Master Dissertations

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Effects of soret-dufour and conjugate heating on mixed convective heat absorbing hydro-magnetic casson fluid from flat semi-infinite vertical porous plate with suction/blowing
(The University of Dodoma, 2023) Felician, Alijen
This work aims to afford the numerical analysis of Soret-Dufour and inclined magnetic field effects on conjugate heat and mass transfer of unsteady heat absorbing hydro- magnetic Casson flow across a flat semi-infinite oscillatory plate in a porous medium with chemically reaction, thermal radiation, and suction/blowing. The momentum of the oscillatory plate is treated as the linear combination of the ’sine’ and ’cosine’ functions of time. The dimensionless coupled flow guiding nonlinear PDEs of the physical model is tackled numerically by the dynamic Galerkin finite element scheme. The demeanor of the profiles of velocity, concentration and temperature due to the alterations in the flow regulating parameters are examined graphically whereas the skin friction, mass transfer and heat transfer rates are explicated by the tabular data. The research discovered that radiation, conjugate heat transfer and diffusion thermo effects build up the temperature and velocity distributions whereas heat absorption has a reverse effect. Likewise, conju- gate mass transfer and thermo-diffusion effects intensify the concentration and velocity distributions whereas chemical reactions show overturn aspects. An increased radiation absorption parameter, magnetic field inclination angle and porosity of the medium stimu- late fluid velocity whereas the Casson and magnetic parameters have the opposite impact. In the case of suction, the profiles of concentration, velocity and temperature displayed a downturn nature but for the case of blowing, it was noticed a reversal trend. Further, a comparative analysis between the current findings and existing research works in the literature demonstrates that the obtained results are exact and accurate.
Charged anisotropic quark star model via embedding
(The University of Dodoma, 2023) Mturo, Johnson
This study, presents an exact solution to the Einstein-Maxwell field equations for charged anisotropic quark stars. By employing the embedding condition and a quark equation of state, a charged quark star model that holds significant physical and astrophysical implica- tions is generated. To facilitate the analysis, a nonlinear differential equation and the field equations are transformed using the Bannerji and Durgapal transformations, which allows us to specify the metric function based on physical considerations. The analysis reveals that both gravitational potentials and matter variables are well behaved and the model sat- isfies important physical conditions, including stability, equilibrium, energy conditions, the mass-radius relationship, compactness, surface redshift, measure of anisotropy and matching.
Mixed convection hydro-magnetic thermo-diffusion flow of a dissipating Casson fluid with an inclined magnetic field past an oscillating slanted porous plate
(The University of Dodoma, 2023) Kobia, Anampiu Jackson
A finite element numerical simulation is undertaken to explore the aspects of an angled magnetic field and thermo-diffusion on the unsteady mixed convection flow of hydro- magnetic chemically reacting and dissipating Casson fluid with thermal radiation. The fluid streams across an oscillating tilted plate ingrained in a porous medium, with time-dependent variations in temperature and concentration. The coupled dimensionless partial differential equations guiding the flow along their associated initial and boundary conditions are solved by utilizing an efficient finite element method. The key parameters affecting the fluid velocity, temperature, and species concentration are comprehensively interpreted through graphical representations while the skin friction, heat transfer, and mass transfer rates are outlined via tables. The ultimate results of the study portrayed that the plate inclination angle, Casson parameter, and applied magnetic strengths are perceived to impede the fluid velocity and the local skin friction whereas the porosity parameter displays a reverse effect. The thermo-diffusion effect amplifies the fluid velocity and species concentration. The heat source and Eckert number boost the fluid velocity and temperature. Moreover, there is an upsurge in the Nusselt number with radiation parameters and time. The Sherwood number increases with the chemical reaction but it decays with the thermo-diffusion parameter. A comparative analysis between the current findings and existing research works in the literature demonstrates the results’ precision and exactitude.
Analysis of mosquito bites of certain dangerous species of mosquitoes based on geographic factors of lupiro village in Morogoro, Tanzania
(The University of Dodoma, 2023) Komba E. B.
This study aimed at analysing the bites of certain dangerous species of mosquitoes based on geographic conditions, time, temperature and humidity of Lupiro village in Morogoro, Tanzania. Secondary data were obtained from Ifakara Health Institute (IHI) for 16 nights of 4 working days per week. Polymerase Chain Reaction (PCR) was used for identification and amplification of species of Mosquitoes. The aim of the study was to identify frequency and probability distributions of different species of mosquitoes, to develop 3D nomogram contour of various dangerous mosquito species’ bites based on geographic conditions and establishing a regression model on mosquito bites with respect to time, temperature and humidity. The study findings in frequency distribution shows that various species of mosquito bites were high at night time from 06 pm to 10 pm and moderate bites were realised from 10pm to 2am. Also, mosquito bites increased from 02 am to 06 am. The findings obtained with respect to temperature indicated that the increase of mosquito bites is associated with the increase of temperature. The findings basing on humidity showed that high humidity increases the breeding conditions of mosquito and consequently the bites also increase. Based on the 3D nomogram contour it was found that where the contour is very close to each other the mosquito bites increases while where the contours are far apart then mosquito bites become low. The Generalized models with family Gaussian with link identity were used and the interpretation was based on p-values of each species of mosquito based on time of bite, temperature and humidity which was statistically significant.
Modelling transmission dynamics of Mumps infection with some Interventions
(The University of Dodoma, 2023) Kibonge, A. A.
Mumps is a viral disease caused by the mumps virus. The disease affects any age group of humans, but it is so prominent in children and adults. The current study investigates a nonlinear deterministic model of mumps transmission dynamics with double-dose vaccination, public health education campaigns, and quarantine control strategies. It is aimed to examine the role of double-dose vaccination, public health education campaigns, and quarantine in reducing disease transmission. The effective reproduction number (Re) is computed via next-generation matrix approach. Moreover, sensitivity analysis is carried through Re to study the effect of model parameters on Re. Results showed that Re is more sensitive to first-dose vaccine efficacy, proportion of vaccinated immigrants with first-dose, per capita birth rate, and transmission rate for symptomatic infectious individuals. Thus, in order to minimize mumps transmission from the community, these parameters should be closely monitored. In addition, stability analysis of DFE and EE points is performed to study the behavior of the disease. Local and global stability of the DFE point is investigated by using the Routh-Hurwitz criteria and Lyapunov function technique respectively, the results show that DFE is locally asymptotically stable if Re <1 and is globally stable if Re <1. Similarly, the global stability of the EE point is established through Lyapunov function, and results show that it is globally asymptotically stable whenever Re > 1. The numerical results of the model show that the number of mumps infections decreases when at least a single control intervention is applied efficiently. Furthermore, the findings indicate that, the most effective strategy of reducing mumps transmission in the community is the combination of three interventions namely; double-dose vaccination, public health education campaigns, and quarantines. Therefore, it is important to opt for the multiple strategy to minimize the number of mumps infections from the community.
Charged anisotropic conformal star model with a quadratic equation of state
(The University of Dodoma, 2023) Christopher, J.
A new exact solution to the Einstein-Maxwell field equations describing the properties of a charged anisotropic compact star is generated. This is achieved by combining a conformal Killing vector and a quadratic equation of state. The utilization of the conformal Killing vector resulted in an equation relating the gravitational potential functions. The quadratic equation of state is used with the Einstein-Maxwell field equations to obtain an equation for the electric field intensity. Then, one of the gravitational potentials is specified on physical grounds to obtain the second gravitational potential and matter variables. The study on charged anisotropic compact stars through merging the conformal symmetry and a quadratic equation of state is missing in the existing literature. The class of solution obtained undergoes several analysis for the acceptable physical conditions for the realistic compact star models. A comprehensive exploration of the physical aspects demonstrates the well-behaved nature of the gravitational potentials and matter variables. Smooth matching of the interior and exterior metrics is achieved at the boundary. The gravitational potentials are free from physical and geometric singularities. Furthermore, the energy conditions are satisfied, and the mass-radius ratio and surface redshifts remain within acceptable ranges. Equilibrium is also achieved with balanced physical forces. The model’s stability against gravitational collapse is also satisfied.
Statistical analysis of child labour participation determinants and impacts on reading knowledge in Tanzania
(The University of Dodoma, 2023) Mtafya, H. A.
Child labour was when a youngster works full-time to support themselves or their family, whether it is paid or unpaid. The goal of this study was to determine the factors that influence children's involvement in labour and how it affects their reading knowledge in Tanzania. The study used cross-sectional Integrated Labour Force Survey (ILFS) data obtained from the National Bureau of Statistics (NBS). Both descriptive and inferential statistics were applied in this study. A 9639 children aged 5-17 were used. Unweighted binary generalized estimating equations have been used to estimate the factors that influence child work involvement, and a multinomial logistic regression model has been used to estimate how child labour participation affects educational success. The results of the unweighted exchangeable binary generalized estimating equation model showed that the age of the child, household size, educational level of the household head, and marital status of the household head, geographic area, and employment status of the household member were all significantly correlated with the participation of children in child labour. The outcome of multinomial logistic regression revealed that every statistically significant variable that affects child labour also statistically affected the child's reading ability. The study results recommend that in order to end the issue, the government, through the Ministry of Labour and Employment and NGOs, must educate kids, families, and society on what child labour is, its risks, and how they may become involved. The government should keep educating parents about the benefits of having a small family, especially in rural areas. The Child Act of 2009 and the Employment and Labour Relations Act of 2004 need to be evaluated and put into effect by the appropriate authorities in coordination with the neighborhood.
Assessment of relative abundance, distribution and illegal killing of water birds in Usangu wetland
(The University of Dodoma, 2023) Chaula, A.
Wetlands hold about one-third of the world bird populations. However, they are threatened by socio-economic activities and hence potentially affecting a large assemblage of bird life. Usangu wetland, one of Tanzania's Important Bird Areas (IBAs), is experiencing an increase in farming and illegal killing of waterbirds activities. This study was conducted to determine the factors influencing relative abundance and distribution of water birds, drivers for illegal killing, and mapping the hotspots of water birds killing in Usangu Wetland. Transect sampling was used to determine abundance and distribution of water birds. Household survey, Focus Group Discussions (FGD) and key informants’ interviews were used to assess illegal killing drivers, where 12 species are illegal killed for household consumption and pest bird control. While participatory mapping was employed in mapping hotspots for illegal killing. Data on abundance and distribution were analyzed by t-test in STATA version 16 while illegal killing among species across study sites were analyzed by Kruskal walis and t-test using SPSS and R-Studio 4.0.3. Hotspots for illegal hunting were mapped using Q-GIS 3.2.14. A total of 34 waterbird species were recorded. The three most common abundant species were Gallinula angulata (47.56%), Dendrocygna bicolor (12.01%) and Plegadis falcinellus (10.15%) and the least common were Amaurornis flavirostra 0.01%, Scopus umbreta 0.01%. Water birds are most abundant and distributed in rice fields habitats compared to open grassland and maize farms especially during their reproductive stage of rice. A total of 12 bird species are illegally killed, and the most killed are: Gallinula angulata (66.1%), Gallinula chloropus (10.6%), Dendrocygna bicolor (6.8%), Aldea spp. (5%) and the Palearctic migrant Ciconia ciconia (3.8%). Most of illegal killing are conducted within rice fields. Rice fields was found to play a crucial function of habitat for diverse waterbirds, but has been a suicide bag from illegal killing as most cases are found in rice fields.
A queuing system model in the outpatient department of jinja regional referral hospital, Uganda
(The University of Dodoma, 2023) Kisakye, A.
This study investigated a queuing system model in the outpatient department of Jinja Regional Referral Hospital, Uganda. Primary data was obtained from JRRH for a period of one week. Observation method was used to record patient arrival times, service start times and service end times. The aim of the study was to identify a suitable distribution for arrival and service time of patients at the hospital, to identify the suitable distribution for waiting time of patients at the hospital and to compare the performance of a queueing model for arrival and service time of patients at the hospital with other existing models. The study findings showed that the Weibull and Gen. Extreme Value distribution acted as good fit for patient arrival and service time based on the AIC and BIC values. Also the findings based on waiting time showed that the Weibull distribution acted as a good fit for patient waiting time at the hospital according to the AIC and BIC values. The findings about the model showed that the G/G/3 model was the best as evidenced by the few expected number of patients in the queue which was 1 and 1, expected number of patients in the system which was 2 and 1, expected waiting time of patients in the queue 0.07minutes and 0.027 minutes and the expected waiting time of patients in the system which was 0.09 minutes and 0.005 minutes at both the registration counter and doctor’s rooms respectively. Therefore, Jinja Regional Referral Hospital might become a role model for other healthcare facilities by putting the recommendations into practice and looking into new research areas. This would improve the patient experience and the way healthcare is delivered there.
Modelling probability of loan repayment in local government authorities (LGAs): a case study of Kahama district
(The University of Dodoma, 2023) Charles, D.
As one of the strategies to eradicate poverty, the government of Tanzania introduced the programme of loan provision to Women, Youth and People with Disabilities (PWDs). Despite the good intention of the government, some of borrowers lack the willingness and the ability to make a full repayment in their loan. This affects the Local Government Authorities (LGAs) to be sustainable in loan provision for the future plan. Mainly, this study aimed at modeling the loan repayment probability in LGAs. Specifically, this study intended to determine the determinants that affect the group loan borrowers, analyze the equality of performance of group loan repayment and determine the probability of group loan repayment in the selected LGAs. The study used secondary data of 683 loan borrowers collected from Kahama Municipal Council (KMC), Ushetu District Council (UDC) and Msalala District Council (MDC). Five (5) variables namely loan amount, group location, group size, time given for repayment, and group type were used to model the probability of loan repayment using logistic regression and to analyze the determinants that affect group loan repayment using Multiple Linear Regression (MLR) model. The equality of performance of loan repayment was analyzed by the Kruskal Wallis H test. Based on logistic regression findings; the study shows that only group type (with p = 0.038 and p=0.075 for women and youth respectively as compared to PWDs), time given for repayment (with p= 0.02 for 2 years as compared to 1 year) and location of group borrowers (with p=0.082) are significantly associated with the probability of loan repayment. The probability of non-default decreases for groups from villages as compared to groups from towns. Groups with 1 year of repayment have low non-default probability than groups with 2 years of repayment. The probability of non-default is low for PWDs than for women and youth. This study recommends that in order to improve loan repayment in the study area, group borrowers should be given at least two (2) years time of loan repayment. The recommended time reduce the risk of default. The LGAs also, have to closely supervise group loan borrowers from village areas and PWDs so as to reduce the default probability from these groups.
Dft and td-dft studies of d-π-a organic dye molecules with different spacers for highly efficient reliable dye sensitized solar cells (DSSCS)
(The University of Dodoma, 2023) Malang, M. P. K.
Dye-sensitized solar cells (DSSCs) have sparked the interest of photovoltaic researchers due to their promising performance, low cost, and simple production procedure. In this study, a series of six D-π-A Organic dye molecules were design by using different π-spacers. The aim of this study was to utilize computational quantum simulations to investigate the molecular structure, absorption spectra, optical, electronic and photophysical properties of D-π-A organic dye molecules using DFT and TD-DFT computational methods. The , , energy gap ( ) and dipole moment for all dyes have been determined and discussed. The obtained results for excitation energies and the HOMO/LUMO energy level, shows an improvement in electron injection and dye regeneration processes. Furthermore, the energy gap, open-circuit voltage ( ), electron injection free energy ( ), light harvesting efficiency (LHE), and absorption spectra of all dyes were examined and indicate some improvement. The results show that D4 dye molecules have the smallest energy gap (1.505-1.709 eV and 1.396-1.545 eV for gas and solvent phases). Light harvesting efficiency was estimated, and this parameter depend on oscillator strength of dye molecules. The results suggested that D5 dye have the higher LHE (0.933 and 0.981 eV respectively) than other compounds. Therefore, the results of these dyes suggested that D4 and D5 dyes molecules are favorable candidates for DSSCs applications. The study of structural, electronics and optical properties for these compound could aid in the development of more efficient sensitizers for solar cells.
Microwave promoted graft copolymerization of poly (ethylacrylate) onto k-carrageenan for removal of selected heavy metal ions from aqueous solution
(The University of Dodoma, 2023) Moses, M.
Microwave promoted graft copolymerization of poly (ethylacrylate) onto k-carrageenan in the presence of a redox pair (potassium persulfate/ascorbic acid) led to the formation of a novel copolymer. By varying the reaction conditions such as the microwave power, reaction time, concentration of k-carrageenan, concentration of ethylacrylate, concentration of ascorbic acid and potassium persulfate concentration, copolymer samples of different grafting percentages were obtained. The copolymer sample with the highest grafting percentage was subjected to FT-IR, SEM, TGA and XRD analyses. The copolymer sample with the highest percentage of grafting was evaluated for its adsorption of Ni(II) and Cd(II) from an aqueous solution by performing batch experiments. Various adsorption parameters which include; contact time, pH, initial metal ion concentration, temperature, electrolyte strength and adsorbent dosage were varied to obtain the optimum conditions for the adsorption of metal ions. The copolymer sample was found to have high adsorption percentage at pH 8 (for Cd(II)) and pH 7 for Ni(II), temperature 35 oC { for both Cd(II) and Ni(II)}, optimum initial metal ion concentration was 100 mgL-1 and contact time of 180 min for both metal ions using 100 mg adsorbent dosage. The adsorption data obtained was studied using both Langmuir and Freundlich isotherm models. The adsorption data for both metal ions fitted with both isotherm models but a better fit was obtained with Langmuir isotherm model for both Cd(II) and Ni(II). This indicates that the copolymer surface active binding sites are heterogeneous in nature with different mechanisms of adsorption involved. Maximum adsorption capacity obtained using Langmuir isotherm model was 308.6 mgg-1 for cadmium ions and 305.8 mgg-1 for nickel ions. The adsorption of both metal ions followed pseudo second order kinetic model. The positive ΔH values endorsed the adsorption process to be endothermic in nature. The negative values of ΔG indicate the spontaneity of the adsorption process while the positive ΔS values showed that the adsorption of metal ions proceeded with increased randomness at the surface of the copolymer. High recovery percentage of the metal ions from the adsorbent indicate that the copolymer could be used for more adsorption cycles.
Antenatal care utilisation and associated factors among women of reproductive age in Tanzania
(The University of Dodoma, 2023) Mrema, M.
Antenatal care (ANC) services for pregnant women are an essential service for identification and prevention of possible maternal health risks so as to ensure better birth outcomes. This study was conducted to examine ANC utilisation and associated factors among reproductive age women in Tanzania with consideration of multiple ANC service utilisation. This study used quantitative approach using secondary data from Demographic Health Survey (DHS) database for years 2015/2016. Data analysis was done by descriptive statistics, Chi-square and log-binomial model. The results indicated an ANC prevalence of 87.7% with high government hospital(s) accessibility in which nurses were the main ANC attendants. Interestingly, in each of ANC services recommended by World Health Organisation (WHO), more than 50% women confirmed to receive each service (except family planning education/method). Likewise, the Chi-square test indicated a significant association between ANC visitation and ANC service utilisation (p<0.05). Model results show that, age group of 45-49 (aPR=0.95, 95% CI 0.88-1.09, p=0.048) is likely to significantly decrease ANC utilisation while primary level of education (aPR=1.09, 95% CI 1.03-1.18, p=0.008), secondary level of education (aPR=1.14, 95% CI 1.05-1.23, p=0.001), rich category of wealth index (aPR=1.09, 95% CI 1.03-1.15, p=0.003), urban residential place (aPR=1.09, 95% CI 1.04-1.14, p=0.001) are significantly increase ANC utilisation. On the other hand, secondary level of education (aPR=1.15, 95% CI 1.05-1.26, p=0.002), higher level of education (aPR=1.51, 95% CI 1.32-1.71, p=0.001), rich category of wealth index (aPR=1.17, 95% CI 1.09-1.24, p=0.001), private ANC centre (aPR=1.28, 95% CI 1.06-1.54, p=0.009) and religious ANC centre (aPR=1.21, 95% CI 1.04-1.40, p=0.015) were positive and significantly associated with ANC visitation. It can be argued that, education level and income status of a woman play a significant influence on both ANC service utilisation and health centre visitation. Health stakeholders in Tanzania should focus on community sensitization and economic empowerment of women so as they can access quality ANC services. The target should be to not only to make women knowledgeable on maternal health issues but also financially able to pay for ANC services as they make visitation at ANC centre(s).
Modelling socio-economic and demographic determinants of food poverty among household heads in Zanzibar
(The University of Dodoma, 2023) Harith, S. M.
In Zanzibar, food poverty among households has become a serious problem, especially in rural areas where a sizable population lives in food poverty. Food poverty among household members significantly contributes to nutritional quality, possibly leading to inadequate nutrition and posing dangers to physical, mental, and financial health. The Zanzibar Household Budget Survey of 2019-2020, which comprised 2788 household heads, was used in this study. This study's objective was to investigate the socio-economic and demographic variables that affect household heads' access to food in Zanzibar. Kilocalories from food consumption per equivalent adult were used as a proxy measure with a baseline value of 2200kc (equal to 1571.109088396 Tanzanian shillings) to evaluate the food poverty status among adults in Zanzibar. The socio-economic and demographic correlates of food poverty in Zanzibar families were identified using a designed based logistic regression model. According to the survey analysis, just 6.00% of household heads were assessed to be food insecure, while 94.00% were food secured. Household size, the level of education of the household heads, total monthly spending, the category of unemployed people, and location (urban or rural) were all significant predictors of food insecurity among household heads in Zanzibar using designed based binary logistic regression model. However, according to the multilayer perceptron neural network model, household size was the most significant predictor of food poverty. Other significant predictors included total monthly domestic spending, the employment status of household heads, and marital status. Both the multilayer perceptron neural network and the designed-based binary logistic regression model performed well. Nevertheless, the designed-based binary logistic regression model was outperformed by the multilayer perceptron neural network. The income levels and economic prospects of Zanzibar households should be improved through action. This can be done by implementing strategies that improve income and lower food insecurity, such as job development, business support, sustainable livelihoods, and vocational training. The improvement of family food security depends heavily on governmental and non-governmental organizations like the Food and Agriculture Organization (FAO) and the World Food Programme (WFP).
Cure model for end-stage chronic kidney disease patients at Benjamin Mkapa hospital, Dodoma -Tanzania
(The University of Dodoma, 2023) Amani, Z.
Cure modelling is a contemporary approach to survival analysis used when some subjects in the study never experience the event of interest. Cure models have been an area of interest and active research in the last three decades. This study used cure modelling approach for survival analysis of end-stage chronic kidney disease (CKD) at Benjamin Mkapa Hospital (BMH), Dodoma-Tanzania. The purpose of this study was to fit cure model for end stage CKD patients, to evaluate cure probabilities for end stage CKD treatments and to assess the cure probabilities due to influence of treatments’ sponsorship factor for survival of end stage CKD patients. The retrospective study was conducted from December, 2021 to June, 2018 for a follow up time of approximately 172 weeks. The cure model was fitted by using the exponentiated half-logistic as a baseline distribution. The comparison of cure rate between haemodialysis and post kidney transplant treatments status as well as the cure rate due to influence of sponsorship status of end stage CKD patients was evaluated by cured probabilities from the fitted model. The findings indicate that general cure probability for end stage CKD patients was 37% whereas the cure probabilities for health insurance sponsored and self-sponsored patients were 46% and 5.3% respectively. Self-sponsored patients were at higher risk of death than insurance sponsored-patients. Similarly, post kidney patients had 94% cure probability while haemodialysis patients had 38% cure probability. This is a call to government institutions and various health stakeholders to improve CKD awareness campaign among Tanzanians and intervene CKD treatments in order to increase longevity especially for self-sponsored end stage CKD patients. Moreover, Artificial Intelligence (AI) research should be conducted to intervene this heath challenge by innovating portable artificial kidneys for patients with end stage kidney diseases to minimize treatment’s costs and prolong their life.
Molecular design and investigation of new Donor-Acceptor-Donor (D-A-Dˈ) monomers for polymer solar cells: DFT/TD-DFT methods
(The University of Dodoma, 2022) Lyakurwa, Melchizedek
The third generation of solar cell technology employs organic materials to harvest sunlight to produce electrical energy. Bulk heterojunction solar cells (BHJ-SC) is among the efficient type of organic solar cells best known for their ability to prevent energy loss which was a problem for previous types of organic solar cells. This work was based on investigating and studying the optical and electronic properties of newly designed light-harvesting monomers. The monomers with D-A-D′ configuration incorporated two different types of donor units (triphenylamine and carbazole) and one acceptor unit (benzothiadiazole or its derivatives) was designed and studiedby DFT and TD-DFT methods in the gas and solvent phase. It was found that all the designed monomers qualify as semiconductors with an energy gap < 3 eV, with absorption characteristics in the visible and near-infrared (400nm to 900 nm) range of the solar spectrum. Changing of acceptor unit from weaker to stronger and structural modifications of donor units lead to the highest open circuit voltage of 1.5V of monomer D8 similar to the AAA batteries, the smallest band gap of 1.67 eV of monomer A7, a high wavelength of absorption 870.8nm of monomer A7 and the smallest exciton binding energy 0.228eV of monomer A8. The result pointed out the D-A-D′ configuration can be used to make potential monomers for organic solar, and from this particular work the optical and electronic properties of monomers A7, A8 and A9 show great potential to be utilized for making the light-harvesting polymer molecule for BHJ-SCs.
Bio-sorption of Congo red dye from aqueous solution using adsorbent prepared from vangueria infausta fruit pericarp
(The University of Dodoma, 2021) Kitemangu, Aisha
The adsorption efficiency of Vangueriainfausta fruit pericap in the removal of Congo red dye from aqueous solution is investigated through batch experiments. Optimum conditions for adsorption process were determined by varying parameters pH, biosorbent dosage, contact time, initial congo red concentration and temperature. The physical characterisitics of the treated and untreated biosorbent were identified using Brunauer–Emmet–Teller (BET) method. Morphology of biosorbent wasviewed using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Chemical characterisitics were determined by Fourier Transform Infaredspectrometer (FT-IR) and Energy Dispersive Xray spectrometer (EDX). Quantification of dye was carried out using Ultraviolet-Visible Spectrophotometer. For explanation of the adsorption process, Freundlich and Langmuir isotherm models were used. Pseudo-first and second order was studied for adsorption mechanism and thermodynamic studies were investigated for testing spontaneity of adsorption. Desorption studies were carried out for the regeneration of the biosorbent after use. Adsorption was effective at pH 2, biosorbent dosage of 0.7 g, 180 minutes contact time, initial dye concentration of 10 mg/L at 55℃. The adsorption efficiency for the treated and untreated biosorbentwas92.3% and 50.3% respectively. The negative values of ΔG°(-5.78, -6.57, -7.37, -8.16, -8.95, -9.74 and -10.53 kJ/mol at 25, 30, 35, 40, 45, 50, 55 ℃ respectively) shows spontaneitywhile the positive values of ΔH°(41.42 kJ/mol) and ΔS (158.32 J/mol.K) depicts that adsorption was endothermic in nature with increase in randomness of the molecules. The adsorption processwas well explained by pseudo second order kinetics and the experimental data best fitted to the Langmuir isotherm model. The results depict that, the treated adsorbent from Vangueriainfaustais more effective in the removal of Congo red dye from aqueous solution.
Determination and treatment of pesticide residues in grapes (vitis vinifera) and their supportive soil from vineyards implementing good agricultural practices in the Dodoma region
(The University of Dodoma, 2021) Mressa, Fatuma
This study describes the levels of 7 pesticide residues in untreated and treated grapes and their supporting soil using GC technique. Target compounds belongs to the organochlorine, organophosphorus and triazole groups. Sample preparation was done using acetonitrile extraction and subsequent cleanup by dispersive solid phase extraction with polymer-based sorbent. Identification and quantification of pesticide residues was done using GC-MS/MS operating in MRM mode an electron impact ionization. Average recoveries or analytes ranged between 79-105% at three fortification levels of 0.025, 0.05 and 0.1 mg/kg. Limit of detection were below 0.001 and limit o quantification was below 0.01 which were sufficiently below the maximum residue levels set by European legislation. The proposed method was applied for determination of pesticide residues in untreated and treated grape samples and their supporting soil from the selected vineyards. Treatment method used was washing with different solution such as vinegar, sodium bicarbonate, tap water and table salt(sodium chloride ) solution. Higher levels of pesticide residues were found in soil than in grape samples. Hexaconazole were detected more than the other pesticides with the concentrations up to 0.5 mg/kg and 0.6 mg/kg in soil samples. The levels of hexaconazole found in the untreated grape samples were much higher than in treated grapes and exceeding its respective MRLs (0.5 mg/kg). This means that some grapes which contain pesticides, are available on the market. This is due to lack of information reporting their presence and their effects to human and animals
Synthesis, characterization and antimicrobial evaluation of carrageenan /TiO2 nanocomposite materials
(The University of Dodma, 2021) Majinyari, Dotto Emanuel
Food loss due to spoilage by microorganisms is still a problem in most developing countries. Antimicrobial nanoparticles (NPs) can be used to make edible coatings that are subsequently applied to fruits and vegetables to increase their shelf life and improve storage quality. This study aimed to synthesize and analyze carrageenan/TiO2 nanocomposite as food additives for antimicrobial purposes. The combination of metal oxides and polysaccharides is gaining and drawing more attention. A substantial research focus has been on understanding the relationship between polysaccharides and metal oxides, aiming at mastering the pore size distribution, morphology, configuration and composition of hybrid materials. In this study, a highly crystalline anatase/rutile mixed phase carrageenan/TiO2 nanocomposite having a larger surface area has been synthesized by the sol-gel process followed by calcination at 450°C and 650°C. The nanocomposites obtained were analyzed for their functional groups and phase formation using Fourier Transform Infrared Spectroscopy (FTIR) and the X-ray Diffraction (XRD). Furthermore, the specific surface area of synthesized materials was analyzed by using Brunauer-Emmett-Teller (BET), while the surface morphology, dispersions, and elemental characteristics were done by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). FTIR spectra revealed variations in bond frequencies in the nanocomposite materials compared to their reference samples, while the XRD pattern revealed the existence of both rutile and anatase phases of titanium dioxide in the composite materials. The surface of the nanocomposite was observed to be morphologically porous by SEM, while the EDX proved the presence of titanium, oxygen and carbon elements in the composite calcined at 450°C and 650°C. The carrageenan/TiO2 nanocomposites calcined at 450°C showed excellent antibacterial activity against selected bacteria (Staphylococcus aureus and Escherichia coli). These findings suggest that the potential of carrageenan/TiO2 nanocomposites to inhibit bacteria is influenced by their crystalline nature, porosity, surface area, and small size. Its antimicrobial property makes it a promising candidate as a food additive in the food industry.
The role of solvents on conformation, aggregation and solubility behaviour of capsaicin: a molecular dynamics simulation study
(The University of Dodma, 2021) Kambaine, Naserian Daniel
Capsaicin is an alkaloid effective in pain management related to rheumatoid arthritis, osteoarthritis and many other pain-related diseases. However, its clinical applications are hampered by its poor solubility. Understanding its solution conformation at the molecular level will help explore its full potential as a therapeutic agent. In this study, using molecular dynamics (MD) simulation, the role of polar protic, polar aprotic and non-polar solvents on conformational behaviour of capsaicin, solvation free energy and aggregation behaviour of capsaicin are reported. In particular, molecular dynamics (MD) simulations of capsaicin in polar protic, polar aprotic and non-polar solvents viz; water, methanol (MeOH), dimethylsulfoxide (DMSO) and dichloromethane (DCM) were carried out to establish its stability and conformation. The structural orientation, conformation, stability and solubility of capsaicin are solvent dependent. Capsaicin is relatively more stable and soluble in DMSO than in DCM, MeOH and water. Capsaicin appears to be bent and extended in water, but only extended conformation is observed in other solvents. In both solvents, capsaicin is seen to be stable with trans-conformation; the measured dihedral angles ascertained that the conformational preference is due to rotation at ϕ = ± 1800. The calculated solvation free energy shows that capsaicin is more soluble in DMSO than in water. The aggregation properties of capsaicin in water and DMSO was further studied by varying the number of capsaicin monomers from 6 to 16. Capsaicin monomers in water tend to form clusters in an ordered fashion that tend to aggregate in parallel and antiparallel orientations of the phenyl ring with a bent shape of a hydrophobic tail as the monomers are increased from 6 to 16. Capsaicin is observed to form more aggregates in water than in DMSO. The findings of this dissertation offer atomistic insights into the function of solvents in capsaicin interaction and solubility. This effort is a part of a broader debate about other but equally important aspects of drug design, such as crystal structure growth and polymorphism of capsaicin. This will also attempt to give further understanding of capsaicin solubility difficulties.

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