East African Journal Of Science, Technology and Innovation
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Influence of rare Earth doping and modifier oxides on optical and thermoluminescence properties of tellurite glasses for radiation dosimetry applications
Full text linkGlasses with the composition ZnF₂-MO-TeO₂:Ln₂O₃ (where M represents Zn, Cd, and Pb, and Ln represents Pr, Eu, Ho, and Er) were prepared using the melt-quench-anneal method. Absorption spectra were recorded for both undoped and rare-earth doped glasses. Judd-Ofelt (J-O) intensity parameters (Ω2, Ω4, and Ω6) were determined from the spectra of the rare-earth doped glasses. The Ω2 values were observed to be higher in ZnO-modified glasses and lower in PbO-modified glasses, indicating more asymmetric and covalent environments for Ln³⁺ ions in ZnO-modified glasses. Among the modified series, Ho³⁺ doped glasses showed lower values of Ω4 and Ω6, which is attributed to their significantly lower vibrational frequencies. Thermoluminescence (TL) characteristics of X-ray irradiated pure and Ln³⁺-doped tellurite-modified glasses were studied in the temperature range of 297-473 K. Undoped glasses containing zinc, cadmium, and lead oxides exhibited single TL peaks at 423 K, 389 K, and 376 K, respectively. No additional peaks were observed upon rare-earth ion doping; however, the existing glow peak temperatures gradually shifted towards higher temperatures with an increase in the intensity of the TL light output. Among the rare-earth doped glasses, the TL light output was found to be maximum in Ho³⁺ containing any modifier. The observed TL results were discussed in light of J-O intensity parameters, showing that Ω4 and Ω6 are more critical than Ω2 in optimizing the thermoluminescence properties of rare-earth-doped tellurite glasses. The trap depth parameters associated with the observed TL peaks were evaluated using Chen\u27s formulae. These parameters suggest the potential applicability of Ho³⁺ ions doped glasses in radiation dosimetry applications
Correlations of Anthropometric Measurements Among Pregnant Women Residing in Arusha City, Tanzania
Full text linkAdequate nutrition during pregnancy is a key for early prevention of poor pregnancy outcomes and future diet related non-communicable diseases. The study aimed to determine the correlations between body mass index with body fat percentage and mid-upper arm circumference to simplify nutrition status assessments among pregnant women. A cross-sectional study was conducted in 2018 at Kaloleni and Ngarenaro antenatal clinics among 468 pregnant women. The body fat percentage was measured using bioelectric impedance analyzer™; mid-upper arm circumference by a non-stretchable mid-upper arm circumference tape; weight using a SECA™ scale, and height by a stadiometer. Demographic information was gathered by face-to-face interview using a questionnaire with structured questions and data analyzed by SPSS™ Version 20. The participants were found to have a mean age of 28 years (SD ± 6), gestational age of 28 weeks (SD ± 3.82), mid-upper arm circumference of 27 centimeters (SD ± 3.7), body fat percentage of 33.7 (SD ± 7.2) and body mass index during pregnancy of 27 kg/m2 (SD ± 5.5). About 36% of the pregnant women had mid-upper arm circumference of ≥ 28cm and 37% were overweight and 22.2 % obese based on body mass index. Among 238 pregnant women who recalled their weight before pregnancy, 25.2% were overweight and 22.7% were obese using categories for a normal adult. Partial correlations showed that, body mass index is positively correlated with body fat percentage (r = 0.701, p < 0.001) and mid-upper arm circumference (r = 0.661, p < 0.001). In addition, mid-upper arm circumference and body fat percentage have strong positive correlation (r = 0.774, p < 0.001) even after controlled for maternal and gestational age. There are positive significant correlations among pre-pregnancy body mass index with percentage body fat, and mid-upper arm circumferences, hence, useable during pregnancy to address challenges associated with BMI
Development of eco-friendly food packaging bio-film from cassava starch plasticized with coconut oil
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The use of food packaging materials is on the rise because of continued growth of food industries. Food packaging materials\u27 environmental effects are now a major concern for people all over the world, particularly for the public, governments, businesses, and producers. To reduce environmental pollution, encourage the recycling of packaging materials, and achieve sustainability in food packaging, numerous studies have focused on developing novel packaging solutions that utilize renewable resources that are biodegradable, compostable, or eco-friendly. This study explored the development of food packaging film of two different thicknesses from cassava starch, glycerol and coconut oil as a plasticizer and evaluating their suitability for food packaging. Cassava starch from Kenya was characterized and used as the main raw material for making the bio-based films at a rate of 80% with glycerol (10%) and coconut oil (10%) as the processing additives. The transparency and water solubility of the films were significantly different and transparency ranged from 0.646-0.668% while the water solubility was 32.61-39.085% for the 150 µm and 200 µm films, respectively. The moisture content increased with thickness, with the highest (200 µm thick) having 10.16%. There was no significant difference on the Young’s modulus, tear strength, tensile strength at rapture and elongation at break, but the thicker films had higher water vapour permeability rate of 5.27× 10-9 g m-1 s-1 Pa-1 as compared to the 150 μm films which had 5.05× 10-9 g m-1 s-1 Pa-1. The film samples were proven to be biodegradable by the average cumulative weight loss of 89.59% for the 150 µm sample and 89.82% for the 200 µm sample, following 120 days of soil burial test. The biofilms obtained had sustainable and promising functional characteristics suitable for packaging of dry solid foods
Towards predicting daily national COVID-19 confirmed cases in Africa using selected weather and environmental parameters
Full text linkThe contribution of weather and environmental factors (WEF) to the increase in daily confirmed cases of coronavirus disease 2019 (COVID-19) is not fully understood. This study focused on the influence of average national daytime temperature (oC), night-time temperature (oC), daytime relative humidity (%), night-time relative humidity (%), Ultraviolet index at noon, Aerosol Optical Depth and volumetric soil moisture (%) on the COVID-19 cases. Daily national COVID-19 data was obtained from Datopian of the total number of confirmed COVID-19 cases reported in Kenya, Ethiopia, Ghana, Nigeria, South Africa and Egypt. Daily COVID-19 data for the period 1st March 2020 and 31st July 2020 were compared with each of the six countries’ WEF. National area average time-series of the atmospheric parameters, using data from National Aeronautics and Space Administration (NASA) Giovanni website, were generated by computing spatial averages over the given variable for each country. Incubation period of COVID-19 ranged from 1- 14 days. Therefore, the effects of each parameter within 1, 5, and 14 days were examined. The analyses were conducted based on Pearson correlation coefficient. Generally, a marked heterogeneity of relationships of factors assessed was evident among the countries. Highest positive correlation was observed for Ultraviolet index 14 days earlier (r=0.852, p=0.000), while negative correlations were observed for daytime temperature 5 days earlier (r = -0.840, p=0.000), and on the day (r= -0.869, p=0.000), respectively. Generally night-time temperatures favored COVID-19 transmission more that daytime temperatures. Nigeria depicted relatively the highest sensitivity to weather and environmental factors. These findings may prove foundational in evolving predictive potential of COVID-19 transmission using weather and environmental factors
Anisotropic stellar model with class one spacetime and barotropic equation of state
Full text linkThis work presents a realistic stellar model that merged two different approaches in generating a charged anisotropic model. The class one spacetime is used with the Einstein-Maxwell field equations and a barotropic equation of state to investigate various physical properties and behavior of compact stars. The barotropic equation of state used to investigate the behavior of compact stellar objects by examining the cosmological constant. The model describes the properties of the phantom dark energy whose cosmological setting is given when . The barotropic equation of state is equated with the Einstein-Maxwell field equations to obtain the electric field. Then, the class one spacetime is introduced to investigate Einstein-Maxwell field equations. In generating the model, the spacetime manifold was assumed to be flat, static, spherical and symmetric. The gravitational potential was specified on physical grounds. The chosen metric function was free from geometric singularities. The physical analysis shows that, metric functions specifically and exhibit behavior free from geometric singularities and align with expected patterns. Stability criteria as assessed through the adiabatic index are met confirming the model\u27s viability. The study confirms that the model adheres to essential physical criteria including mass profiles, electric fields, compactness factors and charge density
Prediction of f2-layer height of the peak electron density (hmf2) over the Southern Africa region using artificial neural network
Full text linkThe ionospheric F2 layer is the essential layer in the propagation of high-frequency radio waves, and height of the peak electron density (hmF2) is one of the important parameter. However, ionosondes are not installed at every location on earth to allow for global measurements of hmF2, especially within the southern African region. This study therefore focuses on developing a regional model for predicting the hmF2 using Artificial Neural Network techniques. In this study, prediction model was developed using year, day of the year, time in 30 minutes intervals, Sunspot Number (SSN), Solar flux at 10.7 cm (F10.7), geomagnetic activity (Kp) and Averaged planetary Index (Ap), longitude, latitude and critical frequency (foF2) as the input. The hmF2 prediction of 2009 and 2014 obtained from proposed model its results during summer and winter was compared with AMTB-2013 and SHU-2015, which are recently parameters of the IRI-2020 model. The result showed that in both 2009 and 2014 the year of low solar activity and high solar activity respectively, ANN over perform other models with minimum RMSE and PRMSE values followed by SHU-2015 and finally AMTB-2013. Therefore, it can be concluded that the architecture and learning efficiency of ANN proposed model are as good as SHU-2015 with slightly difference between them. Although all models need some improvement to increase their accuracy
Detection of co-extracted impurities from methamphetamine seized in Tanzania: a prediction of the source of the precursors
Full text linkUsing UHPLC-HESI-MS/MS, the study investigated the co-extracted target compounds as chemically attributable signatures for the source of ephedrine. Through the investigation, we found EPH as the primary precursor used in the clandestine synthesis of methamphetamine used in this investigation. The samples also contained co-extracted impurities such as norephedrineedrine and methylephedrineedrine. N, N-dimethylamphetamine was also discovered not as a co-extracted impurity but as a degraded product of methylephedrineedrine. The impurities profiles indicate the source of EPH from an Ephedra plant. The findings can help shed light on the origins of the ephedrine used in the clandestine synthesis of methamphetamine and the practices that existed prior to the synthesis of methamphetamine
Composition dynamics and regeneration potential of preferred medicinal plants in the eastern arc mountains: case study of west Usambara mountains
Full text linkThe Lushoto district of Tanzania boasts a rich diversity of medicinal plants, cherished for their therapeutic properties by the local communities. However, utilisation preferences of medicinal plants have been linked to their threats due to overharvesting and poor management. This study aimed at assessing the diversity and regeneration of medicinal plants used by the local people in five selected villages (Kiluwai, Irente, Kwemakame, Viti and Mwangoi) of Lushoto District. Medicinal plants diversity was assessed through phytosociological survey while regeneration potential was determined based on the number and dimensions of seedlings, saplings and adults. Simpson’s diversity index (D) was used to calculate the diversity of medicinal plants in each of the selected village. Quantitative data were analysed by using Statistical package for Social Sciences (SPSS) version 23. The study revealed low diversity of medicinal plants in all studied villages ranging from D = 0.361 in Kiluwai Village to D = 0.054 in Irente Village. Likewise, majority of the medicinal plants exhibited no regeneration (NR) across all study sites. The detected poor or no regeneration status of medicinal plants and low diversity serves as an indicator of the ecological extinction of medicinal plants at local level in the near future. Therefore, strong initiatives should be taken to ensure the sustainability of medicinal plants in the study area
Prevalence of Soil Transmitted Helminths infection in domesticated pigs and dogs of Morogoro region, Tanzania
Full text linkSoil-transmitted helminths (STH) infections are caused by a group of nematode worms that require development in the soil to become infective. These infections cause ill health in animals; some are responsible for zoonotic infection. Zoonotic STH of dogs and pigs include; Ancylostoma spp, Toxocara canis, and Ascaris suum. This study was carried out due to limited information on STH infections in domesticated pigs and dogs in Tanzania. The study aimed to determine the prevalence of STH in domestic pigs and dogs in Morogoro Municipality and Mvomero District, Tanzania. This was a cross-sectional study which involved a total of 281 dogs and 237 pigs from two districts in the two study areas. The study animals were randomly selected and faecal samples collected and examined for STH using a simple test tube flotation technique. The data collected was entered in Excel and analysis done using Stata version 14. Prevalence of the STH was computed for both animal species and chi-square used to obtain p-values as the test for statistical significance. The prevalence of STH in dogs was 50.53% with Ancylostoma species being the most prevalent (47.33%), followed by Toxocara (12.46%), Trichuris (2.49%) and Strongyloides species (1.07%). The STH prevalence in pigs was 85.23% and the isolated species were Oesophagostomum (81.01%), Trichuris (12.24) and Ascaris species (5.49%). Males and pigs aged ≥1 year were more infected with STH species with a p-value of 0.025 and 0.016, respectively. Dewormed dogs were observed to be less likely to be infect with STH species (p- value = 0.002). Results of this study show that STH species were prevalent gastrointestinal parasites in dogs and pigs in the study area. Mixed infection was common in both animal species. Measures for control of STH infections in dogs and pigs should be practiced to improve animal health
DFT and TD-DFT studies of the effect of internal acceptor based on D-A’-Π-A structure for dye-sensitized solar cells
Full text linkEconomic growth and population expansion have led to an increase in the world’s energy consumption. For human use, solar energy is one of the greatest significant renewable energy sources. In this study, six D-A’-π-A of newly organic dye molecules (M1-M6) have been developed by changing the internal acceptor groups. Density functional theory (DFT) and time-dependent DFT (TD-DFT) theory techniques through B3LYP and 6-311G basis set have been employed to assess their optoelectronic properties as well as photovoltaic characteristics of six D-A’-π-A novel organic dyes designed molecules. A number of critical factors like geometrical optimization, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy level, energy bandgap and light-harvesting efficiency (LHE) have been studied so as to determine the effect of developed internal acceptor group on increasing intramolecular charge transfer (ICT) and improving light-absorbing capacities. From the data, out of all the developed six organic dye molecules, M2 perform better than other organic dye molecules, showing injection driving force (ΔGinject) of -0.1807 eV and -0.1125 eV for gas phase and solvent phase, respectively, open-circuit voltage (Voc) of 0.3003 eV and 0.2516 eV for gas phase and solvent phase, respectively, and maximum absorption wavelength of 959.76 nm and 1148.69 nm for gas phase and solvent phase, respectively. Therefore, M2 dye molecule was observed to be more favorable candidate in the application of dye-sensitized solar cells (DSSCs) technology hence recommended for practical study to offer effective advancement in D-A’-π-A system organic dye for sustainable energy development. Additionally, this study contributes to directing researchers for further study toward designing more effective novel organic dye molecules for DSSCs application