Journal Articles


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    Visible light photocatalytic degradation of methylene blue and malachite green dyes with CuWO 4-GO nano composite
    (Elsevier, 2018) Medidi, S.; Markapurapu, S.; Kotupalli, M. R.; Chinnam, R. K. R.; Susarla, V. M.; Gandham, H. B.; Sanasi, P. D.
    Copper Tungstate-Graphene Oxide nano composites have been successfully applied as excellent catalysts for the photocatalytic degradation with Methylene blue and Malachite green dyes under visible light irradiation. A facile solid state metathesis synthesis of copper tungstate (CuWO4) followed by ball milling and subsequent preparation of copper tungstate-graphene oxide (CuWO4-GO) nano composite using a colloidal blending process and its application as a visible light photocatalyst for the degradation of Malachite green and Methylene blue dyes. The morphology and composition of copper tungstate (CuWO4) nano composite have been characterized using X-Ray Diffraction (XRD), UV-Visible Diffuse Reflectance Spectra (UV-DRS), Raman Spectra, Field Emission Scanning Electron Microscopy (FESEM)-EDS and UV Visible Spectroscopy. It shows a band gap value of 2.13 eV, an increase in range and intensity of light absorption and the reduction of electron-hole pair recombination in CuWO4 with the introducing of GO on to it.
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    Catalyst free One-pot synthesis of chromeno quinolines and their antibacterial activity
    (Elsevier, 2017) Vasamsetty, S.; Medidi, S.; Satyanarayana, C. C.; Sanasi, P. D.; Majji, R. K.; Kotupalli, S. R; Ampolu, S.; Nowduri, A.
    An efficient greener one pot synthesis of dimethyl-dihydro-7H-chromeno[3, 2-h]quinolin-8(9H)-one derivatives has been synthesized through cyclization of aromatic aldehyde, dimidone and 8-hydroxy-quinoline through one-pot condensation method is described. The synthesized compounds are screened for further biological activities against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis , Bacillus using cut plate method and disc diffusion method.
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    Modelling the impact of health care providers in transmission dynamics of COVID-19
    (Elsevier, 2022) Maiga, K.; Hugo, A.
    In this paper, a mathematical model is proposed and analysed to assess the impacts of health care providers in transmission dynamics of COVID-19. The stability theory of differential equations is used to examine a mathematical model. The results of both local and global stability of disease-free equilibrium points were determined by using Routh–Hurwitz criteria and Metzler matrix method which verified that was locally and globally asymptotically stable. Also, the endemic equilibrium point was determined by the Lyapunov function which showed that 𝐸∗ was globally asymptotically stable under strict conditions. The findings revealed that non-diagnosed and undetected health care providers seems to contribute to high spread of COVID-19 in a community. Also, it illustrates that an increase in the number of non-diagnostic testing rates of health care providers may result in high infection rates in the community and contaminations of hospitals’ equipment. Therefore, the particular study recommend that there is a necessity of applying early diagnostic testing to curtail the COVID-19 transmission in the health care providers’ community and reduce contaminations of hospital’s equipment.
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    Covid-19 preventive practices, psychological distress, and reported barriers to healthcare access during the pandemic among adult community members in sub-Saharan Africa: a phone survey
    (American Society of Tropical Medicine and Hygiene, 2022) Assefa, Nega; Abdullahi, Yasir Y.; Hemler, Elena C.; Lankoande, Bruno; Madzorera, Isabel; Wang, Dongqing; Ismail, Abbas; Chukwu, Angela; Workneh, Firehiwot; Mapendo, Frank; Millogo, Ourohire; Abubakari, Sulemana Watara; Febir, Lawrence Gyabaa; Lyatuu, Isaac; Dianou, Kassoum; Baernighausen, Till; Soura, Abdramane; Asante, Kwaku Poku; Smith, Emily; Vuai, Said; Worku, Alemayehu; Killewo, Japhet; Mwanyika-Sando, Mary; Berhane, Yemane; Sie, Ali; Tajudeen, Raji; Oduola, Ayo; Fawzi, Wafaie W.
    The COVID-19 pandemic has had serious negative health and economic impacts in sub-Saharan Africa. Continuous monitoring of these impacts is crucial to formulate interventions to minimize the consequences of COVID-19. This study surveyed 2,829 adults in urban and rural sites among five sub-Saharan African countries: Burkina Faso, Ethiopia, Nigeria, Tanzania, and Ghana. Participants completed a mobile phone survey that assessed self-reported sociodemographic, COVID-19 preventive practices, psychological distress, and barriers to healthcare access. A modified Poisson regression model was used to estimate adjusted prevalence ratios (aPRs) and 95% CIs to investigate potential factors related to psychological distress and barriers to reduced healthcare access. At least 15.6% of adults reported experiencing any psychological distress in the previous 2 weeks, and 10.5% reported that at least one essential healthcare service was difficult to access 2 years into the pandemic. The majority of participants reported using several COVID-19 preventive methods, with varying proportions across the sites. Participants in the urban site of Ouagadougou, Burkina Faso (aPR: 2.29; 95% CI: 1.74–3.03) and in the rural site of Kintampo, Ghana (aPR: 1.68; 95% CI: 1.21–2.34) had a higher likelihood of experiencing any psychological distress compared with those in the rural area of Nouna, Burkina Faso. Loss of employment due to COVID-19 (aPR: 1.77; 95% CI: 1.47–2.11) was also associated with an increased prevalence of psychological distress. The number of children under 5 years in the household (aPR: 1.23; 95% CI: 1.14–1.33) and participant self-reported psychological distress (aPR: 1.83; 95% CI: 1.48–2.27) were associated with an increased prevalence of reporting barriers to accessing health services, whereas wage employment (aPR: 0.67; 95% CI: 0.49–0.90) was associated with decreased prevalence of reporting barriers to accessing health services. Overall, we found a high prevalence of psychological distress and interruptions in access to healthcare services 2 years into the pandemic across five sub-Saharan African countries. Increased effort and attention should be given to addressing the negative impacts of COVID-19 on psychological distress. An equitable and collaborative approach to new and existing preventive measures for COVID-19 is crucial to limit the consequences of COVID-19 on the health of adults in sub-Saharan Africa.
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    Chemical profiling of Cannabis sativa from eleven Tanzanian regions
    (Elsevier, 2023) Mhando, H. B.; Sahini, M. G.; Makangara, J. J.
    The aim of this research was to investigate the chemical profiles of Cannabis sativa from 11 Tanzanian regions using preliminary tests as well as instrumental analyses with GC-MS and LCMS. Generally, all the seized samples tested positive for the presence of (Δ9-THC. The preliminary test with Duquenois method followed by chloroform addition revealed the presence of Δ9-tetrahydrocannabinol (Δ9-THC) in all the samples. GC-MS analyses of the samples revealed the presence of nine cannabinoids including Δ9-THC, Δ8-THC, cannabidivarol, cannabidiol, Δ9-tetrahydro cannabivarin (Δ9-THCV), cannabichromene, cannabinol, caryophyllene, and cannabicouramaronone, whereas LC-MS chemical profiling revealed the presence 24 chemical substances, including 4 cannabinoids, 15 different types of drugs and 5 amino acids. The Pwani region had the highest percentage composition of Δ9-THC (13.45%), the main psychoactive ingredient of Cannabis sativa, followed by Arusha (10.92%) and Singida (10.08%). The sample from Kilimanjaro had the lowest percentage of Δ9-THC (6.72%). Apart from cannabinoids, the majority of other chemical substances were found in the Dar es Salaam region sample, which could be attributed to the fact that the city is the epicenter of business rather than the cultivation area, implying that the samples were obtained from different sources and blended as a single package.
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    Trends in illicit drugs based on the analysis of seizures from the Tanzania mainland drugs market
    (Elsevier, 2021) Makangara, J. J.; Mulima, E. Z.
    This study aimed at investigating the pattern of confiscated illegal drugs in the Tanzania mainland drug market from 2011 to 2016. The samples used in this study were seized by the police force and other law enforcement agents and were analysed at the overnment Chemist Laboratory Authority, GCLA. A total of 90,366 samples weighing 17961.5 Kg were seized and analysed during the six years, an average of 15,061 samples corresponding to 2993.6 Kg per year. The overall results indicated cannabis to be the leading drug in terms of number of cases, number of samples and weights with 51.02%, 60.50% and 56.90%, respectively, but from 2011 to 2015 heroin had the highest percentage of both number of cases and samples by 58.46% and 55.91% of all seizures, respectively followed by cannabis. In terms of weight, heroin accounted for 67.55% and 26.32% in 2011 and 2012, respectively, whereas, the rest of the years’ percentage weights were between 0.50 and 6.00% of the total seizures. The trend indicated a steady decrease in heroin seizures over the six years and an increased cannabis seizure. In 2016 cannabis was 78.28% and 80.89% of the total number of cases and samples, respectively. The results also indicated the decrease of cocaine cases and a significant increase in the amount khat. The year 2016 recorded the highest number of cases and number of samples with a total of 1212 and 48,440, respectively, which resulted from the increase in cannabis seizures by 72.28% and 80.89% of the total number of cases and samples, respectively, as compared to 2015. The second and third highest years were 2013 and 2014, respectively. The least was 2011 with 3493 samples. The trend also indicated heroin seizures were highest in 2011 (62.04%), 2014 (75.31%) and 2015 (79.26%) whereas cocaine seizures kept on decreasing gradually from 31.12% in 2011 to 0.05% in 2016. Khat (Catha edulis) had the highest weight in 2014 and 2016 and ranked second after cannabis with 43.63% of the total weight during 2011–2016 period. Benzodiazepines and amphetamine type stimulants (ATS) accounted the least in terms of number of cases and number of samples.
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    Spatial variation of nutrients in Sondu-miriu and Simiyu-duma rivers: Implication on sources and factors influencing their transportation into the Lake Victoria
    (OMICS Publishing Group, 2012) Ibembe, John D.; Mungai, Nancy; Vuai, Said A. H.
    Lake Victoria basin has been under growing pressure from both natural and anthropogenic activities. These activities have created many nutrient pollution sources which affect the survival and sustainability of the Lake Ecosystem. This study was conducted to investigate the transportation of nutrients into the Lake Victoria through the Sondu-Miriu (SM) and the Simiyu-Duma (SD) rivers to represent the changes that have been occurring in many rivers draining the Lake basin. Water samples were collected along the SM and the SD river courses from upstream to the Lake shore. The results showed that the concentration of nitrate ranged between 770 μgL-1 and 970 μgL-1 for SM River and between 400 μgL-1 and 1250 μgL-1 for SD River while for phosphate it ranged from 120 μgL-1 to 270 μgL-1and from 457 μgL-1 to 1175 μgL-1 for SM and SD Rivers, respectively. The estimated nutrient loading through SM were 40ty-1 and 7.9ty-1 while for SD River were 25 ty-1 and 26ty-1 for dissolved inorganic nitrogen and phosphorous, respectively. The spatial variation of the concentrations nitrogen was not significant along the SM while in the SD Rivers the average concentration was lower in downstream than in the middle due to presence of swamp and dam that regulate the flow of water and retain nutrients. The results suggest that the catchment soil and rock are the major sources of the nutrients and their interaction with water dominate the transportation mechanism of the nutrients to the Lake Victoria through the Sondu-Miriu and Simiyu-Duma rivers.
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    Influence of land use activities on spatial and temporal variation of nutrient deposition in Mwanza region: implication to the atmospheric loading to the Lake Victoria
    (Scientific Research, 2013) Vuai, Said A. H.; Ibembe, John D.; Mungai, Nancy W.
    Increase in population growth and the associated activities have increased the nutrient input to the Lake Victoria through atmosphere and river discharge. Atmospheric input of nutrient is believed to exceed that of river discharge due to relatively higher contribution of water mass to the Lake from atmosphere. However, precipitation characteristics with respect to nutrients have not been well studied to allow qualification and quantification of atmospheric contribution to the Lake Victoria. This study was conducted to investigate influence of land use activities on spatial and temporal variation of nutrient inputs from atmosphere and to estimate atmospheric loading to the Lake Victoria. The results re- vealed that there is significant spatial and temporal variation of nutrient deposition in the study area. High concentra- tions of nutrients were observed during short rains starting from September to December. This was attributed to dissolu- tion of nutrients from soil particals and ash residues due to biomass burning accumulated in the atmosphere during dry season of June to August. Spatial variation of nutrients reflects land use activities. Urban and peri-urban areas showed very high concentration of nitrate nitrogen due to industrial and vehicle emission while rural area showed high concen- tration of phosphorous species and reduced forms of nitrogen species reflecting agricultural activities and animal keep- ing. Generally, nutrient deposition load was higher in rural area compared to urban with respective values of 15.5 and 13.9 kg·ha−1·y−1 for total nitrogen and 6.1 and 2.8 kg·ha−1·y−1 for total phosphorous. These results suggest that in order to realize significant reduction of nutrient input to the Lake Victoria, measures should be taken to control agricultural activities through proper land use planning. The measure may be directed to reduce biomass burning, emission from industries and vehicle as well as animal residue.
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    Theoretical design of low bandgap donor–acceptor (D-A) monomers for polymer solar cells: DFT and TD-DFT study
    (Taylor & Francis, 2021) Vuai, Said A.H.; Babu, Numbury Surendra
    Endeavors have been made to construct new donor–acceptor (D-A) monomers utilizing 9 H-carbazole (CB) as electron donors and different electron acceptors. All estimations were finished using DFT and TD-DFT, and B3LYP level with a 6–311 G basis set in the gas and chloroform solvent. The impacts of the distinctive acceptors on the geometry of molecules and optoelectronic properties of these D-A monomers were discussed to dissect the connection connecting the molecular structures and the optoelectronic properties. Likewise, the HOMO – LUMO energies, atomic orbital densities are calculated theoretically. Notwithstanding the charge transfer measure between the carbazole electron donor unit and the electron acceptor one is upheld by breaking down the optical spectra of the acquired monomers and the restriction of involved HOMO and LUMO. The outcomes show that the D-A monomers, CB-ODP, CB-TDP, and CB-SDP, are acceptable for optoelectronic applications in organic solar cells like BHJ.
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    On a nation as a topological space
    (Taylor & Francis, 2023) Mayila, Shega; Mpimbo, Marco; Rugeihyamu, Sylvester
    This paper introduces point-set topology into international interactions. Nations are sets of people who interact if there is a well-defined function between them. To do all these, we need to have the structure that describes how such nations interact. This calls for a topology. The kind of topology we construct in this perspective is made up by decision spaces. We first begin by developing a mathematical representation of a decision space, and use such spaces to develop a topology on a nation. Subsequently, we revisit some properties of the interior, closure, limit, and boundary points with respect to this topology and the new concept of ϕ - proximity. Finally, we define and develop ϕ - connectedness of subspaces of a nation.
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    Theoretical studies of optoelectronic and photovoltaic properties of D–A polymer monomers by Density Functional Theory (DFT)
    (Taylor & Francis, 2021) Babu, Numbury Surendra; Vuai, Said A. H.
    In this research article, the new donor–acceptor (D–A) monomers developed using 4-methoxy- 9-methyl-9 H-carbazole (MMCB) as electron donors and various electron acceptors. DFT and TDDFT methods at the level of B3LYP with a 6–311 G basis set in a gas and chloroform solvent were used to calculate electronic and optoelectronic properties. To dissect the relationship between the molecular and optoelectronic structures, the impacts of specific acceptors on the geometry of molecules and optoelectronic properties of these D–A monomers were discussed. The calculations are also carried out on HOMO–LUMO, atomic orbital densities. The calculated band gap Eg of the monomers considered increases 3,6-MMCB-OCP ≈ 3,6-MMCB-BCO < 3,6-MMCB-SDP < 3,6-MMCBSCP < 3,6-MMCB-TCP < 3,6-MMCB-TDP < 3,6-MMCB-BCS < 3,6-MMCB-BCT in both in the gas and solvent phases. Subsequently, the optoelectrical properties of EHOMO, ELUMO, Eopt, and EB energies were critically updated. Compared to different monomers, the far lower Eg of the 3,6-MMCB-OCP and 3,6-CB-BCO has shown optoelectronic applications in organic solar cells like BHJ.
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    Conformations and stability of capsaicin in bulk solvents: A molecular dynamics study
    (Elsevier, 2022) Kambaine, Naserian D.; Shadrack, Daniel M.; Vuai, Said A.H.
    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 molecular level will help explore its full potential as a therapeutic agent. In this study, molecular dynamics (MD) simulations of capsaicin in polar 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.
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    DFT and TD-DFT studies for optoelectronic properties of coumarin based donor-π-acceptor (D-π-A) dyes: applications in dye-sensitized solar cells (DSSCS)
    (Elsevier, 2021) Khalfan, Mwanahadia Salum; Babu, Numbury Surendra; Vuai, Saidi A, H.
    A series of six coumarin based dye derivatives were investigated and their geometry and optoelectronic properties elucidated for suitability in dye-sensitized solar cells (DSSCs) using TD-DFT/B3LYP with 6-31G basis set. D-π-A schemes were developed by attaching various donors and acceptors to coumarin dye (CM) to calculate changes in their photovoltaic properties. D2-CM-A2 and D4-CM-A4 showed less dihedral angle because of the low steric effect between donor and connector. The D1-CM-A1 and D2-CM-A2 results of intramolecular charge transfer were higher because of low bond length and a strong group of electron donors. The results revealed that LUMO energies of D1-CM-A1, D2-CM-A2, D3-CM-A3 and D4-CM-A4 were higher than the conduction band edge of TiO2 electrode (-4.0 eV) suggesting that these dyes will inject the electrons into the conduction band of the semiconductor. In addition, the light harvest efficiency (LHE), open-circuit voltage (VOC) and band energy gap (Eg) values are calculated in the gas phase, as well as in the solvent phase. This study shows that D1-CM-D1 and D2-CM-A2 derivatives have better properties for application in the DSSCs.
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    Theoretical study of cluster ions existing in vapours over cesium bromide and iodide
    (SCIENCEDOMAIN international, 2015) Mwanga, Stanley F.; Pogrebnaya, Tatiana P.; Pogrebnoi, Alexander M.
    The properties of ions Cs2X+, Cs3X2+, CsX2−, and Cs2X3− (X = Br or I) have been studied using the density functional theory and Möller–Plesset perturbation theory of the 2nd and 4th order. For all species the equilibrium geometrical configurations and vibration frequencies were determined. Different isomers of pentaatomic ions were found to exist: the linear (D∞h), V-shaped (C2v), kiteshaped (C2v) and bipyramidal (D3h). The relative abundances of isomers were calculated for temperatures between 700 K and 1600 K. It was found that at about 800 K, the amount of different isomers was comparable for Cs3Br2+, Cs3I2+ and Cs2I3− ions, while for Cs2Br3− the linear isomer was proved to be predominant. The enthalpies of dissociation reactions with elimination of CsX molecules and the enthalpies of formation of ions were determined.
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    Characterization of agar extracted from Gracilaria species collected along Tanzanian coast
    (Elsevier, 2022) Vuai, Said A. H.
    The study was conducted to investigate the effect of spatial variation, alkali treatment and the volume of extractant on yield and gel strength of agar for three Gracilaria species (G. salicornia, G. edulis and G. corticata) collected from the Tanzanian coast (Dar es Salaam, Tanga and Zanzibar). Treated and untreated G. corticata showed the highest yield (27 ± 0.7 % and 26.2 ± 1.3 % for treated and untreated, respectively), followed by G. salicornia then G. edulis. G. salicornia collected from Zanzibar showed the highest mass yield (22.9 ± 4.3 % for treated) followed by those collected from Tanga. Varying the volume for extraction showed no significant difference in mass yield where the p-value was >0.05. The highest gel strength was recorded from treated G. salicornia collected from Tanga (495 ±29.5 gcm-2). Gel strength varied significantly between species. Spatial variability showed a significant difference in gel strength; the sample collected from Tanga showed the highest gel strength, followed by Zanzibar then Dar es Salaam. The variation due to the volume of distilled water used for extraction showed no significant difference in gel strength at a p-value >0.05. The highest gel strength was recorded at the volume of 1500 mL (467.5 ±98.4 gcm-2), and the smallest gel strength was recorded at 500 mL. In all cases, there was a significant difference in mass yield and gel strength between treated and untreated samples. G. salicornia showed promising results as a local source of agar as it showed the highest gel strength though it produced an intermediate amount of agar. Based on the finding of this study, the volume of extraction of agar should be maintained as 1000 mL because by increasing the volume of extraction from 1000 mL to 1500 mL, the agar yield and gel strength don't change significantly. Agar yield and gel strength of Gracilaria species (G. salicornia, G. edulis and G. corticata) can be improved by alkali treatment, but further study is needed to determine the optimum amount and concentration of alkali to be used that will produce maximum yield and gel strength.
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    Modelling the dynamics of Tungiasis transmission in zoonotic areas
    (2017) Kahuru, J.; Luboobi, L.; Nkansah-Gyekye, Y.
    In this paper we formulated a mathematical model for the dynamics of Tungiasis as a result of interactions between humans, animal reservoirs and sand flea populations. Tungiasis is a parasitic skin disease caused by the female flea “Tunga penetrans” that affect the economically disadvantaged communities in Latin America, the Caribbean and sub-Saharan Africa where prevalence is high and severe infestation occurs commonly. We obtained the basic reproduction number, which has been used to determine parameter sensitivity indices so that the key parameters for the control of the disease transmission are identified. The numerical results showed that the parameters with high impact on are; flea natural mortality rate, the contribution rate of fleas into the soil environment and the transmission rate between soil environment and susceptible animals. The numerical simulation showed that decreases with decreasing and and with increasing. Therefore to control the disease we should reduce the transmission rate between soil environment and susceptible animals by regular cleaning of the home compound, reducing the contribution rate of fleas into the environment by dusting the animals with insecticidal powder and increasing the flea mortality rate by spraying the insecticides into the premises.
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    Processing-properties-performance triad relationship in a Washingtonia robusta mesoporous carbon materials-based supercapacitor device
    (The Royal Society of Chemistry, 2022) Elisadiki, J.; Gabookolwe, M. K.; Onisuru, O. R.; Meijboom, R.; Muiva, C.; King'ondu, C. K.
    Two-electrode electrochemical tests provide a close performance approximation to that of an actual supercapacitor device. This study presents mesoporous carbon materials successfully derived from Washingtonia robusta bark (Mexican fan palm) and their electrical performance in a 2-electrode supercapacitor device. The triad relationship among carbon materials “processing, properties, and performance” was comprehensively investigated. X-ray diffraction reveal that amorphousness increases with activating KOH ratio and decreases with both activation time and temperature. Raman spectroscopy shows an increase in structural defects and degree of graphitization with an increase in KOH ratio, temperature and time while transmission electron microscopy shows conversion of aggregated particles to materials with interconnected porosity and subsequent destruction of porosity with an increase in KOH ratio. A nitrogen-sorption study reveals varying trends between BET, micro and mesopore surface areas, however, pore size and volume and hysteresis loop size decreases with KOH ratio and temperature. Electrochemical studies on the other hand reveal that both the specific capacitance and charge–discharge time increase with KOH ratio, temperature and time while both charge transfer and Warburg resistances decrease and the phase angles increases towards the ideal −90° with an increase in KOH ratio, temperature and time. The device fabricated with the HHPB sample prepared at 700 °C, KOH ratio 3 for 60 min attained a specific capacitance of 179.3 and 169 F g−1 at a scan rate of 5 mV s−1 and current density of 0.5 A g−1, respectively, good cycling stability with 95% capacitance retention and 100% coulombic efficiency when cycled 5000 times at a current density of 2 A g−1. HHPB electrodes reveal perfect EDLC behavior with an energy density of 20 W h kg−1 and power density of 2000 W kg−1 when used in a symmetric coin supercapacitor cell with 6 M KOH solution. These findings show the potential of fan palm bark as electrode materials with good stability and high-rate capability for supercapacitor application.
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    Generalized compact star models with conformal symmetry
    (Springer, 2021) Maharaj, S. D.; Sunzu, J. M.; Mkenyeleye, J. M.; Jape, J. M.
    We generate a new generalized regular charged anisotropic exact model that admits conformal symmetry in static spherically symmetric spacetime. Our model was examined for physical acceptability as realistic stellar models. The regularity is not violated, the energy conditions are satisfied, the physical forces balanced at equilibrium, the stability is satisfied via adiabatic index, and the surface red shift and mass–radius ratio are within the required bounds. Our conformal charged anisotropic exact solution contains models generated by Finch–Skea, Vaidya–Tikekar and Schwarzschild. Also, some recent charged or neutral and anisotropic or isotropic conformally symmetric models are found as special cases of our exact model. Our approach sing a conformal symmetry provides a generalized geometric framework for studying compact objects.
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    The utilisation of woody species by male and female elephants in the Serengeti National Park, a nutrient-rich savanna
    (Springer, 2021) Mramba, Rosemary P.; Mlingi, Valeri N.
    Sexual differences in foraging behaviour of African elephant are comparatively well studied. However, the behaviour is known to vary between savannas due to differences in plant and herbivory communities which determine the level of forage selection and competitions. The sexual variation in foraging behaviour is attributed by sexual dimorphism, where male elephants are larger than females. The different body sizes result in divergent foraging strategies due to the differential scaling coefficients of metabolism and gut size, where the larger bodied individuals can tolerate greater quantities of low-quality forage. We studied the foraging behaviour of male and female elephants in Serengeti National Park, a nutrient-rich savanna in Tanzania, based on the forage selection and the scramble competition hypotheses. Data were collected for 2 months in 2014 by driving in road transects and make visual observations of browsing elephants within 50 m from the road. We recorded the number of bites taken per tree, parts of the tree browsed, browsing height, and tree species. Females targeted a wider range of wood species, browsing at lower heights compared to males. The sexes had a comparable length of browsing bouts, spending an average of 4 min per tree. The results support the scramble competition hypothesis through the feeding height stratification and the forage selection hypothesis through the higher diversity of tree species utilised by females. We suggest that sexual differences in forage requirements interact with forage quality and competing herbivore communities in shaping the foraging behaviour of elephants.