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81.
X. Liang X. Wang J. Zhuang Y. Chen D. Wang Y. Li 《Advanced functional materials》2006,16(14):1805-1813
Uniform magnetite, hematite, and goethite nanocrystals were prepared through an attractive method based on an oleic acid/alcohol/water system. By adjusting the synthetic parameters (base concentration, alcohol content, categories of alcohols, etc.), the controlled synthesis of uniform magnetite, hematite, and goethite nanocrystals can be easily achieved. Detailed investigations on the effect of the experimental parameters on the morphology of the final products and the phase transitions among the magnetite, hematite, and goethite phases were carried out. Finally, a method of doping other metal ions into magnetite was developed and the magnetic properties of magnetite doped with different metal elements were studied. 相似文献
82.
Auguste Commeyras Hlne Collet Laurent Boiteau Jacques Taillades Odile Vandenabeele‐Trambouze Herv Cottet Jean‐Philippe Biron Raphaël Plasson Louis Mion Olivier Lagrille Herv Martin Franck Selsis Michel Dobrijevic 《Polymer International》2002,51(7):661-665
Addressing the still open question of the prebiotic origin of sequential macromolecules (peptides, nucleic acids) on the primitive Earth, we describe a molecular engine (the primary pump), which works at ambient temperature and continuously generates, elongates and complexifies sequential peptides. This new scenario is based on a cyclic reaction sequence, whose keystep is the activation of amino acids into their N‐carboxyanhydrides (NCA) through nitrosation by NOx. This process could have taken place on tidal beaches; it requires a buffered ocean, emerged land and a nitrosating atmosphere. With the help of geochemical studies and computer simulations of atmosphere photochemistry, we show that the primitive Earth during the Hadean may have satisfied all these requirements. © 2001 Society of Chemical Industry. 相似文献
83.
面120区稠油热采增产试验效果分析 总被引:1,自引:1,他引:0
八面河油田面120区储层渗透率较低,油层原油粘度较大,出现了热采效果差,地层能量下降快的现象。针对这种情况可采用氮气+蒸汽吞吐技术。实践表明,该项技术的应用提高了井筒隔热效果,降低了热损失,同时又补充了能量,调整了吸汽剖面。需要强调的是在热采过程中,对油层的保护可采用伴蒸汽注入,但这种方法容易造成地层伤害。因此,在采用伴蒸汽方式时,注入防膨效果最佳。 相似文献
84.
Rakel Lindström Henri Groult Sandrine Zanna Philippe Marcus 《Electrochimica acta》2006,51(23):5001-5011
In order to produce thin films of crystalline V2O5, vanadium metal was thermally oxidised at 500 °C under oxygen pressures between 250 and 1000 mbar for 1-5 min. The oxide films were characterised by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). The lithium intercalation performance of the oxide films was investigated by cyclic voltammetry (CV), chronopotentiometry and electrochemical impedance spectroscopy (EIS). It was shown that the composition, the crystallinity and the related lithium intercalation properties of the thin oxide films were critically dependent on the oxidation conditions. The formation of crystalline V2O5 films was stimulated by higher oxygen pressure and longer oxidation time. Exposure for 5 min at 750 mbar O2 at 500 °C resulted in a surface oxide film composed of V2O5, and consisting of crystallites up to 200 nm in lateral size. The thickness of the layer was about 100 nm. This V2O5 oxide film was found to have good cycling performance in a potential window between 3.8 and 2.8 V, with a stable capacity of 117 ± 10 mAh/g at an applied current density of 3.4 μA/cm2. The diffusion coefficients corresponding to the two plateaus at 3.4 and 3.2 V were determined from the impedance measurements to (5.2 and 3.0) × 10−13 cm2 s−1, respectively. Beneath the V2O5 layer, lower oxides (mainly VO2) were found close to the metal. At lower oxygen pressure and shorter exposure times, the oxide films were less crystalline and the amount of V4+ increased in the surface oxide film, as revealed by XPS. At intermediate oxygen pressures and exposure times a mixture of crystalline V2O5 and V6O13 was found in the oxide film. 相似文献
85.
Tanja Kolli Katariina Rahkamaa-Tolonen Ulla Lassi Auli Savimki Riitta L. Keiski 《Catalysis Today》2005,100(3-4):303-307
In this study, Pd/Al2O3 and Pd/BaO/Al2O3 metallic monoliths were used to investigate the effect of BaO in C2H4 and CO oxidation as well as in NO reduction. A FT-IR gas analyser was used to study the activity of the catalysts. Several activity experiments carried out with dissimilar feedstreams revealed that BaO enhances CO and C2H4 oxidation as well as NO reduction reactions in rich conditions. This effect is due to BaO, which causes a decrease in the ethene poisoning of palladium. In lean conditions BaO is present in the form of Ba(OH)2 which reacts with oxidised NO releasing water. Therefore, NO was stored during the lean reaction. 相似文献
86.
E. Ya. Davydov I. S. Gaponova T. V. Pokholok G. B. Pariiskii G. E. Zaikov 《应用聚合物科学杂志》2008,108(1):128-133
The features of initiation of free radical reactions in polymers by dimers of nitrogen dioxide are considered. The conversion of planar dimers into nitrosyl nitrate in the presence of amide groups of macromolecules has been revealed. Nitrosyl nitrate initiates radical reactions in oxidative primary process of electron transfer with formation of intermediate radical cations and nitric oxide. As a result of subsequent reactions, nitrogen‐containing radicals are produced. The dimer conversion has been exhibited by estimation of the oxyaminoxyl radical yield in characteristic reaction of p‐benzoquinone with nitrogen dioxide on addition of aromatic polyamide and polyvinylpyrrolidone to reacting system. The isomerization of planar dimers is efficient in their complexes with amide groups, as confirmed by ab initio calculations. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
87.
生产电子工业用高纯氮的制氮装置 ,其要点和难点是一氧化碳和氢的清除。采用一氧化碳转换炉和特殊的冷箱内流程组织 ,可以生产纯度为 99 9999%以上的高纯氮。对制取电子工业用高纯氮制氮装置与常规制氮装置加氮终端净化器两种流程进行了比较。 相似文献
88.
89.
90.
Frank J. Owens 《Materials Letters》2007,61(10):1997-1999
Molecular orbital calculations of the ionization potential of single wall carbon nanotubes having donor NH2 and acceptor NO2 groups bonded to the side walls and ends and boron and nitrogen substituted for carbon show substantial increases in ionization potential compared to carbon nanotubes with no functional groups and no carbon substitutions. The presence of a carbon vacancy on the side wall also causes a substantial increase in the ionization potential. The effect of tube length on the ionization energy is also calculated. The calculations also suggest that at appropriate levels of boron and nitrogen doping the armchair carbon nanotubes could be high temperature organic ferromagnetic materials. 相似文献