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Today, the development of the Internet and social networks has changed the lives of human beings. The ability of these technologies to connect people in real-time expands the influence of some people in the community. Therefore, this study is conducted to test whether customers change purchasing behavior in online environments under the impact of those influencers by using Technology Acceptance Model (TAM). The study conducted a survey of 503 Vietnameses on Google Form from November 2020 to mid-January 2021. The collected data were analyzed using AMOS 24 with CB-SEM analysis method. The results showed a positive relationship between influencers and customers’ online purchasing behavior. More specifically, customers are more likely to buy online if they trust influencers and their advertisements. This is the most influential factor among the three influencer traits (as source credibility): trustworthiness, expertise, and attractiveness. A remarkable point in this study is that Vietnamese people are more concerned with perceived ease of use when buying online than other factors in the TAM model. This is the basis for businesses to implement influencer marketing strategies and improve the competitiveness of their online business.

Objective: To evaluate the results of root canal obturation with Wave One (WO) canal shaping system and Gutta Thermafil obturation system. Design: Nonrandomized prospective experimental trial between December 2020 and March 2021. Setting: Central Military Hospital 108. Subject: 30 lower incisors extracted teeth without stem rupture, without root damage such as fracture, stray, fissure. Results: The number of slices with the biggest gaps accounting for 16.7%. The number of slices with the smallest gaps accounting for 10%. The number of slices with gaps over the total slices accounted for 14.4%. The void area in the apical slice was 1,413 ± 519.5 µm2 and the largest void area was 38,654.2 ± 3,939.8 µm2. Conclusion: Thermafil Gutta Percha has a good fit to the canal wall, which can seal the canal more easily and accurately.

In this paper, we report on the fabrication of a normally-off Al(Ga)N/GaN high electron mobility transistor with selective area sublimation under vacuum of the p type doped GaN cap layer. This soft method makes it possible to avoid damages otherwise induced by post processing with reactive ion etching techniques. The GaN evaporation selectivity is demonstrated on AlN as well as on AlGaN barrier layers. Furthermore, by properly choosing the AlGaN barrier thickness and composition it is possible to co-integrate a normally-off with a normally-on device on the same substrate. Finally, a local area regrowth of AlGaN can complement this process to increase the maximum drain current in the transistors.

In mobile base station antennas, linear array antennas are employing and asymmetrical radiation patterns are achieved. For multi frequency use, unequally spaced array configurations are preferable because of reducing grating lobes in higher frequency operations. Previously, radiation pattern synthesis methods were developed for equally spaced array configurations. In radiation pattern synthesis method, the least mean square (LMS) method was very conveniently used in mobile base station designing. The convenience of this method is obtaining array excitation coefficients by simply giving the objective radiation pattern. Moreover, the merit of this method is having the function of emphasizing design importance in the radiation angles that is called the weighting matrix. In this paper, a radiation pattern synthesis program based on LMS scheme is developed for unequally spaced array configuration. As an initial step, the accuracies of a developed program are examined. Through designing actual asymmetric radiation pattern with very low side lobe levels, the accuracies of program and effects of weighting matrix are ensured.

In this paper, the authors propose 2 structures of UWB antennas: one operates as a magnetic dipole with the size of 15 mm × 26 mm × 1.6 mm and the other operates as an electric dipole with the size of 9 mm × 64 mm × 1.6 mm. The proposed antennas can work in the frequency band 3.1–10.6 GHz with VSWR ≤ 2. They also can be used in MIMO system to reduce the mutual coupling between antenna elements.