Mineralization of a sorbed polycyclic aromatic hydrocarbon in two soils using catalyzed hydrogen peroxide

Hydrogen peroxide (H2O2) catalyzed by soluble iron or naturally occurring soil minerals, (i.e., modified Fenton's reagent) was investigated as a basis for mineralizing sorbed and NAPL-phase benzo[a]pyrene (BaP), a hydrophobic and toxic polycyclic aromatic hydrocarbon, in two soils of different complexity. 14C-Benzo[a]pyrene was added to silica sand and a silt loam soil, and mineralization was investigated using three-level central composite rotatable experimental designs. The effects of H2O2 concentration, slurry volume, and iron(II) amendment were investigated in the silica sand systems. In a Palouse loess silt loam soil, the variables included H2O2 concentration, slurry volume, and pH, with H2O2 catalyzed by naturally occurring iron oxyhydroxides. Regression equations generated from the data were used to develop three-dimensional response surfaces describing BaP mineralization. Based on the recovery of 14C-CO2, 70% BaP mineralization was achieved in the sand within 24 h using 15 M H2O2 and an iron(II) concentration of 6.6 mM with a slurry volume of 0.3 x the field capacity of the sand. For the silt loam soil, 85% mineralization of BaP was observed using 15 M H2O2, no iron amendment, and a slurry volume of 20 x the soil field capacity. The balance of the radiolabeled carbon remained as unreacted BaP in the soil fraction. Gas-purge measurements over 5 d confirmed negligible desorption under nontreatment conditions. However, oxidation reactions were complete within 24 h and promoted up to 85% BaP mineralization, documenting that the natural rate of desorption/dissolution did not control the rate of oxidation and mineralization of the BaP. The results show that catalyzed H2O2 has the ability to rapidly mineralize sorbed/NAPL-phase BaP and that partitioning, which is often the rate-limiting factor in soil remediation, does not appear to limit the rate of vigorous Fenton-like treatment.     

Moving toward a global psychology: Changing theories and practice to meet the needs of a changing world.

Increasingly, the United States is becoming internationalized as a result of sophisticated communication technologies that put us in touch with countries known previously to only a few, through economic development and multinational investment, and by the immigration of people who are sometimes fleeing hostile homelands. US citizens, like others abroad, will need to be responsive to the demands of a multiethnic, multiracial, and multinational society. The challenges of this changing world can and will range from such dilemmas as ethical decisions of who can and will have access to expensive technology that saves and prolongs life; to the development of conflict management strategies for peaceful coexistence with neighbors whose behaviors, beliefs, and values are strongly shaped by their religious, cultural, and ethnic backgrounds and socioeconomic circumstances. With the inauguration of this section, US psychology is invited to consider its contribution to meeting the needs of a changing society. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment of myocardial lesion size during in vitro radio frequency catheter ablation

We report our experience with a system that utilizes changes in several biophysical characteristics of cardiac tissue to determine lesion formation and to estimate lesion size both on and off-line in vitro during radio frequency (RF) energy delivery. We analyzed the reactive and resistive components of tissue impedance and tracked the change of phase angle during RF ablation. We correlated the amount of tissue damage with these and other biophysical parameters and compared them with off-line analysis. We found that there are irreversible changes in the reactive and resistive components of impedance that occurred during tissue ablation. The irreversible changes of these components are greater in magnitude, and correlate better with the size of lesions than that of impedance alone that is currently used. Numerically, the best single on-line and off-line correlation for combined perpendicular and parallel electrode orientation was with phase angle. On-line and off-line capacitance and susceptance correlations were essentially similar suggesting that they may be useful as lesion size predictors, given these parameter's persistent change without temperature sensitivity. This study indicates that it is technically feasible to assess lesion formation using biophysical parameters.     

Characterization of poly(L-lactide)-block-poly(ethylene oxide)-block-poly(L-lactide) triblock copolymer by liquid chromatography at the critical condition and by MALDI-TOF mass spectrometry

Poly(L-lactide)-block-poly(ethylene oxide)-block-poly(L-lactide) triblock copolymers (PLLA-b-PEO-b-PLLA) were fractionated in terms of the number of LLA units by liquid chromatography at the critical condition (LCCC) of PEO block. The fractionated samples were identified using MALDI-TOF mass spectrometry. The dependence of the LCCC retention of the diblock and triblock copolymers on the degree of polymerization of PLLA block(s) follows Martin's rule very well. Unlike the case of PEO-b-PLLA diblock copolymer reported earlier (Lee, H.; et al. Macromolecules 1999, 32, 4143), however, a splitting of the elution peaks containing the same number of LLA units was found. The peak splitting was ascribed to the different length distributions of PLLA blocks at the two ends of the PEO block. From the relative intensities of the peaks, the split peaks were assigned to different isomeric structures of the PLLA blocks. From these results we conclude that the interaction of the triblock copolymers with the stationary phase is affected by the distribution of the interacting blocks at the two ends of the center PEO block, in addition to the total number of LLA units in the triblock copolymer.     

Automatic Generation of Redundant Models for Permutation Constraint Satisfaction Problems

If we have two representations of a problem as constraint satisfaction problem (CSP) models, it has been shown that combining the models using channeling constraints can increase constraint propagation in tree search CSP solvers. Handcrafting two CSP models for a problem, however, is often time-consuming. In this paper, we propose model induction, a process which generates a second CSP model from an existing model using channeling constraints, and study its theoretical properties. The generated induced model is in a different viewpoint, i.e., set of variables. It is mutually redundant to and can be combined with the input model, so that the combined model contains more redundant information, which is useful to increase constraint propagation. We also propose two methods of combining CSP models, namely model intersection and model channeling. The two methods allow combining two mutually redundant models in the same and different viewpoints respectively. We exploit the applications of model induction, intersection, and channeling and identify three new classes of combined models, which contain different amounts of redundant information. We construct combined models of permutation CSPs and show in extensive benchmark results that the combined models are more robust and efficient to solve than the single models.     

Identity ambiguity and the promises and practices of hybrid e-HRM project teams

The role of IS project team identity work in the enactment of day-to-day relationships with their internal clients is under-researched. We address this gap by examining the identity work undertaken by an electronic human resource management (e-HRM) ‘hybrid’ project team engaged in an enterprise-wide IS implementation for their multi-national organisation. Utilising social identity theory, we identify three distinctive, interrelated dimensions of project team identity work (project team management, team ‘value propositions’ (promises) and the team’s ‘knowledge practice’). We reveal how dissonance between two perspectives of e-HRM project identity work (clients’ expected norms of project team’s service and project team’s expected norms of themselves) results in identity ambiguity. Our research contributions are to identity studies in the IS project management, HR and hybrid literatures and to managerial practice by challenging the assumption that hybrid experts are the panacea for problems associated with IS projects.     

Technical and Environmental Sustainability Assessment of Water Distribution Systems

An environmental and technical sustainability assessment methodology is developed for both centralized and dual water distribution systems (WDSs) with and without fire flow scenarios. Technical sustainability of potable and reclaimed water networks is measured by a sustainability index (SI) assessment using reliability, resiliency, and vulnerability performance criteria. The U.S. Environmental Protection Agency EPANET software is used to simulate hydraulic (i.e. nodal pressure) and water quality (i.e. water age) analysis in a WDS. Total fresh water use and total energy intensity are considered as environmental sustainability criteria. The procedure considers two separate alternatives for meeting fire flows: (1) adding pumping to a system or (2) adding a non-potable WDS. The reclaimed system is designed using linear programming (LP) optimization. For each alternative, multi-criteria decision analysis (MCDA) is used to combine technical and environmental sustainability criteria for an urban WDS.     

Novel biodegradable amino acid containing anhydride oligomers for orthopedic applications

Novel synthetic biodegradable methacrylated anhydride oligomers (MAOs) based on methacrylated alaninyl maleamic acid (MAMA) and methacrylated aminocaproyl maleamic acid (MACMA) were synthesized and characterized. Injectable and in situ crosslinkable polymer networks were formulated by the copolymerization of MAOs with triethylene glycol dimethacrylate (TEGDMA). Furthermore, composites composed of MAOs, TEGDMA, and β‐tricalcium phosphate were prepared. The networks and composites were initiated by photopolymerization and redox polymerization, respectively. The initial compressive strength (CS) and diametral tensile strength (DTS) of these materials were determined and used to evaluate the effects of the MAO/TEGDMA ratios on the degradation behavior of the materials. The MAMA‐based composites had initial DTS values of 5.7–17.1 MPa and CS values of 30.7–114.2 MPa. The MACMA‐based composites had initial DTS values of 2.8–20.8 MPa and CS values of 19.1–119.5 MPa. During the course of degradation, the neat polymer resins lost 97 and 87% of their initial CS values after 6 months with 50/50 MAMA/TEGDMA and MACMA/TEGDMA ratios, respectively. The composite with a 25/75 MACMA/TEGDMA ratio showed a significant increase in CS after an initial decrease for 7 days and then lost 57% of its initial CS value after 3 months. The composite composed of 100% methacrylated anhydride oligomer (MAOs) showed complete degradation after 21 days. The degrees of conversion of the neat resins were 60–77%. Both the neat resins and the composites had low polymerization shrinkage ranging from 3.8 to 5.6%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1979–1984, 2005     

NMR-measurements for determination of local moisture content of coated wood

Local increased moisture content (MC) in wood constructions may result in different kinds of mechanical and, especially, biological degrading problems. Therefore, it is of great importance to control the MC of the material. However, there is at present no appropriate method for determining local MC in wood without destroying the product itself. Nondestructive measurements of local MC in wood is significant for the possibility of, for instance, monitoring the in situ MC in wood constructions over time, and thereby predicting potential problems. The nuclear magnetic resonance (NMR) technique has been shown to be valuable for the measurement of MC in wood. In this study, the possibility of utilizing this technique for local MC measurement in wood has been tested on wood samples exposed to water absorption for 72 h. The samples came from three different wood species treated with paint systems available on the market. In the wood samples an artificial “crack” had been created in the paint to introduce an area where the water could easily gain access to the wood. The results show the possibility of using the NMR technique for local MC measurements in wood. The measurement area, however, must be related to the properties of the material. In the case of wood, the measurement spot must be related to the early/latewood proportions. Further, a calibration of the NMR measurement must be made in relation to the expected density variations of the material.