Vol. 16 No. 8 (2018)

A study on population dynamics of Javaen barb (Systomus rubripinnis)was carried out from January toDecember, 2016 along Hau River in An Giang and Can Tho provinces. Trap fence nets and gill nets were used for monthly fish catch sampling. Fishes were counted and measured for body weight (g) and length (cm) to monitor the temporal and spatial fluctuation on quantity and size. Results showed that the growth rate was high (K = 0.5/year); the survival rate after hatching to fishing size in the wild was low (6.2%); the total mortality was 2.8/year, and the fish was mostly caught at 8-11 cm in body length. The fish of smaller sizes was not affected by fishing gears and larger sizes were rarely found in the wild. The total length of fish could reach 20.5 cm. The breeding of this species occurred the whole year round with the peak in rainy and flooding seasons. Phytoplankton and detritus were the main food of this species. Larger fish was found more abundant upstream.

A study was conducted on 100 Co Lung broiler ducks (50 males and 50 females) raised in Thanh Hoa province from 1 day to 12 weeks of ageto evaluatetheir growth characteristics, FCR and the economic efficiency, and thus determine the suitable slaughter age. Results showed that the survival rate of Co Lung ducks up to 12 weeks of age was 95.33%. At 10 weeks of age, the body weight was 1960.03 g and 1876.84 g for males and females, respectively. At 12 weeks of age, the males and females weighed 2103.08 g and 2005.97 g, respectively. The absolute growth rate increased gradually from 11.99 g/duck/day at 1 week of age, reached highest value of 35.05 g/duck/day at 7 weeks of age and gradually decreased to 8.54 g/duck/day at 12 weeks of age. FCR during 0-10 weeks of age was 4.02, 1-11 weeks of age was 4.69, and from 1 to 12 weeks of age was 5.41 kg of feed/kg live body weight gain. The economic efficiency was highest when the broiler ducks sold at 10weeks of age and gradually decreased thereafter. It was therefore recommened that Co Lung broiler ducks should be sold for slaughter at 10 weeks of age for high economic profits.

This study was conducted to determine the biofilm formation and antibiotic resistance of the biofilm-forming Staphylococcusspp. By the application of microtiter plate test, a quantitative method, the biofilm formation of staphylococci was determined. It was found that 51.61% strains produced biofilms at strong, medium and weak levels. Study on the production of biofilm over time showed that the biofilm formation by staphylococci increased from 4 hours to 20 hours, and then decreased from 24 hours to 40 hours post innoculation in 96-wells plate. In terms of antibiotic resistance, the biofilm producing strains were able to survive under the concentrations of antibiotics of 10 to 100 times higher than the planktonic bacteria.

A study was conducted in Nam Dinh city, Nam Dinh province, to evaluate the current situation and propose solutions for land acquisition. Results showed that in the 2010-2017 period, the city of Nam Dinh carried out land acquisition in 41 projects with a total area of ​​86.81 ha for infrastructure and urban improvement. The investigation results of 400 households and individuals whose land was recovered showed that the land acquisitionin Nam Dinh city was carried out in accordance with the procedure; however, a small percentage of households assessed that the determination of land price and support were not appropriate. The SWOT analysis of land acquisitionin Nam Dinh city suggested four following solutions to overcome the weaknesses of land acquisition: (1) rearranging organization of land acquisition, compensation, support and resettlement; (2) managing and updating cadastral files; (3) mobilizing capital; and (4) propagating and disseminating land legislation.

Lignin is a component of plant cell wall. The degradation of lignin remains a challenge to date due to its stability. Lignin peroxidase (LiP) from white rot fungi was known as a highly effective oxidase enzyme for lignin degradation. In this study, extracellular LiP obtained from strain TL4 was precipitated by (NH4)2SO4and ethanol 96% for obtaining technical enzyme and then characterized for optimal temperature and pH and thermal and pH stability. Results indicated that the optimal temperature and pH of LiP were 30C and 4.0, respectively. This enzyme was stable between 20 and 30C for 2 hours (relative activities remain 94.17% and 89.10%, respectively) and pH from 2.0 to 4.0 for 3 hours (relative activities remain 78.97% and 97.87%), respectively. The LiP from strain TL4 showed potential application in environmental treatment and pre-treatment of cropby-products.

In vitropropagation of Taiwanese sweet mulberry was carried out to determine technical parametersinthe production of high quality planting materialsfor expanding cultivated area of the newly introducedfruit tree. One-month-old shoots of two-year-old Taiwanese sweet mulberry plantswere used as initial materialsfor in vitroculture. Results showed that BA at the concentration of 3mg/l in MS medium was suitable for stimulating in vitroshoots from stem nodes with highrate(83.33%). BA at 3 mg/l in combination with0.5 mg/l IBA and 10% coconut water gave the best shoot multiplication rate (2.93 shoots/explant) and the highest shoot quality after 4 weeks of culture. The highest rooting percentage at 96.67% of shoots was observed after 4 weeks onMS medium containing 0.5 mg/l IBA. The plantlets were successfully acclimated in sandy substrate with a survival rate of 80%. The liquid fertilizer “Buffalo Head 502” foliar spary 1 time/weekyielded good quality plantlets suitable for transplanting into pots.This in vitropropagation process is highly effective and easy to apply at production scale.

The present study was conducted to examine the current supply and the awareness of the local people about the main characteristics of clean water services. Results showed that most local people were still unaware of the importance of clean tap water, thus they did not consider it the main source of their domestic water with 60% of households still using less than 10 m3of water monthly. Estimation from Probit equation based on CVM showed that the average households’ willingness to pay for clean water cost was VND 141.07 VND per month, which was higher than the current pay of VND 112.3 thousand per month. Analyzing influencing factors pointed out that the awareness of the people about the nescessity of clean water and the existing water sources had significant impacts on household’s willingness to pay. It is therefore suggested that governmenal agencies and providers should promote public awareness and willingness to pay for clean water services, contributing to the sustainability of the rural clean water system in the area in the coming time.