Preparation of Pt-Re/Vulcan carbon nanocomposites using a single-source molecular precursor and relative performance as a direct methanol fuel cell electrooxidation catalyst

Pt-Re/Vulcan carbon powder nanocomposites have been prepared with total metal loadings of 18 wt.% and 40 wt.% using a new non-cluster (1:1)-PtRe bimetallic precursor as the source of metal. Pt-Re nanoparticles having an average diameter of ca. 6 nm and atomic stoichiometry near 1:1 are formed. TEM, on-particle HR-EDS, and powder XRD data are consistent with the formation of Pt-Re alloy nanoparticles having a hexagonal unit cell with cell constants of a = 2.77 A and c = 4.47 A. A nanocomposite prepared at higher total metal loading under more rigorous thermal treatment also contains Pt-Re alloy nanoparticles having a fcc unit cell structure (a = 3.95 A). The precise dependence of Pt-Re nanocrystal structure on the thermal history of the nanocomposite specimen has not been investigated in detail. While these Pt-Re/carbon nanocomposites are active as anode catalysts in operating direct methanol fuel cells, the measured performance is less than that of commercial Pt-Ru/carbon catalysts and has marginal practical importance.     

Dissipation of fragrance materials in sludge-amended soils

A possible removal mechanism for fragrance materials (FMs) in wastewater is adsorption to sludge, and sludge application to land may be a route through which FMs are released to the soil environment. However, little is known about the concentrations and fate of FMs in soil receiving sludge application. This study was conducted to better understand the dissipation of FMs in sludge-amended soils. We first determined the spiking and extraction efficiencies for 22 FMs in soil and leachate samples. Nine FMs were detected in digested sludges from two wastewater treatment plants in Delaware using these methods. We conducted a 1-year die-away experiment which involved four different soils amended with sludge, with and without spiking of the 22 FMs. The initial dissipation of FMs in all spiked trays was rapid, and only seven FMs remained at concentrations above the quantification limits after 3 months: AHTN, HHCB, musk ketone, musk xylene, acetyl cedrene, OTNE, and DPMI. After 1 year, the only FMs remaining in all spiked trays were musk ketone and AHTN. DPMI was the only FM that leached significantly from the spiked trays, and no FMs were detected in leachate from any unspiked tray. While soil organic matter content affected the dissipation rate in general, different mechanisms (volatilization, transformation, leaching) appeared to be important for different FMs.     

Combat experience and youth: Influences on reported violence against women.

A study of 101 VA psychiatric and chemically dependent inpatients (mean age 44.8 yrs) was conducted to investigate the hypothesis that combat veterans (n?=?54) would report a higher frequency of physical violence against female partners than noncombat veterans (n?=?47). Veterans were interviewed by staff psychologists seeking information about the frequency and severity of violence toward their female partners and about whether or not they had been in combat. Results show no significant differences in reported violence toward female partners between the combat and noncombat veterans even when age was controlled. Younger men were, however, more violent toward women than older men. Data cast doubt on the view that combat experience leads to violence within marital relationships. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Equilibrium partitioning of a non-ionic surfactant and pentachlorophenol between water and a non-aqueous phase liquid

The partitioning of the non-ionic surfactant Tergitol NP-10 (TNP10) and pentachlorophenol (PCP) into a mineral oil light non-aqueous phase liquid (NAPL) were quantified in batch tests. Due to the ionizable nature of PCP, the effects of pH and ionic strength (micro) on the equilibrium partitioning were evaluated. NAPL:water partition coefficients (K(n:w)) of TNP10 ranged from 3 to 7 l(water)/l(NAPL). Enhanced PCP dissolution into water from the NAPL was achieved at aqueous TNP10 concentrations > or =200mg/l. Surfactant addition of 1200 mg/l TNP10 increased the aqueous PCP concentrations by 14-fold at pH 5 versus 2 to 3-fold at pH 7 as compared to PCP aqueous solubility. The more significant response at the lower pH is likely due to the greater hydrophobicity of PCP at the lower pH, which is approaching PCP's pK(a) of 4.7. Higher ionic strength (micro 0.11 versus 0.001 M) increased K(n:w) of PCP by 10-33% without surfactant, compared to a more than 150% increase with a dose of 4000 mg/l TNP10. This work contributes information relevant to the application of surfactants to remediate sites contaminated with NAPLs.     

Effects of interface roughness on the spectral properties of thin films and multilayers

We introduce two parameters, large-scale and small-scale rms roughness, to take into account the interface properties of thin films and multilayers in the calculation of their specular reflectance and transmittance. A theoretical motivation for the introduction of these two parameters instead of a standard single rms roughness is provided. Experimental power spectral density functions of several samples are used to illustrate ways in which the parameters introduced can be evaluated.     

Characterization of spatial and temporal variations in the optical properties of tissuelike media with diffuse reflectance imaging

We describe a method to characterize spatial or temporal changes in the optical properties of turbid media using diffuse reflectance images acquired under broad-beam illumination conditions. We performed experiments on liquid phantoms whose absorption (mu(a)) and reduced scattering (mu(s)') coefficients were representative of those of biological tissues in the near infrared. We found that the relative diffuse reflectance R depends on mu(a) and mu(s)' only through the ratio mu(a)/mu(s)' and that dependence can be well described with an analytical expression previously reported in the literature [S. L. Jacques, Kluwer Academic Dordrecht (1996)]. We have found that this expression for R deviates from experimental values by no more than 8% for various illumination and detection angles within the range 0 degrees-30 degrees. Therefore, this analytical expression for R holds with good approximation even if the investigated medium presents curved or irregular surfaces. Using this expression, it is possible to translate spatial or temporal changes in the relative diffuse reflectance from a turbid medium into quantitative estimates of the corresponding changes of (mu(a)/mu(s)')(1/2). In the case of media with optical properties similar to those of tissue in the near infrared, we found that the changes mu(a)/mu(s)' should occur over a volume approximately 2 mm deep and 4 mm x 4 mm wide to apply this expression.     

What predicts psychological resilience after disaster? The role of demographics, resources, and life stress.

A growing body of evidence suggests that most adults exposed to potentially traumatic events are resilient. However, research on the factors that may promote or deter adult resilience has been limited. This study examined patterns of association between resilience and various sociocontextual factors. The authors used data from a random-digit-dial phone survey (N = 2,752) conducted in the New York City area after the September 11, 2001, terrorist attack. Resilience was defined as having 1 or 0 posttraumatic stress disorder symptoms and as being associated with low levels of depression and substance use. Multivariate analyses indicated that the prevalence of resilience was uniquely predicted by participant gender, age, race/ethnicity, education, level of trauma exposure, income change, social support, frequency of chronic disease, and recent and past life stressors. Implications for future research and intervention are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Judgments of synchrony between auditory and moving or still visual stimuli.

The flash-lag effect is a visual illusion wherein intermittently flashed, stationary stimuli seem to trail after a moving visual stimulus despite being flashed synchronously. We tested hypotheses that the flash-lag effect is due to spatial extrapolation, shortened perceptual lags, or accelerated acquisition of moving stimuli, all of which call for an earlier awareness of moving visual stimuli over stationary ones. Participants judged synchrony of a click either to a stationary flash of light or to a series of adjacent flashes that seemingly bounced off or bumped into the edge of the visual display. To be judged synchronous with a stationary flash, audio clicks had to be presented earlier--not later--than clicks that went with events, like a simulated bounce (Experiment 1) or crash (Experiments 2-4), of a moving visual target. Click synchrony to the initial appearance of a moving stimulus was no different than to a flash, but clicks had to be delayed by 30-40 ms to seem synchronous with the final (crash) positions (Experiment 2). The temporal difference was constant over a wide range of motion velocity (Experiment 3). Interrupting the apparent motion by omitting two illumination positions before the last one did not alter subjective synchrony, nor did their occlusion, so the shift in subjective synchrony seems not to be due to brightness contrast (Experiment 4). Click synchrony to the offset of a long duration stationary illumination was also delayed relative to its onset (Experiment 5). Visual stimuli in motion enter awareness no sooner than do stationary flashes, so motion extrapolation, latency difference, and motion acceleration cannot explain the flash-lag effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of aging and encoding instructions on emotion-induced memory trade-offs.

The effects of emotion on memory are often described in terms of trade-offs: People often remember central, emotional information at the expense of background details. The present experiment examined the effects of aging and encoding instructions on participants' ability to remember the details of central emotional objects and the backgrounds on which those objects were placed. When young and older adults passively viewed scenes, both age groups showed strong emotion-induced trade-offs. They were able to remember the visual details as well as the general theme of the emotional object, but they had difficulties remembering the visual specifics of the scene background. Age differences emerged, however, when participants were given encoding instructions that emphasized elaborative encoding of the entire scene. With these instructions, young adults overcame the trade-offs (i.e., they no longer showed impairing effects of emotion), whereas older adults continued to show good memory for the emotional object but poor memory for its background. These results suggest that aging impairs the ability to flexibly disengage attention from the negative arousing elements of scenes, preventing the successful encoding of nonemotional aspects of the environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)