Seed Health and Quality of Rice Seeds Produced by Farmer and Growing in Cho Moi District, An Giang Province, Vietnam

This study was conducted at Laboratory in An Giang University; the varieties examined were collected from farmer households in 2018 – they were varieties that the farmer stored for the next crop (Winter-Spring) from Autumn-Winter crop in Cho Moi district, An Giang Province, Vietnam. The research evaluated the quality of seed rice, which is provided and planted by the farmer. As a result, this study showed that almost all of the varieties of seed rice from farmer households indicated the ratio of filled-grain, the germination, and the determination of seedling healthy, which are lower than certified variation. Besides, the samples of seed rice from farmer household have more infected fungal; especially the samples with higher in a filled-grain ratio is less infected by fungi, there were 12 types of seed borne-fungi in rice varieties from the farmer (in Cho Moi district), included: Alternaria padwickii, Rhizoctonia solani, Aspergillus oryzae, Bipolaris oryzae, Cercospora janseana, Curvularia lunata, Fusarium moniliforme, Pyricularia oryzae, Sarocladium oryzae, Tilletia barclayana, Fusarium graminearum, and Ustilaginoidea viren

Effect of Molecular Charge Asymmetry on Even-to-odd Ratio of High-order Harmonic Generation

Recently, asymmetric molecules, such as HeH$_2^+$, CO, OCS, HCl, have been evolved much attention since its rich information in the high-order harmonic generation (HHG), whose ratio of adjacent even and odd harmonics characterizes the asymmetry of molecules. In this paper, we study the dependence of even-to-odd ratio on the asymmetric parameters, in particular, the nuclear-charge ratio, and the permanent dipole, by exploiting a simple but general model of asymmetric molecules $Z_1Z_2$ subjected to an intense laser pulse. The HHG is simulated by the numerical method of solving the time-dependent Schrödinger equation. We find out that this even-to-odd ratio strongly depends on the nuclear-charge ratio. In particular, the even-to-odd ratio reaches its maximum when the nuclear-charge ratio is about from 0.5 to 0.7. Besides, the dependence on the permanent dipole of the even-to-odd ratio has a non-trivial law. To explain, we calculate the analytical ratio of the transition dipole according to the emission of even and odd harmonics, and this ratio is well consistent with the even-to-odd ratio of the HHG

Evaluation of Pseudomonas stutzeri AM1 and Pseudomonas oleovorans ST1.1 isolated from shrimp pond sediments as probiotics for whiteleg shrimp, Litopenaeus vannamei culture

This study aimed to isolate the probiotic potential of nitrifying bacterial strains and to evaluate their effects on water quality and growth performance of the whiteleg shrimp, Litopenaeus vannamei. Based on an initial screening of 100 isolates identified from sediment samples, 12 strains could remove nitrogen compounds and two strains (Pseudomonas stutzeri AM1 and P. oleovorans ST1.1) showed highly efficient nitrogen removal ability. Within 96 h, total ammonia nitrogen (TAN) removal efficiency in the two strains was 28.0-31.6% and 21.5-24.9%, respectively. The water addition of 103 CFUmL-1 of P. stutzeri AM1 (T1) and P. oleovorans ST1.1 (T2) effectively reduced TAN, nitrite, nitrate, and total sulfide and increased the survival rate and biomass of shrimp. However, no significant differences were found between the control (T0) and treatment groups (T1 and T2) in the final weight, weight gain and specific growth rate of shrimp. Overall, P. stutzeri AM1 (T1) and P. oleovorans ST1.1 used as water supplements improved water quality and the survival rate of whiteleg shrimp

STRUCTURE, MICROSTRUCTURE, AND PIEZOELECTRIC PROPERTIES OF KNLNS-BNKZ LEAD-FREE CERAMICS UNDER THE EFFECT OF DIFFERENT SINTERING TEMPERATURES

Samples of 0.96(K0.48Na0.48Li0.04)(Nb0.95Sb0.05)O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 piezoelectric ceramic were fabricated with conventional ceramic techniques and sintered at different temperatures. The effect of sintering temperature (TS) on the structure, microstructure, and piezoelectric properties of the ceramics was studied in detail. The experimental results showed that with an increase of the TS temperature, the structure of the ceramics transformed from an orthorhombic-tetragonal mixed phase (O-T) at TS £ 1100 °C into a rhombohedral-tetragonal (R-T) mixed phase with a dense microstructure of uniform grain size at TS = 1110 °C. When TS was further increased (TS ³ 1120 °C), the ceramics showed only a rhombohedral phase (R). The ceramics showed the best electrical properties for TS = 1110 °C at which the rhombohedral and tetragonal (R-T) phases coexist. Specifically, the ceramic density reached its highest value (4.22 g/cm3), the electromechanical coupling coefficients kp and kt were 0.46 and 0.50, respectively, and the piezoelectric coefficient d33 was 245 pC/N.Samples of 0.96(K0.48Na0.48Li0.04)(Nb0.95Sb0.05)O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 piezoelectric ceramic were fabricated with conventional ceramic techniques and sintered at different temperatures. The effect of sintering temperature (TS) on the structure, microstructure, and piezoelectric properties of the ceramics was studied in detail. The experimental results showed that with an increase of the TS temperature, the structure of the ceramics transformed from an orthorhombic-tetragonal mixed phase (O-T) at TS £ 1100 °C into a rhombohedral-tetragonal (R-T) mixed phase with a dense microstructure of uniform grain size at TS = 1110 °C. When TS was further increased (TS ³ 1120 °C), the ceramics showed only a rhombohedral phase (R). The ceramics showed the best electrical properties for TS = 1110 °C at which the rhombohedral and tetragonal (R-T) phases coexist. Specifically, the ceramic density reached its highest value (4.22 g/cm3), the electromechanical coupling coefficients kp and kt were 0.46 and 0.50, respectively, and the piezoelectric coefficient d33 was 245 pC/N

Phytoplankton composition in intensive shrimp ponds in Bac Lieu province, Vietnam

Algal overgrowth in shrimp culture ponds can affect the quality of the aquatic environment, thereby adversely affecting the shrimp and causing economic losses. The objective of this study was to evaluate the variation in phytoplankton composition in intensive shrimp ponds in Bac Lieu province, Vietnam. Phytoplankton samples were collected in three black tiger shrimp (Penaeus monodon) ponds and three whiteleg shrimp (Litopenaeus vannamei) ponds. The collected data were analyzed using SPSS and canonical correlation analysis softwares. In total, 75 species of phytoplankton were recorded in black tiger shrimp ponds and 64 species in whiteleg shrimp ponds. Diatoms had the highest species diversity with 29–30 species (39%–47%), followed by green algae with 9–19 species (14%–25%); species numbers of other phyla varied from 5–12 (8%–16%). The total number of phytoplankton species throughout the study varied from 34–50 species. Algal density was relatively high and ranged from 497,091–2,229,500 ind./L and 1,301,134–2,237,758 ind./L in black tiger shrimp and whiteleg shrimp ponds, respectively. The diatom density tended to increase during the final stage of the production cycle in black tiger shrimp ponds. Blue-green algae and dinoflagellates also increased in abundance at the end of the cycle, which can affect shrimp growth. Diatoms were significantly positively correlated with pH, salinity, total ammonia nitrogen, and nitrate (NO3–) concentrations (p < 0.05). Blue-green algae and dinoflagellates were positively correlated with salinity, phosphate (PO43–), and NO3–. Algal species diversity was lower in the whiteleg shrimp ponds than in the black tiger shrimp ponds. Several dominant algal genera were recorded in the shrimp ponds, including Nannochloropsis, Gyrosigma, Chaetoceros, Alexandrium, and Microcystis. The results of this study provide basic data for further investigations, and they contribute to the management of algae in brackish-water shrimp ponds

Performance of Sampling/Resampling-based Particle Filters Applied to Non-Linear Problems

In this work, we propose a wireless body area sensor network (WBASN) to monitor patient position. Localization and tracking are enhanced by improving the effect of the received signal strength (RSS) variation. First, we propose a modified particle filter (PF) that adjusts resampling parameters for the Kullback-Leibler distance (KLD)-resampling algorithm to ameliorate the effect of RSS variation by generating a sample set near the high-likelihood region. The key issue of this method is to use a resampling parameter lower bound for reducing both the root mean square error (RMSE) and the mean number of particles used. To determine this lower bound, an optimal algorithm is proposed based on the maximum RMSE between the proposed algorithm and the KLD-resampling algorithm or based on the maximum mean number of particles used of these algorithms. Finally, PFs based on KLD-sampling and KLD-resampling are proposed to minimize the efficient number of particles and to reduce the estimation error compared to traditional algorithms

Phytoplankton diversity and its relation to the physicochemical parameters in main water bodies of Vinh Long province, Vietnam

Phytoplankton samples were collected in 2016 during the dry and rainy seasons at nine sampling sites in Vinh Long province, Vietnam. Some basic environment parameters such as temperature, pH, dissolved oxygen, nitrate and phosphate were measured and a total of 209 phytoplankton species (six phyla, 96 genera) were identified. The phylum that had the greatest number of species was Bacillariophyta (82 species), followed by Chlorophyta (61 species), Cyanophyta (39 species), Euglenophyta (21 species), Chrysophyta (three species) and Dinophyta (three3 species). The phytoplankton density ranged from 4,128 to 123,029 cells/liter. The dominant algae recorded in the study area include Microcystis aeruginosa, Merismopedia glauca, Oscillatoria perornata, Jaaginema sp., Planktothrix agardhii, Coscinodiscus subtilis, Melosira granulata. In particular, Microcystis aeruginosa was the most density dominant species in the total number of sampling sites during the dry season survey, and this species was classified as a group producing toxins harmful to the environment. Surface water quality, according to QCVN 08: 2015/BTNMT was classified into Column A1 for pH, nitrate and Column B1 for dissolved oxygen, and Column B2 for phosphate. Phytoplankton community structure and environmental factors changed substantially between dry and rainy seasons. A Pearson (r) correlation coefficient was used for the relative analysis. The results indicated that the number of phytoplankton species were a significantly positive correlation with pH, dissolved oxygen and nitrate in the rainy season. The phytoplankton abundance was uncorrelated with environmental factors in both seasons.Các mẫu thực vật phù du được thu thập trong năm 2016 (mùa khô và mùa mưa) tại 9 vị trí ở tỉnh Vĩnh Long, Việt Nam. Một số thông số môi trường như nhiệt độ, pH, oxy hòa tan, nitrat và phốt phát được đo ngay tại hiện trường. Tổng cộng 209 loài thực vật phù du được ghi nhận (6 ngành, 96 chi). Số lượng loài cao nhất là tảo Silic (82 loài), kế đến là tảo Lục (61 loài), tảo Lam (39 loài), tảo Mắt (21 loài), tảo Vàng ánh (3 loài) và tảo Giáp (3 loài). Mật độ thực vật phù du dao động từ 4.128 đến 123.029 tế bào/ lít. Các loài ưu thế ghi nhận được ở khu vực nghiên cứu gồm có: Microcystis aeruginosa, Merismopedia glauca, Oscillatoria perornata, Jaaginema sp., Planktothrix agardhii; Coscinodiscus subtilis, Melosira granulata. Trong đó, loài Microcystis aeruginosa chiếm ưu thế nhiều nhất trên tổng số điểm thu mẫu trong đợt khảo sát mùa khô, đồng thời loài này được xếp vào nhóm sản sinh độc tố gây hại cho môi trường. Chất lượng nước mặt theo QCVN 08:2015/BTNMT được xếp vào loại A1 đối với thông số pH, nitrat và loại B1 đối với thông số oxy hòa tan, và loại B2 đối với phốt phát. Cấu trúc quần xã thực vât nổi và các yếu tố môi trường thay đổi đáng kể giữa mùa mưa và mừa khô. Hệ số tương quan Pearson (r) được dùng để phân tích. Kết quả cho thấy số lượng thực vật phù du có tương quan thuận với pH, oxy hòa tan và nitrat trong mùa mưa và có ý nghĩa về mặt thống kê. Mật độ của thực vật phù du không tương quan với các yếu tố môi trường trong cả hai mùa

Antioxidant and in vitro antidiabetic activities of Peperomia pellucida (L.) Kunth extract

Peperomia pellucida (L.) is commonly used as a herbal plant. Its effectiveness in treating inflammatory diseases, digestive disorders, and cancer in tropical and subtropical countries was introduced, especially in field of folk medicine. However, this plant species has not been studied widely in Vietnam, especially for its biological activities. This study was done to determine the antioxidant capacity of P. pellucida by using in vitro and in vivo methods, as well as its inhibitory ability to α-amylase enzyme activity. The total polyphenolic and flavonoid contents of P. pellucida extract were reported to be 359.91±0.77 mg GAE/g and 200.28±1.23 mg QE/g extract, respectively. The results showed the in vitro antioxidant activity of P. pellucida extract in four methods, including DPPH, and ABTS.+, RP and TAC, had EC50 values of 730.34 μg/mL, 84.33 μg/mL, 95.28 μg/mL, respectively, and Abs0.5 value of 114.73 μg/mL. Under H2O2-induced oxidative stress, fruit flies that were raised in the feed medium supplemented with a concentration of 1 mg/mL of P. pellucida extract showed their average survival time, 50% survival time, and 10% survival time at 1.6 times, 1.8 times, and 1.62 times, respectively, higher than those of the control treatment. The ability to inhibit the α-amylase activity in P. pellucida extract was determined with an EC50 value of 115.32±2.65 μg/mL compared with the commercial drug of 18.67±0, 01 μg/mL. The research results showed that P. pellucida is a potential species in the study of natural compounds with antioxidant and antidiabetic activities