Tanzania Journal of Science

Effect of Substrate Temperature and Deposition Power on the Surface Morphology and Optical Properties of ZnO:Mg Thin Films Deposited by DC Magnetron Sputtering

Saidi Saidi, Margaret E Samiji, Nuru R Mlyuka — Wed, 31 Jan 2024 00:00:00 +0000

Magnesium doped zinc oxide (ZnO:Mg) thin films were deposited on soda lime glass slides by DC magnetron sputtering method. Atomic force microscope (AFM), and UV/VIS spectrophotometer were used to investigate the effect of sputtering power and substrate temperature on the surface morphology and optical properties of ZnO:Mg thin films. AFM images revealed that sputtering power and deposition temperature have significant influence on surface morphology of the ZnO:Mg thin films. For all sputtering powers and substrate temperatures investigated, ZnO:Mg films had peak transmittance above 85%. Samples deposited at 110 W sputtering power and 450 ^°C substrate temperature showed the best peak transmittance of > 90% at 560 nm (visible range). Optical band gap of ZnO:Mg films was in the range of 3.44– 3.69 eV depending on the substrate temperature. The results indicated the potential of the films for transparent conductor applications.

Modelling spatial distributions of sediments fingerprinting in the Ruvu Basin of Tanzania without continuous sediment monitoring

Charles H. Kasanzu — Wed, 31 Jan 2024 00:00:00 +0000

This study investigates various hinterlands’ contribution of sediments into the sub-basin known as Ruvu that comprises Mindu, Kibungo, Mvuha and Mindu catchments of Morogoro, Eastern Tanzania. An integrated geochemical and isotopic data were used to constrain this. Strategic sampling of basement and silty-sized sediments was conducted and the data were modelled using mass-balance computations. This approach revealed that, more than 70% of suspended sediments in the Mgeta River originate from Kigalamila, Sezima, Kingule, Mafumbo and Kibuko areas. Thus, hills north of Kisaki are major contributors of sediments with less contribution from the southern terrain. After modelling of the data from Mvuha sub-catchment, results suggest that the sediments (~50%) originate from Msuluzi area and significant erosion comes from Vihengele region. Evidence for Vihengele is also due to elevated CaCO₃ abundances in the Mvuha samples from the calcareous rocks. Sediments in the Mindu sub-catchment largely originate from Msaga and Monde areas that are dominated by granulites and gneisses based on simulated mixing calculations. Thus, the extreme southern part of the sub-catchment is more prone to erosion. Sediments of more than 47% for the Kibungo sub-catchment originate from the Mfizigo area. However, no significant erosive activities in the catchment were noted.

Turmeric Dyeing of Cotton Fabrics using Tie-Dyeing Techniques

Pendo Bigambo, Happiness Wellah, Hadija Ngaga, Safina Kimbokota, Mbonea Mrango — Wed, 31 Jan 2024 00:00:00 +0000

Tie-dyeing is a resist-dyeing technique which for years has been used by SMEs to produce attractive textile fabrics. However, the technique is challenged by the use of synthetic dyes which are not environmentally friendly and the growing consumers’ environmental awareness. Accordingly, researchers and industrialists are forced to explore the alternative natural dyes in response to the above challenges. Among the natural source of dyes available abundantly in Tanzania, but are yet to be fully exploited for applications via tie-dyeing technique are turmeric (Curcuma longa L.) roots commonly used for food coloring.

In this study turmeric roots were investigated for their potential as dyes for coloration of cotton fabrics through tie-dyeing technique. Turmeric dyes were extracted through boiling of powdered turmeric roots in water followed by filtering the mixture, and applying it to a pre-mordanted and tied fabric. For analysis purposes, un-tied (plain) cotton fabric was also dyed following the same procedure. The findings of this study suggests that, turmeric dyes can be applied on cotton using tie-dyeing technique and produce golden-yellow color on fabrics. Additionally, pre-mordanting of cotton increased the color depth of dyed materials while improving their fastness properties with respect to washing and both wet and dry rubbing.

Application of Remote Sensing and Spectroradiometry in Geological Mapping: a case study of Handeni (QDS 148) Block, Eastern Mozambique Belt, Tanzania

Masota M Magigita, Elisante Mshiu, Cassy Mtelela — Wed, 31 Jan 2024 00:00:00 +0000

This study applies remote sensing (RS) as a geologic mapping aid tool , using Handeni Block of Tanzania as a case study. To achieve the objective of this study, we have utilized various RS processing and image enhancement techniques on multispectral data, including ASTER, Landsat 5, Landsat 8, and Sentinel 2A. The method proved successful whereby both Landsat-5-data with band combination (BC) 7:4:2 and 7:5:4 and band ratio (BR) 5/3:5/1:7/5 and Landsat-8 data with BCs 5:6:7 and 7:6:4 mapped out marble units. Sentinel 2A data (with BC 8:11:3, BRs 12/2:11/2:8/11; 12/4:11/3:11/2 and 12/4:12/2:11/3) together with image enhancement decorrelation stretch on BC 4:3:2 and BC 8:11:3 images succeeded to map other major geologic units. The findings were tested using another approach, an unsupervised classification (K-means algorithm) of Landsat 8 data and unsupervised and supervised classifications by IsoData and minimum distance algorithms, respectively. Similar results were obtained from the image classification whereby Sentinel 2A data produced classified images, which consistently delineate the same lithologies. Geologic structures (lineaments) have been mapped by ASTER DEM data. The result from supervised classification using end-member spectra of the collected representative rock samples also supports the remotely sensed lithologies, demonstrating the usefulness of RS in geologic mapping. The finding of this work have shown that the integration of RS and rock spectral analyses can be used as a robust aiding tool in geologic mapping. The method is more resource efficient than a purely conventional approach.

Heavy Metals Analysis and Physicochemical Characterization of Groundwater at a Battery Recycling Site in South-western Nigeria

Wed, 31 Jan 2024 00:00:00 +0000

Indiscriminate dumping of battery waste is a huge issue that endangers human health and the environment. This study aimed at analysing the health impacts of exposure to pollution from spent battery recycling in Ogun State, which houses a diverse range of battery recycling industries. At this study site, forty water samples were studied over the Wet and Dry seasons to assess the impact of battery recycling waste on groundwater. Except for the TSS, the physiochemical parameters of the groundwater vary with season and are within the permissible limits. The electrical conductivity (EC), turbidity, Phosphorus, Biochemical oxygen demand (BOD), Dissolve oxygen (DO), and Total suspended solid (TSS) within the study year ranges from 51.00 - 178.22 S/cm, 2.26 - 2.36 NTU, 0.089 - 0.66 mg/L, 13.3 - 14.2 mg/L, 5.06 - 5.67 mg/L, and 78.0 - 88.4 mg/L, respectively. Furthermore, the average concentrations (in ppm) obtained for Mn, Cu, Zn, Ni, Cd, As, Fe, Pb, Cr, and Co are 0.407 – 0.42, 0.355 – 0.369, 0.179 – 0.225, 0.061 – 0.265, 0.366 – 0.464, 0.488 – 0.631, 0.544 – 0.601, 0.481 – 0.576, 0.284 – 0.334, 0.3 – 0.382. The Heavy Metal Pollution Index (HPI) values ranging from 3.880 to 4.528 indicate minimal levels of heavy metal contamination, but water quality index (WQI) scores ranging from 124.68 to 131.46 indicate potential environmental hazards.

Quantifying the Strength of the El Niño Southern Oscillation and the Indian Ocean Dipole in Influencing the OND Rainfall Season in Tanzania

Benjamin William Ongito, Paul TS Limbu — Wed, 31 Jan 2024 00:00:00 +0000

The current paper examines the strength of variability between the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) in influencing October to December (OND) rainfall over the bimodal rainfall regime of Tanzania. The empirical orthogonal function (EOF), correlation analysis, and composite analysis were used during the data analysis. The results show more rainfall distribution over the western part of the Lake Victoria basin and to the peripheral of the northern coast of the country, thus suggesting that, during the OND rainfall season, the onset starts in the western part of the Lake Victoria basin, then spreads to the rest of the areas under investigation as the season progresses. Furthermore, on the spatial scale, the findings revealed that there is a strong correlation between IOD and ENSO indices and OND rains in the northeastern highlands. Furthermore, a robust temporal correlation is revealed between the mean OND rains over the bimodal rainfall areas and IOD (r = 0.70) compared to ENSO (r = 0.62). The anomalous warming over the western Indian Ocean (positive IOD) has a faster response to OND rains over the bimodal rainfall regime of Tanzania compared to the remote influence induced by anomalous warming from the central equatorial Pacific Ocean (warm phase of ENSO). Meanwhile, dry years are associated with negative IOD and the cold phase of ENSO conditions. The findings offer valuable insights on strategies for mitigating the effects associated with extreme weather events and improving resilience in Tanzania.

Preparation of 2D Tungsten Diselenide (WSe2) thin films by selenization of DC-sputtered W precursors

Lwitiko P. Mwakyusa — Wed, 31 Jan 2024 00:00:00 +0000

Two-dimensional layered transition metal dichalcogenides based on WSe₂ films demonstrated promising properties for nano-electronics and photovoltaic applications. In this work, WSe₂ films were prepared by selenization of DC-sputtered W precursors. The influence of the selenization temperature on the structural, morphology, and optical properties of the WSe₂ films was investigated. The selenization temperature was varied from 350 °C to 450 °C at the interval of 50 °C. Structural, morphology and optical properties of the WSe₂ were investigated using X-ray diffractometry (XRD), Atomic Force Microscope (AFM), and UV-VIS-NIR spectrophotometer, respectively. XRD analysis revealed that all WSe₂ were polycrystalline and exhibited the co-existence of c-axis perpendicular and parallel substrate texture. Samples selenized at 400 °C demonstrated strong - types of crystal orientations – perpendicular c-axis substrate texture – dominated crystal growth. The AFM images further revealed the co-existence of parallel and perpendicular crystal orientations for samples selenized at 350 °C and 450 °C. Optical measurement showed that all WSe₂ samples were transparent and consisted of an excitonic peak at the wavelength of around 620 nm. The estimated bandgap values were in the range of 1.22 eV to 1.37 eV which is somchat lower than expected – the presence of W₅O₁₄ phases is suggested to be the main cause.

Synthesis of Template-free Flower-like ZnO Nanorods using a Simple Chemical Bath Technique

Benard S. Mwankemwa — Wed, 31 Jan 2024 00:00:00 +0000

Flower-like ZnO nanorods were successfully synthesised using a template-free, low-temperature chemical bath deposition method. The effects of growth time on the structural, morphological, and vibrational properties of flower-like zinc oxide were investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that the crystallite size and density of flower-like ZnO nanorods increased with increasing growth time. Raman spectroscopy confirmed the existence of specific Raman modes that correspond to the wurtzite structure of ZnO. In addition, Raman measurements revealed that increased growth time increases the Raman modes intensity of the flower-like ZnO nanorods. Moreover, the measurements of the Au/ZnO nanorods/FTO Schottky diode showed that all devices functioned as Schottky diodes and rectifying; however, their ideality factor was greater than 1. In addition to the ideality factor, the Schottky barrier height was calculated and slightly increased with growth time. The values of Schottky barrier height obtained were 0.502 eV, 0.523 eV, 0.516 eV and 0.529 eV for samples grown at 1, 2, 3 and 4 h, respectively.

Micro Machining of a Si3N4/SiO2/Ti/Pt Hotplate and Its IR Emissivity Properties

Egidius R. Rwenyagila — Wed, 31 Jan 2024 00:00:00 +0000

This paper presents the fabrication processes for a Si₃N₄/SiO₂/Ti/Pt membrane based micro hotplate (MHP) using photolithography (PL) micro-machining techniques. The properties of the MHP filament are investigated and overall performance characteristics with regard to infrared (IR) radiation emissivity, resistance, breakdown voltage, and temperature of the fabricated Si₃N₄/SiO₂/Ti/Pt micro heater. During characterization, the results show the device breakdown voltage of 24.24 V corresponding to the optimum operation temperature of ~ 1730.30 K. The device also showed an emissivity value of 5.2% with ~ 7% efficiency of transforming electrical power to IR thermal radiation power. The relationship between temperature and resistance, behaviour of fourth power of temperature and thermal response time constant of IR radiation obtained from direct experimental measurements, analytical calculations and extrapolations are shown to provide practical parameters that are needed for applications of MHP in IR radiation sources.

Evaluation of the Modulatory Effects of Capsicum Chinensis Methanol Extract in Streptozotocin-Induced Diabetic Neuropathic Pain in Mice

Wed, 31 Jan 2024 00:00:00 +0000

Diabetes is one of the common causes of neuropathic pain. The first-line treatment drugs used in alleviating neuropathic pain can cause adverse effects. Therefore, the aim of this study is to evaluate the analgesic property of Capsicum chinensis, since the plant was reported to be used against chronic pain in traditional medicine. Streptozotocin-induced diabetes was adopted to model neuropathy in mice and the antihyperalgesic effect of the extract was evaluated using a hot plate test, cold allodynia test, and Randall- Selitto paw pressure test. The plasma level of pain-associated inflammatory biomarkers like interleukin-6 (IL-6) and tissue necrotic factor-α (TNF-α) was also measured. Treatment with varying doses of extract (1, 2.5, and 5 mg/kg) significantly (p < 0.05) increased the mean reaction time to thermal pain during hot and cold plate tests. During the Paw pressure test, reaction time was significantly prolonged in the treatment groups and the plasma level of TNF-α and IL-6 were reduced (p < 0.05). The extract showed a better antihyperalgesic effect than the positive control drug (gabapentin). The result obtained showed that Capsicum chinensis extract can alleviate diabetes neuropathic pain in mice models with a better analgesic effect thanthe control drug (gabapentin).

Gene Flow Between the Wild Rice Species (Oryza longistaminata) and Two Varieties of Cultivated Rice (Oryza sativa) in Kilombero District, Tanzania

Hashim M. Mangosongo, Emmarold E. Mneney , Bramwel Wanjala — Wed, 31 Jan 2024 00:00:00 +0000

The direction and rate of gene flow between the perennial wild rice species, O. longistaminata and cultivated rice, O. sativa was investigated using nine Microsatellite (SSR) markers. The study involved characterization of parental lines of two cultivated rice varieties and O. longistaminata and their F1 progenies. Presence of crop-specific alleles in the wild species or vice-versa was used as an indicator of occurrence of gene flow between the two species. The study revealed that gene flow between O. longistaminata and each of the two varieties of O. sativa occurs naturally. The direction of gene flow was mainly from the cultivated to wild species. The rate (frequency) of gene flow was higher from cultivated (O. sativa) to wild rice (O. longistaminata) than from O. longistaminata to O. sativa and varied with cultivated rice variety. Higher rate of gene flow from cultivated to wild species could be due to floral structure and out-crossing nature of the wild species (O. longistaminata). Gene flow between O. longistaminata and O. sativa is likely to change genetic integrity of natural populations of the two species in areas where they occur sympatrically. However, isolation by distance can help to control gene flow between these species.

Potential of Endophytic Fungal Isolates in Improving Productivity and Postharvest Marketable Fruit Qualities of Tomato

Gabriel Michael, Emmanuel M. Sangu — Wed, 31 Jan 2024 00:00:00 +0000

In Tanzania, low tomato (Solanum lycopersicum) yield and postharvest marketable fruit qualities remain significant limitations for tomato grower’s profit. Seven endophytic fungal isolates from pyrethrum and Lemongrass leaf and or flowers were evaluated to promote tomato productivity and fruit qualities. The isolates were inoculated by priming the seeds in spore suspension, and the variations in the number of germinated seeds, seedling vigour, yield and fruit qualities were compared across the treatments. It was observed that only three isolates induced more than 50% seed germination. Epf1 and Epl1 isolates showed significant promotion of seed germination (F 0.05 (pdf, 23) = 8.121 and P = 0.001) and seedling vigour. Isolate Epf1 increased fruit number (18.4%) and weight (17%) but reduced fruit size (0.63%); the Epl1 increased fruit size (12%) and reduced fruit number (14.4%). The Epf1 induced delayed fruit ripening, colour development and softening, decaying, and prolonged shelf life by 9 days. These findings indicate that promoting tomato productivity and postharvest marketable fruit qualities is isolate-specific; therefore, it requires diligent screening. Incorporation of the Epf1 isolate through seed priming with fungal spore suspension demonstrated a high potential for increasing tomato productivity and postharvest marketable fruit qualities.

Molecular Characterisation of Traditional Cashew (Anacardium occidentale L.) Populations from Nachingwea and Newala Districts in Tanzania

Hussein R. Chiumbi , Hashim M. Mangosongo — Wed, 31 Jan 2024 00:00:00 +0000

This study assessed the genetic diversity of 120 selected cashew plants from Nachingwea and Newala traditional cashew populations, comprising of 60 cashew plants from each population. Eight Simple Sequence Repeats (SSR) makers were used to ascertain the extent of genetic variation within and between the two traditional cashew populations. Genomic DNA extraction and Polymerase Chain Reaction (PCR) were performed using standard protocols. The results showed that all SSR markers were polymorphic. Average Polymorphic Information Content (PIC), heterozygosity, number of alleles per locus, allelic frequency and Shannon’s Index were 0.540, 0.721, 3.391, 0.666 and 0.649, respectively. Analysis of molecular variance results showed that genetic variation within populations was 88% while genetic variation between populations was 12%, implying gene flow between the populations. The results further showed that the two cashew populations are genetically diverse and that Nachingwea traditional cashew population was genetically more diverse than Newala population. High genetic variation observed in the cashew populations shows that they are suitable for use in cashew breeding programmes. Thus, conservation of traditional cashew populations is recommended

Woody Species Composition, Structure, Regeneration Status and Carbon Storage of Mkulazi Forest Reserve in Tanzania

Ezekiel E. Mwakalukwa, Christoganus John, Paulo J. Lyimo — Wed, 31 Jan 2024 00:00:00 +0000

Little is known about the status of forest condition and carbon storage potential of Mkulazi forest reserve (MFR) located in Morogoro District, Tanzania. This study was conducted to assess i) woody species composition, richness and diversity, ii) stand structure, iii) regeneration status and iv) carbon storage. Data collection for vegetation involved establishment of 100 concentric circular sample plots in the forest area of 65,710 ha. A total of 54 plant species for trees and shrubs with DBH ≥ 5 cm that belongs to 20 plant families were identified. The diversity of woody species was high (H’ = 3.11), while Stem density was 336 ± 126 stems ha^-1, basal area was 9.48 ± 2.88 m²ha^-1 and stand volume was 96.22 ± 32.51 m³ha^-1. For the regeneration with DBH < 5 cm, a total of 26 plant species belonging to 11 plant families were identified. The diversity of woody species was also high (H’ = 3.14) and stem density was 1,198 ± 847 stems ha^-1. The mean carbon stocks above ground for trees and shrubs with DBH ≥ 5 cm were 32.13 ± 10.91 Mg C ha^-1 and that of below ground were 11.84 ± 3.58 Mg C ha^-1. The observed high diversity of woody species, regeneration status and relatively high carbon storage potential signifies the importance of continuing protecting this reserve.

Microbial Quality of Fresh Juices Sold by Street Vendors and Associated Human Health Risks: The Case of Ilala Ward, Dar es Salaam City, Tanzania

Juliana I. Rubaratuka, Godwill D. Mrema , Thomas J. Lyimo — Wed, 31 Jan 2024 00:00:00 +0000

Microbial food quality serves to indicate health risks associated with the consumption of contaminated foods. This study aimed to determine the microbial quality of fresh juices and the level of awareness and perception of the consumers and juice vendors at Ilala Ward, Dar es Salaam. Fresh samples of sugarcane, mango and mixed fruit juices were collected from four different sampling stations and analysed using standard methods for Total Coliform (TC), Faecal Coliform (FC) and Total Viable Count (TVC). The level of awareness and perception of 60 juice vendors and 60 consumers were also assessed by using questionnaires. The results showed that TC numbers ranged from the lowest mean of 6.100±4.180x10⁶to 7.483±3.650x10⁷MPN/ml, FC ranged from 2.566±0.989x10⁶to 2.017±1.687x10⁷MPN/ml while TVC ranged from 5.046±1.032x10⁹to 5.871±0.835x10⁹CFU/ml of fresh juices. The level of TC, FC and TVC was beyond the recommended international and Tanzanian standards showing that fresh juices posed a high risk for consumers. On the other hand, 42% of the juice consumers had low awareness of microbial contamination of fresh juices, which leads to high health risks. It is recommended that street juice vendors should adopt proper hygiene measures and undergo appropriate training on microbial quality, food safety and sanitation.

Woody Plant Assemblages of Recently Declared Village Land Forest Reserve in The Eastern Afromontane Biodiversity Hotspot

Samora Macrice Andrew — Wed, 31 Jan 2024 00:00:00 +0000

Understanding of species composition of village land forest reserves and their driving factors informs adequate development of effective restoration strategies and sustainable forest management of miombo woodlands. This study assessed the effects of human disturbance as well as environmental variables on woody plant species composition using 24 square plots of 10 x 10 m in a recently declared village land forest reserve in the Eastern Afromontane biodiversity hotspot of Tanzania. Ordination analysis technique canonical correspondence analysis was used to identify important vegetation gradients and significant factors that explain the spatial variation in species composition of woody plants. Results showed that, 779 individual woody plants were recorded, of which 379 were seedlings (48.6%), 102 saplings (13.1%) and 298 adults (38.3%). The three most dominant plant species were Brachystegia spiciformis (42.2%), Diplorhynchus condylocarpon (9%) and B. boehmii (8.7%), while the least were Multidentia crassa and Diospyros squarrosa with each species having less than 1% overall abundance. Pterocarpus angolensis, a highly protected and near-threatened tree species, was also recorded but with only very few individuals. Canopy cover and soil pH were the two most important variables explaining the spatial variation in species composition of woody plants. These results emphasise that village forests are important for preserving native and threatened tree species, and improved management should discourage all practices that change natural conditions of canopy cover and soil pH to safeguard the remaining village forests, biodiversity and rural livelihoods.

Population Genetic Structure and Demographic History of Opsaridium microcephulum along Lake Nyasa

Alex Nehemia, Alinanuswe J. Mwakalesi — Wed, 31 Jan 2024 00:00:00 +0000

The Sanjika, Opsaridium microcephalum is among the fish species that serve as a major source of proteins and income to people along Lake Nyasa. However, the information on its genetic diversity and structure particularly in the Tanzania part of the Lake is limited. Therefore, the assessment of the genetic diversity and structure of O.microcephalum along the Lake Nyasa part of Tanzania was conducted in the current study using a fragment of the mitochondrial COI gene from 92 individuals of O. microcephalum. The findings showed that an average haplotype diversity and average nucleotide diversity were 0.8065 ± 0.0314 and 0.002380 ± 0.001640, respectively. The molecular Variance (AMOVA) indicated significant genetic variations among the subpopulations studied (Overall Φ_st = 0.31560, p < 0.001). The lowest haplotype diversity was recorded at Manda and the highest haplotype diversity was recorded at Buloma. The lowest nucleotide diversity was recorded at Manda and the highest was recorded at Lupingu. The differences in genetic diversity can be a possible indicator of different localised evolutionary forces that require attention to conservationists for the sustainable management of O. microcephalum