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     

Investigation into transmission of complex sound signals in the human respiratory system

Lumen probing of human lungs with complex acoustic signals in the frequency band from 100 to 1000 Hz made it possible for the first time to explicitly confirm the concurrent existence of two mechanisms differing in propagation velocity behind the transmission of acoustic vibrations from the oral cavity to the thoracic cage surface. The numerical values of propagation time lags allowed one of these mechanisms to be associated with combined aerial-structural transmission and the other, with purely structural transmission.     

Analysis of tracheal noise of forced human expiration according to clinical experimental data

The analysis of tracheal noise of forced expiration is one of the promising methods for the diagnosis of bronchial patency disorders, which are a sign of such widespread diseases as bronchial asthma and chronic obstructive bronchitis. The aim of this study is the verification and refinement of the acoustic model of forced expiration (Korenbaum et al., 1998) on the basis of a statistical analysis of clinical experimental data. A sample of 127 volunteers (from 18 to 74 years old) is used as an experimental statistical model: 34 persons suffering from bronchial asthma, 21 persons suffering from chronic obstructive bronchitis, 29 healthy persons, and 43 persons liable to developing the aforementioned diseases. The following parameters are analyzed: the total duration of noise of forced expiration at the trachea, the duration of wheeze of forced expiration with frequencies from 400 to 600 Hz, and the presence of narrowband high-frequency (over 600–700 Hz) spectral components at the end of forced expiration and during the whole expiration process. Reliable differences in the parameters of tracheal noise are revealed in the groups under study. The high prognostic value (a sensitivity of 89% and a specificity of 86%) of the parameters of tracheal noise of forced expiration, which were suggested a priori as the diagnostic parameters on the basis of the acoustic model (Korenbaum et al., 1998), indirectly confirms the adequacy of this model. The biomechanical-pathophysiological interpretation of the occurrence of acoustic deviations in the experimental sample groups provides an opportunity to relate the parameters of tracheal noise of forced expiration to the degree of mechanical nonuniformity of the lungs.     

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.     

Regression Modeling of the Acousto-Biomechanical Characteristics of Wheezes during Human Forced Expiration

Within the framework of a specified acousto-biomechanical model, a possibility of explaining wheezes during forced expiration on the basis of a vortex separation mechanism is tested and the localization of the zones in the bronchial tree where forced expiratory wheezes are generated is refined. As an experimental model, a group of 18 healthy volunteers from 18 to 44 years old (median is equal 19) was used. On the basis of linear regression modeling the relationship between the principal spectral frequency of medium-frequency forced expiratory wheezes (400–600 Hz) recorded on the trachea and the standard volume flow-rates of expired air measured in computer spirometry is analyzed. The data obtained show that vortex separation in the air flow at the bronchial tree bifurcations (where a stepwise increase in the cross-section area takes place) is a probable mechanism of medium-frequency forced expiratory wheeze generation and that during the forced expiratory maneuver the vortex separation zone tends to be displaced deeper into the bronchial tree.     

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.