Tanzania Journal of Science

Spatial and Temporal Solar Potential Variation Analysis in Uganda Using Measured Data

Fri, 31 Mar 2023 00:00:00 +0000

The paper presents an analysis of spatial and temporal solar potential variations in Uganda. The solar radiation potential distribution was investigated based on measured data from 56 ground meteorological stations across Uganda from January 2015 to February 2022. The data were recorded after every 5-minute interval. The monthly average daily Global Horizontal Irradiance (GHI) was analysed using the spatial inverse distance weighting (IDW) interpolation technique in ArcGIS 10.7.1. The GHI distribution was found to have maxima at equinox and minimum between June and July. The average global horizontal irradiation is found to be 1680 KWh per year, with a daily variability below 10%. This is above the threshold for solar energy applications and with such low variability, large scale solar PV plants can be installed with minimum backup requirements. Northern Uganda receives the highest average daily global horizontal irradiation of 5.38 Whm^–2day^–1, while Western Uganda receives 4.16 Whm^–2day^–1, the lowest. The average AM/PM ratio depicted a value above 2 for all regions in Uganda and therefore, optimal solar energy exploitation for fixed systems favours eastern orientation. The central, eastern and northern Uganda which is 69.3% of the country has relief favourable for large scale solar PV power plants and CSP facilities.

Keywords: GHI, IDW, Global solar radiation, Solar insolation, PV power plants, Uganda

Prevalence of Endoparasites and Haematology in Redbelly Tilapia from a Shallow Tropical Reservoir in Ghana

Elliot H. Alhassan, Samuel A. Osei, Akwasi Ampofo-Yeboah, Samuel O. Dandi — Fri, 31 Mar 2023 00:00:00 +0000

The goal of this study was to assess common endoparasites on Tilapia zillii in the Tono Reservoir, as well as to investigate the mean intensity and prevalence of these parasites. A total of 175 fish specimens were examined during the study. Endoparasites of three metazoans and one protozoan were observed from the Tilapia zillii gills, intestines, and stomach. The findings showed that the most common endoparasites affecting Tilapia zillii are Ichthyopthirius multifiliis, Bothriocephalus sp., Contracaecum sp., and Dactylogyrus sp. Also, Contracaecum sp had the highest prevalence of 29.71, followed by Bothriocephalus sp (18.86), Ichthyopthirius multifiliis (12), and Dactylogyrus sp (6.86). The average quantity of Bothriocephalus sp was 0.84, Contracaecum sp was 1.33, Dactylogyrus sp was 0.31, and Ichthyopthirius multifiliis was 0.54. The reservoir's physicochemical parameters changed every month due to inflows and other runoffs joining. Low levels of these parameters were discovered to influence the prevalence and distribution of these parasites. Haematological parameters showed significant changes between the adult and fingerling groups, where it was observed an improvement in health status in the adult group. It was also observed that fingerlings (0.1–20 g) were more infected, which significantly affected their blood profile.

Keywords: Tilapia zillii, endoparasite, blood profile, pathogenic effects, environmental stress

Semi-Analytic Approach to Solving Rosenau-Hyman and Korteweg-De Vries Equations Using Integral Transform

Adedapo Chis Loyinmi, Kabir Oluwatobi Idowu — Fri, 31 Mar 2023 00:00:00 +0000

In this research, we proposed the fusing of Elzaki transform and projected differential transform (PDTM) to obtain an analytical or approximate solution of the Rosenau-Hyman and Korteweg-de Vries equations which respectively govern pattern formation in liquid drops and model of waves on shallow water surfaces. The results obtained presented in tables and graphs showed better efficiency, accuracy, and convergence of the method to handle Rosenau-Hyman and Korteweg-de Vries equations when compared to other methods in the literature.

Keywords: Rosenau-Hyman Equation; Korteweg-de Vries equation; Elzaki Projected differential transform method; Semi-analytic approach

Ethanol Extracts from Selected Tanzanian Medicinal Plants Selectively Inhibit Plasmodium falciparum Growth In Vitro

Robert Christopher, Amina Msonga, Heinrich C. Hoppe, Fabrice F. Boyom — Fri, 31 Mar 2023 00:00:00 +0000

This study aimed to assess the in vitro antiplasmodial and cytotoxic activities of ethanol extracts from the root barks, leaves and stem barks of seven medicinal plant species growing in Tanzania. The antiplasmodial activities of extracts against chloroquine-sensitive (3D7) and multidrug-resistant (Dd2) strains of Plasmodium falciparum were determined using a SYBR green I-based fluorescence assay, while the cytotoxicity of active extracts was determined against the human HepG2 cell line using a resazurin-based assay. Out of twenty-one extracts screened, two of them, namely, DFRE from Dracaena fragrans root bark (IC₅₀Pf3D7 = 2.4 mg/mL) and EHSE from Erythrina haerdii stem bark (IC₅₀Pf3D7 = 8.6 mg/mL and IC₅₀PfDd2 = 7.6 mg/mL), exhibited good potencies against P. falciparum parasites. The two extracts emerged as the most promising and selective inhibitors (inhibited the growth of P. falciparum strains and were not toxic to the human HepG2 cell line) of chloroquine-sensitive (3D7) and multidrug-resistant (Dd2) strains of P. falciparum. Eight other extracts showed moderate potencies with IC₅₀values ranging from 11–25 mg/mL against both plasmodial strains, while the remaining 11 extracts were mildly active with IC₅₀values ranging from 25.1 to 96.7 mg/mL. The results of the cytotoxicity test indicated that the median cytotoxic concentrations (CC₅₀) of the tested extracts were all ≥ 224.8 mg/mL, leading to selectivity indices (SI) > 10-fold for most of the extracts. The findings described in this article support the traditional use of the investigated medicinal plants to treat malaria.

Keywords: Antiplasmodial; Cytotoxicity; Ethanol extracts; Plasmodium falciparum

Simulation of Mathematical Model of Network Interference on Global System for Mobile Communication

Yidiat O. Aderinto, Yusuf Musa — Fri, 31 Mar 2023 00:00:00 +0000

Network interference is the incorporation of undesirable signals to desirable ones in an interconnected system. In this paper, the simulation of mathematical model of network interference with respect to global system of mobile communication is presented. The model was formulated and analyzed mathematically. Numerical simulation was carried out using real life data from Communication Towers Nigeria Limited, Northwest regional office Kaduna, Nigeria. The results obtained were very close to that of laboratory investigation.

Keywords: Mathematical Model, Network, Interference, Congestion, Mobile communication, Stability

A Cloud Based Model Symbiotic Organism Search Algorithm for Placement of Distributed Energy Resources in the Electrical Secondary Distribution Networks

Shamte Kawambwa, Daudi Mnyanghwalo — Fri, 31 Mar 2023 00:00:00 +0000

The increased penetration of distributed energy resources (DERs) technologies to residential users has fostered the need for DERs integration and control methods in the secondary distribution networks (SDN). In order to reap the potential advantages of DERs and achieve their inclusion in the electrical power system while avoiding their negative impacts, the DERs should be optimally placed and sized. Considering the nature of electrical networks and DER operations, the DERs placement is a nondeterministic polynomial hard (NP-hard) optimization problem. Metaheuristic algorithms are efficient for solving DER placement problems. Metaheuristic algorithms for DER placement in SDN involve high computational effort, theoretical convergence assumptions that cannot be satisfied in the real world and dependence on parameter settings. Therefore, this study proposes a DER placement algorithm that employs a cloud-based model symbiotic organism search algorithm (CMSOS). The CMSOS is attributed to simple implementation and computation, good convergence, and parameter independence. The electrical network segment taken for Tanzania’s electrical distribution network was used for testing the algorithms, considering power loss and voltage deviations. Results show that using DERs in the proposed locations reduces power loss by 89.3%. The convergence profile shows that the proposed CMSOS-based algorithm converges faster than the conventional symbiotic organism search algorithm (SOS).

Keywords: Metaheuristic Algorithms, Symbiotic Organism Search, DER Placements, Radial Distribution Network, Cloud-based model

Household and Community Factors Affecting Nutritional Status of Under-five Children (6-59 months) in Gairo District Using Composite Index of Anthropometric Failure

Tausi M. Mohamed, Cornelio N. Nyaruhucha — Fri, 31 Mar 2023 00:00:00 +0000

In Tanzania, where the majority of under-five children are affected, undernutrition is still a significant public health concern. The study aimed at assessing the prevalence of undernutrition and its determinants among under-five children in Gairo District using a Composite Index of Anthropometric Failure (CIAF). A household-based cross-sectional study was employed involving 300 under-five children with their mothers/caregivers in three wards in the Gairo District. Data collection on socio-demographics, dietary diversity, and healthcare factors were collected by interviewer-based semi-structured questionnaires. Anthropometric measurements using standard procedures were performed to collect anthropometric data. Odds ratios with a 95% confidence interval and p-value ≤ 0.05 were used to identify determinants of undernutrition. Prevalence of undernutrition using CIAF was 57.3%, whereby children with single failure were 105 (61%), double failures were 62 (36%) and triple failures were 5 (2.9%). Factors that were significantly associated with undernutrition were the nearest health facility (p = 0.014; OR: 0.504 (0.291-0.873)), place of delivery (p = 0.000; OR: 0.717 (0.107-0.490)), source of drinking water (p = 0.001; OR: 0.452 (0.283-0.722)), type of latrine (p = 0.000; OR: 21.338 (9.807-46.427)), household solid waste disposal method (p = 0.012; OR: 1.806 (0.682-1.964)), birth weight (p = 0.000; OR: 5.400 (2.625-11.109) and marital status (p = 0.00; OR: 0.403 (0.240-0.676)). Therefore, nutrition intervention efforts should be given to the factors reported to positively affect undernutrition.

Keywords: Undernutrition, factors, Gairo, under-five, CIAF

Evidence of Distinct Genetic Stocks of the Bottlenose Wedgefish (Rhynchobatus australiae) in the Indo-West Pacific

Rehema J. Simwanza , Cyrus Rumisha — Fri, 31 Mar 2023 00:00:00 +0000

Populations of the bottlenose wedgefish (Rhynchobatus australiae) in the Indo-West Pacific (IWP) have declined by nearly 80% in recent decades. In response, IWP countries are establishing sanctuaries to provide refuge for the fish. However, little is known about the genetic stock structure of the fish in the region. Hence, this study analysed partial sequences (610 base pairs) of the cytochrome oxidase subunit (COI) gene from eight bottlenose wedgefish populations in the IWP to assess the genetic stock structure of the fishery. The sequences revealed that Western Indian Ocean (WIO) populations are genetically distinct from those in the West Pacific (WP) (F_CT = 0.24, p = 0.01) and Australia (F_CT = 0.88, p = 0.01). Similarly, WP populations were genetically distinct from Australian populations (F_CT = 0.42, p = 0.01). This suggests that the IWP contains three genetically distinct stocks of the bottlenose wedgefish: the WIO, WP, and Australia. The indices of genetic diversity and population size showed that the WIO stock has low genetic diversity and population size when compared to the WP and Australia. This shows that efforts to establish elasmobranch sanctuaries in the IWP should take into account the three identified stocks, with priority given to the WIO.

Keywords: Restricted gene flow, genetic connectivity, elasmobranch sanctuaries, Indo-West Pacific Ocean

DNA Barcoding Reveals Occurrence of Cardiocephaloides sp. (Digenea: Strigeidae) Infecting the Great Cormorant Phalacrocorax carbo (L. 1758) in Mwanza Gulf, Lake Victoria

Fred D Chibwana — Thu, 30 Mar 2023 00:00:00 +0000

Cormorants (Pelecaniformes) are widely distributed worldwide, occurring as coastal birds in inland waters and marine environments, and have been implicated in the transmission of some aquatic parasites. As such, the objective of the present work was to investigate the occurrence and morphological variations in Cardiocephaloides (Digenea: Strigeidae), parasites of the great cormorant Phalacrocorax carbo. The Cardiocephaloides specimens used for molecular analysis (DNA barcoding (cox1) region) were obtained from the intestines of the great cormorants collected from Mwanza Gulf in Lake Victoria. Morphological examination of Cardiocephaloides specimens showed the possible co-existence of four morphospecies belonging to the genus Cardiocephaloides. However, detailed analyses of the cox1 sequences, phylogeny and haplotypes revealed that all four morphospecies belonged to a single unknown species of Cardiocephaloides. This paper provides the first report on the great cormorant Phalacrocorax carbo, serving as the definitive host for Cardiocephaloides in freshwater systems. The findings also reveal that the diversity of Cardiocephaloides in Africa is higher than earlier reported. Moreover, it highlights the need for more research in Tanzania to divulge snail and fish species involved in the life cycles of digenean species occurring in birds and other vertebrates in aquatic environments.

Keywords: Digenean trematodes; Strigeidae; Phalacrocorax carbo; Cardiocephaloides; cox1

Dosimetric Comparison Between Two and Six Beams Conformal Radiotherapy Plans for Paediatric Wilm's Tumour Patients at Ocean Road Cancer Institute, Tanzania

Fri, 31 Mar 2023 00:00:00 +0000

This study aimed to compare the dose distributions of three-dimensional conformal treatment planning using two and six radiation beams among paediatric patients receiving radiotherapy for Wilms tumour at Ocean Road Cancer Institute. CT scans of 53 patients were used to generate 106 treatment plans, 53 plans for two beams, and 53 plans for six beams. Planning target volumes and organs at risk parameters were compared between both plans using paired samples t-test. A p-value < 0.05 was considered statistically significant. The findings showed that the D_95% and D_mean of the target are better with six beams than with the two-beam plans (p ˂ 0.001). The conformity index and monitor unit are significantly better with two-beam plans than with six-beam plans (p ˂ 0.001). No volume of the contralateral kidney received more than 12 Gy for both two and six plans. There were no differences in D_max for the spinal cord (p = 0.208), while D_mean was observed to be lower in two compared to six beams (p ˂ 0.001) for the liver. Six beam plans have good target coverage, while two beam plans have good conformity index and monitor unit. The observed doses to the organs at risk in both plans were lower than their normal tolerance.

Keywords: Wilm's tumour, Three-dimensional conformal radiotherapy, whole abdomen radiotherapy, paediatric radiotherapy, Dosimetry

Evaluation of Image Enhancement Techniques for Electrical Capacitance Tomography Applications

Alfred J Mwambela — Fri, 31 Mar 2023 00:00:00 +0000

The fast generation of images in Electrical Capacitance Tomography (ECT) systems is a desirable feature for many industrial applications. Non-iterative reconstruction algorithms which qualify for this requirement generate poor-quality images. The Linear Back Projection (LBP) is the fastest non-iterative reconstruction algorithm. The challenge is to find a technique to improve the quality of images from LBP at a low computational cost. Image enhancement techniques have been investigated for improving the quality of images reconstructed from the LBP algorithm. Simulated and measured static and dynamic flow data were used in the evaluation. The performance results were benchmarked with results from the Projected Land Weber (PLW) one of the accurate iterative reconstruction algorithms. The Gompertz enhancement algorithm was found to have 3.5 times more computation cost than the LBP reconstruction algorithm and the accuracy of the iterative PLW reconstruction algorithm. This is noteworthy since the algorithm does achieve a good balance between accuracy and speed. The fact that the accuracy gained satisfies the reservoir management standards in the multiphase hydrocarbon production sector is significant in this regard.

Keywords: Electrical Capacitance tomography, Multiphase flow imaging, Maximum entropy thresholding, Gompertz distribution, Image enhancement

Short-Term Energy Load Forecasting Model with Sample Filtering

Ruthbetha Kateule, Lucas A. Sakala , Mahadia Tunga — Fri, 31 Mar 2023 00:00:00 +0000

Short-term energy load forecasting is a crucial task in the power smart grid, which enables the power utilities to understand the future energy demands and plans to attain the demand and supply equilibrium, thereby optimizing power deployment and reducing power losses. Several techniques have been implemented to enhance energy load forecasting. However, the nonlinear nature of the data collected in the smart grid makes it difficult to attain 100% energy load forecasting accuracy. For instance, the Deep Feedforward Neural Networks model based on Input Attention Mechanism and Hidden Connection Mechanism has a mean absolute percentage error of 3.17%; model based on Sequence to Sequence Recurrent Neural Network with Attention had a mean absolute percentage error of 2.7%. The model based on Deep Recurrent Neural Networks with Levenberg–Marquardt backpropagation algorithm had a mean absolute percentage error of 0.58; and Deep Feedforward Neural Network with sample weights model had 3.22 % as root mean squared error. To improve energy load forecasting accuracy, this work proposed a model based on Deep Recurrent Neural Networks and sample filtering, which provides an exhaustive elucidation for modelling a sophisticated stochastic relationship between the input and output features. Deep Recurrent Neural Networks have proven to be good at modelling the nonlinearities in data of different fields and are mostly used in energy load forecasting to reduce forecasting error and a high degree of overfitting. Sample filtering is achieved through the use of K-Means clustering which determines the number of clusters to be used in the model. Findings from the study showed that by employing Deep Recurrent Neural Networks and sample filtering, the short-term energy load forecasting accuracy is improved in reference to mean absolute percentage error and root mean squared error of 0.31% and 1.014, respectively. As a result of the reduction in error, the energy demand and supply chain equilibrium are enhanced, thereby optimizing power deployment and reducing power losses.

Keywords: Machine learning, Neural networks, Sample filtering, Smart grid, Short-term energy forecasting

Effects of Vacuum Packaging and Chilling Storage on the Microbiological Changes of the Superheated Steam Dried Sardines

Fri, 31 Mar 2023 00:00:00 +0000

Fish are important sources of protein and micronutrients for combating malnutrition. Since fish are highly perishable, methods for processing and preserving them should be the main focus to increase their shelf life and maintain their quality. The present study assessed the effectiveness of the superheated steam dryer (SSD) in processing sardines, and examined the effects of packaging and storage conditions on their microbiological quality. Sardines collected from the Mafia Island were dried in SSD, air-packed and stored at room temperature (AR), air-packed and stored at chilling temperature (AC), vacuum-packed and stored at room temperature (VR), and vacuum-packed and stored at chilling temperature (VC) for 49 days. Following drying, the total viable bacterial counts (TVBC) and total yeast and mould counts (TYMC) both decreased from the initial values of 9.14 (TVBC) and 2 (TYMC) log CFU/g in the fresh samples to 0.00 log CFU/g. The AR samples had the highest microbial growths during storage (7.48 (TVBC) and 2.82 (TYMC) log CFU/g), whereas the VC samples had the lowest (1.79 (TVBC) and 1.42 (TYMC) log CFU/g). The AR treatment was rejected within 21 days, whereas the AC, VR, and VC treatments prolonged the sardines’ shelf life throughout the storage time.

Keywords: Superheated steam dryer, sardine, microbial analysis, vacuum packaging, chilling storage

Geo-Statistical Analysis of Meteorological Drought and Recurrence Intervals in the Context of Climate Change Over Extreme Northeastern Region of Nigeria

Iliya B. Abaje — Fri, 31 Mar 2023 00:00:00 +0000

This study examined the occurrence of meteorological drought in the context of climate change over the extreme northeastern region of Nigeria using rainfall and temperature data spanning a period of 60 years (1961-2020) and 40 years (1981-2020), respectively. Linear regression, 5-year moving average and Cramer’s test were used to examine the changes in the rainfall and temperature. Rainfall Anomaly Index was used in depicting periods of different drought intensities in the region. The trend analysis of the climate data revealed that the region has been experiencing increasing rainfall and temperature in recent years. Findings also revealed that the droughts of the 1980s were more severe than the Great Sahelian Droughts of 1968-1973. The year 1987 was the driest in the whole period of study (1961–2020). Contrariwise, about 81% of the region from 2000 to 2020 experienced normal to very wet conditions. The mean probabilities of mild, moderate, and severe droughts in the area were 0.14 (recurrence interval of 8 years), 0.11 (recurrence interval of 11 years), and 0.07 (recurrence interval of 16 years), respectively. This study concludes that the number of drought occurrences has decreased in recent years. Therefore, government policies related to agriculture and water resources development in the area should take into account the increasing rainfall and temperature in recent years.

Keywords: Climate Change, Meteorological drought, Rainfall, Recurrence Interval, Severe Drought, Temperature

Maintenance Scheduling Algorithm for Transformers in Tanzania Electrical Secondary Distribution Networks

Hadija Mbembati, Kwame Ibwe, Baraka Maiseli — Fri, 31 Mar 2023 00:00:00 +0000

The drive by the government of Tanzania to electrify every village has resulted into expansion of the electrical secondary distribution networks (ESDNs). Therefore, maintenance management is of the highest priority for the smooth operation of the ESDNs to reduce unscheduled downtime and unexpected mechanical failures. Studies show that condition-based predictive maintenance (CBPdM) method allows the utility company to monitor, analyze and process the information obtained from ESDNs transformers. Thus, this study adopts the CBPdM method to develop a maintenance scheduling algorithm that can predict the transformer state, forecast maintenance time based on transformer load profile and schedule its maintenance using a knowledge-based system (KBS). Applying the challenge driven education approach, the requirements for developing an algorithm were established through an extensive literature survey and engagement of the key stakeholders from the Tanzania utility company. Our study uses the Dissolved Gas Analysis tool to collect the transformer parameters used in algorithm design. The parameter analysis was performed using Statistical Package for Social Sciences software. Results show that the designed KBS algorithm minimizes human-related maintenance errors and lowers labour costs as the system makes all the maintenance decisions. Specifically, the proposed maintenance scheduling algorithm reduces downtime maintenance costs by 1.45 times relative to the classical inspection-based maintenance model while significantly saving the maintenance costs.

Keywords: Electrical power network, Forecasted load consumption, Knowledge-Based System, Maintenance Scheduling, Predictive Maintenance, Secondary Distribution

Predictors of Attrition from Care and Treatment Centres among HIV-positive Pregnant and Breastfeeding Adult Women in Dar es Salaam, Tanzania

Felix Elias, Nyimvua Shaban, Edwin Rutalebwa — Fri, 31 Mar 2023 00:00:00 +0000

In Tanzania, poor retention rates among pregnant and breastfeeding mothers continue to be a problem, contributing to a mother-to-child HIV transmission rate of 11% in 2019, compared to a global target of 5%. The goal of this study was to determine the influence of retention on clinical outcomes and identifying predictors of attrition among HIV-positive pregnant and breastfeeding women from follow-up care in Dar es Salaam. A retrospective cohort study included HIV-positive women who engaged in PMTCT services in public and private health facilities between January 2016 and December 2019. Secondary data were extracted from databases used for routine follow-up in care and treatment clinics (CTCs). The estimates of cumulative incidences of poor retention from date of enrollment or ART initiation were assessed using Kaplan–Meier method. The Cox regression model was used to identify the predictors of attrition. Among 20,225 HIV-infected pregnant and lactating women enrolled in PMTCT services, 93.35%, 89.07%, and 85.24% were classified as retained in care at 12, 24, and 36 months, respectively. The attrition rate at the end of the follow-up period was 15.82%, and WHO clinical stages 3 or 4 (aHR = 1.67, 95% CI: 1.46–1.89; p-value < 0.001) and unsuppressed viral load (aHR = 3.79, 95% CI: 3.20–4.49; p-value < 0.001) were predictors of increased risks of attrition. The maternal age group 25–34 years (aHR = 0.24, 95% CI: 0.18–0.32; p-value < 0.001), being married or cohabiting (aHR = 0.45, 95% CI: 0.38–0.55; p-value < 0.001), an efavirenz (EFV)-based regimen (aHR = 0.26, 95% CI: 0.19–0.35; p-value < 0.001), and good adherence to ART (aHR = 0.61, 95% CI: 0.48–0.79; p-value < 0.001) were factors associated with reduced risks of attrition. The study shows that a strong tracking system for lost to follow-up (LTFU), that is, patients who miss appointments to the same health facility for more than 3 months after the last scheduled clinical visit, should be prioritised for successive PMTCT programmes for better clinical outcomes.

Keywords: Retention, Attrition, Treatment, Clinics, Loss-to-follow up

Land Cover Change as a Proxy of Changes in Wildlife Distribution and Abundance in Tarangire-Simanjiro-Lolkisale-Mto wa Mbu Ecosystem

Thobias Anthony, Nyimvua Shaban, Cuthbert Nahonyo — Fri, 31 Mar 2023 00:00:00 +0000

This study analyzed the land use and land cover (LULC) changes from 2000 to 2020 and examined its influence on wildlife distribution and abundance. LULC from satellite imagery for 2000, 2012 and 2020 were acquired from the United States Geological Survey (USGS). Supervised classification along with a maximum likelihood algorithm was used to classify satellite imagery into eight LULC classes: bareland, woodland, wetland, shrubland, grassland, waterbodies, cropland and built-up land. The results showed that grassland, wetland and woodland had declined, while shrubland, cropland and built-up land increased from 2000 to 2020. Grassland, wetland and woodland decreased from 48.1%, 14.1% and 4.4% in 2000 to 19.5%, 10.3% and 2.5% in 2020, respectively. Shrubland, cropland and built-up land expanded from 14.8%, 1.9% and 0.0% in 2000 to 39.0%, 17.2% and 1.9% in 2020, respectively. The findings suggest that the decline in grassland, wetland and woodland had affected terrestrial vertebrate species and their habitats through wildlife habitat destruction and land degradation leading to the changes in the wild animals’ abundance and distribution. The research highlights the need for continuous monitoring and reporting of land use and land cover changes and its effects on wildlife distribution and abundance.

Keywords: Biodiversity change, Land use and land cover change, Wildlife habitat, Tarangire-Simanjiro

Recruitment Behaviour in an African Meliponine Bee Species (hymenoptera, Apidae: Meliponini): Understanding Glandular Origin and Pheromonal Components

Fri, 31 Mar 2023 00:00:00 +0000

Meliponine bees are speculated to use a variety of communication mechanisms to effectively recruit workers of a colony to collect sufficient amounts of food to nourish the entire nest population. Mechanisms used to convey such information include thoracic vibrations and trophallaxis within the nest; footprint secretions and pheromone marks deposited in the field, or a combination of these signals and cues. There have been numerous discrepancies about the origin of trail pheromone production from the head, thorax, abdomen and leg regions of meliponine bees. Because the glandular origin of pheromone marks deposited by African meliponine bee’s species has not yet been investigated, we first confirmed if these species actually carry out scent marking and recruitment behaviour at visited food sources. Secondly, we tested if either nasonov or tarsal gland secretions elicited trail-following behaviour in newly recruited bees by means of chemical and electro-physiological analyses as well as with bio-assays testing both natural extracts and synthetic pheromone compounds from both glands. Significant differences were observed in the foraging patterns of the four bee species on collected resources (nectar, pollen and water) as the synthetic compound, (E)-β-farnesene was significantly as attractive to foragers of the four species when compared to the natural nasonov gland extract. Our results showed a significantly higher proportion of foragers from the four species been attracted to food resources baited with natural extracts from their own glands and recruited additional foragers to such baited food sites.

Keywords: Meliponine bee species, recruitment behaviour, nasonov glands, tarsal glands

Potential of Kaolin Clay on Formulation of Water Based Drilling Mud Reinforced with Biopolymer, Surfactant, and Limestone

Fri, 31 Mar 2023 00:00:00 +0000

Drilling the wellbore into subsurface formations is the earliest stage in the life of a well that requires a suitable drilling fluid with good rheological and filtration control characteristics to achieve a successful drilling operation. This paper reports on the formulation of water-based drilling mud using kaolin clay reinforced with biopolymer, surfactant, and limestone from Tanzania. The raw materials used for the formulation were characterized using XRD, XRF, FTIR, and TGA techniques. The rheological properties, filtration loss, pH, and density of the formulated mud were measured using a viscometer, filter press, pH meter, and mud balance, respectively. The XRD results revealed kaolinite and quartz as the main minerals in all kaolin clay samples which were in agreement with the FTIR findings. The mineralogical composition of the kaolin was observed to vary with the mining sites and influenced the rheological and filtration control characteristics of the mud. The beneficiated drilling mud showed better rheological and filtration control characteristics than the commercially available bentonite mud in Dar es Salaam market and was comparable with the API standards. These results, therefore, are not only new but rather important and novel information on the potential of kaolin clay for the formulation of water based drilling mud.

Keywords: Water-based drilling mud, kaolin clay, biopolymers, bentonite, surfactant

Polyphenolic Content and Radical Scavenging Activities of the Peel, Pulp and Seed of Avocado (Persea americana Mill.) Grown in Tanzania

Fri, 31 Mar 2023 00:00:00 +0000

Avocado is a healthy fruit and the consumption is continuously growing worldwide. The fruit contains polyphenolic compounds with antioxidant effects. Globally, research has been devoted to exploring the fruit quality, especially compounds with antioxidant effects, from different avocado-growing sites. However, the fruit quality of the Tanzanian avocado has so far not been investigated. In this study, the contents of polyphenols in peel, pulp and seed of avocados sampled in south-western Tanzania are described. The levels of total polyphenolic and flavonoid contents were measured, and antioxidant activity was evaluated using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The total polyphenolic content was highest in the seed and lowest in the peel (424 and 200 mg GAE/100 g DW, respectively). As for the total flavonoid content, the pulp had the highest value of 36.98 mg RE/100 g DW, while the seed had the lowest value of 32.54 mg RE/100 g DW. The overall average half maximal effective concentration (EC₅₀) values in decreasing order, corresponding to an increasing antiradical activity, were 4.90 (peel), 3.63 (seed) and 3.24 µg/mL (pulp). The seed and peel possessed high levels of total polyphenolic and flavonoid content, thus demonstrating substantial antioxidant capacity. Seed and peel can potentially be processed and included in the diet to provide inexpensive antioxidant ingredients of natural origin. Consumption of the seed will not only improve human health but also reduce the environmental pollution, as many thousand tonnes of avocado seeds are produced in Tanzania per year; a huge amount currently remains as waste.

Keywords: Flavonoid contents; Free radicals; EC₅₀; Polyphenolic content

Generation of Electricity by Using Microbial Fuel Cell Prototype Fed by Sewage: Case Study at the University of Dar es Salaam

Mahir M Said, Asia A Saad, Geoffrey R John, Aviti T Mushi — Fri, 31 Mar 2023 00:00:00 +0000

The access to electricity is still not reliable in Tanzania. Whilst, there are several locations within the country that have wastewater cites that are not economically used to produce electricity. At the University of Dar es Salaam (UDSM), there are main grid power, and few scattered solar panels. This study was intended to bridge the divide between the current increasing power demands of the UDSM by exploiting not so much used sources, such as electric energy from wastewater. This study was undertaken to develop a Microbial Fuel Cell (MFC) prototype fed by sewage in Dar es Salaam, for electricity generation using cost effective materials for the cathode compartment. The collection of samples took place using sewage substrates from the UDSM oxidation ponds. The untreated sewage was collected from oxidation ponds. Preliminary experiments were carried out to identify the cathode and substrate that produced better results in terms of volts and current output. Aluminium produced the most desirable results compared to copper, stainless steel and mild steel in all the substrates. On the other hand, untreated sewage with aluminium/carbon electrodes produced higher voltage and current compared to treated sewage with the same electrodes. Thereafter, a prototype of the MFC was developed by connecting three single chambered cells in series of 628 cm³ volume of untreated sewage with aluminium and carbon electrodes. The prototype generated a stable voltage of 1.73 V and a current of 0.07 mA recorded for a period of one hour. The power generated was enough to light a 6.25 mW LED bulb of 25 mA across a 100 Ω resister. Therefore, untreated sewage produced more power in MFCs with aluminium/carbon electrodes compared to the other tested materials.

Keywords: Aluminium electrodes, charcoal electrode, alternative energy source, wastewater

Effects of Climate Change, Land Use and Land Cover Variability on Green and Blue Water in Wami/Ruvu Basin, Tanzania

Benson HM Lazaro, Martine M Hagai, Rubhera RAM Mato — Fri, 31 Mar 2023 00:00:00 +0000

Water basins are the primary food sources, giving green water and blue water worldwide. Despite the basins’ potential, information on the periodical variations in blue water and green water is sparse, particularly in developing countries. The study specifically evaluated the changes in land use and land cover variability (LULCV), effects of land use and land cover variability on green water and blue water variations, and effects of climatic changes on green water and blue water. The evaluation involved the Enhanced Thematic Mapper and Operational Land Imager satellite images of 1990, 2000, 2010 and 2020. Image processing utilized the Soil and Water Assessment Tool (SWAT) in ArcGIS software. The land use and land cover variabilities indicated that land use supporting social-economic activities increased, while natural land cover decreased. Proportionally, blue water per annum was decreasing due to declining natural vegetation, enhanced by the increased socio-economic activities. Whereas, the increase in green water per annum was due to the increased temperatures, boosted by climate changes. Since the temperature rise is mainly uncontrolled, greenhouse farming should be encouraged for making green water more productive in agriculture and communities should be encouraged to practice environmentally friendly anthropogenic activities for sustainable green water and blue water management.

Keywords: Basin, Green water, Blue water, SWAT model, Climate change

Measurement of Solar Irradiance for Determining the Optimal Tilt Angle for Photovoltaic Panels

Gbadebo I. Olatona, Tolulope J. Fadairo — Fri, 31 Mar 2023 00:00:00 +0000

Solar panel installers have challenges with the tilting angle needed to obtain optimal performance from the photovoltaic panels; hence, there is the need to determine the tilting configurations and real-time data of daily values of solar irradiance with respect to photovoltaic panel performance. The performances of two 150 W panels under varied conditions of temperature and solar irradiance on a plane at two different heights (1 m and 11.5 m) from the ground surface were determined to find the effects of tilt angle and altitude on their performances. To determine the optimal tilt angle in the location; measurements of solar irradiance, temperature, open-circuit voltage, and short circuit current were made at various tilt angles and compared to one another based on the measured irradiance. The optimal tilt angle at the experimental site, 15°SW, is a function of temperature and height. At 11.5 m, the voltage dropped by 4.44% compared to the panel mounted at 1 m. The performance of a photovoltaic panel solely depends on the tilt angles relative to the height at which the panel is mounted.

Keywords: Solar, Irradiance, Photovoltaic, Panels, Tilt angle