Materials Literature
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The effect of benzotriazole (BTA) on corrosion of copper in 5% NaCl has been studied by immersion tests, potentiostatic polarization, AC impedance measurements, and ellipsometric investigations. It was found that BTA when present in the corrosive environment is a good inhibitor. The good electronic conductivity of the…
Abstract Heats of fusion, melting transitions, and the derived entropies of fusion were obtained by differential scanning calorimetry for examples from three homologous series of homopolymers having long side chains. Homopolymers having side‐chain lengths between 12 and 22 carbon atoms were chosen from the poly( n ‐al…
An analysis is made of the distribution function and its moments for a linear combination of three randomly chosen orthogonal components of the so-called radius of gyration of an unrestricted random-flight chain, and certain averages of moments are obtained of the three-dimensional distribution W (L12L22L32), where L1…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structure of metallocenesHarry B. Gray, Y. S. Sohn, and N. HendricksonCite this: J. Am. Chem. Soc. 1971, 93, 15, 3603–3612Publication Date (Print):July 1, 1971Publication History Published online1 May 2002Published inissue 1 July 1971https://pubs.acs.org/doi/10.10…
Abstract Heterocysts of Anabaena cylindrica in intact filaments or separated from vegetative cells were examined using improved methods of fixation with glutaraldehyde followed by potassium permanganate or osmium tetroxide. The heterocyst envelope, formed external to the outer layer (LIV) of the pre-existing cell wall…
A simple model of heat flow across a metal-insulator interface is used to calculate the spatial variation of the temperature. The characteristic distance for the temperature gradient to reach its bulk value is shown to be of the order of the phonon mean free path in both the metal and the insulator. Explicit expressio…
Magnetic susceptibility measurements have been made between 4.2 K and 1.1 K on single crystals of Sm, Pr and Nd magnesium nitrate and the measurements are found to obey a Curie law plus a Van Vleck temperature independent term. The results are discussed in terms of wavefunctions obtained with the approximation that th…
Low temperature crystallographic phase transitions in DyVO 4 and TbVO are attributed to a co-operative Jahn-Teller effect. A preliminary report of the theory is given, based on a harmonic oscillator Hamiltonian for the crystal and an electron lattice coupling which is small compared to typical phonon zero point energi…
In the presence of acidic phospholipids, inorganic phosphate greatly enhances the net migration of calcium ions from the aqueous phase to the organic phase, an effect that does not occur at less than the physiological pH. The calcium complex in the organic phase is shown by electron microscopy to consist of spherules,…
Rigorous bounds for the density of electronic states are given for an idealized model of a group-IV semiconductor based on the tight-binding method. These include inner bounds which define a minimum gap in the density of states. The importance of this development lies in its independence of periodicity. It applies not…
The optical properties of crystalline and amorphous ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$ and ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$ have been investigated from 1 to 14 eV. A simple rigid-band relationship connects the band structures of the two crystals, and the lowest-energy features observed near the interband thre…
In recent numerical calculations of the one-phonon inelastic neutron scattering in Bravais quantum crystals, the existence of an extra unexplained peak in the scattering cross section has been reported. It is suggested here that this peak is due to two-phonon production via an intermediate virtual phonon. An analytic…
The total inelastic cross section for the scattering of a coherent modulated electron beam, viewed as a single quantum state, is calculated. In addition to the conventional one-electron contribution, there is a many-electron interference contribution which, under proper conditions, can lead to a greatly enhanced cross…
The infrared spectra of B2Cl4 have been studied from 4000 to 33 cm−1 in the gaseous and crystalline states. The Raman spectra have been studied to 45 cm−1 in the liquid phase at several temperatures between − 30 and − 190°C, the sample being in a supercooled liquid or glassy state in the latter cases, and in the cryst…
Dielectric constants at 20, 30, 40, and 50°C have been determined for pure liquid dimethylsiloxane oligomers (CH3)3Si–[OSi(CH3)2]xOSi(CH3)3 having chain lengths corresponding to x = 3, 5, 7, and 9. Mean-square dipole moments 〈μ2〉, calculated from the Onsager equation, are in good agreement with predicted values based…
Diffusion of ${\mathrm{Ti}}^{44}$ into $\ensuremath{\beta}$-titanium has been measured as a function of pressure at approximately 1000 \ifmmode^\circ\else\textdegree\fi{}C using standard lathe-sectioning techniques. The diffusion coefficient is found to decrease with pressure, indicating a positive activation volume.…
Basic laws of motion of micropolar continuum are presented, and the adequacy of applying micropolar theory to liquid crystals is indicated. A set of constitutive equations is derived for nematic liquid crystals. Wave propagation problems are solved, and it is shown that the theoretical analysis is in good agreement wi…
The Raman spectrum of ${\mathrm{Ti}}_{2}$${\mathrm{O}}_{3}$ exhibits seven modes as predicted for the corundum structure. The persistence of all seven of these modes above the semiconductor-metal transition temperature indicates no space-group change on going through the phase transition. The ${A}_{1g}$ mode at 269 ${…
The EPR, optical absorption, and fluorescence spectra of Cr3+ in the spinel ZnGa2O4 have been measured and interpreted using a crystal-field model. The EPR experiments can be described by a spin Hamiltonian whose parameters are: 2D = + 1.048 ± 0.001 cm−1, g‖ = 1.9774 ± 0.0005, g⊥ = 1.9761 ± 0.0005. The broad band tran…
Infrared and Raman measurements of lattice vibrations in hexagonal Mo${\mathrm{S}}_{2}$ have been made over the combined range 20-4000 ${\mathrm{cm}}^{\ensuremath{-}1}$. Two infrared-active modes at 384 and 470 ${\mathrm{cm}}^{\ensuremath{-}1}$ and three Raman-active modes at 287, 383, and 409 ${\mathrm{cm}}^{\ensurem…