Browsing by Author "Vuai, S."
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Item 2-Hexylthiophene-substituted alizarin-based (D–π–A) organic dyes for dye-sensitized solar cell applications:: density functional theory and UV–Vis studies(Science Reviews Ltd., 2021) Abubakari, I.; Babu, S.; Vuai, S.; Makangara, J.This work reports density functional theory and time-dependent density functional theory calculations of the optimized geometries, electronic structures and optical properties of molecular dyes D1, D2, D3, D4, D5, and D6 formulated through substitution of 2-hexylthiophene to alizarin using the hybrid functional B3LYP and 6-31G (d,p) basis sets. The dyes are considered as potential pigments for dye-sensitized solar cells. For all dyes, HOMO/LUMO (Highest Occupied Molecular Orbital/Lowest Unoccupied Molecular Orbital) analysis results in positive outcomes upon electron injection to semiconductors and subsequent dye regeneration by the electrolyte. It is found that charge transfer is from the thiophene and unsubstituted ring of alizarin to the substituted ring of alizarin containing C=O and OH groups. The C=O groups are observed to be very important in strengthening the dyes as they are revealed to be the anchoring group bonding to the TiO2 semiconductor. Comparatively, dye D6 is observed to possess high absorption ability and electron injection power through a study of the light-harvesting efficiency and injection driving force (ΔGinject). The estimated values of open-circuit voltage (Voc) for the computed dyes are also presented. Decisively, all the considered dyes prove to be useful as potential photosensitizers in solar cells using a TiO2 semiconductor and I I− −/ 3 coupling electrolyte.Item The age of opportunity: Prevalence of key risk factors among adolescents 10–19 years of age in nine communities in sub‐Saharan Africa(Wiley Online, 2020) Berhane, Y.; Canavan, C. R.; Darling, A. M.; Sudfeld, C. R.; Vuai, S.; Adanu, R.; Bärnighausen, T.; Dessie, Y.; Bukenya, J. N.To measure health-related behaviours and risk factors among sub-Saharan African adolescents. Cross-sectional study in nine communities in Burkina Faso, Ethiopia, Eswatini, Ghana, Nigeria, Tanzania and Uganda between 2015 and 2017. Community-representative samples of males and females 10–19 years of age were selected. All communities used a uniform questionnaire that was adapted from the WHO Global School-based Student Health Survey. Weighted prevalence estimates and 95% confidence intervals were calculated for each indicator and stratified by age and sex using SAS version 9.4. All prevalence estimates were pooled across communities through random-effects meta-analyses in Stata version 14.resultsA total of 8075 adolescents participated in the study. We observed a high prevalence of inadequate fruit consumption (57–63%) and low physical activity (82–90%); a moderate prevalence of inadequate vegetable consumption (21–31%), unprotected last sex (38–45%), age at first sex<15 years(21–28%) and bullying and physical fighting (12–35%); and a low prevalence of mental health risk factors (1–11%) and alcohol and substance use risk factors (0–6%). We observed a moderate to high prevalence of daily soft drink consumption (21–31%) for all adolescents. Among sexually active adolescents 15–19 years, 37% of females reported ever being pregnant and 8% of males reported to have ever made someone pregnant. Bullying (23%) and physical fighting (35%) were more common among younger male adolescents. The prevalence of low mood was generally higher among older (15–19 years) than younger adolescents (10–14 years). The proportion of adolescents reporting alcohol, drug or cigarette use was very small, with the exception of khat use in Ethiopia. Overall, diet and physical activity, violence, sexual and reproductive health, and depression are important risk factors for these sub-Saharan African communities. These findings suggest that more evidence is needed including novel efforts for the collection of sensitive information, as well as a need to move towards community-tailored interventions to reach adolescent populations with varying needs.Item Design and field methods of the ARISE network adolescent health study(Wiley Online, 2020) Darling, A. M.; Assefa, N.; Bärnighausen, T.; Berhane, Y.; Canavan, C. R.; Guwatudde, D.; Sudfeld, C.; Killewo, J.; Oduola, A.; Sando, M. M.; Sie, A.; Sudfeld, C.; Vuai, S.; Adanu, R.; Fawzi, W. W.The ARISE Network Adolescent Health Study is an exploratory, community‐based survey of 8075 adolescents aged 10–19 in 9 communities in 7 countries: Burkina Faso, Eswatini, Ethiopia, Ghana, Nigeria, Tanzania and Uganda. Communities were selected opportunistically and existing population cohorts maintained by health and demographic surveillance systems (HDSSs). The study is intended to serve as a first round of data collection for African adolescent cohorts, with the overarching goal of generating community‐based data on health‐related behaviours and associated risk factors in adolescents, to identify disease burdens and health intervention opportunities. Household‐based sampling frames were used in each community to randomly select eligible adolescents (aged 10–19 years). Data were collected between July 2015 and December 2017. Consenting participants completed face‐to‐face interviews with trained research assistants using a standardised questionnaire, which covered physical activity, cigarette and tobacco use, substance and drug use, mental health, sexual behaviours and practices, sexually transmitted infections, pregnancy, food security and food diversity, teeth cleaning and hand washing, feelings and friendship, school and home activities, physical attacks and injuries, health care, health status assessment and life satisfaction, as well as media and cell phone use and socio‐demographic and economic background characteristics. Results from this multi‐community study serve to identify major adolescent health risks and disease burdens, as well as opportunities for interventions and improvements through policy changes.Item Maternal dietary diversity and growth of children under 24 months of age in rural Dodoma, Tanzania(Sage publishing, 2018) Huang, M.; Sudfeld, C.; Ismail, A.; Vuai, S.; Ntwenya, J.; Mwanyika-Sando, M.; Fawzi, W.Objective: To identify predictors of maternal dietary diversity in rural Dodoma, Tanzania and assess its association with child growth outcomes. Methods: A cross-sectional survey of 361 mothers with children under 24 months of age was con-ducted in 5 villages in rural Dodoma, Tanzania. Maternal diets were assessed using food frequency questionnaires, and dietary diversity was categorized using Minimum Dietary Diversity for Women (MDD-W) guidelines. Child anthropometric measures were taken to calculate height-for-agez-score (HAZ), weight-for-heightz-score (WHZ), and weight-for-agez-score (WAZ). Linear and logistic regressions were used to examine the association between maternal dietary diversity and children’s growth outcomes. Results: About 40% of mothers did not consume a diverse diet (MDD-W < 5), and 35% of children were stunted. Household production of greater number of crops was associated with greater MDD-W scores (P< .01). Greater maternal dietary diversity was associated with significantly greater child WHZ (mean difference¼0.44; 95% confidence interval [CI]: 0.10-0.78;P¼.01), WAZ (mean dif-ference¼0.37; 95% CI: 0.08-0.65;P¼.01), and reduced risk of wasting (odds ratio¼0.22; 95% CI:0.07-0.66;P¼.01). Conclusions: Greater maternal dietary diversity was associated with improved child WHZ and WAZ outcomes. Sustainable interventions to increase maternal dietary diversity may improve WHZ and WAZ in young children in similar settings.Item Prevalence and risk factors associated with malnutrition among adolescents in rural Tanzania(Wiley Online, 2020) Ismail, A.; Darling, A. M.; Mosha, D.; Fawzi, W.; Sudfeld, C.; Sando, M. M.; Noor, R. A.; Charles, J.; Vuai, S.To determine the prevalence and risk factors associated with malnutrition among adolescents in a rural Tanzanian community. Cross-sectional survey of 1226 randomly selected adolescents from the Dodoma Health and Demographic Surveillance System (HDSS) in the Chamwino district in the Dodoma region. Anthropometric measurements for weight and height were collected. Height-for-age-z-scores (HAZs) and body mass index (BMI)-for-age-z-scores (BAZs) were computed. Descriptive estimates were documented in graphs and tables, and weighted linear regression models were used to examine predictors of malnutrition. Stunting prevalence was 18%, and thinness prevalence was 14%. Overweight and obesity affected 5.23% of participants. Girls had higher HAZs (b: 0.46, 95% CI 0.33, 0.59, P < 0.0001) and BAZs (b: 0.20, 95% CI 0.05, 0.35, P = 0.0098) than boys. Age was inversely associated with HAZs (b: _0.13, 95% CI _0.17, _0.08, P < 0.0001) and BAZs (b: _0.05, 95% CI _0.10, _0.004, P = 0.0327). Wealth score (b: 0.10, 95% CI 0.04, 0.16, P = 0.0009) and dietary diversity score (b: 0.04, 95% CI 0.01, 0.07, P = 0.0080) were positively associated with HAZs and BAZs. Out of school adolescents had higher HAZs (b: _0.49, 95% CI _0.75, _0.23, P = 0.0003) and BAZs (b:0.68, 95% CI _0.99, _0.37, P < 0.0001) than adolescents who attended school. There are substantial variations of HAZs and BAZs across gender, age, education and wealth, with an emerging burden of overweight and obesity among adolescents in this rural population. Interventions are urgently required to curb both ends of the malnutrition spectrum.