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synchrotron radiation

Mai Elfarnawany, Seyed Alireza Rohani, Soroush Ghomashchi, Daniel G Allen, Ning Zhu, Sumit K Agrawal, Hanif M Ladak
High resolution images are used as a basis for finite-element modeling of the middle-ear structures to study their biomechanical function. Commonly used imaging techniques such as micro-computed tomography (CT) and optical microscopy require extensive sample preparation, processing or staining using contrast agents to achieve sufficient soft-tissue contrast. We compare imaging of middle-ear structures in unstained, non-decalcified human temporal bones using conventional absorption-contrast micro-CT and using synchrotron radiation phase-contrast imaging (SR-PCI)...
August 5, 2017: Hearing Research
Lucas Schwob, Mathieu Lalande, Dmitrii Egorov, Jimmy Rangama, Ronnie Hoekstra, Violaine Vizcaino, Thomas Schlathölter, Jean-Christophe Poully
We report on an experimental single-photon absorption study on gas-phase protonated collagen peptides employing a combination of mass spectrometry and synchrotron radiation. Partial ion yields for the main photoabsorption products vary steadily with photon energy over the range from 14 to 545 eV. At low energy, non-dissociative photoionisation competes with neutral molecule loss from the precursor ion, whereas fragmentation of the peptide backbone dominates at soft X-ray energies. Neutral molecule losses from the ionised peptide are found to have low energy barriers and most likely involve amino-acid residue side-chains with radical character, in particular aspartic acid...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
Alfredo Quinto-Hernandez, Shih-Huang Lee, Alec M Wodtke
Synchrotron radiation VUV-photoionization based photofragment translational spectroscopy was used to identify the primary and secondary photodissociation reactions of methyl azide (CH3N3) at 157 nm under collision-free conditions. Two primary dissociation channels are identified, leading to CH3 + N3 (the radical channel) and CH3N + N2 (the molecular elimination channel). The last channel is the major dissociation pathway, but unlike work at longer photolysis wavelengths, here, the radical channel exclusively produces the higher energy isomer cyclic-N3...
August 14, 2017: Journal of Chemical Physics
H Beigzadeh Jalali, E Salimi, J Rahighi
Gas bremsstrahlung is generated in high energy electron storage ring and accompanies the synchrotron radiation into the beamlines, where both strike the various components of the beamline. In this paper, radiation shielding calculations for secondary gas bremsstrahlung are performed for the First Optics Enclosure (FOE) of X-ray powder diffraction (XPD) beamline of the Iranian Light Source Facility. Dose equivalent rate (DER) calculations are accomplished using FLUKA Monte Carlo code. A comprehensive study of DER distribution at the back wall, sides and roof are given...
August 8, 2017: Applied Radiation and Isotopes
Quentin Arnoux, Anthony Boucly, Vincent Barth, Rabah Benbalagh, Albano Cossaro, Luca Floreano, Mathieu G Silly, Fausto Sirotti, Etienne Derat, Stephane Carniato, Fabrice Bournel, Jean-Jacques Gallet, Denis Fichou, Ludovic Tortech, Francois Rochet
2,2',6,6'-tetraphenyl-4,4'-dipyranylidene (DIPO-Ph4) was grown by vacuum-deposition on an indium tin oxide (ITO) substrate. The films were characterized by atomic force microscopy and synchrotron radiation UV and X-ray photoelectron spectroscopy to gain an insight into the material growth and to better understand the electronic properties of the DIPO-Ph4/ITO interface. Results show formation of cationic DIPO-Ph4 at ITO interface with a charge transfer from the organic layer to the anode material. This has been confronted to DFT calculations...
August 14, 2017: ACS Applied Materials & Interfaces
Sanghun Jang, Jaehong Lim, Onseok Lee
Radiation beam interface contrast X-ray microscopy provides resolution of a few dozen nanometers from fixed whole muscle biopsies, allowing better reconstruction of the microstructure of the muscle than is currently possible with classic histological techniques. Fixed soleus muscle biopsies have been evaluated from the walk-in mouse model using phase-contrast X-ray microscopy, and results presented that corroborate the accuracy of the method used, and its potential for application in physiotherapy and occupational therapy studies...
August 12, 2017: Microscopy Research and Technique
Dieter M Herlach, Thomas Palberg, Ina Klassen, Stefan Klein, Raphael Kobold
Crystallization is one of the most important phase transformations of first order. In the case of metals and alloys, the liquid phase is the parent phase of materials production. The conditions of the crystallization process control the as-solidified material in its chemical and physical properties. Nucleation initiates the crystallization of a liquid. It selects the crystallographic phase, stable or meta-stable. Its detailed knowledge is therefore mandatory for the design of materials. We present techniques of containerless processing for nucleation studies of metals and alloys...
December 7, 2016: Journal of Chemical Physics
Bérenger Gans, Séverine Boyé-Péronne, Gustavo A Garcia, Anja Röder, Domenik Schleier, Philippe Halvick, Jean-Christophe Loison
The cyano radical is an ubiquitous molecule, and was for instance one of the first species detected in astrophysical media such as comets or diffuse clouds. In photodis- sociation regions the reaction rate of CN(+) + CO → CN + CO(+) is one of the critical parameters defining nitrile chemistry. The enthalpy of this charge transfer reaction is defined as the difference of ionization energies (EI) between CN and CO. Although EI(CO) is known accurately, the EI(CN) values are more dispersed and deduced indirectly from thermodynamic thresholds only, all above EI(CO), leading to the assumption that the reaction was fast even at low temperature...
August 10, 2017: Journal of Physical Chemistry Letters
Jennifer P Ngo, Bianca Le, Zohaib Khan, Michelle M Kett, Bruce S Gardiner, David W Smith, Mayer M Melhem, Anton Maksimenko, James T Pearson, Roger G Evans
We assessed the utility of synchrotron-radiation micro-computed tomography (micro-CT) for quantification of the radial geometry of the renal cortical vasculature. The kidneys of nine rats and six rabbits were perfusion fixed and the renal circulation filled with Microfil(®) . In order to assess shrinkage of Microfil(®) , rat kidneys were imaged at the Australian Synchrotron immediately upon tissue preparation and then post fixed in paraformaldehyde and reimaged 24 hours later. The Microfil(®) shrank only 2-5% over the 24 hour period...
August 10, 2017: Clinical and Experimental Pharmacology & Physiology
Jan P Scheifers, Yuemei Zhang, Boniface P T Fokwa
Boron's unique chemical properties and its reactions with metals have yielded the large class of metal borides with compositions ranging from the most boron-rich YB66 (used as monochromator for synchrotron radiation) up to the most metal-rich Nd2Fe14B (the best permanent magnet to date). The excellent magnetic properties of the latter compound originate from its unique crystal structure to which the presence of boron is essential. In general, knowing the crystal structure of any given extended solid is the prerequisite to understanding its physical properties and eventually predicting new synthetic targets with desirable properties...
August 9, 2017: Accounts of Chemical Research
Robert H Temperton, Andrew J Gibson, Karsten Handrup, James N O'Shea
The adsorption and charge transfer dynamics of the organic molecule bi-isonicotinic acid (4,4-dicarboxy-2,2-bipyridine) on single crystal Ag(111) has been studied using synchrotron radiation-based photoemission, x-ray absorption, and resonant core spectroscopies. Measurements for multilayer and monolayer coverage are used to determine the nature of the molecule-surface interactions and the molecular orientation. An experimental density of states for the monolayer with respect to the underlying metal surface is obtained by combining x-ray absorption spectroscopy at the N 1s edge and valence photoemission to measure the unoccupied and occupied valence states, respectively...
August 7, 2017: Journal of Chemical Physics
Anthony Roucou, Guillaume Dhont, Arnaud Cuisset, Marie-Aline Martin-Drumel, Sven Thorwirth, Daniele Fontanari, W Leo Meerts
The ν2 and ν5 fundamental bands of thionyl chloride (SOCl2) were measured in the 420 cm(-1)-550 cm(-1) region using the FT-far-IR spectrometer exploiting synchrotron radiation on the AILES beamline at SOLEIL. A straightforward line-by-line analysis is complicated by the high congestion of the spectrum due to both the high density of SOCl2 rovibrational bands and the presence of the ν2 fundamental band of sulfur dioxide produced by hydrolysis of SOCl2 with residual water. To overcome this difficulty, our assignment procedure for the main isotopologues (32)S(16)O(35)Cl2 and (32)S(16)O(35)Cl(37)Cl alternates between a direct fit of the spectrum, via a global optimization technique, and a traditional line-by-line analysis...
August 7, 2017: Journal of Chemical Physics
Hisashi Naitow, Yoshinori Matsuura, Kensuke Tono, Yasumasa Joti, Takashi Kameshima, Takaki Hatsui, Makina Yabashi, Rie Tanaka, Tomoyuki Tanaka, Michihiro Sugahara, Jun Kobayashi, Eriko Nango, So Iwata, Naoki Kunishima
Serial femtosecond crystallography (SFX) with an X-ray free-electron laser is used for the structural determination of proteins from a large number of microcrystals at room temperature. To examine the feasibility of pharmaceutical applications of SFX, a ligand-soaking experiment using thermolysin microcrystals has been performed using SFX. The results were compared with those from a conventional experiment with synchrotron radiation (SR) at 100 K. A protein-ligand complex structure was successfully obtained from an SFX experiment using microcrystals soaked with a small-molecule ligand; both oil-based and water-based crystal carriers gave essentially the same results...
August 1, 2017: Acta Crystallographica. Section D, Structural Biology
You-Yun Li, Hao-Long Chen, Guo-Ju Chen, Chia-Liang Kuo, Ping-Hung Hsieh, Weng-Sing Hwang
Fe-doped LiNbO₃ synthesized by the combustion method to seek new multiferroic materials exhibits room-temperature ferromagnetism, as reported in our previous work [1]. In this work, the defect structure of congruent and Fe-doped LiNbO₃ (0.57-3.3 mol %) powders was investigated in detail by several methods. The molar ratio of [Li]/([Li]+[Nb]) was determined by the Curie temperature (Tc) via DSC. Two peaks of Tc were observed due to phase splitting [2], and the phase at lower Tc disappears as the Fe doping concentration increases...
April 2, 2017: Materials
Edward S O'Neill, Amandeep Kaur, David P Bishop, Dmitry Shishmarev, Philip W Kuchel, Stuart M Grieve, Gemma A Figtree, Anna K Renfrew, Paul D Bonnitcha, Elizabeth J New
Dense tumors are resistant to conventional chemotherapies due to the unique tumor microenvironment characterized by hypoxic regions that promote cellular dormancy. Bioreductive drugs that are activated in response to this hypoxic environment are an attractive strategy for therapy with anticipated lower harmful side effects in normoxic healthy tissue. Cobalt bioreductive pro-drugs that selectively release toxic payloads upon reduction in hypoxic cells have shown great promise as anticancer agents. However, the bioreductive response in the tumor microenvironment must be better understood, as current techniques for monitoring bioreduction to Co(II) such as X-ray absorption near-edge structure and extended X-ray absorption fine structure provide limited information on speciation and require synchrotron radiation sources...
August 2, 2017: Inorganic Chemistry
Qisheng Wang, Feng Yu, Ying Cui, Kunhao Zhang, Qiangyan Pan, Changyou Zhong, Ke Liu, Huan Zhou, Bo Sun, Jianhua He
The macromolecular crystallography beamlines at third-generation synchrotron facilities play a central role in solving macromolecular crystal structures and also in understanding the biological function at molecular levels. The MX beamline BL17U at Shanghai Synchrotron Radiation Facility is a typical standard MX beamline with a focused beam size (H × V) of FWHM around 80 μm × 45 μm. However the protein samples brought to the beamline are down to 5-10 m from the important and challenging science project now...
July 2017: Review of Scientific Instruments
Kasper Tolborg, Mads R V Jørgensen, Sebastian Christensen, Hidetaka Kasai, Jacob Becker, Peter Walter, Ann Christin Dippel, Jens Als-Nielsen, Bo B Iversen
In recent years powder X-ray diffraction has proven to be a valuable alternative to single-crystal X-ray diffraction for determining electron-density distributions in high-symmetry inorganic materials, including subtle deformation in the core electron density. This was made possible by performing diffraction measurements in vacuum using high-energy X-rays at a synchrotron-radiation facility. Here we present a new version of our custom-built in-vacuum powder diffractometer with the sample-to-detector distance increased by a factor of four...
August 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
Nicolai Koebernick, Keith R Daly, Samuel D Keyes, Timothy S George, Lawrie K Brown, Annette Raffan, Laura J Cooper, Muhammad Naveed, Anthony G Bengough, Ian Sinclair, Paul D Hallett, Tiina Roose
In this paper, we provide direct evidence of the importance of root hairs on pore structure development at the root-soil interface during the early stage of crop establishment. This was achieved by use of high-resolution (c. 5 μm) synchrotron radiation computed tomography (SRCT) to visualise both the structure of root hairs and the soil pore structure in plant-soil microcosms. Two contrasting genotypes of barley (Hordeum vulgare), with and without root hairs, were grown for 8 d in microcosms packed with sandy loam soil at 1...
July 31, 2017: New Phytologist
E Troja, V M Lipunov, C G Mundell, N R Butler, A M Watson, S Kobayashi, S B Cenko, F E Marshall, R Ricci, A Fruchter, M H Wieringa, E S Gorbovskoy, V Kornilov, A Kutyrev, W H Lee, V Toy, N V Tyurina, N M Budnev, D A H Buckley, J González, O Gress, A Horesh, M I Panasyuk, J X Prochaska, E Ramirez-Ruiz, R Rebolo Lopez, M G Richer, C Román-Zúñiga, M Serra-Ricart, V Yurkov, N Gehrels
Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light. These outflows power prompt, brief and intense flashes of γ-rays known as γ-ray bursts (GRBs), followed by longer-lived afterglow radiation that is detected across the electromagnetic spectrum. Measuring the polarization of the observed GRB radiation provides a direct probe of the magnetic fields in the collimated jets. Rapid-response polarimetric observations of newly discovered bursts have probed the initial afterglow phase, and show that, minutes after the prompt emission has ended, the degree of linear polarization can be as high as 30 per cent-consistent with the idea that a stable, globally ordered magnetic field permeates the jet at large distances from the central source...
July 26, 2017: Nature
Manuel Izquierdo, Piero Torelli, Jun Fujii, Giancarlo Panaccione, Ivana Vobornik, Giorgio Rossi, Fausto Sirotti
Carbon (C) surface segregation from bulk stabilizes the Fe(0 18 1) vicinal surface by forming a c(3[Formula: see text] × [Formula: see text] reconstruction with C zig-zag chains oriented at 45° with respect to the iron surface steps. The iron surface electronic states as measured by high resolution ARPES at normal emission with polarized synchrotron radiation split in two peaks that follow distinct energy dispersion curves. One peak follows the dispersion of the carbon superstructure and is photoexcited only when the polarization vector is parallel to the steps, the second peak disperses similarly to the pristine Fe(0 0 1) surface...
July 26, 2017: Scientific Reports
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