Materials Literature
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Abstract To obtain more useful information about the effect of the degree of stereoregularity on the motion of the polymer chain, the dielectric and dilatometric measurements were made for a series of stereoregular poly(methyl methacrylates) (PMMA). The α‐ and β‐absorptions were observed in each sample, of which the d…
Precise potential control and measurement have permitted the determination of the primary activation potential, E a , of an Fe‐24% Cr alloy in to within ± 0.5 mv and the determination of the kinetics of passivating film growth at this potential, as well as at other potentials. Small changes in potential give rise to l…
The effect of a series of ternary alloying additions on the galvanic behavior of Al‐Sn base alloys has been investigated. A group of soluble ternary elements including Bi, Zr, Mg, and Ag expands the aluminum lattice, stabilizes the Al‐Sn solid solution and either maintains or enhances the high galvanic currents observ…
Abstract A photoelectric method for the registration of the triboluminescence spectra is described. Using this method the triboluminescence spectra of LiF crystals at destruction in air, vacuum, and in an argon atmosphere are obtained. The experimental study of triboluminescence of some alkali halide crystals have bee…
The nature of freshly prepared and hydrothermally treated anodic alumina films has been studied by infra-red spectroscopy supported by electron microscopy. A comparison of the spectra obtained from freshly prepared specimens and those obtained after evacuation and deuterium exchange respectively, suggests that unseale…
Several parameters controlling the soiling of polyester/cotton fabrics have been assessed. Among those which were found to contribute were hydrophobicity of substrate, fabric construction, fabric finishes, type and concentration of detergents. Laboratory results showed that the body sebum is largely responsible for pi…
Objective estimation of the error (σFmeas) in each structure factor (Fmeas), by a procedure such as that outlined in Acta Cryst. (1964). 17, 1327, allows the indicator \cal uα = [Σ (Δ2Fmeas/σ2Fmeas) ÷ χ2m − n,α]1/2 to be evaluated, where ΔFmeas = |Fmeas| − |Fcalc|, χ2m − n,α is given by the χ2 distribution at the α-si…
The homogeneous thermal decomposition of acetic acid has been studied between 530 and 762° in a flow system. Below 600° dehydration is second-order: k= 109·52 exp(–39,300/RT) l. mole–1sec.–1, but the order falls and the Arrhenius plot curves upwards above this temperature. Above 700°, the process is first-order: k= 10…
Manufacturing processes and materials for engineers , Manufacturing processes and materials for engineers , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
Studies in Pseudomonas putida of the inducible degradation of hydroxyproline to alpha-ketoglutarate have indicated that either of the two epimers, hydroxy-l-proline or allohydroxy-d-proline, acts as an inducer of all the pathway enzymes. In a mutant lacking the first enzyme of the sequence, hydroxyproline-2-epimerase,…
The electronic absorption spectra of a series of compounds having the general formula phthalo-cyanineiron(II)(L)2 have been measured in the range 12–35 kK. L represents a ligand at one of the axial positions. In general, the spectra consist of four major bands and several minor ones. The energies of the two bands of h…
The anodic dissolution of copper at current densities of 10–150 A/cm 2 has been studied in neutral and solutions. An experimental flow system has been built which allows electrochemical measurements of the dissolution process to be performed under denned hydrodynamic conditions typical for the technical electrochemica…
Abstract— The absorption and fluorescence emission spectra of lumiflavin have been studied in nonaqueous solvents of different polarity. The corrected emission spectra show apparent mirror symmetry to the longest wavelength absorption maximum. In view of high molar extinction coefficient of the longest wavelength maxi…
Abstract— The photochemical and chemical properties of the four dimers of thymine have been studied. The extinction coefficients, reversal cross‐sections and quantum yields for reversal are presented as a function of wavelength in the range 200–289 nm. At any wavelength, the dimers have different reversal cross‐sectio…
A semi-classical theory for the effects of curve crossing on the thermal energy differential elastic scattering cross section for alkali-halide and alkali atom-halogen molecule systems is developed. It is shown how in the M-X case the cross section goes over from being determined by the ‘covalent’ potential curve to b…
B. F. Hoskins, S. A. Mason and J. C. B. White, J. Chem. Soc. D, 1969, 554b DOI: 10.1039/C2969000554B
The paper presents a simple mathematical expression which enables representation of all types of magnetisation curves over a very wide range. The equation given is ideally suited for problems which require use of the B/H curve many times, since calculations using it require only a few operations of the basic arithmeti…
The e.s.r. spectra of several low-spin d5 complexes of osmium, iridium, and ruthenium have been measured. The results are discussed in terms of ligand field theory and the stereochemistry of the complexes.
The electron-phonon interaction matrix element is examined in a modified tight-binding approximation. It is found that the matrix element is proportional to the bandwidth and therefore very small for an extremely narrow band. Paradoxically, in the usual Bloch tight-binding approximation the same matrix element which i…
Ferroresonance is defined in a way corresponding to the more general expression "jump resonance." An analytical method called the incremental describing-function method is applied to the problem of ferroresonance in power systems for a certain class of problems. In general, the method is applicable when the conditions…