Zinfer R. Ismagilov

Palladium Nanoparticles Supported on Nitrogen‐Doped Carbon Nanofibers: Synthesis, Microstructure, Catalytic Properties, and Self‐Sustained Oscillation Phenomena in Carbon Monoxide Oxidation

The oxidation of CO over Pd nanoparticles supported on carbon nanofibers (CNFs) and N‐doped carbon nanofibers (N‐CNFs) has been studied. Investigation by scanning transmission electron microscopy together with electron energy‐loss spectroscopy revealed that Pd nanoparticles are located on the N‐CNFs surface patches that have a high concentration of N atoms. The N‐doping of CNFs was shown to change the electric conductivity of N‐CNFs and redox properties of Pd, which thus determines the self‐oscillatory behavior of the catalysts during CO oxidation, the type of oscillations, and the conditions of their generation. Mechanisms that underlie the effect of N in N‐CNFs on the electronic state of Pd as well as the occurrence of two types of oscillation mechanisms—the known redox mechanism and the mechanism related to Pd intercalation into graphene layers—are discussed.

High-performance method for specific effect on nucleic acids in cells using TiO2~DNA nanocomposites

Nanoparticles are used to solve the current drug delivery problem. We present a high-performance method for efficient and selective action on nucleic acid target in cells using unique TiO2·PL-DNA nanocomposites (polylysine-containing DNA fragments noncovalently immobilized onto TiO2 nanoparticles capable of transferring DNA). These nanocomposites were used for inhibition of human influenza A (H3N2) virus replication in infected MDCK cells. They showed a low toxicity (TC50 ≈ 1800 μg/ml) and a high antiviral activity (>99.9% inhibition of the virus replication). The specificity factor (antisense effect) appeared to depend on the delivery system of DNA fragments. This factor for nanocomposites is ten-times higher than for DNA in the presence of lipofectamine. IC50 for nanocomposites was estimated to be 1.5 μg/ml (30 nM for DNA), so its selectivity index was calculated as ~1200. Thus, the proposed nanocomposites are prospective for therapeutic application.

Tellurium NaX zeolites: I. Deuterium tracer studies of cyclohexane dehydrogenation to benzene

Abstract Deuterium tracers were used to explore the mechanisms of dehydrogenation of six-membered cyclic compounds to benzene over a Te NaX zeolite catalyst. Dehydrogenation of cyclohexane to cyclohexene (and probably to cyclohexadiene) precedes the formation of benzene. A large primary kinetic isotope effect ( k c 6 h 12 k c 6 D 12 ~ 2.5 at 400 ° C ) indicates that cleavage of the CH bonds in cyclohexane is the rate-determining reaction step. Although the presence of gaseous hydrogen is required to maintain catalyst activity, the dehydrogenation rates are the same in H 2 as they are in D 2 . Only a limited amount of exchange occurs between D 2 and H atoms in the hydrocarbons. The exchange which is observed probably arises from double bond shift that occurs in the olefins by an addition/abstraction mechanism on a single Te atom containing one adsorbed D atom. Cyclohexane can be formed from cyclohexene by hydrogen transfer from another cyclohexene molecule much more readily than it can be formed by direct saturation with gaseous H 2 . Both the dehydrogenation and isomerization sites are probably Te 0 surface atoms.

Tellurium NaX zeolites: II. Nature of active sites

An unusual dehydrocyclization catalyst can be prepared from an intimate mixture of NaX zeolite and tellurium metal. Careful X-ray diffraction studies by researchers at Mobil Research and Development Company indicated that the active site was a Te2− species nestled in the supercage of the zeolite and coordinated to sodium ions in the zeolite. Our ESCA spectra, however, point toward elemental Te0 as the active sites, and sodium NMR data confirm that the Te is coordinated to sodium ions in the host oxide. These sites are capable of accommodating up to 2H/Te in an activated adsorption process. A dehydrogenation mechanism consistent with the observed kinetics involves the simultaneous removal of two hydrogen atoms by these Te0 sites in a rate limiting step.

TiO 2 ~Deoxyribozyme Nanocomposites as Delivery System and Efficient Site-Specific Agents for Cleavage of RNA Targets

Synthetic DNA molecules of 10-23 deoxyribozymes (Dz) are known to be efficient and site-specific agents for the RNA cleavage in a catalytic manner. To provide the penetration of Dz into cells, we have proposed the new delivery system for deoxyribozymes in the form of TiO 2 •PL-Dz nanocomposite. These nanocomposites consist of catalytically ac- tive Dz molecules noncovalently immobilized through the polylysine linker to TiO 2 nanoparticles, which provide the penetration of Dz into cells. Deoxyribozymes in the prepared TiO 2 •PL-Dz nanocomposites were shown to retain their ability to cleave RNA targets albeit at a slower rate but with the same site-specificity and similar efficiency as free Dz. Unlike free Dz, the proposed TiO 2 •PL-Dz nanocomposites penetrate into cells without auxiliary actions.

Apoptosis-mediated endothelial toxicity but not direct calcification or functional changes in anti-calcification proteins defines pathogenic effects of calcium phosphate bions.

Calcium phosphate bions (CPB) are biomimetic mineralo-organic nanoparticles which represent a physiological mechanism regulating the function, transport and disposal of calcium and phosphorus in the human body. We hypothesised that CPB may be pathogenic entities and even a cause of cardiovascular calcification. Here we revealed that CPB isolated from calcified atherosclerotic plaques and artificially synthesised CPB are morphologically and chemically indistinguishable entities. Their formation is accelerated along with the increase in calcium salts-phosphates/serum concentration ratio. Experiments in vitro and in vivo showed that pathogenic effects of CPB are defined by apoptosis-mediated endothelial toxicity but not by direct tissue calcification or functional changes in anti-calcification proteins. Since the factors underlying the formation of CPB and their pathogenic mechanism closely resemble those responsible for atherosclerosis development, further research in this direction may help us to uncover triggers of this disease.

Development of Granular Catalysts and Natural Gas Combustion Technology for Small Gas Turbine Power Plants

Gas turbine power plants (GTPPs) of low power (tens of kW to 1.5-2 MW) are promising autonomous sources of energy and heat. The application of gas turbine technologies saves fuel, solves heat supply and water shortage problems. The nominal efficiency of GTTPs belonging to different generations varies from 24% to 38% (average weighted efficiency – 29%). This is 1.5 times higher than that of combined heat power plants. The main GTPP drawback is significant emission of toxic nitrogen oxides due to high temperature combustion of the gas fuel. The main approach used today to decrease the emission of nitrogen oxides from GTPPs is based on the use of the so-called homogeneous combustion chambers working with premixed lean fuel-air mixtures with two-fold excess of air. The decrease of NOx formation is principally the result of the low flame temperatures that are encountered under lean conditions (Correa 1992). This technology makes it possible to decrease significantly the temperature in the combustion zone relative to traditional GTPP combustion chambers with separate supply of fuel and air to the combustion zone. As a result, the concentration of nitrogen oxides in the flue gases decreases from 100 ppm to 1020 ppm. The downside of this approach is, however, that it results in low heat release rates, which, in turn, may negatively affect combustion stability. The most efficient way to decrease emissions of nitrogen oxides in GTPPs is to use catalytic combustion of fuel (Trimm, 1983; Pfefferle & Pfeferle., 1987; Ismagilov & Kerzhentsev 1990; Parmon et al., 1992; Ismagilov et al., 1995; Ismagilov & Kerzhentsev, 1999; Ismagilov et al., 2010). In the catalytic chamber, efficient combustion of homogeneous fuel-air mixture is achieved at larger excess of air and much lower temperatures in the zone of chemical reactions compared to modern homogeneous combustion chambers. In the last decade, the obvious advantages of the catalytic combustion chambers in GTPPs initiated intense scientific and applied studies in the USA (Catalytica) and Japan (Kawasaki Heavy Industries) which are aimed at development of such chambers for GTPPs for various applications (Dalla Betta et al., 1995; Dalla Betta & Tsurumi, 1995; Dalla Betta & RostrupNielsen, 1999; Dalla Betta & Velasco, 2002).

Preparation and study of thermally and mechanically stable ceramic fiber based catalysts for gas combustion.

The effective stable fiber based catalyst with a good permeability is prepared and studied. It is shown that proposed preparation method of catalyst with low concentration of active components provides stable activity and durability in hydrocarbon combustion.

Stabilization of copper nanoparticles in Cu-ZSM-5

Abstract The copper nanoparticles formed during reduction of Cu-ZSM-5 in hydrogen at temperature 150 – 400°C were studied by UV-Vis spectroscopy and HRTEM. The plasmon resonance (PR) absorption at 16000–17500 cm −1 was used for copper nanoparticles identification. It was shown that the chain-like and square-plain copper-oxide clusters stabilized in Cu-ZSM-5 during its preparation are the precursors of copper nanoparticles 2–10 nm.

χ-氧化铝的添加对纯的和修饰的γ-氧化铝上H 2 S氧化反应性能的影响

Abstract The influence of the textural and acidic properties of γ-Al2O3, (γ+χ)-Al2O3, and α-Al2O3 on the catalytic activity, selectivity, and stability of direct H2S oxidation has been studied. A comparison of the H2S-to-S conversion effectiveness of aluminas with their acidic properties (identified by Fourier transform infrared spectroscopy and temperature programmed desorption of NH3) shows that H2S adsorption occurs predominantly on weak Lewis acid sites (LAS). γ-Alumina samples containing a χ-phase and/or modified Mg2+ ions have a greater concentration of weak LAS and exhibit greater catalytic activity. When alumina is treated with a sulfuric acid solution, strong LAS appear and the number of LAS decreases significantly. Modification of alumina with hydrochloric acid has a limited effect on LAS strength. Weak LAS are retained and double in number compared to that present in the unmodified alumina, but the treated sample has Al−Cl bonds. Alumina samples modified by sulfate and chloride anions exhibit poor catalytic activity in H2S oxidation.