Mössbauer studies of trimethyl and triphenyl tin chloride adsorbed on grafoil

Trimethyl tin chloride [(CH3)3SnCl] and triphenyl tin chloride [(C6H5)3SnCl] adsorbed on grafoil were studied by the Mössbauer resonance in 119Sn. The temperature dependence of the Mössbauer fraction and the anisotropy ratio of the quadrupole transitions in (CH3)3SnCl measured at two different angles supplied information on the structure of the substrate and on the anisotropy of the recoilless fraction. The relative orientation of (C6H5)3SnCl adsorbed on grafoil was found to be with the Sn–Cl axis perpendicular to the exposed basal planes of grafoil, contrary to (CH3)3SnCl, where the molecules have their symmetry axes parallel to the grafoil plane

Transcatter X-Ray Technique for the Inspection of Insulated, Oil-Carrying Pipelines

Pipelines are subjected to corrosion and require periodic inspection. These pipes are generally covered with an insulating material, that is contained within a metal jacket. The removal of the insulating material is costly, and can hazardous if asbestos is the material being removed. Because a large number of pipes need to be inspected, a cost effective technique for the characterization of corrosion under insulation is desirable

Excess Circulating Alternatively Activated Myeloid (M2) Cells Accelerate ALS Progression While Inhibiting Experimental Autoimmune Encephalomyelitis

Circulating immune cells including autoreactive T cells and monocytes have been documented as key players in maintaining, protecting and repairing the central nervous system (CNS) in health and disease. Here, we hypothesized that neurodegenerative diseases might be associated, similarly to tumors, with increased levels of circulating peripheral myeloid derived suppressor cells (MDSCs), representing a subset of suppressor cells that often expand under pathological conditions and inhibit possible recruitment of helper T cells needed for fighting off the disease.We tested this working hypothesis in amyotrophic lateral sclerosis (ALS) and its mouse model, which are characterized by a rapid progression once clinical symptoms are evident. Adaptive transfer of alternatively activated myeloid (M2) cells, which homed to the spleen and exhibited immune suppressive activity in G93A mutant superoxide dismutase-1 (mSOD1) mice at a stage before emergence of disease symptoms, resulted in earlier appearance of disease symptoms and shorter life expectancy. The same protocol mitigated the inflammation-induced disease model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), which requires circulating T cells for disease induction. Analysis of whole peripheral blood samples obtained from 28 patients suffering from sporadic ALS (sALS), revealed a two-fold increase in the percentage of circulating MDSCs (LIN(-/Low)HLA-DR(-)CD33(+)) compared to controls.Taken together, these results emphasize the distinct requirements for fighting the inflammatory neurodegenerative disease, multiple sclerosis, and the neurodegenerative disease, ALS, though both share a local inflammatory component. Moreover, the increased levels of circulating MDSCs in ALS patients indicates the operation of systemic mechanisms that might lead to an impairment of T cell reactivity needed to overcome the disease conditions within the CNS. This high level of suppressive immune cells might represent a risk factor and a novel target for therapeutic intervention in ALS at least at the early stage

One Sided Radiographic Inspection Using Backscatter Imaging

Radiographic inspection, where access is limited to one side of the part, can be performed by the use of backscatter imaging techniques. Compton scattering is the primary source of the backscattered signal strength with some contribution from x-ray fluorescence. A variety of approaches have been used in both medicine and industry to create the images [1–25]. The flying spot technique which uses a collimated beam of x-rays, and a large area detector has been used in the work reported here. The backscatter imaging is particular useful in the inspection of low-density, composite materials.</p

SUPERCONDUCTIVITY AND LATTICE DYNAMICS OF GRANULAR TIN

La température de transition supraconductrice a été mesurée dans des échantillons de grains d'étain de 45 Å contenus dans une matrice d'oxyde d'étain. La température de Debye des mêmes échantillons a été mesurée par effet Mössbauer de 119Sn afin de déterminer un possible changement du spectre de phonons. On a trouvé que Tc augmente de 10 % tandis que θ diminue de 4 % par rapport à un échantillon massif. Les deux tendances sont quantitativement en accord avec la théorie de McMillan de supraconducteurs à couplage fort. La microstructure et la composition chimique des échantillons ont été étudiées soigneusement par microscopie électronique et par la mesure des interactions hyperfines par spectroscopie Mössbauer. On en déduit plusieurs conclusions quant à la nature des grains et leur interaction avec la couche diélectrique.The superconducting transition temperature was measured in samples of 45 Å Sn grains embedded in a tin-oxide matrix. The Debye temperature of the same samples was measured by the Mössbauer effect in 119Sn in order to detect possible changes in the phonon spectrum. It was found that Tc is enhanced by 10 % and θ is decreased by 4 % relative to the bulk. Both trends are found to fit quantitatively with McMillan's theory of strong-coupling superconductors. The microstructure and the chemical composition of the samples were thoroughly studied by electron-microscopy and the Mössbauer hyperfine interaction. Several conclusions were derived on the nature of the grains and their interaction with the dielectric coating