown that rat incisor dentin contains a considerable amount of magnesium that is distributed heterogeneously. The cementum-related dentin, especially its incisal portion, is richest in magnesium. It was the purpose of the present study to investigate the changes that occur in the magnesium conte…