Authors:Mussa B. Mbegeze, Joan J.E. Munissi, Flora Stephano, Ramadhani S.O. Nondo, Stephen S. Nyandoro Pages: 776 - 787 Abstract: Besides changes in life styles and improper dietary patterns, the rapidly increasing burden of diabetes mellitus type 2 is correlated with antidiabetic agents currently in clinical use, which are costly, less effective, and present undesirable side effects. Natural products from plants are promising alternative sources for developing more effective and cost friendly antidiabetic agents. This study therefore investigated the antidiabetic potential of Vitex mombassae fruits extract (VMFE) in streptozocin-nicotinamide induced diabetic Wistar rat model. Oral acute toxicity test was conducted in male Wistar rat using up and down method by following OECD Guideline 423 (2002). No clinical signs of toxicity were observed at 300 and 2000 mg/kg body weight (b.w.) doses used in the assays. The LD50 value was estimated to be ˃ 2000 mg/kg b.w. In evaluation of antidiabetic activity, diabetic Wistar rats were administered with 100, 200 and 300 mg/kg b.w. of VMFE. VMFE resulting into significant lowering of the levels of fasting blood glucose (p < 0.05) and increased of level of high-density lipoprotein-cholesterol (HDL-C), levels of total cholesterol (TC), triglyceride (TG) and low-density lipoprotein-cholesterol (LDL-C) were reduced significantly (p < 0.05). Therefore, this study provides scientific evidence for antidiabetic activities of V. mombassae fruits extracts, and validates its traditional use in the management of diabetes mellitus type 2. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.1 Issue No:Vol. 49, No. 4 (2023)
Authors:Ndatiye W. Ndatiye, Lupituko L. Mkayula , Grace A. Kinunda Pages: 788 - 808 Abstract: This study aimed at developing activated carbons from Borassus aethiopum shells (BaS), hulls (BaH), kernels (BaK) and fruits (BaF) for removing phenol (Ph) and 2-chlorophenol (2-CP) from aqueous solution. The preparation of the activated carbons involved carbonization of the starting materials at 500 ºC followed by chemical activation at 600 ºC using 0.5 M H3PO4 acid. The prepared activated carbons were found to be mesoporous having pore sizes and surface areas in the range of 3.2 to 3.5 nm and 644 to 740 m2/g, respectively. Thermogravimetric analysis (TGA) thermograms showed that the prepared activated carbons can be applied in the batch solution with a temperature not greater than 500 ºC as above this temperature, the materials decompose. Adsorption experiments showed that the uptake of 100 mg/L of Ph and 2-CP from water is favourable using an adsorbent dose of 0.5 g and a contact time of 6 hours. On the other hand, the batch solution of pH 8 and 6 favoured the adsorption of Ph and 2-CP, respectively. Moreover, the adsorption of the aforementioned adsorbates strongly depended on their initial concentrations and temperature of the batch solution. Equilibrium adsorption isotherms fitted into both Langmuir and Freundlich isotherms, but the Freundlich adsorption model was found to have the highest regression value, hence the best fit. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.2 Issue No:Vol. 49, No. 4 (2023)
Authors:Haji F. Haji, Margaret E. Samiji, Nuru R. Mlyuka Pages: 809 - 818 Abstract: DC magnetron sputtering at a substrate temperature of 425 °C was used to successfully deposit W/Zn-doped VO2 thin films on soda lime glass (SLG) substrates. The aim was to investigate the influence of Zn doping levels on the transition temperature ( ), luminous transmittance (Tlum) and solar transmittance modulation (ΔTsol) of VO2-based thin films. UV/VIS/NIR spectrometer, X-ray Diffraction (XRD), Atomic Force Microscope (AFM), and Rutherford Backscattering Spectroscopy (RBS) were used to characterise the thin films. It was revealed that W/Zn co-doped VO2 thin films with ~ 10.8 at.% Zn showed a luminous transmittance of ~ 40.4%, with excellent solar transmittance modulation of 10.2%. Furthermore, the transition temperature obtained for the Zn and W co-doped VO2 films with ~ 10.8 at.% Zn was lower at 23.1 °C compared to 25.6 °C and 26.8 °C for thin films with ~ 3.9 at.% Zn and ~ 2.8 at.% Zn, respectively. It was not possible to deposit the films with Zn doping level above 10.8 at.% due to some technical limitations. These findings indicate that thin films with a controlled proportion of Zn in the W/Zn co-doped VO2-based thin films have the potential to be employed for applications such as smart windows. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.3 Issue No:Vol. 49, No. 4 (2023)
Authors:Juma Sija, Mohamed Mazunga Pages: 819 - 830 Abstract: This study aimed at determining the concentrations of rare earth elements (REEs) in coal and coal fly ash (CFA) from three coal mines in Tanzania: Kiwira, Ngaka and Rukwa. The goal was to assess if these resources could be commercially viable for extracting REEs. Coal and CFA samples were analysed using X-ray fluorescence (XRF) spectrometry and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The total concentrations of REEs in the coal samples ranged from 89.48 parts per million (ppm) to 196.30 ppm, while in CFA samples, ranged from 362.55 ppm to 475.77 ppm. Computed percentage of critical REEs (REYdef, rel%) and outlook coefficient (Coutl) values ranged from 27.41% to 50.74% and 0.62 to 2.00, respectively. Based on the evaluation criteria proposed for assessing coal and coal ash as sources of REEs, the results suggest that the studied coal and CFA samples have the potential to be used as sources of REEs for economic development. These findings have important implications for the Tanzanian government and other relevant authorities, as they provide valuable insights into the feasibility of investing in the coal and coal ash as promising sources of REEs. This is particularly significant considering the high global demands for REEs. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.4 Issue No:Vol. 49, No. 4 (2023)
Authors:Geradius Deogratias, Grace A. Kinunda Pages: 831 - 841 Abstract: Anchoring groups are crucial for enhancing the performance of dye-sensitized solar cells (DSSCs). For instance, cyanoacrylic acid serves as the primary anchoring group in DSSC due to its crucial elements required for effective electron transport. However, it suffers from degradation. To address this limitation, this study proposes alternative cyano-based anchoring groups for sensitizers. Density functional theory (DFT) and time-dependent DFT were used to investigate the optical and electronic properties of the dyes. The studied dyes (excluding the dye containing OH group) displayed three absorption bands within the visible and NIR regions. Low-energy peaks ranged from 498 to 576 nm, corresponding to excitation from ground state to first excited state. Moderate intensity bands appeared at 376 to 418 nm, with the highest energy bands falling within 351 to 384 nm. Ground state oxidation potential values for the dyes were lower than the redox potential of the iodide/triiodide pair. Similarly, excited state oxidation potential values were higher than or equal to the conduction band of TiO2, except for NO2 and CHO containing dyes. Ionization potential values ranged from 6.24 eV to 6.40 eV, while electron affinity values were within 1.21 eV to 2.74 eV. Chemical potential values ranged from 3.75 to 4.57 eV, and chemical hardness of the dyes fell between 1.83 to 2.54 eV. The proposed cyano-based anchoring groups show promising potential for enhancing DSSC performance. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.5 Issue No:Vol. 49, No. 4 (2023)
Authors:Sai Ngassa, Cyprian Mpinda, Kessy F. Kilulya, Rose Masalu Pages: 842 - 858 Abstract: This study investigated the scientific landscape of research on phthalate esters biodegradation using the Web of Science database up to 2022. The collected data were analysed using bibliometric and scientometric tools. A total of 863 scholarly documents published between 1975 and 2022 in 266 journals were selected for analysis. The analysis revealed a growth rate of 6.9% in the research field, with an average document age of 10.8 years. The trend in phthalate biodegradation research showed a steady increase in citations until 1997, followed by a slight decrease until 2005, but experienced renewed interest in 2006 and significant growth in 2016. Chemosphere was identified as the prominent journal, and China had the most publications (417) followed by India (78), while Africa had the least productivity, with South Africa contributing the highest number of publications (9). Thematic evolution in the field focused on understanding the mechanisms of phthalate breakdown through microbial enzymes like hydrolases, while revealing changing patterns with the current research focus being "microbial community" and "metabolism" as indicated by strongest burstiness strengths. The study sheds light on the scientific landscape of phthalate biodegradation research, highlighting research gaps and suggesting potential research policy improvements such as enhancing funding and capacity building in biodegradation research in Africa. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.6 Issue No:Vol. 49, No. 4 (2023)
Authors:Joseph M. Christopher, Wilirk Ngalason, John V. Lyakurwa Pages: 859 - 870 Abstract: Information on habitat characteristics for endemic and threatened amphibians along the altitudinal gradient in the Uluguru Nature Forest Reserve (UNFR) is limited. We assessed habitat characteristics associated with the occurrence of endemic and threatened amphibians in the Uluguru Nature Forest Reserve between April and June 2022. Bucket pitfall traps, time-constrained audio-visual surveys, plots and opportunistic searching were used to study amphibians in 6 sites along elevational gradient from 600 m to 2100 m a.s.l. Eighteen amphibian species were recorded, thirteen of them being endemic to the Eastern Arc Mountains, two near-endemic and three widely distributed. Among the species recorded, seven are categorized as threatened as per IUCN Red List. We observed more endemic and threatened amphibians in the submontane forests (1200–1800 m) than in other sites. Negative correlations existed between temperature, canopy cover, leaf litter cover and leaf litter depth and species richness, whereas positive correlations existed between humidity and species richness. No single factor was responsible for the occurrence of endemic and threatened amphibians in the Uluguru Nature Forest Reserve. This is only a snapshot survey on the occurrence of threatened and endemic amphibians and their associated habitat features in the northern part of the Uluguru Nature Forest Reserve. A long-term monitoring of these amphibian species is recommended especially at this era of unprecedented forest loss and degradation. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.7 Issue No:Vol. 49, No. 4 (2023)
Authors:Fadhili S. Estomini, Stephen I. Nnungu, Amelia S. Buriyo Pages: 871 - 879 Abstract: Cissus oliveri (Engl.) Gilg ex Engl. is among the plant species of the family Vitaceae widely used in traditional medicine for management of different ailments. This study aimed at assessing the phytochemicals of C. oliveri parts in order to provide scientific validation for its use as a therapeutic agent. Qualitative analysis of water and ethanolic extracts was conducted by using standard methods and the results revealed that all the parts possess alkaloids, flavonoids, phenols and tannins. Similarly, glycosides and saponins were only present in leaf and root. Quantitative analysis performed by gravimetric and spectrophotometric methods showed that all parts contain alkaloids, phenol, and tannins in large quantities. The largest amount was found in leaf for alkaloids (6.47 ± 0.41 mg/g DW) and phenols (4.85 ± 0.90 mg/g DW) compared to stem and root. Alkaloid content was higher in root than in stem (P < 0.01), whereas phenol content was the same in root and stem (p > 0.05). Further, there was no significant difference in tannins content among all the plant parts assessed. The presence and quantities of active phytochemicals in C. oliveri call for further investigations on the bioactivities of the extracts and isolated chemical constituents for potential pharmacological applications. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.8 Issue No:Vol. 49, No. 4 (2023)
Authors:Gregory A. Mtega, Cuthbert L. Nahonyo, Steven Temu, George Sangu, John Bukombe Pages: 880 - 890 Abstract: Ngorongoro Conservation Area (NCA) is renowned worldwide for its multiple land use where pastoralism and wildlife conservation co-exist. Thus, the NCA must meet a delicate balance of competing needs between livestock and wildlife. Currently the NCA is conducting resettlement program to facilitate pastoralists who are willing to move and resettle outside of the conservation area in order to reduce the number of people and livestocks in NCA. The common eland (Tragelaphus oryx) are among the large herbivore species found in the NCA that might be affected by possible competition between livestock and wildlife. The information on this species including habitat utilization and feeding ecology is limited. This study therefore, investigated the factors influencing habitat use and diet composition of the common eland (Tragelaphus oryx) in NCA. Data were collected along 82 pre-established transects using direct field survey. The study therefore assessed habitat use, distribution patterns, diet composition and conservation threats facing the common eland in NCA, The results indicated that the grassland habitat was mainly used by elands (> 85% in both dry and wet seasons), while other habitats were least used (< 15%). Eland diet composition varied significantly among plant species, with the animals most frequently feeding on Themeda triandra but rarely on Vachellia tortilis and Hibiscus aponeurus. The study concludes with recommendations for enhancement of grassland habitat management and reduced anthropogenic activities to enhance eland conservation in NCA. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.9 Issue No:Vol. 49, No. 4 (2023)
Authors:Godfrey L. Chasama, Fred D. Chibwana, Aloyce S. Hepelwa, Jestina V. Katandukila Pages: 891 - 900 Abstract: Increasing competition for feed resources and greenhouse gases pollution have been compelling beef production systems to operate at higher feed utilization. These challenges imply the need to breed cattle for Residual Feed Intake (RFI) to lower feeding costs and enteric methane production per output. To explore relevant indicator traits of RFI, this study investigated the association of RFI to Tanganyika Shorthorn Zebu (TSZ) cattle metrics from the Misungwi and Maswa Districts of Tanzania, where Tarime and Sukuma ecotypes are common. A correlation study involving the fattening of twenty-eight TSZ bulls was conducted at Tanzania Livestock Research Institute -Mabuki. From the animals' body weight and feeding data, regression of daily feed intake on average daily gain and metabolic body weight was analyzed to estimate the animals' RFI. Subsequently, the correlation of RFI to metrics of belly, horn, hip, dewlap and body length was investigated. Residual Feed Intake and Belly Length (BeL) were highly positively correlated, while RFI and Dewlap Depth (DD) were moderately positively correlated. The results indicated prospects for using BeL and DD as indicator traits for RFI. Extensive studies are recommended to analyze the correlation of RFI to hump depth, ear length, muzzle circumference and kidney fat. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.10 Issue No:Vol. 49, No. 4 (2023)
Authors:Peter V. Fayyu, Joan J.E. Munissi, Stephen S. Nyandoro, Flora Stephano Pages: 901 - 910 Abstract: The reported investigations were aimed at establishing anticancer potential of the leaf extracts from Croton dictyophlebodes (CDE), C. kilwae (CKE) and C. longipedicellatus ssp austrotanzanicus (CLE). In vitro cytotoxicity assays of the extracts were performed against human laryngeal cancer cell line (HEp-2) and human breast cancer cell line (MCF-7), while in vivo toxicological studies were done using Swiss albino mice (Mus musculus) following the Organization for Economic Cooperation and Development guideline number 423 of 2001. Results for in vitro assays revealed that CDE and CLE induced cytotoxicity to MCF-7 and HEp-2 cell lines at EC50 values of 86 and 63 µg/mL, respectively, while CKE was inactive to HEp-2 cells at 100 µg/mL. For in vivo studies, mice were given calculated doses based on globally harmonized standards and monitored for 14 days to observe signs of toxicity. Haematological analysis was also carried out to obtain information on changes in blood conditions. The findings showed that LD50 for CKE and CDE were > 2000 mg/kg, while for CLE was 175 mg/kg body weight (b.w.). The oral administration of CDE and CKE did not reveal significant changes in haematological parameters of treated mice, while CLE provoked some. Thus, the studied extracts may be considered potential cancer remedies with safety pre-cautions that warrant further investigations. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.11 Issue No:Vol. 49, No. 4 (2023)
Authors:Imani Kapungu, Emmanuel Evarest, Nyimvua Shaban , Andongwisye J. Mwakisisile Pages: 911 - 920 Abstract: The expenses of medical services are increasing across the globe. As a result, pressure is placed on government and insurance companies’ budgets. The amounts of money collected are not enough to cover the claim payments. Therefore, it threatens the sustainability of the health insurance companies due to the mismatch of income and expenditures. This study aimed to model and forecast claim payments for the national health insurance fund (NHIF) in Tanzania. The claim payment data for the period of 2001–2021 from NHIF were used in building the ARIMA model. It was proven that ARIMA (0, 2, 2) is the most accurate model for forecasting the claim payments from 2022 to 2031. Furthermore, numerical results show that the claim payments for NHIF will grow by 68% by 2031. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.12 Issue No:Vol. 49, No. 4 (2023)
Authors:Idrissa S. Amour, Fatuma Simba, Septimi Kitta, Abdi T. Abdalla Pages: 921 - 929 Abstract: Management of large classes’ tutorials is a known problem in Mathematics. Engineering mathematics classes enrol around 1000 students at the University of Dar es Salaam. For effective learning, each tutorial session should register not more than 40 students. This requires at least 25 sessions of tutorials per week, which may not be feasible due to both scarce human resources and venues. In this work, we developed online Mathematics exercises based on the System for Teaching and Assessment using Computer Algebra Kernel (STACK). About 300 STACK questions in linear algebra, calculus, complex numbers, and numerical analysis were constructed for weekly tutorials and quizzes. Students were given an unlimited number of attempts in tutorials and only one attempt for quizzes. The quality of the questions was analysed by examining their facility indices and discriminative efficiencies. Majority of the questions (87%) were within acceptable region. The questions, therefore, provided reasonable insight as appropriate alternative to classical practice. Competent authoring of STACK questions can improve the quality of teaching and learning of Mathematics and save scarce human and material resources required to serve large classes. This can also address the issue of running online programmes in Mathematics and computational subjects to support distance learning. PubDate: 2023-10-27 DOI: 10.4314/tjs.v49i4.13 Issue No:Vol. 49, No. 4 (2023)
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