Effect of crystallinity in HZSM-5-amorphous alumosilica systems on their catalytic properties in the synthesis of dimethoxymethane

Granulated catalysts with 3–5% H-ZSM-5 phase were obtained from a highly dispersed alumosilica and were used for the synthesis of dimethoxymethane (DMM) from methanol and formaldehyde. The activity of these catalysts is greater than the activity of pure zeolite. A linear correlation was found between the yield of DMM and the content of Brönsted acid sites in the catalysts.     

Synthesis of New Amphiphilic Comb-Like Copolymers Based on Maleic Anhydride and α-Olefins

Summary: Novel amphiphilic comb-like poly(α-olefin-co-maleic anhydride) with a controlled ratio of hydrophilic (polyoxyethylene) and hydrophobic (polymethylene) side chains have been synthesized and characterized. The comb-like copolymers are soluble in organic and aqueous media and form micelles whose behaviour could be correlated to the chemical structure of polymers. We foresee that amphiphilic properties of the novel comb-like polymers are obviously the basis of new architectures in solution which could be used in a broad range of applications. Using micelles from these copolymers, silver nanoparticles with a narrow particle size distribution have been obtained as stable dispersion in both polar and non-polar media.     

Hydrogen adsorption on silicalite in the presence of water and benzene

¹H NMR techniques in the temperature range 200–280 K under isobaric conditions are used to investigate concurrent adsorption of hydrogen and water in the pores of silicalite, a microporous silica. The possibility for a small (up to a few weight percent) quantity of water to exist in the pores is demonstrated. Water is found to exist in the form of two types of cluster structures differing in the degree of water association. A conclusion about the stabilization of the weakly associated form by weakly polar organic molecules is made. Water is shown to promote the hydrogen adsorption process; when its concentration is c _H2O = 2 wt %, adsorption increases more than twofold. A suggestion that this effect is caused by the formation of water-hydrogen cluster structures in the pores is made.     

Increasing efficiency of laser fluorescence diagnostics of microbial diseases

The laser-induced fluorescence spectra of five types of mycobacteria are studied in various associations. The results obtained are used to demonstrate the possibility of a diagnostic system for the differential diagnostics of microbial diseases. The method employed for the specific analysis of microbial species in the substrate that contain various associations is based on a regression of the spectral characteristics of the fluorescence intensity to the principal components. The diagnostic efficiency is increased when the fluorescence spectra are reconstructed with regard to the optical characteristics of the medium. The detergent effect on the parameters of microbial fluorescence diagnostics is studied.     

Asymmetric oxidation of 4-nitro-6-trifluoromethyl-1,2,3-benzotrithiole

Both enantiomers of 4-nitro-6-trifluoromethyl-1,2,3-benzotrithiole 1-oxide as analogs of Varacins B and C were synthesized for the first time. The use of the Modena method ensures higher optical purity but lower yields of the chiral sulfoxides, as compared to the Kagan procedure.