Nanoporous networks as effective stabilisation matrices for nanoscale zero-valent iron and groundwater pollutant removal

Nanoporous networks exhibit effective stabilisation properties for nanoscale zero-valent iron (nZVI) and nZVI, with its reductive potentials and wide availability, offers degradative remediation of environmental contaminants.</p

Instability and Spatiotemporal Dynamics of Alternans in Paced Cardiac Tissue

We derive an equation that governs the spatiotemporal dynamics of small amplitude alternans in paced cardiac tissue. We show that a pattern-forming linear instability leads to the spontaneous formation of stationary or traveling waves whose nodes divide the tissue into regions with opposite phase of oscillation of action potential duration. This instability is important because it creates dynamically an heterogeneous electrical substrate for inducing fibrillation if the tissue size exceeds a fraction of the pattern wavelength. We compute this wavelength analytically as a function of three basic length scales characterizing dispersion and inter-cellular electrical coupling.Comment: 4 pages, 3 figures, submitted to PR

MPGDs in Compton imaging with liquid-xenon

The interaction of radiation with liquid xenon, inducing both scintillation and ionization signals, is of particular interest for Compton-sequences reconstruction. We report on the development and recent results of a liquid-xenon time-projection chamber, dedicated to a novel nuclear imaging technique named "3 gamma imaging". In a first prototype, the scintillation is detected by a vacuum photomultiplier tube and the charges are collected with a MICROMEGAS structure; both are fully immersed in liquid xenon. In view of the final large-area detector, and with the aim of minimizing dead-zones, we are investigating a gaseous photomultiplier for recording the UV scintillation photons. The prototype concept is presented as well as preliminary results in liquid xenon. We also present soft x-rays test results of a gaseous photomultiplier prototype made of a double Thick Gaseous Electron Multiplier (THGEM) at normal temperature and pressure conditions.Comment: presented at MPGD09, CRETE, June 2009; to be published in JINST Proceedings, PDF, 10 pages, 11 figure

Mineral Resources of the Marble Canyon Wilderness Study Area, White Pine County, Nevada, and Millard County, Utah

The 19,150-acre Marble Canyon Wilderness Study Area (NV-040-086) was evaluated for mineral resources (known) and mineral resource potential (undiscovered), and field work was conducted in 1987. The acreage includes 6,435 acres that is now designated as part of the Mount Moriah Wilderness under the Nevada Wilderness Protection Act of 1989 (S. 974), most but not all of which is included in 8,300 acres fro which the U.S. Bureau of Land Management requested a mineral survey. In this report, the wilderness study area, or simply the study area refers to the entire 19,150-acre tract. The area in underlain by quartzite shale and carbonate rocks. The norther Snake Range decollement is a detachment surface within the study area that separates rocks of similar age but different metamorphic grade. Large inferred subeconomic limestone and marble resources i the study area have no special or unique properties. The mineral resource potential for limestone and marble is high in two canyons and is moderate in the rest of the wilderness study area. Parts of the study area above and along the northern Snake Range decollement have low potential for undiscovered deposits of gold, silver, copper, lead, zinc, tungsten, molybdenum, beryllium, and flourite. A zone around barite-bearing rock penetrated by adits inside the southeast boundary of the study area has moderate potential for barite, and the surrounding area has low potential for barite; both areas also have low potential for silver, copper, lead, zinc, and tungsten. The entire study area has moderate potential for oil and gas and low potential for geothermal energy resources

Rubber Impact on 3D Textile Composites

A low velocity impact study of aircraft tire rubber on 3D textile-reinforced composite plates was performed experimentally and numerically. In contrast to regular unidirectional composite laminates, no delaminations occur in such a 3D textile composite. Yarn decohesions, matrix cracks and yarn ruptures have been identified as the major damage mechanisms under impact load. An increase in the number of 3D warp yarns is proposed to improve the impact damage resistance. The characteristic of a rubber impact is the high amount of elastic energy stored in the impactor during impact, which was more than 90% of the initial kinetic energy. This large geometrical deformation of the rubber during impact leads to a less localised loading of the target structure and poses great challenges for the numerical modelling. A hyperelastic Mooney-Rivlin constitutive law was used in Abaqus/Explicit based on a step-by-step validation with static rubber compression tests and low velocity impact tests on aluminium plates. Simulation models of the textile weave were developed on the meso- and macro-scale. The final correlation between impact simulation results on 3D textile-reinforced composite plates and impact test data was promising, highlighting the potential of such numerical simulation tools

Correlation between processing parameters and mechanical properties as a function of substrate polarisation and depth in a nitrided 316 L stainless steel using nanoindentation and scanning force microscopy

The effects of substrate polarisation in a nitrided 316L stainless steel have been investigated in an attempt to accurately correlate processing parameters with surface mechanical properties. Nanoindentation allows the Vickers hardness to be measured at precise depths, meaning that the variation in properties with nitriding depth can be evaluated and correlated with the process parameters. By combining such measurements with surface imaging techniques (scanning force microscopy and scanning electron microscopy) and electron probe micro-analysis, it is possible to explain both the mechanical property and microstructural variations of such layers, having been produced in a low pressure arc plasma discharge at 680 K with a mixed Ar-N2 gas. In this study the nanoindentation technique is presented as a new and valid method for the characterisation of nitrided layers, shown by hardness measurements on four nitrided layers produced with different substrate polarisation potentials. The net advantages of such an approach over conventional methods (e.g. microhardness testing) and the possibility of analysing microstructural phases previously not well detected by X-ray diffraction, make nanoindentation an attractive tool for a more complete understanding of the nitriding process

Experimental Study on the Low-velocity Impact Behavior of Foam-core Sandwich Panels

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97064/1/AIAA2012-1701.pd

Reorganization Energy for Internal Electron Transfer in Multicopper Oxidases.

We have calculated the reorganization energy for the intramolecular electron transfer between the reduced type 1 copper site and the peroxy intermediate of the trinuclear cluster in the multicopper oxidase CueO. The calculations are performed at the combined quantum mechanics and molecular mechanics (QM/MM) level, based on molecular dynamics simulations with tailored potentials for the two copper sites. We obtain a reorganization energy of 91-133 kJ/mol, depending on the theoretical treatment. The two Cu sites contribute by 12 and 22 kJ/mol to this energy, whereas the solvent contribution is 34 kJ/mol. The rest comes from the protein, involving small contributions from many residues. We have also estimated the energy difference between the two electron-transfer states and show that the reduction of the peroxy intermediate is exergonic by 43-87 kJ/mol, depending on the theoretical method. Both the solvent and the protein contribute to this energy difference, especially charged residues close to the two Cu sites. We compare these estimates with energies obtained from QM/MM optimizations and QM calculations in a vacuum and discuss differences between the results obtained at various levels of theory