133 research outputs found
Axial Concentration Profiles and NO Flue Gas in a Pilot-Scale Bubbling Fluidized Bed Coal Combustor
Atmospheric bubbling fluidized bed coal combustion of a bituminous coal and anthracite with
particle diameters in the range 500-4000 Ăm was investigated in a pilot-plant facility. The
experiments were conducted at steady-state conditions using three excess air levels (10, 25, and
50%) and bed temperatures in the 750-900 °C range. Combustion air was staged, with primary
air accounting for 100, 80, and 60% of total combustion air. For both types of coal, high NO
concentrations were found inside the bed. In general, the NO concentration decreased monotonically
along the freeboard and toward the exit flue; however, during combustion with high air
staging and low to moderate excess air, a significant additional NO formation occurred near the
secondary air injection point. The results show that the bed temperature increase does not affect
the NO flue gas concentration significantly. There is a positive correlation between excess air
and the NO flue gas concentration. The air staging operation is very effective in lowering the
NO flue gas, but there is a limit for the first stage stoichiometry below which the NO flue gas
starts rising again. This effect could be related with the coal rank
Barriers to participation in mental health research: are there specific gender, ethnicity and age related barriers?
<p>Abstract</p> <p>Background</p> <p>It is well established that the incidence, prevalence and presentation of mental disorders differ by gender, ethnicity and age, and there is evidence that there is also differential representation in mental health research by these characteristics. The aim of this paper is to a) review the current literature on the nature of barriers to participation in mental health research, with particular reference to gender, age and ethnicity; b) review the evidence on the effectiveness of strategies used to overcome these barriers.</p> <p>Method</p> <p>Studies published up to December 2008 were identified using MEDLINE, PsycINFO and EMBASE using relevant mesh headings and keywords.</p> <p>Results</p> <p>Forty-nine papers were identified. There was evidence of a wide range of barriers including transportation difficulties, distrust and suspicion of researchers, and the stigma attached to mental illness. Strategies to overcome these barriers included the use of bilingual staff, assistance with travel, avoiding the use of stigmatising language in marketing material and a focus on education about the disorder under investigation. There were very few evaluations of such strategies, but there was evidence that ethnically matching recruiters to potential participants did not improve recruitment rates. Educational strategies were helpful and increased recruitment.</p> <p>Conclusion</p> <p>Mental health researchers should consider including caregivers in recruitment procedures where possible, provide clear descriptions of study aims and describe the representativeness of their sample when reporting study results. Studies that systematically investigate strategies to overcome barriers to recruitment are needed.</p
In Vitro Metabolism and Stability of the Actinide Chelating Agent 3,4,3âLI(1,2âHOPO)
The hydroxypyridinonate ligand 3,4,3-LI(1,2-HOPO) is currently under development for radionuclide chelation therapy. The preclinical characterization of this highly promising ligand comprised the evaluation of its in vitro properties, including microsomal, plasma, and gastrointestinal fluid stability, cytochrome P450 inhibition, plasma protein binding, and intestinal absorption using the Caco-2 cell line. When mixed with active human liver microsomes, no loss of parent compound was observed after 60 min, indicating compound stability in the presence of liver microsomal P450. At the tested concentrations, 3,4,3-LI(1,2-HOPO) did not significantly influence the activities of any of the cytochromal isoforms screened. Thus, 3,4,3-LI(1,2-HOPO) is unlikely to cause drug-drug interactions by inhibiting the metabolic clearance of coadministered drugs metabolized by these enzymes. Plasma protein-binding assays revealed that the compound is protein-bound in dogs and less extensively in rats and humans. In the plasma stability study, the compound was stable after 1 h at 37°C in mouse, rat, dog, and human plasma samples. Finally, a bidirectional permeability assay demonstrated that 3,4,3-LI(1,2-HOPO) is not permeable across the Caco-2 monolayer, highlighting the need to further evaluate the effects of various compounds with known permeability enhancement properties on the permeability of the ligand in future studies
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