Tanzania Journal of Science https://www.ajol.info/index.php/tjs <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; Google Scholar; Journals for Free (J4F) database</p> <p><strong>For online submission please <a href="https://tjs.udsm.ac.tz/index.php/tjs/onlinesubmission" target="_blank" rel="noopener">click here</a></strong></p> College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM) en-US Tanzania Journal of Science 0856-1761 <p>Copyright for articles published in this journal is retained by the journal.</p><p>This journal provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge</p> Effects of Annealing Ambient on the Structural, Optical and Electrical Properties of TiO2:Ge Thin Films https://www.ajol.info/index.php/tjs/article/view/223365 <p>TiO<sub>2, </sub>a semiconducting material with a wide energy band gap, has been researched intensively due to its interesting properties and many potential applications. The films properties can as well be modified by preparing the films under diverse ambient to suit diverse applications. In this work, the effects of the annealing atmosphere on the structural, optical and electrical properties of pure TiO<sub>2</sub> and TiO<sub>2</sub>:Ge composite thin films deposited by sputtering from commercially available pure TiO<sub>2</sub> and TiO<sub>2</sub>:Ge (85:15) targets respectively were studied. The films were deposited on fluorine doped tin oxide glass substrates by radio frequency magnetron sputtering technique at room temperature 23–25 ℃ and then annealed at 450 ℃ for one hour in three different atmospheres: air, argon and nitrogen. The XRD results revealed that, both pure TiO<sub>2</sub> and TiO<sub>2</sub>:Ge thin films were crystalline and had a mixed phase of anatase and rutile regardless of the annealing ambient. The calculated crystallite sizes ranged between 19–21 nm with the particle sizes for TiO<sub>2</sub>:Ge films being larger compared to pure TiO<sub>2</sub> as calculated from ImageJ software. Electrical measurements showed that the resistivity of as deposited pure TiO<sub>2</sub> films (about 13.03 × 10<sup>–2 </sup>Ω-cm) was greater than the TiO<sub>2</sub>: Ge composite (5.91 × 10<sup>–2 </sup>Ω-cm). Furthermore, on annealing, pure TiO<sub>2</sub> had a resistivity of 9.47 × 10<sup>–2</sup> Ω-cm–10.4 × 10<sup>–2 </sup>Ω-cm, while the TiO<sub>2</sub>:Ge composite had a resistivity of 2.24 × 10<sup>–2</sup> Ω-cm–3.61 × 10<sup>–2 </sup>Ω-cm depending on the annealing atmosphere. Variation of annealing atmosphere had minimal influence on the electrical resistivity of the films. The films annealed in nitrogen recorded the least resistivity values averaging about 5.86 × 10<sup>–2</sup> Ω-cm, while those annealed in argon and air recorded a resistivity of 6.94 × 10<sup>–2</sup> Ω-cm and 6.65 × 10<sup>–2</sup> Ω-cm, respectively. The transmittance spectra showed that, all the annealed films were transparent in the visible region (400–700 nm) with a mean bandgap of 3.60 eV for each annealing atmosphere. It is recommended that films annealed in nitrogen atmosphere could be considered for potential applications in photovoltaics.</p> <p><strong>Keywords: </strong>Titanium dioxide; Germanium; Ambient; Structural; Optical, Electrical</p> Lilian A. Owino Sebastian Waita Robinson J. Musembi Francis W Nyongesa Copyright (c) 2022-03-31 2022-03-31 48 1 1 12 10.4314/tjs.v48i1.1 Distribution and Pattern of an Insurance Health Claim System: A Time Series Approach https://www.ajol.info/index.php/tjs/article/view/223253 <p>There is a continuous increase in health costs, thereby increasing pressure on individuals and consequently making the amounts claimed by the insured to be on the increase. In this study, data was collected from a large local insurance company in Zimbabwe for the period from January 2012 to December 2016. The aim of this study was to analyse the distribution and future pattern of insurance health claim system using time series approach. Akaike information criterion and Schwarz Bayesian criterion were used to select the adequate model through maximum likelihood estimation methods. &nbsp;ARIMA (0, 0, 0) (1, 0, 1) [12] is the model that was chosen to forecast claim amounts. The use of ARIMA models proves to be an excellent instrument for predicting and capturing the cost trend of health claims which can help in decision making to insurance companies.</p> <p><strong>Keywords:</strong>&nbsp;&nbsp;&nbsp; ARIMA; Box-Jenkins; health insurance; time series.</p> Maxwell Mashasha Praise Mutize Felix Mazunga Copyright (c) 2022 2022-03-31 2022-03-31 48 1 13 21 10.4314/tjs.v48i1.2 Evaluation of Pasting Properties of Plantain, Cooking Banana, Selected Cereals and their Composites as Indicators for their Food Values https://www.ajol.info/index.php/tjs/article/view/223254 <p>The pasting properties of unripe plantain, unripe cooking banana, some selected cereals and their composite flours were investigated in relation to their food values. Each of the samples was cleaned, air–dried and pulverized to form the native flours which were mixed in different proportions to form the composite flours. Soft doughs were prepared from the flours and subjected to textural evaluation. The adjudged best from each set was analysed using Rapid Visco–Analyser followed by determination of their proximate composition and functional properties. The results showed that the breakdown viscosity (cP) of each of the composite flours was less than 920.50 in plantain and 915.50 in cooking banana, indicating improved ability to withstand shear stress. The values of the final viscosity of the composite flours were generally lower than the native flours of plantain and cooking banana which indicated better flow property. The setback viscosities of the composite flours were lower than the native cereal flours except sorghum which indicated lower tendency to undergo retro–degradation. Furthermore, the composite flours gelled at lower temperature (72.1–84.9 °C) when compared with the native flours (82.7–89.2 °C) reflecting less energy requirement for cooking. Combination of cereals with plantain or cooking banana had led to production of composite flours which gave better and improved pasting properties without depreciation in functional properties and nutritional composition.</p> <p><strong>Keywords</strong>: Composite flour; Cereal–plantain; Cereal–cooking banana; Proximate composition; Functional and pasting properties.</p> Wasiu B. Agbaje Oluseye O. Abiona Shola H. Awojide Luqman A. Azeez Adeniyi S. Tayo Copyright (c) 2022 Tanzania Journal of Science 2022-03-31 2022-03-31 48 1 22 33 10.4314/tjs.v48i1.3 Design and Implementation of Distributed Identity and Access Management Framework for Internet of Things (IoT) Enabled Distribution Automation https://www.ajol.info/index.php/tjs/article/view/223435 <p>The smart grid and Internet of Things (IoT) technologies play vital roles in improving the quality of services offered in traditional electrical grid. They open a room for the introduction of new services like distribution automation (DA) that has a significant advantage to both utility companies and final consumers. DA integrates sensors, actuators, intelligent electrical devices (IED) and information and communication technologies to monitor and control electrical grid. However, the integration of these technologies poses security threats to the electrical grid like Denial of Service (DoS) attacks, false data injection attacks, and masquerading attacks like system node impersonation that can transmit wrong readings, resulting in false alarm reports and hence leading to incorrect node actuation. To overcome these challenges, researchers have proposed a centralized public key infrastructure (PKI) with bridged certificate authority (CA) which is prone to DoS attacks. Moreover, the proposed blockchain based distributed identity and access management (DIAM) in IoT domain at the global scale is adding communicational and computational overheads. Also. It is imposing new security threats to the DA system by integrating it with online services like IoTEX and IoTA. For those reasons, this study proposes a DIAM security scheme to secure IoT-enabled distribution automation. The scheme divides areas into clusters and each cluster has a device registry and a registry controller. The registry controller is a command line tool to access and manage a device registry. The results show that the scheme can prevent impersonated and non-legitimate system nodes and users from accessing the system by imposing role-based access control (RBAC) at the cluster level.</p> <p><strong>Keywords</strong>: Distributed Identity and Access Management; Electrical Secondary Distribution Network; Internet of Things; IoT Enabled Distribution Automation; Smart Grid Security</p> Ally T Bitebo Hellen Maziku Ndyetabura , Hamisi Charles N Tarimo Kwame S Ibwe Abdi T. Abdalla Copyright (c) 2022 2022-03-31 2022-03-31 48 1 34 46 10.4314/tjs.v48i1.4 Effects of Neem Aqueous Extract (Azadirachta indica) against Aphids and Aphid-borne Virus in Cowpea (Vigna unguiculata L. Walp) https://www.ajol.info/index.php/tjs/article/view/223256 <p>Pests and diseases are among the major factors limiting plant growth and yields. Pests are known vectors of pathogens including viruses. Proper management of plant pests is an indirect means of controlling viral diseases in plants. This study aimed at comparing the potential of neem extract and a synthetic insecticide (lambda cyhalothrin) for the management of aphids and <em>Cowpea aphid-borne mosaic virus</em> (CABMV) in five different cowpea (<em>Vigna unguiculata</em>) genotypes and to determine the residual effects of the insecticide in the cowpea grains. The experimental field was laid out in randomized complete block design with three replicates. Treatments included; spraying of cowpea plots with aqueous neem extract and lambda cyhalothrin (LC) twice at foliage stage, once at flowering and podding stages. Control plots were left unsprayed. Data were obtained on growth and yields of cowpea genotypes as well as the pest and virus disease traits. Results of the Analysis of Variance (ANOVA) revealed that variations attributable to genotypes were significant (p ≤ 0.01) for cowpea yields and virus disease traits. Treatments applied influenced the occurrence of pests and virus diseases. Neem extract reduced aphid infestations and virus diseases as much as the insecticide. Ife BPC accumulated a very high level of LC (1.14 ppm) in its grain when compared with the maximum residue level (MRL) for lambda cyalothrin in cowpea seeds. The study concludes that the use of eco-friendly bio-pesticide such as neem aqueous extract is effective for the management of aphids and aphid-borne virus in cowpea fields.</p> <p><strong>Keywords</strong>: Aphids; aqueous extract; cowpea; neem; pesticide; virus</p> Kehinde T. Kareem Rachael B. Olayinka Juliana A. Ugwu Olubusola F. Oduwaye Copyright (c) 2022 2022-03-31 2022-03-31 48 1 47 56 10.4314/tjs.v48i1.5 Resource Efficient Advanced Metering Infrastructure Model https://www.ajol.info/index.php/tjs/article/view/223258 <p>Advanced Metering Infrastructure (AMI) enables two-way communication between smart devices and utility control centers. This involves remote monitoring and control of energy consumption as well as other parameters in the electrical power network in real time. However, increasing technologies in AMI due to huge deployment of smart meters, integration of devices and application of sensors, demand a strong architectural model with the best network topology to guarantee efficient usage of network resources with minimal latency. In this work, a resource efficient multi-hop network architecture is proposed using hybrid media access protocols. The architecture combines queuing and random-access protocol to achieve optimal network performance. Numerical results show that the probability of delay incurred by an arbitrary smart meter depends on the mean and distribution of the queue switch over a period. It is also observed that for a single queued system, the throughput performance is equal to the existing hybrid method. As the number of smart meters increases to 500, the throughput of the proposed method improves by 10% compared to the existing method. Likewise, as the number of smart meters increases to 500, the delay reduced by 15% compared to the existing method.</p> <p><strong>Keywords</strong>: Advanced Metering Infrastructure; hybrid media access protocols; Smart Meter; Smart Grid; Power Network.</p> Josephina Kimambo Kwame S Ibwe Ellen Kalinga Abdi T. Abdalla Copyright (c) 2022 2022-03-31 2022-03-31 48 1 57 72 10.4314/tjs.v48i1.6 Geochemistry of Mafic-Intermediate Intrusive Rocks from the Twangiza-Namoya Gold Belt, Eastern Democratic Republic of Congo: Trace Element Constraints on their Origin, Petrogenesis and Tectonic Setting https://www.ajol.info/index.php/tjs/article/view/223367 <p>Bulk geochemical data for the Twangiza-Namoya Gold Belt, Democratic Republic of Congo, are presented in order to classify the rock assemblages, elucidate their petrogenesis and tectonic settings. Nb/Yb and Zr/Ti constraints reveal two suites for the rocks: sub-alkaline to andesitic basalts (Suite-1); and alkaline basalts (Suite-2).&nbsp; Ratios of Ti/Zr = 22–70; Zr/Hf = 35–42; Nb/Ta = 12–13; Nb/Th = 1–2 and La/Nb = 2.4–3.8 suggest arc-generated mantle melts with crustal inputs and arc-fluids metasomatism for Suite-1. The samples have positive LILE and negative Nb, Ta, Ti anomalies, enrichments in the LREE over middle and HREE (La/Yb)<sub>CN</sub> = 3.6–8.9 with negative Eu anomalies (0.7–0.9) in Chondrite-normalized diagrams. Yb-Th/Ta and Ta/Yb-Th/Yb ratios suggest active continental margin settings, whereas Ta/Hf-Th/Ta and Nb/Yb-Th/Yb diagrams suggest a depleted MORB source. Ti/Zr, Zr/Hf, Nb/Ta, Nb/Th and La/Nb constraints for Suite-2 suggest MORB and oceanic plateau basaltic sources. REE patterns show enrichments in the LREE with negative to positive Eu anomalies (0.7– 1.3). Yb-Th/Ta and Ta/Yb-Th/Yb ratios suggest a within plate tectonic setting. It is suggested that Suite-2 rocks were sourced from mantle-derived melts with a composition between an enriched MORB to OIB.</p> <p><strong>Keywords:</strong> Twangiza-Namoya; Petrogenesis; Tectonic setting; Trace element ratios</p> Gerald L. Chuwa Charles H. Kasanzu Copyright (c) 2022 2022-03-31 2022-03-31 48 1 73 87 10.4314/tjs.v48i1.7 Reproductive Potential of the Mackerel Scad, Decapterus macarellus (Cuvier, 1833) in the Coastal Waters of Tanzania https://www.ajol.info/index.php/tjs/article/view/223259 <p>This study investigated the reproductive biology of <em>Decapterus macarellus</em>&nbsp;locally known as ''Msumari", one of the most economically important scad fish along the coastline of Tanzania. Fish samples were collected from ring net artisanal fishers operating in Tanga and Bagamoyo coastal waters, monthly between April 2019 and September 2020. Findings indicated that&nbsp;<em>D. macarellus</em>&nbsp;spawns throughout the year with peaks in August at Tanga and September at Bagamoyo. Overall sex ratios (M: F) were 1:1.03 (Tanga) and 1:1.2 (Bagamoyo) in favour of females. The males and females of&nbsp;<em>D. macarellus</em>&nbsp;at Tanga attained the first maturity at 145.5 mm and 153.2 mm, respectively, whereas at Bagamoyo males attained first maturity at 149.9 mm and females at 156.9 mm. Batch fecundity was not statistically significant (<em>U</em>&nbsp;= 500.5;&nbsp;p&nbsp;= 0.73), with Tanga having mean values (± SE) of 46,105.9 ± 4243.4 ova and Bagamoyo 43,082 ± 2272.9 ova. Although this species appears to spawn all year round, management interventions such as seasonal closure and reduced fishing effort should be used during their spawning peaks to protect the spawners, recruits and ensure the species' long-term survival in the Tanzanian coastal waters.</p> <p><strong>Keywords: </strong>Scad; <em>Decapterus macarellus</em>; reproductive potential; ring net fishery; Tanzania.</p> Joseph S Sululu Blandina R Lugendo Benaiah L Benno Copyright (c) 2022 2022-03-31 2022-03-31 48 1 88 98 10.4314/tjs.v48i1.8 Suitability of Flood Hazard Assessment Methods for Tanzania: A Case of Little Ruaha and Upper Ngerengere Catchment https://www.ajol.info/index.php/tjs/article/view/223261 <p>Understanding the applicability of flood quantile estimation methods in flood hazard assessment is fundamental for planning, prevention, and management of flood risks. Therefore, this study evaluates and compares three hydrological methods, namely Hydrologiska Byråns Vattenbalansavdelning (HBV), Soil Conservation Service-Curve Number (SCS-CN), and regional regression equation (RRE), to estimate flood quantiles embedded in the existing flood damage assessment framework by applying them to two different river catchments, Little Ruaha (LR) and Upper Ngerengere (UN), Tanzania. The evaluation of method performance was carried out using three standard statistical measures for data from 1954 to 2010 and the 1971–1988 period in LR and UN catchments (LRC and UNC). The findings indicated that no single approach could fit all catchments and return periods for these case studies. Overall performance indicated that the RRE method provides more accurate and consistent quantile estimates than other approaches. These findings indicate that spatial scale, model structure, parameters, and hydro-climatic data condition are the most important elements influencing the suitability of the supplied methods for flood risk assessments, which serve as the foundation for developing an improved flood damage assessment framework.</p> <p><strong>Keywords:</strong>&nbsp;Flood Quantiles; Estimate Methods; Flood Risk Management; Little Ruaha; Ngerengere</p> Kashimbi J. Kihara Patrick Valimba Joel Nobert Copyright (c) 2022 2022-03-31 2022-03-31 48 1 99 108 10.4314/tjs.v48i1.9 The Role of Agricultural Social Enterprise to Smallholder Farmers’ Adaptive Capacity to Climatic Stresses in Tanzania https://www.ajol.info/index.php/tjs/article/view/223262 <p>This paper intended to ascertain the implications of agricultural social enterprise on the adaptive capacity of smallholder farmers to climatic stresses in the Kilolo District, Tanzania. The study used a sample of 90 households. Household questionnaires, focus group discussions (FGD), and key informant interviews were used to collect primary data for this study. Secondary data were collected through a review of literature relevant to this study. The content analysis was used to analyse qualitative data, whereas quantitative data were subjected to Statistical Product and Service Solution (SPSS) version 20 for analysis. Microsoft Excel 2007 was used to analyse rainfall and temperature data trends of the study area. Findings revealed that the agricultural social enterprise found in the study area (i.e. One Acre Fund-OAF) enhanced the adaptive capacity of smallholder farmers since the services it provided to its clients positively influenced the functioning of the determinants of adaptive capacity and consequently led to the increase of average maize production per acre by 54.5%. This study concludes that agricultural social enterprises such as OAF have the potential to enhance smallholder farmers’ adaptive capacity to climatic stresses, however other stakeholders should come together to support this cause.</p> <p><strong>Keywords</strong>&nbsp; Climatic stresses; Adaptive capacity; Social enterprises; Social entrepreneurship</p> Stanley G Kulanga Noah M Pauline Copyright (c) 2022 2022-03-31 2022-03-31 48 1 109 123 10.4314/tjs.v48i1.10 Solar cells: Types, Modules, and Applications–A Review https://www.ajol.info/index.php/tjs/article/view/223263 <p>The basic operating principle of photovoltaic (PV) devices is the conversion of solar irradiation into electricity. There are various applications of this principle in many countries such as Egypt, Nigeria and Denmark. Most of the solar PV projects are designed for street lighting, water pumping and water desalination. However, we hope about wide range of using the appropriate components and best technical procedures, standard PV projects with maximum performance output. The present systems now provide 20% to 40% only of the community's heat or lightness on annual basic needs. These include innovative and alternative ways to reduce material uses and module degradation, and opportunities to reuse and recycle PV panels at the end of their lifetime because of the installations of photovoltaic solar modules which are growing extremely very fast.&nbsp;&nbsp;</p> <p><strong>Keywords</strong>: Solar cells; renewable energy; photovoltaic; free energy; solar panel cost; solar battery.</p> Amira Abd-elfattah Darwish Rana S. Abdelmohsen Mohamed Ahmed M. Megeed Copyright (c) 2022 2022-03-31 2022-03-31 48 1 124 133 10.4314/tjs.v48i1.11 Investigation of the Vertical Profile Radio Refractivity Gradient and Effective Earth Radius Factor (k-factor) in Transmission Link Over Oyo, Oyo State, South Western Nigeria https://www.ajol.info/index.php/tjs/article/view/223369 <p>Surface radio refractive gradient and k-factor are very imperative in observing propagation conditions, designing and planning of microwave communication links in the lower part of the atmospheric boundary layer. The measurement of weather variables (air temperature, atmospheric pressure, relative humidity and wind speed) were conducted in this study at the School of Science, Emmanuel Alayande College of Education, Oyo (7.83°N, 3.95°E), Oyo State, Nigeria. The research was carried out for a period of one year (January to December, 2020) using self-designed cost effective portable weather monitoring systems. The systems were sited from the ground to a height of 200 m on a 220 m Nigeria Television Authority (NTA) UHF channel 37 tower at Oke-Apitipiti in Oyo Town of Oyo State. The calculated daily and monthly averages data are employed to investigate the vertical surface radio refractivity and its refractivity gradient. The highest value of -1.093E+26 N-units/km was recorded in January, while the month of July experienced the least of about -9.305E+19 N-units/km. The months of January–July verified sub-refractive conditions with propagation conditions having varying degree of occurrence. On the other hand, super-refraction and ducting were recorded mostly between August–December from the study. The results also find applicability in radio engineering for refining VHF/UHF terrestrial links based on clear-air considerations which will support operational planning of terrestrial radio networks in Oyo, South Western Nigeria</p> <p><strong>Keywords: </strong>Microwave; k-factor; refractivity gradient; sub-refractive; super-refraction</p> Akeem L. Sheu Kamaldeen O Suleman Qasim A Adeniji Copyright (c) 2022 2022-03-31 2022-03-31 48 1 134 139 10.4314/tjs.v48i1.12 Synthesis of Polydispersed P(St-MMA-AA) Microspheres and Fabrication of Colloidal Crystals with Non-Compact Morphology https://www.ajol.info/index.php/tjs/article/view/223384 <p>Great attention has been given to the synthesis of monodispersed and uniform colloidal polymer particles with controllable particle sizes. However, investigations on the preparation, characterization and fabrication of polydisperse polymeric particles are very few. Polydisperse polymers are also needed to meet the new demands of the modern markets due to the ease of their synthesis. This study, therefore, synthesized polydispersed poly(styrene-methyl-methacrylate acrylic-acid) (P(St-MMA-AA)) via emulsion polymerization synthetic approach under unstable reaction conditions. The synthesized P(St-MMA-AA) microparticles were characterized using Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), a thermo-gravimetric analyzer (TGA) and scanning electron microscope (SEM). The DLS results revealed a highly polydispersed P(St-MMA-AA) microparticles with an average particle diameter of 803.4 nm. SEM, TEM (transmission electron microscopy) and AFM (atomic force microscopy) analyses showed that the particles were spherical and polydispersed. The unequal diameters and non-compact nature of the fabricated colloidal crystals may have affected its possible uses in some specific applications such as decorative coatings, biomedical and sensing applications. However, other materials can be incorporated into the polydispersed prepared P(St-MMA-AA) colloidal microspheres to improve their properties and possible applications.</p> <p><strong>Keywords</strong>: Emulsion polymerization; Polydispersed; Polymer; P(St-MMA-AA).</p> Ikhazuagbe H. Ifijen Eribe M. Jonathan Jacob N. Jacob Nyaknno U. Udokpoh Ukeme D. Archibong Copyright (c) 2022 2022-03-31 2022-03-31 48 1 140 147 10.4314/tjs.v48i1.13 Boron Doped ZnO Films Deposited by DC Reactive Sputtering Using Zn:B Target: Influence of the Deposition Temperature on the Structural, Electrical and Optical Properties https://www.ajol.info/index.php/tjs/article/view/223436 <p>ZnO-based transparent and conducting oxides (TCOs) are commonly used as a window layer in thin-film solar cells. However, TCOs with high transparency in the visible and near-infrared parts of the electromagnetic spectrum, plus excellent electrical properties are required in this application. In this study, TCOs based on ZnO:B films deposited by DC reactive sputtering using Zn:B alloy target were investigated. The impact of deposition temperature on the growth and physical properties of the films was examined. Structural, optical and electrical properties of these films were investigated by means of x-ray diffraction (XRD), Ultraviolet-Visible-Near Infrared (UV-VIS-NIR) spectroscopy, and Hall effect measurement, respectively. The XRD analysis revealed that all films are of hexagonal wurtzite structures, with a preferred orientation along the <em>c</em>-axis. The optical spectroscopy results indicated that all the ZnO:B films had optical transparency above 90% in the visible region which then slightly decreased in the near-infrared region. The highest carrier concentration, conductivity, and mobility were obtained at the deposition temperature of 300 °C–due to improvement in crystal growth–while higher temperatures slightly deteriorated the electrical properties, possibly due to a slight decrease in the crystallite size.</p> <p><strong>Keywords: </strong>ZnO; Transparent and conducting oxides; ZnO:B, DC reactive sputtering; deposition temperature</p> Lwitiko P. Mwakyusa Nuru R. Mlyuka Margaret E. Samiji Copyright (c) 2022 2022-03-31 2022-03-31 48 1 148 155 10.4314/tjs.v48i1.14 Influence of Roasting on the Proximate, Functional and Sensory Properties of Jackfruit Seeds and Amaranth Grain Composite Complementary Flours https://www.ajol.info/index.php/tjs/article/view/223493 <p>This study evaluated the effects of roasting on jackfruit seeds (JFS) and amaranth grain composite complementary flours. Eleven formulations were used for the study. The moisture, crude protein, crude fat, crude fibre, crude ash and carbohydrate contents varied from 6.5 to 8.7%, 10.66 to 20.9%, 0.93 to 5.98%, 4.46 to 10.2%, 2.6 to 3.76% and 51.3 to 71.7%, respectively. The water absorption capacity (WAC), water solubility index (WSI), oil absorption capacity, swelling power (SP) and bulk density (BD) ranged from 238.9 to 360.5%, 3.9 to 12%, 107.4 to 200.6%, 13.3 to 45.9%, and 0.5 to 0.7 g/mL, respectively. Increasing amaranth flour and roasting JFS increased the WSI and SP but decreased the WAC and BD. The peak viscosity, breakdown viscosity, final viscosity, setback viscosity, peak time and pasting temperature varied from 326.5 to 1292 RVU, 15 to 417 RVU, 432 to 1334.5 RVU, 138.5 to 4595 RVU, 4.09 to 7 minutes and 79 to 90.1 °C, respectively. Viscosity of the flours increased with increase in grain amaranth. The porridges made with roasted JFS yielded higher sensory scorers, hence suitable for complementary feeding.</p> <p><strong>Keywords:</strong>&nbsp;&nbsp;&nbsp; Jackfruit seeds; Amaranth; Composite flour.</p> Agnes Nabubuya Robert Mugabi Abraham Kaggwa Paddy Ainebyona Rukia Nalugya Copyright (c) 2022 2022-03-31 2022-03-31 48 1 156 169 10.4314/tjs.v48i1.15 Assessment of the Impact of Climate Change on Stream Flow: The Case of Little Ruaha Catchment, Rufiji Basin, Tanzania https://www.ajol.info/index.php/tjs/article/view/223494 <p>Little Ruaha catchment has been recognized for its potential to support multi-projects including irrigated schemes, urban water supply and providing significant inflow to Mtera reservoir for hydropower generation and ultimately Julius Nyerere Hydropower Plant (JNHPP). &nbsp;Despite the potential, the catchment has experienced declining flows in the recent years. This study assessed the likely changes in streamflow due to future climate change in the Little Ruaha catchment for the period 2025-2060. General Circulation Model (GCM) datasets from ACCESS1.0, CNRM-CM5 and BCC-CSM1 models and RCP4.5 and RCP8.5 greenhouse gas concentration scenarios were selected as the representative scenarios. Impact of climate change on stream flows was assessed using the calibrated NAM hydrological model. The impact assessment results show that under the climate change scenario (2025–2060), the monthly maximum and minimum temperatures will increase in the range of 0.8 °C to 2 °C for both RCP4.5 and RCP8.5 scenarios. For the case of rainfall, average annual rainfall is expected to increase by about 10% compared to the baseline. However, the inter-annual variability of rainfall for the period between 2025 and 2060 shows the decreasing trend for RCP 8.5. The simulation results show that streamflow will decrease by about 30% and 6% for RCP4.5 and RCP8.5, respectively.</p> <p><strong>Keywords</strong>: Hydrological modelling; climate change scenarios; hydrological impacts; Little Ruaha.</p> Joel Nobert Copyright (c) 2022 2022-03-30 2022-03-30 48 1 170 184 10.4314/tjs.v48i1.16 Using Constructed Wetlands to Remove Pathogenic Parasites and Fecal Coliforms from Wastewater in Dar es Salaam and Iringa, Tanzania https://www.ajol.info/index.php/tjs/article/view/223728 <p>Wastewater treatment is a widely used health protection measure that can be applied to control the transmission of wastewater-related infectious diseases to communities exposed to wastewater. This study determined the efficiency of three full-scale constructed wetlands (CWs) in removing pathogenic parasites and fecal coliform (FC) bacteria from wastewater. Wastewater samples were collected from three CW systems located in the Dar es Salaam and Iringa regions of Tanzania. The modified Bailenger and modified Ziehl-Neelsen stain techniques were used to detect and quantify parasites. The membrane filtration method was used to detect and quantify FC bacteria. Data were analysed using IBM SPSS version 20. Helminth (<em>Ascaris lumbricoides</em>, hookworm, and <em>Taenia</em> spp.) eggs were completely removed by two CW systems. In all the systems, the removal of protozoa ranged from 99.8% to 100%. The mean concentrations of FCs in effluents ranged from 5 to 6 log units/100 mL. Effluents of all CW systems met the recommended parasitological quality requirements of the World Health Organization for the safe reuse of wastewater. FC effluents concentrations did not meet the local discharge standards of the Tanzania Bureau of Standards. Therefore, improvement to the CWs’ design, operation, and maintenance are required for the efficient removal of bacteria.</p> <p><strong>Keywords</strong>: helminth, protozoa, fecal coliform, wastewater treatment, constructed wetland</p> Abdallah Zacharia Wajihu Ahmada Anne H. Outwater Billy Ngasala Rob Van Deun Copyright (c) 2022 2022-03-31 2022-03-31 48 1 185 195 10.4314/tjs.v48i1.17 Mathematical Modelling of Syphilis Transmission Dynamics: Impacts of Mass Media Report, Risky Sexual Behavior and Treatment https://www.ajol.info/index.php/tjs/article/view/223729 <p><strong>Abstract</strong></p> <p>Syphilis is one of the deadly sexually-transmitted diseases. This paper studied the impacts of sexual behavior, mass media report and treatment of infected individuals on the dynamics of syphilis transmission. The analytical and numerical analyses of the model are presented. The disease free equilibrium of the model is both locally and globally asymptotic stable when the associated reproduction number is less than unity.&nbsp; Analysis of the Reproduction number shows that it is not possible to control syphilis disease transmission if the rate of individuals practicing risky sexual behavior is high. Furthermore, the treatment of late (latent and tertiary) syphilis infection is beneficial to the infected individuals, but has no impact in the lowering of the reproduction number. This study suggests that the effective control strategy of syphilis must focus on lowering the number of individuals practicing risky sexual behavior and applying higher treatment rates for early syphilis infections. Furthermore, the media function should address the issues regarding safe sexual behavior.</p> <p><strong>Keywords</strong>: Syphilis, sexually transmitted infection, Risky sexual behavior, Mass media</p> Gasper G. Mwanga Copyright (c) 2022 2022-03-31 2022-03-31 48 1 196 211 10.4314/tjs.v48i1.18 Assessment of Soil Quality along the Proposed Main Road through Ngorongoro and Northern Serengeti, Tanzania https://www.ajol.info/index.php/tjs/article/view/224012 <p>A new road through northern Serengeti National Park is proposed to be built. The purpose of this study was to collect baseline data on soils along the route of the proposed road before its construction. The physicochemical properties were used to characterize the soil before the construction of the proposed road. Levels of soil macro-elements mainly potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na), and physicochemical properties: electrical conductivity (EC), pH, organic carbon (OC), soil organic matter (SOM), total nitrogen (TN), cation exchange capacity (CEC), phosphorus (P), aluminium (Al) were determined. Also, heavy metals: cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni) and zinc (Zn) were analyzed. This study was done on the eastern (Ngorongoro District) and western (Serengeti District) segments of the proposed road. The ranges in average values obtained for the physicochemical parameters and metal concentrations in the soils were: 0.05–0.57 mS/m for EC, 6.5–7.9 for pH, 0.71–1.23% for OC, 0.30–0.74 g/kg for TN, 1.23–2.12% for SOM, 20.6–79.7 mg/kg for available P, 0.27–2.08 meq/100-g for available K, 9.89–30.3 meq/100-g for available Ca, 0.29–0.67 meq/100-g for available Mg, 0.06–1.35 meq/100-g for available Na, 11.04–33.12 meq/100-g for CEC, 46702.9–63963.3 mg/kg for Al, BDL for Cd, 24.70–101.55 mg/kg for Cr, 27.31–34.96 mg/kg for Cu, 32390.8–42439 mg/kg for Fe, 18.06–22.19 mg/kg for Pb, 957.1–1458.9 mg/kg for Mn, BDL for Hg, 20.24–32.52 mg/kg for Ni and 96.09–124.14 mg/kg for Zn. These observed levels indicate that the soils before road construction are unpolluted, moderately fertile and within the specifications of good agricultural soil. On the western segment of the proposed road, the soil will need application of fertilizers for better agricultural usage.</p> <p><strong>Keywords:&nbsp;&nbsp;&nbsp; </strong>Physicochemical properties; soil quality; total nitrogen; macro-elements; heavy metals.</p> Othman C. Othman Abiud L. Kaswamila Kjetil Bevanger Augustino Mwakipesile Kelvin Haule Emilian Kihwele Gloria Summay Emmanuel Gereta Copyright (c) 2022 Tanzania Journal of Science 2022-04-14 2022-04-14 48 1 212 224 10.4314/tjs.v48i1.19 Investigation of the Effects of Some Statistical Data Components on the Selection of Optimum Smoothing Constant https://www.ajol.info/index.php/tjs/article/view/224011 <p>Simple exponential smoothing is one of the best forecast methods, especially for time series data. Its efficacy depends on a parameter called smoothing constant (α) which, if optimally determined, minimises the mean square error (MSE), the mean absolute error (MAE) and the mean absolute percentage error (MAPE). The widely used method for selecting the optimum smoothing constant is to conduct a grid search within a wide range of possible values of α using the trial-and-error method. Not only that this method involves the knowledge of advanced statistical processes, but it is also time-consuming, and its results are limited to the data being analysed. In order to eliminate these limitations, there is a need to develop a benchmark that will guide the users of simple exponential smoothing to select the optimum α without necessarily repeating the trial-and-error method once a value has been established for data of similar statistical components. This study investigated some statistical components (mean, standard deviation, range, number of observations and pattern) of data to determine which components could aid in the quick and easy determination of optimum smoothing constant. The study determined the optimum smoothing constants for 16 different data of varying statistical components, and found that mean, standard deviation, range and the number of data observations are not related to the optimum smoothing constants. However, the demand pattern is an excellent precursor to determining the optimum smoothing constant. The study recommends further study in developing a classification model for demand patterns in job shops.</p> <p><strong>Keywords: </strong>Simple exponential smoothing; optimum smoothing constant; trial and error; demand pattern; number of observations.</p> Musibaudeen O. Idris Busayo S. Adeboye Buliaminu Kareem Godwin C. Enwerem Selimot A. Adekanye Copyright (c) 2022 2022-04-14 2022-04-14 48 1 225 234 10.4314/tjs.v48i1.20