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A mathematical model for fall armyworm management on maize biomass
Get PDFThis research article published by Springer Nature, 2021Fall armyworm (Spodoptera frugiperda), a highly destructive and fast spreading agricultural pest native to North and South America, poses a real threat to global food security. In this paper, to explore the dynamics and implications of fall armyworm outbreak in a field of maize biomass, we propose a new dynamical system for maize biomass and fall armyworm interaction via Caputo fractional-order operator, which is not only a nonlocal operator but also contains all characteristics concerned with memory of the dynamical system. We define the basic reproduction number, which represents the average number of newborns produced by one individual female moth during its life span. We establish that the basic reproduction number is a threshold quantity, which determines persistence and extinction of the pest. Finally, we simulate the Caputo system using the Adam–Bashforth–Moulton method to illustrate the main results
Integrated constructed wetlands treating industrial wastewater from seed production
Get PDFThis research article published by IWA Publishing, 2021The performance of an integrated wastewater treatment system composed of horizontal subsurface flow constructed wetland (HSSFCW), floating constructed wetland (FCW), and anaerobic baffled reactor (ABR) was studied for pollutant removal from seed production wastewater. Cyperus alternifolius (Umbrella Papyrus) plants were used in the HSSFCW, and Vetiveria zizanioides (Vetiver grass) in the FCW. The ABR was fed with 25 m3/d wastewater from its equalization tank. The average raw wastewater organic loading rate was 0.208 kg-COD/d. Grab wastewater samples were collected twice weekly for three months from each unit's inlet and outlet. The system's performance in removing biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), turbidity, nitrate, phosphate, and ammonium was studied. The average removal efficiencies obtained were 95.5% BOD5, 94.6% COD, 86.2% TSS, 76.6% turbidity, 82.4% nitrate, 76% phosphate, and 32.9% ammonium. The results show that integrating ABR, HSSFCW, and FCW improves pollutant removal from seed production wastewater, and the treated water can be used for agricultural purposes
Effect of lactic acid fermentation of watermelon juice on its sensory acceptability and volatile compounds.
Get PDFThis research article published by Elsevier Ltd., 2021Fermentation increases food shelf-life but is characterized by changes that affect product's perception. Watermelon juice was fermented with Lactobacillus plantarum (WJ-LP), L. rhamnosus (WJ-LR), L. casei (WJ-LC), L. brevis (WJ-LB) and Pediococcus pentosaceus (WJ-PP). Their sensory characteristics and volatile compounds were investigated by consumers and Headspace Solid Phase Microextraction integrated with Gas Chromatography-Mass Spectrometry, respectively. WJ-PP and WJ-LB were most liked and perceived with 'watermelon-flavor', 'natural taste', 'sweet' and 'watermelon-color' while WJ-LC, WJ-LP and WJ-LR were least liked and perceived as 'sour', 'bitter', 'off-flavor', 'aftertaste' and 'intense-flavor'. Fifty-four volatiles were identified. After fermentation, alcohols, ketones, monoterpenes, acids, and furans increased while aldehydes and alkanes decreased. Lactic acid fermentation introduced 4-decanone and 2,3-butanedione in WJ-LB, WJ-LC, WJ-LP and WJ-LR, however, heptanal, 2-heptenal, 2,6-nonadienal, 2-decenal, and 2,4-decadienal in WJ-LC, heptanal, 2-hexenal, 2-heptenal, 2,6-nonadienal, 2-decenal and octanal in WJ-LR and 2,6-dimethyl-2,6-octadiene in WJ-LP disappeared. Juice sensory profiles were associated with their volatile compounds
Phytochemical analysis and in vitro antifungal evaluation of Jatropha curcas against Late Leaf Spot disease on groundnut
Get PDFThis research article published by the Journal of Animal & Plant Sciences, Vol.47, 2021This study was done to evaluate the antifungal efficacy of Jatropha curcas leaf extracts against
groundnut late leaf spot disease caused by Phaeosariopsis personata (P. personata) and
identify their bioactive compounds responsible for antifungal effects. Jatropha curcas leaves
extracted sequentially through chloroform, ethyl acetate and methanol solvents were
evaluated against the mycelial growth of P. personata by food poisoning method. About 0.1,
0.25 or 0.5 mg/ml (plant extract/water) of each extract were mixed in molten PDA poured
into Petri dishes. Thereafter solidified amended PDA with extracts was kept at room
temperature for 24 hours. A seven-day-old fungal plug (4mm diameter) of P. personata was
plated at the middle of the Petri dishes in triplicates. Inoculation on PDA plates amended
with fungicide Chlorothalonil (720g/L) or water was included as positive and negative control
respectively. The results proved that J. curcas leaf extracts possessed fungicidal properties
since they inhibited the growth of P. personata. Moreover the antifungal effect of J. curcas
leaf extracts increased as concentration increased. Moreover, J. curcas leaf extracts highly
inhibited mycelial growth by (85.78%) similar to standard fungicide (chlorothalonil) (88.37%)
in this experiment. The presence of important compounds found in J. curcas leaf extracts by
GC-MS supported their ability against P. personata pathogen. Among the major compounds
identified with antifungal activity were hexadecanoic acid methyl ester, hexadecanoic acid
ethyl ester, hexadecane, n-hexadecanoic acid, octadecanoic acid ethyl ester, phytol and 9, 12-
octadecadienoic acid (Z,Z)-methyl ester. The potentiality of J. curcas extracts in managing
groundnut late leaf spot disease was confirmed by their ability to inhibit the growth of P.
personata and possession of important phytochemical compounds
Integrated Capacitive Deionization and Humidification-Dehumidification System for Brackish Water Desalination
Get PDFThis research article published by MDPI, 2021A hybrid capacitive deionization and humidification-dehumidification (CDI–HDH) desalination system is theoretically investigated for the desalination of brackish water. The CDI system
works with two basic operations: adsorption and regeneration. During adsorption, water is desalted,
and during the regeneration process the ions from electrodes are detached and flow out as wastewater,
which is higher in salt concentration. This wastewater still contains water but cannot be treated
again via the CDI unit because CDI cannot treat higher-salinity waters. The discarding of wastewater
from CDI is not a good option, since every drop of water is precious. Therefore, CDI wastewater
is treated using waste heat in a process that is less sensitive to high salt concentrations, such as
humidification-dehumidification (HDH) desalination. Therefore, in this study, CDI wastewater was
treated using the HDH system. Using the combined system (CDI–HDH), this study theoretically
investigated brackish water of various salt concentrations and flow rates at the CDI inlet. A maximum distillate of 1079 L/day was achieved from the combined system and the highest recovery rate
achieved was 24.90% from the HDH unit. Additionally, two renewable energy sources with novel
ideas are recommended to power the CDI–HDH system
Characterization of rhizobacteria and their formulation into biofertilizers for potato (solanum tuberosum l.) growth promotion in Tanzania
Get PDFA Thesis Submitted in Fulfillment of the Requirements for the Degree of Doctor of
Philosophy in Life Sciences of the Nelson Mandela African Institution of Science and
TechnologyRhizobacteria and their plant growth-promoting (PGP activities have widely been investigated as
biofertilizers for many crops but rarely for the potato (Solanum tuberosum L.). In the present
study, potato-grown soils from three agro-ecological zones in Tanzania were sampled,
characterized, and a total of 145 rhizobacteria isolated from them. The isolates were screened in
vitro for PGP activities like nutrients solubilization, nitrogen fixation, and phytohormones
production, and 52 most-promising isolates were characterized and identified by 16S-rRNA
sequencing. Their effects on pot-grown potatoes were evaluated against non-inoculated plants as
controls. Klebsiella grimontii MPUS7, Serratia marcescens NGAS9, and Citrobacter freundii
LUTT5 were selected based on their effects on pot-grown potatoes and formulated in different
carrier materials as possible biofertilizers. Their shelf lives were determined as colony-forming
units (CFU) under refrigerated (8
o
C) and room conditions (25 ± 2
o
C) for eight months and their
effects on field-grown potatoes evaluated against recommended fertilizers and non-treated
plants. Data analysis involved XLSTAT (2.3). Significant differences (p ≤ 0.05) were evident for
the fertility-related properties of the sampled soils but not their nutrient contents. Though slightly
acidic (pH < 6.5), non-saline (Electrical conductivity < 1 dS m
-1
), and greater proportions of silt
+ clay (average 46.85 ± 15.18%) than gravel and sand, the soils contained low nutrient levels
which may not be ideal for potato production. The rhizobacteria significantly differed in their invitro
PGP
activities.
Except
for
the
number
of
days
to
emergence
and
flowering,
rhizosphere
soil
pH,
and salinity, potato growth-related parameters like tuber numbers, sizes, weights, and
nutrient contents were enhanced by the rhizobacterial treatments in the screen house by up to
90%. The PM-1 formulation supported the maximum K. grimontii MPUS7 growth (5.3 log-CFU
g
-1
) under refrigeration and C. freundii LUTT5 (4.1 log-CFU g
-1
) under refrigerated and room
conditions but the highest K. grimontii MPUS7 population (3.7 log-CFU g
-1
) was realized in
room-stored PM-4. The formulations also showed varied activities at enhancing potato growth
and most had similar or greater effects on potato growth as the artificial fertilizers and can
effectively be used to replace the use of synthetic fertilizers in potato production systems in
Tanzania
Anthropogenic disturbance and chimpanzee (pan troglodytes) habitat use in the Masito-Ugalla ecosystem, Tanzania
Get PDFA Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of
Master’s in Life Sciences of the Nelson Mandela African Institution of Science and
TechnologyThe habitat quality of chimpanzee (Pan troglodytes), including the availability of food and
nesting resources, is important to ensure the long-term survival of chimpanzees. Botanical
composition of vegetation is spatially variable and depends on numerous biotic and abiotic
factors. There are few data regarding the availability of chimpanzee plant food and nesting
species in the Masito-Ugalla ecosystem (MUE), and how these resources vary with human
disturbance. It was hypothesized that chimpanzee plant food species richness, diversity, and
abundance, decline with increasing disturbance. Further, it was predicted that chimpanzee
abundance and habitat use is influenced negatively by disturbance. Published literature from
Issa Valley, Gombe, and Mahale Mountains National Parks, was used to document plant
species consumed by chimpanzees, and quantify their richness, diversity, and abundance,
along 32 transects totaling 63.8 km in length across four sites of varying human disturbance in
MUE. A total of 102 plant food species was documented and found significant differences in
their species richness (H = 55.09, P < 0.001) and diversity (H = 36.81, P < 0.001) across
disturbance levels. Chimpanzees built nests in 17 tree species. The abundance of nesting tree
species did not vary across survey sites (H = 0.279, P > 0.964). The least disturbed site
exhibited the highest encounter rate of chimpanzee nests km
-1
, with rates declining towards
the highly disturbed sites. Thus, severe anthropogenic disturbance in MUE is associated with
the loss of chimpanzee plant food species and negatively influences chimpanzee habitat use, a
relationship that threatens the future of all chimpanzee populations outside national parks
Integrated Mobile Application Based on Machine Learning for East Africa Stock Market
Get PDFThis research article published by Veritas Publications LTD, 2021Regional Integration refers to the process of states coming together to sign agreements where they agree to cooperate in certain areas common to them. The East African Community (EAC) which was founded on November 30, 1999, identified three integration pillars; common Market protocol, customs union and political federation. In attempt to achieve the named pillars, financial markets have been identified as a key driver for common market and customs union. The challenge however is that the East African countries run the most expensive stocks on the African Continent and this has greatly influenced trade volumes and investor appetite. When these markets are integrated it allows collective bargaining thereby increasing their market share across the region other than a given country running its own exchange. This paper presents a software platform that will enable an investor to purchase and sell stocks irrespective of any location in the East African Region thus spur the development of stock market in terms of volume and competitiveness
Groundwater recharge estimation and quality on the southern slopes of mount Kilimanjaro, Tanzania
Get PDFA Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of
Master’s in Hydrology and Water Resource Engineering of the Nelson Mandela African
Institution of Science and TechnologyThis study was undertaken to estimate groundwater recharge rates using three methods (water
table fluctuation (WTF), chloride mass balance (CMB) and soil moisture balance (SMB), as
well as assessing the impact use of the pesticides and fertilizers on groundwater quality in a
Kahe catchment located on the Southern slope of Mt. Kilimanjaro, Tanzania. The estimated
recharge rates of the WTF method yielded a higher value of about 248.4 million m
3
/year,
whereas that of CMB and SMB methods was 156.0 and 132.1 million m
3
/year, respectively.
The concentration of pesticide residues was below the detection limit, while, NO
3
-
levels of
sampled groundwater were averaged about 18.40 ± 4 and 7.6 ± 1.7 mg/l in the wet and dry
season, respectively. An elevated level of nitrate (NO
3
-
), sulfate (SO
4
2-
), phosphate (PO
4
3-
),
and ammonium (NH
4
+
) was found nearby the large-scale sugarcane farms. Generally, the
groundwater chemistry was dominated by magnesium-sodium-bicarbonate (Mg-Na-HCO
3
)
water type. The cations levels were in the trend of Mg
2+
> Na
+
> Ca
2+
> K
+
, whereas anions
were HCO
3
-
> Cl
-
> SO
4
2-
for both seasons. The heavy metals concentration of Pb, Cd, Fe,
Mn, Zn and Cu for both seasons were averaged approximately 0.08 ± 0.03, 0.11 ± 0.03, 0.16
± 0.02, 0.11 ± 0.01, 0.46 ± 0.05 and 0.55 ± 0.02 mg/l, respectively. Whereas the
concentration was higher in shallow groundwater than deep boreholes and most of them were
located around the western-eastern zone of the Kahe catchment. The findings from this study
provided reliable data information for future monitoring programs of groundwater resources
management in Kahe catchment, Tanzania
African Swine Fever Virus (ASFV): Biology, Genomics and Genotypes Circulating in Sub-Saharan Africa
Get PDFThis research article published by MDPI, 2021African swine fever (ASF) is a highly infectious and fatal haemorrhagic disease of pigs
that is caused by a complex DNA virus of the genus Asfivirus and Asfarviridae African suids family.
The disease is among the most devastating pig diseases worldwide including Africa. Although
the disease was first reported in the 19th century, it has continued to spread in Africa and other
parts of the world. Globally, the rising demand for pork and concomitant increase in transboundary
movements of pigs and pork products is likely to increase the risk of transmission and spread of ASF
and pose a major challenge to the pig industry. Different genotypes of the ASF virus (ASFV) with
varying virulence have been associated with different outbreaks in several countries in sub-Saharan
Africa (SSA) and worldwide, and understanding genotype circulation will be important for ASF
prevention and control strategies. ASFV genotypes unique to Africa have also been reported in SSA.
This review briefly recounts the biology, genomics and genotyping of ASFV and provides an account
of the different genotypes circulating in SSA. The review also highlights prevention, control and
progress on vaccine development and identifies gaps in knowledge of ASFV genotype circulation in
SSA that need to be addressed