Fermentative biohydrogen production by anaerobic, Thermophilic bacterium thermoanaerobacterium aciditolerans Trau DAt isoalted from Vietnam

Thermoanaerobacterium aciditolerans bacterium Trau DAt isolated in Vietnam had the hydrogen production capability under the anaerobic condition at 55oC. Using glucose, the dark fermentation of strain Trau DAt for hydrogen production was performed in three different scales: the flask scales under the suitable (1) and optimal (2) conditions, and the automatic fermentor system Bio-Flo 110 (3). Under the suitable condition, the strain Trau DAt produced 330 ml volume total gas (L-1) and hydrogen occupied 42.95% of gas total. Under the optimal condition, the maximum volume total gas of 701 ml (L-1) was obtained and hydrogen occupied of 77.2% total volume gas. Based on results of RSM analysis and pH controlled examination, the dark fermentation of strain Trau DAt was performed under automatic fermentor system scale (Bio-Flo 110). 2.64 L total gas (L-1) was obtained by consuming 92.58% glucose and hydrogen volume occupied 94.85% of gas total. The maximum hydrogen yield of strain Trau DAt was 1.63 mol H2 (mol glucose)-1. Obtained results showed the remarkable potentiality of Trau DAt strain in application to the larger fermentation scale for biohydrogen production in Vietnam

Using of response surface methodology for optimization of biohydrogen production by Clostridium sp. tr2 isolated in Vietnam

Biohydrogen is a clean, renewable, sustainable energy resource due to the highest energy density among all fuels and its combustion has no contribution to the environmental pollution and climate change. Biohydrogen production depends on a number of nutritional and environmental variables. The present paper is to determine the optimum condition for enhanced hydrogen production by a fermentative hydrogen-producing bacterium (designated as Clostridium sp. Tr2) isolated from buffalo-dung in Vietnam. The response surface methodology (RSM) was employed to determine the mutual effects of glucose, yeast extract and iron concentration on its hydrogen production in a batch condition. RSM analysis showed that the highest hydrogen production potential (Ps) was obtained under the condition of 10.18 g L-1 glucose, 2.5 g L-1 yeast extract and 58 mg L-1 FeSO4.7H2O. All three factors had significant influences on the Ps. Glucose and iron concentration, yeast extract and iron concentration were interdependent or there was a significant interaction on Ps. Glucose and yeast extract concentration was slightly interdependent, or their interactive effect on Ps was not significant. Under optimum conditions, the maximum H2 volume of 1080 ml (L medium)-1 were found after 22 h facultative anaerobic fermentation. The experiment results show that the RSM analysis with the central composite design was useful for optimizing the biohydrogen-producing process by newly isolated Clostridium sp. Tr2 in Vietnam

Erratum: Mott Transition in the Mass Imbalanced Ionic Hubbard Model at Half Filling

Erratum: Mott Transition in the Mass Imbalanced Ionic Hubbard Model at Half Filling[Nguyen Thi Hai Yen, Le Duc Anh, Hoang Anh Tuan, Nguyen Toan Thang and Tran Thi Thu Trang, Communications in Physics, Vol. 29, No. 3SI (2019), pp. 305-312]This paper was published on 22 October 2019 with an omission in the text of the author’s list. The author list should read asNGUYEN THI HAI YEN$^1$, LE DUC ANH$^2$, HOANG ANH TUAN$^{1,3,\dagger}$, NGUYEN TOAN THANG$^1$, TRAN THI THU TRANG$^4$ AND NGUYEN THI HUONG$^5$$^1$Institute of Physics, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam $^2$Hanoi National University of Education, Hanoi, Vietnam $^3$Graduate University of Science and Technology, VAST, Hanoi, Vietnam $^4$Ha Long University, Quang Ninh, Vietnam $^5$Thuy Loi University, Hanoi, Vietnam$^{\dagger}$E-mail: [email protected] author’s list has been corrected as of 29 November 2019. The author’s list has been corrected in the electronic version of the journal

Biohydrogen production by fermentive bacterium Clostridium sp. Tr2 using batch fermenter system controlled pH under dark fermentation

Limitation of fuels reserves and contribution of fossil fuels to the greenhouse effect leads to develop a new, clean and sustainable energy. Among the various options, biohydrogen appears as a promising alternative energy source. The fermentative hydrogen production process holds a great promise for commercial processes. Hydrogen production by fermentative bacteria is a very complex and greatly influenced by pH. This paper presents biohydrogen production by bacterial strain Clostridium sp. Tr2. Operational pH strongly affected its hyrogen production. Its gas production rate as well as obtained gas product were roughly increase twice under controlled pH at 6 than non-controlled condition. Dark fermentation for hydrogen production of strain Tr2 was performed under bottle as well as automatic fermenter scale under optimal nutritional and environmental conditions at 30oC, initial pH at 6.5, then pH was controlled at 6 for bioreactor scale (BioFlo 110). Bioreactor scale was much better for hydrogen production of strain Tr2. Clostridium sp. Tr2 produced 0.74 L hydro (L medium)-1 occupying 72.6 % of total gas under bottle scale while it produced 2.94 L hydro (L medium)-1 occupying 95.82 % of total gas under fermenter scale. Its maximum obtained hydrogen yield of Clostridium sp. Tr2 under bioreactor scale Bioflo 110 in optimal medium with controlled pH 6 was 2.31 mol hydro (mol glucose)-1.Dự trữ nhiên liệu có giới hạn và việc sử dụng nhiên liêu hoá thạch góp phần không nhỏ gây hiệu ứng nhà kính dẫn đến cần phải phát triển năng lượng mới, sạch và bền vững. Trong số các giải pháp, hydro sinh học xuất hiện như một nguồn năng lượng thay thế đầy hứa hẹn. Quá trình lên men sản xuất hydro có tiềm năng lớn để áp dụng trong sản xuất thương mại. Tuy nhiên qúa trình này rất phức tạp và chịu ảnh hưởng lớn bởi pH. Nghiên cứu này trình bày sản xuất hydro sinh học do chủng vi khuẩn Clostridium sp. Tr2. Quá trình sản xuất hydro của chủng này bị ảnh hưởng mạnh mẽ bởi pH thay đổi trong quá trình lên men. Tốc độ tạo khí cũng như lượng khí thu được của chủng này tăng gần gấp đôi trong môi trường có duy trì pH ở pH 6 so với môi trường không kiểm soát pH. Quá trình lên men tối sản xuất hydro của chủng Tr2 được thực hiện ở quy mô bình thí nghiệm cũng như bình lên men tự động trong điều kiện môi trường tối ưu ở 30oC, pH ban đầu 6.5, ở qui mô bình lên men tự động (BioFlo 110), pH môi trường sau đó được duy trì ổn định ở pH 6. Lên men sản xuất hdyro của chủng Tr2 trong bình lên men tự động tốt hơn rất nhiều so với lên men trong bình thí nghiệm. Clostridium sp. Tr2 chỉ tạo ra được 0,74 L hydro (L medium)-1 chiếm 72,6 % tổng thể tích khí thu được ở điều kiện lên men bình thí nghiệm trong khi chủng này sản xuất được 2,94 L hydro (L medium)-1 chiếm 95,82 % tổng thể tích khí ở điều kiện lên men tự động. Sản lượng hydro thu được lớn nhất của chủng này trong bình lên men tự động BioFlo 110 trong trong môi trường tối ưu có kiểm soát pH tại pH 6 là 2,31 mol hydro (mol glucose)-1

In-action reflective teaching in Vietnam: A qualitative exploration of practices, influences and implications

Reflective teaching plays a crucial role in the field of education though its intricacies in particular cultural contexts like Vietnam are still little understood. This study aims to investigate reflective teaching practices in more detail within the context of Vietnamese education.  This study used a qualitative methodology and semi-structured interviews with twelve Vietnamese teachers, each representing a different stage of their careers to shed light on the many forms of in-action reflective practices and their implementation, benefits, drawbacks and even cultural influences. The results of this in-depth investigation provided an overview of the wide range of in-action reflective practices that are actively used in the classroom.  The enhancement of adaptive teaching methodologies and the bolstering of student engagement are prominent among the many advantages that were noted.  Teaching in the Vietnamese context also presents unique challenges. Teachers often struggle with the demands of multitasking, the complexities of navigating uncertainties in real-time classroom scenarios   and the predominant challenge of managing large class sizes. Moreover, it was surprising to learn how many Vietnamese cultural, social   and educational factors influenced teacher understanding and use of in-action reflection.  The understanding of reflective teaching practices is enhanced by the research findings which also have broad implications for areas such as instructional strategies, teacher preparation programmes, academic research perspectives and even the development of educational policies.  The study strongly emphasizes the pressing need for more context-specific investigations into reflective teaching and underscores the indispensable role of reflection in fostering an environment conducive to effective teaching and learning

Challenges of Implementing Outcome-Based Assessment in Vietnamese Higher Education – A Qualitative Inquiry

This qualitative study investigates the key challenges faced by university lecturers in implementing outcome-based assessments (OBA) in higher education institutions in Vietnam, a country currently undergoing significant educational transformation. Utilizing a qualitative research design, the study conducted semi-structured interviews with 15 lecturers from diverse academic fields in a institution. The data were thematically coded and interpreted through the lenses of Constructivism, Institutional Theory, and Diffusion of Innovations Theory. Nine major challenges emerged from the findings, including pedagogical hurdles, lack of training and resources, institutional constraints, and technological limitations. These challenges are contextualized within the existing theoretical frameworks and related literature. The study offers critical insights that are deeply rooted in cultural, institutional, and structural variables. These findings are pertinent for educators, administrators, and policymakers in Vietnam and potentially for those in similar educational settings, and they hold broader implications for professional development, institutional policies, technological infrastructure, and cultural shifts within the educational landscape

Multi-faceted identities of teacher assessors: A qualitative study in the Vietnamese educational context

Within the educational landscape of Vietnam, the professional identity of teachers when acting as assessors remains a comparatively uncharted domain and requires further explorations. Consequently, this qualitative investigation was initiated to delve deeper into the intricate identities Vietnamese teachers adopt in their capacities as assessors. Relying upon frameworks such as Constructivist Grounded Theory and Identity Theory, the study meticulously analyzed self-reported narratives from 15 tertiary lecturers based in Vietnam. Through this rigorous analysis, a spectrum of fifteen distinct identities was uncovered. These identities included “Gatekeepers of Knowledge and Competency”, “Nurturers”, “Diplomatists”, “Auditors”, “Confusian Sages”, “Innovators”, “Social Justice Advocators”, “Cultural Mediators”, “Emotional Anchors”, “Scalfolders”, “Technological Navigators”, “Lifelong Learners”, “Community Builders”, “Ethical Guardians”, and “Democratic Facilitators.” Intriguingly, these identities were not merely seen as additional layers to their professional duties; instead, they emerged as foundational components of teachers’ professional self-image. The forces molding these roles are diverse, encompassing deep-seated cultural values, prevailing educational paradigms, and personal lived experiences of educators. Unraveling these identities offers consequential implications for the broader educational sector. It underscores the imperative to holistically re-envision teacher training programs and assessment design, ensuring they resonate with the multifaceted roles educators play in steering both academic achievements and wider societal outcomes

Pencil lead graphite electrochemically modified with polyglutamic acid as a sensor for detection of enrofloxacin in aqueous media

This study investigates the modification of pencil lead graphite electrodes with polyglutamic acid using an effective and fast static method to develop a sensor for the detection of enrofloxacin (ENR). The successful fabrication of pGA on the electrode surface was confirmed by scanning electron microscopy, energy dispersive X-ray analysis, and Fourier-transform infrared spectroscopy. The conditions of electrochemical modification, including the applied potentials and number of cycles in the potentiostatic process, were systematically investigated to determine their effects on the ENR electrochemical response. The pH of the electrolyte media was also explored to elucidate the electrochemical reaction mechanism of ENR. The developed electrochemical sensor was evaluated using square wave stripping voltammetry for ENR detection. Under optimal conditions, the sensor demonstrated good reproducibility with a relative standard deviation of 4.3% (from five measurements) for ENR signal detection. A linear relationship between ENR concentration and its peak current was observed in the concentration range of 0.1 to 5 µM, with a high correlation coefficient of 0.9988. The limit of detection for ENR using the sensor was 0.12 µM. Our findings provide valuable insights into the design and optimisation of pencil lead graphite electrode-based sensors for ENR detection in aqueous media

Research on Factors Affecting Credit Risk of Joint Stock Commercial Banks on Vietnam Stock Market

Design/methodology/approach: The article aims at identifying factors affecting credit risk of commercial banks in Vietnam. The study uses data collected from financial statements of 15 typical joint stock commercial banks out of a total of 27 joint stock commercial banks listed on the Vietnam stock exchange from 2012 to 2022 with panel data of 15 joint stock commercial banks for the period 2012 - 2022. The banks in the research data are the those with the largest total assets in the banking system. After collecting and processing data, research sample includes 165 observations and the study uses E-view software in quantitative analysis to build a regression model to determine the relationship and level of influence of Internal factors to credit risk of listed joint stock commercial banks.   Findings: Research results indicate that factors affecting credit risk of listed joint stock commercial banks include: Ratio of equity to total assets, capital structure of the bank, and operational performance of the banks.   Research, Practical & Social impications: These results confirm the importance of taking into account micro finance factors when making financing. Understanding the impact of these factors and relationships contributes to decision and risk management.   Originality/value: In order to limit credit risk it is necessary to focus on: Ensuring reasonable equity; Stricter control over loan capital; Optimal use of resources

Dry Eyes Status on Des Scale and Related Factors in Outpatients at Vietnam National Institute of Ophthalmology

BACKGROUND: Dry eye (DE) can effect on quality of life by pain, inability to perform certain activities that require prolonged attention (driving, reading,…) and productivity at work and finally effect to Q0L associated with DE. OSDI is scale questionnaire is created team to measure the quality of life related to ocular surface disease. AIM: To describe the dry eye disease according to OSDI scale and related factors of this disease. METHODS: A cross-sectional descriptive study was carried out on outpatients (≥ 16-year-old) who were examined and diagnosed with dry eyes at Vietnam National Institute Of Ophthalmology from April to July 2018. Data was collected using the OSDI questionnaire. RESULTS: The average age of participants was 44.6 years; 80.9% of patients were female; 39.9% were identified having mild dry eye. The related factors have been identified that associated with severe dry eye, including age OR = 1.03 (95%CI: 1.01-1.05, p = 0.005), binocular good vision OR = 0.11 (95%CI: 0.05-0.23; p < 0.0001), medical history OR = 17.09 (95%CI: 2.24-130.25; p < 0.0001), chronic conjunctivitis OR = 0.36 (95%CI: 0.14-0.91; p = 0.027), refractive errors OR = 0.14 (95%CI: 0.04-0.48; p < 0.0001), Sjogren's syndrome OR = 31.13 (95%CI: 7.08-136.76; p < 0.0001). CONCLUSION: Several related factors have been identified associated with severe dry eye, including: age, binocular good vision, medical history, chronic conjunctivitis, refractive errors, Sjogren's syndrome