Cyclic deformation of aluminium and its alloys

The formation of slip bands is the main mechanism of cyclic deformation in pure Al. Their density, orientation and heights in polycrystalline Al were investigated during cycling. Types, sizes and densities of precipitates are responsible for the mode of cyclic deformation in AlCu4 pure alloy. In technical Al alloys intermetallic phases have detrimental effects on deformation homogeneity and largely govern the fatigue mechanism of the material and especially microcrack initiation.     

含氧光敏引发体系的研究——Ⅵ.二苯酮/三乙胺体系引发光聚合过程中的再次引发效应

过去,作者曾发表了多种光敏引发体系引发烯类单体光聚合的工作,在研究2,2-二甲氧基苯乙酮在氧存在下引发甲基丙烯酸甲酯光聚合时,结合在聚合物链端的引发剂碎片具有光化学活性,在光聚合反应中产生高分子自由基,发生再次聚合,出现高分子量     

Gamma-ray bursts from evaporating primordial black holes

It is believed that the detection of gamma-ray bursts from evaporating primordial black holes is highly improbable in the near future since the expected photon flux, consisting mainly of photons with energies ≳ GeV, is too low. Contrary to this point of view, we show that a large fraction of the black hole power at the final stage of evaporation (the last 10³ s) can be liberated as a burst of soft γ-ray emission of duration 10⁻¹–10³ s and luminosity 10²⁸–10³¹ erg/s in the energy range 0.1–1 MeV. According to our calculations of the black hole evaporation rate (within the Standard Model of elementary particles), when the black hole temperature exceeds approximately 10 GeV, the charged particle outflow from a black hole forms a well-defined plasma and can be described in the hydrodynamic approximation. In this case more than half of the rest energy of a black hole can be converted into soft gamma-rays due to the presence of the magnetic field with energy density comparable to that of charged particles. We consider various mechanisms leading to such transformation and estimate their efficiency. It is shown that, at least, some of the gamma-ray bursts detected by BATSE can be associated with evaporating black holes. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 1, pp. 36–45, January, 1998.     

Mikrochemie

Ohne Zusammenfassung     

The effect of LH wave on the peripheral plasma of TM-1-MH tokamak

The work is devoted to the study of the LH wave effect on the peripheral plasma of the TM-1-MH tokamak. The observed enhancement of the ion saturated current in the limiter shadow is interpreted as heating of the peripheral ions by absorption of decay waves generated in this region due to the nonlinear wave-plasma interaction.     

Polymer-polymer rectifying heterojunction based on poly(3,4-dicyanothiophene) and MEH-PPV

Thin, homogeneous films of a high electron affinity (n-dopable) polymer, poly(3,4-dicyanothiophene) (PDCTh), were prepared by in-situ thermal polymerization of 2,5-diiodo-3,4-dicyanothiophene on substrates. As a result of the presence of two cyano substituents on the thiophene backbone, PDCTh is an electronegative polymer, with the LUMO at ca. 3.6 eV and the HOMO at ca. 6.7 eV. We demonstrate the fabrication of polymer-polymer rectifying heterojunctions using PDCTh and poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) polymer layers on ITO-glass. Rectification ratios in the current voltage characteristics of these devices exceed 10.³ This device exhibits a photovoltaic effect with a dc sensitivity at -3 V reverse bias of 4 × 10^-4 A/W or quantum yield of 0.1% electrons/photon. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3115–3120, 1998     

Anreicherung von Spuren Seltener Erden aus Mineralwässern durch Ionenaustausch

In the described analysis of mineral waters, after the throughflow of the sample through a column with Dowex 50 WX 12 in H⁺ form, the main cations are first eluted by 1.6 N HCl and then the rare earths by 6 N HCl. The latter are separated by ion-exchange chromatography on Dowex 50WX8 in NH₄ ⁺ form, the elution being performed with ammonium citrate pH 4.19. The presence of rare earths in the eluate was ascertained spectrophotometrically by means of their reaction with xylenol orange in the presence of cetylpyridinium bromide. In mineral waters from the West-Bohemian spa region it was possible to find traces of trivalent La, Ce, Pr, Nd, Sm + Gd, Y, Dy, Ho, Er, Tm, Yb and Lu.     

Universal formulas for the number of partitions

In this paper, a formula that generalizes the total number of partitions of a natural number and the number of all possible decompositions of a certain number of parts can be united in the same formula. An advantage of this formula compared to similar ones is that it is given as a finite sum. Another advantage is that this amount may be expressed as a polynomial whose coefficients can be computed explicitly in an elementary form. The most important advantage of this approach is the fact that it is possible to express the results obtained in the general form, which so far in all similar attempts was not the case. From the general form we will prove as follows: (a) Partition functions, can be written with one fractal polynomial. (b) In partition functions, \(p\left( n \right) \) is the first half of its coefficients with the highest degree which are in common with all unified polynomials that form it. (c) The remaining coefficients vary. The first variable coefficient can have two values; the next coefficient can have up to six values, etc. The variability of coefficients increases as the degree of polynomials decreases up to a free member whose variability is up to \(\hbox {LCM}\left( {2,3,\ldots ,n} \right) \).