Science and Technology Development Journal http://stdj.scienceandtechnology.com.vn/index.php/stdj <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="https://creativecommons.org/licenses/by/4.0/" 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> A high dynamic range imaging algorithm: implementation and evaluation http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/871 <p>Camera specifications have become smaller and smaller, accompanied with great strides in technology and thinner product demands, which have led to some challenges and problems. One of those problems is that the image quality is reduced at the same time. The decrement of radius lens is also a cause leading to the sensor not absorbing a sufficient amount of light, resulting in captured images which include more noise. Moreover, current image sensors cannot preserve whole dynamic range in the real world. This paper proposes a Histogram Based Exposure Time Selection (HBETS) method to automatically adjust the proper exposure time of each lens for different scenes. In order to guarantee at least two valid reference values for High Dynamic Range (HDR) image processing, we adopt the proposed weighting function that restrains random distributed noise caused by micro-lens and produces a high quality HDR image. In addition, an integrated tone mapping methodology, which keeps all details in bright and dark parts when compressing the HDR image to Low Dynamic Range (LDR) image for display on monitors, is also proposed. Eventually, we implement the entire system on Adlink MXC-6300 platform that can reach 10 fps to demonstrate the feasibility of the proposed technology.</p> <p>&nbsp;</p> Vu Hong Son ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2019-08-07 2019-08-07 22 3 293 307 10.32508/stdj.v22i3.871 title description none g Electrochemical performance of sulfone-based electrolytes in sodium ion battery with NaNi1/3Mn1/3Co1/3O2 layered cathode http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1682 <p><strong>Introduction</strong>: Sulfolane (SL), having an edge of low melting point over other sulfones, has been adopted as an electrolyte co-solvent for lithium-ion battery (LIB), as it exhibits high stability against oxidation and combustion while not causing much side effects to the battery electrochemistry. It is therefore expected that SL may serve as a safety-enhancing agent in sodium-ion battery (SIB). To evaluate the effect of SL content on the behavior of common carbonate-based sodium electrolytes as well as the compatibility of SL-based electrolytes with NaNi1=3Mn1=3Co1=3O2 (NaNMC) cathode, mixtures of 0, 10, 20, 30 or 50% vol. SL and each of the following, EC:PC 1:1 vol. (EP11), EC:DMC 1:1 vol. (ED11), EC:PC:DMC 1:1:3 vol. (EPD113) and EC:PC:DMC 3:1:1 vol. (EPD311), with or without 1M NaClO4, were studied with regard to both inherent properties and performance in NaNMC half-cells.</p> <p><strong>Methods</strong>: Solvent flammability was evaluated via the self-extinguishing time (SET) and ignition time indexes. Conductivity and viscosity were respectively measured by Electrochemical Impedance Spectroscopy (EIS) and Ostwald method. Electrochemical techniques, i.e. Cyclic Voltammetry (CV) and Galvanostatic Cycling with Potential Limitation (GCPL), were used to test the sodium-ion battery performance.</p> <p><strong>Results</strong>: A moderate amount of SL (typically below 30% vol.) proved to enhance both electrolyte non-flammability and self-extinguishing behavior, while maintaining an acceptable compromising rate in viscosity and conductivity. Amongst 30%-SL electrolytes, EPD311-based ones allow the best Na+ diffusion when combined with NaNMC cathode in sodium half-cell configuration. The corresponding system gives satisfactory performance: initial specific capacity of 97 mAh.g<sup>-1</sup>, 92% capacity retention, and above 90% reversibility after 30 cycles at C/10 rate.</p> <p><strong>Conclusion</strong>: SL can be used as a stabilizing co-solvent for SIB, but its content should be limited to below 30% vol. to ensure its effectiveness.</p> THANH DUY VO AN LE BAO PHAN BINH THANH TRAN NAM PHAM PHUONG LE PHUNG MY LOAN LE ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2019-10-03 2019-10-03 22 3 335 342 10.32508/stdj.v22i3.1682 title description none g Frequency distribution of dental caries disease among the local community of Harichand http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1704 <p>A cross-sectional study was designed to determine the dental caries disease and associated risk factors among the study subjects in Harichand, Pakistan. A total of 150 patients were investigated, of which male to female percentage was (77%) and (23%) respectively. The maximum tooth decay (33%) was found in the age (years) of 21-30. The results showed that decayed and missing teeth (DMT) were (57%), followed by decayed, missing and filled teeth (DMFT) (27%) and filled teeth (FT) (16%). Most of the patients were suffering from score 6, (30%). The DMT and score 6 was recorded high among the study subjects in Harichand. This study will update the epidemiology of dental caries diseases, increase awareness, and provide the base line information for future research and intervention. Further studies are recommended on large scale.</p> Haroon Haroon Tauseef Ahmad Muhammad Khan Inamullah Inamullah Arif Jan Hui Jin ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2019-08-20 2019-08-20 22 3 314 316 10.32508/stdj.v22i3.1704 title description none g Homology of Borel Subgroup of SL(2,\mathbb{F}_p) http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1225 <p>In this paper we compute the integral homology of the Borel subgroup $B$ of the special linear group $SL(2,\mathbb{F}_p), p$ is a prime number. Arcoding to Adem \cite{AJM} these are periodic groups. In order to compute the integral homology of $B,$ we decompose it into $\ell-$ primary parts. We compute the first summand based on Invariant Theory and compute the rest summand based on Lyndon-Hochschild-Serre spectral sequence. We assume that $p$ is an odd prime and larger than $3.$</p> Bui Anh Tuan Bao Quoc Vo ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2019-08-18 2019-08-18 22 3 308 313 10.32508/stdj.v22i3.1225 title description none g The influence of thickness on ammonia gas sensitivity of reduced graphene oxide films http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1236 <p>Graphene is a single carbon layer in a two-dimensional (2D) lattice. Its delocalized π bonds give rise to unique electronic properties, but these π bonds are easily influenced by the environment. Meanwhile, many publications present that the sensitivity of graphene is not only necessarily intrinsic to this material but also by external defect. In this study, we produced reduced Graphene Oxide (rGO) sensors based on random rGO plates. We analyzed the ammonia (NH3 ) sensitivity of such sensors as a function of thickness of rGO films (in terms of change in transparence) at room temperature. When the thickness of rGO films decreased, a maximum response was observed for the thinnest rGO film (the transparence was 84 %), with a sensitivity up to 38 %. Our results suggest that the dependence of NH3 sensitivity on rGO films thickness is dictated by the fully exposed surface area for thinnest films and by 2D charge carrier hopping through edge defects.</p> <p>&nbsp;</p> Tran Quang Nguyen Huynh Tran My Hoa Tran Quang Trung ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2019-08-03 2019-08-03 22 3 289 292 10.32508/stdj.v22i3.1236 title description none g The research determines appropriate parameters in the synthesis process of syringic acid grafted chitooligosaccharides http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1289 <p><strong>Introduction</strong>: The aim of this study is to determine appropriate parameters in the synthesis of syringic acid onto chitooligosaccharides (COSs) with an ascorbic acid/hydrogen peroxide redox pair in order to obtain the derivative with the highest grafting degree.</p> <p><strong>Methods</strong>: In this study, syringic acid grafted COSs, catalysed by an ascorbic acid/hydrogen peroxide redox pair were investigated. The synthesis conditions were investigated, including the mass ratio between syringic acid and COSs, pH, temperature and synthesis time. Characteristics of the derivative were evaluated by Thin Layer Chromatography (TLC), Ultraviolet-Visible (UV-vis) and Fourier Transform Infrared (FT-IR) spectroscopy. The activities of COSs and derivative were evaluated by antimicrobial ability.</p> <p><strong>Results</strong>: The results showed, that the best conditions for the synthesis were the mass ratio between syringic acid and COSs at 0.5:1, pH 5, temperature 27<sup>o</sup>C, for 6 hours with grafting degree at 32%. The TLC assay showed, that free ascorbic acid and syringic acid are not present in the product. The UV-vis and FT-IR data confirmed, that syringic acid was successfully conjugated onto COSs. Furthermore, the antibacterial assay showed that syringic acid grafted onto COSs had minimum inhibitory concentration against foodborne pathogenic bacteria at 1%.</p> <p><strong>Conclusion</strong>: The syringic acid onto chitooligosaccharides were successfully synthesized by free radical mediated grafting method with an ascorbic acid/hydrogen peroxide redox pair. The grafting degree of syringic acid onto COSs was greatly affected by many factors, including COSs, syringic acid, pH, as well as temperature and time of reaction. Moreover, the new derivative showed enhanced antibacterial capabilities, as compare to free COSs.</p> <p>&nbsp;</p> Hoai Van Bui Dai-Nghiep Ngo ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2019-08-22 2019-08-22 22 3 317 323 10.32508/stdj.v22i3.1289 title description none g Hydrophobic Property of (R)-3 Amidinophenylalanine Inhibitors Contributes to their Inhibition Constants with Thrombin Enzyme http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1684 <p><strong>Introduction</strong>: Thrombin is the key enzyme of fibrin formation in the blood coagulation cascade. Thrombin is released by the hydrolysis of prothrombinase which is generated from factor Xa and factor Va in the presence of calcium ion and phospholipid. The inhibition of thrombin is of therapeutic interest in blood clot treatment. Currently, potent thrombin inhibitors of (<em>R</em>)-3- amidinophenylalanine, derived from benzamidine-containing amino acid, have been developed so far. In order to quantitatively express a relationship between chemical structures and inhibition constants (K<sub>i</sub> with thrombin enzyme in a data set of (<em>R</em>)-3-amidinophenylalanine inhibitors), we developed a quantitative structure-activity relationship (QSAR) modeling from a group of 60 (<em>R</em>)-3- amidinophenylalanine inhibitors.</p> <p><strong>Methods</strong>: A database containing chemical structures of 60 inhibitors and their Ki values was put into molecular operating environment (MOE) 2008.10 software, and the two-dimensional (2D) physicochemical descriptors were numerically calculated. After removing the irrelevant descriptors, a QSAR modeling was developed from the 2D-descriptors and K<sub>i</sub> values by using the partial least squares (PLS) regression method.</p> <p><strong>Results</strong>: The results showed that the hydrophobic property, reflected through <em>n</em>-octanol/water partition coefficient (P) of a drug molecule, contributes mainly to K<sub>i</sub> values with thrombin.The statistic parameters that give the information about the goodness of fit of a 2D-QSAR model (such as squared correlation coefficient of R2 = 0.791, root mean square error (RMSE) = 0.443, cross-validated Q2 cv = 0.762, and cross-validated RMSEcv = 0.473) were statistically obtained for a training set (60 inhibitors). The R2 and RMSE values were obtained by using a developed model for the testing set (9 inhibitors) ; the total set has statistically significant parameters. Furthermore, the 2D-QSAR modeling was also applied to predict the K<sub>i</sub> values of the 69 inhibitors. A linear relationship was found between the experimental and predicted pK<sub>i</sub> values of the inhibitors.</p> <p><strong>Conclusion</strong>: The results support the promising application of established 2D-QSAR modeling in the prediction and design of new (<em>R</em>)-3-amidinophenylalanine candidates in the pharmaceutical industry.</p> <p>&nbsp;</p> Hien Van Nguyen Van Thi Bich Pham Hao Minh Hoang ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2019-10-15 2019-10-15 22 3 10.32508/stdj.v22i3.1684 title description none g Triterpenoid Glycosides from Olax imbricata http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1660 <p><strong>Introduction</strong>:<em> Olax imbricata</em>, owning antibacterial, antioxidant, and anti-inflammatory activities, has been investigated as one of traditional diabetic plants in Vietnam. In our previous publications on <em>Olax imbricata</em>, the structure analysis of the isolated compounds were reported, including two phenolic compounds, three phenolic glycosidic compounds, a sesquiterpenoid tropolone and 1,2,3,4-tetrahydronaphthalene derivatives. This article described the isolation and structure elucidation of three triterpenoid glycosides isolated from the methanol extract of Olax imbricata growing in Phu Yen province. Additionally, the evaluation of inhibitory activity for a-glucosidase was performed on a pure compound.</p> <p><strong>Method</strong>: The methanol extract of this plant applied the chromatographic techniques, including thin-layer chromatography and silica gel column chromatography, led to the isolation of three pure compounds. The structures of three isolated compounds were elucidated by the spectroscopic data, including 1D and 2D NMR spectra in a combination of HRESIMS, and the sugar moieties were elucidated by acid hydrolysis. The a-glucosidase inhibitory assay was applied to a pure compound by the colorimetric method.</p> <p><strong>Results</strong>: Three triterpenoid glycosides, namely 3-O-a-L-rhamnopyranosyl-(1-&gt;4)-b -D-glucopyranosyl-(1-&gt;3)-6′- O-ethyl-b -Dglucuronyl oleanolic acid (<strong>1</strong>), oleanolic acid 28-O-b -D-glucopyranoside (<strong>2</strong>) and spergulacin (<strong>3</strong>) were isolated and elucidated. The compound <strong>2</strong> showed its strong potentiala-glucosidase inhibitory activity with the IC<sub>50</sub> value of 56.15+/-1.31 mM.</p> <p><strong>Conclusion</strong>: Among them, compound 1 is a new one, the compounds <strong>2</strong> and <strong>3</strong> were isolated for the first time from the genus Olax. The compound 2 exhibited the potential a-glucosidase inhibition activity, contributing to demonstrating the diabetes treatment ability of <em>Olax imbricata</em> in the folklore.</p> <p>&nbsp;</p> Nga Thi Vo Suong Thi Minh Huynh Huong Thi My Nguyen Huy Thuc Duong Phung Kim Phi Nguyen ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2019-09-02 2019-09-02 22 3 324 334 10.32508/stdj.v22i3.1660 title description none g Evaluating the applicability of a low-cost sensor for measuring PM2.5 concentration in Ho Chi Minh city, Viet Nam http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1688 <p><strong>Introduction</strong>: Continuous monitoring provides real-time data which is helpful for measuring air quality; however, these systems are often very expensive, especially for developing countries such as Vietnam. The use of low-cost sensors for monitoring air pollution is a new approach in Vietnam and this study assesses the utility of low-cost, light-scattering-based, particulate sensors for measuring PM<sub>2.5</sub> concentrations in Ho Chi Minh City.</p> <p><strong>Methods</strong>: The low-cost sensors were compared with both a Beta attenuation monitor (BAM) reference method and a gravimetric method during the rainy season period of October to December 2018.</p> <p><strong>Results</strong>: The results showed that there was a very strong correlation between two low-cost sensors (R = 0.97, slope = 1.0), and that the sensor precision varied from 0 to 21.4% with a mean of 3.1%. Both one-minute averaged data and one-hour averaged data showed similar correlations between sensors and BAM (R<sup>2</sup> = 0.62 and 0.69, respectively), while 24-hour averaged data showed excellent agreement (R<sup>2</sup> = 0.95, slope = 1.05). In addition, we also found a strong correlation between those instruments and a gravimetric method using 24-hour averaged data. A linear regression was used to calibrate the 24-hour averaged sensor data and, once calibrated, the bias dropped to zero.</p> <p><strong>Conclusion</strong>: These results show that low-cost sensors can be used for daily measurements of PM<sub>2.5</sub> concentrations in Ho Chi Minh City. The effect of air conditions, such as temperature and humidity, should be conducted. Moreover, technical methods to improve time resolution of lowcost sensors need to be developed and applied in order to provide real-time measurements at an inexpensive cost.</p> <p>&nbsp;</p> Chi Doan Thien Nguyen Hien Thi To ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2019-09-30 2019-09-30 22 3 343 347 10.32508/stdj.v22i3.1688 title description none g