Materials Literature
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In a limited temperature range above the clearing point of crystal suspensions, submicroscopic entities representing unmeasurably small portions of the original crystal population may survive whose existence is revealed by crystals nucleated on subsequent cooling [1]. Factors influencing the number of these nuclei and…
For an arbitrary electron configuration l1n1l2n2l3n3⋯, analytical expressions are derived for the energy-matrix coefficients of the electrostatic-interaction parameters Fk(li,lj) and Gk(li,lj) and of the spin–orbit parameters ζ(li). A computer program is described which calculates decimal values of these coefficients…
Ferroelectric Ba0.27Sr0.75Nb2O5.78, with Tc = 348° ± 15°K, is a tungsten bronze-type structure crystallizing in the tetragonal system, with lattice constants a = 12.43024 ± 0.00002 and c = 3.91341 ± 0.00001 Å at 298°K, space group P4bm, and five formulas in the unit cell. The integrated intensities of 6781 structure f…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRegulation of glutamine synthetase. XII. Electron microscopy of the enzyme from Escherichia coliR. C. Valentine, B. M. Shapiro, and E. R. StadtmanCite this: Biochemistry 1968, 7, 6, 2143–2152Publication Date (Print):June 1, 1968Publication History Published online1 May 2002P…
Phosphorus, the element itself, becomes superconducting near 4.7 degrees K and at pressures exceeding 100 kilobars. This constitutes one of the four last missing links in the proof that superconductivity is normal behavior for every truly metallic sp element. The three remaining ones are arsenic, sulfur, and iodine.
The crystalline material covering the cocoon of Malacosoma neustria testacea (Lasiocampidae, Lepidoptera) was analyzed physically and chemically. The mean component was identified as calcium oxalate monohydrate, and the crystals were found to be whewellite in form.
Abstract Anionic polymerizations of methyl and other n ‐alkyl cinnamtes with organometallic catalysts were studied. Calcium‐zinc‐tetraethyl showed the greatest catalytic activity for the polymerization of the above monomers. In copolymerization of cis and trans isomers of methyl crotonate and isopropyl crotonate the t…
A recent microscopic elasticity formalism is generalized to nonprimitive, nonpiezoelectric crystals, and extended to treat long-range electrostatic interactions explicitly. Its relationship with the macroscopic theory of crystal elasticity is established for this type of crystal up to, and including, third order. The…
Neutron-diffraction studies on powered samples of BaLiH3 and BaLiD3 have shown that the structure is of the inverted perovskite type with the atomic positions of space group Pm3m: Ba in (0, 0, 0), Li in (12, 12, 12), and H or D in (12, 12, 0; 0, 12, 12; 12, 0, 12). The SrLiH3 and EuLiH3 are presumably isostructural. T…
The results of measurements of the proton spin–lattice relaxation time T1 in ice are reported. The ice samples were single crystals grown by zone refining at atmospheric pressure. The measured activation energy for the T1 process is 14.1 ± 0.1 kcal/mole. No anisotropy of T1 is observed. A theoretical calculation of T1…
Spontaneous emission probabilities for electric- and magnetic-dipole transitions from several electronic states of Pr3+ in LaF3 are calculated using the Judd–Ofelt theory and experimental intensity parameters. The calculated radiative decay probabilities are combined with observed fluorescence lifetimes to determine t…
Raman-scattering measurements on K${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$ reveal a broad, low-frequency ferroelectric mode which can be represented by a simple damped-harmonic-oscillator function. The resultant characteristic frequency and reciprocal zero-frequency susceptibility approach zero while the damping factor r…
Received 29 January 1968DOI:https://doi.org/10.1103/PhysRevLett.20.1045©1968 American Physical Society
Abstract Optically-negative cholesteric liquid-crystal films can be transformed to an optically-positive state by applying high d-c electric fields. A phase transformation occurs in which the helicoidal cholesteric structure is converted to either a planar smectic, or a linear nematic, structure. The threshhold field…
Abstract Mercerized cellulose in the form of 7/2 yarn was reactivated with 17.5% sodium hydroxide and then heated at 100°C. with 5 moles of trityl chloride, in pyridine, per anhydroglucose unit. The time of reaction was varied, giving ether derivatives of the cellulose containing 0.31–0.79 triphenylmethyl groups (DS)…
Abstract : Tables, curves, equations, and example problems presented in the report make it possible, within the range of the experiments, to accurately predict any desired dimensions of the limit of complete rupture.
An approximate solution is obtained for the problem of steady-state longitudinal-wave propagation in anisotropic bars of infinite length and rectangular cross section by employing the variational method of Ritz. The first three dispersion curves are presented for orthotropic, tetragonal, hexagonal, cubic, and isotropi…
Because of its high magnesium content and relatively small anount of silica, iron and aluminum, the weathering process of serpentine rock is very different from other aluminosilicate rocks. Generally it has been thought that podsolization does not occur in the soil derived from this rock.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of complex formation between hexacyanoferrate(III) ions and iron(III) to form FeFe(CN)6 (Prussian brown)R. G. Walker and Kenneth O. WatkinsCite this: Inorg. Chem. 1968, 7, 5, 885–888Publication Date (Print):May 1, 1968Publication History Published online1 May 2002Pu…
The temperature and strain rate dependence of the flow stress of ordered and disordered polycrystalline Cu3Au was investigated in the range 20°–420°K. A thermally activated deformation mechanism was observed at temperatures less than ∼100°K and ∼340°K for the ordered and disordered material respectively. For ordered C…