Objective: The purpose of the research presented in this thesis is to explore new biomedical applications of synchrotron imaging in the field of neurosurgery.<p> Methods: Four different studies were performed, all using advanced biomedical synchrotron imaging techniques. In the first two experiments, diffraction enhanced imaging (DEI) and analyzer based imaging (ABI) were utilized to study the anatomy of the rat spine and a novel rat model of spinal fusion. In a third experiment, K-edge digital subtraction angiography (KEDSA) was used to study the cerebral vasculature in a rabbit model. In a fourth experiment, rapid scanning X-ray fluorescence spectroscopy (RS-XRF) was used to study stem cell migration in a rat stroke model.<p> Results: DEI had superior visualization of ligamentous and boney anatomy in a rat model. Analyzer based imaging was able to visualize physiologic amounts of bone graft material and progressive incorporation into the spine. Intravenous KEDSA showed excellent visualization of the cerebral vasculature in a rabbit model. Finally, RS-XRF was used to track iron labeled stem cells implanted in a rat stroke model. The technique was able to visualize the iron that represented the stem cell migration. This was correlated with histology and magnetic resonance imaging information.<p> Conclusions: 1) Diffraction enhanced imaging has excellent contrast for the study of boney and ligamentous anatomy. 2) Analyzer based imaging is an excellent tool to study animal models of boney fusion. 3) Intravenous KEDSA is able to clearly visualize the arterial vasculature in a rabbit model. 4) RS-XRF can be used to study the migration patterns of implanted iron labeled stem cells.

Objective: The purpose of the research presented in this thesis is to explore new biomedical applications of synchrotron imaging in the field of neurosurgery.<p> Methods: Four different studies were performed, all using advanced biomedical synchrotron imaging techniques. In the first two experiments, diffraction enhanced imaging (DEI) and analyzer based imaging (ABI) were utilized to study the anatomy of the rat spine and a novel rat model of spinal fusion. In a third experiment, K-edge digital subtraction angiography (KEDSA) was used to study the cerebral vasculature in a rabbit model. In a fourth experiment, rapid scanning X-ray fluorescence spectroscopy (RS-XRF) was used to study stem cell migration in a rat stroke model.<p> Results: DEI had superior visualization of ligamentous and boney anatomy in a rat model. Analyzer based imaging was able to visualize physiologic amounts of bone graft material and progressive incorporation into the spine. Intravenous KEDSA showed excellent visualization of the cerebral vasculature in a rabbit model. Finally, RS-XRF was used to track iron labeled stem cells implanted in a rat stroke model. The technique was able to visualize the iron that represented the stem cell migration. This was correlated with histology and magnetic resonance imaging information.<p> Conclusions: 1) Diffraction enhanced imaging has excellent contrast for the study of boney and ligamentous anatomy. 2) Analyzer based imaging is an excellent tool to study animal models of boney fusion. 3) Intravenous KEDSA is able to clearly visualize the arterial vasculature in a rabbit model. 4) RS-XRF can be used to study the migration patterns of implanted iron labeled stem cells.

The Rossendorf Beamline (ROBL) - located at BM20 of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France - is in operation since 1998. This 6th report covers the period from January 2007 to December 2008. In these two years, 50 peerreviewed papers have been published based on experiments done at the beamline. The average citation index, which increased constantly over the years, has now reached 3.5 (RCH) and 3.0 (MRH), indicating that papers are predominately published in journals with high impact factors. Six exemplary highlight reports on the following pages should demonstrate the scientific strength and diversity of the experiments performed on the two end-stations of the beamline, dedicated to Radiochemistry (RCH) and Materials Research (MRH). Demand for beamtime remains very high as in the previous years, with an average oversubscription rate of 1.8 for ESRF experiments. The attractiveness of our beamline is based upon the high specialization of its two end-stations. RCH is one of only two stations in Europe dedicated to x-ray absorption spectroscopy of actinides and other radionuclides. The INE beamline at ANKA provides superior experimental flexibility and extends to lower energies, including important elements like P and S. In contrast, ROBL-RCH provides a much higher photon flux, hence lower detection limits crucial for environmental samples, and a higher energy range extending to elements like Sb and I. Therefore, both beamlines are highly complementary, covering different aspects of radiochemistry research. Once the MARS beamline at SOLEIL is ready to run radionuclides (>2010), it will cover a third niche (Materials Science of actinides, including irradiated fuel) not accessible for the two other beamlines. The Materials Research Hutch MRH has realized an increasing number of in-situ investigations in the last years. On the one hand thin film systems were characterized during magnetron sputtering. On the other hand diffraction experiments under controlled atmosphere were performed. A high variety of experimental parameters was covered by varying pressure, temperature and atmospheric compositions including highly reactive gases. Furthermore structural investigations were combined with electrical conductivity measurements. These kind of in-situ experiments are the key to monitor and understand reaction mechanism or the influence of process parameters, which are again the basis to tailor materials properties on demand. The core competences of MRH are these experimental possibilities, which make it unique among other diffraction beamlines. In fall 2007, ROBL was reviewed by an international panel on behalf of the ESRF. The very positive panel report recommended a renewal of the contract between ESRF and FZD for the next five years, and a major upgrade of critical optical components of the beamline to keep ROBL competitive for the next decade. The FZD will provide 2 Mio € from 2009 to 2011 for this upgrade, which will be performed in parallel to the major upgrade of the ESRF to minimize the downtime. According to the current plans of the ESRF, our users have to expect that ROBL will have only limited or no operation for several months from August 2011 on. Since July 2004 the beamline is a member of the pooled facilities of ACTINET – European Network of Excellence. In the reported period, RCH has provided 27 % of its inhouse beamtime to perform 11 ACTINET experiments. The success of ACTINET within FP-6 has now led to a renewal of ACTINET within FP-7, running until end of 2011.

Rasmussen et al. (2001) observed that Sb concentrations were enriched in household dust relative to outdoor garden soil samples and suspected the enrichment may be due to anthropogenic internal sources. Antimony trioxide (Sb2O3) is commonly found in various halogen flame-retardants and is a suspected carcinogen (IARC, 1989). North Americans spend a significant proportion of their time indoors, and are frequently exposed to dust. Therefore, characterizing potentially harmful metal(loid)s (i.e. Sb2O3) has become of increasing priority to various governmental agencies. A combination of micro-analytical synchrotron techniques (micro X-ray fluorescence (µXRF), micro X-ray diffraction (µXRD), micro X-ray absorption near-edge spectroscopy (µXANES)) and environmental scanning electron microscopy (ESEM) were used to characterize five archived samples provided by Health Canada. Two samples were in the 90th percentile for Sb content in household dust from a suite of 50 houses studied by Rasmussen et al. (2001). The corresponding garden soils of these houses were also analysed. The fifth sample was a children’s bedroom from a house studied in detail by Walker et al. (2010). Synchrotron microanalysis of Sb presents many challenges, given its high absorption energy (31 KeV), and the relatively low concentrations and small particles in house dust. An appropriate experimental set-up was optimized after several trials. Antimony within household dust is currently not of toxicological concern (EU, 2008). Micro-XRF maps of household dust samples and corresponding garden soils from sample to sample displayed distinct element correlations of Sb with other elements. This suggests that Sb species present within homes are not restricted to a single source. Potential sources are Pb based or Sb containing pigments (Naples Yellow), metal alloys and possibly flame-retardants. The lack of correlation between Sb hot spots in the garden soil sample compared to the household dust suggests the source of interior Sb may not be external. A collaborative project with another student in the Environmental Studies Masters program was conducted to examine the potential for interdisciplinary work. Effective communication was the greatest barrier but there was success in the creation of a forum where people could critically think about the various nuances of household dust. / Thesis (Master, Environmental Studies) -- Queen's University, 2010-12-24 14:37:03.016

The Goldstrike property, located in northern Nevada within the Carlin Trend, contains one of the largest Carlin-type Au deposits in the world. The vast majority of this mineralization, formed in the Eocene, is in the form of Au-bearing, trace element-rich arsenian pyrite, either as very fine grains, overgrowths on earlier pyrite, or as reported in this study, patchy zones with high As values. Eight samples characteristic of Ore I and Ore II - ore types defined by Almeida et al. (2010) - were selected and analysed using electron microprobe, secondary ion mass spectrometry, and synchrotron !-XRF. !-XRF is a non-destructive technique for the elemental analysis of these samples with additional structural analysis capability. Although Ore I and Ore II yield similar Au values in whole rock analyses, and in the samples selected in this study, Ore II yielded much lower Au and trace element values in pyrite than Ore I. However, free gold was found in an Ore II sample, which explained their similar gold grade in whole rock. Two compositional trends were identified based on the ratio of Au and As in auriferous pyrite from both Ore I and Ore II: 1) those above an Au/As ratio of 0.007, characterized by elevated Ag, Au, As, Cu, Hg, Sb, and Tl that trend positively with respect to Au. The maximum value of Au ranges from 0.12 to 0.15at% (0.56 to 0.68wt%), occurring at an As concentration of 2.5 to 4.3at% (5 to 7.4wt%), and 2) those below an Au/As ratio of 0.007, characterized by As above the optimal range associated with lower Au and lower trace element concentrations. The peak in As corresponds well with the theoretical maximum amount of As that can be incorporated as a solid solution in pyrite (~6wt%) before the structure changes to a two-phase pyrite-arsenopyrite system. The less structurally stable solid solution has a more reactive surface that is more amenable to adsorption of other trace elements, including Au, especially with increased As. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2012-08-27 14:03:12.542

No description available.

Th. doct.--Sci.--Paris 11, 1995. N°: 3982. / Notes bibliogr. Résumé en français et en anglais.

No description available.

No description available.

No description available.