Published: 2020-03-31

Efficacy of PCDairy application in optimal ration formulation for milking cows on milk productivity and quality

Nguyen Thanh Hai, Diep Tan Toan
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The aim of this study was to evaluate the efficacy of PCDairy application in optimal ration formulation for milking cows on milk productivity and quality at the Dairy Demonstrative and Experimental Farm with High Technology of Israel in intensive large farming conditions in Ho Chi Minh City, Vietnam from February to May 2019. The experiment was arranged into a randomized complete block design with 2 rations (Control treatment with cows fed the current farm based ration and PCDairy treatment with cows fed the PCDairy corrected ration) and lasted 3 months. Total of 56 Holstein Friesian crossbred cows at the 2nd and 3rd parities were divided into 2 treatments. The results showed that the average milk yield of cows fed the current farm based ration (Control) was 26.59 kg/cow/day and lower than that of cows fed the PCDairy corrected ration (PCDairy) of 29.48 kg/cow/day (p0.05). Dry matter intake/kg milk of cows in control treatment (0.75 kg DMI/kg milk) was higher than that of PCDairy treatment (0.69 kg DMI/kg milk) (p0.05). In brief, PCDairy application improved milk yield and DMI/kg milk, as well as reduced feed cost.

Determination of total polyphenol, saponin contents, antioxidant and antibacterial activities of Melastoma malabathricum leaves by liquid-liquid extraction

Huynh Thanh Duy, Nguyen Van Thanh, Le Nhu Thuy, Nguyen Trieu Nhat Uyen, Nguyen Duc Do
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The present study aims to investigate the total polyphenol and saponin contents, antioxidant and antibacterial activities of Melastoma malabathricum leaves extracts. These fractions were carried out using n-hexane, n-hexane:ethyl acetate (ratio 1:1), ethyl acetate and methanol solvents. The crude extract (CE) exhibited the highest amount of total polyphenol content by using the Folin-Ciocalteu assay. The n-hexane fraction (F1) showed the highest total saponin content which was determined by Vanillin/H2SO4 method. The antioxidant activity of extracts was evaluated by using three different methods including DPPH radical scavenging assay, hydrogen peroxide assay (H2O2) and reducing power assay (Fe3+). The results showed that the activity of the methanol fraction (F4) against DPPH was the strongest, the CE extract was the highest reducing power and the ethyl acetate fraction (F3) illustrated the strongest antioxidant capacity through H2O2 assay. Furthermore, all extracts were also tested for the antibacterial activity by agar well diffusion method at a concentration of 100 mg/mL. F4 showed the highest activity against Escherichia coli and Staphylococcus aureus, while there were no significant differences among all extracts when testing with Lactobacillus acidophilus. These findings provide important evidence that a correlation between the polyphenol content and antioxidant capacity and antibacterial activity. Whereas, the saponin content was no contribution to antioxidant and antibacterial abilities.

Determinants of economic growth in the Mekong Delta provinces

Le Minh Son, Bui Kieu Anh
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The paper, based on the database of 13 provinces in the Mekong Delta in the period of 2010 - 2016, is aimed at analysing the relationship between per capita GRDP growth and the ratio of local investment capital, foreign direct investment and local government expenditure to GRDP, population and human capital (proxied by Labour Training Index - a component of Vietnam Provincial Competitiveness Index), infrastructure and spatialstructure. Multivariate regression results showed little evidence for positive impact of implemented FDI to GRDP per capita, negative impacts of government spending on education, training, vocation, science and techonology to GRDP per capita, in the short-term. Labour quality, infrastructure and spatial concentration are shown to have positive impacts to economic growth. Policy recommendations to the region GRDP growth were then proposed. 

Optimization of condition for pectin extraction from pomelo peel using response surface methodology

Pham Van Hung, Nguyen Duong Phuoc Tuan, Tan Hoang Nam, Nguyen Thi Lan Phi
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The objective of this study was to optimize extraction condition of pectin from the pomelo peel based on the ultrasound-assisted extraction method using response surface methodology. The effect of four independent variables: solid/liquid ratio (1/30, 1/40, 1/50 g/mL), pH values of citric acid (pH 1.5 - 2.5), sonication time (30 - 50 min) and extraction temperature (60 - 80oC) on the yield of pectin extracted from Da Xanh pomelo pomace was analyzed using Box-Behnken design. The high coefficient of determination value (R2 = 0.9299) indicated that the experimental data were fitted to a second order polynomial equation using multiple regression analysis. The model was highly significant because the model F-value was 11.37 with low p-value (p < 0.0001). Therefore, the model could be employed to optimize the extraction process. Optimal experimental extraction condition for the highest pectin yield from pomelo peel (12.4%) were obtained with the solid/liquid ratio of 1/49.5 g/mL, pH of citric acid of 1.5, sonication time of 47 min and temperature of 78oC. The results obtained from validation experiments were consistent with the predicted data.

The preparation of a fine tip calcium ion selective electrode

Nguyen Van Dat, Huynh Lien Huong, Huynh Thanh Tuan, Ho Quoc Phong, Do Vo Anh Khoa, Nguyen Thanh Dat, Ronny Purwadi
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The purpose of this present study is to make a fine tip Ca2+—selective electrode. Detection limit is found at pCa around 7.5 in Ca2+ buffer solution. The changes in EMF induced between two solutions for 10—fold change in Ca2+ concentration are close to 30 mV. This electrode characteristics were found for single—barrelled microelectrodes of 72.6 nm diameter tip and an internal filling solution buffered for pCa of 6.

Teachers’ professional development as a tool to enhance institutional quality: Current practices at a center for foreign languages

Luu Nguyen Quoc Hung
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In this incredibly challenging and complex world, many teaching professionals require continuous learning and support, or professional development. Teachers are always recognized as key players in the education system and therefore professional development of these teachers is crucial if the quality of education is to be enhanced. At a center for foreign languages in Vietnam, professional development activities are always encouraged. Annually, teachers of every level are required to attend certain workshops and structured training and learning sessions, and their participation in these activities are necessary for their performance evaluation related to teaching contracts and pay for performance. The current study has been undertaken with 51 teachers of English at the Center for Foreign Languages in Can Tho University, Vietnam. An online survey was administered to assess the teachers’ perceptions of the effectiveness of the professional development activities and of the influence of these activites on quality of education. After three years of implementation, these programs of professional development have gained initial positive results. There is an increasing number of teachers who have gained necessary language competency and teaching qualifications. Through practical and effective activities such as implementing a new set of curriculum materials, professional discussions, attending workshops or seminars, teachers have taken up opportunities for further academic growth and consequently could enhance the quality of education. From the current practices there are important implications. When educational leaders and managers need to enhance the institutional quality, they should provide appropriate teachers’ professional development programs.

Common grammartical errors in English writing - A case study with second-year students of information technology at HAUI

Nguyen Thi Huyen
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ABSTRACTThis study is conducted to find out common grammatical errors in English writing paragraphs made by the second-year Information Technology students at Hanoi University of Industry (HaUI). Quantitative method was used with data collection instruments including survey questionnaires for seven teachers and 667 students, and 125 randomly chosen students’ weekly paragraph writings in the study.  The findings revealed four most common grammatical errors, namely verb tense, sentence structure, verb form and subject-verb agreement. Besides, the data analysis results also indicated some causes and suitable error correction types to help students avoid these kinds of errors. This paper, hopefully, provides useful information for those who would like to find out effective ways to eliminate grammatical errors in writing in general and in writing paragraphs in particular.

Extraction, isolation and identification of four methoxyflavones from leaves of Muntingia calabura L.

Ngo Quoc Luan, Ngo Khac Khong Minh, Nguyen Phuc Dam, Tiet Bao Tinh, Tran Thi Tuyet Hoa, Nguyen Trong Tuan
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Four known methoxyflavones, namely 5-hydroxy-7-methoxyflavone (1), 5-hydroxy-3,7-dimethoxyflavone (2), 5-hydroxy-6,7-dimethoxyflavone (3) and 5-hydroxy-3,7,8-trimethoxyflavone (4) were isolated from acetone extracts of the leaves of Muntingia calabura L. Their structures were elucidated by modern spectra including UV, IR, ESI-HR-MS, 1D-NMR, 2D-NMR and by comparison with published data.