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We find that certain cyano Schiff bases and cyanobiphenyls with alkyl or alkoxy end groups exhibiting a bilayer smectic-$A$ phase, also exhibit a reentrant nematic phase at high pressure. A tentative model of the bilayer smectic-$A$ phase and the mechanism whereby the reentrant transition may occur is presented.
Abstract not Available.
For pt.I see Act Crystallogr., vol.B32, p.1348 (1976). The intermetallic compound Fe 3 Sn 2 has been studied by neutron diffraction and magnetisation measurements. This compound is ferromagnetic (T C =657K). At room temperature the spin direction is along the c axis. A spin rotation is observed between approximately 2…
Research on metal–insulator transitions is at the moment quite fashionable. In many materials the electrical behavior changes from metallic to nonmetallic when the pressure, temperature or magnetic field is varied or (as in alloys) when the composition is varied, and the theoretical description of these processes is q…
The structure parameters of Li 3 N in the temperature range -120 to 20°C were refined both for neutral atoms (Li 0 and N 0 ) and for ions (Li + and N 3- ). For N 3- new scattering curves were used which were calculated by applying stabilizing Watson-sphere potentials for different radii. All structure parameters depen…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGroup 6 transition metal peroxo complexes stabilized by polydentate pyridinecarboxylate ligandsStephen E. Jacobson, Reginald Tang, and Frank MaresCite this: Inorg. Chem. 1978, 17, 11, 3055–3063Publication Date (Print):November 1, 1978Publication History Published online1 May…
The morphology of horse shoe corrosion of copper and copper alloys in sea water cooled condensers in power stations is presented, and the mechanism of nucleation and of development of this type of corrosion is discussed. Horse shoe corrosion is the result of the formation of an active-passive cell: the pH of the sea w…
The variation of electrical resistivity of an insulator-conductor composite, namely, wax-graphite composite, with parameters such as volume fraction, grain size, and temperature has been studied. A model is proposed to explain the observed variations, which assumes that the texture of the composite consists of insulat…
The elastic and misfit strain in vapor-grown InGaP/GaAs crystals was determined by measuring the lattice parameter of the InGaP before and after removal of the GaAs substrate. The energy-band-gap shift as a function of strain was measured in a similar manner using photoluminescence. Up to 70% of the misfit strain was…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPorphyrins. 38. Redox potentials, charge transfer transitions, and emission of copper, silver, and gold complexesArtemis Antipas, David Dolphin, Martin Gouterman, and Eugene C. JohnsonCite this: J. Am. Chem. Soc. 1978, 100, 24, 7705–7709Publication Date (Print):November 1, 1…
Abstract The reactivity of seven phosphate rocks was estimated by five methods (neutral ammonium citrate first and second extractions, 2% citric acid, 2% formic acid, ammonium citrate pH 3, and absolute citrate solubility). These measurements were evaluated by crop response data obtained from a greenhouse experiment w…
Energy loss spectra of 80 keV electrons transmitted through thin films polymethylmethacrylate (PMMA) were measured with a resolution of 0.1 eV for energy losses from 1 to 300 eV. From the loss spectra, the dielectric response function of PMMA was obtained from 1 to 100 eV and compared with recent synchrotron radiation…
The structures of the bismuth oxides are discussed and evaluated. Calculated powder diffraction patterns were made for all reported phases with known crystal structures. Comparing the calculated and experimental patterns indicates that the α and β polymorphs are well characterized. All previous observations concerning…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular Weight Distribution and Correlation between Chemical Composition and Molecular Weight in a High-Conversion Copolymer of Styrene-Methyl AcrylateShinya Teramachi, Akira Hasegawa, Makoto Akatsuka, Akira Yamashita, and Nobuhiro TakemotoCite this: Macromolecules 1978, 1…
The usefulness of Crewe's Z-contrast technique for the study of small catalyst particles in the scanning transmission electron microscope is investigated and discussed. By forming suitable combinations of the annular dark-field and energy-loss signals, structural details in platinum particles as small as 2 nm may be i…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExcluded-Volume Effects in Dilute Polymer Solutions. 7. Very High Molecular Weight Polystyrene in Benzene and CyclohexaneY. Miyaki, Y. Einaga, and H. FujitaCite this: Macromolecules 1978, 11, 6, 1180–1186Publication Date (Print):November 1, 1978Publication History Published…
The Judd-Ofelt (JO) theory was applied to optical-absorption transitions in Nd+3 : YVO4 to obtain intensity parameters (Ω2=5.88×10−20 cm2; Ω4=4.08×10−20 cm2; Ω6=5.11×10−20 cm2) and the radiative lifetime (152 μs) and quantum efficiency (0.72) of the 4F3/2 state. The variations of the absorptions with respect to the op…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMixed valence interactions in di-.mu.-oxo bridged manganese complexes. Electron paramagnetic resonance and magnetic susceptibility studiesStephen R. Cooper, G. Charles Dismukes, Melvin P. Klein, and Melvin CalvinCite this: J. Am. Chem. Soc. 1978, 100, 23, 7248–7252Publicatio…
Abstract High‐pressure CO 2 sorption data in semicrystalline poly(ethylene terephthalate) (PET) are presented for temperatures ranging from 25 to 115°C. The results are described by Henry's law above the glass‐transition temperature of PET, while a dual‐mode sorption model comprised of a Henry's law and a Langmuir iso…
A phase diagram for all the possible collinear spin arrangements for ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ is derived within the atomic limit. Due to the fact that the ${a}_{1g}$ electrons of the V atoms form a diamagnetic bond for the vertical pairs of V atoms, the magnetic structure of ${\mathrm{V}}_{2}$${\mathrm{O}}…