Science and Technology Development Journal <p><span id="result_box" class="" lang="en"><span title="Tạp chí Phát triển Khoa học và Công nghệ (PTKH&amp;CN) của Đại học Quốc gia thành phố Hồ Chí Minh (ĐHQG-HCM) được thành lập từ năm 1997, ra số đầu tiên vào tháng 1 năm 1998. Từ năm 2006 Tạp chí đã"><strong>Science and Technology Development Journal</strong> (STDJ), Vietnam National University - Ho Chi Minh City (VNU-HCM) was established in 1997. And the first issue was published in January 1998 with </span><span title="đăng ký mã số chuẩn quốc tế ISSN 1859-0128.">ISSN 1859-0128. </span><span title="Từ đó cho đến nay, Tạp chí PTKH&amp;CN đã trở thành diễn đàn khoa học quan trọng nhất của đội ngũ cán bộ nghiên cứu, giảng viên, nghiên cứu sinh của ĐHQG-HCM và cũng là diễn đàn khoa học công nghệ đáng tin cậy của">Since then, STDJ has become the most important scientific forum of scientists from VNU-HCM as well as</span><span title="nhiều nhà nghiên cứu, giảng viên các trường đại học khác tại Việt Nam."> other universities. </span><span title="Tạp chí đã trải qua 20 năm phát triển và đã trở thành nhịp cầu giao lưu khoa học, cũng như làm phong phú tài liệu tham khảo cho đội ngũ giảng viên, nghiên cứu sinh, sinh viên ĐHQG-HCM nói riêng và các Trường đại">The magazine has undergone 20 years of development and has become a bridge for scientific exchanges, as well as enriching reference materials for the faculty, doctoral students, students of VNU-HCM in particular and other universities, institutes... </span></span></p> <p><span id="result_box" class="" lang="en"><span title="học phía Nam nói chung. "><br></span><span title="Tính đến hết năm 2016 Tạp chí đã xuất bản được 276 số với 2714 bài nghiên cứu của các nhà khoa học, cán bộ trong và ngoài ĐHQG-HCM trong 5 lĩnh vực nghiên cứu: Kỹ thuật và Công nghệ, Khoa học Tự nhiên,">By the end of 2016, the journal has published 276 issues with 2714 research articles in five areas of research: Engineering and Technology, Natural Sciences, </span><span title="Khoa học Xã hội và Nhân văn, Kinh tế luật và Khoa học Quản lý, Khoa học Trái đất và Môi trường tương ứng với 5 chuyên san chuyên ngành của Tạp chí.">Social Sciences and Humanities, Economics of Law and Management Sciences, Earth Sciences and Environment corresponding to 5 specialized journals of the Journal. </span></span></p> <p><span id="result_box" class="" lang="en"><span title="Tạp chí đã được phát hành tại các thư viện của các đơn vị thành viên của ĐHQG-HCM, các Sở Khoa học Công nghệ của các tỉnh thành trên cả nước và được Hội đồng học hàm Giáo sư Nhà nước đánh giá cao.">The magazine has been widely indexed in the various libraries at Vietnam. </span></span></p> <p><span id="result_box" class="" lang="en"><span title="Từ tháng 12/2006 Tạp chí đã nhận được sự giúp đỡ của tổ chức mạng quốc tế về các xuất bản phẩm khoa học thuộc Hội đồng khoa học quốc tế để tham gia vào mạng lưới các Tạp chí Khoa học quốc tế. "><br></span><span title="Hiện nay tạp chí bao gồm 5 chuyên san sau đây: ">The journal currently consists of the following five sections:<br></span><span title="• Kỹ thuật và Công nghệ, ">• Engineering and Technology</span></span></p> <p><span id="result_box" class="" lang="en"><span title="• Khoa học Tự nhiên, ">• Natural Sciences</span></span></p> <p><span id="result_box" class="" lang="en"><span title="• Khoa học Xã hội và Nhân văn, ">• Social Sciences and Humanities</span></span></p> <p><span id="result_box" class="" lang="en"><span title="• Kinh tế luật và Khoa học Quản lý, ">• Economics, Law and Management</span></span></p> <p><span id="result_box" class="" lang="en"><span title="• Khoa học Trái đất và Môi trường">• Sciences of Earth and Environment</span></span></p> <p><span class="" lang="en"><span title="• Khoa học Trái đất và Môi trường"><span id="result_box" class="" lang="en">• Health Sciences : It includes work from basic science, clinical science, dental, nursing and other related medical fields. <br></span></span></span></p> Viet Nam National University Ho Chi Minh City en-US Science and Technology Development Journal 1859-0128 <p>Copyright The Author(s) 2018. This article is published with open access by Vietnam National University, Ho Chi Minh city, Vietnam. This article is distributed under the terms of the&nbsp;<a href="" target="_blank" rel="noopener">Creative Commons Attribution License (CC-BY 4.0)</a> which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.&nbsp;</p> The priming role of dendritic cells on the cancer cytotoxic effects of cytokine-induced killer cells <p><strong>Introduction</strong>:<em> In vitro</em> cultivation of DCs and cytokine-induced killer cells (CIK cells) - a special phenotype of T lymphocyte populations — for cancer treatment has gained significant research interest. The goal of this study is to understand whether the priming from DCs helps CIK cells to exert their toxic function and kill the cancer cells.</p> <p><strong>Methods</strong>: In this research, DCs were differentiated from mononuclear cells in culture medium supplemented with Granulocyte-macrophage colony-stimulating factor (GM-CSF), and Interleukin-4 (IL-4), and were induced to mature with cancer cell antigens. Umbilical cord blood mononuclear cells were induced into CIK cells by Interferon-γ (IFN-γ), anti-CD3 antibody and IL-2. After 4-day exposure (with DC:CIK = 1:10), DCs and CIK cells interacted with each other.</p> <p><strong>Results</strong>: Indeed, DCs interacted with and secreted cytokines that stimulated CIK cells to proliferate up to 133.7%. In addition, DC-CIK co-culture also stimulated strong expression of IFN-γ. The analysis of flow cytometry data indicated that DC-CIK co-culture highly expressed Granzyme B (70.47% ± 1.53, 4 times higher than MNCs, twice higher than CIK cells) and CD3+CD56+ markers (13.27% ± 2.73, 13 times higher than MNCs, twice higher than CIK cells). Particularly, DC-CIK co-culture had the most specific lethal effects on cancer cells after 72 hours.</p> <p><strong>Conclusion</strong>: In conclusion, co-culture of DCs and CIK cells is capable of increasing the expression of CIK-specific characteristics and CIK toxicity on cancer cells.</p> <p>&nbsp;</p> <p>&nbsp;</p> Binh Thanh Vu Nguyet Thi-Anh Tran Tuyet Thi Nguyen Quyen Thanh-Ngoc Duong Phong Minh Le Hanh Thi Le Phuc Van Pham ##submission.copyrightStatement## 2019-05-27 2019-05-27 22 2 196 212 10.32508/stdj.v22i2.1683 title description none g Critical concentration of the exotic nuclei in the 232Th chain for the alpha analysts <p>The critical concentration plays an important role in the consideration of the analysts, such as gamma or alpha analyzers, for the isotopic analysis. Since the <sup>232</sup>Th isotope and its a-decay daughters are abundant in the environments of soils, rocks and water, it is necessary to investigate the content of these isotopes to reduce the risks of health. In this work, the critical concentrations of the mentioned radioactive nuclei were estimated based on their radioactivities for the alpha analysts. The a-decay half-lives of the nuclei in the decay chain of the <sup>232</sup>Th isotope were re-examined for the radioactivities. The semi-empirical formulae proposed by Viola-Seaberg, Royer and Poenaru were applied to the estimation. The predicted half-lives were normalized by their average values and compared to the data (NuDat) of the National Nuclear Data Center, Brookhaven National Laboratory. The results show that there exist a large uncertainty, 15% - 95% dispersed from the average values (in decimal logarithmic scale), of the half-lives evaluated by each models. Most of average half-lives are close to the NuDat data except the multi-decay-mode isotopes. The relationships between the estimated half-lives and the NuDat data are deduced as linear functions. The decay-constant deviations due to the half-life uncertainty are in the range of 1% - 120% from the average values. The large radioactivity uncertainty due to the half-lives estimated by the three models should be paid an attention for considering the environmental samples for the analysis of the natural exotic isotopes using alpha spectrometers. By assuming an efficiency of 100%, the critical concentration for the alpha analyst of the <sup>232</sup>Th nucleus is found to be in the range 1.5 – 2.5 microgram/(l or kg).</p> Ngoc Duy Nguyen Thi To Vy Vo Kim Uyen Nguyen ##submission.copyrightStatement## 2019-06-07 2019-06-07 22 2 213 218 10.32508/stdj.v22i2.1543 title description none g A combined Euler deconvolution and tilt angle method for interpretation of magnetic data in the South region <p><strong>Introduction</strong>: The purpose of this paper is to determinate the position, depth, dip direction and dip angle the faults in the South region of Vietnam from the total magnetic intensity anomalies, that reduced to the magnetic pole (RTP).</p> <p><strong>Methods</strong>: Based on the Oasis Montaj software, we proposed a new way to compute the positions and the depth to the top of the faults by combining the Tilt angle and the Euler deconvolution methods. In addition, the angle and direction of the dip of theses faults were also determined by considering maximum of the total horizontal derivative of the RTP upward continuation at the different height levels.</p> <p><strong>Results</strong>: The results show that there are 12 faults along the longitudinal direction, latitudinal direction, Northwest — Southeast direction and Northeast — Southwest direction with the mazimum depth is about 3100 m and the dip angle changes in the range of 65-82◦.</p> <p><strong>Results</strong>: These indicate that these methods are valuable tools for specifying the characteristics of geology, contribute to give and confirm the useful information on geological structure in the South region of Vietnam.</p> <p>&nbsp;</p> Hai Hong Nguyen Liet Van Dang Vuong Van Vo ##submission.copyrightStatement## 2019-06-07 2019-06-07 22 2 219 227 10.32508/stdj.v22i2.1226 title description none g Synthesis of cellulose graft ionic liquid using silanization reaction <p><strong>Introduction</strong>: Ionic liquids (ILs) have attached many attentions due to their interesting physicochemical properties. However, ionic liquids have several disadvantages including high viscosity, difficult to purify, separate and recycle, and expensive. Therefore, supported ionic liquids (SIL) have been developed to overcome these problems. SIL based on cellulose material was conventionally synthesized by silanization reaction between ionic liquid trialkoxyl silane and hydroxyl groups on the surface of cellulose. However, low reactivity of cellulose hydroxyl groups causes the low efficiency of silanization reaction. With the aim to resolve these problems and improve the reactivity of cellulose silanization reaction, cellulose graft ionic liquid was synthesized and characterized.</p> <p><strong>Methods</strong>: Cellulose graft ionic liquid (CL-IL) material was synthesized by silanization reaction. The influence of reaction condition such as IL/CL (w/w) ratio, base catalyst (NH<sub>3</sub>) and agent coupling tetraethyl orthosilicate (TEOS) on silanization reaction was investigated. The modified CL-IL materials were characterized using FT-IR, TGA, SEM. The ion exchange properties were evaluated via batch adsorption studies to evidence the efficiency of silanization reaction of cellulose.</p> <p><strong>Results</strong>: The study indicated that adding TEOS with NH<sub>3</sub> catalyst could significantly increase the number of imidazolium groups grafted on cellulose about 75% compared to the conventional approach. CL-IL material is an efficient anion exchange materials displaying fast kinetic adsorption and high capacity adsorption of MO up to 1.4 mmol g<sup>-1</sup>.</p> <p><strong>Conclusion</strong>: High-efficiency of cellulose silanization was obtained by using coupling agent TEOS and base catalyst. Therefore, the silanization reaction can be used for synthesis divers of functional cellulose materials. This approach can be aimed for the design of cheaper and high-performance materials for catalysis, polymer composite and adsorption in water treatment and depollution of industrial wastewater.</p> <p>&nbsp;</p> Ut Dong THACH Thi Lan Nhi Do Ngoc Lan Anh Do Minh Huy Do ##submission.copyrightStatement## 2019-06-13 2019-06-13 22 2 228 234 10.32508/stdj.v22i2.1150 title description none g Construction of expression plasmid for Bacillus subtilis using Pspac promoter and BgaB as a reporter <p><strong>Introduction</strong>: In basic research, it is essential to use an inducible promoter which can be controlled to express a small amount of protein for studying their roles in the cell. Pspac, a well-known weak promoter for Bacillus subtilis, uses isopropyl β-D-1-thiogalactopyranoside (IPTG) as an inducer. However, plasmids carrying this promoter such as pHCMC05 still have a disadvantage which harbors a repetitive DNA fragment of about 200 bp, resulting in structural instability in Escherichia coli, causing difficulty during cloning.</p> <p><strong>Methods</strong>: In this study, we constructed a plasmid that does not carry the repetitive sequences and investigated plasmid structural stability in E. coli, then measured the β-galactosidase reporter gene (bgaB) expression in B. subtilis.</p> <p><strong>Results</strong>: The constructed plasmid pHT2002 was stable over 56 generations while pHCMC05-bgaB was structurally instable and ultimately lost after 42 generations. BgaB activities and Western-blot indicated that BgaB-coding gene under control of IPTG-inducible promoter Pspac could be expressed at low levels.</p> <p><strong>Conclusion</strong>: The study demonstrated that the new expression plasmid without the repeated sequences retained its structural stability in E. coli facilitating the cloning step. The expression plasmid with Pspac promoter for B. subtilis could be used to express a modest amount of the heterologous protein in the presence of IPTG.</p> <p>&nbsp;</p> Hanh Thi-Thu Phan Nguyen Ngoc Yen Nhi Le Thuy Tien Chu Thi Bich Phuong Le Thi Phuong Ngan Phan Thi Phuong Trang Hoang Duc Nguyen ##submission.copyrightStatement## 2019-06-19 2019-06-19 22 2 239 246 10.32508/stdj.v22i2.1284 title description none g A further investigation on the chemical constituents from Euphorbia tirucalli growing in Binh Thuan province <p><strong>Introduction</strong>: <em>Euphorbia tirucalli L.</em> is a medicinal plant popularly distributed in Asian countries. In Vietnam, only one study on the polar extract the plant Euphorbia tirucalli growing in Binh Thuan province, Vietnam was reported, revealing several phenolic components. As of 2019, no chemical reports on the non-polar extract from the Vietnamese plant were found. This research described the isolation and elucidation of compounds isolated from the non-polar extract of E.<em> tirucalli</em> growing in Binh Thuan province.</p> <p><strong>Method:</strong> The n-hexane extract of this plant was carried out by using normal phase silica gel column chromatography, thin-layer chromatography, and gel chromatography (Sephadex LH-20). Analysis of spectroscopic data and a comparison of the NMR data with that in the literature led to the structural elucidation of isolated compounds.</p> <p><strong>Results</strong>: Three terpenoid compounds, euphol (1), lupenone (2), and vomifoliol (3), along with ergosterol peroxide (4), ferulic acid (5), and vanillic acid (6) were isolated and elucidated.</p> <p><strong>Conclusions</strong>: Among them, compound 3 and 4 were reported in the first time from <em>E. tirucalli</em>.</p> <p>&nbsp;</p> Huy Thuc Duong ##submission.copyrightStatement## 2019-06-19 2019-06-19 22 2 247 252 10.32508/stdj.v22i2.1658 title description none g Influence of indium and hydrogen co-doping on optical and electrical properties of zinc oxide thin films deposited by DC magnetron sputtering <p><strong>Introduction</strong>: ZnO-based thin films, known as potential transparent-conducting oxides (TCO), have still attracted much attention in applications for good-performance electrodes and inner layers in solar cells. Recently, the research tendency has focused on improving carrier mobility rather than carrier concentration to enhance performance and response speed of TCO thin films. In this work, Indium, and Hydrogen co-doped ZnO (HIZO) thin films were deposited by using DC magnetron sputtering technique in hydrogen-plasma atmosphere.</p> <p><strong>Methods</strong>: Indium-doped ZnO ceramics were used as sputtering targets, in which, Indium content varied from 0.07 to 1.0 at.%. The electrical, optical, structural and surface morphological properties of the as-deposited films were investigated by using Hall effect-based measurement, UV-Vis spectra, X-ray diffraction (XRD) and fieldemission scanning electron microscopy (FE-SEM), respectively.</p> <p><strong>Results</strong>: As a result, the HIZO films sputtered from the 0.1 at.% In-doped ZnO target and at H2/(H2+Ar) ratio of 3.5% exhibit high electron mobility (47 cm2/Vs), the lowest resistivity (4.9x10<sup>-4</sup> Ω.cm) and sheet resistance (4.7 Ω/sq.), simultaneously, high average transmittance (&gt;80%) in the visible – near IR spectrum regions.</p> <p><strong>Conclusion</strong>: Based on these results, the HIZO films are considered as potential TCO thin films that can be well-used as transparent electrodes in solar cells.</p> <p>&nbsp;</p> Nguyen Huu Truong Tinh Van Nguyen Tuan Anh Thanh Pham Dung Van Hoang Hung Minh Vu Hoi Cong Nguyen Thang Bach Phan Vinh Cao Tran ##submission.copyrightStatement## 2019-07-07 2019-07-07 22 2 253 257 10.32508/stdj.v22i2.1657 title description none g Application of variance reduction techniques in EGSnrc based Monte-Carlo method <p><strong>Introduction</strong>: Monte Carlo (MC) is considered to be the most accurate method to calculate dose distribution in radiation therapy. However, the limitation of MC simulations is the long calculation time to reach the desired statistical uncertainty in the dose calculation as well as in clinical practice. To overcome the above limitations, Variance reduction techniques (VRTs) has developed and shorten the calculation time while maintaining accuracy. Therefore, the purpose of this study is the application of VRTs in code EGSnrc to find the optimal method for accelerator simulation and calculated dose distribution using MC method.</p> <p><strong>Methods:</strong> The linear Accelerator HPD Siemens Primus at the General Hospital of Dong Nai had been simulated by using BEAMnrc code and several variance reduction techniques such as: range rejection, photon forcing, bremsstrahlung photon splitting (uniform, selective and direction)... These VRTs were used under the same set of input parameters as histories of 2x10<sup>8</sup>, photon energy of 6 MV, structure, size and material of the phantom… The computational efficiency ε is calculated by the following equation ε = 1/T.σ<sup>2&nbsp;</sup>where T is the CUP time of calculation and &nbsp;σ<sup>2&nbsp;</sup>is an estimate of the variance, for evaluating and selecting the VRT which gives the best computational efficiency.</p> <p><strong>Results</strong>: The results showed a good agreement between the calculated dose and measured ones when applying different VRTs. These techniques were significantly reduced uncertainty in simulation compared the analog cases. Specifically, the efficiency of DBS and UBS improved by more than 90 times and 15 times compared with the analog instances, respectively. Rang rejection and photon forcing techniques also have<br>improved the efficiency of simulation, but not significantly.</p> <p><strong>Conclusions:</strong> The application of the VRTs for EGSnrc increase the efficiency of the simulation. VRTs is a powerful tool that should be applied for the simulation by code EGSnrc to improve calculation efficiency by reducing simulation time and its variance. Our results show that the direction bremsstrahlung splitting (DBS) gives the<br>best computational efficiency.</p> <p>&nbsp;</p> Tuan Duc Hoang Tai Thanh Duong Oanh Thi Luong Loan Thi Hong Truong ##submission.copyrightStatement## 2019-07-12 2019-07-12 22 2 258 263 10.32508/stdj.v22i2.1234 title description none g A brief introduction to Quillen conjecture <p><strong>Introduction</strong>: In 1971, Quillen stated a conjecture that on cohomology of arithmetic groups, a certain module structure over the Chern classes of the containing general linear group is free. Over time, many efforts has been dedicated into this conjecture. Some verified its correctness, some disproved it. So, the original Quillens conjecture is not correct. However, this conjecture still has great impacts on the field cohomology of group, especially on cohomology of arithmetic groups. This paper is meant to give a brief survey on Quillen conjecture and finally present a recent result that this conjecture has been verified by the authors.</p> <p><strong>Method</strong>: In this work, we investigate the key reasons that makes Quillen conjecture fails. We review two of the reasons: 1) the injectivity of the restriction map; 2) the non-free of the image of the Quillen homomorphism. Those two reasons play important roles in the study of the correctness of Quillen conjecture.</p> <p><strong>Results</strong>: In section 4, we present the cohomology of ring ​ which is isomorphic to the free module ​ over ​. This confirms the Quillen conjecture.</p> <p><strong>Conclusion</strong>: The scope of the conjecture is not correct in Quillens original statement. It has been disproved in many examples and also been proved in many cases. Then determining the conjectures correct range of validity still in need. The result in section 4 is one of the confirmation of the validity of the conjecture.</p> <p>&nbsp;</p> Tuan Anh Bui Thi Anh Nguyen ##submission.copyrightStatement## 2019-06-14 2019-06-14 22 2 235 238 10.32508/stdj.v22i2.1229 title description none g