Materials Literature
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Abstract A variety of β-perfluoroalkylpyrroles were prepared from reaction of β-perfluoroalkyl-α,β-unsaturated ketones with p-toluenesulfonylmethylisocyanide in moderate yields. Tetrakis(perfluoroalkyl)porphyrins were readily obtained by oxidative cyclization of 2-hydroxymethyl-3-ethyl-4-perfluoroalkylpyrroles in acid…
The relaxation of the soft mode is observed both in the Sm A and Sm C * phases by eliminating the contribution of the Goldstone mode under a dc bias field. Three relaxations are observed in the Sm C * phase at the frequency range below 10 MHz. The temperature dependence of the dielectric constant originating in the so…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFluorescent lanthanide complexes. 1. Reaction between terbium(3+) and 4-oxo-4H-1-benzopyran-3-carboxaldehyde in alcoholic mediumCarla Bisi Castellani, Oliviero Carugo, Carlo Tomba, and Anna Invernizzi GambaCite this: Inorg. Chem. 1988, 27, 22, 3965–3968Publication Date (Prin…
NiSO 4 .6H 2 O cristallise dans C 2 /c avec affinement jusqu'a 0,031 ou P4 1 2 1 2 avec affinement jusqu'a 0,045
The partial structure factors and radial distribution functions for liquid CuSe have been determined by the isotopic substitution technique and the results compared with those from an earlier study of liquid CuTe. It is shown that, whereas the underlying ionic configuration of CuTe can be written as Cu+Te−, for CuSe t…
The specific liquid permeabilities of a wide variety of phosphatebonded, porous alumina compacts prepared from alumina powders of differing size distribution, and ranging in porosity from 32 to 50 vol%, were not described well by the Carmen‐Kozeny model but were described by a capillary model based on mean entry pore…
Abstract A unified numerical method to integrate stiff time‐dependent constitutive equations has been developed. This method is a stable, non‐iterative and self‐correcting solution procedure which works successfully over a wide range in strain rate sensitivity. Time steps are automatically controlled during integratio…
The optical detection of the surface coupling of nematic liquid crystals (NLCs) with rubbed polyimide substrates subjected to pure twist is described. Transmitted light beams through a cell comprised of homogeneously aligned NLC of a cyanobiphenyl, 5CB, inserted between crossed polarizers are observed as functions of…
The X-ray scattering intensity of liquid sulfur was measured at 130, 155, 180, 210, 240, 270 and 300°C by a reflection method from a free liquid surface. This was carried out using a special inner diffraction chamber as a sample holder. As a result of a radial distribution analysis, the radial functions were obtained…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIron(IV) phthalocyanines. Moessbauer spectral studies of (.mu.-carbido)(phthalocyaninato)iron(IV) and of its axially ligated and oxidized (Pc.cntdot.+.pi. cation radical) derivativesEddy N. Bakshi, Christopher D. Delfs, Keith S. Murray, Birgit Peters, and Heiner HomborgCite…
Abstract High‐density polyethylene and randomly branched linear low‐density polyethylene of varying branch length and content were used to produce oriented thin films. Sample morphology was investigated using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and dynamic mechanical therma…
Proton NMR spectra and relaxation times (${T}_{1}$s) at 60 MHz were obtained for the thermotropic compound 4'-n-hexadecyloxy-3'-nitro-biphenylcarboxylic acid, which, upon heating, has the sequence of phases: crystal\ensuremath{\rightarrow}${\mathrm{S}}_{\mathrm{C}}$\ensuremath{\rightarrow}D (or smectic-D)\ensuremath{\…
Following the recent discovery of a new magnetic phase transition in the Ce(Fe 1-x Co x ) 2 compounds for which x<0.3, the authors report the results of a neutron powder diffraction study on a compound with x=0.20 using HRPD at the Rutherford Appleton Laboratories. Rietveld structure refinements show that the ferromag…
The title compound, a candidate for solar photovoltaic applications, crystallizes in at least two polymorphic structures. Triclinic form: a = 11.911 (4), b = 7.401 (9), c = 6.501 (7) Å, α = 92.78 (7), β = 111.9 (4), γ = 98.08 (6)°, = .046 for 955 reflections with F 0 > 2σ(F 0). Monoclinic form: a = 15.72 (4), b = 7.28…
A novel method is described for calculating the breakdown voltage of uniform field gaps in compressed air and SF/sub 6/ without the need for experiments. This method is based on the criterion of self-recurring single-electron avalanches developed in the gap. It is shown that the results computed by this method for pd…
Glassy B2O3 samples annealed at 300 °C at 10 and 15 kbar were densified by 9% and 11%, respectively. Relaxation by subsequent annealing at ambient pressure restored the original density. The structure of the pressurized samples was determined with x-ray diffraction. A new method was developed for eliminating the Compt…
Glasses containing up to 60-mol % PbF2 have been made in the binary system PbF2-B2O3. The glass transformation and crystallization temperatures, thermal expansion behavior, and electrical conductivity of these glasses have been measured. A corresponding series of lead borate glasses were also studied to provide a basi…
Garnets on the pyrope-grossular join have been synthesized, their unit-cell edges measured, and the activity of $$Ca_{3}Al_{2}Si_{3}O_{12}$$ component in $$Pyr_{85}Gr_{15}$$ determined experimentally at 1000°C. There is no significant departure from ideal volume mixing in the composition range 0 to 21 mole% $$Ca_{3}Al…
Hydrogenated amorphous carbon (HAC) films have been prepared by direct condensation of cool carbon vapor at low temperatures. Quantitative absorption coefficients for these films have been obtained between 0.16 and 20 microns. Spectra of HAC at 3.4 microns are quite similar to those seen in comet Halley and in the Gal…
The method of constant-stress molecular dynamics using the Parrinello-Rahman Lagrangian is described, particularly as applied to Coulomb systems. The method is used to simulate the phase behavior of silver iodide. The \ensuremath{\beta}, \ensuremath{\alpha}, rocksalt, and liquid phases are reproduced and the boundarie…