Browsing by Author "Zhang, Wen-Xin"

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Ability of an alkali-tolerant mutant strain of the microalga Chlorella sp AT1 to capture carbon dioxide for increasing carbon dioxide utilization efficiency
(2017-11-01)
Kuo, Chiu-Mei
;
Lin, Tsung-Hsien
;
Yang, Yi-Chun
;
Zhang, Wen-Xin
;
Lai, Jinn-Tsyy
An alkali-tolerant Chlorella sp. AT1 mutant strain was screened by NTG mutagenesis. The strain grew well in pH 6-11 media, and the optimal pH for growth was 10. The CO2 utilization efficiencies of Chlorella sp. AT1 cultured with intermittent 10% CO2 aeration for 10, 20 and 30 min at 3-h intervals were approximately 80, 42 and 30%, respectively. In alkaline medium (pH = 11) with intermittent 10% CO2 aeration for 30 min at 3-, 6- and 12-h intervals, the medium pH gradually changed to 10, and the biomass productivities of Chlorella sp. AT1 were 0.987, 0.848 and 0.710 g L-1 d(-1), respectively. When Chlorella sp. AT1 was aerated with 10% CO2 intermittently for 30 min at 3-h intervals in semi-continuous cultivation for 21 days, the biomass concentration and biomass productivity were 4.35 g L-1 and 0.726 g L-1 d(-1), respectively. Our results show that CO2 utilization efficiency can be markedly increased by intermittent CO2 aeration and alkaline media as a CO2-capturing strategy for alkali-tolerant microalga cultivation.
An efficient Photobioreactors/Raceway circulating system combined with alkaline-CO2 capturing medium for microalgal cultivation
(2018-10-01)
Kuo, Chiu-Mei
;
Jian, Jhong-Fu
;
Sun, Yu-Ling
;
Lin, Tsung-Hsien
;
Yang, Yi-Chun
High efficiency of microalgal growth and CO2 fixation in a Photobioreactors (PBRs)/Raceway circulating (PsRC) system combined with alkaline-CO2 capturing medium and operation was established and investigated. Compared with a pH 6 medium, the average biomass productivity of Chlorella sp. AT1 cultured in a pH 11 medium at 2L min(-1) circulation rate for 7 days increased by about 2-fold to 0.346g L-1 d(-1). The maximum amount of CO2 fixation and CO2 utilization efficiency of Chlorella sp. AT1 could be obtained at a PBRs to Raceway ratio of 1:10 in an indoor-simulated PsRC system. A similar result was also shown in an outdoor PsRC system with a 10-ton scale for microalgal cultivation. Under the appropriate circulation rate, the stable growth performance of Chlorella sp. AT1 cultured by long-term semi-continuous operation in the 10-ton outdoor PsRC system was observed, and the total amount of CO2 fixation was approximately 1.2kg d(-1) with 50% CO2 utilization efficiency.
Exploring the Impacts of Cognitive and Metacognitive Prompting on Students\' Scientific Inquiry Practices Within an E-Learning Environment
(2015-02-11)
Zhang, Wen-Xin
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Hsu, Ying-Shao
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Wang, Chia-Yu
;
Ho, Yu-Ting
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教育研究所
This study explores the effects of metacognitive and cognitive prompting on the scientific inquiry practices of students with various levels of initial metacognition. Two junior high school classes participated in this study. One class, the experimental group (n = 26), which received an inquiry-based curriculum with a combination of cognitive and metacognitive prompts, was compared to the other class, the comparison group (n = 25), which received only cognitive prompts in the same curriculum. Data sources included a test of inquiry practices, a questionnaire of metacognition, and worksheets. The results showed that the mixed cognitive and metacognitive prompts had significant impacts on the students\' inquiry practices, especially their planning and analyzing abilities. Furthermore, the mixed prompts appeared to have a differential effect on those students with lower level metacognition, who showed significant improvement in their inquiry abilities. A combination of cognitive and metacognitive prompts during an inquiry cycle was found to promote students\' inquiry practices.
Supporting technology-enhanced inquiry through metacognitive and cognitive prompts: Sequential analysis of metacognitive actions in response to mixed prompts
(2017-07-01)
Hsu, Ying-Shao
;
Wang, Chia-Yu
;
Zhang, Wen-Xin
;
教育研究所
;
Institute of Education
The aim of this study was to develop and examine supports for inquiry practices in computer-based learning environments (CBLEs). Two kinds of supports for inquiry practices were developed, namely cognitive and metacognitive prompts. We employed a multiple case study design to analyze students' metacognitive reactions to these two kinds of prompts and the fading effect on the regulation process using a sequential analysis technique. The results of this study indicate that the high level inquiry group performed not only more metacognitive actions of monitoring and evaluating, but also performed them in different sequences than the less successful students (the middle and low level inquiry groups) during the prompted inquiry tasks. The sequential analysis in this study identified the students' crucial learning patterns of successful inquiry practices in both the structured and guided inquiry stages. The findings can be used to explore the possible alignment between scaffolding and learning behaviors, and the mechanism of fading for inquiry-based learning in CBLEs. (C) 2016 Elsevier Ltd. All rights reserved.