Phase transition in three-dimensional quantum electrodynamics at <Emphasis Type="Italic">T</Emphasis> ≠ 0

Dynamic mass generation in 3D quantum electrodynamics (QED₃) is considered at T ≠ 0. To solve the Schwinger–Dyson equation for the Matsubara electron Green’s function, the ladder approximation is used and the corresponding photonic function is taken in the Landau gauge. In this case, the instant approximation is used for the photonic function. It is established that the process of dynamical mass generation in QED₃ at T ≠ 0 is accompanied by a phase transition. Formal analogy of transitions in the coupling constant is revealed at T ≠ 0 in QED₃, at T = 0 in QED₄, and in graphene theory. Critical values of the coupling constant and temperature, calculated numerically based on an approximate analytical solution of the Schwinger–Dyson equation are of the same orders of magnitude.     

Reaction of 2- and 3-furylmethanephosphonates with esters

2- and 3-furylmethanephosphonates are acylated with ethyl formate, diethyl oxalate, and ethyl trifluoroacetate in toluene in the presence of sodium foil to afford five phosphorylated derivatives of furylacetic aldehyde, furylpyruvic acid, and 1,1,1-trifluoro-1-(2-furyl)propan-2-one. In a chloroform solution these compounds exist in the equilibrium with their enolic forms. When treated with sodium ethylate they form sodium salts which were isolated and characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy. It was shown that in DMSO solutions sodium salts of formyl and oxalyl derivatives of 2-furylmethanephosphonate exist as mixtures of the carbanion and enolate forms. In the first case the carbanion form is predominant, while in the second one the enolate forms prevail. Sodium salt of formylated 3-furylmetanephosphonate exists only in the carbanion form, while the salt of 3-furylpyruvate is enolate. The alkylation of these salts with iodomethane proceeds at the carbon atom as well as at the oxygen one. First reaction pathway is often preferred.     

Reaction of (ethoxycarbonylfuryl)methanephosphonates with diethyl carbonate in presence of sodium foil

Reaction of (ethoxycarbonylfuryl)methanephosphonates with diethyl carbonate in presence of sodium foil is studied. It is shown that if the acidifying group is conjugated with the carbanion center of 2-furylmethanephosphonate, addition of the carbanion to the carbonyl group of diethyl carbonate takes place to give 2-furylacetic acid derivatives in high yield. Sodium salts of these CH-acids are synthesized, isolated, and characterized. Their alkylation with alkyl bromoacetates is carried out. If ethoxycarbonyl group is not conjugated with the carbanion center, conversion of starting phosphonate and yield of adduct sharply decreases. Alkyl (2- and 4-ethoxycarbonylfur-3-yl)methanephosphonates immediately after acylation with diethyl carbonate are reduced with sodium-diethyl carbonate system to form alkyl 1-(2- and 4-ethoxycarbonylfur-3-yl)-ethanephosphonates. Formation of intermediate reduction product, the phosphorylated furylacetic aldehyde is also fixed spectroscopically. Simultaneously with the reduction dealkylation of ester group of starting phosphonates and alkyl 1-(3-furyl)ethanephosphonates takes place leading to the carboxylic acid salts. Alkyl (2-methyl-5-ethoxycarbonylfur-3-yl)methanephosphonate does not take part in condensation. It gives only the products of dealkylation under the action of sodium ethylate forming from diethyl carbonate.     

Synthesis of aminomethyl derivatives of phosphonocarboxylates of the furan series

By reaction of halomethyl derivatives of phosphonocarboxylates of the furan series with sodium azide corresponding azidomethyl compounds were synthesized. Treating them with triphenylphosphine in ethanol results in primary amines. Seven of the twelve possible position isomers of the aminomethyl phosphonocarboxylates were obtained. Method was found of selective dealkylating phosphonates leaving intact the ester group present in the molecule.     

Vibrational spectra and structure of 1,2,4-triazole derivatives

The frequencies and forms of the normal vibrations of 3-nitro-1,2,4-triazole, its 1-deuteroand 1-methyl derivatives, and 1-methyl-3-nitro-5-chloro(bromo)-1,2,4-triazole, which are classified as having C_S group symmetry, were calculated. The potential energy constants were refined by solution of the reciprocal spectral problem, and the frequencies in the experimental spectra were assigned to the principal types of vibrations.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 707–712, May, 1973.     

Differential inhibition of postnatal brain,spinal cord and body growth by a growth hormone antagonist

Background  

Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH.     

Effective potential, the structure of fermion vacuum, and the mechanism of chiral symmetry breaking in QED3

Elementary-particle Physics and Field Theory

Effective potential, the structure of fermion vacuum, and the mechanism of chiral symmetry breaking in QED₃     

Berezin kernels and maximal degenerate representations associated with Riemannian symmetric spaces of Hermitian type

We introduce the Berezin kernels for Riemannian symmetric spaces of Hermitian type by restricting the maximal degenerate representations of the corresponding noncompactly causal Lie groups. Bibliography: 20 titles.Published in Zapiski Nauchnykh Seminarov POMI, Vol. 292, 2002, pp. 11–21.This revised version was published online in April 2005 with a corrected cover date and article title.     

Thin films of mesoporous silica: preparation and characterization

Preparation of mesoporous materials in a thin film geometry was first reported in 1996. Recently, improvement of the preparation methods yielded stable films with well-defined symmetries, controlled pore orientation, continuity and film thickness. The ability to tailor film properties is important for their utilization in applications ranging from catalysis to microelectronics, where morphological control in the meso-domain is vital.     

Aminomethyl derivatives of furancarboxylic acids in the Paal-Knorr reaction

Aminomethyl derivatives of furancarboxylic acids react with 1,4-dicarbonyl compounds under Paal-Knorr reaction conditions to form the pyrrole ring. It is found that α-aminomethyl derivatives of furancarboxylic acids react faster than their β analogs. The carboxy group adjacent to the aminomethyl fragment decelerates the process.