X-ray high-resolution diffraction using refractive lenses

Refractive x-ray lenses have recently been applied for imaging and scanning microscopy with hard x rays. We report the application of refractive lenses in an optical scheme for high-resolution x-ray diffraction, performed at a high brilliance synchrotron radiation source. An experimental proof of principle and a theoretical discussion are presented. In particular, we observe the x-ray diffraction pattern from a two-dimensional photonic crystal with 4.2 µm periodicity, which normally is employed to scatter light in the infrared

Viewing the Extracellular Matrix: An imaging method for tissue engineering

The field of regenerative medicine seeks to create replacement tissues and organs, both to repair deficiencies in biological function and to treat structural damage caused by injury. Scaffoldings mimicking extracellular matrix (ECM), the structure to which cells attach to form tissues, have been developed from synthetic polymers and also been prepared by decellularizing adult tissue. However, the structure of ECM undergoes significant remodeling during natural tissue repair, suggesting that ECM-replacement constructs that mirror developing tissues may promote better regeneration than those modeled on adult tissues. This work investigated the effectiveness of a method of viewing the extracellular matrix of developing embryos. Embryos were perfused with acrylamide, polymerized, and decellularized with sodium dodecyl sulfate (SDS) in phosphate-buffered saline (PBS). Cell nuclei were stained with a fluorescent DNA-binding compound to verify decellularization. Whole-mount embryos were stained and used to verify that the overall structure of the ECM was not altered. Antibody staining was combined with fluorescent confocal microscopy to determine the presence of fibrillin-2 (FBN2), fibronectin (FN), tenascin-C (TNC), and collagen-VI (COL6). This study demonstrated that while the results of SDS decellularization depend on SDS concentration, embryonic stage, the protein under consideration, and the region of the embryo examined, FBN2 and FN tended to maintain their natural structure and to become more visible with treatment, while TNC and COL6 tended to be disrupted and removed. Future efforts to develop tissue-replacement constructs may benefit by using this method to examine, quantify, and mimic the structure and composition of specific proteins of developing ECM

Residual stress distribution in a Ti-6Al-4V T-joint weld measured using synchrotron X-ray diffraction

To improve the manufacturing quality of welded structures, to prevent failures at weld joints and to predict their lifetime, measurements of the residual stresses generated by welding in the structures are extremely useful. The residual stresses may reduce the component life due to phenomena that occur at low applied stresses such as brittle fracture, fatigue and stress corrosion cracking. Welded thin Ti-6Al-4V panel components are commonly found in aero-engine assemblies and the weld integrity and reliability are critical. In this work, the residual stress distributions in a welded thin Ti-6Al-4V T-joint were measured by the newly developed SScanSS program with synchrotron X-ray diffraction technique. The measurement performed in this study, which included a large number of measurement points, has mapped a complete stress field in a thin sheet T-joint weld. It has not only provided improved understanding of residual stress in such a joint but also filled the missing link between the residual stress obtained by numerical modelling and their validation. The results have shown that the longitudinal stresses play the most important role in the residual stress distribution over the flange and high tensile stresses appear in the region near the weld zone. The measured results were compared with numerically predicted results and these showed good agreement

Los arenales costeros del litoral catalán (la bahía de Rosas)

[ES] Se distinguen dos fuentes para los minerales pesados que se encuentran en las playas de la bahía de Rosas: los basaltos de Olot, para la augita, olivino e hiperstena y las rocas metamórficas del macizo de los Alberes y Cabo de Creus de donde proceden la andalucita, silimanita y distena. La distribución de los minerales, se explica por el transporte efectuado por las corrientes de deriva, los temporales y el viento. Las anomaiías en la distribucidn de algunas especies se deben a los accicentes del terreno y a las condiciones dinámicas muy activas de la bahía, que afectan a la seleccidn de minerales.[EN] The heavy minerals of Gulf of Rosas coastal sand have two different sources. The more frequent heavy minerals are augite and olivine which come from Olot basalts. The metamorfic association is presented by andalusite, siliimanite and kyanite and they come from the metamorfic rocks of the Pyrenees and Cap of Creus massif. Homblende can have two origins: the metamorfic and the granitic rocks of river Muga basin.Peer reviewe