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Modelling the spread and control of prosopis juliflora plants
Get PDFA Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of
Master’s in Mathematical and Computer Sciences and Engineering of the Nelson
Mandela African Institution of Science and TechnologyThe Prosopis julifrola plant is a thorny leguminous shrub or small tree, a kind of mesquite in a
family of Fabacea. It is extremely aggressive and invasive. The spreading agents include livestock
dispersal and seeds in their droppings, human activity by vegetation restoration, firewood and
charcoal and soil erosion control. In this study a deterministic model examines the dynamics of
Prosopis juliflora plant by adopting a similar approach of a dynamical system as used in
epidemiological modeling. The local and global stability analyses of the equilibrium points of the
model were conducted by using next generation matrix for the computation of basic reproduction
number R0 and Lypunov function. The study showed that the Prosopis juliflora plant free
equilibrium of the model is both locally and globally asymptotically stable if and only if the
number of secondary infections is less than unity, that is if R0 < 1. Furthermore, the study shows
that there exists Prosopis juliflora endemic equilibrium for the spread of the plant when R0> 1.
The numerical simulation was implemented in MATLAB ODE 45 algorithm for solving linear
ordinary differential equations. The study showed that the plant spread with an increase of animals
that ingested it. Based on the study, recommended is the application of the model on the endemic
area to improve the existing situation through: Enlightening and involving policymakers,
environmentalists, stakeholders and community groups in the preservation framework on the
spread and control strategy of the Prosopis juliflora invasio
Assessing intensification options of common bean cultivation to improve food security on smallholder farms in the Northern Highlands of Tanzania
Get PDFA Thesis Submitted in Fulfilment of the Requirements for the Degree of Doctor
of Philosophy in Life Sciences of the Nelson Mandela African Institution of
Science and TechnologyComplementarities of common bean (Phaseolus vulgaris L.) with non-legume food crops and
their significances to the agricultural systems are underexploited. Based on the description of
this study, eight options were assessed for the sustainable intensification of common bean
cultivation (through manipulations of intercropping and rotation) against the monocultures of
maize (Zea mays L.), and the improved and local varieties of common bean in the northern
highlands of Tanzania. The factors assessed were the cropping seasons/years (S) (2015 to
2017), agro-ecological zones (A) above sea level (lower 843 m, middle 1051 m, upper 1743
m), cropping systems (C) (sole, intercrop, rotation), and bean varieties (V) (improved
Lyamungu 90 and local Mkanamna) and their interactions. Results indicated that S, A, C, and
S×A, S×C, S×A×C were significant and bean grain yields increased in intercrops ranging
from 1.5 to 2.9 t ha-1 with land equivalent ratio (LER) of 1.58. Intercropping over five
cropping seasons indicated that with S×V grain yields increased from 0.2 to 3.5 t ha-1
in bean
and from 2.3 to 2.6 t ha-1
in maize with LERs of 1.48 and 1.55. In rotations, higher bean grain
yields were attributed to S (3.3 t ha-1
), C (3.4 t ha-1
), and V (2.7 t ha-1
) and for maize were in C
(2.9 t ha-1
) and S (2.6 t ha-1
). In conclusion, out of eight assessed options, this study found two
main useful options for improving food security on smallholder farms in the northern
highlands of Tanzania. The options were continuous cultivation of the improved and/or local
varieties of common bean in intercrops with the maize throughout two rainy seasons of the
year (long and short). Another option was cultivation of the improved and/or local varieties of
common bean intercropped with maize in the long rainy season and rotating of these
intercrops with the maize cultivated in the short rainy seasons. Importantly, the improved
bean variety Lyamungu 90 was heavier in weight, using the same number of seeds, than the
local bean variety Mkanamna, which provided additional factors to be considered to improve
income where weight is the acceptable standard in the market
Antimicrobial investigation of Tephrosia Vogelii hook.f from Hai District in Tanzania towards development of antifungal agents for topical application
Get PDFA Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of
Doctor of Philosophy in Life Sciences of the Nelson Mandela African Institution of
Science and TechnologyInfectious diseases such as fungal diseases are the global health problem. Moreover,
antimicrobial resistance to modern fungicides and antibiotics is even perplexing in the health
settings. Such situation needs serious attention to search for alternative antimicrobial agents.
Thus, this study aimed to investigate antimicrobial activity of Tephrosia vogelii Hook.f found
in Tanzania and develop antifungal agents therefrom. The n-hexane, dichloromethane and
methanolic extracts from leaves and roots of Tephrosia vogelii were evaluated for
antimicrobial activity against Candida albicans (ATCC 90028), Cryptococcus neoformans
(clinical isolate), Staphylococcus aureus (ATCC25923), Escherichia coli (ATCC29953),
Klebsiella pneumoniae (ATCC 700603) and Salmonella typhi (NCTC 8385). A serial dilution
method using the sterilized 96 wells of polystyrene microliter plates were used to determine
the minimum inhibitory concentrations (MIC) of extracts. The in vivo toxicity of methanolic
leaf and root extracts was evaluated using albino rats. Extracts doses of 600, 1200, 2000 and
5000 mg/kg body weight were evaluated for lethality test while doses of 600, 1200 and 2000
mg/kg body weight subjected for sub-acute toxicity test. Gas Chromatography-Mass
Spectrometry (GC-MS) technique was employed to appraise phytochemical compounds
present. Antifungal agent for topical application was formulated and evaluated through in
vitro and in vivo test to establish its effectiveness. The study results revealed that n-hexane
and dichloromethane extracts exhibited the lowest activity. Equally, methanolic root and leaf
extracts exhibited high activity at MICs ranging from 0.625 - 5.0 mg/mL against assayed
pathogens. Phytochemical screening of both methanolic leaf and root extracts revealed the
presence of tannins, flavonoids, terpenes, fatty acids and saponins. The GC-MS analysis
unveiled the presence of ten phytocompounds. Five compounds; demethylmunduserone
sumatrol, munduserone, hexadecanoic acid and hexadecanoic acid, methyl ester are new and
this is the first time to be reported from Tephrosia vogelii. Furthermore, toxicity evaluation
revealed that methanolic leaf and root extracts of Tephrosia vogelii were not deleterious at
highest dose of 5000 mg/kg body weight. Though there was no mortality recorded,
histopathological examination revealed toxicity indices due to vacuolation and necrosis in
hepatocytes under treatment of methanolic root extracts of dose 2000 mg/kg body weight.
The herbal cream prototype (CBTV3) was formulated, and it exhibited antimicrobial activity
through in vitro and in vivo tests. The development of herbal cream prototype from Tephrosia
vogelii Hook.f is hereby reported for the first time
Perceptions and experiences of community-networks that facilitate engagement in health research: Ifakara Health Institute-Bagamoyo case-study
Get PDFA Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of
Master of Science in Public Health Research of the Nelson Mandela African Institution
of Science and TechnologyInvolvement of communities in the field of health research collectively known as community
engagement is considered as ethical conduct of research. At the Ifakara Health Research
Institute (IHI) in Bagamoyo, Tanzania, nothing has been documented on how the engagement
is being done and what community structures/networks are involved in the facilitation of
engagement activities, and what are the systematic functioning of these structures since the
formulation of community advisory board (CAB) in 2007. In this study six focus group
discussions (FGDs) and 19 in-depth interviews (IDIs) among respondents participated in IHI research
for the past five years were performed. Furthermore, focus groups and in-depths interview were
audiotaped, transcribed, and analyzed using framework analysis techniques. This study found that;
engagement was more likely being influenced by the type of research project and kind of
participants needed, different community networks such as village executive officers,
community health workers, hamlet leaders, and community advisory boards were the key
stakeholders and; community-level public meetings, household visitation and informationgiving
sessions at the health facilities were the main approaches used during engagement
processes. However, it was found that they did not reach most of the target people due to
limited levels of interaction with potential participants, there are no central coordination of the
engagement activities at the Institute, different research projects at the same Institute have
been approaching these structures separately, little engagement, misunderstanding of the
research objectives have been reported in contributing to the participants dropout. This study
recommends that there is a need of developing a community engagement unit that would work
across projects to support engagement with the community
Genome scan for signatures of adaptive evolution in wild African goat (capra nubiana)
Get PDFA Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of
Doctor of Philosophy in Life Sciences of the Nelson Mandela African Institution of
Science and TechnologyNubian ibex (Capra nubiana) is a wild goat species inhabiting the Sahara and Arabia deserts. C.
nubiana thrives well in its habitat which is characterized by intense solar radiation, high
temperatures, little feed, and water supply. The genetic basis of C. nubiana adaptation to its
environment remains unknown. Adaptive signatures of evolution in C. nubiana genome were
investigated using comparative genomics approaches. Paired-end sequence reads of three C.
nubiana individuals and other publicly available genome data were used for comparative genomic
analysis. Positive selection signals were detected from sequence alignment by comparing the rates
of synonymous versus non-synonymous substitutions (dN/dS) in orthologous protein-coding
genes shared by C. nubiana and related species using CodeML program in PAML package. Copy
number variations were detected from the sequence data using read-depth method, with the
domestic goat genome data acting as the reference. Genes involved in the skin barrier and hair
follicle development, such as ATP binding cassette subfamily A member 12 and UV stimulated
scaffold protein A, were found to be positively selected, suggesting that C. nubiana has evolved
adaptive mechanisms to cope with solar radiation and temperature extremes in its environment.
Additionally, a DNA repair gene (UV stimulated scaffold protein A) was reported to be under
strong selection signals, further supporting the assertion that C. nubiana has acquired adaptive
mechanisms to deal with possible DNA damages induced by prolonged exposure to solar
radiation. Similarly, duplications of viral response genes such as UL16 binding protein 3, Cluster
of Differentiation 48, Natural Killer Group 2D ligand 1-like, Bactericidal/permeability-increasing
fold containing family A, member 1, and Natural Killer Group 2D ligand 4-like were reported
in C. nubiana, indicating that it has acquired adaptive strategies to cope with viral stressors in its
environment. Additionally, xenobiotic compounds metabolism genes involved in
biotransformation (Cytochrome P450 2D6, carboxylesterase 1 and cytochrome P450 family 2
subfamily B member 6), conjugation (UDP Glucuronosyltransferase-2B7 and Glutathione S transferase Mu 4), and transport (Multidrug resistance protein 4) of toxic compounds were found
to be expanded in C. nubiana, suggesting possible adaptative mechanisms to desert diets that are
affluent in toxic compounds. This work represents the first effort to understand the genomic of
adaptations in C. nubiana, a wild African goat. The C. nubiana genomic information generated in
this study is an important resource for researchers seeking to find genes of interest for breeding
purposes among small ruminants of economic importance
Impact of invasive alien plants Gutenbergia cordifolia and Tagetes minuta on native taxa in the Ngorongoro crater, Tanzania
Get PDFThis research article published by Elsevier, 2021Understanding the ecological impacts of invasive plant species on the native communities and identifying native plant species that co-exist with invasive plants are important for planning the effective control and restoration of invaded rangelands. Systematic random sampling technique was applied to assess the effect of the two invasive plants (Gutenbergia cordifolia and Tagetes minuta) on native vascular plant species’ cover and diversity as well as identification of native grasses that co-exist well with the two invasive plants in the Ngorongoro crater, Tanzania. Native species ground cover in lowly invaded quadrats doubled that of medium and highly invaded quadrats. The mean height of native plants in highly invaded areas doubled the height of native plants in lowly invaded areas. While species richness was higher in both G. cordifolia and T. minuta lowly invaded quadrats compared to quadrats that were under medium and high invasion similarly, lowly invaded quadrats had higher species evenness than both medium and highly invaded quadrats. Cynodon dactylon was the most co-existing native grass with both G. cordifolia and T. minuta followed by Chloris pycnothrix. The results highlights how invasive plants G. cordifolia and T. minuta drastically changed the abundance and richness of the native vascular plant community within the Ngorongoro crater. It also highlighted on presence of native grasses that are capable of co-existing with the two invasive plants. This study further generated a baseline information for long term research to elucidate mechanisms associated with the two invasive plants interactions, while at the same time informing the management authorities on the threats to native plant species associated with invasive plants G. cordifolia and T. minuta
Toxic metals in East African agro-ecosystems: Key risks for sustainable food production
Get PDFThis research article published by Elsevier B.V, 2021The dramatic increase in world population underpins current escalating food demand, which
requires increased productivity in the available arable land through agricultural intensification.
Agricultural intensification involves increased agrochemicals use to increase land productivity.
Increased uses of agrochemicals pose environmental and ecological risks such as contamination
and water eutrophication. Consequently, toxic metals accumulate in plant products, thus entering
the food chain leading to health concerns. To achieve this study, secondary data from peerreviewed
papers,
universities,
and
government
authorities
were
collected
from
a
public
database
using
Tanzania as a case study. Data from Science Direct, Web of Science, and other internet
sources were gathered using specific keywords such as nutrient saturation and losses, water
eutrophication, potentially toxic metal (PTEs), and impact of toxic metals on soils, water, and food
safety. The reported toxic metal concentrations in agro-ecosystem worldwide are linked to
agricultural intensification, mining, and urbanization. Statistical analysis of secondary data
collected from East African agro-ecosystem had wide range of toxic metals concentration such as;
mercury (0.001–11.0 mg Hg/kg), copper (0.14–312 mg Cu/kg), cadmium (0.02–13.8 mg Cd/kg),
zinc (0.27–19.30 mg Zn/kg), lead (0.75–51.7 mg Pb/kg) and chromium (19.14–34.9 mg Cr/kg). In
some cases, metal concentrations were above the FAO/WHO maximum permissible limits for soil
health. To achieve high agricultural productivity and environmental safety, key research-informed
policy needs are proposed: (i) development of regulatory guidelines for agrochemicals uses, (ii)
establishment of agro-environmental quality indicators for soils and water assessment to monitor
agro-ecosystem quality changes, and (iii) adoption of best farming practices such as split
fertilization, cover cropping, reduced tillage, drip irrigation to ensure crop productivity and agroecosystem
sustainability. Therefore, robust and representative evaluation of current soil
contamination status, sources, and processes leading to pollution are paramount. To achieve safe
and sustainable food production, management of potential toxic metal in agro-ecosystems is vital
Effects of livestock browsing and illegal harvesting on natural regeneration and ecology of balanites aegyptiaca in dinder biosphere reserve, Sudan
Get PDFA Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy in Life Sciences of the Nelson Mandela African Institution of Science and TechnologyLivestock browsing, and illegal harvesting often influence natural woodlands, rangelands, and
biosphere reserves. However, the resulting tree species diversity, composition, and population
structure have rarely been quantified. This study explored the status of tree diversity,
composition, and the growth of Balanites aegyptiaca, across 100 sample plots of 25 m x 40 m at
disturbed and non-disturbed sites in Dinder Biosphere Reserve, Sudan (DBR). The dendrometric
parameters of B. aegyptiaca, fruit production, and the soil-chemical properties were also assessed
in the same sample plots. Moreover, to examine the response of B. aegyptiaca seedlings and
saplings to livestock browsing, the study used a stratified sampling design with four sites been
browsed by goats, cattle, camels, and control, respectively. The study data was collected over
two years from January 2019 to January 2021. It was observed that non-disturbed sites had
double tree diversity than that of disturbed ones (T = 32.6, p < 0.001), and their seedlings and
saplings constituted more than 70% of the entire population (F2,48 = 116.4, p = 0.034; F2,48 =
163.2, p = 0.021, respectively). The soil nitrogen and phosphorus contents beneath trees in non disturbed sites were almost double that of those in the disturbed site (F1, 196 = 68.1, p < 0.001; F1,
196 = 97.9, p < 0.001, respectively) while sodium and electrical conductivity were by about 50%
lower (F1, 196 = 535.8, p < 0.001; F1, 196 = 16.1, p < 0.001, respectively). Mortalities of seedlings
under goat browsing were four times higher than that under camel browsing and control and
twice as high than under cattle browsing (F3,196 = 100.39, p < 0.001). Sapling mortality was three
times higher under goat browsing compared to cattle and control (F3,196 = 73.4, p < 0.001). The
study found that seedlings recover better than saplings, and, unexpectedly, goat browsing
severely affected the natural regeneration of B. aegyptiaca in DBR. Illegal harvesting in DBR
severely reduced tree structure and recruitment parameters of B. aegyptiaca, which might also
impact soil fertility. Intensive monitoring and awareness-raising programs are urgently needed to
conserve this vulnerable tree species
Strength and Durability Properties of Concrete Containing Pumice and Scoria as Supplementary Cementitious Material
Get PDFThis research article was published by Hindawi, 2021Concrete structures suffer serious deterioration under a corrosive environment. Consequently, the service life of these concrete
structures is decreased and deteriorates under combined attack of sulphate and chlorides. Most studies confined on single
deteriorating factor such as sulphate attack only or chloride attack only but the current study focused on the influence of natural
pumice (NP) and natural scoria (NS) on the strength performance of concrete exposed to the combined attack of sulphate and
chloride. Portland cement (PLC) was replaced with NP or NS at a substitution level of 10%. Concrete samples were cured in water
for the curing period of 28 days. Afterwards, the specimens were immersed in 5% sodium sulphate (Na2SO4), 5% sodium chloride
(NaCl), and combined sodium sulphate and chloride solutions for additional curing of 28, 56, and 90 days. /e results were
compared between concrete mixes with NP or NS and control mix (CT) with PLC. /e effects of sulphate, chloride, and combined
sulphate and chloride were evaluated in terms of change in weight, variation in compressive strength, and degree of damage.
Conclusively, the application of NP and NS has extraordinary potential to be utilized as a cementitious material in concrete to
increase the resistance against aggressive salts
Investigation of metallic iron for water defluoridation
Get PDFA Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Master’s in Environmental Science and Engineering of the Nelson Mandela African Institution of Science and TechnologyFluorosis is a significant ailment that affects millions of humans and animals, especially in low income countries. It has been the focus of past and present scientific endeavours to research and
develop efficient and deployable technologies, especially in these low-income communities. In
this work, metallic Iron (Fe0
) is a promising technology, and its filters have successfully
addressed both safe drinking water and sanitation and are frugal. The recalled science of Fe0
filters is demonstrated with the lingering design investigations. This study aimed at the critical
assessment on defluoridation efficiencies under conventional metallic iron aqueous systems;
where at first, Fe0 materials were characterized with 1,10 Phenanthroline (Phen) in aqueous
condition, and later batch studies were realized at the laboratory scale for two days under varied
experimental conditions of: (a) 0.1 g and 1.0 g of iron mass, (b) Equimolar contamination,
23±2.0 mg/L, of co-solutes, i.e. NO3, PO4, SO4, HCO3, Cl, (c) Initial pH values of 4.5, 7.0 and
9.5, and (d) Disturbed and non-disturbed treatments. Characterization results proved the
potential of 1,10-Phenanthroline as a sole Fe0
novel and facile characterization method.
Defluoridation results revealed a maximum of 94% and 47% for quantitative (involving co precipitation, adsorption and occasionally size-exclusion remediations) and non-quantitative
(associated with adsorption as major remediation means) fluoride removal efficiencies,
respectively. Thus, a conventional metallic iron aqueous system requires incorporating
suggested nano-scale practices towards enhancing efficiency for affordable defluoridation
achievements in future continuous system designs