bluuebunny/crossref_metadata_2025 huggingface dataset:
Neutron Yield from (γ, n) and (γ, 2n) Reactions following 100 MeV Bremsstrahlung in a Tungsten Target
Authors: Khai Nguyen Tuan , Thiep Tran Duc , An Truong Thi , Cuong Phan Viet , Vinh Nguyen The
Published: April 2018

The photonuclear reactions of (γ, xn) or (γ, xnp) types can be used to produce high-intensity neutron sources for research and applied purposes. In this work a Monte-Carlo calculation has been used to evaluate the production yield of neutrons from the (γ, n) and (γ, 2n) reactions following the bremsstrahlung produced by a 100 MeV electron beam on a tungsten target.
Effect of Annealing Temperature on the Li\(^{ + }\) Ionic Conductivity of La\(_{0.67 - x}\)Li\(_{3x}\)TiO\(_{3 }\)
Authors: Trong Le Dinh , Long Pham Duy , Dinh Nguyen Nang
Published: April 2018

Perovskite La0.67-xLi3xTiO3 with x = 0.10, 0.11, 0.12 and 0.13 were firstly annealed at 800 oC then treated by reactive milling, followed by post-annealing at temperatures from 1100 to 1200oC. The crystalline structure of grain and grain-boundary were characterized by XRD and SEM. The impedance measurements showed that nanocrystalline La0.67-xLi3xTiO3 after being annealed at 1150 oC possessed a grain conductivity as high as 1.3×10-3 S.cm-1. The grain-boundary conductivity was enhanced one order in magnitude after annealing at temperature higher 1100oC and consists of 5.8×10-5 S.cm-1. The results have also showed the limitation of the adiabatic thermal treatment for the improvement of the grain-boundary conductivity and suggested the way to overcome the limitation by rapidly cooling the samples from the high temperature to room temperature.
Table of Contents
Authors: - - -
Published: April 2018

Table of Contents, Vol. 24 No.2 (2014)
Development of the C-band radiometer and use it for sea surface temperature research in Vietnam
Authors: Lan Anh Vo Thi , Ngoc Ngo Tuan , Chung Doan Minh , Kostov K. G. , Vichev B. I.
Published: April 2018

The microwave (MW) sensors are being used widely on the ground based, airborne and satellite due to their advantage of being worked day/night and cloudy free. The MW radiometer (RDM) is an example of such passive MW device for remote measurement of environmental parameters as like soil moisture, sea surface temperatures. The satellite SMOS of ESA observing soil moisture and ocean salinity and satellite HYDROS of NASA are two examples of these devices. This paper describes briefly the research method and some results based on the protocol cooperative project between Vietnam and Bulgarian namely "Development of the C band radiometer and use it for vegetation biomass and sea surface temperature research in Viet Nam" accomplished by the Space Technology Institute.
Development of Spray Pyrolysis System for Deposition of Nano-structure Materials
Authors: Son Vuong , Chien Nguyen Duc , Toan Truong Thanh , Anh Doan Tuan , Tuan Mai Anh , Thuy Luong Thi Thu , Thanh Pham Thi Kim
Published: April 2018

In this paper, we report the development of the spray pyrolysis technique for preparing different nano-structure materials toward the application in thin film solar cells. The spray pyrolysis system can heat up the substrate to 6000C with less than 0.01% full scale. The ramping rate can be set to 100C per minute. The effective coating area can be up to 100 x 100 mm2. Using this technique, the thickness and roughness of the films can be controlled. The obtained morphology, the microstructure of the thin-films, given by scanning electron microscope, X ray diffraction…showed that the system is suitable for deposition of different layers of the dye sensitized solar cell.
Optical Property and Photoelectrical Performance of a Low-bandgap Conducting Polymer Incorporated with Quantum Dots Used for Organic Solar Cells
Authors: Thao Tran Thi , Hai Vu Thi , Dinh Nguyen Nang , Trong Le Dinh
Published: April 2018

By using spin-coating technique, a low bandgap conjugated polymer, poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopen-ta[2,1-b;3,4-b′]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT)  and its composite thin films have been prepared. The optical absorption and photoconductive properties with over a wide spectral range, from 350 to 950  nm, were characterized. The obtained results showed that PCPDTBT:10 wt% CdSe  composite is the most suitable for efficient light-harvesting in polymer-based photovoltaic cells. The photoelectrical conversion efficiency (PCE) of the device with  a multilayer structure of ITO/PEDOT/ PCPDTBT:CdSe /LiF/Al  reached a value as large as 1.34% with an open-circuit voltage (Voc) = 0.57 V, a short-circuit current density (Jsc) = 4.29 mA/cm2, and a fill factor (FF) = 0.27. This suggests a useful application in further fabrication of quantum dots/polymers based solar cells.
A Novel Method of Immobilizing Antigens on Gold Electrode for Immunosensing
Authors: Uyen Nguyen Hoang Phuong , Nenad Gajovic-Eichelmann , Bier Frank. F. , Thanh Ngo Vo Ke
Published: April 2018

An antigen modified gold electrode based on a self-assembled lipoic acid monolayer has been developed. The contact angle measurement and cyclic voltammetry confirm the formation of a dense self-assembled monolayer on gold from 100 mM lipoic acid in ethanol. The electrochemical behavior shows a stable activity in a range of potential from -0.2 V to 0.65 V vs. Ag/AgCl. By applying a potential of 1 V vs. Ag/AgCl the monolayer is completely removed by oxidative desorption and a clean gold surface re-established. This allows for an easy renewal of the gold surface and recycling of modified immunosensor chips. This lipoic acid monolayer was covalently functionalized with a small molecule antigen synthesized from progesterone-3-(O-carboxymethyl)oxime and 4,7,10-trioxa-1,13 tridecanediamine to form a well ordered, low unspecific binding, antigen layer for an antibody-antigen interaction study.The effectiveness of antigen - antibody binding reaction was demonstrated by fluorescence imaging using a fluorescence-labeled anti-progesterone antibody as the binding partner. The new approach represents a way of improving the surface chemistry of electrochemical, surface-plasmon resonance and QCM-based immunosensors for which reusability, simplicity and sensitivity in flow-injection mode are required.
Enhancement of Lasing Emission in the Metalliccoated Microsphere Cavity Based on Er-doped Silica Glasses
Authors: Hoi Pham Van , Anh Nguyen The , Trang Nguyen Thi Thu , Thang Le Huu , An Nguyen Van
Published: April 2018

In this paper, we present a review of enhancement and wavelength shift of abnormal upconversion green light emission from erbium ions doped in silica with narrow linewidth in the metallic-coated microsphere cavity. Although the phenomenon of the 537 nm- green light emission is not yet understood, its enhancement of several orders of magnitude seems to be due to the excitation of plasmons. The metallic-coated microsphere cavity has led to the lowest threshold so far observed in microsphere cavity lasers from 0.2 mW to 60 nW. By combining microcavity and surface plasmonic enhancement effect the researchers have created a new kind of photonic devices.
Facile Synthesis of Carbon Quantum Dots by Plasma-liquid Interaction Method
Authors: Tung Do Hoang , Thuong Tran Thi , Cong Nguyen Dinh , Liem Nguyen Thanh , Kha Nguyen Van , Manh Le Hong , Minh Pham Hong , Thuy Nguyen Thi Thu , Hoa Nguyen Minh , Phu Nguyen Van
Published: April 2018

Carbon quantum dots (CQDs) are a novel type of fluorescent nano-materials with various unique properties. They are recently attracting enormous interest due to their superiority in water solubility, chemical inertness, low toxicity, ease of functionalization as well as resistance to photo-bleaching and potential applications in biomedical indication, photo-catalysis, energy conversion, optoelectronics, and sensing. In this work, we present a facile and environmentally friendly synthesis of CQDs based on plasma - liquid interaction method. This is a single-step method and does not use toxic chemicals. The size distribution of obtained CQDs is rather uniform at approximately 3 nm. The emission peak of CQDs shifts from 427 nm to 523 nm as the excitation wavelength is varied from 340 nm to 460 nm. The non-equilibrium reactive chemistry of plasma liquid interaction is responsible for acceleration of the CQDs formation process.
Left-right Model for Dark Matter
Authors: Phung Dong Van , Do Huong Thi
Published: April 2018

We argue that dark matter can automatically arise from a gauge theory that possesses a non-minimal left-right gauge symmetry, SU(3)_C \otimes SU(M)_L \otimes SU(N)_R \otimes U(1)_X, for (M,N)=(2,3), (3,2), (3,3), \cdots, and (5,5).
Table of contents (Volum 14 Number 1 (2016))
Authors: Biotechnology Journal Of
Published: April 2018

Volum 14 Number 1 (2016)
Screening of hybridoma cell lines secreting monoclonal antibodies specific for staphylococcal enterotoxin B (SEB) derived from Staphylococcus aureus
Authors: Minh Nghiêm Ngọc , Thu Nguyễn Thị Hoài , Linh Phạm Thùy , Dương Thân Đức , Hằng Vũ Thị Thu , Phan Lê Văn
Published: April 2018

Staphylococcus aureus (S. aureus) produces 11 types of toxins and more than 20 different Staphylococcal enterotoxins (SEs), including SEA to SEE, SEG to SER and SEU. Among them, enterotoxin type B (Staphylococcal enterotoxin B - SEB) is quite heat stable and causes gastrointestinal diseases in food poisoning. The symptoms of SEB intoxication begin with the onset of sudden fever, about 40oC to 41oC, chills, headache, muscle aches and dry cough. Some patients feel shortness of breath and chest pain. Although SEB is not considered lethal, high level of exposure can lead to shock and death. Therefore, a nontoxic SEB recombinant antigen was produced to immunize mice to create B lymphocytes. Myeloma cells were fused with the B lymphocytes to generate  hybridoma lines. The screening of monoclonal antibodies for the SEB antigen was determined by ELISA and Western blot tests. This study demonstrates that an SEB recombinant antigen can immunize a response against SEB in BALB/c mice. The production of monoclonal antibodies will be used to make a rapid detection strip for SEB based on immunochromatography.
Development of an ELISA using the surface antigen one protein to detect for Streptococcus suis infection
Authors: Chiêu Trần Thị Bích , Hoa Võ Minh , Uyên Phan Nhã , Hùng Trần Mạnh , Châu Nguyễn Văn Vĩnh , Hoa Ngô Thị
Published: April 2018

Streptococcus suis (S. suis) is one of the most important pathogens to cause acute bacterial meningitis in Viet Nam and other Asia countries including Thailand and Hongkong. We investigated the potential of using ELISA with the SAO protein as antigen to detect for S. suis specific sero positive. An SAO specific antibody collected from hyperimmunised rabbits was employed to develop the prototype ELISA. S. suis and other bacterial pathogens were used to validate the sensitivity and specificity of this method. This prototype ELISA was validated using serum samples collected from meningitis patients to evaluate its application in sero surveillance. The prototype ELISA protocol included a 0.1mg/well concentration of the cloned and purified SAO-M antigen; the primary antibody, anti SAO-M protein, and secondary antibody were used at the dilution of 1:500 and 1:10000, respectively.  Rabbit antisera contained specific SAO-M antibody with 100% specificity and titer of >1:16000.  Validating the prototype ELISA using serum samples collected from patients infected with S. suis and other common pathogens for bacterial meningitis in Vietnam showed the specificity of 95% and sensitivity of 90%. Our current results confirmed the initial success in developing the prototype ELISA in diagnosis for S. suis infections and the potential for its future application.
Study on genetic diversity of Castanopsis phuthoensis Luong in Phu Tho province, Vietnam by RAPD markers
Authors: Thọ Nguyễn Văn , Linh Lê Thị Mai , Viễn Nguyễn , Tiến Phạm Quang
Published: April 2018

Castanopsis phuthoensis Luong is an endemic tree species of Phu Tho province, only distributed narrowly in forest rehabilitation in two communes belonging to Doan Hung district with density of this species is very low, only from 3.1 to 11.1 trees per hectare. Diameter distributions of the species of number of trees is characterized by curve style with a peak in 20cm or 24cm diameter classes. As it is difficult to find the seedling in the nature, research on forest structure, relations between tree species and genetic diversity is very necessary to define method of conservation for this species. In this study, we used RAPD markers to study on genetic diversity of Castanopsis phuthoensis Luong. The random amplified polymorphic DNA (RAPD) based on the polymeraze chain reaction (PCR) detects nucleotide sequence polymorphism using a single 10mer of arbitrary nucleotided sequence. The RAPD technology has quickly gained widespread acceptance and application because it providesa tool for genetic analysis that have not previously benefited the use of molecular markers. In this study, ten random primers to analyse the genetic diversity of 15 Castanopsis phuthoensis Luong samples that were collected from Phu Tho province, Vietnam. 9 RAPD primers gave DNA polymorphism and 01 RAPD primer OPA20 gave not DNA polymorphism. In the analysis region 0.25-2 kb, there were 56 DNA fragments amplified and 34 DNA fragments were polymorphic. Genetic similarity coefficients of 15 Castanopsis phuthoensis Luong samples ranged from 0.55- 0.95. The phylogenetic tree of 15 samples are divided into two main groups. As results of RAPD-PCR analysis, these samples were collected from the homologous geographical locations and the genetic diversity of 15 samples is not high. Therefore, it is necessary to conserve the "Castanopsis phuthoensis Luong".
Co-expression of AGPS and AGPL genes encoded for AGPase from cassava to enhance starch accumulation in transgenic tobacco
Authors: Đoài Nguyễn Văn , Hồng Nguyễn Minh , Ngọc Lê Thu , Thơm Nguyễn Thị , Trọng Nguyễn Đình , Trang Vũ Huyền , Hường Nguyễn Thị Thuý , Vân Phạm Thị , Ngọc Phạm Bích
Published: April 2018

The AGPase (ADP-Glucose pyrophosphorylase) is one of the ubiquitous enzymes catalyzing the first step in starch biosynthesis. It plays an important role in regulation and adjusts the speed of the entire cycle of glycogen biosynthesis in bacteria and starch in plants. In higher plants, it is a heterotetramer and tetrameric enzyme consisting two large subunits (AGPL) and two small subunits (AGPS) and encoded by two genes. In this paper, both AGPS and AGPL genes were sucessfully isolated from cassava varieties KM140 and deposited in Genbank with accession numbers KU243124 (AGPS) and KU243122 (AGPL), these two genes were fused with P2a and inserted into plant expression vector pBI121 under the control of 35S promoter. The efficient of this construct was tested in transgenic N. tabacum. The presence and expression of AGPS and AGPL in transgenic plants were confirmed by PCR and Western hybridization. The starch content was quantified by the Anthrone method. Transgenic plant analysis indicated that that two targeted genes were expressed simultaneously in several transgenic tobacco lines under the control of CaMV 35S promoter.  The starch contents in 4 analyzed tobacco transgenic lines displays the increase 13-116%  compared to WT plants. These results indicated that the co-expression of AGPS and AGPL is one of effective strategies for enhanced starch production in plant. These results can provide a foundation for developing other genetically modified crops to increase starch accumulation capacity.
Study of suitable media for laccase synthesis of basidiomycete fungi from Bidoup - Nuiba park and its reactive dye decolorization ability
Authors: Hiền Trần Thị Thu , Hiền Lê Thị , Huynh Nguyễn Văn , Hằng Đinh Thị Thu , Hà Đặng Thị Cẩm
Published: April 2018

A fungal strain FBD154 with high laccase production was isolated from Bidoup-Nui Ba Parks, Lam Đong, Vietnam. FBD154 was identified as Polyporus sp. FBD154 based on traditional method and ITS sequence analysis. Polyporus sp. FBD154 synthesized laccase with high activity 74925 U/l on modified TSH1 (200 g/l containing potato extract, 1 g/l casein, 1 g/l rice bran, 5 g/l soybean meal, 10 g/l manose, 3 g/l NH4Cl, 0.3 mM CuSO4, pH 4). Crude laccase of Polyporus sp. FBD154 was applied to decolor several synthetic and commercial dyes. After 30 min, laccase from Polyporus sp. FBD154 could decolorize synthetic dyes at 100 mg/l concentration with efficiency of 60% acid red (NY1), 18% acid red 299 (NY7), 52% acid blue 281 (NY5) and 83% Remazol Brilliant Blue R (RBBR) without mediator. For commercial dyes at concentration of 100 mg/l, color removal efficiency reached to 62% megafix black CLS (CLS) and 72% everzol red LF2B (LF-2B) without mediator. Efficiency of synthetic dye removal by Polyporus sp. FBD154 crude laccase with 200 µM mediator obtained 90% RBBR with violuric acid (VIO) after 30 min; 80% NY5 with hydroxybenzotriazole (HBT) for 24 hours; 87% NY1 with acetosyringone (Ace) for 5 min; 92% NY7, 91% LF-2Band 73% CLS with syringaldehyde (Syr) for 5 min. The obtained evidences show that laccase was synthesized by Polyporus sp. FBD154 with high potential for application in wastewater treatment of textile plants in particular as well a sin detoxification of polycyclic aromatic compounds in general.
Study on the effect of radiation-degraded β-glucan on body weight gain and blood biochemical indexes in mice
Authors: Long Nguyễn Thành , Xô Dương Hoa , Luân Lê Quang
Published: April 2018

The suspension solution containing 10% water-insoluble β-glucan extracted from yeast cell wall was irradiated by gamma rays from a Co-60 source for degradation. The water-soluble β-glucan products with molecular weight (Mw) of about 30.5, 24.9 and 10.8 kDa were successfully prepared from the samples irradiated at the doses of 100, 200 and 300 kGy, respectively. The obtained water-soluble β-glucan products were tested in mice for examination of their effect on the weight gain, feed conversation rate and blood chemistry indexes. The results after 4 weeks testing indicated that the oral supplementation of all water-soluble β-glucan samples prepared by gamma rays Co-60 irradiation method promoted the increase of body weight as well as the efficiency in converting the feed mass into the weight gain in the tested mice. In addition, β-glucan samples also reduded some contents of blood biochemistry indexes such as of glucose, urea, total protein, triglyceride and cholesterol in tested mice. The supplementation by 2 mg per mouse water-soluble β-glucan product with Mw ~ 24.9 kDa prepared by gamma irradiation at 200 kGy enhanced 16.1% the body weight and decresed 13.3% the feed conversation rate for the tested mice. The results on the blood biochemistry indexes also indicated that this β-glucan product reduced the contents of glucose, urea, total protein, triglyceride, and cholesterol in blood of tested mice by 27.1, 67.3, 56.0, 57.4 and 51.5%, respectively, compared to those in blood of the control ones. Thus, the low Mw and water-soluble β-glucan prepared by irradiation method can be applied as a potential material for production of the functional foods.
The influence of some factors on the reproduction and growth of Saccharomyces cerevisiae MS42
Authors: Quyên Nguyễn Văn , Thảo Nguyễn Quang , Anh Nguyễn Thảo , Đạt Nguyễn Thành
Published: April 2018

Research on the growth of yeast is a critical requirement, occupying an important role in the technology of alcohol production. In reality, there are many factors affecting on the reproductive process and the growtht of yeast such as: temperature, pH, dissolved oxygen content, sugar content, nutrients, etc... The quantity and quality of yeast decide the quality on the wine products. When the amount of yeast is abundant, the fermentation speed is faster, which is an important factor in preventing infection from harmful microorganisms during fermentation. The study on influences affecting the growth of yeast is necessary to ensure the main aim of the propagation which is to create good quality breeding populations of yeast in a short time period. Furthermore, this has important implications for the fermentation process to create good products. Besides, increasing the speed and the number of yeast cells in practice, efficient, inexpensive materials used, as well as a common key element in the production process also bring high economic efficiency. In this study, basic factors affecting the growth of the species Saccharomyces cerevisiae MS42 we determined. Optimal conditions and compositions of the medium for breeding are shown in following: sugar content is 80 g/l: pH = 5.0; temperature from 28oC, the amount of dissolved oxygen from the initial is 7.0 mg/l, after 24 hours of incubation (since followed the same), the number of yeast cells has reached the maximum (219.5 ± 3.0 million cells/ml) and budding cell ratio (approximately 70 - 72%).
Removal of lead by sulfate-reducing bacteria in anaerobic continuous stirred tank reactors
Authors: Yên Nguyễn Thị , Hoa Kiều Thị Quỳnh
Published: April 2018

Lead contaminated wastewater negatively impacts to living organisms as well as humans. In recent years, a highly promising biological process using the anaerobic production of sulfide ions by sulfate-reducing bacteria has presented itself as an alternative option for the removal of lead. This process is based on microbial utilization of electron donors, such as organic compounds (carbon sources), and sulfate as the terminal electron acceptor for sulfide production. The biogenic hydrogen sulfide reacts with dissolved heavy metals to form insoluble metal sulfide precipitates Removal of lead by an enriched consortium of sulfate-reducing bacteria (DM10) was evaluated sulfate reduction, sulfide production and lead precipitation. Four parallel anaerobic continuous stirred tank reactors (CSTR, V = 2L) (referred as R1 - R4) were fed with synthetic wastewater containing Pb2+ in the concentrations of 0, 100, 150 and 200 mg L-1 of lead and operated with a hydraulic retention time of 5 days for 40 days. The loading rates of each metal in R1- R4 were 0, 20, 30 and 40 mg L-1 d-1, respectively. The results showed that there was no inhibition of SRB growth and that lead removal efficiencies of 99-100% for Pb2+ were achieved in R2 (100 mg L-1) and R3 (150 mg L-1) throughout the experiment. For the highest lead concentration of  200 mg L-1, a decrease in efficiency of removal (from 100 to 96%) was observed at the end of the experiment. The obtained result of this study might help for a better control operation and performance improvements of reactors.
Extraction, purification and characterization of antifungal and antibacterial substances produced from Bacillus velezensis CP 1604
Authors: Trung Trịnh Thành , Vân Đinh Thị Tuyết , Liên Nguyễn Phương , Lương Đào Thị , Hợp Dương Văn
Published: April 2018

Bacillus velezensis is one of the members of the Bacillus subtilis species complex which is generally considered as safety organism. The bacterium possesses several beneficial properties for crops, especially production of antifungal and antibacterial agents against plant pathogens. In this study, we aimed to investigate the biological properties of antimicrobial subtances produced from B. velezensis CP 1604. From liquid culture, substances with activity against Fusarium oxysporum and Xanthomonas oryzae were extracted by means of adsorption with Amberlite XAD-7, extraction from lyophilized powder using ethanol, precipitation at low pH and extraction with organic solvents of 1-butanol and 2-pentanol. The substances were subsequently purified using High Performance Liquid Chromatography (HPLC). Antifungal substance was eluted at 5.328 min while antibacterial substance was observed at 15.313 min. Mass spectrometry analysis showed that antifungal substance was iturin A with molecular weight of 1042 Da and antibacterial substance was macrolactin A with molecular weight of 402 Da. The antifungal substance was stable at high temperature but antibacterial activity was significantly reduced when treated at 100° C for 2 hours. Both substances reduced the activity at low pH but the activities still maintained at high pH. The antimicrobial activities against the fungal and bacterium were not affected when treated with hydrolytic enzymes such as trypsin, α-chymotrypsin, amylase, lipase and proteinase K. Further safety and efficiency investigations of the antifungal and antibacterial substances from B. velezensis CP 1604 on the plant disease control are required in order to seek for the potential application on sustainable agricultural production.
Cloning, expression and purification of m-cell specific binding peptide (CO1) fused with GFP
Authors: An Nguyen Hoang , Truong Dang Tat , Hieu Tran Van
Published: April 2018

Despite many advantages over injection vaccines such as cost effectiveness, safety and easy to use, and so on, oral vaccines are negligibly concerned. This is mostly because of the availability of vast surface in the gastro-intestinal tract, thereby requiring lot of antigens which could hamper their potential. To circumvent this issue, a novel strategy for targeting antigens to M cells (microfold cells), a minority of cells located in the small intestine for antigen transportation, is utilized by making a fusion protein comprised of an antigen with an M cell specific ligand. Discovered via biopanning, Co1 peptide is a potential ligand because of its small size (12 amino acids) and having an adjuvant capacity. To develop a monitoring model, we fused GFP (green fluorescent protein) as a monitoring marker with Co1 peptide. Initially, co1-gfp fusion gene was created by overlap extension PCR on GFP-encoded vector backbone, then it was incorporated into an expression vector pET22b before transforming into E. coli DH5α. The recombinant vector was screened by PCR method, sequenced and aligned with designed sequences. The in-frame vector was then introduced into E. coli BL21(DE3) for expression by inducing with 0.5mM IPTG. Fusion protein was purified using Ni-affinity chromatography. The results showed that the fused genes were in-frame cloned and completely matched with the designed sequences. SDS-PAGE and Western blot analyses showed Co1-GFP protein expressed in soluble form and could be purified at one-step elution of 500mM imidazole. The purified fusion protein could emit fluorescent light under UV excitation. Collectively, recombinant Co1-GFP fusion protein was successfully produced and its potential applications need to be warranted.
Computational approach for selection of epitope-based dengue vaccine targets
Authors: Nguyen Phuc , Le Ly
Published: April 2018

High antigenic variability in the envelope (E) protein of different virus strains has been a major obstacle in designing effective vaccines for Dengue virus (DENV). To maintain their biological function, some parts of viral proteins remain stable during evolution thus one possible approach to solve this problem is to recognize specific regions within different protein sequences of E that have the tendency to stay constant through evolution. These regions may possess some special attributes to become a vaccine candidate against dengue virus. In this study, a computational approach was utilized to identify and analyze highly conserved amino acid sequences of the DENV E protein. Sequences of 9 amino acids or more were specifically focused due to their immune-relevant as T-cell determinants. Different bioinformatics tools were responsible for revealing conserved regions in the DENV E protein and constructing the phylogenetic tree from the sequence database. The tools also predicted immunogenicity of the identified vaccine targets. Ultimately, two peptide regions of at least 9 amino acids were chosen due to their high conserved attribute in more than 95% of all collected DENV sequences. Moreover, both of them was found to be immune-relevant by their correspondence to known or putative HLA-restricted T cell determinants. The conserved attribute of these sequences through the entire analysis of this study supports their potential as candidates for further in vitro experiments for rational design a universal vaccine which has longer and broader impact.
Construction of GmNAC085 vector for future development of drought-tolerant crops
Authors: Xuan Hoang Thi Lan , Thu Nguyen Binh Anh , Phuc Nguyen Bao Thien , Thao Nguyen Phuong
Published: April 2018

Various members of NAC transcription factor family have been shown to play important roles in regulating plant responses to abiotic stresses, such as drought, cold and salinity. Our previous research on differential expression patterns of twenty three soybean NAC genes (GmNACs) by realtime quantitative PCR suggested a correlation between inducible expression of GmNAC085 and the drought tolerance degree in DT51 and MTD720 soybean cultivars, which presented for the drought-tolerant and the drought-sensitive, respectively. Therefore, the gene has been proposed as a potential candidate for engineering in order to produce new varieties with better drought stress tolerance. However, functional studies of GmNAC085 should be carried out to identify how this transcriptional factor can contribute in the plant stress-responsive pathway. Herein, this paper presented that we have successfully developed a recombinant binary vector carrying full-length cDNA of GmNAC085 and expression of this gene is placed under the control of constitutive promoter CaMV 35S. The generated construct was firstly transformed into E.coli for sequencing the target gene and then the identified genuine construct was transformed into Agrobacterium tumefaciens. This can be used for plant transformation mediated by Agrobacterium in serving for GmNAC085 - related studies using in planta system such as the model plant Arabidopsis and also serving for the development of drought-tolerant crops by genetic engineering. Additionally, results from sequence alignment analysis revealed that GmNAC085s of DT51 and MTD720 had identical nucleotide sequence, thus supporting our hypothesis that difference in GmNAC085 gene expression levels, not the variation in GmNAC085 protein sequence or structure, might cause the difference in plant resistance degree to drought stress in these two soybean varieties.
Enhanced growth and development of Chrysanthemum morifolium in microponic system under light-emitting diodes
Authors: Tung Hoang Thanh , Nam Nguyen Ba , Huy Nguyen Phuc , Phuong Truong Thi Bich , Nhut Duong Tan
Published: April 2018

This paper investigated the growth and development of Chrysanthemum shoots in microponic systems in comparison with shoots in micropropagation system. A microponic culture system, combining micropropagation and hydroponics, could reduce the drawbacks of micropropagation system such as reduction of infection, saving of labor, material, space, etc. In this study, Chrysanthemum morifolium shoots with 3 cm in length were cultured in MC (microponic system with circular container - 12 cm diameter at top, 9 cm diameter at bottom and 8.5 cm in height), MR (microponic system with rectangular box - 8.5 cm in height, 35 x 28 cm at top and 30 x 25 cm at bottom) and micropropagation system (MO - rectangular plastic box with 800 ml of half-strength MS medium containing 30 g/l sucrose and 8 mg/l agar). The results indicated that shoots pretreated with 500 ppm IBA, cultured in MC (15 shoots per container) and ventilated with millipore membrane (MillisealTM, pore size 0.5 µm of diameter 2 cm) under 70% red LED combined with 30% blue LED gave thebest plant height, number of roots, fresh weight, and chlorophyll content (a, b and a+b) (5.18 cm, 12.50, 0.52 g, 28.19 µg/g, 13.56 µg/g and 41.75 µg/g, respectively). The survival rates of plants derived from MC and MR in the greenhouse were higher than those in MO (100%, 100% and 85%, respectively). This study indicated that MR was an effective and simple system for large-scale production of Chrysanthemum morifolium.
Chemical composition and cytotoxic activity of the essential oils of Cymbopogon citratus L. Grown in phu tho province
Authors: Van Hoang Thi Kim , Quy Nguyen Minh , Ha Do Thi Vinh , Hai Nguyen Thanh , Ly Hoang Thi , Hien Nguyen Thi , Trang Duong Thu , Dang Nguyen Hai , Dat Nguyen Tien
Published: April 2018

Culms and leaves of Cymbopogon citratus L. were collected from two regions of Phu Tho province (Thanh Son and Phu Ninh) and used as materials for essential oil extraction. Oils obtained were steam-distilled, analyzed for chemical composition and evaluated for cytotoxic activity against three different cancer cell lines. The GC/MS analysis showed that citral is the major content of the steam-distilled essential oils which was found in the range of 64.15-76.22%. Camphene was found only in culm oils of both regions but it was not detected in the leaf oils. Interestingly, the isomer forms of ocimene present at higher content in the culm oils than in the leaf oils whereas myrcene content in the leaf oils is higher than that in the culm oils. In a cytotoxicity test, four essential oils of culms and leaves of C. citratus from Thanh Son and Phu Ninh showed potent activity against A549 (human lung carcinoma) cell line with the IC50 values ranging from 4.01±0.39 to 6.3±0.54 µg/ml. The essential oils (culms and leaves) from Phu Ninh exhibited moderate effects on the Hela (human cervical adenocarcinoma) cells with the IC50 values of 19.43±1.16 and 42±2.41 µg/ml, respectively. However, they were inactive against the human hepatocellular carcinoma Hep3B cell line. The essential oils from Thanh Son exhibited potent cytotoxic activity against Hela and Hep3B cell lines with the IC50 values ranging from 1.18±0.26 to 8.91±0.32 µg/ml. The results indicated that the essential oils of C. citratus from Thanh Son, Phu Tho could be considered as a promising candidate for the natural sources of anticancer agents.
A DENSITY FUNCTIONAL THEORY STUDY OF ANTIOXIDANT ACTIVITY OF ISOTHIOCYANATES IN BROCCOLI SPROUTS (BRASSICA OLERACEA L.)
Authors: Nguyen Phan Truc Xuyen
Published: April 2018

Antioxidant activity of 9 isothiocyanate derivatives (−N=C=S) extracted from Broccolisprouts (Brassica oleracea L.) has been investigated using density functional theory (DFT) –based computational methods. Through the hydrogen atom transfer (HAT) and single electrontransfer (SET) mechanisms, three thermodynamic parameters including bond dissociationenthalpy (BDE), vertical ionization energy (IE), and vertical electron affinity (EA) werecalculated in the gas phase using B3LYP/6-311++G(3df,3p)//B3LYP/6-311G(d,p) modelchemistry. As a result, the isothiocyanate (ITC) shows potential antioxidant activity via HATmechanism. The most potential antioxidant is 3-isothiocyanato pro-1-en (3ITCP) withBDE(C−H) of 72.9 kcal/mol. The SET mechanism is not dominant in case of the studied ITCs.Moreover, the radicals formed H• removal had more reactive and less stable than the intialneutral compounds with lower IE, higher EA and ω.
EFFECT OF SULFATION ON THE STRUCTURE AND ANTICOAGULANT ACTIVITY OF ULVAN EXTRACTED FROM GREEN SEAWEED ULVA RETICULATA
Authors: Minh Thu Quach Thi
Published: April 2018

Ulvans are sulfated polysaccharides derived from the cell wall of green seaweeds. Thechemical structure of ulvan extracted from Ulva reticulata is reported, focusing on investigationof the sulfated modification of the ulvan and the changes in structure and anticoagulant activity.The results showed that sulfated modification was able to change the ulvan conformationalstructure and markedly enhance its anticoagulant activity.
SEPARATION PROCESS OF ROSMARINIC ACID AND THEIR DERIVATIVES FROM CELASTRUS HINDSII BENTH LEAVES
Authors: Tram Ly Ngoc
Published: April 2018

Rosmarinic acid is a naturally antioxidant, which is biosynthesized from the amino acids Lphenylalanineand L-tyrosine by eight enzymes that include phenylalanine ammonia lyase andcinnamic acid 4-hydroxylase. Rosmarinic acid can also be chemically produced by theesterification of caffeic acid and 3,4-dihydroxyphenyllactic acid. Recently, rosmarinic acid andits derivatives (RA) have attracted interests for their biological activities, which include antiinflammatory,anti-oxidant, anti-angiogenic, anti-tumor, and anti-microbial functions. RAextraction procedure from Xaden leaves Celastrus hindsii was investigated. RA extracts wereobtained from 50 % ethanol extract. The optimal conditions for extraction were as followings:solvent/material ratio 12/1 (v/m), two time extractions, and total extraction time of 3 hours. RAextracts were refined by Diaion HP-20column to have RA with 83.30 % purity and yield 2.86 %(by dry weight material).
LiClO4 CATALYZED AZA-MICHAEL ADDITION OF SECONDARY AMINES TO α,β-UNSATURATED ESTERS UNDER A SOLVENT-FREE CONDITION
Authors: Duc Dau Xuan
Published: April 2018

An efficient aza-Michael addition of secondary amines to some α,β-unsaturated esters hasbeen carried out using LiCLO4 as a catalyst. β-amino esters were obtained in high yields at roomtemperature without using solvent.
REMOVAL OF Ni2+ FROM AQUEOUS SOLUTION BY ADSORPTION ONTO TEA WASTE–DERIVED ACTIVATED CARBON
Authors: Bach Long Giang
Published: April 2018

Activated carbon from a locally available and widespread tea waste source was fabricated, characterized and used as an efficient adsorbent for the removal of Ni2+ from aqueous solutions. The response surface methodology (RSM) and central composite design (CCD) were used to investigate the effect of the essential variables including initial concentration, adsorbent dosage and pH solution on the absorption of Ni2+. The order polynomial regression equations–based model has been developed and 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). Based on the predicted optimum conditions, actual experiment was employed to obtain the maximum percentage of Ni2+ removal efficiency (96.6 %). There is no doubt that the use of tea waste as abundant raw material for the preparation of activated carbon to remove Ni2+from aqueous solutions by five times with negligible change is a promising way.
PLASMA ELECTROLYTIC OXIDATION COATING ON 6061 AL ALLOY USING AN ELECTROLYTE WITHOUT ALKALI IONS
Authors: Tran Quang Phu
Published: April 2018

Plasma electrolytic oxidation (PEO) technique is well known to use for modifying the surface of valve metal such as Al, Mg and Ti, which improves mechanical and corrosion resistance properties. PEO is an electrochemical process of oxidation by creating micro-discharges on the surface of metal immersed in an electrolyte under applying a high voltage. Electrolyte used in PEO process is almost based on alkali ions such as Na ion. The report on PEO process using free-alkali ion is very rare. In this study, the oxide layer on 6061 Al alloy was produced in a free-alkali ion electrolyte containing calcium phosphate and ammonia water by PEO method. Microstructure, micro-hardness and corrosion resistance of PEO coated were investigated and discussed. Surface morphology analysis indicated the coating characterized by micro-pores, pan-cakes like, and micro-crakes with pore size and percentage of pores on coating surface are smaller than 1 mm and 2.5 %, respectively. Micro-hardness and corrosion resistance of PEO coated are greatly improved compared to the bare Al alloy. Free-alkali-ions in oxide layer coated on Al alloy is important for many applications today.
BIODEGRADABLE GELATIN DECORATED Fe3O4 NANOPARTICLES FOR PACLITAXEL DELIVERY
Authors: Nguyen Dai Hai
Published: April 2018

The objective of this study is to prepare biodegradable iron oxide nanoparticles with gelatin (GEL) for paclitaxel (PTX) delivery. In detail, Fe3O4 nanoparticles were prepared and then coated them with GEL (Fe3O4@GEL) conjugate by co–precipitation method. Furthermore, the formation of Fe3O4@GEL was demonstrated by Fourier transform infrared (FT–IR) and powder X–ray diffraction (XRD). The superparamagnetic property of Fe3O4@GEL was also showed by hysteresis loop analysis, the saturation magnetization reached 20.36 emu.g–1. In addition, size and morphology of Fe3O4@GEL nanoparticles were determined by transmission electron microscopy (TEM). The results indicated that Fe3O4@GEL nanoparticles were spherical shape with average diameter of 10 nm. Especially, PTX was effectively loaded into the coated magnetic nanoparticles, 86.7 ± 3.2 % for drug loading efficiency and slowly released up to 5 days. These results suggest that the potential applications of Fe3O4@GEL nanoparticles in the development of stable drug delivery systems for cancer therapy.
SIMPLE SYNTHESIS OF GRAPHENE NANOSHEETS USING A MICROWAVE–ASSISTED METHOD
Authors: Khai Tran Van
Published: April 2018

In this research, few–layer–graphene (FLG) sheets had been successfully fabricated by using a microwave–assisted method. First, graphite intercalation compounds were prepared from potassium–tetrahydrofuran (K–THF) –expanded graphite by solvothermal process, and then the exfoliation was assisted by microwave radiation and sonication process. The resulted nano–graphene has average thickness about ~ 2 nm with a lateral size of 3–7 μm. Raman analysis showed that the as–synthesized graphene nanosheets contain only a few numbers of structural defects or impurities. X–ray photoelectron spectroscopy and Fourier transform infrared spectroscopy spectra revealed that the nano–graphene consisted of several peaks similar to those of graphite, indicating the effectiveness of the solvothermal reduction method in lowering the oxygen level. The electrical conductivity of the as–synthesized nano–graphene was measured to be 170 S/m. In contrast to the Hummer method, the method is simple, inexpensive, and does not generate toxic gas. This simple method could provide the synthesis of high quality nano–graphene on a large scale.
USING THE RESPIRATORY QUOTIENT AS A MICROBIAL INDICATOR TO MONITOR SOIL BIODEGRADATION
Authors: Chi Tran Thanh
Published: April 2018

The effects of nutrient amendments on the variation in time of the respiratory quotient (RQ) were investigated in soil. Microbial activity measured by CO2 production, biomass growth determined by plate counts technique and residual contaminants quantified by gas chromatography analysis were monitored in order to check their relation to RQ fluctuations. RQ values in all treatments displayed significant fluctuations over time which were closely related to the phases of the respiratory response as well as to microbial growth. After pollutant addition, an increase of RQ occurred in all microcosms. RQ values decreased when high degradation activity and microbial growth took place. RQ values slightly increased in all microcosms at the end of the incubation. These results show that the respiratory quotient is closely related to the physiological state of microorganisms and may be a determinable indicator for the efficiency of bioremediation.
A REVIEW OF SEAGRASS STUDIES BY USING SATELLITE REMOTE SENSING DATA IN THE SOUTHEAST ASIA: STATUS AND POTENTIAL
Authors: Thien Huong Nguyen Thi
Published: April 2018

This review presents synthetic results of remote sensing application in monitoring and management of seagrass beds in the Southeast Asia region. The objective of this paper aims to evaluate the status and potential of using remote sensing technologies in seagrass mapping to enhance its effective utilization and management. The results showed that the number of studies in the application of remote sensing for seagrass are still limited, mainly from 2011 to 2017, which focus on habitat mapping (accounting for 62 %) and other studies on the detection of seagrass change in temporal (38 %). The number of studies on using medium and high resolution remote sensing images are approximately about 50 % and 44 %, respectively. Only 6 % studies used very high resolution remote sensing images. Finally, it is suggested that having more study in seagrass bed mapping by using remote sensing data is significant for understanding the variability of seagrass beds in the coastal areas for effective management and protection in the future.
KINETICS AND MODELING OF OIL EXTRACTION FROM VIETNAM LEMONGRASS BY STEAM DISTILLATION
Authors: Binh Thanh Nguyen Dang
Published: April 2018

Essential oils from parts of plants such as stump, flower, kernel, and seed are usually produced by extraction, distillation and mechanical press. In practice, steam distillation is commonly used for the extraction of crude essential oils since it is not only a simple process but also applicable at various scales. Furthermore, the method makes it possible for a keeping of precious components of the oils unchanged. Therefore, studies on kinetics and modeling of the essential oil steam distillation are needed for the optimization of the operating conditions, energy requirement, and the process scale-up.In this work, experiments of lemongrass (Cymbopogon Citratus) steam distillation were carried out and a kinetics model was developed for the extraction of lemongrass essential oil. Raw materials were pretreated by natural drying, primarily crushing and chopping prior to the distillation. The oil yield obtained is in the range of 2.1 – 2.9 ml/kg of raw materials. Composition of the crude oil extracted was measured by GC-MS. Measurements showing that the oil product contains 70.5 % of precious component–Citral in which Neral is 29.8 % and Geranial 40.7 %. The kinetics parameters were estimated from experimental data conducted at various operating conditions for different preparation of the raw materials. The process rate constant (extraction rate constant) describing the extraction efficiency obtained from this study is varied from 0.02 to 0.027 min-1 using first-order kinetic model.
ELECTRODEPOSITION OF CO-DOPED HYDROXYAPATITE COATING ON 316L STAINLESS STEEL
Authors: Hanh Vo Thi , Nam Pham Thi , Phuong Nguyen Thu , Thanh Dinh Thi Mai
Published: April 2018

Hydroxyapatite (HAp) co-doped by magnesium (Mg), strontium (Sr), sodium (Na) and fluorine (F) were deposited on the 316L stainless steel (316L SS) substrate by electrodeposition method. The influences of scanning potential ranges, scanning times, scanning rates to form MgSrFNaHAp coating were investigated. The analytical results FTIR, SEM, Xray, EDX, thickness and adhension of the obtained coating at scanning potential ranges of 0 ÷ -1.7 V/SCE; scaning times of 5, scanning rate of 5 mV/s showed that MgSrFNaHAp coatings were single phase crystals of HAp, rod shape with the thickness 8.9 µm and the adhesion strength reached 8.38 MPa.
Fatigue crack growth at the representative zones in friction stir welding of a heat-treatable aluminum alloy at 200oC
Authors: Tra Tran Hung
Published: April 2018

Aluminum alloy 6063-T5 plates were joined by friction stir welding technique. The fatigue crack growth (FCG) in the thermo-mechanical affected zone (TMAZ) and in the heat affected zone (HAZ) of the welding was examined at 200oC. Although the grain microstructure of the TMAZ was significantly refined in comparison with that of BM, the FCG rate in TMAZ and base metal was shifted a comparable amount when the test temperature was elevated from room temperature to 200oC. In the metallurgical view, the FCG rate in the fine grain TMAZ was higher than that in coarse grain HAZ and base metal site.
BIODIVERSITY AND DISTRIBUTION PATTERNS OF FREE-LIVING NEMATODES COMMUNITIES IN BALAI RIVER, BENTRE PROVINCE
Authors: Thai Tran Thanh , Lam Nguyen Le Que , Yen Nguyen Thi My , Quang Ngo Xuan , Vanreusel Ann
Published: April 2018

Nematodes communities in Ba Lai river, Ben Tre province were investigated in September of 2015 (eight stations from estuary to upstream). The results showed that the nematodes communities have characterized by high density and biodiversity, providing useful information of nematodes assemblages in freshwater habitas, in particular inland river. Also the results indicated that the distribution of nematodes communities in Ba Lai river was strongly discriminated between in and outside of dam with two groups. The Ba Lai dam may be reasons for cause  the nematodes distribution discontinuity. Present study is a pioneering attempt to record the impact of the dam on benthic-invertebrate in Vietnam.