Materials Literature
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The temperature dependence of the spin-lattice relaxation time of $F$ centers in KBr is investigated between 6 and 15\ifmmode^\circ\else\textdegree\fi{}K. The observed values of ${T}_{1}^{\ensuremath{-}1}$ can be fitted by a law of the form ${T}_{1}^{\ensuremath{-}1}=B{T}^{7}+C{T}^{9}$ with $B$ and $C$ independent of…
Singular instabilities at crystal growth interfaces of group-IV and III-V semiconductors lead to as-grown surfaces optical devices, however, requirethe achievement of smoth planar layers. We consider the stability of surfaces with respect to singular instabilities and show that stable planar growth interfaces occur at…
The stacking sequence and interplane and interlayer separation of $2H\ensuremath{-}\mathrm{M}\mathrm{o}{\mathrm{S}}_{2}$ and $2H\ensuremath{-}\mathrm{N}\mathrm{b}{\mathrm{Se}}_{2}$ are determined by the dynamical low-energy-electron diffraction approach. Although lateral reconstructions corresponding to alteration in…
The resistivity and activation energy $\ensuremath{\Delta}E$ in $\ensuremath{\rho}={\ensuremath{\rho}}_{0}\mathrm{exp}(\frac{\ensuremath{\Delta}E}{\mathrm{kT}})$ of flash evaporated amorphous ${\mathrm{As}}_{2}$${\mathrm{Te}}_{3}$ films were found to decrease gradually with increasing pressure until $\ensuremath{\rho}…
Monolayer structures and epitaxial growth of vapor-deposited crystalline phthalocyanine films on single-crystal copper substrates were studied using low-energy electron diffraction. At monolayer coverage, ordered layers of copper-, iron-, and metal-free phthalocyanines were observed on both Cu(100) and Cu(111). With i…
The authors have measured the photoelectron distribution curves of single-crystal faces of copper, silver and gold using photon energies of 11.83, 16.85 and 21.22 eV. The photoelectrons are collected in a narrow cone normal to the surfaces. The results show the existence of occupied surface states in the L gaps of eac…
A Monte Carlo method based on Curgenven and Duncumb's treatment (1971) is described. It is shown that the predictions of the model agree well with experimental backscattered electron energy distributions and phi ( rho z) curves. The model is used to generate phi ( rho z) curves for a wide range of analytical condition…
The $^{31}\mathrm{P}$ chemical-shift tensors $\stackrel{\ensuremath{\leftrightarrow}}{\ensuremath{\sigma}}$ have been determined as a function of temperature on going through the ferroelectric phase transition in a single crystal of K${\mathrm{D}}_{2}$P${\mathrm{O}}_{4}$, and an abrupt change in $\stackrel{\ensuremath…
Incident electrons follow a parabolic trajectory when an electric field is applied normal to the surface of a metal crystal with force vector directed outwards. Under appropriate conditions touching trajectories may be neglected, and electron-surface-plasmon scattering is dominated by trajectories with closest approac…
Semi-transparent films of gold, copper, silver and aluminium prepared by vacuum deposition techniques show filter properties of lower transmission and higher reflection in the near infrared region than in the visible region. These films are therefore used as coatings for solar control glasses and produced in large vac…
SYNOPSIS Block polymers typically undergo microphase separation in the solid state to produce a self‐reinforced copolymer system. If one of the components has a low T g while the second possesses a high T g or melting point, a thermoplastic elastomer may result. Important variables which influence properties include s…
The stoichiometric mixture proportions of any fuel with air may be expressed in terms of the air/fuel ratio (A/F)s, or its inverse fuel/air ratio (F/A)s on either a gravimetric or volumetric (molar) basis. The proportions of a non-stoichiometric mixture are often expressed in terms of percentage of fuel weakness or ri…
Dans une première partie, on décrit les systèmes magnétiques des projets de grands TOKAMAKS. L'utilisation des supraconducteurs est devenue indispensable dès la prochaine génération de TOKAMAKS. On situe les problèmes rencontrés dans ces projets par rapport à l'état actuel de la technologie des supraconducteurs. Dans…
Polyoxins A-M, which belong to the class of peptidyl-pyrimidine nucleoside antibiotics, are produced by Streptomyces cacaoi var. asoensis. Polyoxins, except C and I, are active against various phytopathogenic fungi. Polyoxins A, B and D are shown to inhibit selectively the incorporation of 14C-glucosamine into cell wa…
The mechanism of crevice corrosion in stainless steels has been studied using an electrochemical technique. Experiments were conducted based on the idea that the rate of crevice corrosion could be determined by combining the crevice potential and the polarization curve in low pH, high Cl- solutions simulating the solu…
OVER the past two years, ten vessels on intercontinental routes have been examined and found to have suffered varying degrees of microbiological deterioration of the main engine lubricating oil. In one case, the emulsification of the oil had caused severe corrosion, necessitating a crankshaft regrind. In several cases…
Desulphurization of molten ferritic stainless steel (25%Cr-Fe alloy) was studied by using plasma jet of hydrogen-argon gas mixture to which powders of various calcium bearing fluxes were supplied.The fluxes used were (6-17) wt%CaC2-CaF2, 20wt%CaO-CaF2 and 12wt%CaC2-(18-35) wt%CaO-CaF2, the diameters of powder particle…
The structure and thermal behavior of human serum low-density lipoproteins showing either a high or a low reactivity against a proteoglycan isolated from human arteries have been found to be different from each other. It is suggested that modifications in the lipoprotein surface structure induced by the physical state…
The authors have measured the normal Hall effect at liquid helium temperatures for about 250 binary and ternary nickel-based alloys. The results are analysed in terms of the two (spin) current model. For the minority spin band the Hall effect coefficient equals R 0 spin down =-6*10 -13 Omega cm G -1 , independent both…
The X-ray crystal structure of Bun4N[Cu-o-C6H4(NCONHCONH)2].CHCl3 shows that the Cu atom is formally tervalent and is co-ordinated by four deprotonated amide nitrogen atoms; the CuIII–N bonds (1·82–1·89 Å) are shorter than those found in related CuII complexes.