Configurational assignments in some dihydrobenzo[c]thiophenes by NMR solvent effects. Correlation of the relative chemical shifts of α-methyl groups with sulphoxide stereochemistry

The configuration of isomeric 3,3-dimethyl-1-phenyl-1,3-dihydrobenzo[c]thiophene 2-oxides was assigned on the basis of selective benzene- and TFA-induced NMR shifts. The same method was employed for assigning the α-methyl resonances of these sulphoxides. Examination of NMR data for a variety of cyclic sulphoxides revealed that in CCl₄ or CDCl₃ solution, α-hydrogen cis to S? O often resonates at higher magnetic field, while α-methyl group cis to S? O characteristically resonates at lower field, than the same hydrogen or methyl group trans to S? O, respectively.     

Non-Debye response for the structural relaxation in glass-forming liquids: test of the Avramov model

The experimentally observed characteristic features of the alpha-relaxation process in glass-forming liquids are the non-Arrhenius behavior of the structural relaxation times and the non-Debye character of the macroscopic relaxation function. The Avramov model in which relaxation is considered as an energy activation process of surmounting random barriers in liquid energy landscape was successfully applied to describe the temperature and pressure dependences of the macroscopic relaxation times or viscosity. In this paper, we consider the dielectric spectrum associated with Avramov model. The asymmetrical broadening of the loss spectra was found to be related directly to dispersion of the energy barrier distribution. However, it turns out that temperature dependence of the spectrum broadening as predicted by the Avromov model is at odds to experimental observation in glass-forming liquids.     

Human skin as arrays of helical antennas in the millimeter and submillimeter wave range

Recent studies of the minute morphology of the skin by optical coherence tomography showed that the sweat ducts in human skin are helically shaped tubes, filled with a conductive aqueous solution. A computer simulation study of these structures in millimeter and submillimeter wave bands show that the human skin functions as an array of low-Q helical antennas. Experimental evidence is presented that the spectral response in the sub-Terahertz region is governed by the level of activity of the perspiration system. It is also correlated to physiological stress as manifested by the pulse rate and the systolic blood pressure.