Pyridinyl trifluoromethanesulfonates: preparation methods and use in organic synthesis

The methods for the synthesis of pyridinyl trifluoromethanesulfonates are reviewed. Examples of their use in organic synthesis for the production of valuable products are presented.     

Frequency spectrum of tantalum at temperatures of 293–2300 K

The temperature dependence of the frequency spectrum of tantalum in the temperature range from room temperature to 2300 K has been studied for the first time using inelastic slow-neutron scattering. The inelastic slow-neutron scattering spectra have been measured at different temperatures on a DIN-2PI time-of-flight spectrometer installed at the IBR-2 nuclear reactor (Joint Institute for Nuclear Research, Dubna, Russia) with the use of a TS3000K high-temperature thermostat. From the measured spectra, the frequency spectra of the tantalum crystal lattice have been determined at temperatures of 293, 1584, and 2300 K by the iteration method. As the temperature increases, the frequency spectrum, on the whole, is softened and the specific features manifested themselves at room temperature are smoothed. The variations observed have been explained by the increase in the role of the effects of vibration anharmonism at high temperatures.     

Macroscopic evidence of soliton formation in multiterawatt laser-plasma interaction

A novel physical phenomenon has been observed following the interaction of an intense (10(19) W/cm(2)) laser pulse with an underdense plasma. Long-lived, macroscopic bubblelike structures have been detected through the deflection that the associated electric charge separation causes in a proton probe beam. These structures are interpreted as the remnants of a cloud of relativistic solitons generated in the plasma by the ultraintense laser pulse. This interpretation is supported by an analytical study of the soliton cloud evolution, by particle-in-cell simulations, and by a reconstruction of the proton-beam deflection.     

Detection of B-FSK signals using schmidt trigger

Possibility to record B-FSK signals with use of stochastic resonance is studied. A Schmidt trigger is employed as bistable stochastic resonator. A digital model of the detector is proposed and quantitative results are obtained by means of simulations. Dependence of the probability of correctly detected bits on the added noise power and on the low-pass filter cutoff frequency is studied. Also the stability of the detector with respect to channel-introduced phase shifts is revealed.     

Dienone ⇆ 2H-pyran valence isomerization. (Review)

The researches of the author and her colleagues on the synthesis of -dicarbonyl-containing dienes with various structures and study of their valence isomerization to 2H-pyrans¹H by an¹³C NMR, UV, and IR spectroscopy and flash photolysis are reviewed.N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 14431461, November, 1999.     

Formation of extra- and intracellular amino acids by micromycetes

A comparative study has been made of extra- and intracellular amino acids in the dynamics of the growth and development of the cellulolytically active fungusTrichoderma harzianum and of a protoplast culture and a hybrid culture of the fungus obtained by the methods of cell engineering.Institute of Microbiology, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 41 71 29. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 94–100, January–February, 1998.     

Synthesis based on β-phenylethylamines X. Synthesis of new derivatives of phenylethylaminomethylbenzo-crown ethers

Three methods have been developed for the introduction of a β-phenylethylamine fragment into a benzo-crown ether molecule. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 796–800, November–December, 1998.     

The accuracy of a discrete spectral problem with mixed derivatives

The accuracy of a difference spectral problem for a second-order elliptic equation with mixed derivatives and constant coefficients is estimated. In so doing, the fact that the eigenfunctions belong to the Sobolyev space W ₂ ² in a rectangle is used. Bibliography: 6 titles. Translated fromObchyslyuval’na ta Prykladna Matematyka, No. 76, 1992, pp. 59–66.