Antibacterial properties of Ag-TiO2 composite sol-gel coatings

This study reveals the connection between the silver-doping method, the resulting nature and amount of the silver dopant together with the structural properties and the long-term antibacterial activity of composite coatings.</p

Investigation of the performance of thermally generated Au/Ag nanoislands for SERS and LSPR applications

In this work the performance of Au/Ag nanoislands was investigated for Surface Enhanced Raman Spectroscopy (SERS) and Localized Surface Plasmon Resonance (LSPR) applications. The nanoislands were generated by thermally annealing thin layers of silver and gold (having thickness in the 5-15 nm range), which were previously sputtered onto glass surfaces. Both pure (silver and gold nanoparticles – AuNP and AgNP) and composite metallic systems (silver-gold core-shell structures – Ag-Au core-shell) were evaluated based on their plasmonic and SERS sensitivity. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) were used to measure the size, shape and distribution of the nanoparticles to correlate them with the obtained plasmonic/Raman capabilities. The technological parameters of nanoisland fabrication for optimal sensitivities are presented

A class of residual distribution schemes and their relation to relaxation systems

Residual distributions (RD) schemes are a class of of high-resolution finite volume methods for unstructured grids. A key feature of these schemes is that they make use of genuinely multidimensional (approximate) Riemann solvers as opposed to the piecemeal 1D Riemann solvers usually employed by finite volume methods. In 1D, LeVeque and Pelanti [J. Comp. Phys. 172, 572 (2001)] showed that many of the standard approximate Riemann solver methods (e.g., the Roe solver, HLL, Lax-Friedrichs) can be obtained from applying an exact Riemann solver to relaxation systems of the type introduced by Jin and Xin [Comm. Pure Appl. Math. 48, 235 (1995)]. In this work we extend LeVeque and Pelanti's results and obtain a multidimensional relaxation system from which multidimensional approximate Riemann solvers can be obtained. In particular, we show that with one choice of parameters the relaxation system yields the standard N-scheme. With another choice, the relaxation system yields a new Riemann solver, which can be viewed as a genuinely multidimensional extension of the local Lax-Friedrichs scheme. This new Riemann solver does not require the use Roe-Struijs-Deconinck averages, nor does it require the inversion of an m-by-m matrix in each computational grid cell, where $m$ is the number of conserved variables. Once this new scheme is established, we apply it on a few standard cases for the 2D compressible Euler equations of gas dynamics. We show that through the use of linear-preserving limiters, the new approach produces numerical solutions that are comparable in accuracy to the N-scheme, despite being computationally less expensive.Comment: 46 pages, 14 figure

Resonance strengths in the 14N(p,γ)15O astrophysical key reaction measured with activation

The 14N(p,gamma)15O reaction plays a vital role in various astrophysical scenarios. Its reaction rate must be accurately known in the present era of high precision astrophysics. The cross section of the reaction is often measured relative to a low energy resonance, the strength of which must therefore be determined precisely. The activation method, based on the measurement of 15O decay, has not been used in modern measurements of the 14N(p,gamma)15O reaction. The aim of the present work is to provide strength data for two resonances in the 14N(p,gamma)15O reaction using the activation method. The obtained values are largely independent from previous data measured by in-beam gamma-spectroscopy and are free from some of their systematic uncertainties. Solid state TiN targets were irradiated with a proton beam provided by the Tandetron accelerator of Atomki using a cyclic activation. The decay of the produced 15O isotopes was measured by detecting the 511 keV positron annihilation gamma-rays. The strength of the Ep = 278 keV resonance was measured to be 13.4 +- 0.8 meV while for the Ep = 1058 keV resonance the strength is 442 +- 27 meV. The obtained Ep = 278 keV resonance strength is in fair agreement with the values recommended by two recent works. On the other hand, the Ep = 1058 keV resonance strength is about 20% higher than the previous value. The discrepancy may be caused in part by a previously neglected finite target thickness correction. As only the low energy resonance is used as a normalization point for cross section measurements, the calculated astrophysical reaction rate of the 14N(p,gamma)15O reaction and therefore the astrophysical consequences are not changed by the present results.Comment: Accepted for publication in Phys. Rev.