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Keiji Sakaki Toshihiro Yokochi Osamu Suzuki Toshikatsu Hakuta 《Journal of the American Oil Chemists' Society》1990,67(9):553-557
The extraction of oil from fungi (Mortierella ramanniana var.angulispora) was studied using carbon dioxide (CO2), nitrous oxide (N2O), trifluoromethane (CHF3) and sulfur hexafluoride (SF6) under supercritical conditions. The oil solubility was highest in SC-N2O followed by SC-CO2, while both SC-CHF3 and SC-SF6 showed poorer solvent power. The recorded oil solubilities at 333 K and 24.5 MPa were 2.3 wt% in N2O, 0.48 wt% in CO2, 0.0099 wt% in CHF3 and 0.0012 wt% in SF6.
The oil solubilities in SC-N2O and SC-CO2 were measured over the pressure range 15.7–29.4 MPa and at temperatures ranging from 313–353 K. N2O always showed greater solvent power than did CO2 at the same temperature and pressure. The solvent power of a supercritical fluid increases with density at a given temperature,
and increases with temperature at constant density.
The change in neutral lipid composition of the extracted oil with the extraction ratio was measured. Free fatty acids or diglycerides
were extracted more easily than triglycerides or sterol esters. The change in fatty acid composition was also measured. The
proportion of γ-linolenic acid in the extract remained constant throughout the extraction. 相似文献
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The gaseous visosity of trifluoromethane (CHF3) was measured in the critical region. The experimental temperature range was between 299.150 and 303.150 K and the pressure
range was up to 5.66 MPa. The measurements were obtained with an oscillating-disk viscometer, combined with local determination
of the density at the position of the oscillating disk, and they have an estimated accuracy of 0.6% for the viscosity and
0.5% for the gas density. The viscosity of CHF3 exhibits an anomalous increase near the critical point. The anomalous increase in viscosity was analyzed with the viscosity
equation proposed by Basu and Sengers. 相似文献
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研究双(三氟甲基磺酰)亚胺锂(LiTFSI)和二氟草酸硼酸锂(LiODFB)混合锂盐电解液用于磷酸铁锂(LiFePO_4)锂离子电池时的高温60℃性能,用SEM和X射线光电子能谱(XPS)研究高温60℃下LiTFSI基电解液对铝箔的腐蚀及LiODFB的防腐蚀机理。在高温60℃下,LiODFB的加入能减少LiTFSI基电解液对铝箔的腐蚀;当LiTFSI与LiODFB物质的量比为4∶6时,混盐基电解液电池以1 C在2.5~4.2 V充放电,第80次循环的放电容量保持率为99.7%,优于商业化六氟磷酸锂(LiPF_6)基电解液电池的58.6%。 相似文献
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Fernanda F.C. Bazito 《Electrochimica acta》2007,52(23):6427-6437
Two room temperature ionic liquids (RTILs) without acidic protons, based on different cationic species (1-n-butyl-2,3-dimethylimidazolium) (BMMI) and N-n-butyl-N-methylpiperidinium (BMP) using (CF3SO2)2N− (TFSI) as anion, were prepared by quaternization of their respective amines with an appropriate alkyl halide, followed by ion exchange reaction. All relevant properties of these ionic liquids, such as, thermal stability, density, viscosity, electrochemical behavior, ionic conductivity and self-diffusion coefficients for both ionic species, were determined at different temperatures. In spite of their ionic conductivity being lower than 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonylimide) (BMITFSI), the absence of an acidic proton in both compounds is crucial to maintain their chemical stability towards metallic lithium and, thereby, to make possible the safe assembly of lithium ion batteries. Both ionic liquids without acidic protons do not react with metallic lithium; on the other hand, the formation of carbene species when BMITFSI was exposed to Li was confirmed by 1H and 13C nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS). 相似文献
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The treatment or upgrading of waste trifluoromethane (CHF3, R23), which has a significant greenhouse effect, is of great importance in industry. Herein, series of SO42−/ZrO2-SiO2 catalysts with different Brønsted and Lewis acid site densities and ratios were prepared for pyrolysis of R23 to tetrafluoroethylene (C2F4, TFE) and hexafluoropropylene (C3F6, HFP). The effects of impregnation concentration of (NH4)2SO4 on specific surface area, crystal phase, and Brønsted and Lewis acid site densities and ratios were respectively demonstrated. The Brønsted and Lewis acid sites were observed to have cooperative effects on R23 transformation and up to 94.6% selectivity of (TFE + HFP) could be achieved at 750°C. The kinetic studies revealed the decomposition of R23 into CF2 carbene and HF was the rate-determining step, and a deactivation behavior was found due to the site coverage and pore blockage by the oligomers of TFE and HFP. 相似文献
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Reactive ion etching (RIE) was performed on gallium nitride (GaN) films grown by electron cyclotron resonance (ECR) plasma
assisted molecular beam epitaxy (MBE). Etching was carried out using trifluoromethane (CHF3) and chloropentafluoroethane (C2ClF5) plasmas with Ar gas. A conventional rf plasma discharge RIE system without ECR or Ar ion gun was used. The effects of chamber
pressure, plasma power, and gas flow rate on the etch rates were investigated. The etch rate increased linearly with the ratio
of plasma power to chamber pressure. The etching rate varied between 60 and 500Å/min, with plasma power of 100 to 500W, chamber
pressure of 60 to 300 mTorr, and gas flow rate of 20 to 50 seem. Single crystalline GaN films on sapphire showed a slightly
lower etch rate than domain-structured GaN films on GaAs. The surface morphology quality after etching was examined by atomic
force microscopy and scanning electron microscopy. 相似文献
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Biodegradable synthetic polymers: Preparation, functionalization and biomedical application 总被引:1,自引:0,他引:1
Huayu TianZhaohui Tang Xiuli ZhuangXuesi Chen Xiabin Jing 《Progress in Polymer Science》2012,37(2):237-280
Biodegradable polymers have been widely used and have greatly promoted the development of biomedical fields because of their biocompatibility and biodegradability. The development of biotechnology and medical technology has set higher requirements for biomedical materials. Novel biodegradable polymers with specific properties are in great demand. Biodegradable polymers can be classified as natural or synthetic polymers according to the source. Synthetic biodegradable polymers have found more versatile and diverse biomedical applications owing to their tailorable designs or modifications. This review presents a comprehensive introduction to various types of synthetic biodegradable polymers with reactive groups and bioactive groups, and further describes their structure, preparation procedures and properties. The focus is on advances in the past decade in functionalization and responsive strategies of biodegradable polymers and their biomedical applications. The possible future developments of the materials are also discussed. 相似文献