Additive coloration of crystals of calcium and cadmium fluorides

The particular features of additive coloration—formation of color centers as a result of annealing in a reducing atmosphere—have been considered for two crystals with fluorite structure, calcium and cadmium fluorides. The significant differences in the processes of coloration of these crystals are related to both the chemical reactions on their surface and the interaction (or absence of such) between the two components diffusing into the crystal bulk: anion vacancies and electrons.     

Dilatometric method of investigating the phase transitions of elastomers in the deformed state

A method is proposed for investigating crystallization and melting processes in vulcanizates in relation to the change of volume of specimens in the compressed or extended state. The method combines the advantages of dilatometry (accuracy of quantitative estimates) and mechanical methods (possibility of acceleration of crystallization associated with orientation of the macromolecules). The vulcanizates are tested under realistic conditions. Vulcanizates of NT Nairit and cis-1,4-polybutadiene have been tested by means of the method described; the crystallization kinetics are shown to depend on the degree of extension and compression of the specimens.Lebedev All-Union Scientific-Research Institute of Synthetic Rubber, Leningrad. Translated from Mekhanika Polimerov, No. 5, pp. 780–784, September–October, 1970.     

Neutron-neutron angular correlations in spontaneous fission of <Superscript>252</Superscript>Cf

An experiment has been carried out to study neutron-neutron angular correlations in spontaneous fission of ²⁵²Cf. Angular dependences of the number of neutron-neutron coincidences obtained in the experiment were compared with the results of the Monte Carlo calculations for various neutron detection thresholds in the range 425–1600 keV. It was inferred that 10–11% of the total number of prompt neutrons from ²⁵²Cf (s.f.) in the laboratory system were emitted isotropically and may probably be interpreted as neutrons directly associated with the instant of scission of the nucleus. The analysis allowed their energy distribution to be determined as well. A similar method was also used to describe the angular correlation of prompt neutrons that accompanied the reaction ²³⁵U(n _th ,f).     

Fabrication of LIGA masks for microfluidic analytical systems

Preliminary results of fabrication and testing of LIGA mask samples for deep x-ray lithography in the spectral range of 3.5–13.5 keV are presented. The mask fabrication method is based on direct mask patterning with minimum element sizes of ≥ 10 μm by a synchrotron radiation x-ray microbeam. Such a method does not require an intermediate mask, which significantly simplifies fabrication and reduces the laboriousness and cost of LIGA masks.     

High-Temperature Heat Capacity and Thermal Extension of FeTa2O6

Physics of the Solid State - The heat capacity of synthesized iron tantalate FeTa2O6 was measured in the temperature range of 323–1103 K by the ratio method using a thermal analyzer combining...     

Kinetic study of the reaction of nucleophilic cyclopropanation of C60 fullerene with halogenated maleopimarimide

The kinetics of nucleophilic fullerene cyclopropanation by halomethyl ketones with a diterpene fragment has been studied by the Bingel method, and the influence of the biologically active cyclopropanating agent on the process has been estimated. It has been revealed that favorable conditions for carrying out the reaction result in maximum monofunctionalized methanofullerenes formation with the maximum yield.     

Structures of two high-temperature Dy2TiO5 modifications

Single crystals of two structural modifications of high-temperature dysprosium titanate Dy₂TiO were grown. Using X-ray diffraction, the crystal structure of the cubic modification (space group Fd3m, a = 10.28(1)Å, Z = 10.4) was refined and the structure of a new monoclinic modification (space group B2/m, a = 10.33(1)Å, b = 3.653(5)Å, c = 7.306(6)Å, β = 90.00(7)°, Z = 2.4), which crystallizes in minor amounts together with the cubic phase, was determined. The lowering of symmetry from cubic to monoclinic is due to different distributions of the Dy³⁺ and Ti⁴⁺ cations over the sites present in the cubic cell.     

A novel heteropolycyclic system from n-methylquinoxalinium iodide and nitroethane

Reaction of N-methylquinoxalinium iodide with nitroethane results in either the 1:2 diadduct at C-2 and C-3 or the formation of substituted 1,3,6,10-tetraazatetracyclo[7.3.1.0.^2,70^6,13] tridecane derivative.     

11-Aryl-3,3-dimethyl-7- and 7,8-Substituted 1,2,3,4,10,11-Hexahydro-5H-dibenzo[b,e]-1,4-diazepin-1-ones

In reactions of 3-(5- and 5,6-substituted 2-aminophenylamino)-5,5-dimethylcyclohex-2-en-ones with carbaldehydes of pyridine, thiophene, and furan and substituted benzaldehydes, we have obtained 21 novel 7H-7-methoxycarbonyl-, 7-benzoyl-, 7-trifluoromethyl-, 7-nitro- and 7,8-dichloro-11-aryl-3,3-dimethyl-1,2,3,4,10,11-hexahydro-5H-dibenzo[b,e]-1,4-diazepin-1-one.     

Reactions of 4-oxobenz[1,3-e]oxazinium perchlorates with α-aminoazoles

Reactions of 4-oxo benz[1,3-e]oxazinium perchlorates with 1-R¹-3-R²-5-aminopyrazoles lead to the formation of derivatives of pyrazolo[3,4-d]pyrimidine and pyrazolo[1,5-a]1,3,5]triazine series, and with 3-amino-1,2,4-triazole, to [1,2,4]triazolo[1,5-a][1,3,5]triazines.