Analysis of fragment mass distribution in asymmetric area at fission of <Superscript>235</Superscript>U induced by thermal neutrons

The fragment mass yields in fission of ²³⁵U induced by thermal neutrons for A = 145–160 and E_K = 50–75 MeV were measured using a mass spectrometer. The fine structure is observed at A = 153, 154 and E_K = 50–60 MeV. The obtained results were described in the framework of a model based on the dinuclear system concept. The analyzed correlation between the total kinetic energy and mass distribution of fission fragments is connected with the shell structure of the formed fragments of fission. From this correlation and the time dependence of the calculated mass distribution of the binary reaction products, one can conclude that the descent time from a saddle point to a scission point for the more deformed fragments is longer than that for fragments of more compact shape.     

Isolation of a ca-channel blocker from the venom of the spiderAgelena labirintica

From the venom of the spider Ageiena labirintica we have isolated the neurotoxin Agll (IV-6-1) with a molecular mass of 1000 Da, which effectively blocks the Ca channels of presynaptic membranes of frog nerve-muscle synapses.Institute of Physiology and Biophysics, Academy of Sciences of the Republic of Uzbekistan, 700095, Tashkent, ul. Niyazova, 1. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 467–470, May–June, 1995. Original article submitted October 24, 1994.     

ESR spectrum of the oxidized vanadylporphyrin complex of Karazhanbass petroleum

As a result of the use of various oxidants, mono- and bications of the natural vanadylporphyrins of Karazhanbass petroleum have been obtained, and their ESR spectra have been studied.Institute of the Chemistry of Petroleum and Natural Salts of the Kazakh SSR Academy of Sciences, Gur'ev. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 190–193, March–April, 1990.     

Structural transformations in Cu<Subscript>1.95</Subscript>Ni<Subscript>0.05</Subscript>S crystals

A solid solution of the Cu_1.95Ni_0.05S composition has been synthesized for the first time due to the partial replacement of Cu with Ni atoms in Cu₂S. The polymorphic transformations in the polycrystalline samples in the temperature range of 300–1400 K have been investigated by X-ray diffraction and differential thermal analysis. It is established that, at room temperature, the synthesized Cu_1.95Ni_0.05S samples have an orthorhombic lattice with unit-cell parameters a = 26.50 Å, b = 15.39 Å, and c = 13.85 Å (sp. gr. Abm2). Heating to T = 379 ± 2 K leads to its transformation into a hexagonal lattice with parameters a = 3.960 Å and c = 6.78 Å (sp. gr. P6₃/mmc). At 750 ± 2 K, the hexagonal modification is transformed into a cubic one with period a = 5.788 Å (sp. gr. Fm\(\bar 3\)m). The phase transition in this crystal is enantiotropic.     

Effect of the entrance channel on the synthesis of superheavy elements

Cross-sections for the synthesis of superheavy elements were analyzed using the concept of a dinuclear system. Experimental values for the production of elements Z = 104, 108, 110, 111 and 112 by cold fusion reactions with targets of ²⁰⁸Pb and ²⁰⁹Bi were reproduced. The model reveals the importance of entrance channel dynamics and competition between quasi-fission and complete fusion processes. Energy windows were observed which allow capture of the reacting nuclei and formation of the compound nucleus. The quantities were studied which are significant for the interaction dynamics of massive nuclei in the entrance channel.     

The structure of nitrarine

Summary Dehydrogenation of the alkaloid nitrarine with selenium has given 3-(quinolin-8-yl)--carboline (II) and 3-(5, 6, 7, 8-tetrahydroquinolin-8-yl)--carboline (III).On the basis of the results of a study of the chemical and physical properties of nitrarine, and also from the results of x-ray structural analysis, structure (I) has been established for it.Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow, Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 334–345, May–June, 1976.     

X-ray structural investigation on alkaloids V. Crystal and molecular structure of sibiricine

Summary A complete x-ray structural investigation of the spirobenzy1isoquinoline alkaloid sibiricine in the form of the base has been carried out. The bond lengths and valence angles are the usual ones.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 752–758, November-December, 1978. Original article submitted July 4, 1978.