This paper is aimed to evaluate the performance of the Quasi-Newton in online training of an adaptive sliding mode control using radial basis function neural networks. The controller is applied in trajectory tracking of an Omni-directional mobile robot. The sliding mode control plays a role of tracking the trajectories of the robot reaching the references. The radial basis function neural networks are used to estimate nonlinear functions in the sliding mode control law which is calculated based on the Lyapunov stability theory adapting to control conditions. The simulation results in MATLAB/SIMULINK show that the Quasi-Newton algorithm applying in the proposed controller is positive effect; the responses of the robot converge to references without steady-state error; the overshoot is only 0.442 (%), and the mean square error approximates 3.48 x 10-4.

This paper is to proposed an algorithm for estimating parameters (i.e., Kp, Ki, Kd) of a PID (proportional integral derivative) controller using RBF (radial basis function) neural network. The proposed algorithm is then applied to control direct current motor and a degree-of-freedom robot arm. MATLAB based simulation results show that the RBF based PID gives better performance than the conventional PID for both cases: the fixed and changed parameters of the DC motor and 1 DOF robot arm. It is noteworthy that the proposed approach gives the step response with insignificant overshoot, fast settling time (2 s), and the rise time (0.8 s) is shorter than the conventional PID.

Horizontal deformation rate was calculated from the vertical deformation rate of riverbank soil on simple correlation; from stability calculation, horizontal deformation rate calculation, vertical deformation rate of riverbank soil, the new correlation between the horizontal and vertical deformation rates of riverbank soil  in ward 1 in Vinh Long city was built.

The accelerating growth in technology and consumption leads to resource reduction, increase in waste production and, simultaneously, negative impacts on the environment and human by the wastes of electrical and electronic devices at the end of their product lifecycles. However, some kinds of these used products can be remanufactured, recycled and reused. This paper is aimed to study a reverse supply chain network, in which manufacturers produce new products and remanufacture used products. The decisions to be made are: the number and potential locations of storehouses and collection centers, the capacities of each facility and flows should be transported between each pair of sites. Two linear and multi-period integer programming models are built for determining the traffic levels on every link and jointly analyzing investment and operational costs. A specific study on the cartridge products using in the printers or photocopiers for agencies and schools in Can Tho City and neighboring districts is carried out to propose some managerial insights for using the model in real situations.

Nano ferrite has been published by many previous studies because of its important properties such as magnetic materials and catalysts. In this study, nickel ferrite (NixFe3-xO4) was prepared by sol-gel method with ethylenediaminetetraacetic acid (EDTA) as complex agent. The effect of parametters on material structure and properties were investigated such as EDTA (in acid and salt of sodium compounds), calcination temperature, calcination time, the molar ratio of nickel/iron. The XRD results showed that with calcination temperature higher 600 oC the product was formed with spinel structure and single phase. The product had narrow band gap value, about 1.52 eV. Its photocatalytic in wave lenght of visible light range was investigated with methylene blue solution at wave length of 578 nm and the decompositional yield about 83.4%.

Based on the surveys combining with interviews, key informants, and the plant inventory method, this is to evaluate the current situation of the green system on the campus of Binh Duong School of Agriculture and Forestry. Overall, 43 plant species identified on the campus belong to 27 families, 18 orders. However, both master and detailed plans for the green landscape system have not been made yet. Additionally, the green system has lacked plant data, a highly qualified green team, and professional management. It is recommended that both master and detailed plans for the green system in compliance with infrastructure should be preferred. Especially, the school needs to build a plant database, a highly qualified green team, and professional management of the green system.

Direct contact membrane distillation (DCMD) is a simple configuration that is commonly used in membrane distillation. This study is aimed to develop a DCMD technology for treating saline water with the use of a submerged tubular polytetrafluoroethylene membrane module. The change of feed temperature was operated to investigate its effect on permeate flux as well as distilled water quality. Feed temperatures varied from 40 to 60°C with the fixed operating parameters (cooling temperature of 22 ± 1°C, membrane pore size of 0.45 μm, total dissolved solids of feed water of 5,000 mg/L). The results showed that the permeate flux increased with an increase in feed temperature, but membrane layer (top layer) was swolen when the feed temperature was rising high. In this study, the feed temperature of 60°C was observed to be the optimum feed temperature with a permeate flux of 4.47 L/m2h. It indicates that the proposed DCMD system could treat saline water effectively with the salt removal of greater than 99.45%.

Integrating principles of green chemistry in nanotechnology is a developing area of nanoscience. Therefore, the synthesis of nanoparticles from environmentally benign and sustainable methods is received growing demands. These methods are required to use nontoxic chemicals, environmentally friendly solvents, and renewable materials to avoid their adverse effects. In this work, a simple, economical and environmentally benign method for the synthesis of gold nanoparticles (AuNPs) was described. This single-step method was highlighted by avoiding the use of surfactant, capping agents and following several principles of green chemistry. Specifically, AuNPs were synthesized by the reaction of an aqueous solution of tetrachloroauric (III) acid with the stock solution of tea leaves at room temperature. In this reaction, the polyphenolic molecules contained in tea leaves were responsible for reduction and stabilization. The formation of AuNPs was confirmed by using UV-Vis absorption spectrum. The phase composition, size and morphology of AuNPs were determined by using X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). Next, AuNPs were mixed as a component in cosmetic formulation for skin care. The analyzing for the obtained product, AuNP cream, showed that AuNPs were presented in cream with the amount of 7.55 ppm. Remarkably, the obtained AuNP cream was proved to be safe for skin.

This research is to proposed a new measure to evaluate the similarity of cluster for discrete elements called the cluster similar index (CSI). CSI is used as criterion to build the algorithms to analyze fuzzy and non-fuzzy cluster and to determine the suitable number of clusters. CSI is also used to evaluate the quality of established clusters and compare them together. These established algorithms can be quickly performed by the Matlab procedures. The numerical examples illustrate the proposed algorithms and show their benefits compared to existing algorithms. Finally, analyzing the cluster of images from the proposed algorithm shows potential in the practical application of this research.

Protective effect of young mango (Mangifera indica L.) leaves extract against endoplasmic reticulum (ER) stress was conducted in MIN6 pancreatic β-cells in vitro. The MIN6 cell line was cultured with 5 µg/mL tunicamycin added in 24 hours of exposure and 5% CO2 to induce ER stress and cell death. Cytotoxicity effects of young mango leaves extract on MIN6 cells were observed at various concentration from 50 to 500 µg/mL. Protective effects of the extract were also examined. The results showed that the young mango leaves extract exhibited no cytotoxicity effects on MIN6 cells in 48 hours of culture. The maximal concentration of the extract to protect MIN6 cells against cell death with ER stress was 500 µg/mL. In addition, the antioxidant effects of the young mango leaves extract were recorded in this study. The methods including 2, 2-diphenyl-l-picrylhydrazyl (DPPH), reducing power (RP) assays and 2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) assays were used to determine antioxidant effects of the extract. The EC50 values were 26.64±0.88 µg/mL in DPPH assays, 12.11±1.15 µg/mL in ABTS•+ assays and 45.7±0.50 µg/mL in reducing power assays. It is proved that the young mango leaves have potential in diabetes treatment by against cell death in pancreatic β-cells through ER stress pathway.

Ethanolic extract from the leaves of starfruit (Averrhoa carambola L.) contains the phytochemical components such as alkaloid, flavonoid, triterpene, steroid, reducing sugar, saponin, and tannin. Essential oil of the starfruit leaves was extracted by steam distillation method. After that, it was analyzed by GC-MS for the presence of seven components, in which the most abundant components were 9-eicosyne (9.62%) and butylated hydroxytoluene (3.02%). In addition, the study also investigated the in vitro anti-inflammatory activity of the various extracts by albumin denaturation inhibitory assay. Results showed that ethyl acetate fraction had the strongest anti-inflammatory activity, followed by dichloromethane fraction, ethanolic extract, and water fraction with IC50 values ​​of 79.89 μg/mL, 278 μg/mL, 414,64 μg/mL, 695,91 μg/mL, respectively, compared to prednisolone (IC50 = 12.88 μg/mL) and diclofenac (IC50 = 36.88 μg/mL). But n-hexane fraction showed that anti-inflammatory effect was weak. The results from this study were first reported from the leaves of Averrhoa carambola L.

The hepatoprotective effect of methanol leaf extract of skunkvine (Paederia scandens L.) was investigated on carbon tetrachloride - induced hepatic damage in mice. Liver damage in mice was induced by administration of CCl4 in olive oil with the ratio of 1 to 4 at dose of 2.5 ml/kg per day in 4 consecutive weeks. After one hour taking CCl4 by oral administration, mice were treated with methanol leaf extract of skunkvine at different concentrations of 100, 200, and 400 mg/kg body weight. Silymarin was used as a positive control. After 4 weeks of treatment, the results indicated that the liver transaminase levels decreased significantly. Specifically, the AST level declined by 94.2%, 98%, 99% and ALT levels declined by 91.6%, 93.5%, 95.2% at three tested concentrations. The hepatoprotective effects of leaf extract of skunkvine were similar to those of silymarin at dose of 16 mg/kg BW. Observation of the microscopic cross section of liver tissue also revealed that the mice treated with leaf extract of skunkvine at dose 200 and 400 mg/kg body weight had significantly improvement in liver tissues compared to the non-treated control group.

An experiment was carried out to evaluate the effect of the cage position on growth rate of Luong phuong chickens from 0-6 weeks of age. A total of 300 Luong Phuong chickens were distributed in a completely randomized design, with 10 replications of 3 treatments (each replicate consisted of 10 birds). The treatments were in the front (NT1), in the middle (NT2) and in the back of house (NT3). The experimental birds were fed by the concentrate containing 20.5% crude protein (CP) and 3,000 kcal metabolisable energy (ME)/ kg. The results showed that the daily weight gain was the highest (26.3 g/bird/day) (P

The study was to isolate and select high active yeast train from fermented Baccaurea juice to produce high quality Baccaurea ramiflora wine (high alcohol, low aldehyde and methanol content, good sensory evaluation, good taste and smell). The reasult showed that 48 yeast strains were isolated from Baccaurea ramiflora fruit juices in Can Tho and Hau Giang. Based on the classification keys of yeasts (morphology, physiology, and biochemistry), the isolated yeast strains were generally characterized as three genera: Saccharomyces, Hanseniaspora, and Pichia. Results of selective experiment from yeasts belong to Saccharomyce show that the yeast strain CB1.1 isolated from Baccaurea ramiflora (Bon bon) fruit juice in Phong Dien (Can Tho) has the best fermented activities such as the fastest fermentation by Durham test (24 hours), the highest ethanol content (12.71% v/v) and low remained sugar (7.83oBrix).  Baccaurea ramiflora wine fermented by the yeast CB1.1 with optimal parameters: Brix = 24.70, pH = 4.20, and 107 CFU/mL of yeast cell density in 10 days providing the highest ethanol content (13,76% v/v). Result of the identification of yeast by DNA sequencing showed that the superior yeast strain CB1.1 belong to Saccharomyces cerevisiae.

Bacterial leaf blight of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is a destructive disease which constrains the production of this staple crop in many rice-cultivation regions. This study aims at testing for the disease-reducing effects and demonstrating the involvement of induced resistance in the observed effects of an aqueous leaf extract of Kalanchoe pinnata (life plant) using foliar spraying. A total of six concentrations (1, 2, 3, 4, 5 and 10% [w/v]) of the plant extract were sprayed at 14 or 7 days before inoculation. Under greenhouse conditions, 1% at 14 days before inoculation was the lowest concentration at which the extract showed the disease-reducing effects similar to those of the chemical control at all assessment time points (7, 14, and 21 days after inoculation). Induction of systemic resistance was shown by the increased accumulation of the two enzymes phenylalanine ammonia-lyase and polyphenol oxidase following foliar spraying with the K. pinnata extract and challenge inoculation with Xoo.

This study was carried out to develop elite rice variety/lines with good quality, that can meet export requiements based on hybrid backcross between Pokkali (male) and OM5451 (female). The BC2F2, BC3F2 and BC3F6 populations of the backcross combination of OM5451/Pokkali were used to survey the separation in grain quality characteristics based on the evaluation method of International Rice Research Institute (2002). The results showed that the amylose content and the chalkiness of endosperm of the combinations were significantly lower than those of the father Pokkali through the backcross-breeding. Seed coat (bran) color, brown rice length and shape characteristics have complex dissociation in BC2F2, BC3F2 populations, but are stable in selection process to generation BC3F6. Six rice lines were selected including 1, 2, 5, 6, 7 and  8 in the BC3F6 generation with low amylose content £  20%, gel strength is in group 1 (soft rice), low chalikiness of endosperm (1 - 3%); brown rice shape is slender and long or slender and extra long grain to develop salt tolerant and good quality rice.

In the purpose of finding out the fungi that caused diseases on turmeric (Curcuma) to support for storing medicine materials, the study was carried out. Seventeen strains of pathogen fungi were isolated and identified morphology characteristics from four fresh Curcuma samples named as Binh Phuoc, Xa Cu, Indonesia, Black and three dried samples of AGZG030510, AGZG010510 and DL020611. All of the isolated strains were verified as saprophytic and pathogenous fungi in plants. Fifteen of them were selected for identification by PCR (polymerase chain reaction) technique and sequencing of internal transcribed spacer (ITS) regions. The result showed that seven of them were belong to Fusarium genus: F. oxysporum, F. chlamydosporum, F. verticilliodes, 4 strains of F. proliferatum; three strains were Aspergillus genus: A. flavus, A. terreus, A. tubingensis; two Penicillium species; one was Rhizopus oryzae; one was Dichotomomyces cejpii and another was Coriolopsis polyzona. The phylogenetic tree was drawn based on their ITS sequences. R. oryzae and C. polyzona species were located on two main branches because they belong to the large fungal phylum as Zygomycetes and Basidiomycetes. The others were Ascomycetes and located on the other two branches with bootstrap value of 87%.

Evaluation the effect of six bacteriophages (i. e. ФBurVL34, ФBurVL39, ФBurAG58, ФBurDT47a, ФBurDT48a) on controlling bacterial grain rot caused by B. glumae in greenhouse conditions. All six bacteriophages expressed disease control with the percentage of infected grain significantly lower than the control. In which, the treatment applied with bacteriophage ФBurDT47a showed a higher level of disease protection than other treatments at 20 days after pathogen inoculation. In addition, all four tested titers of the bacteriophage ФBurDT47a (105 pfu/ml, 106 pfu/ml, 107 pfu/ml and 108 pfu/ml) could prevent grain rot disease, of which the 108 pfu/ml titer was the best treatment in giving disease protection. The result of study on additives combined with phage suspension for enhance disease control showed that three additives (carrot flour, soya flour and corn flour) gave a lower level of percentage of grain infection than phage suspension without additives.

The study was aimed to compare efficiency between water-saving irrigation techniques (WSI) and traditional irrigation practices applied on upland crops in sandy soil areas in Tra Vinh province to provide basic information for improving and expending the WSI techniques in the areas with this type of soil in the Mekong Delta. Tools such as key informant panels, focus group discussion, and households survey have been employed to collect data. In addition, the study used CropWat model to simulate irrigation water requirements, and build a pilot trial for evaluating the effectiveness of the WSI model that was applied on watermelon and groundnut crops (representatives of upland crops) in Cau Ngang and Tra Cu districts, Tra Vinh province. The study figured out that water amount irrigated was higher than crops’ actual requirements. The WSI techniques helped to save irrigation water by approximately 26 - 30%, reduce irrigation time 80 - 87%, and increase crop production by 15 - 17% in comparison with local farmer's irrigation practices. These results will be useful information for agriculture extension systems in encouraging farmers to apply the WSI techniques in upland crops cultivation to reduce impacts of groundwater exploitation and adapt to climate change on agriculture in the sandy soil areas of the Mekong Delta.

The aim of this study was to assess phosphorus solubilizing microorganisms in eutric fluvisols (Gia Lam district, Hanoi) and gleyic fluvisols (Tien Lu district, Hung Yen province) for cultivating rice in the Red River Delta (2 crops per year). The results of isolation showed the appearance of bacteria, actinomycetes in the samples, but absence of fungi. Overall, density of phosphorus solubilizing microorganisms in eutric fluvisols was much more than that in gleyic fluvisols; however, the amount of strains was less diverse. It was not the same between the 2 types of soil, even between different samples of the same soil type. There were 4 common strains of bacteria in eutric fluvisols; the density ranged from 15.5 to 22.9 x104 CFU/g soil. Meanwhile, the gleyic fluvisols had 4 strains of popular bacteria and 1 strains of actinomycetes, ranged from 2.3 to 17.3 x104 CFU/g soil. In these 2 soil types, the density of inorganic-phosphate solubilizing microorganism was higher than that of organic- phosphate solubilizing microorganism. However, compared to the total of microorganisms, both microbial groups were very low in density, less than 1% of each. Besides, ability of phosphorus solubilization of them are not high, phosphate PO43-  released ranging from 0.70 to 5.66 ppm (Tricalcium phosphate form) and from 0.0 to 1.83 ppm (Lecithine form).

The study is aimed to determine the effect of alternate wetting and drying (AWD) compared to continuous flooding (CF) on soil available nitrogen (N), rice yield in the field experiment and N mineralization in the laboratory. The study was conducted in (i) the rice field in Autumn-Winter 2014 at Hoa Binh district, Bac Lieu province and (ii) in the laboratory with anaerobic and aerobic incubation for N mineralization after two alternate wetting-drying processes at the rice field. The experiment was designed in a completely randomized block with 3 treatments including CF, AWD1 (irrigated when water level below -15 cm) and AWD2 (below -30 cm) with 3 replications for each treatment. The results showed that AWD saved about 13-18% of irrigation water in comparison with CF. Applying AWD2 and AWD1 had respectively higher NH4+ and NO3- contents than those from CF at the harvesting stage, but did not affect the rice yield. The results of mineralization showed that the mineral N content in aerobic incubation was higher than that in anaerobic incubation. Particularly, AWD1 had a significant increase in mineralized NH4+ after 21, 28 days of anaerobic incubation, while after 7 days in aerobic incubation. Similarly, AWD1 also achieved high mineralized NO3-content in 21 days of anaerobic and 28 days of aerobic incubations.

This study was to evaluate the effect of fresh spent coffee ground (FSCG) on growth and yields of maize, soybean and rice and on soil biological properties under nethouse conditions. Maize, soybean and rice were continuously cultivated in Arenosols taken from Tieu Can district, Tra Vinh province. Seven different treatments including the control (no fertilization), 2, 4, 6, 8, 10% of FSCG applied (w/w, based on the dry soil mass) and the treatment with recommended inorganic fertilizer were conducted. Four replicates were repeated for each treatment. Plant height, bacterial and fungal numbers in soil were sampled at day 30, 45 (60), 60 (90) after seedling. Besides, crop yields and structure of soil bacterial community at the end of the cultivation were collected. The results showed that an application dose of FSCG with either 2 or 10% was efficient on stimulation of the growth and yields of soybean and rice as compared to the recommended inorganic fertilizer treatment. Moreover, in these treatments, some soil fertility characteristics, the numbers of soil bacteria, fungi, nitrogen fixing bacterial and phosphate solubilizing bacterial increased signicifcantly compared to other treatments (without FSCG application) over three cropping seasons. Thus, it can conclude that FSCG can be applied with an application dose of 2% or 10% into soil as a soil clean amendment to soybean and rice for good production and sustainable agricultural development.

Levels of genetic diversity were quantified for kissing gourami collected from several locations in the Mekong Delta using inter-simple sequence repeats (ISSR) markers. Fish were sampled from natural water bodies in the Lang Sen Wetland Reserve (Long An) and from cultured ponds in three provinces including Can Tho, Hau Giang, and Tra Vinh. First, random samples (one or two from each population) were analyzed DNA barcoding (gene COI) and compared their sequences to Genbank database to confirm species identification. Then, genetic diversity levels of four populations were quantified based on six ISSR primers (20-21 samples per population). Results of the DNA barcoding analysis indicated a high level of identity (99.2%) between COI sequences of kissing gourami in this study with sequences of the same species (Helostoma temminckii) reported to Genbank. Amplifications of ISSR primers on 82 individuals generated 86 fragments with the size ranges from 400 bp to 3,000 bp, polymorphic ratios 55.42-90.36%, expected heterozygosity 0.180-0.245, and Shannon index 0.269-0.386. In general, genetic diversity was relatively high in all kissing gourami populations. In which, parameters of genetic diversity were found highest in Hau Giang population and lowest in Lang Sen population. Therefore, the Lang Sen wild population needs to be conserved and applied appropriate supplementary programs.

The study was aimed to determine optimal stocking density for the growth and survival of white leg shrimp (Litopenaeus vannamei) in bioflocs systems. The experiment was randomly conducted at density of 150, 300, 450 and 600 inds/m3 with four replications. Shrimp were stocked in 0.5 m3 tanks(containing 0.3 m3 of water), at 15‰of salinity in bioflocs system (C:N ratio =15:1). The initial shrimp weight was 0.74±0.09 g/ind (4.33±0.32 cm). After 60 days of culture, water quality parameters as temperature, pH, TAN and nitrite were in suitable range for shrimp growth. The results indicated that white leg shrimp in 150 inds/m3 treatment showed the best growth rate with 10.85 cm, 12.12 g/ind and 77.8% of body length, body weight and survival rate, respectively. It was significantly different (p0,05).

Material flow cost accounting (MFCA) is management tool of production process related to the flow of raw materials and energy, aiming to determine and calculate the real cost of waste and material losses. In this paper, MFCA is studied to apply for the sushi shrimp processing in Ocean Shine Food. The analysis focuses on the cost of material (cost of product and waste) and energy used in the production process. Then, basic measures to improve the process are given. The result showed that MFCA is a helpful tool in clarifying waste issues and optimizing production with actual conditions of the company.

The study is aimed to determine the best rearing system for growth, the survival rate of black tiger shrimp larvae and post larvae (PL). The experiment consisted of four treatments: (i) recirculating system, (ii) opened system (water exchange), (iii) Bio-product, and (iv) Bioflocs technology. The larvae at nauplius 4 (body length = 0.41±0.02 mm) were stocked in 500 L tanks at 150 inds/L of density and 30‰ of salinity. When the larvae reached to Mysis-1 phase, then applications for each system were started as (i) connecting to bio-filters, (ii) water exchange every 3 days, (iii) using bio-product (Yucca with 10 mL/m3 every 3 days) and (iv) adding molasses (C: N = 30) every 3 days. After 19 days of stocking, the water parameters in all treatments were in the suitable range for the growth of larvae and postlarvae. The body length of the larvae at Zoea-1, Mysis-1, and PL5 among treatments were not significantly different (p> 0.05). However, the body length of PL10 in bio-product treatment and RAS were 9.60 mm and 9.58 mm, respectively, which were not significant compared to Bioflocs treatment (9.24 mm), but significantly different compared to exchange water treatment (8.86 mm). Similarly, the survival rate of PL10 reached the highest post in bio-product treatment (51.9%), statistically greater to opened system (36.9%) and Bioflocs (42%), but there is no significant difference compared to RAS (43.9%).

A study of fishing activities was conducted from July to December 2017 in coastal provinces of the Mekong Delta. Results show that the gill nets, trawl nets, bag nets, and cage traps were main fishing gears and had highest number of fishing boats and yields. All of fishing gears can capture whole year round. Gill nets had largest scale, but the yield of trawlers was highest. Gill nets were most effective with highest profit achieved (298 million VND per year). Trawlers had highest yield (20.42 tons/year), but they had highest ratio of trash fish (38.4%) and lowest benefit ratio (0.45 times). Although the bag nets had highest benefit ratio (1.41 times), they had lowest yield (7.17 tons/year) and highest ratios of trash fish so they affected fisheries resources. Cage traps had highest ratio of trash fish (23.8%). For the sustainable development of fishing, management of fisheries resources should be promoted, supporting fishermen to access low interest rates to invest in capture production, and training them to use advanced fishing gear to increase their fishing efficiency.

The marine high tide aquaculture status in Phu My commune, Phu Vang district, Thua Thien Hue province was studied from April to November 2017. The study had investigated 33 households on aquaculture, combing GIS techniques procedures with pond sites identified by GPS  to create the attributes such as culture area, species, culture form, management and economic efficiency. The results had built the vector maps of all above aspects. The mainly cultured species in the region were black tiger shrimp, crab, rabbit fish and white-spotted rabbit fish with the form of polyculture (99.1%). Each species was stocked at different densities of 1.5 - 5 ind./m2 (black tiger shrimp) and less than 1 ind./m2 (fish and crab). These species were cultured from 2-3 cycles per year. Water treatment was not completed to implement with pollution factors. Waste water was not  mostly treated. The efficiency of culture was low with 0.4 - 1 profit margin.

This paper proposes a number of teaching aids and tools to promote the application of information and communication technolog in the regular fostering of teachers and administrators from grade schools to enhance the efficiency in innovating training methods. WebQuest is a modern teaching methodology, built on the basis of new teaching tools (e.g. information technology and the Internet) through free, simple and easy-to-use online tools such as Google’s G Suite for education, OKMindmap, Scratch, Moodle and Facebook. WebQuest is used as a blended learning method to serve the needs of educational reform from one-way transmission, teacher-centered education to student-centered teaching, project-based learning to stimulate creative thinking and active self-learning of learners. Feeback from the learners is positive to the practices at School of Education in Can Tho University. This suggests that this teaching methodology is effective in fostering teacher professional development.

This article is intended to clarify the difficulties and errors of 4th grade students in learning the decimal system. The study begins with a summary of Gerente's study (2015) concerning the system of counts; in particular, it clarifies two features: the positional aspect and the decimal aspect of the decimal system. Next, a study of the current teaching system through textbook analysis allows the prediction of three difficulties related to difference between writing and reading numbers, understanding numerals, and using the decimal aspect to solve problem. The difficulties were clarified through a set of questions on 108 4th grade students. Student errors indicated that they still did not understand the two aspects of the decimal system.

Doing scientific research is one of the basic tasks of university lecturers. Besides teaching ability, the capacity to do scientific research determines a lecturer’s professional competence. However, the capacity of doing scientific research has not been addressed, and only a small number of lecturers have published scientific papers. A survey among 150 lecturers from Can Tho University was analyzed by descriptive statistics using SPSS 20.0 to assess the current state of doing scientific research of the university lecturers. The results have showed that many lecturers have not participated in scientific research activities, specifically, 41.3% of lecturers have not done research yet; 30.7% of lecturers are not members of scientific research; 48% of lecturers do not have scientific papers; 34.7% of lecturers have not yet done the scientific reports (seminars) at the unit; 50% of lecturers have not yet written papers for conferences or scientific seminars, etc. This study also investigated the motivation and difficulties of lecturers in scientific research; it then proposed solutions to promote the scientific research activities of lecturers in order to fulfill the mission of better technology transfer, and serving the society.

This study was conducted to investigate the demand on experiential tourism of the resident of Can Tho city. It was based on interview data from 200 citizens and use of descriptive statistics and crosstab method. The results showed that experiential tourism is not only a new type of tourism but also a tourist trend of young generations. In addition, the results also indicated a range of essential activities in an experiential tour for the customers. Based on these results, some policy recommendations were proposed for tourism enterprises to satisfy demand on experiential tourism of the resident of Can Tho city better in the coming years.

This research was aimed to investigate the impact of ownership concentration and board ownership on the performance of firms listed in Ho Chi Minh stock exchange. The data were collected from 287 non-financial listed firms in the period from 2011 to 2015. The generalized method of moments is used to analyze the data. The results indicated that ownership concentration enhanced the performance of non-financial firms listed in terms of market value as well as accounting performance. However, there was no statistical evidence on the impact of board ownership on firm performance. Besides, the higher leverage was found to reduce the performance of listed firms. In addition, listed firms which had good growth rates, large size and high annual fixed asset investment rate were statistically associated with higher market value and better accounting performance.

Transformation of agricultural production system in coastal areas is an indispensable trend in the climate change context, specifically from sugarcane to mono-shrimp farming with higher profit expectations. Face-to-face interviews were conducted with 90 farmers who have recently transformed from sugarcane cultivation to shrimp production in Cu Lao Dung district, Soc Trang province in order to estimate the economic efficiency to provide empirical evidences for policy makers. The results showed that the average profit was 452 million VND/ha/season. However, there was large variation in profits among the shrimp farmers, which in part reflected the risk in shrimp production. The results also showed that the returns to scale are increasing. The average economic efficiency of shrimp farming was 80.82%, and there was a great variation in economic efficiency among shrimp farmers. It was also found that the total economic loss due to economic inefficiency or the total cost that shrimp farmers could reduce was 102 million VND/ha/season.

The choice experiment method was used to investigate farmers’ valuations of health risk changes associated with pesticide use. 90 rice-cultivated households were surveyed in Tam Binh District, Vinh Long Province. Results show that all included attributes are significant factors to determine farmers’ valuation. They are related to the application of pesticides in production with differences in information about health consequences, baseline risk, scale of risk reduction as well as increase in annual production costs.

This study is aimed to analyze the professional competence framework for employees in the travel sector in Can Tho city, based on the survey of 100 respondents – managers and staff members – with regarding to the three core groups of factors: knowledge, skills, and attitude. The surveyed results indicate that the important role of the professional compences of employees in creating values and improving service quality. It is worth noting that employee’s attitude is likely assessed as the most high-ranking factor among the professional competences to be a good employee in this sector.