Materials Literature
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A new lyotropic liquid crystal, potassium laurate, decylammonium chloride and water, which has two uniaxial phases and a biaxial nematic phase, is reported. A surface of the phase diagram and X-ray diffraction studies are presented. The chemical stability of this mixture is compared with the potassium laurate/decanol/…
PZT powder of the composition Pb(Zr0.53Ti0.47)O3 was modified by the incorporation of Sr2+, La3+ and Fe3+ as isovalent, supervalent and subvalent cations respectively using spray drying technique. Powders were calcined and converted into piezoelectric ceramics by cold compaction, sintering and poling. Finished ceramic…
Understanding the relationship between the molecular structure and the macroscopic properties of polymer solutions and gels, oil-water-surfactant emulsions, lyotropic and thermotropic liquid crystals, colloidal dispersions, detergents, and other such "microstructured fluids" is essential to the optimal use of these co…
Cladistic analysis of species of the diatom genus Gomphoneis indicates that possession of doubly punctate striae and marginal laminae is sufficient but not necessary for inclusion in the genus. This diagnosis is compared to previous interpretations of Gomphoneis. Within Gomphoneis two subgeneric groups are recognized.…
The sintering of glass can sometimes be impeded by crystallization. In the optimum process the glass should sinter to full density before the onset of crystallization. In an earlier paper we showed how sinter‐forging experiments can be used to investigate the coupling between densification and crystallization. Here we…
Abstract X-ray powder diffraction (XRD) and energy-dispersive X-ray analyses (EDX) of individual clay particles from hydrothermal mounds in the Galapagos spreading center (GSC) (Deep Sea Drilling Project, hole 509B) and high-resolution transmission electron microscopy (HRTEM) of the <2- µ m size fraction of these s…
Abstract Transmission electron microscope (TEM) images of mixed-layer illite/smectite (I/S) from Gulf Coast shales obtained earlier by the authors have been reexamined by comparing them with the calculated images of G. D. Guthrie and D. R. Veblen. Ordered two-layer periodicity was not detected in the 1750- and 2450-m…
ABSTRACT Community structure of benthic diatoms in two sandy streams was studied for two summers to assess differences in abundances and species composition among habitats and between years and streams. The greatest differences in abundances (cells·cm −2 ) were lower abundances on rocks than on sand, whether the sand…
Polycrystalline aggregates with overall icosahedral symmetry have been found in rapidly solidified Al—Mn—Fe—Si alloys. The orientation relationship between crystals is such that icosahedral motifs in all the crystals are parallel. Although the cubic axes undergo fivefold rotation about irrational ⟨1, τ, 0⟩ axes, only…
We discuss the effect on two-dimensional bubble growth of deviations in internal vertex angles from the predicted 120\ifmmode^\circ\else\textdegree\fi{}. We also present evidence that Plateau border broadening contributes to the anomalous growth exponent that we have previously observed in froth coarsening.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLiquid crystal polymers containing macroheterocyclic ligands. 2. Side chain liquid crystal polysiloxanes and polymethacrylates containing 4-(.omega.-alkan-1-yloxy)-4'-(4'-carboxybenzo-15-crown-5)biphenyl side groupsVirgil Percec and Randall RodenhouseCite this: Macromolecule…
The semiconductor properties of passive films formed in alkaline aqueous solutions on Zn, Zn‐Co, and Zn‐Ni substrates were studied by electrochemical and photoelectrochemical methods. Substrate doping with Co and Ni leads to a homogeneous distribution of these elements in the passive oxide layer. The density and energ…
A new ferroelectric crystal from the family of alkylammonium halogenoantimonates and halogenobismuthates, namely (CH3NH3)5Bi2Cl11 (PMACB), was grown. It revealed a second order phase transition at 307 K with a high peak of the dielectric permittivity: ϵ ≃ 5.103 along the c-axis. X-ray diffraction, DSC and dielectric s…
Abstract The kaolin minerals in lateritic weathering profiles on dolerite and granite in Western Australia have been characterized by intercalation tests for halloysites, and also by their particle morphologies. Towards the surface of the profiles there is a decrease in both total kaolin mineral content, and in the ex…
Degradation of the electrical resistance of perovskite‐related dielectrics under voltage–temperature stress is a function of the concentration of the most mobile ionic species, the oxygen vacancy. Sources of oxygen vacancies in simple perovskite oxides are reviewed, and the effects of the compositional complexity of t…
Polyimide films containing up to 3.2 wt. % water (H2 O or D2 O) have been studied by dielectric relaxation (DR) and 2H nuclear magnetic resonance (NMR) spectroscopies. Dielectric loss measurements show the presence of a double peak near 200 K due to water, with two components designated as γ1 and γ2 . The γ2 peak, whi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface studies of polymer blends. 3. An ESCA, IR and DSC study of poly(.epsilon.-caprolactone)/poly(vinyl chloride) homopolymer blendsMichael B. Clark Jr., Cindy A. Burkhardt, and Joseph A. Gardella Jr.Cite this: Macromolecules 1989, 22, 12, 4495–4501Publication Date (Print…
ADVERTISEMENT RETURN TO ISSUEPREVArticleUnanticipated redox transformations in gold polyselenides. Isolation and characterization of diselenobis(tetraselenido)diaurate(2-) and undecaselenido(2-)Mercouri G. Kanatzidis and Song Ping HuangCite this: Inorg. Chem. 1989, 28, 26, 4667–4669Publication Date (Print):December 1,…
A commercially available mammary implant containing a soft polyester polyurethane foam shell has been examined for possible diamine hydrolysis products. Fourier Transform Infrared (FT-IR) analysis has shown ester and aromatic structures present in the intact foam shell. Vigorous hydrolysis conditions using NaOH have p…
We have measured the specific heat down to 1.5 K of a collection of high-quality single crystals of \ensuremath{\kappa}-(ET${)}_{2}$Cu(NCS${)}_{2}$ in fields parallel to the crystalline ${a}^{\mathrm{*}}$ direction to 12.5 T. In this first determination of \ensuremath{\gamma}, we find \ensuremath{\gamma} to be 25\ifmm…