Analytical evaluation of different carbon sources and growth stimulators on the biomass and lipid production of Chlorella vulgaris – Implications for biofuels

The key challenges in lipid production from marine microalgae include the selection of appropriate strain, optimization of the culture conditions and enhancement of biolipid yield. This study is aimed at evaluating the optimal harvest time and effect of chlorella growth factor (CGF) extract, carbon sources and phytohormones on the biomass and lipid production in Chlorella vulgaris. CGF, extracted using hot water from Chlorella has been reported to possess various medicinal properties. However, in the present study, for the first time in C. vulgaris, CGF was found as a best growth stimulator by enhancing the biomass level (1.208 kg m⁻³) significantly on day 5. Gibberellin and citrate augmented the biomass by 0.935 kg m⁻³ and 1.025 kg m⁻³. Combination of CGF and phytohormones were more effective than CGF and carbon sources. Analysis of fatty acid methyl esters indicated that the ratio of saturated to unsaturated fatty acids is higher in cytokinin, abscisic acid and CGF, and are also rich in short chain carbon atoms, ideal criteria for biodiesel. Nitrogen starvation favoured synthesis of more unsaturated fatty acids than saturated. This study shows that CGF enhances the biomass and lipid significantly and thus can be used for large scale biomass production.     

基于SFA的工业用水节水潜力分析

构建基于随机前沿生产函数的工业用水节水潜力计算模型,认为节水潜力是技术充分有效、不存在任何效率损失情形下的工业最小用水量与实际用水量的差,是用水户在现有的生产技术、用水结构、水资源管理制度、用水意识、投资能力等因素综合作用下能达到的目标。以徐州市为例进行计算分析,指出徐州工业技术效率呈现上升趋势,总体节水潜力为当前用水量的22.52%。     

中国人为主导的铝循环分析(英文)

采用铝产品生命周期的铝流程图进行中国人为主导的铝循环分析。人为主导的铝循环主要包括4个阶段:氧化铝及电解铝的生产、铝制品的加工和制造、铝制品的使用和报废铝制品的回收。采用加权平均法确定我国铝制品的平均使用寿命。基于中国2003-2007年的铝循环分析,发现了铝工业发生的一些变化。氧化铝生产阶段的原料自给率从95.42%下降到55.50%,原铝生产阶段的原料自给率从52.45%上升到79.25%,但整个铝工业的原料自给率基本维持在50%左右。在2007年铝工业中,国内自产废铝和进口废铝的使用比例分别占总原料的5.38%和9.40%。在此阶段,净进口各类含铝资源和铝产品生命周期中铝的损失量都是上升的,同时,社会蓄积量中铝的存量及铝的循环量都是增加的。提出了改善铝循环的对策、建议以及中国铝工业的进出口政策和降低铝产品生命周期铝损失量的措施。     

Effect of slaughter season on fatty acid composition, conjugated linoleic acid isomers and nutritional value of intramuscular fat in Barrosã-PDO veal

This paper describes the influence of slaughter season on lipid content, fatty acid composition, conjugated linoleic acid (CLA) isomeric profile and nutritional value of fat in Barrosã veal from calves reared according to the specifications of the Protected Designation of Origin (PDO). Barrosã purebred calves (n = 27) were raised in a traditional production system and slaughtered in early autumn (October) and late spring (June). Barrosã-PDO veal only presented seasonal differences in the levels of some minor fatty acids and CLA isomers, as well as in the PUFA/SFA ratio. Based on the analysed grass intake indicators, it was shown that veal-PDO has similar values to pasture-fed cattle for both slaughter seasons. From a human nutrition perspective, intramuscular fat in Barrosã-PDO veal has a high nutritional value throughout the year, since CLA contents and the percentages of the c9,t11 isomer are relatively high, and the n − 6/n − 3 ratios are within the recommended values for the human diet.     

复合流动分析法测定环境水样中的总磷

应用FSIV型流动分析仪,采用在线紫外／过硫酸盐消解、复合流动分析法对环境水样中的总磷进行测定。通过试验,确定了最佳测定条件,对方法的灵敏度、准确度和精密度进行了测试,测定的方法检出限为0．006mg／L,相对标准偏差（P,3D）为1．2％～6．5％,回收率为9;3．5％～107％。该方法测定结果与标准法测定结果无显著性差异,可以用于测定环境水样中的总磷。     

基于电压源换流器的高压直流输电系统多尺度暂态建模与仿真研究（英文）

针对基于电压源转换器的高压直流(high voltage direct current based voltage source converter,VSC-HVDC)输电系统,该文提出电磁暂态–机电暂态多尺度建模方法并验证多尺度仿真算法的准确、快速和灵活性。该模型采用频移分析(shifted-frequency analysis,SFA)等多尺度建模方法。首先推导移频(shifted frequency,SF)域和dq域之间的解析变换关系,并提出用于系统特性分析的VSC移频多尺度模型;其次,选择性插入π模型获得直流输电线的多尺度暂态模型;最后,通过调整仿真参数,如仿真时间步长和移动频率,使得建立的模型能够灵活仿真具有多个时间尺度和不同网络位置的各种暂态。采用两端和五端VSC-HVDC输电系统作为算例,仿真结果对比表明,提出的模型和算法能够精确模拟高频暂态,快速仿真慢变化暂态,降低计算成本。此外,多尺度模型还可提高VSC-HVDC输电系统电磁–机电暂态混合仿真的灵活性。     

调和油生产与调和数学模型的建立

根据世界卫生组织与联合国粮农组织为发展中国家提供的ＳＦＡ∶ＭＵＦＡ∶ＰＵＦＡ＝１∶１∶１的建议,完成玉米调和油的调制过程,并建立调和数学模型。经使用,调和模型合理,可用于各种调和油的研制过程中     

Fatty acid composition, conjugated linoleic acid isomers and cholesterol in beef from crossbred bullocks intensively produced and from Alentejana purebred bullocks reared according to Carnalentejana-PDO specifications

The purpose of this study was to characterise and compare the nutritional value of Portuguese Carnalentejana-PDO beef, obtained from Alentejana purebred bullocks reared in a semi-extensive system, with the meat from Alentejana×Charolais crossbred bullocks produced in a conventional intensive concentrate-based system. In addition, seasonal changes in Carnalentejana-PDO beef quality were assessed, by analysing meat samples from animals slaughtered in early autumn and late spring. The results showed that beef-PDO has different intramuscular fat characteristics in comparison with meat from crossbred bullocks fed intensively with concentrate. However, the finishing period of Alentejana purebred bullocks with concentrate seems to attenuate most of the typical grass-fed characteristics of meat fat. Nevertheless, from a human nutrition perspective, Carnalentejana-PDO beef seems to be healthier than that from intensively reared animals since it has a lower n-6/n-3 ratio, although always above the recommended guidelines for human diet, and higher proportions of c9,t11 conjugated linoleic acid (CLA) isomer and total CLA relative to saturated fatty acids plus total cholesterol (CLA/SFA+CHR). Furthermore, no seasonal variation in the nutritional quality of beef-PDO was apparent. Taken together, the data indicate that Carnalentejana-PDO beef is of greater nutritional value than intensively produced beef from crossbred bullocks throughout the year.     

Factors influencing proportion and composition of CLA in beef

Bovine meat is criticised for the bad nutritional image of its lipids and fatty acids. However, with dairy products, beef is the major source of conjugated linoleic acid (CLA) which could have several human health benefits. The present study compared, from data of five nutritional experiments on bovine animals performed by the laboratory, the impact of factors linked to the animals (breed, age, sex, type of muscle) and to feeding conditions (basal diet, lipid supplements) on the CLA proportion and composition in muscles. Among these factors, linseed supplementation was an efficient way to increase CLA proportion in beef (+22% to +36%) but was highly modulated by the nature of the basal diet, and by intrinsic factors (breed, age/sex, type of muscle) since these ones could modulate CLA proportion in beef from 24% to 47%. Moreover, these factors modified also the proportion of cis,trans-CLA, related to cis,cis- and trans,trans-isomers. Specific biological properties of these latter isomers should be determine to understand the consequences of intramuscular CLA isomer variations for the health of consumers.