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981.
Linhua Liu Toshihiro Isobe Kiyoshi Okada Akira Nakajima 《Materials Research Bulletin》2011,46(2):175-184
The respective influences of calcination, drying methods, and washing conditions on the morphologies, surface properties, and photocatalytic activities of TiO2 powders prepared from acid treatments of BaTiO3 were investigated. Rutile powder was obtained using the treatment under strong acid conditions. It possesses a bundle-like shape and comprises rutile nanorods. After calcination, characteristic voids were observed in the particles. Anatase powder was obtained by adjusting pH values of a BaTiO3 suspension to 2.5-3. Drying at 110 °C engendered the formation of spheroidal anatase, although freeze-dried anatase particles assembled into a flake-like shape. The freeze-dried samples show lower crystallinity. With grafting Cu ions, rutile exhibited better photocatalytic performance for the decomposition of gaseous 2-propanol (IPA) under visible light, although it did not work effectively for anatase. 相似文献
982.
Preparation of bismuth oxyiodides and oxides and their photooxidation characteristic under visible/UV light irradiation 总被引:2,自引:0,他引:2
Bismuth oxyiodides and oxides were prepared by a solution combination with thermal treatment method. The prepared samples were characterized by X-ray diffraction, thermogravimetry, scanning electron microscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectra, and Brunauer-Emmett-Teller surface areas. The photooxidation activity of the samples was evaluated by photocatalytic decolorization of acid orange II under both visible light (λ > 420 nm) and UV light (λ = 365 nm) irradiation. Results show that a series of changes in the compounds take place during the course of calcination, described as: BiOI → Bi5O7I → α-Bi2O3. Under visible light irradiation, the photocatalytic activities follow the order: BiOI > Bi5O7I > Bi5O7I/Bi2O3 mixture > Bi2O3, which is mainly attributed to the different absorption ability to visible light due to the different band gap energy; the activities are in the order: BiOI < Bi2O3 < Bi5O7I/Bi2O3 mixture < Bi5O7I under UV light irradiation, which is mainly caused by the different oxidability. 相似文献
983.
Binary skutterudite CoSb3 nanoparticles were synthesized by solvothermal method. The nanostructuring of CoSb3 material was achieved by the inclusion of various kinds of additives. X-ray diffraction examination indicated the formation
of the cubic phase of CoSb3. Structural analysis by transmission electron microscopy analysis further confirmed the formation of crystalline CoSb3 nanoparticles with high purity. With the assistance of additives, CoSb3 nanoparticles with size as small as 10 nm were obtained. The effect of the nanostructure of CoSb3 on the UV–visible absorption and luminescence was studied. The nanosized CoSb3 skutterudite may find application in developing thermoelectric devices with better efficiency. 相似文献
984.
Kamlendra Awasthi M. StammVolker Abetz Y.K. Vijay 《International Journal of Hydrogen Energy》2011,36(15):9374-9381
In the present case, Polyethylene terephthalate (PET) membranes of thickness 25 μm were irradiated by 100 MeV Cl9+ ion beam with ion fluence of 107 ions/cm2. These membranes were etched in 6N NaOH at 60 °C at different etching times to generate pores. The permeabilities of nitrogen, oxygen, methane, carbon dioxide as well as hydrogen were measured for etched membranes at various etching times. The permeability of gases was found to increase with etching time and a rapid increase was noticed after a critical etching time when the etched tracks meet at their vertexes. The selectivity of hydrogen gas over other gases was also observed. 相似文献
985.
Using a shock tube facility, measurements on ignition delay times of propane/hydrogen mixtures (hydrogen fraction XH2 is from 0% to 100%) were conducted at equivalence ratios of 0.5, 1.0 and 2.0. Results show that when XH2 is less than 70%, ignition delay time shows a strong Arrhenius temperature dependence, and the ignition delay time increases with the increase of equivalence ratio. When XH2 is larger than 95%, the ignition delay times do not retain an Arrhenius-like temperature dependence, and the effect of equivalence ratio is very weak when the hydrogen fraction is further increased. Numerical studies were made using two selected kinetic mechanisms and the results show that the predicted ignition delay times give a reasonable agreement with the measurements under all test conditions. Both measurements and predictions show that for mixtures with XH2 less than 70%, the ignition delay time is only moderately decreased with the increase of XH2, indicating that hydrogen addition has a weak effect on the ignition enhancement. Sensitivity analysis reveals the key reactions that control the simulation of ignition delay time. Further investigation of the H-atom consumption is made to interpret the ignition delay time dependence on equivalence ratio and XH2. 相似文献
986.
Tine Missiaen Martin Söderström Paula Vanninen 《The Science of the total environment》2010,408(17):3536-914
This paper discusses the results of geophysical and chemical investigations carried out in a chemical munition dumpsite in the southern Baltic Sea, east of the island of Bornholm. After WW2 over 32,000 tons of chemical war material was dumped here including shells and bombs as well as small drums and containers. The geophysical investigations combined very-high-resolution seismics and gradiometric measurements. The results indicate the presence of a large number of objects buried just below the seafloor. The size of the objects and their distribution, with a marked increase in density towards the center of the dumpsite, suggests that we are dealing with dumped war material. Sediment and near-bottom water samples, taken within the dumpsite and in the surrounding area, were analysed for the presence of various chemical warfare agents (CWA) including Adamsite, Clark, sulphur mustard, tabun, chlorobenzene and arsine oil. The results indicate a widespread contamination that reaches far beyond the dumpsite boundary. CWA degradation products were found in most of the sediment samples. The contamination was mostly related to arsenic containing compounds; only one sample indicated the presence of sulfur mustard. Although the correlation between detected objects and CWA concentrations is not always straightforward, the overall results suggest that a lot of the dumped war material is leaking and that over the years the contamination has reached the seafloor sediments. 相似文献
987.
M.K. Suresh H. Sreemoolanadhan Annamma John P.R.S. Wariar 《Materials Research Bulletin》2010,45(7):761-3095
Nanocrystalline magnesium titanate was synthesized through an auto-ignited combustion method. The phase purity of the powder was examined using X-ray diffraction, thermo gravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy and Raman spectroscopy. The transmission electron microscopy study showed that the particle size of the as-prepared powder was in between 20 and 40 nm. The nanopowder could be sintered to 98% of the theoretical density at 1200 °C for 3 h. The microstructure of the sintered surface was examined using scanning electron microscopy. The dielectric constant (?r) of 16.7 and loss factor (tan δ) of the order of 10−4 were obtained at 5 MHz when measured using LCR meter. The quality factor (Qu × f) 73,700 and temperature coefficient of resonant frequency (τf) −44.3 ppm/°C, at 6.5 GHz are the best reported values for sintered pellets obtained from phase pure nanocrystalline MgTiO3 powder. 相似文献
988.
Nanopowders of Ni and ZrO2 (11 nm and 90 nm, respectively) were synthesized from NiO and Zr by high energy ball milling. A highly dense nanostructured 2Ni-ZrO2 composite was consolidated at low temperature by high-frequency induction heat sintering within 2 min of the mechanical synthesis of the powders (Ni-ZrO2) with horizontal milled NiO + Zr powders under 500 MPa pressure. This process allows very quick densification to near theoretical density and prohibits grain growth in nano-structured materials. The grain sizes of Ni and ZrO2 in the composite were calculated. Finally, the average hardness and fracture toughness values of nanostructured 2Ni-ZrO2 composites were investigated. 相似文献
989.
Chemical stimulation techniques for geothermal wells: experiments on the three-well EGS system at Soultz-sous-Forêts,France 总被引:1,自引:0,他引:1
Rock matrix stimulation is a method of enhancing well production or injection within a broad range of challenging environments, varying from naturally fractured limestones to sandstones with complex mineralogy. A common and often successful stimulation option, matrix acidizing, utilizes acids that react and remove mineral phases restricting fluid flow. Reviewed is the technology of chemical treatments available for oil, gas and geothermal wells and the key elements and results of the chemical reservoir stimulation program at the Soultz-sous-Forêts, France, Enhanced Geothermal System Project. 相似文献
990.
The fault diagnosis is one of the most important topics on Proton Exchange Membrane Fuel Cell (PEMFC) stacks. Statistical methodologies for diagnosis are considered as one of the most relevant. This paper is dedicated to the diagnosis of flooding, using statistical methodology. 相似文献