非导电型各向同性手性介质中非线性旋光的宏观理论

采用经典电磁场理论描述非导电型各向同性手性介质,研究了圆偏振抽运光作用下线偏振信号光的非线性旋光现象．给出了非线性旋光角的解析表达式．用该公式计算的结果与实验结果一致.关键词：     

Estimating the effectiveness of human-cell irradiation by protons of a therapeutic beam of the joint institute for nuclear research phasotron using cytogenetic methods

The effectiveness of the impact of therapeutic proton beams in human cells with respect to the criterion of formation of chromosome aberrations in human-blood lymphocytes is estimated. The physical characteristics of radiation (proton LET at the input of the object and in the region of the modified Bragg peak) and the role of the biological factor (the differences in the radiosensitivity of nondividing cells corresponding to the irradiation of normal tissues along the proton-beam path and tumor tissues) are taken into account. The relative biological effectiveness of protons is ∼1 at the beam input of the object and ∼1.2 in the Bragg peak region. Taking into account the higher radiosensitivity of dividing cells in the G ₂ phase of the cell cycle, the irradiation effectiveness increases to ∼1.4.     

РАСПAД170Lu

The spectrum of -radiation of the radioactive isotope¹⁷⁰Lu was studied by means of two Ge(Li) coaxial semiconductor detectors. Around 150-transitions belonging to the decay of¹⁷⁰Lu were found and their relative intensities were determined. Using the relative intensities of the conversional electrons from other works the internal conversional coefficients and the multipolarities of -ray transitions in the¹⁷⁰Yb nucleus were established. Twenty new excited levels of the¹⁷⁰Yb nucleus were introduced.A comparison of the experimental results with the predictions of the superfluid and Davydov models is made. The possible existence of I=O^– excited states in the level scheme of¹⁷⁰Yb is discussed.

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On leave fromFaculty of Mathematics and Physics, Charles University, Behová 7, Praha, Czechoslovakia.

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On leave fromNuclear Research Institute, Czechosl. Acad, Sci., e, Czechoslovakia.     

DFT study on a fullerene doped with Si and N

DFT calculations are applied for some stable C₆₀, C₅₉Si, and C₅₉N hetero fullerenes. Sn and Ge atoms are doped at the same position of C₆₀. Computations are carried out at the B3LYP/cc pVDZ levels. In this work the effects of the heteroatoms, Si and N, on the structural properties of the fullerene have been studied. The structure, energetic and relative stabilities of the compounds were compared and analyzed with each other. In addition, vibrations spectra of proposed stable neutral species, as well as the infrared intensities are calculated. From the data obtained from calculation, we found that there is strong correlation between the stability of pure C₆₀ fullerene molecule and the numbers of different C-C bonds.     

Tetrathiaoxa Macrocycles with Dibenzo-subunits: A Search for New Tl(I)- and Ag(I)-Selective Ionophores

Novel S⁴O ⁿ mixed donor macrocycles (1, n=1; 2, n=2) were synthesized by the coupling reactions of corresponding dichlorides with dithiols under high dilution conditions. Synthesis and crystal structures of Tl⁺ and Ag⁺ complexes, [Tl(2)⁺ and Ag(2)⁺], with macrocycle 2 are described. The electrode based on macrocycle 2 showed excellent potentiometric sensing ability for Tl⁺ and Ag⁺ ions. This remarkable sensing of the proposed electrode can be understood in terms of the synergy effect of a soft–soft acid–base interaction and π-coordination, especially for the Tl⁺ ion, which was observed from the crystal structure of the corresponding complex.