Materials Literature
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Abstract The rate of oxygen permeation through La1−xSrxCo1−yFeyO3−δ was found to increase with an increase in Sr or Co content, showing that the permeability was mainly controlled by the amount of oxygen vacancies. The results obtained indicate that mixed conductive perovskite-type oxides are promising materials for o…
Data obtained in recent years on the epoxidising agents and the mechanism of their interaction with olefins are surveyed. Different types of hydroperoxides as well as certain short-lived epoxidising intermediates of the molecular and radical types functioning in situ are examined. The results of the stereospecific epo…
We present measurements and analysis of the basal thermal conductivity for two dichalcogenides: $1T$-Ta${\mathrm{S}}_{2}$ and $2H$-Ta${\mathrm{Se}}_{2}$. The data which are obtained for the first time cover the range 80-400 K. The lattice contribution is important for each compound and possesses specific features rela…
A description is given of the use of the Fresnel zone plate as a focusing or a frequency-filtering device at millimeter wavelengths. Sample design data are given, as well as references to prior results. A newer type of zone plate is discussed which employs two dielectrics of equal thickness to produce a flat zone plat…
The order parameter and anisotropy (elongation) of the configurations of a nematic polymer in the nematic phase are calculated. At low temperatures exponentially rapid growth of chain dimensions as a function of inverse temperature is found. In the nematic direction the chain eventually adopts a rod-like state. The th…
Silicon surface reconstructions are directly observed in profile by high-resolution transmission-electron microscopy. Low-energy surface facets are formed at edges by in situ annealing of a 〈110〉 thin specimen at an ambient pressure of ${10}^{\mathrm{\ensuremath{-}}9}$ Torr. As well as 〈111〉, 〈100〉, and 〈110〉 reconstr…
We report the first realization of a quasiperiodic (incommensurate) superlattice. The sample, grown by molecular-beam epitaxy, consists of alternating layers of GaAs and AlAs to form a Fibonacci sequence in which the ratio of incommensurate periods is equal to the golden mean $\ensuremath{\tau}$. X-ray and Raman scatt…
A molecular theory for smectic A liquid crystals is described which starts from an expression for the internal energy in terms of the orientational and translational order parameters. This expression is used to determine the single particle distribution function by invoking the molecular field approximation. The relat…
The application of x-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) to the solution of complex real world catalyst problems is often difficult and frustrating. Three recent developments in this laboratory have greatly aided in the solution of such problems. These are 1) a dual anode x-ray s…
An attempt is made to study the heating rate dependence of the peak and position of the maximum depolarization current in ITC measurements. It is observed that the area under the ITC curve, where depolarization current is plotted as a function of time remains unchanged at different heating rates. Mathematical equation…
Electron microscopic evidence is presented for the presence of discommensuration walls in incommensurate ferro-electric-ferro-elastic Ba2NaNb5O15 and its homologues Sr2KNb5O15 and Pb2KNb5O15. The displacement vector of the discommensuration walls is one fourth of a lattice vector of the orthorhombic commensurate super…
By means of electron irradiation the amorphous state can be produced in quasicrystalline and crystalline Al14 at% Mn. The transitions between these three phases are studied in situ in a high-voltage electron microscope. The behaviour of the quasicrystalline phase exhibits features distinctly different from those of t…
Two series belonging to the systems (TeO2)100−x–(WO3)x and (TeO2)100−x–(ZnCl2)x [0 ≦ x ≦ 33.8%] are prepared in the glassy state. The infra-red spectra of the two series are studied in the range 200 to 4000 cm−1. The main IR absorption bands in both series are related to the characteristics of TeO2. The detected shift…
Procedures were developed for the optimal solubilization of D-lactate dehydrogenase, D-mandelate dehydrogenase, L-lactate dehydrogenase and L-mandelate dehydrogenase from wall + membrane fractions of Acinetobacter calcoaceticus. D-Lactate dehydrogenase and D-mandelate dehydrogenase were co-eluted on gel filtration, as…
For silica (pure and synthetic) optical fibers, on which tensile stresses from 0 to 4 GPa were imposed, Raman studies were carried out. It has become evident by deconvoluting the silica Raman peaks that the main peak intensity at 440 cm−1 decreases with increasing stress while the peaks at 490, 604, and 800 cm−1 remai…
A series of platinum-oxygen alloys were grown by sputter deposition using a platinum target and rf-excited, oxygen-bearing discharges. The films were deposited on water-cooled single-crystal silicon and glass substrates. Optical behavior in the near-ultraviolet–visible–near-infrared region was studied by spectrophotom…
A simple explicit dispersion relation is given for the surface plasmon of a semi-infinite layered electron gas. Two limiting cases are discussed. Effects of the optical phonons and magnetic field are discussed.
Numerical results are presented on transmission, reflection, and color of the recently described, supertwisted birefringence effect for highly multiplexed liquid-crystal displays. The electro-optical properties, which are investigated for normal and oblique incidence of light assuming a multiplexed duty cycle of 1/100…
A simple, three-constant pressure-volume-temperature PVT equation of state, previously applied to polymer liquids, is applied to polymer solids, both crystalline and amorphous. In terms of reduced variables P̄=P/B0, V̄=V/V0, and T̄=T/T0, the equation P̄ V̄5=T̄3/2−ln V̄ fits experimental volume data taken from the lite…
We report the observation of complete rf-induced mode locking in the charge-density-wave (CDW) state of ${\mathrm{NbSe}}_{3}$. Over each mode-locked region, the CDW phase velocity is uniquely determined by the frequency of the rf field, and all broadband noise normally associated with CDW conduction is absent. These o…