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991.
This research reports the development of a biotrickling filter (BTF) to upgrade biogas, which is achieved by adding H2 to reduce CO2. H2 and CO2 (80:20% vol.) were fed to a bench-scale BTF packed with polyurethane foam (PUF) and inoculated with hydrogenotrophic methanogens. Maximum CH4 production rates recorded were as high as 38 m3 CH4 m?3 reactor day?1, which is 5–30 times faster than earlier reports with other kinds of bioreactors. The high rates were attributed to the efficient mass transfer and high density of methanogens in the BTF. The removal efficiencies for H2 and CO2 were 83 and 96%, respectively. 5-Cyano-2,3-ditolyl tetrazolium chloride/DAPI staining revealed that 67% of cells were alive near the gas entrance port, while only 8.3% were alive at the exit. Furthermore, DNA sequencing showed that only 27% of the biomass was composed of Euryarchaeota, the phylum which includes methanogens. These two observations suggest that optimizing the methanogen density and activity could possibly reach even higher biogas upgrading rates.  相似文献   
992.
Ni@CeO2 core–shell catalysts were synthesized via a facile surfactant-assisted hydrothermal method and their catalytic performance in the dry reforming of methane (DRM) reaction was evaluated. A variety of techniques including XRD, N2 adsorption–desorption, SEM, TEM, TPO, TGA were employed to characterize the prepared or spent catalysts. The encapsulation by the CeO2 shell, on one side, can restrict the sintering and growth of Ni nanoparticles under harsh reaction conditions. On the other side, compared to the conventional shell material of SiO2, CeO2 can provide more lattice oxygens and vacancies, which is helpful to suppress coke deposition. Consequently, the Ni@CeO2 core–shell catalysts exhibited better catalytic activity and stability in the DRM reaction with respect to the referenced Ni@SiO2 core–shell catalysts and Ni/CeO2 supported catalysts.  相似文献   
993.
A series of composites containing hexagonal tungsten trioxide (h-WO3) and reduced graphene oxide (rGO) sheets are synthesized via a modified one-step hydrothermal route without assisted additive. The composites are characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and UV-vis absorption spectroscopy. The new procedure made it possible to increase the reduction degree of GO. Based on the evidence presented hexagonal WO3 grows on the surface of graphene through chemical interactions with the surface. The visible-light photocatalytic degradation of methylene blue shows that the h-WO3/rGO composites exhibit superior photocatalytic performance of 96% with a maximum degradation rate achieved under visible-light irradiation for 6 h. The speculations concerning the mechanism of photocatalytic reactions are discussed. The improved photocatalytic activity can be accounted for by the increased adsorption toward chemical species, the enhanced light absorption and an efficient separation of photogenerated electron-hole pairs and transfer of charge carriers.  相似文献   
994.
In this work, the solubilities of the salt minerals and the densities of solution in two ternary systems sodium chloride–zinc chloride–water and magnesium chloride–zinc chloride–water were measured at 373 K using an isothermal solution saturation method. Based on the determined equilibrium solubility data and the corresponding equilibrium solid phase, the phase diagrams and density diagrams of the two systems were plotted. The results show that the two ternary systems are complex and the eutectic points, the univariant solubility curves and the solid crystalline phase regions are shown and discussed. The phase diagram of the ternary system NaCl?ZnCl2?H2O at 373 K is constituted of two eutectic points, three univariant solubility curves and three solid crystalline phase regions corresponding to NaCl, ZnCl2 and 2NaCl · ZnCl2. And the phase diagram of the ternary system MgCl2?ZnCl2?H2O at 373 K includes two eutectic points, three univariant solubility curves and three solid crystalline phase regions corresponding to MgCl2 · 6H2O, MgCl2 · ZnCl2 · 5H2O and ZnCl2. The experimental results were simply discussed.  相似文献   
995.
The transfer properties and microscopic structures of methanol, ethanol, 1-propanol, 2-propanol, and 1-pentanol in the temperature range from 290 to 450 K and pressure range from 0.1 to 200 MPa were studied by molecular dynamics (MD) simulation through the calculation of the self-diffusion coefficients, velocity autocorrelation functions (VACF), and radial distribution function (RDF). The calculated self-diffusion coefficients conform to the experimental values on the whole, and the temperature has greater influence, which weaken with the increase of the carbon chain, on self-diffusion coefficient than pressure. The factors affecting self-diffusion coefficients were also analyzed from micro perspective by calculation of VACF and RDF, which is helpful to understand the relationship between microscopic structures of fluid and its transfer properties. This work not only provides a reliable simulation method for transfer properties of alkanols, but also provides the prediction data for design and development of chemical processes.  相似文献   
996.
Molecular imprinting is an approach to synthesize receptors with specific molecular recognition properties. A computational method was carried out to study interaction between template and monomer in prepolymerization mixture. The functional monomer and template complexes were optimized, at the minimum energy confirmation using Austin Model 1 semi empirical method within Restricted Hartree Fock formalism. The theoretical results showed that allylthiourea (functional monomer) has the largest interaction energy towards template (sodium nitrate) with the mole ratio of 4 : 1; functional monomer : template. The resulting polymers were characterized using Fourier Transform infrared spectroscopy, thermogravimetry analysis and field emission scanning electron microscopy. Rebinding experiments were carried out to evaluate binding capacity of the polymer. The adsorption data of ion imprinted polymer (IIP) were fitted with Langmuir-Freundlich isotherm model. Pseudo-second order kinetic model was used to describe the kinetic adsorption behavior of IIP. The experimental binding result showed good agreement with theoretical computation and the IIP was further used for nitrate ion detection. The results of membrane optimization indicated that the sensor, which composed of 30% polyvinylchloride, 60% nitrophenyl octyl ether as a plasticizer, 2% sodium tetraphenyl borate, and 10% IIP as ionophore exhibited an almost Nernstian slope with the limit of detection 3.9 × 10-6 M. The fabricated sensor had shown good potential in nitrate detection with wide linear range, low limit of detection and found to have good selectivity towards nitrate ion over other anion.  相似文献   
997.
刘志勇 《高分子科学》2017,35(8):924-938
Well-defined p H-responsive poly(ε-caprolactone)-graft-β-cyclodextrin-graft-poly(2-(dimethylamino)ethylmethacrylate)-co-poly(ethylene glycol) methacrylate amphiphilic copolymers(PCL-g-β-CD-g-P(DMAEMA-co-PEGMA)) were synthesized using a combination of atom transfer radical polymerization(ATRP),ring opening polymerization(ROP) and "click" chemistry.Successful synthesis of polymers was confirmed by Fourier transform infrared spectroscopy(FTIR),proton nuclear magnetic resonance(1H-NMR),and gel permeation chromatography(GPC).Then,the polymers could selfassemble into micelles in aqueous solution,which was demonstrated by dynamic light scattering(DLS) and transmission electron microscopy(TEM).The p H-responsive self-assembly behavior of these copolymers in water was investigated at different p H values of 7.4 and 5.0 for controlled doxorubicin(DOX) release,and these results revealed that the release rate of DOX could be effectively controlled by altering the p H,and the release of drug loading efficiency(DLE) was up to 88%(W/W).CCK-8 assays showed that the copolymers had low toxicity and possessed good biodegradability and biocompatibility,whereas the DOX-loaded micelles remained with high cytotoxicity for He La cells.Moreover,confocal laser scanning microscopy(CLSM) images revealed that polymeric micelles could actively target the tumor site and the efficient intracellular DOX release from polymeric micelles toward the tumor cells further confirmed the anti-tumor effect.The DOX-loaded micelles could easily enter the cells and produce the desired pharmacological action and minimize the side effect of free DOX.These results successfully indicated that p H-responsive polymeric micelles could be potential hydrophobic drug delivery carriers for cancer targeting therapy with sustained release.  相似文献   
998.
    
Realizing the full potential of oxide‐supported single‐atom metal catalysts (SACs) is key to successfully bridge the gap between the fields of homogeneous and heterogeneous catalysis. Here we show that the one‐pot combination of Ru1/CeO2 and Rh1/CeO2 SACs enables a highly selective olefin isomerization‐hydrosilylation tandem process, hitherto restricted to molecular catalysts in solution. Individually, monoatomic Ru and Rh sites show a remarkable reaction specificity for olefin double‐bond migration and anti‐Markovnikov α‐olefin hydrosilylation, respectively. First‐principles DFT calculations ascribe such selectivity to differences in the binding strength of the olefin substrate to the monoatomic metal centers. The single‐pot cooperation of the two SACs allows the production of terminal organosilane compounds with high regio‐selectivity (>95 %) even from industrially‐relevant complex mixtures of terminal and internal olefins, alongside a straightforward catalyst recycling and reuse. These results demonstrate the significance of oxide‐supported single‐atom metal catalysts in tandem catalytic reactions, which are central for the intensification of chemical processes.  相似文献   
999.
1000.
This study describes an accurate, sensitive, and specific chromatographic method for the simultaneous quantitative determination of lamivudine and zidovudine in human blood plasma, using stavudine as an internal standard. The chromatographic separation was performed using a C8 column (150 × 4.6 mm, 5 μm), and ultraviolet absorbency detection at 270 nm with gradient elution. Two mobile phases were used. Phase A contained 10 mM potassium phosphate and 3% acetonitrile, whereas Phase B contained methanol. A linear gradient was used with a variability of A-B phase proportion from 98–2% to 72–28%, respectively. The drug extraction was performed with two 4 mL aliquots of ethyl acetate.  相似文献   
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