Adsorption of RDX and HMX in Rapid Small-Scale Column Tests: Implications for Full-Scale Adsorbers

The high explosive (HE) compounds royal demolition explosive or hexahydro-1,3,5-trinitro-1,3,5-triazocine (RDX) and high melting explosive or octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) have been detected as groundwater contaminants at many military facilities. This research evaluated adsorption of RDX and HMX with granular activated carbon (GAC) to provide guidance for the design and operation of GAC adsorbers for treatment of HE-contaminated groundwater. Five GACs were screened using rapid small-scale column tests (RSSCTs), after which additional tests were performed with the two GACs that most effectively treated mixtures of RDX and HMX (Calgon F400 and Northwestern LB-830). GAC service life as a function of empty-bed contact time (EBCT) was determined using RSSCTs for a range of simulated full scale EBCTs with influent concentrations of 2,200 μg RDX/L and 350 μg HMX/L. Increasing the influent concentration of either contaminant significantly reduced the predicted service life, as did preloading GAC with groundwater natural organic matter. In batch isotherm tests, RDX was less adsorbable than HMX under all conditions studied. Concurrent loading of natural organic matter reduced the Freundlich K for RDX, whereas adsorption of HMX was not affected. Of the GACs tested, Calgon F400 most effectively removed RDX and HMX.     

Examining the locus of age effects on complex span tasks.

To investigate the locus of age effects on complex span tasks, the authors evaluated the contributions of working memory functions and processing speed. Age differences were found in measures of storage capacity, language processing speed, and lower level speed. Statistically controlling for each of these in hierarchical regressions substantially reduced, but did not eliminate, the complex span age effect. Accounting for lower level speed and storage, however, removed essentially the entire age effect, suggesting that both functions play important and independent roles. Additional evidence for the role of storage capacity was the absence of complex span age differences with span size calibrated to individual word span performance. Explanations for age differences based on inhibition and concurrent task performance were not supported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fines Accumulation and Distribution in a Storm-Water Rain Garden Nine Years Postconstruction

Storm water control measures (SCMs), also known as best management practices (BMPs), such as rain gardens, are designed to infiltrate storm-water runoff and reduce pollutant transport to surface waters. The life span of these SCMs may be limited depending on the composition of sediments in runoff water. Settling of fine sediments may clog soil pore spaces, reducing the infiltration capacity of the soil and reducing the potential benefits of this SCM. A study was conducted on a Villanova campus rain garden that accepts runoff from an adjacent parking lot to determine if there was a relationship between the accumulation of fine sediments over time and the infiltration capacity. The soil textural profile within the rain garden was characterized prior to SCM installation (2001), after installation, after five years, and after seven years of receiving storm-water runoff. Infiltration data were collected by the single-ring infiltrometer method in 2006 and 2009. Differences in soil texture were found between locations within the infiltration basin, and accumulation of fines smaller than 0.1 mm was observed at both locations sampled in 2009. Infiltration rates were significantly different between the two locations measured within the rain garden, but infiltration rates did not change significantly over time within those regions. This SCM was designed at a 10:1 watershed to SCM area ratio, which is twice what is recommended by the PA DEP BMP Manual. The data collected over the seven years since installation indicate that while fines have accumulated in the SCM there has been no significant change in infiltration potential.     

Performance of Silica-Titania Carbon Composites for Photocatalytic Degradation of Gray Water

The objective of this research was to develop a photocatalytic reactor that will reduce the total organic carbon (TOC) concentration of a gray water influent. The system used a reactor packed with titanium dioxide (TiO2) supported by silica gel (SiO2) and was optimized with respect to several system parameters. The SiO2–TiO2 composites (STCs) were capable of reducing the TOC concentration from 3,000 ppb to below the targeted concentration of 500 ppb in a recirculating system. An optimum empty bed contact time of 7 min was found based on the fastest destruction rate to reach below 500 ppb of TOC. Also based on destruction rate, a STC having a TiO2 loading of 12 g/100 mL of SiO2 precursor and approximately 120-? pore size was shown to have the best performance among several composites of different TiO2 loadings and pore sizes. The addition of activated carbon to the STC was found to improve the overall performance of the system by increasing the composite’s adsorption capabilities.     

Do neuropsychological tests have the same meaning in Spanish speakers as they do in English speakers?

Objective: The purpose of this study was to examine whether neuropsychological tests translated into Spanish measure the same cognitive constructs as the original English versions. Method: Older adult participants (N = 2,664), who did not exhibit dementia from the Washington Heights Inwood Columbia Aging Project (WHICAP), a community-based cohort from northern Manhattan, were evaluated with a comprehensive neuropsychological battery. The study cohort includes both English (n = 1,800) and Spanish speakers (n = 864) evaluated in their language of preference. Invariance analyses were conducted across language groups on a structural equation model comprising four neuropsychological factors (memory, language, visual-spatial ability, and processing speed). Results: The results of the analyses indicated that the four-factor model exhibited partial measurement invariance, demonstrated by invariant factor structure and factor loadings but nonequivalent observed score intercepts. Conclusion: The finding of invariant factor structure and factor loadings provides empirical evidence to support the implicit assumption that scores on neuropsychological tests are measuring equivalent psychological traits across these two language groups. At the structural level, the model exhibited invariant factor variances and covariances. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Should I stay or should I go? Personality Assessment Inventory and Rorschach indices of early withdrawal from psychotherapy.

The Personality Assessment Inventory (PAI) and the Rorschach were used to investigate differences between patients who withdrew early from university-based outpatient psychodynamic psychotherapy and those who continued in treatment. The study employs two sets of analyses, one utilizing the complete sample (N = 101) and a second comprised of comparison pairs matched on the specific therapist delivering treatment (n = 36 for Rorschach; n = 38 for PAI). It was hypothesized that early withdrawers would score higher on the PAI Treatment Rejection Scale (RXR) and the PAI Treatment Process Index (TPI) than treatment continuers. It was also hypothesized that early treatment withdrawers will have better overall interpersonal relationships, less need for closeness and intimacy, less available psychological resources and more current stimulus demands, and lower levels of psychological/cognitive disturbance as measured by the Rorschach. In addition, differences between the two groups on PAI treatment and clinical scales and subscales were examined. Results indicated that PAI RXR differentiated between the two groups (p     

Solvent-free oxidation of benzyl alcohol using titania-supported gold–palladium catalysts: Effect of Au–Pd ratio on catalytic performance

The oxidation of benzyl alcohol with molecular oxygen under solvent-free conditions has been investigated using a range of titania-supported Au–Pd alloy catalysts to examine the effect of the Au–Pd ratio on the conversion and selectivity. The catalysts have been compared at high reaction temperature (160 °C) as well as at 100 °C, to determine the effect on selectivity since at lower reaction temperature the range of by-products that are formed are limited. Under these conditions the 2.5 wt.% Au–2.5 wt.% Pd/TiO₂ was found to be the most active catalyst, whereas the Au/TiO₂ catalyst demonstrated the highest selectivity to benzaldehyde. Toluene, formed via either a hydrogen transfer process or an oxygen transfer process, was observed as a major by-product under these forcing conditions.     

Structure–Property Relationships in Aligned Electrospun Barium Titanate Nanofibers

Barium titanate nanofibers were uniaxially aligned by electrospinning onto a rotating copper wire drum and alignment was maintained during calcination of the fibers. Two methods for maintaining alignment during calcination were tested, by either using carbon tape or a peeling off method to remove the aligned fibers from the mandrel followed by calcination. The carbon tape removal method led to the formation of shorter aligned nanowires while the peeling off method resulted in longer nanofibers. Additionally, the effects of calcination temperature and time on crystal structure were also examined. The degree of tetragonality in the barium titanate nanofibers increased at higher calcination temperatures and times. Piezoelectricity was confirmed in the nanofibers calcined using piezoeresponse force microscopy, yielding a d₃₃ value of 15.5 pm/V. Using the methods presented here, large quantities of aligned piezoelectric barium titanate and other ceramic fibers or wires can be produced to fulfill their demand in novel microelectronics.     

Time and shear dependent rheology of maleated polyethylene and its nanocomposites

Dipole-dipole and/or hydrogen-bonding interactions between the pendant functional groups within maleated high-density polyethylene (PE-g-MAn) establish a physical polymer network, whose formation kinetics and shear-sensitivity are revealed by dynamic oscillatory testing. The pronounced time and shear dependent viscoelastic properties of PE-g-MAn were not observed for a corresponding imide derivative, PE-g-imide, presumably due to weakened functional group associations in the latter material.The melt compounding of PE-g-MAn with onium-ion exchanged montmorillonite clay (NR₄⁺-MM) resulted in a partially exfoliated hybrid nanocomposite structure, whose viscoelastic behaviour differed significantly from that of the unfilled polymer. The presence of dispersed clay platelets altered the extent of functional group associations, thereby changing the dynamics of network formation.     

Health benefits of CLA – lessons from pig models in biomedical research

The objective of this review is to highlight the use of pig models for investigating safety, efficacy and the mechanisms of action of conjugated linoleic acid (CLA). Although CLA elicits positive effects in animal models and in vitro systems, a consistent concern in terms of translational research is that the health benefits observed by using these model systems cannot be extrapolated directly into humans. Conversely, the similarities between pigs and humans make the pig an ideal model for examining the health benefits of dietary supplements, functional foods and nutraceuticals. We have developed pig models of viral and bacterial infection to examine the preventive role of dietary CLA supplementation on virally induced immunosuppression and gut health, respectively. Results from these studies indicate that CLA significantly enhances the immune function while limiting the catabolic effects of uncontrolled immune and inflammatory responses. The scientific findings in pig models and human clinical trials demonstrate that CLA modulates immune responses in pigs and humans. Pig models of immunomodulation represent significant improvements over other animal models and in vitro systems because they mimic more closely the compartmentalization of the human immune system and the clinical presentation of human infectious, immune and inflammatory diseases.