The Use of the Major Component (Solvent) As an Internal Standard in the Gas-Chromatographic Determination of Impurities

A gas-chromatographic method was proposed for determining impurities using the major component as an internal standard. This method exhibits sufficiently high performance characteristics.     

Kinetic processes in the electric discharge in SF6

The simulation of the kinetic processes in the spatially homogeneous and heterogeneous plasma of the gas discharge in SF6 is performed. The calculated time dependences of the rates of the most important processes and the concentrations of electrons, ions, and other particles that affect the plasma characteristics are presented. The calculated and experimental results are compared. The kinetic processes are analyzed and their effect on the plasma characteristics is demonstrated. The calculated data regarding the development of the plasma channel are presented. An increase in the conductivity inside the channel is discussed. Original Text ? Astro, Ltd., 2006.     

On the dynamics of a curved deflagration front

An equation describing evolution of a curved deflagration front of finite thickness is obtained for the case of an arbitrary equation of state of the “fuel”, an arbitrary type of energy release and an arbitrary type of thermal conduction. The equation is complemented by conservation laws for the mass flux and the momentum flux through the deflagration front of finite thickness. As an illustration of the method, the growth rates and the cutoff wavelengths for the linear stage of the flame instability are calculated for the case of a flame in an ideal gaseous fuel and for the case of a thermonuclear deflagration propagating in a strongly degenerate matter of white dwarfs. Zh. éksp. Teor. Fiz. 111, 514–527 (February 1997) Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor.     

Stabilization of water/n‐hexane emulsions by amphiphilic copolymers based on vinyl ethers and their polycomplexes with poly(acrylic acid)

Amphiphilic random copolymers based on vinyl ether of ethylene glycol and vinyl butyl ether as well as their polycomplexes with poly(acrylic acid) were studied as polymeric reagents for the stabilization of water/n‐hexane emulsions. The emulsion stability strongly depended on the content of vinyl butyl ether in the copolymers as well as their concentration in solution. The more hydrophobic copolymers stabilized emulsions more efficiently. An increase in the temperature and the addition of inorganic salts reduced the emulsion lifetime. The formation of interpolymer complexes between the copolymers and poly(acrylic acid) significantly influenced the stability of the emulsions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2625–2632, 2004     

129I-Mössbauer study of molecular dynamics in the organic superconductor β-(BEDT-TTF)2I3

¹²⁹ I-Mössbauer spectroscopy was applied to study the organic superconductor β _H -(BEDT-TTF)₂ I ₃ withT _c=8 K. The measurements were performed in the temperature range 1.4 K to 160 K. A detailed analysis of the well-resolved spectra, including transmission integral fits, revelas information about the hyperfine interactions and the local binding strength (f-factor) for the terminal and central sites of the linear and symmetricI ₃ ^? anion. A change in the local Debye temperature of both sites of theI ₃ ^? anions is observed around 120 K, where a phase transition was monitored by other methods. Most interesting with respect to the superconducting properties is a change of the relative intensities of the terminal and central iodine sites, which starts below 10 K and increases down to 1.4 K. This behaviour may be attributed to a libral motion of the iodine molecules and seems to be connected with the occurence of superconductivity in this system.     

Brønsted base-modulated regioselectivity in the aerobic oxidative amination of styrene catalyzed by palladium

Palladium(II)-catalyzed aerobic oxidative amination of styrene with oxazolidinone proceeds with catalyst-controlled regioselectivity: (CH3CN)2PdCl2 (1) and (Et3N)2PdCl2 (2) catalyze formation of the anti-Markovnikov and Markovnikov enecarbamate products, 3 and 4, respectively. Kinetic studies and deuterium kinetic isotope effects demonstrate that these two reactions possess different rate-limiting steps, and the data indicate that the product regiochemistry arises from the presence or absence of an effective Br?nsted base in the reaction. In the presence of a Br?nsted base such as triethylamine or acetate, the kinetically preferred Markovnikov aminopalladation adduct of styrene is trapped via rapid deprotonation of a zwitterionic intermediate and leads to formation of 4. In the absence of an effective Br?nsted base, however, slow deprotonation of this adduct enables aminopalladation to be reversible, and product formation proceeds through the thermodynamically preferred anti-Markovnikov aminopalladation adduct to yield 3.     

Characteristics of volume discharge in gaps with a small interelectrode separation

This paper examines the excitation conditions, ignition ranges, and also the energetic characteristics of high-pressure volume discharge. It is shown that, using the UV radiation of an auxiliary discharge to preionize the active medium, volume discharge turns out to be substantially more stable than if weak x-ray radiation is used, creating an initial electron concentration 10⁸ cm^–3. Data are cited which indicate that the energy entering the gas with the primary discharge increases in proportion to the increase of energy dissipated in the auxiliary discharge. Several results are reported about the effect of electric field homogeneity on the nature of the discharge progression.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 89–94, April, 1986.     

Synthesis, characterization, and theoretical study of stable isomers of C70(CF3)n (n = 2, 4, 6, 8, 10)

Reaction of C70 with ten equivalents of silver(I) trifluoroacetate at 320-340 degrees C followed by fractional sublimation at 420-540 degrees C and HPLC processing led to the isolation of a single abundant isomer of C70(CF3)n for n = 2, 4, 6, and 10, and two abundant isomers of C70(CF3)8. These six compounds were characterized by using matrix-assisted laser desorption ionization (MALDI) mass spectrometry, 2D-COSY and/or 1D 19F NMR spectroscopy, and quantum-chemical calculations at the density functional theory (DFT) level. Some were also characterized by Raman spectroscopy. The addition patterns for the isolated compounds were unambiguously found to be C1-7,24-C70(CF3)2, C1-7,24,44,47-C70(CF3)4, C2-1,4,11,19,31,41-C70(CF3)6, Cs-1,4,11,19,31,41,51,64-C70(CF3)8, C2-1,4,11,19,31,41,51,60-C70(CF3)8, and C1-1,4,10,19,25,41,49,60,66,69-C70(CF3)10 (IUPAC numbering). Except for the last compound, which is identical to the recently reported, crystallographically characterized C70(CF3)10 derivative prepared by a different synthetic route, these compounds have not previously been shown to have the indicated addition patterns. The largest relative yield under an optimized set of reaction conditions was for the Cs isomer of C70(CF3)8 (ca. 30 mol % of the sublimed mixture of products based on HPLC integration). The results demonstrate that thermally stable C70(CF3)n isomers tend to have their CF3 groups arranged on isolated para-C6(CF3)2 hexagons and/or on a ribbon of edge-sharing meta- and/or para-C6(CF3)2 hexagons. For Cs- and C2-C70(CF3)8 and for C2-C70(CF3)6, the ribbons straddle the C70 equatorial belt; for C1-C70(CF3)4, the para-meta-para ribbon includes three polar hexagons; for C1-7,24-C70(CF3)2, the para-C6(CF3)2 hexagon includes one of the carbon atoms on a C70 polar pentagon. The 10.3-16.2 Hz 7JF,F NMR coupling constants for the end-of-ribbon CF3 groups, which are always para to their nearest-neighbor CF3 group, are consistent with through-space Fermi-contact interactions between the fluorine atoms of proximate, rapidly rotating CF3 groups.