A Comprehensive Performance Evaluation of GGBS-Based Geopolymer Concrete Activated by a Rice Husk Ash-Synthesised Sodium Silicate Solution and Sodium Hydroxide

Commercial sodium hydroxide (NaOH) and sodium silicate (SS) are commonly used as alkaline activators in geopolymer concrete production despite concerns about their availability and associated CO2 emissions. This study employs an alternative alkaline activator (AA) synthesized from a sodium silicate alternative (SSA) solution derived from rice husk ash (RHA) and a 10 M sodium hydroxide solution. The initial phase established an optimal water-to-binder (W/B) ratio of 0.50, balancing workability and structural performance. Subsequent investigations explored the influence of the alkali/precursor (A/P) ratio on geopolymer concrete properties. A control mix uses ordinary Portland cement (OPC), while ground granulated blast-furnace slag (GGBS)-based geopolymer concrete—GPC mixes (GPC1, GPC2, GPC3, GPC4) vary the A/P ratios (0.2, 0.4, 0.6, 0.8) with a 1:1 ratio of sodium silicate to sodium hydroxide (SS: SH). The engineering performance was evaluated through a slump test, and unconfined compressive strength (UCS) and tensile splitting (TS) tests in accordance with the appropriate standards. The geopolymer mixes, excluding GPC3, offer suitable workability; UCS and TS, though lower than the control mix, peak at an A/P ratio of 0.4. Despite lower mechanical strength than OPC, geopolymers’ environmental benefits make them a valuable alternative. GPC2, with a 0.4 A/P ratio and 0.5 W/B (water to binder) ratio, is recommended for balanced workability and structural performance. Future research should focus on enhancing the mechanical properties of geopolymer concrete for sustainable, high-performance mixtures

Water use efficiency of six rangeland grasses under varied soil moisture content levels in the arid Tana River County, Kenya

This study evaluated water use efficiency (WUE) of six range grasses, namely; Chloris roxburghiana, Eragrostis superba, Enteropogon macrostachyus, Cenchrus ciliaris, Chloris gayana, and Sorghum sudanense grown at 80, 50, 30% field capacity (FC) soil moisture contents and rainfed treatment which represented water deficit conditions. The changes in soil moisture content were measured by Gypsum Block which aided in determining the irrigation schedules. The grasses demonstrated varied levels of WUE which was evaluated by amount of biomass productivity in relation to evapotranspired water during the growing period. The three soil moisture content treatments had higher water use efficiency than rainfed conditions. There was a declining trend in WUE with grass species maturity where S. sudanense had higher WUE at 8, 10 and 12th weeks (> 15 kg DM ha-1 mm-) in all the treatments followed by C. gayana and E. macrostachyus and were significantly (p<0.05) different from E. superba, C. ciliaris and C. roxburghiana which had WUE less than 10 among the six grass species. The 30% FC soil moisture content had higher WUE at all the phenological stages for S. sudanense, C. gayana and E. macrostachyus compared to 80, 50% FC and rainfed with all having WUE greater than 20 kg DM ha-1 mm-1. These three species are recommended for irrigated pasture establishment in semi-arid lands where water supply uncertainties exist, owing to their high water use efficiency under lower soil moisture levels.Key words: Water use efficiency (WUE), water stress tolerance, range grasses, pasture irrigation, water deficit, Kenya

Utilization of a PFA-GGBS-Based Precursor in Geopolymer Concrete Production as a Sustainable Substitute for Conventional Concrete

Awareness of environmental sustainability is driving the shift from conventional Portland cement, a major contributor to carbon dioxide emissions, to more sustainable alternatives. This study focuses on developing a geopolymer concrete by optimizing geopolymer concrete mixtures with various ratios of Ground Granulated Blast Furnace Slag (GGBS) and pulverized fly ash (PFA) as precursors, aiming to find a mix that maximizes strength while minimizing environmental impacts. The precursor was activated using a laboratory-synthesized silica fume (SF)-derived sodium silicate solution in combination with NaOH at a molarity of 10M. This study aims to find the optimal geopolymer concrete mix with a 0.55 water-to-binder ratio, a 0.40 alkali-to-precursor ratio, and a 1:1 sodium silicate to sodium hydroxide ratio. Ordinary Portland cement was used as the control mix binder (C), while the geopolymer mixes included varying GGBS-PFA compositions [CL0 (50% GGBS—50% PFA), CL1 (60% GGBS—40% PFA), CL2 (70% GGBS—30% PFA), CL3 (80% GGBS—20% PFA), and CL4 (90% GGBS—10% PFA)]. The engineering performance of the mixtures was assessed using slump, unconfined compressive strength, split tensile, and flexural strength tests in accordance with their relevant standards. Observations showed that GPC specimens exhibited similar or slightly higher strength values than conventional concrete using PC. In addition to strength, geopolymers have a smaller environmental footprint, consuming less energy and reducing greenhouse gas emissions. These qualities make geopolymer concrete a sustainable construction option that aligns with global efforts to reduce carbon emissions and conserve resources

Low HIV incidence in pregnant and postpartum women receiving a community-based combination HIV prevention intervention in a high HIV incidence setting in South Africa

BACKGROUND: Young Southern African women have the highest HIV incidence globally. Pregnancy doubles the risk of HIV acquisition further, and maternal HIV acquisition contributes significantly to the paediatric HIV burden. Little data on combination HIV prevention interventions during pregnancy and lactation are available. We measured HIV incidence amongst pregnant and postpartum women receiving a community-based combination HIV prevention intervention in a high HIV incidence setting in South Africa. METHODS: A cohort study that included HIV-uninfected pregnant women was performed. Lay community- based workers provided individualized HIV prevention counselling and performed three-monthly home and clinic-based individual and couples HIV testing. Male partners were referred for circumcision, sexually transmitted infections or HIV treatment as appropriate. Kaplan-Meier analyses and Cox's regression were used to estimate HIV incidence and factors associated with HIV acquisition. RESULTS The 1356 women included (median age 22.5 years) received 5289 HIV tests. Eleven new HIV infections were detected over 828.3 person-years (PY) of follow-up, with an HIV incidence rate of 1.33 infections/100 PY (95% CI: 0.74±2.40). Antenatally, the HIV incidence rate was 1.49 infections/100 PY (95% CI: 0.64±2.93) and postnatally the HIV incidence rate was 1.03 infections/100 PY (95% CI: 0.33±3.19). 53% of male partners received HIV testing and 66% of eligible partners received referral for circumcision. Women within known serodiscordant couples, and women with newly diagnosed HIV-infected partners, adjusted hazard ratio (aHR) = 32.7 (95% CI: 3.8±282.2) and aHR = 126.4 (95% CI: 33.8±472.2) had substantially increased HIV acquisition, respectively. Women with circumcised partners had a reduced risk of incident HIV infection, aHR = 0.22 (95% CI: 0.03±1.86). CONCLUSIONS: Maternal HIV incidence was substantially lower than previous regional studies. Community-based combination HIV prevention interventions may reduce high maternal HIV incidence in resource-poor settings. Expanded roll-out of home-based couples HIV testing and initiating pre-exposure prophylaxis for pregnant women within serodiscordant couples is needed in Southern Africa

Do clinicians adhere to practice guidelines? A descriptive study at a referral hospital in Kenya

Background: Clinical guidelines when implemented correctly have shown to improve disease outcomes. This study describes utilization of Kenya National guidelines in managing ante partum haemorrhage (APH) in 3rd trimester.Objective: To describe adherence to clinical guideline in management of antepartum haemorrhage at Garissa Provincial General Hospital Design: Crossectional mixed methods studySetting: Garissa Provincial General HospitalSubjects: Medical records of patients managed for APH between 2002 and 2012 and Key Informant Interviews (KIIs) of Health workers.Results: 36.1% of the cases assessed were managed with strict adherence to guidelines. 90% of health care workers had high levels of awareness of the existence of guidelines and sited utilization challenges attributed to resource inadequacies.Conclusion: Clinicians are skilled on APH guidelines, but adherence levels are still low. Therefore, continuous appraisal of clinical practices, availing equipment, facilities and supplies to reinforce adherence is recommended

Alcohol and illicit drug use among young people living with HIV compared to their uninfected peers from the Kenyan coast: prevalence and risk indicators

Background: In sub-Saharan Africa, there is paucity of research on substance use patterns among young people living with HIV (YLWH). To address the gap, we sought to: i) determine the prevalence of substance use, specifically alcohol and illicit drug use, among YLWH compared to their HIV-uninfected peers; ii) investigate the independent association between young people’s HIV infection status and substance use; iii) investigate the risk indicators for substance use among these young people. Methods: Between November 2018 and September 2019, a cross-sectional study was conducted at the Kenyan coast recruiting 819 young people aged 18–24 years (407 HIV-positive). Alcohol and drug use disorders identification tests (AUDIT and DUDIT) were administered via audio computer-assisted self-interview alongside other measures. Logistic regression was used to determine substance use risk indicators. Results: The point prevalence of current substance use was significantly lower among YLWH than HIV-uninfected youths: current alcohol use, 13% vs. 24%, p \u3c 0.01; current illicit drug use, 7% vs. 15%, p \u3c 0.01; current alcohol and illicit drug use comorbidity, 4 vs. 11%, p \u3c 0.01. Past-year prevalence estimates for hazardous substance use were generally low among young people in this setting (\u3c 10%) with no significant group differences observed. Being HIV-positive independently predicted lower odds of current substance use, but not hazardous substance use. There was overlap of some risk indicators for current substance use between young people with and without HIV including male sex, khat use and an experience of multiple negative life events, but risk indicators unique to either group were also identified. Among YLWH, none of the HIV-related factors was significantly associated with current substance use. Conclusions: At the Kenyan coast, substance use is a reality among young people. The frequency of use generally appears to be low among YLWH compared to the HIV-uninfected peers. Substance use prevention initiatives targeting young people, regardless of HIV infection status, are warranted in this setting to avert their potential risk for developing substance use disorders, including dependence. The multifaceted intrapersonal and interpersonal factors that place young people at risk of substance use need to be addressed as part of the substance use awareness and prevention initiatives

The Gender Context of HIV Risk and Pregnancy Goals in Western Kenya

Background: Intentional childbearing may place heterosexual couples at risk of HIV infection in resource-limited settings with high HIV prevalence areas where society places great value on having children.Objective: To explore cognitive, cultural, and spatial mapping of sexual and reproductive health domains and services in western Kenya among men and women.Design: Community-based formative qualitative study design.Setting: Five administrative/geographical divisions of Nyando District, western Kenya.Subjects: Adult male 18 years and older and female who were of reproductive-potential ages (15 to 49 years for females)(n=90).Results:Men and women have disparate goals for number of children and engage in gendered patterns of protective method use (contraceptives used by women often in secret, condoms by men but rarely).Conclusion: HIV infection was still seen as stigmatising. These study results are relevant to design of effective integrated delivery for reproductive and HIV services in high-burden sub-Saharan African countries

Air pollution exposures in early life and brain development in children (ABC): protocol for a pregnancy cohort study

Introduction Air pollution is linked with poor neurodevelopment in high-income countries. Comparable data are scant for low-income countries, where exposures are higher. Longitudinal pregnancy cohort studies are optimal for individual exposure assessment during critical windows of brain development and examination of neurodevelopment. This study aims to determine the association between prenatal ambient air pollutant exposure and neurodevelopment in children aged 12, 24 and 36 months through a collaborative, capacity-enriching research partnership. Methods and analysis This observational cohort study is based in Nairobi, Kenya. Eligibility criteria are singleton pregnancy, no severe pregnancy complications and maternal age 18 to 40 years. At entry, mothers (n=400) are administered surveys to characterise air pollution exposures reflecting household features and occupational activities and provide blood (for lead analysis) and urine specimens (for polycyclic aromatic hydrocarbon (PAH) metabolites). Mothers attend up to two additional antenatal study visits, with urine collection, and infants are followed through age 36 months for annual neurodevelopment and caregiving behaviour assessment, and child urine and blood collection. Primary outcomes are child motor skills, language and cognition at 12, 24 and 36 months, and executive function at 36 months. The primary exposure is urinary PAH metabolite concentrations. Additional exposure assessment in a subset of the cohort includes residential indoor and outdoor air monitoring for fine particulate matter (PM2.5), carbon monoxide (CO), ultrafine particles (UFP) and black carbon (BC). Ethics and dissemination This study was approved by the Kenyatta National Hospital - University of Nairobi Ethics and Research Committee, and the University of Washington Human Subjects Division. Results are shared at annual workshops

Opportunities and Challenges to Emergency Department-Based HIV Testing Services and Self-Testing Programs: A Qualitative Study of Healthcare Providers and Patients in Kenya

BACKGROUND: Young people in Sub-Saharan Africa, especially males, have been insufficiently engaged through HIV Testing Services (HTS). In Kenya, younger persons are often treated in emergency departments (EDs) for injuries, an interaction where HTS and HIV self-testing (HIVST) can be leveraged. Data from stakeholders on ED-HTS and HIVST is lacking and needed to understand opportunities and barriers for HIV testing and care, and inform program implementation. METHODS: Between December 2021 and March 2022, 32 in-depth interviews (IDIs) were conducted with 16 male and 16 female patients who had been treated in the Kenyatta National Hospital (KNH) ED, half of whom had been HIV-tested. Six focus-group discussions (FGDs) were also conducted with 50 nurses, doctors, HIV testing counselors, and administrators working in the ED. All transcripts were double-coded and thematically analyzed using Dedoose software and a parallel inductive and deductive coding approach which allowed for capture of both a priori and emergent themes. RESULTS: Patients and providers agreed that ED-HTS are facilitated by friendly staff, patient education, high perceived HIV risk, and confidentiality. However, ED-HTS is limited by burdens on staff, resources, time, and space, as well as severity of patient injuries limiting ability to consent to or prioritize HIV testing. These limitations provide opportunities for ED-HIVST: particularly the ability to test at a comfortable time and place, especially when provided alongside sufficient HIV and testing education, contact with healthcare providers, and psychosocial support. Barriers for ED-HIVST where identified and as patients’ concerns about HIVST accuracy and mental health impacts of a positive test, as well providers’ identified barriers on their concerns for loss to follow up and inability to complete confirmatory testing. COM-B Model [Figure: see text] Application of the COM-B Model of Behavior Change to ED-HIVST Acceptability in Kenya CONCLUSION: ED stakeholders are receptive to HTS and HIVST, and patients desire the opportunity to use HIVST. Potential challenges—such as psychological effects of testing positive, worries about access to follow-up care, and confusion about how to self-administer testing, may be addressed through programming designed to promote education, access and ensure follow-up mechanisms. DISCLOSURES: All Authors: No reported disclosures