The effects of a range of different sublethal salinities were assessed on physiological processes and growth performance in the freshwater 'tra' catfish (Pangasianodon hypophthalmus) juveniles over an 8-week experiment. Fish were distributed randomly among 6 salinity treatments [2, 6, 10, 14 and 18 g/L of salinity and a control (0 g/L)] with a subsequent 13-day period of acclimation. Low salinity conditions from 2 to 10 g/L provided optimal conditions with high survival and good growth performance, while 0 g/L and salinities >14 g/L gave poorer survival rates (p < 0.05). Salinity levels from freshwater to 10 g/L did not have any negative effects on fish weight gain, daily weight gain, or specific growth rate. Food conversion ratio, however, was lowest in the control treatment (p < 0.05) and highest at the maximum salinities tested (18 g/L treatment). Cortisol levels were elevated in the 14 and 18 g/L treatments after 6 h and reached a peak after 24-h exposure, and this also led to increases in plasma glucose concentration. After 14 days, surviving fish in all treatments appeared to have acclimated to their respective conditions with cortisol levels remaining under 5 ng/mL with glucose concentrations stable. Tra catfish do not appear to be efficient osmoregulators when salinity levels exceed 10 g/L, and at raised salinity levels, growth performance is compromised. In general, results of this study confirm that providing culture environments in the Mekong River Basin do not exceed 10 g/L salinity and that cultured tra catfish can continue to perform well.

The primary goal of a generic optimal power load flow problem Is minimizing total fuel costs of generating units in an electrical power system while maintaining the security of the system. This paper presents an algorithm for optimizing power load flow analysis through the application of Newton ’s method and attends to interchange power between the different power systems. Specifically, it will explore the implementation of data structure such as the binary tree in searching OPF variables (controls, states, constraints) in large power system. So the OPF solution is quickly converging. The primary goal of a generic OFF has been tested by simulation method for 6- bus system in Power World environment. The optimal power flow results is shown that total generation fuel cost in the interchange power case is less expensive than in no interchange power case as well as total transmission losses in the power system are smaller.

This study was conducted through the interview of 48 households applying alternative system of the giant freshwater prawn and shrimp farming in Tra Vinh province. The study aimed to evaluate the effects of different factors on the efficiency of the prawn farming in order to contribute to sustainable development ofthe faming system in the brackish water area of the Mekong Delta. The results showed that the pond was in average area of 0.8 ha; water salinity varied in range of 1-10 ppt during prawn farming. Prawn stocking density was 9.0 inds./m2, and all of the prawn were fed with pellet feed or combined with by-products andtrash fish. After 5, 6 months of culture, average prawn yield of 886 kg/ha/crop and net income of 68 millions VND/ha/crop were achieved. Prawn farming covered only 28.5% of total production cost of the whole system including prawn and tiger shrimp but contributed up to 44.1% of total net income of the prawn -tiger shrimp system.  A total of 89.6% of prawn farming households succeeded in getting net income, compared to 81.3% for tiger shrimp farming households. Inaddition, the study also found that factors such as water salinity, pond preparation, seed nursing and feeding methods strongly affect to the efficiency of prawn farming. The result indicated the great potential and feasibility for farming giant freshwater alternatively with tiger shrimp in brackish water areas of the Mekong delta.

Na8TM (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) clusters are optimized by DFT calculations combining the Triple zeta valence plus polarization (TZVP) method to determine magnetic torque values on orbits, point groups, electron structures, and spin density images of the atomic groups. The results indicate that Na atoms in Na8TM cluster strongly affect the total magnetic moment of the whole group of atoms. In a cluster, each Na atom contributes one electron which combines with valence electron of transition metal for creating a sum of valence electron of the cluster. Atomic groups with the highest magnetic moments are Na8V (5 B) and non-magnetic clusters are Na8Ni and Na8Zn. The electronic structure and magnetic properties of the clusters resemble those of some metals and transition metal ions. This study will orientate to substitution in magnetic materials by metal clusters.