http://erepository.uonbi.ac.ke/handle/11295/13923 Tue, 28 Apr 2026 13:00:44 GMT 2026-04-28T13:00:44Z http://http://erepository.uonbi.ac.ke:80/bitstream/id/c9fa5293-ccd0-4145-b97a-0de4038e1078/ http://erepository.uonbi.ac.ke/handle/11295/13923 http://erepository.uonbi.ac.ke/handle/11295/163698 Mathematical Competitions in Africa: Their Prevalence and Relevance to Students and Teachers Baker, Liam; Labuschagne, Phil; Katende, James; Kariv, Jonathan; Weitbrecht, Jessica; Aloui, Karam Mathematical competitions feature in most developed countries as a part of the secondary school experience, but to a lesser extent in developing countries. In this paper we investigate how widespread these competitions are in Africa, both historically as well as currently, focussing both on national Olympiads and on the participation of African countries in competitions beyond their borders, such as the continent-wide Pan African Mathematical Olympiad and the global International Mathematical Olympiad. Since we could not find a consolidated source of information on African competitions, we include many details and links, hoping that this paper will serve as a valuable starting point for future investigators. Next, we present some survey findings on the attitudes towards and experiences of mathematical competitions, both from the perspective of teachers in secondary schools as well as from secondary school students, and whether these experiences have served to improve or degrade their perceptions of mathematics in general. Among other results, we find that teachers view their students' participation in mathematics competitions as being important, with the biggest barrier to participation being that there are not enough competitions at appropriate levels available, and that students enjoy mathematics competitions and are more likely to pursue a STEM career because of them. Finally, we present some suggestions on how this research may be taken further, and on how the state of mathematical competition culture in Africa may be improved. Sat, 01 Jan 2022 00:00:00 GMT http://erepository.uonbi.ac.ke/handle/11295/163698 2022-01-01T00:00:00Z http://erepository.uonbi.ac.ke/handle/11295/163648 Influence of the pH of anthocyanins on the efficiency of dye sensitized solar cells Okello, Alex; Owuor, Brian O; Namukobe, Jane; Okello, Denis; Mwabora, Julius The influence of the pH of anthocyanins on photovoltaic performance in dye-sensitized solar cells has been investigated. Anthocyanins were extracted from crushed leaf stocks of Manihot esculenta Crantz (Cassava plant) using methanol acidified with 0.5% trifluoracetic acid. The filtrate was concentrated using a rotary evaporator and partitioned against ethyl acetate. The anode was prepared by screen printing TiO2 paste on a previously cleaned fluorine-doped tin oxide (FTO) glass substrate. The cathode was made by applying plastisol on a previously cleaned FTO glass substrate using an artistic brush and later annealed at 450 °C for 20 min to activate platinum. The performance of the solar cells was measured using a solar simulator fitted with an AM1.5 air filter. Electron transport was studied using electrochemical impedance spectroscopy (EIS). It was observed that the short circuit current and efficiency dropped from pH 2 to pH 6 and peaked at pH 8, with values of 0.399 mA and 0.390%, respectively. It then drops further as the basicity increases. The open circuit voltage was observed to increase consistently from pH 2 to pH 12. EIS results showed that the electron density in the conduction band of TiO2 increases from pH 2 to pH 10 and drops from pH 10 to pH 12. It was concluded that, while a large number of electrons ............................................. Sat, 01 Jan 2022 00:00:00 GMT http://erepository.uonbi.ac.ke/handle/11295/163648 2022-01-01T00:00:00Z http://erepository.uonbi.ac.ke/handle/11295/161398 Conglomeratin: a New Antibacterial Flavonol Derivative From Macaranga Conglomerata Brenan (Euphorbiaceae) Hashim, Ibrahim; Onyari, John M; Omosa, Leonidah K; Maru, Shital M; Nchiozem-Ngnitedem, Vaderament-A; Karpoormath, Rajshekhar A new prenylated kaempferol, conglomeratin (1), alongside 7 known compounds including flavonoids (2 and 3), ellagic acid derivatives (4 and 5), triterpenoids (6 and 7), and a coumarin (8)were isolated from the leaves (125) and stembark (628) of Macaranga conglomerata. Their structures were elucidated using spectroscopic and spectrometric techniques. The antibacterial assay was performed using disc diffusion method against Gram-positive and Gram-negative microorganisms. Compound 1 was significantly active against Pseudomonas aeruginosa ATCC 27853 (MIC ¼ 7.8 mg/mL) and moderately active towards Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Klebsiella pneumoniae ATCC 31488 (MIC ¼ 62.5 mg/mL). Compound 2 showed potency against P. aeruginosa ATCC 27853 (MIC ¼ 1.0 mg/mL) while 4 and 7 were selective towards K. pneumoniae ATCC 31488 (MIC ¼ 7.8 and 1.0 mg/mL, respectively). These findings suggest that prenylation of flavonoids may contribute to improving their broad-spectrum antimicrobial activities. Sat, 01 Jan 2022 00:00:00 GMT http://erepository.uonbi.ac.ke/handle/11295/161398 2022-01-01T00:00:00Z http://erepository.uonbi.ac.ke/handle/11295/156031 Water and the UN sustainable development goals Campos, Luiza C; Olago, Daniel; Osborn, Dan Water is essential for life, but we need to balance human needs with those of the environment on which we depend for our wellbeing, our health and much of our wealth. Not all of us are lucky enough to have access to adequate water resources and services linked to water, such as readily available low-cost drinking water and sanitation systems. According to the World Health Organization and United Nations Children’s Fund (WHO/UNICEF), hundreds of millions of people are still without access to safely managed drinking water and sanitation services [1]. Their Joint Monitoring Programme (JMP) report, Progress on Drinking Water, Sanitation and Hygiene 2000–2020 [2], found that although considerable progress has been made in achieving universal access to basic water services, the proportion of improved water sources that are accessible, available and free from contamination varies widely between countries. This indicates that many countries are facing a challenge to meet the Sustainable Development Goal (SDG) target for safely managed services. In addition, despite increasing the rural coverage of safely managed water services in some countries, and in other countries this coverage is similar to the urban coverage, there is a huge gap in terms of water quality. Sat, 01 Jan 2022 00:00:00 GMT http://erepository.uonbi.ac.ke/handle/11295/156031 2022-01-01T00:00:00Z