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We report results of the computed tomography reconstruction of the index of refraction in a whole rabbit knee joint examined at the photon energy of 51 keV. Refraction based images make it possible to delineate the bone, cartilage, and soft tissues without adjusting the contrast window width and level. Density variations, which are related to tissue composition and are not visible in absorption X-ray images, are detected in the obtained refraction based images. We discuss why refraction-based images provide better detectability of low contrast features than absorption images. [ABSTRACT FROM AUTHOR]

In situ X-ray radiography and spatio-temporal image analysis yield quantitative information about coalescence during metal foam formation and decay. The choice of weighting every detected coalescence event by its projected area yields reliable information about the impact of coalescence on structural coarsening. The comparison of two particle-stabilized metal foams containing ceramic particles of different sizes demonstrates that the stabilization effect is provided by solid particles which are small in comparison to the average film thickness of the foamed liquid melt. [Copyright &y& Elsevier]

Graphical abstract Highlights • Poly-3-hydroxybutyrate (PHB) films were plasma-treated in NH 3 , Ar and NH 3 /Ar mixtures. • Surface chemistry and topography changes were observed in PHB films. • A significant decrease in contact angle and an increase in free surface energy were observed. • Fibroblast cell adhesion was significantly improved after Ar plasma treatment. Abstract Poly-3-hydroxybutyrate (PHB) films were plasma-treated using pure NH 3 , pure Ar or mixtures of the two different proportions (20%, 30%, 40%, 50%, 70% NH 3 in Ar). Surface chemistry and surface topography changes of PHB films were observed after plasma processing in all plasma regimes. The XPS results confirmed the absence of chemical modification in the case of pure Ar plasma treatment. Nitrogen-containing groups (e.g., N C O) were detected on the surfaces of P3HB films treated with NH 3 -containing plasma. The surfaces of the untreated P3HB films were hydrophobic, and plasma treatment turned the surfaces hydrophilic, irrespective of the treatment. A significant decrease in the contact angle and an increase in the free surface energy were observed. An insignificant surface ageing effect was observed when P3HB samples were exposed to air for 10 days. In NIH 3T3 mice fibroblast cells, cell adhesion was significantly improved after plasma treatment in an Ar atmosphere, which is likely related to the fact that there was a surface ξ potential of 88.6 mV at neutral pH, causing a cleavage of the polymer chains and an increase in surface roughness. [ABSTRACT FROM AUTHOR]

VN coatings were deposited by reactive sputtering at different deposition angles χ . The thin film growth was monitored by angle-dispersive in situ X-ray reflectivity measurements. These measurements were realized using a monochromatic X-ray beam and exploiting its angular divergence. Already during deposition of the first few nm, the measurements revealed the formation of a porous coating with stable growth rate. The growth rate decreased with increasing tilt angle. The reduction was less than expected from the flux projection onto the sample surface. This can only partially be explained by the porosity increase with increasing tilt angle. SIMTRA simulations confirmed that the deposition rate is strongly influenced by the interplay between deposition geo-metry and particle transport. [ABSTRACT FROM AUTHOR]

Europium silicide nanoislands and films with Eu coverage in the range 0.3 ML–303 ML were grown on the vicinal Si(001) surface with 4° miscut towards [110] by molecular beam epitaxy. The nanostructures were characterized by atomic force microscopy, reflection high energy electron diffraction, in situ synchrotron radiation X-ray absorption near edge structure spectroscopy and ex situ X-ray diffraction. The analysis revealed the formation of EuSi 2 with a tetragonal structure. By increasing the Eu coverage the surface morphology gradually changes from isolated islands through films with very rough surface to thick films with smoother surface. [ABSTRACT FROM AUTHOR]

In order to achieve large area semipolar GaN layers with high crystal quality, we have etched trenches into n-plane and r-plane sapphire wafers exposing c-plane-like side-walls, from which GaN stripes can be grown by metalorganic vapor phase epitaxy mainly in c -direction, forming semipolar { 10 1 ¯ 1 } or { 11 2 ¯ 2 } surfaces after coalescence. Here, we describe how to improve such layers by optimizing the side-facet orientation and by including a SiN nanomask interlayer in situ into the growth process, eventually resulting in a basal plane stacking fault density below 5 × 10 3 cm − 1 . Moreover, doping experiments have revealed a substantially lower Mg incorporation efficiency on the { 11 2 ¯ 2 } surface as compared to the c-plane, whereas Si does not show such differences. [ABSTRACT FROM AUTHOR]

We present epitaxial growth of europium (Eu) on the oxygen-induced c(6×2) reconstructed (110)Nb (niobium) surface at 150°C and at 260°C for various Eu coverages. The samples are characterized by reflection high-energy electron diffraction, atomic force microscopy and low-temperature in-situ nuclear resonance scattering. At a substrate temperature of 260°C Eu forms islands with the face-centered cubic (fcc) crystal structure that is an exotic crystallographic phase for metallic europium. The deposition at 150°C results to the already reported formation of a smooth film with hexagonal symmetry. The up to now unknown initially formed intermediate phase in this growth mode is identified as EuO-type stacking of [111]Eu layers that quickly relaxes towards that of an [0001]Eu film. The analysis of the nuclear resonance scattering data unambiguously demonstrates the formation of EuO interface at 260°C that facilitates the stabilization of the strained fcc Eu lattice. No traces of EuO are found in the sample grown at 150°C. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a group of Lu2SiO5:Tb (LSO:Tb) scintillating layers with a Tb concentration between 8% and 19% were investigated by means of synchrotron and laboratory techniques. The scintillation efficiency measurements proved that the highest light yield is obtained for a Tb concentration equal to 15%. At higher concentration, quenching processes occur which lower the light emission. The analysis of the reciprocal space maps of the (082) (280) and (040) Bragg reflections showed that LSO:Tb epilayers are well adapted on YbSO substrates for all the investigated concentrations. The spatial resolution tests demonstrated the possibility to achieve a resolution of 1 μm with a 6 μm thick scintillating layer. [Copyright &y& Elsevier]

Abstract: In this work, we present preliminary in-line X-ray lensless projection imaging results at a synchrotron facility by using novel solid-state detectors based on non-destructive readout of photoluminescent colour centres in lithium fluoride thin films. The peculiarities of LiF radiation detectors are high spatial resolution on a large field of view, wide dynamic range, versatility and simplicity of use. These properties offered the opportunity to test a broadband X-ray synchrotron source for lensless projection imaging experiments at the TopoTomo beamline of the ANKA synchrotron facility by using a white beam spectrum (3–40 keV). Edge-enhancement effects were observed for the first time on a test object; they are discussed and compared with simulations, on the basis of the colour centre photoluminescence linear response found in the investigated irradiation conditions. [Copyright &y& Elsevier]

Abstract: Novel X-ray imaging detectors based on photoluminescence of colour centres in lithium fluoride (LiF) have been proposed and tested for extreme ultraviolet, soft and hard X-rays up to 10keV. For the first time we present the optical characterisation of LiF crystals and thin films irradiated at the TOPO–TOMO beamline of synchroton light source Anka (Karlsruhe, Germany) in the energy range 6–40keV for different exposure times. Absorption and photoluminescence spectra were analysed to study the optical response of the LiF-based detectors. High resolved X-ray imaging of commercial test patterns has been obtained on LiF crystals and films by optical readout with a confocal laser scanning fluorescence microscope. [Copyright &y& Elsevier]

Abstract: High resolution X-ray coplanar (symmetric X-ray diffraction (SXRD) and asymmetric X-ray diffraction (ASXRD)) and non-coplanar diffraction (grazing incidence diffraction (GID)) have been used to investigate the quality of AlGaN epilayers with 20% Al content, grown on sapphire using SiN x interlayers. The measurement of reciprocal space maps (RSM) with higher orders of reflections of SXRD and ASXRD which is readily performed at the synchrotron with high resolution and intensity reveals the presence of several diffraction peaks originating from the occurrence of local differences in the lattice constants. Two distinguishable AlGaN phases having different crystalline parameters were clearly recognized from X-ray data and the corresponding densities of screw dislocations have been determined measured as function of the overgrowth thickness varying from 0.5μm to 3.5μm. The variation of the screw and edge type dislocation densities with the overgrowth thickness has been found to follow the scaling law h −n where h is the thickness of the buffer layer. [Copyright &y& Elsevier]

Abstract: Semi-solid melts exhibit a very unpredictable rheology and filling dynamics, when injected into thin-walled components. Optimization of the process requires an insight into the casting process during injection. For this purpose we injected semi-solid an Al–Ge alloy into two different thin channel geometries while recording high resolution radiographs at fast frame rates (up to 1000 images per s). Comparison of a bottleneck channel, which has previously been used for slower experiments, with a right-angle turn geometry reveals a significant influence of the channel shape on the flow behaviour of the particle–liquid mixture. While the bottleneck is quickly sealed with densified solid, turbulences in the right-angle turn apparently permit solid particles and clusters to move conjointly with the liquid and thus achieve a more complete filling. Single particle trajectories and rapid break-up of solid skeletons in such a system have been observed for the first time in situ. [Copyright &y& Elsevier]

Abstract: Tomographic imaging using both laboratory sources and synchrotron radiation (SR) was performed to achieve a multi-scale damage assessment of carbon fibre composites subjected to impact damage, allowing various internal damage modes to be studied in three-dimensions. The focus of this study is the comparison of different tomographic methods, identifying their capabilities and limitations, and their use in a complementary manner for creating an overall 3D damage assessment at both macroscopic and microscopic levels. Overall, microfocus laboratory computed tomography (μCT) offers efficient routine assessment of damage at mesoscopic and macroscopic levels in engineering-scale test coupons and relatively high spatial resolutions on trimmed-down samples; whilst synchrotron radiation computed tomography (SRCT) and computed laminography (SRCL) offer scans with the highest image quality, particularly given the short acquisition times, allowing damage micromechanisms to be studied in detail. [Copyright &y& Elsevier]

Abstract: Titanium beryllide Be12Ti and vanadium beryllide Be12V are considered to be promising materials for advanced neutron multipliers in the helium-cooled breeding blanket of DEMO reactor. A study of the surface layers of oxidized beryllide specimens by means of powder X-ray diffraction technique is presented in this work. The phase composition of the near-to-surface layers of Be12Ti and Be12V specimens was investigated at the Single Crystal Diffraction (SCD) beamline at ANKA synchrotron facility after air-annealing at 800°C. A high surface sensitivity of measurements was achieved at grazing incidence conditions by varying the incidence angle. Since beryllium has low values of X-ray absorption, the near-surface regions having depths from 2 up to 20μm were investigated. The main objective of the work is the evaluation of composition of the reactant products which can influence the parameters of retention and release of radiogenic gases. [Copyright &y& Elsevier]

Abstract: During the last years the electron beams produced by Laser-Plasma Accelerators were used for the first time to generate synchrotron radiation in an undulator. Both the emittance and especially the energy spread of a laser plasma accelerator beam are significantly larger than the emittance and the energy spread of beams from conventional accelerators. Beams with a high energy spread produce in a conventional undulator photon beams with a high wavelength spread. In this paper a novel modified undulator design is presented which can reduce the energy spread of the photon beam caused by the energy spread of the electron beam. The magnetic concept is analysed in detail by tracking test electrons through the device. An experiment to test this concept is in preparation. [Copyright &y& Elsevier]

Characterization of the microstructure of thermal barrier coatings (TBCs) is essential for assessing coating lifetime and for understanding the damage mechanisms leading to ceramic layer spallation. Recent progress in synchrotron-radiation computed laminography (SRCL) enables imaging of samples that are thin but extended in two dimensions. This study reports on the first results of the 3-D characterization of electron beam–physical vapour deposition TBCs by SRCL. Image analysis was very helpful in investigating the 3-D microstructure obtained and is also described. [ABSTRACT FROM AUTHOR]

Ductile crack initiation and propagation within a naturally aged aluminium alloy sheet has been observed in situ via synchrotron radiation-computed laminography, a technique specifically adapted to three-dimensional imaging of thin objects that are laterally extended. Voids and intermetallic particles, and their subsequent evolution during ductile crack extension at different associated levels of stress triaxiality, were clearly observed within fracture coupons of a reasonable engineering length-scale, overcoming the conventional sample size limitation of computed tomography at high resolutions. [Copyright &y& Elsevier]

Abstract: The generation and propagation of dislocations in Si at high temperature is observed in situ with white beam X-ray topography. For the heating experiments a double ellipsoidal mirror furnace was installed at the Topo–Tomo beamline of the ANKA synchrotron light source, Research Centre Karlsruhe, Germany. Details of the experimental set-up and the first results on the occurrence of dislocations are presented. Artificial damage was generated in commercial (100) Si wafers using a nanoindenter with various loads. The applied forces for each set of indents were varied from 100 to 500mN, respectively. After heating to approx. 790°C large area transmission topographs were taken every 30min which were then compared to room temperature topographs before and after heating. At the outset straight 60°-dislocations with b = a/2〈110〉 originate from the 500mN indents into the direction of the strongest temperature gradient. After 60min at constant temperature an increase in the length and number of the dislocations in other directions is also observed. As a result of the continual thermal stressing dislocations develop from the 100mN indents too. [Copyright &y& Elsevier]

X-ray computed laminography (CL) with synchrotron radiation is used to investigate fracture in carbon fibre–epoxy laminates. CL allows for high-resolution (∼1μm) imaging of laterally extended objects. Whilst artefacts inherent to CL data reduce image quality compared with computed tomography (CT), imaging regions of interest in large planar samples greatly increases the engineering applicability. High-resolution in situ three-dimensional analysis of structural failure is therefore achievable at levels that would be impossible via CT or any other volume-imaging methods. [Copyright &y& Elsevier]

Abstract: X-ray topography is a well known imaging technique to characterise strain and extended defects in single crystals. Topographs are typically collected on X-ray films. On the one hand such photographic films show a limited dynamic range and the production of films will be discontinued step by step in the near future. On the other hand new imaging detectors improved for X-ray tomography become more and more attractive even for topography because of increasing resolution, dynamic range, speed and active area. In this paper we report about the upgrade of the TOPO–TOMO beamline at the synchrotron light source ANKA, Research Centre Karlsruhe, with a high resolution digital camera for the topography use. [Copyright &y& Elsevier]