50 research outputs found

    Arsenate reductase gene from Pityrogramma calomelanos L. enhances tolerance to arsenic in tobacco

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    Arsenic (As) contamination in soil, water and air is an alarming issue worldwide and has serious effects on human health and environment. Arsenic is a naturally occurring element found in rocks, soil, and water, and exposure to high levels of arsenic can lead to a range of health problems. The effects of arsenic contamination can also be felt in the environment, as it can harm plants and animals and disrupt ecological systems. The major purpose of this study was to produce transgenic plants with improved tolerance to and accumulation of arsenic via transformation of arsenate reductase gene (ArsC) into tobacco genome. Transgenic plants were screen by PCR and southern blot. Further, their tolerance and accumulation to arsenic were evaluated. In the result, we have cloned, characterized, and transformed the ArsC gene from Pityrogramma calomelanos L. (PcArsC). Its phylogenetic analysis revealed 99% homology to ArsC gene in GenBank (accession number X80057.1). Moreover, Southern blot analysis showed that ArsC gene was integrated into the tobacco genome as a single-copy. These single-copy transgenic lines showed much higher tolerance to and accumulation of As than wild type, with no other phenotypes observed. These results demonstrated that Pityrogramma calomelanos ArsC gene can improve arsenic tolerance and accumulation in transgenic tobacco lines. Thus, using Pityrogramma calomelanos L. ArsC gene for genetic engineering has potential implications in the decontamination of arsenic-containing soil

    THE RELATIONSHIPS BETWEEN STUDENTS’ SELF-CONFIDENCE AND THEIR ENGLISH-SPEAKING PERFORMANCE: A CASE STUDY OF ENGLISH-MAJORED STUDENTS AT A PRIVATE UNIVERSITY IN VIETNAM

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    This research aimed to discover the relationships between students' self-confidence and their English-speaking performance. In our research, self-confidence was divided into three components which are affective confidence, behavioral confidence, and cognitive confidence. In addition, speaking performance included eight components which are vocabulary, grammar, pronunciation, fluency, coherence, comprehension, task, and content. A sample of 150 English-majored students at a university in Vietnam was surveyed in this study by using a convenience sampling technique, and then conducting semi-structured interviews to seek for qualitative information from 10 participants out of 150. The result from our study showed that there are significant relationships between the two variables. The more confident the students are, the more accomplished they would be in the presenting procedure since they have superior cognition and understand how to modify their learning methods to build a comprehensive individual in learning English language. We expect that these findings can help students adjust their learning methods to improve their self-confidence as well as English speaking performance and by that way, universities can add more speaking-related subjects so that students can have more opportunities to speak and learn more speaking skills.  Article visualizations

    Genetic susceptibility to Plasmodium falciparum malaria : association and functional analyzes studies of candidate genetic variants located in the regions genetically related to malaria

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    Dans cette thèse, nous avons étudié l'influence de plusieurs variants génétiques situés dans les régions chromosomiques 5q31-q33, 6p21, et 17p12, pour lesquelles une liaison génétique avec des phénotypes de paludisme a été montrée.Les gènes NCR3 et TNF, qui sont situés dans la région chromosomique 6p21, ont été associés au paludisme dans une population vivant au Burkina Faso. Nous avons répliqué ces études dans une population congolaise afin deconfirmer les associations des polymorphismes avec les accès palustres simples et la parasitémie symptomatique. Nos résultats montrent que le polymorphismeNCR3-412 est associé avec les accès palustres simples au Congo, et que les polymorphismes TNF-308, TNF-244, et TNF-238 sont associés avec les accès palustres simples ou la parasitémie symptomatique. En outre, nos analyses bioinformatiques suggèrent que les polymorphismes TNF-244 et TNF-238 agissent en synergie pour modifier le site de fixation pour au moins un facteur de transcription.Les deux gènes HS3ST3A1 et HS3ST3B1, qui sont situés dans la région chromosomique 17p12, sont impliqués dans la biosynthèse des heparanes sulfates. Dans cette étude, nous avons étudié l'association d’un polymorphisme situé dans le promoteur de HS3ST3A1 avec les accès palustres simples et la parasitémie symptomatique, et n’avons détecté aucune association. Nous avons étudié en outre le gène NDST1, situé dans la région chromosomique 5q31-q33, et qui code également pour une enzyme impliquée dans la voie héparane sulfate. Des résultats préliminaires encourageants soutiennent l'hypothèse que la variation génétique de NDST1 influence la parasitémie asymptomatique.In this thesis, we investigated the influence of some genetic variants located within chromosomes 5q31-q33, 6p21, and 17p12, which have been shown to be linked to malaria phenotypes. The genes NCR3 and TNF, which are located in the chromosomal region 6p21, have been reported to be associated with malaria in Burkina Faso population. We have replicated those studies in Congolese population to evaluate the associations of the SNPs in those genes with mild malaria attack and Plasmodium parasitemia. The results showed that the variant NCR3-412 is associated with mild malaria in Congo, and TNF-308, TNF-244, and TNF-238 are associated with mild malaria attack, maximum parasitemia, or both. In addition, bioinformatic studies suggest that TNF-244 and TNF-238 synergise to alter the binding of transcription factors.The two genes HS3ST3A1 and HS3ST3B1, which are located in chromosomal regions 17p12, are involved in the heparan sulfate proteoglycan biosynthesis. In this study, we further investigated the association of the polymorphisms in these genes with mild malaria attack and maximum parasitemia. However no association was found. We further studied the NDST1 gene, which is located within chromosome 5q31-q33, and which encodes the bifunctional enzyme N-deacetylase/ N-sulfotransferase 1, and also participates in the heparan sulfate synthesis . Encouraging results support the hypothesis that NDST1 variation influence controlling parasitemia. Further association and functional studies are needed to validate the role of NDST1 in malaria infection. More generally, the enzymes involved in the heparan sulfate pathway might play a key role in controlling malaria infection

    Catalytic partial oxidation of methyl acetate as a model to investigate the conversion of methyl esters to hydrogen

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    Rhodium, platinum, copper, palladium, and rhodium-ceria catalysts were investigated in the catalytic partial oxidation of methyl acetate, the simplest methyl ester, to better understand the conversion of biodiesel to hydrogen. Only rhodium and rhodium-ceria catalysts allowed for an autothermal reactor operation. Both catalysts were active in producing hydrogen, carbon monoxide, water, and carbon dioxide, although the rhodium-ceria catalyst showed the greater methyl acetate conversion and the greater hydrogen and carbon monoxide selectivities. A low C/O feed ratio favored the methyl acetate conversion, the hydrogen selectivity, and the carbon monoxide selectivity. Furthermore, a high gas hourly space velocity also improved the reactor performance. According to the experimental data, it appears that the oxidation of methyl acetate forms carbon monoxide and water as a primary step, instead of carbon dioxide and water as with the combustion reaction. In general, methyl acetate does not yield more synthesis gas than biodiesel. The methyl ester functional group limits the hydrogen yield and hence new catalysts should be developed and investigated in order to better target the decomposition of methyl esters to hydrogen

    Outsourcing Reverse Logistics for E-Commerce Retailers: A Two-Stage Fuzzy Optimization Approach

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    On the heels of the online shopping boom during the Covid-19 pandemic, the electronic commerce (e-commerce) surge has many businesses facing an influx in product returns. Thus, relevant companies must implement robust reverse logistics strategies to reflect the increased importance of the capability. Reverse logistics also plays a radical role in any business’s sustainable development as a process of reusing, remanufacturing, and redistributing products. Within this context, outsourcing to a third-party reverse logistics provider (3PRLP) has been identified as one of the most important management strategies for today’s organizations, especially e-commerce players. The objective of this study is to develop a decision support system to assist businesses in the selection and evaluation of different 3PRLPs by a hybrid fuzzy multicriteria decision-making (MCDM) approach. Relevant criteria concerning the economic, environmental, social, and risk factors are incorporated and taken into the models. For obtaining more scientific and accurate ranking results, linguistic terms are adopted to reduce fuzziness and uncertainties of criteria weights in the natural decision-making process. The fuzzy analytic hierarchy process (FAHP) is applied to measure the criteria’s relative significance over the evaluation process. The fuzzy technique for order preference by similarity to an ideal solution (FTOPSIS) is then used to rank the alternatives. The prescribed method was adopted for solving a case study on the 3PRLP selection for an online merchant in Vietnam. As a result, the most compatible 3PRLP was determined. The study also indicated that “lead time,” “customer’s voice,” “cost,” “delivery and service,” and “quality” are the most dominant drivers when selecting 3PLRLs. This study aims to provide a more complete and robust evaluation process to e-commerce businesses and any organization that deals with supply chain management in determining the optimized reverse logistics partners

    Solving Order Planning Problem Using a Heuristic Approach: The Case in a Building Material Distributor

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    For building material distributors, order planning is a key process as a result of the increase in construction projects’ scale and complexity. In this paper, the integration of simulation modeling and the response surface methodology (RSM) is presented to solve an order planning problem in the construction supply chain. The interactions of various factors are examined to observe their effects on key system measurements, and a combination of factor levels is determined to achieve the optimal performance. RSM is applied to find the possible values of the optimal setting for system responses, which consists of three main steps: central composite design (CCD), Box–Behnken design (BBD), and a comparison of both designs. The model is tested with a realistic case study of a building material distributor in Vietnam to demonstrate its effectiveness. Controllable factors (independent variables), which are the review period (T), order quantity (Q), and safety stock (SS), are found to significantly affect system responses, which are the total cost (TC) and customer service level (CSL). The results provide the best settings of factor levels that produce the possible minimum TC and maximum CSL. The developed framework could be applied as a useful reference for decision-makers, purchasing managers, and warehouse managers to obtain the most suitable order policy for a robust order planning process

    An Investigation into the Perspectives of Elementary Pre-Service Teachers on Sustainable Development

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    Teachers in elementary schools play a crucial role in educating children about sustainable development. Therefore, the concept of sustainable development is essential for elementary pre-service teachers to be ready for their future careers. This study used the sequential mixed methods design to investigate the relationship between the sustainable development perspectives of elementary pre-service teachers in Southern Vietnam and the current teacher training curriculum. The EDINSOST sustainability questionnaire was distributed to 392 participants in order to measure four dimensions of sustainable development: critical contextualization of knowledge, sustainable use of resources, participation in community processes, and ethics. A set of six interview questions was conducted with eight participants, focused on their understandings of sustainable development and the evaluation of the curriculum on sustainable development. Quantitative findings revealed that elementary pre-service teachers rate moderately on all dimensions; however, the knowledge is slightly higher than the behavior. Moreover, there were variations in perspectives based on pre-service teachers’ grade level and gender. Qualitative findings suggested the lack of sustainable development perspectives amongst pre-service teachers and the gaps in the teacher training curriculums regarding sustainable development. Finally, detailed discussions regarding the implementation of sustainable development in the training curriculum were provided

    A Hybrid OPA and Fuzzy MARCOS Methodology for Sustainable Supplier Selection with Technology 4.0 Evaluation

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    The concern of sustainable supplier selection has been raised recently in organizations’ decision making to enhance their competitiveness. Many tools have been developed to support supplier evaluation, yet the factors of Industry 4.0 (I4.0) have been ignored despite their impact on sustainable performance. Hence, this paper aims to include the technology of I4.0 as the criteria to evaluate the competence of suppliers in sustainability. Multiple-criteria decision making (MCDM) has been used to build decision-making systems; thus, this study employed two advanced methods of MCDM, the ordinal priority approach (OPA) and measurement of alternatives and ranking according to compromise solution (MARCOS) in a fuzzy environment. To test the feasibility of the proposal, five manufacturers of Vietnam’s leather and footwear industry were hypothetically assigned. Firstly, the evaluation criteria were weighted by OPA. Then, the ranking of alternatives was determined by fuzzy MARCOS. The results show that “green image”, “green product innovation”, “cloud computing”, “service level”, and “blockchain” are the topmost significant criteria in evaluating sustainable practices in the supply chain from the I4.0 perspective. Furthermore, sensitivity and comparison analyses were carried out to verify the robustness of the methodology. The outcomes of this paper contribute a new model of decision making with respect to the involvement of sustainability and I4.0

    A Two-Stage Multi-Criteria Supplier Selection Model for Sustainable Automotive Supply Chain under Uncertainty

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    Sustainable supplier selection (SSS) is gaining popularity as a practical method to supply chain sustainability among academics and practitioners. However, in addition to balancing economic, social, and environmental factors, the emergence of the COVID-19 pandemic has affected the selection of long-term suppliers to ensure sustainable supply chains, recover better from the pandemic and effectively respond to any future unprecedented crises. The purpose of this study is to assess and choose a possible supplier based on their capability to adapt to the COVID-19 epidemic in a sustainable manner. For this assessment, a framework based on multi-criteria decision making (MCDM) is provided that integrates spherical fuzzy Analytical Hierarchical Process (SF-AHP) and grey Complex Proportional Assessment (G-COPRAS), in which spherical fuzzy sets and grey numbers are used to express the ambiguous linguistic evaluation statements of experts. In the first stage, the evaluation criteria system is identified through a literature review and experts’ opinions. The SF-AHP is then used to determine the criteria weights. Finally, the G-COPRAS method is utilized to select sustainable suppliers. A case study in the automotive industry in Vietnam is presented to demonstrate the proposed approach’s effectiveness. From the SF-AHP findings, “quality”, “use of personal protective equipment”, “cost/price”, “safety and health practices and wellbeing of suppliers”, and “economic recovery programs” have been ranked as the five most important criteria. From G-COPRAS analysis, THACO Parts (Supplier 02) is the best supplier. A sensitivity study was also conducted to verify the robustness of the proposed model, in which the priority rankings of the best suppliers are very similar. For long-term development and increased competitiveness, industrial businesses must stress the integration of response mechanisms during SSS implementation in the COVID-19 epidemic, according to the findings. This will result in significant cost and resource savings, as well as reduced environmental consequences and a long-term supply chain, independent of the crisis

    A Two-Stage Multiple Criteria Decision Making for Site Selection of Solar Photovoltaic (PV) Power Plant: A Case Study in Taiwan

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    At the heart of Covid-19 responses, the transition from fossil sources to green energy is an urgent issue for nations to address the crisis and secure sustainable economies. As a country in a seismically active zone that relies heavily on imported fossil fuels, Taiwan is vigorously taking the next step in renewable energy development, which is pivotal to securing its position in global supply chains. Solar energy is today the most suitable renewable energy source for Taiwan. However, land prices and policies, and challenges of scale still hinder its development. In this context, identifying optimal sites for solar photovoltaic (PV) construction is a crucial task for major energy stakeholders. In this paper, a two-stage approach, combining the data envelopment analysis (DEA) models and the analytic hierarchy process (AHP), has been done for the first time to identify the most suitable locations among 20 potential cities and counties of Taiwan for constructing solar PV farms. DEA models were applied to filter out the areas with the most potential by measuring their efficiency indices with temperature, wind speed, humidity, precipitation, and air pressure, as inputs, and sunshine hours and insolation, as outputs. The locations with perfect efficiency scores were then ranked with the AHP method. Five selected evaluation criteria (site characteristics, technical, economic, social, and environmental) and sub-criteria of each were utilized to prioritize the locations with solar energy potential. AHP was used to determine the relative weights of the criteria and sub-criteria and the final weights of the areas. For criteria weighting results, “support mechanisms,” “electric power transmission cost,” and “electricity consumption demand” with weights of 0.332, 0.122, and 0.086, respectively, were found as the most significant sub-criteria. The final ranking suggests Tainan, Changhua, and Kaohsiung as the top three most suitable cities for constructing solar PV energy systems
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