Thermoacoustic instability of a plasma

The possibility of the onset of a self-excited instability in a high-temperature plasma as a result of energy released in thermonuclear interactions between ions is discussed, and the resulting instability conditions are used to investigate the behavior of a linear pinch.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 52–57, January, 1988.     

One-electron transfer in reactions of organomercury compounds with di-tert-butyl-substituted o-quinone

The reaction of bis(triethylgermyl)mercury with 3,5-di-tert-butyl-l,2benzoquinone has been investigated. It has been shown by means of ESR spectroscopy that the primary reaction step is a one-electron transfer from a germylmercurial compound to quinone, the paramagnetic species observed being o-semiquinone derivatives. The adduct, 3,5-di-tert-butyl-l,2-bis(triethylgermyloxy)benzene, is formed via the recombination of an ion-radical pair in the solvent cage. Partial exit of triethylgermyl radicals from the cage leads to the generation of hexaethyldigermane as one of the reaction products.Under more drastic temperature conditions, the same quinone reacts with diethylmercury via a one-electron transfer stap. The observed ESR spectrum has been attributed to a mercury-containing chelate of 3,5-di-tert-butyl-l,2-benzosemiquinone.     

Determination of Selenium(IV) by Stripping Voltammetry at a Mercury-Film Electrode

A procedure was proposed for the determination of selenium(IV) by stripping voltammetry on a mercury-film electrode at an electrolysis potential of +0.4 V versus the saturated silver–silver chloride reference electrode in a 1 M H₂SO₄ solution. The current of the cathodic peak is a linear function of the selenium(IV) concentration in the range from 5 × 10^–3 to 3 × 10^–1 mg/L (6.3 × 10^–8 to 3.8 × 10^–6 M) at a time of electrolysis of 30 s (t _el). The detection limit for selenium is 1 × 10^–4 mg/L (1.3 × 10^–9 M) at t _el = 300 s. It was shown that selenium(IV) can be determined in the presence of 10 mg/L Zn(II), 1 mg/L Cd(II), 0.5 mg/L Pb(II), and 0.2 mg/L Cu(II). A procedure for the determination of selenium in natural, mineral, and potable water was proposed.     

Tunable single-frequency diode laser at wavelength lambda = 1.645 microm for methane concentration measurements

This paper deals with the development of a novel single-frequency tunable diode laser with fiber-optic output for gas-analysis applications. The approach we propose is a convenient, simple and cheap solution for spectroscopy of single absorption lines of any gases having absorption bands in the optical fiber transparency window (0.7 microm/1.7 microm). The presence of fiber-optic output is an additional advantage for remote sensing applications. The laser operation is demonstrated as applied to R7 line of 2 nu(3) methane absorption band at lambda = 1.645 microm. The mode-hop-free tuning range of 35 GHz (1.2 cm(-1)) has been achieved.     

Stabilization at high temperatures

A general detailed model of polymer oxidative degradation in the presence of a stabilizer-oxygen acceptor was considered. The motion of the degradation zone boundary and the sample lifetime were obtained for various conditions of the process. In particular, it is shown that within the given concentration immobile oxygen acceptor has the best stabilizing properties. The theoretical results are compared with the experimental data obtained by using two independent methods: polymer sample cracking and a change in the ESR signal. Good agreement between theory and experiment was obtained.     

Voltammetric Determination of Rubeanic Acid

Procedures for the voltammetric determination of rubeanic acid (RA) at a mercury-film electrode were proposed. They are based on the oxidation of RA at –0.70 to –0.80 V or on the reduction of mercury sulfide, the product of RA oxidation, at –0.82 to –0.85 V (versus a saturated silver–silver chloride electrode) in a 1 M NaOH solution. The oxidation and reduction currents are linear functions of RA concentration in the ranges from 9 × 10^–6 to 3 × 10^–4 M and from 5 × 10^–6 to 3 × 10^–4 M, respectively.     

Determination of Ammonium by Stripping Voltammetry

The behavior of ammonium ions at amalgam electrodes was studied by cyclic and stripping voltammetry. It was found that the oxidation peak of an ammonium hydride amalgam can be used as the analytical signal. Conditions were selected for the determination of ammonium ions in aqueous solutions at a mercury film electrode by stripping voltammetry using potassium chloride as the supporting electrolyte. The determination limit for ammonium ions was found to be 2 × 10^–7M (0.004 mg/L). The procedure was tested in river waters of the Ob' basin and in the atmospheric air.     

Comparative Study of PHA Degradation in Natural Reservoirs Having Various Types of Ecosystems

The kinetics of polyhydroxyalkanoate (PHA) degradation in natural environment in two water reservoirs having various ecological characteristics was studied. It was shown that biodegradation of polymer essentially depends on the environment temperature and inorganic composition of water. The processes of polymer degradation under aerobic and anaerobic conditions were compared. The polymer degradation was slower under anaerobic conditions.     

The supersymmetric interpretation of the EGRET excess of diffuse Galactic gamma rays

Recently it was shown that the excess of diffuse Galactic gamma rays above 1 GeV traces the Dark Matter halo, as proven by reconstructing the peculiar shape of the rotation curve of our Galaxy from the gamma ray excess. This can be interpreted as a Dark Matter annihilation signal. In this Letter we investigate if this interpretation is consistent with supersymmetry. It is found that the EGRET excess combined with all electroweak constraints is fully consistent with the minimal mSUGRA model for scalars in the TeV range and gauginos below 500 GeV.