Department of Chemistry

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3 - Advanced biopolymer-based green composites: their processing and damage mechanism
(ScienceDirect, 2021-09) Mwesigwa, Ronald; Nkomo, Nkosilathi Zinti; Mwasiagi, Josphat Igadwa; Wanyama, Aaron
Composites are constructions of lightweight bearing high toughness and custom-made properties for precise use, globally. In addition, bio-based composites are constructions made from natural and/or synthetic fibers and petroleum-based polymers and/or biodegradable polymers. Furthermore, green composites are constructions obtained from biopolymers and agricultural/natural or biofibers that are more environmentally friendly hence highly sought after worldwide. Currently, green composites are offering enormous benefits that are promoting them in the automotive, packaging, construction, electrical and insulation, furniture, consumer, and household industries among others. This chapter therefore presents advanced biopolymer-based green composites in relation to their processing and damage mechanism. Subtopics covered include processing and characterization of biopolymers, agricultural/natural fibers, and green composites. Various failure and damage mechanisms pertaining to green composites are also covered.
Aflatoxins in Uganda: an encyclopedic review of the etiology, epidemiology, detection, quantification, exposure assessment, reduction, and control
(International Journal of Microbiology, 2020-01-08) Timothy, Omara; Winfred, Nassazi; Tom, Omute; Aburu, Awath; Fortunate, Laker; Raymond, Kalukusu; Bashir, Musau; Brenda, Victoria Nakabuye; Sarah, Kagoya; George, Otim; Eddie, Adupa
Uganda is an agrarian country where farming employs more than 60% of the population. Aflatoxins remain a scourge in the country, unprecedentedly reducing the nutritional and economic value of agricultural foods. This review was sought to synthetize the country’s major findings in relation to the mycotoxins’ etiology, epidemiology, detection, quantification, exposure assessment, control, and reduction in different matrices. Electronic results indicate that aflatoxins in Uganda are produced by Aspergillus flavus and A. parasiticus and have been reported in maize, sorghum, sesame, beans, sunflower, millet, peanuts, and cassava. The causes and proliferation of aflatoxigenic contamination of Ugandan foods have been largely due to poor pre-, peri-, and postharvest activities, poor government legislation, lack of awareness, and low levels of education among farmers, entrepreneurs, and consumers on this plague. Little diet diversity has exacerbated the risk of exposure to aflatoxins in Uganda because most of the staple foods are aflatoxin-prone. On the detection and control, these are still marginal, though some devoted scholars have devised and validated a sensitive portable device for on-site aflatoxin detection in maize and shown that starter cultures used for making some cereal-based beverages have the potential to bind aflatoxins. More efforts should be geared towards awareness creation and vaccination against hepatitis B and hepatitis A to reduce the risk of development of liver cancer among the populace.
Antibacterial and anticancer activities of green-synthesized silver nanoparticles using Photinia glabra fruit extract
(Nanomedicine, 2023-08) Tabbisa, Namulinda; Lei-Lei, Bao; Justus, Kwetegyeka; Ivan, Gumula; Yi-Jia, Yan; Zhi-Long, Chen
Aims: We prepared Photinia glabra (PG) aqueous fruit extract, utilized it to synthesize silver nanoparticles (PG-Ag NPs) and evaluated the antibacterial and anticancer activities of the nanoparticles (NPs). Materials & methods: Silver nitrate aqueous solution was reduced to PG-Ag NPs using aqueous PG fruit extract. NP shape, size, composition and functionalization were determined using transmission electron microscopy, x-ray photoelectron spectroscopy, Fourier transform infrared and x-ray diffraction. Results & conclusions: PG-Ag NPs were spherical, approximately 39–77 nm-sized, functionalized surfaces with notable antibacterial activity against both Escherichia coli and Staphylococcus aureus, with an MIC <30 ug/ml and cytotoxicity toward esophageal cancer cells, with IC50 values less than 20 ug/ml. PG-Ag@rt NPs have been shown to be a potent antibacterial and anticancer agent, and their enriched particle surfaces can be conjugated with other compounds for multibiomedical applications.
Antibacterial properties of phytochemicals isolated from leaves of alstonia boonei and aerial parts of ipomoea cairica
(Natural Product Communications, 2024-09-26) Gumula, Ivan; Kyarimpa, Christine; Nanyonga, Sarah Kiwanuka; Kwesiga, George; Busulwa, George; Opio, Boniface; Heydenreich, Mathias; Omara, Timothy
Objective: The leaves of Alstonia boonei and aerial parts of Ipomoea cairica are used for treatment of microbial infections among other ailments in African traditional medicine. The aim of this study was to investigate the antimicrobial phytochemicals in A. boonei leaves and Ipomoea cairica aerial parts to validate their traditional use in Ugandan herbal medicine. Methods: The plant materials were separately extracted using a dichloromethane/methanol (1:1) solvent system and subjected to repeated chromatographic separation to isolate pure compounds. The chemical structures of the isolated compounds were determined through 1H NMR, 13C NMR and 2D NMR(COSY, HSQC and HMBC). The antibacterial activity of the extracts and pure compounds were assessed using the agar well diffusion method. Results: Chromatographic fractionation of the extracts yielded trans-fagaramide and a pentacyclic lupane-type triterpenoid, lupeol, from A. boonei, and friedelin from I. cairica. Trans-fagaramide was identified for the first time in the Alstonia genus while friedelin was identified for the first time in I. cairica. The isolated compounds demonstrated antibacterial activity, with trans-fagaramide showing a minimum inhibitory concentration (MIC) of 125 μg/mL against Pseudomonas aeruginosa and 250 μg/mL against Staphylococcus aureus, Salmonella typhi and Escherichia coli. Friedelin exhibited a MIC of 125 μg/mL against Escherichia coli and 250 μg/mL against Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella typhi. Conclusion: The antibacterial activities observed in this study support the traditional use of A. boonei and I. cairica by indigenous communities in Uganda for treating microbial infections.
Antimicrobial activity of cotton and silk fabrics dyed with Datura stramonium (Jimson weed) plant leaf extracts
(African Journal of Microbiology Research, 2019-11) Musinguzi, Alex; Mwasiagi, Josphat Igadwa; Wanyama, Aaron; Gumisiriza, Onesmas
Functional finishes are agents that are applied to fabrics to make them suitable for specific uses and contribute a specific attribute to a fabric without altering its appearance. In this context, the present study reveals the importance of dyed fabrics with Datura stramonium plant leaf extracts to control antibiotic-resistant bacteria, which have been a threat to human health and posed noticeable challenges confronted with medical physicians in the treatment of many infectious diseases. More still, the importance of using natural dye is not limited to its antimicrobial and other medicine values but also to its wide range of advantages via elimination of environmental pollution due to the usage of synthetic dyes. 100% plain woven, desized, scoured and bleached cotton fabric samples and 100% degummed and bleached hand knitted silk fabric samples were dyed with aqueous extracts from D. stramonium plant leaves in combination with Alum and Iron Sulphate as mordants using post-mordanting method and then tested against two strains of Staphylococus aureus (Gram-positive bacteria) and Pseudomonas aeruginosa (Gram-negative bacteria) using Agar diffusion method as per SN195920-1992 standard. The fastness properties (wash fastness, light fastness and rubbing fastness) of the dyed fabrics were assessed following guidelines from The American Association of Textile Chemists and Colorists (AATCC) and International Organization for Standardisation (ISO) testing methods. Spectrophotometric experiments were employed to evaluate the colour strength (K/S) of the dyed samples. The antimicrobial activity results showed that for both cotton and silk dyed fabric samples; there was an interruption of the microbial growth beneath the fabric and a clear zone of inhibition around the fabric. Dye ability and fastness results showed that dyed fabric samples with D. stramonium extracts using mordants had relatively high colour strength (K/S) values as compared to the control fabrics which were dyed without a mordant and their colorant was more stable to light, rubbing and washing, respectively.
Assessment of the quality of levonorgestrel emergency contraceptive tablets (morning-after pill) sold in Uganda
(Kyambogo University [unpublished work], 2023-08) Babirye, Lydia Brenda
Use of poor quality emergency contraceptives may lead to unwanted pregnancies. Many unwanted pregnancies lead to illegal abortions having a devastating impact on the health of the girl child and women at large. This study was aimed at assessing the quality of levonorgestrel tablets sold on the Ugandan market. The quality of levonorgestrel tablets was established through collection of samples from the Eastern, Western, Central and Northern regions of Uganda. The High Performance Thin Layer Chromatography (HPTLC) and the High Performance Liquid Chromatography (HPLC) analytical techniques were used to identify and determine the content of levonorgestrel, respectively. The quality parameters assessed included visual inspection, identification, content uniformity, assay and dissolution. Results showed that thirteen percent of samples found on the market were counterfeits and all belonged to brand G. The samples that had been confirmed counterfeits further failed the uniformity of content, assay and dissolution tests. Eighty-seven percent of the samples found on the market passed the assay and uniformity of content test and the statistical analysis conducted at 95% CI revealed significant differences (ANOVA, p < 0.05) within the brands in the mean uniformity of content and assay results. Further findings showed that 30% of the samples on market exhibited inadequate release of levonorgestrel by dissolution testing whereas 13% showed no release of levonorgestrel. Similarly, the statistical analysis conducted using the one-way ANOVA at 95% CI revealed that there was a significant difference (p < 0.05) in the drug release of the different brands of levonorgestrel tablets examined in the study. From the study it was observed that only 57% provided the stated level of contraceptive action, 30% provided questionable results whereas 13% offered no prevention against unwanted pregnancy. The statistically significant differences observed further indicated the availability of levonorgestrel tablets on the market that are not therapeutically equivalent. It was concluded that there is need to emphasize regular assessment of the quality of emergency contraceptives on the market in order to lower the risk of patients being exposed to products of poor quality, safety, and efficacy.
Catalytic potential of natural zeolites and selected metalic ores in pyrolysis of groundnut shells for bio-oil production
(Kyambogo University (un published work), 2019-07) Kalega, Ivan Fredrick
Catalytic pyrolysis is a promising thermochemical method of conversion of biomass to chemicals and fuels compatible with current petrochemical engines. Catalytic modification of pyrolyzed bio-oils are geared towards the elimination and substitution of oxygen and oxygen containing functionalities in addition to increasing hydrogen to carbon ratio in the final product. Recent progress has focused on both hydrodeoxygenation and hydrogenation of bio-oil using a variety of metal catalyst in the production of aromatic compounds from bio-oil using catalytic pyrolysis. However, current effectiveness of catalysts and conversion efficiency remain a challenge. In this study five naturally occurring inorganic materials from Usuuku rock, Kilembe mines rock, Tiira soil, Katwe salt and Manafwa river zeolites, having traces of transition metal elements were investigated for their influence on H/C and O/C ratio of bio-oil produced by pyrolysis of groundnut shells. The results showed bio-oil catalysed by zeolitic with metallic ore in the framework had a high H/C ratio and generated are hydrocarbons, that is, paraffins, olefins and aromatics than those without catalyst. Basing on the results of the study, it was concluded that different catalysts have impact on product composition, with catalysts of highest SiO2/Al2O3 producing more light gases. This result agrees with Cheng et al. (2000) who studied furan conversion to aromatics and olefins using HZSM-5. It was also concluded that the natural catalytic materials enhanced yields of the petroleum like compounds mentioned above, i.e., Kilembe ore for benzofuran; Katwe salt for aromatics; and Manafwa catalyst for olefins, CO and aromatics. This was based on eraspec fuel analyser and showed that the materials selected had catalytic potential for pyrolysis of groundnut
Characterization and analysis of some natural dyes from selected plants in Uganda
(Makerere University (Unpublished work)., 2012-08) Wanyama, Aaron P.G
Forty different plant species with potential to yield natural dyes were collected from different parts of Uganda between 2004 and 2008. Extraction of the plant materials was done using distilled water after heating for 30 minutes and cooling the contents of the beaker, after which dyeing of I00% cotton pieces of fabrics was carried out using crude extracts from each selected plant species. The colours developed on each fabric sample varied from plant to plant depending on the nature, structure and composition of the colour components found in each crude plant extract, the geographical location of the plants, the mordant used, the fabric support and the liquor ratio employed during the dyeing process. Colour was evaluated using spectral reflectance values measured by the Datacolour SF600 spectral reflectance spectrophotometer. The colour developed on some of the dyed cotton fabrics was evaluated for colour fastness and colour characterization using the CIELab colour order system. The shade variation was mordant dependent and the values of the hue angle correlated between the colour appearance of the dyed fabric samples and the phenolic composition of the plant extracts. The surface colour yield on cotton fabrics of some of the natural dyes investigated was determined using the Kubelka-Munk equation and was found to vary from plant to plant. Some of the natural dyes notably Albizia coriaria, Vitellaria paradoxa, Morindu lucida, Syzygium cordatum and Mangiferu indicawere evaluated and exhibited good colour fastness properties, had no adverse effects on test animals occupied mainly the yellow-red quadrant of the colour space diagram and contained in their molecular structures characteristic colour moieties capable of dyeing textile materials as potential alternatives to synthetic dyes.
Co-Mn hybrid oxides supported on N-doped graphene as efficient electrocatalysts for reversible Oxygen electrodes
(Journal of The Electrochemical Society., 2018-06-27) Lu, Zhenjie; Chen, Xingxing; Liu, Penggao; Huang, Xinning; Wei, Jiong; Ren, Zhong; Yao, Songdong; Fang, Zhigang; Wang, Tao; Masa, Justus
Journal of The Electrochemical Society The Electrochemical Society, find out more Co-Mn Hybrid Oxides Supported on N-Doped Graphene as Efficient Electrocatalysts for Reversible Oxygen Electrodes Zhenjie Lu1, Xingxing Chen7,1, Penggao Liu2, Xinning Huang3, Jiong Wei6,1, Zhong Ren1, Songdong Yao1, Zhigang Fang1, Tao Wang7,2 and Justus Masa7,4,5 Published 27 June 2018 • © 2018 The Electrochemical Society Journal of The Electrochemical Society, Volume 165, Number 9 Citation Zhenjie Lu et al 2018 J. Electrochem. Soc. 165 H580 141 Total downloads 99 total citations on Dimensions. Turn on MathJax Get permission to re-use this article Share this article Share this content via email Share on Facebook (opens new window) Share on Twitter (opens new window) Share on Mendeley (opens new window) Hide article information Author affiliations 1 Research Group of Functional Materials for New Energy, School of Chemical Engineering, University of Science and Technology Liaoning, 114051 Anshan, People's Republic of China 2 Key Laboratory of Energy Materials Chemistry, Institute of Applied Chemistry, Xinjiang University, 830046 Urumqi, People's Republic of China 3 Engineering Training Center, University of Science and Technology Liaoning, 114051 Anshan, People's Republic of China 4 Analytical Chemistry - Center for Electrochemical Sciences (CES), Ruhr-Universität Bochum, 44780 Bochum, Germany 5 Department of Chemistry, Kyambogo University, Kyambogo, Uganda Author notes 6 Present address: College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry, Nankai University, 300071 Tianjin, China. 7 E-mail: xingchenstar79@163.com; renbility@163.com; justus.masa@rub.de ORCID iDs Xingxing Chen https://orcid.org/0000-0002-5754-2236 Justus Masa https://orcid.org/0000-0002-8555-5157 Dates Received 5 January 2018 Published 27 June 2018 DOI https://doi.org/10.1149/2.1411809jes Buy this article in print Journal RSS Sign up for new issue notifications Create citation alert Abstract Despite metal-air batteries possessing very high theoretical energy densities, inefficient reversibility of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) at the oxygen electrode undermines their rechargeability, which has slowed their market entry. Herein, we demonstrate a simple procedure for synthesis of a hybrid of MnO and metallic Co supported on N-doped graphene that exhibits activity and stability as a bifunctional ORR/OER catalyst, with a round trip ORR/OER overvoltage of 0.85 V, which remained constant for at least 70 h when cycling alternately, between oxygen evolution at a current density of 10 mA cm−2 and oxygen reduction at −1 mA cm−2. Insights into the key properties of the catalyst that influence its performance are proposed based on structural characterization by TEM, SEM, Raman spectroscopy, XRD and XPS. Besides MnO and metallic Co as the predominant crystalline species in the Co-Mn hybrid oxide, XPS revealed Mn3O4 and CoO rich surfaces, ascribed to oxidation of MnO and metallic Co due to atmospheric exposure. The synergetic interaction between the Co-Mn hybrid oxides and N-doped graphene, as well as Co-Mn interaction, favor improved ORR, OER and bifunctional ORR/OER performance of the catalyst.
Compliance and implementation of municipal solid waste management laws and regulations in Mukono district, Uganda
(Archives of Current Research International, 2023-09) Dan, Kibuuka Kiguli; Ameria, Nabukonde; Alex, Barakagira
Consumption and production of resources leads to generation of wastes that may be undesirable in the environment. Solid waste management laws are put in place aimed at ensuring proper and effective control and management of wastes in an area. This study was set out to assess the compliance and implementation of municipal solid waste management laws and regulations in Mukono district, Uganda. Specifically, the study sought to: characterize the solid wastes generated in Mukono municipality; determine the mechanisms of implementation of solid waste management laws and regulations in Mukono municipality; and to assess the effectiveness of the solid waste management laws and regulations in Mukono municipality. A case study design complimented with both quantitative and qualitative approaches were employed to obtain the required data to answer the stated objectives. A questionnaire and documentary review were used to collect the required data for the study. A number of solid wastes including food and food wastes; glass, plastics and metals; and textiles among others were generated in Mukono municipality. There are solid waste management laws and regulations used in the management of wastes in Mukono municipality. Some mechanisms including awareness creation and monitoring implementation processes have been put in place for an effective implementation of municipal solid waste management laws. The study found out that there has been an ineffective implementation of municipal solid waste management laws in Mukono municipality which were most likely brought about by poor leadership, inappropriate allocation of funds and low levels of awareness among members of the local community. It is recommended that Institutions like the Environment Police and the National Environment Authority should work hand in hand to strengthen the implementation of solid waste management laws and regulations in the country. The government should enhance sensitization campaigns about what the solid waste management laws and regulations entail. In addition, funds required for implementation of the laws and regulations should be appropriated and be used for the intended purposes.
Concentrations and sources apportionment of polycyclic aromatic hydrocarbons in sediments from the Uganda side of Lake Victoria
(Environmental Science: Processes & Impacts, 2017) Nasifu, Kerebba; Patrick, Ssebugere; Justus, Kwetegyeka; Kenneth, Arinaitwea; John, Wasswa
This study presents the levels and possible sources of selected polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Napoleon Gulf and Murchison Bay of Lake Victoria. Sediment samples were extracted and cleaned up for PAHs using UNEP, 1992, and EPA method 3630C protocols. The analysis of sample extracts was carried out using a gas chromatograph coupled to a mass spectrometer. Fifteen congeners, mostly the high molecular weight PAHs (HPAHs) (4–6 rings) were detected. Total (∑) concentrations varied from 44.2 to 80.2 ng g−1 dry weight (d.w.) at the Napoleon Gulf, while those at the Murchison Bay ranged from 17.0 to 55.0 ng g−1 d.w. Statistical analysis showed no significant difference in the concentrations of PAHs among sites (p < 0.05, ANOVA). It was noted that the concentrations for most sampling sites were far below the lowest effect levels based on the Sediment Quality Guidelines, except for one station at the Napoleon Gulf. Principal component analysis and diagnostic ratios indicated that PAHs of combustion and petroleum origin were dominant and brought about mainly by atmospheric deposition.
A detailed time series assessment of the diet of Lesser Flamingos: further explanation for their itinerant behaviour
(Hydrobiologia., 2013-04-27) Kaggwa, Mary N.; Gruber, Martin; Oduor, Steve Omondi; Schagerl, Michael
We hypothesised that changes in nutritional composition and quality of the pelagic phytoplankton community influence the occurrence of Lesser Flamingo populations in two Kenyan saline– alkaline lakes, Nakuru and Bogoria. This was achieved by carrying out a detailed time series assessment of the phytoplankton community composition and nutritional components (carbohydrates, crude protein and lipids) from July 2008 to October 2009 on a weekly basis for each lake. Lesser Flamingos were estimated visually from the lake shore of the sampling sites. In Lake Nakuru, Lesser Flamingos had a significant positive relationship with lipids and Arthrospira biomass but a negative relationship with small cyanoprokaryotes. For Lake Bogoria, no significant differences were observed as the Arthrospira was available throughout the sampling period though the flamingo numbers still fluctuated. We concluded that the nutritional composition and quality of the phytoplankton community influence the temporal and spatial abundance of Lesser Flamingos although other factors such as the prevailing environmental conditions may take precedence.
Determination of selected acaricide residues in soils and water resources around cattle dip tanks in Mbarara district, western Uganda
(Kyambogo University (un published work), 2019-10) Ssenoga, Eric
This study determined the levels of selected acaricide residues in soils and water samples around cattle dips in Mbarara District western Uganda. Samples were collected, prepared and analysed for amitraz, chlorpyrifos and cypermethrin residues by gas chromatography equipped with a Flame Ionization Detector (GC/FID). The obtained data revealed evidence of amitraz, chlorpyrifos and cypermetherine contributing to the presence of acaricide residues in the area. The observed quantities were higher than United States permissible maximum residue limits (MRL) for agricultural soils. The amitraz, chlorpyrifos and cypermethrin residue concentrations at the sampled sites are high near the dip and reduce with all investigated distance of 25 m, 50 m and 75 m away from the cattle dip tank. This could be as a result of the cattle carrying some acaricide as they move away from the cattle dip tank and not all the acaricides flow back into the cattle dip tank. The data obtained from obtained from analysis of samples indicated presence of amitraz, chlorpyrifos and cypermetherin present in the area for all the studied farms. There was a significant difference in amitraz residue concentration in water samples from farms A compared to farms B and C this is due to different dosing in farm A compared to B and C. However, farms D and E were at zero because amitraz was not used as acaricide in these particular farms At farms D and E, only chlorpyrifos and cypermethrin residues were detected and no amitraz residues was detected at any of the studied distances away from the cattle dip tanks. The data obtained from water resources showed that only amitraz residues were detected from water samples collected from farms A, B, and C at all studied distances away from the cattle dip tanks with no Chlorpyrifos and cypermethrin being detected at the three farms A, B and C xii At farms D and E, only Chlorpyrifos and Cypermethrin residues were reported from water samples collected at farms E and D and no amitraz residues was detected at any of the studied distances away from the cattle dip tanks. The study from cattle dip samples showed that amitraz was found in the three dip tanks from farms A, B, and C while Chlorpyrifos and cypermethrine were detected from farms D and E. Farm A had the highest amitraz concentration, followed by farm B and then farm C. All the concentrations exceeded the allowable maximum standard values / Normal range of 250 ± 5 ppm of amitraz inside the cattle dip tank an indication of overdosing of the cattle dip tanks by farmers. At farms D and E, both Chlorpyrifos and cypermethrin were reported with farm E having the highest concentration of Chlorpyrifos and cypermethrine followed by farm D with concentration of Chlorpyrifos and cypermethrine. All the concentrations exceeded the allowable maximum standard values / Normal range of 500 ± 5 ppm Chlorpyrifos and 50 ± 5 ppm for cypermethrin inside the cattle dip tank an indication of overdosing of the cattle dip tanks.
Effects of industrial effluents on the quality of water in Namanve stream, Kampala Industrial and Business Park, Uganda
(BMC Research Notes, 2020) Christopher, Angiro; Patrick, P’Odyek Abila; Timothy, Omara
Objective: Kampala Industrial and Business Park (KIBP) is one of the premier and the most successful Ugandan indus‑ trial complexes that impact the inner Murchison bay of Lake Victoria. The current study aimed at evaluating the effect of industrial effluents on the physicochemical and microbiological quality of water taken from four different sites along Namanve stream in KIBP, Wakiso district, Uganda. Results: All the water quality parameters were below WHO maximum permissible limits except turbidity, electrical conductivity and Escherichia coli count. Mean values of the monitored water quality parameters increased from the point of effluent discharge downstream of Namanve stream.
Electrodeposition of nickel-metalloid alloy films and their investigation for electrocatalytic water splitting
(Kyambogo University, 2021-03) Ssemwanga, Herbert
Electrocatalytic splitting of the water molecule to produce hydrogen as an energy carrier provides a very promising pathway for provision of green and inexhaustible renewable energy for the future. The bottleneck of this reaction is the sluggish kinetics of the OER that makes the processes to be extremely energy intensive. Electrochemists have devoted much research efforts in finding cost-effective electrocatalysts that can speed up the OER during electrochemical water splitting. In this study, reference (NiB, NiP and NiTe) metalloid alloy powders pre-synthesized at Ruhr University, Germany and (Ni-Ga and Ni-In) metalloid films synthesized by electrodeposition were investigated for the OER activity in an alkaline electrolyte using LSV. The results showed that the optimal number of CV deposition cycles for the highest OER activity were 7 for Ni, 7 for Ga,3 for In,7 for Ni-In and 5 for Ni-Ga composite electrocatalytic films. The OER activity of 𝑁𝑖(𝑂𝐻)2formed by electrodeposition was several fold higher than that of the pure Ga and In films, as well as of the composite Ni-Ga and Ni-In films. It was concluded that CV deposition cycles that had the highest activity and therefore the highest performance were; 7 for Ni, 7 for Ga ,3 for In ,7 for Ni-In and 5 for Ni-Ga composite electrocatalytic films respectively. Ga and In species exist as discrete domains rather than alloys in the Ni-Ga and Ni-In composite films. The attempted method for synthesis of Ni-Ga and Ni-In alloy films by electrodeposition most likely led to the formation of Ni-Ga and Ni-In composite films with discrete domains of oxides of their respective elements but not alloys.
Environmental levels and human body burdens of per- and poly-fluoroalkyl substances in Africa: a critical review
(Elsevier : Science of The Total Environment., 2020-10-15) Ssebugere, Patrick; Sillanpää, Mika; Matovu, Henry; Wang, Zhanyun; Schramm, Karl-Werner; Omwoma, Solomon; Wanasolo, William; ChelangatNgeno, Emily; Odongo, Silver
Per- and polyfluoroalkyl substances (PFASs) are known organic pollutants with adverse health effects on humans and the ecosystem. This paper synthesises literature about the status of the pollutants and their precursors, identifies knowledge gaps and discusses future perspectives on the study of PFASs in Africa. Limited data on PFASs prevalence in Africa is available because there is limited capacity to monitor PFASs in African laboratories. The levels of PFASs in Africa are higher in samples from urban and industrialized areas compared to rural areas. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are the dominant PFASs in human samples from Africa. Levels of PFOS and PFOA in these samples are lower than or comparable to those from industrialized countries. PFOA and PFOS levels in drinking water in Africa are, in some cases, higher than the EPA drinking water guidelines suggesting potential risk to humans. The levels of PFASs in birds' eggs from South Africa are higher, while those in other environmental media from Africa are lower or comparable to those from industrialized countries. Diet influences the pollutant levels in fish, while size and sex affect their accumulation in crocodiles. No bioaccumulation of PFASs in aquatic systems in Africa could be confirmed due to small sample sizes. Reported sources of PFASs in Africa include municipal landfills, inefficient wastewater treatment plants, consumer products containing PFASs, industrial wastewater and urban runoff. Relevant stakeholders need to take serious action to identify and deal with the salient sources of PFASs on the African continent.
Facile synthesis and characterization of multi-walled carbon nanotubes decorated with hydroxyapatite from cattle horns for adsorptive removal of fluoride
(Heliyon Open access, 2023-03-08) Ojok, Walter; Bolender, James; Wasswa, John; Ntambi, Emmanuel; Wanasolo, William; Moodley, Brenda
Developing a new adsorbent for fluoride removal from cattle horn waste materials by a facile chemical method has shown great potential for fluoride removal. This paper reports the synthesis of multi-walled carbon nanotubes decorated with hydroxyapatite from cattle horns (MWCNT-CH) using a facile chemical method. Characterization studies using standard techniques showed that the composite is mesoporous with a rough morphology and contained MWCNTs uniformly encapsulated by the hydroxyapatite forming a crystalline MWCNT-CH composite. Optimization of fluoride adsorption by the as-synthesized composite using Response Surface Methodology (RSM) showed that a maximum fluoride removal efficiency of 80.21% can be attained at initial fluoride concentration = 10 mg/L, pH = 5.25, adsorbent dose = 0.5 g and a contact time of 78 min. ANOVA indicates contribution of the process variables in descending order as pH > contact time > adsorbent dose > initial fluoride concentration. Langmuir isotherm (R2 = 0.9991) best described the process, and the maximum adsorption capacity of fluoride onto the as-synthesized MWCNT-CH composite was 41.7 mg/g. Adsorption kinetics data were best fitted in the pseudo-second-order kinetic model (R2 = 0.9969), indicating chemisorption. The thermodynamic parameter ( Δ H = 13.95 J/mol and Δ S = 65.76 J/mol/K) showed that fluoride adsorption onto the MWCNT-CH composite was a spontaneous, endothermic, and entropy-driving process. Moreover, the adsorption mechanism involves ion exchange, electrostatic interaction, and hydrogen bonding. Fluoride was successfully desorbed (using 0.1 M NaOH) from the composite in four cycles, retaining fluoride removal efficiency in the fourth cycle of 57.3%.
Factors influencing non-compliance to occupational safety and health practices in the informal non-food manufacturing sector in Kampala city, Uganda
(Current Journal of Applied Science and Technology, 2020-02) Wekoye, Stephen Aurice; Moturi, Wilkister Nyaora; Makindi, Stanley
The informal non-food manufacturing sector is an engine of growth and development in both developed and developing countries. It’s unregulated and unregistered in official government statistics. However, this particular sector is faced with occupational safety and health hazards without preventive measures. A number of factors affect compliance with control measures. The study assessed factors influencing non-compliance to occupational safety and health practices in the informal non-food manufacturing sector in Kampala, Uganda. The purpose of the study was to acquire occupational safety and health data on the informal sector and identify needed interventions for mitigation. A cross-sectional survey design was adopted with qualitative and quantitative data collection techniques in 424 firms. Chi-square analysis showed occupational safety and health was good among male respondents compared to females (p<0.05. 2 =23.9), use of Personal Protective Equipment (2 =40.393, p<0.000), education level (2 =147.3, p< 0.000), period working at the enterprise (p<0.05. 2 = 87.5, p=0.002) the period spent working provides experience to workers hence better equipped to manage occupational safety and health. Hours spent at work (p<0.05. 2 =19.8), due to less fatigue and exhaustion. Multivariate logistic regression showed that respondents who were 31-40 years old had significantly reduced odds (COR 0.0467-0.0478) of practising occupational safety and health practices at work and able to employ good occupational safety and health practices at work, compared to below 30 and above 50 years. Men in general employed safe practices of occupational safety and health than women (COR 0.0918-0.0997) hence safer at work due to higher literacy in men. Adequate knowledge and awareness had (COR 0.860-0.863) knowledge empowers workers about hazards prevention, usually provided through training by employers. Duration of work (COR 1.189-1.10) as result of experience in managing hazards at work coupled by supervision over time. Use of personal protective equipment (COR of 0.0317- 0.0319) being cheap. Creation of awareness, safe work practices Provision and use of PPE and provision of occupational safety and health (OSH) regulations, as well as proactive multi-media strategies to improve the situation is required.
The fatty acid composition of edible grasshopper Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) feeding on diversifying diets of host plants
(Wiley online Library: Entomological Research, 2018-12-12) Rutaro, Karlmax; Malinga, Geoffrey M.; Lehtovaara, Vilma J.; Opoke, Robert; Valtonen, Anu; Kwetegyeka, Justus; Nyeko, Philip; Roininen, Heikki
Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) is a highly valued edible grasshopper species in Africa. However, the effects of plant diets on lipid content and fatty acid composition of R. differens are not well understood. We tested the effects of four diets on the total lipid content and fatty acid composition of R. differens. Sixth instar nymphs of R. differens were reared on one, and mixtures of two, three, and six natural plant inflorescences. Individuals collected from the field constituted a control treatment. We extracted lipids and analyzed the fatty acid methyl esters using gas chromatography–mass spectrometry. We analyzed if the total lipid content, body weight, and fatty acid composition differed among diets and between the sexes using two-way ANOVAs and a PERMANOVA model, respectively. The total lipid content and weight of R. differens did not differ among the diets. The nine common fatty acids were palmitic (mean across treatments, 26%), oleic (22%), palmitoleic (18%), linoleic (13%), stearic (7%), myristic (6%), myristoleic (4%), α-linolenic (2%) and arachidic acid (1%). The composition of fatty acids and the proportion of essential fatty acids significantly differed among the diets. The proportion of essential fatty acids was highest in the control treatment (21%) but low in less diversified (one to three feed) diets (12–13%). This study demonstrates that the fatty acid composition in R. differens can be influenced through diet. Thus, with dietary manipulations, using local plants in Africa, it is possible to produce R. differens with preferred high quality essential fatty acids for human consumption.
Fatty acid composition of muscle, liver, and adipose tissue of freshwater fish from Lake Victoria, Uganda
(Journal of Aquatic Food Product Technology., 2011) Masa, Justus; Ogwok, Patrick; Muyonga, John Herbert; Kwetegyeka, Justus; Makokha, Vincent; Ocen, Denis
Fish oils may differ in fatty acid (FA) composition depending on diet. Oils extracted from muscle, liver, and adipose tissue of Nile perch (Lates niloticus), Nile tilapia (Oreochromis niloticus), silver fish (Rastrineobola argentea), lungfish (Protopterus aethiopicus), Victoria squeaker (Synodontis victoriae), and two catfishes (Clarias gariepinus and Bagrus docmac) from Lake Victoria, a tropical freshwater lake, were evaluated for FA composition. Oil contents of muscles, livers, and adipose tissues were in the range of 3.16 to 13.8%, 3.62 to 53.4%, and 28.8 to 42.4%, respectively. Omega-3 polyunsaturated FA, particularly alpha-linolenic (ALA), eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids, were found to be in substantial amounts in oils from all seven fish species. Ratios of polyunsaturated FA to saturated FA (0.79 to 1.18) were in the range considered adequate for normal health. Overall, the results show that the fish species studied are a rich source of omega-3 polyunsaturated FA.

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