Vol. 19 No. 8 (2021)

In Vietnam, local maize varieties are increasingly reduced in the cultivated areas due to the development of hybrid maize varieties. However, local maize genetic resources have numerous precious traits and are of high value in maize breeding. The local maize varieties are still grown in some regions, hence, the collection and evaluation of those varieties should be imperatively carried out for conservation and exploitation. In this study, 30 accessions of indigenous maize varieties were collected from Lai Chau and Dien Bien provinces were characterized for their agro-biological traits. The results showed that 24 accessions (86.7%) were over 120 days in growing period. Plant height ranged from 161.2 to 277.0cm. The length of corn was from 12.7 to 19.4cm. Corndiameter was from 2.87 to 4.93cm. Number of rows per corn was 9.2 to 13.2 rows. Number of seeds in rows was from 13.4 to 34.8. Similarity coefficients of maize varieties were fluctuated from 0.19 to 0.43 and were then classified into two main groups, group one with 6 varieties, and group two with 24 accessions, respectively. High diversity of agro-biological characteristics was found in the maize accessions collected from Lai Chau and Dien Bien provinces. The collected maize accessions could be used for maize breering programs in Vietnam.

The study was conducted in order to determine the pathological and biological features of the feline panleukopenia virus causing disease in domestic cats in Hanoi. In the present study,eight cats from 2 months to 1 year-old-age were observed for clinical symptoms, and collected samples were collected for a histopathology examination. The results showed that feline leukopenia caused by FPV hadsymptoms of vomiting, dehydration, and diarrhea, etc. Gastrointestinal lesions included congestion, mucosal hemorrhage, bloody substance contents. The major microscopic lesions were proliferation of the intestinal lymphatic nodules, with epithelial cell degeneration, collapsed villiofthe intestine. The number of lymphocytes decreased sharply in the mesenteric lymph nodes, whereas monocytes and macrophages increased. The virus isolationresults on CRFK cells have obtained 5 different virus strains with titers ranging from 1.77 108to 1.77 109TCID50/ml. The present findings on the growth curve of the virus showed that with the multiplicity of infectious dose MOI = 0.001, the highest viral titration was 1010,5TCID50/ml after 36 hours post-infection.

This study aimed to examine the correlation between salinity, organic matter content (TOM) and sediment structure on the distribution of Polychaetes in Cu Lao Dung district, Soc Trang province. The study was conducted with 2 sampling periods in the rainy season (9/2019) and dry season (3/2020) at 24 sites, divided into 8 locations denoted as N1-N8 thereafter, in which the inland area from N1-N5 and the mangrove area from N6-N8. The results showed that salinities ranged from 0.1-18.6‰. Salinity in the dry season was higher around 8 times than that in the rainy season. Similarly, total organic matter (TOM) in the dry season was also higher than that in the rainy season. At all locations, the percentage of silt was much higher than clay and sand. A total of 13 species belonging to 12 genera, 10 families and 5 orders was identified in the study area, in which number of species varied from 1-7 at each sampling site. Density of polychaetes varied from 3-117inds m-2among locations and densities of each species highly varied with a range of 0-71 inds m-2. The canonical correspondence analysis (CCA)revealed that there was a high correlation between environmental factors, such as salinity and sediment characteristics, and distribution of polychaetes in the study area.

This study aimed to synthesize a hybrid material of non-valent iron nanoparticles and bentonite with the purpose to promote the pre-eminence of both materials. Moreover, this combination could form a new material that can preserve non-valent iron nanoparticles in normal conditions. Nano zero-valent iron/Bentonite composite material (B-nZVI) was synthesized via liquid-phase reduction (using NaBH4). The surface morphology and structure of the materials were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectroscopy (XRD). The effect of B-nZVI on nitrobenzene removal was studied at different concentrations (25, 50, 75 and 100ppm), contact time (30, 60, 90; 120 and 180m), ratio of mass of material in 100mL of sample solution (0.1, 0.2, 0.5 and 1.0 g/100 ml of sample solution) and pH (pH = 3, 5, 7 and 9). The results indicated that B-nZVI is effective in the removal of nitrobenzene from aqueous solution, where removal efficiency of 99% of nitrobenzene was achieved after 120 m for initial nitrobenzene concentration 50ppm, the ratio of 0.5 g/100ml solution, pH = 7 and pH = 9, at room temperature. Kinetic studies showed that the removal of nitrobenzene by B-nZVI correlated well with the pseudo-first-order model. The removal is an endothermic adsorption process, and the experimental data fitted well the Langmuir isotherm with Qmax being 156.25 mg.g-1for B-nZVI.

This study applied the CLUMondo model to predict agricultural land-use changes to 2030 in the coastal area of ​​Nam Dinh province. The predictions weredonebased on the correlations between the probability of changesrelated to each land use typeand its location suitability factors. Model outputs were validated by ROC statistic and Kappa coefficient.Results showedthatchanges inagricultural land use in 2030followed scenario 1 (baseline) with a decrease in rice areabut increase in the aquaculture area. The trend was similar in scenario 2 (as the land use planning) but the rice area was more decreased. In addition, in both scenarios, there was an increase in annual and perennial crops. Under the assumption of scenario 2, freshwater aquaculture tendedto continue expanding to paddies, while a portion of brackish water aquaculture wasconverted to forest land. Therefore, when implementing land use planning, it is necessary to prepare solutions for trading-off between staple food and aquaculture to ensure food security and sustainable development for local communities.

Poliomyelitis is an acute viral infectious disease caused by a poliovirus that damages the brainstem, spinal cord, andirreversible motor neuron damage. In Vietnam, the polio vaccine hasbeen produced from thelive attenuated poliovirus strain (the Sabin strain)inoculated on Macaca mulattaprimary monkey kidney cells. Inthe conventional procedure, cells are cultured in a monolayer on Roux bottles with a limited surface, therefore, the yield is insufficient. Thisstudy applied a new approach to improve the production efficiency andhigher yield of Polio vaccineby using 10-layer cellSTACK® instead of using glass Roux bottles. Cultureconditions were optimized with the different cell densities and thevolume of the culture medium. The results showed that the optimal density of cells for culture was 156.000 cells/ml and the optimal volume of medium for cell culture after virus inoculation was 150 ml/layer. The optimalparameterswere applied to validate the trial production of3 continuous batchesby using 20of 10-layer cellSTACK® per batch. The result was consistentforall 3 batcheswith high viral titers from7.73 to 7.76 log10CCID50/0.1ml,higher than the standard 5.5 log10CCID50/0,1ml.

In this paper, a four-variable refined plate theory (HSDT4) was used for free vibration analysis of functionally graded carbon nanotube-reinforced laminated composite plates. Equations of motion for simply supported rectangular plates were derived using Hamilton's principle. Comparison studies were carried out to verify accuracy of the present model. New parameter studies regarding the influence of material properties, plate geometry, CNT volume fraction, CNT distribution types, on the natural frequency were performed in detail.

The study aims to develop a simple protocol for in vitro regeneration of Kaempferia galanga L., a local medicinal plant in Vietnam. The rhizome buds (2-3cm) were collected as initial explants and surface sterilized with 0.1% HgCl2for 10m. Initial in vitro shoots were cultured in MS medium supplement with different plant regulatorsincluding BA, Kinetin, NAA and IAA. The combination of 2 mg/l BA and 0.5 mg/l NAA induced the highest shoot multiplication with a mean of 5.03 shoots per explantafter 4 weeks of culture. In this optimal shoot induction medium, in vitro shoots also induced vigorousshoots and roots after five cycles of multiplication. The proposed medium is an efficient medium for in vitro rapid propagation or conservation of K. galanga L. 

The paper presentsthe situation of pig production in the context of disease outbreaks in Yen Phong district, Bac Ninh province.Descriptive statistics, classification and comparison methods were utilized.Pig production in Yen Phong district was organized at various scales from households, family farms to large farms. Most households applied a traditional production procedure in the residential area. There were several family and large farms producing pigs outside the residential area where three large farms applied production procedures to control animal diseases. Formal linkages with contracts in pig production and marketing of pig products wwerenot developed yet; only informal, horizontal linkages were available among pig farmers to exchange knowledge related to farming practices and disease control. The study proposed four solutions to develop pig production in Yen Phong district in the future.

The objective of this study was to identify the factors that affected the competitiveness of garment firms in the Red River Delta region. To achieve this, the study applied the Porter’s five forces as the framework for analysis. By using the previous studies and group-discussion results, the authors have built the metrics to serve the factor analysis. The data were collected through the survey of garment business managers in the Red River Delta provinces with a total of 201 samples. The analysis results showed that 4/5 factors affected the competitiveness of garment enterprises in the Red River Delta region. These are Suppliers, Customers, Potential of new entrants into the industry and Competition in the industry. In which the factor “Customers” is the most important factor for the competitiveness of garment enterprises in the Red River Delta.

Cooperatives play an important role in the national economy to help link and create motivation for small-scale farmer households. Application of high technology in agriculture is considered due to the benefits such as providing safe and high-yielding agricultural products, raising incomes, reducing impacts to the environment. Therefore, promoting the application of high technology in agricultural cooperatives is necessary. This study aimed to overview the theoretical and practical basis for promoting high-tech agricultural cooperatives. Thereby, some suggestions have been given to promote agricultural cooperatives to apply high technology include providing legal bases to help identify high technology agricultural cooperatives; speeding up the formulation and approval of high-tech agricultural projects in localities; flexibility in forms of a mortgage when borrowing capital; extending the limits on land holdings; raising awareness of producers and consumers on the role of high technology and paying attention to capacity building for the cooperative management board as well as fostering vocational skills for agricultural workers.

This research aimed to evaluate the economic, social, and environmental efficiency of high-tech mango production models in Yen Chau district, Son Lan province. We applied the descriptive statistics, economic efficiency evaluating methods, and scoring technique to analyze those models' efficiency based on information from interviewing 60 households by a semi-structured questionnaire. The results showed that high-tech production models have brought higher efficiency in all aspects compared with the traditional cultivation techniques, especially, the model which applied multiple high-technologies attained the highest efficiency. On the economic side, high technologies' application increased farm's productivity, revenue, mixed-income and efficient capital. Meanwhile, in the social aspect, high-tech applications helped households enhance their production capability, created more job opportunities, and increased their income. As for environmental efficiency, high-tech production models minimized the used quantity of inputs such as pesticides, water, and electricity. Those models have also contributed to protecting the environment of soil.