Site-specific modification of the 5"-terminal fragment of PGY1/MDR1 gene mRNA by reactive conjugates of antisense oligonucleotides

The site-specific modification of the 5"-terminal fragment of PGY1/MDR1 mRNA by oligodeoxyribonucleotide conjugates bearing residues of bleomycin A₅ (Blm), cobalt(ii) tetracarboxyphthalocyanine (Phcn), 4-[N-(2-chloroethyl)-N-methylamino]benzylamine (RCl), or perfluoroarylazide (Az) was studied. Conjugates of oligonucleotides complementary to the RNA sequences 123—138 and 155—166 selectively modify RNA in the vicinity of these regions. The highest efficacy (up to 50%) was achieved in reactions with alkylating and perfluoroarylazide conjugates of oligonucleotides. Conjugates of perfluoroarylazide with 2"-O-modified oligonucleotides are much more efficient than analogous conjugates with oligodeoxyribonucleotides (extents of RNA modification are 40—50% and 20%, respectively).     

Nonstationary Phenomena in the Low-Temperature Gas-Phase Catalytic Oxidation of H2S with Oxygen

The conditions of the existence were determined and reasons were revealed for the appearance of periodic oscillations of the SO₂concentration in the reaction products and warming temperature in the catalyst bed in the oxidation of H₂S with oxygen at temperatures below the dew point of sulfur on the V–Al–Ti oxide catalyst. The formation of polysulfides during the reaction was experimentally found. It was proposed that the adsorption of sulfur and polysulfides on the catalyst surface is responsible for the observed oscillatory processes.     

Investigation of H2S oxidation by oxygen on oxide catalysts in sulfur condensation conditions

H₂S oxidation with oxygen has been studied on three industrial oxide catalysts (Fe−Cr−Zn, Cu−Cr−Al, V−Ti−Al). Thermodynamically possible changes in the composition of the catalysts have been evaluated. Regularities determining deep or partial oxidation of H₂S have been found. Deep oxidation is connected to the presence of active oxygen on the catalyst surface; its removal results in a decrease of activity and increase of the sulfur selectivity. Oscillations caused by periodic adsorption-desorption of sulfur on the catalyst surface have been observed on the most active V−Ti−Al catalysts in oxygen excess.     

Nickel catalysts for the hydrodeoxygenation of biodiesel

A number of nickel and nickel-copper catalysts for the hydrodeoxygenation of fatty acid esters (biodiesel) were studied. The CeO₂ and ZrO₂ oxides and the CeO₂-ZrO₂ binary system were used as supports. The Ni-Cu/CeO₂-ZrO₂ catalyst exhibited the highest activity; it allowed us to quantitatively convert biodiesel into linear alkanes under mild conditions (290–320°C, 1.0 MPa). It was found that the selectivity of the formation of the main product (heptadecane) was 70–80%. The main correlations between the nature of catalysts and their activity under conditions of the target reaction were determined using temperature-programmed reduction, X-ray diffraction analysis, and electron microscopy. It was hypothesized that the high activity of Ni-Cu/CeO₂-ZrO₂ in the test reaction can be explained by the presence of a Ni_{1 − x} Cu _x (x = 0.2–0.3) solid solution as a constituent of the active component of the catalyst.     

XPS studies of active surface of Al?Cu?Cr catalysts for oxidation of tail gases from sulfur production

Surface variations of the Al–Cu–Cr catalytst in H₂S and CO oxidation in the process of cleaning of tail gases from sulfur production have been examined. XPS data indicate that the interaction of CuCr₂O₄ spinel with H₂S and SO₂ produces CuSO₄ on the catalyst surface and sulfate poisoning is of a reversible character.

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Al–Cu–Cr H₂S CO . CuCr₂O₄ H₂S SO₂ CuSO₄ , .

     

Chimeric oligonucleotides based on 2"-O-modified oligoribonucleotides with the terminal 3"—3" internucleotide linkage as potential inhibitors of MDR 1 gene expression

Chimeric constructs were synthesized based on oligoribonucleotides modified at the 2"-position of the ribose (2"-O-tetrahydropyranyl- or 2"-O-methyl-) and at the 3"-terminus of the oligonucleotide chain (terminal 3"—3" internucleotide linkage), which are complementary to a region of MDR 1 mRNA. A comparative study of the properties of these chimeric constructs was performed. The chimeric oligomers with the modified 3"-terminus are characterized by high stability with respect to 3"-exonucleases, form stable complementary complexes with RNA, and can activate RNase H in a duplex with RNA.