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热工过程参数的改进逐维黄金分割法辨识 被引量:1
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作者 韦根原 冯新强 《热力发电》 CAS 北大核心 2015年第10期68-71,76,共5页
针对基于群体智能算法的热工过程参数辨识存在随机性强、收敛慢、耗时长的不足,提出了一种快速辨识方法。在仿真验证辨识目标函数随各个参数变化呈单峰性后,将黄金分割法与坐标轮换法相结合,形成逐维黄金分割法,并通过选取最优初始点和... 针对基于群体智能算法的热工过程参数辨识存在随机性强、收敛慢、耗时长的不足,提出了一种快速辨识方法。在仿真验证辨识目标函数随各个参数变化呈单峰性后,将黄金分割法与坐标轮换法相结合,形成逐维黄金分割法,并通过选取最优初始点和提高寻优精度等方法对其进行改进;基于现场数据分别采用粒子群优化算法、逐维黄金分割法及其改进算法对风煤比-过氧量模型的过程参数进行了辨识比较。结果表明,改进后的逐维黄金分割法在快速性、精确性上明显优于粒子群算法和逐维黄金分割法,其更适合于热工过程参数的在线辨识,从而为热工控制系统调节参数的在线快速优化提供条件。 展开更多
关键词 热工过程 参数辨识 逐维黄金分割法 坐标轮换法 粒子群优化算法 风煤比 过氧量
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The application of metal-organic frameworks and their derivatives for lithium-ion capacitors
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作者 ZHAO Sha-sha ZHANG Xiong +5 位作者 LI Chen AN Ya-bin HU Tao WANG Kai SUN Xian-zhong MA Yan-wei 《新型炭材料(中英文)》 SCIE EI CAS CSCD 北大核心 2024年第5期872-895,共24页
There is an urgent need for lithium-ion capacitors(LICs)that have both high energy and high power densities to meet the continuously growing energy storage demands.LICs effectively balance the high energy density of t... There is an urgent need for lithium-ion capacitors(LICs)that have both high energy and high power densities to meet the continuously growing energy storage demands.LICs effectively balance the high energy density of traditional rechargeable batteries with the superior power density and long life of supercapacitors(SCs).Nevertheless,the development of LICs is still hampered by limited kinetic processes and capacity mismatch between the cathode and anode.Metal-organic frameworks(MOFs)and their derivatives have received significant attention because of their extensive specific surface area,different pore structures and topologies,and customizable functional sites,making them compelling candidate materials for achieving high-performance LICs.MOF-derived carbons,known for their exceptional electronic conductivity and large surface area,provide improved charge storage and rapid ion transport.MOF-derived transition metal oxides contribute to high specific capacities and improved electrochemical stability.Additionally,MOF-derived metal compounds/carbons provide combined effects that increase both the capacitive and Faradaic reactions,leading to a superior overall performance.The review begins with an overview of the fundamental principles of LICs,followed by an exploration of synthesis strategies and ligand selection for MOF-based composite materials.It then analyzes the advantages of original MOFs and their derived materials,such as carbon materials and metal compounds,in enhancing LIC performance.Finally,the review discusses the major challenges faced by MOFs and their derivatives in LIC applications and offers future research directions and recommendations. 展开更多
关键词 Lithium-ion capacitors MOFS Transition metal oxide Energy density Power density
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Effects of Relative Soil Water Content on Antioxidant Enzyme System in Malus sieversii(Lebed.) Roem 被引量:1
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作者 徐佳宁 刘钢 王文军 《Agricultural Science & Technology》 CAS 2016年第6期1281-1284,共4页
By pot experiment under artificially simulated water stress conditions, soluble protein content, MDA content and SOD, POD, CAT and APX activities in Malus sieversfi leaves were determined to reveal the response mechan... By pot experiment under artificially simulated water stress conditions, soluble protein content, MDA content and SOD, POD, CAT and APX activities in Malus sieversfi leaves were determined to reveal the response mechanism of M. sieversii to changes of relative soil water content. According to the results, with the decrease of relative soil water content, MDA content in M. sieversii leaves increased by mem- brane lipid peroxidation. Cells resist water stress-induced membrane lipid peroxidation and clear the increased reactive oxygen species by improving soluble protein content and SOD, POD, CAT and APX activities. However, various enzymes were involved in the response to water stress under different moisture conditions. In addition, the results indicated that M. sieversii had a good adaptability to higher relative soil water contents. 展开更多
关键词 Malus sieversii (Lebed.) Roem. Relative soil water content Membrane lipid peroxidation Antioxidant enzyme system
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Effects of Heavy-ion Beams Irradiation on Survival Rate and Antioxidant Enzymes of Sweet Sorghum Seedlings
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作者 刘智全 谷卫彬 李文建 《Agricultural Science & Technology》 CAS 2012年第11期2257-2260,2268,共5页
[Objective] This study aimed to investigate the effects of heavy-ion beams irradiation on the seed germination potential, survival rate, antioxidant enzyme activi- ties and lipid peroxidation of sweet sorghum. [Method... [Objective] This study aimed to investigate the effects of heavy-ion beams irradiation on the seed germination potential, survival rate, antioxidant enzyme activi- ties and lipid peroxidation of sweet sorghum. [Method] The dry seeds were irradiated by '2(36. heavy ion beams with absorbed doses: 0, 40, 80, 120, 160 and 200 Gy, respectively. Then, the seed germination potential, survival rate, antioxidant enzyme activities and lipid peroxidation of sweet sorghum were measured. [Result] Heavy-ion beams irradiation exhibited different influence on germination potential and survival rates. Germination rate showed a downward trend, but the corresponding survival curve of seedlings was saddle-shaped. The activities of SOD, POD, CAT and ASA- POD changed in different trends as well. The MDA content rose toward increasing irradiation dose, suggesting that high dose of heavy-ion beams irradiation enhanced the damage to membrane of sweet sorghum seedlings. [Conclusion] After being irra- diated, germination potential and survival rates of sweet sorghum were decreased, and antioxidant enzymes activity changed greatly. This study laid the basis for fur- ther work on breeding and improvement of sweet sorghum irradiated by ,^(12)C^(6+) heavy ion beams. 展开更多
关键词 Heavy ion beams IRRADIATION Sweet sorghum Antioxidant enzymes
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Fat poetry:a kingdom for PPARγ 被引量:10
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作者 Silvia I Anghel Walter Wahli 《Cell Research》 SCIE CAS CSCD 2007年第6期486-511,共26页
Adipose tissue is not an inert cell mass contributing only to the storage of fat, but a sophisticated ensemble of cellular components with highly specialized and complex functions. In addition to managing the most imp... Adipose tissue is not an inert cell mass contributing only to the storage of fat, but a sophisticated ensemble of cellular components with highly specialized and complex functions. In addition to managing the most important energy reserve of the body, it secretes a multitude of soluble proteins called adipokines, which have beneficial or, alternatively, deleterious effects on the homeostasis of the whole body. The expression of these adipokines is an integrated response to various signals received from many organs, which depends heavily on the integrity and physiological status of the adipose tissue. One of the main regulators of gene expression in fat is the transcription factor peroxisome proliferatoractivated receptor γ (PPARγ), which is a fatty acid- and eicosanoid-dependent nuclear receptor that plays key roles in the development and maintenance of the adipose tissue. Furthermore, synthetic PPAR7 agonists are therapeutic agents used in the treatment of type 2 diabetes. This review discusses recent knowledge on the link between fat physiology and metabolic diseases, and the roles of PPARγ in this interplay via the regulation of lipid and glucose metabolism. Finally, we assess the putative benefits of targeting this nuclear receptor with still-to-be-identified highly selective PPARγ modulators. 展开更多
关键词 adipose tissue energy homeostasis OBESITY peroxisome proliferator-activated receptor
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Effect of Polyamine Priming on Chilling Tolerance of Lolium perenne during Seed Imbibition 被引量:4
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作者 王应芬 王普昶 +3 位作者 吴佳海 赵丽丽 莫本田 黎俊 《Agricultural Science & Technology》 CAS 2012年第9期1859-1863,1869,共6页
[Objective] This study aimed to investigate the effect of potyamine priming on physiological and biochemical variations of Lolium perenne embryos and seed germination. [Method] With annual Lolium perenne (Diamond T a... [Objective] This study aimed to investigate the effect of potyamine priming on physiological and biochemical variations of Lolium perenne embryos and seed germination. [Method] With annual Lolium perenne (Diamond T and Grazing-8000) as experimental materials, after priming with 0.5 mmol/L putrescine (Put), spermidine (Spd) and spermine (Spm) for 24 h and chilling imbibition at 5 ℃ for 12, 24, 36 and 48 h, the effect of Put, Spd and Spm priming on chilling tolerance and germination ability of annual Lolium perenne seeds during imbibition was investigated. [Result] Put, Spd and Spm priming improved the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) and content of soluble protein content under low temperature stress, significantly in-creased the germination rate, and shortened the average germination duration. After chilling imbibition for 48 h, compared with the control, the average germination rate of annual Lolium perenne seeds was improved by 15.5% and 12.0% after Put, Spd and Spm priming, and the average germination duration was shortened by 1.21 and 1.14 d. During seed imbibition, the chilling tolerance of Grazing-8000 was stronger than that of Diamond T. Overall, Put, Spd and Spm treatment could increase the chilling tolerance of annual Lolium perenne seeds during imbibition, and improve the germination ability of seeds under low temperature stress. [Conclusion] Results of this study provided theoretical basis for the application of seed priming technology in the production of annual ryegrass. 展开更多
关键词 Polyamines Annual Lofium perenne Chilling tolerance Seed imbibition Antioxidant enzymes
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Response of enzymatic and non-enzymatic antioxidant defense systems of Polygonum hydropiper to Mn stress 被引量:2
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作者 杨贤均 邓冬梅 +1 位作者 刘可慧 于方明 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第4期793-797,共5页
The response of enzyme and non-enzymatic antioxidants of Mn hyperaccumuator, Polygonum hydropiper (P. hydropiper), to Mn stress was studied using hydroponics culture experiments to explore the mechanism of Mn tolera... The response of enzyme and non-enzymatic antioxidants of Mn hyperaccumuator, Polygonum hydropiper (P. hydropiper), to Mn stress was studied using hydroponics culture experiments to explore the mechanism of Mn tolerance in this species. Results showed that both chlorophyll and carotenoid contents significantly (p〈0.05) decreased with increasing Mn treatment levels (0, 0.5, 1, 2, 4, and 8 mg/L) in hydroponics. The concentrations of malondialdehyde (MDA) and hydrogen peroxide (H202) in the root and shoot of P hydropiper were accumulated under Mn stress. Meanwhile, the anti-oxidative functions of several important enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) in plants were stimulated by Mn spike in leaves and roots, especially at low Mn stress; while sulfhydryl group (--SH) and glutathion (GSH) were likely involved in Mn detoxification ofP. hydropiper under high Mn stress. 展开更多
关键词 Polygonum hydropiper HYPERACCUMULATION enzymatic antioxidative defense non-enzymatic antioxidative defense
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Analysis of irrationality of coal susceptibility to spontaneous combustion determination method with fluid oxygen adsorption
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作者 何启林 《Journal of Coal Science & Engineering(China)》 2008年第4期554-557,共4页
Based on experiment results and theoretical analysis,pointed out that the method of coal susceptibility to spontaneous combustion determination with fluid oxygen adsorption can not present the essence of coal oxidatio... Based on experiment results and theoretical analysis,pointed out that the method of coal susceptibility to spontaneous combustion determination with fluid oxygen adsorption can not present the essence of coal oxidation process and oxidation reaction. The method is incorrect,paying attention at one aspect and ignoring the rest.The method is not reasonable for coal susceptibility to spontaneous combustion determination.Sus- ceptibility to spontaneous combustion of coal reflects chemical property of coal oxidation with oxygen absorption and heat release at low temperature.Coal's susceptibility to spon- taneous combustion is mainly decided by the number of molecules with reaction activation energy and activation molecule production rate at certain temperature.Therefore,index of susceptibility to spontaneous combustion should adopt accumulative value or trend of heat release or oxygen adsorption during oxidation process. 展开更多
关键词 susceptibility to spontaneous combustion method of fluid oxygen adsorption coal mine safety
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Fuzzy Neural Network Model of 4-CBA Concentration for Industrial Purified Terephthalic Acid Oxidation Process 被引量:7
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作者 刘瑞兰 苏宏业 +3 位作者 牟盛静 贾涛 陈渭泉 褚健 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2004年第2期234-239,共6页
A fuzzy neural network (FNN) model is developed to predict the 4-CBA concentration of the oxidation unit in purified terephthalic acid process. Several technologies are used to deal with the process data before modeli... A fuzzy neural network (FNN) model is developed to predict the 4-CBA concentration of the oxidation unit in purified terephthalic acid process. Several technologies are used to deal with the process data before modeling.First,a set of preliminary input variables is selected according to prior knowledge and experience. Secondly,a method based on the maximum correlation coefficient is proposed to detect the dead time between the process variables and response variables. Finally, the fuzzy curve method is used to reduce the unimportant input variables.The simulation results based on industrial data show that the relative error range of the FNN model is narrower than that of the American Oil Company (AMOCO) model. Furthermore, the FNN model can predict the trend of the 4-CBA concentration more accurately. 展开更多
关键词 purified terephthalic acid 4-carboxybenzaldchydc fuzzy neural network soft sensor input variables selection fuzzy curve dead time detection
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Elementary Flux Mode Analysis for Optimized Ethanol Yield in Anaerobic Fermentation of Glucose with Saccharomyces cerevisiae 被引量:1
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作者 许晓菁 曹利民 陈询 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2008年第1期135-142,共8页
Elementary flux mode (EFM) analysis was used in the metabolic analysis of central carbon metabolism in Saccharomyces cerevisiae based on constructed cellular network. Calculated from the metabolic model, the ethanol... Elementary flux mode (EFM) analysis was used in the metabolic analysis of central carbon metabolism in Saccharomyces cerevisiae based on constructed cellular network. Calculated from the metabolic model, the ethanol-producing pathway No. 37 furthest converts the substrate into ethanol among the 78 elementary flux modes. The in silico metabolic phenotypes predicted based on this analysis fit well with the fermentation performance of the engineered strains, KAM3 and KAMll, which confirmed that EFM analysis is valid to direct the construction of Saccharomyces cerevisiae engineered strains, to increase the ethanol yield. 展开更多
关键词 elementary flux mode analysis metabolic phenotype redox balance Saccharomyces cerevisiae ETHANOL
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Feasibility of using lysozyme to reduce excess sludge in activated sludge process 被引量:3
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作者 宋勇 施周 +1 位作者 陈世洋 罗璐 《Journal of Central South University》 SCIE EI CAS 2013年第9期2472-2477,共6页
Lysozyme reaction was developed as a novel technique for minimizing the amount of excess sludge in the sequential batch reactor(SBR).In the present work,excess sludge taken from a SBR system was treated by lysozyme re... Lysozyme reaction was developed as a novel technique for minimizing the amount of excess sludge in the sequential batch reactor(SBR).In the present work,excess sludge taken from a SBR system was treated by lysozyme reaction and then returned to the reactor.The quality of the effluent water and characteristics of the activated sludge in the SBR were analyzed to determine the effectiveness of the reduction process.The results show that excess sludge production could be reduced to almost 100%in the first30 d of operation and could be reduced to further by 40%in the succeeding 20 d or so.In these time periods,the average removal efficiencies of the chemical oxygen demand and total nitrogen are 87.38%and 52.78%,respectively,whereas the average total phosphorous in the effluent is nearly 17.18%greater than that of the effluent of the reference system.After 50 d of operation,the sludge floc size is in the range of 20 to 80μm,which was smaller than the size prior to the start of the hydrolysis and the ratio of mixed liquor volatile suspended solids/mixed liquor suspended solids increases from 86%to 90%. 展开更多
关键词 cell lysis sludge minimization sequential batch reactor LYSOZYME ATP
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Antioxidant system responses in two co-occurring green-tide algae under stress conditions
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作者 王影 赵新宇 唐学玺 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2016年第1期102-108,共7页
Green tides have occurred every year from 2007 to 2014 in the Yellow Sea. Ulva prolifera (Mtiller) J. Agardh has been identified as the bloom-forming alga, co-occurring with U. intestinalis. We observed distinct str... Green tides have occurred every year from 2007 to 2014 in the Yellow Sea. Ulva prolifera (Mtiller) J. Agardh has been identified as the bloom-forming alga, co-occurring with U. intestinalis. We observed distinct strategies for both algal species during green tides. U.prolifera exhibited a high abundance initially and then decreased dramatically, while U. intestinalis persisted throughout. The antioxidant system responses of these two macroalgae were compared in the late phase of a green tide (in-situ) and after laboratory acclimation. Lipid peroxidation and antioxidant system responses differed significantly between the two. Malondialdehyde and hydrogen peroxide contents increased significantly in-situ in U. prolifera, but not in U. intestinalis. In U. prolifera, we observed a significant decrease in total antioxidant ability (T-AOC), antioxidant enzymes (SOD and Apx), and non-enzyme antioxidants (GSH and AsA) in-situ. U. intestinalis showed the same pattern of T-AOC and SOD, but its Gpx, Apx, and GSH responses did not differ significantly. The results suggest that U. prolifera was more susceptible than U. intestinalis to the harsh environmental changes during the late phase of a Yellow Sea green tide. The boom and bust strategy exhibited by U. prolifera and the persistence of U. intestinalis can be explained by differences in enzyme activity and antioxidant systems. 展开更多
关键词 antioxidant system Yellow Sea green tide U. prolifera U. intestinalis algal bloom
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Venting Design for Di-tert-butyl Peroxide Runaway Reaction Based on Accelerating Rate Calorimeter Test 被引量:6
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作者 魏彤彤 蒋慧灵 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第4期710-714,共5页
In order to design the relief system size of di-tert-butyl peroxide(DTBP) storage tanks,the runaway re-action of DTBP was simulated by accelerating rate calorimeter(ARC).The results indicated that under adiabatic cond... In order to design the relief system size of di-tert-butyl peroxide(DTBP) storage tanks,the runaway re-action of DTBP was simulated by accelerating rate calorimeter(ARC).The results indicated that under adiabatic conditions the initial exothermic temperature was 102.6 ℃,the maximum self-heating rate was 3.095×107 ℃·min-1,the maximum self-heating temperature was 375.9 ℃,and the pressure produced by unit mass was 4.512 MPa·g-1.Judged by ARC test,the emergency relief system for DTBP was a hybrid system.Based on Design Institute for Emergency Relief System(DIERS) method,the releasing mass flow rate W was determined by Leung methods,and the mass velocity G was calculated by two modified Omega methods.The two relief sizes calculated by monograph Omega method and arithmetic Omega method are close,with only 0.63% relative error.The monograph Omega method is more convenient to apply. 展开更多
关键词 di-tert-butyl peroxide accelerating rate calorimeter runaway reaction venting size
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A review of chemical absorption of carbon dioxide for biogas upgrading 被引量:5
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作者 Fouad R.H. Abdeen Maizirwan Mel +2 位作者 Mohammed Saedi Jami Sany Izan Ihsan Ahmad Faris Ismail 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第6期693-702,共10页
Significant attention has been given to biogas production, purification and upgrading as a renewable and clean fuel supplement. Biogas is a product of an anaerobic digestion process comprising methane, carbon dioxide,... Significant attention has been given to biogas production, purification and upgrading as a renewable and clean fuel supplement. Biogas is a product of an anaerobic digestion process comprising methane, carbon dioxide,and trace amounts of other gases. Biogas purification removes trace gases in biogas for safe utilisation. Biogas upgrading produces methane-rich biogas by removing bulk carbon dioxide from the gas mixture. Several carbon dioxide removal techniques can be applied for biogas upgrading. However, chemical absorption of carbon dioxide for biogas upgrading is of special significance due to its operation at ambient or near ambient temperature and pressure, thus reducing energy consumption. This paper reviews the chemical absorption of carbon dioxide using amine scrubbing, caustic solvent scrubbing, and amino acid salt solution scrubbing. Each of these techniques for biogas upgrading is discussed. The paper concludes that an optimised implementation of the chemical absorption techniques for biogas upgrading requires further research. 展开更多
关键词 Biogas upgrading BiofuelCO2 captureAbsorptionAmine scrubbingCaustic scrubbing
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Kinetics of Treated Domestic Sewage Disinfection through Catalytic Oxidation with H2O2
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作者 Gean Delise Leal Pasquali Vargas Deisi Spricigo Humberto Jorge Joss Regina de Fatima Peralta Muniz Moreira 《Journal of Chemistry and Chemical Engineering》 2011年第11期995-1001,共7页
The inactivation of bacterial cells through catalyzed oxidation using hydrogen peroxide as the primary oxidant agent is dependent on a series of factors, such as the concentration of the catalyst, the rate of hydroxyl... The inactivation of bacterial cells through catalyzed oxidation using hydrogen peroxide as the primary oxidant agent is dependent on a series of factors, such as the concentration of the catalyst, the rate of hydroxyl radical formation in the controlled decomposition of the oxidant agent, and the concentration and toxicity of hydrogen peroxide. The objective of this study was to develop a mathematical model able to predict the kinetics of the inactivation Escherichia coli and total coliforms cells present in treated domestic sewage through catalytic peroxidation. The catalyst used was iron oxide supported on mineral coal (called CP), and the effects of the operational conditions, including hydrogen peroxide concentration and dosage of catalyst, were evaluated. The results showed that the disinfection kinetics of the treated domestic sewage is dependent on the concentrations of hydrogen peroxide and catalyst dosage. The kinetic model was shown to be able to predict the behavior of the inactivation kinetics of the bacterium Escherichia coli ATCC-25922 when different concentrations of hydrogen peroxide (75 and 100 mg·L^-1) were used, regardless of the catalyst dosage. 展开更多
关键词 DISINFECTION domestic sewage KINETICS catalytic oxidation Escherichia coli total coliforms
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Studies on the Effects on Growth and Antioxidant Responses of Two Marine Microalgal Species to Uniconazole 被引量:3
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作者 MEI Xueqiao ZHENG Kang +1 位作者 WANG Lingdong LI Yantuan 《Journal of Ocean University of China》 SCIE CAS 2014年第5期877-882,共6页
Uniconazole, as a plant growth retardant, can enhance stress tolerance in plants, possibly because of improved antioxidation defense mechanisms with higher activities of superoxide dismutase(SOD) and peroxidase(POD) e... Uniconazole, as a plant growth retardant, can enhance stress tolerance in plants, possibly because of improved antioxidation defense mechanisms with higher activities of superoxide dismutase(SOD) and peroxidase(POD) enzymes that retard lipid peroxidation and membrane deterioration. These years much attention has been focused on the responses of antioxidant system in plants to uniconazole stress, but such studies on aquatic organism are very few. Moreover, no information is available on growth and antioxidant response in marine microalgae to uniconazole. In this paper, the growth and antioxidant responses of two marine microalgal species, Platymonas helgolandica and Pavlova viridis, at six uniconazole concentrations(0-15 mg L-1) were investigated. The results demonstrated that 3 mg L-1 uniconazole could increase significantly chlorophyll a and carbohydrate contents of P. helgolandica(P < 0.05). Higher concentrations(≥12 mg L-1) of uniconazole could inhibit significantly the growth, dry weight, chlorophyll-a and carbohydrate contents of P. helgolandica and P. viridis(P < 0.05). Uniconazole caused a significant increase in lipid peroxidation production(MDA) at higher concentrations(≥ 9 mg L-1). The activities of antioxidant enzymes, superoxide dismutase(SOD) and catalase(CAT) were enhanced remarkably at low concentrations of uniconazole. However, significant reduction of SOD and CAT activities was observed at higher concentrations of uniconazole. 展开更多
关键词 catalase(CAT) lipid peroxidation Platymonas helgolandica Pavlova viridis superoxide dismutase(SOD) UNICONAZOLE
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Preparation of polysaccharides in different molecular weights from Ulva pertusa Kjellm (Chorophyta)
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作者 于鹏展 张全斌 +2 位作者 张虹 牛锡珍 李智恩 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2004年第4期381-385,共5页
As molecular weight controls the biological activities of polysaccharides, screening the optimal molecular weight of polysaccharides is important in drug research and application. In this study, hydrogen peroxide was ... As molecular weight controls the biological activities of polysaccharides, screening the optimal molecular weight of polysaccharides is important in drug research and application. In this study, hydrogen peroxide was employed as oxidant, and temperature, reaction time, and concentration of polysaccharides and hydrogen peroxide were examined for their effects on the preparation of polysaccharides in different molecular weights from Ulva pertusa. Our experiment suggested that the optimal degradation concentrations for polysac-charides and hydrogen peroxide were 2.5% (w/v) and 8.0% (v/v), respectively. The range of degradation measured by relative viscosity was mainly controlled by temperature and time. Results revealed that 35℃ was the optimal temperature for obtaining low-degradation samples, and 50℃ was the most favorable temperature to accelerate the reaction to yield highly-degraded samples. Four samples in different molecular weights A, B, C and D were finally prepared. The controllability was evaluated by the relative standard deviation (RSD) of relative viscosity, and the peak molecular weights and the polydispersity indexes (Mw/Mn) of molecular weights were measured by high performance gel permeation chromatography (HPGPC). 展开更多
关键词 Ulva pertusa POLYSACCHARIDES hydrogen peroxide controllable degradation molecular weight
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Physiological and Biochemical Changes Induced by PRD Irrigation in Four Olive Varieties
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作者 Badia Aganchich Said Wahbi Cherkaoui El Modafar 《Journal of Agricultural Science and Technology(B)》 2013年第5期344-357,共14页
The present study was conducted to evaluate the effects of partial root-zone drying (PRD) irrigation technique on stomatal conductance (gs), leaf water potential (qJpd), leaf relative water content (RWC), vege... The present study was conducted to evaluate the effects of partial root-zone drying (PRD) irrigation technique on stomatal conductance (gs), leaf water potential (qJpd), leaf relative water content (RWC), vegetative growth, fruit quality and enzymatic antioxidants of young plants of four Olea europaea L. varieties (Picholine Marocaine, Haouzia, Picholine Languedoc and Manzanilla) grown under arid conditions in Southern Morocco. In this irrigation strategy, a split-root technique was used to divide the root system of the plants in two parts. Two water regimes were used: (1) control, with both root compartments well watered; (2) PRD, with one compartment irrigated (50% of the control), the other compartment was kept dry switching every 10 days. For all olive varieties studied, gs and the shoot length of the plants subjected to PRD decreased, whereas, Woo and RWC remained higher. The effect of PRD was similar among the four olive varieties, with their stomata closing in response to the water deficit before any significant changes in leaf water status were detectable. At the agronomic level, the benefits of PRD on olive were expressed by an earlier maturity and by higher values of olive fruit weight and dimensions, especially, in Manzanilla, which produced a fruit reaching 7.1 g and 2.6 cm, respectively. The enzymatic activities of soluble peroxidases (POX), insoluble peroxidases (POXins), polyphenoloxidase (PPO) and superoxide dismutase (SOD) were up-regulated under PRD. Picholine Marocaine and Haouzia showed higher enzymatic activities revealing that in these two varieties, PRD had possibly induced oxidative stress, which resulted in an up-regulation of the antioxidant activities of POXins, POX, PPO and SOD under water deficit. 展开更多
关键词 OLIVE water deficit PRD irrigation water relations vegetative growth antioxidant enzymes
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Blood micronutrient, oxidative stress, and viral load in patients with chronic hepatitis C 被引量:6
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作者 Wang-Sheng Ko Chih-Hung Guo +5 位作者 Maw-Sheng Yeh Li-Yun Lin Guoo-Shyng W. Hsu Pei-Chung Chen Mei-Ching Luo Chia-Yeh Lin 《World Journal of Gastroenterology》 SCIE CAS CSCD 2005年第30期4697-4702,共6页
AIM: To assess the extent of micronutrient and oxidative stress in blood and to examine their linkages with viral loads in chronic hepatitis C patients.METHODS: Hepatitis C virus (HCV)-RNA levels were quantified in th... AIM: To assess the extent of micronutrient and oxidative stress in blood and to examine their linkages with viral loads in chronic hepatitis C patients.METHODS: Hepatitis C virus (HCV)-RNA levels were quantified in the serum from 37 previously untreated patients with chronic hepatitis C. The plasma and erythrocyte micronutrients (zinc, selenium, copper, and iron) were estimated, and malondialdehyde (MDA)contents were determined as a marker to detect oxidative stress. Antioxidant enzymes, superoxide dismutase (SOD),glutathione peroxidase (GPX) and glutathione reductase (GR) activities in blood were also measured. The control group contained 31 healthy volunteers.RESULTS: The contents of zinc (Zn), and selenium (Se)in plasma and erythrocytes were significantly lower in hepatitis C patients than in the controls. On the contrary,copper (Cu) levels were significantly higher. Furthermore,plasma and erythrocyte MDA levels, and the SOD and GR activities in erythrocytes significantly increased in hepatitis C patients compared to the controls. However, the plasma GPX activity in patients was markedly lower. Plasma Se (r= -0.730, P<0.05), Cu (r = 0.635), and GPX (r = -0.675)demonstrated correlations with HCV-RNA loads. Significant correlation coefficients were also observed between HCV-RNA levels and erythrocyte Zn (r = -0.403), Se (r = -0.544), Cu (r = 0.701) and MDA (r = 0.629) and GR (r = 0.441).CONCLUSION: The levels of Zn, Se, Cu, and oxidative stress (MDA), as well as related anti-oxidative enzymes (GR and GPX) in blood have important impact on the viral factors in chronic hepatitis C. The distribution of these parameters might be significant biomarkers for HCV. 展开更多
关键词 MICRONUTRIENT Oxidative stress Viral load Plasma and erythrocytes Hepatitis C
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Variation of the Content of Ethyl Esters in Extra Virgin Olive Oils during Their Shelf Life
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作者 Maria A. Grompone Nicolas Callejas +3 位作者 Natalia Martinez Camila Feller Miguel Amarillo Bruno A. Irigaray 《Journal of Food Science and Engineering》 2016年第1期21-25,共5页
Fatty acids' ethyl and methyl esters are not natural components of edible vegetable oils and therefore should not be present in virgin olive oils. Among the quality requirements for extra virgin olive oils, the Inter... Fatty acids' ethyl and methyl esters are not natural components of edible vegetable oils and therefore should not be present in virgin olive oils. Among the quality requirements for extra virgin olive oils, the International Olive Council (IOC) Norm, 2015 review, set limits for the ethyl ester content at ≤ 435 ppm for the 2014/2015 and 2015/2016 harvests and at ≤ 30 ppm for the 2016/2017 harvest. The purpose of this paper is to: (a) determine the alkyl ester content in two extra virgin olive oils (of the Arbequina and Coratina varieties) as parameters of quality at the moment of their elaboration and to assess the length of their shelf life, over a 12 month period at room temperature; (b) determine extra virgin olive oils' free alcohols content as these may esterify due to the free fatty acids present during storage. After 6 months of storage, the Arbequina oil's ethyl ester content was 32 ppm, and the Coratina's was 46 ppm. As a result, the shelf life for both was only about half a year (labeling usually indicates it must be consumed "before 1 year"). However, parameters related to oxidation (peroxide index, K 232, K 270 and AK) remained within the limits set by the International Olive Council (IOC) throughout the year. In conclusion: ethyl ester content is a very fine parameter for assessing the quality of extra virgin in an olive oil and determining the length of its shelf life. 展开更多
关键词 Alkyl esters free alcohols olive oil shelf life
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