Multiplication Factor for Subcritical Multiplying System and the Efficiency of Source Neutrons

Physics of Atomic Nuclei - In this paper, the analysis of the relation between the multiplication factor of neutrons of the multiplying system measured in critical experiments and the system...     

Electrical breakdown of anodic aluminum oxide

Results are presented from a study of electrical breakdown of anodic aluminum oxide in a constant field with a platinum pressure electrode. Statistical breakdown parameters and their dependence on the magnitude and polarity of the applied voltage are obtained. Field and temperature dependences of breakdown delay time over the interval 10^–6–10³ sec are determined. It is shown that the experimental (E) curves can be rectified (in two segments) in the coordinates log E^–1. This indicates a possible contribution to the breakdown mechanism by both tunnel injection of electrons from the cathode and subsequent avalanche multiplication of electrons within the dielectric.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 25–29, April, 1990.In conclusion, the authors thank T. V. Shmidt and E. Ya. Khanin for assistance in the study.     

Determination of Aluminum and Beryllium by Diffuse Reflectance Spectrometry with the Use of Chromaticity Functions

Immobilized Eriochrome Cyanine R was used for the direct determination of trace aluminum and beryllium by diffuse reflectance spectrometry. Anion exchanger AV-17, silica gel Silochrom C-120, Chromaton N-Super, octadecyl silica gel, and cellulose were examined as supports. Optimal sorption conditions were found. The dependence of chromaticity functions (chromaticity coordinates, lightness, color saturation, yellowness, and whiteness) on different factors was studied. Advantages of the use of chromaticity functions rather then the diffuse reflectance coefficient were demonstrated. A method is developed for the separate determination of aluminum and beryllium using cellulose as the support; the method was used for the analysis of real samples and tested with standard samples. When solution samples of 50 and 100 mL were used, the determination limit was 0.004 g/mL for aluminum and 0.0002 g/mL for beryllium.     

Identification of impurities accumulated in the extractant in the course of purification of wet-process phosphoric acid with tri-<Emphasis Type="Italic">n</Emphasis>-butyl phosphate

Impurities accumulated in the extractant in the course of operation of the plant for purification of wet-process phosphoric acid, obtained from apatite concentrate, by extraction with tri-n-butyl phosphate are identified by IR and mass spectra.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 9, 2004, pp. 1425–1429.Original Russian Text Copyright © 2004 by Lembrikov, Konyakhina, Volkova, Perov, Kiseleva, Ershova.     

Synthesis and structure of three clusters (μ-H)Os3 [μ-1,1,4-η2-XCH2CH(CO2CH2CH3)NH2](CO)9 (X = S,O)

Institute of Inorganic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 6, pp. 108–116, November–December, 1990.     

Unusual coordination of the in(3+) atom in the decahydrated complex Na3{In[N(CH2COO)3]2}·9H2O

All-Union Scientific-Research Institute of Chemical Reagents and Ultrapure Chemical Substances. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 163–166, March–April, 1991.     

Formation of columns of anomalous water by condensation in quartz capillaries

It is shown that these columns are formed in the kinetic mode from unsaturated water vapor. The condensation coefficient for an anomalous column is much less than for ordinary water. The growth rate is dependent on the equilibration time for the concentration of the anomalous component in the column. The diffusion coefficient for the anomalous component in water is less than the self-diffusion coefficient of water by nearly an order of magnitude; this and the low volatility are to be ascribed to large molecular size. It is supposed that the molecules of the anomalous component are strong groups of H₂O molecules that are only slowly converted to monomers.     

Invariant exchange perturbation theory for multicenter systems and its application to the calculation of magnetic chains in manganites

The formalism of exchange perturbation theory is presented with regard to the general principles of constructing an antisymmetric vector with the use of the Young diagrams and tableaux in which the coordinate and spin parts are not separated. The form of the energy and wave function corrections coincides with earlier obtained expressions, which are reduced in the present paper to a simpler form of a symmetry-adapted perturbation operator, which preserves all intercenter exchange contributions. The exchange perturbation theory (EPT) formalism itself is presented in the standard form of invariant perturbation theory that takes into account intercenter electron permutations between overlapping nonorthogonal states. As an example of application of the formalism of invariant perturbation theory, we consider the magnetic properties of perovskite manganites La_1/3Ca_2/3MnO₃ that are associated with the charge and spin ordering in magnetic chains of manganese. We try to interpret the experimental results obtained from the study of the effect of doping the above alloys by the model of superexchange interaction in manganite chains that is constructed on the basis of the exchange perturbation theory (EPT) formalism. The model proposed makes it possible to carry out a quantitative analysis of the effect of substitution of manganese atoms by doping elements with different electron configurations on the electronic structure and short-range order in a magnetic chain of manganites.     

Reaction of 2-Chloropyridine-3,4-dicarbonitrile with Anilines. Synthesis of 2-(Arylamino)pyridine-3,4-dicarbonitriles

Russian Journal of Organic Chemistry - The reaction of 2-chloropyridine-3,4-dicarbonitrile with anilines in propan-2-ol in the presence of N,N- diisopropylethylamine (DIPEA) in a sealed vial at...     

Reactions of N-substituted allylacetic acid amides with selenium and tellurium tetrahalides

The addition of selenium tetrabromide to the olefinic bond of N-substituted allylacetic acid amides (reagent molar ratio 21) proceeds counter to Markownikoff's rule with the formation of tetrahydrofuran derivatives. The addition of tellurium tetrahalides under the same conditions (reagent molar ratio 11) proceeds in accordance with Markownikoff's rule with the formation of tetrahydropyran derivatives.Communication 10 in the series Electrophilic reactions of halides of elements of the sixth group; see [1] for Communication 9.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 743–745, June, 1989.