Effects of Mev Si Ions and Thermal Annealing on Thermoelectric and Optical Properties of SiO2/SiO2+Ge Multi-nanolayer thin Films

AbstractThermoelectric generator devices have been prepared from 200 alternating layers of SiO2/SiO2+Ge superlattice films using DC/RF magnetron sputtering. The 5 MeV Si ionsbombardmenthasbeen performed using the AAMU Pelletron ion beam accelerator to formquantum dots and / or quantum clusters in the multi-layer superlattice thin films to decrease the cross-plane thermal conductivity, increase the cross-plane Seebeck coefficient and increase the cross-plane electrical conductivity to increase the figure of merit, ZT. The fabricated devices have been annealed at the different temperatures to tailor the thermoelectric and optical properties of the superlattice thin film systems. While the temperature increased, the Seebeck coefficient continued to increase and reached the maximum value of -25μV/K at the fluenceof 5x1013 ions/cm2. The decrease in resistivity has been seen between the fluence of 1x1013 ions/cm2 and 5x1013 ions/cm2. Transport properties like Hall coefficient, density and mobility did not change at all fluences. Impedance spectroscopy has been used to characterize the multi-junction thermoelectric devices. The loci obtained in the C*-plane for these data indicate non-Debye type relaxation displaying the presence of the depression parameter

PIXE pollution studies across Europe

We collected vegetation and soil samples from various locations along a route covering Eastern and Western Europe. We measured the level of elemental pollution in different places uniformly spread across the continent to determine which of them may have common sources. To achieve these objectives, samples were collected along the main roads from Romania to Portugal and analyzed using in-air PEE (Particle-Induced X-ray Emission)

Modification of surface morphology of UHMWPE for biomedical implants

Ion-Beam-Based Nanofabrication; San Francisco, CA; United States; 10 April 2007 through 12 April 2007Ultra High Molecular Weight Polyethylene (UHMWPE) samples were implanted with metal and metal-gas hybrid ions (Ag, Ag+N, C+H, C+H+Ar, Ti+O) by using improved MEVVA Ion implantation technique [1,2]. An extraction voltage of 30 kV and influence of 1017 ions/cm2 were attempted in this experiment, to change their surface morphologies in order to understand the effect of ion implantation on the surface properties of UHMWPEs. Characterizations of the implanted samples with RBS , ATR - FTIR, spectra were compared with the un-implanted ones . Implanted and unimplanted samples were also thermally characterized by TGA and DSC. It was generally observed that C-H bond concentration seemed to be decreasing with ion implantation and the results indicated that the chain structure of UHMWPE were changed and crosslink density and polymer crystallinity were increased compared to unimplanted ones resulting in increased hardness. It was also observed that nano size cracks (approx.10nm) were significantly disappeared after Ag implantation, which also has an improved antibacterial effect. Contact angle measurements showed that wettability of samples increased with ion implantation. Results showed that metal and metal+gas hybrid ion implantation could be an effective way to improve the surface properties of UHMWPE to be used in hip and knee prosthesis.Center for Irradiation of Materials, Alabama A&M Universit

Manipulating national identity: The strategic use of rhetoric by supporters and opponents of the ‘Cronulla riots’ in Australia

This research explores the role of opinion-based groups in understanding responses to racist violence such as the 2005 Cronulla riots in Australia. Traditionally, explanations of collective action in social psychology and sociology focus on conflict between broad social categories. We propose that the responses to the riots can be understood not only as inter-group conflict between Muslims and non-Muslims, or an in-group argument amongst non-Muslims, but as a bona fide inter-group conflict between supporters and opponents of the riots. We argue that these groups use rhetoric in attempts to claim dominant status within society by aligning their identities with positively valued social categories such as ethnicities and national identities. The analysis of rhetoric from the groups supporting and opposing the riots demonstrates consistent, albeit contested, attempts to align support for the riot with the Australian national category in conflict with countervailing attempts to align opposition to the riot with the same national category

Enhanced biocompatibility of GPC by MeV ion bombardment

2005 MRS Spring Meeting -- 28 March 2005 through 1 April 2005 -- San Francisco, CA -- 69749Glassy Polymeric Carbon (GPC) is completely biocompatible and is widely used as a material for artificial heart valves and in other biomedical applications. Although it is ideally suited for fluid flow in the blood stream, collagenous tissue that normally forms around the moving parts of a GPC heart valve sometimes loses adhesion and creates embolisms downstream. We have shown that moderate fluence of MeV ions, especially oxygen ions, increases the surface roughness of GPC on a scale appropriate for enhancing tissue adhesion. Silver ion implantation is shown to inhibit cell growth on GPC. Ion bombardment also increases the surface hardness of GPC, already an extremely hard material. In vitro biocompatibility tests have been carried out with model cell lines to demonstrate that MeV ion bombardment can favorably influence the surface of GPC for biomedical applications. © 2005 Materials Research Society

Studying the destruction of various fluoropolymers caused by y-irradiation and MeV protons

While fluoropolymers are normally used as anti-adherent coating, they are intensely investigated for potential use in various radiation dosimeter applications as well as space technology. In order to understand the discrepancy between high chemical and thermal stability and low radiation stability of various fluoropolymers, we are bombarding them with 1 MeV protons to fluences up to 2*10^15 protons/cm^2 as well as subjected some of them to у-irradiation by dose of 10 kGy. During bombardment we are monitoring the emission of chemical species with a residual gas analyzer (RGA). у - irradiated samples were tested by Radio thermoluminescence (RTL) method. The results we present here are a good indicator that material damage happens much earlier than 2*10^15 protons/cm^2 and that further work should be addressed at much smaller exposures. RTL also can be used at small doses of Irradiation (10-30 kGy). The thermomechanical curve (TMC) of radiation-free polyvlnyledenefluoride (PVDF) is characteristic for topologlcally di-block amorphous polymer of quasi-crossing structure. In the temperature range of from 173 К up to 228 К polymer is vitrified. The vitrification temperature of PVDF is 228 K. All molecular-relaxation and quantitative characteristics of PVDF were determined before and after its Irradiation by protons. Protons caused significant changes in PVDF. From di-block amorphous it transformed in to amorphous-crystalline structure. An appreciable influence of dose at proton irradiation of polymer was revealed both on topological level and on molecular-relaxation one