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71.
Abdul Hakeem Memon Mohammad Shahrul Ridzuan Hamil Madeeha Laghari Fahim Rithwan Salman Zhari Mohammed Ali Ahmed Saeed Zhari Ismail Amin Malik Shah Abdul Majid 《Journal of Zhejiang University. Science. B》2016,17(9):683-691
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%). 相似文献
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Mulberry longicorn beetle, Apriona germari, has been reported to produce two endo-β-l,4-glucanases or AgEGases (accession Nos. Q6SS52 and Q5XQD1). AgEGase sequence contains catalytic motif (amino acid residues 37~48), which is the characteristic of family Glycohydrolase 45 and is identified as the substrate binding site. The application of bioinformatics approaches includes sequence analysis, structural modeling and inhibitor docking to relate the structure and function of AgEGases.We have dissected the sequence and structure of AgEGase catalytic motif and compared it with crystal structure of Humicola insolens endoglucanases Ⅴ. The results show an involvement of sulfur containing amino acid residues in the active site of the enzyme. Cys residues and position of disulfide bonds are highly conserved between the two structures of endoglucanases of A.germari. Surface calculation of AgEGase structure in the absence of Cys residues reveals greater accessibility of the catalytic site to the substrate involving Asp42, a highly conserved residue. For the inhibition study, tannin-based structure was docked into the catalytic site of AgEGase using ArgusLab 4.0 and it resulted in a stable complex formation. It is suggested that the inhibition could occur through formation of a stable transition state analog-enzyme complex with the tannin-based inhibitor, as observed with other insect cellulases in our laboratory. 相似文献
74.
The educational history of the Sultanate of Oman has undergone rapid development. In 1970, there were three primary schools. Today, there is universal education, with modern public and private institutions. In 1985, the first teacher education institutions offered a diploma programme. In 1994, six Colleges of Education, offering a degree, were established. Recently, the Directorate General-Colleges of Education, Ministry of Higher Education, introduced a quality assurance process in these colleges based on self-assessment, external review, feedback, and monitored change. This paper outlines how the process was established, the challenges it presented, and the solutions that have been developed. 相似文献
75.
Mohammed Saqr Ward Peeters 《British journal of educational technology : journal of the Council for Educational Technology》2022,53(5):1283-1303
Social Network Analysis (SNA) has enabled researchers to understand and optimize the key dimensions of collaborative learning. A majority of SNA research has so far used static networks, ie, aggregated networks that compile interactions without considering when certain activities or relationships occurred. Compressing a temporal process by discarding time, however, may result in reductionist oversimplifications. In this study, we demonstrate the potentials of temporal networks in the analysis of online peer collaboration. In particular, we study: (1) social interactions by analysing learners' collaborative behaviour, part of a case study in which they worked on academic writing tasks, and (2) cognitive interactions through the analysis of students' self-regulated learning tactics. The study included 123 students and 2550 interactions. By using temporal networks, we show how to analyse the longitudinal evolution of a collaborative network visually and quantitatively. Correlation coefficients with grades, when calculated with time-respecting temporal measures of centrality, were more correlated with learning outcomes than traditional centrality measures. Using temporal networks to analyse the co-temporal and longitudinal development, reach, and diffusion patterns of students' learning tactics has provided novel insights into the complex dynamics of learning, not commonly offered through static networks. 相似文献
76.
Chiong Ing Tiong Yahya Azli Mohammed Rafiq Abdul Kadir Samion Syahrullail 《浙江大学学报(A卷英文版)》2012,13(8):633-640
The effects of the mechanical factors with applied loads on the tribological performance of refined, bleached and deodorised (RBD) palm stearin (PS) were studied using a four-ball tribotester. All the RBD PS results were simultaneously compared with the additive-free paraffinic mineral oil (PMO). The experiments were carried out using different loads with a constant speed in order to gain a better understanding of the mechanical processes that occurred during the experiment. For each experiment, the temperature was increased to 75 °C and was run for 1 h. In a mechanical system, lubricant plays an important role in reducing wear and friction. PS exists as a semi-solid at room temperature after the fractionation process from oil palm. Due to the increasing rate of pollution to the environment, vegetable oil was chosen as the test lubricant with regard to its biodegradability. Other advantages of vegetable oil are that it is more easily harvestable and non-toxic compared to petroleum-based oil, which made it a suitable candidate. From the experiment, RBD PS is found to have a better friction constraint reduction compared with additive-free PMO. 相似文献
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79.
Greg Roberts Nancy Scammacca David J. Osman Colby Hall Sarojani S. Mohammed Sharon Vaughn 《Educational Psychology Review》2014,26(3):451-468
Promoting Acceleration of Comprehension and Content through Text (PACT) and similar team-based models directly engage and support students in learning situations that require cognitive elaboration as part of the processing of new information. Elaboration is subject to metacognitive control, as well (Karpicke, Journal of Experimental Psychology: General 138(4):469–485, 2009)—successful learners use metacognitive elaborative rehearsal to process and make sense of incoming information even in the absence of structured opportunities or instructional prompts for elaborating. Levels of processing and cognitive load theories suggest that students in PACT classrooms may outperform students in comparison classes because PACT engages and supports deep cognitive processing (via elaboration and discussion) at the time of learning, allowing participants to better conserve and more consistently reallocate cognitive and metacognitive resources (compared to students in the non-treated group) for encoding content. In other words, PACT may moderate the relationship of metacognitive elaborative rehearsal and content retrieval. Extant data from years 1 (n?=?419) and 2 (n?=?704) of the PACT/RFU project suggests such an effect. As hypothesized, there were no mean differences in reported metacognitive rehearsal use across the groups because metacognitive elaborative rehearsal was not taught. However, regression coefficients for content recall on metacognitive elaboration were greater in the treatment group in both samples suggesting that an instructional emphasis on deep processing leads to better content recall. The findings are discussed in the context of the Common Core State Standards and the large-scale testing programs in place currently across the USA. 相似文献
80.
Mohammed Sani Ibrahim Simin Ghavifekr Sii Ling Saedah Siraj Mohd Ibrahim K. Azeez 《Asia Pacific Education Review》2014,15(2):177-190
This study investigates the impact of transformational leadership as idealized influence, inspirational motivation, intellectual stimulation, and individualized consideration on teachers’ commitment towards organization, teaching profession, and students’ learning. A quantitative survey method was applied, and four broadly hypothesized relationships were tested with a sample of 1,014 trained non-graduate and graduate teachers serving in twenty-seven secondary schools in Sarawak, Malaysia. The results indicate a moderate level of teachers’ commitment and a low level of transformational leadership qualities among the respondents. This study found that inspirational motivation, individualized consideration, and intellectual stimulation were the factors contributing towards teachers’ commitment to teaching profession, and there was no dominant factor influencing commitment to students’ learning. Moreover, it was discovered that inspirational motivation was a factor to teachers’ efficacy and teaching experience. Besides, teachers’ efficacy and teaching experience were predictors to teachers’ commitment to organization, teaching profession, and students’ learning, respectively. These findings revealed that there was a significant relationship between transformational leadership and teachers’ commitment to organization and teaching profession, but not students’ learning. The results of this study indicate the necessity for leadership development of school leaders so that they could systematically acquire and internalize the effective transformational leadership qualities that are crucial in changing teachers’ attitude and improving their commitment towards their profession. 相似文献