Materials Literature
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A bias field dependence of dielectric permittivity ∊'(E) of ferroelectric liquid crystals DOBAMBC and a mixture of DOBAMBC with Sm C substance in a planar Sm C* sample shows four different frequency regions. In two of them the unusual behaviour—increase of ∊' with increasing E—is observed. The first increase found in…
The dielectric and electrostrictive properties of relaxor ferroelectric Pb (Mg1/3Wb2/3)O3-based ceramics are strongly affected by the microstructure with emphasis on the grain size. Both the dielectric constant K and electrostrictive field coefficient (M) were found to increase with increasing grain size whereas the e…
Abstract A method is described for IR spectroscopy whereby combining statistical analysis with the quantitative method described by Slonimskaya et al. (1986) results in more informative spectra. Application of this method to dioctahedral micaceous minerals with vacant trans octahedra has revealed a number of peculiari…
The static dielectric constant ∊⊥ in the smectic A and the smectic C* phase of the ferroelectric liquid crystal 4-(3-methyl-2-chlorobutanoyloxy)-4'-heptyloxybiphenyl was determined. Strong pretransitional effects were observed in the smectic A phase. When the Goldstone mode contribution in the smectic C* phase is quen…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTQuantum effects in anisotropic semiconductor clusters: colloidal suspensions of bismuth sesquisulfide and antimony sesquisulfideB. F. Variano, D. M. Hwang, C. J. Sandroff, P. Wiltzius, T. W. Jing, and N. P. OngCite this: J. Phys. Chem. 1987, 91, 26, 6455–6458Publication Date…
Extended x-ray absorption fine structure (EXAFS) studies were conducted on catalysts containing platinum and rhenium, or palladium and rhenium, on alumina. The atomic ratio of rhenium to either platinum or palladium was close to one in the catalysts investigated. The metallic entities in the catalysts were characteriz…
1. The (R)-2-hydroxyglutaryl-CoA dehydratase system from Acidaminococcus fermentans was separated by chromatography of cell-free extracts on Q-Sepharose into two components, an activator and the actual dehydratase. The latter enzyme was further purified to homogeneity by chromatography on blue-Sepharose. It is an iron…
The recent discovery of a periodic distortion of the lattice structure of gamma -Fe precipitates in Cu motivated the authors to re-examine the magnetic structure of these precipitates using a neutron diffraction technique. They find that the spin structure is that of a longitudinal type-1 antiferromagnet as is well kn…
Abstract The effect of cold work on the transport of liquid methanol in crosslinked PMMA disks has been determined at temperatures from 35–56°C. Deformed samples absorb at fast rates with kinetics that approach those of Fickian diffusion. Undeformed samples sorb at lower rates and the kinetics tend toward those of Cas…
Abstract Fibers of organic polymers (polystyrene, cellulose acetate, and polypropylene) were formed by the rapid expansion of supercritical fluid solutions through a small diameter nozzle to ambient temperature and pressure. Solutions were prepared either by dissolving the polymer directly in room temperature pentane,…
The nucleotide and deduced amino acid sequences of the lacE and lacF genes, which code for the lactose-specific Enzyme II and Enzyme III of the Staphylococcus aureus phosphotransferase system, are presented. The primary translation products consist of a hydrophobic protein of 572 amino acids (Mr = 62,688) and a polype…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDivalent titanium chemistry. Synthesis, reactivity, and x-ray and neutron diffraction studies of Ti(BH4)2(dmpe)2 and Ti(CH3)2(dmpe)2James A. Jensen, Scott R. Wilson, Arthur J. Schultz, and Gregory S. GirolamiCite this: J. Am. Chem. Soc. 1987, 109, 26, 8094–8096Publication Da…
Abstract A series of rigid rod polyimides 1a–f derived from pyromellitic anhydride (PMDA) and 2,5‐di‐n‐alkoxy‐1,4‐phenylenediamine containing flexible alkoxy side chains with 4 to 16 carbon atoms was prepared by solution polycondensation. As demonstrated by model experiments full conversion to the imide structure is a…
Slow strain rate tests (SSRTs) were conducted to study the effect of electrode potential on the intergranular stress corrosion cracking (IGSCC) of Alloy 600 in deaerated 0.01 M H3BO3 + 0.001 M LiOH solution at two different partial pressures of molecular hydrogen at 350 C, using tensile specimens with a cold-pressed h…
Time-domain spectroscopy is used to study the complex permittivity of two types of liquid crystals: heptylcyanobiphenyl (7CB) and octylcyanobiphenyl (8CB). The variation of the dominant relaxation frequency values of both 7CB and 8CB as a function of temperature are very similar, showing no influence of the smectic st…
Abstract have been investigated as function of substrate used and experimental conditions.
Abstract The hyper‐Raman spectra of K 2 SnCl 6 crystals were measured for various scattering geometries at ambient temperature. The F 2u deformation mode of [SnCl 6 ] 2− , which is inactive in infrared and Raman spectra but hyper‐Raman active, was observed at 112 cm −1 . The TO and LO frequencies of an F 1u species ar…
Abstract The production of reinforced plastics has constantly increased since the Second World War. With a forecast growth rate of 8 to 12 percent annually over the next decade, composites are one of the fastest growing sectors of the plastics industry. Advanced composites will show the largest expansion, due to a str…
The corrosion products of steel plate obtained in aqueous solution in the presence or absence of an external magnetic field of 40 oersted (Oe) were studied. The Mössbauer phase composition data of the rust show that the magnetic field has an influence on the corrosion mechanism.
Mr=419.87, trigonal, P3cl, a=7.198(1), c= 13.076 (1) ~k, V = 586.7 A, 3, Z = 6 (30 Mn and 12 Ge per unit cell), Dx=7.129Mgm -3, A(MoKa)= 071069~, /x=31.0mm -~, F(000)=1134.0, T= 295 K. The crystal structure of ~r2-MnsGe2 has been determined using diffraction data derived from a mixed crystal of ~r~-Mns.l~Ge2 and ~'2-M…