Understandings and misunderstandings of eighth graders of five chemistry concepts found in textbooks

The research reported in this study was designed to answer three questions: (a) What misconceptions do eighth grade students have concerning the chemistry concepts from their textbooks. (b) How is reasoning ability related to misconceptions concerning chemistry concepts. (c) How effective are textbooks in teaching an understanding of chemistry concepts? Five chemistry concepts were used in the study: chemical change, dissolution, conservation of atoms, periodicity, and phase change. Problems concerning the five concepts were given to 247 eighth-grade students in order to assess the students' degree of understanding of chemistry concepts and to identify specific misconceptions. Two pencil-and-paper Piaget-type tasks were used to assess intellectual level. A comparison of intellectual level and scores on the chemistry concepts showed moderate correlations. However, the small number of formal operational students in the sample makes these results inconclusive. A study of the level of understanding of the five chemistry concepts and the nature of the misconceptions held by students indicate a general failure of textbooks to teach a reasonable understanding of chemistry concepts.     

Learning to listen: from historical sources to classroom practice

Listening to students in productive ways seems to be at the core of teaching practices aligned with the basic tenets of the constructivist world view. We present a definition for productive ways of listening, discuss the challenges involved in implementing it, and propose a way to support the “decentering” needed to learning to listen for teacher education programs. The proposal is based on reading and understanding historical texts as a way to exercising the adoption of the ‘other’s perspective.’ We describe the materials developed for teacher workshops, their implementation and what participants, and we, learned from the experience.     

Polymerase chain reaction: It’s diagnostic application

The development of the Polymerase Chain Reaction (PCR) has been a major technical milestone in molecular genetics with the greatest impact on research, in rapid medical diagnosis and in studying the pathogenesis of disease. This study highlights the practical applications of polymerase chain reaction in diagnosis and includes a recent application of PCR in differentiating polio from other nonpolio enteroviruses.     

Leucine125Valine (Leu125Val) Gene Polymorphism of Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1) and Myocardial Infarction in Indian Population

Platelet-endothelial cell adhesion molecule-1 (PECAM-1) has role in atherosclerotic plaque development as well as in thrombosis leading to myocardial infarction (MI). Present study was aimed to analyse the association of PECAM-1 Leu125Val gene polymorphism with MI in Indian population. Subjects included healthy individuals as control (N = 116) and MI patients (N = 100) divided into two groups; MI patients at presentation of the acute event (MI-Group-1, N = 46) and patients with recent event of MI stabilized with treatment 4.5 days from their symptoms (MI-Group-2, N = 54). The difference in the distribution of Leu125Val genotype frequencies of controls and patients did not reach statistical significance. However Leu allele frequency (0.57) was more associated with MI patients as compared to control (0.504). sPECAM-1 levels were significantly elevated in patients at acute event of MI (MI-Group-1) by 44.1% (P = 0.009) as compared to controls and by 95.2% (P = 0.001) as compared to stabilized MI patients (MI-Group-2).     

On Their Own but Not Alone: The Difficulty in Competence-Oriented Approaches to Teaching Reading and Writing of Thinking of ‘Performance’ in Communal Terms*

Among educators in the field of language and literature, in the German-speaking world and beyond, the concept of ‘competence’ has been gaining ground for three decades. This article questions the validity of prevalent competence definitions, which by focusing on the proficiency of an individual student ignore the fact that in understanding literature, as well as in composition, communal achievement is essential. By drawing on evolutionary anthropology and by collecting evidence from studies in literary and composition learning, the author draws on his own teaching experience to show that students’ competence develops by interaction. Educational research, however, widely fails to take this into account.     

Stable, biocompatible lipid vesicle generation by solvent extraction-based droplet microfluidics

In this paper, we present a microfluidic platform for the continuous generation of stable, monodisperse lipid vesicles 20–110 μm in diameter. Our approach utilizes a microfluidic flow-focusing droplet generation design to control the vesicle size by altering the system’s fluid flow rates to generate vesicles with narrow size distribution. Double emulsions are first produced in consecutive flow-focusing channel geometries and lipid membranes are then formed through a controlled solvent extraction process. Since no strong solvents are used in the process, our method allows for the safe encapsulation and manipulation of an assortment of biological entities, including cells, proteins, and nucleic acids. The vesicles generated by this method are stable and have a shelf life of at least 3 months. Here, we demonstrate the cell-free in vitro synthesis of proteins within lipid vesicles as an initial step towards the development of an artificial cell.