In this study, Monte-Carlo simulation samples are generated by the periodic Gibbs sampling algorithm. The probability of a rare event will be estimated from these simulated samples. By using the Naïve Monte Carlo method to estimate the very small probability of rare events, it is necessary to create very large simulation samples that take a long time to initialize. This limitation was significantly improved by combining the cross-entropy method with the Gibbs sampling algorithm to create Monte-Carlo simulation samples. Using the technique of probability measure change in the cross-entropy method, rare events will occur in the simulation sample at a higher frequency according to the new probability measure. The probability of these rare events can be well estimated by returning the results for the initial probability measure.

This paper is to deal with Mond-Weir duality and Wolfe duality for constrained set-valued optimization problems in terms of cone-directed Clarke derivatives. Firstly, necessary and sufficient optimality conditions for constrained set-valued optimizations in terms of cone-directed Clarke derivatives for the cone-semilocally convex like maps are investigated. Then, the Mond-Weir duality and Wolfe duality for a constrained set-valued optimization and their weak duality, strong duality and converse duality are considered.

Belinostat is a histone deacetylase inhibitor for the treatment of hematological malignancies and solid tumor. In this study, belinostat analogues were successfully synthesized through a simple and effective process suited to laboratory scale in Vietnam including 6 steps: i) Preparation of m-nitrobenzaldehyde using KNO3/H2SO4; ii) Use of Wittig reaction with ylide compound as the nucleophile; iii) Reduction of –NO2 group. iv) Preparation of sulfonyl; v) Substitution reaction with amines as the nucleophile; and vi) Synthesis of hydroxamate by NH2OH. Belinostat derivatives were obtained in good yields. The structures of the products were confirmed by 1H-NMR and MS spectra. The evaluation of HDAC inhibitory capacity of the synthesized compounds in silico was also carried out to investigate the biological activity.

Nowadays, the continuous wavelet transform has been applying for interpretation of potential field data to detect accurately the location for the anomaly sources and their properties. For magnetic data at low latitude areas such as the Mekong Delta (latitudes  11,07o), both of the magnetization and ambient field are not directed vertically, making magnetic anomalies antisymmetrical and often skewed to the location of the sources. So it is significantly problematic to interpret these anomalies. In this paper, two-dimensional continuous wavelet transform (2-D CWT), using Farshad-Sailhac complex wavelet function is studied and applied for reducing the magnetic anomaly to a symmetrical one - this located on the source of the anomaly, and then determining the position of the center of the object causing anomalies by wavelet transform modulus maxima (WTMM) method, to enhance the quality of magnetic data interpretation in this area. Furthermore, to determine the anomaly sources ’s properties effectively, the relationship between the source depth and the scale corresponding the maximum point of the wavelet transform coefficients as well as the equation for estimation the one size have been formed. After verifying the reliability of the proposed method on the modeling data, a process for the location of the magnetic anomalies at low latitude areas using the wavelet transform is set up, and then application for analyzing the magnetic data in the Mekong Delta.

This study is aimed to determine determine conditions effecting fermentation process of Syzygium cumini L. using Saccharomyces cerevisiae TN4 strain. Design Expert 7.0 was used determine optimal factors including pH, oBrix and yeast cell density. The results indicated that, with pH 4.2, 24oBrix and 6 x 106 cells/mL, the highest alcohol content reached 10.78% v/v. After 3 days of fermentation, the fermented product reached an alcohol content of 5.20% v/v, consistent with fermented juice product. Simultaneously, 11 herbal compounds have been identified through spectroscopic methods, including steroids, triterpenoids, phenols, tannins, flavonoids, quinones, saponins, antocyanins, glucose, carotenoids and alkaloids from initial juice and fermented juice product. The quantitative change of these compounds before and after fermentation is negligible. The total polyphenol content of Syzygium cumini juice is higher than fermented product, particularly 57.0 mgGAE/L and 55.0 mgGAE/L respectively.  After fermentation, the reduction peroxide capacity of fermented juice reached an IC50 value at 8.56 μL/mL, which is higher than the Syzygium cumini juice (IC50 value at 12.23 μL/mL.), shows that the fermented product has better antioxidant resistance than the original Syzygium cumini juice.

This article is aimed to study the transmission of corona virus in which exposed group can cause infection and a recovered individual can be relapsed. The model is given by a system of stochastic differential equations. Mathematical analysis shows that the dynamic of transmission is determined by the basic reproduction R0 and a threshold value Rs. For Rs< 1 then the transmission goes extinct, while R0 > 1 then the transmission remains. Differential operator and Lyapunov theory are used to prove the stability and persistence of equilibria. Numerical investigation is carried out to confirm the analytical results.

In this study, silver nanoparticles with different sizes and shapes were synthesized by a polyol method. The formation of silver nanoparticles was determined by employing different characterization methods such as ultraviolet–visible spectroscopy (UV-Vis), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). It was found that in the ethylene glycol/PVP media, silver nanoparticles were spherical and their average particles sizes (21 nm, 85 nm) depended on the amount of silver nitrate while most silver nanoparticles were rod – shapes with the present of anions Cl-. The antibacterial activities of 21-nm, 85-nm silver nanoparticles and silver nanorods were processed by counting colonies on agar petri disks method, determining minimum inhibitory concentration (MIC). It was found that 21-nm, 85-nm silver nanoparticles and silver nanorods were good antibacterial effects on Escherichia coli. 21-nm silver nanoparticles were the best antibacterial effect on Staphylococcus aureus (MIC = 7,5 µg/mL) while silver nanorods did not show antibacterial activity on Staphylococcus aureus.

In this study, two simulation toolkits including Geant 4 and MCNP-CP are used to investigate the configuration of the Compton suppression spectrometer at Nuclear Research Institute. The Compton suppression system consisting of 12 bismuth germanate (BGO) scintillation crystals surrounding one HPGe detector is used to reduce background from Compton scattering. The simulation results illustrate the good suitability between response functions for point source with each radioisotope such as Na-22, Co-60 and Cs-137. Moreover, the difference between the full-energy peak efficiency of two simulation toolkits is less than 1%. This research gives the initial results to optimize the configuration of Compton suppression system and to compare with experimental data in the future.

Isaria cicadae (I. cicadae) and Isaria tenuipes (I. tenuipes) are insect parasitic fungi that contain many bioactivites including tumor inhibited activity, anticancer, immune booster. MMP-8 (Matrix Metalloproteinase-8) is one of the collagenases belonging to the endopeptidase enzyme family in mammals, related to extracellular matrix degeneration, angiogenesis, invasion and metastasis. The objective of this study conducted to investigate metastatic inhibitory activity of MMP-8 through restraining collagen resolution using 26 extracts of I. cicadae and I. tenuipes, at concentrations of 20, 200, 2000 µg/mL. Cordyceps polysaccharide extract (CPS) of I. cicadae fruiting body exhibited the highest of MMP-8 inhibitory cabacity at the concentration of 2000 µg/mL, with inhibitory ratio was 52.05 ± 0.18%. The results show the MMP-8 inhibitory potential of polysaccharide extract, plant the seed for more in-depth studies on MMP-8, I. cicadae and I. tenuipes in the future. Isaria cicadae (I. cicadae) và Isaria tenuipes (I. tenuipes) là nấm ký sinh côn trùng chứa nhiều hợp chất có hoạt tính sinh học bao gồm hoạt tính ức chế khối u, kháng ung thư, tăng cường miễn dịch. MMP-8 (Matrix Metalloproteinase-8) là một trong những collagenase thuộc endopeptidase ở động vật có vú, liên quan đến sự thoái hóa chất nền ngoại bào, tăng sinh mạch, xâm lấn và di căn ung thư. Mục tiêu của nghiên cứu nhằm khảo sát hoạt tính ức chế di căn thông qua ức chế sự phân giải collagen của MMP-8 bằng 26 loại cao chiết của hai loài I. cicadae và I. tenuipes, ở các nồng độ 20, 200, 2000 µg/mL. Cao chiết cordyceps polysaccharide (CPS) I. cicadae quả thể thể hiện khả năng ức chế MMP-8 là cao nhất ở nồng độ 2000 µg/mL, với tỷ lệ ức chế là 52,05 ± 0,18%. Kết quả cho thấy tiềm năng ức chế MMP-8 của cao chiết polysaccharide, làm tiền đề cho các nghiên cứu chuyên sâu hơn về MMP-8, I. cicadae và I. tenuipes trong tương lai.

This article, based on the Copula theory, is to establishe the weighted density and distribution functions for sum of two dependent random variables. The research also surveyed some measures to evaluate the risk for investing in a certain stock. These measures and the established functions has been used in evaluating for a plan when investing on two stocks at the same time. The article also proposes the estimations for the parameters to apply the theory to real data. Performing for the real data in Vietnam, the research  they  not only illustrate the complex calculations of the present theories, but also shows the potential in the application

Berberine (BBr), a natural isoquinoline alkaloid, has pharmacological activities such as anti-inflammatory, analgesic, antimicrobial and antitumor effects. However, the low bioavailability of BBr has restricted its applications. This study is aimed to fabricate berberine nanoparticles by roll milling method to enhance their bioavailability and study their anticancer activities. For the characterization of berberine nanoparticles, Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), X-ray Diffraction (XRD) and Ultraviolet – visible spectroscopy (UV-Vis) were employed. The results showed that berberine nanoparticles average diameters were 60 nm after 120 hours roll milling with the support of Zirconia beads. Cytotoxicity assessments indicated that Nano BBr inhibited breast cancer (MCF-7) and hepatic cancer (Hep G2) cells growth.

Carbon nanotubes were activated by a mixture of nitric acid and sulfuric acid (volume ratio 1:1) with different time and temperatures. The platinum-ruthenium electrocatalyst material (PtRu) based on activated carbon nanotubes (CNTs) was synthesized by chemical reduction method. The precursors H2PtCl6 and RuCl3 were used with the efficient reduction of NaBH4 agent in ethylene glycol. Analytical methods such as X-ray diffraction, transmission electron microscopy, and cyclic voltammetry were used for analysis and evaluation. The results showed that PtRu nanoparticles on activated CNTs were successfully synthesized. The PtRu/CNTs sample using activated carbon nanotubes for five hours at 50oC was the highest methanol oxidation ability.

The study is aimed at evaluating some biological activities of methanol extract of Hedyotis diffusa Willd. (Rubiaceae family). The chemical composition of Hedyotis diffusa Willd. contained alkaloids, flavonoids, glycosides, tannins and triterpenoids. The total polyphenol and flavonoid contents were equivalent to 83.58 ± 1.38 mg GAE/g and 398.53±7.13 mg QE/g, respectively. The results from 2.2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and reducing power (RP) assays showed slightly high antioxidant activity of the extracts from H. diffusa. The anti-inflammatory activity was determined by two in vitro methods: inhibition of heat induced denaturation of egg albumin and Bovine serum albumin. The results have shown that the percentage inhibition was observed at 200 µg/mL (57.07±5.93%) for egg albumin and (60.30±6.04%) for bovine serum albumin. The hepatoprotective activity of the extract was investigated in mice which were previously treated with carbon tetrachloride (CCl4) to induce liver damage. The extract at the dose of 100, 200 and 400 mg/kg body weight effectively reduced the level of alanine transaminase and aspartate transaminase in serum. In addition, the extract also improved the oxidative stress status in mice liver through effective reduction of malondialdehyde level and increasing of glutathione level in the liver.

The research is to build some Physics teaching processes based on 5E teaching cycle to develop high school students’ competences throughout teaching Chapter “Gas” in Physics grade 10 that contributing to the educational objectives to develop learner’s capacity of Vietnamese new curriculum (MOET, 2018). Base on 5E teaching cycle, we build successfully a teaching process for chapter “Gas” in Physics grade 10. More clearly, our new method is used for high school students throughout an experimental session. As a result, we recognize that their learning skill is developed significantly.

A previous study proved that leaf extract of mango (Mangifera indica L.) has the anti-hyperglycemia, anti-dyslipidemia, and anti-atherogenicity in alloxan-induced diabetic mice. In this study, the abilities of mango leaf extract in regulating glucose-6-phosphatase (G6Pase) and glucose-6-phosphate dehydrogenase (G6PDH) were tested. The results showed that the leaf extract of mango at the concentration of 100 and 125 µg/mL were able to inhibit G6Pase and G6PDH activities in vitro, respectively 90% and 80%. In addition, at a dose of 450 mg/kg body weight, the activities of key carbohydrate metabolising enzyme comprising G6Pase and G6PDH in alloxan monohydrate-induced toxic mice were recovered close to the normal levels. Observation of the microscopic cross section of liver tissues revealed that mice treated with mango leaf extract had significantly improvement in liver tissues compared to those of the non-treated control group. The results of this study demonstrated the efficacy of mango leaf extract in regulating enzyme activities on carbohydrate metabolism. Therefore, mango leaves can be a promising candidate for hypoglycemic drug in the future.

Based on the extraction of interval data from gray level co-occurrence matrix, this study proposes the Genetic Algorithm in Cluster analysis for Images (GACI). This algorithm can determine the suitable number of clusters, and find the objects in each cluster. The GACI is quickly performed by the established Matlab procedure. The numerical examples illustrate step by step for the GACI, and compare it with the existing algorithms. The results have shown the advantage of the proposed algorithm and the potential in real application of this research.

In this work, electronic and transport properties of the sawtooth penta-graphene nanoribbon doping by boron (B), aluminium (Al), and gallium (Ga) at various positions are systematically investigated by using the density-functional theory in combination with the non-equilibrium Green’s function formalism. Specifically, band structure, density of states, I-V curve and transmission spectrum of all samples are studied in detail. Our result shows that electronic and transport properties of the sawtooth penta-graphene nanoribbon not only depend on doped element but also doped position. Especially, all studied devices have the current intensity more than 8 orders compared to that of SSPGNR.

This research is aimed to investigate the ability of the convolutional algorithm to reconstruct the image of sample in coherent diffractive imaging using partially coherent X-ray beams. This work is performed using different degrees of coherence for the illuminating wavefield and different types of sample. The obtained results in this research allow to explore the ability to apply the convolutional algorithm in single-shot coherent diffractive imaging using partially coherent X-ray beams.

Dendrobium lituiflorum Lindl. is endemic, rare and threatened Vietnam orchids. Therefore, in order to meet the demand for a large scale production, a good propagation technique of high quality D. lituiflorum transplants is essential. In this study, the effects of sucrose concentration (0, 5, 10, 15, 20 g/L), mineral medium strength (MS, ½MS, ¼MS) on the development of shoots, roots, ex vitro planlets in shoot ventilation culture of D. lituiflorum were evaluated. The highest number of roots and ex vitro plantlet survival was observed on ½MS and ¼MS medium. Increasing numbers of shoot and root were observed in high sucrose-containing medium. However the highest survival rate was observed in ½MS medium supplemented with 10g/L sucrose (70%). This study suggests that sucrose concentration, mineral medium strength is key factors to increase plantlet survival during acclimatization.

In this article, the theory of equating the test is introduced and a procedure to write, analyze, and equate two mathematical tests of the multiple – choice questions are suggested. Statistical softwares (IATA and Excel) and Item Response Theory (IRT) were used in order to establish a common scale for two tests. These are the base to transfer the raw score as well as the latent trait or the ability score of testees from one test to another, in order to equate the difficulty between two tests and asssess exactly the ability of testees. Using the above theory, this study has experimented two one-period tests for one chapter of grade 12 mathematical curriculum for students in Bac Lieu, Soc Trang, and Kien Giang provinces in 2019.

Structures and electronic properties of gold cluster AuN (N = 2-20) are investigated by density functional theory (DFT) using LC-BLYP functional in conjunction with the consistent-correlation pseudo potential cc-pVDZ-PP basis set. The structural evolution and some basic thermodynamic parameters including the binding energy per atom, the second-order difference of energy, and the one-step fragmentation energy are determined and examined in details. Their electronic properties and stability trend are elucidated in terms of the PSM model. The optical spectra of Au6 cluster are also investigated by means of TD-DFT calculations.

The general direction of New General Education Program issued in 2018 is to transform from a content-based approach to a competency-based approach. In the 2018 program, the Science subject at primary school initially forms a scientific worldview about the natural world for pupils. The Science subject program built in this new direction requires changes in designing and organizing teachers’ teaching and students’ learning activities. The knowledge about “sound” plays an important role in this subject and should be in the process of exploring the natural world of children. Additionally, the knowledge about sound is the basic knowledge which is very important in the exploring the natural world of elementary. This article is to introduce the construction of teaching material resources about sound content in 4th Grade Science with the aim of developing naturally scientific competency and meeting the educational aims of the New General Education Program (2018).

Potassium chlorate is used to induce off-season flowering in longan. However, intensive application of potassium chlorate was shown to cause toxic effects for the environment and human health. Fourteen bacterial isolates capable of reducing potassium chlorate were isolated from soil samples collected from a longan plantation orchard in Cai Rang district, Can Tho city. After cultivating in liquid minimal salt medium added with potassium chlorate (100 ppm) and glucose (2000 ppm), 7 isolates producing high biomass were selected to determine potassium chlorate reducing efficiency. The results indicated that all isolates showed higher potassium chlorate reducing efficiency in medium supplemented with potassium chlorate and glucose compared to control treatment without glucose supplementation. Isolates CR10 and CR8 performed the highest efficiency on potassium chlorate reduction (99.8% and 97.4%, respectively) after 7 days of incubation. In sterile soil with KClO3 (375 ppm) and glucose (750 ppm) addition, the two isolates CR10 and CR8 also performed higher potassium chlorate reducing efficiency than the others (94.4% and 93.7%, respectively) after 9 days of incubation. Among these 2 potential isolates, CR8 showed chemotaxis towards potassium chlorate. Based on the 16S-rRNA gene sequence, isolate CR8 was genetically identified as Enterobacter sp. CR8. Potassium chlorate (KClO3) là hợp chất được sử dụng để xử lý ra hoa nhãn vào mùa nghịch giúp tăng hiệu quả kinh tế. Tuy nhiên, sử dụng các hợp chất có gốc chlorate vượt liều lượng cho phép gây ô nhiễm môi trường, từ đó, ảnh hưởng đến hệ sinh thái và sức khỏe cộng đồng. Mười bốn dòng vi khuẩn đã được phân lập từ các mẫu đất vườn nhãn ở quận Cái Răng, Cần Thơ có khả năng phân hủy KClO3, trong đó 7 dòng tạo sinh khối cao trong môi trường khoáng tối thiểu có bổ sung KClO3 (100 ppm) và glucose (2000 ppm). Trong môi trường khoáng tối thiểu lỏng có bổ sung KClO3 và glucose, hiệu suất phân hủy KClO3 của các dòng vi khuẩn cao hơn so với thí nghiệm không bổ sung glucose.  Dòng CR10 và CR8 có hiệu suất phân hủy KClO3 cao nhất, tương ứng 99,8% và 97,4% sau 7 ngày nuôi cấy. Khi chủng vi khuẩn vào đất đã khử trùng có bổ sung KClO3 (375 ppm) và glucose (750 ppm), 2 dòng vi khuẩn CR10 và CR8 cũng có hiệu suất phân hủy KClO3 cao hơn các dòng vi khuẩn còn lại, đạt 94,4% và 93,7% sau 9 ngày nuôi cấy.Trong 2 dòng vi khuẩn tiềm năng, dòng CR8 có khả năng hóa hướng động theo KClO3. Phân tích trình tự gen 16S-rRNA cho thấy dòng vi khuẩn CR8 thuộc chi Enterobacter và được định danh là Enterobacter sp. CR8.

In this study, molecular docking using AutoDock was utilized to analyze interactions between several promising drugs (tacrine, rivastigmine, galantamine, and donepezil) and acetylcholinesterase (AChE). The X-ray structure of AChE (PDB: 4EY6) from Protein Data Bank was used for molecular modeling simulation software (AutoDock Vina, AutoGrid4, and AutoDock4). Binding free energies of docking calculations were generated by the automatic docking method of Lamarckian genetic algorithm (LGA). Inhibitory effects of ligands were analyzed by Discovery Studio Visualizer software, which showed important interactions such as hydrogen bond, hydrophobic interaction, pi-stacking interaction between aromatic amino acids and drugs. Based on results obtained from LGA and Discovery Studio Visualizer software, the important interactions between these anticholinergic inhibitors and the active site residues were determined. This study can be further used for the virtual screening approach of house database compounds against Alzheimer’s disease.

Multiple scattering is being considered as a main reason of leading to statistical errors in position finding of incoming particles. A probability density function (PDF) of multiple scattering angles plays an important role in track-fitting of high energy physics experiments. Nowadays, the track-fitting codes in high energy physics experiments with Gaussian-PDF of multiple scattering angles are being used. That makes many errors in the track-fitting. In order to understand deeply about multiple scattering angle distribution, in this article, interaction between particles and material to estimate the PDF of the multiple scattering angles by using g4beamline simulation code was done. Base on calculation c2 and Kullback-Leibler distance, number of Gaussian functions to describe the PDF was determined.

The aim of this study was to evaluate diversification of medicinal plant resources at the Go Thap Special National Monument site in Thap Muoi district, Dong Thap province. The study was carried out through field trips and plant sampling from 50 standard squares (20 m x 20 m) with typical ecosystems. As a result, 335 medicinal plant species belonging to 243 genera, 100 families, 59 orders and 3 phyla (Polypodiophyta, Cycadophyta and Magnoliophyta) were collected. Of 335 collected species, 31 highly-conserved valuable species are threatened at national and international levels. Of which, 2 species are listed in Vietnam Red Data Book (2007), 29 species in the IUCN Red List (2019), and 1 of 29 this species is recorded in the 06/2019 Decree of Vietnamese Government. Total of 10 parts of these medicinal plants are used to treat 26 disease groups. These medicinal plants are found to grow in 6 types of habitats. The life-forms of these found medicinal plants are divided into 5 main groups (Phanerophytes, Chamaephytes, Hemicryptophytes, Cryptophytes, Therophytes) according to Biological Spectrum of the vascular flora (with life-forms spectrum BS = 57,31 Ph + 8,06 Ch + 5,67 Hm + 10,75 Cr + 18,21 Th), in which the group of Phanerophytes are the most dominant. This study contribute imprtant information and bases to the management, medicinal plant resources conservation in the monument site.

In this study, the Monte Carlo method is applied for simulating the Rayleigh-Compton measurement system using the Si(Li) detector on MCNP6 software. In which, incident photon’s energy is 59.54 keV of 241Am source and the scattering angle is determined at 124o. The targets are elements in the range of atomic numbers from 13 to 82. Besides the simulation, the theoretical values of Rayleigh-Compton ratio were calculated basing on NRFF, RFF, MFF models on MATLAB software. The results of the Rayleigh-Compton ratio from the simulation and the theoretical calculation have an average discrepancy of 4%. In conclusion, by utilizing the Rayleigh-Compton measurement system model, the effective atomic number and electron density of compounds can be determined more accurately, conveniently, and quickly. 

Kaempferia galanga L. is considered as a medicinal plant used in folkloric medicine and used in anti-inflammatory, analgesic, and anti-cancer,... Moreover, the essential oils from leaves is an incredients for medicines, perfumery, cosmetics, spices and mouthwash thanks to their antioxidant and antibacterial properties. The study is aimed to evaluate antioxidant activity in vitro and in vivo conditions of the ethanolic extract from rhizomes of Kaempferia galanga L.. The results showed that the ethanolic rhizomes extract displayed in vitro antioxidant activities using DPPH, ABTS+ and RP method, with the EC50 (effective concentration) values are 151.6±2.5 µg/mL, 2404.8±55 µg/mL and 116.5±4.8 µg/mL, respectively. In addition, D. melanogaster given extract-supplemented feed had resistance to stress conditions induced by H2O2 and paraquat better than those grown with standard food. Total polyphenol and flavonoid content were 54.42 mg GAE/g and 56.96 mg QE/g, respectively. These findings indicated that Kaempferia galanga L. is a very potential herb containing natural antioxidant compounds.

In this paper we investigate existence of solutions, optimality conditions, and solution stability for a class of optimal control problems governed by semi linear elliptic partial differential equations. In the class of optimal control problems, distributed controls and boundary controls will be considered, they may appear nonlinearly in the state equation. This class of control problems is more general and complicated, investigation of them is interesting and meaningful.

In this paper, three kinds of heterostructure of TiO2/ZnO were fabricated by combining electrochemical, sputtering and/or hydrothermal methods. The crystal structure and morphology of ZnO/TiO2 were studied by the X-ray diffraction method (XRD), scanning electron microscopy method (SEM), atomic force microscopy method (AFM). The photocatalytic performance of the TiO2/ZnO heterostructures was examined by monitoring the degradation of methylene blue (MB) under ultraviolet (UV) or visible light irradiation. The results show that all the TiO2/ZnO heterostructures exhibited the  right crystal structure of ZnO and TiO2 phases. All the TiO2/ZnO heterostructures presented superior photocatalytic activities as compared to the TiO2 or ZnO single material. In addition, amongst the three heterostructures, the TiO2-hydrothermal/ZnO rod obtained the highest reaction rate constant (0,065 min-1; 0,056 min-1), followed by TiO2/ZnO rod structure (0,054 min-1; 0,031 min-1), and double-layer TiO2/ZnO(0,05 min-1; 0,021 min-1) under UV light and visible light respectively, primarily due to the effects of enhanced charge separation and generation and the characteristics of the surface area of each heterostructure.

The study on variation of composition and individual density of cyanobacteria was conducted in Tra Vinh province in several waterbodies: natural freshwater and wastewater ponds, aquaculture ponds, rice fields, drainage channels from rice fields, river mouths during the rainy and dry season. As results, 47 species of cyanobacteria belonging to 14 genera, 9 families, 4 orders (Chroococcales, Noctoscales, Oscillatoriales, Synechococcales) were identified. The Oscillatoriales accounts for the most numberous species (44.68%) with 21 species, followed by the Nostoccales (25.53%) with 12 species, and the Chroococcales occupied for 21.28%, with 10 species. The Synechococcales has the lowest species (4 species), accounting for 8.51%. Cyanobacteria were found to distribute in all surveyed waterbodies. Of which, standing waterbodies like sewage ponds and aquaculture ponds consist of high species composition and high density of Cyanobacteria. Species composition during the rainy season is more abundant than that during the dry season (rainy season: 34/47 species; the dry season: 27/47 species). Of 47 found species, Arthrospira (Spirulina) sp. has the highest density in aquaculture ponds (D15) (50,577 individuals/L) and mainly occurs in the rainy season with the highest density of 81,953 individuals/L, while Microcytis sp. has the highest density (73,567 individuals/L) in the dry season.

A combined genetic algorithm and steepest descent method (GA-SD) is applied to determine the thickness of a 2-D sedimentary basin whose density contrast varies with depth as a parabolic function. The steepest descent’s an initial model was the best individual in the population obtained after evolutionary generations of the genetic algorithm (GA); then, the steepest descent method (SD) is applied to find a solution based on the minimum of the objective function. Firstly, it was tested on a synthetic model; then, it was applied on An Giang and Bac Lieu gravity anomalies in the Mekong Delta. The computed depths agree well with the results of the previous studies.

Colletotrichum sp. causes very popular and serious harm on many crops, from vegetables such as peppers, tomatoes, cucumber, melon, etc. to fruit trees such as mangoes, durians, papayas, bananas, dragon fruits. The study is aimed to determine the inhibition of tea tree (Meleleuca alternifolia) essential oil against Colletotrichum capsici. The in vitro result showed that inhibitory concentrations of tea tree essential oil against C. capsici was 6 μL/mL. Testing C. capsici morphological variations by SEM showed remarkable changes in the morphology and structure of mycelium. The in vivo result showed that tea tree essential oil concentration of 10% inhibited the development of lesion diameter and controlled the growth of C. capsici on postharvest capsicum fruits.