THEORETICAL CALCULATIONS OF THE TRANSITIONS OF PHOTOCOLORED FORMS OF CHROMENES

Abstract— –Theoretical prediction (MO-SCF-CI) of numbers, energies and intensities of transitions are compared with experimental data for the photocolored products of three types of chromenes. Generally good results are obtained. Several conclusions resulted from variation of parameters: (1) When all carbon-carbon bonds are considered equal in length, there is good agreement between experiment and theory regarding band locations and intensities, however, very poor correlation exists between theory and experiment when calculations are done on a model where the carbon-carbon bonds are alternately single and double, (2) theoretical calculations employing the Mataga approximation for the two-center repulsion integrals gives superior correlation with the experimental spectra in comparison with the Pariser-Parr approximation, and (3) variation of certain parameters (as I.P., E.A., β) did produce changes in the results, especially in the oscillator strengths, but there was no clear best choice, and therefore, conventional parameters were used.     

CYTOTOXIC AND MUTAGENIC EFFECTS OF THE PHOTODYNAMIC ACTION OF CHLOROALUMINUM PHTHALOCYANINE AND VISIBLE LIGHT IN L5178Y CELLS

Abstract The cytotoxic and mutagenic effects of chloroaluminum phthalocyanine (CAPC) plus red light have been measured in strains of L5178Y mouse lymphoma cells which differ in their DNA repair capacities. Strain LY-R, deficient in the excision repair of UV-induced dimers, was found to be relatively more sensitive to the cytotoxic effects of CAPC plus light, whereas strain LY-S, deficienl in the repair of DNA double-strand breaks, was more sensitive than strain LY-R to the mutagenic effects of the treatment. Mutation frequencies were measured in LY-S and LY-R sub-strains which were heterozygous or hemizygous at the thymidine kinase (tk) locus. The mutation frequency at the tk locus induced in the heterozygous strain LY-SI by CAPC plus light was lower than that induced by an equitoxic dose of ionizing radiation but similar to that induced by an equitoxic dose of UVC radiation: The mutation frequency at the F., dose of CAPC plus light was approximately 1100 per 10⁶ surviving cells. The induced frequency in strain LY-S1 was much higher than in either tk+l-heterozygous or ik+10 hemizygous strains of LY-R. The rate and extent of incorporation of CAPC by the LY-R strains was somewhat greater than for strain LY-S1 at early times after CAPC addition, but by the time the cells were irradiated (18 h after CAPC addition) the difference was not great enough to account for the difference in cytotoxicity. It is possible that the cytotoxic and mutagenic lesions differ and that either the quantities of the respective lesions induced or the efficiencies of repair of the respective lesions differ inversely in the two strains. light have been measured in strains of L5178Y mouse lymphoma cells which differ in their DNA repair capacities. Strain LY-R, deficient in the excision repair of UV-induced dimers, was found to be relatively more sensitive to the cytotoxic effects of CAPC plus light, whereas strain LY-S, deficienl in the repair of DNA double-strand breaks, was more sensitive than strain LY-R to the mutagenic effects of the treatment. Mutation frequencies were measured in LY-S and LY-R sub-strains which were heterozygous or hemizygous at the thymidine kinase (tk) locus. The mutation frequency at the tk locus induced in the heterozygous strain LY-SI by CAPC plus light was lower than that induced by an equitoxic dose of ionizing radiation but similar to that induced by an equitoxic dose of UVC radiation: The mutation frequency at the F., dose of CAPC plus light was approximately 1100 per 10⁶ surviving cells. The induced frequency in strain LY-S1 was much higher than in either tk+l-heterozygous or ik+10 hemizygous strains of LY-R. The rate and extent of incorporation of CAPC by the LY-R strains was somewhat greater than for strain LY-S1 at early times after CAPC addition, but by the time the cells were irradiated (18 h after CAPC addition) the difference was not great enough to account for the difference in cytotoxicity. It is possible that the cytotoxic and mutagenic lesions differ and that either the quantities of the respective lesions induced or the efficiencies of repair of the respective lesions differ inversely in the two strains.     

Approximation of non-monotone multivalued differential inclusions

An approximation of non-monotone, multivalued differential inclusions,the so-called hemivariationa] inequalities, is presented. Arelation between the approximation problem and the problem offinding a substationary point of an approximation of the correspondingpotential function is also established. This relation makesit possible to solve the approximated problem by using nonsmooth,non-convex optimization methods. Some numerical experimentsare also presented.     

THE SPECTROSCOPY AND PHOTOCHEMISTRY OF NATURALLY OCCURRING AND SYNTHETIC CHROMENES

Abstract— –All naturally occurring and synthetic chromenes studied exhibit photochromism at — 196°C and in some cases at room temperature. Chromenes containing a coumarin moiety have the least photochemistry and also exhibit the strongest emissions. Chromenes containing a hydroxyl group ortho to an acetyl group exhibit solely a phosphorescence. Lapachenole (a 7,8-benzochromene) shows the most rapid and highest percentage conversion to the colored form and no emission. Photocolored form of evodione can be produced by a triplet energy transfer from benzophenone.     

Computer simulations of soft repulsive spherocylinders

Computer simulations of systems of soft repulsive spherocylinders (SRS) of aspect ratio (L/D) equal to 4 have been carried out using the parallel molecular dynamics program GBMOLDD. At sufficiently high densities the system forms stable nematic and smectic-A liquid crystalline phases. Results are presented for a series of seven isochores in the NVE ensemble, and for isobars at T? = kT/?= 0.5, 1.0, 1.5 in the NpT ensemble.     

Rotational viscosities of Gay-Berne mesogens

Rotational viscosities γ₁ are calculated for three Gay-Berne models for a wide range of state points in the nematic phase. There was a strong density dependence in the results, with γ₁ increasing with increasing density. Away from the clearing point, the temperature dependence of γ₁ was described by simple Arrhenius-like behaviour. A comparison of the values of γ₁ and the Arrhenius activation energies with real mesogens pointed to a number of problems with the Gay-Beme potential, when used as a model for real mesogenic systems.     

Pion showers in highly granular calorimeters

New results on properties of hadron showers created by pion beam at 8?C80 GeV in high granular electromagnetic and hadron calorimeters are presented. Data were used for the first time to investigate the separation of the neutral and charged hadron showers. The result is important to verify the prediction of the PFA algorithm based up to now on the simulated data only. Next, the properties of hadron showers were compared to different physics lists of GEANT4 version 9.3.