ẢNH HƯỞNG CỦA MẬT ĐỘ NUÔI LÊN TỐC ĐỘ TĂNG TRƯỞNG VÀ TỶ LỆ SỐNG CỦA CÁ ÔNG TIÊN (PTEROPHYLLUM ALTUM PELLEGRIN, 1930)

Three-day-old Angel fishes (Pterophyllum altum) were utilized to investigate the effect of stocking density on their growth performance and survival rate. The fish were cultured in 25 liter, glass tanks at different treatments of density, including 5 individuals/L, 10 inds/L,              15 inds/L and 20 inds/L (triplicated). The results after 84 days showed that growth and survival rate of angel fish were significantly influenced by stocking density. The length and weight of fish reared at 5 inds/L (9.597±0.002 mm; 11.700± 0.1 g) were the best and significantly higher than fish in the treatment  of 10 inds/L (9.167±0.058 mm; 11.067± 0.208g); 15 inds/L (7,699±0,03 mm; 10.933± 0,057 g) and 20 inds/L (4.928±0.004 mm; 7.900± 0.1g) (P0.05). The survival rate of 5 inds/L treatment 85% was significantly higher than that of other treatments (10 inds/L: 80.0±0,5%; 15 inds/L: 77.0±0,57% and 20 inds/L: 74.6±0.38%). In combination of these two factors, the density of 5 inds/L is recommended in culture of three day old to three month old angel fishes.Cá ông tiên (Pterophyllum altum) sau 3 ngày nở được nuôi trong các bể kính có thể tích 25 lít với các mật độ 5 con/lít, 10 con/lít, 15 con/lít và 20 con/lít (3 lần lặp lại) để làm rõ ảnh hưởng của mật độ đến tốc độ tăng trưởng và tỷ lệ sống của cá. Kết quả sau 84 ngày thí nghiệm cho thấy có sự ảnh hưởng của mật độ nuôi đến tốc độ tăng trưởng và tỷ lệ sống của cá giai đoạn 3 tháng đầu mới nở.Cá được nuôi ở mật độ 5 con/lít có tốc độ tăng trưởng về chiều dài và trọng lượng (9,597±0,002 mm ; 11,700± 0,1 g) là tốt nhất và khác nhau đáng kể so với cá được nuôi ở mật độ 10 con/lít (9,167±0,058 mm; 11,067± 0,208 g) 15 con/lít (7,699±0,03 mm; 10,933± 0,057 g) và 20 con/lít (4,928±0,004 mm; 7,900± 0,1 g) (P0,05). Tỷ lệ sống của cá nuôi ở mật độ 5 con/lít là 85% cao nhất so với các mật độ còn lại (10 con/lít: 80,0±0,5%; 15 con/lít: 77,0±0,57% và 20 con/lít: 74,6±0,38%). Kết quả thí nghiệm cho thấy cá ông tiên mới nở đến 3 tháng tuổi nên nuôi ở mật độ 5 con/lít là tốt nhất

Factors Affecting Successful Quality Assurance Implementation in Vietnamese Higher Education: A Qualitative Study

Quality assurance and accreditation was officially introduced into the higher education system in Vietnam over ten years ago. It is evident that quality assurance has resulted in positive impacts on university management, teaching, learning and research activities. This paper aims to explore factors that aid the successful implementation of higher education quality assurance and accreditation in Vietnam. Through semi-structured interviews with 32 participants, this study identified a number of factors that contributed to quality assurance processes, including awareness of the importance of quality assurance, better institutional manager leadership, support of university lecturers, staff, and students, and the vital responsibility of internal quality assurance staff. These confirm that internal stakeholders play an important role in undertaking quality assurance programmes and activities

Heat Stress Affects Seed Set and Grain Quality of Vietnamese Rice Cultivars during Heading and Grain Filling Period

Environmental stress trigger a variety of rice plant response, ranging from alters seed set, grain yield and grain quality during flowering and grain filling stage.  Efforts are required to improve our understanding of the impact of heat stress on rice production, which are essential strategies in rice cultivation. This article investigated the seed set, yield components and grain yield of Vietnamese rice cultivars (Indica germplasm) under high temperature environment during the flowering and grain filling stage. Six rice cultivars, including popular cultivars and new cultivars of Cuu Long Delta Rice Research Institute, and one popular extraneous cultivar with differences in maturing time, were grown in pots at high temperature (HT) and natural temperature condition as control (CT). All rice cultivars were subjected to the high temperature starting from the heading stage to the harvest maturity, applied by greenhouse effect. The greenhouse has about 25 cm window opening on 3 sides for air ventilation. The seed set rate of the heat-sensitive rice genotypes decreased significantly under HT, leading to a significant reduction in grain yield. The lowest seed set was recorded in “OM4900” (44.3%) and “OM18” (39.9%) under high temperature environment. The lower yield in all rice cultivars at an elevated temperature resulted in a dramatic decrease of filled grains and contributed to a loss of 1000-grain weight. ‘“OM892” is a potential rice cultivar for heat tolerant breeding program due to the seed set percentage was above 80% in both HT and CT conditions. High temperature during the grain filling stage resulted in a decreased amylose and increased chalkiness for all OM cultivars

Cloning and expression of gene FanC-2NT encoding K99-2NT fimbrial antigen of enterotoxigenic Escherichia coli from diarrheic post-weaning piglets

Background and Purpose: The K99 (F5) is one pilus adhesin that mediates the attachment of enterotoxigenic E. coli (ETEC) strains to small intestines to cause to diarrhea in piglets, lambs and newborn calves. In this work, we carried out cloning and expression of the mature peptide of FanC subunit, K99 fimbriae, one of the most common adhesive antigens in E. coli. Materials and Methods: E. coli 2NT strain was isolated from fecal samples of post-weaning piglets with diarrhea. The coding sequence of the mature peptide of K99-2NT subunit was isolated by PCR amplification and cloned into pGEM®-T Easy vector for sequencing using fluorescent dideoxy-terminator method. Expression of K99-2NT protein which was inserted into pET200/D-TOPO vector induced with IPTG. The PCR product and expression level of protein was examined by agarose gel electrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively. Results and Conclusions: We cloned and expressed successfully the mature peptide of K99 subunit with molecular weight of approximately 17.5 kDa from E. coli 2NT strain (named K99-2NT). Nucleotide sequence of the K99-2NT subunit coding region of fanC-2NT gene is 477 bp in length and is 99% similarity with that of fanC gene (accession no: M35282). Highest expression level occurred after 12 h of induction with 0.75 mM IPTG at 37oC. This subunit antigen will be tested for immune response of rat in the next time

Excellent Teacher Training at University of Education, Vietnam National University Hanoi.

This paper discusses the importance of excellent teachers, factors which impact on the quality of teacher training in general, teacher training in Vietnam and the model of excellent teacher training at the University of Education, Vietnam National University in Hanoi in particular

Rice Straw Biochar and Magnetic Rice Straw Biochar for Safranin O Adsorption from Aqueous Solution

This study investigates the adsorption of Safranin O (SO) from aqueous solution by both biochar and magnetic biochar derived from rice straw. Rice straw biochar (RSB) was made by pyrolysis in a furnace at 500 °C, using a heating rate of 10 °C·min−1 for 2 h in an oxygen-limited environment, whilst the magnetic rice straw biochar (MRSB) was produced via the chemical precipitation of Fe2+ and Fe3+. The physicochemical properties of the synthesized biochars were characterized using SEM, SEM- EDX, XRD, FTIR techniques, and N2 adsorption (77 K) and pHpzc measurements. Batch adsorption experiments were used to explore the effect of pH, biochar dosage, kinetics, and isotherms on the adsorption of SO. Experimental data of RSB and MRSB fit well into both Langmuir and Freundlich isotherm models, and were also well-explained by the Lagergren pseudo-second-order kinetic model. The maximum SO adsorption capacity of MRSB was found to be 41.59 mg/g, while for RSB the figure was 31.06 mg/g. The intra-particle diffusion model indicated that the intra-particle diffusion may not be the only rate-limiting step. The collective physical and chemical forces account for the adsorption mechanism of SO molecules by both RSB and MRSB adsorbents. The obtained results demonstrated that the magnetic biochar can partially enhance the SO adsorption capacity of its precursor biochar and also be easily separated from the solution by using an external magnet

Adsorption capacity of chitosan hydrogel beads fabricated from Penaeus monodon shrimp shell waste for safranin o dye

In this study, we extracted chitosan from Penaeus monodon shrimp shell waste and used it as a bio-sorbent to remove safranin O (SO) dye in aqueous solutions. The chitosan adsorbent was characterised by using SEM and FTIR techniques. Batch adsorption experiments were carried out to evaluate the influence of solution pH (3–10), chitosan dosage (0.1–3 g), contact time (1–720 min), and initial SO concentration (10–200 mg·L–1) on adsorption. The results show that the adsorption of SO with chitosan reached equilibrium after 120 min, and after that, an insignificant change in SO removal efficiency was observed. The maximum adsorption capacity of SO, calculated according to the Langmuir model, was 17.86 mg·g–1 under ambient temperature (25 ± 2 °C), pH 7, chitosan dose of 0.2 g, and SO concentration of 50 mg·L–1. The adsorption kinetics followed the pseudo-second-order model with a correlation coefficient R2 of 0.95. The Langmuir and Freundlich adsorption isotherm models described the SO’s adsorption well, with R2 higher than 0.95