Examining Vietnam's Success in Controlling COVID-19 Pandemic in Terms of People's Behavior

To deal with an unprecedented pandemic known as COVID-19, every country has developed its own policies to prevent the expansion of Coronavirus. The purpose of this study is to investigate Vietnam’s success in controlling the spread of COVID-19 epidemic from the perspective of people’s behavior. This study applied the Health Belief Model developed by Don Nutbeam and Elizabeth (2004). An online survey engine (docs.google.com/forms) and an offline survey were employed to collect data from citizens in Hanoi, Ho Chi Minh City, Quang Ninh, Haiphong and other cities. The statistical analysis used 423 questionnaires from 450 respondents, mainly aged 18 to 35. The results demonstrated that people's awareness of COVID-19 as well as their behaviors have contributed significantly to the successful efforts to prevent and control the disease in Vietnam. Keywords: Covid-19 pandemic, controlling Covid-19, people’s behavior, behavior, Vietnam DOI: 10.7176/EJBM/13-6-07 Publication date:March 31st 202

Combination of epoxy coating with cerium-modified clays doped hybrid sol-gel film for active corrosion protection of aluminium alloys

peer reviewedAluminum alloy 2024 (AA2024) is widely used as an important material for aerospace industry. Therefore, with high copper content, AA2024 is susceptible to corrosion, especially pitting or intergranular corrosion. Generally, the pre-treatments exploiting the Cr (VI) compounds have been considered as the most effective conversion layers for protection against corrosion of this alloy due to the strong oxidation properties of Cr (VI). Unfortunately, as they cause problems on human health and the environment, new pre-treatments for corrosion protection have been actively developed in the last decade. This work presents a new approach to develop protective multilayer system of aluminum alloys AA2024 based on the inhibitor efficiency of cerium ions which are considered as a promising alternative to replace chromate compounds. Cerium ions were inserted into nanoclays platelets by cationic-exchange reactions (CeMMT). XRD analysis proved the presence of cerium ions intercalated into clays structure. EIS measurements and polarization curves highlighted a high corrosion inhibition effect of cerium-modified nanoclays. This effeciency can be related to the release of 60 % of cerium ions from CeMMT structure in sodium chloride solution as determined by UV-VIS measurements. EIS measurements revealed that hybrid sol-gel film doped with CeMMT improved barrier properties and anticorrosion protection of aluminum 2024 substrate. Scanning Vibrating Electrode Technique and salt spray test made on scratched sol-gel samples indicated a self-healing effect of cerium ions which provide an active corrosion protection to aluminum substrate. A second layer based on solvent-free epoxy coating was then applied onto hybrid sol-gel film. When combining cerium-nanocontainers doped sol-gel film with epoxy coating, EIS measurements showed a high potential anticorrosion property of this multilayer system to protect aluminum 2024. Results of this research indicated that epoxy coating combining sol-gel film incorporating cerium-nanocontainers can give an active corrosion protection to AA2024. Keyword: Sol-gel, AA2024, corrosion, montmorillonite, cerium salts, EIS, epoxy Acknowledgments: Authors would like to thank ARES/CCD (Belgium) for financial support. Reference: [1] R.L. Twite, G.P. Bierwagen, Progress in Organic Coatings 33 (1998) 91-100. [2] C. Motte, M. Poelman, A. Roobroeck, F. Deflorian, M.-G. Olivier, Progress in Organic Coatings 74 (2012) 326-333. [3] E.A. Matter, S. Kozhukharov, M. Machkova, V. Kozhukharov, Corrosion Science 62 (2012) 22-33 [4] R. Naderi, M. Fedel, F. Deflorian, M.Poelman, M.-G. Olivier, Surface and Coatings Technology 224 (2013) 93-100. [5] M.-E. Druart. I. Recloux, T.T. Thai, S.Ershov, R. Snyders,M.-G. Olivier, Surface and Coatings Technology 304 (2016) 40-50. [6] T.T. Thai, M.-E. Druart, Y. Paint, A.T. Trinh, M.-G. Olivier, Progress in Organic Coatings 121 (2018) 53-63. [7] A.T. Trinh, T.T. Thai, K.O Vu, T.X.H To, A.S. Nguyen, N. Caussé, N. Pébère, Surfaces and Interfaces 14 (2019) 26-33. [8] K.A. Yasakau, M.L. Zheludkevich, M.G.S. Ferreira, Surface Science and Electrochemistry, Reference Module in Chemistry, Molecular Science and Chemical Engineering (2018) 115-12

Hybrid sol-gel coatings doped with cerium -nanocontainers for active protection of aluminium alloys

peer reviewedAbstract Aluminum alloy 2024 (AA2024) is widely used as an important material for aerospace industry. Therefore, with high copper content, AA2024 is susceptible to corrosion, especially pitting or intergranular corrosion. Generally, the pre-treatments exploiting the Cr (VI) compounds have been considered as the most effective conversion layers for protection against corrosion of this alloy due to the strong oxidation properties of Cr (VI). Unfortunately, as they cause problems on human health and the environment, new pre-treatments for corrosion protection have been actively developed in the last decade. This work presents a new approach to develop protective pre-treatment for AA2024 based on the inhibitor efficiency of cerium ions which are considered as a promising alternative to replace chromate compounds. In this study, the inhibition properties of cerium salts for improving the anti-corrosion performance of AA2024 have been characterized by polarization curves and EIS measurements. Cerium ions were inserted into nanoclays platelets by cationic-exchange reactions (CeMMT). XRD analysis proved the presence of cerium ions intercalated into clay structure. EIS measurements and polarization curves highlighted a high corrosion inhibition effect of cerium-modified nanoclays. This effectiveness can be related to the release of 60% of cerium ions from CeMMT structure in sodium chloride as determined by UV-VIS measurements. Scanning Vibrating Electrode Technique and salt spray test made on scratched sol-gel samples indicated a self-healing effect of cerium ions which provide an active corrosion protection to aluminum substrate. EIS measurements revealed that hybrid sol-gel films doped with CeMMT improve barrier properties and anticorrosion protection of aluminum 2024 substrate. Results of this research indicated that sol-gel films incorporating cerium-nanocontainers can give an active corrosion protection to AA2024. Keywords. Sol-gel, AA2024, corrosion, montmorillonite, cerium salts, EIS

Hybrid sol-gel coatings doped with cerium nanocontainers for active corrosion protection of AA2024

peer reviewe

Student Satisfaction with Quality of Accounting and Auditing Education: The Case of Vietnam

This research is conducted to examine and evaluate determinants influencing the level of student satisfaction in the quality of auditing and accounting training at Vietnamese universities. Data were collected from 213 students of accounting and auditing field in three universities of National Economics University, University of Commerce and Academy of Finance. Exploratory factor analysis (EFA) and linear regression models were employed to determine the determinants influencing student satisfaction about quality of accounting and auditing. The findings show that the strongest impact on student satisfaction was the ability to serve; then training program; infrastructure component, and the last of teaching team. Based on the results, some recommendations are proposed for improving the satisfaction levels of students of accounting and auditing. Keywords: Quality of service; Quality of training; Satisfactio

The effects of firm’s innovation on customer’s loyalty: A case study of Saigon COOP

Identifying how the innovation affects the customer’s loyalty via the consumer perceived value and customer satisfactions from products or services provided by the Coopmart Retailers System in Ho Chi Minh City, Vietnam is the purpose of this search. This research also draws some suggestions for the firm’s future development. The research was conducted through 2 phases: a qualitative pilot study and quantitative analysis. The pilot study was conducted with 5 people who are working in Coopmart as department heads, deputy heads, and managers with at least 10 years’ experience. The qualitative survey will be distributed in the Ho Chi Minh City Coopmart system’s customers with member cards where 291 valid surveys were qualified for further analysis. This research’s insight is the impacts of innovation on the consumer perceived value, which has few focuses from previous studies. The outcome of the research has shown different aspects of the innovation to the consumer perceived value and customer satisfactions

HIGH PROTECTION PERFORMANCE OF COATING SYSTEMS BASED ON ZINC RICH PRIMER AND FLUOROPOLYMER COATING

Coating systems based on zinc rich primer and fluoropolymer top coat were exposed for 8 years at different atmospheric stations in Vietnam: Hanoi, Ha Long and Nha Trang. For comparison the coating system with zinc rich primer and polyurethane topcoat was also tested. The degradations of coating systems were evaluated by gloss measurement and electrochemical impedance spectroscopy. The obtained results show that coating systems with zinc rich primer and top coatings based on fluoropolymer  and polyurethane topcoats show very high weather resistance and corrosion protection performance, but the systems with fluoropolymer are better than coating system with polyurethane topcoat

Effect of cerium salts in the cut edge of zinc-based sacrificial coatings: influence of Al and Mg alloying elements on galvanic corrosion

peer reviewedZinc sacrificial coatings alloyed with Al and Mg for sacrificial protection of steel have been developed during the last decades and improved significantly the performance of steel against corrosion compared to pure zinc coating [1]. Despite the significant reinforcement achieved by this sacrificial coating, the cut edges or the appearance of scratches reaching the steel are the major problems due to the formation of galvanic coupling between steel and zinc-based coating. Therefore, it required supplementary active protection for galvanic coupled metallic materials. In previous work [2], cerium chloride has been reported as a promising corrosion inhibitor on the top surface of electro-galvanized steel. Thus, this study aims at investigating the protective properties of cerium salts for the cut edge of zinc-based sacrificial layers. Four types of the sacrificial coating were employed in this study: pure zinc coating on steel (fabricated by electrodeposition), Hot Dip Galvanized steel (HDG), ZA (9 wt. % Al), and ZAM (7 wt. % Al and 4 wt. % Mg). A galvanic corrosion prediction was established through the potentiodynamic polarization curves performed on the top surface of sacrificial coatings and steel in 0.1 M NaCl + 5.10-3 M cerium salts. Then, a local electrochemical technique (Scanning Vibrating Electrode Technique) was conducted on the cross-section of Zn-based coated steel in 0.015 M NaCl + 5.10-3 M inhibitor. In addition, cross-section characterizations of all substrates after 24 h of immersion in the electrolyte solution without and with inhibitor were analyzed by Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectroscopy.4617 - ARES PRD 2020 - Vietnam - Renforcement de l'expertise du centre de compétences en protection contre la corrosion et en éléctrochimie - Fédération Wallonie Bruxelles9. Industry, innovation and infrastructur

Effect of cerium salts on the cut-edge of zinc-based sacrificial coatings: Influence of Al and Mg alloying elements on galvanic corrosion

peer reviewedThe effect of cerium salts on the cut-edge of zinc-based sacrificial coated steel was investigated by theoretical approach (based on individual polarization curves on the top surface and by Scanning Vibrating Electrochemical Technique (SVET). In both approaches, cerium salts increase the galvanic corrosion of zinc-based sacrificial layer coupled with steel. Furthermore, the anion parts of cerium salts exhibited a synergistic accelerated effect of galvanic activity on the cross-section. The SVET results indicated that the addition of Al, Mg alloying elements promotes localized corrosion and influences the formation and distribution of corrosion products.4617 - ARES PRD 2020 - Vietnam - Renforcement de l'expertise du centre de compétences en protection contre la corrosion et en éléctrochimie - Fédération Wallonie Bruxelle

Improvement of adherence and anticorrosion properties of an epoxy-polyamide coating on steel by incorporation of an indole-3 butyric acid-modified nanomagnetite

In this study, synthesized magnetite (Fe 3 O 4 ) nanoparticles were treated with a corrosion inhibitor, indole-3 butyric acid (IBA) and incorporated in an epoxy-polyamide coating. The coating was applied on a carbon steel substrate. For comparison, coatings with- out particles or with nontreated Fe 3 O 4 particles were also prepared. The IBA-modified nanomagnetite (IBA–Fe 3 O 4 ) was characterized by infrared spec- troscopy and Zeta potential measurements. The inhibitive action of IBA was shown by electrochemical measurements (polarization curves) performed for a bare carbon steel in 0.1 M NaCl solution containing Fe 3 O 4 or IBA–Fe 3 O 4 nanoparticles. Adherence and anticorrosion properties of the epoxy-based coatings containing Fe 3 O 4 or IBA–Fe 3 O 4 were compared to those of the pure epoxy-polyamide resin by dry and wet adherence measurements and by salt spray test. The results showed significant improvement of the film adherence and higher corrosion protection of the carbon steel in the presence of IBA–Fe 3 O 4 . It was concluded that the IBA effect was restricted to the metal/coating interface