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A series of star-shaped poly(lactic acid)s with carboxylic acid terminal groups have been synthesized by direct poly-condensation of lactic acid in the presence of a poly-carboxylic acid core molecule with triphenylphosphonium trifluoromethanesulfonate (TPP-T) catalyst.These star-polymers had thermal properties not very much different from those of star-shaped poly(lactic acid) with hydroxyl terminal groups and linear poly(lactic acid), irrespective of the structure of the core molecule and number of polymer arms. Solubility and degradability of these star-polymers were, however, greatly enhanced compared to those of star-polymers with hydroxyl terminal groups and increased depending on the number of polymer arms. From the star-shaped polymers, a variety of ammonium salts and the corresponding carboxyamides were successfully prepared. 相似文献
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Kunio Matsui Jun Kikuma Masamichi Tsunashima Tetsuji Ishikawa Shin-ya Matsuno Akihiro Ogawa Masugu Sato 《Cement and Concrete Research》2011,(5):510-519
The hydrothermal formation of tobermorite during the processing of autoclaved aerated concrete was investigated by in situ X-ray diffraction (XRD) analysis. High-energy X-rays from a synchrotron radiation source in combination with a newly developed autoclave cell and a photon-counting pixel array detector were used.To investigate the effects of the silica source, reactive quartz from chert and less-reactive quartz from quartz sand were used as starting materials. The effect of Al addition on tobermorite formation was also studied. In all cases, C-S-H, hydroxylellestadite and katoite were clearly observed as intermediates.Acceleration of tobermorite formation by Al addition was clearly observed. However, Al addition did not affect the dissolution rate of quartz. Two pathways, via C-S-H and katoite, were also observed in the Al-containing system. These results suggest that the structure of initially formed C-S-H is important for the subsequent tobermorite formation reactions. 相似文献
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Recovery of liquid fuel from hydrocarbon-rich microalgae by thermochemical liquefaction 总被引:11,自引:0,他引:11
Yutaka Dote Shigeki Sawayama Seiichi Inoue Tomoaki Minowa Shin-ya Yokoyama 《Fuel》1994,73(12):1855-1857
Liquefaction of Botryococcus braunii, a colony-forming microalga, with high moisture content was performed with or without sodium carbonate as a catalyst for conversion into liquid fuel and recovery of hydrocarbons. A greater amount of oil than the content of hydrocarbons in B. braunii (50 wt% db) was obtained, in a yield of 57–64 wt% at 300 °C. The oil was equivalent in quality to petroleum oil. The recovery of hydrocarbons was a maximum (>95%) at 300 °C. 相似文献
6.
Chunyang Liu Motoki Yagi Xu Gao Sun-Joong Kim Fuxiang Huang Shigeru Ueda Shin-ya Kitamura 《Metallurgical and Materials Transactions B》2018,49(5):2298-2307
Magnesia-chromite refractory materials are widely employed in steel production, and are considered a potential MgO source for the generation of MgO·Al2O3 spinel inclusions in steel melts. In this study, a square magnesia-chromite refractory rod was immersed into molten steel of various compositions held in an Al2O3 crucibles. As the immersion time was extended, Mg and Cr gradually dissolved from the magnesia-chromite refractory, and the Mg and Cr contents of the steel melts increased. However, it was found that the inclusions in the steel melts remained as almost pure Al2O3 because the Mg content of the steel melts was low, approximately 1 ppm. On the surface of the magnesia-chromite refractory, an MgO·Al2O3 spinel layer with a variable composition was formed, and the thickness of the MgO·Al2O3 spinel layer increased with the immersion time and the Al content of the steel melts. At the rod interface, the formed layer consisted of MgO-saturated MgO·Al2O3 spinel. The MgO content decreased along the thickness direction of the layer, and at the steel melts interface, the formed layer consisted of Al2O3-saturated MgO·Al2O3 spinel. Therefore, the low content of Mg in steel melts and the unchanged inclusions were because of the equilibrium between Al2O3-saturated MgO·Al2O3 layer and Al2O3. In addition, the effects of the Al and Cr contents of the steel melts on the dissolution of Mg from the magnesia-chromite refractory are insignificant. 相似文献
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Masanori Tanno Jiang Liu Xu Gao Sun-Joong Kim Shigeru Ueda Shin-ya Kitamura 《Metallurgical and Materials Transactions B》2017,48(6):2913-2921
The formation of metal emulsion in a steel-making process enhances the reaction between metal and slag. A part of the metal emulsion is formed by a bubble passing through the interface between the metal and slag phases. In a previous study, it was determined that the formation of metal column by the bubble is related to the formation of metal droplets. In this research, the effects of bubble particle size, interfacial tension, viscosity of upper layer, and lower layer density on the formation of lower liquid column were investigated. In order to conduct an in situ observation of gas and liquid behaviors, aqueous solution and silicon oil systems were employed. It was determined that a narrow and elongated column forms liquid droplets in the upper liquid layer and contributes to the formation of droplets. The height of the column and the volume of droplets increase with the increase in bubble size. The influence of interfacial tension of the two liquid phases on the column height and the formation of droplet is slight. The height of the formed column decreases with the increase in the density of lower liquid. 相似文献
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Miyazaki Y. Tada H. Shin-ya Tokizaki Takagi K. Aoyagi T. Mitsui Y. 《Quantum Electronics, IEEE Journal of》2003,39(6):813-819
A small-chirp 40-Gbps electroabsorption modulator (EAM) with a novel tensile-strained asymmetric quantum-well (QW) absorption layer has been demonstrated for the first time. The strain and the band line-up of the asymmetric QW structure were designed in order to obtain a small-chirp operation, a clear eye opening, and a high extinction ratio simultaneously. The chirp measured as /spl alpha/-parameter was reduced without any penalty of extinction ratio and eye opening. The measured /spl alpha/-parameter was smaller than 1.5 at any bias voltage from 0 to -2 V. The measured 3-dB bandwidth of a 75-/spl mu/m-long EAM exceeded 50 GHz at -1 V bias voltage. Under a 40-Gbps modulation, a clear eye opening was obtained, and the eye diagram showed no violation of the standard STM256/OC768 mask. The measured dynamic extinction ratio was over 11 dB. 相似文献
10.
Hiroshi Kominami Jun-ichi Kato Shin-ya Murakami Yoshinori Ishii Masaaki Kohno Kei-ichi Yabutani Takuhei Yamamoto Yoshiya Kera Masashi Inoue Tomoyuki Inui Bunsho Ohtani 《Catalysis Today》2003,84(3-4):181-189
Thermal treatment of titanium(IV) butoxide dissolved in 2-butanol at 573 K under autogenous pressure (alcohothermal treatment) yielded microcrystalline anatase-type titanium(IV) oxide (TiO2). Thermal treatment of oxobis(2,4-pentanedionato-O,O′)titanium (TiO(acac)2) in ethylene glycol (EG) in the presence of sodium acetate and a small amount of water at 573 K yielded microcrystalline brookite-type TiO2. Tungsten(VI) oxide (WO3) powders of monoclinic crystal structure with high crystallinity were synthesized by hydrothermal treatment (HTT), at 523 or 573 K, of aqueous tungstic acid (H2WO4) solutions prepared from sodium tungstate by ion-exchange (IE) with a proton-type resin. Anatase and brookite TiO2 products were calcined at various temperatures and then used for photocatalytic mineralization of acetic acid in aqueous solutions under aerated conditions and dehydrogenation of 2-propanol under deaerated conditions. Almost all the anatase-type TiO2 samples showed the activities more than twice higher than those of representative active photocatalysts, Degussa P-25 and Ishihara ST-01 in both reactions. A brookite sample with improved crystallinity and sufficient surface area obtained by calcination at 973 K exhibited the hydrogen evolution rate almost equal to P-25. HTT WO3 powders with various physical properties were used as photocatalyst for evolution of oxygen (O2) from an aqueous silver sulfate solution. WO3 powder of high crystallinity, e.g., IE-HTT-WO3 synthesized at 573 K, gave much higher O2 yield than commercially available WO3 samples. 相似文献