Copolymerization of Acrylonitrile/1-Vinyl-3-Ethylimidazolium Bromide and Rheological,Thermal Properties of the Copolymer

Acrylonitrile(AN)/1-vinyl-3-ethylimidazolium bromide(VIMB) copolymer was prepared via solution polymerization using dimethyl sulfoxide(DMSO) as a solvent and azodiisobutyronitrile as an initiator. The effects of comonomer VIMB on the polymerization, rheological properties of the polymer solution and thermal properties of the copolymer were investigated. The ionic liquid VIMB resulted in higher polymerization conversion ratio and higher average molecular weight when copolymerized with AN than itaconic acid(ITA). Rheological measurements indicated that the transition shear rate increased linearly with increasing temperature for P(AN/ITA)/DMSO solution, while an exponential growth with temperature was observed for P(AN/VIMB)/DMSO solution. The exothermic peaks of DSC curves in N_2 appeared at 276.67 and 257.34 °C for P(AN/VIMB) and P(AN/ITA), respectively. As a potential comonomer of AN for PAN carbon fibers, the VIMB resulted in about 7% higher char yield in N_2, and 23.7% less weight loss at 600 °C in air than ITA copolymer.     

The Conceptualization and Development of the Practical Epistemology in Science Survey (PESS)

Research in Science Education - Various inquiry approaches have been promoted in science classrooms as a way for students to engage in, and have a deeper understanding of scientific discourse....     

Cross-Case Study of Self-Regulated Learning as a Series of Events

This exploratory cross-case study: (a) examined self-regulated learning (SRL) during 3 studying episodes, and (b) explored ways 8 students of varying proficiencies productively self-regulated their learning. Profiles of SRL were constructed by examining traces of studying activity, test performance, and student reflections. Profiles were used to: (a) identify individual strengths and weaknesses, (b) compare pairs of High, Low, Average, and Improving students, and (c) construct a model of SRL proficiency. SRL proficiency (skill, will, and adaptation) was not consistent with performance. This study illustrates the importance of collecting multiple measures of SRL as a series of events over time.     

Coding and Centering of Time in Latent Curve Models in the Presence of Interindividual Time Heterogeneity

The coding of time in latent curve models has been shown to have important implications in the interpretation of growth parameters. Centering time is often done to improve interpretation but may have consequences for estimated parameters. This article studies the effects of coding and centering time when there is interindividual heterogeneity in time such as when longitudinal responses are dependent on a point of origin that varies between individuals. Using representative examples that differ in their degree of interindividual time heterogeneity, we compare different models based on alternative forms of coding and centering of time to evaluate potential for biased estimates. Recommendations are made for studies marked by heterogeneity in time measures.     

Texas Community College Funding: Nonmetropolitan and Metropolitan Ad Valorem Tax Rates and Revenue

This article examines ad valorem tax rates per $100 valuation and the resultant tax revenues per in-district contact hour for Texas nonmetropolitan and metropolitan public community colleges. The results of the analyses indicate no difference in ad valorem tax rates between these institutions but demonstrate differences in the resultant tax revenues. Recommendations for further research are provided.     

Interactive TV as an option in early childhood teacher education

Abstract

The qualitative study examined the processes and approaches to collaboration, reflection, and dialogue of preservice and mentoring teachers who were engaged in a yearlong internship experience. Within the context of a university course grounded in constructivism, social constructivism, and the concept of teacher as researcher, the study explored the social interactions of the teachers throughout the course of the school day. Teachers were observed in the process of planning and reflecting on daily classroom activities through collaborative meetings with a focus on the teaching and learning process. The preservice teachers were educated in the use of the main principles described by the Reggio Emilia Approach ‐ collaboration reflection, and dialogue (Edwards, Gandini &; Forman, 1998) and thus, served as a guide for the collaborative interactions with the mentoring teachers.