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A simple design of a broadband multifunctional polarization converter using an anisotropic metasurface for X-band application is proposed. The proposed polarization converter consists of a periodic array of the two-corner-cut square patch resonators based on the FR-4 substrate that achieves both cross-polarization and linear-to-circular polarization conversions. The simulated results show that the polarization converter displays the linear cross-polarization conversion in the frequency range from 8 to 12 GHz with the polarization conversion efficiency above 90%. The efficiency is kept higher than 80% with wide incident angle up to 45°. Moreover, the proposed design achieves the linear-to-circular polarization conversion at two frequency bands of 7.42–7.6 GHz and 13–13.56 GHz. A prototype of the proposed polarization converter is fabricated and measured, showing a good agreement between the measured and simulated results. The proposed polarization converter exhibits excellent performances such as simple structure, multifunctional property, and large cost-efficient bandwidth and wide incident angle insensitivity in the linear cross polarization conversion, which can be useful for X-band applications. Furthermore, this structure can be extended to design broadband polarization converters in other frequency bands.

A simple design of terahertz polarization converter has attracted great attention owing to the applicability of terahertz technology in broad fields such as imaging, non-destructive sensing, and communications, but remains a key challenge to simultaneously achieve both wide bandwidth and high conversion efficiency. Here we report a single-layer metasurface-based polarization converter formed by a combination of different resonator shapes that realizes cross-polarization conversion and achieves an ultra-broadband and high conversion efficiency with a wide oblique incidence in the terahertz region from 1.35 THz to 3.55 THz. The high performance and physical mechanism attributed to both electric and magnetic resonances of this proposed structure are guaranteed and analyzed by numerical study. Our design structure provides the frequency tunability to other frequency bands and possesses promising applications in terahertz polarization-control devices.

Mpox was diagnosed in 2 women returning to Vietnam from the United Arab Emirates. The monkeypox viruses belonged to an emerging sublineage, A.2.1, distinct from B.1, which is responsible for the ongoing multicountry outbreak. Women could contribute to mpox transmission, and enhanced genomic surveillance is needed to clarify pathogen evolution.

Comprehensive profiling of actionable mutations in non-small cell lung cancer (NSCLC) is vital to guide targeted therapy, thereby improving the survival rate of patients. Despite the high incidence and mortality rate of NSCLC in Vietnam, the actionable mutation profiles of Vietnamese patients have not been thoroughly examined. Here, we employed massively parallel sequencing to identify alterations in major driver genes ( EGFR , KRAS, NRAS, BRAF , ALK and ROS1 ) in 350 Vietnamese NSCLC patients. We showed that the Vietnamese NSCLC patients exhibited mutations most frequently in EGFR (35.4%) and KRAS (22.6%), followed by ALK (6.6%), ROS1 (3.1%), BRAF (2.3%) and NRAS (0.6%). Interestingly, the cohort of Vietnamese patients with advanced adenocarcinoma had higher prevalence of EGFR mutations than the Caucasian MSK-IMPACT cohort. Compared to the East Asian cohort, it had lower EGFR but higher KRAS mutation prevalence. We found that KRAS mutations were more commonly detected in male patients while EGFR mutations was more frequently found in female. Moreover, younger patients (<61 years) had higher genetic rearrangements in ALK or ROS1 . In conclusions, our study revealed mutation profiles of 6 driver genes in the largest cohort of NSCLC patients in Vietnam to date, highlighting significant differences in mutation prevalence to other cohorts.

Automated learning analytics is becoming an essential topic in the educational area, which needs effective systems to monitor the learning process and provides feedback to the teacher. Recent advances in visual sensors and computer vision methods enable automated monitoring of behavior and affective states of learners at different levels, from university to pre-school. The objective of this research was to build an automatic system that allowed the faculties to capture and make a summary of student behaviors in the classroom as a part of data acquisition for the decision making process. The system records the entire session and identifies when the students pay attention in the classroom, and then reports to the facilities. Our design and experiments show that our system is more flexible and more accurate than previously published work.

Three new assassin bug species of the genus Biasticus Stål, 1867 are recognized in Vietnam based on morphological examination, morphometric and molecular phylogenetic analyses, and described as Biasticus taynguyenensis Ha, Truong & Ishikawa, sp. nov. , Biasticus griseocapillus Ha, Truong & Ishikawa, sp. nov. , and Biasticus luteicollis Ha, Truong & Ishikawa, sp. nov. The conspecific male and female associations of the new species were confirmed by phylogenetic analyses and DNA barcoding of the mitochondrial 16S rDNA and COI genes. All three new species are presently restricted to the Central Highlands, Vietnam (Kon Chu Rang NR, Gia Lai Province, and Chu Yang Sin NP, Dak Lak Province).

This study investigates the corrosion behavior of API-grade steels micro-alloyed with Cr, Mo, and V in a 3.5 wt.% NaCl solution through a combined experimental and theoretical approach. Electrochemical techniques, weight loss evaluations, and surface analyses were complemented by density functional theory (DFT) calculations to elucidate initial adsorption and oxidation mechanisms. Cr additions significantly enhanced corrosion resistance by promoting the formation of compact and protective oxide layers such as α-(Fe, Cr)OOH and Fe x Cr 3-x O 4 (1 ≤  x  ≤ 1.5). Co-addition of V increased initial surface reactivity through strong oxygen adsorption and charge transfer, facilitating early-stage oxidation, followed by a reduction in subsequent anodic dissolution due to elevated Fe escape energy. V suppressed coarse M 7 C 3 carbide formation by favoring fine V-carbide precipitates, which may retain more Cr in solid solution. Mo addition, even in small quantities, further improved corrosion resistance by enhancing water adsorption and stabilizing surface oxides with minimal charge transfer. However, excessive carbide formation in steels with higher Cr and slightly elevated C markedly reduced corrosion resistance, which was effectively mitigated by water quenching. The quenched sample exhibited the most uniform corrosion scale and the highest resistance. These findings provide practical insight into alloying and thermal processing strategies for enhancing corrosion resistance in marine environments.

In 2022, we established a residual sample serosurveillance program in Ho Chi Minh City, Vietnam. During September 2022-April 2024, we found low measles antibody seroprevalence in children in the city's western region, where a measles outbreak began in May 2024. Serosurveillance could be a useful tool for outbreak prediction and prevention.

We recently published the description of three new species of the genus Biasticus Stål, 1867 (Insecta, Heteroptera, Reduviidae, Harpactorinae) from Central Highlands, Vietnam (Ha NL, Truong XL, Ishikawa T, Jaitrong W, Lee CF, Chouangthavy B, Eguchi K 2022). However, the first author made mistakes when indicating the deposition of the holotype and paratype of the three new species regardless of some regulations and agreements about those specimens. In this corrigendum, we made a revision of the status of the holotype and paratype deposition.