Materials Literature
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Smectic–nematic phase boundaries that resemble arcs of ellipses can be analyzed by a quadratic expansion in temperature and pressure of the change ΔG of Gibbs function. If the change of entropy or volume is known, ΔG and its first two derivatives can be determined. Data on 8OCB and mixtures of 8OCB and 6OCB and of CB9…
We report time-resolved studies of luminescence excited in nominally pure single-crystal MgO by short pulses of 500-keV electrons at sample temperatures from 10 to 500 K. The principal luminescence bands have peaks at approximately 4.9, 3.3, and 1.7 eV. The decay kinetics and spectral shift of the 4.9-eV luminescence…
The energy position of the occupied and unoccupied $4f$ levels relative to the Fermi energy is studied for the rare-earth metals. This is done by treating the excited state as an impurity in an otherwise perfect crystal. This picture is first considered in the complete screening approximation. In this approximation th…
The bond lengths and bond angles of orthorhombic black phosphorus have been determined as a function of hydrostatic pressures to 26.6(5) kbar using time-of-flight neutron powder diffraction. We show that the markedly anisotropic compression reported previously results from a large pressure-induced shortening of the va…
The band structure and electronic properties of pure and heavily doped polyacetylene (both as grown and stretch oriented) have been investigated by a combination of optical-absorption and -reflection measurements in the frequency range from the middle ir (0.1 eV) through the visible (4.0 eV). The absorption data are c…
Aqueous solutions of methyl and hydroxypropyl methylcellulose are known to gel upon heating. These gels are completely reversible in that they are formed upon heating yet will liquefy upon cooling. The precipitation temperature, gelation temperature, and gel strength of these methylcellulose solutions were determined…
A detailed investigation of ${\mathrm{V}}_{2}$${\mathrm{O}}_{5}$, V${\mathrm{O}}_{2}$, ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$, and V metal is presented. The vanadium core lines in the x-ray photoelectron spectra are anomalously wide for ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ and V${\mathrm{O}}_{2}$. It is shown that this…
On 24 January 1978 the Russian satellite Cosmos-954 reentered the atmosphere over northern Canada. By use of high-altitude balloons, the atmosphere was sampled during 1978 up to an altitude of 39 kilometers to detect particulate debris from the reactor on board the satellite. Enriched uranium-bearing aerosols at conce…
Abstract A vibronic centre with a zero phonon line at 2.367 eV is produced in type Ib diamond by electron irradiation. The absorption system associated with the centre is strongly photochromic, and at low temperature (less than 200 K) may be bleached to less than 10% of its original strength; as the 2.367 eV system is…
Abstract The infrared and Raman spectra were studied for polycrystalline TlNO 3 in the modifications γ‐D or C , β‐C , and α‐O . The site group and factor group analysis of the NO − 3 anion, own symmetry D 3h , was carried out for the space groups considered. The following site groups are possible for the various modif…
Abstract A recent method for the determination of Clebsch‐Gordan coefficients is applied to the crystallographic space groups.
Manganese-rich Mn-Cu alloys quenched from the high temperature γ-phase state are known to show a high damping capacity, which has been revealed to be associated with the fcc → fct transformation of the metastable γ-phase. The γ-phase of high manganese Mn-Fe alloys is also reported to show tetragonality when quenched.
Abstract The cellulose blotter/torsion pendulum technique used for the determination of relaxations that occur in low molecular weight compounds, oligomeric materials, and amorphous polymers is discussed. The glass transition temperature of a number of aliphatic alcohols and hydrocarbons have been determined and corre…
(1979). Acoustic Emission from Wool during Compression. The Journal of The Textile Institute: Vol. 70, No. 8, pp. 364-366.
Maleic acid(MA) was found to polymerize easily by potassium persulfate (KPS) in water in the presence of polyvinylpyrrolidone (PVP), and to form a polymer complex in which the molar ratio of MA to VP monomer unit was approximately unity. The formation of the polymer complex was accelerated by increases in the reaction…
The cylindrical cell method for determining the refractive indices of liquid crystals is described. This method is based on the use of a cylindrical cell composed of a pair of semi-cylindrical prisms and the measurement of the incident angle dependence of transmitted light intensities. It is applied to the measurement…
Abstract The anodic peak potentials of [2.2]para- and -metaparacyclophanes were found to be highly dependent on the solvent. A cleavage reaction occured when [2.2]paracyclophane was electrolyzed anodically, using acids or alcohols as nucleophilic solvents, whereas lead tetraacetate oxidation in trifluoroacetic acid–di…
To the Editor.— "Whisker hair" is the name that barbers have given to the short, dark, curly hair that grows anterior to, over, and behind the ears in young men. This hair begins to appear in young men at approximately 18 to 25 years of age. It only occurs in individuals who are, or will be, quite bald. It undoubtedly…
Fission fragments anisotropy in fast-neutron-induced fission of 235U was measured at neutron energies ranging from 0.3 to 1.4 MeV at intervals of 0.1, 1.6, 1.8, and 2.2 MeV. In the present study, the pairing energy gap (2Δ0) for the highly deformed transition state of the nucleus 236U was found to be 2.0 ± 0.06 MeV.
The domain memory was first reported by Bobeck (1) in 1967. His concept was based on the fact that a cylindrical magnetic domain, that is, a small region of reversed magnetic polarity in an otherwise com pletely magnetized plate of material, is stable over a convenient range of applied field. The stable cylindrical d…