title: New insights into the role of pH and aeration in the bacterial production of calcium carbonate (CaCO₃)

authors: Seifan, Mostafa

subjects: Science & Technology

abstract: Over recent years, the implementation of microbially produced calcium carbonate (CaCO₃) in different industrial and environmental applications has become an alternative for conventional approaches to induce CaCO₃ precipitation. However, there are many factors affecting the biomineralization of CaCO₃, which may restrict its application. In this study, we investigated the effects of pH and aeration as the main two influential parameters on bacterial precipitation of CaCO₃. The results showed that the aeration had a significant effect on bacterial growth and its rise from 0.5 to 4.5 SLPM could produce 4.2 times higher CaCO₃ precipitation. The increase of pH to 12 resulted in 6.3-fold increase in CaCO₃ precipitation as compared to uncontrolled-pH fermentation. Morphological characterization showed that the pH is an effective parameter on CaCO₃ morphology. Calcite was found to be the predominant precipitate during aeration-controlled fermentations, while vaterite was mainly produced at lower pH (up to 10) over controlled-pH fermentations. Further increase in pH resulted in a morphological transition, and vaterite transformed to calcite at the pH ranges between 10 and 12.

text: New insights into the role of pH and aeration in the bacterial production of calcium carbonate (CaCO₃) Over recent years, the implementation of microbially produced calcium carbonate (CaCO₃) in different industrial and environmental applications has become an alternative for conventional approaches to induce CaCO₃ precipitation. However, there are many factors affecting the biomineralization of CaCO₃, which may restrict its application. In this study, we investigated the effects of pH and aeration as the main two influential parameters on bacterial precipitation of CaCO₃. The results showed that the aeration had a significant effect on bacterial growth and its rise from 0.5 to 4.5 SLPM could produce 4.2 times higher CaCO₃ precipitation. The increase of pH to 12 resulted in 6.3-fold increase in CaCO₃ precipitation as compared to uncontrolled-pH fermentation. Morphological characterization showed that the pH is an effective parameter on CaCO₃ morphology. Calcite was found to be the predominant precipitate during aeration-controlled fermentations, while vaterite was mainly produced at lower pH (up to 10) over controlled-pH fermentations. Further increase in pH resulted in a morphological transition, and vaterite transformed to calcite at the pH ranges between 10 and 12.

year: 2017

title: Challenges for e-learning for university instructors in Taiwan

authors: Wang, Su-Chen

subjects: e-learning

abstract: Blended courses that include both face-to-face and e-learning have been offered  in many universities in Taiwan but very little research has been undertaken on instructor  perspectives of the challenges they faced in their e-learning teaching. This paper explores the challenges faced by university instructors in a national research-based university in Taiwan. An interpretive paradigm utilizing qualitative and quantitative methods was adopted. The paper outlines the findings from 27 e-learning instructors in in-depth interviews and 55 of 69 e-learning instructors who responded to this open-ended question in the questionnaire. Instructors noted they faced pedagogical, personal, and technological challenges. The findings suggested instructors needed to adopt different pedagogical approaches to work with new media in developing their e-learning courses so new curriculum design, new teaching methods, new ways of assessment, and new interaction approaches were needed. The instructors faced personal challenges in time management and role change if they needed to provide course materials online and respond in time. Instructors noted they also encountered four categories of technological challenges: easy access to necessary computer equipment, technical skills to access computer technology and the e-learning system, technical skills for communication, and the quality of e-learning computer facilities and technology. University administrators interested in solving the issue of the under-use of e-learning would be wise to recognize the challenges instructors face and to provide the necessary policy and practical support to help overcome these challenges if they wish to promote the use of e-learning as a part of the blended delivery of courses.

text: Challenges for e-learning for university instructors in Taiwan Blended courses that include both face-to-face and e-learning have been offered  in many universities in Taiwan but very little research has been undertaken on instructor  perspectives of the challenges they faced in their e-learning teaching. This paper explores the challenges faced by university instructors in a national research-based university in Taiwan. An interpretive paradigm utilizing qualitative and quantitative methods was adopted. The paper outlines the findings from 27 e-learning instructors in in-depth interviews and 55 of 69 e-learning instructors who responded to this open-ended question in the questionnaire. Instructors noted they faced pedagogical, personal, and technological challenges. The findings suggested instructors needed to adopt different pedagogical approaches to work with new media in developing their e-learning courses so new curriculum design, new teaching methods, new ways of assessment, and new interaction approaches were needed. The instructors faced personal challenges in time management and role change if they needed to provide course materials online and respond in time. Instructors noted they also encountered four categories of technological challenges: easy access to necessary computer equipment, technical skills to access computer technology and the e-learning system, technical skills for communication, and the quality of e-learning computer facilities and technology. University administrators interested in solving the issue of the under-use of e-learning would be wise to recognize the challenges instructors face and to provide the necessary policy and practical support to help overcome these challenges if they wish to promote the use of e-learning as a part of the blended delivery of courses.

year: 2008

title: Stemming the colonial environmental tide

authors: Joseph, Robert

subjects: human activities

abstract: Stemming the colonial environmental tide supports an Aotearoa New Zealand context that fundamentally acknowledges mātauranga and tikanga Māori law and shared co-governance and concurrent jurisdiction through 7 Aotearoa New Zealand EBM principles.

text: Stemming the colonial environmental tide Stemming the colonial environmental tide supports an Aotearoa New Zealand context that fundamentally acknowledges mātauranga and tikanga Māori law and shared co-governance and concurrent jurisdiction through 7 Aotearoa New Zealand EBM principles.

year: 2022-05