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91.
92.
Kapuruge Don Kunkuma Amila Somarathne Ekenechukwu C. Okafor Daiki Sugawara Akihiro Hayakawa Hideaki Kobayashi 《Proceedings of the Combustion Institute》2021,38(4):5163-5170
This study examined the effects of OH concentration and temperature on the NO emission characteristics of turbulent, non-premixed methane (CH4)/ammonia (NH3)/air swirl flames in two-stage combustors at high pressure. Emission data were obtained using large-eddy simulations with a finite-rate chemistry method from model flames based on the energy fraction of NH3 (ENH3) in CH4/NH3 mixtures. Although NO emissions at the combustor exit were found to be significantly higher than those generated by CH4/air and NH3/air flames under both lean and stoichiometric primary zone conditions, these emissions could be lowered to approximately 300 ppm by employing far-rich equivalence ratios (?) of 1.3 to 1.4 in the primary zone. This effect was possibly due to the lower OH concentrations under far-rich conditions. An analysis of local flame characteristics using a newly developed mixture fraction equation for CH4/NH3/air flames indicated that the local temperature and NO and OH concentration distributions with local ? were qualitatively similar to those in NH3/air flames. That is, the maximum local NO and OH concentrations appeared at local ? of 0.9, although the maximum temperature was observed at local ? of 1.0. Both the temperature and OH concentration were found to gradually decrease with the partial replacement of CH4 with NH3. Consequently, NO emissions from CH4/NH3 flames were maximized at ENH3 in the range of 20% to 30%, after which the emissions decreased. Above 2100 K, the NO emissions from CH4/NH3 flames increased exponentially with temperature, which was not observed in NH3/air flames because of the lower flame temperatures in the latter. But, the maximum NO concentration in CH4/NH3 flames was occurred at a temperature slightly below the maximum temperature, just as in NH3/air flames. The apparent exponential increase in NO emissions from CH4/NH3 flames is attributed to a similar trend in the OH concentration at high temperatures. 相似文献
93.
Wenting Bu Qiuju Guo Jian Zheng Shigeo Uchida 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(2):999-1005
Surface soil samples collected in the Jiuquan region in the downwind area of the Chinese nuclear test site (CNTs) were analyzed for Pu isotopes. The 239+240Pu activities ranged from 0.025 ± 0.009 to 0.89 ± 0.16 mBq g?1, varying significantly with different sampling sites. The Dunhuang city that is located in the southwestern part of the Jiuquan region received the heaviest Pu deposition (239+240Pu activities, 0.23–0.89 mBq g?1). Most of the 240Pu/239Pu isotopic ratios were similar with that of the global fallout. However, the low values (0.080–0.147) observed in three sampling sites further supported the finding of Pu originated from CNTs in that region. 相似文献
94.
Keiki Kishikawa Yuki Furukawa Tomohiro Watanabe Michinari Kohri Tatsuo Taniguchi Shigeo Kohmoto 《Liquid crystals》2017,44(8):1332-1339
Blue phases (BPs) obtained by doping a commercially available liquid crystalline compound (4-butyl-N-(4-ethoxybenzylidene)aniline (EBBA)) with (2R,3R)-2,3-bis(4-octyloxyphenylbenzoyloxy)-N-(hydroxydecyl)succinimide (1) were highly stabilised by the addition of a small amount of alkane diols. Especially, addition of only 0.5 mol% of octane-1,8-diol increased the BP–Iso transition temperature by 10 K and widened the BP temperature range up to 35 K. A model stabilisation mechanism based on the construction of a hydrogen bond network in each disclination zone in BPs was proposed. 相似文献
95.
96.
Wang J Sugawara A Shimojima A Okubo T 《Langmuir : the ACS journal of surfaces and colloids》2010,26(23):18491-18498
A facile solution process for the preparation of anisotropic silica nanoparticles (ASNPs) is presented. ASNPs are prepared via controlled self-assembly of spherical silica seeds (22 nm) in alcohol-water mixed media, followed by their in situ fixation and overgrowth with tetraethoxysilane (TEOS). Ethanol and L-arginine (Arg) are used to modify the dielectric constant and ionic strength of the reaction media, by which seed assembly is controlled through the adjustment of electrostatic interaction. Ethanol and Arg also serve as a cosolvent and a catalyst for hydrolysis and condensation of TEOS, respectively, which enables us to produce ASNPs in a simple one-pot process. In addition to ASNPs with wormlike structures, different kinds of NPs (bimodal spherical NPs, monodisperse spherical NPs, and spherical aggregates) have also been obtained by changing the concentrations of ethanol and Arg. The length, thickness, or both of ASNPs are controlled systematically by varying the concentrations of Arg, seed NPs, and TEOS. Other alcoholic cosolvents, such as methanol, 1-propanol, 2-propanol, and t-butanol, are also effective to give ASNPs when the dielectric constant of the alcohol-water mixed media is properly adjusted, showing the versatility of the present method. 相似文献
97.
We report the construction of a molecular recognition layer composed of polyelectrolyte brushes and metal complexes on the surface of a quartz crystal microbalance (QCM) and the sensing abilities for various volatile organic compounds (VOCs). Atom‐transfer radical polymerization of 2‐(dimethylamino)ethyl acrylate from an initiator‐terminated self‐assembled monolayer yielded polyelectrolyte brushes on the surface of a weight‐detectable quartz crystal microbalance. One end of a poly[(2‐dimethylamino)ethyl methacrylate] brush was covalently attached onto the surface of a sensor. We found that metallophthalocyanines with four bulky pentaphenylbenzene substituents could adsorb volatile organic compounds selectively into their cavities. Macromolecular metal complexes were prepared by immersing polymer‐brush‐modified QCMs into an aqueous solution of sterically protected cobalt phthalocyanine. Anionic cobalt phthalocyanine was trapped in the polymer brushes and acted as a molecular receptor for the sensing of VOC molecules. 相似文献
98.
A first synthesis of an asymmetric and amphiphilic β-substituted porphyrin is reported. The porphyrin can be integrated into various types of nanostructures with the amphiphilic characters in hydrophilic solvents. The one-dimensional integration may induce a magnetic interaction between the central metals. 相似文献
99.
100.
Sang-Woo Kim Teruhisa Kotani Masaya Ueda Shizuo Fujita Shigeo Fujita 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):601
Selective formation of ZnO nanodots grown by metalorganic chemical vapor deposition (MOCVD) was achieved on focused-ion beam (FIB)-nanopatterned SiO2 and Si substrates. The selective formation characteristics, dimension, and density of ZnO nanodots on FIB-nanopatterned substrates strongly depended on the FIB-patterning and MOCVD-growth conditions. The mechanism of the selective formation of ZnO nanodots on FIB-nanopatterned SiO2 substrates is attributed to a surfactant effect of the implanted Ga which leads to the formation of the preferred nucleation sites for the growth of ZnO nanodots, while that of ZnO nanodots on nanopatterned Si substrates is mainly considered in terms of the generation of surface atomic steps and kinks, which are created by Ga+ ion sputtering, on the patterned Si areas. 相似文献