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     

Search forββ decay of76Ge to the excited states in76Se

Lower limits on the half-life of theββ(2v+0v) decay of⁷⁶Ge to the excited states in⁷⁶Se have been obtained using the results of low-background measurements with a HPGe detector surrounded by passive germanium shielding: T_1/2(0⁺ → 2 ₁ ⁺ ) >1.1 · 10²¹ y, T_1/2(0⁺ → 0 ₁ ⁺ ) > 1.7 · 10²¹ y, T_1/2(0⁺ → 2^2/+) > 1.4 ·10²¹ y.     

Search for double beta decay of Mo with liquid argon ionization chamber (first results)

First two runs with 138.7 g of ¹⁰⁰Mo were done 9202 h and 238 h). Limits on half-lives for 0ν- and 0νχ⁰-decays of ¹⁰⁰Mo were obtained, > 2.3 · 10²¹ y and 0.8 · 10²⁰ y, respectively at 90% CL. Also the limit on the content of radioactive ⁴²Ar in the natural Ar was obtained, < 5 · 10⁻²¹ g/g. Perspectives for the future are discussed.     

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.     

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.     

Testing the Pauli exclusion principle with the NEMO-2 detector

The Pauli Exclusion Principle (PEP) was tested with the NEMO-2 detector. Limits at the 90% C.L. on the violation of PEP for p-shell nucleons in ¹²C were obtained. Specifically, transitions to the fully occupied 1s _1/2-shell yielded a limit of 4.2 · 10²⁴ y for the process with emission of a γ-quantum. Similarly limits of 3.1 · 10²⁴ y for β⁻ and 2.6 · 10²⁴ y for β⁺ Pauli-forbidden transitions of ¹²C →¹²?¹²B) are reported here. Received: 25 August 1999