bluuebunny/crossref_metadata_2025 huggingface dataset:
INHIBITION OF BACTERIA ISOLATED FROM NINH THUAN GRAPES BY ORGANIC ACIDS
Authors: Hanh Nguyen Thi
Published: April 2018

Ninh Thuan grapes are famous specialty of Vietnam. After harvesting, they are very susceptible to damage if not preserved in time. This study aimed to find the minimal inhibitory concentration and minimal bactericidal concentrations of organic acids, such as lactic acid, citric acid, and ascorbic acid towards seven bacteria previously isolated from Ninh thuan grapes (Empedobacter  brevis, Citrobacter sp. Enterobacterium ludwigii, Bacillus cereus, Flavobacterium sp., Pseudomonas oryzihabitans and Bacillus thuringiensis) in order to apply in pretreatment of grapes prior to storage. The Minimal Inhibitory Concentration (MIC) was determined by the binary dilution method. 0.1 ml of each dilution of test acids with initial concentration of 3 % was mixed with 0.1 ml of bacteria (c.a. 5.105 CFU/ml), in 96-culturing-well plate. Innoculated plate was incubated for 24 hours at temperature of 37 °C. Optical density was measured at 620 nm wavelength by a Microplate reader device. For Minimal Bactericidal Concentration (MBC) determination, 0.1 ml of bacteria (c.a.5.105 CFU/ml) was mixed with 0.4 ml liquid medium of Tryptone Glucose Agar (TGA) and of 0.5 ml acid at above concentrations, culturing within 24 hours at temperature of 37 °C. After 24 hours, they were dropped onto TGA agar plates, and cultured for 24 hours at 37 °C. The results showed that, the MIC and MBC of citric acid toward Empedobacter brevis were 0.12 mg/ml and 0.12 mg/ml; Citrobacter sp. were 0.9 mg/ml and 3.8 mg/ml; Enterobacterium ludwigii were 0.45 mg/ml and 1.9 mg/ml; Bacillus cereus were  0.9 mg/ml and 0.9 mg/ml; Flavobacterium sp. were 0.12 mg/ml  and 0.45 mg/ml; Pseudomonas oryzihabitans were 0.12 mg/ml and 0.45 mg/ml and Bacillus thuringiensis were 0.12 mg/ml  and 0.9 mg/ml, respectively. Similarly, MIC and MBC of  lactic acid toward: Empedobacter brevis were 0.12 mg/ml and 0.23 mg/ml;Citrobacter sp. were 0.9 mg/ml and 1.9 mg/ml; Enterobacterium ludwigii were 0.45 mg/ml and 0.9 mg/ml; Bacillus cereus were 0.23 mg/ml and 0.45 mg/ml; Flavobacterium sp. were 0.12 mg/ml and 1.9 mg/ml;  Pseudomonas oryzihabitans  were 0.23 mg/ml and 1.9 mg/ml and Bacillus thuringiensis were 0.12 mg/ml and 1.9 mg/ml, respectively. Ascorbic acid was found to be inefficient for use as antimicrobial agent against isolated bacteria. The above results suggested that citric and lactic acids could be used at maximal concentrations of 3.8 mg/ml and 1.9 mg/ml, respectively to suppress bacteria from grapes. This finding would contribute to develop method for pretreatment of grapes in fresh grape preservation techniques.
COVALENT CONJUGATION OF ANTIBODY AND GOLD NANOPARTICLE FOR DEVELOPMENT OF LATERAL FLOW IMMUNOASSAY TEST STRIP
Authors: Phong Truong Quoc
Published: April 2018

Nanotechnology is one of the fastest growing technologies in this era. Gold nanoparticle (AuNP) based immunoassays have been performed on the basis of antigen-antibody interaction using AuNP antibody conjugates. Lateral flow immunoassays(LFA) which are also based on AuNP antibody conjugates are useful innovation in nanotechnology and widely applied in medicine and research fields. However, there are some limitations of the present LFA kits such as sensitivity and stability. In the study, we showed the result of covalent conjugation of anti-rotavirus antibody and AuNP for generating a lateral flow immunoassay strip to detect rotavirus in fecal samples. The suitable conditions for coating polyethylene glycol (PEG) on the surface of AuNP were 10.0 mM PEG for 3 hours at room temperature (25 oC). Optimized conditions for covalent conjugation of antibody and AuNP were pH 4.0, 0.1 mg antibody/conjugate, 0.01 mM reactant EDC/NHS [1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/(N-hydroxy sulfosuccinimide]. The coupling reaction was carried out at room temperature for 90 min. The conjugate pad, antibody immobilized nitrocellulose membrane strip were created with investigated conditions for generating an LFA test strip. The limit of detection of LFA test strip was determined by 1.6 × 105 virus particles/ml, three times lower than that of Rotaclone kit (UK). The generated strip could be used to detect rotavirus in fecal sample of patient.
A NEW SYNTHESIS PROCESS OF LIGNOSULFONATE USING LIGNIN RECOVERED FROM BLACK LIQUOR OF PULP AND PAPER MILLS
Authors: Giang Nguyen Truong
Published: April 2018

Lignosulfonate is an important deriver of lignin, which has many advantages as a surfactant in various fields, for example, in petroleum, printing, construction and agricultural industries. In this study, a new synthesis process of lignosulfonate by two steps were investigated. The results showed that lignosulfonates synthesized by two steps process have similar characteristics and functional groups with lignosulfonates synthesized by one step process. Process by two steps can be easier operated than that by one step, also reaction time and reaction temperature in two steps process were shorter and lower than in one step process.
ENHANCED EFFICIENCY OF TREATMENT OF TNT WASTEWATER BY INTERNAL ELECTROLYSIS REACTION USE BIMETALIC MATERIALS Fe-Cu
Authors: Nhan Vu Duy
Published: April 2018

In this article, wastewater containing 2,4,6 trinitrotoluen (TNT) was treated by internal microelectrolysis with bimetal Fe-Cu materials. Components of TNT pollutant content was identified by HPLC method. Examined factors: pH, time, temperature, concentration of Fe-Cu bimetal to efficient treatment of TNT in the wastewater. With conditions at pH 5, bimetal Fe-Cu dosage of 50 g for l litre of wastewater, TNT original content in the wastewater infected about 95-106.4 mg/l, temperature of 25 0C, after 6 hours of processing time, content TNT rest 0.2 - 0.5 mg/l, after 6 hours not observed.
SURFACE MODIFICATION OF ACTIVATED CARBON FROM RICE HUSK FOR ENHANCING THE NICKEL(Ni2+) AND CADMIUM (Cd2+) ADSORPTION CAPACITY
Authors: Ma Hoa Thai
Published: April 2018

Activated carbon (AC) has been proven to be an effective adsorbent for the removal of a variety of pollutants. AC is extensively used for adsorption because its high surface area is well-developed internal micro porosity. The objective of this study is to determine the optimal condition of the surface modification process of activated carbon from rice husk (ACRH) using HNO3. That increase the functional group, and improve affinity towards certain contaminants of ACRH for increasing the adsorption capacity of Ni2+ and Cd2+. Two factors were taken into account as: the concentration of HNO3 (1, 3, and 5 M), reaction time (1, 2, 3, 4 and 5 hours). The results showed that the optimal condition of the surface modification process was derived at the equilibrium concentration of HNO3 = 3 M and the equilibrium reaction time = 4 hour. Interestingly, in comparison with the control sample (ACRH not modified), the adsorption capacity of Ni2+ and Cd2+ increased from 10.0 to 17.2 mg/g and 10.4 to 29.6 mg/g, respectively. This adsorption capacity of modified ACRH shows the increase significantly.
COMBINATION OF METHANE OXIDATION AND DENITRIFICATION PROCESS IN A TWO-STAGE BIOREACTOR
Authors: Thu Vu Phuong
Published: April 2018

The importance of a combination of methane oxidation and denitrification processes in a two-stage bioreactor was investigated for the removal of nitrate using methane gas. In the configuration I, methane and oxygen were supplied separately to two columns of the two-stage bioreactor, an oxic column and an anoxic column. The nitrate removal efficiency was around            25 % and nitrite presented in the liquid medium, showing that the denitrification process was not complete.  In the configuration II, methane and oxygen were supplied together to one column of the two-stage bioreactor, better results were achieved. Nitrate removal efficiency increased to almost 100 %, no nitrite was found in the liquid medium. The methane oxidation and the denitrification processes seemed to be happened simultaneously in one column of the two-stage bioreactor and demonstrated its advantages. Methane utilized concentration in the medium of the methane oxidation column increased from 1 to 2.1 mg/L, which resulted in more soluble organic carbon was created and supplied for denitrifiers. The C/N utilized ratio was lower in the Configuration II showing that the aerobic methane oxidation coupled to denitrification (AMO-D) achieved higher efficiency when methane and oxygen were supplied together.
SYNTHESIS AND PHOTOCATALYTIC ACTIVITIES OF CuO-TiO2 NANOCOMPOSITES
Authors: Le Thi Ngoc Tu
Published: April 2018

TiO2 nanotubes were prepared by hydrothermal method and then modified by CuO by two different methods: adsorption – calcination (A-C) method and photo-reduction method. The obtained solid product (CuO-TNTs) was investigated of: morphology, crystal structure and absorbance spectroscopy by transmission electron microscopy (SEM), X-ray diffractometry (XRD), UV-vis spectroscopy; respectively. The photocatalytic ability of CuO-TNTs was determined by absorbance spectroscopy of methylene blue (MB) solution under various irradiation conditions. Results showed that the photocatalytic activity of CuO-TNTs is lower than that of the original TNTs in UV irradiation. In contrast, it shows the better performance in visible light and sunlight than that of the TNTs.
UTILIZATION OF ANALYTICAL TECHNIQUE FOR EVALUATION OF 13CDIC IN GROUNDWATER USING EA-IRMS UNDER THE CONDITION OF VIETNAMESE LAB
Authors: Hong Nguyen Trinh Thi
Published: April 2018

As the demand of extraction and consumption of groundwater increases, its quality has been facing the issue of water contamination caused by industrial as well as domestic activities. Isotopic ratio analysis is a modern and effective technique widely used to trace the source of groundwater contamination. In this study, an analytical technique for carbon stable isotopic ratio of dissolved inorganic carbon in groundwater using elemental analyzer - isotopic ratio mass spectrometer was utilized under the condition in Vietnamese lab. As a result, correlation and calibration equations were established in which good reproducibility of the international standards was achieved with the value of first standard deviation less than 0.3 ‰ as well as the accuracy and precision of the measurements were obtained with errors less than 0.12 ‰. Based on these equations, 15 samples of groundwater collected from Cu Chi (Viet Nam) district were analyzed and calculated.
EVALUATION OF THE IMPACT OF DYKE ON THE PRACTICE OF USING PLANT PROTECTION CHEMICALS AND THE ENVIRONMENT IMPACT QUOTATION INDEX OF RICE CULTIVATION AREAS IN THAP MUOI, DONG THAP PROVINCE
Authors: Van Ha Nguyen Thi
Published: April 2018

This report presents the result of a survey to evaluate the use of crop protection chemicals (pesticides – HCBVTV) in rice-growing areas with dyke, semi-dyke and no embankment based on interview result with 112 interviewers such as farmers, agricultural specialists, and pesticide dealers in Thap Muoi District, Dong Thap Province and pesticide usage data recorded by three selected framers in 3 different dyke systems. It showed that dyke practice affects the use of pesticides of farmers. After  dykes constructed, the pesticides used were more diverse, with higher dosage compared to before having embankments. The report also evaluates the risk of using pesticides through Environmental Impact Quotient (EIQ) index. It showed that areas with dyke and semi-dyke have much higher EIQ index than areas without embankment, 167, 145 and 54, respectively.
REMOVAL OF TOTAL PHOSPHORUS FROM MUNICIPAL WASTEWATER USING CYLINDRICAL ALUMINUM ELECTRODE IN CONTINUOUS MODE
Authors: Viet Tran Tuan
Published: April 2018

This study aimed to apply electro-coagulation method using cylindrical Aluminum electrode in continuous mode to remove total phosphorus (T-P) in municipal wastewater. The effects of NaCl concentration (or conductivity) and hydraulic retention time (HRT, or flow rate) on T-P removal efficiency were investigated. To determine the efficiency of this system the ratio Al consumption/T-P removal was also considered. The results showed that, with raw sewage as influent, HRT = 1.17 min and added NaCl = 0.04 % was found the best conditions for the highest T-P removal efficiency (92.80 %; T-P concentration remainder was 0.17 mg/L) and the ratio Al consumption/T-P removal was 5.0. In general, this method achieves a high efficiency of removing phosphorus from wastewater and it can be used in sewage treatment systems.
OPTIMIZATION OF THE AQUEOUS EXTRACT PROCESS FROM MANGOSTEEN PEEL FOR DYEING SILK
Authors: Pham Thi Hong Phuong
Published: April 2018

This research studied the juice extraction process from mangosteen peel with water solvent and the paramesters influencing on extraction process such as extraction temperature, extraction time and extraction ratio, and evaluating the juice of extract by determining extraction efficiency, color saturation of fabric and color fastness of silk fabric. The research results showed that the juice extracted from mangosteen peel can be used to dye silk fabric with high color strength and fastness. And the results of research will bring the efficiency of environmental, economy and society; and will meet urgent demands today.
OPTIMIZING THE PROCESS OF TRANSFORMING COFFEE HUSKS INTO BIOCHAR BY MEANS OF HYDROTHERMAL CARBONIZATION
Authors: Hien Tran Thi
Published: April 2018

The conditions of the hydrothermal carbonization process to produce biochar from coffee husk will be optimized for maximum yield. Besides, response surface methodology (RSM) and central composite face-centered (CCF) method will be used in designing experiments. Also, the optimal value of factors such as temperature, time and biomass: water ratio which can provide a maximum yield of biochar will be worked out using Modde 5.0. As a result, the optimal conditions for maximum yield of biochar was obtained as temperature of 180 oC, 3.5 h and biomass: water ratio of 15 %. It can also be concluded that temperature has greater impact on the transformation of biochar than time and biomass: water ratio.
ANTIBIOTICS AND PESTICIDES IN WATER AND SEDIMENTS FROM INTENSIVE SHRIMP FARMS IN SOUTHERN VIETNAM
Authors: An Nguyen Truong
Published: April 2018

In recent years, shrimp farming has developed rapidly and become one of the major export sectors of Vietnam. In particular, Mekong Delta Vietnam (MDVN) accounts for over 90 % shrimp farming area in Vietnam. Shrimp industry development leads to use a large amount of antibiotics (ABs) and pesticides for disease prevention, treatment and sanitation pond. These compounds are usually discharged directly into the environment through water and sludge after harvesting. The presence of antibiotics and pesticides in the environment cause negative impacts on ecosystems and human health. In this study, the passive sampling method with POCIS sampler (Polar Organic Chemical Integrative Samplers) was used to monitor the presence of 12 ABs and 2 pesticides in water of intensive shrimp ponds and the surrounding canals at Tan Tru District (Long An province) and Can Gio District (Ho Chi Minh city) following a production cycle. The results showed that ABs and pesticides were detected in water and sediment in the pond and canals in both research sites. Two pesticides (atrazine and diuron) were detected in the pond and leading canals in both study areas with low concentrations from several ng/L to several tens of ng/L. In Tan Tru, three antibiotics (Trimethoprim, Sulfamethoxazole and Enrofloxacin) were detected in water at concentrations ranging from several tens of ng/L to 300 ng/L; in sediments of shrimp pond and canal the levels of pesticides and ABs ranged from 10 to 200 µg/kg. In Can Gio - HCMC, 4 ABs (Trimethoprim, Sulfamethoxazole, Ciprofloxacin and Enrofloxacin) were detected ranging from a few ng/L to several µg/L in water, and a few mg/kg in sediments of the pond. The results also showed that in the pond, ABs type and concentration detection varied by region and shrimp growth cycles.
POSSIBILITY AND CONSTRAINT PARAMETERS FOR AUTOMATED GENERALIZATION OF MULTI – SCALE BASE MAPS
Authors: Hong Hanh Nguyen Thi
Published: April 2018

Map generalization plays an important role in map-making process. Map generalization depends on many factors such as purpose, geographic scope, thematic, map scale… and therefore it remains one of the challenging issues in Cartography. This paper discusses the constraint parameters and process of cartographic generalization from map data at 1:2000 to map data at smaller scale such as 1:5.000, 1:10.000, 1:25.000, 1:50.000 and 1:100.000. These constraint parameters are indentified by applying cartographic principles and using experimental procedures with generalization toolset in ArcGIS 10. Defined constraint parameters are then put in cartographic generalization for base maps of Ho Chi Minh City in order to verify their rationalities.Research result shows that, using right parameters and GIS cartographic generalization tools could provide good way to generalize and create base map products fast, efficient and reasonable. It also provides useful information for further research in automated map generalization and in creating multi-scale, multi-purpose map database.
CALCULATION OF ENVIRONMENTAL PROPERTIES FOR ORGANIC COMPOUNDS USING QUANTITATIVE STRUCTURE-SOLUBILITY RELATIONSHIPS
Authors: Cong Vo Thanh
Published: April 2018

The solubility of organic compounds in water was related to the environmental behaviors. In this work, the solubility values of 27 organic compounds were calculated by using the different molecular descriptors. The quantitative structure-solubility relationships (QSSRs) were constructed by incorporating the multivariable technique and the genetic algorithm. The important molecular descriptors such as logP, SsCH3_acnt, ABSQ, nelem, nrings, SHBa, Gmax, Gmin, Xvp6, and Xvpc4 were selected to construct the linear models QSSRs with the genetic algorithm. The best four-variable linear model QSSR was obtained from those descriptors. The quality of QSSR linear model indicated in statistical values R2training of 96.60, standard error of estimation, SE of 0.2961, F-statistic of 156.0, P-value of 0.0, R2test of 95.02, and RSS value of 2.823. The architecture of neural network I(4)-HL(4)-O(1) with R2training of 99.03 was constructed by the molecular descriptors in the four-variable linear model. The predicted solubility values of organic substances in test group resulting from these models are in good agreement with those from literature.
THERMO-PRETREATMENT ON BAMBOO BIOMASS WITH AMMONIA
Authors: Ngan Dai Hue
Published: April 2018

Hydrogen is rising as one of potential fuel types to instead of petroleum and fossil energy in the future because of its high energy density and non-carbon exhaust. There are many processes for hydrogen production, but fermentative hydrogen production (FHP) from lignocellulosic biomass as rich-carbohydrate feedstocks is considered to be the one of the most effective methods. However, the yield of fermentable sugar could be strongly impacted by pretreatment of lignocellulosic materials.Thus, this work studied the effects of thermal-ammonia pretreatment method on bamboo powder at 125 oC, during in 30-90 minutes. The results showed that the maximum recovery of carbohydrate in solid were 554.21 mg/(1g bamboo powder), and the sugar conversion yield and sugar content in final solution were 9.07 % and 8.31 g/L, respectively. 94.2 % of lignin content in bamboo biomass could be removed. The maximum hydrogen accumulation reached 5.7 % of the gaseous mixtures after 48 h of fermentation. This study showed that hydrothermal technique could be an efficient way in order to disrupt the lignin structure of the biomass and increase the accessibility of other treatment agents to cellulose and hemicellulose.
RELATIONSHIP BETWEEN FLUORIDE CONTENTS IN GROUNDWATER AND PREVALENCE OF FLUOROSIS IN TAY SON DISTRICT, BINH DINH PROVINCE, VIETNAM
Authors: Nguyet Phan Nhu
Published: April 2018

The communities within Binh Dinh province in the Central Vietnam are reliant on groundwater as their primary supply of domestic and potable water. Meanwhile, it is seriously contaminated with fluoride that causing fluorosis problem for people. This study aims to investigate the link between severity of dental fluorosis rate in a population and fluoride concentration in drinking water in Tay Son area. A total of 50 well-water samples were collected and 220 people were surveyed by questionnaire from 50 households at 3 villages: Tay Phu, Binh Tuong, Tay Giang of Tay Son district, Binh Dinh province, Vietnam. The quantitative assessment of severity of dental fluorosis was done by calculating the Community Fluorosis Index (CFI) using Dean’s classification. Result of this study showed that fluoride concentration in well-water varied from 0.31 mg/L to 7.69 mg/L (mean 2.66 mg/L, SD: 2.18 mg/L) with 70 % of well-water samples above the maximum permissible limit of 1.5 mg/L of World Health Organization (WHO) drinking water standard. 100 % people surveyed was suffered from dental fluorosis and Dean scale of dental fluorosis ranged from level 2 to level 5. CFI varied from 3.45 to 4.13 above limit value (0.6). The community seriously suffered from dental fluorosis. The fluoride concentrations and Dean Index have high correlation (r = 0.580, p < 0.0001). Based upon results of this study, it is recommended that the government should supply drinking water with appropriate fluoride content for this community.
TREATMENT EFFECTIVENESS EVALUATION OF WASTEWATER FROM INDUSTRIAL FRIED CHICKEN RE- PROCESSING PROCESSES BY ADVANCED OXIDATION PROCESSES
Authors: Chau Nguyen Dien
Published: April 2018

The experiment was conducted by using ozone and graphite electrodes to treat wastewater from industrial fried chicken re-processing peocesses with COD value ranges of 1600 - 2000 mgO2/L. A chamber of 20 liters was used in this study. The chamber height was 1 meter (the high response of 50-60 cm) in order to increase the diffusion of ozone into the wastewater. The study results showed that the amount of ozone needed for the reaction is 300 mg/h with COD removal efficiency of 40 % during reaction time of 45-60 minutes.The rate of BOD/COD increased within 1.55 - 1.80 times as compared with the BOD/COD rate of the initial wastewater. The experiments also showed that the COD removal efficiency of wastewater was not affected much by the pH value of the wastewater.
Contents
Authors: Contents Contents
Published: April 2018

36 bài báo
A STUDY FOR SYNTHESIS OF DICALCIUM PHOSPHATE FROM VARIOUS GRADES OF PHOSPHATIC MATERIALS
Authors: Huy Bui Quoc
Published: April 2018

Anhydrous dicalcium phosphate with monetite structure plays a significant biological importance for the mineralization of bones and teeth. This compound can reconstruct the hard tissues due to its high solubility in the body than other calcium phosphate compounds. Di calcium phosphate is being used as a food - additive supplying calcium and phosphate for humans and animals. Due to the high effective P2O5 content, this compound is also used efficiently as a slowly soluble fertilizer in agriculture for all soil and crop types. This paper presents results of synthesis of di calcium phosphate monetite from Ca(OH)2 and phosphoric acid and di calcium phosphate brushite  from the resulting solution after enriching of type II - Lao Cai apatite ore by phosphoric acid. The samples were examined by volumetric titration methods, XRD, SEM and EDS.
CÔNG NGHỆ HÀN ĐẮP PHỤC HỒI KÍCH THƯỚC TRỤC THÉP C45 BẰNG HÀN LĂN TỰ ĐỘNG VỚI DÂY THÉP HỢP KIM
Authors: Tân Nguyễn Minh
Published: April 2018

Bài báo giới thiệu công nghệ hàn phục hồi chi tiết trục C45 có đường kính Ø ≤ 100 bằng phương pháp hàn lăn tự động với dây thép hợp kim. Với công nghệ này cho năng suất cao vì quá trình hàn sử dụng dòng điện hàn có cường độ rất lớn, thời gian tác dụng ngắn, tốc độ hàn ổn định nhờ thiết bị dễ được cơ khí hóa và tự động hóa nên chi tiết hàn ít bị biến dạng. Chất lượng mối hàn tốt, mối hàn không có xỉ, quá trình hàn không cần đến thuốc hàn hay khí bảo vệ. Bằng công nghệ hàn đắp phục hồi này có thể làm cho độ cứng và tính chống mài mòn của lớp bề mặt các chi tiết máy làm từ thép C45 tăng lên khoảng 1,5 lần (đạt được độ cứng từ 50 đến 55 HRC).
ĐIỀU CHẾ TiO2 TỪ QUẶNG ILMENIT BÌNH ĐỊNH BẰNG TÁC NHÂN PHÂN GIẢI QUẶNG KOH NHẰM ỨNG DỤNG XÚC TÁC PHÂN HỦY CÁC CHẤT HỮU CƠ Ô NHIỄM
Authors: Diệu Cẩm Nguyễn Thị
Published: April 2018

Titan đioxit được điều chế từ quặng ilmenit Bình Định bằng phương pháp kiềm hóa với tác nhân phân hủy quặng là dung dịch KOH. Vật liệu titan đioxit được điều chế trong điều kiện: nồng độ KOH phân hủy quặng 80 %,nồng độ H2SO4 dùng để phản ứng với chất rắn thu được ở dạng bột nhão là 4 M, tỉ lệ giữa khối lượng quặng ilmenit và thể tích axit H2SO4 là 1 : 9 và nhiệt độ nung kết tủa TiO(OH)2 là 600 oC. Vật liệu TiO2 thu được tồn tại cả hai pha anatas và rutil nhưng pha anatas chiếm ưu thế hơn với cường độ pic mạnh và sắc nét, kích thước hạt trung bình khoảng 25 nm và diện tích bề mặt riêng là 47,8 m2/g. Kết quả khảo sát sự phân hủy xanh metylen trên xúc tác TiO2 cho thấy, hoạt tính quang xúc tác của TiO2 được điều chế từ quặng ilmenit Bình Định với nguồn sáng kích thích bức xạ UV là khá tốt.
DISSIMILAR JOINING A6061 ALUMINUM ALLOY AND SUS304 STAINLESS STEEL BY THE TUNGSTEN INERT GAS WELDING PROCESS
Authors: Manh Nguyen Quoc
Published: April 2018

Welding dissimilar materials has been widely applied in industries. Some of them are considered this as a strategy to develop their future technology products. Aluminum alloy and stainless steel have differences in physical, thermal, mechanical and metallurgic properties. However, selecting a suitable welding process and welding rods can solve this problem. This research aimed to investigate the T-joint welding between A6061 aluminum alloy and SUS304 stainless steel using new welding rods, Aluma-Steel by the Tungsten Inert Gas (TIG) welding process. The mechanical properties, the characteristics of microstructure, and component analysis of the welds have been investigated by the mechanical testing, microhardness testing, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). As a result, the fracture occurred at the adjacent area between welding seam and A6061 aluminum alloy plate. The average microhardness between welding seam and SUS304 stainless steel is 279.72 HV, welding seam and A6061 aluminum alloy of 274.50 HV. A large amount of copper elements found in the welds due to using the new welding rod, Aluma-Steel rod.
EFFECT OF ELECTRIC CURRENT PULSE ON MECHANICAL PROPERTIES OF ULTRA-HIGH STRENGTH STEEL 1180CP
Authors: Thien Nguyen Trung
Published: April 2018

Effect of the pulse electric current on mechanical properties of an ultra-high strength steel (UHSS) is experimentally investigated. A single pulse of electric current with a short duration of 0.36 sec is applied to the specimen under tensile plastic loading. The experimental result showed that flow stress of the UHSS nearly instantly drops at moment of electric current, following strain hardening until necking of the specimen. Uniform elongation completely depends on the pulsing strain, while ultimate tensile strength slightly changes after electric current.
EFFECT OF SYNTHESIZING PARAMETERS ON MORPHOLOGY AND DIAMETER OF CARBON NANOTUBES GROWN BY THERMAL CVD METHOD
Authors: Tu Nguyen Cong
Published: April 2018

Carbon nanotubes were synthesized by thermal chemical vapor deposition method. There were parameters of the synthesizing process which influence the morphology and quality of nanotubes such as substrate material, the topology of substrates, the reduction process, and growing temperature. The topology of substrate affected the uniform of nanotubes. The reduction process using NH3 reductant helped reducing diameter of carbon nanotubes. Growing temperature complexly modified the quality of carbon nanotubes.
FABRICATION OF BIODEGRADABLE POLYESTER MICROSPHERES BY ELECTROSPRAYING METHODS FOR DRUG CARRIER APPLICATION
Authors: Viet Linh Nguyen Vu
Published: April 2018

This research investigated the effects of polymer concentration, molecular weight polymer and type of polymer on the morphology of electrosprayed microparticles by Scanning Electron Microscopy. Electrospraying process has been studied to produce nano- and micro- particles for drug carrier application because of high loading capacity and high encapsulation efficiency. Controlling morphology and structure of electrosprayed particles can decide the release of drug from these particles. Particles were hollow and wrinkled semi-spheres as using low polymer concentration while wrinkled spheres as using higher polymer concentration. The electrosprayed particles obtained spherical morphology when the polymer concentration is high enough to generate significant chain entanglements. The results also indicated that high molecular weight polymer could produce spherical microspheres, even with low polymer concentration. The electrospraying process fabricated the microspheres from biodegradable PLA and PCL for drug carrier application.
NEW INSIGHTS ON THE MECHANISM OF SEMICONDUCTOR NANOSTRUCTURES FORMED DURING VAPOR TRANSPORT AT ATMOSPHERIC PRESSURE
Authors: Trung Tran
Published: April 2018

Co-deposition of two types of high aspect ratio nanostructured ZnO involving nanowires and nanotetrapods with a uniform structure were carried out through thermal evaporation and vapor transportation of a mixture of highly pure ZnO and graphite powders in 1:1 weight ratio. The mixture was heated at 1100 oC under various flow rates of N2 and air mixture. The surface morphology and structural characteristics of synthesized ZnO nanostructured materials revealed a highly crystalline structure with an average diameter of about 30 nm and length of several micrometers. The mechanism of co-deposition of ZnO nanowires and nanotetrapods during vapor transport at atmospheric pressure was proposed.
NGHIÊN CỨU ĐỘ BỀN ĐIỆN HÓA CỦA ĐIỆN CỰC ANOT BIẾN TÍNH BẰNG CÁC OXIT KIM LOẠI TRÊN NỀN TITAN
Authors: Thu Hiền Chu Thị
Published: April 2018

Bài viết này trình bày các kết quả của nghiên cứu  tính chất điện hóa và độ bền của điện cực Ti/PbO2 được phủ bởi hỗn hợp oxit kim loại SnO2 và Sb2O3. Các phương pháp phân cực liên tục và phương pháp quét theo chu kì đã được sử dụng trong nghiên cứu. Các kết quả nghiên cứu cho thấy các điện cực Ti/Sb2O3-SnO2/PbO2 có tuổi thọ dài nhất khoảng 290 giờ với lớp phủ SnO2-Sb2O3 được hình thành ở nhiệt độ nung của dung dịch muối là 480 oC. Điện cực Ti/Sb2O3-SnO2/PbO2 khả năng điện hóa tốt hơn các điện cực Ti/PbO2.
TỐI ƯU HÓA CÁC CHỈ TIÊU CƠ TÍNH KHI CƠ NHIỆT LUYỆN NHIỆT ĐỘ CAO HỢP KIM NHÔM AlMgSi BẰNG PHƯƠNG PHÁP HÀM NGUYỆN VỌNG HARRINGTON
Authors: Thông Nguyễn Khắc
Published: April 2018

Bài báo đề cập đến tối ưu hóa các chỉ tiêu cơ tính khi cơ nhiệt luyện nhiệt độ cao hợp kim nhôm AlMgSi. Trên cơ sở đó tác giả đã sử dụng phương pháp hàm nguyện vọng Harrington để xác định tối ưu các chỉ tiêu cơ tính về độ bền, độ dẻo của họp kim AlMgSi khi cơ nhiệt luyện nhiệt độ cao. Kết quả xác định được chế độ tối ưu cơ nhiệt luyện nhiệt độ cao hợp kim AlMgSi là: nhiệt độ hoá già 174 0C; nhiệt độ biến dạng 413 0C; độ biến dạng 75 %; thời gian hoá già 6,76 giờ.
REVIEW ARTICLE: HYBRID MATERIALS BASED ON CARBON NANOTUBES
Authors: Tu Nguyen Cong
Published: April 2018

Carbon nanotubes-based hybrid and composite materials, recently, are a hot topic in research about advanced materials. Nanotubes are functionalized and hybridized with both organic and inorganic compounds for designed applications. Hybrid materials can be fabricated by direct or in-direct method. Some investigations about electrical, optical and photocatalytic properties of hybrid materials would be discussed.
STRUCTURE OF SPAN-80 ACTIVATED DOUBLE PEROVSKITE SYSTEM La2Co1-xFexMnO6 (x = 0.00, 0.01, 0.02, 0.03)
Authors: Tan Pham The
Published: April 2018

We report the structure and the magnetic behaviors of the Fe-doped La2Co1-xFexMnO6 family of compounds at low doping concentrations x ≤ 3 %. The substitution of Fe into the Co site induced the increase in ferromagnetism at the cost of TC. The small doping of Fe in          La2Co1-xFexMnO6 (£ 3 %) led to the slight changes in the lattice constants but the symmetry of the lattice remained unchanged (Pnma). The doping also reduced TC for both transitions at around 215 K and 130 K which attribute for the different spin orderings of the magnetic ions.
EFFECTS OF GUIDING CHAMBER ON WELDING PRESSURE IN HOLLOW EXTRUSION DIE DESIGN OF AA7075
Authors: Tuan Do Anh
Published: April 2018

Porthole die extrusion has a great advantage in the forming of hollow section of aluminum alloy tube. This paper aims at the development of an extruding seam square tube of AA7075 high strength aluminum alloy. In order to increase the welding pressure of the hollow AA7075 tube in extrusion process, a special die feature has been created. Several different proportions of chamber structure in outlet of extrusion die have been designed. The finite element analysis software DEFORM 3D to analyze various design parameters on the load – displacement and the welding pressure have been studied. In this study, a different high proportion in material guiding chamber has been defined. The results showed that if a suitable material guiding chamber has been built then welding pressure can be increased rapidly. When the ratio of chamber height and length is 2:1 the increased welding pressure is the best.
Rhodosporidium sp. GROWTH IN MOLASSES MEDIUM AND EXTRACTION OF ITS ASTAXANTHIN BY USING HCl
Authors: Vinh Tran Quang
Published: April 2018

Astaxanthin is classified as a xanthophyll-carotenoid, which is red-orange colour and powerful antioxidant activity. In this study, astaxanthin was collected from Rhodosporidum sp. by pilot culture (10 liters). Molasses medium was investigated with urea ((NH4)2CO), magnesium sulfate heptahydrate (MgSO4.7H2O) and potassium dihydrogen phosphate (KH2PO4) at different concentrations. Astaxanthin was extracted by using chlorhydric acid (HCl) method.The highest dried yeast biomass was 8.3682 g/l culture supernatant and astaxathin was 1.932 g/l culture supernatant by molasses medium containing 20 g/l sugar, 0.5 g/l ((NH4)2CO, 3 g/l MgSO4.7H2O and 10 % (v/v) inoculum. HCl extraction method was mixed 10 mg biomass: 1 ml HCl 0.6 N and incubated at 70 oC, 150 minutes.
DISCOVERY OF ENTOMOPATHOGENIC FUNGI Cordyceps takaomontana AT LANGBIAN MOUNTAIN, LAM DONG, VIET NAM
Authors: Hiep Dinh Minh
Published: April 2018

The stromata of Cordyceps sp. were found on the Langbian Mountain – Da Lat, Vietnam at the height of 1.650 meter above sea level, on the larva of Lepidoptera. Stromata were lemon-yellow, clavate to elongated clavate, arising from a white pseudosclerotium. The fertile head was on the top part of stromata, darker coloured in comparison to the stipe. Perithecium was narrowly ovoid, superficial and forming dark yellow punctate on the surface of stromata. Ascus cylindrical with semi- spherical cap. Ascospores were cylindric, truncated and separately after discharge from the ascus.Pure culture was isolated on Potato Glucose Agar (PGA) medium: white colony in young and yellow in old. The isolated mycelium was not homogenous in thickness and in growth rate at the peripheral area. Conidiophores were phialide, tapering to both apexes. Conidia had elliptical shape and form into chains after maturation.DNA was isolated, then purified from pure mycelium and used to amplifying the nrLSU (nuclear ribosomal large subunit) sequence. The amplified products were used for sequencing, proof-reading by some professional solfwares before combining with other nrLSU sequences. Then this database was used to search for the suitable evolution model as well as to construct the phylogenetic trees.The results of phylogenetic analysis completely supported the morphological classification: DL0038A and  DL0038B were Cordyceps takaomontana.
LEAF LITTER FUNGI ISOLATED IN BACH MA NATIONAL PARK, VIET NAM
Authors: Hoang Yen Le Thi
Published: April 2018

A survey of fungi from leaf litter at Bach Ma National Park in Viet Nam was initiated.  Using surface disinfection and moist chamber with single spore isolation methods, 102 isolates were obtained and of those, 70 isolates were selected for further morphological study. They belong to 5 classes, 9 orders, 14 families, 33 genera, and 51 species. Among them, Ceratosporella deviata, Lateriramulosa sp., Isthmolongispora ampuliformis, Polylobatispora quinquecornuta, Scolecobasidium tricladiatum, Triglyphiuma labamense, Tricladiella pulvialis, Tripospermum myrti, Triscelophorus sp., Varicosporium elodeaea are newly recorded in Viet Nam.
SCREENING OF SALT TOLERANT BACTERIA FOR PLANT GROWTH PROMOTION ACTIVITIES AND BIOLOGICAL CONTROL OF RICE BLAST AND SHEATH BLIGHT DISEASE ON MANGROVE RICE
Authors: Minh Nguyen Van
Published: April 2018

From 22 rice, soil and water samples collected in the field of Long An and Tien Giang provinces, we isolated and screened 87 strains of bacteria around the root zone and endophytic bacteria. Through testing the ability of plant growth stimulation, the result showed 16 strains were capable of nitrogen fixation, 13 strains were capable of phosphate solubilization, 27 strains were capable of IAA production and 2 strains had all 3 activities. By the dual testing method and the percentage of inhibition method between bacterial and fungal pathogen, LD5 and LS6 strains had the highest antifungal activity against Rhizotocnia sp. CR1 at 94.02 %. TS3 and TĐ13 strains had the highest antifungal activity against Magnaporthe sp. BP3 at 81.74 ± 0.88 % and 80 ± 0.60 %, respectively. Furthermore, there were 6 strains inhibiting both Rhizotocnia sp. CR1 and Magnaporthe sp. BP3 (LĐ5, LS4, LS6, LN1, LN6, TS3). The strains were identified by biochemical methods. The results showed that LD5, LS6 and TS3 were 70.37 % similar to Bacillus thurigiensis, TD13 strain was 70.37 % similar to Bacillus pantothenticus, TD9 strain was 72.72 % similar to Azotobacter vinelandii and TD6 strain was 70.37 % similar to Bacillus subtilis. Regarding the test of activity to stimulate growth in net house model, combination of 4-strain (TD6, TD9, TD13, TS3) had the effect of increasing the length of roots, trunk and weight of rice compared with control treatment. For evaluation of biocontrol of fungal pathogen in net house model, the abilities to control sheath blight in N-2C1 and N-LĐ5 treatment were the highest (40.59 % and 39.06 %, respectively). The ability to control rice blast in N-2C2 treatment was the highest (41.26 %). The ability to biocontrol both sheath blight and rice blast in N-4C treatment was 37.89 %.
ANALYSIS OF nrLSU GENE TO SUPPORT IDENTIFICATION OF FUNGUS BELONGING TO Cordyceps GENUS AND CLAVICIPITACEAE FAMILY
Authors: Luyen Vu Tien
Published: April 2018

Nucleotide sequences of the nuclear large ribosomal subunit (nrLSU) have been used in fungal systematics for a long time. nrLSU was also used in Cordyceps and related genera within the Clavicipitaceae family. A previously identified sample by morphology and ITS was used in this research to analyze the ability of nrLSU to support the identification of entomopathogenic fungi. Our results show that we successfully amplified nrLSU gene using the primer pair LR0R and LR5. The PCR product on agarose gel showed a clear band at 950 bp. Sequencing method was then adopted and proofread before molecular phylogenetic analysis was applied with reference sequences obtained from the publication of Sung et al. Once again, this analysis confirms the DL0004 specimen as Cordyceps neovolkiana.
PURE CULTURE OF WILD TOUGH MUSHROOM COLLECTED FROM TAY NINH PROVINCE OF VIET NAM
Authors: Huong Tran Thi
Published: April 2018

Pure cultures of wild edible mushroom have drawn much attention all over the world for exploitation and conservation of precious genetic resources. In this study, a wild strain of tough mushroom, which has been used as human food in Tay Ninh Province, was collected. The strain was purely cultured on agar medium and grown on different culture media for mycelial growth and fruiting body production. It was also classified based on morphological characteristics and molecular methods. The results show that this wild tough mushroom belongs to Lentinus squarrosulus (Polyporaceae). The best mycelial growth rate (8.3 mm/day) was recorded on the unhusked rice medium containing CaCO3 (1 %) and MgSO4 (1 %). In both of rubber tree sawdust medium supplemented with corn bran (10 %) and the one supplemented with earthworm fertilizer (5 %), the mycelial growth rates were significantly similar (8.4 mm/day) and achieved full colonization of the both supplemented sawdust bags (each 1 kg) after 24 days of incubation. The fresh fruiting bodies yielded 398 - 412 g/bag of the both sawdust media.
ISOLATION AND STUDY ON PURE CULTURE OF WILD EDIBLE MUSHROOMS COLLECTED FROM PROVINCES IN THE SOUTHEAST REGION OF VIET NAM
Authors: Hoa Nguyen Xuan
Published: April 2018

The present study aimed to characterize, classify and attempt to purely culture wild edible mushrooms collected from several provinces in the Southeast region of Viet Nam. We isolated seven mushroom strains that belonged to different genera, Phlebia sp., Ganoderma sp., Tricholoma sp., Polyporus sp., Panus sp., Pleurotus sp. and Phlebopus sp. These mushroom mycelia were able to well grow on both of PGA and modified PGA media. Most of the strains, except for Phlebopus sp (M3), were able to grow on unhusked rice medium supplemented with rice bran and corn bran. Among them, Ganoderma sp. (M20) exhibited the highest mycelial growth rate (7.8 mm/day). The other strains had growth rates of 4.0 - 5.2 mm/day. Rubber tree sawdust supplemented with corn bran or earthworm fertilizer was used for production of fruiting bodies. The results indicated that Phlebia sp. (M10) gave better yields of fruiting bodies (536–539 g/kg dw on the media supplemented with 10 or 15 % corn bran or 5 % earthworm fertilizer) than those of Ganoderma sp. and Pleurotus sp. (M4), 164 and 153 g/kg dw, respectively, on the medium with 5 % corn bran. The mycelia from rice grain spawn of the remaining other strains failed to colonize or form fruiting bodies on the tested substrates.
UiO66–NH2 AS A NEW PHOTOCATALYST FOR THE DEGRADATION OF p–XYLENE IN GASEOUS PHASE
Authors: C. Loc L.
Published: April 2018

Ammonia functionalized UiO66 (UiO66–NH2) in the form of thin film was synthesized by a solvothermal method combined with a dip–coating technique and determined with physicochemical characteristics by X–ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen physisorption measurements (BET), infrared spectroscopy (IR), thermogravimetric analysis (TGA), and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). Also, the obtained material was assessed on the photoactivity in the degradation of p–xylene in the gas phase. Photoreaction was carried out in the micro flow reaction system with the radiation sources of a UV lamp (λ = 365 nm, the power of 8 W) and 81 pieces of light emitting diode (LED) (λ = 400–510 nm, total power of 19.2 W). The results showed that UiO66–NH2 was successfully prepared in the ball shape and featured by a high surface area of up to 576 m2/g, a band gap energy of 2.83 eV and a thermal stability of up to 673 K. Additionally, UiO66–NH2 thin film catalyst performed an efficiency of 1.27 g/gcat in the earlier 60 minutes of the photodegradation of p–xylene. The optimal treatment conditions were established with the moisture content of 8.65 mg/L and the atmospheric oxygen with the concentration of 300 mg/L.
MICROWAVE–ASSISTED SYNTHESIS OF MOLYBDENUM DISULFIDE (MoS2)
Authors: Minh Nguyet Nguyen Thi
Published: April 2018

Molybdenum disulfide (MoS2) nanostructured has been synthesized by a facile and rapid microwave, in which ethylene glycol can act as an excellent susceptor of microwave irradiation. The structure and morphology of MoS2 were characterized by X–ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that nanometer scaled (< 100 nm) molybdenum disulfide with different morphologies can be successfully fabricated by microwave liquid–state method. Microwave irradiation can make localized heating that allows higher heating rates and shorter processing time. The low–cost synthesis procedure paves the way for the exploitation of the present product as electrode material in lithium ion batteries (LIBs).
SYNTHESIS OF BENZOXAZINE MONOMER WITH LOW CURING TEMPERATURE FROM RENEWABLE DIPHENOLIC ACID, BENZYLAMINE AND PARAFORMALDEHYDE
Authors: Viet Cao Xuan
Published: April 2018

The aim of this study was to examine the use of renewable diphenolic acid (DPA) as starting materials together with benzylamine and paraformaldehyde for the synthesis of novel polybenzoxazine resin with low curing temperature. The monomer structure was confirmed by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) was also used to study crosslinking behavior of synthesized material. The benzoxazine monomer exhibited low exothermic peak with the onset around 162 °C, which is significantly lower than conventional benzoxazines derived from bisphenol A. The presence of carboxyl groups in monomer structure is responsible for the low polymerization temperature of this monomer.
THE EFFECT OF LEATHER FIBERS ON VULCANIZATION BEHAVIOR OF NATURAL RUBBER
Authors: Hang Le Thuy
Published: April 2018

This paper shows the primary research results of the effect of the leather fibers on the vulcanization of natural rubber (NR). The fibers used in this research were prepared by grinding waste leather scraps of Vietnam shoe making company. Leather fibers (LFs) and natural latex rubber were mixed together at various rates by a stirring machine.  The obtained composites of natural rubber containing leather fibers were dried at pleasant condition prior to the analysis. Vulcanization behavior of the samples was clarified using a moving die rheometer. The vulcanization temperature as 120 °C is found to be the appropriate temperature for the NR/LFs composite. The increasing of minimum and maximum torque with the increasing of leather fiber content shows the improving in stiffness of natural rubber with the presence of leather fibers. Regarding to curing curves, 40 wt% promises to be the optimal leather fiber content to reinforce natural rubber.
APPLYING BI–FUNCTIONAL DYEING AND UV PROTECTION ON PROTEIN TEXTILE MATERIALS WITH WASTE FROM USED TEABAGS AND MANGOSTEEN HULLS
Authors: Huong Bui Mai
Published: April 2018

This paper presents the connection among three factors of the eco–friendly approach and products: natural textile materials, natural dyes and utilization of waste. The silk and wool materials were chosen as they are both protein fibers that have natural dyes affinity. The dyes were extracted from wastes (mangosteen hulls and used tea–bags) with optimal conditions found during our experiments: 80 °C for 120 min with a 15 % w/v citric acid solution in a 1:10 ratio of mangosteen flakes to solvent and 100 °C for 60 min in a 1:20 ratio of spent tea powder to solvent. The silk dyeing and wool dyeing were carried out at separately proper temperature, time and concentrations. The effect on dyeing of mordant types with different salt–metals mordanting methods and mordant techniques – pre–mordanting, simultaneous mordanting and post–mordanting were undertaken. The K/S values were used for determining the fixation of dyes on textile materials as it reflects the surface luster shade of the dyeing products. The results helped to estimate the influence of dyeing processes on protein materials where low temperature (< 90 °C) and post–mordanting methods exhibited good effects. The UPF values above 29 measured on dye fabric proved the excellent UV protection, even with non–mordant dyeing.