Publications

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2019
Mwaniki JM, Onyatta JO, Yusuf AO. "Adsorption of Heavy Metal Ions from Aqueous Solutions and Wastewater using Water Hyacinth Powder." Adsorption. 2019;4(1). AbstractAdsorption Journal

ABSTRACT
The adsorption of heavy metals on water hyacinth powder from both
wastewater and aqueous solution was studied using batch experiments. The
adsorption efficiency of water hyacinth powder was evaluated in this study.
The levels of heavy metals in wastewater were in the range of: 1.2-75.3 ppm
for lead, 0.4-87.6 ppm for chromium, 0.1-63.5 ppm for nickel, 0.5-95.5 ppm for
zinc and 0.8-52.7 ppm for cadmium. The levels of zinc, lead and cadmium were
above the limits set by the write NEMA in full then bracket (NEMA) for
discharge into the environment (0.01 ppm for cadmium and lead, 0.5 ppm for
zinc). The adsorption efficiency of hyacinth powder was higher in aqueous
solution than in wastewater while at low metal concentrations (0.1-3.2 ppm),
the adsorption efficiency of water hyacinth powder was 100% in both
wastewater and aqueous solution. The study showed that water hyacinth
powder is a low cost adsorbent which could be used to remove heavy metals
from wastewater and aqueous solution.

Njogu REN, Fodran P, Tian Y, Njenga LW, Kariuki DK, Yusuf AO, Scheblykin I, Wendt OF, Wallentin C-J. "Electronically Divergent Triscyclometalated Iridium (III) 2-(1-naphthyl) pyridine Complexes and Their Application in Three-Component Methoxytrifluoromethylation of Styrene." Synlett. 2019;3007:792-798. AbstractJournal Publication

Description
A systematic study of the photophysical and electrochemical properties of triscyclometalated homoleptic iridium(III) complexes based on 2-(1-naphthyl)pyridine (npy) ligands is presented. A systematic investigation of ligand substitution patterns showed an influence on the lifetime of the excited state, with slight changes in the absorption and emission spectral features. Specifically, the emission lifetime of a complex of an npy ligand substituted with a strongly electron-withdrawing trifluoromethyl group was longer than that of the corresponding complex with the electronically nonperturbed ligand (3.7 μs versus 1.5 μs). Electronically complementary ligands and complexes with orthogonal configurations showed slightly shorter excited state lifetimes compared with unsubstituted npy (1.4–3.0 μs). All complexes displayed reversible or quasireversible redox-couple processes, with the complex of the trifluoromethylated …

2018
Muthee SM, Salim AM, Onditi AO, Yusuf AO. "Concentration Levels of Iron (Fe), Copper (Cu), Lead (Pb), Cadmium (Cd), Chromium (Cr) and Selected Nutrients in Water of Motoine River Channel, Kibera, Kenya." Chemical Science International Journal. 2018;24(1):1-8. AbstractJournal article

Abstract

The need for clean and safe consumable water is of paramount importance to any society since water is a crucial substance for the sustenance of life. Kibera slum is one of the leading slums in the world with a high population, leading to poor levels of sanitation and inadequate clean water supply. Consequently, the residents have to seek for alternative water supply. Motoine River flows through the slum, and thus acts as an alternative source of water. This study determined the concentration levels of heavy metals (Pb, Fe, Cu, Cr and Cd) and nutrients (nitrates, nitrites and phosphates) in Motoine River, Kibera in September 2014 and compared the variations downstream. The metals were determined using Atomic Absorption Spectroscopy (AAS) while the nutrients were determined using UV/Visible spectroscopy. Concentration levels of Cu, Cd and Cr were found to be lower than the Environmental Protection Agency (EPA) values for maximum contaminant level (MCL) while those of Fe, Pb and the nutrients were higher than EPA’s MCL values. Cd had the lowest concentration and was below the detection limit of the instrument used. Nitrates were found to be of the highest concentration at 16.4959 ± 2.4432 parts per million (ppm). The high concentration of nutrients in the water could be due to domestic waste and effluent disposal into the river and agricultural runoffs while that of metal ions could be due to waste from informal jua kali industries and erosion of natural deposits. The efforts by the government to rehabilitate and clean rivers within Nairobi should be extended to include Motoine River.

Barnabas TM, Yusuf AO, Arowolo KO. "Impacts of adaptation strategies of climate change on rice production in Kwara State." Journal of Agricultural Research and Development. 2018;17(1):102-114. AbstractJournal article

Description
The study was to determine the effectiveness of adaptation strategies of climate change on rice production, it specifically identified the adaptation strategies employed and described the determinants of the strategies. Both descriptive and inferential statistics were used to analyze data. Adaptation strategies employed by the respondents were planting of early maturing variety (89.2%), planting of improved variety (85.0%) and change in planting date (76.7%). Determinants of adaptation strategies were educational attainment, farming experience, age, climate information, cooperative membership, extension contact and farm size. Planting of improved and early maturing variety with a mean score of x̄꞊ 3.75 and x̄꞊ 3.66 respectively were adjudged the most effective adaptive strategies that could help in the production of rice in the study area. Use of irrigation, mixed farming; soil conservation and off-farm activities were effective as adaptation strategies in mitigating the adverse effect of climate change on rice production. Therefore, it was recommended that government policies should ensure that farmers have access to timely, affordable and adequate credit to increase their ability and flexibility to change production strategies in response to climate change, Similarly, adequate and timely information should be made available to farmers in order to keep them alert about the constant changes in climate.

Korir PC, Salim AM, Odalo JO, Waudo W, Gitu LM, Yusuf AO. "Optimization of Extraction Condition and Characterization of Malva Verticillata Root Bark Mucilage." International Journal of Chemistry. 2018;10(2):1-9. AbstractInternational Journal of Chemistry

Description
The study aimed at optimizing the extraction conditions and establishing the physicochemical properties of the mucilage obtained from root bark of Malva verticillata. Effects of temperature, time, particle size and amount of water as a solvent on the yield and composition of mucilage were established. Micrometric, physical, chemical and structural properties were used to characterise the extracted mucilage. Result showed significant correlation between extraction conditions and mucilage yield. Low temperature and short extraction time results into pharmaceutically valuable mucilage with low protein content, high viscosity and good dispersion in aqueous solvent. Large and small size particles of the plant material results into low mucilage yield without significant difference (p= 0.054). The mucilage shows mixed cohesiveness with less tendencies to flow. It exhibits vibration bands in FTIR that are associated with the presence of polysaccharides and proteins. The mucilage contains 2.65% protein, 13.83% inorganics, 1.85% fats, and the rest carbohydrates. High extractive value˃ 80% and moisture content˃ 12% implies that mucilage has high tendency to microbial attack. Optimized extraction conditions results into high yield of the mucilage with the same physicochemical properties and mineral composition regardless of the plant material sampling sites.

Ooko JO, J.O. O, A.O. Y, P.M. G. "Use of accelerated tests to estimate corrosion rates of roofing sheets." International Journal of Sciences. 2018;37(3):1-8.publication_juspher_onyatta_yusuf_guto.pdf
2017
Birgen J, Yusuf AO, Wafula G, Onyatta JO. "Assessment of sulphur dioxide levels in selected sites in Athi River, Kenya." International Journal of Trend in Scientific Research and Development. 2017;1(5):416-422.scan_trend.pdf
2016
2015
V. S, J. K, B. O, A. Y, M. K. "In-vitro anthelmintic activity of vernonia amygdalina Del. (asteraceae) roots using adult Haemonchus contortus worms." International Journal of Pharmacological Research. 2015;5(1):1-7.vernonia_amygdalina.pdf
2014
Yusuf A, Gitu P, Bhatt B, Njogu M, Salim A, Orata D. "1-Tetralinyl as carboxamide protecting group for asparagines and application to N-alpha-t-butyloxycarbonyl (Boc) solid-phase peptide synthesis of oxytocin." chemistry and materials research. 2014;6(2):1-11.
Muiva L, Macharia B, Akala H, Derese S, Omosa LK, Yusuf A, Kamau E, Koch A, Heidenreich M, Yenesew A. "6a-Hydroxy-α-toxicarol and (+)-Tephrodin with antiplasmodial activities from Tephrosia species." Phytochemistry Letters. 2014;10:179-183.scan0062.pdf
Yusuf A, Gitu P, Bhatt BM, Njogu M, Salim A, Orata D. "Solid-Phase Peptide Synthesis of Arginine-vasopressin With Amide Side chain of Asparagine Protected With 1-Tetralinyl Group." Journal of Chemistry & Materials Research. 2014;6(4):60-65.
Yusuf AO, Gitu PM, Bhatt BM, Njogu M, Salim A, Orata D. "Solid-Phase Peptide Synthesis of Arginine-vasopressin With Amide Side chain of Asparagine Protected With 1-Tetralinyl Group." Journal of Chemistry & Materials Research. 2014;6(4):60-65.cmr_spps_arg_vaso.pdf
Orata D, Yusuf AO, Nineza C, Mukabi M, D. M. "Surface Modified Electrode Used In the Electro-Analysis of N- Acetyl P-Aminophenol- A Pharmaceutical Drug ." Journal of Applied Chemistry. 2014;7(5):90-99.iosr_7_5_2_2014_acetyl.pdf
Orata D, Yusuf AO, Nineza C, Mbui D, Mukabi M. "Surface modified electrodes used in cyclic voltammetric profiling of quinine, as antimalarial drug." Journal of Applied Chemistry. 2014;7(5):81-89.iosr_7_5_2_2014_quinine.pdf
Orata D, Yusuf A, Nineza C, Mbui D, Mukabi M. "Surface modified electrodes used in cyclic voltammetric profiling of quinine, as antimalarial drug”." IOSR Applied Chemistry. 2014;7(5, ver II):81-89.scan0001.pdf
2011
2010
Mbugua P, Salim A, Onditi A, Yusuf A. "Determination of Micronutrients and micronutrients in Soil Samples from Around Lake Ol-Bolossat." Int. J. Biol. Sci.. 2010;2(8):140-148.scan0016.pdf
DM K, A S, A O, A Y. "Environmental effects of selected chemical and physical geothermometers at Olkaria Geothrmal power plant." Journal of Sustainable Development. 2010;3(6):14-25. Abstractscan0015.pdfWebsite

21) S. Derese, A. Yenesew, J.O. Midiwo, Heydenreich and M.G. Peter. (). ..

2007
Mbugua MN, Yusuf AO, Bhatt BM, P.M. G. "CONVERSION OF VERNONIA GALAMENSIS OIL TO PYRIDINYLVERNOLAMIDES AND THEIR ANTIMICROBIAL ACTIVITIES ." Bulletin of the Chemical Society of Ethiopia. 2007;21(1):103-110.bcse_21_1_vernonia_galamensis_2007.pdf
2006
2005
SA O, PF M, GJ S, J M, S K, GA O, HD. S. "Plasmodium falciparum: evaluation of a quantitative nucleic acid sequence-based amplification assay to predict the outcome of sulfadoxine-pyrimethamine treatment of uncomplicated malaria.". 2005. AbstractFull text link

A quantitative nucleic acid sequence-based amplification (QT-NASBA) assay was employed to predict retrospectively the outcome of sulfadoxine-pyrimethamine (SP) treatment of uncomplicated malaria in children aged <6 years in an endemic region. Blood samples were collected at initial diagnosis and during follow-up. Mutation-specific nested PCR methods to analyse DHFR (Arg-59) and DHPS (Glu-540) mutations that are associated with SP drug resistance were applied. Parasite genotyping was performed to distinguish between re-infection and recrudescence. Eighty-six patients were recruited of which 66 were available for follow-up. Nine children were classified as early treatment failure, 13 cases were classified as late clinical failure, 32 as late parasitological failure, and only 12 children had an adequate clinical and parasitological response. DHFR and DHPS mutations conferring SP resistance were abundant in the Plasmodium population. Blood samples obtained 7 days after treatment were used to predict retrospectively the outcome of SP treatment. QT-NASBA was able to give a correct prediction of treatment outcome in 85.7% of the cases. Positive predictive value (PPV) of QT-NASBA case was 95% (95% confidence interval = 88.3-100) and negative predictive value (NPV) was 63% (95% CI = 39.5-86.5). In contrast, microscopy correctly predicted outcome in only 37.5% of the cases. PPV of microscopy was 100% (95% CI = 73.9-100) and the NPV was 25.5% (95% CI = 13.0-38.0). The analysis of a day 7 blood sample with QT-NASBA allows for the prediction of late clinical or parasitological treatment failure in the majority of the cases analysed in the present study.

2004
Yusuf A. Organic Chemistry 2 (SCH 202). Nairobi: University of Nairobi Press; 2004.scan0023.pdf
2002
2001
1998
Gitu P, Yusuf A, Ogutu V. "Application of tetralinyl group in solid-phase peptide synthesis." Int. J. BioChemiPhysics. 1998;6,7(1,2):7-10.scan0055.pdf
Gitu PM, Yusuf A, Bhatt BM. "Application of tetralinyls as carboxamide protecting groups in peptide synthesis." Bulletin of the Chemical Society of Ethiopia. 1998;12(1):35-43.bcse_12_1_1998.pdf
YUSUF DROKEYOAMIR. "Solid-phase peptide syntheses of oxytocin, oxytocin analogs and interferon short chain with the amide side-chain functionality of asparagine protected with 1-tetralinyl group.". In: Doctor of Philosophy in Chemistry. Journal of the Kenya Chemical Society; 1998. Abstract
1-Tetralone was converted to 1-aminotetralin. This amine was then used to protect the carboxamide side-chain of asparagine. Syntheses of oxytocin and its derivatives were then done via Boc-solid-phase peptide synthesis using this protected asparagine. After syntheses of the nonapeptide resins, cleavage and eventual cyclization of the hormones was done using trifluoromethane sulphonic acid at 40 degrees Celcius for two hours.
1993
Bhatt B, Gitu P, Yusuf A. "Synthesis of 1-aminotetralin and its derivatives by reductive amination of their corresponding 1-tetralones"." Int. J. BioChemiPhysics. 1993;2(1,2):55-77.
YUSUF DROKEYOAMIR. "Synthesis of 1-aminotetralin and its derivatives by reductive amination of their corresponding 1-tetralones.". In: Int. J. of BioChemiPhysics. Journal of BiochemiPhysics; 1993. Abstract
Tetralones were converted to their corresponding N-formyl derivatives using ammonia and formic acid at 170-180 degrees Celsius. These were then hydrolyzed to the corresponding amines using acid and base. In all cases base hydrolysis gave better yields as compared to acid hydrolysis.
1989

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