Topology, connectivity and electronic structure of C and B cages and the corresponding nanotubes

After a brief discussion of the structural trends which appear with increasing number of atoms in B cages, a one-to one correspondence between the connectivity of B cages and C cage structures will be proposed. The electronic level spectra of both systems from Hartree-Fock calculations is given and discussed. The relation of curvature introduced into an originally planar graphitic fragment to pentagonal 'defects' such as are present in buckminsterfullerene is also briefly treated. A study of the structure and electronic properties of B nanotubes will then be introduced. We start by presenting a solution of the free-electron network approach for a 'model boron' planar lattice with local coordination number 6. In particular the dispersion relation E(k) for the pi-electron bands, together with the corresponding electronic Density Of States (DOS), will be exhibited. This is then used within the zone folding scheme to obtain information about the electronic DOS of different nanotubes obtained by folding this model boron sheet. To obtain the self-consistent potential in which the valence electrons move in a nanotube, 'the March model' in its original form was invoked and results are reported for a carbon nanotube. Finally, heterostructures, such as BN cages and fluorinated buckminsterfullerene, will be briefly treated, the new feature here being electronegativity difference.Comment: 22 pages (revtex4) 12 figure

Caring for our country: wind erosion extent and severity maps for Australia, final report

The Wind Erosion Extent and Severity Maps (WEESMAP) project for Australia has been completed. As a result of the project significant improvements were made to both the soil and vegetation input data. These improvements include: • A new dynamic erodibility mask was created for the model,based on Fractional Cover Index (FCI) of Guerschman et al. (2009). • Increasing the soil descriptions available from 12 to 29 soils. • Replacing LAI GIS layer with the MODIS LAI layer, which no longer uses empirical relationships developed for AVHRR NDVI product. • The model was extend to a 10km resolution for the whole of the continent. Statistical comparison of the CEMSYS model before (Version 5) and after the soil/vegetation improvements (Version 6) shows that the model over estimated daily dust concentrations at 26 of the DustWatch nodes in 2009 by approximately 3 fold for V5 and underestimated it by 0.6 for V6. The mean error between modelled and observed dust levels was reduced for V6 (0.0227 to 0.0084). Finally V6 explained twice the level of variability in the observed data compared to V5 (0.2292 to 0.3956). Given the result was comparing 26 stations over 365 days, V6 appears extremely robust over the yearly period. In addition, the time series of available data was extended significantly. At the end of the project data the following data is available: • Version 650 km data is available from March2000–June2012. • Version 510 km dat is available for NSW/Victoria from February2000–June2012. • Version 610 km data is available nationally for 2002,2008,and 2009. Finally several other coding improvements were made to the model to increase performance. Consequently, it is now possible to produce 50 km and 10 km maps within 10 days of the external MODIS and Atmospheric data becoming available. This means it is now possible to use the CEMSYS in monthly reporting products

Time-resolved characterization of a pulsed discharge in a stationary bubble

In recent years, plasma generation in water has been proposed for the application of water treatment. The process efficiency is believed to be improved by the introduction of bubbles in the plasma active region. For further optimization, the initiating and developmental mechanisms of plasma inside bubbles need to be understood to a greater extent. In order to meet this necessity, we investigated pulsed electrical discharge inside a stationary bubble in water. This paper deals with the evolution of the discharge and of the bubble shape during discharge, investigated by electrical characterization and fast imaging. Only several microseconds after the application of the voltage pulse, plasma light is observed. Different phases are observed during plasma formation. The plasma is strongest at the bubble surface, causing the surrounding water to evaporate. This leads to both the formation of propagating streamers into the water and the expansion and collapse of the bubble. These observations show that plasma inside a bubble has the strongest activity at the bubble surface, making it attractive for water treatment

Fire history reconstruction in grassland ecosystems: amount of charcoal reflects local area burned

Citation: Leys, B., Brewer, S. C., McConaghy, S., Mueller, J., & McLauchlan, K. K. (2015). Fire history reconstruction in grassland ecosystems: amount of charcoal reflects local area burned. Environmental Research Letters, 10(11), 114009. https://doi.org/10.1088/1748-9326/10/11/114009Fire is one of the most prevalent disturbances in the Earth system, and its past characteristics can be reconstructed using charcoal particles preserved in depositional environments. Although researchers know that fires produce charcoal particles, interpretation of the quantity or composition of charcoal particles in terms of fire source remains poorly understood. In this study, we used a unique four-year dataset of charcoal deposited in traps from a native tallgrass prairie in mid-North America to test which environmental factors were linked to charcoal measurements on three spatial scales. We investigated small and large charcoal particles commonly used as a proxy of fire activity at different spatial scales, and charcoal morphotypes representing different types of fuel. We found that small (125–250 μ m) and large (250 μ m–1 mm) particles of charcoal are well-correlated (Spearman correlation = 0.88) and likely reflect the same spatial scale of fire activity in a system with both herbaceous and woody fuels. There was no significant relationship between charcoal pieces and fire parameters <500 m from the traps. Moreover, local area burned (<5 km distance radius from traps) explained the total charcoal amount, and regional burning (200 km radius distance from traps) explained the ratio of non arboreal to total charcoal (NA/ T ratio). Charcoal variables, including total charcoal count and NA/ T ratio, did not correlate with other fire parameters, vegetation cover, landscape, or climate variables. Thus, in long-term studies that involve fire history reconstructions, total charcoal particles, even of a small size (125–250 μ m), could be an indicator of local area burned. Further studies may determine relationships among amount of charcoal recorded, fire intensity, vegetation cover, and climatic parameters

Plasma-laser assisted synthesis of nanoparticles for antibacterial coatings

The “green synthesis” of colloidal nanoparticles and their application for the antibacterial coatings is based on the plasma-laser assisted ablation in liquids. Nanoparticles are synthesized through the process of laser ablation of target in water, which enables additional advantages in comparison with the other standard wet chemical synthesis, such as simplicity and complete utilization of materials. Furthermore, these nanoparticles are used and tested for antibacterial coatings on polymers, where they are grafted or imbedded through atmospheric pressure plasma assisted processes. The advantages of different coatings made from those nanoparticles are presented as well.Plasmatexinfo:eu-repo/semantics/publishedVersio

Molecular clusters of hydrogen, deuterium, and tritium: especially cationic species H3+(H2)m: m=2, 5 and 14

Presentado a la Conferencia "Nanotechnology: Power of Computation for Nanotechnology" celebrada en Gran Canaria (España) el 19 de mayo de 2003.Two recent experimental studies by Zweiback et al. and by Gobet et al. have motivated us to study the ground-state geometry and the consequent electronic structure of the singly-charged cationic hydrogen cluster H3+(H2)m for m=2,5 and 14, using at first the Hartree-Fock approximation. For the H+7 cluster the fully optimized ground-state geometry yeilds an isosceles triangle H3, with charge ~ 0.85(e), and sides 0.852 and 0.884 Å flanked by two H2 molecules lying parallel to each other, wiht bond lengths of 0.740 Å. In contrast, for the H+13 cluster, the central 'building block' is equilateral H3 with bond length 0.861 Å, and with charge ~0.815(e). This configuration of H3 is flanked by three almost-parallel H2 molecules with bond length 0.739 A. MP2 refinements of geometry, charge distribution and normal mode vibrational frequencies of the cationic tritium cluster T+7 and the corresponding deuterium cluster D+13 are also reported. Finally, Hartree-Fock and MP2 results are recorded for H+13.KVA thanks the University of Antwerp for financial support under grant GOA-BOF-UA nr 23. This work received financial support from MCyT of Spain Grants MAT2001-04499 and MAT2001-0946 and the EC-RTN program NANOPHASE (contract HPRN-CT-2000-00167), Basque Country University and Basque Hezkuntza Saila.Peer reviewe

Logics of marginalisation in health and social care reform:integration, choice, and provider-blind provision

The period 2010–2013 was a time of far-reaching structural reforms of the National Health Service in England. Of particular interest in this paper is the way in which radical critiques of the reform process were marginalised by pragmatic concerns about how to maintain the market-competition thrust of the reforms while avoiding potential fragmentation. We draw on the Essex school of political discourse theory and develop a ‘nodal’ analytical framework to argue that widespread and repeated appeals to a narrative of choice-based integrated care served to take the fragmentation ‘sting’ out of radical critiques of the pro-competition reform process. This served to marginalise alternative visions of health and social care, and to pre-empt the contestation of a key norm in the provision of health care that is closely associated with the notions of ‘any willing provider’ and ‘any qualified provider’: provider-blind provision

AstroPix: investigating the potential of silicon pixel sensors in the future of gamma-ray astrophysics

This paper details preliminary photon measurements with the monolithic silicon detector ATLASPix, a pixel detector built and optimized for the CERN experiment ATLAS. The goal of this paper is to determine the promise of pixelated silicon in future space-based gamma-ray experiments. With this goal in mind, radioactive photon sources were used to determine the energy resolution and detector response of ATLASPix; these are novel measurements for ATLASPix, a detector built for a ground-based particle accelerator. As part of this project a new iteration of monolithic Si pixels, named AstroPix, have been created based on ATLASPix, and the eventual goal is to further optimize AstroPix for gamma-ray detection by constructing a prototype Compton telescope.The energy resolution of both the digital and analog output of ATLASPix is the focus of this paper, as it is a critical metric for Compton telescopes. It was found that with the analog output of the detector, the energyresolution of a single pixel was 7.69 +/- 0.13% at 5.89 keV and 7.27 +/- 1.18% at 30.1 keV, which exceeds the conservative baseline requirements of 10% resolution at 60 keV and is an encouraging start to an optimistic goal of<2% resolution at 60 keV. The digital output of the entire detector consistently yielded energy resolutions that exceeded 100% for different sources. The analog output of the monolithic silicon pixels indicates that thisis a promising technology for future gamma-ray missions, while the analysis of the digital output points to the need for a redesign of future photon-sensitive monolithic silicon pixel detectors

How Advanced Change Patterns Impact the Process of Process Modeling

Process model quality has been an area of considerable research efforts. In this context, correctness-by-construction as enabled by change patterns provides promising perspectives. While the process of process modeling (PPM) based on change primitives has been thoroughly investigated, only little is known about the PPM based on change patterns. In particular, it is unclear what set of change patterns should be provided and how the available change pattern set impacts the PPM. To obtain a better understanding of the latter as well as the (subjective) perceptions of process modelers, the arising challenges, and the pros and cons of different change pattern sets we conduct a controlled experiment. Our results indicate that process modelers face similar challenges irrespective of the used change pattern set (core pattern set versus extended pattern set, which adds two advanced change patterns to the core patterns set). An extended change pattern set, however, is perceived as more difficult to use, yielding a higher mental effort. Moreover, our results indicate that more advanced patterns were only used to a limited extent and frequently applied incorrectly, thus, lowering the potential benefits of an extended pattern set