Finite element analysis of dynamic stability of skeletal structures under periodic loading

INTRODUCTION Some structures fail geometrically before thestrength failure because of lack of stability and such afailure is known as instability failure or bucklingfailure. Determination of buckling load is importantin order to ensure the stability of a structure. If thestructure under consideration is subjected to a dy-namic load then this problem comes under the pur-view of dynamic stability problems. Examples areslender offshore structures subjected to periodic ex-citations and colum…     

Parent-Infant Rough Play: Its Cultural Specificity

The salience of father-infant rough play in some industrialized and nonindustrialized countries around the world was reviewed, and data were presented on the physical play interactions of 34Indianmothers and fathers with their year-old infants in the home. Our review of the parent-infant physical play literature failed to show that fathers had a uniformly greater propensity to engage in vigorous rough activity with infants than mothers did. The data from the observational study suggest that Indian parents are not vigorous play partners to infants. Mothers were more likely to engage in object-mediated play than were fathers. In total, the data reviewed do not support the contention that rough play is a major activity between fathers and infants across cultures. Rather, the data from parent-infant play in the nonindustrialized countries suggest that rough play may be culture specific, casting doubts about its biological underpinnings.     

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%).     

Peer learning in international higher education: the experience of international students in an Irish university

Some of the main concerns in international higher education are the feeling of isolation among international students and their inability to adapt to the host environment, which may result in sub-optimal academic performance. Theoretically, peer learning can be an effective method to reduce these problems since it has the capacity to address isolation and adaptability issues among international students in a way that improves their learning experience and outcomes. Given the above, our study was designed to investigate this topic, focusing on the experience of international students. In this exploratory case study of a leading Irish university, we adopted a survey method via questionnaire to quantify and compare the experiences of a sample of international students at the said university. Five aspects of peer learning were explored, namely usage rate, current practices, outcomes, challenges, and coping strategies. We also included an open-ended section in the survey instrument for respondents to offer qualitative suggestions to the host institution. Through methodological triangulation of the quantitative and qualitative data, we discovered diverse practices, challenges, and outcomes of peer learning across different groups of international students in this university. The paper concludes with a discussion of research implications and suggestions for future studies.     

Identification of novel catalytic features of endo-β-1,4-glucanase produced by mulberry longicorn beetle Apriona germari

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.     

Meeting the challenges: The development of quality assurance in Oman’s Colleges of Education

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.     

Temporal networks in collaborative learning: A case study

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.     

Tribological evaluation of refined, bleached and deodorized palm stearin using four-ball tribotester with different normal loads

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.