Methods for determination of weight vector of adaptive arrays with short samples

Methods are proposed for determination of the weight vector in adaptive antenna arrays (AA) in the case of a short input-process sample, when the number of sampled vectors is smaller than the number of AA elements and an inverted correlation matrix of the interference in the AA receiving channels does not exist.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 4, pp. 493–509, April, 1994.     

Phosphorylated flavonoids as selective carboxylesterase inhibitors

1. Download high-res image (133KB)
2. Download full-size image

     

Dissociation of water by microwave radiation

The hydrogen-peroxide concentrations c(H₂O₂) in water irradiated by electromagnetic energy at frequencies of 2500 MHz and 10000 MHz are measured by means of chemiluminescence. It is concluded that water dissociation into H and OH groups is a part of the mechanism of microwave-radiation absorption.Institute of Applied Physics, Russian Academy of Sciences. Institute of Organometallic Chemistry, Russian Academy of Sciences. Translated from izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 1, pp. 149–154, January, 1994.     

Synthesis of glucosamine vinyl ether derivative and its deuterated analog

The use of calcium carbide (in the presence of H₂O) as a source of acetylene in the reaction with methyl 2-amino-4,6-O-benzylidene-2-deoxy-β-d-glucopyranoside under superbasic conditions (KF, KOH, DMSO, 130 °C, 3 h) led to the corresponding vinyl ether in 78% yield. The vinylation does not affect other reaction centers. Replacement of water with deuterium oxide in the reaction mixture gave a stable deuterated analog of this vinyl ether in 72% yield. The one-step isotopic enrichment was practically quantitative (isotopic purity >96%). Introduced deuterium atoms can be used as a convenient label in further transformations.

     

Oxidation of polyfunctional sulfides with chlorine dioxide

3-Benzylsulfanyl-4,5-diphenyl-4H-1,2,4-triazole, 5-methylsulfanyl-1-phenyl-1H-tetrazole, 2-methylsulfanyl-1H-benzimidazole, 2-benzylsulfanyl-1H-benzimidazole, and 1-butylsulfanyl-4-nitrobenzene were oxidized to the corresponding sulfoxides with chlorine dioxide using different modes of oxidant supply. The oxidation process was characterized by high chemoselectivity.     

Low-Temperature Operation Features of Proton-Exchange Membrane Fuel Cells with an Active Air Cooling

Russian Journal of Electrochemistry - Development of operation algorithms and proper design of proton exchange membrane fuel cell stacks for effective operation at various external climatic...     

Synthesis of new fluorine-containing pyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]pyridinones as promising drug precursors

Methods for the synthesis of 4-R-6,7-dihydro-1H-pyrazolo[3,4-b]pyridin-6-ones (R = CF₂SAr and 4-CFHSAr) were developed. The derivatives with R = CF₂SAr were obtained by both heterocyclization of 1-substituted 5-aminopyrazoles with ethyl 4,4-difluoro-3-oxo-4-phenylsulfanylbutanoate and replacement of the Br atom in 4-bromodifluoromethyl-6,7-dihydro-1H-pyrazolo[3,4-b]pyridin-6-ones by sodium arenethiolates. The fragment 4-CF-HSAr was introduced by replacement of the Cl atom in 4-chlorofluoromethyl-6,7-dihydro-1H-pyrazolo[3,4-b]pyridin-6-ones by sodium arenethiolates. Oxidation of 4-CF₂SPh-6,7-dihydro-1H-pyrazolo[3,4-b]pyridin-6-ones gave the corresponding sulfoxides; their structures were confirmed by X-ray diffraction data.