Tanzania Journal of Science 2024-05-03T07:36:50+00:00 Prof. John Andrew Marco Mahugija Open Journal Systems <p><strong><em>Tanzania Journal of Science</em></strong> (<em>Tanz. J. Sci.</em>)&nbsp; is an <strong>international journal</strong> published by the College of Natural and Applied Sciences, University of Dar es Salaam. The <strong><em>Tanzania Journal of Science</em></strong>,&nbsp;formerly known as “<em>University Science Journal", </em>was established in 1975 as a forum for communication and co-ordination between and among scientists and allied professionals. It is also intended as a medium for dissemination of scientific knowledge among scientists and the public at large to promote the advancement of pure and applied sciences. Tanzania Journal of Science publishes high quality contributions on original works in the fields of pure and applied sciences. Its review processes and decision criteria are rigorous. The manuscripts are evaluated by expert reviewers and editors to assess their scientific quality. Those manuscripts judged by the editors and Chief Editor to be of insufficient scientific quality or interest, or generally inappropriate are rejected promptly without formal review. Also, manuscripts not complying with the journal requirements and author guidelines are returned to the authors or rejected. The decisions regarding acceptance or rejection of papers are independent, unbiased and fair.&nbsp;</p> <p><strong>Indexed/Abstracted</strong> in: African Journals OnLine (AJOL); CAB International or CABI (Centre for Agriculture and Bioscience International, UK); CAB Direct; CAB Abstracts; CAB Global Health; Crossref; EBSCO Publishing; Journals for Free (J4F) database</p> <p><strong>For online submission please <a href="" target="_blank" rel="noopener">click here</a></strong></p> Effects of Bending and Re-bending on Mechanical Properties of Locally-Manufactured Steel Rebars 2024-04-30T12:45:24+00:00 Patrick W Waruhiu Simon I Marandu Mussa I , Mgwatu <p>Steel rebars experience deformation when subjected to bending and re-bending operations. Subsequently, their microstructures are impaired thus affecting the mechanical properties and leading to failure. This study establishes the effects of bending and re-bending the steel rebars on the mechanical properties. Experiments were conducted to determine the effects of bending and re-bending of the steel rebars. Testing was conducted on Ten virgin and Thirty specimens which were bent and re-bent at 45º, 90º, and 180º, and followed by tensile tests. Yield strength, ultimate tensile strength, elongation, and ultimate tensile strength to yield strength ratio (Rm/Re), were recorded. Results showed the yield strength, ultimate tensile strength, elongation, and Rm/Re of virgin steel rebars varied from 553.62 MPa to 618.49 MPa, 634.39 MPa to 745.68 MPa, 17.6 % to 21.67 %, and 1.14 to 1.19. The yield strength, ultimate tensile strength, elongation, and Rm / Re of bent and re-bent steel rebars at angles of 45º, 90º, and 180º varied from 603.67 MPa to 677.38 MPa, 692.82 MPa to 751.76 MPa, 6.88 % to 19 % and 1.09 to 1.21. It was established that bending and re-bending increase strength and reduce the ductility of the rebars proportionally.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Angular Distribution of Bremsstrahlung Spectral Temperature Measured in a Full Dimension of ECR Ion Source Using NaI(TI) Detector 2024-04-30T12:53:40+00:00 Mwingereza J. Kumwenda <p>Measurement of angular distribution (AD) of the bremsstrahlung spectral temperature from a full dimension of the Electron Cyclotron Resonance Ion Source (ECRIS) along the beam axis is challenging. To overcome some challenges, this paper presents the AD of the bremsstrahlung spectral temperature measured in a full dimension of the ECRIS along the beam axis using data obtained from the Busan Center of Korea Basic Science Institute (KBSI). The bremsstrahlung spectral temperature from 28-GHz ECR Ion source at the KBSI was measured in six, three, and nine azimuthal angles at the injection, centre, and extraction sides of the ECRIS using three round type thallium-activated sodium iodide (NaI(TI)) scintillation detectors. Monte Carlo simulation based on the Geant4 software package was performed to take the geometrical acceptance and energy-dependent detection efficiency into account due to large non-uniformity in the material budget. True bremsstrahlung energy spectra from the 28-GHz ECR ion source were obtained using the inverse-matrix deconvolution method. The unfolding method was based on a full geometry of the Geant4 model of the ECRIS plasma. The results show that in all three measurement locations, the highest value of the spectral temperature was at an angle of 30∘ coincident with one of the maximum angles of the ECRIS plasma shape.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Geological Structure and Possible Mineralized Zones in Ikungi – Manyoni Area, Tanzania: Delineated from High-resolution Aeromagnetic Data 2024-04-30T12:56:59+00:00 Raymond K Pius Michael M Msabi <p>Understanding geological structures is important in mineral exploration. Delineating subsurface geological structures, structural intersections, and complexities of potential geological settings for the formation of hydrothermal mineral deposits, such as gold requires using magnetic data, particularly, high-resolution aeromagnetic data. To define possible targets for mineral exploration, this study used linear detection and the Centre for Exploration Targeting (CET) techniques on high-resolution aeromagnetic data for structural delineation and interpretation. The study's conclusions indicate that the majority of geological features, such as faults, shears, fault intersections, and fracture systems, trend NE-SW, N-S, and occasionally NW-SE. These structures create potentially large areas that have a strong chance of becoming mineralized. The CET grid analysis technique defined mineralized zones, particularly the structural intersections which are potential targets in mineral exploration. The effectiveness of the CET technique in mineral prospecting was demonstrated by the correlation between the results and existing mineral occurrences (such as Shanta Gold Mine, abandoned pits, and the operating pits of small-scale miners in Muhintiri). Based on the findings reported herein, any sites that share characteristics with those that have demonstrated gold mineralization should be prioritized for ground follow-up</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Green and Blue Water Footprints of Major Crops in the Wami/Ruvu Basin, Tanzania: Implications for Water Scarcity and Sustainability 2024-04-30T13:02:27+00:00 Benson HM Lazaro Martine M Hagai Rubhera RAM Mato <p>Accurate estimation of the blue and green water requirements of the various crops cultivated in a water basin is essential for planning specific plant/crop irrigation schedules. In this study, the crop water requirements of the major crops grown in the Wami/Ruvu basin were determined using the FAO-CROPWAT model based on meteorological parameters: monthly maximum and minimum temperature, wind speed, mean relative humidity, sunshine hours, rainfall data, and effective rainfall for 23 hydro-meteorological stations distributed in the study area. The studied crops are rice, maize, beans, tomatoes, and sugarcane. The crop reference evapotranspiration (ETo) and actual evapotranspiration (ETc) for each crop were determined using crop coefficients (Kc) of various growth stages of crops. The results indicated that the total annual reference evapotranspiration (ETo) was 1604 mm, whereas an average ETo per month was 134 mm. The highest total irrigation water requirements were recorded in sugarcane, followed by rice, while the lowest water requirements were observed in beans and tomatoes. The results presented in this study may facilitate plant-specific water irrigation implementation and maximize crop production while conserving the environment.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Influence of Stacking Order on the Structural and Optical Properties of Cu2ZnSnS4 Absorber Layer Prepared from DC-Sputtered Oxygenated Precursors 2024-04-30T13:09:24+00:00 January S Gwaydi Hezekiah B Sawa Egidius R Rwenyagila Nathanael R Komba Talam E Kibona Nuru R Mlyuka Margaret E Samiji Lwitiko P Mwakyusa <p>Several studies have attempted to overcome the sudden volume expansion of the precursor during sulfurization by the use of oxygen-containing precursors when growing the CZTS absorber. This work demonstrates the influence of precursor stacking orders on the properties of the CZTS thin film absorber layer from DC-sputtered oxygenated precursors for solar cell applications. CZTS absorber layers were prepared from three types of DC-sputtered stacks, namely, Zn-O/Sn/Cu, Sn/Zn-O/Cu, and Sn/Cu/Zn-O. The precursors were sequentially deposited on a soda lime glass (SLG) using DC-magnetron sputtering and annealed in a sulfur and nitrogen ambient. X-ray diffractometry (XRD) and Raman spectroscopy analyses reveal the formation of crystalline kesterite CZTS structure regardless of the precursor stacking order. Atomic force microscope (AFM) analysis showed that CZTS thin films grown from precursor stacks SLG/Zn-O/Sn/Cu and SLG/Sn/Zn-O/Cu had improved morphological properties with densely packed large grains compared to that with stack SLG/Sn/Cu/Zn-O. SLG/Zn-O/Sn/Cu is the best stack among the studied stacking orders since it exhibits large grains in the absorber layer, which is preferential for high-efficiency thin film solar cells. The use of oxygenated precursor with order Sn/Zn-O/Cu promises improved CZTS absorber properties as it exhibits better morphological properties.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Extraction of Natural Dyes from Delonix regia Flowers for Cotton Fibres 2024-04-30T13:22:11+00:00 Lutamyo Nambela Liberato V Haule <p>Textile colouration is among the major industry that pollutes the environment with effluents rich in dye chemicals. Most of the dyes used are synthetics which possess health and environmental impacts. Potentially, the use of bio-based dyes and other chemicals can lessen the environmental challenges of the textile effluents. This study reports on sustainable extraction and dyeing of cotton fabric using extract of Delonix regia flowers. The extraction process was done using acid-ified water as a solvent and the dyeing process was free from hazardous auxiliary chemicals. To improve the dyeing performance, banana sap was used as an affordable and eco-friendly bio-mordant. To optimise energy consumption, dyeing experiments were done between room tem-perature and 90 °C. The dyeing performance was assessed through wash fastness, rub fastness and colour strength tests. The cotton fabric was successively dyed with the Delonix regia flowers extract rich in anthocyanin pigments in the presence of banana sap bio-mordant. The optimum dye performance was obtained at a dyeing temperature of up to 60 °C, above which the perfor-mance was negatively affected.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Genetic Characterization of Water Yam (Dioscorea alata L.) and Production Constraints of Yam in Pwani Region and Unguja Island, Tanzania 2024-05-02T04:53:05+00:00 Gladness E Temu Veneranda E Mlegi Nessie D Luambano <p>Yam (Dioscorea spp.) is a tuber crop cultivated in over 30% of all regions in Tanzania, contributing to the carbohydrate needs of many households. The morphological and genetic diversity of water yam (D. alata L.) local cultivars collected from Pwani region and Unguja Island were evaluated using 26 agro-morphological characters and 10 Short Sequence Repeat (SSR) markers. Cluster analysis using morphological characters classified nine water yam local cultivars into two main clusters with three subclusters. Tuber flesh and leaf colour were the main descriptors for clustering. The genetic diversity of 128 water yam genotypes using ten polymorphic SSR markers generated a total of 40 alleles that ranged from 2 to 7 per SSR marker. The mean polymorphic information content (PIC) ranged from 0.3 to 0.9, with a mean of 0.56. Cluster analysis separated 128 yam genotypes into two main clusters with five subclusters. The findings revealed relatively high genetic diversity of D. alata in the study areas. A structured questionnaire revealed drought (29.3%) and lack of planting materials (23.3%) as the major constraints to yam production in the study areas. Information reported in this study is useful in improving, reviving and promoting yam through breeding and conservation programs.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Modelling and Mapping of Forest Biodiversity Indicators Using Sentinel-2 and PlanetScope Remotely Sensed Data 2024-04-30T12:29:46+00:00 Diana L. Tesha Ernest W. Mauya Sami D. Madundo <p>Tropical montane forests harbour exceptionally high biodiversity yet face severe threats from human activities. Assessing forest biodiversity over large areas is crucial yet extremely challenging. Remote sensing provides an efficient monitoring solution, but few studies have focused on Tanzania's diverse, montane forests. We collected field data on tree species composition within 159 plots across montane forests in Tanzania's West Usambara region. We calculated species richness, evenness, and Shannon diversity index as indicators of tree diversity. Using Sentinel-2 and PlanetScope satellite imagery, we derived spectral, textural, and vegetation index predictors to model these indices via generalized additive models and extreme gradient boosting. PlanetScope-based XGBoost models performed best, explaining 19.7% of variation in Shannon diversity. Incorporating textural predictors further improved model accuracy. Despite inherent challenges in modelling complex tropical forests, our findings demonstrate promising potential of Sentinel-2 and PlanetScope for regional biodiversity monitoring where field surveys are limited. Further research could enhance these initial results by leveraging higher resolution data and increasing field sampling for effective monitoring of tropical biodiversity.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 The Effects of Algal Blooms on Oxygen Levels in Lakes Babati and Eyasi, Tanzania 2024-04-30T14:28:59+00:00 Amelia S. Buriyo1 Nyatwere D. Mganga Mary Melchiory <p>Globally aquatic ecosystems are reportedly overwhelmed by algal blooms due to excessive deposition of nutrients which ultimately cause hypoxia, leading to massive fish death. This study aimed at assessing the relationship between algae contents and dissolved oxygen (DO) in Lake Babati which is threatened by anthropogenic activities, whereas Lake Eyasi was used as a control. Algae contents (chlorophyll a), DO and surface water temperature were measured using standard methods. Results revealed that the mean algae content was significantly higher (4.47±0.88 mg/L) in Lake Babati than in Lake Eyasi (1.6±0.45 mg/L) (P &lt; 0.05) and was beyond the standard permissible levels for domestic water supply and healthy ecosystem. Conversely, DO was significantly lower in Lake Babati than in Lake Eyasi (P &lt; 0.05). There was no significant difference in water temperature in the two lakes (P &gt; 0.05). Furthermore, there was an inverse relationship between algae content and DO in Lakes Eyasi and Babati (r = -0.88 and r = -0.30, respectively) suggesting that algal bloom is partly responsible for lowering DO. Responsible authorities are advised to enforce management policies and regulations to control unsustainable activities around these lakes that contribute to nutrient loading resulting into overgrowth of algae.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Microbiological Quality of Irrigation Water and Leafy Vegetables in Dar es Salaam, Tanzania 2024-04-30T12:38:38+00:00 Bubelwa L Kamara Godwill D. Mrema Thomas J. Lyimo <p>The quality of water used for the irrigation of leafy vegetables in urban settings is in doubt due to contamination associated with poor hygiene and water pollution. This study examined the microbiological quality of irrigation water and leafy vegetables at Chang’ombe in Dar es Salaam, Tanzania as well as the perceptions and level of awareness of nearby consumers. Water and leafy vegetable samples were analysed for faecal coliform (FC) using standard techniques. Perception and awareness of consumers were collected using a questionnaire survey. The results showed an average FC count of 406.1 ± 16.40 MPN/100 ml for the irrigation water. The sweet potato leaves and amaranth had FC counts of 11.40 ± 5.220 CFU/g and 17.60 ± 11.98 CFU/g respectively. The levels of FC in irrigation water and leafy vegetables were within the allowed limits by WHO and NAS-USA standards respectively but fall short of some stricter European standards for irrigation water. The household survey showed that consumers perceive irrigation water at Chang’ombe as polluted and may be one of the main sources of food contamination. They minimize associated health risks in various ways such as using clean storage, washing and cooking. It was concluded that the microbial quality of water used for irrigation of leafy vegetables at Chang’ombe poses no risk to public health, but based on tighter standards, improved public awareness of hygienic practices is crucial to address potential risks.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Modelling the Combined Use of Long-Lasting Insecticidal Nets and Insecticides Zooprophylaxis Against the Resilience of Anopheles Arabiensis for Effective Malaria Control 2024-04-30T13:27:33+00:00 Watson Levens <p>Malaria is a significant public health concern, especially in tropical regions. It remains endemic in many areas where malaria mosquitoes are prevalent. This study investigates the viability of insecticide zooprophylaxis (IZ) in conjunction with Long Lasting Insecticidal Nets (LLINs) as a strategic approach to combat malaria transmission, particularly in regions dominated by zoophagic vectors. Through the presentation and analysis of a mathematical model that integrates IZ and LLINs for the control of Anopheles arabiensis (An. arabiensis), the research underscores IZ's role in reducing zoophagic vector populations and enhancing malaria control efforts. Notably, the study reveals that achieving comprehensive coverage of LLINs and IZ distribution systems can reduce the basic reproduction number (R₀) below 1. Furthermore, the research highlights the potential for substantial reductions in human biting rates, vectorial capacity and Entomological Inoculation Rate (EIR) when high intervention coverage encompasses all zoophagy blood sources for malaria vectors.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024 Modeling the Transmission Dynamics of Tuberculosis in Humans 2024-05-03T07:36:50+00:00 Farida Kisinda Joshua A. Mwasunda Mbwiga S. Aloni <p>Tuberculosis (TB) is a major threat to human health particularly in most of developing countries. In this article, we formulate and analyze a deterministic model for the transmission dynamics of pulmonary and extra-pulmonary tuberculosis. The next generation method is employed to find the basic reproduction number R<sub>0</sub> which helps to determine whether TB clears or persists in the human population. Global stability of model equilibria is done through Lyapunov functions whereas the normalized forward sensitivity index method is adopted to determine parameters that drive tuberculosis. Analysis shows that both TB free and endemic equilibria exist. <br>The TB free equilibrium is globally asymptotically stable whenever the basic reproduction number R<sub>0</sub> &lt; 1 whereas the endemic equilibrium is globally asymptotically stable whenever R<sub>0</sub> &gt; 1. Sensitivity analysis shows that the TB infection rate, the fraction of individuals who progress to pulmonary tuberculosis and its induced death drive TB. Numerical results indicate that when there are no interventions, susceptible humans decline significantly with time until when they are attracted to the steady state whereas latently infected, pulmonary and extra-pulmonary TB individuals increase until when they settle at the equilibrium states supporting the analytical results for existence of the endemic equilibrium. In light of these findings, we recommend treating humans infected with pulmonary TB who are carriers of the disease.</p> 2024-05-03T00:00:00+00:00 Copyright (c) 2024 Prevalence and Predictors of Cesarean Delivery in a Tertiary Hospital in Taraba State, Nigeria 2024-04-30T13:39:16+00:00 Olateju Alao Bamigbala Ayodeji Oluwatobi Ojetunde Maza Tanko <p>A cesarean section (CS) is a surgical technique in which a baby is delivered through an abdomen and uterine incision following fetal viability. It is imperative to identify the factors that influence the use of CS to reduce the needless use of this life-saving procedure and increase its availability for those who need it most. Therefore, this study assesses the prevalence and predictors of cesarean delivery in a tertiary hospital in Taraba state, Nigeria. Information of pregnant women who came for delivery to Federal Medical Center, Jalingo, Taraba state Nigeria from August 2021 to August 2023 was collected. Binary Logistic Regression using the probit model was used to analyse the data. p&lt;0.05 was considered to be statistically significant. During the study period, there were 747 deliveries 115 by caesarean section (15.4%). The results show that maternal age, location, occupation, maternal education, maternal weight, birth weight, and number of antenatal care (ANC) visits significantly predict cesarean delivery. The results of this research will help to make policies and decisions related to health issues and intensify efforts to make provisions and precautionary steps on managing and controlling cesarean birth.</p> 2024-04-30T00:00:00+00:00 Copyright (c) 2024