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https://www.readbyqxmd.com/read/28723150/double-imaging-photoelectron-photoion-coincidence-sheds-new-light-on-the-dissociation-of-state-selected-ch3f-ions
#1
Xiaofeng Tang, Gustavo A Garcia, Laurent Nahon
The vacuum ultraviolet (VUV) photoionization and dissociative photoionization of methyl fluoride (CH3F) in the 12.2-19.8 eV energy range were investigated by using synchrotron radiation coupled to a double imaging photoelectron photoion coincidence (i(2)PEPICO) spectrometer. The production of several fragment ions including CH2F(+), CHF(+), CH3(+) and CH2(+) as a function of state and internal energy of CH3F(+) ions was identified and analyzed, with their individual appearance energies measured through threshold photoelectron spectroscopy...
July 19, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28721902/permeability-of-brain-tumor-vessels-induced-by-uniform-or-spatially-microfractionated-synchrotron-radiation-therapies
#2
Audrey Bouchet, Marine Potez, Nicolas Coquery, Claire Rome, Benjamin Lemasson, Elke Bräuer-Krisch, Chantal Rémy, Jean Laissue, Emmanuel L Barbier, Valentin Djonov, Raphael Serduc
PURPOSE: To compare the blood-brain barrier permeability changes induced by synchrotron microbeam radiation therapy (MRT, which relies on spatial fractionation of the incident x-ray beam into parallel micron-wide beams) with changes induced by a spatially uniform synchrotron x-ray radiation therapy. METHODS AND MATERIALS: Male rats bearing malignant intracranial F98 gliomas were randomized into 3 groups: untreated, exposed to MRT (peak and valley dose: 241 and 10...
August 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28718696/tumor-induced-disorder-of-iron-metabolism-in-major-organs-a-new-insight-from-chemical-speciation-of-iron
#3
Rujie Chen, Guangcun Chen
Objective To investigate the evolution of iron speciation in major organs of tumor-bearing mice and its role in cancer formation and cancer-associated complications. Methods The concentration and chemical speciation of iron in the spleen, liver, lung, kidney, heart, blood, muscle, and tumor tissue of healthy mice and tumor-bearing mice were studied by synchrotron radiation-based total reflection X-ray fluorescence spectrometry (SR-TXRF) coupled with X-ray absorption spectroscopy (XAS). Results The TXRF and XAS results showed that the iron content, especially the ferritin content, significantly decreased in the blood and spleen but significantly increased in the liver, lung, and muscle of mice after tumor implantation...
January 1, 2017: Journal of International Medical Research
https://www.readbyqxmd.com/read/28699688/photoionization-and-ionic-dissociation-of-the-c3-h3-ns-molecule-induced-by-soft-x-ray-near-the-c1s-edge
#4
A F Lago, R D Januário, R L Cavasso Filho, M Simon, J Z Dávalos
Time of flight mass spectrometry, electron-ion coincidence and ion yield spectroscopy were employed to investigate for the first time the thiazole (C3 H3 NS) molecule in the gas phase excited by synchrotron radiation in the soft X-ray domain. Total Ion Yield and PEPICO spectra were recorded as a function of the photon energy in the vicinity of the carbon K edge (C1s). The C1s resonant transitions as well as the core ionization thresholds have been determined from the profile of TIY spectrum and the features were discussed...
July 12, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28698654/megapixel-multi-elemental-imaging-by-laser-induced-breakdown-spectroscopy-a-technology-with-considerable-potential-for-paleoclimate-studies
#5
J O Cáceres, F Pelascini, V Motto-Ros, S Moncayo, F Trichard, G Panczer, A Marín-Roldán, J A Cruz, I Coronado, J Martín-Chivelet
Paleoclimate studies play a crucial role in understanding past and future climates and their environmental impacts. Current methodologies for performing highly sensitive elemental analysis at micrometre spatial resolutions are restricted to the use of complex and/or not easily applied techniques, such as synchrotron radiation X-ray fluorescence micro-analysis (μ-SRXRF), nano secondary ion mass spectrometry (nano-SIMS) or laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Moreover, the analysis of large samples (>few cm²) with any of these methods remains very challenging due to their relatively low acquisition speed (~1-10 Hz), and because they must be operated in vacuum or controlled atmosphere...
July 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28698372/crystal-structure-of-co-bound-cytochrome-c-oxidase-determined-by-serial-femtosecond-x-ray-crystallography-at-room-temperature
#6
Izumi Ishigami, Nadia A Zatsepin, Masahide Hikita, Chelsie E Conrad, Garrett Nelson, Jesse D Coe, Shibom Basu, Thomas D Grant, Matthew H Seaberg, Raymond G Sierra, Mark S Hunter, Petra Fromme, Raimund Fromme, Syun-Ru Yeh, Denis L Rousseau
Cytochrome c oxidase (CcO), the terminal enzyme in the electron transfer chain, translocates protons across the inner mitochondrial membrane by harnessing the free energy generated by the reduction of oxygen to water. Several redox-coupled proton translocation mechanisms have been proposed, but they lack confirmation, in part from the absence of reliable structural information due to radiation damage artifacts caused by the intense synchrotron radiation. Here we report the room temperature, neutral pH (6.8), damage-free structure of bovine CcO (bCcO) in the carbon monoxide (CO)-bound state at a resolution of 2...
July 11, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28696751/detecting-molecular-rotational-dynamics-complementing-the-low-frequency-terahertz-vibrations-in-a-zirconium-based-metal-organic-framework
#7
Matthew R Ryder, Ben Van de Voorde, Bartolomeo Civalleri, Thomas D Bennett, Sanghamitra Mukhopadhyay, Gianfelice Cinque, Felix Fernandez-Alonso, Dirk De Vos, Svemir Rudić, Jin-Chong Tan
We show clear experimental evidence of cooperative terahertz (THz) dynamics observed below 3 THz (∼100  cm^{-1}), for a low-symmetry Zr-based metal-organic framework structure, termed MIL-140A [ZrO(O_{2}C-C_{6}H_{4}-CO_{2})]. Utilizing a combination of high-resolution inelastic neutron scattering and synchrotron radiation far-infrared spectroscopy, we measured low-energy vibrations originating from the hindered rotations of organic linkers, whose energy barriers and detailed dynamics have been elucidated via ab initio density functional theory calculations...
June 23, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28693947/synchrotron-radiation-%C3%AE-ct-and-histology-evaluation-of-bone-to-implant-contact
#8
Camilla Albeck Neldam, Jon Sporring, Alexander Rack, Torsten Lauridsen, Ellen-Margrethe Hauge, Henrik L Jørgensen, Niklas Rye Jørgensen, Robert Feidenhansl, Else Marie Pinholt
The purpose of this study was to evaluate bone-to-implant contact (BIC) in two-dimensional (2D) histology compared to high-resolution three-dimensional (3D) synchrotron radiation micro computed tomography (SR micro-CT). High spatial resolution, excellent signal-to-noise ratio, and contrast establish SR micro-CT as the leading imaging modality for hard X-ray microtomography. Using SR micro-CT at voxel size 5 μm in an experimental goat mandible model, no statistically significant difference was found between the different treatment modalities nor between recipient and reconstructed bone...
June 3, 2017: Journal of Cranio-maxillo-facial Surgery
https://www.readbyqxmd.com/read/28693671/100-years-of-x-ray-crystallography
#9
Terence J Kemp, W Alcock
The developments in crystallography, since it was first covered in Science Progress in 1917, following the formulation of the Bragg equation, are described. The advances in instrumentation and data analysis, coupled with the application of computational methods to data analysis, have enabled the solution of molecular structures from the simplest binary systems to the most complex of biological structures. These developments are shown to have had major impacts in the development of chemical bonding theory and in offering an increasing understanding of enzyme-substrate interactions...
March 1, 2017: Science Progress
https://www.readbyqxmd.com/read/28688448/valence-shell-threshold-photoelectron-spectroscopy-of-the-chxcn-x-0-2-and-cnc-radicals
#10
Gustavo A Garcia, Julia Krüger, Bérenger Gans, Cyril Falvo, Laurent H Coudert, Jean-Christophe Loison
We present the photoelectron spectroscopy of four radical species, CHxCN (x = 0-2) and CNC, formed in a microwave discharge flow-tube reactor by consecutive H abstractions from CH3CN (CHxCN + F → CHx-1CN + HF (x = 1-3)). The spectra were obtained combining tunable vacuum ultraviolet synchrotron radiation with double imaging electron/ion coincidence techniques, which yielded mass-selected threshold photoelectron spectra. The results obtained for H2CCN complement existing ones while for the other radicals the data represent the first observation of their (single-photon) ionizing transitions...
July 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28688422/an-imaging-photoelectron-photoion-coincidence-investigation-of-homochiral-2r-3r-butanediol-clusters
#11
Steven Daly, Ivan Powis, Gustavo A Garcia, Maurice Tia, Laurent Nahon
We report an experimental investigation of homochiral cluster formation in seeded molecular beam expansions of (2R,3R)-butanediol. Synchrotron radiation vacuum ultraviolet photoionization measurements have been performed using a double imaging electron-ion spectrometer in various configurations and modes of operation. These include measurements of the cluster ion mass spectra, wavelength scanned ion yields, and threshold electron spectra. Protonated cluster ions ranging up to n = 7 have been observed and size-selected photoelectron spectra and photoelectron circular dichroism (PECD) have been recorded by velocity map imaging, recorded in coincidence with ions, at a number of fixed photon energies...
July 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28684994/glycoscience-synchrotron-synchrotron-radiation-applied-to-structural-glycoscience
#12
REVIEW
Serge Pérez, Daniele de Sanctis
Synchrotron radiation is the most versatile way to explore biological materials in different states: monocrystalline, polycrystalline, solution, colloids and multiscale architectures. Steady improvements in instrumentation have made synchrotrons the most flexible intense X-ray source. The wide range of applications of synchrotron radiation is commensurate with the structural diversity and complexity of the molecules and macromolecules that form the collection of substrates investigated by glycoscience. The present review illustrates how synchrotron-based experiments have contributed to our understanding in the field of structural glycobiology...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28680138/investigation-of-thermally-induced-degradation-in-ch3nh3pbi3-perovskite-solar-cells-using-in-situ-synchrotron-radiation-analysis
#13
Nam-Koo Kim, Young Hwan Min, Seokhwan Noh, Eunkyung Cho, Gitaeg Jeong, Minho Joo, Seh-Won Ahn, Jeong Soo Lee, Seongtak Kim, Kyuwook Ihm, Hyungju Ahn, Yoonmook Kang, Hae-Seok Lee, Donghwan Kim
In this study, we employ a combination of various in-situ surface analysis techniques to investigate the thermally induced degradation processes in MAPbI3 perovskite solar cells (PeSCs) as a function of temperature under air-free conditions (no moisture and oxygen). Through a comprehensive approach that combines in-situ grazing-incidence wide-angle X-ray diffraction (GIWAXD) and high-resolution X-ray photoelectron spectroscopy (HR-XPS) measurements, we confirm that the surface structure of MAPbI3 perovskite film changes to an intermediate phase and decomposes to CH3I, NH3, and PbI2 after both a short (20 min) exposure to heat stress at 100 °C and a long exposure (>1 hour) at 80 °C...
July 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28680101/a-storage-ring-based-free-electron-laser-for-generating-ultrashort-coherent-euv-and-x-ray-radiation
#14
Chao Feng, Zhentang Zhao
Generation of ultrashort coherent radiation pulses in the extreme ultraviolet (EUV) and x-ray regime is of remarkable interest in the synchrotron radiation user community. In this work, a novel technique is proposed for directly imprinting strong coherent microbunching on the electron beam with very small laser-induced energy spread. Theoretical analysis and numerical simulations demonstrated that this technique can be used for the generation of megawatt-scale level, fully temporal coherent femtosecond EUV and soft x-ray radiation pulses at a storage ring light source...
July 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28678253/single-photon-absorption-of-isolated-collagen-mimetic-peptides-and-triple-helix-models-in-the-vuv-x-energy-range
#15
Lucas Schwob, Mathieu Lalande, Jimmy Rangama, Dmitrii Egorov, Ronnie Hoekstra, Rahul Pandey, Samuel Eden, Thomas Schlathölter, Violaine Vizcaino, Jean-Christophe Poully
Cartilage and tendons owe their special mechanical properties to the fibrous collagen structure. These strong fibrils are aggregates of a sub-unit consisting of three collagen proteins wound around each other in a triple helix. Even though collagen is the most abundant protein in the human body, the response of this protein complex to ionizing radiation has never been studied. In this work, we probe the direct effects of VUV and soft X-ray photons on isolated models of the collagen triple helix, by coupling a tandem mass spectrometer to a synchrotron beamline...
July 5, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28674417/serial-femtosecond-crystallography-structure-of-cytochrome-c-oxidase-at-room-temperature
#16
Rebecka Andersson, Cecilia Safari, Robert Dods, Eriko Nango, Rie Tanaka, Ayumi Yamashita, Takanori Nakane, Kensuke Tono, Yasumasa Joti, Petra Båth, Elin Dunevall, Robert Bosman, Osamu Nureki, So Iwata, Richard Neutze, Gisela Brändén
Cytochrome c oxidase catalyses the reduction of molecular oxygen to water while the energy released in this process is used to pump protons across a biological membrane. Although an extremely well-studied biological system, the molecular mechanism of proton pumping by cytochrome c oxidase is still not understood. Here we report a method to produce large quantities of highly diffracting microcrystals of ba 3-type cytochrome c oxidase from Thermus thermophilus suitable for serial femtosecond crystallography. The room-temperature structure of cytochrome c oxidase is solved to 2...
July 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28668050/ionization-of-pyridine-interplay-of-orbital-relaxation-and-electron-correlation
#17
A B Trofimov, D M P Holland, I Powis, R C Menzies, A W Potts, L Karlsson, E V Gromov, I L Badsyuk, J Schirmer
The valence shell ionization spectrum of pyridine was studied using the third-order algebraic-diagrammatic construction approximation scheme for the one-particle Green's function and the outer-valence Green's function method. The results were used to interpret angle resolved photoelectron spectra recorded with synchrotron radiation in the photon energy range of 17-120 eV. The lowest four states of the pyridine radical cation, namely, (2)A2(1a2(-1)), (2)A1(7a1(-1)), (2)B1(2b1(-1)), and (2)B2(5b2(-1)), were studied in detail using various high-level electronic structure calculation methods...
June 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28667968/fast-x-ray-detector-system-with-simultaneous-measurement-of-timing-and-energy-for-a-single-photon
#18
T Masuda, S Okubo, H Hara, T Hiraki, S Kitao, Y Miyamoto, K Okai, R Ozaki, N Sasao, M Seto, S Uetake, A Yamaguchi, Y Yoda, A Yoshimi, K Yoshimura
We developed a fast X-ray detector system for nuclear resonant scattering (NRS) experiments. Our system employs silicon avalanche photo-diode (Si-APD) as a fast X-ray sensor. The system is able to acquire both timing and energy of a single X-ray photon simultaneously in a high rate condition, 10(6) counts per second for one Si-APD. The performance of the system was investigated in SPring-8, a synchrotron radiation facility in Japan. Good time resolution of 120 ps (FWHM) was achieved with a slight tail distribution in the time spectrum by a level of 10(-9) at 1 ns apart from the peak...
June 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28666767/towards-breast-cancer-rotational-radiotherapy-with-synchrotron-radiation
#19
Francesca Di Lillo, Giovanni Mettivier, Antonio Sarno, Roberta Castriconi, Paolo Russo
PURPOSE: We performed the first investigations, via measurements and Monte Carlo simulations on phantoms, of the feasibility of a new technique for synchrotron radiation rotational radiotherapy for breast cancer (SR(3)T). METHODS: A Monte Carlo (MC) code based on Geant4 toolkit was developed in order to simulate the irradiation with the SR(3)T technique and to evaluate the skin sparing effect in terms of centre-to-periphery dose ratio at different energies in the range 60-175keV...
June 27, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28665636/x-ray-phase-contrast-radiography-and-tomography-with-a-multiaperture-analyzer
#20
M Endrizzi, F A Vittoria, L Rigon, D Dreossi, F Iacoviello, P R Shearing, A Olivo
We present a multiaperture analyzer setup for performing x-ray phase contrast imaging in planar and three-dimensional modalities. The method is based on strongly structuring the x-ray beam with an amplitude modulator, before it reaches the sample, and on a multiaperture analyzing element before detection. A multislice representation of the sample is used to establish a quantitative relation between projection images and the corresponding three-dimensional distributions, leading to successful tomographic reconstruction...
June 16, 2017: Physical Review Letters
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