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Preparation of natural alpha-tocopherol from non-alpha-tocopherols. 从非α -生育酚制备天然α -生育酚。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1524
Yi-Wen Yang, Guang-Dong Wen, Cai-Juan Wu, Qi-Long Ren, Ping-Dong Wu
{"title":"Preparation of natural alpha-tocopherol from non-alpha-tocopherols.","authors":"Yi-Wen Yang,&nbsp;Guang-Dong Wen,&nbsp;Cai-Juan Wu,&nbsp;Qi-Long Ren,&nbsp;Ping-Dong Wu","doi":"10.1631/jzus.2004.1524","DOIUrl":"https://doi.org/10.1631/jzus.2004.1524","url":null,"abstract":"<p><p>Non-alpha-tocopherols are hydroxymethylated and hydrogenated to produce alpha-tocopherol in one pot process by simultaneously reacting with paraformaldehyde and hydrogen in the presence of catalysts of benzenesulfonic acid and 5% Pd/C in an autoclave. Effects of various operation conditions have been studied. The preferable reaction conditions are: temperature 180 degrees C to 200 degrees C, pressure 5.0 MPa, acid concentration 0.5 g/100 ml ethanol, mass ratio of Pd/C to tocopherols 7.1 g/100 g, and reaction time 5.0 h. A product with alpha-tocopherol content of 80% was obtained by using a raw material with a total tocopherols content of 80.54%. The conversion of non-alpha-tocopherols is almost 100%, and the mole yield of alpha-tocopherol is more than 90%.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1524-7"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1524","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24815050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Experimental study on transient behavior of semi-open two-phase thermosyphon. 半开式两相热虹吸管瞬态特性实验研究。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1565
Hua Zhu, Jian-Xin Wang, Qiao-Hui Zhang, Chuan-Jing Tu
{"title":"Experimental study on transient behavior of semi-open two-phase thermosyphon.","authors":"Hua Zhu,&nbsp;Jian-Xin Wang,&nbsp;Qiao-Hui Zhang,&nbsp;Chuan-Jing Tu","doi":"10.1631/jzus.2004.1565","DOIUrl":"https://doi.org/10.1631/jzus.2004.1565","url":null,"abstract":"<p><p>An experimental system was set up to measure the temperature, pressure, heat transfer rate and mass flow rate in a semi-open two-phase thermosyphon. The behaviors of a semi-open two-phase thermosyphon during startup, shutdown and lack of water were studied to get complete understanding of its thermal characteristics. The variation of wall temperature, heat-exchange condition and pressure fluctuations of semi-open two-phase thermosyphons showed that the startup of SOTPT needs about 60-70 min; the startup speed of SOTPT is determined by the startup speed of the condensation section; the average pressure in the heat pipe is equal to the environmental pressure usually; the shutdown of SOTPT needs about 30-50 min; a semi-open two-phase thermosyphon has good response to lack of water accident.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1565-9"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1565","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24815531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
Solvothermal synthesis of nanosized CoSb(3) skutterudite. 溶剂热法合成纳米CoSb(3)方钨矿。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1504
Jian Xie, Xin-Bing Zhao, Jian-Li Mi, Gao-Shao Cao, Jiang-Ping Tu
{"title":"Solvothermal synthesis of nanosized CoSb(3) skutterudite.","authors":"Jian Xie,&nbsp;Xin-Bing Zhao,&nbsp;Jian-Li Mi,&nbsp;Gao-Shao Cao,&nbsp;Jiang-Ping Tu","doi":"10.1631/jzus.2004.1504","DOIUrl":"https://doi.org/10.1631/jzus.2004.1504","url":null,"abstract":"<p><p>Nanostructures enhance phonon scattering and improve the figure of merit of thermoelectric materials. Nanosized CoSb(3) skutterudite was synthesized by solvothermal methods using CoCl(2) and SbCl(3) as the precursors. A \"two-step\" model was suggested for the formation of CoSb(3) based on the X-ray diffraction analysis. The first step is the formation of cobalt diantimonide in the earlier stage during the synthesis process. Diantimonide was then combined with antimony atoms to form the skutterudite structured triantimonide, CoSb(3), in the later stage of the synthesis process as the second step. The synthesized CoSb(3) powders consist of irregular particles with sizes of about 20 nm and sheets of about 80 nm.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1504-8"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1504","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24816412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 16
Ant colony system algorithm for the optimization of beer fermentation control. 蚁群算法在啤酒发酵控制中的应用。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1597
Jie Xiao, Ze-Kui Zhou, Guang-Xin Zhang
{"title":"Ant colony system algorithm for the optimization of beer fermentation control.","authors":"Jie Xiao,&nbsp;Ze-Kui Zhou,&nbsp;Guang-Xin Zhang","doi":"10.1631/jzus.2004.1597","DOIUrl":"https://doi.org/10.1631/jzus.2004.1597","url":null,"abstract":"<p><p>Beer fermentation is a dynamic process that must be guided along a temperature profile to obtain the desired results. Ant colony system algorithm was applied to optimize the kinetic model of this process. During a fixed period of fermentation time, a series of different temperature profiles of the mixture were constructed. An optimal one was chosen at last. Optimal temperature profile maximized the final ethanol production and minimized the byproducts concentration and spoilage risk. The satisfactory results obtained did not require much computation effort.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1597-603"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1597","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24816004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 20
Research on the rheological properties of pesticide suspension concentrate. 农药悬浮液的流变性能研究。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1604
Cheng-Xia Tan, De-Long Shen, Jian-Quan Weng, Qing-Wu Chen, Hui-Jun Liu, Qi-Liang Yuan
{"title":"Research on the rheological properties of pesticide suspension concentrate.","authors":"Cheng-Xia Tan,&nbsp;De-Long Shen,&nbsp;Jian-Quan Weng,&nbsp;Qing-Wu Chen,&nbsp;Hui-Jun Liu,&nbsp;Qi-Liang Yuan","doi":"10.1631/jzus.2004.1604","DOIUrl":"https://doi.org/10.1631/jzus.2004.1604","url":null,"abstract":"<p><p>This study reports research on pesticide suspension rheology and a new rheological parameter, the relative value of approach, which has great advantage for judging the physical stability of a pesticide suspension concentrate. Experiments showed that the system can form stable dispersions when the value of the relative value of approach (S(r)) is less than 0.1.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1604-7"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1604","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24816005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Land degradation, government subsidy, and smallholders' conservation decision: the case of the loess plateau in China. 土地退化、政府补贴与小农保护决策:以中国黄土高原为例。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1533
Min-Jun Shi, Kevin Chen
{"title":"Land degradation, government subsidy, and smallholders' conservation decision: the case of the loess plateau in China.","authors":"Min-Jun Shi,&nbsp;Kevin Chen","doi":"10.1631/jzus.2004.1533","DOIUrl":"https://doi.org/10.1631/jzus.2004.1533","url":null,"abstract":"<p><p>Land degradation is one of the severe environmental problems in China. In order to combat land degradation, a soil conservation program was introduced since 2000 to reduce soil erosion by converting slope-cultivated land into forestry and pasture. This paper represents the first systematic attempt to investigate the impact of the soil conservation program on land degradation in the loess plateau. The results indicate that the soil conservation program to convert slope fields into forest or pasture is an effective way to combat soil erosion. However, a subsidy that is higher than profit of land use activity of slope fields before their conversion into forest and pasture is needed to encourage farmers to join the conservation program. A policy measure to encourage and assist farmers to develop sedentary livestock by using crops produced from fields as well as fodder and forage grass from the converted slope fields might contribute to combat soil erosion. Increase in off-farm job opportunities may encourage households to reduce cultivation in slope fields. That implies a policy measure to encourage rural urbanization might contribute to combat soil erosion.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1533-42"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1533","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24815052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 11
The mechanism of Fe (III)-catalyzed ozonation of phenol. Fe (III)催化苯酚臭氧化反应机理研究。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1543
Xiang-Feng Zhu, Xin-Hua Xu
{"title":"The mechanism of Fe (III)-catalyzed ozonation of phenol.","authors":"Xiang-Feng Zhu,&nbsp;Xin-Hua Xu","doi":"10.1631/jzus.2004.1543","DOIUrl":"https://doi.org/10.1631/jzus.2004.1543","url":null,"abstract":"<p><p>Fe (III)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe(3+)) dosage. The existence of a critical pH value determining the catalysis of Fe (III) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (III)-catalyzed ozonation of phenol was obtained based on the results and literature.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1543-7"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1543","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24815053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 19
Comparison of volatile and semivolatile compounds from commercial cigarette by supercritical fluid extraction and simultaneous distillation extraction. 用超临界流体萃取和同步蒸馏萃取法比较商用卷烟中的挥发性和半挥发性化合物。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1528
Zi-Gang Xu, Lin Zheng
{"title":"Comparison of volatile and semivolatile compounds from commercial cigarette by supercritical fluid extraction and simultaneous distillation extraction.","authors":"Zi-Gang Xu, Lin Zheng","doi":"10.1631/jzus.2004.1528","DOIUrl":"10.1631/jzus.2004.1528","url":null,"abstract":"<p><p>Supercritical carbon dioxide fluid extraction (SFE) was studied as a rapid method for extraction of volatile and semivolatile compounds of Chinese commercial cigarettes. The method was compared with simultaneous distillation and extraction (SDE). Temperature and pressure for the SFE were optimized. The extracts obtained by the two methods showed different characters in composition and represented differently the flavor characteristics of tobacco; compared to SDE, SFE can extract compounds within a shorter time and avoid the thermal degradation and solvent contamination of samples. The extracts by the two extraction methods are complementary for investigating the flavor characteristic of tobacco products.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1528-32"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1528","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24815051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
Synthesis of TiO(2) supported on activated carbon by MOCVD: operation parameters study. MOCVD法合成活性炭负载型TiO(2):操作参数研究
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1548
Xing-Wang Zhang, Ming-Hua Zhou, Le-Cheng Lei, Su Xu
{"title":"Synthesis of TiO(2) supported on activated carbon by MOCVD: operation parameters study.","authors":"Xing-Wang Zhang,&nbsp;Ming-Hua Zhou,&nbsp;Le-Cheng Lei,&nbsp;Su Xu","doi":"10.1631/jzus.2004.1548","DOIUrl":"https://doi.org/10.1631/jzus.2004.1548","url":null,"abstract":"<p><p>The metallo-organic chemical vapor deposition (MOCVD) technique has been applied to the preparation of the photocatalyst titanium dioxide supported on activated carbon. The effects of various condition parameters such as carrier gas flow rate, source temperature and deposition temperature on the deposition rate were investigated. The maximum deposition rate of 8.2 mg/(g x h) was obtained under conditions of carrier gas flow rate of 400 ml/min, source temperature of 423 K and deposition temperature of 913 K. The deposition rate followed Arrhenius behavior at temperature of 753 K to 913 K, corresponding to activation energy E(a) of 51.09 kJ/mol. TiO(2) existed only in anatase phase when the deposition temperature was 773 K to 973 K. With increase of deposition temperature from 1073 K to 1273 K, the rutile content sharply increased from 7% to 70%. It was found that a deposition temperature of 773 K and a higher source temperature of 448 K resulted in finely dispersed TiO(2) particles, which were mainly in the range of 10-20 nm.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1548-53"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1548","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24815054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 15
Mutagenic effects of chromium trioxide on root tip cells of Vicia faba. 三氧化铬对蚕豆根尖细胞的诱变作用。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1570
Xiao-Wei Qian
{"title":"Mutagenic effects of chromium trioxide on root tip cells of Vicia faba.","authors":"Xiao-Wei Qian","doi":"10.1631/jzus.2004.1570","DOIUrl":"https://doi.org/10.1631/jzus.2004.1570","url":null,"abstract":"<p><p>In this study on the mutagenic effects of different concentrations of chromium trioxide (CrO(3)) on Vicia faba root tip, micronucleus assay and chromosome aberration assay were used to determine the mitotic indexes, micronucleus aberration rate and chromosome aberration rate of Vicia faba root tip cells. The results showed that the effects of CrO(3) concentration on the mitotic indexes were complicated. CrO(3) increases the micronucleus aberration rate of Vicia faba root tip cells. It was found that within certain range of CrO(3) concentration the micronucleus aberration rate increased systematically with increased concentration of CrO(3), but that the micronucleus aberration rate decreased at higher level of CrO(3) and that CrO(3) also caused various types of chromosome aberration at a rate which increased systematically with increased concentration of CrO(3). We concluded that CrO(3) has significant mutagenic effect on Vicia faba root tip cells.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1570-6"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1570","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24815532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 62
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