2,373 research outputs found
Preliminary results of measurements by automated probes Vega 1 and 2 or particle concentration in clouds of Venus at heights 47-63 KM
Results of the preliminary processing of the Vega 1 and 2 descender data on the cloud layer structure of the Venusian atmosphere are discussed. A photoelectric counter for aerosol particles is described together with its optical and pneumatic circuits and operation algorithm. Vertical profiles of concentrations of particles with a diameter of 0.4 microns agree quantitatively with the Pioneer-Venus and Venera 9 and 10 data. Concentrations of these particles are: in the B layer, up to 190/cu cm; in the C layer, up to 10/cu cm; and in the D layer, up to 130/cu cm. Layers have sharp boundaries with a significant vertical heterogeneity of the aerosol concentration field inside them
Detector for imaging of explosions: present status and future prospects with higher energy X-rays
The detector for imaging of explosions (DIMEX) is in operation at the
synchrotron radiation (SR) beam-line at VEPP-3 electron ring at Budker INP
since 2002. DIMEX is based on one-coordinate gas ionization chamber filled with
Xe-CO2(3:1) mixture at 7atm, and active Frisch-grid made of Gas Electron
Multiplier (GEM). The detector has spatial resolution of ~0.2mm and dynamic
range of ~100 that allows to realize the precision of signal measurement at a
percent level. The frame rate can be tuned up to 8 MHz (125 ns per image) and
up to 32 images can be stored in one shot. At present DIMEX is used with the
X-ray beam from 2T wiggler that has ~20 keV average energy. Future possibility
to install similar detector at the SR beam-line at VEPP-4 electron ring is
discussed.Comment: 14 pages, 15 figures. Submitted to JINS
Dipyrazolodioxadiazocines as Easily Storable and “Ready to Use” Precursors for in Situ Generation of Enolate-Iminium 1,4-Dipoles: an Atom-Economical Approach Topyrazolo[5,1-d][1,3,5]Dioxazines
The work was supported by Russian Science Foundation, project № 19-13-00290
Detector for imaging of explosions: present status and future prospects with higher energy X-rays
The detector for imaging of explosions (DIMEX) is in operation at the
synchrotron radiation (SR) beam-line at VEPP-3 electron ring at Budker INP
since 2002. DIMEX is based on one-coordinate gas ionization chamber filled with
Xe-CO2(3:1) mixture at 7atm, and active Frisch-grid made of Gas Electron
Multiplier (GEM). The detector has spatial resolution of ~0.2mm and dynamic
range of ~100 that allows to realize the precision of signal measurement at a
percent level. The frame rate can be tuned up to 8 MHz (125 ns per image) and
up to 32 images can be stored in one shot. At present DIMEX is used with the
X-ray beam from 2T wiggler that has ~20 keV average energy. Future possibility
to install similar detector at the SR beam-line at VEPP-4 electron ring is
discussed.Comment: 14 pages, 15 figures. Submitted to JINS
CYCLOADDITION OF 1,4-CNCO DIPOLES GENERATED FROM DIPYRAZOLODIOXADIAZOCINES
This work was supported by the Russian Science Foundation, project # 19-13-00290
Regiodivergent dipolar cycloaddition based on pyrrole-2,3-diones
It was previously demonstrated, that thermal decarbonylation of N-substituted 2,3-dihydro-2,3-pyrroldiones afforded imidoylketenes, whose chemical behavior largely depends on the nature of substituents at N-1. It was discovered that N-(diphenylenamino)pyrrolediones experienced facile CO-extrusion at elevated temperatures and the resulting a zwitterionic dihydropyrazolone species, which can be represented by enolate-iminium 1,4-dipole resonance form. In the absence of dipolarophiles, the products of [4+4]-cyclodimerization – bis(pyrazolo)dioxadiazocines – were formed in high yields. To this end, we generated the ketenes in the presence of alkyl vinyl ethers, aldehydes, ketenes, nitriles and isocyanides targeting products of dipolar cycloadditions. We further elaborated on the development of various synthetic schemes involving cycloaddition of these unusual 1,4-dipoles. Dipyrazolodioxadiazocines are shelf-stable "ready-to-use" precursors for an in situ generation of enolate-iminium 1,4-dipoles.This work was supported by the Russian Science Foundation, project № 19-13-00290
Measurement of decay rate and parameters at KEDR
Using the inclusive photon spectrum based on a data sample collected at the
peak with the KEDR detector at the VEPP-4M collider, we
measured the rate of the radiative decay as well
as mass and width. Taking into account an asymmetric photon
lineshape we obtained keV, MeV/, MeV.Comment: 6 pages, 3 figure
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