Attenuation coefficient for surface acoustic waves in fluid region

In recent years, surface acoustic wave devices used in bio-sensing applications have demonstrated high sensitivity in the detection of fluid properties such as density, viscosity, stream velocity. In this paper, a more effective measurement of the SAWsensorstructure is presented. It is reported that at density of 6 g/cm3, the amplitude of mechanical wave is excited while for electrical signal, attenuation at 3 g/cm3 reaches a peak.In our analysis, single–crystal Aluminium Nitride substrate is used. Several parameters of leaky waves including displacement, decay constant in the liquid media are analyzed

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

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

8-hydroxyquinoline-modified clay incorporated in an epoxy coating for the corrosion protection of carbon steel

In the present work, a well-known corrosion inhibitor (8-hydroxyquinoline (8HQ)) was inserted within the montmorillonite platelets (8HQ-MMT) and the modified clay was incorporated (3 wt.%) into a solvent-free epoxy coating which was afterwards deposited on carbon steel substrates. First, the inhibitive action of 8HQ was investigated by electrochemical methods carried out on a bare carbon steel rotating disk electrode in a 0.1 M NaCl solution. Then, electrochemical impedance measurements were performed to assess the effect of the 8HQ-MMT in the epoxy coating for the corrosion protection. The results were compared with a reference sample constituted by the epoxy coating containing an ammonium quaternary salt-modified clay. It was shown that the two coatings presented good barrier properties. Dry and wet adherence measurements revealed an improvement of the adherence when the 8HQ-MMT was incorporated into the coating by comparison with the reference sample. It was concluded that the 8HQ mainly had an effect at the metal/coating interface but its concentration was too low to afford significant corrosion protection of the carbon steel

Numerical study and experimental investigation of an electrohydrodynamic device for inertial sensing

We present a multi-physics simulation associated with experimental investigation for an electrohydrodynamic gyroscope based on ion wind corona discharge. The present device consisting of multiple point-ring electrodes generates a synthetic jet flow of ions for inertial sensing applications. Meanwhile the residual charge of jet is neutralized by an external ring electrode to guarantee the ion wind stable while circulating inside the device's channels. The working principle including the generation and then circulation of jet flow within the present device is firstly demonstrated by a numerical simulation and the feasibility and stability of the device are then successfully investigated by experimental work. Results show owing to the ion wind corona discharge based approach associated with new configuration, the present device is robust and consumes low energy

The immunogenicity of plant-based COE-GCN4pII protein in pigs against the highly virulent porcine epidemic diarrhea virus strain from genotype 2

Porcine epidemic diarrhea virus (PEDV) is a serious infectious causative agent in swine, especially in neonatal piglets. PEDV genotype 2 (G2) strains, particularly G2a, were the primary causes of porcine epidemic diarrhea (PED) outbreaks in Vietnam. Here, we produced a plant-based CO-26K-equivalent epitope (COE) variant from a Vietnamese highly virulent PEDV strain belonging to genotype 2a (COE/G2a) and evaluated the protective efficacy of COE/G2a-GCN4pII protein (COE/G2a-pII) in piglets against the highly virulent PEDV G2a strain following passive immunity. The 5-day-old piglets had high levels of PEDV-specific IgG antibodies, COE-IgA specific antibodies, neutralizing antibodies, and IFN-γ responses. After virulent challenge experiments, all of these piglets survived and had normal clinical symptoms, no watery diarrhea in feces, and an increase in their body weight, while all of the negative control piglets died. These results suggest that the COE/G2a-pII protein produced in plants can be developed as a promising vaccine candidate to protect piglets against PEDV G2a infection in Vietnam

Analysis of Students' Ability to Accept M-Learning Technology: An Exploratory Study from High Schools in Vietnam

With the availability of mobile devices capable of accessing the Internet in the Industry 4.0 era, M-learning methodology has been established. Based on the Technology Acceptance Model on technology adoption, this article analyses factors affecting the decision to use M-learning in Vietnam. The study used survey questionnaires with 238 students. The analysis shows to encourage students to choose to use M-learning is that educators need to pay attention to the design of appropriate courses to save time, improve learning efficiency, increase the mobility of learners and necessary introduce the convenience of courses to learners through many different channels

Factors Influencing the Use of Digital Games in Teaching: An Exploratory Study in the Context of Digital Transformation in Northern Vietnam

In recent years, "digital transformation" has been mentioned more and more in most social aspects of life, including education. Digital transformation takes advantage of every opportunity that technology offers and can create an ecosystem in digital education to connect teachers, learners, and countries with new learning models. Besides, a technology trend that has been gaining traction is "gamification." In many countries, games are used in education to engage students through digital media, utilizing platforms or applications that require digital devices such as tablets, smartphones, or computers. However, to be able to apply it in Vietnam, various issues need to be addressed. The study polled 245 secondary and high school teachers in Vietnam to find out what factors influence the use of digital games in teaching in high schools in Northern Vietnam. The findings revealed that the teacher factor significantly affects the usage of digital games in the classroom. In addition, there are other factors, such as information technology tools for digital games in education, external resources, and available inherent resources. This can be used as a guide for adjusting the curriculum or developing pedagogical training programs to improve innovation and effectively use digital games in teaching

Factors Influencing the Use of Digital Games in Teaching: An Exploratory Study in the Context of Digital Transformation in Northern Vietnam

In recent years, "digital transformation" has been mentioned more and more in most social aspects of life, including education. Digital transformation takes advantage of every opportunity that technology offers and can create an ecosystem in digital education to connect teachers, learners, and countries with new learning models. Besides, a technology trend that has been gaining traction is "gamification." In many countries, games are used in education to engage students through digital media, utilizing platforms or applications that require digital devices such as tablets, smartphones, or computers. However, to be able to apply it in Vietnam, various issues need to be addressed. The study polled 245 secondary and high school teachers in Vietnam to find out what factors influence the use of digital games in teaching in high schools in Northern Vietnam. The findings revealed that the teacher factor significantly affects the usage of digital games in the classroom. In addition, there are other factors, such as information technology tools for digital games in education, external resources, and available inherent resources. This can be used as a guide for adjusting the curriculum or developing pedagogical training programs to improve innovation and effectively use digital games in teaching