FT IR ATR Study of Molecular Interactions in the Urea/Dimethyl Sulfoxide and Urea/Diethyl Sulfoxide Binary Systems

FT IR ATR spectra of urea/dimethyl sulfoxide and urea/diethyl sulfoxide mixtures in the S=O and N—H stretching vibration regions at different molar ratios have been measured. On the basis of the band deconvolution data, various types of intermolecular associated forms, including dimers and hydrogen-bonded urea–sulfoxide complexes, have been revealed. The latter has been confirmed also by ab initio calculations.     

Hydrocarbomethoxylation of 1-hexene with formic acid and methanol under conditions of phosphoric acid catalysis

Conclusions When the hydrocarbomethoxylation of 1-hexene with formic acid is run at atmospheric pressure and temperatures close to room temperature, in the presence of conc. H₃PO₄, an increase in the relative amount of the latter, as well as an increase in the reaction temperature in the investigated range, both favor an increase in the yields of the methyl esters of the C₇ acids, in particular, those containing two methyl groups on the quaternary carbon atom in the -position. An increase in the relative amount of formic acid also favors an increase in the amounts of these esters in the obtained mixtures of esters.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1116–1118, May, 1971.     

Stevens rearrangement of ammonium salts containing 2-propynyloxy or tert-butoxycarbonylmethyl groups

The Stevens rearrangement of ammonium salts containing 2-alkenyl, 2-alkynyl, or benzyl groups along with 2-propynyloxy or tert-butoxycarbonylmethyl was studied. Under the action of a suspension of sodium phenolate in benzene the salts containing a 2-propynyloxycarbonylmethyl group form 2-propynyl esters of 2-dialkylamino-4-pentenoic acids, whereas with sodium methylate as the basic reagent, rearrangement is preceded by an almost complete transesterification. The salts containing a tert-butoxycarbonylmethyl group undergo almost no transesterification under the action of sodium methylate. The tert-butyl fragment in the ester group of the salt with a benzyl group exerts a fairly strong effect on the regiochemistry of the rearrangement and on the prototropic isomerization of the 3,2-Stevens rearrangement of the salts with 2-butynyl or 3-phenyl-2-propynyl groups.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1321–1326.Original Russian Text Copyright © 2004 by Babakhanyan, Ovakimyan, Grigoryan, Kocharyan.This revised version was published online in April 2005 with a corrected cover date.     

Structural and energetic properties of Ni-Cu bimetallic clusters

The lowest-energy structures for all compositions of Ni n Cu m bimetallic clusters with N = n + m up to 20 atoms, N = 23, and N = 38 atoms have been determined using a genetic algorithm for unbiased structure optimization in combination with an embedded-atom method for the calculation of the total energy for a given structure. Comparing bimetallic clusters with homoatomic clusters of the same size, it is shown that the most stable structures for each cluster size are composed entirely of Ni atoms. Among the bimetallic clusters in the size range N = 2-20, the Ni N-1 Cu 1 clusters possess the highest stability. Further, it has been established that most of the bimetallic cluster structures have geometries similar to those of pure Ni clusters. The size N = 38 presents a special case, as the bimetallic clusters undergo a dramatic structural change with increasing atom fraction of Cu. Moreover, we have identified an icosahedron, a double, and a triple icosahedron with one, two, and three Ni atoms at the centers, respectively, as particularly stable structures. We show that in all global-minimum structures Ni atoms tend to occupy mainly high-coordination inner sites, and we confirm the segregation of Cu on the surface of Ni-Cu bimetallic clusters predicted in previous studies. Finally, it is observed that, in contrast to the bulk, the ground-state structures of the 15-, 16-, and 17-atom bimetallic clusters do not experience a smooth transition between the structures of the pure copper and the pure nickel clusters as a function of the relative number of the two types of atoms. For these sizes, the concentration effect on energy is more important than the geometric one.     

Effect of aminoacids on the critical micellization concentration of different surfactants

The effect of aminoacids (DL-glycine, DL-alanine, DL-serine, L-leucine, L-lysine, DL-phenylalanine, DL-tyrosine, and L-aspartic acid) on the critical micellization concentration (CMC) of nonionic, anionic, and cationic surfactants is investigated. It is established that, as the hydrophobicity of aminoacids rises, the CMC values of ionic and nonionic surfactants increase and decrease, respectively. An exception is aspartic acid, which reduces CMC values irrespective of the nature of surfactants.     

On the interference absorption of X-rays in crystals with weak deformations

The problem of Borrmann absorption (anomalous absorption) of X-rays in weakly deformed crystals is considered on the basis of Takagi’s approach to the dynamical theory. Using wave function considerations, the attenuation of rays is represented by exp(−σl) where the attenuation factor σ includes a parameter of the lattice deformation field. The possibility of cases σ = 0 and even σ < 0 is discussed.     

Influence of self-phase modulation on coherent effects in five-level system

The possibility of formation of a coherent dark state in the five-level system in the entire volume of the medium in an adiabatic pulse propagation is investigated. It is shown that the dark state formation is independent on the value of the first two-photon detuning from the resonance, which may be changed during the propagation in the medium. In the case of the M-type system with the equal strengths of oscillators at the extreme transitions it is shown that the self-phase modulation does not influence the coherent effects while in the ladder-type system it may lead to the destruction of the dark state. The estimation of the length of the medium in which the propagation effects are negligible is obtained.     

The <Emphasis Type="Italic">A</Emphasis> dependence of <Emphasis Type="Italic">K</Emphasis><Superscript>0</Superscript> and Λ Neutrinoproduction on nuclei

The A dependence of the production of K ⁰ and Λ is investigated for the first time in neutrino-nuclear reactions using the data obtained with the SKAT bubble chamber. An exponential parametrization (∼A ^β) of the particle yields results in = 0.20 ± 0.05 for V ⁰ particles (K ⁰ and Λ), while for π ⁻ mesons the A dependence is much weaker ( = 0.068 ± 0.007). A nuclear enhancement of the ratio K ⁰/π ⁻ is found; this ratio increases from 0.055 ± 0.013 for vN interactions up to 0.070 ± 0.011 at A ≈ 21 and 0.099 ± 0.011 at A ≈ 45. It is observed that the multiplicity rise of V ⁰ occurs predominantly in the backward hemisphere of the hadronic system. It is shown that the A dependence of the Λ⁰ and π ⁻ yields can be reproduced in the framework of a model incorporating the secondary intranuclear interactions of pions originating from the primary vN interactions. The text was submitted by the authors in English.