388 research outputs found
Impact of controlled vacuum induced surface freezing on the freeze drying of human plasma
During the freezing step of a typical freeze drying process, the temperature at which nucleation is induced is generally stochastically distributed, resulting in undesired within-batch heterogeneity. Controlled nucleation techniques have been developed to address this problem; these make it possible to trigger the formation of ice crystals at the same time and temperature in all the batch. Here, the controlled nucleation technique known as vacuum induced surface freezing is compared to spontaneous freezing for the freeze drying of human plasma, a highly concentrated system commonly stored in a dried state. The potency of Factor VIII (FVIII), a sensitive, labile protein present in plasma, and the reconstitution time of the dried cakes are evaluated immediately after freeze drying, and after 1, 3, 6 or 9 months storage at different degradation temperatures. We show that the application of controlled nucleation significantly reduces the reconstitution time and in addition helps to improve FVIII stability
Teaching energy conservation as a unifying principle in physics
In this work we present the design and assessment of a teaching sequence aimed at introducing the principle of energy conservation at post-compulsory secondary school level (16-18 year olds). The proposal is based on the result of research into teaching-learning difficulties and on the analysis of the physics framework. Evidence is shown that this teaching sequence, together with the methodology used in the classroom, may result in students having a better grasp of the principle of energy conservation. Keywords Physics education · Energy conceptions · Teaching activitie
From teaching physics to teaching children : beginning teachers learning from pupils
This paper discusses the development of beginning physics teachers' pedagogical content knowledge (PCK) in the context of teaching basic electricity during a one-year Professional Graduate Diploma in Education course (PGDE) and beyond. This longitudinal study used repeated semi-structured interviews over a period of four-and-a-half years. The interview schedule followed a line of development through the secondary school electrical syllabus in Scotland. Fifteen student teachers were interviewed during the PGDE year. Six of them were followed up at the end of the Induction Year (their first year as a newly qualified teacher), and again two-and-a-half years later. Thematic analysis of the interviews showed that before the beginning teachers had taught any classes, their initial focus was on how to transform their own subject matter knowledge (SMK) about electricity into forms that were accessible to pupils. As the beginning teachers gained experience working with classes, they gave vivid descriptions of interacting with particular pupils when teaching electricity which showed the development of their pedagogical knowledge. This played a significant role in the teachers' change of focus from teaching physics to teaching children as they transformed their SMK into forms that were accessible to pupils and developed their general pedagogical knowledge
Developing critical analysis of explanations in physics teachers: Which direction to take?
International audienc
Using resource graphs to represent conceptual change
We introduce resource graphs, a representation of linked ideas used when
reasoning about specific contexts in physics. Our model is consistent with
previous descriptions of resources and coordination classes. It can represent
mesoscopic scales that are neither knowledge-in-pieces or large-scale concepts.
We use resource graphs to describe several forms of conceptual change:
incremental, cascade, wholesale, and dual construction. For each, we give
evidence from the physics education research literature to show examples of
each form of conceptual change. Where possible, we compare our representation
to models used by other researchers. Building on our representation, we
introduce a new form of conceptual change, differentiation, and suggest several
experimental studies that would help understand the differences between
reform-based curricula.Comment: 27 pages, 14 figures, no tables. Submitted for publication to the
Physical Review Special Topics Physics Education Research on March 8, 200
Characterisation of tetanus monoclonal antibodies as a first step towards the development of an in vitro vaccine potency immunoassay
Batch release testing for human and veterinary tetanus vaccines still relies heavily on methods that involve animals, particularly for potency testing. The quantity and quality of tetanus antigen present in these products is of utmost importance for product safety and clinical effect. Immunochemical methods that measure consistency of antigen content and quality, potentially as an indicator of potency, could be a better choice and negate the need for an in vivo potency test. These immunochemical methods require at least one well characterised monoclonal antibody (mAb) that is specific for the target antigen. In this paper we report the results of the comprehensive characterisation of a panel of mAbs against tetanus with a view to select antibodies that can be used for development of an in vitro potency immunoassay. We have assessed binding of the antibodies to native antigen (toxin), detoxified antigen (toxoid), adsorbed antigen and heat-altered antigen. Antibody function was determined using an in-house cell-based neutralisation assay to support prior in vivo potency data that was available for some, but not all, of the antibodies. In addition, antibody affinity was measured, and epitope competition analysis was performed to identify pairs of antibodies that could be deployed in a sandwich immunoassay format. Not all characterisation tests provided evidence of âsuperiorityâ of one mAb over another, but together the results from all characterisation studies allowed for selection of an antibody pair to be taken forward to assay development
âEven though it might take me a while, in the end, I understand itâ: a longitudinal case study of interactions between a conceptual change strategy and student motivation, interest and confidence
Although there have been many investigations of the social, motivational, and emotional aspects of conceptual
change, there have been few studies investigating the intersection of these factors with cognitive aspects in the
regular classroom. Using a conceptual change approach, this case study reports experiences of a student of low to
average prior attainment who achieved high levels of conceptual gains in five science topics over a two-year
period. Her experience in the cognitive, social and affective domains was probed through analysis of interviews,
student artefacts, video recordings of classroom learning, pre/post-tests and questionnaire results. For this student,
peripheral or incidental persuasion of belonging to a supportive small group initially led to greater engagement
with the construction of understanding through production of multiple student-generated representations,
resulting in improved self-confidence and high levels of conceptual change. Evidence of transfer from performance
to mastery approach goals, adoption of positive activating emotions and increased interest in science were
observed. This study highlights that adoption of a multidimensional conceptual change approach with judicious
organisation of small groups to support construction of verbal, pictorial and written representations of
understanding may bring about changes in motivational stance, self-confidence and emotions to maximise
conceptual change
High School Students' Proficiency and Confidence Levels in Displaying Their Understanding of Basic Electrolysis Concepts
This study was conducted with 330 Form 4 (grade 10) students (aged 15 â 16 years) who were involved in a course of instruction on electrolysis concepts. The main purposes of this study were (1) to assess high school chemistry studentsâ understanding of 19 major principles of electrolysis using a recently developed 2-tier multiple-choice diagnostic instrument, the Electrolysis Diagnostic Instrument (EDI), and (2) to assess studentsâ confidence levels in displaying their knowledge and understanding of these electrolysis concepts. Analysis of studentsâ responses to the EDI showed that they displayed very limited understanding of the electrolytic processes involving molten compounds and aqueous solutions of compounds, with a mean score of 6.82 (out of a possible maximum of 17). Students were found to possess content knowledge about several electrolysis processes but did not provide suitable explanations for the changes that had occurred, with less than 45â% of students displaying scientifically acceptable understandings about electrolysis. In addition, students displayed limited confidence about making the correct selections for the items; yet, in 16 of the 17 items, the percentage of students who were confident that they had selected the correct answer to an item was higher than the actual percentage of students who correctly answered the corresponding item. The findings suggest several implications for classroom instruction on the electrolysis topic that need to be addressed in order to facilitate better understanding by students of electrolysis concepts
An exploration of secondary students' mental states when learning about acids and bases
This study explored factors of studentsâ mental states, including emotion, intention, internal mental representation, and external mental representation, which can affect their learning performance. In evaluating studentsâ mental states during the science learning process and the relationship between mental states and learning achievement, valid, reliable, and scalable measures of studentsâ mental states and learning achievement are needed. This paper presents the development of the Mental State Conceptual Learning Inventory (MSCLI) to identify studentsâ mental states before and after learning about acids and bases. This instrument is time efficient and convenient and can be administered to large student samples so that teachers and researchers can gain profound insights into their studentsâ learning of acids and bases in science class. The results of this study indicate that studentsâ mental states are highly correlated with their achievement. As a whole, low-achieving students tended to have negative emotions and low intentions, were not good at internal visualization, and were unable to interpret graphics and draw pictures. In contrast, high-achieving students had positive emotions and intentions when learning life-related topics about acids and bases, and were good at internal visualization and drawing and interpreting graphics
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