The effect of carbon content on the beginning of slip in single crystals of Fe-3·2 wt%Si alloy

Specimens with 18 ppm and 100 ppm carbon of different orientations were deformed by compression (?～1·1×10^?4 s^?1) at the temperatures 150 °K, 195 °K, 293 °K, 393 °K and 483 °K. The measuredΨ(χ) andτ(χ) curves are presented. The changes of the curves caused by increased carbon content are discussed from the point of view of the low temperature induced cross-slip. Deviations from the Schmid law of critical resolved shear stress are found for both carbon contents. The dependence of the CRSS on temperature for specimens of standard purity has a slightly different course for orientationχ=?30° than for orientationsχ=0° andχ=+30°. These deviations are discussed in terms of the influence of normal stress on the slip. The course ofΔτ (difference between the CRSS in the MRSS plane for specimens with 100 ppm and 18 ppm of carbon) onχ is discussed using different models of lattice hardening due to interstitial impurities. These models can also be applied to the explanation of deviations ofτ(χ) curves from the Schmid law.     

Polarometrische Bestimmung von Methylenblau mit Phosphorwolframsäure

Zusammenfassung Ein Mol Phosphorwolframsäure reagiert in 2,5M Salzsäure mit 5 Mol Methylenblau unter Bildung eines Niederschlages, der in Wasser und verdünnten Mineralsäuren unlöslich ist. Diese Reaktion wurde zur polarometrischen Bestimmung von Methylenblau benützt. Bei Einhaltung aller Versuchsbedingungen, besonders der Acidität der Lösung, sind die Resultate gut. Der Äquivalenzpunkt der Titration wurde unter Verwendung einer modifizierten Rechenmethode bestimmt.

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Polarometric determination of methylene blue with phosphotungstic acid

Summary One mol phosphotungstic acid reacts in 2.5M hydrochloric acid with 5 mol Methylene Blue creating a precipitate insoluble in water and in diluted mineral acids. The given reaction was applied for the polarometric determination of Methylene Blue. Under keeping of all experimental conditions, especially of the solution acidity, the results are good. The equivalence point of the titration was determined using a modified method of calculation.

     

Glass forming ability and the electrical properties of semiconducting AsxTe1−x glasses

In the binary system of As-Te semiconducting glasses the glass forming ability is evaluated using the DTA data and the conditions of glass formation are discussed. A comparison of the thermophysical parameters with the electrical activation energy is made and the linear dependence between the atomization enthalpy and the activation energy is discussed.     

External inversion,internal inversion,and reflection invariance

Having in mind that physical systems have different levels of structure we develop the concept of external, internal and total improper Lorentz transformation (space inversion and time reversal). A particle obtained from the ordinary one by the application of internal space inversion or time reversal is generally a different particle. From this point of view the intrinsic parity of a nuclear particle (elementary particle) is in fact the external intrinsic parity, if we take into account the internal structure of a particle. We show that non-conservation of the external parity does not necessarily imply noninvariance of nature under space inversion. The conventional theory of beta-decay can be corrected by including the internal degrees of freedom to become invariant under total space inversion, though not under the external one.     

Thin SiO2 films on GaAs substrates

The formation of thin dielectric SiO₂ films on n-type GaAs substrates and obtained results on the investigation of their physical and chemical parameters are described. The SiO₂ films are produced by low-temperature deposition of tetraethoxisilane in the continuous flow system with argon as a carrier gas. Some of the technological aspects of this preparation (as the growth conditions and proper apparatus) are discussed in great detail. For improvement of some typical parameters (infrared spectra, etch rate and permitivity) a suitable thermal treatment is recommended. From the results we have achieved, the potential possibilities for construction of various types of electronic devices are also proposed.The authors wish to thank Ing. I.Srb for infrared spectra measurements. The technical assistance of Mrs. O.Janouková is also greatly appreciated.     

On the connection between the continuum eigenfunctions and the dispersion function of the vlasov operator

It is shown that a function may be extracted from the continuum eigenmode of the Vlasov operator which is related to the boundary values of the dispersion function on the real axis of the complex frequency plane. The precise content and possible consequences of this relationship are investigated in detail, especially the possibility of reconstructing the dispersion function and establishing stability criteria.