Attosecond temporal gating with elliptically polarized light

Temporal gating allows high accuracy time-resolved measurements of a broad range of ultrafast processes. By manipulating the interaction between an atom and an intense laser field, we extend gating into the nonlinear medium in which attosecond optical and electron pulses are generated. Our gate is an amplitude gate induced by ellipticity of the fundamental pulse. The gate modulates the spectrum of the high harmonic emission and we use the measured modulation to characterize the sub-laser-cycle dynamics of the recollision electron wave packet.     

RBS and XFA analysis of polyimide films from the Mir space station

The elemental composition of polyimide film contamination was studied by the RBS and XFA methods. The films were exposed to the space environment aboard the Mir orbital space station during the KOMPLAST in-flight experiment. It was shown that the prevalent deposit element was silicon, which agrees with measurements performed on other spacecrafts.     

Degradation of complexons derived from succinic acid under UV radiation

The destruction of complexons derived from succinic acid under the action of UV radiation was studied. IR spectroscopy, thin-layer paper chromatography, and complexometric titration were used to determine the destruction products of these complexons. It was found that the complexons decompose under UV irradiation substantially more easily than ethylenediaminetetraacetic acid does, and the products of their decomposition can undergo a biological utilization under natural conditions. The data obtained in the study make it possible to choose, instead of ethylenediaminetetraacetic acid, ligands that will be nearly fully destructible in the light without deteriorating the ecology.     

The lignin of the sea island cotton plant of variety S-6030 affected by fusarial wilt. I

A comparative study of the dioxane lignins isolated from healthy and wilt-affected cotton plant stems has shown thatFusarium fungi demethylate lignin and make it more oxidized than the lignin from healthy stems.     

Chemical modification of the amine group of antibiotic A-128-OP

Summary 1. Seven different derivatives of the polypeptide antibiotic A-128-OP at its -amino group have been obtained for the first time, and their physicochemical and antibiotic properties have been studied.2. It has been shown that modification of the amino group lowers the antibacterial activity of the antibiotic. Derivatives with an additional acid grouping have one fifth to one seventh of the biological activity of derivatives of the antibiotic with voluminous hydrophobic substituents.M. V. Lomonosov Moscow State University. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 632–636, September–October, 1974.     

Spectroscopic and quantum-chemical study of 5-alkoxypyridine-2- and 6-alkoxypyridine-3-carboxylic acids

The peculiarities of the structures of 5-alkoxypyridine-2- and 6-alkoxypyridine-3-carboxylic acids were studyed by experimental (IR, UV, and PMR spectroscopy) and quantum-chemical methods. It was established that both types of compounds exist in the form of dimers in the crystalline state, whereas in CC1₄, the first type exist in the form of monomers, while the second type exist in the form of dimers and monomers in dynamic equilibrium. The ability to form an intramolecular hydrogen bond and the interaction of the unshared pairs of electrons of the ring nitrogen atom and the oxygen atom of the C=0 group are among the reasons for the absence of liquid-crystal properties in 5-alkoxypyridine-2-carboxylic acids as compared with 6-alkoxypyridine-3-carboxylic acids, which have such properties. From the point of view of the electronic structures, 6-alkoxypyridine-3-carboxylic acids differ from 5-alkoxypyridine-2-carboxylic acids in that in the former the ring nitrogen atom and the COOH and OAlk groups have an identical effect on the sign of the -electron charges of the ring carbon atoms, and their -dipole moments are directed virtually along the longitudinal axis of the molecule.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 228–234, February, 1978.     

Synthesis of δ-cyclohexyl- and δ,δ-alkylene-α,α-dicarbonyl-substituted dienes and study of their valence isomerization

β-Cyclohexylacrolein, β-cyclohexylmethacrolein, or α-cycloalkylidenalkanals were condensed with methyl acetoacetate or dimethyl malonate to give the δ-cyclohexyl- and δ,δ-alkylene-substituted α,α-dicarbonyl-containing α,β∶γ,δ-dienes. The structures of the reaction products were studied using¹H NMR,¹³C NMR, and UV spectroscopy. The diene keto esters bearing no substituents at the γ-position were shown to be in fact three-component equilibrium mixtures comprised ofE- andZ-isomers of the diene (at the α,β bond) and a corresponding 2H-pyran. On the other hand, for keto esters with a Me group at the γ-position the equilibrium is shifted entirely to the 2H-pyrans. In contrast with the keto esters, dienic diesters exist only in the open form.     

Molecular and crystal structure of methyl-4-anti-hydroxyimino-1-dioxolano-13-isopropyl-10a,7-dimethylpentacyclo×[10b.8.5.04b,10b.06a,10a.01a,4a]icos-14-ene-7-carboxylate

Synthesis is performed and the molecular structure is analyzed of methyl-4-anti-hydroxyimino-1-dioxolano-13-isopropyl-10a,7-dimethylpentacyclo[10b.8.5.0^4b,10b.0^6a,10a.0^1a,4a]icos-14-ene-7-carboxylate IIa. Compound IIa C₂₇H₄₀O₄ crystallizes in monoclinic symmetry with cell parameters: a = 13.785(13) ?, b = 7.302(7) ?, c = 13.817(13) ?, β = 94.799(19)°, space group P2(1), Z = 2, d = 1.164 g/cm³. Original Russian Text Copyright ? 2009 by I. E. Smirnova, E. V. Tret’yakova, O. B. Kazakova, and Z. A. Starikova __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 393–395, March–April, 2009.