GROUP OF SUOI BA ARCHAEOLOGICAL SITES (DAK NONG PROVINCE): DOCUMENTS, PERCEPTION, AND DISCUSSION

This article introduces the results of investigations and surveys from 2006 to 2017 of the group of Suoi Ba archaeological sites in Nhan Co commune, Dak R’Lap district (Dak Nong). The results reveal eight prehistoric archaeological sites in the Suoi Ba area, which are distributed over an area of about 20 hectares, equivalent to the size of an ancient village, and date from 3,500 to 2,000 years BP. In this study, the authors systematize materials, assess historical-cultural values, briefly outline the prehistoric cultural process at Suoi Ba during the late Neolithic and early Metal Age in Dak Nong, and discuss issues related to Suoi Ba relics in a broader context

OPTIMIZING THE PRODUCTION OF A FUNCTIONAL TYPE A RECOMBINANT ENDOCHITINASE FROM Trichoderma asperellum IN Escherichia coli

Chitinases from the genus Trichoderma fungi are mainly responsible for their anti-fungal activities, which allow them to become the most widely used fungal biocontrol. Therefore, several Trichoderma chitinases have been cloned and expressed to facilitate their production and applications. A previous study of the same authors has characterized an endochitinase from a relatively novel Trichoderma spp., Trichoderma asperellum. To produce this enzyme more economically and efficiently, we reported the synthesis and expression of its synthetic encoding gene in the Escherichia coli M15 strain and established the optimal conditions for preparative scale production of the enzyme in its functional form. By lowering the induction temperatures, we observed substantial improvement in the expression levels of the active enzyme.  At 30 oC and 0.5 mM IPTG induction, 1 L of cells yielded approximately 80 - 100 mg of soluble protein, accounting for about 9-11 % of total soluble protein. This figure may be an underestimation of the actual yield, as deduced from the SDS-PAGE data. The recombinant enzyme can be retrieved by simple repeated freezing and thawing cycles and purified to near homogeneity using Ni-NTA chromatography. The purified enzyme showed in vitro colloidal chitin hydrolysis activity. These results could be scaled up to produce soluble 42 kDa chitinase in E. coli. The study demonstrated an economical method to produce chitinases for various agricultural and environmental applications

Mechanism of Inverse Magnetoresistance in High-TaT_{a} Annealed MnNi/Co/Ag(Cu)/Py Spin Valves

The magnetic transport properties -- magnetoresistive (MR) effects of MnNi/Co/Ag(Cu)/\break Py pinned spin valve structures (SVs) prepared by rf sputtering method and annealed at $T_{a} = 100$°C - 500°C for 30 minutes in high vacuum ($\sim 10^{ - 5}$ torr) are investigated. The received results show a change in the observed MR behaviors from a normal giant magnetoresistance effect to an inverse magnetoresistance effect after annealing at high temperatures, 300°C and 400°C, for these SVs. The origin and mechanism of the IMR behavior are analyzed and discussed. These results will suggest an ability to manufacture SV devices used the IMR effect for enhancing the application capacities for SV-sensor systems

Growth and development of transgenic peanut (Arachis hypogaea) lines containing chitinase 42 kDa gene from Trichoderma asperellum SH16

Peanut (Arachis hypogaea L.) is vulnerable to many diseases. Vietnam and other regions where peanut is widely cultivated have a high threat of fungal and other plant diseases. Various fungicides are available to control the fungal disease but these have various harmful effects on the natural flora, fauna, and environment. Transgenic peanut lines which possess antifungal activity provide a possible solution in managing fungal diseases apart from the traditional resistance and fungicide usage. Therefore, this study evaluated the probable growth and development of chitinase transgenic peanut lines against Sclerotium rolfsii, a pathogen that causes “southern blight” in plants, under greenhouse conditions. This study provided evidence that through Agrobacterium itumefaciens mediated transformation, 42 kDa chitinase genes from Trichoderma asperellum, which is under the regulation of 35S promoter, were successfully incorporated into the peanut’s (A. hypogaea L.) genome and expressed in their plants. This evidence also demonstrated that transgenic peanut lines were suitable for growing and developing in the greenhouse. Further, it was reported that transgenic peanut lines took approximately 133 to 145 days from planting to maturity. These results also revealed that various growth characteristics of transgenic peanut lines having two synthetic genes (syncod Chi42-2 i.e. S2-2, S2-4, S2-6, and syncod Chi42-1 i.e. S1-1, S1-2, S1-3) were greater than that from the wild-type Chi42 (WT-1, WT-2, and WT-3). In addition, yield-related parameters including the number of mature pods, 100 pods weight and 100 seeds weight for all the transgenic peanut lines were higher than that of the non-transformed plant. Among the transgenic lines, line S2-4 exhibited significantly higher growth and yield than the other transgenic lines. These results demonstrated that 42 kDa chitinase genes overexpressing peanut lines could be a candidate for improvement against plants to phytopathogenic fungus S. rolfsii and high yield.

INTEGRATED ASSESSMENT OF RISK LEVEL CAUSED BY HAZARDS IN THE COASTAL ZONE OF VIETNAM (CASES STUDY : CAM RANH-PHAN RI COASTAL ZONE)

Joint Research on Environmental Science and Technology for the Eart

An efficient protocol for in vitro regeneration of peanut (Arachis hypogaea L.) cultivar L14

The present work aims to establish an efficient protocol for in vitro regeneration of peanut (Arachis hypogaea) cultivar L14. The study showed that de-embryonated cotyledon was a suitable explant for shoot multiplication on MS medium containing 4 mg/L BAP. The highest number of shoots per explant obtained after 4 weeks of culture was up to 6.8 shoots. Shoots in vitro were able to produce a large number of approximately 11 roots on MS medium supplemented with 0.5 mg/L NAA. These results will be very useful in establishing an in vitro regeneration protocol for peanut cultivar L14 during gene transfer in the next studies to improve their disease resistance

CONTAMINATION BY PERSISTENT ORGANIC POLLUTANTS AND ENDOCRINE DISRUPTING CHEMICALS IN VIETNAM : PATTERNS, BEHAVIOR, TRENDS AND TOXIC POTENTIAL

Joint Research on Environmental Science and Technology for the Eart

Solving the Traveling Salesman Problem with Ant Colony Optimization: A Revisit and New Efficient Algorithms

Ant colony optimization (ACO) techniques are known to be efficient for combinatorial optimization. The traveling salesman problem (TSP) is the benchmark used for testing new combinatoric optimization algorithms. This paper revisits the application of ACO techniques to the TSP and discuss some general aspects of ACO that have been previously overlooked. In fact, it is observed that the solution length does not reflect exactly the quality of a particular edge belong to the solution, but it is only used for relatively evaluating whether the edge is good or bad in the process of reinforcement learning. Based on this observation, we propose two algorithms– Smoothed Max-Min Ant System and Three-Level Ant System– which not only can be easily implemented but also provide better performance, as compared to the well-known Max-Min Ant System. The performance is evaluated by numerical simulation using benchmark datasets

APPLICATION OF THE FLUX BENDING EFFECT IN AN ACTIVE FLUX-GUIDE FOR LOW-NOISE PLANAR VECTOR TMR MAGNETIC SENSORS

A concept of a planar vector magnetic sensor comprising in-plane tunnel magnetoresistive (TMR) sensors and an active flux-guide (AFG) was introduced in this work. The AFG redirected the magnetic flux at high-frequency benefiting the vertical detection capability and lessening the noise of the TMR at low-frequency measurement. The vertical sensitivity of 19.5 V/T was almost the similar the in-plane sensitivity of 19.2 V/T. In addition, the 1-Hz field noise was suppressed from 6 nT/sqrt-Hz down to 0.4 nT/sqrt-Hz. The flux bending effect of the AFG was also verified by the angular measurements with the deflected angle was found to be about 50º. It revealed that the vertical field component was certainly detected by the in-plane sensor and the proposed method was a feasible technique for the development of the low-noise planar three-dimensional magnetic sensor

TẠO DÒNG GEN MÃ HÓA CHITINASE 42 kDa CỦA TRICHODERMA ASPERELLUM VÀ DỰ ĐOÁN ĐẶC TÍNH CỦA ENZYME

Chitinase is an enzyme that catalyzes the hydrolytic reaction of chitin by cleaving 1,4-N-acetyl-β-glucosaminide linkages. Chitinase has been widely used in various fields, especially pest control, pollution reduction, and basic and applied biology. Chitinase from microorganisms is an essential source, typically from Trichoderma. After removing intron sequences, the gene encoding chitinase 42 kDa (chi42) from Trichoderma asperellum SH16 was synthesized and cloned into the pUC19 vector. The gene chi42 digested by BamHI and SacI was successfully cloned into the pQE30 vector, which was expressed in E. coli. The primary in silico analysis of the protein structure shows that chitinase is an extracellular protein. The secondary structure analysis reveals that chitinase has 15 α helices and 13 β sheets, while the dimension structure of chitinase is highly homological with the chitin hydrolytic enzyme from T. harzianum. The chitinase from T. asperellum is resistant to temperatures higher than 65 °C and exhibits acidic catalysis activity. Our results would provide basic information for heterologous expression and scale-up production of chitinase 42 kDa.Chitinase là enzyme xúc tác thủy phân chitin bằng cách phân cắt liên kết 1,4-N-acetyl-β-glucosaminide. Chitinase được ứng dụng rộng rãi trong nhiều lĩnh vực khác nhau, đặc biệt trong kiểm soát dịch bệnh, giảm thiểu ô nhiễm, nghiên cứu sinh học cơ bản và ứng dụng. Nguồn thu nhận chitinase chủ yếu là từ vi sinh vật, điển hình từ các chủng nấm Trichoderma. Gen mã hóa chitinase 42 kDa (chi42) của Trichoderma asperellum SH16 sau khi tạo dòng vào vector pUC19 được ghép nối thành công vào vector pQE30 để biểu hiện ở E. coli M15. Chitinase là enzyme ngoại bào. Cấu trúc bậc 2 của chitinase bao gồm 15 chuỗi xoắn α và 13 phiến β với cấu trúc không gian tương đồng cao với enzyme thủy phân chitin ở T. harzianum. Chitinase có khả năng chịu nhiệt độ cao hơn 65 °C và hoạt tính xúc tác mang tính acid. Kết quả nghiên cứu là cơ sở cho các nghiên cứu biểu hiện và sản xuất enzyme tái tổ hợp