Remediation of Contaminated Soils by Solvent Flushing

Solvent flushing is a potential technique for remediating a waste disposal/spill site contaminated with organic chemicals. This technique involves the injection of a solvent mixture (e.g., water plus alcohols) that enhances contaminant solubility, reduces the retardation factor, and increases the release rates of the contaminants. A simulation model is developed to predict contaminant elution curves during solvent flushing for the case of one‐dimensional, steady flow through a contaminated medium. Column experiments are conducted with a Eustis fine sand that is initially equilibrated with an aqueous naphthalene solution, and then eluted with different methanol‐water mixtures to remove the naphthalene. The model simulations, based on parameter values estimated from literature data, agree well with the measured elution profiles. Solvent flushing experiments, where the soil was initially equilibrated with a solution of naphthalene and anthracene, show that compounds with different retardation factors are separated at low cosolvent contents, while coelution of the compounds occurs at higher contents. In general, the smaller the retardation factor in water and the higher the cosolvent fraction, the faster the contaminant is recovered. The presence of nonequilibrium conditions, soil heterogeneity, and type of cosolvent will influence the time required to recover the contaminant.\u

B-Type Natriuretic Peptide and Prognosis in Heart Failure Patients With Preserved and Reduced Ejection Fraction

<p>Objectives This study sought to determine the prognostic value of B-type natriuretic peptide (BNP) in patients with heart failure with preserved ejection fraction (HFPEF), in comparison to data in HF patients with reduced left ventricular (LV) EF (</p><p>Background Management of patients with HFPEF is difficult. BNP is a useful biomarker in patients with reduced LVEF, but data in HFPEF are scarce.</p><p>Methods In this study, 615 patients with mild to moderate HF (mean age 70 years, LVEF 33%) were followed for 18 months. BNP concentrations were measured at baseline and were related to the primary outcome, that is, a composite of all-cause mortality and HF hospitalization, and to mortality alone. The population was divided in quintiles, according to LVEF, and patients with reduced LVEF were compared with those with HFPEF.</p><p>Results There were 257 patients (42%) who had a primary endpoint and 171 (28%) who died. BNP levels were significantly higher in patients with reduced LVEF than in those with HFPEF (p <0.001). BNP was a strong predictor of outcome, but LVEF was not. Importantly, if similar levels of BNP were compared across the whole spectrum of LVEF, and for different cutoff levels of LVEF, the associated risk of adverse outcome was similar in HFPEF patients as in those with reduced LVEF.</p><p>Conclusions BNP levels are lower in patients with HFPEF than in patients with HF with reduced LVEF, but for a given BNP level, the prognosis in patients with HFPEF is as poor as in those with reduced LVEF. (J Am Coll Cardiol 2013;61:1498-506) (C) 2013 by the American College of Cardiology Foundation</p>