Aerosol enrichment of the surfactant PFO and mediation of the water--air transport of gaseous PFOA

Aerosol-mediated transport of perfluorooctanoate (PFO) from a water body to the atmosphere and the subsequent emission of gas-phase perfluorooctanoic acid (PFOA) was investigated. The potential for this process to facilitate long-range transport of PFOA/PFO was assessed. In a laboratory experiment, aerosols were generated and collected from deionized, fresh, and ocean waters spiked with PFO and analyzed by LC-MS/MS. Gas-phase samples were also collected from the system and analyzed for PFOA. Aerosols were found to have significantly higher concentrations of PFO than the parent water body (< or = 80 times for ocean waters). The PFOA, at equilibrium with the PFO in the aqueous aerosol, partitioned rapidly (t 1/2 = 7.2 s) out of the aerosol droplet. This suggests that rainout rates are likely to be longer than previously hypothesized. These results imply that water bodies are not a permanent sink for atmospheric PFOA as previous studies have suggested. The occurrence of contamination in remote regions may not depend solely on the previously hypothesized indirect sources but also on the long-range transport, via the gas phase, of direct releases of PFOA to both the aquatic and atmospheric environments.     

Short communication: change in plasma ghrelin in dairy cows following an intravenous glucose challenge

Ghrelin is an endogenous ligand of the growth hormone secretagogue receptor and a potent orexigenic (appetite-stimulating) agent in humans and rodents, but little is known about its effect in dairy cows. Ten multiparous dairy cows 35 d in milk were subjected to an i.v. glucose challenge (300 mg of d-glucose/kg of body weight). Before infusion and at regular intervals after infusion, plasma glucose, insulin, nonesterified fatty acids (NEFA), growth hormone, epinephrine, and ghrelin concentrations were monitored. Plasma insulin rose (27.2 mU/L at 10 min) and NEFA, epinephrine, and ghrelin declined (nadir = 0.22 mmol/L, 22.2 μg/L, and 272 μg/L at 31, 13, and 22 min, respectively) after the glucose infusion. Ghrelin declined for 22 min before returning to suprabasal levels at approximately 75 min postinfusion. Sequential changes of the hormones and metabolites suggested a glucose transporter, type 2- and glucose transporter, type 4-mediated disposal of glucose, and an insulin-mediated reduction in NEFA. Ghrelin and epinephrine declined after glucose infusion and before the insulin peak, but the effect of insulin as a controlling factor in the hyperglycemic reduction in these hormones cannot be discounted. The post-nadir surge in ghrelin may be regulated by the decline in circulating concentrations of glucose and NEFA (an energy-deficit signal). The profile of change in plasma ghrelin in lactating dairy cows after a glucose challenge was similar to that in monogastric animals.     

Extraordinary all-dielectric light enhancement over large volumes

We present resonant dielectric structures exhibiting arbitrarily large optical field enhancement, only limited by fabrication imperfections. Three different arrangements are investigated, based upon dielectric waveguides, dielectric particle arrays, and a combination of these two structures. Experimental confirmation of enhancement in a waveguide resonator is achieved by measuring the luminescence of quantum dots dispersed in the hot optical region of the structure. The performance of these systems can be readily controlled by simply changing geometrical parameters, which allows obtaining remarkable values of the intensity enhancement approaching 105 relative to the incident intensity over large volumes under feasible experimental conditions. This opens new avenues for all-optical switching and biosensing.     

Structure of hydrogen triple flames and premixed flames compared

Triple flames consisting of lean, stoichiometric, and rich reaction zones may be produced in stratified mixtures undergoing combustion. Such flames have unique characteristics that differ from premixed flames. The present work offers a direct comparison of the structure and propagation behavior between hydrogen/air triple and premixed flames through a numerical study. Important similarities and differences are highlighted. Premixed flames are generated by spark-igniting initially quiescent homogeneous mixtures of hydrogen and air in a two-dimensional domain. Triple flame results are also generated in a two-dimensional domain by spark-igniting initially quiescent hydrogen/air stratified layers. Detailed flame structure and chemical reactivity information is collected along isocontours of equivalence ratio 0.5, 1.0, and 3.0 in the triple flame for comparison with premixed flames at the same equivalence ratios. Full chemistry and effective binary diffusion coefficients are employed for all computations.     

Social support and the well-being of persons with spinal cord injury living in the community.

100 men and 40 women (all aged 19–77 yrs) with spinal cord injury completed a social support questionnaire, the Center for Epidemiologic Studies Depression Scale, the Life Satisfaction Index Form A, and a single-item self-assessment of health status. A physician assessed the presence or absence of urinary tract infection from laboratory findings and determined the absence, presence, and severity of pressure ulcers from physical examination. Amount of social support was positively related to life satisfaction and physical well-being. Satisfaction with one's support network was associated negatively with depressive symptomatology and positively with life satisfaction. There were significant differences in the correlations between life satisfaction and total social support for men and women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

News: EPA, environmentalists clash over proposal to test contaminated dredged sediments

Government.     

News: DOE Environmental Management program awards first basic research grants

Science.     

How independent are independent psychological examinations? A workers' compensation dilemma.

In recent years there has been an increasing demand for clinicians to conduct independent psychological examinations (IPEs) of persons involved in work-related injuries, with referrals coming from insurance carriers and attorneys. This article discusses the role of the psychologist in the workers' compensation system, specifically focusing on the challenges facing psychologists who accept the IPE assignment. Potential abuses of the workers' compensation process by psychologists and ethical considerations are also discussed. Several recommendations for improving the system are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)