Enamel Coatings and Surface (Super) Hydrophobicity

Vitreous enamel is hydrophilic due to its oxide components being affine to water, and there is little research on the hydrophobicity of enamel coatings. The Thesis introduces new knowledge on hydrophobic enamel coatings and significant contributions to the non-wettability concept through various solutions to hydrophobize enamel coatings. Experimental methodologies are based on a combination of surface roughening and silane treatment. The former increases roughness and the latter imparts a low surface energy to produce (super) hydrophobicity. The distinct inner microstructure of enamel was readily exposed by appropriate acid etching. After surface silanization, the microstructures improved the static hydrophobicity of coatings to a contact angle of 134o. The etched microscale structure contributed to mechanical durability against an abrasive cloth, while fluoroalkyl silane reagents provided a thermal stability of the enamel’s hydrophobic properties at an elevated temperature (400oC). Hydrophobic enamel coatings produced a water condensation in a dropwise manner which indicates qualitatively the enhanced surficial heat transfer for heat exchanger applications

Digital Innovations for the Circular Economy

Doctoral thesis (PhD) - Nord University, 2023publishedVersio

THE RELATIONSHIP BETWEEN BASELINE CD4 T CELLS’ LEVEL AND RECOVERY RATE AFTER INITIATION OF ART IN HIV/AIDS INFECTED AT HOSPITAL FOR TROPICAL DISEASES, VIETNAM

Objective: HIV/AIDS pandemic continues to be a public health problem in developing countries. This study aimed to assess the correlation of recovery responses and baseline CD4 T cells’ level in HIV/AIDS adult patients after initiation of antiretroviral therapy (ART) in Vietnam. Methods: The study was a clinic-based longitudinal study done at an outpatient clinic, Tropical Diseases Hospital, Ho Chi Minh City, Vietnam, from 10/2018 to 8/2019. Results: Ninety-three patients were provided informed consent to participate in this study. Overall, the mean of CD4 T cell counts was 161.7 cells/μl. In AIDS patients groups, at the baseline mean of T CD4 cell was 65 cells/μl and in the non-AIDS group was 315 cells/μl. The slope of the plotted overall CD4 cell counts increased significantly in both two groups and the steepest increases in the first 3 months. After 6 months, patients who were AIDS stages were had a higher viral load in plasma than others, with p<0.005. The changes in CD4 T cell counts were significantly associated with age and occupational status. Conclusion: The present study found that immunological responses of patients with first-line ART were not related to baseline CD4 T cells’ level. However, low baseline CD4 counts were associated with poor virologic suppression

The percentage of hepatitis B virus infection and related factors in Tra Vinh province, Vietnam

Background: Hepatitis B virus infection continues to be a public health problem in developing countries. This study aimed to assess the percentage of hepatitis B virus infection and related factors among adult population in Tra Vinh Province, Vietnam 2022. Methods: The study applied the cross-sectional descriptive design with the combination of structured interview and serological blood tests, from September 1, 2021, to June 1, 2022. Results: There were 1,289 respondents in the study. Overall, the percentage of sample positive reaction with HBsAg were 7.68% (99 peoples). Most of the people did not likely have relatives with a family history of hepatitis B virus infection, the proportion of people who had household family members who had hepatitis B, hepatocellular carcinoma, and cirrhosis was 1.24%, 0.93%, and 2.48% respectively. People who did not preventive vaccination for hepatitis B virus had higher rates of HBsAg (+) than people get preventive vaccination, with p=0.005. However, in other medical practice, the rate of HBsAg was non-significance, such as blood transfusion, surgery, dental treatment, injecting medications, and injected skin boils. The percentage of hepatitis B virus infection in the study was not significantly associated with hepatitis B prevention practices in daily life, including acupuncture, sharing shavers, sharing toothbrushes, sharing nail tools, and spraying tattoo. Conclusions: The percentage of hepatitis B virus infection in Tra Vinh province was 7.68%. There was a statistically significant relationship between the incidence of hepatitis B with preventive vaccination for the hepatitis B virus

Seasonal Variations in Groundwater Quality under Different Impacts Using Statistical Approaches

The objective of this study was to evaluate seasonal fluctuations in groundwater quality, determine the effects of different stressors on this resource, and recognize the potential pollution sources in a coastal region of southern Vietnam. Eleven samples collected in Ben Tre province during the dry and wet seasons were then analyzed for sixteen parameters, including pH, total dissolved solids (TDS), salinity, total hardness (TH), ammonium (NH₄⁺-N), nitrite (NO₂ˉ-N), nitrate (NO₃ˉ-N), sulfate (SO₄²ˉ), chloride (Clˉ), iron (Fe), manganese (Mn), lead (Pb), mercury (Hg), arsenic (As), coliforms, and Escherichia coli (E. coli). Pearson correlation analysis, principal component analysis (PCA), and cluster analysis (CA) were employed. The results indicated that total dissolved solids, salinity, total hardness, Clˉ, E. coli and coliform were detected as contaminants in groundwater samples. The trend of fluctuations in the parameters was mostly higher in the dry season. Which Mn and coliform significantly fluctuated between the dry and wet seasons. Activities in industrial-craft areas, landfills and seawater-intruded areas negatively impacted groundwater quality, typically TDS in industrial-craft areas, coliform and E.coliat the landfill area. Six principal components obtained from PCA could explain 93.6% of the variance, and all parameters are responsible for variations in groundwater quality. Geology, discharged wastewater, landfill leachate, agricultural activities, and saltwater intrusion can be considered representative factors. CA grouped the collected samples into four clusters based on the similarity in water properties. The analysis results showed that the locations in each cluster have outstanding water quality characteristics, clusters I and III have high TDS characteristics, cluster II has coliforms, and cluster IV sets of locations with high salinity. This study is promised to partially fill the gap in comprehensive information on groundwater quality in the coastal province so that policymakers can develop sustainable water management strategies in the future. Doi: 10.28991/CEJ-2023-09-03-01 Full Text: PD

Ecological Risk Associated with the Occurrence of Heavy Metals in Agricultural Soil in Soc Trang Province, Vietnam

The study aimed to evaluate the content and potential ecological risks due to the presence of toxic elements (Pb, Cu, Cr, Zn, As) in agricultural soil in Soc Trang province. Data of five heavy metals and physical factors at eight sites (from D1 to D8) in three ecological zones (fresh, brackish and saline agricultural activities) in the study were collected from the Department of Natural Resources and Environment of Soc Trang province. Multivariate statistical analyzes, including principal component analysis (PCA), correlation analysis (Pearson), cluster analysis (CA) and potential ecological risk index (RI), were used in the study. The results showed that the content of Pb, Cu, Cr, Zn and As fluctuated in the range of 8.54–30, 21.90–28.10, 20.60–38.70, 46.80–86, 1.35–11.30 mg/kg, respectively, within the allowable limits of QCVN 03-MT:2015/BTNMT. The soil in the study area has moderate to neutral acidity, suitable for growing crops. The Pearson and PCA results showed that the inputs in local agricultural development (fertilizers, pesticides, fungicides, and herbicides) have contributed to the increase of heavy metal content in the soil. The results of the CA grouped eight soil samples into two large groups belonging to the ecological areas (brackish, saline) and freshwater. The mean RI value of 68.84 indicated low potential ecological risks in agricultural land in Soc Trang province. However, As and Cr are heavy metals that would pose significant potential risks to the environment and humans. Thus, measures are needed to strictly control the sources of these metals