http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/issue/feedScience & Technology Development Journal: Natural Sciences2024-01-21T07:11:41+07:00Phuc Van Phampvphuc@vnuhcm.edu.vnOpen Journal Systemshttp://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/1286Electrochemical sensor for detection of uric acid using screen-printed electrodes modified with NiO/PANI-Graphene2024-01-20T16:02:59+07:00http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_1286_cover_en_US.pngNgan Thi Kim Nguyennganvk490@gmail.comY Ngoc Thi Dangdangthingocy8399@gmail.comAnh Hoang Nguyennhanh@hcmus.edu.vnMan Van Trantvman@hcmus.edu.vnHai Viet Lelvhai@hcmus.edu.vn<p>Uric acid (UA) is a product of the catabolism of purine bases (adenine and guanidine) of nucleic acids that occurs naturally in the human body. The analysis of UA plays an important role in diagnosing and treating diseases such as gout, kidney stones, diabetes, heart disease, and Lesch-Nyhan syndrome. UA is analysed in the laboratory by the enzymatic colorimetric method with a time consuming of approximately one hour. Currently, electrochemical sensors are considered as a potential approach in the rapid quantification of UA due to the advantages of rapid analysis, low cost, few samples required for analysis, compact design and easy to use and do not require highly skilled technicians like traditional analytical methods. In this study, a commercial printed electrode (SPE) was surface-modified with a polyaniline-graphene (PANI-Graphene) composite coating and functionalize the surface of a PANI-Graphene film with a NiO electrochemical catalyst by cyclic voltammetry (CV) method. The fabricated electrode (designated NiO/PANI-Graphene/SPE) was used for UA analysis in a simulated human fluid medium (PBS, pH 7.4). The results show that the NiO/PANI-Graphene/SPE sensor electrode has good electrocatalytic activity for the oxidation of UA in the potential range of 0.3 to 0.5 V. Characteristically, the sensor has a wide linear range in the concentration range of 10 to 1750 μM with a high sensitivity of 29.5 μA mM<sup>-1</sup> cm<sup>-2</sup> and a low detection limit of 5.00 μM (S/N = 3). The NiO/PANI-Graphene/SPE sensor electrode has potential applications in the development of non-enzymatic electrochemical sensors for the rapid quantification of UA content in human body fluids.</p>2023-12-31T00:00:00+07:00##submission.copyrightStatement##http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/1294Conversion of fructose to 5-hydroxymethylfurfural using 1,4-bis(4-sulfobutyl)-DABCO-1,4-diium tetrachloroaluminate ionic liquid in [CholineCl][Citric acid] deep eutectic solvent2024-01-20T19:01:56+07:00http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_1294_cover_en_US.pngNguyễn Hào Trìnhnguyenhaotrinh@gmail.comNguyễn Minh Nhậtnnhat1604@gmail.comNguyễn Phước Thiệnnguyenphuocthien2100@gmail.comPhan Bích Hàphanbichha261077@gmail.comPhuong Hoang Tranthphuong@hcmus.edu.vn<p>In recent years, there has been a significant interest from both domestic and international researchers in ionic liquids as they are recognized as environmentally friendly solvents and catalysts. From 5-hydroxymethylfurfural (HMF), a substrate derived from carbohydrate, various important compounds particularly the 2,5-dimethylfuran can be synthesized because it could be used as a biofuel and valuable substance. Furan derivatives such as 5-alkoxymethylfurfural, 2,5-furandicarboxylic acid, 5-hydroxymethylfuroic acid, bis-hydroxymethylfuran and 2,5-dimethylfuran have significant applications in the fields of fuel and polymers. This paper presented the preparation of 8 ionic liquids containing Brønsted acid and Lewis acid site, intending to utilize them as catalysts for converting carbohydrates into 5-hydroxymethylfurfural (HMF). Several factors affecting the performance of HMF were investigated, including the type and catalyst loading, temperature, solvent, and reused. The results showed that 1,4-bis(4-sulfobutyl)-DABCO-1,4-diium tetrachloroaluminate (IL1) exhibited potential as a catalyst for the synthesis of HMF from fructose. This reaction was conducted at a temperature of 100℃ for 5 min with the yield of approximately 60% when using [CholineCl][Citric acid] deep eutectic solvent. This catalyst, IL1/[CholineCl][Citric acid], was successfully recovered and reused for four times. This demonstrated the efficacy of various ionic liquids as catalysts for the synthesis of HMF from fructose. Further study on this catalyst is needed for the application in the producing fuel precursors derived from carbohydrates on an larger scale.</p>2023-12-31T00:00:00+07:00##submission.copyrightStatement##http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/1279A syntax‒aware deep‒learning model for biomedical semantic role labelling2024-01-20T19:28:03+07:00http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_1279_cover_en_US.pngHoai Duc Tuan Nguyentnhduc@fit.hcmus.edu.vnTruong Duong Luuluutruongduong20@gmail.comQuoc Duy Huynhhqd1902@gmail.com<p>A deep learning model for biomedical semantic role labeling was build. Semantic role labeling is a useful task that enables the computer to comprehend the key facts expressed in each sentence, and is a necessary first step in the resolution of several other semantic-related tasks, such as event extraction, entity extraction, and Q-A systems... Semantic role labeling is a domain-dependent task. In the biomedical field, semantics are transmitted via more intricate grammatical structures and dependencies in addition to being built on a predicate argument frameset that differs greatly from that of the general domain. To effectively account for these unique characteristics, three types of information were integrated into this deep learning model: Context knowledge obtained from a pre-trained language model trained on a substantial corpus of biomedical texts, dependencies derived from the dependency parse trees and sentence structure obtained from constituency parse trees. To handle grammatical information that is naturally represented as graphs, the Graph Attention Network which is well-known for its remarkable graph learning capabilities, was used. To further boost the model effectiveness, predicate indicator embedding was additionally included in the proposed model. According to experimental findings, the two above-indicated forms of syntactic information along with the predicate indicator embedding, could boost F1 by up to 20%.</p>2023-12-31T00:00:00+07:00##submission.copyrightStatement##http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/1306Study the effects on the phonon drag Seebeck coefficient of bilayer graphene and bilayer graphene−bilayer graphene double layers2024-01-20T20:47:17+07:00http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_1306_cover_en_US.pngTruong Van Tuantruongtuanphysics@gmail.comNguyen Quoc Khanhnqkhanh@hcmus.edu.vn<p>This paper presented the investigation of the influence of the temperature−dependent screening effect on the Seebeck phonon drag coefficient Sg of a monolayer of bilayer graphene (BLG) and a BLG−BLG double layer placed in an air environment. For a system in an air environment, the two-dimensional electrons of the BLG was assumed to interact only with the intralayer deformation acoustic potential phonons in the BLG. After reviewing the results published by Kubakaddi and Bhargavi, “Enhancement of phonon-drag thermopower in bilayer graphene” in Phys. Rev. B 82, 155410 (2010), this paper expanded the mentioned-results to encompass the screening and double layers and found that the phonon drag coefficient in the BLG monolayer system was strongly reduced by the screening effect, even up to several orders of magnitude compared to the zero temperature screening function, as shown in some recent publications. When comparing the effect of electron screening in the second layer on electron-phonon interaction in the remaining layer, or on the intralayer screening function, the distance between the two layers was small. The screening effect of the second layer significantly reduced the magnitude of the phonon drag Seebeck coefficient Sg in the BLG-BLG double layer. The effect of temperature, layer spacing and particle density on S<sup>g</sup> for symmetric and asymmetric systems with varying layer densities were also investigated.</p>2023-12-31T00:00:00+07:00##submission.copyrightStatement##http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/1276Chemical constituents from aerial parts of Mussaenda saigonensis2024-01-21T04:27:05+07:00http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_1276_cover_en_US.pngMinh Nhat Phanpnhatminh@gmail.comPhat Tan Nguyenntphat@ict.vast.vnKhiem Huy Trancongcan20032000@yahoo.comDat Trong Buitrongdat2005@yahoo.comHau Van Tanhautanvan120@gmail.comSon Van Dangdvsonitb@yahoo.com.vnTri Dinh Maimaidinhtri@gmail.com<p>The genus Mussaenda, belonging to the family Rubiaceae, comprising approximately 160 species, widely distributed in tropical and subtropical regions including Africa, Asia and Southeast Asia. 27 species were found in Viet Nam and several of them are used in folk medicine. An extensive survey of literature on phytochemicals and biological activities of Mussaenda indicated that most of the studies were on M. pubescens, M. macrophylla, M. frondosa, M. hirsutissima, M. arcuata. There are no reports on the chemical and biological data of the Mussaenda saigonensis. This paper reported the results of the isolation of some compounds from aerial parts of M. saigonensis. The dried powder of M. saigonensis aerial parts was exhaustively extracted with ethanol at room temperature to give the crude extract after evaporation of the solvent. This extract was applied to liquid‒liquid partition procedure and successively afford different polar extracts. Compound isolation was performed using column chromatography on silica gel. Chemical structures were elucidated by 1D, 2D-NMR, MS spectra and compared with the literature published data. Six compounds were isolated, including two triterpenoids, 2,3-dihydroxyurs-12-en-28-oic acid (1), 3,23-dihydroxyurs-12-en-28-oic acid (2), two phenolics, coumaric acid (3), caffeic acid (4) and two anthraquinones, aloe-emodin (5) and 11-O--rhamnopyranosylaloe-emodin (6). All compounds were the first reported for Mussaenda saigonensis.</p>2023-12-31T00:00:00+07:00##submission.copyrightStatement##http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/1251Study on chemical constituents of the ethyl acetate extract of Elephantopus mollis2024-01-21T05:16:50+07:00http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_1251_cover_en_US.pngLe Nguyen Loccocale1995@gmail.comDang Thi Phuong Thaothaodp@hcmus.edu.vnNguyen Thi Y Nhintynhi@hcmus.edu.vnTran Le Quantlquan@hcmus.edu.vn<p><em>Elephantopus mollis, </em>family Asteraceae, is a herbaceous perennial plant with the main component of sesquiterpene lactones. In the<em> Elephantopus mollis, </em>there are other chemical components such as triterpenoids, steroids, flavonoids, and simple phenolic compounds. Since this plant was discovered and studied until now, there have been many studies on the biological activity of <em>Elephantopus mollis</em>, in which the cytotoxic activity was noted to be superior to many cell lines such as breast cancer cell lines (MCF-7; T-47D), lung cancer cell lines (A549; NCI-H2), leukemia cell line (HL-60), lymphoma cell line (RAJI)… The cytotoxic studies were performed mainly on petroleum ether, ethyl acetate, methanol, and water extracts. In Vietnam, <em>Elephantopus mollis</em> distributed mainly in the central highlands and are used in the traditional medicine to treat toxic boils, skin diseases, acute lymphadenitis, acute jaundice… In this paper, six compounds were isolated from an ethyl acetate extract of the whole plant, including two known sesquiterpene lactones, molephantinin (<strong>1</strong>), 2-deethoxy-2β-methoxyphantomolin (<strong>2</strong>) and four other compounds including a simple phenolic, methyl 4-hydroxybenzoate (<strong>3</strong>); a triterpene, epifridelanol (<strong>4</strong>), a phytosterol, stigmasterol (<strong>5</strong>), and a biflavonoid, lophirone L (<strong>6</strong>). Among them, compound<strong> 6 </strong>was found for the first time in<em> Elephantopus mollis </em>species. The chemical structure of the isolated compounds were elucidated by spectroscopic analysis <sup>1</sup>H- NMR, <sup>13</sup>C-NMR, HSQC, HMBC and HR-ESI-MS, combining with the comparison of their NMR data with those published in the literature.</p>2023-12-31T00:00:00+07:00##submission.copyrightStatement##http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/1258Preparation of carbon black masterbatch from natural rubber latex2024-01-21T06:51:39+07:00http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_1258_cover_en_US.pngChi Le Pham Thiptlchi@hcmus.edu.vnNguyen Ngoc Annnan@hcmus.edu.vn<p>Carbon Black Masterbatch containing high carbon black content (60% by weight) was made from carbon black and a low viscosity natural rubber latex without the application of other chemical agents as well as coagulating agents. The slurry compound, after natural coagulation, was dried at 70℃ in 24h, followed by sheet shaping for next step. The Carbon Black Masterbatch was used for rubber compounding (containing 35 phr of carbon black) with natural rubber by two roll mill-mixing, and then vulcanized. Simultaneously, the reference sample was also fabricated from block natural rubber and carbon black in same compounding condition. This sample was made by directly mixing a dry natural rubber with carbon black at the same content of 35 phr of carbon black. The samples were then investigated for various characterizations for the comparison of some criteria: carbon black dispersion, vulcanization rheometer and mechanical properties (tensile strength and tear strength). The rubber sample, prepared from the masterbatch, showed the carbon black dispersion better than the ones fabricated by direct mixing method. This could be explained by the fact that carbon black was dispersed once time in Carbon Black Masterbatch. The masterbatch samples had the better properties: the curing time was shorter and the maximum torque (MH) was higher than the other sample, thank for good carbon black dispersion in the masterbatch samples. Similar results were also observed in the tensile strength and tear strength tests: samples fabricated from masterbatch possessed higher values of tensile and tear strength about 8.5% and 4.6%, respectively compared with the other sample.</p>2023-12-31T00:00:00+07:00##submission.copyrightStatement##http://stdjns.scienceandtechnology.com.vn/index.php/stdjns/article/view/1269One–dimensional magnetotelluric inversion by modified differential evolution algorithm2024-01-21T07:11:41+07:00http://stdjns.scienceandtechnology.com.vn/public/journals/2/article_1269_cover_en_US.pngHung Luuhungluu@hcmute.edu.vn<p>Traditional methods of solving geophysical inverse problems often used an initial structural model and an iterative process to find solutions. During each iteration, the model was linearized and updated, then the error between the model's response and the observed data were calculated and minimized. The inverse results solved by this method were often strongly dependent on the initial model choice, and the minimum of the objective function found could be the local value but not the global minimum. Global search methods such as genetic algorithm (GA) overcame these limitations of traditional solutions. This paper presented the application of modified differential evolution (MDE) algorithm which was developed from the genetic algorithm, to one-dimension (1D) magnetotelluric inversion. The algorithm had been used to invert two 3-layer geoelectrical models. The results showed that when using a 3-layer model for inversion, the obtained parameters of the subsurface almost coincided with those of the theoretical models. In the case the number of layers used for inversion had more than three layers (four layers and five layers), the obtained results showed that there was still a good agreement between the inverted structure and the theoretical model. Therefore, the algorithm was applied to one-dimensional (1D) inversion for data of one magnetotelluric station measured at Cu Chi district, Ho Chi Minh city. The results showed that the subsurface structure down to a depth of 16 km consisted of 3 layers: the top layer had a resistivity of 119 Ω.m with a thickness of about 760 m, the middle resistive layer with a resistivity of 4353 Ω.m with about 10 km thickness, and the lower half-space with a relatively low resistivity of 41.4 Ω.m. This result was consistent with the geoelectric structure information obtained from other magnetotelluric studies carried out in the studied area, demonstrating the practical applicability of the improved differential evolution algorithm.</p>2023-12-31T00:00:00+07:00##submission.copyrightStatement##