bluuebunny/crossref_metadata_2025 huggingface dataset:
APPLYING THE ATTRIBUTED PREFIX TREE FOR MINING CLOSED SEQUENTIAL PATTERNS
Authors: Thiet Pham Thi
Published: April 2018

Mining closed sequential patterns is one of important tasks in data mining. It is proposed to resolve difficult problems in mining sequential pattern such as mining long frequent sequences that contain a combinatorial number of frequent subsequences or using very low support thresholds to mine sequential patterns is usually both time- and memory-consuming. This paper applies the characteristics of closed sequential patterns and sequence extensions into the prefix tree structure to mine closed sequential patterns from the sequence database. The paper uses the parent–child relationship on prefix tree structure and each node on prefix tree is also added fields to determine whether that is a closed sequential pattern or not. Experimental results show that the number of sequential patterns is reduced significantly.
INTELLIGENT DISTRIBUTED COOPERATIVE CONTROL FOR MULTIPLE NONHOLONOMIC MOBILE ROBOTS SUBJECT TO UNKNOWN DYNAMICS AND EXTERNAL DISTURBANCES
Authors: Luy Nguyen Tan
Published: April 2018

This paper addresses an optimal cooperative tracking control method with disturbance rejection in the presence of no knowledge of internal dynamics for multi-nonholonomic mobile robot (NMR) systems. Unlike most existing methods, our method integrates kinematic and dynamic controllers into one using adaptive dynamic programming techniques based on the concept of differential game theory and neural networks, and is therefore entirely optimal. First, with the aim to reduce the computational complexity, the number of neural networks for each agent in the method is chosen to be less than one-third. Second, novel weight-tuning laws of the neural networks and online algorithms are proposed to approximate solutions of the Hamilton-Jacobi-Isaacs equations. By using Lyapunov theory, value functions and both cooperative control and disturbance laws are proved convergence to the approximately optimal values while the cooperative tracking errors and function approximation errors are uniformly ultimately bounded. Finally, the effectiveness of the proposed method is demonstrated by the results of the compared simulation and experiment on a multi-NMR system equipped with omnidirectional vision.
MODEL CHECKING EARLY REQUIREMENTS SPECIFICATIONS IN ALLOY
Authors: Phuoc Ton Long
Published: April 2018

Automation generated source code and verifying are essential sector for software engineering. There are many ways to generate source code and verify from the specification languages. In this paper, we propose an approach that automatically generated code from a specification language Alloy. From this specification language, we will describe how to translate from one language to the Java source. An application in this paper is a gardening game program. Applied after the findings will be organized according to the MVC (Model-View-Controller) architectural pattern. Besides, we will also verify the identity of the structure of the application and the content of the Alloy specification. We built an tool as GmDSL, we have verified the aplication in GmDSL. The application was created from the tool also shows the correctness of the early constraints. Simultaneously, we also compares be verified through the GmDSL tool with NuSVM tool.
SYNTHESIS AND CHARACTERIZATION OF FEED GRADE MONOCALCIUM PHOSPHATE, Ca(H2PO4)2·H2O IN AQUEOUS MEDIUM
Authors: Bac Nguyen Quang
Published: April 2018

The feed grade monocalcium phosphate monohydrate, Ca(H2PO4)2·H2O was prepared by the reaction of CaCO3 and H3PO4 at elevated temperature in aqueous solution. The obtained precipitates were characterized by powder X-ray diffraction, infrared spectroscopy (FTIR), and thermal analysis (TG, DTA) techniques. The chemical composition of final products was evaluated by analysing the phosphorus and calcium content in the samples.
TỐI ƢU HÓA CÁC YẾU TỐ ĐỂ HẠN CHẾ SỰ SINH TRƢỞNG CỦA ASPERGILLUS FUMIGATUS TP01 VÀ ASPERGILLUS ORYZAE TP01
Authors: Kim Liên Phan Thị
Published: April 2018

Nghiên cứu được thực hiện với mục tiêu là đánh giá ảnh hưởng của nhiệt độ, hoạt độ nước và ethanollên sự sinh trưởng và phát triển của hai chủng Aspergillus fumigatus Tp01 và Aspergillus oryzae Tp01 và tối ưu hóa các yếu tố trên để hạn chế sự sinh trưởng và phát triển của chúng. Đánh giá khả năng kìm hãm sự sinh trưởng của chúng dựa trên tốc độc tăng trưởng ở các hoạt độ nước 0,85 ÷ 0,99 và nồng độ ethanol 1 ÷ 5 % với các mốc nhiệt độ 18 ÷ 50 oC trong 7 ngày nuôi cấy. Từ các số liệu thực nghiệm tiến hành tối ưu hóa các cặp yếu tố bằng phần mềm Modde 5.0. Kết quả nghiên cứu cho thấy: 42 oC và aw= 0,912; aw= 0,9 và 50 oC là điều kiện tối ưu để kìm hãm tốc độ tăng trưởng của Asp. oryzae Tp01 (60,3 10-5 mm.ngày-1) và Asp. fumigatus Tp01 (59 10-3 mm.ngày-1). 5 % ethanol và 34 oC là điều kiện tốt nhất để giảm tốc độ tăng trưởng của Asp. oryzae Tp01 (39,7 10-3 mm.ngày-1); 5 % ethanol cũng là điều kiện tối ưu để ngăn chặn tốc độ tăng trưởng của Asp. fumigatus Tp01 (20,46 10-2 mm.ngày-1) ở nhiệt độ 38 oC.
ĐẶC ĐIỂM SINH HỌC VÀ KHẢ NĂNG SINH TỔNG HỢP CHẤT KÍCH THÍCH SINH TRƢỞNG THỰC VẬT CỦA XẠ KHUẨN NỘI SINH STREPTOMYCES HEBEIENSIS TQR8-7
Authors: Hồng Thảo Phan Thị
Published: April 2018

Trong tự nhiên, ngoài thực vật, một số nhóm vi sinh vật cũng có khả năng sinh chất kích thích sinh trưởng thực vật indole-3-acetic acid (IAA). Xạ khuẩn nội sinh là những loài xạ khuẩn cư trú trong nội mô thực vật mà không gây hại cho cây chủ. Ngày nay, đối tượng này được quan tâm nghiên cứu do có khả năng sinh nhiều hợp chất trao đổi thứ cấp có tác dụng điều hòa sinh trưởng và kiểm soát dịch bệnh cho cây trồng, do đó có tiềm năng ứng dụng trong sản xuất nông nghiệp bền vững. Bài báo này trình bày kết quả nghiên cứu khả năng sinh IAA của các chủng xạ khuẩn nội sinh phân lập được từ cây có múi đặc sản của miền Bắc như cam Hàm Yên (Tuyên Quang), Cao Phong (Hòa Bình), bưởi Diễn Hà Nội. Trong số đó, chủng xạ khuẩn nội sinh TQR8-7 có khả năng sinh IAA cao nhất, được nghiên cứu về đặc điểm sinh học, phân loại và điều kiện sinh tổng hợp IAA. Trong phòng thí nghiệm, xạ khuẩn TQR8-7 sinh trưởng tốt trên nhiều loại môi trường thử nghiệm, với khoảng nhiệt độ sinh trưởng từ 15÷40ᵒC, pH 5÷10 và chịu được độ muối đến 5 %. Chủng TQR8-7 có khuẩn ty khí sinh màu vàng ngả xám nhạt đến xám xanh trên các môi trường ISP 2, 3, 4 và 8, sinh ra nhiều chuỗi bào tử dài xoắn lò xo, mỗi chuỗi mang từ 30-50 bào tử có bề mặt dạng mụn cơm. Chủng TQR8-7 có khả năng đồng hóa tốt D-glucose, D-sucrose, D-xylose, D-cellulose và D-rhamnose, và sinh enzym ngoại bào như cellulose, xylanase. Dựa vào các đặc điểm sinh học và phân tích trình tự gen 16S rDNA, có thể xếp chủng TQR8-7 thuộc chi Streptomyces, loài S. hebeiensis, nên được đặt tên là Streptomyces hebeiensis TQR8-7. Chủng S. hebeiensis TQR8-7 có khả năng sinh IAA cao nhất là 37 μg/ml trên môi trường 79 có bổ sung 0,2 % tryptophan, ở nhiệt độ 37oC và pH 7,0.
EFFECT OF ULTRASOUND ON PRETREATMENT OF TUNA SKIN FOR GELATIN PRODUCTION
Authors: Nhat Dang Minh
Published: April 2018

This paper presents the result of study on the effect of ultrasound on extraction yield and quality of gelatin obtained from tuna skins using alkaline treatment method and alkaline-acid treatment method with ultrasound assistance. The results showed that ultrasound could shorten the time of alkaline treatment, while ensured the yield and the quality of obtained gelatin. Accordingly, the appropriate parameters of ultrasound mode that gave the best yield and quality of gelatin were determined as follows: for alkaline treatment method: amplitude of 80 %, period of 0.8s and ultrasound time of 90 min; for the alkaline-acid treatment method: amplitude of 8 0%, period of 0.8s and ultrasound time of 30 min. The former method produced gelatin with better yield and gel strength compared to the latter one (22.7 % and 143.3 g in comparison with 15.8 % và 122.4 g, respectively). The method with ultrasound support gave the gelatin with better quality in term of lipid content and gel strength in comparison with the traditional alkaline treatment method without ultrasound assistance.
ISOLATION, SCREENING AND THE INFLUENCE OF CULTIVATION FACTORS ON CELLULASE OF BACTERIA ISOLATED FROM TERMITES GUT
Authors: Nguyen Hien Thi
Published: April 2018

From five termites guts samples collected in different places in Ha Noi and Vinh, 11 isolates which formed halo on agar plates with CMC were isolated. Among them strain G4 possessed the highest CMCase activity. Based on morphology and 16S rRNA gene sequences analysis, G4 was identified as Bacillus subtilis G4. The results from cultivation study revealed that M3 medium containing rice bran 1 %, soy flour 1 %, casein 1 % and 1 % NaCl  was the best medium for cellulase production of B. subtilis G4. At optimal conditions for G4 which were  inoculums ratio 1 %, cultivation temperature 37ºC, cultivation time 72 hours, shaking speed 150 rpm and initial pH medium 7, CMCase and FPase activity reached 3.36 U/ml and 0.35 U/ml, respectively.
RESEARCH ON PROTEIN HYDROLYSIS FROM SHRIMP WASTE USING COMMERCIAL PROTEASES
Authors: Linh Tran Chi
Published: April 2018

Protein hydrolysates were produced from shrimp waste mainly comprising head and shell by different commercial proteases (Alcalase, Protamex, Flavourzyme). Shrimp waste was mixed with water (ratio of 1:5 w/v) and was treated with protease individually or together, which were incorporated either simultaneously or sequentially. Temperature was kept at the optimum for each enzyme. pH was initially adjusted to the most favorable value for each enzyme. Result of study showed that in case of individial addition, the highest yield of protein recovery (YPR 48.88 %) was obtained with Alcalase (375 U/g material) at 50 °C, pH 8 for 4 hours. Besides, the maximal yield of amino acids recovery (2.91 %) was obtained with Flavourzyme (250 U/g material) at 50 °C, pH 7 for 4 hours. Specially, the sequential treatment with Alcalase and Flavourzyme improved significantly the hydrolysis of protein. The yield of protein recovery (YPR 49.13 %) and yield of amino acids recovery (YAR 6.91 %) were obtained by addition of Flavourzyme 6 hours after Alcalase, which is attributed to the combined nature of the endo- and exocatalytic action of Alcalase and Flavourzyme, respectively. This research shows the feasibility of hydrolyzing shrimp by-products using different commercial proteases.
COMPARISON OF RADICALS SCAVENGING ACTIVITY OF EXOPOLYSACCHARIDES FROM CULTURED CORDYCEPS SPP. ISOLATED IN VIET NAM
Authors: Ho Thi Phuong Tham
Published: April 2018

Cordyceps is a well-known traditional medicine to heal various serious diseases for centuries. Besides, polysaccharides isolated from Cordyceps had demonstrated to exhibit potential bioactivities, especially antioxidant activity. Hence, this study concentrated on the antioxidant effects of exopolysaccharides (EPS) isolated from ten kinds of Cordyceps cultured broth. Consequently, Cordyceps sinensis cultured broth possessed the highest EPS as well as total carbohydrate content, but the nearly lowest protein content (2.75 g/l, 69.39 % and 1.01 % respectively).  Most of EPSs exhibited potential radical - scavenging activities suggesting that EPSs would have been regarded as antioxidant resources. Nonetheless, the EPS from DL0067 possessed the highest ABTS radicals scavenging activity (IC50 value = 1026.70 ± 3.64 µg/ml) but low hydroxyl radicals scavenging activity (IC50 value > 5,000 µg/ml). The EPS from DL0075, in contrast, exhibited the highest hydroxyl radicals scavenging activity (IC50 value = 463.15 ± 26.19 µg/ml). All in all, the experiments were indicated higher antioxidant activities of EPS from Cordyceps isolated in Viet Nam than those from Cordyceps sinensis. These findings demonstrated that the antioxidant activities related to complexes of polysaccharides and proteins instead of only polysaccharide contents.
STUDY ON THE USE OF ACIDOPHILIC IRON OXIDIZING BACTERIA FOR DISSOLVING IRON FROM LOW-GRADED CHALCOPYRITE ORES
Authors: Hung Nguyen Van
Published: April 2018

Biomining is a microbiological-based approach to extract minerals from ores without adding acids and other extraction chemicals. Having biological nature, the process is considered environmental friendly and tends to be applied more widely nowadays, especially for low-graded ores, for which chemical extraction is no longer efficient. In this study, two iron oxidizing bacterial strains Acidithiobacillus sp. IOB1 and Leptospirillum sp. IOB2 originated from mining sites in Vietnam were used in laboratory leaching experiments for the recovering minerals from low-graded chalcopyrite ores. The obtained results showed that both strains could significantly accelerate the leaching process, the highest iron dissolution rate was estimated for 0.83 g×kg-1×d-1 within two weeks of incubation with strain IOB2, about 30 % and 50 % respectively higher than leaching with strain IOB1 or control without bacteria, respectively. The iron extraction from ores was also evidenced by EDX analyses comparing the ore particles before and after incubation with the bacteria. Microscopic observation of DAPI-stained ore particles also showed high cell density attached to the particles, instead of freely moving in the liquid extract. Furthermore, FISH analyses using a specific probe for the g-Proteobacteria GAM42a revealed that only ~50 % of DAPI-stained cells were Acidithiobacillus sp. IOB1 – like in the leaching experiment with this train as starting culture, indicating that other bacterial species have developed and contributed to the metal dissolution here; however very rare positive signals were observed in leaching experiment with strain IOB2 as starting culture or the control without added bacteria. Thus, the acidophilic iron oxidizing strains Acidithiobacillus sp. IOB1 and Leptospirillum sp. IOB2 could serve as potential microbial sources for the development of biologically based approaches to extract minerals from ores, especially for those having low mineral contents.
CHEMICAL CONSTITUENTS FROM THE SEEDS OF ANNONA RETICULATA L. IN VIETNAM
Authors: Hung Nguyen Huy
Published: April 2018

In the present study, the chemical investigation of the seeds of A. reticulata L. (Annonaceae) in Vietnam has resulted in the identification of four known compounds, including two triterpenoids (rotundic acid (1), pedunculoside (2)), and two phenolic compounds (eleutheroside B (3), sinapaldehyde glucoside (4). Their chemical structures were elucidated on the basis of spectroscopic analysis, including homonuclear and heteronuclear correlation NMR (1H-NMR, 13C-NMR, COSY, HSQC, and HMBC) experiments.
IN VITRO ASSESSMENT OF POTENTIAL PROBIOTIC MICROORGANISMS FOR APPLICATION IN ANIMAL FEEDING
Authors: Hong Van Le Thi
Published: April 2018

This study aimed to evaluate and to select potential probiotic microorganisms. The obtained results would be further studied for application in production of animal feed. A total of 16 strains of microorganisms including 11 strains of Lactobacillus, four strains of Bacillus and a yeast strain Saccharomyces boulardii PLCP were investigated for acid production, digestive enzyme production and antimicrobial activity as well as their survival when exposed to simulated gastrointestinal conditions. The results showed that all 11 strains of Lactobacillus bacteria were capable of acid generation (in the range from 18.05 – 19.04 g/l). All four strains of Bacillus bacteria were capable of producing protease. Only Bacillus sp D7 strain was capable of producing three digestive enzymes (protease, amylase, cellulase) with hydrolyzed hollows ranged from 15.5–18.5 mm. The antibacterial activity of 9/16 test strains was positive against Salmonella Typhimurium, Staphylococcus aureus and Escherichia coli. Survivability of 15 test microorganisms in simulated gastrointestinal conditions was relatively high (c.a. 80 %). Three strains of L. acidophilus VAST, S. boulardii PLCP and Bacillus sp D7 when in mixture demonstrated a great potential as probiotics for animal.
EFFECT OF SUCROSE AND SODIUM POLYPHOSPHATE ON RETROGRADATION OF RICE STARCHES
Authors: Nga Luong Hong
Published: April 2018

Starch retrogradation is a process occurred in many food products made from starch-containing raw materials. It affects qualities of food during storage. In this research, the effects of sucrose and phosphate on rice starch retrogradation were studied. Experiments were conducted with sucrose content ranged from 1 – 5 % (w/w) and sodium polyphosphate – from 0.1 – 1 % (w/w). Results showed that sucrose and polyphosphate reduced the syneresis of starch gel 1.19 - 1.44 and 4.6 - 4.87 times respectively. Both substances reduced the hardness of starch gel, but sucrose reduced the stickiness while polyphosphate increased stickiness of rice starch gel.
PRODUCTION OF POLYCLONAL ANTIBODIES AGAINST RECOMBINANT VP6 ANTIGEN OF ROTAVIRUS
Authors: Thu Nga Do Thi
Published: April 2018

Rotavirus is the most common cause of diarrhea in infants and young children under five years old. The VP6 protein of rotavirus was considered as an important antigen in the development of novel vaccine generation and diagnostic tools. Polyclonal antibodies of VP6 antigen could be used to generate a rapid test based on the lateral flow immunoassay. In the present study, we showed the results of synthesis of polyclonal antibodies against recombinant VP6 protein of rotavirus. Recombinant VP6 protein was strongly produced by E. coli in suitable conditions. The properties of recombinant VP6 protein were characterized by Western blot and ELISA methods. Pure recombinant VP6 protein was used as an antigen to inject into the rabbits. The recombinant VP6 protein was highly immunogenic in rabbits. Anti-VP6 antibodies were purified from the rabbit serum using the Protein A affinity chromatography. The specificity of the antibody towards its antigen was characterized by Western blot and ELISA immunoassay. The purity of antibody was reached as 97 %. The efficiency of antibody production in rabbit was 3.94 mg/ml serum. The amount and quality of the obtained anti-rotavirus VP6 antibody was suitable for application in the development of the diagnostic kits.
STUDY ON TREATMENT TECHNOLOGY OF “TAO MEO” USING PECTINASE ENZYME IN “TAO MEO” VINEGAR PRODUCTION BY SUBMERGED METHOD
Authors: Viet Anh Nguyen Thi
Published: April 2018

“Táo mèo” vinegar, a fat-burner famous for its many benefits for the digestive and immune systems, can be consumed as functional drinks. However, “táo mèo” vinegar is still producing mainly in manual-based, small-scaled with the surface fermentation method and containing many hazards. For industrial scales, the application of pectinase during the fruit extraction process has increased the quality of end-products and extraction efficiency, leaving no residue during storage. This research focus on the simultaneous application of two kinds of pectinase: PectinexUltra SP-L and PectinaseUltra Clear, during the extracted processing of “táo mèo”. The results indicated that simultaneously using both enzymes has increased the extractivity of the process to 25 %, and also has increased the amounts of function substances such as vitamin C, polyphenol, sugar, acid, and soluble pectin, compared to not using enzymes. The extractive process using the two enzymes for the fruit extracts is determined as follows: PectinexUltra SP-L is used at  concentration of 0.15 %, temperature is 30 oC for 60 minutes;  followed by  using PectinaseUltra Clear with concentration of 0.1 %, temperature is 55 oC for 60 minutes. The enzyme processing does not interfere with the vinegar fermentation process; vinegar  with  enzyme pretreatment contains higher amounts of polyphenol, vitamin C, and potassium compared to that without enzyme pretreatment. The amount of soluble pectin in vinegar with enzyme pretreatment stays constant with no sediment during six months of storage, whereas vinegar without enzymes pretreatment  produces precipitation afer two months of storage.
SOLVOTHERMAL SYNTHESIS OF BI2WO6 AND ITS PHOTOCATALYTIC ACTIVITY UNDER VISIBLE LIGHT IRRADIATION
Authors: Nguyen Trinh Duy
Published: April 2018

Flower-like Bi2WO6 were successfully synthesized using the solvothermal method at different temperatures and characterized by XRD, FE-SEM, and DRS. We also investigated the photocatalytic activity of Bi2WO6 for the decomposition of rhodamine B under visible light irradiation. From XRD and SEM results, the reaction temperature has significant effects on the morphologies of the samples. From DRS results, Bi2WO6 samples displayed the absorption spectrum up to the visible region and then they showed the high photocatalytic activity under visible light irradiation, as a comparison with TiO2-P25.
OPTIMIZATION OF SIMAFIX RED DYE DECOLORIZATION BY USING ADVANCED OXIDATION PROCESS: PHOTO-FENTON
Authors: Dinh Nga Thi
Published: April 2018

This study investigated the Photo-Fenton process in textile wastewater treatment by using textile synthesis wastewater made of Symafix Red Dye solution. The aim of the study was to investegate the factors that influent to the photo-Fenton process such as contact time, pH, H2O2 and Fe2+conectrations, and UVexposure in order to research the optimum values of this process.Treatment of textile wastewater was carried out at ambient temperature in a batch reactor. As a result, the second-order is suitable for the reaction of removing color by using Photo –Fenton processes. The removal efficiencies decreased when we increased the concentration of Fe2+ from 7.162 mM to 14.162 mM. When we increased the H2O2 concentration from 0.037 mM to 0.11mM, the removal efficiencies slightly decreased. The optimum value of pH is pH = 3. At the optimum of pH value and minimum the concentration of Fe2+ and H2O2 the removal efficiency could reach up to 95.82 %.
PERFORMANCE OF TiO2 IN PHOTODEGRADATION SEAFOOD WASTEWATER
Authors: Loc Luu Cam
Published: April 2018

In this work, photocatalysts TiO2-HT prepared by hydrothermal method and TiO2-P25 Degussa were characterized by Energy Dispersive X-Ray analysis (EDX), X-ray powder diffraction analysis (XRD), Raman Spectroscopy, BET surface area measurements, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and UV-Vis absorption spectroscopy and tested in degradation of recalcitrant organic pollutants in bio-treated seafood wastewater (COD > 80 mg/L). After 9 hours of photodegradation under UV-A irradiation, COD removal efficiency reached 85.6 % and 48.9 % on TiO2-P25 and TiO2 catalysts, respectively. COD values of seafood wastewater treated by photocatalysis met the standard discharge requirement - QCVN 11:2008 – level A (COD £ 50 mg/L).
ISOLATION AND IDENTIFICATION OF AEROBIC MICROBIAL COMMUNITY TREATING BENZENE FROM A CONSTRUCTED WETLAND SYSTEM
Authors: Vuong Tran Hau
Published: April 2018

The main objective of this study was to isolate and identify the aerobic bacteria in bacterial community of constructed wetland in Vietnam, which were spiked with benzene. For this target, four random samples of rhizosphere soil of phragmiteskarkas from constructed wetlands in Vietnam were collected and mixed together. The soil sample was labeled VS. Bacteria in the sample was grown in 80 mg/L benzene liquid media with optimal conditions of temperature and shaken to find out whether bacteria in the sample can remove benzene or not. The result showed that bacteria in the sample can survive and treat benzene well. Strains of bacteria were isolated through incubation in Burk’s medium mixed with benzene. The strain named VS1 from VS sample was obtained. The strain adapted well in agar medium containing benzene as sole carbon source. Through molecular methods, VS1 was identified as PandoraeapnomenusaCM25.
REUSE OF A CLOSED LANDFILL SITE FOR INSTALLATION AND OPERATION OF A BIOMASS UTILIZATION PLANT
Authors: Anh Le Hung
Published: April 2018

The professional management of landfills during operation and after landfill capping is an important task to prevent environmental impacts. Landfill maintenance after closure can become economically favourable if landfill sites can be reused. Several approaches and experiences for reuse of capped landfills exist for example in livestock farming or installation and operation of solar power plants. Also the utilization for spare time activities after green capping and recreation or the industrial reuse for the development of a waste utilization plant is a common practice in Europe. The feasibility of reuse options depend on the site conditions including size and location of the landfill, the climatic conditions and the interests of the involved stakeholders. For the urban landfill site Gò Cát in Ho Chi Minh City (HCMC) experts from Germany and Vietnam developed a variant assessment for the preferred reuse options. One of three investigated options is considering the reuse of the landfill site for the development of a biomass utilization plant. In terms of the above described approach for Gò Cát the landfill operator is strongly involved in the landfill closure and long term maintenance works (leachate treatment, landfill gas utilization). Moreover, the operator can reuse the landfill site for an additional or new business. The design and operation criteria for the biomass utilization plant and best practice examples are presented. Beside the economic evaluation results of water and landfill gas balance will be discussed.
CO-OXIDATION REACTION ACTIVITY OF Pt CLUSTER CATALYSTS ON Ti0.9MO0.1O2 SUPPORT
Authors: Nguyen Trung Thanh
Published: April 2018

Platinum-based heterogeneous catalysts are critical to many important commercial chemical processes. However, their efficiency is extremely low on a per metal atom basis, because only the surface active-site atoms are used. Catalysts with clusters of atom dispersions are thus highly desirable to increase atom efficiency, but making them is challenging. Here we report the synthesis of a catalyst that consists of isolated clusters of Pt atoms anchored to the surfaces of Molybdenum-doped titanium oxide nanocrystallites. This cluster-atom catalyst has extremely high atom efficiency and shows excellent stability and activity for CO oxidation. The result showed that the highest activity and stability of catalyst with 0.2 wt.% loading of Pt are observed. These could be due to the partially vacant 5d orbitals of the positively charged, high-valent Pt atoms.
EVALUATION OF THE EFFECTIVENESS OF AUTOMATIC SPRINKLING SYSTEM FOR SHALLOT CULTIVATION IN VINH CHAU DISTRICT, SOC TRANG PROVINCE
Authors: Hoang Hong Minh
Published: April 2018

Shallot is one of the main crops in Vinh Chau district, Soc Trang province where farming techniques are still simply and mainly based on traditional irrigation types. In the district, groundwater is the main water source for daily uses of the local and farming activities. However, this water source increasingly becomes scarity due to over-exploitations. Therefore, this study aims to save water in agricultural production by applying automatic sprinkling irrigation model (Sprinklers system) in shallot farming and Vinh Chau district is selected as the research site. In this study, the amount of irrigation water for Shallot will be determined by CropWat model and the irrigation time will be measured by a soil moisture device (Takemura DM -15). The results show that the automatic sprinkling system model has saved by 43 - 59 % water amount and 85-91 % time of irrigation per 1000 m2 compared to traditional irrigation methods. The input costs of automatic sprinkling system are estimated at about 8 million VND/1000 m2 and it can be applied for many types of plants with its span of 4 years (depending on users’ uses). In conclusion, the automatic sprinkling irrigation model can alter traditional methods of famers in order to improve productivity, reduce negative impacts on groundwater source, and to adapt to water shortage due to climate change impacts.
INTEGRATED EVALUATION MODEL FOR SURFACE WATER QUALITY A CASE STUDY IN HO CHI MINH CITY, VIETNAM
Authors: Minh Nguyen Thu Thi
Published: April 2018

The quality of water is a measure of a number of characteristics that impact on its condition.  Parameters affecting the water quality are classified as having chemical, physical, biological and radiation characteristics.  However there is uncertainty as to whether or not a water sample meets set standards in quality if two or more parameters need to be considered.  Therefore, this study is to develop an effective evaluation model, adopting fuzzy logic, to assess the quality of water.  Using a case study in Ho Chi Minh, Vietnam, a model has been developed and applied the collected surface water monitoring data in 2015.  The results obtained from this model are then compared to the results gained from Vietnam national water quality index established in 2011.
EFFECTS OF THE SEA LEVEL RISE ON UNDERGROUND WATER RESOURCES IN HO CHI MINH AREA
Authors: Ky Nguyen Viet
Published: April 2018

Ho Chi Minh City has 7 aquifers with different distributions, ascending from the east, western-north to eastern-southeast with total potential reserves of about 1.65 million mP3P of fresh water/day, potential reserves of underground water brackish-salty approximately 2.25 million mP3P/day. This resource is invaluable for the development of the city today and the future. However, groundwater resources are at risk of depletion of reserves, quality under the impact of climate change and sea level rise. In this paper, the authors focus on evaluating the impact of rising sea levels to shift the boundaries of the aquifer salinity, which narrow the area of fresh water and diminishing reserves of fresh water . To assess, first based on climate change scenarios and sea level rise has been Vietnam announced in 2012, at the same time as the underground water is exploited more constant (the maximum amount of water extraction in 2015 basis), the authors conducted for running surface flow model to get the water level data at some point to put into models of groundwater flow. Thanks to model groundwater flow, the authors showed that the sea level rise significantly shift the boundaries of the aquifer salinity toward the inner city. The area contains fresh water and reduced water reserves only light compared with present reserves.
A RESPONSE SURFACE METHODOLOGY APPROACH FOR THE OPTIMIZATION OF CU2+ REMOVAL USING RICE HUSK–DERIVED ACTIVATED CARBON
Authors: Bach Long Giang
Published: April 2018

In this study, we have used the potassium hydroxide (KOH) as an eco–friendly and favorable activating agent to develop the porous and defect structure of activated carbon. Otherwise, the response surface methodology (RSM) has been applied to investigate the effects of the adsorption parameters including initial concentration, adsorbent dosage, and pH of solution on the percentage of Cu2+ removal. The RSM–based two order regression polynomial models were found to be statistically signiﬁcant by values of the coefficients of determination (R2) closer than 1.0 and the P–values < 0.0001 from analysis of variance (ANOVA). Under the predicted optimum conditions, actual experiments were confirmed to optimize the percentage of Cu2+ removal efficiency (97.5 %) and maximum adsorption capacity (24.45 mg.g–1) from Langmuir equation. Based on experimental results, a treatment process can be easily designed using rice husk for the fabrication of activated carbon to remove toxic metal ions from the polluted water.
ANALYSIS OF SURFACE LAYERS OF HOT – FORGING DIES OF SKD61 STEEL FABRICATED BY DIE – SINKING ELECTRICAL DISCHARGE MACHINING USING COPPER AND TITANIUM ELECTRODES
Authors: Phan Nguyen Huu
Published: April 2018

Electrical discharge machining (EDM) is a popular unconventional method for manufacturing tools, molds, and dies. Currently, the surface layer of the hot die after EDM needed to be polished to remove the layer of » 50 mm. This is accepted according to practical experience and the lack of scientific basis because of limited research on the surface layer quality of the products after EDM and the study is focused on the evaluation of the product quality in the final processing. This study is aimed at the investigation of performance and structure of the surface layer in hot-forging die following die-sinking EDM. The machining conditions included the use of copper (Cu) and titanium (Ti) as electrode materials. A cross-sectional micrographic and hardness analysis was performed, as well as surface roughness measurements, in order to study the thermally affected zones of the hot-forging die surface layer of the SKD61 steel after EDM using oil as the dielectric fluid. The results showed that the performance of the die was reduced due to changes in the hardness and the chemical composition of the workpiece surface. The surface quality of hot-forging die after EDM with Ti or Cu electrode are similar. In this case, EDM using Ti electrode to improve the quality of hot die surface layer was unreasonable.
D,L-SERINE BASED pH-SENSITIVE OLIGOESTER
Authors: Tri Dang Nguyen
Published: April 2018

In recent years, pH/temperature-sensitive polymers have attracted increasing attention as drug/protein delivery systems. In this study, the main objective was to synthesize a pH-sensitive oligoester. The oligoester was synthesized by condensation reaction from carboxylic and hydroxyl groups of D,L-Serine, which had been previously modified with benezenesulfonyl chloride in order to create sulfonamides as pH sensitive groups. Various molecular weights of the oligoesters were obtained by means of manipulating the mole ratio of N,N'-Dicyclohexylcarbodiimide (DCC)/Serine (DCC acts as a coupling agent) and the Dimethylformamide (DMF)/Serine (v/w) ratio (DMF acts as solvent). The synthesized oligoesters were characterized by 1H-NMR and their molecular weights were measured by gel permeation chromatography (GPC). Also, the pKa values of pH-sensitive oligoesters were obtained by the titration method. This pH dependent property of the polymers could be very useful for preparing drug carriers that are sensitive to pH environment.
EFFECT OF AGING TREATMENT PARAMETERS ON MICROSTRUCTURE AND PROPERTIES OF Cu-Ni-Si ALLOY
Authors: Anh Phung Tuan
Published: April 2018

In this paper, effect of cold pre-deformation and sequent aging time and temperature on microstructure and properties of Cu-2.8Ni-1.0Si alloy are reported. The results shown that, hardness and electrical conductivity of alloy increase with increasing cold deformation degree after quenching and subsequent aging. With undeformed specimens after quenching, hardness and electrical conductivity of alloy reach maximum values with subsequent aging at 425 and 475 oC, respectively. Alloy attains maximum hardness of 255 HV5 with aging at 425 oC for 4.5 hours, while maximum electrical conductivity of 38.5 %IACS with aging at 475 oC for 8 hours. In the case of deformed specimens after quenching and subsequent aging, this rule is still preserved. Especially, at 70 % cold pre-deformation degree, alloy attains the maximum hardness of 274.3 HV5 with aging at 425 oC for 3.5 h, while maximum electrical conductivity reaches 42.4 % IACS with aging at 475 oC for 6 h.
SILICON NANOWIRES FABRICATION BY PHYSICAL METHOD
Authors: Thuy Nguyen Thi
Published: April 2018

Silicon nanowires (Si NWs) were fabricated on Si(111) surfaces by both thermal evaporation and sputtering methods. Au nanocrystals were used as the metal catalysts and they were fabricated by electron beam evaporation. The field emission scanning electron microscopy (FESEM) was used to characterize the Si NWs. The diameters of the Si NWs were measured to be about few tens of nanometer. The mechanism of the nanowires formation by these methods was also discussed.
STUDY THE RESPONSE OF GAS SENSOR USING ZnO NANORODS SYNTHESIZED BY HYDROTHERMAL METHOD
Authors: Han Hoang Van
Published: April 2018

Low-dimensional nano structures ZnO are potential material for optoelectronicand gas-sensing applications. The syntheses of a large quantity of ZnO nanostructures play an important role for practical applications for future. In the paper, we propose hydrothermal reduction method to synthesize large quantities ZnO nanorods under atmospheric pressure and without using any catalysts. As-prepared ZnO nanorods exhibited a hexagonal wurtzite crystal structure. For sensing properties, ZnO nanorods were coated on the Pt interdigitated microelectrodes arrays and examined at operating temperatures of 200 to 350 oC for the detection capacity of NO2 gas. The changes in response resistance revealed that the sensor exhibited a high sensing performance for low concentrations of NO2 gas (0.5 ppm). Additionally, the ZnO nanowires sensors have a good performance to ethanol.
TÍNH TOÁN THIẾT KẾ TỐI ƯU CÁNH MÁY BAY LÀM TỪ VẬT LIỆU COMPOSITE CÓ TÍNH ĐẾN TÍNH DỊ HƯỚNG
Authors: Phong Nguyễn Hồng
Published: April 2018

Nghiên cứu khả năng giảm tải trọng tính toán lên cánh bằng cách sử dụng tính dị hướng của vật liệu composite trong vỏ cánh của thiết bị bay không người lái cánh thẳng dạng “Predator”. Nghiên cứu các phương án tổ hợp hướng sợi khác nhau và tìm ra được tổ hợp hướng sợi tối ưu. Thực hiện tối ưu hóa khối lượng kết cấu với việc áp dụng các tiêu chuẩn phá hủy vật liệu composite và so sánh các tiêu chuẩn.
USING INVERSE METHOD FOR EVALUATING THERMAL CHARACTERISTICS OF A MICRO HIGH SPEED MOTORIZED SPINDLE
Authors: Thao Ngo Thi
Published: April 2018

A combination of finite element and conjugate gradient methods to establish an inverse method for estimating heat sources as well as temperatures of a micro high speed motorized spindle is presented in this article. The proposed method is simple in constructing the direct problem by using COMSOL software. Experiment setup and measurement process are introduced. Results show that inverse solutions agree with experimental data based on temperatures at only one measurement point. Influence of speed on heat sources and temperatures is indicated. Temperature distribution in the spindle is also given and discussed. From these findings, it can be said that the proposed method is appropriated for inversely determining the heat source in micro high speed motorized spindle. The obtained results provide useful information to estimate thermal deformation.
SELECTION OF INDIGENOUS STRAINS (Paecilomyces lilacinus) PARASITIZE Meloidogyne spp. ISOLATED FROM BA RIA – VUNG TAU PROVINCE
Authors: Thuy Duong Nguyen Thi
Published: April 2018

Twenty two Paecilomyces lilacinus strains were isolated from forest soils and black pepper rhizospheres in Ba Ria –Vung Tau Province. The ability to degrade chitin of PB 3.3, PB 2.9, QT2, and QT5 strains was high. The ability to degrade casein of PB 1.3, PB 2.10, KL5, and KL6 strains was efficient. And then, these strains were parasitized females and egg masses of Meloidogyne spp. in vitro. In female parasitism test, the rates of parasitizing female nematodes reached more than 50 % after treating for 2 days. Four strains of PB 2.10, PB 1.3, KL6 and QT5 belonged to the first group achieved the highest parasitic (> 90 %) effects on female after 3 days of incubation. In egg masses parasitism test, three strains of PB 1.3, PB 2.10 and QT5 exhibited 83.33 %, 75 % and 75 % parasitism on egg masses after 11 days of incubation. The rates of parasitizing female were higher than egg masses. Three selected strains from the experiments were PB 1.3, PB 2.10 and QT5.
RADIATION SYNTHESIS OF SILVER NANOPARTICLES/CHITOSAN AGAINST Corynespora cassiicola CAUSING LEAF FALL DISEASE ON RUBBER TREES
Authors: An Nhien Le Thi
Published: April 2018

In this study, silver nanoparticles (AgNPs) were prepared by gamma rays irradiation of 1.0, 2.5, 5.0 and 10 mM silver nitrate solution using chitosan as a stabilizer. UV spectra, morphology and size of AgNPs irradiated at different doses were characterized by using UV-vis spectrophotometer and TEM images. The obtained results indicated that the average size of AgNPs increased by the increase of silver concentration in irradiated solution or the degree of acetylation of chitosan, while the increase of chitosan concentration was found to be a functional key for reducing the average size of particles in AgNPs product. In vitro test, AgNPs inhibited the growth of Corynespora cassiicola. In particularly, the inhibitory efficiency of AgNPs on the growth of C. cassiicola on rubber leaf extract media increased from 52.1 to 100 % when the average particle size of particles in AgNPs product decreased from 15 to 5 nm at the concentration of 50 ppm. In addition, the increase of AgNPs concentration from 10 to 90 ppm also enhanced the antifungal activity to be from 6.3 to 100 %, respectively. It suggests that the silver nanoparticles/chitosan (AgNPs/chitosan) synthesized by γ-rays irradiation method is a very promising fungicidal product applying for treating C. cassiicola, a serious pathogen fungus on rubber trees.
ISOLATING THE MONOKARYON COLLECTION OF Pleurotus spp.
Authors: Ngoc My Tran Thi
Published: April 2018

Pleurotus spp. is one of the most important cultivated mushrooms in the world by their nutrition and medicinal property. In Vietnam, although many Pleurotus species are popularly cultivated, but most of them are imported. These strains are easily degenerated when they are cultivated in large scale, because they are difficult to adapt to the environment of Vietnam. This research aims to construct the monokaryon collection of Pleurotus spp. with details of taxonomy, genetic diversity, cultivating traits, monokaryotic mating types focused on Pleurotus strains with the high yield, genetic stable and adaptability to Vietnam environment. 09 Pleurotus strains were collected in South Vietnam and signed PL1 to PL9. Identification by morphology and phylogenetic analysis based on ITS sequences showed that PL1 is P. citrinopileatus; PL2, PL6 and PL9 are P. ostreatus; PL3 is P. cystidiosus; PL4 and PL8 are P. pulmonarius; PL5 is P. cornucopiae; PL7 is P. incarnatus. AFLP analyses indicated a wide genetic diversity of the collected strains with the similar coefficient 52 – 90 %. Pair of PL2 and PL9 is the most closed genetic distance and pair of PL6 and PL7 is the furthest genetic distance. PL4, PL8 and PL1 adapted well to Vietnam environment. PL2, PL5, PL6 and PL9 are cold strains and formed fruiting bodies slowly. PL3 had the highest biological efficiency, but the longest harvesting period (2.5 – 3 months). Except PL7, the biological efficiencies of other strains are over 50 %. 120 monokaryotic isolates of PL1, PL2 and PL8 are collected and determined the mating type.
BIODIVERSITY OF YEASTS ISOLATED FROM CON DAO ISLAND – BA RIA VUNG TAU
Authors: Luong Dao Thi
Published: April 2018

During the study on yeast diversity from natural samples in Viet Nam, we have collected 38 samples of flowers, fruits, leaves, litter and soils in Con Dao Island and isolated 54 yeast strains. They were identified based on morphology observation and sequences of D1/D2 domain of 26S rDNA. The results showed that they belonged to 13 genera, 28 species, of which 15 strains were suspected as 13 new species. Thirty-nine strains were identified as Ascomycetes belonging 7 genera, 11 species, and the fifteen remaining strains belonged to Basidomycetes, 6 genera and 13 species. The results also showed that four Ascomycetous and nine Basidomycetous isolated were suspected to be new species. The results also showed that Candida was the genus with highest number isolates- 26 strains, and half of these were Candida rugosa. The most diverse species in this study was found in Cryptococcus genus with 7 species from 8 isolates only, and all of them were suspected to be new species. This study also proved that the samples had differences in yeast diversity and species composition among them. Therefore, Con Dao Island is multi potential to discover and publish new yeast species in Vietnam.
IDENTIFICATION OF THE ENTOMOPATHOGENIC FUNGI SAMPLE DL0069 BY COMBINATION OF MORPHOLOGICAL AND MOLECULAR PHYLOGENETIC ANALYSES
Authors: Luyen Vu Tien
Published: April 2018

Species of Simplicillium are biological control agents against certain plant diseases caused by insects and nematodes due to their ability to parasite and kill the host. Recently, this anamorphic genus is classified under Cordycipitaceae as a monophyletic group apart from the type genus Cordyceps. In this current research, we reported the combination of morphological data and molecular phylogenies to identify an entomopathogenic fungal sample (DL0069) found in the mountainous regions of Langbian mountain, Lam Dong Province, Vietnam. Through formation of phialides and conidial chains, DL0069 was most likely a member of Simplicillium genus. From molecular phylogenetic analyses of a portion of the nuclear large ribosomal unit (nrLSU), it was confirmed that DL0069 was most closely related with Simplicillium chinense, a recently found Simplicillium species with a high potency as a biocontrol of nematodes parasiting plants.
THICKNESS DETERMINATION AND CONTROL OF FUNCTIONAL Ni–COMPOSITE ELECTRODEPOSITED COATINGS
Authors: Hung Nguyen Duc
Published: April 2018

Surface electrochemically plated with nickel and highly inert particles provides useful applications: Ni–CeO2 as chemical catalysts, high hardness Ni–CBN (cubic boron nitride) as grinding tools, among others. The plating’s inert particles – 100 mm in size – on nickel surface need to be tightly adherent and evenly dispersed; it is therefore necessary to determine and control the coating layer’s thickness corresponding to the inert particles’ size by parameters like electrical current density and time. With 40–60 nm CeO2 particle size, Ni plating thickness is 12 mm. With 60–100 mm CBN particles, Ni plating thickness is up to 60 mm. Weight and plating thickness were determined by the weight method and Faraday's law. The difference between the two methods showed the presence of inert functional particles on composite coating. EDX method and SEM image also showed the alignment as well as the distribution of particles on the coating surface. Catalytic ability of Ni–CeO2 coating and abrasive properties of Ni–CBN coating were tested by special methods, proving composite plating method useful as catalyst sand grinding metal surface.
RADIATION SYNTHESIS AND CHARACTERIZATION OF CHITOSAN STABILIZED GOLD NANOPARTICLES AND CATALYTIC ACTIVITY STUDY
Authors: D. N. Vo K.
Published: April 2018

In this paper, gold nanoparticles (AuNPs) were synthesized in a single and efficient procedure by e–beam and γ–irradiation using chitosan as a stabilizing agent. The investigations on synthesis of AuNPs under ionizing radiation by studying the influence of initial conditions of the preparation of Au(III)–chitosan solutions prior to irradiation on the nucleation process and on the morphological characteristic of the formed nanoparticles. The results of UV–vis absorption spectroscopy, transmission electron microscopy indicated that spherical well–dispersed gold nanoparticles ranging from 5 to 10 nm were elaborated, depending on the irradiation dose, the dose rate and the [GLA]/[Au(III)] ratio (GLA: glucosamine units). Furthermore, we also reported the application of the synthesized gold nanoparticles as catalyst in the reduction of 4–nitrophenol (4–NP) to 4–aminophenol (4–AP) by excess sodium borohydride.
HYDROTHERMAL SYNTHESIS OF NANO BILAYERED V2O5 AND ELECTROCHEMICAL BEHAVIOR IN NON–AQUEOUS ELECTROLYTES LiPF6 AND NaClO4
Authors: Thanh Nguyen Huynh Le
Published: April 2018

This work aimed to prepare bilayered V2O5 by hydrothermal route from vanadium (III) chloride (VCl3). According to XRD results, bilayered V2O­5 showed a large interlayer spacing around 11.3 Å. The electrochemical properties of bilayered V2O5 were carried out by cyclic voltammetry and charge–discharge testing in non–aqueous electrolytes LiPF6 and NaClO4. The curves charge–discharge showed that mechanism of insertion/extraction of Li+ ions and Na+ ions were occurred on a solution solid without the phase transition. Moreover, specific capacity for lithium and sodium intercalation of bilayered V2O5 were found out 250 mAh/g and 200 mAh/g, respectively. The kinetic of lithium’s and sodium’s insertion was evaluated by the electrochemical impedance spectroscopy (EIS). The EIS results exhibited a stabilization of charge transfer in both case and a slow kinetic of sodium’s diffusion compared to lithium’s case due to the large ionic radius of sodium.