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Magana A.M.,Egerton University | Magana A.M.,Chuka University | Dobson M.,The Landing | Mathooko J.M.,Egerton University
Inland Waters | Year: 2012

We compared 2 methods for sampling the freshwater crab Potamonautes odhneri (Colosi) in Kenyan streams: standard Surber sampling, in which a sample is taken over a period of several minutes; and rapid Surber sampling, in which the process is reduced to around 10 seconds. Rapid Surber sampling caught more crabs than standard Surber sampling, This suggests that the crab species investigated is normally able to evade capture if sampling is carried out at an unhurried pace, but that if precision is sacrificed for speed, then capture efficiency increases. The size of crabs caught using the 2 techniques was similar, and use of baited traps set in the same locations showed that Surber sampling methods were not capturing larger individuals. Like all methods available to sample large benthic crustaceans, rapid Surber sampling has its limitations, but this study demonstrates that it can be used as a method for rapid assessment of crab presence and for comparative determination of population density, to significantly greater effect than the standard method of Surber sampling. © International Society of Limnology 2012.


Mbaabu P.R.,Chuka University | Hussin Y.A.,University of Twente | Weir M.,University of Twente | Gilani H.,International Center for Integrated Mountain Development | Gilani H.,LIAONING Technical University
Journal of the Indian Society of Remote Sensing | Year: 2014

The impact of forest management activities on the ability of forest ecosystems to sequester and store atmospheric carbon is of increasing scientific and social concern. This is because a quantitative understanding of how forest management enhances carbon storage is lacking in most forest management regimes. In this paper two forest regimes, government and community-managed, in Kayar Khola watershed, Chitwan, Nepal were evaluated based on field data, very high resolution (VHR) GeoEye-1 satellite image and airborne LiDAR data. Individual tree crowns were generated using multi-resolution segmentation, which was followed by two tree species classification (Shorea robusta and Other species). Species allometric equations were used in both forest regimes for above ground biomass (AGB) estimation, mapping and comparison. The image objects generated were classified per species and resulted in 70 and 82 % accuracy for community and government forests, respectively. Development of the relationship between crown projection area (CPA), height, and AGB resulted in accuracies of R2 range from 0.62 to 0.81, and RMSE range from 10 to 25 % for Shorea robusta and other species respectively. The average carbon stock was found to be 244 and 140 tC/ha for community and government forests respectively. The synergistic use of optical and LiDAR data has been successful in this study in understanding the forest management systems. © 2014, Indian Society of Remote Sensing.


Otachi E.O.,University of Vienna | Otachi E.O.,Egerton University | Magana A.E.M.,Chuka University | Jirsa F.,University of Vienna | And 2 more authors.
Parasitology Research | Year: 2014

In Lake Naivasha, the common carp Cyprinus carpio L. 1758 was accidentally introduced from fish farms adjacent to River Malewa in 1999 and now forms the bulk of the total fish caught. Since its introduction, no study has been made on its parasitic community nor are there any reports on ectoparasites from other fish species in this lake to the best of our knowledge. Therefore, the aim of this study was to describe the parasitic community of C. carpio and two other commercially important fish species: Oreochromis leucostictus and Tilapia zillii. Additionally, the abundant Barbus paludinosus was included in the study. A total of 286 fish (145C. carpio, 56 O. leucostictus, 18 T. zillii, and 67 B. paludinosus) were collected during the year 2011 and examined. Ten taxa of parasites were recovered from C. carpio dominated by the monogenean Dactylogyrus minutus, occurring with a prevalence (p) of 99.3 %. Thirteen taxa of parasites were identified from O. leucostictus dominated by monogeneans Cichlidogyrus spp. (p = 91.1 %). T. zillii harbored nine taxa of parasites with the digenean Tylodelphys sp. (p = 83.3 %) being dominant and B. paludinosus harbored 11 taxa of parasites dominated by an unidentified monogenean of the genus Dactylogyrus (p = 83.6 %). C. carpio had the lowest helminth species diversity and richness while monogenetic trematodes, which have never been reported from fish in Lake Naivasha, were the most prevalent parasites recovered. © 2014 Springer-Verlag Berlin Heidelberg.


Odhiambo R.,Kenyatta University | Muthakia G.K.,Kenyatta University | Kagwanja S.M.,Chuka University
Bulletin of the Chemical Society of Ethiopia | Year: 2010

New complexes derived from the reaction of Mo(NO)Tp* Cl2 = Tp* = tris(3,5-dimethylpyrazolyl) borate with a series of manganese(II) Schiff bases have been synthesized. Characterization by UV, IR, MS and elemental analysis support their formulations. Cyclic and differential pulse voltammograms of manganese(II) Schiff base monometallic complexes exhibit one reduction peak which may be associated with the reduction of the manganese(II) center. In CH3CN solutions, the molybdenum(II)-manganese(II) bimetallic complexes showed two reversible reduction peaks which are associated with the reduction of the molybdenum and manganese centers. In CH2Cl2, only the reduction of molybdenum(II) center exhibited reversibility while the reduction of manganese(II) center was irreversible. These observations demonstrate that reduction potentials for bimetallic complexes are solvent dependent. © 2010 Chemical Society of Ethiopia.


Kamweru P.K.,Chuka University | Tindibale E.L.,Egerton University
International Journal of Medicinal Mushrooms | Year: 2016

Vitamin D may have an important role in many aspects of human health, from bone fractures to prostate cancer, cardiovascular disease, neuromuscular problems, and diabetes. Vitamin D is produced in the human body by the skin after sunlight absorption, but as human lifestyles change, so does the time of exposure to sunlight, necessitating dietary supplementation of vitamin D. Mushrooms have the advantages that they are the only source of vitamin D in the produce aisle and they are one of the few nonfortified food sources. Here, we review the current literature on enhancement of the vitamin D content in mushrooms and literature evidence on the bioavailability of vitamin D in humans and animals after ingesting ultraviolet (UV)-irradiated mushrooms. We also present available literature on health safety after UV irradiation of mushrooms, and we discuss issues arising in the attempt to incorporate UV irradiation into the mushroom production line. © 2016 Begell House, Inc.


Odhiambo R.A.,University of Nairobi | Muthakia G.K.,Kenyatta University | Kagwanja S.M.,Chuka University
Transition Metal Chemistry | Year: 2012

Mo(NO)T p * Cl 2 (T p * = 3,5-dimethyl pyrazole) when reacted with m-functionalized Fe(III) Schiff base complexes; the Schiff base ligands being derived from condensation of 2,4-dihydroxybenzaldehyde or salicylaldehyde with a variety of x,Ω-diamines [1,2-C 6H 4(NH 2) 2, NH 2(CH 2)nNH 2; n = 2-4] affords bimetallic complexes containing two potential reduction centers. The compounds were characterized by physicochemical and spectroscopic methods. It is shown that as the polymethylene carbon chain of the Schiff base backbone increases, the physicochemical and spectroscopic properties also change gradually. Electrochemical data show that the m-functionalized complexes reduce at potentials less cathodic than their psubstituted analogues. It is also shown that the redox potentials are solvent dependent. © Springer Science+Business Media B.V. 2012.


PubMed | Masinde Muliro University of Science and Technology, P.A. College and Chuka University
Type: Journal Article | Journal: Environmental monitoring and assessment | Year: 2016

The detection of antibiotics in water systems has instigated great environmental concern due to the toxicological effects associated with these compounds. Their discharge into the environment results from the ubiquity of use in medical, veterinary, and agricultural practices. Some of the effects of antibiotics include development of antibiotic-resistant bacteria, making it difficult to treat diseases, variation in natural microbial communities, and enzyme activities. In this study, the first comprehensive survey of some frequently used antibiotics namely ampicillin (AMP), amoxicillin (AMX), sulfamethoxazole (SMX), chloramphenicol (CAP), and ciprofloxacin (CPF) within Lake Victoria Basin of Kenya is presented. Sludge and wastewater samples were collected from wastewater treatment plants (WWTPs) and hospital lagoons within the study area. Samples were extracted and cleaned by solid-phase extraction, and analysis was carried out using high-performance liquid chromatography (HPLC). All wastewater samples and sludge collected contained quantifiable levels of the selected antibiotics. The highest concentrations were recorded for AMP with WWTPs and hospitals having 0.360.04 and 0.790.07g/L, respectively. In sludge samples, SMX recorded the highest concentrations of 27612ng/g. The high levels in sludge indicate the preferential partition of antibiotics onto solid phase, posing great danger to consumers of crops grown in biosolid-amended soils. The daily discharge loads of antibiotics from nine WWTPs ranged between 80.75 and 3044.9mgday(-1) with a total discharge of 6395.85mgday(-1), signifying a high potential of water resource pollution within the region. This report will aid in the assessment of the risks posed by antibiotics released into the environment.


PubMed | Egerton University and Chuka University
Type: Journal Article | Journal: International journal of medicinal mushrooms | Year: 2016

Vitamin D may have an important role in many aspects of human health, from bone fractures to prostate cancer, cardiovascular disease, neuromuscular problems, and diabetes. Vitamin D is produced in the human body by the skin after sunlight absorption, but as human lifestyles change, so does the time of exposure to sunlight, necessitating dietary supplementation of vitamin D. Mushrooms have the advantages that they are the only source of vitamin D in the produce aisle and they are one of the few nonfortified food sources. Here, we review the current literature on enhancement of the vitamin D content in mushrooms and literature evidence on the bioavailability of vitamin D in humans and animals after ingesting ultraviolet (UV)-irradiated mushrooms. We also present available literature on health safety after UV irradiation of mushrooms, and we discuss issues arising in the attempt to incorporate UV irradiation into the mushroom production line.


PubMed | University of Bonn, Central Institute for Engineering, University of Nairobi and Chuka University
Type: | Journal: Journal of trace elements in medicine and biology : organ of the Society for Minerals and Trace Elements (GMS) | Year: 2016

A large number of medicinal plants is traditionally known in Kenya and used for treatment of various diseases, for example diabetes, where metals are supposed to be involved in pathogenesis and therapy. Therefore, detailed investigation of the concentration of a large number of metals in medicinal plants is required for improved understanding and optimisation of the therapeutic role of metals and also to exclude potentially toxic effects. Our study focused on the determination of 30 selected elements in 19 medicinal plant species each collected from 3 sampling locations in Nyamira County, Kenya. The obtained comprehensive data set showed large variability and multivariate data analysis revealed that the differences in the elemental composition were stronger dependent on the plant species than on the sampling location. In addition, hot water extractions were performed to mimic the traditional preparation of medicine from the plants. It was found that the mean extraction efficiencies were below 20% except for B, Mg, P, K, Mn, Co, Ni, Cu, Zn, Rb, Mo, Cd and Tl, which are mostly essential elements apart from Cd and Tl. Sequential (ultra)filtration of the extracts was applied as novel approach for molecular size-fractionation of the extracted elemental species. The results indicate more than 50% low molecular weight species (<3kDa) for Mg, Mn, Co, Ni and Zn while predominantly larger size-fractions (>3kDa up to<5m) were detected for V, Cu, Al and Fe.


PubMed | Chuka University and Nanjing University of Finance and Economics
Type: | Journal: Food chemistry | Year: 2015

Volatile compounds are important factors that affect the flavor quality of Flammulina velutipes, but the changes occurring during hot air drying is still unclear. To clarify the dynamic changes of flavor components during hot air drying, comprehensive flavor characterization and volatile compounds of F. velutipes were evaluated using electronic nose technology and headspace solid phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively. Results showed that volatile components in F. velutipes significantly changed during hot air drying according to the principal component analysis and radar fingerprint chart of electronic nose. Volatile compounds of fresh F. velutipes consisted mainly of ketones, aldehydes and alcohols, and 3-octanone was the dominant compound. Drying process could significantly decrease the relative content of ketones and promoted the generation of alcohols, acids, and esters, which became the main volatile compounds of dried F. velutipes. These may provide a theoretical basis for the formation mechanism of flavor substances in dried F. velutipes.

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