Long-Range Plasmons in Asymmetric Four-Layer Structure: the Phase-Polarization Contrast Method

An asymmetric fourlayer structure supporting a longrange surface plasmon mode for sensing purposes was investigated. The excitation of the plasmon modes was achieved by means of a corrugated grating. The anomalous increase in the reflectivity was observed experimentally. The phasepolarization contrast method for a longrange surface plasmon was investigated experimentally.     

Synthesis,stereochemistry, and isomeric transformations of cis- and trans-1,2-dimethyl-4-aryl-5-aroyl-2-imidazolines

The corresponding trans- and cis-1,2-dimethyl-4-aryl-5-aroyl-2-imidazolines were obtained from complexes of cis- and trans-1-methyl-2-aryl-3-aroylaziridines with BF₃ by heating with acetonitrile. The reaction proceeds with inversion of the configuration of the starting 3-aroylaziridines. In the presence of bases the complexes of cis-1,2-dimethyl-4-aryl-5-aroyl-2-imidazolines readily undergo isomerization to the corresponding trans analogs. The structures of the products were established on the basis of the IR, PMR, and mass spectra and the results of elementary analysis. The configurations of the compounds were determined by means of the Overhauser nuclear effect.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 952–957, July, 1981.     

Features of sensitized phosphorescence and delayed annihilation fluorescence spectra of coronene in frozen solutions

We have studied the sensitized phosphorescence spectra of coronene in toluene and its delayed annihilation fluorescence spectra in n-decane at 77 K. We show that as a result of perturbation of electronic states by exchange interactions, intensity redistribution occurs in both the sensitized phosphorescence spectrum and the delayed annihilation fluorescence spectrum. The nonzero probability of the symmetry-forbidden radiative 0–0 transition is explained by the lower symmetry of the bimolecular system compared with the symmetry of the coronene molecule.     

Crystal structure of ribosomal protein L1 from the bacterium <Emphasis Type="Italic">Aquifex aeolicus</Emphasis>

The crystal structure of ribosomal protein L1 from the bacterium Aquifex aeolicus was solved by the molecular-replacement method and refined to R _cryst = 19.4% and R _free = 25.1% at 2.1 Å protein consists of two domains linked together by a flexible hinge region. In the structure under consideration, the domains are in close proximity and adopt a closed conformation. Earlier, this conformation has been found in the structure of protein L1 from the bacterium Thermus thermophilus, whereas the structures of archaeal L1 proteins and the structures of all L1 proteins in the RNA-bound form have an open conformation. The fact that a closed conformation was found in the structures of two L1 proteins which crystallize in different space groups and belong to different bacteria suggests that this conformation is a characteristic feature of L1 bacterial proteins in the free form.     

IR spectra and structure of biologically active carbulose preparation

The structural features of the carbulose preparation were studied by IR spectroscopy. It was shown that its base consists of a stable dimer of pyranose rings with a cellulose matrix, while its biological activity is determined by aprotic carboxylic COO^– groups in the side chains.Kiev Polytechnical Institute. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 3, pp. 387–390, May–June, 1991. Original article submitted March 4, 1991.     

Activity coefficients for the system NaCl+Na2SO4+H2O at various temperatures. Application of Pitzer's equations

The mean activity coefficients of NaCl in the system NaCl+Na₂SO₄+H₂O at various compositions were determined in the temperature range 5–45°C from the emf of potentiometric cells. By processing the results using Pitzer's equations the mixing parameters describing the non-ideal behavior of electrolytes were calculated. The temperature coefficients of the mixing parameters were determined and found not to be significant. The mixing parameters and temperature coefficients calculated for the binary mixture can be used to describe the behavior of multicomponent systems containing NaCl and Na₂SO₄, and eventually sea water.