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Evdokimova Olga L. Alves Carla S. Krsmanović Whiffen Radenka M. Ortega Zaida Tomás Helena Rodrigues João 《Journal of Zhejiang University. Science. B》2021,22(6):450-461
In this study, the fibers of invasive species Agave americana L. and Ricinus communis L. were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers. Cellulose nanofibers were obtained by two methods, based on either alkaline or acid hydrolysis. The morphology, chemical composition, and crystallinity of the obtained materials were characterized by scanning electron microscopy(SEM) together with energy-dispersive X-ray spectroscopy(EDX), dynamic light scattering(DLS), X-ray diffraction(XRD), and Fourier transform infrared(FTIR)spectroscopy. The crystallinity indexes(CIs) of the cellulose nanofibers extracted from A. americana and R. communis were very high(94.1% and 92.7%, respectively). Biological studies evaluating the cytotoxic effects of the prepared cellulose nanofibers on human embryonic kidney 293 T(HEK293 T) cells were also performed. The nanofibers obtained using the two different extraction methods were all shown to be cytocompatible in the concentration range assayed(i.e., 0-500 μg/mL). Our results showed that the nanocellulose extracted from A. americana and R. communis fibers has high potential as a new renewable green source of highly crystalline cellulose-based cytocompatible nanomaterials for biomedical applications. 相似文献
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We present new methods of query expansion using terms that form lexical cohesive links between the contexts of distinct query terms in documents (i.e., words surrounding the query terms in text). The link-forming terms (link-terms) and short snippets of text surrounding them are evaluated in both interactive and automatic query expansion (QE). We explore the effectiveness of snippets in providing context in interactive query expansion, compare query expansion from snippets vs. whole documents, and query expansion following snippet selection vs. full document relevance judgements. The evaluation, conducted on the HARD track data of TREC 2005, suggests that there are considerable advantages in using link-terms and their surrounding short text snippets in QE compared to terms selected from full-texts of documents. 相似文献
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Even though there are increasing numbers of PhD students in the distance mode, our current understanding of PhD candidature at a distance is limited and incomplete. On the one end of the spectrum are accounts of unhappy and isolated doctoral students who are separated from communities of practice. At the same time, literature offers accounts of PhD students at a distance who view themselves as agential and autonomous and are happy not to get sidetracked by others. In this reflection we ask what distinguishes the conventional PhD student from one who is studying at a distance, and invite more research on self-efficacy and vicarious learning of PhD students at a distance. 相似文献
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This study examined the effect of a short-term training programme οn in-service physical education teachers’ behaviour and students’ engagement in learning. Teachers (n = 32) were randomly divided into an experimental and a control group. Each teacher’s behaviour was observed in six lessons; two for each measurement (pre, post and retention) and analysed with qualitative dimensions of lesson introduction, task presentations and lesson closure. Student engagement was analysed with the time analysis form. The total and successful attempts of selected students were also recorded. The experimental group attended a two-hour lecture followed by a two-hour practicum, and showed significant improvement and learning of all the examined behaviours as well as significantly higher performance than the control group. Also, students of the experimental teacher group presented significantly greater activity time, more practice attempts and more successful ones than their peers in the control group. The results establish the effect of the training programme on teacher behaviour and student engagement in learning. 相似文献
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This paper studies the publication productivity of inbreds and non‐inbreds among Russian academics. Existing literature provides ambiguous results on the relationship between inbred status and productivity. This may be explained by the use of different indicators for measuring publication productivity. We use data, which include indicators of both current publication productivity (at a certain point of time) and cumulative productivity (throughout the career) to identify whether inbreds and non‐inbreds differ in their productivity. We did not find any difference in current publication productivity of inbreds and non‐inbreds. We found, however, a difference in their cumulative publication productivity: non‐inbreds are being more productive on an individual level throughout their careers. Although the conclusions are based on the Russian data, the analysis provides an explanation for existing contradictory results on the relationship between academic inbreeding and productivity in general. 相似文献
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Olga Fedorenko 《Inter-Asia Cultural Studies》2017,18(4):498-517
This article examines conflicts over the transnationalization of South Korean celebrities in the wake of the Korean Wave (Hallyu) in the twenty-first century. I consider a number of celebrity controversies to argue that the demands placed upon Hallyu celebrities by domestic observers, foreign audiences, and global capital are fundamentally irreconcilable. South Korean nationalist appropriation of Hallyu, as well as the local celebrity culture, demand that Hallyu stars firstly be exemplary Korean patriots, whereas international audiences expect sympathy for their own causes. Local nationalist agendas have proven particularly troublesome because of postcolonial sensibilities and ongoing territorial disagreements between South Korea and its neighbors. Finally, as circulating commodities and commercial assets, Hallyu stars are also pledged to global capital. Their value is highest when they appeal to as broad an audience as possible and alienate no one with their politics. An apolitical neutrality on regionally controversial issues, however, is an untenable position when antagonistic geopolitical interests are concerned and nationalist passions flare. I situate this argument within critical scholarship on cultural globalization flows within Asia, while engaging celebrity studies to frame Hallyu stars as transnational commodities. 相似文献
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The usability of interactive whiteboards vs. computers was evaluated on three dimensions (visibility, legibility and comprehension) in the secondary school pupils. The visibility assessment consisted in detecting a visual stimulus varying in luminance using a staircase procedure, legibility was assessed with a target-search task, and we administered narrative and explanatory texts with or without illustrations to evaluate comprehension. The results of the visibility test showed that pupils found the light signal easier to detect on the IWB. For the legibility test, we observed differences in error rates and discriminability according to medium, font size and congruence between target and the distractor letters. Performances in the comprehension test were similar for both explanatory and narrative texts. Moreover, the presence of illustrations does not improve comprehension. These results could be related to the hierarchical structure of the texts, which facilitate comprehension. 相似文献