Pub Date : 2023-04-17DOI: 10.15625/2525-2518/16432
H. Hoang, Nguyen Hong Tin, Dinh Diep Anh Tuan, Van Pham Dang Tri
Climate change, hydro-power dams and socio-economic development in the upper Mekong River, have caused changes in surface water resources and agricultural transformation in the Vietnamese Mekong Delta (VMD). It is unpredictable and influences decision-making processes on water resource management. This study aims at applying the DAPP (Dynamic Adaptive Policy Pathways) approach to develop solution roadmaps supporting rice production in the Mekong Delta projection to 2030 under the context of uncertain changes on surface water resources. Data were collected from local officers, farmers, experts at Can Tho University, Technical University Delft, and Utrecht University using semi-structured interview techniques including workshops, group discussions, and in-depth interviews. The consolidated solutions from stakeholder’s opinions were evaluated at different socio-economic and environmental dimensions, specially focused on the time of tipping point of each solution. The study results show that two solution roadmaps were developed as sample scenarios to promote rice production in the upper area of the VMD. The determination of the solutions roadmaps based on the agreement of the stakeholders, which is a new feature of this approach in linking many stakeholders for the general development of the region. The DAPP approach could be suitable to support decision-making on surface water resources management in the context of uncertain changes. Therefore, further studies can apply this approach to other regions in the VMD which will support to reinforce and demonstrate the applicability of the DAPP approach on supporting decision-making in the face of increasingly uncertain changes in the VMD.
{"title":"Developing solutions roadmaps for rice production in flooding area of the Vietnamese Mekong Delta adapting to uncertain changes in climate and surface water resources","authors":"H. Hoang, Nguyen Hong Tin, Dinh Diep Anh Tuan, Van Pham Dang Tri","doi":"10.15625/2525-2518/16432","DOIUrl":"https://doi.org/10.15625/2525-2518/16432","url":null,"abstract":"Climate change, hydro-power dams and socio-economic development in the upper Mekong River, have caused changes in surface water resources and agricultural transformation in the Vietnamese Mekong Delta (VMD). It is unpredictable and influences decision-making processes on water resource management. This study aims at applying the DAPP (Dynamic Adaptive Policy Pathways) approach to develop solution roadmaps supporting rice production in the Mekong Delta projection to 2030 under the context of uncertain changes on surface water resources. Data were collected from local officers, farmers, experts at Can Tho University, Technical University Delft, and Utrecht University using semi-structured interview techniques including workshops, group discussions, and in-depth interviews. The consolidated solutions from stakeholder’s opinions were evaluated at different socio-economic and environmental dimensions, specially focused on the time of tipping point of each solution. The study results show that two solution roadmaps were developed as sample scenarios to promote rice production in the upper area of the VMD. The determination of the solutions roadmaps based on the agreement of the stakeholders, which is a new feature of this approach in linking many stakeholders for the general development of the region. The DAPP approach could be suitable to support decision-making on surface water resources management in the context of uncertain changes. Therefore, further studies can apply this approach to other regions in the VMD which will support to reinforce and demonstrate the applicability of the DAPP approach on supporting decision-making in the face of increasingly uncertain changes in the VMD.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74048858","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 : 2023-04-17DOI: 10.15625/2525-2518/16847
Quyen, Thi Bich Tran, Phuong Thi Ngoe Huynh, My, Nguyen Tra Ngo, Thien, Van Hong Doan, T. H. Luong, L. Tran
Graphene Quantum Dots (GQDs) were successfully synthesized by a green and eco-friendly synthetic method using abundant and naturally available raw materials from rice flour. This study suggested and compared two aggressive approaches to fabricate GQDs, which are hydrothermal method at 170 °C for 8 h and microwave irradiation method at 900 W with a short reaction time of 30 min. The results showed that the hydrothermal method produced GQDs with better nanoparticle size and properties than the microwave irradiation method. Furthermore, the products were only GQDs, water and carbide precipitate, thus avoiding complicated post-processing steps. The synthesized GQDs were determined for their morphology by Transmission electron microscope (TEM) showing spherical nanoparticles with an average size of ~5-7 nm and ~10-14 nm for hydrothermal and microwave irradiation methods, respectively. Besides, these GQDs were also analyzed for their characterizations, morphologies and compositions by UV-vis, XRD and FTIR. Thanks to their low cytotoxicity, good optical stability, and excellent photo-luminescence property, GQDs have become novel nanostructured materials in many application fields from energy to biomedicine and environment such as sensors, bio-imaging, drug carriers, and solar cells.
{"title":"Green synthesis of graphene quantum dots from rice flour","authors":"Quyen, Thi Bich Tran, Phuong Thi Ngoe Huynh, My, Nguyen Tra Ngo, Thien, Van Hong Doan, T. H. Luong, L. Tran","doi":"10.15625/2525-2518/16847","DOIUrl":"https://doi.org/10.15625/2525-2518/16847","url":null,"abstract":"Graphene Quantum Dots (GQDs) were successfully synthesized by a green and eco-friendly synthetic method using abundant and naturally available raw materials from rice flour. This study suggested and compared two aggressive approaches to fabricate GQDs, which are hydrothermal method at 170 °C for 8 h and microwave irradiation method at 900 W with a short reaction time of 30 min. The results showed that the hydrothermal method produced GQDs with better nanoparticle size and properties than the microwave irradiation method. Furthermore, the products were only GQDs, water and carbide precipitate, thus avoiding complicated post-processing steps. The synthesized GQDs were determined for their morphology by Transmission electron microscope (TEM) showing spherical nanoparticles with an average size of ~5-7 nm and ~10-14 nm for hydrothermal and microwave irradiation methods, respectively. Besides, these GQDs were also analyzed for their characterizations, morphologies and compositions by UV-vis, XRD and FTIR. Thanks to their low cytotoxicity, good optical stability, and excellent photo-luminescence property, GQDs have become novel nanostructured materials in many application fields from energy to biomedicine and environment such as sensors, bio-imaging, drug carriers, and solar cells.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87984549","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 : 2023-04-17DOI: 10.15625/2525-2518/16785
Le Duc Anh, Luu Van Chinh, Truong Ngoc Hung, Nguyen Manh Cuong, Pham Hong Ngoc
2’-Hydroxychalcones and murrayafoline A, a natural compounds isolated from Glycomis stenocarpa, have been reported to have the promising anti-cancer activity. In this study, a series of 2'-hydroxychalcones containing murrayafoline A (MuA) 6a-f were achieved by Claisen-Schmidt condensation of the key intermediate 5'-(1-methoxy-3-methyl-carbazolyl)methyl-2'-hydroxyacetophenone 4 with various aldehydes 5a-f with purpose of combining activity of two precusors. Their structures were determined by NMR and MS spectral data. Screening for cytotoxicity of compounds showed that compounds 6a-6d expressed cytotoxic activity, notably compound 6a displayed activity against all tested cell lines LU-1, Hep-G2, MCF-7, P338, and SW480 with the IC50 values ranging from 23.97 to 80.19 μg/mL. Clearly, the substitution at position of N-H group of murrayafoline a led to a decline in the cytotoxicity of the obtained derivatives. This finding suggests the presence of the N-H group might be play a crucial role for the cytotoxicity of the murrayafoline A derivatives.
2′-羟基查尔酮和murrayafoline A是一种从窄果糖中分离得到的天然化合物，具有良好的抗癌活性。本研究通过关键中间体5′-(1-甲氧基-3-甲基-咔唑基)甲基-2′-羟基苯乙酮4与多种醛5a-f的Claisen-Schmidt缩合反应，获得了一系列含murrayafoline a (MuA) 6a-f的2′-羟基查尔酮，以达到两种前体的结合活性。通过核磁共振和质谱数据确定了它们的结构。化合物6a-6d均表现出细胞毒活性，其中化合物6a对所有细胞株LU-1、Hep-G2、MCF-7、P338和SW480均表现出活性，IC50值在23.97 ~ 80.19 μg/mL之间。显然，甲基亚酚a N-H基位置的取代导致所得到的衍生物的细胞毒性下降。这一发现表明N-H基团的存在可能在murrayafoline a衍生物的细胞毒性中起关键作用。
{"title":"Synthesis and cytotoxic activity of some novel 2’-hydroxychalcones containing murrayafoline A","authors":"Le Duc Anh, Luu Van Chinh, Truong Ngoc Hung, Nguyen Manh Cuong, Pham Hong Ngoc","doi":"10.15625/2525-2518/16785","DOIUrl":"https://doi.org/10.15625/2525-2518/16785","url":null,"abstract":"2’-Hydroxychalcones and murrayafoline A, a natural compounds isolated from Glycomis stenocarpa, have been reported to have the promising anti-cancer activity. In this study, a series of 2'-hydroxychalcones containing murrayafoline A (MuA) 6a-f were achieved by Claisen-Schmidt condensation of the key intermediate 5'-(1-methoxy-3-methyl-carbazolyl)methyl-2'-hydroxyacetophenone 4 with various aldehydes 5a-f with purpose of combining activity of two precusors. Their structures were determined by NMR and MS spectral data. Screening for cytotoxicity of compounds showed that compounds 6a-6d expressed cytotoxic activity, notably compound 6a displayed activity against all tested cell lines LU-1, Hep-G2, MCF-7, P338, and SW480 with the IC50 values ranging from 23.97 to 80.19 μg/mL. Clearly, the substitution at position of N-H group of murrayafoline a led to a decline in the cytotoxicity of the obtained derivatives. This finding suggests the presence of the N-H group might be play a crucial role for the cytotoxicity of the murrayafoline A derivatives.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78168285","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 : 2023-04-17DOI: 10.15625/2525-2518/16627
N. Hung
The article is focused on the application of the reliability and experimental statistics theory to predict the distribution of the cylinder inner diameter and the piston outer diameter post-manufacture for the gas-operated automatic rifles. Besides, the influence of these dimensions on the operation of the automatic system was also studied in 5 cases with the maximum, minimum, and the most probable. The study object in the article is 7.62mm AKM-1 rifles. Research results show that the cylinder inner diameter and the piston outer diameter post-manufacture of 7.62mm AKM-1 rifles follow the normal distribution. The research results of the article can be used to establishing technical conditions for new gun acceptance post-manufacture.
{"title":"Prediction of the Distribution and Effect of Diameters of the Cylinder and the Piston Post-Manufacture on the Operation of Gas-Operated Automatic Rifles","authors":"N. Hung","doi":"10.15625/2525-2518/16627","DOIUrl":"https://doi.org/10.15625/2525-2518/16627","url":null,"abstract":"The article is focused on the application of the reliability and experimental statistics theory to predict the distribution of the cylinder inner diameter and the piston outer diameter post-manufacture for the gas-operated automatic rifles. Besides, the influence of these dimensions on the operation of the automatic system was also studied in 5 cases with the maximum, minimum, and the most probable. The study object in the article is 7.62mm AKM-1 rifles. Research results show that the cylinder inner diameter and the piston outer diameter post-manufacture of 7.62mm AKM-1 rifles follow the normal distribution. The research results of the article can be used to establishing technical conditions for new gun acceptance post-manufacture.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88442837","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 : 2023-04-05DOI: 10.15625/2525-2518/16865
Thi Tuyet Ngan Nguyen, Thi Thu Ha Vu, Van Thanh Dang, Tragiang Nguyen, Thi Hai Yen Pham
In this study, a graphite electrode (GrE) modified with polyglutamic acid was used to determine chloramphenicol (CAP), a phenicol antibiotic, in a water environment using adsorptive stripping linear sweep voltammetry. The pGA modification process involved electropolymerization via cyclic voltammetry, resulting in a significantly enlarged electrochemical active area of the pGA/GrE interface (1.5 times greater than that of the unmodified GrE). The highest CAP signal was obtained on the electrode fabricated by scanning 50 cycles in the potential range of -1.2 V to +2.0 V. The CAP signal recorded on the pGA/GrE electrode was nine times higher than that on the GrE, which was due to the larger electrochemical active area of the pGA/GrE and its good adsorption capacity with CAP. Analysis conditions including the pH of electrolyte and accumulation time, were optimized. Under optimal conditions, the calibration curve was built with two linear regions in the concentration ranges of 0.5-20 µmol L-1 (R2 = 0.987) and 20-100 µmol L-1 (R2 = 0.996), and the detection limit for CAP was 0.28 µmol L-1.
{"title":"Fabrication of polyglutamic acid-based sensor for electrochemical determination of a phenicol antibiotic in water environment","authors":"Thi Tuyet Ngan Nguyen, Thi Thu Ha Vu, Van Thanh Dang, Tragiang Nguyen, Thi Hai Yen Pham","doi":"10.15625/2525-2518/16865","DOIUrl":"https://doi.org/10.15625/2525-2518/16865","url":null,"abstract":"In this study, a graphite electrode (GrE) modified with polyglutamic acid was used to determine chloramphenicol (CAP), a phenicol antibiotic, in a water environment using adsorptive stripping linear sweep voltammetry. The pGA modification process involved electropolymerization via cyclic voltammetry, resulting in a significantly enlarged electrochemical active area of the pGA/GrE interface (1.5 times greater than that of the unmodified GrE). The highest CAP signal was obtained on the electrode fabricated by scanning 50 cycles in the potential range of -1.2 V to +2.0 V. The CAP signal recorded on the pGA/GrE electrode was nine times higher than that on the GrE, which was due to the larger electrochemical active area of the pGA/GrE and its good adsorption capacity with CAP. Analysis conditions including the pH of electrolyte and accumulation time, were optimized. Under optimal conditions, the calibration curve was built with two linear regions in the concentration ranges of 0.5-20 µmol L-1 (R2 = 0.987) and 20-100 µmol L-1 (R2 = 0.996), and the detection limit for CAP was 0.28 µmol L-1.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78758156","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 : 2023-04-05DOI: 10.15625/2525-2518/16892
Tam The Le, Linh Nguyen Thi Ngoc
In this work, highly stable Ag nanoparticles solution was synthesized using TBAB to reduce Ag+ in the presence of OLA in organic solvents at room temperature, and poly(acrylic acid) (PAA) as a phase transfer ligand in organic solvents. The effects of different solvents on the morphology and properties of the Ag nanomaterials were investigated in detail. The products were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), and absorption spectroscopy. Structural analysis demonstrated that the Ag nanomaterials showed good crystallinity. We have successfully synthesized Ag nanoparticles (Ag NPs) with small particle size (6.1 - 7.3 nm), high uniformity in organic solvents at room temperature. The Ag NPs obtained after phase transformation with PAA are well dispersed, endurance and stability in aqueous solvents. The obtained in-vitro CT imaging results have good X-ray absorption value. These findings suggest the potential application of PAA-coated Ag nanoparticles in the biomedical field, especially in imaging diagnostics using CT computed tomography.
{"title":"Synthesis of highly stable silver nanoparticles as computed tomography contrast agents","authors":"Tam The Le, Linh Nguyen Thi Ngoc","doi":"10.15625/2525-2518/16892","DOIUrl":"https://doi.org/10.15625/2525-2518/16892","url":null,"abstract":"In this work, highly stable Ag nanoparticles solution was synthesized using TBAB to reduce Ag+ in the presence of OLA in organic solvents at room temperature, and poly(acrylic acid) (PAA) as a phase transfer ligand in organic solvents. The effects of different solvents on the morphology and properties of the Ag nanomaterials were investigated in detail. The products were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), and absorption spectroscopy. Structural analysis demonstrated that the Ag nanomaterials showed good crystallinity. We have successfully synthesized Ag nanoparticles (Ag NPs) with small particle size (6.1 - 7.3 nm), high uniformity in organic solvents at room temperature. The Ag NPs obtained after phase transformation with PAA are well dispersed, endurance and stability in aqueous solvents. The obtained in-vitro CT imaging results have good X-ray absorption value. These findings suggest the potential application of PAA-coated Ag nanoparticles in the biomedical field, especially in imaging diagnostics using CT computed tomography. ","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82872449","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 : 2023-04-05DOI: 10.15625/2525-2518/16945
Q. Pham, Thi-Hong-Minh Pham
In this study, computational molecular simulation and drug-like properties assessment were used to gain insight into the binding ability of 16 alkaloid and phenolic compounds isolated from Zanthoxylum nitidum on protein tubulin. Amongst studied candidates, compounds 8 and 10 were identified as potential candidates for inhibiting the function of tubulin at the active site regarding binding affinity, dock pose and ADMET properties analysis. These findings shed light on the potential anti-cancer of compounds isolated from Zanthoxylum nitidum.
{"title":"In silico studies on potential MCF-7 inhibitors of alkaloid and phenolic compounds isolated from Zanthoxylum nitidum: A combination of molecular docking and ADMET analysis","authors":"Q. Pham, Thi-Hong-Minh Pham","doi":"10.15625/2525-2518/16945","DOIUrl":"https://doi.org/10.15625/2525-2518/16945","url":null,"abstract":"In this study, computational molecular simulation and drug-like properties assessment were used to gain insight into the binding ability of 16 alkaloid and phenolic compounds isolated from Zanthoxylum nitidum on protein tubulin. Amongst studied candidates, compounds 8 and 10 were identified as potential candidates for inhibiting the function of tubulin at the active site regarding binding affinity, dock pose and ADMET properties analysis. These findings shed light on the potential anti-cancer of compounds isolated from Zanthoxylum nitidum.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73383000","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 : 2023-04-05DOI: 10.15625/2525-2518/17073
Eight hydrazones 7a-h containing benzo[d]thiazole were synthesized in high yield by the condensation reaction of N-(5-(benzo[d]thiazol-2-yl)-2-(2-hydrazinyl-2-oxoethoxy)phenyl)acetamide (6) derived from 4-hydroxy-3-nitrobenzaldehyde with aromatic aldehydes under microwave irradiation. Structures of these derivatives 7a-h were elucidated by IR, NMR, and MS analysis. NMR spectra showed that in solution, hydrazones may exist in two conformations EN-C(O)ZN-C(O)EC=N and ZN-C(O)ZN-C(O)EC=N, the relative ratio of these two conformations is about 3:2. Four compounds 7a, 7c, 7e, 7g were screened for antimicrobial activities. Compounds 7c, 7e, and 7g exhibited weak antibacterial and antifungal activity against B. subtillis and S. cerevisiae, E. coli, or P. aeruginosa at 200 µg/L.
{"title":"Synthesis, structure and antibacterial, antifungal activities of some hydrazones synthesized from 4-hydroxy-3-nitrobenzaldehyde","authors":"","doi":"10.15625/2525-2518/17073","DOIUrl":"https://doi.org/10.15625/2525-2518/17073","url":null,"abstract":"Eight hydrazones 7a-h containing benzo[d]thiazole were synthesized in high yield by the condensation reaction of N-(5-(benzo[d]thiazol-2-yl)-2-(2-hydrazinyl-2-oxoethoxy)phenyl)acetamide (6) derived from 4-hydroxy-3-nitrobenzaldehyde with aromatic aldehydes under microwave irradiation. Structures of these derivatives 7a-h were elucidated by IR, NMR, and MS analysis. NMR spectra showed that in solution, hydrazones may exist in two conformations EN-C(O)ZN-C(O)EC=N and ZN-C(O)ZN-C(O)EC=N, the relative ratio of these two conformations is about 3:2. Four compounds 7a, 7c, 7e, 7g were screened for antimicrobial activities. Compounds 7c, 7e, and 7g exhibited weak antibacterial and antifungal activity against B. subtillis and S. cerevisiae, E. coli, or P. aeruginosa at 200 µg/L.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85106345","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 : 2023-04-05DOI: 10.15625/2525-2518/17395
Task incremental learning, a setting of Continual learning, isan approach to exploit the knowledge from previous tasks for currentlynew task. Task incremental learning aims to solve two big challengesof continual learning: catastrophic forgetting and knowledge transfer orsharing between previous tasks and current task. This paper improveTask incremental learning by (1) transferring the knowledge (not thetraining data) learned from previous tasks to a new task (contrast ofmulti-task learning); (2) to maintain or even improve performance oflearned models from previous tasks with avoid forgetting; (3) to developa continual learning model based on result from (1) and (2) to applyfor aspect sentiment classification. Specifically, we combine two loss baseon contrastive learning modules from Contrastive Knowledge Sharing(CKS) for encouraging knowledge sharing between old and current tasksand improve the performance of the current task by Contrastive Super-vised learning (CSC) module. The experimental results show that ourmethod could get rid of previous learned tasks catastrophic forgettingphenomenon and outperform the previous study for aspect sentimentclassification.
{"title":"Bert Adapter and Contrastive Learning for Continual Classification of Aspect Sentiment Task Sequences","authors":"","doi":"10.15625/2525-2518/17395","DOIUrl":"https://doi.org/10.15625/2525-2518/17395","url":null,"abstract":"Task incremental learning, a setting of Continual learning, isan approach to exploit the knowledge from previous tasks for currentlynew task. Task incremental learning aims to solve two big challengesof continual learning: catastrophic forgetting and knowledge transfer orsharing between previous tasks and current task. This paper improveTask incremental learning by (1) transferring the knowledge (not thetraining data) learned from previous tasks to a new task (contrast ofmulti-task learning); (2) to maintain or even improve performance oflearned models from previous tasks with avoid forgetting; (3) to developa continual learning model based on result from (1) and (2) to applyfor aspect sentiment classification. Specifically, we combine two loss baseon contrastive learning modules from Contrastive Knowledge Sharing(CKS) for encouraging knowledge sharing between old and current tasksand improve the performance of the current task by Contrastive Super-vised learning (CSC) module. The experimental results show that ourmethod could get rid of previous learned tasks catastrophic forgettingphenomenon and outperform the previous study for aspect sentimentclassification.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79989907","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 : 2023-04-05DOI: 10.15625/2525-2518/16768
In this study, Al-Mg alloy coatings were deposited on a C45 steel substrate by using the electric arc spray technique. The corrosion behavior of the coating was studied by electrochemical measurements and salt spray tests. The electrochemical tests were performed in 3.5 wt.% NaCl solution. Polarization tests indicated that the corrosion potential of the coating is significantly more negative than that of steel substrate after 240 hours of immersion. EIS measurements showed that after 24 hours of immersion, the total impedance increased with increasing the immersion time. This could be due to sealing of pores by corrosion products which hinder further penetration of the solution through the coating. Red rust spots did not appear on the surface of the coating after 1360 hours of salt spray test. The corrosion rate of the coating decreased with the increase in salt spray test time. After the salt spray test, the coating surface pitted and the cross section of the coating appeared with many long voids. In addition, XRD analysis proved that the main corrosion product was Al(OH)3. The results obtained indicated that arc thermal sprayed Al-Mg alloy coatings can reliably protect steel structures against corrosion in chloride-containing aqueous solutions.
{"title":"Study of corrosion behavior of arc thermal sprayed Al-Mg alloy coating","authors":"","doi":"10.15625/2525-2518/16768","DOIUrl":"https://doi.org/10.15625/2525-2518/16768","url":null,"abstract":"In this study, Al-Mg alloy coatings were deposited on a C45 steel substrate by using the electric arc spray technique. The corrosion behavior of the coating was studied by electrochemical measurements and salt spray tests. The electrochemical tests were performed in 3.5 wt.% NaCl solution. Polarization tests indicated that the corrosion potential of the coating is significantly more negative than that of steel substrate after 240 hours of immersion. EIS measurements showed that after 24 hours of immersion, the total impedance increased with increasing the immersion time. This could be due to sealing of pores by corrosion products which hinder further penetration of the solution through the coating. Red rust spots did not appear on the surface of the coating after 1360 hours of salt spray test. The corrosion rate of the coating decreased with the increase in salt spray test time. After the salt spray test, the coating surface pitted and the cross section of the coating appeared with many long voids. In addition, XRD analysis proved that the main corrosion product was Al(OH)3. The results obtained indicated that arc thermal sprayed Al-Mg alloy coatings can reliably protect steel structures against corrosion in chloride-containing aqueous solutions.","PeriodicalId":23553,"journal":{"name":"Vietnam Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87246841","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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