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synchrotron radiation

Sebastien F Barre, David Haberthür, Tiziana P Cremona, Marco Stampanoni, Johannes C Schittny
The pulmonary airways are subdivided into conducting and gas-exchanging airways. The small tree of gas-exchanging airways which is fed by the most distal conducting airway represents an acinus. Very little is known about the development of the number of acini. The goal of this study was to estimate their number throughout rat postnatal development. Right middle rat lung lobes were obtained at postnatal day 4-60, stained with heavy metals, paraffin embedded, and scanned by synchrotron radiation based X-ray tomographic microscopy or imaged using micro computed tomography after critical point drying...
October 19, 2016: American Journal of Physiology. Lung Cellular and Molecular Physiology
Anders Sandell, Davide Ragazzon, Andreas Schaefer, Mari Helene Farstad, Anne Borg
We present a dedicated synchrotron radiation photoelectron spectroscopy (SR-PES) study of a photochemical reaction on the surface of rutile TiO2(110). The photoreaction kinetics of carboxylate species (trimethyl acetate, TMA) upon irradiation by UV and soft x-rays were monitored and we show that it is possible to control the reaction rates from UV light and soft x-rays independently. We directly observe Ti4+ → Ti3+ conversion upon irradiation, attributed to electron trapping at Ti sites close to surface OH groups formed by deprotonation of the parent molecule, trimethyl acetic acid (TMAA)...
October 18, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Lorenzo Massimi, Michela Fratini, Inna Bukreeva, Francesco Brun, Alberto Mittone, Gaetano Campi, Raffaele Spanò, Milena Mastrogiacomo, Nicole Kerlero de Rosbo, Alberto Bravin, Antonio Uccelli, Alessia Cedola
High resolution Synchrotron-based X-ray Phase Contrast Tomography (XPCT) allows the simultaneous detection of three dimensional neuronal and vascular networks without using contrast agents or invasive casting preparation. We show and discuss the different features observed in reconstructed XPCT volumes of the ex vivo mouse spinal cord in the lumbo-sacral region, including motor neurons and blood vessels. We report the application of an intensity-based segmentation method to detect and quantitatively characterize the modification in the vascular networks in terms of reduction in experimental visibility...
October 12, 2016: Physica Medica: PM
JingJie Ge, Dong Sheng He, Wenxing Chen, Huanxin Ju, Han Zhang, Tingting Chao, Xiaoqian Wang, Rui You, Yue Lin, Yu Wang, Junfa Zhu, Hai Li, Bin Xiao, Weixin Huang, Yuen Wu, Xun Hong, Yadong Li
We report a one-pot synthesis of atomically dispersed Ru on ultrathin Pd nanoribbons. By using synchrotron radiation photoemission spectroscopy (SRPES), extended X-ray absorption fine structure (EXAFS) measurements in combination with aberration corrected high-resolution transmission electron microscopy (HRTEM), we show that atomically dispersed Ru with content up to 5.9% was on the surface of the ultrathin nanoribbon. Furthermore, the ultrathin Pd/Ru nanoribbons could remarkably prohibited the hydrogenolysis in chemoselective hydrogenation of C=C bonds, leading to an excellent catalytic selectivity compared with the commercial Pd/C and Ru/C...
October 14, 2016: Journal of the American Chemical Society
Na Li, Xiuhong Li, Yuzhu Wang, Guangfeng Liu, Ping Zhou, Hongjin Wu, Chunxia Hong, Fenggang Bian, Rongguang Zhang
The beamline BL19U2 is located in the Shanghai Synchrotron Radiation Facility (SSRF) and is its first beamline dedicated to biological material small-angle X-ray scattering (BioSAXS). The electrons come from an undulator which can provide high brilliance for the BL19U2 end stations. A double flat silicon crystal (111) monochromator is used in BL19U2, with a tunable monochromatic photon energy ranging from 7 to 15 keV. To meet the rapidly growing demands of crystallographers, biochemists and structural biologists, the BioSAXS beamline allows manual and automatic sample loading/unloading...
October 1, 2016: Journal of Applied Crystallography
Artem Y Lyubimov, Monarin Uervirojnangkoorn, Oliver B Zeldin, Qiangjun Zhou, Minglei Zhao, Aaron S Brewster, Tara Michels-Clark, James M Holton, Nicholas K Sauter, William I Weis, Axel T Brunger
X-ray free electron lasers (XFELs) reduce the effects of radiation damage on macromolecular diffraction data and thereby extend the limiting resolution. Previously, we adapted classical post-refinement techniques to XFEL diffraction data to produce accurate diffraction data sets from a limited number of diffraction images (Uervirojnangkoorn et al., 2015), and went on to use these techniques to obtain a complete data set from crystals of the synaptotagmin-1 / SNARE complex and to determine the structure at 3...
October 12, 2016: ELife
Niki Baccile, Anne-Sophie Cuvier, Sylvain Prévost, Christian V Stevens, Elisabeth Delbeke, Jan Berton, Wim Soetaert, Inge N A Van Bogaert, Sophie Roelants
A set of four structurally related glycolipids are described: two of them have one glucose unit connected to either stearic or oleic acid, and two other ones have a diglucose headgroup (sophorose) similarly connected to either stearic or oleic acid. The self-assembly properties of these compounds, poorly known, are important to know due to their use in various fields of application from cleaning to cosmetics to medical. At basic pH, they all form mainly small micellar aggregates. At acidic pH, the oleic and stearic derivatives of the monoglucose form, respectively, vesicles and bilayer, while the same derivatives of the sophorose headgroup form micelles and twisted ribbons...
October 12, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Adam Michael Scheer, Arkke J Eskola, David L Osborn, Leonid Sheps, Craig Allen Taatjes
The pulsed photolytic chlorine-initiated oxidation of diethyl ketone [DEK; (CH3CH2)2C=O], 2,2,4,4-d4-DEK [d4-DEK; (CH3CD2)2C=O] and 1,1,1,5,5,5-d6-DEK [d6-DEK; (CD3CH2)2C=O] is studied at 8 Torr and 1 - 2 atm and from 400 - 625 K. Cl atoms produced by laser photolysis react with diethyl ketone to form either primary (3-pentan-on-1-yl, RP) or secondary (3-pentan-on-2-yl, RS¬¬) radicals, which in turn react with O2. Multiplexed time of flight mass spectrometry, coupled to either a hydrogen discharge lamp or tunable synchrotron photoionizing radiation, is used to detect products as a function of mass, time and photon energy...
October 11, 2016: Journal of Physical Chemistry. A
D Egorov, L Schwob, M Lalande, R Hoekstra, T Schlathölter
Multiply protonated peptides and proteins in the gas phase can respond to near edge X-ray absorption in three different ways: (i) non dissociative ionization and ionization accompanied by loss of small neutrals, both known to dominate for proteins with masses in the 10 kDa range. (ii) Formation of immonium ions, dominating for peptides in the 1 kDa range. (iii) Backbone scission leading to sequence ions which is typically weaker and has mainly been observed for peptides in the 1 kDa range. We have studied carbon 1s photoexcitation and photoionization for a series of peptides and proteins with masses covering the range from 0...
September 21, 2016: Physical Chemistry Chemical Physics: PCCP
G Goldsztejn, T Marchenko, R Püttner, L Journel, R Guillemin, S Carniato, P Selles, O Travnikova, D Céolin, A F Lago, R Feifel, P Lablanquie, M N Piancastelli, F Penent, M Simon
Using synchrotron radiation and high-resolution electron spectroscopy, we have directly observed and identified specific photoelectrons from K^{-2}V states in neon corresponding to simultaneous 1s ionization and 1s→valence excitation. The natural lifetime broadening of the K^{-2}V states and the relative intensities of different types of shakeup channels have been determined experimentally and compared to ab initio calculations. Moreover, the high-energy Auger spectrum resulting from the decay of Ne^{2+}K^{-2} and Ne^{+}K^{-2}V states as well as from participator Auger decay from Ne^{+}K^{-1}L^{-1}V states, has been measured and assigned in detail utilizing the characteristic differences in lifetime broadenings of these core hole states...
September 23, 2016: Physical Review Letters
Viviane Lutz-Bueno, Jianguo Zhao, Raffaele Mezzenga, Thomas Pfohl, Peter Fischer, Marianne Liebi
The determination of in situ structural information of soft matter under flow is challenging, as it depends on many factors, such as temperature, concentration, confinement, channel geometry, and type of imposed flow. Here, we combine microfluidics and scanning small-angle X-ray scattering (scanning-SAXS) to create a two-dimensional spatially resolved map, which represents quantitatively the variation of molecular properties under flow. As application examples, mappings of confined amyloid fibrils and wormlike micelles under flow into various channel geometries are compared...
October 5, 2016: Lab on a Chip
Xiaofang Hu, Jian Fang, Feng Xu, Bo Dong, Yu Xiao, Luobin Wang
In this work, the underlying micro-damage mechanisms of randomly oriented short fibre-reinforced composites were revealed based on real internal microstructural characteristics obtained by high-resolution (0.7 μm/pixel) synchrotron radiation X-ray computed tomography (SR-CT). The special 'pore dominant micro-damage processes' were directly observed through SR-CT three-dimensional reconstructed images, which were different from the well-known 'fibre breakage dominant failure mode'. The mechanisms of pore formation and pore evolution were further investigated on the basis of the microstructural parameters extracted from the SR-CT results...
October 7, 2016: Scientific Reports
David Santamaría-Pérez, Chris McGuire, Adam Makhluf, Abby Kavner, Raquel Chuliá-Jordán, Julio Pellicer-Porres, Domingo Martinez-García, Andrew Doran, Martin Kunz, Plácida Rodríguez-Hernández, Alfonso Muñoz
The role of carbon dioxide, CO2, as oxidizing agent at high pressures and temperatures is evaluated by studying its chemical reactivity with three transition metals: Au, Pt, and Re. We report systematic X-ray diffraction measurements up to 48 GPa and 2400 K using synchrotron radiation and laser-heating diamond-anvil cells. No evidence of reaction was found in Au and Pt samples in this pressure-temperature range. In the Re + CO2 system, however, a strongly-driven redox reaction occurs at P > 8 GPa and T > 1500 K, and orthorhombic β-ReO2 is formed...
October 6, 2016: Inorganic Chemistry
Ivo de Sena Oliveira, Ming Bai, Henry Jahn, Vladimir Gross, Christine Martin, Jörg U Hammel, Weiwei Zhang, Georg Mayer
The anomalous occurrence of supposedly Gondwanan taxa in Laurasian-derived regions remains an intriguing chapter of paleobiogeographical history. Representatives of Peripatidae, a major subgroup of velvet worms (Onychophora), show a disjointed distribution in the neotropics, tropical Africa, and Southeast Asia, the latter being the only landmass previously associated with Laurasia [1, 2]. The arrival of these animals in Southeast Asia is explained by two alternative, albeit not mutually exclusive, hypotheses: an early migration via Europe before continental drift (Eurogondwana hypothesis) or transportation via insular India during the Cretaceous and Paleogene ("out-of-India" hypothesis) [3-6]...
October 10, 2016: Current Biology: CB
Andrii Ishchenko, Vadim Cherezov, Wei Liu
Membrane proteins (MPs) are essential components of cellular membranes and primary drug targets. Rational drug design relies on precise structural information, typically obtained by crystallography; however MPs are difficult to crystallize. Recent progress in MP structural determination has benefited greatly from the development of lipidic cubic phase (LCP) crystallization methods, which typically yield well-diffracting, but often small crystals that suffer from radiation damage during traditional crystallographic data collection at synchrotron sources...
2016: Journal of Visualized Experiments: JoVE
Shaocheng Ma, Oliver Boughton, Angelo Karunaratne, Andi Jin, Justin Cobb, Ulrich Hansen, Richard Abel
Bone is a complex hierarchical structure, and its principal function is to resist mechanical forces and fracture. Bone strength depends not only on the quantity of bone tissue but also on the shape and hierarchical structure. The hierarchical levels are interrelated, especially the micro-architecture, collagen and mineral components; hence, analysis of their specific roles in bone strength and stiffness is difficult. Synchrotron imaging technologies including micro-CT and small/wide angle X-ray scattering/diffraction are becoming increasingly popular for studying bone because the images can resolve deformations in the micro-architecture and collagen-mineral matrix under in situ mechanical loading...
2016: Clinical Reviews in Bone and Mineral Metabolism
Yong Cao, Yuan Zhou, Shuangfei Ni, Tianding Wu, Ping Li, Shenghui Liao, Hong-Bin Lu, Jianzhong Hu
A full understanding of the mechanisms behind spinal cord injury (SCI) processes requires reliable 3D imaging tools for a thorough analysis of changes in angio-spatial architecture. We aimed to employ synchrotron radiation μCT (SRμCT) to characterize 3D temperal-spatial changes in microvasculature post-SCI. Morphometric measurements revealed a significant decrease in vascular volume fraction (VVF), vascular bifurcation density (VBD), vascular segment density (VSD) and vascular connectivity density (VCD) 1 day post-injury, followed by a gradual increase at 3, 7, and 14 days...
September 27, 2016: Journal of Neurotrauma
A Bouchet, M T Potez, M Flaender, L Schaad, C Rome, R Farion, J A Laissue, M Grotzer, V Djonov, H Elleaume, E Brun, R Serduc
No abstract text is available yet for this article.
October 1, 2016: International Journal of Radiation Oncology, Biology, Physics
J Livingstone, J F Adam, A W Stevenson, D Hausermann
No abstract text is available yet for this article.
October 1, 2016: International Journal of Radiation Oncology, Biology, Physics
J F Adam, J Balosso, M Renier, H Elleaume, F Estève, P Berkvens, C Nemoz, T Brochard, A Tessier, C Verry, J F Le Bas
No abstract text is available yet for this article.
October 1, 2016: International Journal of Radiation Oncology, Biology, Physics
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