Variants of closing the nuclear fuel cycle

Influence of the nuclear energy structure, the conditions of fuel burnup, and accumulation of new fissile isotopes from the raw isotopes on the main parameters of a closed fuel cycle is considered. The effects of the breeding ratio, the cooling time of the spent fuel in the external fuel cycle, and the separation of the breeding area and the fissile isotope burning area on the parameters of the fuel cycle are analyzed.     

Searches for single-spin asymmetry in the inclusive production of neutral pions in the central region at a proton beam energy of 70 GeV

Results are presented that were obtained by measuring single-spin asymmetry in the inclusive production of neutral pions in the reaction p+p ↑→ π ⁰+X at x _F≈0. A beam of 70-GeV protons was extracted directly from the vacuum chamber of the accelerator by means of a bent single crystal. For transverse momenta in the range 1.0<p _T<3.0 GeV/c, the single-spin asymmetry independently measured by two detectors is zero within the errors. This result is in agreement with Fermilab data obtained at 200 GeV, but it is at odds with CERN data measured at 24 GeV.     

Photosensitivity of holographic recording media based on films of polymer compositions with cadmium sulfide nanoparticles

The effect of doping with CdS nanoparticles of recording medium films for the thermoplastic holographic recording process, which are based on photosemiconductors (oligomers and cooligomers of glycidylcarbazole) and a dielectric (a styrene copolymer with octyl methacrylate) containing a photoconductivity sensitizer, on their photosensitivity was studied. The enhancement of photosensitivity of films by doping with nanoparticles is associated with the appearance of an additional channel for transport of electrons generated from sensitizer molecules. A difference in informational properties between the oligomer and the polymer films was revealed.     

Effects of the Structural Rigidity of Polymethine Dye Molecules on Quenching of Their Photoluminescence by an Electric Field and Charge Photogeneration in Poly(N-epoxypropylcarbazole)

For photoconducting poly(N-epoxypropylcarbazole) films doped with cationic polymethine dyes used as an example, it was found that an increase in dye molecular rigidity increased the photoconductivity of the films in the region of dye absorption, quenching effect of an electric field on photoluminescence, and concentration ratio of photogenerated triplet electron–hole pairs to singlet pairs. The effects were enhanced by an increase in the quantum energy of excitation light. The results are explained by a decrease in the dissipation rate of the electronic excitation energy of dye molecules upon growing their rigidity, which accelerates singlet–triplet intersystem crossing in the photogenerated electron–hole pairs via the spin–lattice relaxation mechanism.     

Electrophysical and photophysical properties of films made from an azobenzene-functionalized polymeric cobalt complex

Electric conductivity, photoconductivity, and electro-and magneto-optical properties of films from a novel polymeric complex of 4-methacryloyloxy-(4′-carboxy-3′-hydroxy)azobenzene with cobalt were studied. Electric conductivity and visible photoconductivity are determined by the orientation effects of azobenzene groups and by charge-carrier generation and transport in the polymer films. A change in the spatial orientation of the photoinduced dipole moments of azobenzene groups in an external electric or magnetic field is accounted for by the appearance of forces acting on charged magnetic metal ions that are rigidly bound to these fragments.     

Microbiological synthesis of 7-bromo-5-(o-chlorophenyl)-3-hydroxy-1,2-dihydro-3H-1,4-benzodiazepin-2-one by immobilized actinomycetes

It has been shown that the highest yields (15%) of 7-bromo-5-(o-chlorophenyl)-3-hydroxy-1,2-dihydro-3H-1,4-benzodiazepin-2-one are obtained by the use of the cells of actinomycetes immobilized in poly(vinyl alcohol) in the presence of the cosubstrate 7-bromo-5-(o-chlorophenyl)-3-methyl-1,2-dihydro-3H-1,4-benzodiazepin-2-one.Physicochemical Institute, Academy of Sciences of the Ukrainian SSR, Odessa. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 779–783, November–December, 1981.     

Quenching of the fluorescence of riboflavin by the histidinates and alaninates of nickel,copper, and zinc

The formation of complexes of histidinates and alaninates of Ni(II), Cu(II), and Zn(II) with riboflavin (RF) in the ground state and the quenching of the fluorescence of RF by these compounds has been investigated. It has been found that the quenching of the fluorescence of RF by the Cu²⁺ and Ni²⁺ complexes is caused mainly by the nonemissive energy transfer from the donor (RF) to the metal ions. In the case of the Cu²⁺, Ni²⁺, and Zn²⁺ histidinates the formation of nonfluorescing unstable complexes (K_stab — 3–10) of the metal histidinates with RF in the ground state also contribute to the quenching. Free histidine and zinc histidinate quench the fluorescence of RF by the transfer of an electron to the excited molecule of the flavin with the formation of nonfluorescing reduced RF.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 4, pp. 488–493, July–August, 1985.     

Information media based on electron-donor oligomers

Routes for designing hole-conducting organic polymers for use in photoelectric solar-energy converters and light emitters and primarily for recording, storage, and processing of optical information are considered. New carbazole-containing radially tetrasubstituted silanes and germanes are described. It is shown that the information characteristics of holographic recording media based on oligomer compositions substantially depend on the shapes of the oligomer macromolecules.