Organic layer formation and sorption of U(vi) on acetamide diethylphosphonate-functionalized mesoporous silica.

Acetamide diethylphosphonate (AcPhos)-functionalized silica has been shown to have a high affinity for U(vi) in pH 2-3 nitric acid. Previous work with AcPhos-functionalized silica has focused on actinide and lanthanide extraction under various conditions, but has shown poor reproducibility in the functionalization process. For this work, four AcPhos-functionalized SBA-15 materials were synthesized and evaluated based on their U(vi) sorption capacity and their stability in nitric acid. Materials synthesized using pyridine as a basic catalyst were shown to form a greater fraction of polymeric structures at the silica surface, which correlated with higher structural integrity upon contact with acidic solutions. Single-pulse 31P and 1H NMR spectra of these materials show evidence of phosphonic acid groups, as well as hydrogen-bonding interactions either between ligands or with the silica surface. Additionally, these materials were found to have significantly higher U(vi) sorption capacities and Keq values than the materials synthesized without pyridine, most likely due to the ion-exchange properties of the phosphonic acid groups. The 31P-31P DQ-DRENAR NMR technique was used to compare the average strength of dipolar coupling interactions between phosphorus atoms for the four materials. Because the strength of dipolar coupling interactions depends on the number and proximity of neighboring spins, this technique provides information about the average density of ligands on the surface. The conventional functionalization procedure yielded materials with the lowest average surface ligand density, while those using extended reaction times and the pyridine base catalyst yielded materials with higher surface ligand densities

Local structure of glassy lithium phosphorus oxynitride thin films: a combined experimental and ab initio approach

Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion conductor displaying exemplary cyclability against lithium metal anodes. There is no definitive explanation for this stability due to the limited understanding of the structure of LiPON. We provide a structural model of RF-sputtered LiPON via experimental and computational spectroscopic methods. Information about the short-range structure results from 1D and 2D solid-state nuclear magnetic resonance experiments investigating chemical shift anisotropy and dipolar interactions. These results are compared with first principles chemical shielding calculations of Li-P-O/N crystals and ab initio molecular dynamics-generated amorphous LiPON models to unequivocally identify the glassy structure as primarily isolated phosphate monomers with N incorporated in both apical and as bridging sites in phosphate dimers. Structural results suggest LiPON's stability is a result of its glassy character. Free-standing LiPON films are produced that exhibit a high degree of flexibility highlighting the unique mechanical properties of glassy materials

XMM-Newton spectroscopy of high redshift quasars

We present XMM-Newton X-ray spectra and optical photometry of four high redshift (z=2.96-3.77) quasars, [HB89] 0438-436, [HB89] 2000-330, [SP89] 1107+487 and RX J122135.6+280613; of these four objects the former two are radio-loud, the latter two radio-quiet. Model fits require only a power law with Galactic absorption in each case; additional intrinsic absorption is also needed for [HB89] 0438-436 and RX J122135.6+280613. The spectra are hard (Gamma \~1.7 for [HB89] 0438-436, [HB89] 2000-330 and ~1.4 for RX J122135.6+280613) with the exception of [SP89]~1107+487 which is softer (Gamma ~2.0); the combined Galactic and intrinsic absorption of lower energy X-rays in the latter source is much less significant than in the other three. The two intrinsically unabsorbed sources have greater optical fluxes relative to the X-ray contributions at the observed energies. While there is no need to include reflection or iron line components in the models, our derived upper limits (99% confidence) on these parameters are not stringent; the absence of these features, if confirmed, may be explained in terms of the high power law contribution and/or a potentially lower albedo due to the low disc temperature. However, we note that the power-law spectrum can be produced via mechanisms other than the Comptonization of accretion disc emission by a corona; given that all four of these quasars are radio sources at some level we should also consider the possibility that the X-ray emission originates, at least partially, in a jet.Comment: Accepted for publication in MNRA

Project MERCI (Medical Emergency Response Care Initiative)

This project proposed a program intended to foster a greater sense of community, shared responsibility, and mutual aid within Virginia Commonwealth University. The group members saw an opportunity to develop the expectation that students, faculty and staff will come to one another’s aid, and to provide the tools necessary to help ensure our mutual safety and health. The medical emergencies as an initial project were selected, focusing their research on the current status of CPR and first-aid training and the placement of automated external defibrillators (AEDs) at VCU

An argument for the use of Aristotelian method in bioethics

The main claim of this paper is that the method outlined and used in Aristotle's Ethics is an appropriate and credible one to use in bioethics. Here “appropriate” means that the method is capable of establishing claims and developing concepts in bioethics and “credible” that the method has some plausibility, it is not open to obvious and immediate objection. It begins by suggesting why this claim matters and then gives a brief outline of Aristotle's method. The main argument is made in three stages. First, it is argued that Aristotelian method is credible because it compares favourably with alternatives. In this section it is shown that Aristotelian method is not vulnerable to criticisms that are made both of methods that give a primary place to moral theory (such as utilitarianism) and those that eschew moral theory (such as casuistry and social science approaches). As such, it compares favourably with these other approaches that are vulnerable to at least some of these criticisms. Second, the appropriateness of Aristotelian method is indicated through outlining how it would deal with a particular case. Finally, it is argued that the success of Aristotle's philosophy is suggestive of both the credibility and appropriateness of his method.</p