Controlling a bunch of multiple filaments by means of a beam diameter

We demonstrate a three orders of magnitude increase and stability in the backscattered fluorescence signal from nitrogen molecules by terawatt femtosecond laser pulse induced air filaments using a new method. The method is based on squeezing the initial beam diameter using a telescope. The effect of laser shot-to-shot fluctuations was included in numerical simulations by a random distribution of the initial intensity in both squeezed and non-squeezed beams. Statistical processing of the simulation results shows that the average diameter of plasma channels as well as the total amount of free electrons generated in a bunch of multiple filaments in air is larger in the squeezed beam. Shot-to-shot stability of the simulated plasma density increases in the squeezed beam. The change of this plasma density with propagation distance is in good qualitative agreement with the change of the range-corrected nitrogen fluorescence signal with distance. PACS 42.65.Jx; 42.60.Jf; 42.68.Ay; 42.68.Wt     

Synthesis of 3,4,4'- and 2',3,4-Triaminodiphenyl Ethers

Procedures were developed for preparing 3,4,4'- and 2',3,4-triaminodiphenyl ethers by the reaction of 4-acetylaminophenol with, respectively, 4-nitro- or 2-nitrochlorobenzene, followed by nitration of the resulting 4-acetylamino-4'- or -2'-nitrodiphenyl ether, hydrolysis of the product, 4-acetylamino-3,4'- or -2',3-dinitrodiphenyl ether, and reduction of 4-amino-3,4'- or -2'-3-dinitrodiphenyl ether.     

Derivatives of Methyl N-[5(6)-(4-Aminophenylsulfanyl)benzimidazol-2-yl]carbamate and Phthalic Anhydrides. Synthesis and Biological Properties

Products of the reactions methyl N-[5(6)-(4-aminophenylsulfanyl)benzimidazol-2-yl]carbamate with phthalic anhydrides, involving the aniline nitrogen atoms, were obtained. Biological properties (embryotoxicity and toxicity) of the products and their mixtures with phase-transfer catalysts were studied. On this basis, new antihelminthic agents were developed.     

Complexing properties of the trifluoroethyl xanthate ion and volatility of its intracomplex compounds

Russian Chemical Bulletin -     

Simulation of the radiation-chemical transformations of acetic acid in aqueous solutions

A general model for the radiolysis of acetic acid and its aqueous solutions is proposed. The model adequately describes experimental data on the degradation of the acid and the formation of gases (H₂, CO₂, and CH₄) in aqueous solutions at various pH values.     

Condensed Tetrazolo-1,3,5-triazines. 1. Synthesis of 5-Polynitromethyltetrazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]-1,3,5-triazin-7-one Salts

The aziridation of 2-R-4,6-bis(trinitromethyl)-1,3,5-triazines containing electron-donor substituents has been studied. It was found that the corresponding 4-azido-2-dialkylamino-6-trinitromethyl-1,3,5-triazines are formed when R = NMe₂, NEt₂. When R = O^–NMe₄ ⁺ a novel reaction route was discovered leading to the tetramethylammonium salt of 5-polynitromethyltetrazolo[1,5-a]-1,3,5-triazin-7-one which is formed as a result of azido-tetrazole and lactim-lactam tautomeric conversion. Denitration of this salt at the trinitromethyl group occurs with retention of the tetrazolo-1,3,5-triazine structure. An X-ray analysis was carried out for the denitration product which was the dipotassium salt of 5-dinitromethyltetrazolo[1,5-a]-1,3,5-triazin-7-one.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 259–266, February, 2005.     

Radiolytic Gas Formation in Aqueous Alkali–Nitrate and Alkali–Nitrate–Aluminate Solutions Simulating Liquid Intermediate-Level Wastes

Radiolytic gas formation was measured in aqueous alkali–nitrate and alkali–nitrate–aluminate solutions simulating liquid intermediate-level wastes. The radiation-chemical yields of the gas mixture and its individual components depending on solution composition and irradiation temperature (up to 60°C) were determined. It was noted that oxygen was formed in comparatively high yields (up to 0.4 and 0.6 molecule/100 eV in alkali–nitrate–aluminate solutions at 30 and 60°C, respectively). This fact was explained by the decomposition of hydrogen peroxide, which is formed as a primary product of water radiolysis and in the combination of O^– radical ions, and by the catalytic effect of aluminate ions.     

Nitration of 4-Acetylamino-4'-nitro-, 4-Acetylamino-2'-nitrodiphenyl Sulfides and 4-Acetylamino-2'-nitrodiphenyl Ether

Nitration of 4-acetylamino-4'-nitrodiphenyl sulfide, 4-acetylamino-2'-nitrodiphenyl sulfide, and 4-acetylamino-2'-nitrodiphenyl ether yields respectively 4-acetylamino-3,4'-dinitrodiphenyl sulfide, 4-acetylamino-2',3-dinitrodiphenyl sulfide, and 4-acetylamino-2',3-dinitrodiphenyl ether.     

Backward Terahertz Radiation from a Two-Color Femtosecond Laser Filament

A change in the quasistatic magnetic susceptibility in thin plates of iron borate (FeBO₃), which is a weak ferromagnet, has been revealed at adsorption of water molecules. The measurements have been performed at room temperature with the use of the magneto-optical Faraday effect. The change of the susceptibility in saturated water vapors is about 30%. The observed effect is reversible. The time of establishing the susceptibility after the introduction of water vapors is 1.5 min, which is twice as large as the time of establishing the susceptibility after the evacuation. The effect is explained by the appearance of uniaxial surface magnetic anisotropy in the basal plane because of the adsorption of water molecules.