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>Indexed/Abstracted in: African Journals OnLine (AJOL); CAB International or CABI (Centre for Agriculture and Bioscience International, UK); CAB Direct; CAB Abstracts; CAB Global Health; 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> en-US <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> tjs@udsm.ac.tz (Prof. John Andrew Marco Mahugija) cmgina@yahoo.com (Dr. Clarence Anthon Mgina) Wed, 01 Dec 2021 13:09:45 +0000 OJS http://blogs.law.harvard.edu/tech/rss 60 Mitigating the Spread of Measles under Constrained Health Care Resources in Tanzania using Social Contact Network Models https://www.ajol.info/index.php/tjs/article/view/217981 <p>Tanzania revaccinates individuals during measles outbreaks, despite having scant healthcare resources. We construct epidemiological models of measles spread by employing a hybrid of existing social contact networks models to develop SEIR simulation model. Using demographic and measles surveillance data from three rural villages in Tanzania, we simulate the spread of measles and examine which vaccination strategies can effectively control outbreaks. Results strongly indicate the spread of measles largely depends on contact rates among infected individuals within a population. Findings indicate a need for targeted vaccination for children of 6 months to 15 years of age, but equally for unvaccinated older age groups who were born before 1957 or missed the second dose. This work contributes theoretically and methodologically to existing applications of social contact network models for airborne infectious diseases in areas with health system constraints. It sets out implications for the design of effective vaccination programs for control of measles in Tanzania and in other developing countries.</p> <p><strong>Keywords:</strong> Vaccination strategies, Control strategies, Social contact network models, Airborne infectious diseases, Measles.</p> Herieth Rwezaura, Seán McGarraghy Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217981 Wed, 01 Dec 2021 00:00:00 +0000 Optical and Chemical Properties of Fragaria ananassa and Galena: Potential Photosensitizers in a Natural Dye-Sensitized Solar Cell https://www.ajol.info/index.php/tjs/article/view/217538 <p>Dye is one of the major components for high power conversion efficiency in a dye-sensitized solar cell. There are challenges natural dyes encounter, especially with quick degradation of the dye molecules. This work considered mineral dye in comparison with plant dye to address the challenge of degradation of natural plant dyes. The optical properties and functional groups of the two natural dyes were studied in this work. The absorption spectra, the optical band gaps and the absorption coefficients of the dyes were reported and found to be suitable for use as photosensitizers in a dye-sensitized solar cell (DSSC), as they absorb in the visible region of the electromagnetic radiation. The functional groups were studied by carrying out Fourier transform infrared spectroscopy and the amine, carbonyl and hydroxyl groups present in both dyes confirmed promising material that can absorb solar radiation in the visible region (around 380–800 nm) and which finds application in fabricating DSSC. The organic compositions in the mineral dye are studied via the gas chromatography-mass spectrometry and the results justify the observation from the FTIR spectroscopy. The properties observed, via the characterizations techniques used, confirm materials suitable for use as photosensitizers in fabricating DSSC.</p> <p>Keywords: Plant dye, Mineral dye, Photosensitizer, Visible region, DSSC.</p> Ibukun S Akinsola, Aderemi B Alabi, Coppede Nicola Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217538 Wed, 01 Dec 2021 00:00:00 +0000 Environmental Noise Pollution and its Impacts on the Hearing Ability of Men and Women in Ilorin, Kwara State, Nigeria https://www.ajol.info/index.php/tjs/article/view/217539 <p>Noise is an environmental disturbance that has harmful effects on the physiological and psychological lives of human beings and animals. This work examined the perceived health implications associated with noise pollution on both genders in Ilorin, Nigeria. It specifically identified the major sources of noise pollution, assessed noise pollution levels in the selected areas and determined the differences in the impacts of noise pollution on the health of both genders in Ilorin. A total of 384 respondents were sampled. Sound Level Meter (SLM) was used to ascertain the levels of noise in the study areas. Descriptive statistics and ANOVA were used to analyze the gathered data. Findings revealed that 73.2% of the respondents believed that traffic constitutes the highest source of noise pollution while others include music studios (63.3%), hotels/night clubs (52.1%) and power generating sets (50%). Noise levels were higher than the acceptable recommended noise level of 65 decibels for commercial and 55 decibels for commercial/residential locations by NESREA. Findings further revealed that males are more susceptible to the effects of noise pollution than females. Hence, possible mitigation measures such as noise pollution regulatory policy enactment and design of noise absorbing structures are strongly recommended</p> <p><strong>Keywords</strong>: Diseases, Gender, Health Risks, Impacts, Noise.</p> Afolabi M Tunde, Salamat Abdulquadri Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217539 Wed, 01 Dec 2021 00:00:00 +0000 Paleodepositional Environment and Sequence Stratigraphy of Miocene Sediments in Well TN-1, Coastal Swamp Depobelt, Niger Delta Basin, Nigeria https://www.ajol.info/index.php/tjs/article/view/217540 <p>This research focused on the interpretation of paleodepositional environment and development of a sequence stratigraphic framework for the well TN-1 section, located in the coastal swamp depositional belt of the Niger Delta Basin. Integration of interpreted litho- and biofacies data sets that facilitated the interpretation of the paleodepositional environment enabled the erection of a sequence-stratigraphic framework. Three lithotypes (sand, clay, and shale) distributed within fourteen facies variants were integrated with palynomorph components to delineate five paleodepositional cycles ranging from distal delta plain to bathyal. Eight systems tracts (closely related to depositional cycles, but transcended depositional boundaries in some intervals) that hosted three maximum flooding surfaces (MFS), three sequence boundaries (SBs), distributed within four third-order and three second-order sequences, were defined. Age-significant palynomorphs recovered indicated an Aquitanian to Messinian age range (with non-deposition or erosion of Burdigalian, Langhian, Serravallian Stages sediments), distributed within five pollen zones (P628–P840) that correlated with published global cycles. This study demonstrates the significance of integrated studies to erect a sequence-stratigraphic framework applicable for field and basin-scale exploration and exploitation purposes.</p> <p><strong>Keywords</strong>: Sequence stratigraphy, paleodepositional cycles, systems tract, cyclic sedimentation,<br>lithofacies analysis, integrated studies.</p> Jerry Osokpor, Efetobore G Maju-Oyovwikowhe Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217540 Wed, 01 Dec 2021 00:00:00 +0000 Effects of Copper Fungicides Spray on Nutrient Contents in Soils of Cocoa Growing Areas of Southwestern Nigeria https://www.ajol.info/index.php/tjs/article/view/217541 <p>The present study aimed at evaluating the effects of copper fungicides spray on physical and chemical properties of soils of cocoa growing areas of southwestern Nigeria. Samples were collected from selected cocoa farms and adjacent plots across three states (9 samples from Osun State, 9 samples from Ondo State and 7 samples from Ekiti State), within rainforest zone of Nigeria. The physical and chemical properties of the soil samples were determined. Copper contents of the cocoa plantation soils were significantly higher (16.23 mg Cu/kg) than the adjacent plots (6.31 mg Cu/kg) indicating accumulation of Cu in the soil because of long-term Cu fungicides spray. Other chemical properties determined (pH, Zn, % organic matter, % total N, Ca, Mg and Na) also had higher values in cocoa plantations compared to adjacent plots. Significant decrease was observed in available P in soil samples from cocoa plantations (24.05 mg P/kg) when compared with adjacent plots (30.36 mg P/kg). Management practices like applications of K and P fertilizers are highly recommended for viable cocoa growth and optimum yield in the study areas. Reduction of canopy formed by cocoa trees will allow easy penetration of sunlight into cocoa plantation thereby increase the rate of organic matter decomposition.</p> <p><strong>Keywords</strong>: Copper, fungicide spray, cocoa farms, black pod disease.</p> Musibau O Azeez, Olusola O Adesanwo, Joseph A Adepetu Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217541 Wed, 01 Dec 2021 00:00:00 +0000 Development of Biodegradable Food Packaging Materials from Agricultural Biomass https://www.ajol.info/index.php/tjs/article/view/217546 <p>This study utilised maize husk fibres and pulp to prepare a biocomposite fabric for food<br>packaging. The optimum conditions for extracting maize husk fibres were determined<br>experimentally to be 5 g/l of sodium hydroxide concentration at 100 °C for 60 minutes and liquor ratio of 1:20. The fabric was manufactured by solution casting of maize husk pulp on a web prepared by aligning maize husk and sisal fibres using a deckle and frame. The sisal fibre content was varied from 5 to 50% at ratios ranging from 95:5 to 50:50 (maize: sisal fibres). The biodegradable fabric was characterised using three mechanical properties: tear strength, tensile strength, and abrasion resistance. The tear strength ranged from 0.79 MPa to 3.93 MPa whereas the tensile strength ranged from 13.35 MPa to 56.46 MPa, which conforms to the data available from literature. Abrasion tests verified that there was no mass loss at 5,000, 10,000 and 15,000 cycles. Overall, the study findings show that maize husk fibres can replace up to 80% of sisal<br>fibres in materials for food packaging applications without compromising their quality.</p> <p><strong>Keywords</strong>: Maize husk fibre, biocomposite, sisal fibres, food packaging.</p> Jerome M Bidu, Arnold Towo, Liberato , Haule, Joshua C William, Lilian D Kaale Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217546 Wed, 01 Dec 2021 00:00:00 +0000 Rural Electrification using Iliceto Shield Wire Scheme in Developing Countries: Tanzania Case Study https://www.ajol.info/index.php/tjs/article/view/217552 <p>Rural electrification rate in Tanzania is still very low despite the efforts made by the Rural Energy Agency (REA) in Tanzania. Rural electrification using medium voltage (MV) method has two major obstacles. First obstacle is high cost associated with the cost of extending the grid electricity to rural areas. Second obstacle is remoteness of the villages, which leads to high power loss during transmission. In lieu of economic extension of rural electrification areas, this paper proposes a low cost solution of Iliceto Shield Wire Scheme (ISWS). This technique involves insulating shield wires (SW) from high voltage (132-400 kV) transmission line and energizing (11-33 kV) them from nearby substation at one line and use ground as MV phase conductor. The paper undertakes literature review of ISWS technology as installed in other developing countries. After that, a case study is selected in Mpaji village in Tanga region Tanzania. Analysis was made on voltage drop, power flow and cost for rural electrification using ISWS technology. Using ISWS for Mpaji village resulted in 10.89% voltage drop with total investment cost of about 49.4% compared to MV conventional method.</p> <p><strong>Keywords:</strong> Iliceto Shield Wire Scheme (ISWS), Medium Voltage, Rural Electrification</p> Heavenlight M Munisi, Santos Kihwele Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217552 Wed, 01 Dec 2021 00:00:00 +0000 Determination of Cramer-Rao Lower Bound (CRLB) and Minimum Variance Unbiased Estimator of a DC Signal in AWGN Using Laplace Transform https://www.ajol.info/index.php/tjs/article/view/217553 <p>This paper presents an alternative approach for the determination of Cramer-Rao Lower Bound (CRLB) and Minimum Variance Unbiased Estimator (MVUE) using Laplace transformation. In this work, a DC signal in Additive White Gaussian Noise (AWGN) was considered. During the investigation, a number of experiments were conducted to analyze different possible outputs under different conditions, and then the patterns of the outcomes were studied. Finally closed-form expressions for the CRLB and MVUE were deduced employing the Laplace transformation. The resulting expressions showed that the proposed method has almost the same number of steps as the existing method. However, the latter requires only the knowledge of algebra to arrive at the CRLB expressions contrary to the existing approach where a strong mathematical background is required and hence making it superior over the existing method, in that sense.</p> <p><strong>Keywords: </strong>Additive White Gaussian Noise, Cramer-Rao Lower Bound, DC-Value, Laplace transform, and Minimum Variance Unbiased Estimator (MVUE).</p> Abdi T Abdalla Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217553 Wed, 01 Dec 2021 00:00:00 +0000 Temperature Effects on the Corrosion Inhibition of Mild Steel in Sulfuric Acid Solution by Acacia senegal Gum with Halide Ions https://www.ajol.info/index.php/tjs/article/view/217554 <p>The effects of temperature on the inhibitive effect of naturally occurring <em>Acacia senegal</em> gum exudate on the corrosion of mild steel in sulfuric acid was studied between 35 and 70 °C using electrochemical impedance spectroscopy and potentiodynamic polarization methods. Findings showed that <em>Acacia senegal</em> gum exudate decreases the corrosion rate of mild steel. The inhibition efficiency declined with raising temperature above 35 °C. The increase in the corrosion rate with increasing temperature was observed for both uninhibited and inhibited systems. Addition of halide ions to the <em>Acacia senegal</em> gum exudate solution enhanced the corrosion inhibition efficiency because of synergistic effects, achieving higher performance with iodide ions as compared to bromide ions. However, the synergistic effects declined above 35 °C up to 70 °C due to temperature effects. It has been observed that increasing temperature adversely affected inhibition efficiencies of both <em>Acacia senegal</em> gum exudate and the synergy between <em>Acacia senegal</em> gum exudate and halide ions. Corrosion rates of mild steel, inhibition efficiencies of <em>Acacia senegal</em> gum exudate and the synergistic effects of halide ions from polarization and impedance measurements were consistent.</p> <p><strong>Keywords</strong>: temperature, corrosion, mild steel, synergistic effects, <em>Acacia senegal</em>, gum exudate.</p> Jovine Emmanuel, Joseph Buchweishaija Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217554 Wed, 01 Dec 2021 00:00:00 +0000 Physico-chemical Properties of Mechanically Extracted Banana Juice at Different Ripening Stages https://www.ajol.info/index.php/tjs/article/view/217555 <p>This paper presents the findings of a study on physico-chemical properties of low viscosity banana juice from five banana cultivars: Pisang Awak (PSA) an ABB genome, Yangambi km5 (YKM5) an AAA genome and cultivars from AAA-EA genome, namely <em>Mbilabile, Ndeshi</em> and <em>Mlonga</em>. Low viscosity banana juice was extracted using improved mechanical method at five ripening stages. The physico-chemical properties significantly varied according to cultivars and ripening stages (<em>p </em>&lt; 0.05). Yields, total soluble solids (TSS), titratable acidity (TA) and pH were in the range of 19.50–74.03%, 7.33–27.64 ºBrix, 0.37–0.76% malic acid equivalent and 4.09–4.70, respectively. Yields decreased in the order of <em>Mbilabile &gt; Ndeshi &gt; Mlonga </em>&gt; YKM5 &gt; PSA whereas the total soluble solids increased as follows <em>Mlonga &lt; Mbilabile &lt; Ndeshi </em>&lt; YKM5 &lt; PSA. Furthermore, ashes and mineral contents decreased with ripening stages whereas the low viscosity banana juice was rich in potassium and magnesium. Finally, the study recommends stage 5 of the ripeness as ideal for producing low viscosity banana juice.</p> <p><strong>Keywords</strong>: Mechanical extraction, Banana cultivar, Ripening stage, Tannin, Banana juice</p> Mathayo G Mathias, Lilian D Kaale , Oscar Kibazohi Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217555 Wed, 01 Dec 2021 00:00:00 +0000 Heavy Metal Contamination and Potential Ecological Risks in Surface Sediments along Dar es Salaam Harbour Channel https://www.ajol.info/index.php/tjs/article/view/217556 <p>Investigation of heavy metal contamination along Dar es Salaam harbour channel was carried out in order to determine their current concentrations, sources and potential ecological risks to benthic biota. Sampling was carried out from January to May 2019 and samples analysed using ICP-OES and C-H-N-S analyser. Analysis of heavy metal relationships showed that, Cu, Zn, Cr, As, Ni, Co, Fe, Cd had strong relationships with each other, while Pb only related to Zn. Principal component analysis partitioned metals into two groups; PC1: Ni, Cr, Fe, Co, As, Cu, Cd, and Zn explaining 73.6% variance and PC2: Pb, Zn, and Cd with 13.7% variance. Similarly, Cd, Pb and Zn had severe to very high enrichments (Cd &gt; Pb &gt; Zn) showing serious anthropogenic contamination of these metals in sediments along Dar es Salaam harbour channel. Degree of contamination and potential ecological risks varied from low, moderate, to high; indicating that sediments were considerably contaminated with heavy metals. Levels of contamination varied in space and according to the type of heavy metal Higher contamination and ecological risks were revealed at the harbour area probably due to the observed high concentrations of Cd, Pb and Zn. Monitoring of metals should be emphasized in order to control contaminants release into this area from their sources.</p> <p><strong>Keywords</strong>: Dar es Salaam harbour channel, Heavy metals, Contamination, Sediments, Degree of contamination, Ecological risks</p> Benard Mwakisunga, Harishchandra B Pratap, John F Machiwa, Flora Stephano Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217556 Wed, 01 Dec 2021 00:00:00 +0000 Analysis of the Current and Future Land Use/Land Cover Changes in Peri-Urban Areas of Dar es Salaam City, Tanzania using Remote Sensing and GIS Techniques https://www.ajol.info/index.php/tjs/article/view/217580 <p>A rapid increase in population and urban development has direct impacts on the natural environment of peri-urban areas of big cities, especially in the developing countries. This study examined land use and land cover changes (LULCC) of peri-urban areas of Kinondoni Municipality in Dar es Salaam city for the period between 1999 and 2019 and predicted future changes by 2039. The specific objectives were to; (i) map the spatial-temporal land use and cover changes (ii) analyze settlements (built-up areas) patterns and factors influencing their changes (iii) predict changes that might happen for the next two decades. LULCC for 1999 to 2019 were detected through Maximum Likelihood (ML) supervised classification techniques while Cellular Automata based on Artificial Neural Network (CA-ANN) model was used to predict future changes. Over the past two decades, 33.7% of vegetation has been lost due to increased settlements, as shown by linear development pattern of built-up areas, which has gained about 30% of other land covers. This study predicts that by 2039, built-up areas will increase drastically to occupy 51.6%, while vegetation and water cover will decrease to occupy 40.4% and 1.4%, respectively. Without good planning strategies and land use policies, the control and management of the magnitude and patterns of peri-urban growth and sustainable management of natural and built environments in Tanzania will remain a challenge. This paper seeks to contribute to the body of knowledge required for evidence-based policy formulation and decision making to attain sustainable urbanization through setting suitable management plans for peri-urban areas of Tanzanian cities.</p> <p><strong>Keywords</strong><strong>: </strong>Artificial Neural Network, Land use/cover changes, Maximum likelihood, Peri-urban, Remote sensing</p> Erick T Mnyali, Silvia F Materu Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217580 Wed, 01 Dec 2021 00:00:00 +0000 Effects of Ripeness and Blending Speed on the Extraction Yield and Physical Chemical Properties of Low Viscosity Banana Juice https://www.ajol.info/index.php/tjs/article/view/217582 <p>Low viscosity banana juice can be extracted from banana by blending and pressing the resulted semi-solid pulp to separate the juice. This juice extraction technology is relatively new and further studies to understand key parameters for juice release is vital for scaling up production and commercialisation. This study, investigated the influence of blending speed and ripeness stage on banana juice yield using two banana cultivars; the East African highland banana (<em>Mbile</em>) and the exotic banana (Pisang awak). Types of sugars and organic acids in the juice were analysed using an HPLC. Changes with ripening of fruit firmness, juice pH and soluble solids were also examined. The juice yield increased significantly (<em>p</em> &lt; 0.05) with increasing blending speed and ripeness stage for all cultivars. The <em>Mbile</em> cultivar from Kagera had the highest juice yield of 82.35%, followed by <em>Mbile</em> cultivar from Kilimanjaro with 75.30% and Pisang awak cultivar with juice yield of 62.50%. The highest juice yield for all cultivars was achieved at 3500 rpm blending speed and ripeness stage 5. Fructose and glucose sugars increased significantly (<em>p</em> &lt; 0.05) with ripeness, while sucrose showed insignificant changes. Malic and citric acids were observed to increase significantly (<em>p</em> &lt; 0.05) during ripening in all banana cultivars.</p> <p><strong>Keywords: </strong>East African highland banana, Banana juice extraction, Blending speed, Low viscosity banana juice.</p> Oscar Kibazohi, Victor V Matabura Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217582 Wed, 01 Dec 2021 00:00:00 +0000 Atmospheric Instability Conditions during Rainy Seasons over Tanzania https://www.ajol.info/index.php/tjs/article/view/217583 <p>The amount of rainfall and its distribution in time and space is dependent on the atmospheric instability conditions, and on its moisture content. The aim of this study was to determine the atmospheric instability conditions during January to March (JFM), February to April (FMA), March to May (MAM), and October to December (OND) rainy seasons over local climate zones in Tanzania. Zone area average seasonal Convective Available Potential Energy (CAPE), Convective Inhibition (CIN), Precipitable Water (PW) and Lifted index (Li) were calculated and analyzed. Results showed Li &lt; 0 in JFM and FMA over whole Tanzania. During MAM and OND, Li &lt; 0 over the Lake Zone, Western Highlands Zone and Central Zone only. CAPE ranged from 793 J/kg to 1183 J/kg during JFM, and 700 J/kg to 1080 J/kg during FMA. During MAM, CAPE ranged from 170 J/kg to 921 J/kg and from 173 J/kg to 833 J/kg during OND. Results also showed CAPE &gt; 1000 J/kg over the Lake Zone, Western Highlands Zone, Island Zone, and Central Zone. These results show that the atmosphere was moderately unstable during the JFM and FMA and was weakly unstable during the MAM and OND. Therefore, the atmosphere is likely to be more convective during JFM and FMA seasons.</p> <p><strong>Keywords</strong>: Lifted index, Convective inhibition, Precipitable water, Convective available potential energy, Atmospheric instability.</p> Pasvolo J Mwinuka, Christian BS Uiso, Ladslaus B Chang’a, Mwingereza J Kumwenda Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217583 Wed, 01 Dec 2021 00:00:00 +0000 Analogue Sandbox Scaled Modelling of Oblique and Orthogonal Extension Rifting in Rukwa Rift Basin, Tanzania https://www.ajol.info/index.php/tjs/article/view/217584 <p>Fault evolution in oblique and orthogonal rift systems in the brittle upper crust of the Rukwa rift basin was simulated using scaled sandbox modelling by varying the angle between the rift axis and the extension direction, α, through 45° and 90°, over a 10 cm displacement. The 45° oblique model exhibits a half-graben architecture bounded by a planar fault, intra-rift faults and a conjugate fault in some vertical sections. The map view of the model’s basin trends in the NW-SE direction, and is comparable with the Rukwa rift basin orientation. The 90° oblique model forms a basin structure which is orthogonal to the extension direction of the model in aerial photos. Its linear fault remains orthogonal to the extension direction, while the flexural side of the model segments into sinuous normal faults. Planar to slightly curved intra-rift faults are observed in vertical sections. The half-grabens have similar geometries in vertical sections for both models, while intra-rift faults elongate in vertical sections. The results of the oblique model are similar to natural examples of rift fault systems like the Rukwa rift. The fault geometries of the sandbox models can serve as examples for recognizing fault styles in oblique rift systems.</p> <p><strong>Keywords</strong>: Analogue Sandbox modelling, Oblique rifting, Orthogonal rifting, Tanganyika-Rukwa-Malawi Rift Segment, Rukwa Rift Basin</p> Tonny Ojok, John BK Duot, Majorine Namaganda, Nasra Sadiki , Michael Msabi Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217584 Wed, 01 Dec 2021 00:00:00 +0000 Placental Insulin-Like Growth Factor-1 Receptor, Protein Kinase B and Mammalian Target of Rapamycin are Downregulated in HIV-1 Positive Women on Antiretroviral Drugs https://www.ajol.info/index.php/tjs/article/view/217585 <p>HIV-1 and ARV drugs uptake during pregnancy may change placental phenotype during pregnancy affecting fetal growth. We investigated the influence of maternal HIV-1 and ARV drugs on expression of placental genes important for fetus growth. A total 51 HIV-1 positives and 46 HIV-1 negative pregnant women were studied. Placental gene expression changes of insulin-like growth factor receptor 1 (IGF-1) R, mammalian target of rapamycin (mTOR), protein kinase B (AKT-1), sodium-coupled neutral amino acid transporters (Slc38a1, Slca38a2, Slc38a4), inhibin A, adrenomedullin and 11<em> beta-</em>Hydroxysteroid dehydrogenase type (HSD)<em>-2</em> were assessed by RT-qPCR. There was a significant decrease in mRNA expression of placental IGF-1R, mTOR, and AKT-1 in HIV-1 positive placentas compared to controls (p &lt; 0.0001). There was also significant upregulation of an antiangiogenic molecule, inhibin A and downregulation of angiogenic molecule adrenomedullin in HIV-1 positive placenta (all p &lt; 0.0001). However, the mRNA expression of placental Slc38a1 and Slca38a2 was higher in both HIV-1 positive and negative women delivering LBW babies compared to controls (p &lt; 0.0001). The placental mRNA expression of 11<em> β-</em>HSD<em>-2 </em>increased by 17 folds in HIV-1 negative and by 3.8 folds in HIV-1 positive women delivering LBW babies. IGF-1-P13-AKT-1-mTOR signaling pathway is dysregulated in placenta of HIV-1 positive women on ARV drugs. Higher mRNA expression levels of inhibin A and lower levels of adrenomedullin occur in placenta of HIV-1 positive women delivering LBW babies. ARV drugs and HIV-1 may be involved in the disruption of vascular tone of the placenta and therefore placental perfusion.</p> <p><strong>Keywords: </strong>Pregnant women, HIV-1, ARV drugs, Placental IGF-1-AKT-1-mTOR signaling, inhibin A, adrenomedullin, amino acid transporters.</p> Winifrida B Kidima , Gatambwa D Mukandala, Osiana Leonard, Daniel Nkungu Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217585 Wed, 01 Dec 2021 00:00:00 +0000 Critical Analysis of Material Consumption and Cost Reduction Techniques for the Apparel Cutting Processes https://www.ajol.info/index.php/tjs/article/view/217586 <p>Revenues generation in the garment industry is synonymous with material consumption. This study thus analysed material consumption and cost reduction techniques in the Tanzanian garment industry. The research employed quantitative (experimentation) and qualitative approaches (document review and observation technique) in the apparel cutting processes. Experimental results of material consumption from ten tests averaged efficiency of 78.67%, the wasted pieces (19.2%), and unnoticed waste (2.03%). Essential considerations to reduce material waste include: digitalising the fabric cutting processes; providing workers training; deploying appropriate practices in the cutting room (e.g. pattern engineering and pattern accuracy); considering the quality of the procured fabric and fabric efficiencies relative to different human body shapes and proportions; and considering the separation process rather than extending facings, splitting substantial components, slight reductions in a flare, and seam displacements. The study implies that apparel enterprises can benchmark their actual material consumption circa 50-70% of their total garment manufacturing costs.</p> <p><strong>Keywords: </strong>Material waste, Garment industry, Fabric losses, Cost reduction techniques, Small and medium-sized enterprises.</p> Ismail WR Taifa, Ibrahim Twaha , Mboka A Mwakibambo Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217586 Wed, 01 Dec 2021 00:00:00 +0000 Design and Performance Analysis of Composite Airfoil Wind Turbine Blade https://www.ajol.info/index.php/tjs/article/view/217587 <p><strong>Abstract</strong></p> <p>Small horizontal axis wind turbine rotors with composite airfoil rotor blades were designed and investigated in the present study in order to improve its performance in low wind speed and low Reynolds number (Re) conditions for standalone system. The geometrical and aerodynamic nature of a single airfoil small horizontal axis wind turbine blade curtails efficient energy harnessing of the rotor blade. The use of composite airfoil rotor blade improves energy production but imposes uncertainty in determining an optimal design angle of attack and the off design aerodynamic behaviour of the rotor. This research investigated the effects of two airfoils used at different sections in a composite blade and determined the blade’s optimal design angle of attack for maximum power generation. The wind turbine rotor blades were designed using blade element momentum (BEM) method and modelled by SolidWorks software. The SG6042 and SG6043 airfoils were used for the composite airfoil blades. Five wind turbines were designed with rotor blades of design angles of attack from 3° to 7°. The five wind turbine blades were simulated in computational fluid dynamics to determine the optimal design angle of attack. The composite airfoil wind turbine blade showed improved performance, whereas, the wind power generated ranged from 4966 W to 5258 W and rotor power coefficients ranged from 0.443 to 0.457. The blade with design angle of attack of 6° showed highest performance.</p> <p><strong>Keywords</strong>: composite airfoil, lift-to-drag ratio, pressure coefficient, Reynolds number, design angle of attack.</p> Hegespo H Mwanyika, Yusufu AC Jande, Thomas Kivevele Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217587 Wed, 01 Dec 2021 00:00:00 +0000 Optimal Design of Hybrid Renewable Energy for Tanzania Rural Communities https://www.ajol.info/index.php/tjs/article/view/217588 <p><strong>Abstract</strong></p> <p>Rural communities in developing countries lack access to electricity due to high costs of grid extension. This paper proposes a hybrid system of renewable energy (HRES) as solution. The HRES consists of solar, wind, and battery energy storage (BES). The village called Ngw’amkanga in Shinyanga region of Tanzania, East Africa is selected as a case study. An iterative method to determine the size of wind and solar photovoltaic (PV) generation required assuming a project life of 25 years at minimum annualised cost of the system ( ) is proposed. The project life time is fixed on the life span of the main component, solar PV at 25 years. The iteration is undertaken to meet the energy demand ensuring the BES is charged throughout the year. The required BES has three days of autonomy, and a maximum battery depth of discharge 50%. At minimum ACS, the HRES comprises only solar PV and BES, due to insufficient wind at this site. The levelised cost of energy ( ) of the HRES is 27.18 p/kWh, paid by the users. This is cheaper than the grid connected small power producers of Tanzania as discussed in the paper.</p> <p><strong>Keywords</strong>: Renewable energy; wind energy generation; solar photovoltaic; annualised cost of the system; levelised cost of energy</p> Ester T Marcel, Joseph Mutale, Aviti T Mushi Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217588 Wed, 01 Dec 2021 00:00:00 +0000 Application of Faulkenberry (2018) Bayes Factor to a Balanced Two Way Analysis of Variance with Random Effects https://www.ajol.info/index.php/tjs/article/view/217589 <p>The Analysis of Variance technique estimates variance components by comparing their mean squares to their expected values. Nevertheless, this method could give variance component estimates that are found outside the parameter space, i.e. negative estimates. In a bid to overcome this deficiency, alternate approaches are essential, and likelihood-based approaches have become common over time. Bayesian techniques have also been proposed and Bayes factors developed for examining various models. We applied the Bayes factor proposed by Faulkenberry (2018) to a Balanced Two Way ANOVA under three (3) cases, namely <strong>Case 1</strong>: the levels of the two factors are fixed; <strong>Case 2</strong>: the levels of the two factors are random; and <strong>Case 3</strong>: the levels of one factor are considered as fixed, while the levels of the other factor are considered as random. We realized that when the levels of the two factors are fixed, the Bayesian conclusion about the variability in the effects is in line with that of a frequentist. But when the same data set was considered to be wholly or partly as sample observations drawn randomly from a given population of interest, the Bayesian conclusion differed slightly from that of the frequentist.</p> <p><strong>Keywords: </strong>Bayes Factor; Bayesian; Frequentist, Fixed; Random.</p> Onyeike D Egburonu, Omotayo A Abidoye Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217589 Wed, 01 Dec 2021 00:00:00 +0000 Smart Electric Meter Deployment in Tanzania: A Survey https://www.ajol.info/index.php/tjs/article/view/217982 <p>Using information and communication technologies (ICT) to make the electrical power network intelligent and smarter (smart grid) has been the focal point in transforming electrical power industry. The idea behind smart grid is to transform the Tanzanian power sector into a secure, adaptive, sustainable, and digitally enabled ecosystem that provides reliable and quality energy for all with active participation of stakeholders. Smart metering is a central segment in realizing smart grid. However, a big question is whether Tanzanian power stakeholders are ready for smart metering technology investments for household applications. Operation and maintenance of a smart metering solution is a relatively new business in Tanzania and requires investment in resources and capacity building. A case study was conducted at the utility company in Dar es Salaam offices, to investigate the deployment status and services offered. Fixed tariff rates, high cost, low rates on returns of investment and non-customization of the features, were some of the shortcomings identified by the study in terms of non-deployment in residential homes. Further, the authors, propose development of standardization document for smart metering technologies and the adoption of software based smart meter for residential applications using Internet of Things platform. Its low cost of development and ease installation would be ideal for residential applications.</p> <p><strong>Keywords</strong>:&nbsp; Smart grid, Utility Company, Smart meter, Advanced Metering Infrastructure, Deployment Status.</p> Theresia B Maziku, Kwame S Ibwe, Abdi Abdalla , Ellen A Kalinga Copyright (c) 2021 https://www.ajol.info/index.php/tjs/article/view/217982 Wed, 01 Dec 2021 00:00:00 +0000