Reactions of Alkyl 1H,1H-Perfluoroalkyl Sulfones with Ammonia, Amines, and Hydrazines

2,2,3,3-Tetrafluoropropyl and 2,2,3,3,4,4,5,5-octafluoropentyl alkyl sulfones react with ammonia, primary and secondary amines, hydrazine hydrate, phenylhydrazine, and N,N-dimethylhydrazine to afford, depending on the length of the polyfluoroalkyl chain and reaction conditions, the corresponding enamines, imines, or mono- and bis-hydrazones. The bis-hydrazone obtained from phenylhydrazine and 2,2,3,3,4,4,5,5-octafluoropentyl benzyl sulfone is capable of undergoing further dehydrofluorination to give 5-difluoromethyl- or 5-unsubstituted 1-phenylpyrazole.     

Criterion for Invertibility of Endomorphisms and Test Rank of Metabelian Products of Abelian Groups

Let G be a finitely generated torsion-free group, which is a metabelian product of Abelian groups. We establish a criterion for endomorphisms satisfying some extra restriction to be invertible in G. Test sets for IA-endomorphisms of G are described and its test rank computed.     

An investigation of terpene hydrocarbons of the carane series by photoelectron spectroscopy

2- and 3-Carenes and carane have been studied by PE spectroscopy. On the basis of an analysis of orbital interactions and information obtained from the PE spectra of model compounds an assignment has been made of the bands corresponding to ionization from the molecular orbitals of the double bond and of the cyclopropane ring.     

Dispersion of optical anisotropy in nanostructurized silicon films

Optical characteristics of (110) oriented porous silicon films obtained by electrochemical etching are studied. Dispersion of refractive indices, dichoroism in the visible range of the spectrum, depolarization factor, and porosity of silicon films are measured. It is shown that the results obtained may be described based on the generalized Bruggeman model. Possible causes of the established discrepancies between the experimental data and the model are discussed.     

Comparison of the energy histograms and conformations between different lattice models of copolymers

Based on large-scale Monte Carlo simulations the energy probability distribution functions are investigated for a large set of primary sequences in distinct lattice models of copolymers at low temperatures below transitions to compacted states. Amphiphilic copolymers with hydrophobic and hydrophilic units are found to produce single or double peak energy distributions corresponding to mono- or multi-meric micellar conformations. However, copolymers with short-ranged random ‘charge’ interactions in some cases are found to produce energy distribution functions with a well pronounced lowest energy state and a gap separating it from the rest of the spectrum. These, however have rather peculiar conformations corresponding to effectively immiscible domains comprised from monomers of likewise species. The relevance of these observations for coarse-grained models for protein folding is discussed.     

Surface self-diffusion of organic molecules adsorbed in porous silicon

The pulsed field gradient nuclear magnetic resonance method has been employed to probe self-diffusion of organic guest molecules adsorbed in porous silicon with a 3.6 nm pore size. The molecular self-diffusion coefficient and intrapore adsorption were simultaneously measured as a function of the external vapor pressure. The latter was varied in a broad range to provide pore loading from less than monolayer surface coverage to full pore saturation. The measured diffusivities are found to be well-correlated with the adsorption isotherms. At low molecular concentrations in the pores, corresponding to surface coverages of less than one monolayer, the self-diffusion coefficient strongly increases with increasing concentration. This observation is attributed to the occurrence of activated diffusion on a heterogeneous surface. Additional experiments in a broad temperature range and using binary mixtures confirm this hypothesis.     

Studies of supported catalysts for ethylene polymerization, prepared using organovanadium compounds

Catalysts containing trimethylsilyl complexes of V(IV) and (III) supported on SiO₂ and Al₂O₃, have been synthesized and examined for ethylene polymerization. The state of vanadium in solution and on the support and catalysts interaction with C₂H₄, CO, H₂ and pyridine have been studied using ESR and IR spectroscopy.

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, (IV) (III), SiO₂ Al₂O₃. , C₂H₄, CO, H₂ .

     

Effects of light localization in photoluminescence and Raman scattering in silicon nanostructures

The effect of light localization in photoluminescence (PL) and Raman scattering (RS) in silicon nanowires with diameter of 100 nm was investigated. The optical excitation was done by CW radiation of a YAG:Nd laser at 1.064 μm. The PL an RS intensities were found to increase strongly for the samples with Si nanowires in comparison with corresponding values of c-Si substrate. The effect is explained by an increase of the lifetime of photons in silicon nanowire structures.