随机扩增多态性DNA技术研究发现二氧化钛纳米颗粒对西葫芦具有基因毒性

研究目的：二氧化钛（TiO2）纳米颗粒已经广泛应用于化妆品、防晒霜、涂料和牙膏等。这些纳米颗粒性质非常稳定,能在废水和生物固体中转移和分散。现有研究表明,TiO2纳米颗粒对动物正常生理活动具有毒性等负面作用。但是,它们对植物是否具有毒性特别是是否会产生植物基因毒性至今尚不清楚。因此,本文使用随机扩增多态性DNA技术研究TiO2纳米颗粒是否对西葫芦具有基因毒性,为TiO2纳米颗粒排放进入环境后的潜在植物毒性风险评价提供依据。 创新要点：首次发现了TiO2纳米颗粒对西葫芦具有基因毒性。 重要结论：采用随机扩增多态性DNA技术,发现TiO2纳米颗粒污染处理的西葫芦样品与未处理样品的基因组DNA图谱相比,不仅在谱带强度有明显差异,而且存在谱带消失和新谱带产生现象,表明TiO2纳米颗粒对西葫芦具有基因毒性。     

The EFQM self-assessment processes in HEIs in Spain and in Jordan

The purpose of this paper is to compare the European Foundation for Quality Management （EFQM） self-assessment model in higher education institutions （HEIs） in Spain and in Jordan. Case study methodology on eight services provided by a public university in Spain and seven services provided by one public university and one private university in Jordan is used. The findings show the steps that an administrative service may follow in order to apply the questionnaire approach to conduct self-assessment in a successful manner and the difficulties, benefits and success factors in both countries by comparing the results. This paper provides lessons for decision makers and managers of other universities in developing countries, who wish to perform an exercise in self-assessment using a questionnaire approach.     

A case example of one state's efforts to measure and address the critical shortage of school psychologists

Despite persistent calls for school psychologists to provide comprehensive and integrated services, school psychologists may have difficulty providing these services because of critical shortages in the profession. This practical action research study involved surveying district supervisors of school psychologists and training program directors in the state to identify the current and projected shortages in Florida. This multimethod, multi‐informant case example also focused on facilitators of and barriers to addressing the critical shortage. How the data have been used to inform recruitment, retention, and advocacy efforts to identify school psychology as a critical shortage legislatively are provided as well as recommendations for future research.     

Studying mathematics problem-solving classrooms. A comparison between the discourse of in-service teachers and student teachers

In the article we compare the approaches of 3 in-service teachers and 3 student teachers when they tried to solve a verbal arithmetic problem in the classroom. Each interaction was studied using a System of Analysis that takes into account the cognitive processes involved in the solution of a mathematic problem and describes the interaction at different levels showing what is done and to what degree teachers and/or pupils are responsible for what is done. The results of the study suggest that both groups of teachers are different in how they direct the student’s attention toward the essential aspects implied in the resolution of word problem. On the one hand, the in-service teachers guaranteed students’ understanding of the problem before dealing with the solution, while students teachers only did so when pupils committed errors. On the other hand, the in-service teachers allowed a high level of student participation, while student teachers took a more prominent role so children’s participation was lower.     

Images of Science Linked to Labwork: A Survey of Secondary School and University Students

This paper presents findings about the images of science drawn upon in laboratory work, by upper secondary and university students, in academic streams with a science focus. Data were collected through four written questions, administered to a total of 368 students. The questions all required students to comment on laboratory investigations carried out by research scientists or by science students. We show that students' reasoning has an epistemological and an ontological dimension, and that it often differs significantly from accepted perspectives on the nature of science. The issue for teaching appears to be showing students what counts (and what does not count) as appropriate reasoning in actual situations. In other words, explicit teaching about the various relationships that can exist between theory and data would transform labwork towards a more critical process that involves making and justifying decisions.     

Tunnelling effects in chemistry

Most of the molecules react to form products by climbing a barrier. The energy involved in this climbing of the barrier is known as the activation energy of the reaction. Questions like how fast a reaction occurs can be answered by considering the height of the barrier. However, in some reactions, the reactants transform to products by directly tunnelling across the barrier instead of climbing over it. Such a purely quantum mechanical effect, which becomes more prominent for reactions at low temperatures can lead to interesting and even completely unexpected products. This effect and its consequences in representative examples are discussed.     

The Curious Case of the Deaf and Contested Landscapes of Bilingual Education

In this article, the authors examine deaf education as a “curious case” to prompt thinking about issues of language inequities. The authors argue that tying the fortunes of deaf students to those of other language minority students provides opportunities for new insights into policies and practices of deaf education as well the education of other language minorities in American schools. The authors provide a case example of successful deaf bilingual education that challenges the equation of deaf communicative difference with academic failure. They conclude with a discussion of American bilingual education history and how a consideration of the “curious case” of deaf education opens up possibilities for expanding understandings of more general issues of language difference in education.     

Professional Development of Teacher Trainers: a case study

This paper reviews the literature on teacher trainers with special reference to current initiatives in Spain, and provides a case study of the design, delivery and follow‐up to a course for teacher trainers of English language teaching and the pedagogy of language. The course was designed to promote the concept of teachers as reflective practitioners.