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Human cardiac Troponin I is one of three subunits of the cardiac Troponin complex that are released into the bloodstream upon injury to cardiac muscle, particularly myocardial infarction, where it is absent under normal conditions. Rapid, sensitive detection of blood borne Troponin I is extremely important for early detection of myocardial infarction. An optical biosensor has been proposed as a versatile, adaptable, and effective method for detection of Troponin I. The biosensor architecture utilizes fluorescence resonance energy transfer (FRET), a distance-dependent chemical signal transduction method that occurs between two fluorescent molecules, termed the donor and acceptor. In order to launch FRET, a donor-labeled protein A molecule is bound to an acceptor-labeled capture antibody. When exposed to the Troponin I antigen, the antibody-antigen binding event initiates a conformational change within the structure of the antibody. As this morphological change in the antibody takes place, the distance between the donor and acceptor changes, resulting in a measurable shift in energy transfer. In this study, quantum dots were utilized as the FRET donors to further increase the efficiency of the biosensor system and organic dyes were utilized as the acceptors. This sensing mechanism was then interfaced in a liquid-core waveguide (LCW) platform that was able to capture the resulting fluorescence to achieve highly sensitive and accurate measurements. The biosensor demonstrated an ample sensitivity to the analyte, achieving a lower limit of detection of approximately 32 nM in phosphate buffered saline and 55 nM in human plasma. A high degree of specificity was also observed when the response to cardiac Troponin I is compared with that of a nonspecific protein. Response time of the biosensor was determined to be less than 1 min; an expeditious time compared with other Troponin diagnostic assays. [ABSTRACT FROM PUBLISHER]

A novel sensing method for detecting the human immunodeficiency virus (HIV) is reported. The method utilized a two receptor-binding event and required the integration of a chemical transducer system with two unique protein receptors, CD4 and Mab, a monoclonal antibody, which bind to gp120, a single-surface protein receptor on HIV. The chemical transduction system was based on the distance-dependent principle of fluorescence resonance energy transfer (FRET). During the binding event, the two fluorophore-labeled receptors docked at the surface of the gp120. The resulting close proximity of the two fluorophores upon binding initiated an energy transfer resulting in a detectable change of fluorescence. Donor fluorophore to acceptor fluorophore ratios were examined to ascertain any effects on energy transfer. The experiments demonstrated that higher ratios of acceptor fluorophores to donor fluorophores resulted in enhanced energy transfer. In-solution testing proved the feasibility of the dual receptor technique in detecting the presence of gp120 with a limit of detection of 5 ng/ml. [ABSTRACT FROM PUBLISHER]

Analyzes the temperature dependence of water retention curves for wettable and water-repellent soils. Details on the capillary pressure in unsaturated porous media; Effect of temperature on the surface tension of the pore water and on the angle of contact; Measurements of capillary pressure and water content.

Studies the effects of grazing by sheep on blanket bog vegetation in southwest Scotland over 11 years in an experiment in which three stocking rates were provided at each of three sites. Treatment of one site as though it were part of an off-wintering system; Two sites as though they were part of year-round grazing systems; Increase in total biomass in successive harvests as the dwarf shrubs aged and accumulated wood.

Focuses on a comparative study on the seasonal variation in floristic composition of the diets selected by sheep and cattle grazing together on blanket bog and on calluna vulgaris heather moor. Characterization of biomass species, morphological composition and canopy structure; Collection of diet samples from esophageally-fistulated animals; Difference between the dietary components of sheep and cattle.

(1) A comparative study was made of the seasnal variation in floristic composition of the diets selected by sheep and cattle grazing together on Agrostis-Festuca. Nardus and Molinia grassland communities in southern Scotland. Fenced plots at each site were grazed in sequence with the experimental animals moved between sites as appropriate. (2) For each period at each site, sward biomass, Species and morphological composition and canopy structure were characterized. Diet samples were collected from three to five oesophageally-Fistulated animals of each species from four to seven, separate, two-week periods of observation at each site over three years. (3) Sheep diets were more variable than cattle diets, both between and within animals. for all sites, Sheep and cattle differed significantly for almost all major dietary components; exceptions were Molinia leaf, grass sheath and dead material at the Molinia site. (4) At all sites in suimmer, sheep diets contained more forbs and less grass flowerstem than did cattle diets. (5) At the Agrostis-Festuca and Nardus sites, sheep diets contained more live components than did cattle diets on all sampling dates. At the Molinia site, sheep and cattle diets contained similar proportions of live components in early stummer, but in autumn after the Molinia and Holcus leaves died, sheep grazed died. sheep grazed other grass species and their diets contained less live components than those of the cattle which grazed Juncus spp. (6) At the Nardus site, both sheep and cattle preferentially grazed the Festuca and Deschampsia (from between the Nardus tussocks) and the small patches of broad leaved grasses. The progressive reduction in herbage biomass and height on the preferred areas in successive grazing periods was associated with a marked increase in the Nardus content of cattle diets but not of sheep diets. (7) Differences between sheep and cattle diets were explicable by (i) a difference in the height at... [ABSTRACT FROM AUTHOR]