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> Triterpenoids and coumarins from the leaves of Sterculia foetida Linn. <p><strong>Introduction</strong>: Sterculia foetida Linn. is widely distributed in tropical countries. As the continuous study on the hexane and ethyl acetate extracts of Sterculia foetida leaves, the isolation and structural determination of four triterpenoids and two coumarins were addressed.</p> <p><strong>Method</strong>: The crude extract was prepared from dried power of Sterculia foetida leaves by maceration method in ethanol. This extract was then separated by liquid-liquid partition with n-hexane, chloroform, and ethyl acetate, respectively, to obtain the corresponding extracts. The hexane and ethyl acetate extracts were applied to multiple silica gel column chromatography to yield six compounds. Their chemical structures were determined by the NMR data analysis as well as the comparison their spectroscopic data and physical properties with those of reported literature.</p> <p><strong>Results</strong>: Four triterpenoid compounds, including betulinic acid (1), conyzasaponin G (2), taraxerol (3), and taraxer-14-ene- 1a,3b -diol (4), and two coumarins fraxetin (5), and aesculin (6) were identified.</p> <p><strong>Conclusion</strong>: To the best of our knowledge, they have not been reported in the leaves of Sterculia foetida before, and compound 2 was known to present in Sterculia genus for the first time.</p> Pham Nguyen Kim Tuyen Nguyen Thi Quynh Trang Huynh Cong Doan Pham Dinh Thuong Nguyen Trung Duan Tran Doan Duy Cuong Huynh Bui Linh Chi Nguyen Thi Anh Tuyet Nguyen Kim Phi Phung Thu Thi-Hoai Nguyen ##submission.copyrightStatement## 2020-10-25 2020-10-25 23 4 First First 10.32508/stdj.v23i4.2449 title description none g Potential applications of waste lignin from the paper and pulp industry in Viet Nam <p>The conversion of waste lignin from the paper and pulp industry is a potential process to produce chemicals and materials in the industry. With the development and the demand for the pulp and paper industry, the amount of waste lignin will increase remarkably. In Vietnam, the forest tree for the pulp industry is abundant, and the pulp industry has increased in recent years. In parallel, the government planned to develop the material resource and high-tech factories for this industry. In this work, we summarized the pulp and paper industry in Vietnam, then suggest the potential applications of waste lignin in several valuable products.</p> Thanh Khoa Phung Quynh-Thy Song Nguyen Khanh B. Vu Giang Duy-Le Vo Vinh Ngoc Nguyen ##submission.copyrightStatement## 2020-10-09 2020-10-09 23 4 716 726 10.32508/stdj.v23i4.2442 title description none g On the calm b-differentiability of projector onto circular cone and its applications <p>In this paper, we study a concept on the calm B-differentiability, a new kind of generalized differentiabilities for a given vector function introduced by Ye and Zhou in 2017, of the projector onto the circular cone. Then, we discuss its applications in mathematical programming problems with circular cone complementarity constraints. Here, this problem can be considered to be a generalization of mathematical programming problems with second-order cone complementarity constraints, and thus it includes a large class of mathematical models in optimization theory. Consequently, the obtained results for this problem are generalized, and then corresponding results for some special mathematical problems can be implied from them directly. For more detailed information, we will first prove the calmly B-differentiable property of the projector onto the circular cone. This result is not easy to be shown by simply resorting to those of the projection operator onto the second-order cone. By virtue of exploiting variational techniques, we next establish the exact formula for the regular (Fréchet) normal cone (this concept was proposed by Kruger and Mordukhovich in 1980) to the circular cone complementarity set. Note that this set can be considered to be a generalization of the second-order cone complementarity set. In finally, the exact formula for the regular (Fréchet) normal cone to the circular cone complementarity set would be useful for us to study first-order necessary optimality conditions for mathematical programming problems with circular cone complementarity constraints. Our obtained results in the paper are new, and they are generalized to some existing ones in the literature.</p> Vo Duc Thinh ##submission.copyrightStatement## 2020-10-10 2020-10-10 23 4 727 736 10.32508/stdj.v23i4.2426 title description none g Photocatalytic activity enhancement for removal of dye molecules based on plasmonic Ag grafted TiO2 nanocubes under visible light driven <p><strong>Introduction</strong>: Finding a novel photocatalyst for photocatalytic degradation operating in the wavelength range from UV to visible light has been considered a great potential for environmental remediation. Herein, TiO<sub>2</sub> nanocubics (NCs) decorated Ag nanoparticles (NPs) with various concentrations were developed.</p> <p><strong>Methods</strong>: The crystal structure, morphological and chemical characteristics of prepared photocatalysts were thoroughly analyzed by a series of main analyses (X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and UVVis spectra).</p> <p><strong>Results</strong>: The results revealed that a significantly promoting visible-light photocatalytic behavior of TiO<sub>2</sub>NCs@Ag photocatalyst was observed. The photocatalytic methyl orange (MO) degradation of the as-synthesized Ag anchored TiO<sub>2</sub>NCs photocatalyst (85% and 62% under UV light and visible light, respectively) exhibited outstanding photocatalytic efficacy compared with pristine TiO<sub>2</sub> NCs. The achieved results could be assigned to the synergistic effects between TiO<sub>2</sub>NCs and Ag- NPs, leading to enhanced charge carrier separation and improved absorption ability in visible-light response.</p> <p><strong>Conclusion</strong>: This work facilitates designing and developing high-efficiency heterostructure photocatalysts for practical works related to environmental deterioration.</p> Ton Nu Quynh Trang Le Thi Ngoc Tu Tran Van Man Vu Thi Hanh Thu ##submission.copyrightStatement## 2020-11-08 2020-11-08 23 4 743 751 10.32508/stdj.v23i4.2455 title description none g Comparing atmospheric trace element accumulation of three moss species <p><strong>Introduction</strong>: The intention of Vietnam to participate in the European-Asian Moss Survey in the framework of The United Nations Economic Commission for Europe - International Cooperative Programme on effects of air pollution on natural vegetation and crops (UNECE ICP Vegetation) necessitates choosing appropriate moss species that grow in the tropical and subtropical climate of Vietnam. The three selected moss species, divided into phytogeographical elements, were as follows: <em>Leucobryum (aduncum, albidum), Hypnum commutatum</em> and <em>Barbula indica</em>.</p> <p><strong>Methods</strong>: The present study focuses on Central Vietnam where 18 samples of the three above moss species were collected in the vicinity of Dalat and Hue cities. Elements in the moss samples were detected by neutron activation analysis (NAA) at the IBR-2 reactor of the Division of Neutron Activation Analysis, Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research in Dubna, Russia.</p> <p><strong>Results</strong>: The analytical results for twenty-three trace elements, which were used to study elemental accumulation abilities of the three moss species in the air, were Na, Mg, Al, Cl, K, Ca, Ti, V, Mn, Fe, Co, Zn, As, Br, Rb, Sr, Sb, I, Cs, Ba, La, Th, and U. The accumulation abilities were found to decrease in the following order: <em>Leucobryum &gt; Hypnum &gt; Barbula</em>. However, Leucobryum, because of its short stem, was not judged to be a suitable candidate for biomonitoring.</p> <p><strong>Conclusion</strong>: The element accumulation abilities of <em>Hypnum</em> moss were better than those for <em>Barbula</em>, but both were comparable and could be used as indicators for air deposition monitoring; however, <em>Hypnum</em> was not widely present in Vietnam. Thus, <em>Barbula indica</em> moss could be used for performance of atmospheric deposition monitoring in Vietnam.</p> Doan Phan Thao Tien Le Hong Khiem Trinh Thi Thu Trinh Marina Vladimir Frontasyeva Nguyen Thi Minh Sang Son An Nguyen ##submission.copyrightStatement## 2020-11-08 2020-11-08 23 4 752 757 10.32508/stdj.v23i4.2417 title description none g Global research trends in coronavirus disease 2019 <p><strong>Introduction</strong>: The outbreak of the novel coronavirus disease 2019 (COVID-19) is an ongoing global epidemic incident. The present study aims to bibliometrically analyze the global research trends of scientific papers related to COVID-19 with regard to the number of publications, subject categories, and prolific countries. A total of 47,061 publications, published during the last seven months, were collected and analyzed in this study.</p> <p><strong>Methods</strong>: The bibliometric data in this study, which was extracted from the LitCovid Hub from January 17 to July 31, 2020.</p> <p><strong>Results</strong>: Our results indicate that the number of publications on COVID-19 has increased significantly from January to July 2020, along with the rapid spread of the infection. China has produced the largest number of research papers on COVID-19 (5,751 articles, accounting for 12.2%), followed by the USA (2,005 publications, accounting for 4.3%) and Italy (1,374 publications, accounting for 2.9%). Most recent research papers have focused on prevention, treatment, and diagnosis. Our results reveal that although the most affected countries are the USA, Brazil, India, and many countries in Europe, their contribution to research about COVID-19 has been limited.</p> <p><strong>Conclusion</strong>: More research in the field of prevention, diagnosis, and treatment from highly affected countries is recommended. Overall, this study not only provides a global status update on COVID-19 scientific literature but also contributes to future research.</p> Thai Thanh Tran Luu Thanh Pham ##submission.copyrightStatement## 2020-10-10 2020-10-10 23 4 737 742 10.32508/stdj.v23i4.2432 title description none g