Ministry of Science and Technology, Vietnam最新文献_第9页

Assessing the risk and morphological characteristics of weedy rice outbreak in Thap Muoi district, Dong Thap province, Vietnam 评估越南同塔省 Thap Muoi 县杂草稻爆发的风险和形态特征

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).77-83

Cong Vinh Kieu, Ho Le Thi

{"title":"Assessing the risk and morphological characteristics of weedy rice outbreak in Thap Muoi district, Dong Thap province, Vietnam","authors":"Cong Vinh Kieu, Ho Le Thi","doi":"10.31276/vjste.65(4).77-83","DOIUrl":"https://doi.org/10.31276/vjste.65(4).77-83","url":null,"abstract":"The Thap Muoi district in Dong Thap province, Vietnam, is renowned as the largest rice producer, cultivating 112,762 hectares and specialising in three rice crops per year, with some areas achieving 3.5 annual crops. However, changing farming practices, low-quality rice seeds, and mechanisation have led to the emergence and spread of weedy rice (Oryza spp.) in Thap Muoi and the broader Mekong delta. This comprehensive assessment of weedy rice outbreak risks in Thap Muoi provides a vital foundation for effective management strategies to prevent its spread in the Mekong delta. Sixty questionnaires were collected from rice-farming households. Approximately 80% of farmers reported the appearance of weedy rice approximately five years ago. Alarmingly, 95% of surveyed farmers (57 individuals) reported weedy rice infestations, with 40% of them encountering infection levels ranging from 11 to 20 plants/m2. To distinguish weedy rice from cultivated varieties, seven distinct types were identified based on various morphological characteristics, including growth time, leaf blade structure, plant height, leaf/stem colour and shape, grain beard/tail, seed/husk colour, grain length, ripening time, and seed dispersal potential. However, all seven weedy rice varieties exhibited short growth cycles and the capacity to produce seeds, posing significant challenges to rice production management in Thap Muoi. This research underscores the critical importance of assessing weedy rice outbreak risks in Thap Muoi and understanding its morphology and prevalence. This understanding is essential for developing effective preventive measures to mitigate the threat of weedy rice outbreaks across the entire Mekong delta in Vietnam.","PeriodicalId":18650,"journal":{"name":"Ministry of Science and Technology, Vietnam","volume":"184 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138998251","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}

引用次数: 0

Methyl orange-doped thiourea barium chloride crystals: Natural bond orbital analysis of the fock matrix for laser applications 掺杂甲基橙的硫脲氯化钡晶体：用于激光应用的福克矩阵天然键轨道分析

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).36-41

S. Panimalar, P. Kumaresan, S. Nithiyanantham, K. Selva Sambath Kumar, R. Mohan

{"title":"Methyl orange-doped thiourea barium chloride crystals: Natural bond orbital analysis of the fock matrix for laser applications","authors":"S. Panimalar, P. Kumaresan, S. Nithiyanantham, K. Selva Sambath Kumar, R. Mohan","doi":"10.31276/vjste.65(4).36-41","DOIUrl":"https://doi.org/10.31276/vjste.65(4).36-41","url":null,"abstract":"Pure thiourea barium chloride (TBC) crystals were synthesised using a slow cooling rate (0.05°C/day) and gradual evaporation from an aqueous solution. The growth process occurred over more than 19 days at a temperature of 39°C. Natural bond orbital (NBO) analysis has proven beneficial for studying charge transfer and conjugative interactions in molecular systems. Moreover, it sheds light on intermolecular bonding, and the interactions between these bonds have implications for optical applications. Additionally, the charge transfer interactions within the molecule that influence its catalytic activity can be elucidated by a lower HOMO and LUMO energy gap. This energy difference can be an indicator of a compound’s excitability; the more readily a compound can be excited, the narrower the energy gap. The energy gap might be significantly affected by the influence of thermal energy. The non-linear optical (NLO) efficiency of methyl orange-doped (MOD) TBC crystals was contrasted with that of the pure form, and the doped version exhibited greater efficiency, particularly for high-frequency applications.","PeriodicalId":18650,"journal":{"name":"Ministry of Science and Technology, Vietnam","volume":"103 S7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138998587","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}

引用次数: 0

Effects of the wheel rotation speed during the melt-spinning process on the structural morphology and the thermoelectric properties of Ti0.5Zr0.5NiSn alloy 熔融纺丝过程中的砂轮转速对 Ti0.5Zr0.5NiSn 合金的结构形态和热电性能的影响

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).42-47

Nguyen Van Du, Nguyen Tu, Do Quang Trung, Noy Sysavanh, M. Tran, Tong Thi Hao Tam

{"title":"Effects of the wheel rotation speed during the melt-spinning process on the structural morphology and the thermoelectric properties of Ti0.5Zr0.5NiSn alloy","authors":"Nguyen Van Du, Nguyen Tu, Do Quang Trung, Noy Sysavanh, M. Tran, Tong Thi Hao Tam","doi":"10.31276/vjste.65(4).42-47","DOIUrl":"https://doi.org/10.31276/vjste.65(4).42-47","url":null,"abstract":"Half-Heusler alloys based on (Ti, Hf, Zr)NiSn possess excellent mechanical and chemical properties as well as high thermal stability, making them promising materials for high-performance thermoelectric (TE) power generators. However, the high cost of Hf limits its use in these alloys. Therefore, Hf-free (Ti, Zr)NiSn alloys synthesised using a rapid process offer a cost-effective approach to reducing product costs. In this study, we employed the fast synthesis melt-spinning (MS) method to prepare an Hf-free Ti0.5Zr0.5NiSn alloy while systematically optimising MS conditions. We found that by varying the rotation speed of the copper wheel in the MS system from 1000 to 4000 rpm, a marked change in the structural morphology of the melt-spun ribbons occurred. Grain growth during the spark plasma sintering process significantly affected TE properties of the bulk Ti0.5Zr0.5NiSn alloy depending on the structural morphology. As a result, a maximum ZT of ~1.1 at 823 K was achieved for a wheel rotation speed of 3000 rpm, which is comparable to ZT values obtained from the (Ti, Hf, Zr)NiSn-based half-Heusler alloys prepared by other methods.","PeriodicalId":18650,"journal":{"name":"Ministry of Science and Technology, Vietnam","volume":"14 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139000496","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}

引用次数: 0

Tensile behaviour of the dissimilar friction stir welding between pure copper and aluminium 1050 纯铜和铝 1050 之间异种摩擦搅拌焊的拉伸性能

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).25-28

Hoai Nam Quach, Dinh Hao Duong, Thanh Nhut Pham, Huu Huy Ho, Hong Chuong Pham, Van Hao Pham, Hung Tra Tran

{"title":"Tensile behaviour of the dissimilar friction stir welding between pure copper and aluminium 1050","authors":"Hoai Nam Quach, Dinh Hao Duong, Thanh Nhut Pham, Huu Huy Ho, Hong Chuong Pham, Van Hao Pham, Hung Tra Tran","doi":"10.31276/vjste.65(4).25-28","DOIUrl":"https://doi.org/10.31276/vjste.65(4).25-28","url":null,"abstract":"Copper-aluminum hybrid connectors play a crucial role in electric vehicles, but welding these metals together poses a significant challenge due to their distinct physical and mechanical properties. Friction stir welding, a solid-state welding technique, proves to be suitable for joining dissimilar metals. In this study, friction stir welding was employed to create a joint between pure copper 1100 and aluminum 1050 plates, each with a thickness of 5 mm. The fabricated results showed that a significant amount of copper was dispersed into the aluminum side to establish the bonding. The bonding strength was evaluated through tensile testing, while the macrostructure and fracture paths of the joints were monitored using an optical microscope. Despite efforts, eliminating defects in the joint proved challenging, with most defects attributed to vacancies. Increasing the tool rotation speed resulted in greater mixing intensity between the aluminum and copper. The interface between the copper and aluminum was found to be prone to crack propagation. The tensile strength of the joint improved with higher tool rotation, reaching up to 88 MPa. For further analysis, stress within the joint under tensile loading was simulated.","PeriodicalId":18650,"journal":{"name":"Ministry of Science and Technology, Vietnam","volume":"35 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138995864","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}

引用次数: 0

Isolation of Weizmannia coagulansand probiotic characterisation of strains 分离凝结地衣芽孢杆菌并确定菌株的益生特性

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).101-109

Thuy Duong Pham, Thi Lan Anh Hoang, Thi Le Quyen Tran, T. T. Trinh

{"title":"Isolation of Weizmannia coagulansand probiotic characterisation of strains","authors":"Thuy Duong Pham, Thi Lan Anh Hoang, Thi Le Quyen Tran, T. T. Trinh","doi":"10.31276/vjste.65(4).101-109","DOIUrl":"https://doi.org/10.31276/vjste.65(4).101-109","url":null,"abstract":"Weizmannia coagulans is a potential bacterial candidate for probiotics because of their advantageous characteristics in endospore formation, antibacterial production, and other beneficial human health effects. In this study, we isolated W. coagulans strains from different sample types collected in Hanoi and examined them for probiotic characteristics. From 40 samples, 5 strains were isolated from cow faeces. All W. coagulans strains had non-haemolytic activity and were susceptible to seven tested antibiotics. Cell-free supernatants of W. coagulans strains cultured in MRS medium could inhibit some bacterial pathogens such as Enterococcus faecalis, Listeria monocytogenes, Vibrio vulnificus, and Aeromonas dhakensis. The strains showed antioxidant activity with scavenging DPPH rates ranging from 72 to 82%. Three strains were able to adhere to the HT-29 cell line with adhesion ratesranging from 46 to 62.59%. The spores and vegetative cells of the three strains also showed great stress tolerance (survival rates >90%) against simulated gastrointestinal fluid. In liquid media containing 0.1% pancreatin and 0.3% bile salt, spores of VTCC 12782 and VTCC 12779 could germinate at rates of 25 and 2%, respectively. With the most beneficial characteristics, W. coagulans VTCC 12782 is suggested as a potential candidate for the development of probiotic products in the future.","PeriodicalId":18650,"journal":{"name":"Ministry of Science and Technology, Vietnam","volume":"49 39","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138995879","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}

引用次数: 0

Application of deep learning in chest X-ray abnormality detection 深度学习在胸部 X 光异常检测中的应用

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).84-93

Nhan Ngo, Toi Vo, Lua Ngo

引用次数: 0

Iron(III) promoted oxidative annulation of benzylic C-H bonds in (α-amino)arylacetic acids for synthesis of 4-aryl pyrrolo[1,2-a]quinoxalines 铁(III)促进(α-氨基)芳基乙酸中苄基 C-H 键的氧化环化以合成 4-芳基吡咯并[1,2-a]喹喔啉类化合物

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).11-13

Tuan H Ho

{"title":"Iron(III) promoted oxidative annulation of benzylic C-H bonds in (α-amino)arylacetic acids for synthesis of 4-aryl pyrrolo[1,2-a]quinoxalines","authors":"Tuan H Ho","doi":"10.31276/vjste.65(4).11-13","DOIUrl":"https://doi.org/10.31276/vjste.65(4).11-13","url":null,"abstract":"Using amino acids for synthesis of heterocycles is a synthetically promising field. However, developing the practical methods for transformations of amino acids into heterocycles is still challenging. Given that alpha amino acids are abundant or easily prepared, herein we report a method for annulation of benzylic C-H bonds in derivatives of 2-phenylglycine with 1-(2-nitroaryl)pyrroles. The reactions proceeded well in the presence of iron(III) acetylacetonate catalyst and potassium carbonate base. Scope of pyrrolo[1,2-a]quinoxalines was studied. Regardless of electronic properties of substituents, the pyrrolo[1,2-a]quinoxaline de-rivatives were successfully isolated, as yields varied from 42% to 52%. Pyrrolo[1,2-a]quinoxalines substituted with heterocycles at C4 positions as pyridine and thiophene were competent substrates. Reaction mechanism was proposed to start with a decar-boxylative/deaminative sequence of 2-phenylglycine to afford benzaldehyde. The iron catalyst was presumed to facilitate the re-duction of 1-(2-nitroaryl)pyrroles to furnish the corresponding aniline. Imine condensation followed by cyclisation and oxidation would yield the pyrrolo[1,2-a]quinoxaline. Our method would offer a convenient tactic to transform abundant alpha amino acids into synthetically useful heterocycles.","PeriodicalId":18650,"journal":{"name":"Ministry of Science and Technology, Vietnam","volume":"122 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138999671","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}

引用次数: 0

Study on flexural behaviour of printed concrete wide beams using polypropylene fibres 使用聚丙烯纤维的印花混凝土宽梁抗弯行为研究

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).48-53

Thi Loan Pham, D. Trinh, Thi-Thu Nguyen, Trong Quang Do, P. Nguyen

{"title":"Study on flexural behaviour of printed concrete wide beams using polypropylene fibres","authors":"Thi Loan Pham, D. Trinh, Thi-Thu Nguyen, Trong Quang Do, P. Nguyen","doi":"10.31276/vjste.65(4).48-53","DOIUrl":"https://doi.org/10.31276/vjste.65(4).48-53","url":null,"abstract":"Sustainability in building construction is an inevitable aspect of future construction projects. The justification of sustainability is highly appreciated by comparing 3D concrete printing technology with conventional construction. However, the 3D printing concrete system has limitations and challenges in industrial applications. The reason is that this process was initially used in small non-structural applications and is now being adopted for large-scale structures. Thanks to concrete printing machines, a wide variety of web frames are also available - something completely impossible to achieve using traditional formwork for pouring concrete. In this study, the girder web is designed in the style of truss beams. Three wide beams with different amounts of polypropylene (PP) fibre were printed, and 3-point loading tests were conducted. The failure mode, load-bearing capacity, and deflection were reported in this study. According to the results, applying concrete printing technology in civil and industrial construction is entirely feasible. The printing process successfully produced models with a nozzle diameter of 22 mm and layer height of 10 mm, ensuring sufficient adhesion force between the printing layers. Using a PP fibre content of about 0.25% yielded the best results in terms of concrete compressive strength and beams’ flexural strength, while a PP fibre content of about 1.00% tended to increase the ductility of the member. Although the failure mode is brittle, the beams exhibited deflection before fracture far beyond the allowable deflection value of a flexural member. Therefore, the application of printed components to construction is feasible.","PeriodicalId":18650,"journal":{"name":"Ministry of Science and Technology, Vietnam","volume":"25 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138996067","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}

引用次数: 0

Biodegradable containers from rice husk as substitutes for single-use plastic products 用稻壳制成的可生物降解容器替代一次性塑料制品

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).71-76

Nhung T. Tuyet Hoang, Anh Thi-Kim Tran

{"title":"Biodegradable containers from rice husk as substitutes for single-use plastic products","authors":"Nhung T. Tuyet Hoang, Anh Thi-Kim Tran","doi":"10.31276/vjste.65(4).71-76","DOIUrl":"https://doi.org/10.31276/vjste.65(4).71-76","url":null,"abstract":"Vietnam ranks among the top four nations for single-use plastic (SUP) waste, trailing only China, Indonesia, and Philippines. The abundant rice husk (RH) by-product of rice cultivation presents an opportunity to fabricate biodegradable containers, potentially supplanting single-use disposables. This study focuses on creating biodegradable containers from RH via thermo-pressing. Utilising the Taguchi orthogonal array method, we examined the impact of the RH to modified starch (MS) ratio (w/w %), pressing temperature (°C), and time (minutes) on the trays’ hardness, colour variation, and density, aiming to refine the manufacturing process. Additionally, variations in adhesive concentrations and glycerol were assessed for their influence on the aforementioned properties. The identified optimal conditions for fabricating viable biodegradable containers were a RH and MS composition of 80% (w/w), with a pressing duration of 3 minutes at 150°C. The resulting product exhibited a hardness of 5.26±0.22 kgF. Moreover, the thickness, density, and colour on the front and back sides were measured at 2.05±0.01 mm, 0.97±0.004 g/cm³, 50.87±0.96, and 48.05±0.87, respectively. Consequently, RH-based materials have emerged as promising candidates for crafting consumer-safe, environmentally benign biodegradable containers.","PeriodicalId":18650,"journal":{"name":"Ministry of Science and Technology, Vietnam","volume":"54 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138996365","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}

引用次数: 0

Investigation of residual stress in epoxy-based coatings using X-ray and FEM-ANN techniques 利用 X 射线和 FEM-ANN 技术研究环氧基涂层中的残余应力

Ministry of Science and Technology, Vietnam Pub Date : 2023-12-15 DOI: 10.31276/vjste.65(4).54-61

Jasim Haider Hadi

{"title":"Investigation of residual stress in epoxy-based coatings using X-ray and FEM-ANN techniques","authors":"Jasim Haider Hadi","doi":"10.31276/vjste.65(4).54-61","DOIUrl":"https://doi.org/10.31276/vjste.65(4).54-61","url":null,"abstract":"Residual stresses play a significant role in the properties and performance of epoxy-based coatings, with their origins rooted in various factors encountered during production and application. This study focuses on quantifying residual stresses in three distinct epoxy-based coatings, commonly used as linings for crude oil storage tanks, namely, pure epoxy, Novolac epoxy, and glass-flake-reinforced epoxy. We employ X-ray diffraction to measure these residual stresses and compare them against predicted values obtained through finite element and artificial neural network methods. Our findings reveal notable differences in residual stresses among the three types of epoxy coatings. Specifically, pure epoxy coatings exhibit higher residual stresses, Novolac epoxy coatings display the lowest, and those reinforced with glass flakes fall in between. Utilising the FEM-ANN model for simulations yields results that closely align with experimental measurements obtained via the X-ray method. Test results demonstrate that the coatings cured at high temperatures have high residual stresses compared to those cured at lower temperatures. Increasing the curing temperature from 10 to 50oC will increase residual stresses by 40.81, 11.085, and 56.98% for coatings reinforced with glass-flake, Novolac, and pure epoxy-based coating, respectively.","PeriodicalId":18650,"journal":{"name":"Ministry of Science and Technology, Vietnam","volume":"335 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138996645","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}

引用次数: 0