Search

Herein we report the zwitterionic pentagonal bipyramidal oxidorhenium(V) complex trans-[ReOI2(bpp)] where bpp is (1E,3E)-1,3-bis(pyrimidin-2-ylimino)propan-2-ide anion. The complex trans-[ReOI2(bpp)] was unusually formed from the reaction of trans-[ReOI2(OEt)(PPh3)3] with 2-aminopyrimidine in propan-2-ol in the presence of triethylamine (Et3N). The anionic ligand bpp was formed by oxidorhenium(V)-catalysed dehydroxylation of propane-2-ol followed by condensation with 2-aminopyrimidine, and coordinates to the [ReO]3+ core as tetradentate N-donor chelate. A few numbers of pentagonal bipyramidal complexes are known for oxidorhenium(V), and the complex trans-[ReOI2(bpp)] is another example. The complex was analyzed by 1H NMR, IR, UV-visible and single crystal X-ray crystallography. In addition, density functional theory (DFT) was also studied. [ABSTRACT FROM AUTHOR]

Smartphones and computer-based technology have revolutionized different development sectors including education. The current review describes the existing literature on Web-Based Learning ( WBL) as a novel methodology applied in teaching and learning, and its potential effectiveness in teaching and learning chemistry. Further, the study intends to reflect on how the WBL could be applied in the Rwandan context of teaching and learning chemistry as the country adopted the competency-based curriculum (CBC) in 2015. This review is a narrative overview in which much of the existing literature such as books, articles, and other online literatures related to the study were reviewed. The literature was obtained from different electronic databases including Scopus, ERIC, ISI web of knowledge, academia, web of science, digital library, and google scholar., Competing Interests: Conflict of interestThe authors declare that they have no conflicts of interest., (© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2022, Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

This study intended to explore the contribution of Task-Based Learning (TBL) to raising students' attitudes toward learning chemistry. The study employed a quasi-experimental research design with 369 secondary school grade-2 students in Rwanda. The study randomly assigned students to two groups of differentiated instruction. Thus, the experimental group was exposed to the TBL method, while a control group was taught the teacher-centered method. An internationally standardized Chemistry attitude questionnaire of 0.831 Cronbach alpha reliability coefficient was used before and after teaching and learning activity. The Kruskal Wallis test was computed in SPSS 23.0 to measure the effect of TBLin raising positive attitudes among students in the experimental group compared to the control group. The attitude gain was measured from pre-test to post-test in attitude variables. This study showed a statistically significant difference between the control group and the experimental group (ꭓ 2 = 4.118, df = 1, p < .05). Furthermore, the students perceived chemistry's importance more than the other three variables (difficulty, interest, and usefulness of chemistry). Results also showed that gender affected students' perceptions of learning chemistry. Females students developed more positive attitudes than male students. However, school location statistically affecting students' attitudes towards chemistry. The study result implies that TBL method helped to increase students' attitudes toward chemistry. Recommendations were given to implement TBL methods in the chemistry classroom., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s).)

The past decade has seen a significant shift from teacher-centered pedagogy to a learner-centered approach in chemistry education research. Game-based learning has emerged as one of the most beneficial instructional approaches because it emphasizes "hands-on" and "minds-on" activities in chemistry classrooms. However, there has been a scarcity of review studies in chemistry education research that have attempted to document different educational games implemented and how such games have contributed to enhancing students' motivation and understanding of chemistry concepts. A total of 57 articles were reviewed to identify educational games implemented in chemistry classrooms from 2010 to 2021 to address this gap. All the reviewed articles were downloaded from the Google Scholar search engine and have all been indexed by Scopus. A systematic analysis was adopted to identify the purposes, educational game designs and implementation, and the chemistry content areas of focus for all the reviewed studies. Results show that educational games enhance students' conceptual understanding of chemistry and increase their motivation to learn and have fun while making sense of the learned content., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s).)

This study aims at assessing the classroom practices of Rwandan chemistry teachers in secondary schools, the second grade (S2), age range between 14 to 16 years old. The classroom observation conducted using the Classroom Observation Protocol for Undergraduate STEM (COPUS). In general, the best practice of group work or collaborative learning and students' engagement was observed. The analysis of the COPUS data reveals that active learning in chemistry classes is dominating, 54% against 42% of passive learning; found high, statistically significant over passive learning at p < .01 (tCritical = 1.89, df = 7, p = .003). The active students' practice is taking 82% of a 2-min time interval across 30 lessons observed, as one class period has 40 min to make 20 intervals of 2 min. Teachers are engaging their students in collaborative learning by assigning them various tasks in groups. These results established the current instructional practices in chemistry classes to draw conclusions and recommendations., Competing Interests: The authors declare no conflict of interest., (© 2021 The Author(s).)

Fresh and pasteurized milk samples from Kampala markets were analyzed for organochlorine pesticides using a gas chromatograph equipped with an electron capture detector. Five organochlorine pesticides, namely; aldrin, dieldrin, endosulfan, lindane, DDT and its metabolites were detected in the milk samples and confirmed with a gas chromatograph equipped with a mass spectrometer [GC-MS]. The mean values are expressed in mgkg(-1) milk fat (mf) basis. The mean concentration in the fresh milk (n=54) were: 0.026 ± 0.003 mg kg(-1) mf; 0.002 ± 0.0003 mg kg(-1), below the detection limit; 0.007 ± 0.003 mg kg(-1), 0.009 ± 0.002 mg kg(-1) milk fat for lindane, endosulfan dieldrin and aldrin, respectively. The mean concentrations of p,p'-DDE; p,p'-DDT and o,p'-DDT were 0.009 ± 0.002 mg kg(-1); 0.033 ± 0.007 mg kg(-1) and 0.008 ± 0.001 mg kg(-1) mf, respectively in the fresh milk samples. In the pasteurized milk samples (n=47), the mean concentrations recorded were: 0.008 ± 0.003 mg kg(-1), 0.025 ± 0.004 mg kg(-1), and 0.007 ± 0.001 mg kg(-1), respectively for p,p'-DDE; p,p'-DDT and o,p'-DDT. Alpha and beta-endosulfan recorded the concentration below the detection limit and the mean of 0.022 ± 0.001 mg kg(-1) mf, 0.005 ± 0.002 mg kg(-1) mf, and 0.006 ± 0.0002 mg kg(-1) mf, respectively for lindane, dieldrin and aldrin. Although, most of the residues detected were above the residue limits set by the FAO/WHO (2008), bioaccumulation of these residues is likely to pose health risks to the consumers of milk in Uganda., (Copyright © 2011. Published by Elsevier Ltd.)