Predicting Science Engagement with Motivation and Teacher Characteristics: a Multilevel Investigation

The purpose of this study was to investigate the student and teacher-level predictors of Turkish middle school students' engagement in science classes. Students' engagement was examined in terms of agentic, behavioral, cognitive, and emotional engagement. The participants of the study were 134 Turkish science teachers and their 3394 grade 7 students. Separate multilevel models were specified for each dimension of students' science engagement. Results of the HLM analyses indicated that dimensions of students' science engagement were significantly predicted mostly by the student-level variables including science self-efficacy, mastery approach and avoidance goals, and performance approach goals. Teacher-level variables were influential only on the cognitive and emotional engagement. There were also cross-level interactions in predicting science engagement. Results were discussed in the light of related literature

Ring-Opening Copolymerization of L-Lactide and Epsilon-Caprolactone in Supercritical Carbon Dioxide Using Triblock Oligomers of Caprolactone and Peg As Stabilizers

In this study, the use of triblock (A-B-A) oligomers of epsilon-caprolactone (epsilon-CL) (A) and PEG400 (B) as stabilizers (SB) for the copolymerization of L-lactide (LLA) and epsilon-CL in supercritical carbon dioxide (scCO(2)) was investigated. To determine the effect of CO2-philic and polymer-philic segments on copolymerization, oligomers with three different average molecular weights (M-w=2000-6000 Da) were synthesized by changing the PEG400/epsilon-CL ratio. Copolymerizations were confirmed by H-1-nuclear magnetic resonance (NMR), C-13-NMR and differential scanning calorimeter data. It was possible to copolymerize LLA and e-CL in scCO(2) without any SB; however, the polymerization yields and average molecular weights were low, and significant aggregate formations were detected. Recipes featuring only 5% SB were successfully applied to reach high polymerization yields of similar to 85% and polymers with average molecular weights greater than 20 kDa. When the polymer-philic segment of the SB increased, both the yield and molecular weight of the copolymer also increased significantly, resulting in white powdery products. Polymer Journal (2011) 43, 785-791; doi: 10.1038/pj.2011.70; published online 27 July 2011Wo