Published: 2021-05-04

Isolation and screening of carotenoid-producing Bacillus spp. from seashore saline soil and seawater at Hon Son islet

Lam Bang Hong, Ngoc Huynh Nguyen, Dat Nguyen Le Thanh, Nguyen Minh Chon
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Carotenoids are natural pigment compounds with a variety of colors. They are antioxidants and boost the immune system. It is interesting to examine strains of bacteria capable of producing carotenoids applied in the food industry, animal feed, and aquaculture. Rach Gia bay of Kien Giang province has a good ecosystem, and the carotenoid-producing microorganisms in these regions are very plentiful. However, there are fewer studies about them in this region. This study was conducted to isolate and select carotenoids-producing Bacillus from Hon Son islet of Rach Gia bay. Seashore saline soil and seawater samples were shocked at 65°C in 1 hour and plated on Difco sporulation medium. Colored colonies of bacteria were selected and incubated at 37°C on Difco sporulation medium. Pigments from these isolates were extracted in the mixture of methanol and chloroform (with the ratio 1:2 of v/v). The extracted solutions were scanned absorbance by spectrophotometer at the wavelength range from 400 to 600 nm. Bacterial isolates were identified by 16S rRNA sequencing. Twenty carotenoid-producing bacterial species were isolated, including five colony colors such as pale yellow, yellow, yellow-orange, pale pink, and pink. They were Gram-positive, positive - catalase test, motile, and endospore-forming. The results of extracted solutions from 20 bacterial species indicate that all the extracts have absorbance from 400-600 nm, this is the popular absorbance of carotenoids. Two high-carotenoid-producing species (HS3-7 and HS8-3) were analyzed the 16S rRNA gene sequence. They were showed high similarity with Bacillus vietnamensis species Marseille-P799 and Bacillus infantis species NRRL B-14911,...

Controlling the external device in real-time using eeg brain signals based on eyes states

Hoang Dung Nguyen, Thach Nguyen Co, Hien Huynh The, Ngan Nguyen Mai
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The paper proposes a new method to control external device in real-time using electroencephalography-based brain signals. The brain signals of a healthy female student at F7 and F8 channels are recorded from Emotiv Epoc+. They are filtered using a combination of wavelet approach and recursive least square estimation to remove unwanted noises. Open and closed eyes states are extracted from filtered brain signals. The support vector machine approach is applied to classify two states of eyes (open and closed). The classified eyes states are utilized to generate the on and off commands, respectively. Those commands are sent to an Arduino control board to control on and off states of the light. Experimental results showed that the average accuracy of two control commands is 81.6%. The obtained results promise for extraction of more commands that can be utilized for applications in daily life.

Bimetallic CuCo-Zeolitic imidazole frameworks (CuCo-ZIFs): Synthesis and characterization

Dang Huynh Giao, Vi Truong Tuong, Ngan Ho Thi Thu, Binh Nguyen Van, Ho Ngoc Tri Tan, Pham Van Toan
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A kind of bimetallic Cu/Co zeolitic imidazole frameworks (CuCo-ZIFs) has been successfully synthesized in ethanol solvent by ultrasound method. The morphology, structural features and physicochemical properties of CuCo-ZIFs were analyzed by several techniques including powder X-ray diffraction, thermo-gravimetric analysis, Fourier-transform infrared spectroscopy,, energy-dispersive X-ray spectroscopy, scanning electron microscope, and nitrogen physisorption measurements. The results showed that CuCo-ZIFs nanocrystals demonstrated a ZIF-67-like polyhedral morphology with high thermal stability. The Brunauer-Emmett-Teller surface areas of CuCo-ZIFs were achieved approximately 1172 m2/g, while its Langmuir surfaces areas were achieved approximately 1907 m2/g.

Establishment of a spontaneously started sourdough in Vietnam

Phuong Le Vu Lan, Sua Huynh Thi, An Le Tri
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The use of sourdoughs in bread baking in Vietnam has recently been increased but little is known about microorganisms in those sourdoughs. This study was to assess changes in pH value and microbial density of a sourdough from bread flour (BF) and a sourdough from all-purpose flour (AF) during propagation. The results showed that the type of flour did not cause a significant difference in pH changes, but it could contribute to the distinct levels of lactic acid bacteria (LAB) and yeast in the two sourdoughs. The BF sourdough gained proper maturation in 15 days when it reached pH of 3.69, 1.3 x 109 CFU g-1 LAB and 7.4 x 108 CFU g-1 yeast. Meanwhile, the AF sourdough had lower levels of LAB and yeast (3.9 x 108 CFU g-1 and 1.0 x 108 CFU g-1, respectively). Sequencing analysis revealed the presence of Lactobacillus plantarum in the BF sourdough on the 10th and 15th days of the propagation process. Wickerhamomyces anomalus was found on the 10th day while Saccharomyces cerevisiae was detected on the 15th day. This sourdough can be used in further studies to assess the benefits of sourdough in bread baking.

ELT pedagogical reforms: EFL high-school teachers’ perceptions and responses

Thao Le Thi Thanh, Le Xuan Mai
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Educational change, particularly English language teaching (ELT) pedagogical reforms, has received much attention from language researchers in the era of globalization and internationalization. Despite the recognition of problems in implementation, ELT pedagogical reforms have been widely introduced and adopted in schools all over the world, particularly in Vietnam. What English teachers’ overall perceptions, understanding, and practices are, and what influential factors on response to ELT pedagogical reforms are, the major foci in this study. The data were collected from 102 teachers of English as a Foreign Language (EFL) in different high-schools (grades 10, 11 and 12) in the Mekong Delta. The results from the questionnaire and interview revealed that the teachers highly perceived ELT pedagogical reforms. Moreover, the results also showed that the teachers well understood the values of ELT pedagogical reforms. However, the findings also showed that the teacher’s practices of ELT pedagogical reforms were above average and that their practices did not match with their understanding of the values of ELT pedagogical reforms. Besides that, from the findings, the EFL high-school teachers were relative strongly influenced, both the internal and external factors; the main influential factors are students’ learning outcomes after implementing ELT pedagogical reforms, teachers’ attitudes towards the adoption of these reforms, and teachers’ self-efficacy on their teaching. Moreover, the study contributed an interesting finding to the literature that teaching and learning culture is a factor that influenced teachers’ responses. Based on these findings, implications were made for enhancing teachers’ teaching practices in response to ELT pedagogical...

Effects of computer-based feedback and formative assessment on learning outcomes

Thien Ngo Van
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The purpose of the study is to examine the effect of student response systems in computer-based feedback and formative assessment on learning outcomes. The backward design course is a tool to be applied for collecting necessary assessment evidence. The quasi-experimental research design involves collecting pretest and posttest data on students assigned to the control and the experimental group. The sample group consists of 148 college students randomly selected from two of the eight classes of electrical and electronics students at Cao Thang Technical College in Ho Chi Minh City, Vietnam. The research findings revealed that the experimental group, in which student response systems were applied, got better results than the control group, who did not apply them. Results show that using student response systems for technology-based feedback and formative assessment is vital and meaningful not only for teachers but also for students in the teaching and learning process.

Teaching English online at a center for foreign languages: Challenges and opportunities

Luu Nguyen Quoc Hung
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With the rapid development of technology for the past decades, online instruction has emerged as an alternative mode of teaching and learning and a substantial supplement to traditional teaching. At the Center for Foreign Languages, Can Tho University, online teaching has been growing recently, particularly due to many schools’ closures because of the Covid-19 pandemic. This small-scale study was conducted with a group of online teachers of English of the Center for Foreign Languages with the aim to understand the teachers’ challenges as well as their opportunities to develop online courses. The results revealed that the primary challenge of online teaching was about technology impacts on both teachers and learners. There were also suggestions for both administrators and teachers for enhancing quality of online teaching.

Climate change-related risk adaptation in striped catfish, tilapia and shrimp farming systems in the Mekong Delta, Vietnam

Vo Nam Son, Minh Hai Dao, Nguyen Do Quynh, Nghia Long Van, Truc Phan Thi Thanh, Anh Nguyen Quynh, Nguyen Do Quynh, Boripat Lebel, Louis Lebel, Nguyen Thanh Phuong
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This study aims to determine climate change-related risk (CCR) impacts, responses of farmers, and assistant activities in tilapia cage culture (TC), striped catfish nursery (SCN), striped catfish grow-out (SCG), improved extensive shrimp (IES) and intensive shrimp (IS) systems. A survey of 601 farmers in the Mekong Delta, Vietnam, was conducted using clustered sampling. Intense rainfall events and rapid changes in temperature affected all five surveyed farm systems. Extreme high temperatures impacted the TC, IES and IS systems, while extreme low temperatures impacted the striped catfish groups (SCN and SCG). Striped catfish farming systems were more sensitive to low temperatures in comparison to shrimp and tilapia. For risk management purposes, increasing pond dike height was applied in the SCN and SCG farming systems. While increased pond depth was observed in the SCN, SCG and IS systems, the IS and SCN systems had higher counts of additional pond construction. Water quality was monitored and feed supplements/medicines were used by farmers in all five farm systems; however, these activities were higher for the SCN, SCG and IS systems than for the TC and IES groups. Reduced stocking density was observed in TC, SCN, SCG and IS, but not in IES. In addition, the use of aerators or mixers was the most-employed solution in the IS system. Amongst information sources of climate-related risks, television was found to be the most important, followed by neighbouring farmers and the Department of Fisheries (DOF)...

Investigation of antioxidant activity of protein hydrolysate derived from baby clam (Corbiculidae sp.) broth

Tam Vo Dinh Le, Minh Tran Cao, Hoai Le Duc, Khang Duong Lap, Anh Nguyen Ngoc Quynh
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This study is aimed to bring baby clam broth (BCB) into antioxidant proteolysate utilizing enzymatic hydrolysis. Chemical compositions of BCB were firstly analyzed, followed by investigating the effects of enzymatic hydrolysis parameters involving in enzyme type, pH, temperature, enzyme:substrate (E:S) ratio and hydrolysis time on antioxidant of BCB proteolysate. It can be seen from the result that the BCB owned the moisture content, protein content, lipid content, and ash content of 97.55±0.89%, 1.52±0.16%, 0.09±0.02%, and 0.37±0.04%, respectively. The BCB proteolysate, under the hydrolysis condition including Flavourzyme, pH 7, 50°C, E:S ratio of 5 U/g protein and hydrolysis time of 50 min, exhibited the highest 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) cation ratio (ABTS●+) scavenging activity of 770.67±28.33 µM Trolox Equivalent (µM TE) (7.1 and 2.5 times lower than those of vitamin C and butylated hydroxytoluene (BHT), in order) and ferric reducing antioxidant power (FRAP) value of 245.26±7.37 µM TE (11.6 and 4.0 folds lower than those of vitamin C and BHT, respectively). This study suggests a new use of the BCB, antioxidant proteolysate which could be applied as a functional food or natural antioxidant additive, substituting for synthetic compounds.

Corporate cultural characteristics of startups in developed countries and recommendations for vietnamese small businesses

Trung Nguyen Quang
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In the situation of globally connected digital economy, changes in organizational structure and smart corporate governance are placing the entrepreneurial structures in the face of unprecedented decisions on building and developing corporate culture. By the method of literature review, desk review on the basis of secondary data is a typical study case on the cultural characteristics of startups in the United States of America (USA), China, Korea, Japan, Singapore and European Union. Based on the experiences from developed countries, some recommendations has been proposed for small business founders in Vietnam. It is expected to contribute an additional perspective on digital business in the era of globalization.