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101.
ChenluSONG WenjianWENG KuiCHENG HaiboQU PiyiDU GeSHEN GaorongHAN JuanYANC JoseM.F.Ferreira 《材料科学技术学报》2003,19(5):495-499
Fluorapatite/hydroxyapatite solid solution has better biological properties than other apatites, especially used as films or coatings. In this work, sol-gel preparation and in vitro behavior of fluorapatite/hydroxyapatite solid solution films on titanium alloy were investigated. Ca(NO3)2-4H20 and PO(OH)x(OEt)3-x were selected as precursors, and hexafluorophosphoric acid (HPFo) was used as a fluorine containing reagent. The Ca and P precursors were mixed with HPFo to keep the Ca/P molar ratio 1.67. The mixtures refluxed for 12 h were used as dipping sols for the preparation of the films. The phase of the films obtained at 600℃ was apatite. The F contents in the films increased with the concentrations of HPF6 in the dipping sols. The solid solution films were shown to have better stability than hydroxyapatite films, and a reasonably good bioactivity in the in vitro evaluation. 相似文献
102.
The corrosion behaviour of tin in different concentrations of citric acid solutions (0.3–1.0 M, pH=1.8) was studied at 30 °C by potentiodynamic technique. The E/I profiles exhibit an active passive behaviour. The active dissolution involves one anodic peak A associated with a dissolution of the metals as Sn(II) species. The passivity is due to the formation of thin film of SnO2 and or Sn(OH)4 on the anode surface. The cathodic sweep shows a small peak C related to the reduction of the passive film. The peak current density Ip of peak A increases with increasing both acid concentration and sweep rate.
The effects of adding increasing concentrations of Na2CrO4, NaMoO4, NaNO3 and NaNO2 on the corrosion of tin in 0.5 M citric acid at 30 °C were investigated. Both CrO42− and MoO42− ions inhibit the corrosion of tin and the extent of inhibition enhances with their concentrations. Addition of either NO3− or NO2− accelerates the corrosion of tin. NO3− ions are more aggressive than NO2− ions. 相似文献
103.
Animesh Chakrabarti Man Mohan Sharma 《Journal of the American Oil Chemists' Society》1992,69(12):1251-1253
Anhydrous esterification of myristic acid with propylene was carried out in the temperature range of 110–145°C and pressure
from 190–195 psig in the presence of Amberlyst-15 (cation exchange resin) and Filtrol-24 (acid-treated clay) as catalysts.
The product ester, isopropyl myristate finds use in cosmetic and topical medicinal preparations where good absorption through
the skin is desired. Filtrol-24 is the catalyst of choice, and the recommended operating temperature is 130°C with a pressure
of 190 psig. 相似文献
104.
K. Y. Cheah T. S. Tang Fujio Mizukami Shu-ichi Niwa Makoto Toba Y. M. Choo 《Journal of the American Oil Chemists' Society》1992,69(5):410-416
A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-1-ol (oleyl + elaidyl
alcohol) at low pressure with high yield. Catalyst preparation methods, catalyst raw materials and activation conditions have
a significant effect on the activity of the catalyst. The optimum atomic ratio of ruthenium to tin is about 1:2. Catalyst
prepared by an improved sol-gel method shows higher activity and selectivity than catalysts prepared by impregnation and coprecipitation
methods. Chloride is found to have a negative effect on catalytic activity. The best catalyst is prepared from chloride-free
ruthenium and tin raw materials. Under the optimum reaction conditions of 250°C and 5.6 MPa, the selectivities for 9-octadecen-1-ol
and total alcohol (9-octadecen-1-ol + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%. 相似文献
105.
研究了杂多酸催化无水乙醇和环氧乙烷(EO)制备乙醇乙醚的醚化反应,考察了不同种类的杂多酸以及醚化反应工艺条件对反应活性和选择性的影响.结果表明,PW_(12)催化剂的反应活性高、反应温度低、选择性好,当用PW_(12)作催化剂,乙醇与环氧化乙烷之比为3.0(mol),反应温度45℃,反应时间1h时,转化率和选择性均超过97%. 相似文献
106.
107.
108.
Copper phthalocyanine as corrosion inhibitor for ASTM A606-4 steel in 16% hydrochloric acid 总被引:2,自引:0,他引:2
A study based on the corrosion inhibition properties of copper phthalocyanine is described. Coverage degrees of copper phthalocyanine (Cu-phcy) on ASTM-A606-4 steel, obtained by weight loss measurements, were fitted to Langmuir, Frumkin, Temkin and Flory–Huggins adsorption isotherms. A better fit to the Langmuir isotherm was obtained. The polarization curves showed that polarization of both the anodic and cathodic reactions were verified for concentrations higher than 10–4 M, indicating a mixed type action. Only the anodic reactions were polarized for lower concentrations. At high frequencies the Nyquist diagrams showed one capacitive loop attributable to double layer charging and a small one at intermediary frequencies attributable to the faradaic process of hydrogen evolution. The formation of an adsorbed film was characterized by increasing charge transfer resistance values in the low frequency range for increasing inhibitor concentrations. According to the techniques used in this study, copper phthalocyanines showed a high corrosion inhibiting efficiency for all concentrations. 相似文献
109.
Bhupesh C. Roy Motonobu Goto & Tsutomu Hirose 《International Journal of Food Science & Technology》1996,31(2):137-141
Tomato seed oil was extracted with supercritical carbon dioxide in a semibatch-flow extractor within the temperature range 313–343 K and the pressure range 10.8–24.5MPa. The extraction rates increased with pressure, but decreased with temperature increase because of the variation in solvent density and resultant differences in oil solubility. The fatty acid composition of the extracted oil was similar to that of soybean oil. 相似文献
110.