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81.
Anatoly S. Lermontov Jean-Sébastien Girardon Anne Griboval-Constant Stanislas Pietrzyk Andrei Y. Khodakov 《Catalysis Letters》2005,101(1-2):117-126
Chemisorption of propene and propane was studied in a pulse reactor over a series of cobalt silica-supported Fischer–Tropsch catalysts. It was shown that interaction of propene with cobalt metal particles resulted in its rapid autohydrogenation. The reaction consists in a part of the propene being dehydrogenated to surface carbon and CHx chemisorbed species; hydrogen atoms released in the course of propene dehydrogenation are then involved in hydrogenation of remaining propene molecules to propane at 323–423 K or in propene hydrogenolysis to methane and ethane at temperatures higher than 423 K. The catalyst characterization suggests that propene chemisorption over cobalt catalysts is primarily a function of the density of cobalt surface metal sites. A correlation between propene chemisorption and Fischer–Tropsch reaction rate was observed over a series of cobalt silica-supported catalysts. No propane chemisorption was observed at 323–373 K over cobalt silica-supported catalysts. Propane autohydrogenolysis was found to proceed at higher temperatures, with methane being the major product of this reaction over cobalt catalysts. Hydrogen for propane autohydrogenolysis is probably provided by adsorbed CHx species formed via propane dehydrogenation. Propene and propane chemisorption is dramatically reduced upon the catalyst exposure to synthesis gas (H2/CO = 2) at 323–473 K. Our results suggest that cobalt metal particles are probably completely covered by carbon monoxide molecules under the conditions similar to Fischer–Tropsch synthesis and thus, most of cobalt surface sites are not available for propene and propane chemisorption. 相似文献
82.
Khorcheska Batyrova Anastasia Gavrisheva Elena Ivanova Jianguo Liu Anatoly Tsygankov 《International journal of molecular sciences》2015,16(2):2705-2716
Previously it has been shown that green microalga Chlamydomonas reinhardtii is capable of prolonged H2 photoproduction when deprived of sulfur. In addition to sulfur deprivation (-S), sustained H2 photoproduction in C. reinhardtii cultures can be achieved under phosphorus-deprived (-P) conditions. Similar to sulfur deprivation, phosphorus deprivation limits O2 evolving activity in algal cells and causes other metabolic changes that are favorable for H2 photoproduction. Although significant advances in H2 photoproduction have recently been realized in fresh water microalgae, relatively few studies have focused on H2 production in marine green microalgae. In the present study phosphorus deprivation was applied for hydrogen production in marine green microalgae Chlorella sp., where sulfur deprivation is impossible due to a high concentration of sulfates in the sea water. Since resources of fresh water on earth are limited, the possibility of hydrogen production in seawater is more attractive. In order to achieve H2 photoproduction in P-deprived marine green microalgae Chlorella sp., the dilution approach was applied. Cultures diluted to about 0.5–1.8 mg Chl·L−1 in the beginning of P-deprivation were able to establish anaerobiosis, after the initial growth period, where cells utilize intracellular phosphorus, with subsequent transition to H2 photoproduction stage. It appears that marine microalgae during P-deprivation passed the same stages of adaptation as fresh water microalgae. The presence of inorganic carbon was essential for starch accumulation and subsequent hydrogen production by microalgae. The H2 accumulation was up to 40 mL H2 gas per 1iter of the culture, which is comparable to that obtained in P-deprived C. reinhardtii culture. 相似文献
83.
Dr. M. Monsur Ali Dr. Anatoly Slepenkin Dr. Ellena Peterson Dr. Weian Zhao 《Chembiochem : a European journal of chemical biology》2019,20(7):906-910
Pathogenic bacteria pose a serious threat to public health, and the rapid and cost-effective detection of such bacteria remains a major challenge. Herein, we present a DNAzyme-based fluorescent paper sensor for Klebsiella pneumoniae. The DNAzyme was generated by an in vitro selection technique to cleave a fluorogenic DNA–RNA chimeric substrate in the presence of K. pneumoniae. The DNAzyme was printed on a paper substrate in a 96-well format to serve as mix-and-read fluorescent assay that exhibits a limit of detection (LOD) 105 CFUs mL−1. Evaluated with 20 strains of clinical bacterial isolates, the DNAzyme produced the desired fluorescence signal with the samples of K. pneumoniae, regardless of their source or drug resistance. The assay is simple to use, rapid, inexpensive, and avoids the complex procedures of sample preparation and equipment. We believe that this DNAzyme-based fluorescent assay has potential for practical applications to identify K. pneumoniae. 相似文献
84.
Rachel E. Sheldon Marc Baghdadi Conor McCloskey Andrew M. Blanks Anatoly Shmygol Hugo A. van den Berg 《Journal of the Royal Society Interface》2013,10(86)
The muscular layer of the uterus (myometrium) undergoes profound changes in global excitability prior to parturition. Here, a mathematical model of the myocyte network is developed to investigate the hypothesis that spatial heterogeneity is essential to the transition from local to global excitation which the myometrium undergoes just prior to birth. Each myometrial smooth muscle cell is represented by an element with FitzHugh–Nagumo dynamics. The cells are coupled through resistors that represent gap junctions. Spatial heterogeneity is introduced by means of stochastic variation in coupling strengths, with parameters derived from physiological data. Numerical simulations indicate that even modest increases in the heterogeneity of the system can amplify the ability of locally applied stimuli to elicit global excitation. Moreover, in networks driven by a pacemaker cell, global oscillations of excitation are impeded in fully connected and strongly coupled networks. The ability of a locally stimulated cell or pacemaker cell to excite the network is shown to be strongly dependent on the local spatial correlation structure of the couplings. In summary, spatial heterogeneity is a key factor in enhancing and modulating global excitability. 相似文献
85.
Elena Arnautova Eugene Sviridov Eugene Rogach Esther Savchenko Anatoly Grekov 《组合铁电体》2013,141(1):147-150
The polarization switching processes of ferroelectric polycrystalline Sn2P2S6 films on Al substrates were studied. The effect of full reverse spontaneous switching after the influence of a repolarizing pulse on the prepoled sample was investigated. This opens the way for making the ferroelectric memory devices with rapid nondestructive readout. 相似文献
86.
87.
Nikita V. Muravyev Anatoly A. Bragin Konstantin A. Monogarov Anna S. Nikiforova Alexander A. Korlyukov Igor V. Fomenkov Nikolay I. Shishov Alla N. Pivkina 《Propellants, Explosives, Pyrotechnics》2016,41(6):999-1005
The nitrogen‐rich energetic compound 5‐amino‐3,4‐dinitropyrazole (5‐ADP) was investigated using complementary experimental techniques. X‐ray diffraction indicates the strong intermolecular hydrogen bonding in 5‐ADP crystals. Compound exhibits low impact sensitivity (23 J) and insensitivity to friction. The activation energy of thermolysis determined to be 230±5 kJ mol−1 from DSC measurements. Accelerating rate calorimetry indicates the lower thermal stability (173 °C) of 5‐ADP than that of RDX, which is probably the main concern about using this compound. 5‐ADP also exhibits good compatibility with common energetic materials (viz. TNT, RDX, ammonium perchlorate), including an active binder. The burning rate of 5‐ADP monopropellant is higher than that of benchmark HMX, while the pressure exponent 0.51±0.04 is surprisingly low. Addition of ammonium perchlorate does not affect the pressure exponent of 5‐ADP, while the burning rate increases. The 5‐amino‐3,4‐dinitropyrazole exhibits a notable combination of combustion performance, low sensitivity, and good compatibility, which renders it as a promising energetic material. 相似文献
88.
Smolovich AM 《Applied optics》2006,45(30):7871-7877
The principles of wavefront reconstruction by means of a geometric-optical reflection of radiation from surfaces of interference fringe maxima are discussed. The optical elements based on these principles should be achromatic. Two methods of the optical elements design are proposed. The first method is a direct holographic recording of the interference fringe structure containing only a few periods, and the second method is a combination of the measurement of the object wavefront shape with digital holography methods. 相似文献
89.
Method of Monte Carlo simulation verification in hadron therapy with non-tissue equivalent detectors
In hadron therapy the spectra of secondary particles can be very broad in type and energy. The most accurate calculations of tissue equivalent (TE) absorbed dose and biological effect can be achieved using Monte Carlo (MC) simulations followed by the application of an appropriate radiobiological model. The verification of MC simulations is therefore an important quality assurance (QA) issue in dose planning. We propose a method of verification for MC dose calculations based on measurements of either the integral absorbed dose or the spectra of deposited energies from single secondary particles in non-TE material detectors embedded in a target of interest (phantom). This method was tested in boron neutron capture therapy and fast neutron therapy beams. 相似文献
90.
Khorcheska A. Batyrova Anatoly A. TsygankovSergey N. Kosourov 《International Journal of Hydrogen Energy》2012
This study demonstrates that, besides sulfur deprivation, sustained H2 photoproduction in Chlamydomonas reinhardtii cultures can be generated by incubating algae under phosphorus-deprived (−P) conditions. However, phosphorus deficiency in algal cells could not be obtained by resuspension of algae in −P medium, evidently due to a significant reserve of phosphorus in cells. In this study, phosphorus deficiency was accomplished by inoculating the washed algae into the −P medium at low initial cell densities (below 2 mg Chl l−1). After the initial growth period, where cells utilize intracellular phosphorus, algae established anaerobic environment followed by the period of H2 photoproduction. The maximum H2 output (∼70 ml l−1) was obtained in cultures with the initial Chl content ∼1 mg l−1. Cultures with Chl above 2 mg l−1 did not produce H2 gas. The physiological response of algal cultures to phosphorus deprivation demonstrated significant similarities with the response of algae to sulfur depletion. 相似文献