Synthesis of gaussian beam excited rectangular dielectric guide modes by ray theory

In the present paper, ray analysis of the wave propagation has been used to evaluate the excitation of a linear dielectric guide by a gaussian beam. The paper begins by determining the Green's function of the structure and also evaluates the excitation by gaussian beam therefrom, following Falsen and Shin [1].     

Substituted 2- and 4-benzylpyridines in the synthesis of benzo[g]quinolines and benzo[g]isoquinolines

Nitrogen-containing heterocyclic analogs of anthracene, viz., benzo[g]isoquinolines and benzo[g]quinolines, were obtained by dehydrocyclization on a K-16 catalyst of mixtures of methyl-substituted 2- and 4-benzylpyridines with methyl groups in various positions of the pyridine and benzyl rings, which are formed by benzylation of -picoline, as well as pyridine, by the Ladenburg method. The spectral characteristics of the synthesized compounds are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 673–676, May, 1980.     

The effect of pH and surfactant on the aggregation behavior of chlorin p6: a fluorescence spectroscopic study

Steady state and time-resolved fluorescence properties of chlorin P6, a potential drug for photodynamic therapy, have been investigated as functions of pH. A decrease in pH of the medium has been shown to cause protonation of the ionizable carboxylic acid side chain, leading to an increase in hydrophobicity and consequent aggregation. The aggregates dissociate on further protonation. The dissociation is explained in terms of formation of cations and their mutual repulsion. A synchronous fluorescence spectroscopic study revealed the presence of two anionic forms in equilibrium at physiological pH, with a shift in the equilibrium on slight decrease in the pH. The anionic nature of chlorin P6 in aqueous solutions at physiological pH has been confirmed by complexation with surfactants. The nature of the charge on the headgroups of the surfactants has been found to govern the formation of chlorin-surfactant complexes.     

Approach to geminally alkylated azaphthalans via a consecutive double desilylation-alkylation reaction: application to a synthesis of cerpegin

A new approach to geminally alkylated azaphthalans and an application of this chemistry to the synthesis of the pyridone alkaloid, cerpegin, is reported.     

Is the Excited‐State H‐atom Transfer in Hypericin Concerted?¶

The excited-state intramolecular H-atom transfer of hypericin (Hyp) was investigated as a function of pH in monodispersed reverse micelles formed by sodium bis(2-ethylhexyl)sulfosuccinate/heptane/water and in complexes with Tb3+ under conditions in which one of the two carbonyl groups of Hyp is incapable of accepting a hydrogen atom. The results of pump-probe transient absorption experiments provide no evidence for a concerted H-atom transfer mechanism.     

Improved virtual orbitals in perturbative calculations: The case of an average double-hole potential model

The possibility of using modified virtual orbitals generated by an average double-hole potential model in perturbative calculations of correlated potential energy curves is tested in a semi-empirical framework. Comparison is made with the results of conventional perturbative calculations.     

Activity coefficients of hydrochloric acid and ionic interactions in the system HCl-LiCl-H2O from 5 to 45°C

The activity coefficient of HCl (_A) in aqueous mixtures of HCl and LiCl was determined by emf measurements of cells without liquid junction at five values of the total ionic strength, namely 0.1, 0.5, 1.0, 2.0, and 3.0 mol-kg^–1 (m), and at nine temperatures from 5 to 45°C. The ionic strength fraction (_B) of LiCl in the mixtures was varied from 0 to 0.9. The values of log _A were found to vary linearly with the molality of salt, in accordance with the Harned rule, indicating that the properties of these mixtures are determined primarily by binary ionic interactions of the type H-Li and that ternary interactions are not significant even at I=3m. The results also support the suggestion of Robinson that the interaction parameter _H,Li is insensitive to temperature changes when I is less than 2m.On leave 1977–78 from the University of Durban-Westville, South Africa