Erosion behavior and mechanism of boronised steels

Boronising of steels is a hardening process to get high surface hardness. The erosion resistance of boronised steels was researched with the use of four kinds of erodent, i.e. glass, alumina, quartz and silicon carbide. The erosion rate increases rapidly with erodent hardness and severe erosion occurs with high impacting angle range of hard particles. SEM analysis indicated that chipping is caused by repetitive impacting of glass and quartz, whereas by alumina and silicon carbide impacting, chipping, and that plastic flow take place simultaneously and the erosion rate reaches the peak value when the impacting angle is above 60°.     

Social network analysis of international student mobility: uncovering the rise of regional hubs

Research on the patterns of international student mobility and the dynamics shaping these patterns has been dominated by studies reflecting a Western orientation, discourse, and understanding. Considering political, economic, cultural, historical, and ecological factors, this study argues that international student mobility is not only an issue of the economically developed, politically stable, and academically advanced Western world but also one that involves countries with different economic, political, and academic characteristics. Taking into account various theoretical orientations, this study argues that political, economic, cultural, and historical factors have led to the emergence of non-traditional destinations for international students; these countries are labeled as emergent regional hubs. In order to empirically test this, a social network analysis was conducted on a worldwide dataset representing 229 countries. The findings evidenced the strong position of traditional destinations for international students. However, the results also suggest the rise of several regional hubs, which are undergoing internationalization processes in different forms and with different rationales. The mobility patterns in emerging regional hubs deviate from those in traditional destinations, which fundamentally change the nature of internationalization in this context.     

The promises and limitations of international comparative research on teacher education

This article revisits methodological perspectives on international comparative research on teacher education (TE). Benefits and problems related to comparative educational research methodology in general are discussed. Further, methodological issues associated with designing and carrying out an international comparative study on TE are addressed using a multi-level study on teacher education in Finland and Norway an as example. Towards the end of the article, the promises and limitations of international comparative research on TE are presented. Important benefits of comparative education on TE include widening the understanding of one’s own and other TE systems as well as gaining an understanding of international trends. However, uncritical use of such research may lead to decontextualised, ahistorical and standardised transfer and development of education and educational policies. The article concludes by urging researchers in the field of international comparative research on teacher education to address the questions: What is being compared? How is context addressed?     

Concurrent and longitudinal predictors of calculation skills in preschoolers

Early calculation abilities in preschoolers are predictive of mathematics achievement in subsequent grades (e.g., Jordan et al. 2009). Two studies were conducted to evaluate concurrent and longitudinal predictors of early calculation skills. In the first study, 102 preschoolers (57.8 % female; mean age?=?60.57?±?8.66 months) were given vocabulary, language comprehension, and verbal working memory tasks and a test battery that evaluated components of early number competence (quantity comparison, counting, number line, size seriation, semantic knowledge of digits, visual-spatial memory). The children were also asked to complete early calculation tasks, including addition and subtraction calculations. The results of this task constituted the dependent variable. The results showed that vocabulary, size seriation, and visual-spatial memory were significant concurrent predictors of early calculation competence. In the second study, 43 children completed the early number competence battery at time 1 (53.5 % female; mean age?=?59.30?±?3.46 months) and the linguistic and early calculation tasks at time 2, about 10 months later (mean age?=?69.43?±?3.31 months). The analysis of the longitudinal predictors of early calculation showed significant effects for counting and size seriation. The implications for preschool assessment and intervention are discussed.     

Preservice teachers’ use of contrasting cases in mathematics instruction

Drawing comparisons between students’ alternative solution strategies to a single mathematics problem is a powerful yet challenging instructional practice. We examined 80 preservice teachers’ when asked to design a short lesson when given a problem and two student solutions—one correct and one incorrect. These micro-teaching events were videotaped and coded, revealing that fewer than half of participants (43%) made any explicit comparison or contrasts between the two solution strategies. Those who did were still not likely to use additional support strategies to draw students’ attention to key elements of the comparison. Further, correlations suggest that participants’ mathematical content knowledge may be related to whether participants’ showed contrasting cases but not to whether they used specific pedagogical cues to support those comparisons. While these micro-teaching events differ from the interactive constraints of a classroom, they reveal that participants did not immediately orient toward differing student solutions as a discussion opportunity, and that future instruction on contrasting cases must highlight the utility of this practice.     

Validation of a self-perceived media competence instrument for pre-service teachers / Validación de un instrumento de autopercepción de competencia mediática para docentes en formación

Abstract

Key to guaranteeing the fundamental human rights of freedom of expression and information is the development of media competence, particularly in schools. Training teachers in the area of media competence is particularly important for developing these skills in the broader citizenry. In order to provide educators and educational policymakers with a useful diagnostic tool, we have designed a self-perception questionnaire. The questionnaire was applied to a sample of Peruvian education students (N = 501). On the one hand, the results confirm the construct’s coherence, validity and instrumental reliability. On the other hand, they allow us to propose a theoretically based update to the way in which this construct is interpreted and applied, confirming the multidimensionality of media competence. Finally, we use this empirical evidence to discuss the integral, transversal and ecological status of media competence.     

„Jeder Schule ihre Lehrer“?

Neue Personalauswahl- und Einstellungsverfahren, an denen die Einzelschulen ma?geblich beteiligt werden, kommen bei der Besetzung von Lehrerstellen in zahlreichen Bundesl?ndern seit Mitte der 1990er-Jahre zur Anwendung und haben mittlerweile die herk?mmlichen zentralen Auswahl- und Zuweisungsverfahren zumindest in einigen von ihnen nahezu vollst?ndig abgel?st. Die Praxis und Wirkung der neuen Auswahlverfahren wurde bislang allerdings nicht systematisch untersucht. In diesem Beitrag werden empirische Befunde einer Untersuchung von Schulen in Nordrhein-Westfalen vorgestellt, die im Jahr 2002 freie Lehrerstellen über das neue Ausschreibungsverfahren besetzt haben. Erfasst wurden unter anderem die in der Praxis angewandten Kriterien der Personalauswahl und die Inhalte der Auswahlgespr?che, die Beurteilung des neuen Auswahl- und Einstellungsverfahrens durch die beteiligten Schulleitungen und Mitglieder der Auswahlkommissionen, Einsch?tzungen und Erfahrungen der neu eingestellten Lehrkr?fte sowie der Verlauf ihrer Berufseinstiegsphase und ihre Bew?hrung am neuen Arbeitsplatz.     

Photoresists for microlithography

Photoresist technology, which is used for micro-patterning exploits changes in properties of polymeric materials, such as their solubility or volatility, upon photo-irradiation. This process has greatly benefitted from the knowledge base of organic chemistry and photo-induced organic transformations. The role of chemistry in the development of photoresists is described in this article.