Materials Literature
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Thin film ferroelectrics are technologically important materials. Doped or undoped lead zirconate titanate (PZT) and lead titanate (PT) films are of special interest since they have numerous applications in electro-optic, piezoelectric and non-volatile memory devices. In this brief overview, PZT films deposited by rf-…
The influence of heat treatments on the anodic polarization behavior of alloy 400 in acidic Na2SO4 solutions with different pH values and chloride contents has been studied. Alloy 400 is susceptible to intergranular corrosion (IGC) in 0.5 N Na2SO4 solution (pH 3) containing 0.2% CuCl2. For the same heat treatment (soa…
High‐temperature dynamic mechanical thermal analysis (DMTA) has been used to study a lithium zinc silicate glassceramic. The DMTA technique was capable of measuring the glass transition temperature of the original starting glass composition, as well as being able to follow crystallization and structural changes within…
Abstract A boundary‐element method is derived for determining the anti‐plane displacement and stress in an inhomogeneous elastic material subjected to a time‐dependent load.
The life history of freshwater populations of Rhizoclonium hieroglyphicum is fully described and illustrated for the first time, using morphological and karyological data. The cycle is diplobiontic with isomorphic gametophytes (n=24) and sporophytes (2n=48).
This study examined two polyethylene glycol (PEG) polymers (PEG 6000 and PEG 10000) and compared measurements of water potential obtained with a thermocouple osmometer and thermocouple psychrometers at three temperatures (15, 25 and 35°C) and five osmdalities (50, 100, 200, 300 and 400 g/1000 g water). These were then…
Selbst bei Konzentrationen von nur 1 Gew. ‐% lassen sich in einer Lösung von Dikaliumfolat in Wasser makromolekulare Aggregate nachweisen. Ihre wahrscheinliche Struktur ist in Einklang mit den Ergebnissen von Untersuchungen an höher konzentrierten Lösungen, die zum Teil flüssigkristallines Verhalten zeigen. In ihnen l…
Electric-field-induced cholesteric-nematic (Ch-N) phase transition and its reverse process (N-Ch) are discussed by taking account of the surface interaction effect. Threshold electric fields of a cholesteric to nematic and a nematic to cholesteric phase transition are investigated in conjunction with a liquid crystal…
The results of the observation of as-grown domain structure in lead germanate Pb5Ge3O11 (LGO) by specially deviced cleavage method are presented. The influence of periodic composition inhomogeneties (growth layers) is investigated. It is shown that the observed at room temperature frozen-in domain pattern is defined b…
A Bacillus subtilis mutant that produced glutamine synthetase (GS) with altered sensitivity to DL-methionine sulfoximine was isolated. The mutation, designated glnA33, was due to a T.A-to-C.G transition, changing valine to alanine at codon 190 within the active-site C domain. Altered regulation was observed for GS act…
Ein effizienter bifunktioneller Katalysator für die Titelreaktion ist Cobalttetra(hydrochinon)porphyrin 1 . Die oxidierte Form von 1 (rechts schematisch dargestellt. R = Hydrochinon) hat eine Einheit für die Wechselwirkung mit molekularem O 2 , eine andere für die Wechselwirkung mit dem Pd‐Katalysator. So können Elekt…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCorrelation of CrOCr .pi.-bonding strength with .pi.-donor effectiveness of bridging and nonbridging ligands in (tris(2-pyridylmethyl)amine)chromium(III) dimersThomas F. Tekut, Charles J. O'Connor, and Robert A. HolwerdaCite this: Inorg. Chem. 1993, 32, 3, 324–328Publication…
The anisotropic thermal expansion parameters a(T), b(T) and c(T) of some RECu 2 , intermetallics (RE=Y, Er, Nd) has been measured in the temperature range from 400 K down to 4.2 K using X-ray powder diffraction. The influence of the crystal field on the thermal expansion in ErCu 2 and NdCu 2 has been determined by com…
A model for the shape and motion of disclination loops observed in thermotropic small molar mass and polymeric nematic liquid crystals in the presence of steady rectilinear shear and oscillatory rectilinear shear flow is presented. In steady rectilinear simple shear, disclination loops elongate and tumble, before retr…
Transgranular stress‐corrosion cracking without copper oxidation has been demonstrated in α‐brass, confirming the findings of Bertocci, Thomas, and Pugh (1984), Cracks continued to propagate in monocrystals at potentials as low as −40 mV vs. a copper reference electrode in solutions. Residual Cu(II) in these solutions…
Corrosion and its control of mild steel in drilling muds containing 3.2 g/L H2S have been studied with the wheel test method to increase drill pipe service life. The high corrosion rate is attributed to the presence of H2S. The corrosion product was shown to be Fe9S8 by x-ray diffraction and exhibited very poor protec…
Abstract High molecular weight aromatic polyetherketone (PEK) was found to react with 4,4′‐difluorobenzophenone (DFB) in the presence of potassium carbonate in benzophenone or diphenyl sulfone at 300°C, yielding low molecular weight PEK with fluorophenyl end groups, while neither polyetheretherketone (PEEK) nor poly‐t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolyisobutylene-toughened poly(methyl methacrylate). 1. Synthesis, characterization, and tensile properties of PMMA-l-PIB networksJoseph P. Kennedy and G. Caywood RichardCite this: Macromolecules 1993, 26, 4, 567–571Publication Date (Print):February 1, 1993Publication Histor…
The early-to-late stage of spinodal decomposition in a critical mixture of polystyrene and polymethylphenylsiloxane was studied by time-resolved light scattering over 1.8k21.1 \ensuremath{\mu}${\mathrm{m}}^{\mathrm{\ensuremath{-}}1}$ and 0t502 h, with k and t being the wave number and the elapsed time after temperatur…
Abstract Durch Umsetzungen der Alkalimetallcarbonate mit Chrom und dem entsprechenden Chalkogen in der Schmelze konnten die Verbindungen RbCr 3 S 5 , K 3 Cr 11 S 18 , RbCr 5 Se 8 und CsCr 5 Se 8 als gut ausgebildete Kristalle erhalten werden. Die Verbindungen kristallisieren monoklin im Raumgruppentyp C2/m (RbCr 3 S 5…