Journal Articles

Permanent URI for this collectionhttp://localhost:4000/handle/20.500.12504/98

Browse

Now showing 1 - 20 of 42

Fatty acid profile and stability of oil from the belly flaps of Nile perch (Lates niloticus)
(Elsevier: Food Chemistry., 2008-05-01) Ogwok, P.; Muyonga, J.H.; Sserunjogi, M.L.
Oil extracted from the belly flaps of Lake Victoria Nile perch (Lates niloticus) was evaluated for fatty acid composition, contents of vitamin A, β-carotene and α-tocopherol, and oxidative stability. The oil was found to contain substantial amount of palmitic, palmitoleic, stearic, oleic, docosapentaenoic and docosahexaenoic fatty acids (FAs) and had high vitamin A content (3.94 ± 0.02 to 5.90 ± 0.02 mg/100 g of oil). Docosahexaenoic acid (10.45 ± 0.38%), docosapentaenoic acid (5.30 ± 0.60%) and eicosapentaenoic acid (3.63 ± 0.05%) were the most dominant polyunsaturated fatty acids (PUFAs). Ratios of PUFAs to saturated FAs were in the range 0.68 ± 0.02 to 0.74 ± 0.03, while the ratio of total ω-3 FAs to total ω-6 FAs was 0.85 ± 0.02 to 0.95 ± 0.08. The oils showed exceptional resistance to accelerated oxidation at 65 °C probably because of its high content of β-carotene (2.93 ± 0.03 to 4.69 ± 0.01 mg/100 g of oil) and α-tocopherol (2.11 ± 0.03 to 11.4 ± 0.92 mg/100 g of oil). From the results, it can be concluded that Nile perch oil is a rich source of essential fatty acids and vitamin A.
Pesticide residues and heavy metals in lake Victoria nile perch, lates niloticus, belly flap oil
(Springer Link: Bulletin of Environmental Contamination and Toxicology., 2009-03-05) Ogwok, P.; Muyonga, J. H.; Sserunjogi, M. L.
Oil was extracted from the belly flaps of varied sizes of Nile perch caught from Lake Victoria (Uganda). The oil was analyzed for pesticide residues and heavy metals. Total residual concentration of dichlorodiphenyltrichloroethane, endosulfan, hexachlorocyclohexane, hexachlorobenzene, heptachlor, chlordane, endrin, aldrin and chlorofenvinphos increased significantly (p < 0.05) with fish size. Mercury and lead were detected in most samples while arsenic and cadmium were below detection limits. Nile perch may, therefore, accumulate significant amount of chemical contaminants. Levels of contaminants in Nile perch oil were, in general, within limits considered acceptable by the stringent German Food Law for human consumption.
Speciation of heavy metals in water from the Uganda side of Lake Victoria
(International Journal of Environmental Studies, 2010-02) Jolocam, Mbabazi; H., Twinomuhwezi; J., Wasswa; M., Ntale; G., Mulongo; J., Kwetegyeka; K.H., SchrǾder
Different forms of copper Cu, zinc Zn, lead Pb and cadmium Cd in water from the Uganda side ofLake Victoria (25°C, pH 6.75–7.18), the second largest inland freshwater lake in the world, havebeen studied using ion-exchange, dialysis and atomic absorption spectrophotometry. The resultsindicate that heavy metals Cu, Zn, Pb and Cd are present mainly in the cationic form (80–83%).Small quantities of anionic (13–22%), non-ionic, dialyzable (4–8%), and non-ionic, non-dialyzable(< 1.3–4.4%) forms were also detected for all metals except Cd. The corresponding concentrationslay in the ranges: cationic, 0.06–0.99; anionic, < 0.001–0.25; non-ionic, dialyzable, < 0.001–0.08;non-ionic, non-dialyzable, < 0.001–0.06 μg ml−1. The existence of the metals in non-ionic and non-dialyzable forms is attributable to metal associations with high relative molecular mass (RMM)organic matters.
Speciation of heavy metals in water from the Uganda side of Lake Victoria
(International Journal of Environmental Studies., 2010-02-15) Mbabazi, Jolocam; Twinomuhwezi, H.; Wasswa, J.; Ntale, M.; Mulongo, G.; Kwetegyeka, J.; SchrǾder, K.H.
Different forms of copper Cu, zinc Zn, lead Pb and cadmium Cd in water from the Uganda side of Lake Victoria (25°C, pH 6.75–7.18), the second largest inland freshwater lake in the world, have been studied using ion‐exchange, dialysis and atomic absorption spectrophotometry. The results indicate that heavy metals Cu, Zn, Pb and Cd are present mainly in the cationic form (80–83%). Small quantities of anionic (13–22%), non‐ionic, dialyzable (4–8%), and non‐ionic, non‐dialyzable (< 1.3–4.4%) forms were also detected for all metals except Cd. The corresponding concentrations lay in the ranges: cationic, 0.06–0.99; anionic, < 0.001–0.25; non‐ionic, dialyzable, < 0.001–0.08; non‐ionic, non‐dialyzable, < 0.001–0.06 µg ml−1. The existence of the metals in non‐ionic and non‐dialyzable forms is attributable to metal associations with high relative molecular mass (RMM) organic matters.
Heavy metal contamination in vegetables cultivated on a major urban wetland inlet drainage system of Lake Victoria, Uganda
(International Journal of Environmental Studies, 2010-06) Jolocam, Mbabazi; J., Wasswa; J., Kwetegyeka; G.K., Bakyaita
The population of the Ugandan capital, Kampala, located close to Lake Victoria, appears to be exposed to risk of ingesting the heavy metals Cadmium (Cd) and Lead (Pb) through vegetables in their diet. Lake Victoria is responsible for frequent torrential polluted runoffs in the city. The Nakivubo channel, the city’s major wetland drainage system, empties directly into the lake. Vegetables are grown on the urban wetland soils. Heavy metal content in vegetables from the wetland cultivation sites was determined by wet acid digestion, with 87–92% recovery. The results showed that although the heavy metal levels of manganese (Mn), zinc (Zn), cadmium (Cd) and lead (Pb) were significantly higher than those in similar food crops from rural control sites, only Cd and Pb exceeded the World Health Organisation (WHO) maximum permissible levels. Cd and Pb pose serious human health risks. Early pollution control measures are advisable.
Ineffectiveness of Nakivubo wetland in filtering out heavy metals from untreated Kampala urban effluent prior to discharge into Lake Victoria, Uganda
(African Journal of Agricultural Research, 2010-12) Jolocam, Mbabazi; J., Kwetegyeka; M., Ntale; J., Wasswa
The population of the Ugandan capital city of Kampala has dramatically increased since the political turmoil of the 1970s and with it a considerable rise in industrialisation. Few manufacturing plants, however, have pretreatment installations in place for their polluted effluent prior to discharge into the surrounding ecosystems. Kampala’s main drainage system is the Nakivubo channel which empties directly into the neighbouring Lake Victoria, the second largest inland freshwater lake in the world. Increased urban effluent load coupled with reclamation for crop farming have considerably reduced the effectiveness of the wetland to filter out major pollutants, in particular heavy metals. Using atomic absorption spectrophotometry, this study showed that the efficiency in sieving out zinc (Zn), copper (Cu), cadmium (Cd) and lead (Pb) has shrunk from 89.7 – 98.3% in December 2006 to 79.4 – 92.1% in December 2008, over a period of three consecutive years. This is indicative of the growing ineffectiveness of the wetland to absorb heavy metals. Levels of the same metals in the lake water some two kilometres away from the mouth of the wetland have correspondingly increased from 23 - 31% to 35 - 47% in the same period. This poses a serious threat to the quality of the fish and to the over two million urban population that directly depend on the lake water for domestic and industrial use. The remedy lies in the relevant authorities to enforce pretreatment at each factory site, increased factory management sensitisation on environmental concerns and more stringent measures against wetland encroachment.
Nitrification in modified sewerage stabilisation ponds prior to discharge into the Ugandan side of Lake Victoria
(International Journal of Environmental Studies., 2010-12-08) Mbabazi, Jolocam; Wanasolo, W.; Gava, J.; Kwetegyeka, J.
Large volumes of wastewater in the Ugandan capital Kampala have seriously polluted Lake Victoria, from which the city draws its freshwater. Untreated effluent drains directly into this lake. In tropical temperatures, oxidation ponds are used for wastewater treatment, especially for organic matter. This technology should be the focus of work to improve its efficacy, and thus to secure the sustainability of the lake and its freshwater fish which are marketed worldwide. A pilot scale plant was set up comprising an anaerobic tank, a facultative pond and four fibre‐glass maturation tanks. The total nitrification rates in the tanks T1–T4 were 5.5, 7.5, 10.1 and 6.4 (±0.4) mg‐N/l/day, respectively. For more efficient wastewater treatment stabilisation pond systems, a modification similar to that in T3 should be considered. T3 was constructed with biofilm attachment surfaces in a manner which allowed effluent to be channelled round them, contrary to direct T1 flow which is currently in use.
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.
Small tropical reservoirs and fish cage culture: a pilot study conducted in Machakos district, Kenya
(Aquaculture International., 2011-01-07) Kaggwa, Mary N.; Liti, David M.; Schagerl, Michael
The findings of this study provide useful insights into the key aspects of fish cage farming to be considered during setting and overall management of multi-purpose water resources so as to maximise their aquacultural potential. The study was conducted in Machakos District, Kenya, to characterise limnochemistry and algal composition of three small man-made reservoirs Ngeki, Ngei and Kavovi, used for cage culture of Nile tilapia (Oreochromis niloticus). In Ngeki, the open water was compared with areas in between the cages and significant differences in dissolved oxygen were found. For N, P and chlorophyll-a, no differences were noticed. In all the reservoirs, temporal variations were noticed for all parameters except NO3N and NH4N. Peak concentrations of nutrients occurred during the rainy season with lower values in the dry season (below detectable limits for SRP). All reservoirs were classified as hyper-eutrophic with a strong positive correlation between chlorophyll-a and TP. Algal abundances changed with season. Chlorophyta dominated at the start of the rainy season, while cyanobacteria prevailed at the onset of thermal stratification. Diatoms prevailed in the dry season but were notably absent in the rainy season. It was concluded that all the reservoirs are suitable for cage culture of Nile tilapia, but this should be undertaken with caution considering critical periods when anoxic conditions may occur.
Fatty acids of polar lipids in heart tissue are good taxonomic markers for tropical African freshwater fish
(African Journal of Aquatic Science, 2011-07) J, Kwetegyeka; J, Masa; BT, Kiremire; GB, Mpango; O, Grahl-Nielsen
The fatty acid profiles in total, neutral and polar lipids in the heart tissues of five freshwater fish species (Nile perch Lates niloticus, Nile tilapia Oreochromis niloticus, marbled lungfish Protopterus aethiopicus, Bagrus docmak and African catfish Clarias gariepinus) from Lakes Victoria and Kyoga were determined chemometrically by methanolysis of the lipid extracts and gas chromatography of the resulting methyl esters. The analytical data were treated using multivariate principal component analysis. In neutral and polar lipids palmitic acid (16:0) and stearic acid (18:0) were the dominant saturated fatty acids. The polyunsaturated fatty acids in the polar lipid fraction ranged from 33% to 56% and in the neutral lipid fraction from 23% to 30%, dominated by arachidonic acid (20:4n6) and docosahexaenoic acid (22:6n3). The amount of cholesterol in the neutral fraction was 57–89 mg g –1 lipid. The amount of plasmalogen was 12–27 mg g–1 and 14–37 mg g–1 lipid in the polar fraction and total lipid, respectively. In the principal component plots, the fish species from the two lakes were distinguished by fatty acid profiles in neutral, polar and total lipid from the heart tissue. However, polar lipid fractions were better markers of fish species and populations than the neutral fraction and total lipids. Heart tissues have low lipid levels dominated by polar lipids (phospholipids), with polyunsaturated fatty acids as the principal components. The dominance of genetically controlled phospholipids in the heart tissue makes heart tissue most suitable for differentiating between species and populations.
Nutrient alterations in Nile perch (Lates niloticus) skins owing to various processing and cooking techniques
(International Journal of Environmental Studies, 2012-01) Margaret, Kabahenda; Jolocam, Mbabazi; Justus, Kwetegyeka; Ronald, Amega
Nile perch (Lates niloticus) skin is a major substitute for whole fish especially among low-income groups who are especially vulnerable to protein and micronutrient deficiencies. The object of this study was to determine the extent of nutrient alterations that occur in Nile perch skins when sub- jected to various processing and cooking techniques. Whereas the study showed that Nile perch skins are rich sources of zinc, iron, calcium and lipids, their content is significantly altered by the various preparative methods currently in use.
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.
Phytoplankton patterns along a series of small man-made reservoirs in Kenya
(Environmental Monitoring and Assessment., 2014-04-10) Straubinger-Gansberger, Nadja; Kaggwa, Mary N.; Schagerl, Michael
We studied nine small man-made reservoirs located in different climate regions of Kenya to get an insight into the relationship between phytoplankton community structure and its environment. The investigated ponds form three groups of three reservoirs each found in the rural areas of Machakos district, Mount Kenya region, and Lake Victoria area with varied climatic characteristics. The ponds were sampled in monthly intervals between May 2007 and June 2008 for physicochemical variables including water chemistry, phytoplankton community composition, zooplankton abundance, and bacterial numbers. All ponds were classified as hypertrophic. Seasonal changes were reflected in the phytoplankton pattern, as all ponds showed a community shift after the short dry season in February. Due to high nutrient loads and increased turbidity, Cyanobacteria, which were initially thought to be predominating in all investigated water bodies, were found to play only a minor role except for the Bomet reservoir in Lake Victoria region. Instead, Chloro- and Streptophyta, Dinophyta, and Euglenophyta were abundant in the pelagial. A principal component analysis explained around 85 % of the data variance with four principal components (PCs) interpreted as “location”, “ions”, “zooplankton”, and “particulate matter”. A clear separation of ponds with and without cattle access based on algal species community data was found indicating the need for a sustainable use and regular monitoring program as the local population is largely dependent on these sensitive small-scale ecosystems.
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.
Performance of Egg-Shell and Fish-Scale as Adsorbent Materials for Chromium (VI) Removal from Effluents of Tannery Industries in Eastern Uganda
(Open Access Library Journal, 2017-08-16) Bamukyaye, Sam; Wanasolo, William
The performance of egg-shells and fish-scales biomaterials in separating chromium (VI) ions from tannery effluents obtained from tannery industries in Jinja town of Eastern Uganda was investigated. Using crushed egg-shell and fish-scales as adsorbents, sorption tests were carried out to determine the effects of bio-sorbent concentration and particle size on chromium (VI) removal. The adsorbate concentration in the tannery effluents before and after adsorption was analyzed using the UV-vis Spectrophotometer at wavelength of 540 nm. The adsorbent concentration was calculated from concentration change in aqueous solution before and after equilibrium sorption. Results showed that chromium (VI) ions adsorb on the surfaces of both biomaterials. The optimum conditions for chromium (VI) removal were found at pH of 6.8, particle size of 300 μm and bio-sorbent concentration of 0.5 g. The correlation coefficient (R2) showed that chromium (VI) adsorption fitted Langmuir adsorption isotherms. It was concluded that the adsorption process of chromium (VI) on the fish-scales and egg-shells was highly feasible.
Utilization of solid waste as a substrate for production of oil from oleaginous microorganisms
(Hindawi: Journal of Lipids, 2018-05-16) Laker, Fortunate; Agaba, Arnold; Akatukunda, Andrew; Gazet, Robert; Barasa, Joshua; Nanyonga, Sarah; Wendiro, Deborah; Wacoo, Alex Paul
The overwhelming demand of oil and fats to meet the ever increasing needs for biofuel, cosmetics production, and other industrial purposes has enhanced a number of innovations in this industry. One such innovation is the use of microorganisms as alternative sources of oil and fats. Organic solid waste that is causing a big challenge of disposal worldwide is biodegradable and can be utilized as substrate for alternative oil production. The study evaluated the potential of isolated yeast-like colonies to grow and accumulate oil by using organic solid waste as substrate. Of the 25 yeast-like colonies isolated from the soil samples collected from three different suburbs in Kampala district, Uganda, 20 were screened positive for accumulation of lipid but only 2 were oleaginous. The NHC isolate with the best oil accumulation potential of 48.8% was used in the central composite design (CCD) experiments. The CCD experimental results revealed a maximum oil yield of 61.5% from 1.25 g/L cell biomass at 10 g/L of solid waste and temperature of 25°C. The study revealed that organic solid waste could be used as a substrate for microbial oil production.
Lignosulfonate biomass derived N and S co-doped porous carbon for efficient oxygen reduction reaction
(Royal Society of Chemistry., 2018-06-26) Zhang, Mingli; Song, Yanliang; Tao, Hengcong; Yan, Chao; Masa, Justus; Liu, Yongchao; Shi, Xiaoyou; Liu, Shizhen; Zhang, Xu; Sun, Zhenyu
Finding sustainable, active, inexpensive, and stable electrocatalysts to replace Pt-based materials for the oxygen reduction reaction (ORR) remains a significant challenge. Here we report the use of functionalized lignin biomass as both carbon and dopant source for the direct synthesis of N and S dual-doped carbon sheet networks with abundant mesopores and high surface area. The resulting N and S-doped porous carbon exhibits good activity, long-term durability, and high selectivity for metal-free oxygen reduction electrocatalysis, approaching the performance of 20 wt% Pt/C, the state of the art ORR catalyst. Our method using natural biological resources thus offers a promising way to produce very promising noble metal-free ORR catalysts with potential application in alkaline fuel cells and metal–air batteries.
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.
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.
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.

Browse

Browsing Journal Articles by Issue Date