Age-time-specific transmission of hand-foot-and-mouth disease enterovirus serotypes in Vietnam: A catalytic model with maternal immunity.

Hand, foot and mouth disease (HFMD) is highly prevalent in the Asia Pacific region, particularly in Vietnam. To develop effective interventions and efficient vaccination programs, we inferred the age-time-specific transmission patterns of HFMD serotypes enterovirus A71 (EV-A71), coxsackievirus A6 (CV-A6), coxsackievirus A10 (CV-A10), coxsackievirus A16 (CV-A16) in Ho Chi Minh City, Vietnam from a case data collected during 2013-2018 and a serological survey data collected in 2015 and 2017. We proposed a catalytic model framework with good adaptability to incorporate maternal immunity using various mathematical functions. Our results indicate the high-level transmission of CV-A6 and CV-A10 which is not obvious in the case data, due to the variation of disease severity across serotypes. Our results provide statistical evidence supporting the strong association between severe illness and CV-A6 and EV-A71 infections. The HFMD dynamic pattern presents a cyclical pattern with large outbreaks followed by a decline in subsequent years. Additionally, we identify the age group with highest risk of infection as 1-2 years and emphasise the risk of future outbreaks as over 50% of children aged 6-7 years were estimated to be susceptible to CV-A16 and EV-A71. Our study highlights the importance of multivalent vaccines and active surveillance for different serotypes, supports early vaccination prior to 1 year old, and points out the potential utility for vaccinating children older than 5 years old in Vietnam.

A combination of annual and nonannual forces drive respiratory disease in the tropics.

INTRODUCTION: It is well known that influenza and other respiratory viruses are wintertime-seasonal in temperate regions. However, respiratory disease seasonality in the tropics is less well understood. In this study, we aimed to characterise the seasonality of influenza-like illness (ILI) and influenza virus in Ho Chi Minh City, Vietnam. METHODS: We monitored the daily number of ILI patients in 89 outpatient clinics from January 2010 to December 2019. We collected nasal swabs and tested for influenza from a subset of clinics from May 2012 to December 2019. We used spectral analysis to describe the periodic signals in the system. We evaluated the contribution of these periodic signals to predicting ILI and influenza patterns through lognormal and gamma hurdle models. RESULTS: During 10 years of community surveillance, 66 799 ILI reports were collected covering 2.9 million patient visits; 2604 nasal swabs were collected, 559 of which were PCR-positive for influenza virus. Both annual and nonannual cycles were detected in the ILI time series, with the annual cycle showing 8.9% lower ILI activity (95% CI 8.8% to 9.0%) from February 24 to May 15. Nonannual cycles had substantial explanatory power for ILI trends (ΔAIC=183) compared with all annual covariates (ΔAIC=263) in lognormal regression. Near-annual signals were observed for PCR-confirmed influenza but were not consistent over time or across influenza (sub)types. The explanatory power of climate factors for ILI and influenza virus trends was weak. CONCLUSION: Our study reveals a unique pattern of respiratory disease dynamics in a tropical setting influenced by both annual and nonannual drivers, with influenza dynamics showing near-annual periodicities. Timing of vaccination campaigns and hospital capacity planning may require a complex forecasting approach.

Health and Economic Benefits of Air Pollution Reductions in Vietnam During 2020-2021.

Objectives: This paper explores the potential reduction in the number of deaths and the corresponding economic benefits in Vietnam that could have arisen from the decreased in concentrations of particulate matter with a diameter of 2.5 µm or less (PM2.5) and nitrogen dioxide (NO2). Methods: Using Global Exposure Mortality Models, we estimated the potential health and economic benefits on people aged 25 and above across Vietnam's 63 provinces. The counterfactual scenario assumed reducing PM2.5 and NO2 concentrations to levels observed during the two COVID-19 epidemic waves in 2021 with national lockdowns and activity restrictions. Results: In 2019, PM2.5 concentrations ranged from 12.8 to 40.8 µg/m3 while NO2 concentrations ranged between 2.9 and 36.98 µg/m3. The reduced levels of PM2.5 and NO2 resulted in 3,807 (95% CI: 2,845-4,730) and 2,451 (95% CI: 2,845-4,730) avoided deaths of adults aged 25 and above due to non-injury-related causes, respectively. Considering that every prevented death represents potential tangible and intangible cost savings, reduced levels of PM2.5 and NO2 concentrations during COVID-19 restrictions would have resulted in economic benefits of $793.0 million (95% CI: 592.7-985.4) and $510.6 million (95% CI: 381.3-634.9), respectively. Conclusion: The COVID-19 lockdown led to decreased PM2.5 and NO2 concentrations, benefiting health and economy in Vietnam. Our findings highlight the potential advantages of implementing air quality control policies in the country.

What matters most? A qualitative study exploring priorities for supportive interventions for people with tuberculosis in urban Viet Nam.

INTRODUCTION: The health and economic burden of tuberculosis (TB) in urban Viet Nam is high. Social protection and support interventions can improve treatment outcomes and reduce costs. However, evidence regarding optimal strategies in this context is lacking. This study aimed to increase understanding of what people with TB and healthcare providers (HCPs) perceive as important to improve TB treatment outcomes and reduce costs. METHODS: We conducted qualitative focus group discussions (seven groups, n=30) and key informant interviews (n=4) with people with drug-susceptible and multidrug-resistant TB and HCPs in Ha Noi and Ho Chi Minh City. Topic guides covered perspectives on and prioritisation of different forms of social protection and support. Data were analysed using reflexive thematic analysis and interpreted using a Framework for Transformative Social Protection. RESULTS: We identified three themes and seven subthemes. The first theme, 'Existing financial safety nets are essential, but could go further to support people affected by TB', highlights that support to meet the medical costs of TB treatment and flexible cash transfers are a priority for people with TB and HCPs. The second, 'It is important to promote "physical and spiritual health" during TB treatment', demonstrates that extended psychosocial and nutritional support would encourage people with TB during their treatment. The third, 'Accessibility and acceptability are critical in designing social support interventions for people with TB', shows the importance of ensuring that support is accessible and proportional to the needs of people with TB and their families. CONCLUSIONS: Accessible interventions that incorporate financial risk protection, nutritional and psychosocial support matter most to people with TB and HCPs in urban Viet Nam to improve their treatment outcomes and reduce catastrophic costs. This study can inform the design of stronger person-centred interventions to advance progress towards the goals of the WHO's End TB Strategy.

New Guaiane-Type Sesquiterpene and Norsesquiterpene from Alisma plantago-aquatica and Their Xanthine Oxidase Inhibitory Activity.

A new sesquiterpene (1) and a new norsesquiterpene (2) belonging guaiane-type skeleton together with six known compounds (3-8) were isolated from the rhizomes of Alisma plantago-aquatica. Their structures were determined by HR-ESI-MS, 1D and 2D NMR spectroscopic methods. Absolute configurations of new compounds were established by experimental and TD-DFT computational ECD spectra. Compounds 1-8 exhibited xanthine oxidase inhibitory activity with their IC50 values in range of 9.4-66.7 µM. The sesquiterpenoids 1-5 displayed the inhibitory activity and hence they could be potential xanthine oxidase inhibitors from A. plantago-aquatica.

Ante-, Peri-, and Neonatal Factors Associated with Autism Spectrum Disorders in Vietnam: A Population-Based Cross-Sectional Survey.

Background: Autism Spectrum Disorders (ASDs) are common behavioral syndromes but limited critical evidence in Vietnam. This study aimed to identify ante-, peri- and neonatal factors for ASDs amongst children in Vietnam. Methods: This population-based study applied the cross-sectional design with a multistage sampling in 21 urban and rural districts in seven cities/provinces in Vietnam during 2017-2018. Overall, 42,551 children age 18 to 30 months were enrolled in the study. Two phases of assessment using Modified Checklist for Autism in Toddlers (M-CHAT) for screening and diagnostic assessment using Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for confirmation. We employed univariate and binary logistic regression to identify. Results: Our study showed a fast-growing trend of ASDs amongst children age 18 and 30 months (75.8 per 10,000 individuals). Nine ante-, peri-, and neonatal factors were associated with ASDs: five factors of antenatal period (history of miscarriage/abortion or stillbirth, children conceived by assisted reproduction technologies, having cold, flu or acquiring virus during pregnancy, having gestational diabetes, toxemia, high blood pressure or pre-eclampsia during pregnancy, and having stress or mental disorders during pregnancy); one factors of perinatal period (mode of delivery); and three factors of neonatal period (jaundice, respiratory distress, and newborn seizures). Conclusion: This first large-scale survey in Vietnam confirms some prenatal, perinatal, and postnatal factors with ASDs amongst children age 18 and 30 months. Future interventions should focus on these factors to early diagnosis and intervention to improve functional outcomes for risky children.

Development of a thermochromic lateral flow assay to improve sensitivity for dengue virus serotype 2 NS1 detection.

Dengue disease is a viral infection that has been widespread in tropical regions, such as Southeast Asia, South Asia and South America. A worldwide effort has been made over a few decades to halt the spread of the disease and reduce fatalities. Lateral flow assay (LFA), a paper-based technology, is used for dengue virus detection and identification because of its simplicity, low cost and fast response. However, the sensitivity of LFA is relatively low and is usually insufficient to meet the minimum requirement for early detection. In this study, we developed a colorimetric thermal sensing LFA format for the detection of dengue virus NS1 using recombinant dengue virus serotype 2 NS1 protein (DENV2-NS1) as a model antigen. Plasmonic gold nanoparticles, including gold nanospheres (AuNSPs) and gold nanorods (AuNRs), and magnetic nanoparticles (MNPs), namely iron oxide nanoparticles (IONPs) and zinc ferrite nanoparticles (ZFNPs), were studied for their thermal properties for sensing assays. AuNSPs with 12 nm diameter were chosen due to their great photothermal effect against light-emitting diodes (LEDs). In the thermal sensing assay, a thermochromic sheet is used as a temperature sensor transforming heat into a visible colour. In the typical LFA, the test line is visible at 6.25 ng mL-1 while our thermal sensing LFA offers a visual signal that can be observed at as low as 1.56 ng mL-1. The colorimetric thermal sensing LFA is capable of reducing the limit of detection (LOD) of DENV2-NS1 by 4 times compared to the typical visual readout. The colorimetric thermal sensing LFA can enhance the sensitivity of detection and deliver visuality to the user to translate without the need for an infrared (IR) camera. It has the potential to expand the utilities of LFA and satisfy early diagnostic applications.

Enhanced detoxification of Cr6+ by Shewanella oneidensis via adsorption on spherical and flower-like manganese ferrite nanostructures.

Maximizing the safe removal of hexavalent chromium (Cr6+) from waste streams is an increasing demand due to the environmental, economic and health benefits. The integrated adsorption and bio-reduction method can be applied for the elimination of the highly toxic Cr6+ and its detoxification. This work describes a synthetic method for achieving the best chemical composition of spherical and flower-like manganese ferrite (MnxFe3-xO4) nanostructures (NS) for Cr6+ adsorption. We selected NS with the highest adsorption performance to study its efficiency in the extracellular reduction of Cr6+ into a trivalent state (Cr3+) by Shewanella oneidensis (S. oneidensis) MR-1. MnxFe3-xO4 NS were prepared by a polyol solvothermal synthesis process. They were characterised by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectrometry (XPS), dynamic light scattering (DLS) and Fourier transform-infrared (FTIR) spectroscopy. The elemental composition of MnxFe3-xO4 was evaluated by inductively coupled plasma atomic emission spectroscopy. Our results reveal that the oxidation state of the manganese precursor significantly affects the Cr6+ adsorption efficiency of MnxFe3-xO4 NS. The best adsorption capacity for Cr6+ is 16.8 ± 1.6 mg Cr6+/g by the spherical Mn0.22+Fe2.83+O4 nanoparticles at pH 7, which is 1.4 times higher than that of Mn0.8Fe2.2O4 nanoflowers. This was attributed to the relative excess of divalent manganese in Mn0.22+Fe2.83+O4 based on our XPS analysis. The lethal concentration of Cr6+ for S. oneidensis MR-1 was 60 mg L-1 (determined by flow cytometry). The addition of Mn0.22+Fe2.83+O4 nanoparticles to S. oneidensis MR-1 enhanced the bio-reduction of Cr6+ 2.66 times compared to the presence of the bacteria alone. This work provides a cost-effective method for the removal of Cr6+ with a minimum amount of sludge production.

Correction: Enhanced detoxification of Cr6+ by Shewanella oneidensis via adsorption on spherical and flower-like manganese ferrite nanostructures.

[This corrects the article DOI: 10.1039/D2NA00691J.].

A Genetic Algorithm for Universal Optimization of Ultrasensitive Surface Plasmon Resonance Sensors with 2D Materials.

We present a general optimization technique for surface plasmon resonance, (SPR) yielding a range of ultrasensitive SPR sensors from a materials database with an enhancement of ∼100%. Applying the algorithm, we propose and demonstrate a novel dual-mode SPR structure coupling SPP and a waveguide mode within GeO2 featuring an anticrossing behavior and an unprecedented sensitivity of 1364 deg/RIU. An SPR sensor operating at wavelengths of 633 nm having a bimetal Al/Ag structure sandwiched between hBN can achieve a sensitivity of 578 deg/RIU. For a wavelength of 785 nm, we optimized a sensor as a Ag layer sandwiched between hBN/MoS2/hBN heterostructures achieving a sensitivity of 676 deg/RIU. Our work provides a guideline and general technique for the design and optimization of high sensitivity SPR sensors for various sensing applications in the future.

Greatly Enhanced Resonant Exciton-Trion Conversion in Electrically Modulated Atomically Thin WS2 at Room Temperature.

Excitonic resonance in atomically thin semiconductors offers a favorite platform to study 2D nanophotonics in both classical and quantum regimes and promises potentials for highly tunable and ultra-compact optical devices. The understanding of charge density dependent exciton-trion conversion is the key for revealing the underlaying physics of optical tunability. Nevertheless, the insufficient and inefficient light-matter interactions hinder the observation of trionic phenomenon and the development of excitonic devices for dynamic power-efficient electro-optical applications. Here, by engaging an optical cavity with atomically thin transition metal dichalcogenides (TMDCs), greatly enhanced exciton-trion conversion is demonstrated at room temperature (RT) and achieve electrical modulation of reflectivity of ≈40% at exciton and 7% at trion state, which correspondingly enables a broadband large phase tuning in monolayer tungsten disulfide. Besides the absorptive conversion, ≈100% photoluminescence conversion from excitons to trions is observed at RT, illustrating a clear physical mechanism of an efficient exciton-trion conversion for extraordinary optical performance. The results indicate that both excitons and trions can play significant roles in electrical modulation of the optical parameters of TMDCs at RT. The work shows the real possibility for realizing electrical tunable and multi-functional ultra-thin optical devices using 2D materials.

A combination of annual and nonannual forces drive respiratory disease in the tropics.

Background: It is well known that influenza and other respiratory viruses are wintertime-seasonal in temperate regions. However, respiratory disease seasonality in the tropics remains elusive. In this study, we aimed to characterize the seasonality of influenza-like illness (ILI) and influenza virus in Ho Chi Minh City (HCMC), Vietnam. Methods: We monitored the daily number of ILI patients in 89 outpatient clinics from January 2010 to December 2019. We collected nasal swabs and tested for influenza from a subset of clinics from May 2012 to December 2019. We used spectral analysis to describe the periodicities in the system. We evaluated the contribution of these periodicities to predicting ILI and influenza patterns through lognormal and gamma hurdle models. Findings: During ten years of community surveillance, 66,799 ILI reports were collected covering 2.9 million patient visits; 2604 nasal swabs were collected 559 of which were PCR-positive for influenza virus. Both annual and nonannual cycles were detected in the ILI time series, with the annual cycle showing 8.9% lower ILI activity (95% CI: 8.8%-9.0%) from February 24 to May 15. Nonannual cycles had substantial explanatory power for ILI trends (ΔAIC = 183) compared to all annual covariates (ΔAIC = 263). Near-annual signals were observed for PCR-confirmed influenza but were not consistent along in time or across influenza (sub)types. Interpretation: Our study reveals a unique pattern of respiratory disease dynamics in a tropical setting influenced by both annual and nonannual drivers. Timing of vaccination campaigns and hospital capacity planning may require a complex forecasting approach.

Seroprotection against tetanus in southern Vietnam.

BACKGROUND: Ongoing tetanus cases and sporadic outbreaks of vaccine-preventable diseases associated with routine vaccination programmes remain problems in many low and middle-income countries, including Vietnam. With no human-to-human transmission or natural immunity, tetanus antibody levels indicate both individual risk of tetanus and gaps in vaccination programmes. METHODS: To investigate gaps in immunity to tetanus in Vietnam, a country with a historically high level of tetanus vaccination coverage, tetanus antibodies were measure by ELISA from samples selected from a long-term serum bank, established for the purposes of general-population seroepidemiological investigations in southern Vietnam. Samples were selected from 10 provinces, focussing on age-groups targeted by national vaccination programmes for infants and pregnant women (Expanded Programme on Immunization, EPI, and Maternal and Neonatal Tetanus, MNT). RESULTS: Antibodies were measured from a total of 3864 samples. Highest tetanus antibody concentrations occurred in children under 4 years old, over 90 % of whom had protective levels. Approximately 70 % of children aged 7-12 years had protective antibody concentrations although there was variation among provinces. For infants and children, there were no significant differences in tetanus protection between males and females, but for adults aged 20-35 years, in five of the ten provinces surveyed, protection against tetanus was higher in females (p < 0.05) who are eligible for booster doses under the MNT programme. In seven of ten provinces, antibody concentrations were inversely related to age (p < 0.01) and protection of older individuals was generally low. CONCLUSION: Widespread immunity to tetanus toxoid is seen in infants and young children consistent with the high coverage rates reported for diptheria tetanus toxoid and pertussis (DTP) in Vietnam. However, the lower antibody concentrations seen in older children and men suggest reduced immunity to tetanus in populations not targeted by EPI and MNT programmes.

Feruloylmonotropeins: promising natural antioxidants in Paederia scandens.

Paederia scandens (Lour.) is a widely used medicinal herb in Vietnam, China, India, and Japan for the treatment of a variety of conditions, including toothache, chest pains, piles, and spleen inflammation. There is broad interest in identifying the composition of its extracts and confirming their numerous biological activities, including anti-nociceptive, antiviral, and anticancer properties. Two iridoid glucosides obtained from the MeOH extract of P. scandens, 6'-O-E-feruloylmonotropein (6-FMT) and 10'-O-E-feruloylmonotropein (10-FMT), are potential antioxidants based on their structure. In this study, the hydroperoxyl scavenging activity of 6-FMT and 10-FMT was examined in silico by using density functional theory. These FMTs are predicted to be weak antioxidants in non-polar environments, whereas a good HOO˙ scavenging activity is expected in polar environments (pH = 7.4) with k overall = 3.66 × 107 M-1 s-1 and 9.45 × 106 M-1 s-1, respectively. This activity is better than many common antioxidants such as trolox and nearly equivalent to ascorbic acid and resveratrol. The hydroperoxyl scavenging activity was exerted mainly by the di-anion form of FMTs in water at physiological pH following the single electron transfer mechanism. The results suggest that FMTs are promising natural antioxidants in aqueous physiological environments.

Monkeypox Virus Infection in 2 Female Travelers Returning to Vietnam from Dubai, United Arab Emirates, 2022.

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.

Zn doped iron oxide nanoparticles with high magnetization and photothermal efficiency for cancer treatment.

Magnetic nanoparticles (NPs) are powerful agents to induce hyperthermia in tumours upon the application of an alternating magnetic field or an infrared laser. Dopants have been investigated to alter different properties of materials. Herein, the effect of zinc doping into iron oxide NPs on their magnetic properties and structural characteristics has been investigated in-depth. A high temperature reaction with autogenous pressure was used to prepare iron oxide and zinc ferrite NPs of same size and morphology for direct comparison. Pressure was key in obtaining high quality nanocrystals with reduced lattice strain (27% less) and enhanced magnetic properties. Zn0.4Fe2.6O4 NPs with small size of 10.2 ± 2.5 nm and very high saturation magnetisation of 142 ± 9 emu gFe+Zn-1 were obtained. Aqueous dispersion of the NPs showed long term magnetic (up to 24 months) and colloidal stability (at least 6 d) at physiologically mimicking conditions. The samples had been kept in the fridge and had been stable for four years. The biocompatibility of Zn0.4Fe2.6O4 NPs was next evaluated by metabolic activity, membrane integrity and clonogenic assays, which show an equivalence to that of iron oxide NPs. Zinc doping decreased the bandgap of the material by 22% making it a more efficient photothermal agent than iron oxide-based ones. Semiconductor photo-hyperthermia was shown to outperform magneto-hyperthermia in cancer cells, reaching the same temperature 17 times faster whilst using 20 times less material (20 mgFe+Zn ml-1vs. 1 mgFe+Zn ml-1). Magnetothermal conversion was minimally hindered in the cellular confinement whilst photothermal efficiency remained unchanged. Photothermia treatment alone achieved 100% cell death after 10 min of treatment compared to only 30% cell death achieved with magnetothermia at clinically relevant settings for each at their best performing concentration. Altogether, these results suggest that the biocompatible and superparamagnetic zinc ferrite NPs could be a next biomaterial of choice for photo-hyperthermia, which could outperform current iron oxide NPs for magnetic hyperthermia.

Study on the effect of processing methods on the total polyphenol, 2,3,5,4'-tetrahydroxystilben-2-O-ß-D-glucoside, and physcion contents in Fallopia multiflora Thunb. Haraldson root

Abstract This study investigated the changes in the ingredients in Fallopia multiflora Thunb. Haraldson (FMT) root after processing it with different methods such as soaking, stewing, and steaming or combined methods. The total polyphenol, 2,3,5,4'-tetrahydroxystilben-2-O-ß-D-glucoside (THSG), and physcion contents in FMT products after processing were determined using high-performance liquid chromatography (HPLC) and ultraviolet-visible (UV-VIS) methods. The results demonstrated that the processing method and time significantly affected the contents of polyphenol, THSG, and physcion. The physcion and total polyphenol content increased or decreased during processing depending upon the processing time, while the THSG content gradually decreased with an increase in the processing time. The content of physcion (a substance that can cause liver toxicity) was analysed, and the suitable conditions for processing of the FMT products were determined as initial soaking in rice swill for 24 h and subsequent stewing with black beans and water for 12 h

Age-dependent heterogeneity in the antigenic effects of mutations to influenza hemagglutinin.

Human influenza virus evolves to escape neutralization by polyclonal antibodies. However, we have a limited understanding of how the antigenic effects of viral mutations vary across the human population, and how this heterogeneity affects virus evolution. Here we use deep mutational scanning to map how mutations to the hemagglutinin (HA) proteins of the A/Hong Kong/45/2019 (H3N2) and A/Perth/16/2009 (H3N2) strains affect neutralization by serum from individuals of a variety of ages. The effects of HA mutations on serum neutralization differ across age groups in ways that can be partially rationalized in terms of exposure histories. Mutations that fixed in influenza variants after 2020 cause the greatest escape from sera from younger individuals. Overall, these results demonstrate that influenza faces distinct antigenic selection regimes from different age groups, and suggest approaches to understand how this heterogeneous selection shapes viral evolution.

Mortality benefits of reduction fine particulate matter in Vietnam, 2019.

Introduction and objectives: Studies assessing the health benefits of air pollution reduction in Vietnam are scarce. This study quantified the annual mortality burden due to PM2.5 pollution in Vietnam above the World Health Organization recommendation for community health (AQG: 5 µg/m3) and the proposed National Technical Regulation on Ambient Air Quality (proposed QCVN: 15 µg/m3). Methodology: This study applied a health impact assessment methodology with the hazard risk function for non-communicable diseases (NCDs) and lower respiratory infections (LRIs) in the Global Exposure Mortality Model (GEMM) to calculate attributable deaths, Years of Life lost, and Loss of Life expectancy at birth due to air pollution in the Vietnamese population above 25 years of age in 11 provinces. We obtained annual average PM2.5 concentrations for Vietnam in 2019 at a 3x3 km grid modeled using Mixed Linear regression and multi-data sources. Population and baseline mortality data were obtained from administrative data system in Vietnam. We reported the findings at both the provincial and smaller district levels. Results: Annual PM2.5 concentrations in all studied provinces exceeded both the AQG and the proposed QCVN. The maximum annual number of attributable deaths in the studied provinces if they had complied with WHO air quality guidelines was in Ha Noi City, with 5,090 (95%CI: 4,253-5,888) attributable deaths. At the district level, the highest annual rate of attributable deaths if the WHO recommendation for community health had been met was 104.6 (95%CI: 87.0-121.5) attributable deaths per 100,000 population in Ly Nhan (Ha Nam province). Conclusion: A much larger number of premature deaths in Vietnam could potentially be avoided by lowering the recommended air quality standard. These results highlight the need for effective clean air action plans by local authorities to reduce air pollution and improve community health.

A versatile non-fouling multi-step flow reactor platform: demonstration for partial oxidation synthesis of iron oxide nanoparticles.

In the last decade flow reactors for material synthesis were firmly established, demonstrating advantageous operating conditions, reproducible and scalable production via continuous operation, as well as high-throughput screening of synthetic conditions. Reactor fouling, however, often restricts flow chemistry and the common fouling prevention via segmented flow comes at the cost of inflexibility. Often, the difficulty of feeding reagents into liquid segments (droplets or slugs) constrains flow syntheses using segmented flow to simple synthetic protocols with a single reagent addition step prior or during segmentation. Hence, the translation of fouling prone syntheses requiring multiple reagent addition steps into flow remains challenging. This work presents a modular flow reactor platform overcoming this bottleneck by fully exploiting the potential of three-phase (gas-liquid-liquid) segmented flow to supply reagents after segmentation, hence facilitating fouling free multi-step flow syntheses. The reactor design and materials selection address the operation challenges inherent to gas-liquid-liquid flow and reagent addition into segments allowing for a wide range of flow rates, flow ratios, temperatures, and use of continuous phases (no perfluorinated solvents needed). This "Lego®-like" reactor platform comprises elements for three-phase segmentation and sequential reagent addition into fluid segments, as well as temperature-controlled residence time modules that offer the flexibility required to translate even complex nanomaterial synthesis protocols to flow. To demonstrate the platform's versatility, we chose a fouling prone multi-step synthesis, i.e., a water-based partial oxidation synthesis of iron oxide nanoparticles. This synthesis required I) the precipitation of ferrous hydroxides, II) the addition of an oxidation agent, III) a temperature treatment to initiate magnetite/maghemite formation, and IV) the addition of citric acid to increase the colloidal stability. The platform facilitated the synthesis of colloidally stable magnetic nanoparticles reproducibly at well-controlled synthetic conditions and prevented fouling using heptane as continuous phase. The biocompatible particles showed excellent heating abilities in alternating magnetic fields (ILP values >3 nH m2 kgFe-1), hence, their potential for magnetic hyperthermia cancer treatment. The platform allowed for long term operation, as well as screening of synthetic conditions to tune particle properties. This was demonstrated via the addition of tetraethylenepentamine, confirming its potential to control particle morphology. Such a versatile reactor platform makes it possible to translate even complex syntheses into flow, opening up new opportunities for material synthesis.