A comparative study of conventional and supercritical fluid extraction methods for the recovery of secondary metabolites from <Emphasis Type="Italic">Syzygium campanulatum</Emphasis> Korth

Syzygium campanulatum Korth is a plant, which is a rich source of secondary metabolites (especially flavanones, chalcone, and triterpenoids). In our present study, three conventional solvent extraction (CSE) techniques and supercritical fluid extraction (SFE) techniques were performed to achieve a maximum recovery of two flavanones, chalcone, and two triterpenoids from S. campanulatum leaves. Furthermore, a Box-Behnken design was constructed for the SFE technique using pressure, temperature, and particle size as independent variables, and yields of crude extract, individual and total secondary metabolites as the dependent variables. In the CSE procedure, twenty extracts were produced using ten different solvents and three techniques (maceration, soxhletion, and reflux). An enriched extract of five secondary metabolites was collected using n-hexane:methanol (1:1) soxhletion. Using food-grade ethanol as a modifier, the SFE methods produced a higher recovery (25.5%?84.9%) of selected secondary metabolites as compared to the CSE techniques (0.92%?66.00%).     

巴基斯坦高等学校设置制度:缘起、程序及标准

在巴基斯坦现行高等教育行政管理机构及组织体系下,巴基斯坦高等学校设置制度的构建缘起、设置程序及标准具有一定的特色.研究发现,巴基斯坦高等学校设置程序围绕申请、审核、考察、赋权等四个环节进行,具备系统的设置标准,涵盖师资队伍建设、设备场地规范、经费使用、管理若干方面.巴基斯坦高等学校设置制度较为完备,符合本国国情,利益主体均衡,标准刚柔相济,但也存在重硬件、轻科研,未能为高等教育国际化纵深发展预留对接平台,以及“一刀切”色彩过重等问题.     

试论多媒体新闻

本文着重对多媒体新闻的编辑及传播进行探讨,提出嵌入式的多媒体新闻整合方式等。     

Computer Simulations Improve University Instructional Laboratories

Laboratory classes are commonplace and essential in biology departments but can sometimes be cumbersome, unreliable, and a drain on time and resources. As university intakes increase, pressure on budgets and staff time can often lead to reduction in practical class provision. Frequently, the ability to use laboratory equipment, mix solutions, and manipulate test animals are essential learning outcomes, and “wet” laboratory classes are thus appropriate. In others, however, interpretation and manipulation of the data are the primary learning outcomes, and here, computer-based simulations can provide a cheaper, easier, and less time- and labor-intensive alternative. We report the evaluation of two computer-based simulations of practical exercises: the first in chromosome analysis, the second in bioinformatics. Simulations can provide significant time savings to students (by a factor of four in our first case study) without affecting learning, as measured by performance in assessment. Moreover, under certain circumstances, performance can be improved by the use of simulations (by 7% in our second case study). We concluded that the introduction of these simulations can significantly enhance student learning where consideration of the learning outcomes indicates that it might be appropriate. In addition, they can offer significant benefits to teaching staff.     

Use of glycated hemoglobin (HbA<Subscript>1C</Subscript>) and impaired glucose tolerance in the screening of undiagnosed diabetes in the Malaysian population

Although HbA_1C is widely accepted as a useful index of mean blood glucose in type 2 diabetic patients its usefulness as screening test for diabetes has been controversial. The present study was undertaken to determine whether the level of HbA_1C predicted diabetes in a prediabetic group of subjects. Plasma lipids, oral glucose tolerance, HbA_1C was determined in 90 normal control subjects, 57 offspring of one type 2 diabetes mellitus parent and 11 diagnosed type 2 diabetes mellitus individuals. The mean age of participants was 44.5 yrs (not significantly different amongst the three groups) and the mean body mass index was 26.8 (not significantly different amongst the three groups). Two hours after a 75 g glucose challenge, the offspring had a significantly higher plasma glucose level (mean = 7.1 mmol/L, p value = 0.002) than the normals. Similarly the HbA_1C values were higher in the offspring than in the normals (mean = 5.78%, p value = 0.016). Besides the significantly higher values for oral glucose tolerance test and HbA_1C, the diabetics also were significantly higher for triglycerides (mean = 2.25mmol/L), total cholesterol (mean = 6.24mmol/L) and systolic blood pressure (mean = 138.45mm Hg) than the offspring (P value = 0.031, 0.006, 0.010) and the normals (P value = 0.026, 0.018, 0.002) respectively. The mean values of diastolic blood pressure, LDL cholesterol and HDL cholesterol were not significantly different amongst the three groups.     

The Privatization of the Internet's Backbone Network

Scholars have neglected the privatization of the Internet's backbone network, despite the obvious significance of the U.S. government turning control of a powerful new communication technology over to the private sector. This article analyzes the transition from a government-sponsored backbone network to multiple commercially owned backbone networks. The authors also analyze the implications of the privatization on the Internet's governance, competition, and performance.     

“Split Screens” and “Spin Rooms”: Debate Modality,Post-Debate Coverage,and the New Videomalaise

This experimental research examines how different presentation modalities in presidential debates and post-debate spin influence the ability to form evaluations about candidates' character, shape perceptions of their incivility, and alter judgments of political trust and news credibility. Results indicate that these experimental factors work together to encourage character judgments, diminish perceptions of candidate civility, and reduce levels of trust in government. In addition, political talk conditioned experimental effects on perceptions of news credibility, with the adverse effects of split screen presentations concentrated among those who talked about the debate. Thus, the negative effects of “in your face” politics conveyed by the “split-screen” modality appear to be most pronounced among those primed to think about performance and those attuned to politics through interpersonal talk.