Effect of Silica Nanoparticles on Properties of Coatings Based on Acrylic Emulsion Resin

Effect of nanosilica size on physic-mechanical properties, thermal stability and weathering durability of coating based on acrylic emulsion. Nanocomposite coating formulas were filled by 2 wt.% nanosilica particles which were used in this study, namely: nanosilica from Sigma (15-20nm), nansilica from rice husk (~70-200 nm) and nanosilica from Arosil – Belgium (7-12 nm). Obtained results showed that viscosity flow of coating formula containing nanosilica from Arosil saw the highest flow-time while coating formulas filled other nanosilica and unfilled nanosilica experienced similar flow-time. In presence of nanosilica, coating properties were improved in comparison with neat coating. However, coating filled by nanosilica from rice husk indicated the best properties in studied coating formula. It may explained that size of nanosilica from rice husk was the largest in studied nanosilica particles and thus easily dispersing into coating formula

Influence of operating conditions and membrane fouling on water flux during seawater desalination using air gap membrane distillation

Membrane distillation (MD) has emerged as a promising process for seawater desalination applications to augment fresh water supply in remote coastal areas. Amongst four basic MD configurations, air gap membrane distillation (AGMD) exhibits the highest thermal efficiency, and thus is the most used configuration for small-scale seawater desalination. In this study, the influences of operating conditions and membrane fouling on water flux of a lab-scale AGMD process with actual seawater feed were systematically investigated. The experimental results demonstrated strong impacts of feed temperature, circulation rates, and membrane fouling on the process water flux. Increasing feed temperature exponentially raised water flux but also aggravated polarization effects of the AGMD process. Elevating water circulation rates, particularly of the feed stream, helped alleviate polarization effects, hence improving the process water flux. During the AGMD process of raw seawater feed, the accumulation of organic matters on the membrane reduced its active surface for water evaporation, increased polarization effects, and therefore significantly reduced the process water flux. Pretreatment of the seawater feed by 0.45 mm paper filters removed organic foulants from the feed, and hence helped sustain the water flux of the AGMD process at water recoveries up to 70 %. When the process water recovery exceeded 70 %, water flux rapidly dropped owing to the precipitation of sparingly soluble salts (e.g. CaSO4, CaCO3) on the membrane. Subsequent cleaning the fouled membrane using vinegar removed nearly all foulants from the membrane surface to restore the membrane hydrophobicity, and thus the process water flux. The results reported in this study manifest that seawater AGMD desalination can be a practical process to supply drinking water to small and remote communities in Vietnam. Keywords. Membrane distillation (MD), air gap membrane distillation (AGMD), seawater desalination, membrane fouling, membrane fouling mitigation

Productivity costs from a dengue episode in Asia: a systematic literature review

Background Dengue is a mosquito-borne viral infection which has been estimated to cause a global economic burden of US$8.9 billion per year. 40 Method We searched PubMed and Web of Knowledge without date and language restrictions using terms related to dengue and cost and economics burden. The titles and abstracts of publications related to Asia were screened to identify relevant studies. The reported productivity losses and costs of non-fatal and fatal dengue episodes were then described and compared. Costs were adjusted for inflation to 2017 prices. Results We reviewed 33 relevant articles, of which 20 studies reported the productivity losses, and 31 studies reported productivity costs. The productivity costs varied between US$6.7–1445.9 and US$3.8–1332 for hospitalized and outpatient non-fatal episodes, respectively. The productivity cost associated with fatal dengue episodes varied between US$12,035-1,453,237. A large degree of this variation was due to the range of different countries being investigated and their corresponding economic status. However, estimates for a given country still showed notable variation. Conclusion We found that the estimated productivity costs associated with dengue episodes in Asia are notable. However, owing to the significant variation in methodology and approaches applied, the reported productivity costs of dengue episodes were often not directly comparable across studies. More consistent and transparent methodology regarding the estimation of productivity costs would help the estimates of the economic burden of dengue be more accurate and comparable across studies

Spatiotemporal evolution of SARS-CoV-2 Alpha and Delta variants during large nationwide outbreak of COVID-19, Vietnam, 2021

We analyzed 1,303 SARS-CoV-2 whole-genome sequences from Vietnam, and found the Alpha and Delta variants were responsible for a large nationwide outbreak of COVID-19 in 2021. The Delta variant was confined to the AY.57 lineage and caused >1.7 million infections and >32,000 deaths. Viral transmission was strongly affected by nonpharmaceutical interventions

The 80-year development of Vietnam mathematical research: Preliminary insights from the SciMath database on mathematicians, their works and their networks

Starting with the first international publication of Le Van Thiem (Lê Văn Thiêm) in 1947, modern mathematics in Vietnam is a longstanding research field. However, what is known about its development usually comes from discrete essays such as anecdotes or interviews of renowned mathematicians. We introduce SciMath—a database on publications of Vietnamese mathematicians. To ensure this database covers as many publications as possible, data entries are manually collected from scientists’ publication records, journals’ websites, universities, and research institutions. Collected data went through various verification steps to ensure data quality and minimize errors. At the time of this report, the database covered 8372 publications, profiles of 1566 Vietnamese, and 1492 foreign authors since 1947. We found a growing capability in mathematics research in Vietnam in various aspects: scientific output, publications on influential journals, or collaboration. The database and preliminary results were presented to the Scientific Council of Vietnam Institute for Advanced Study in Mathematics (VIASM) on November 13th, 2020

Differential prevalence and geographic distribution of hepatitis C virus genotypes in acute and chronic hepatitis C patients in Vietnam.

BACKGROUND: The highest burden of disease from hepatitis C virus (HCV) is found in Southeast Asia, but our understanding of the epidemiology of infection in many heavily burdened countries is still limited. In particular, there is relatively little data on acute HCV infection, the outcome of which can be influenced by both viral and host genetics which differ within the region. We studied HCV genotype and IL28B gene polymorphism in a cohort of acute HCV-infected patients in Southern Vietnam alongside two other cohorts of chronic HCV-infected patients to better understand the epidemiology of HCV infection locally and inform the development of programs for therapy with the increasing availability of directly acting antiviral therapy (DAAs). METHODS: We analysed plasma samples from patients with acute and chronic HCV infection, including chronic HCV mono-infection and chronic Human Immunodeficiency Virus (HIV)-HCV coinfection, who enrolled in four epidemiological or clinical research studies. HCV infection was confirmed with RNA testing. The 5' UTR, core and NSB5 regions of HCV RNA positive samples were sequenced, and the genotype and subtype of the viral strains were determined. Host DNA from all HCV positive patients and age- and sex-matched non-HCV-infected control individuals were analysed for IL28B single nucleotide polymorphism (SNP) (rs12979860 and rs8099917). Geolocation of the patients were mapped using QGIS. RESULTS: 355 HCV antibody positive patients were analysed; 54.6% (194/355) and 46.4% (161/355) were acute and chronic infections, respectively. 50.4% (81/161) and 49.6.4% (80/161) of chronic infections had HCV mono-infection and HIV-HCV coinfection, respectively. 88.7% (315/355) and 10.1% (36/355) of the patients were from southern and central regions of Vietnam, respectively. 92.4% (328/355) of patients were HCV RNA positive, including 86.1% (167/194) acute and 100% (161/161) chronic infections. Genotype could be determined in 98.4% (322/328) patients. Genotypes 1 (56.5%; 182/322) and 6 (33.9%; 109/322) predominated. Genotype 1 including genotype 1a was significantly higher in HIV-HCV coinfected patients compared to acute HCV patients [43.8% (35/80) versus 20.5% (33/167)], (p = <0.001), while genotype 6 was significantly higher in chronic HCV mono-infected patients [(44.4% (36/81) versus 20.0% (16/80)] (p = < 0.004) compared to HIV-HCV coinfected patients. The prevalence of IL28B SNP (rs12979860) homozygous CC was 86.46% (83/96) in control individuals and was significantly higher in acutely-infected compared to chronically-infected patients [93.2 (82/88) versus 76.1% (35/46)] (p = < 0.005). CONCLUSION: HCV genotype 6 is highly prevalent in Vietnam and the high prevalence in treatment naïve chronic HCV patients may results from poor spontaneous clearance of acute HCV infection with genotype 6

Associations of Underlying Health Conditions With Anxiety and Depression Among Outpatients: Modification Effects of Suspected COVID-19 Symptoms, Health-Related and Preventive Behaviors

Objectives: We explored the association of underlying health conditions (UHC) with depression and anxiety, and examined the modification effects of suspected COVID-19 symptoms (S-COVID-19-S), health-related behaviors (HB), and preventive behaviors (PB).Methods: A cross-sectional study was conducted on 8,291 outpatients aged 18–85 years, in 18 hospitals and health centers across Vietnam from 14th February to May 31, 2020. We collected the data regarding participant's characteristics, UHC, HB, PB, depression, and anxiety.Results: People with UHC had higher odds of depression (OR = 2.11; p &lt; 0.001) and anxiety (OR = 2.86; p &lt; 0.001) than those without UHC. The odds of depression and anxiety were significantly higher for those with UHC and S-COVID-19-S (p &lt; 0.001); and were significantly lower for those had UHC and interacted with “unchanged/more” physical activity (p &lt; 0.001), or “unchanged/more” drinking (p &lt; 0.001 for only anxiety), or “unchanged/healthier” eating (p &lt; 0.001), and high PB score (p &lt; 0.001), as compared to those without UHC and without S-COVID-19-S, “never/stopped/less” physical activity, drinking, “less healthy” eating, and low PB score, respectively.Conclusion: S-COVID-19-S worsen psychological health in patients with UHC. Physical activity, drinking, healthier eating, and high PB score were protective factors