Pub Date : 2024-05-10DOI: 10.15625/2525-2518/19478
Thi Thuy Huong Ngo, Thi Thanh Thao Nguyen
Dioxins (PCDD/Fs) are well-known toxic organic pollutants that accumulate in the environment and the food chain, imposing a risk to human health and the ecosystem. Due to the use of dioxin-contaminated herbicides during the US-Vietnam War, there are several hotspots in Vietnam with very high levels of dioxins. Phytoremediation has been increasingly developed in recent decades because of its low cost and environmental-friendly aspect. Vetiver grass is a plant that can remediate both organic and inorganic agents. In this study, the uptake and translocation of dioxins in Vetiver grass (Chrysopogon zizanioides) from the dioxin-contaminated soil was investigated in a field experiment on the Bien Hoa airbase, Vietnam. An experimental area was divided into six plots, of which three were planted with Vetiver grass and three served as control plots, with the initial dioxin concentrations as following: FC2>FC3>FC1>FT2>FT3>FT1. Vetiver grass had grown well on the dioxin-contaminated soils, yielding high biomass and the level of dioxins in the roots of vetiver grass was positively correlated (r2 = 0.67; p<0.01) with its growth rate. During the first year of cultivation, Vetiver grass had the greatest capacity to efficiently accumulate dioxin. Accumulation occurs in the roots, with BAF>1 throughout the entire experiment period for FT3, and in the first year for FT1 and FT2. The dioxin translocation from the roots to the shoots was significantly lower than the BAF and less than one (TF<1), with the first and second sampling times having the highest values compared to the others. Dioxin concentrations do not provide a reliable indicator of its bioavailability but numerous other factors, such as physicochemical properties of the soil and microbes. Our study aims to contribute significant insights to capability of Vetiver grass to accumulate and translocate dioxins, hence the arsenal of dioxin remediation. Furthermore, we envisage translating our findings into practical applications in other areas, considering optimized planting techniques, growth conditions, and long-term sustainability.
{"title":"Assessing the bioaccumulation and translocation potential of vetiver grass for dioxins phytoremediation in Bien Hoa airbase, Viet Nam","authors":"Thi Thuy Huong Ngo, Thi Thanh Thao Nguyen","doi":"10.15625/2525-2518/19478","DOIUrl":"https://doi.org/10.15625/2525-2518/19478","url":null,"abstract":"Dioxins (PCDD/Fs) are well-known toxic organic pollutants that accumulate in the environment and the food chain, imposing a risk to human health and the ecosystem. Due to the use of dioxin-contaminated herbicides during the US-Vietnam War, there are several hotspots in Vietnam with very high levels of dioxins. Phytoremediation has been increasingly developed in recent decades because of its low cost and environmental-friendly aspect. Vetiver grass is a plant that can remediate both organic and inorganic agents. In this study, the uptake and translocation of dioxins in Vetiver grass (Chrysopogon zizanioides) from the dioxin-contaminated soil was investigated in a field experiment on the Bien Hoa airbase, Vietnam. An experimental area was divided into six plots, of which three were planted with Vetiver grass and three served as control plots, with the initial dioxin concentrations as following: FC2>FC3>FC1>FT2>FT3>FT1. \u0000Vetiver grass had grown well on the dioxin-contaminated soils, yielding high biomass and the level of dioxins in the roots of vetiver grass was positively correlated (r2 = 0.67; p<0.01) with its growth rate. During the first year of cultivation, Vetiver grass had the greatest capacity to efficiently accumulate dioxin. Accumulation occurs in the roots, with BAF>1 throughout the entire experiment period for FT3, and in the first year for FT1 and FT2. The dioxin translocation from the roots to the shoots was significantly lower than the BAF and less than one (TF<1), with the first and second sampling times having the highest values compared to the others. Dioxin concentrations do not provide a reliable indicator of its bioavailability but numerous other factors, such as physicochemical properties of the soil and microbes. Our study aims to contribute significant insights to capability of Vetiver grass to accumulate and translocate dioxins, hence the arsenal of dioxin remediation. Furthermore, we envisage translating our findings into practical applications in other areas, considering optimized planting techniques, growth conditions, and long-term sustainability.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140990685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.15625/2525-2518/17989
Hoai Linh Nguyen, Kim Chi Ngo, Le Minh Tran, Ngoc Phuong Dang, Xuan Tung Nguyen, Thuy Tien Do, Hong Minh Pham Thi
This study investigates the adsorption potential of AC-GCB biochar, obtained by pyrolyzing green coffee extracted bioactive compounds at 400 ºC, for ammonium removal from groundwater. The biochar's microstructure was characterized using scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and Energy dispersive spectrometry (EDS) Mapping. Optimal adsorption conditions were observed at an initial pH range of 4 to 8, an initial NH4+ concentration of ≤ 25 mg.L-1, and a biochar dose of 10 g.L-1. The ammonium adsorption of AC-GCB was consistent with both Langmuir and Freundlich's adsorption theories (R2 > 0.92). The AC-GCB biochar obtained the maximum adsorption capacity Qm was 14,48 mg.g-1, higher than the control BC-GCB biochar that pyrolysised without bioactive compound extracted with Qm was only 5.41 mg.g-1.
{"title":"Biochar from waste green coffee extracted bioactive compounds as materials for ammonium adsorption","authors":"Hoai Linh Nguyen, Kim Chi Ngo, Le Minh Tran, Ngoc Phuong Dang, Xuan Tung Nguyen, Thuy Tien Do, Hong Minh Pham Thi","doi":"10.15625/2525-2518/17989","DOIUrl":"https://doi.org/10.15625/2525-2518/17989","url":null,"abstract":"This study investigates the adsorption potential of AC-GCB biochar, obtained by pyrolyzing green coffee extracted bioactive compounds at 400 ºC, for ammonium removal from groundwater. The biochar's microstructure was characterized using scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and Energy dispersive spectrometry (EDS) Mapping. Optimal adsorption conditions were observed at an initial pH range of 4 to 8, an initial NH4+ concentration of ≤ 25 mg.L-1, and a biochar dose of 10 g.L-1. The ammonium adsorption of AC-GCB was consistent with both Langmuir and Freundlich's adsorption theories (R2 > 0.92). The AC-GCB biochar obtained the maximum adsorption capacity Qm was 14,48 mg.g-1, higher than the control BC-GCB biochar that pyrolysised without bioactive compound extracted with Qm was only 5.41 mg.g-1.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140083472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.15625/2525-2518/18298
Hieu Ngo, Tuan Anh Hoang Le, Cong Pham
Thirteen compounds, including catechin (1), gallocatechin (2), quercetin (3), myricetin (4), kaempferol 3-O-α-ʟ-arabinofuranoside (5), avicularin (6), guaijaverin (7), quercetin-3-O-β-ᴅ-galactopyranoside (8), quercetin-3-O-β-ᴅ-glucopyranoside (9), quercetin-3-O-β-ᴅ-glucuronide (10), casuarinin (11), ursolic acid (12), and 4-methoxy-3,5-dihydroxybenzoic acid (13) were isolated from the leaves of Psidium guajava. The structures of these compounds were elucidated by modern spectroscopic methods (MS, 1H/13C-NMR) and compared with those reported data. Additionally, all isolated compounds were evaluated for their inhibitory effects on NO production. Among them, compounds 3, 8, 10, and 11 showed inhibitory effects on NO production within IC50 values of 19.30 – 42.86 µM. Compound 13 was firstly isolated from Psidium guajava.
从番石榴叶中分离出了槲皮素-3-O-β-ᴅ-吡喃葡萄糖苷（9）、槲皮素-3-O-β-ᴅ-葡萄糖醛酸苷（10）、番荔枝素（11）、熊果酸（12）和 4-甲氧基-3,5-二羟基苯甲酸（13）。通过现代光谱方法（质谱、1H/13C-NMR）阐明了这些化合物的结构，并与已报道的数据进行了比较。此外，还评估了所有分离化合物对 NO 生成的抑制作用。其中，化合物 3、8、10 和 11 对 NO 生成具有抑制作用，IC50 值在 19.30 - 42.86 µM 之间。化合物 13 首先是从番石榴中分离出来的。
{"title":"ISOLATION, CHARACTERIZATION, AND NITRIC OXIDE PRODUCTION INHIBITORY ACTIVITIES OF THE METABOLITES FROM PSIDIUM GUAJAVA L.","authors":"Hieu Ngo, Tuan Anh Hoang Le, Cong Pham","doi":"10.15625/2525-2518/18298","DOIUrl":"https://doi.org/10.15625/2525-2518/18298","url":null,"abstract":"Thirteen compounds, including catechin (1), gallocatechin (2), quercetin (3), myricetin (4), kaempferol 3-O-α-ʟ-arabinofuranoside (5), avicularin (6), guaijaverin (7), quercetin-3-O-β-ᴅ-galactopyranoside (8), quercetin-3-O-β-ᴅ-glucopyranoside (9), quercetin-3-O-β-ᴅ-glucuronide (10), casuarinin (11), ursolic acid (12), and 4-methoxy-3,5-dihydroxybenzoic acid (13) were isolated from the leaves of Psidium guajava. The structures of these compounds were elucidated by modern spectroscopic methods (MS, 1H/13C-NMR) and compared with those reported data. Additionally, all isolated compounds were evaluated for their inhibitory effects on NO production. Among them, compounds 3, 8, 10, and 11 showed inhibitory effects on NO production within IC50 values of 19.30 – 42.86 µM. Compound 13 was firstly isolated from Psidium guajava.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140086917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.15625/2525-2518/17140
Van Thinh Pham, Thi Bach Tuyet Dao, Thi Kim Ngan Tran, Ngoc Quyen Tran, Long Giang Bach
Ni-doped BiVO4 photocatalysts were successfully synthesized by hydrothermal method. The catalytic samples were characterized by scanning electron microscopy (SEM), UV-vis diffuse reflection spectroscopy (DRS), photoluminescence spectroscopy (PL) and X-ray diffraction (XRD). Based on the results of PL spectrum analysis, the electron-hole recombination phenomenon is limited by the presence of the second metal Ni in the structure at Bi3+ positions. The catalyst materials at the Ni doping ratios all have the monoclinic-scheelite BiVO4 structure as shown by the XRD and Raman methods. The photocatalytic ability of methyl blue (MB) on the Ni/BiVO4 catalyst was studied under visible light irradiation in order to contribute to reducing the current environmental pollution problem. The removal efficiency of MB varies with the doping ratio of Ni/BiVO4, reaching the highest decomposition efficiency of 84.77% in the 5% mol Ni sample, which is 30% higher than that of the BiVO4 sample. The BiVO4 material modified with Ni gives a high photocatalytic efficiency of organic pigment decomposition under visible light indicates the potential improvement in the efficiency of a material for existing applications and exploit many new applications in the future.
采用水热法成功合成了掺镍 BiVO4 光催化剂。通过扫描电子显微镜（SEM）、紫外-可见漫反射光谱（DRS）、光致发光光谱（PL）和 X 射线衍射（XRD）对催化样品进行了表征。根据光致发光光谱分析结果，电子-空穴重组现象受限于结构中 Bi3+ 位置第二金属 Ni 的存在。XRD 和拉曼方法显示，不同掺杂比例的催化剂材料均具有单斜闪长石 BiVO4 结构。在可见光照射下，研究了 Ni/BiVO4 催化剂对甲基蓝（MB）的光催化能力，以期为减少当前的环境污染问题做出贡献。甲基蓝的去除率随 Ni/BiVO4 的掺杂率而变化，5% mol Ni 样品的分解效率最高，达到 84.77%，比 BiVO4 样品的分解效率高 30%。用镍修饰的 BiVO4 材料在可见光下具有很高的光催化分解有机颜料的效率，这表明该材料在现有应用中的效率有可能得到提高，并在未来开发出许多新的应用。
{"title":"SYNTHESIS OF NICKEL-DOPED BIVO4 MATERIALS BY HYDROTHERMAL METHOD AND EVALUATE THE PHOTOCATALYTIC ABILITY TO DECOMPOSE METHYLENE BLUE UNDER VISIBLE LIGHT","authors":"Van Thinh Pham, Thi Bach Tuyet Dao, Thi Kim Ngan Tran, Ngoc Quyen Tran, Long Giang Bach","doi":"10.15625/2525-2518/17140","DOIUrl":"https://doi.org/10.15625/2525-2518/17140","url":null,"abstract":"Ni-doped BiVO4 photocatalysts were successfully synthesized by hydrothermal method. The catalytic samples were characterized by scanning electron microscopy (SEM), UV-vis diffuse reflection spectroscopy (DRS), photoluminescence spectroscopy (PL) and X-ray diffraction (XRD). Based on the results of PL spectrum analysis, the electron-hole recombination phenomenon is limited by the presence of the second metal Ni in the structure at Bi3+ positions. The catalyst materials at the Ni doping ratios all have the monoclinic-scheelite BiVO4 structure as shown by the XRD and Raman methods. The photocatalytic ability of methyl blue (MB) on the Ni/BiVO4 catalyst was studied under visible light irradiation in order to contribute to reducing the current environmental pollution problem. The removal efficiency of MB varies with the doping ratio of Ni/BiVO4, reaching the highest decomposition efficiency of 84.77% in the 5% mol Ni sample, which is 30% higher than that of the BiVO4 sample. The BiVO4 material modified with Ni gives a high photocatalytic efficiency of organic pigment decomposition under visible light indicates the potential improvement in the efficiency of a material for existing applications and exploit many new applications in the future.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140090220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.15625/2525-2518/18250
Dũng Võ Tiến
This article presents the modeling of overcurrent and differential relays in MATLAB/Simulink. The overcurrent relay has the features of instantaneous, time-definite, and inverse definite minimum time (IDMT) characteristics according to IEC 60255 and IEEE C37.112-1996 standards. The 220 kV km transmission systems are selected as examples for fault simulation and relay testing for each relay model and the coordination protection. The simulation results are given and a description of how this case study can be used to compare protection schemes.
{"title":"MODELING OF RELAY PROTECTION OF ELECTRIC POWER SYSTEM USING MATLAB/SIMULINK","authors":"Dũng Võ Tiến","doi":"10.15625/2525-2518/18250","DOIUrl":"https://doi.org/10.15625/2525-2518/18250","url":null,"abstract":"This article presents the modeling of overcurrent and differential relays in MATLAB/Simulink. The overcurrent relay has the features of instantaneous, time-definite, and inverse definite minimum time (IDMT) characteristics according to IEC 60255 and IEEE C37.112-1996 standards. The 220 kV km transmission systems are selected as examples for fault simulation and relay testing for each relay model and the coordination protection. The simulation results are given and a description of how this case study can be used to compare protection schemes.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140085988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.15625/2525-2518/18373
Thuy Bich Ly, Le-Ha T. Vo, Dieu Anh Van, Thu Hien Nguyen, Duy Nam Dao, Trung-Dung Nghiem, Quoc Dat Nguyen
High levels of fine (PM2.5) and ultrafine (PM0.1) particles in the atmosphere can cause adverse effects on the environment and human health. This study aims at determining the mass concentrations of PM and health risks on pollution event days (episodes) in Hanoi. Semi-daily samples (daytime and night-time) of PM2.5 and PM0.1 were collected at Hanoi University of Science and Technology, in December 2021. The daily PM2.5 concentrations were in the range of 42 – 204 µg/m3 (average of 123 µg/m3). Those of PM0.1 varied from 9 to 30 µg/m3 (average of 22 µg/m3). There is negligible change on daytime and night-time PM0.1 concentrations, whereas those levels of PM2.5 were remarkably different. PM2.5 daytime concentrations were in the range of 39 – 205 µg/m3 with an average of 107 µg/m3. The level ranges of night-time were slightly wider which varied from 39 to 230 µg/m3 (average of 132 µg/m3). A prolonged episode of PM2.5 (which is defined by the criterion of PM2.5 > 50 µg/m3) was found with an intensity of 26 days in December. During the pollution episode, the Monte Carlo simulation showed that respirable doses were the highest for the adult (above 21 years) for chronic effects, whereas the highest doses for acute were observed in the children (0-3 years), which has implications in the adverse health effects for sensitive groups. The sensitive analysis finds the concentration of PM to be the most influencing factor in inhalation dose estimation.
{"title":"OCCURRENCE OF PM0.1 AND PM2.5 AT HIGH POLLUTING EVENT DAYS IN HANOI AND HEALTH IMPLICATION","authors":"Thuy Bich Ly, Le-Ha T. Vo, Dieu Anh Van, Thu Hien Nguyen, Duy Nam Dao, Trung-Dung Nghiem, Quoc Dat Nguyen","doi":"10.15625/2525-2518/18373","DOIUrl":"https://doi.org/10.15625/2525-2518/18373","url":null,"abstract":"High levels of fine (PM2.5) and ultrafine (PM0.1) particles in the atmosphere can cause adverse effects on the environment and human health. This study aims at determining the mass concentrations of PM and health risks on pollution event days (episodes) in Hanoi. Semi-daily samples (daytime and night-time) of PM2.5 and PM0.1 were collected at Hanoi University of Science and Technology, in December 2021. The daily PM2.5 concentrations were in the range of 42 – 204 µg/m3 (average of 123 µg/m3). Those of PM0.1 varied from 9 to 30 µg/m3 (average of 22 µg/m3). There is negligible change on daytime and night-time PM0.1 concentrations, whereas those levels of PM2.5 were remarkably different. PM2.5 daytime concentrations were in the range of 39 – 205 µg/m3 with an average of 107 µg/m3. The level ranges of night-time were slightly wider which varied from 39 to 230 µg/m3 (average of 132 µg/m3). A prolonged episode of PM2.5 (which is defined by the criterion of PM2.5 > 50 µg/m3) was found with an intensity of 26 days in December. During the pollution episode, the Monte Carlo simulation showed that respirable doses were the highest for the adult (above 21 years) for chronic effects, whereas the highest doses for acute were observed in the children (0-3 years), which has implications in the adverse health effects for sensitive groups. The sensitive analysis finds the concentration of PM to be the most influencing factor in inhalation dose estimation.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140086617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.15625/2525-2518/16311
T. Tu, Huy Q. Tran, Huong D. T. Nguyen, Nhung Thi Tran, Tung T. Nguyen, Long H. Ngo
The iron-based metal–organic frame (Fe-MOF), VNU-20, and its carbonized analogues were synthesized. Subsequently, this material was investigated for electrical properties in comparison with the carbonized samples from other MOFs and ZIFs (such as ZIF-8, ZIF-67, MOF-199, MIL-53). The experiments showed the results with the reversible cyclic voltammetry (CV) curve characterized by the redox oxidation reactions of Fe(II)/Fe(III). Furthermore, the electrode composed of carbonized VNU-20 shows a comparable capacitance with that of carbonized ZIF-67, the highest capacitance material recorded up to date for the same class of materials. While further experiments need to be carried out for the optimization, initial analyzes show the promising result for further investigation and use of carbonized VNU-20 as the electrode material for electro-catalysis and the supercapacitor.
{"title":"SYNTHESIZING AND INVESTIGATING THE ELECTRICAL PROPERTIES OF CARBONIZED METAL–ORGANIC FRAMEWORKS","authors":"T. Tu, Huy Q. Tran, Huong D. T. Nguyen, Nhung Thi Tran, Tung T. Nguyen, Long H. Ngo","doi":"10.15625/2525-2518/16311","DOIUrl":"https://doi.org/10.15625/2525-2518/16311","url":null,"abstract":"The iron-based metal–organic frame (Fe-MOF), VNU-20, and its carbonized analogues were synthesized. Subsequently, this material was investigated for electrical properties in comparison with the carbonized samples from other MOFs and ZIFs (such as ZIF-8, ZIF-67, MOF-199, MIL-53). The experiments showed the results with the reversible cyclic voltammetry (CV) curve characterized by the redox oxidation reactions of Fe(II)/Fe(III). Furthermore, the electrode composed of carbonized VNU-20 shows a comparable capacitance with that of carbonized ZIF-67, the highest capacitance material recorded up to date for the same class of materials. While further experiments need to be carried out for the optimization, initial analyzes show the promising result for further investigation and use of carbonized VNU-20 as the electrode material for electro-catalysis and the supercapacitor.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140402496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-23DOI: 10.15625/2525-2518/17919
Phan Thanh Toan, Do Van Tuan
MS-RCPSP is a combinatorial optimization problem that has many practical applications, this problem has been proven to belong to the NP-hard class, the approach to solving this problem is to use algorithms to find approximate solution. This paper proposed a New Adaptive Local Particle Swarm Optimization algorithm for the MS-RCPSP problem. The solution for the class of NP-Hard problems is to find approximate solutions using metaheuristic algorithms. However, most metaheuristic-based algorithms have a weakness that can be fallen into local extreme after a number of evolution generations. In this paper, we adopted a new adaptive nonlinear weight update strategy based on fitness value and new neighborhood topology for Particle Swarm Optimization algorithm, thereby helping to prevent PSO from falling into local extremes. The new algorithm is called AdaL-PSO. A numerical analysis is carried out using iMOPSE benchmark dataset and is compared with some other early algorithms. Results presented suggest the prospect of our proposed algorithm.
{"title":"AdaL-PSO A New Adaptive Algorithm for the Multi-Skilled Resource-Constrained Project Scheduling Problem","authors":"Phan Thanh Toan, Do Van Tuan","doi":"10.15625/2525-2518/17919","DOIUrl":"https://doi.org/10.15625/2525-2518/17919","url":null,"abstract":"MS-RCPSP is a combinatorial optimization problem that has many practical applications, this problem has been proven to belong to the NP-hard class, the approach to solving this problem is to use algorithms to find approximate solution. This paper proposed a New Adaptive Local Particle Swarm Optimization algorithm for the MS-RCPSP problem. The solution for the class of NP-Hard problems is to find approximate solutions using metaheuristic algorithms. However, most metaheuristic-based algorithms have a weakness that can be fallen into local extreme after a number of evolution generations. In this paper, we adopted a new adaptive nonlinear weight update strategy based on fitness value and new neighborhood topology for Particle Swarm Optimization algorithm, thereby helping to prevent PSO from falling into local extremes. The new algorithm is called AdaL-PSO. A numerical analysis is carried out using iMOPSE benchmark dataset and is compared with some other early algorithms. Results presented suggest the prospect of our proposed algorithm.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140435773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-23DOI: 10.15625/2525-2518/17071
Pham Thi Mai, Huong, Nguyen Thi Huong
In this work, the electrochemical behavior of carbon steel, brass, bronze and aluminum alloys in the presence of various important organic acids (sebacic acid (SbA), terephthalic (TPA), 2-ethylhexanoic (E2C6A), and octanoic (C8A)) and the effect that these have on the growth and protectiveness of the alloys have been investigated. The results show that the presence of organic acids in the coolant increases the protective effect of the system by forming a film on the surface of the alloys. The EIS impedance results demonstrate the formation of active and passive protective layers on the surface of the alloys. The results of surveying 04 types of organic acids for the protection of different alloy substrates show that TPA and SbA acid additives are more effective than C8A and E2C5A. The additive C8A not only did not inhibit corrosion but also promoted this process strongly, especially with aluminum alloys and the TPA has the best anti-corrosion effect for steel, followed by C1 copper alloy and aluminum.
{"title":"Study ability of protection effect of organic acids for multi-metallic anti-corrosion additive system in ethylene glycol-water coolants","authors":"Pham Thi Mai, Huong, Nguyen Thi Huong","doi":"10.15625/2525-2518/17071","DOIUrl":"https://doi.org/10.15625/2525-2518/17071","url":null,"abstract":"In this work, the electrochemical behavior of carbon steel, brass, bronze and aluminum alloys in the presence of various important organic acids (sebacic acid (SbA), terephthalic (TPA), 2-ethylhexanoic (E2C6A), and octanoic (C8A)) and the effect that these have on the growth and protectiveness of the alloys have been investigated. The results show that the presence of organic acids in the coolant increases the protective effect of the system by forming a film on the surface of the alloys. The EIS impedance results demonstrate the formation of active and passive protective layers on the surface of the alloys. The results of surveying 04 types of organic acids for the protection of different alloy substrates show that TPA and SbA acid additives are more effective than C8A and E2C5A. The additive C8A not only did not inhibit corrosion but also promoted this process strongly, especially with aluminum alloys and the TPA has the best anti-corrosion effect for steel, followed by C1 copper alloy and aluminum.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140436229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-23DOI: 10.15625/2525-2518/17349
Nguyen Thi Thuy Khue, Le Thi Thanh Tam, Ngo Thanh Dung, Nguyen Thi Ngoc Linh, Nguyen Huu Tuan Dung, Le The Tam, Le Trong Lu
In this work, we present the synthesis and applications of Gd2O3@PVP nanoparticles as an efficient contrast agent for MRI and CT techniques. Gd2O3@PVP nanoparticles have been successfully synthesized by the polyol method using ethylene glycol and poly(vinylpyrrolidone) as solvent and surfactant, respectively. The structure, morphology and characteristic properties of the materials are thoroughly investigated by SEM, TEM, UV-Vis, XRD, FTIR and DLS measurements. As an important result, NPs synthesized under optimized conditions have a diameter in the range of 12 nm and exhibit a good contrast signal in magnetic resonance imaging and computed tomography at relatively low concentration ([NPs] = 0.1 mM for MRI and 1.25 mg.mL-1 for CT). In particular, the concentration of Gd2O3@PVP nanoparticles used in CT is 10 times lower than that of the commercial Iobitridol product (i.e., 12.5 mg.mL-1) to achieve similar signal intensity. This result has an important implication for reducing the dose of contrast agent introduced into the body. The obtained results suggest that PVP-coated Gd2O3 nanoparticles can be applied as multifunctional contrast agents for imaging diagnostic applications in the near future.
{"title":"Synthesis and characterization of PVP coated gadolinium oxide nanoparticles for imaging applications","authors":"Nguyen Thi Thuy Khue, Le Thi Thanh Tam, Ngo Thanh Dung, Nguyen Thi Ngoc Linh, Nguyen Huu Tuan Dung, Le The Tam, Le Trong Lu","doi":"10.15625/2525-2518/17349","DOIUrl":"https://doi.org/10.15625/2525-2518/17349","url":null,"abstract":"In this work, we present the synthesis and applications of Gd2O3@PVP nanoparticles as an efficient contrast agent for MRI and CT techniques. Gd2O3@PVP nanoparticles have been successfully synthesized by the polyol method using ethylene glycol and poly(vinylpyrrolidone) as solvent and surfactant, respectively. The structure, morphology and characteristic properties of the materials are thoroughly investigated by SEM, TEM, UV-Vis, XRD, FTIR and DLS measurements. As an important result, NPs synthesized under optimized conditions have a diameter in the range of 12 nm and exhibit a good contrast signal in magnetic resonance imaging and computed tomography at relatively low concentration ([NPs] = 0.1 mM for MRI and 1.25 mg.mL-1 for CT). In particular, the concentration of Gd2O3@PVP nanoparticles used in CT is 10 times lower than that of the commercial Iobitridol product (i.e., 12.5 mg.mL-1) to achieve similar signal intensity. This result has an important implication for reducing the dose of contrast agent introduced into the body. The obtained results suggest that PVP-coated Gd2O3 nanoparticles can be applied as multifunctional contrast agents for imaging diagnostic applications in the near future.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140436804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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