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    ABSTRACT: Poly- and single-crystal thin films of U-Mo alloys have been grown both on glass and sapphire substrates by UHV magnetron sputtering. X-ray and Electron Backscatter Diffraction data indicate that for single-crystal U1-xMox alloys, the pure cubic uranium gamma-phase exists for x > 0.22 (10 wt.% Mo). Below 10 wt.% Mo concentration, the resulting thin film alloys exhibited a mixed alpha-gamma uranium phase composition.
    Thin Solid Films. 11/2013; 550.
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    ABSTRACT: Transmission and scanning electron microscopy are used to examine the sulphidation of hydrother- mally grown [0001]-oriented ZnO nanorods in aqueous thioacetamide (CH3C(S)NH2) solution. At the early stages of growth, the reaction occurs preferentially on the (0001) top surface,confirmed to be Zn- polar by convergent beam electron diffraction, and on the lines of intersection of the {1010} facets. It is shown that the reaction involves surface migration of Zn species towards ZnS deposits.The presence of voids at the ZnS/ZnO interface also confirms a Kirkendall mechanism where ZnS grows from the top surface of the deposit.
    Journal of Solid State Chemistry 01/2013; 199(2013):109-115.
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    ABSTRACT: In nonrelativistic quantum mechanics, measurements performed by separate observers are modeled via tensor products. In algebraic quantum field theory, though, local observables corresponding to spacelike separated parties are just required to commute. The problem of determining whether these two definitions of separation lead to the same set of bipartite correlations is known in nonlocality as Tsirelson's problem. In this article, we prove that the analog of Tsirelson's problem in steering scenarios is false. That is, there exists a steering inequality that can or cannot be violated depending on how we define spacelike separation at the operator level.
    Physical Review Letters 10/2012; 109(16):160405.
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    ABSTRACT: Abstract I summarize the early developments of the more quantitative aspects of exoplanet detection. After a brief overview of the observational methods currently applied to exoplanet searches and a summary of the first true exoplanet detections resulting from these various techniques, the more relevant historical background is organized according to the observational techniques that are currently most relevant. Key Words: Exoplanets-History of astronomy. Astrobiology 12, 928-939.
    Astrobiology 09/2012; 12(10):928-39.
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    ABSTRACT: We construct a sample of 3516 radio-loud host galaxies of active galactic nuclei (AGN) from the optical Sloan Digital Sky Survey and Faint Images of the Radio Sky at Twenty cm. These have 1.4-GHz luminosities in the range 1023–1025 W Hz−1, span redshifts 0.02 < z < 0.18, are brighter than r*petro < 17.77 mag and are constrained to ‘early-type’ morphology in colour space (u*−r* > 2.22 mag). Optical emission line ratios (at >3σ) are used to remove type 1 AGN and star-forming galaxies from the radio sample using Baldwin–Phillips–Terlevich diagnostics. For comparison, we select a sample of 35 160 radio-quiet galaxies with the same r*-band magnitude–redshift distribution as the radio sample. We also create comparison radio and control samples derived by adding the NRAO VLA Sky Survey (NVSS) to quantify the effect of completeness on our results.We investigate the effective radii of the surface brightness profiles in the SDSS r and u bands in order to quantify any excess of blue colour in the inner region of radio galaxies. We define a ratio R=re(r)/re(u) and use maximum likelihood analysis to compare the average value of R and its intrinsic dispersion between both samples. R is larger for the radio-loud AGN sample as compared to its control counterpart, and we conclude that the two samples are not drawn from the same population at >99 per cent significance. Given that star formation proceeds over a longer time than radio activity, the difference suggests that a subset of galaxies has the predisposition to become radio loud. We discuss host galaxy features that cause the presence of a radio-loud AGN to increase the scale size of a galaxy in red relative to blue light, including excess central blue emission, point-like blue emission from the AGN itself and/or diffuse red emission. We favour an explanation that arises from the stellar rather than the AGN light.
    Monthly Notices of the Royal Astronomical Society 08/2011; 416(4):2869 - 2881.
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    ABSTRACT: The Cliff-Lorimer ratio technique for thin foils was used to determine a set of k factors at 120 kV for calibration of the energy dispersive X-ray analyser on a Philips EM400 analytical electron microscope. The standards used were the crystallized forms of microdroplets of solutions of inorganic salts. These experimental data were compared with other experimental work and found to agree within the experimental error with theoretical k factors.
    Journal of Microscopy 08/2011; 133(3):275 - 280.
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    ABSTRACT: The established electron backscatter diffraction (EBSD) technique for obtaining crystallographic information in the SEM has been adapted to permit elastic strain measurement. Basically, the displacement of crystallographic features in an EBSD pattern, such as zone axes, which result from strain in a crystal, is determined by comparing those same features as they appear in a pattern from an unstrained region of the crystal. The comparison is made by cross-correlation of selected regions in the two patterns. Tests show that the sensitivity to displacement measurement is 1 part in 10 000, which translates to a strain sensitivity of 2 parts in 10 000. Eight components of the strain tensor are determined directly and the ninth is calculated using the fact that the free surface of the sample is traction-free. Examples discussed are taken from studies of a lenticular fracture in germanium, the strain distribution surrounding a carbide precipitate in a nickel base alloy and grain boundary studies in another nickel base alloy.
    Journal of electron microscopy 08/2010; 59 Suppl 1:S155-63.
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    ABSTRACT: Highly symmetrical protein cage architectures from three different iron storage proteins, heavy and light human ferritin chains (HuHFt and HuLFt) and ferritin from the hyperthemophilic bacterium Pyrococcus furiosus (PfFt), have been used as models for understanding the molecular basis of silver ion deposition and metal core formation inside the protein cavity. Biomineralization using protein cavities is an important issue for the fabrication of biometamaterials under mild synthetic conditions. Silver nanoparticles (AgNPs) were produced with high yields within PfFt but not within HuHFt and HuLFt. To explain the molecular basis of silver incorporation, the X-ray crystal structure of Ag-containing PfFt has been solved. This is the first structure of a silver containing ferritin reported to date, and it revealed the presence of specific binding and nucleation sites of Ag(I) that are not conserved in other ferritin templates. The AgNP encapsulated by PfFt were further characterized by the combined use of different physical-chemical techniques. These showed that the AgNPs are endowed with a narrow size distribution (2.1 +/- 0.4 nm), high stability in water solution at millimolar concentration, and high thermal stability. These properties make the AgNP obtained within PftFt exploitable for a range of applications, in fields as diverse as catalysis in water, preparation of metamaterials, and in vivo diagnosis and antibacterial or tumor therapy.
    Journal of the American Chemical Society 02/2010; 132(10):3621-7.
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    ABSTRACT: In some galaxies, matter falling onto a supermassive black hole is ejected in narrow jets moving at close to the speed of light. New observations provide insight into the workings of these cosmic accelerators.
    Nature 02/2010; 463(7283):886-7.
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    Chemical Reviews 02/2010; 110(4):2313-65.
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