Bioactive metabolites from Trichoderma harzianum and Trichoderma longibrachiatum

The tea plant, Camellia sinensis (L.) O. Kuntze is an important crop in the agriculturally based economy of Kenya. Many diseases affect the tea plant but the most prevalent is armillaria root rot caused by the fungus Armillaria mellea. Compounds from the fermentation of Trichoderma species in different media were bioassayed against some selected gram-positive and gram-negative bacteria, fungi including Armillaria mellea, a yeast and a Mucor. Compounds obtained from T. harzianum, and T. longibrachiatum when cultured in various media were investigated individually for in-vitro antifungal and antibacterial activities by agar diffusion technique. Some of the compounds produced definite antifungal and antibacterial activities. 2-Phenylethanol (1) and tyrosol (2) obtained from T. harzianum are reported for the first time from Trichoderma species. The most active metabolite isolated from these strains was 6-n-pentyl-α-pyrone (3), which showed the highest antifungal and antibacterial activity and completely inhibited the growth of Armillaria mellea fungus at a concentration of 200 ppm. Compound 4 (sorbicillin) exhibited moderate activity against the fungal test organisms. KEY WORDS: Trichoderma harzianum, Trichoderma longibrachiatum, 2-Phenylethanol, Tyrosol, 6-n-Pentyl-•-pyrone, Armillaria Mellea  Bull. Chem. Soc. Ethiop. 2003, 17(2), 185-190

Organochlorine residues in tissues of marine fauna along the coast of Kenya-Mombasa Island

Soft tissues of species of marine fauna; crabs (Crustacea), oysters (Pelecypoda, Bivalvia), sea stars (Asterroidea), sea urchin (Echinoidea) and bony fishes (Osteichtyes) sampled along the Kenya-Mombasa coastal region were analyzed to determine the levels of organochlorine pesticides (OCPs). Analysis was done using gas chromatography with an electron capture detector. This study showed that marine fauna accumulated some OCPs in their tissues, 1,2,3,4,5,6-hexachlorocyclohexane (BHC) being the most common of the OCPs. These findings highlight evidence of pollution of marine fauna at the Kenyan coastal sites. It is necessary to have thorough waste management programs as a strategy to minimize marine pollution.  KEY WORDS: Environmental samples; Marine samples; Kenya-Mombasa coastline; Marine fauna, Organochlorine, Pesticides  Bull. Chem. Soc. Ethiop. 2007, 21(1), 145-149.

L-ascorbic acid losses in Kenyan vegetables during cooking as determined by high performance liquid chromatography

The loss of L-ascorbic acid (L-AA) in 14 different cooked local vegetables found in Nairobi markets was determined by high performance liquid chromatography. The effect of quantity of water on the loss of L-AA during cooking was studied with cowpea leaves. It was found that more L-AA was lost when larger amount of water was used than when smaller amount was used. The effect of the sharpness of the knife on the loss of L-AA was studied with spinach. It was found that more loss of L-AA occurred when a blunt (edge thickness 0.08 cm) knife was used for cutting the vegetables than when a sharp knife (edge thickness 0.04 cm) was used during cooking. L-AA was also determined when vegetables were cooked in different size pieces (surface are >1 cm2 and Bulletin of the Chemical Society of Ethiopia. ISSN: 1011-392

Experimental Feasibility Study of Fiber Optic Extrinsic Fabry-Perot Interferometric Sensor for Civil Structures and other Applications

An experimental bench set up of a fibre optic Extrinsic Fabry-Perot Interferometer (EFPI) sensor was realised and its feasibility demonstrated in an open configuration. The basic interferometric coupling between the sensing and reference reflections from a Fabry Perot (FP) air cavity realised between two fibre ends was so achieved that the sensor exhibits extreme sensitivity to external disturbances. The study reports about the salient features, scope, operating principle, and details of the experimental set-up of a fibre optic EFPI. The results of qualitative studies undertaken for sensing vibrations due to external disturbances under different situations and its further refinement/modifications for applications in health monitoring of structures are also discussed

<b>Bioactive metabolites from <i>Trichoderma harzianum</i> and <i>Trichoderma longibrachiatum</i></b>

The tea plant, Camellia sinensis (L.) O. Kuntze is an important crop in the agriculturally based economy of Kenya. Many diseases affect the tea plant but the most prevalent is armillaria root rot caused by the fungus Armillaria mellea. Compounds from the fermentation of Trichoderma species in different media were bioassayed against some selected gram-positive and gram-negative bacteria, fungi including Armillaria mellea, a yeast and a Mucor. Compounds obtained from T. harzianum, and T. longibrachiatum when cultured in various media were investigated individually for in-vitro antifungal and antibacterial activities by agar diffusion technique. Some of the compounds produced definite antifungal and antibacterial activities. 2-Phenylethanol (1) and tyrosol (2) obtained from T. harzianum are reported for the first time from Trichoderma species. The most active metabolite isolated from these strains was 6-n-pentyl-α-pyrone (3), which showed the highest antifungal and antibacterial activity and completely inhibited the growth of Armillaria mellea fungus at a concentration of 200 ppm. Compound 4 (sorbicillin) exhibited moderate activity against the fungal test organisms

Chimneys, channels, pathway flow or water conducting features - an explanation from numerical modelling and implications for CO2 storage

Large amounts of CO2 have to be captured, transported, injected and safely stored in the subsurface in order to counteract increasing atmospheric CO2 concentrations due to steadily high consumption of energy from fossil fuels. The injection of gigatons of carbon dioxide poses challenges for pressure management and the mechanical integrity of the storage complex. Optimizing the injection strategy, controlling deformation, preventing leakage and assuring safe long term containment requires reliable and predictive hydromechanical modelling. Based on a newly derived thermodynamically consistent set of equations we have developed fully coupled codes in one, two and three dimensions. In accordance with field observations and laboratory measurements, stress dependent poro- viscoelastoplastic deformation is taken into account. Our simulations predict the spontaneous formation of self- localizing high-porosity channels (or pathway flow) under conditions applicable to CO2 storage in reservoirs. These channels form due to mechanical instabilities that occur as a natural outcome of buoyancy driven flow in viscoplastically deforming rocks. Our results indicate that viscous deformation may explain the formation of chimneys such as those observed at the Sleipner pilot, and that non-linear effects have a major impact on the velocity and distribution of the fluid as well as on stress and deformation of the rock matrix. Thus, complex rheology and non-linear coupling between porosity, permeability, pressures and stresses should be included in state of the art reservoir simulation software in order to determine safe injection and storage conditions and correctly model observations and monitoring results