This paper presents a novel design of quad-band rat-race couplers (RRCs) based on a modified T-shaped structure (MTSS). Two coupled lines are incorporated into the conventional dual-band T-shaped structure to create the MTSS, making it equivalent to a quarter-wavelength transmission line at four operating bands. The ABCD matrix method is applied to analyze the quad-band MTSS, deriving closed-form equations for calculating parameters of the structure. Then, a conventional RRC is separated into quarter-wavelength transmission lines, which are replaced by the proposed MTSS. To validate the design method, a quad-band RRC operating at 0.6, 1.196, 1.853, and 2.45 GHz is designed, fabricated, and tested. Simulation and experimental results demonstrate excellent agreement with theoretical prediction. The measured results show that input return loss exceeds 21.75 dB, isolation is greater than 21.6 dB, and insertion loss is less than 4.4 dB at all four operating frequencies. Phase deviations observed from the measured in-phase and out-phase responses are within 0o ± 4.6o and 180o ± 6.7o, respectively. Compared to most previously reported quad-band RRCs, the proposed circuit features a simple design and offers superior performance in isolation, return loss, and insertion loss.

The current study characterized voice onset time (VOT) and vowel onset fundamental frequency (F0) in the production of three Vietnamese alveolar stops (i.e. /t̪ʰ/, /t/, and /d/) by monolingual Vietnamese children and adults. Eighty Vietnamese children aged 3–7 years and 16 adults aged 22–44 years participated in this study. Unlike speakers of other languages with a three-way voicing contrast, Vietnamese children were able to produce distinct categories for the three Vietnamese stop categories by 3 years of age. However, differences in vowel onset F0 among the three voicing categories were not significant in any age group. These findings enhance our understanding of how Vietnamese children acquire three-way voicing contrast in stop production and offer broader insights into stop consonant acquisition across languages.

Tri-octahedral clay minerals have the potential to be used as CO2 sorbents at intermediate temperatures (200–400°C) owing to their thermal stability in this temperature range. In this study, Laponite RD®, a commercially synthesized hectorite (with Na+ as the exchangeable cation) was used to investigate its capacity of CO2 adsorption at 200°C and ambient pressure. Various cations such as Co2+, Ni2+, Mg2+ and Ca2+ were employed to exchange Na+, with the aim being to study their effects on the capacity for adsorbing CO2. The commercial sample showed an adsorption capacity of 144 µmolCO2 g–1. Most of the other exchanged samples displayed a lower quantity of CO2 adsorbed. An exception was the Ca2+-saturated sample, which exhibited a better performance (163 µmolCO2 g–1) compared with Laponite RD®. Thus, with its greater affinity towards CO2, such a sample could be a good candidate for CO2 capture. For all of the samples, most of the CO2 was desorbed, and the formation of carbonate bonds was not observed using Fourier-transform infrared spectroscopy, suggesting that the CO2 was mainly physisorbed.

Although nudibranchs are common and attractive animals, our understanding of these marine gastropods in Vietnam remains limited. Prior research has suggested that combining morphological examination with molecular analysis results in more accurate identification of nudibranchs. However, previous studies in Vietnam have typically relied solely on morphological methods for nudibranch identification. In this study, the nudibranch species Halgerda batangas was recorded in Vietnam for the first time based on both morphological and molecular approaches. Halgerda batangas was characterized by a network pattern consisting of orange lines, relatively low dorsal tubercles with red-orange caps and white basal rings, and an orange line along the foot margin. Molecular analysis corroborated the morphological findings. These results suggest that integrating morphological and molecular methods is an effective approach for identifying nudibranchs.

In the past, Vietnam was impacted by numerous epidemics, particularly during the Nguyễn Dynasty from 1802 to 1883. Based on data from the Đại Nam Thực Lục (1961) (The Veritable Records of the Great South), this article investigates the frequency and nature of these epidemics, identifies the types of common diseases at that time, and explores the underlying causes of these outbreaks. The study further examines the Nguyễn Dynasty's strategies for managing these health crises. During these outbreaks, the dynasty faced significant challenges, with frequent epidemics leading to high death rates, widespread social disruption, and economic decline. The dynasty's primary preventive measures, heavily reliant on spiritual practices like prayer, highlight the limited medical understanding at the time and the constraints of its socio-political framework. However, there was a progressive shift towards the incorporation of Western medical innovations, particularly in the vaccine approach to treat diseases like smallpox. This transition not only marked a critical evolution in the local healthcare approach but also set the stage for more systematic medical advancements in Vietnam during the colonial period (1884–1945).

Comparative studies have identified “Antigone's sisters” across the globe, excepting for Southeast Asia. Yet in Vietnam, there exists Kiều, the protagonist in Nguyễn Du's The Tale of Kiều, whose cultural significance is comparable to Antigone. What insights can be gained about feminist political power by comparing Antigone to Kiều? Proposing a shift in focus on Kiều and Antigone's love from the questions of who and why to how, the paper argues that their love shares three fundamental commonalities related to their living conditions, actions, and choices. First, they are women who live a life full of love in worlds where love is forbidden. Secondly, they are women who practice love during dark times. And third, they choose to love in unconventional ways, and in doing so, they engender possibilities, particularly in terms of contemplating the interplay between life, death, and freedom. This analysis demonstrates a multiplicity of women's love and the experiences that possess a transcultural dimension, one that signals a type of harmony in the resistance of war through love. Therefore, Antigone and Kiều represent a different direction of a feminist world-building project—that of constructing a world through love.

Globally, mental disorders account for almost 20% of disease burden and there is growing evidence that mental disorders are socially determined. Tackling the United Nations Sustainable Development Goals (UN SDGs), which address social determinants of mental disorders, may be an effective way to reduce the global burden of mental disorders. We conducted a systematic review of reviews to examine the evidence base for interventions that map onto the UN SDGs and seek to improve mental health through targeting known social determinants of mental disorders. We included 101 reviews in the final review, covering demographic, economic, environmental events, neighborhood, and sociocultural domains. This review presents interventions with the strongest evidence base for the prevention of mental disorders and highlights synergies where addressing the UN SDGs can be beneficial for mental health.

Because of their isolating capacity, smectite-rich clays have been proposed as buffer and backfill materials in high-level radioactive waste repositories. These repositories have to guarantee long-term safety for ~1 million years. Thermodynamics and kinetics of possible alteration processes of bentonite determine its long-term performance as a barrier material. Smectites in 25 different clays and bentonites were investigated in order to identify possible differences in their rates of alteration. These samples were saturated for 30 days in 1 M NaCl solution and deionized water, and then overhead rotated at speeds of 20 rpm and 60 rpm. Depending on the octahedral and interlayer composition, each of the smectites studied had specific rate of alteration, a so-called specific dissolution potential of smectite. The bentonites were classed as ‘slow-reacting bentonite’, ‘moderate-reacting bentonite’, or ‘fast-reacting bentonite’ corresponding to a relatively low (ΔP specific dissolution potential — <-5%), moderate (-5% < ΔP < -20%), or high specific dissolution potential (ΔP > -20%), respectively. The larger the amount of octahedral Fe and Mg compared to octahedral Al, the greater the specific dissolution potential. The present study found that the interlayer composition has a discernible impact on the rate of alteration. In experiments with rotation speeds of 60 rpm and a 1 M NaCl solution, Na+ was found to be the stabilizing cation in the interlayers of all the smectites. The Na-stabilizing mechanism was identified in only some of the smectites (type A) in experiments with 20 rpm (1 M NaCl solution). A second stabilization mechanism (by interlayer cations; Ca and Mg) was identified for other smectites (type B). Each bentonite has a specific rate of alteration. ‘Slow-reacting bentonite’ and clay with smectite-illite interstratifications are recommended as potential clay barriers in HLW repositories. The experimental and analytical procedures described here could be applied to potential barrier materials to identify ‘slow-reacting bentonite’.

The COVID-19 pandemic and ensuing restrictions/lockdowns have caused significant physical and psychological consequences for people with cognitive impairment who are heavily dependent on their care-givers. However, little is known about the impact on care-givers, the factors that exacerbate their situation and what supports they need. The aims of this paper are threefold: (a) to examine the impact of COVID-19 physical restrictions on both formal and informal care-givers of people with cognitive impairment; (b) to identify attributing factors influencing this impact; and (c) to recognise their support needs. Further, this paper informs future research, policy and practice. Guided by the Joanna Briggs Institute framework, a systematic review was conducted using a mixed-methods convergent integrated approach. Eight databases were searched using keywords related to COVID-19 restriction, dementia care-givers, impacts and care settings, followed by a manual search. The study was limited to primary research published in English between January 2020 and December 2021. Of the 840 records identified, 30 met the inclusion criteria. Service withdrawal and social distancing has effectively led to the reprivatisation of care to the family, particularly women. Care-givers experienced negative impacts including reduced psychological wellbeing and physical health, increased care burden and financial difficulties. A number of clinical attributes and socio-demographic factors influenced the COVID-19 impact on care-givers. Consequently, counselling services, assistance with care and financial support were identified as support needs. Implementation of new support and the strengthening of existing services are recommended to enhance resilience, build capacity to support care-givers in any given situation and mitigate the effects of future outbreaks.

The aim of this study is to analyse the changing patterns in the transmission of COVID-19 in relation to changes in Vietnamese governmental policies, based on epidemiological data and policy actions in a large Vietnamese province, Bac Ninh, in 2021. Data on confirmed cases from January to December 2021 were collected, together with policy documents. There were three distinct periods of the COVID-19 pandemic in Bac Ninh province during 2021. During the first period, referred to as the ‘Zero-COVID’ period (01/04–07/04/2021), there was a low population vaccination rate, with less than 25% of the population receiving its first vaccine dose. Measures implemented during this period focused on domestic movement restrictions, mask mandates, and screening efforts to control the spread of the virus. The subsequent period, referred to as the ‘Transition’ period (07/05–10/22/2021), witnessed a significant increase in population vaccination coverage, with 80% of the population receiving their first vaccine dose. During this period, several days passed without any reported COVID-19 cases in the community. The local government implemented measures to manage domestic actions and reduce the time spent in quarantine, and encouraged home quarantining for the close contacts of cases with COVID-19. Finally, the ‘New-normal’ stage (10/23–12/31/2021), during which the population vaccination coverage with a second vaccine dose increased to 70%, and most of the mandates for the prevention and control of COVID-19 were reduced. In conclusion, this study highlights the importance of governmental policies in managing and controlling the transmission of COVID-19 and provides insights for developing realistic and context-specific strategies in similar settings.

In this study, a novel, cost-effective miniaturized tag antenna was developed for applications on the human body. To achieve impedance matching with the complex conjugate impedance of the Monza-4 tag chip (7.17–j74.22 Ω at 915 MHz), the proposed structure was configured by coarsely tuning the positions of vias and fine-tuning the small gaps of its coupled patches. For further reducing the profile and dimensions of the antenna, a design technique based on the three-dimensional dipole antenna current distribution was used. The proposed antenna configuration was not only miniaturized but also achieved a long stable reading distance (>5.0 m) and a wide impedance bandwidth of 71 MHz or 7.65% (covering the ultrahigh frequency radio frequency identification ranges in most regions), regardless of the location of the tag on the human body. Experiments were conducted to validate the simulated results, and adequate agreement was found between the simulated results and the measured results.

OBJECTIVES/GOALS: COVID-19 disproportionately affects patients with prior health conditions and those living at a lower socioeconomic status. Persons living with HIV (PLWH) are infected with SARS-CoV-2 at a higher rate than seronegative patients. Risk factors and incidence of post-COVID-19 comorbidities in PLWH, specifically, are still unknown METHODS/STUDY POPULATION: We will study PLWH enrolled in the Emory Centers for AIDS Research (CFAR) Registry who receive care at the Grady Ponce de Leon Center in Atlanta, Georgia to 1) investigate the incidence of, and 2) identify risk factors that predispose PLWH to post-COVID-19 comorbidities. All PLWH with documented COVID-19 (by positive SARS-CoV-2 PCR or antigen test) between March 1, 2020, and September 30, 2021, with a clinic visit within 12 months will be included. We will identify comorbidities using problem list diagnoses and ICD9/10 codes. With a predicted sample size of 395, we will use a Cox proportional hazards model for time-to-detection of comorbidity, and bivariate and multivariate logistic regression models to identify predictors of incident comorbidity within 12 months of COVID-19. RESULTS/ANTICIPATED RESULTS: o Previous work demonstrated that in PLWH, age and non-AIDS comorbidities, but not HIV-related factors, were associated with hospitalization for COVID-19 in a dose dependent fashion.18 We anticipate that rate of incident comorbidities will be significantly higher in PLWH after COVID-19 compared to PLWH without a history of COVID-19. We also expect that pre-existing comorbidities including obesity and cardiovascular disease, male sex, Black race, and older age are associated with higher incidence of post-COVID-19 comorbidities in PLWH. When stratifying by organ system, we also anticipate that prior comorbidities of an organ system will predispose patients to later complications of that same system. DISCUSSION/SIGNIFICANCE: By understanding the incidence and risk factors associated with developing post-COVID-19 comorbiditieswe can improve guidelines for treatment of groups experiencing the disproportionate impact of co-infection with HIV and SARS-CoV-2.

Objectives: At the onset of COVID-19, whenever SARS-CoV-2 was detected at Children’s Hospital 1 (CH1), the related department or building was closed for extensive tracing, testing, and medical isolation. This process disrupted hospital activities, reduced the efficiency of patient care, and used medical resources. To address this problem, CH1 implemented a system of grouping inpatients to color-coded areas from June to December 2021. Methods: In this retrospective study, we describe the system of grouping inpatients to color-coded areas based on SARS-CoV-2 test result at a 1,600-bed, national pediatric hospital in Ho Chi Minh City. Results: Inpatients were first separated into those with or without respiratory symptoms, and secondly to different color-coded areas based on SARS-CoV-2 test result and hospitalization length: red zone (days 1–3), orange zone (days 3–7), and green zone (day 7 onward). Prior to admission, all patients were tested with a SARS-CoV-2 rapid diagnostic test. If negative, the patient was admitted to the red zone. On days 3 and 7 of hospitalization, the patient was tested using a pooled RT-PCR method. Patients negative on day 3 were relocated to the orange zone; patients negative on day 7 were relocated to the green zone. A patient with a positive test result at any time point was transferred to a COVID-19 zone. One caregiver was allowed to stay with 1 patient with similar testing regimen. A mobile transportation team was set up to deliver food and other necessities; thus, movement was restricted and interaction was prevented among zones. After this system was implemented, COVID-19 cases were detected early, with most positive cases in the red zone (19.6%) and the orange zone (2.8%), with only 1 case in the green zone (0.7%). Conclusions: The system of grouping patients to color-coded areas helped prevent SARS-CoV-2 transmission within the hospital, allowing undisrupted operation.

Objectives: In early 2021, when the COVID-19 vaccine was scarce in Vietnam, healthcare workers (HCWs) were prioritized for vaccination due to high risk of occupational exposure. However, there is some COVID-19 vaccine hesitancy within HCW communities. Assessing COVID-19 severity among vaccinated and nonvaccinated HCWs would contribute essential information to assure people of vaccine effectiveness and reduce vaccine hesitancy. Methods: We conducted a descriptive cross-sectional study at the National Hospital for Tropical Diseases in Hanoi, Vietnam, from May to June 2021. Clinical and epidemiological data from HCWs with positive polymerase chain reaction (PCR) results were collected. The severity of symptoms were classified according to Vietnam Ministry of Health guideline (Decision no. 3416 issued  July 14, 2021) into 5 categories: asymptomatic, mild, moderate, severe, and critical conditions Results: Overall, 25 HCWs qualified for this study (14 women and 11 men), with a median age of 31 years. Among them, 3 HCWs were infected due to community exposure, and the rest were infected due to occupational exposure. Also, 3 HCWs received the Astra Zeneca vaccine before being infected with SARS-CoV-2 (one fully vaccinated with 2 doses and the other 2 had had the first dose). Categorized by the severity of infection, 28% were asymptomatic, 44% had mild symptoms, 20% had moderate symptoms, and 8% experienced severe symptoms. All 3 vaccinated HCWs showed only mild symptoms. Cough and sore throat were the main symptoms recorded (60%), followed by fever (56%). Blood test results did not show significant differences between the severe and mild COVID-19 groups. Conclusions: COVID-19 vaccination reduced the severity of COVID-19 in this small sample of HCWs. Full COVID-19 vaccination is strongly recommended for HCWs to reduce the spread of COVID-19 and to limit the number of cases with severe disease.

Objectives: SARS-CoV-2 is a novel and highly infectious virus. An effective response requires rapid training of healthcare workers (HCWs). We measured the change in knowledge related to COVID-19 and associated factors before and after training of HCWs in Vietnam. Methods: A quasi-experimental design was used to evaluate HCW knowledge related to prevention and control of SARS-CoV-2 before and after attending a 2-day training-of-trainers course. Between June and September 2020, 963 HCWs from 194 hospitals in 21 provinces received the training. HCW knowledge was assessed using a 20-item questionnaire consisting of multiple-choice questions at the beginning and closing of the training course. A participant received 1 point for each correct answer. He or she was considered to have improved knowledge the posttest score was higher than the pretest score with a score ≥15 on the posttest. We applied the McNemar test and logistic regression model to test the level of association between demographic factors and change in knowledge of COVID-19. Results: Overall, 100% of HCWs completed both the pretest and posttest. At baseline, only 14.7% scored ≥15. Following the training, 78.4% scored ≥15 and 64.3% had improved knowledge according to the predetermined definition. Questions related to the order of PPE donning and doffing and respiratory specimen collection procedures were identified as having the greatest improvement (44.6% and 60.7%, respectively). Being female (OR, 1.5; 95% CI, 1.1–2.0), having a postgraduate degree (OR, 2.5; 95% CI, 1.4–4.4), working in a nonmanager position (OR, 1.5; 95% CI, 1.1–2.1), previous contact with a COVID-19 patient (OR, 1.5; 95% CI, 1.1–2.0), and working in northern Vietnam (OR, 2.0; 95% CI, 1.4–2.6), were associated with greater knowledge improvement. Conclusions: Most HCWs demonstrated improved knowledge of COVID-19 prevention and control after attending the training. Particular groups may benefit from additional training: those who are male, leaders and managers, those who hold an undergraduate degree, and those who work in the southern provinces.