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Outbreaks of the Southern rice black-streaked dwarf virus (SRBSDV) have caused significant losses in many rice-growing areas in Vietnam, especially in both North and Central Vietnam in recent years. To detect the virus, traditional reverse transcription polymerase chain reaction (RT-PCR) methodology and immunoassays are currently employed. RT-PCR is accurate but requires expensive chemicals and instruments, as well as complex procedures that limit its applicability for field tests. To develop a cheaper, simpler, and reliable SRBSDV diagnosis assay based on the dot-enzyme-linked immunosorbent assay (dot-ELISA) method, anti-SRBSDV polyclonal antibodies were produced by using the antigens derived from the P10 coat protein of SRBSDV, which was achieved from a previous study. The IgG antibody purified from the antiserum of recombinant P10-immunized mice by protein A-agarose affinity chromatography could specifically detect both the target protein and SRBSDV at a dilution of 1:100000. In the trial test of SRBSDV diagnosis, the dot-ELISA assay using the obtained anti-SRBSDV antibody showed an accuracy rate of 90.9% in comparison with the standard RT-PCR assay. These results are important premises for the large-scale application of dot-ELISA assay for SRBSDV diagnosis in order to protect rice crops against viral disease damage.

Chili (Capsicum annum L.) was one of the most important seasoning constituents of the cuisines of many countries in the world and it was ranked the fourth major crop cultivated globally. However, Anthracnose disease caused by Colletotrichum gloeosporioides has affected chili production worldwide, especially in tropical and subtropical regions. It is necessary to have greatly effective disease management. Therefore, this study had examined the antifungal effect of some nano solutions on C. gloeosporioides in both in vitro and in vivo conditions. The results clearly demonstrated that silver nano, copper nano, and silver-copper nano solutions had inhibited the spore germination and the growth of C. gloeosporioides. Inhibitory effects were 100% mycelial diameter at the solutions with concentrations of 125 ppm silver nano or 75 ppm copper nano or 50 ppm mixed silver-copper nano. The medium with the concentration of 75 ppm silver nano or 25 ppm copper nano or 12.5 ppm silver-copper nano solution completely inhibited spore germination of C. gloeosporioides. In vivo experiment, the silver-copper solutions with a concentration of 50 ppm could control the growth of C. gloeosporioides in chili fruits the findings were that there were only 13.3% disease fruits, and the inhibition efficiency was 86.7%.

The reaction-diffusion equations including the Fisher-Kolmogorov-Petrovsky-Piskunov (Fisher-KPP) and Fisher-Stefan model have been used to study biological invasion. In this thesis, we first consider the standing waves and travelling waves of the Fisher- KPP equation and the behaviour of the dynamical system near the equilibrium points. Next, we examine the existence of solutions to the Fisher-KPP model by constructing a trapping region in the plane for the wave speed 𝑐 ≠ 0. Then, we study stability of standing waves and travelling waves of this model by looking at the point spectrum, the asymptotic operator and the essential spectrum. However, a limitation of the Fisher-KPP equation is that it cannot be used to model the extinction of invasive populations in practical situations. Hence, the Fisher-Stefan equation is introduced to simulate both biological invasion for 𝑐 > 0 and recession for 𝑐 < 0. This model is reformulated from the Fisher-KPP equation and includes a moving boundary, which gives rise to a spreading-vanishing dichotomy. Moreover, we look at the existence and uniqueness of solutions to the Fisher-Stefan equation. By analysing the phase portrait, numerical results and the perturbation solutions, we can construct approximate solutions of the Fisher-Stefan equation. This phase portrait of this model also suggests that the solutions of the Fisher-KPP model exist for 𝑐 < 2 but they are unstable. Therefore, these solutions are disregarded when 𝑐 < 2 and considered as not exist. This unstable solution has value in describing solution of Fisher- Stefan problem. Thus, the stable solutions exist in the Fisher-Stefan problem. Last, we consider the spectral stability of the Fisher-Stefan equation by analysing its asymptotic operator, continuous spectrum and point spectrum. The results indicate that there is no point spectrum of the Fisher-Stefan asymptotic solution for the eigenvalue parameter 𝜆 > 1 at 𝑐 ≥ 0.

BC15 rice is a pure quality rice variety, capable of adapting to large ecological ranges, therefore chosen by farmers to cultivate on large areas. Because global warming and climate change have greatly affected the water source for irrigation, so the rice yield is significantly reduced. This study was conducted to evaluate the drought tolerance of the BC15 variety in vitro culture system to get more information about the characteristics of the BC15 variety when selecting production areas. The object of the study was to determine the most suitable artificial drought conditions for BC15 rice seedlings in vitro. The result shows that in the MS1/2 medium supplemented with PEG with osmotic potential -4 bar; or the MS1/2 supplemented with 7% Saccharose; or the MS1/2 added 3% Mannitol or MS1/2 added 4% Sorbitol, shoots of the rice can be survival. Under these artificial drought conditions caused by Saccharose, Mannitol, Sorbitol, Mannitol expressed the strongest effect on rice sprouts in vitro. Just adding 3% Mannitol to the medium, the root length and shoot height were significantly reduced compared with the control, followed by Sorbitol and finally Saccharose, significantly on the roots and shoots of the seedlings. The results of this study will support necessary information about the suitable environment to evaluate the drought tolerance of rice in vitro and the basic source for in vivo assessment.

Handling physical evidence is one of the criminal procedural activities, conducted by state bodies, during the process to resolve criminal cases. This activity requires the objectivity and fairness in the process of handling crimes, and the protection of legitimate rights and interests of relevant individuals and organizations; therefore, it contributes to the stability of the society and the development of the economy. Thus, a system of legal provisions on handling physical evidence have been developed to ensure the role of this activity, including not only criminal procedure law, but also provisions in the penal law, the civil law, and other relevant legal documents. Over the recent years, apart from successes, the implementation of activities to handle physical evidence in Vietnam in practice has revealed numerous limitations: the law on handling of physical evidence is not yet in line with the actual case settlement in practice; there are violations of the law on handling of physical evidence by competent persons, agencies, which might create conditions for abuse of powers, appropriating, damaging, losing physical evidence and might cause irreversible consequences. For those reasons, this article addresses theoretical and practical issues on the handling of physical evidence and, on that basis, proposes solutions to improve the efficiency of this activity in criminal cases at the requests of the judicial reform in Vietnam. Keywords: Physical evidence, handling physical evidence, methods to handle physical evidence, criminal procedure.

Nano silver (NS) have been known as a novel material which cannot only destroy the structure of cell microorganism but also have positive effects on in vitro plant morphology. In this research, NS was used to sterilize lily samples and stimulate lily morphogenesis in vitro. Separated bulb scales were treated in solutions of NS with four different concentrations (100, 200, 300 and 400 ppm) in five different times (60, 90, 120, 150 and 180 min) that were compared with controls being soaked in sodium hypochlorite solution. Besides, four different concentrations (2, 4, 6, and 8 ppm) of NS were also added to culturing medium that aimed to test effects of NS on lily plant growth parameters in vitro. The result illustrates that NS with 300 ppm concentration was the most useful solution for sterilizing the lily samples in 120 min., making up 87.78% sample survival and clean. Moreover, NS enhanced bulblet formation from bulb scales samples. On the medium supplemented with 4 ppm NS, 100% bulb scales were formed new bulblets with a coefficient, 2.98 after six weeks culturing; and on the rooting medium, 6 ppm NS made up the highest percentage of bulblets samples rooting, 87.33%, with the highest root number per bulblet, 3.67 and average 2 cm in length, each.

Rice breeding was conducted for a long time during historical times and is an important job in Vietnam because rice is the major food for domestic consumption and export. In this review, we have provided a comprehensive insight into the importance of promising rice germplasm resources, breeding achievements, and breeding approaches as well as discussed challenges and perspectives of rice breeding in this country. With rice germplasm and wild rice relative resources with rich and various genetic diversity, their useful genes and traits have been exploited and integrated into commercial varieties as the final outputs of rice breeding programs. New achievements of the modern genetics era have been approached and effectively contributed to breeding activities in this country. Genome sequences, molecular breeding, and mutation are powerful tools and playing vital roles in developing new varieties with characteristics of interest that should be followed by the current market demands. In the last decades, there has been a plethora of newly generated varieties by Vietnamese scientists and rice breeders and approved by the state authorities. However, very few domestic mega varieties have prevailed over the imported varieties. Therefore, rice breeding in this country is faced with big challenges, including limitations of backgrounds, budgets, and even talents in basic research to compete with other rice-producing countries. The target goals and long-term approaches for rice breeding should be paid explicitly in priority to ensure national food security and the advantage and development of rice breeding in this country.

Objective: The aim of this study was to develop and optimize the formulation of tablets containing Aquilaria crassna extract using the direct compression method. Methods: D-optimal design based on three independent variables was applied to evaluate the cause-effect relations and optimize the A. crassna tablet formulation. The weight variation (Y 1 ), disintegration time (Y 2 ), hardness (Y 3 ) and friability (Y 4 ) were investigated with respect to three independent variables including % dicalcium phosphate anhydrous (DCPA) in filler (X 1 ), % filler (X 2 ) and % croscarmellose sodium (CCNa) (X 3 ). The dissolution study of the optimized A. crassna tablets were investigated in simulated gastric fluid (SGF) (pH 1.2) using a validated high-performance liquid chromatography (HPLC) method for mangiferin analysis. Results: All investigation factors were found to have significant effects on the physical properties of A. crassna tablet. The tablet hardness and the disintegration time increased in positive relations with the ratios of DCPA. The results exhibited the negative relations between disintegration time and the percentages of CCNa. The optimized A. crassna tablet formulation which included 35 % (w/w) DCPA in filler, 60 % (w/w) filler and 7% (w/w) CCNa possessed the weight variation of 1.38 % (w/w), the disintegration time of 6.29 min, the hardness of 85.63 N and the friability of 0.41 % (w/w). The optimized A. crassna tablet formulation was experimentally examined which demonstrated a good agreement between the experimental and predicted values. Mangiferin was found to release completely from the optimized A. crassna tablets within 30 min. Conclusion: The cause-effect relations and optimization of A. crassna tablet formulation were investigated and reported for the first time. The A. crassna spray-dried extract could be formulated into tablet by direct compression method with good mechanical properties and acceptable release profile.