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排序方式: 共有259条查询结果,搜索用时 31 毫秒
251.
A sum-frequency-generation system for differential absorption lidar measurement of atmospheric nitrogen dioxide in the lower troposphere was developed. The system uses a combination of a pair of KD*P crystals and a tunable dye laser with LDS 765 dye pumped by the second harmonic of a Nd:YAG laser to generate lambdaon and lambdaoff alternatively. Compared with the conventional system that uses Coumarin 445 dye pumped by the third harmonic, the output energy and long-term stability were improved. By use of this system, atmospheric NO2 concentrations of approximately 10-50 ppb were measured, with an instrumental error of approximately 7 ppb. 相似文献
252.
Koichiro Fukuda Iwao Maki Suketoshi Ito Hideto Yoshida Chika Kato 《Journal of the American Ceramic Society》1994,77(11):3027-3029
During the remelting reaction, belite crystals with Al/Fe ratio <1 produced a liquid which formed droplets on the lamellar boundaries; the rate of remelting reaction was very low. Belite crystals with Al/Fe >1 produced a liquid which readily spread on the lamellae with a resulting high rate of reaction. At 1450°C the distribution coefficient of Al and Fe atoms between the belite and the interstitial liquid ((Al/Fe)Belite /(Al/Fe)Liquid ) was about 0.8. 相似文献
253.
Zheng Wang Keizo Nakagawa Kecheng Guan Qiangqiang Song Siyu Zhou Shunsuke Tanaka Yasunao Okamoto Atsushi Matsuoka Eiji Kamio Guangchao Li Molly Meng-Jung Li Tomohisa Yoshioka Hideto Matsuyama 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(33):2300672
Laminar membranes comprising graphene oxide (GO) and metal–organic framework (MOF) nanosheets benefit from the regular in-plane pores of MOF nanosheets and thus can support rapid water transport. However, the restacking and agglomeration of MOF nanosheets during typical vacuum filtration disturb the stacking of GO sheets, thus deteriorating the membrane selectivity. Therefore, to fabricate highly permeable MOF nanosheets/reduced GO (rGO) membranes, a two-step method is applied. First, using a facile solvothermal method, ZnO nanoparticles are introduced into the rGO laminate to stabilize and enlarge the interlayer spacing. Subsequently, the ZnO/rGO membrane is immersed in a solution of tetrakis(4-carboxyphenyl)porphyrin (H2TCPP) to realize in situ transformation of ZnO into Zn-TCPP in the confined interlayer space of rGO. By optimizing the transformation time and mass loading of ZnO, the obtained Zn-TCPP/rGO laminar membrane exhibits preferential orientation of Zn-TCPP, which reduces the pathway tortuosity for small molecules. As a result, the composite membrane achieves a high water permeance of 19.0 L m−2 h−1 bar−1 and high anionic dye rejection (>99% for methyl blue). 相似文献
254.
Development of antifouling poly(vinyl chloride) blend membranes by atom transfer radical polymerization
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In this study, antifouling poly(vinyl chloride) (PVC) blend membranes were prepared by blending the PVC based amphiphilic copolymer PVC‐g‐poly(hydroxyethyl methacrylate) (PVC‐g‐PHEMA), synthesized by atom transfer radical polymerization (ATRP), into the hydrophobic PVC matrix via the nonsolvent‐induced phase separation method. The in situ ATRP reaction solutions were also used as the blend additives to improve membrane performance. Attenuated total reflectance–Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy indicated that the blend membranes based on the two blend routes exhibited similar surface chemical compositions. The membrane morphology and surface wettability were determined by scanning electronic microscopy and water contact angle measurement, respectively. The blend membranes showed improved water permeability, comparable rejections and enhanced antifouling properties compared with the pure PVC membrane. The PVC blend membranes also had excellent long‐term stability in terms of chemical compositions and fouling resistance. The results demonstrated that ATRP was a promising technique to synthesize amphiphilic copolymer and prepare stable blend antifouling membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45832. 相似文献
255.
Yu You Makoto Ohtsuka Hideto Miyake Hiroyuki Fukuyama 《Journal of the American Ceramic Society》2014,97(12):3781-3786
The growth of AlN crystals on c‐plane 6H–SiC substrates by thermal nitridation of Al2O3 pellets in the presence of graphite and ZrO2 was demonstrated. Addition of graphite and ZrO2 effectively accelerated the evaporation of Al2O3, yielding c‐axis oriented AlN films on SiC substrates. The SiC substrate was severely deteriorated at 2173 K, which produced a porous interface between the AlN film and substrate, resulting in low‐quality AlN crystals. The deterioration of SiC was successfully suppressed by introducing a pre‐deposited homo‐buffer layer, allowing two‐dimensional‐like growth of AlN. The buffer layer promoted the formation of a high‐quality AlN film. At 2173 K, the full‐width at half maximum of the X‐ray rocking curves of the (0002) and (10–10) planes of the AlN film was 360 and 425 arcsec, respectively. 相似文献
256.
Differential scanning calorimetry and wide-angle X-ray diffractometry first revealed the formation of hetero-stereocomplex (HTSC) between biodegradable, optically active, and isotactic poly(2-hydroxyalkanoic acid)s having different chemical structures and opposite configurations, i.e., l-configured substituted poly(lactic acid) (PLA) [poly(l-2-hydroxybutanoic acid), P(l-2HB)] with linear side chains (ethyl groups) and d-configured substituted PLA [poly(d-2-hydroxy-3-methylbutanoic acid), P(d-2H3MB)] with branched side chains (isopropyl groups) in solution and in bulk from the melt. The melting temperature of P(l-2HB)/P(d-2H3MB) HTSC crystallites was 197–204 °C, which is much higher those of P(l-2HB) and P(d-2H3MB) homo-crystallites (100–101 °C and 158–165 °C, respectively). The interplain distances and crystalline lattice sizes of P(l-2HB)/P(d-2H3MB) HTSC crystallites were respectively larger and smaller than those of P(l-2HB)/P(d-2HB) and P(l-2H3MB)/P(d-2H3MB) homo-stereocomplexes. The HTSC formation of substituted PLA with opposite configurations reported in the present study will provide a versatile way to prepare poly(2-hydroxyalkanoic acid)-based biodegradable materials having a wide variety of physical properties and biodegradability. 相似文献
257.
258.
Shiinoki Masato Hashimoto Nao Fukuda Hideto Ando Yuki Suzuki Shinsuke 《Metallurgical and Materials Transactions B》2018,49(6):3357-3366
Metallurgical and Materials Transactions B - By utilizing the shear cell technique and achieving stable density layering with the addition of an alloying element Bi, the self-diffusion coefficients... 相似文献
259.
Jiayu Zhang Yuqing Lin Yiren Zhang Baolong Wu Xingzhong Cao Zhenjia Shi Zhicheng Xu Jiadi Ying Yan Jin Qianhong She Hideto Matsuyama Jianguo Yu 《American Institute of Chemical Engineers》2023,69(12):e18232
Precise control over the nanofluid behavior of polyelectrolyte-based membranes is a primary step toward understanding the structure-morphology-property relationships to ultimately determine the mass transfer characteristics. In this study, a high-performance multistacked polyelectrolyte-based cation exchange membrane (CEM) with a heterogeneous structure and versatile surface chemistry was developed to achieve selective ion conductance. The self-assembled CEM can facilitate ion permeation with fluxes of 2.9 mol m−2 h−1 for K+ and 0.22 mol m−2 h−1 for Mg2+, reaching a mono/multivalent ionic selectivity of up to 13, outperforming mono/divalent fractionation when compared with state-of-the-art membranes. Molecular dynamic (MD) simulations illustrated the ionic transport trajectory in hierarchical channels with angstrom-scale cavities using multilayered CEMs. Both the experimental measurements and theoretical simulations indicated that ionic fractionation was associated with a large disparity in the energy barrier between mono/multivalent cations, which was the primary origin of the differences in the ion dehydration-rehydration processes in the angstrom-confinement membrane ion channels. 相似文献