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https://www.readbyqxmd.com/read/29208996/relativistic-inverse-compton-scattering-of-photons-from-the-early-universe
#1
Siddharth Malu, Abhirup Datta, Sergio Colafrancesco, Paolo Marchegiani, Ravi Subrahmanyan, D Narasimha, Mark H Wieringa
Electrons at relativistic speeds, diffusing in magnetic fields, cause copious emission at radio frequencies in both clusters of galaxies and radio galaxies through non-thermal radiation emission called synchrotron. However, the total power radiated through this mechanism is ill constrained, as the lower limit of the electron energy distribution, or low-energy cutoffs, for radio emission in galaxy clusters and radio galaxies, have not yet been determined. This lower limit, parametrized by the lower limit of the electron momentum - pmin - is critical for estimating the total energetics of non-thermal electrons produced by cluster mergers or injected by radio galaxy jets, which impacts the formation of large-scale structure in the universe, as well as the evolution of local structures inside galaxy clusters...
December 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29207234/vacuum-uv-polarization-spectroscopy-of-p-terphenyl
#2
Duy Duc Nguyen, Nykola C Jones, Søren Vrønning Hoffmann, Jens Spanget-Larsen
p-Terphenyl is used as a component in a variety of optical devices. In this investigation, the electronic transitions of p-terphenyl are investigated by synchrotron radiation linear dichroism (SRLD) spectroscopy in the range 30000 - 58000 cm-1 (330 - 170 nm) on molecular samples aligned in stretched polyethylene, thereby extending the region investigated by polarization spectroscopy into the vacuum UV. The resulting partial absorbance curves reveal that the vacuum UV band system with a maximum at 55000 cm-1 (180 nm) is predominantly short axis-polarized...
December 5, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29203779/plasma-channel-undulator-excited-by-high-order-laser-modes
#3
J W Wang, C B Schroeder, R Li, M Zepf, S G Rykovanov
The possibility of utilizing plasma undulators and plasma accelerators to produce compact ultraviolet and X-ray sources, has attracted considerable interest for a few decades. This interest has been driven by the great potential to decrease the threshold for accessing such sources, which are mainly provided by a few dedicated large-scale synchrotron or free-electron laser (FEL) facilities. However, the broad radiation bandwidth of such plasma devices limits the source brightness and makes it difficult for the FEL instability to develop...
December 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29200226/green-synthesis-of-a-new-layered-aluminium-citraconate-crystal-structures-intercalation-behaviour-towards-h2o-and-in-situ-pxrd-studies-of-its-crystallisation
#4
Niclas Heidenreich, Alexandra Lieb, Norbert Stock, Helge Reinsch
A new Al-based layered MOF [Al2(OH)4(O2C-C3H4-CO2)]·nH2O denoted as CAU-15-Cit was synthesised under mild aqueous conditions. It exhibits a layered structure incorporating infinite chains of edge-sharing AlO6 polyhedra being interconnected by citraconate anions to arrange into layers, which are stacked in an AAA fashion (citraconic acid = methylmaleic acid = H2Cit, HO2C-C3H4-CO2H). The crystal structures of the hydrated and dehydrated MOF were determined ab initio from powder X-ray diffraction (PXRD) data...
December 4, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29199979/a-standardized-technique-for-high-pressure-cooling-of-protein-crystals
#5
David Quirnheim Pais, Barbara Rathmann, Juergen Koepke, Cveta Tomova, Paul Wurzinger, Yvonne Thielmann
Cryogenic temperatures slow down secondary radiation damage during data collection from macromolecular crystals. In 1973, cooling at high pressure was identified as a method for cryopreserving crystals in their mother liquor [Thomanek et al. (1973). Acta Cryst. A29, 263-265]. Results from different groups studying different crystal systems indicated that the approach had merit, although difficulties in making the process work have limited its widespread use. Therefore, a simplified and reliable technique has been developed termed high-pressure cooling (HPC)...
December 1, 2017: Acta Crystallographica. Section D, Structural Biology
https://www.readbyqxmd.com/read/29196935/serial-femtosecond-crystallography-at-the-sacla-breakthrough-to-dynamic-structural-biology
#6
REVIEW
Eiichi Mizohata, Takanori Nakane, Yohta Fukuda, Eriko Nango, So Iwata
X-ray crystallography visualizes the world at the atomic level. It has been used as the most powerful technique for observing the three-dimensional structures of biological macromolecules and has pioneered structural biology. To determine a crystal structure with high resolution, it was traditionally required to prepare large crystals (> 200 μm). Later, synchrotron radiation facilities, such as SPring-8, that produce powerful X-rays were built. They enabled users to obtain good quality X-ray diffraction images even with smaller crystals (ca...
December 1, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/29195417/quantification-of-stiffness-measurement-errors-in-resonant-ultrasound-spectroscopy-of-human-cortical-bone
#7
Xiran Cai, Laura Peralta, Pierre-Jean Gouttenoire, Cécile Olivier, Françoise Peyrin, Pascal Laugier, Quentin Grimal
Resonant ultrasound spectroscopy (RUS) is the state-of-the-art method used to investigate the elastic properties of anisotropic solids. Recently, RUS was applied to measure human cortical bone, an anisotropic material with low Q-factor (20), which is challenging due to the difficulty in retrieving resonant frequencies. Determining the precision of the estimated stiffness constants is not straightforward because RUS is an indirect method involving minimizing the distance between measured and calculated resonant frequencies using a model...
November 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/29195371/cat-act-a-new-highly-versatile-x-ray-spectroscopy-beamline-for-catalysis-and-radionuclide-science-at-the-kit-synchrotron-light-facility-anka
#8
A Zimina, K Dardenne, M A Denecke, D E Doronkin, E Huttel, H Lichtenberg, S Mangold, T Pruessmann, J Rothe, Th Spangenberg, R Steininger, T Vitova, H Geckeis, J-D Grunwaldt
CAT-ACT-the hard X-ray beamline for CATalysis and ACTinide/radionuclide research at the KIT synchrotron radiation facility ANKA-is dedicated to X-ray spectroscopy, including "flux hungry" photon-in/photon-out and correlative techniques and combines state-of-the-art optics with a unique infrastructure for radionuclide and catalysis research. Measurements can be performed at photon energies varying between 3.4 keV and 55 keV, thus encompassing the actinide M- and L-edge or potassium K-edge up to the K-edges of the lanthanide series such as cerium...
November 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29189770/langmuir-blodgett-nanotemplates-for-protein-crystallography
#9
Eugenia Pechkova, Claudio Nicolini
The new generation of synchrotrons and microfocused beamlines has enabled great progress in X-ray protein crystallography, resulting in new 3D atomic structures for proteins of high interest to the pharmaceutical industry and life sciences. It is, however, often still challenging to produce protein crystals of sufficient size and quality (order, intensity of diffraction, radiation stability). In this protocol, we provide instructions for performing the Langmuir-Blodgett (LB) nanotemplate method, a crystallization approach that can be used for any protein (including membrane proteins)...
December 2017: Nature Protocols
https://www.readbyqxmd.com/read/29189105/characterization-of-diffuse-intrinsic-pontine-glioma-radiosensitivity-using-synchrotron-microbeam-radiotherapy-and-conventional-radiation-therapy-in-vitro
#10
L M Smyth, P A W Rogers, J C Crosbie, J F Donoghue
Synchrotron microbeam radiation therapy is a promising preclinical radiotherapy modality that has been proposed as an alternative to conventional radiation therapy for diseases such as diffuse intrinsic pontine glioma (DIPG), a devastating pediatric tumor of the brainstem. The primary goal of this study was to characterize and compare the radiosensitivity of two DIPG cell lines (SF7761 and JHH-DIPG-1) to microbeam and conventional radiation. We hypothesized that these DIPG cell lines would exhibit differential responses to each radiation modality...
November 30, 2017: Radiation Research
https://www.readbyqxmd.com/read/29180654/ellipsoidal-mirror-for-two-dimensional-100-nm-focusing-in-hard-x-ray-region
#11
Hirokatsu Yumoto, Takahisa Koyama, Satoshi Matsuyama, Yoshiki Kohmura, Kazuto Yamauchi, Tetsuya Ishikawa, Haruhiko Ohashi
Cutting-edge hard X-ray microscopy strongly depends on sophisticated focusing optics and ultrabright X-ray sources at synchrotron-radiation and X-ray free-electron laser (XFEL) facilities. These facilities typically provide two-dimensional nanofocusing X-ray beams by combining one-dimensional focusing mirrors. However, single-reflecting two-dimensional focusing mirrors with an ellipsoidal surface, which are well-known to possess high efficiency, have limited microfocusing applications. In this paper, we present an ultrahigh-precision ellipsoidal mirror for two-dimensional X-ray nanofocusing by overcoming the difficulties faced in the manufacturing process of its aspherical surface, including the surface-processing methods and surface metrology...
November 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29177785/elemental-composition-of-pm2-5-in-the-urban-environment-of-san-juan-argentina
#12
Mariela Aguilera Sammaritano, Daniel G Bustos, Arnobio G Poblete, Eduardo D Wannaz
This study contributes to the current knowledge about air pollution in the province of San Juan, Argentina. Sampling was carried out to measure the fine particulate matter in the atmosphere (PM2.5) of the city of San Juan. PM2.5 was collected continuously during the winter and spring seasons of 2014 and 2015, and the concentrations of 14 elements (Pb, Ca, K, Cd, Ni, Cr, Mn, V, Cu, Ti, Ba, Co, Sr, and Fe) were determined in PM2.5 filters using the technique of X-ray fluorescence by synchrotron radiation (SR-XRF)...
November 25, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29173465/the-chemical-speciation-spatial-distribution-and-toxicity-of-mercury-from-tibetan-medicine-zuotai%C3%AF-%C3%AE-hgs-and-hgcl2-in-mouse-kidney
#13
Cen Li, Wei Xu, Shengqi Chu, Zhiyuan Zheng, Yuancan Xiao, Linshuai Li, Hongtai Bi, Lixin Wei
Zuotai, a famous Tibetan medicinal mixture containing β-HgS, has been used to combine with herbal remedies for treating diseases for more than 1 300 years. The target organ for inorganic mercury toxicity is generally considered to be the kidney. Therefore, it is crucial to reveal the chemical speciation, spatial distribution and potential nephrotoxicity of mercury from Zuotai in kidney. To date, this remains poorly understood. We used X-ray absorption spectroscopy (XAS) and micro X-ray fluorescence (μ-XRF) imaging based on synchrotron radiation to study mercury chemical forms and mercury special distribution in kidney after mice were treated orally with Zuotai, β-HgS or HgCl2...
January 2018: Journal of Trace Elements in Medicine and Biology
https://www.readbyqxmd.com/read/29170428/complex-three-dimensional-self-assembly-in-proxies-for-atmospheric-aerosols
#14
C Pfrang, K Rastogi, E R Cabrera-Martinez, A M Seddon, C Dicko, A Labrador, T S Plivelic, N Cowieson, A M Squires
Aerosols are significant to the Earth's climate, with nearly all atmospheric aerosols containing organic compounds that often contain both hydrophilic and hydrophobic parts. However, the nature of how these compounds are arranged within an aerosol droplet remains unknown. Here we demonstrate that fatty acids in proxies for atmospheric aerosols self-assemble into highly ordered three-dimensional nanostructures that may have implications for environmentally important processes. Acoustically trapped droplets of oleic acid/sodium oleate mixtures in sodium chloride solution are analysed by simultaneous synchrotron small-angle X-ray scattering and Raman spectroscopy in a controlled gas-phase environment...
November 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/29168517/crossed-beam-polyatomic-reaction-dynamics-recent-advances-and-new-insights
#15
REVIEW
Huilin Pan, Kopin Liu, Adriana Caracciolo, Piergiorgio Casavecchia
Over the past ten years or so, great advances in our understanding of the dynamics of elementary (bimolecular) polyatomic reactions in the gas-phase have occurred. This has been made possible by critical improvements (a) in crossed molecular beam (CMB) instruments with rotating mass spectrometric detection and time-of-flight analysis, especially following the implementation of soft ionization (by tunable low energy electrons or vacuum-ultraviolet synchrotron radiation) for product detection with increased sensitivity and universal detection power, and (b) in REMPI-slice velocity map ion imaging (VMI) detection techniques in pulsed CMB experiments for obtaining product pair-correlated information through high-resolution measurements directly in the center of mass system...
November 23, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/29166118/photofragmentation-of-gas-phase-acetic-acid-and-acetamide-clusters-in-the-vacuum-ultraviolet-region
#16
Marta Berholts, Hanna Myllynen, Kuno Kooser, Eero Itälä, Sari Granroth, Helena Levola, Joakim Laksman, Shabnam Oghbaiee, Bart Oostenrijk, Ergo Nõmmiste, Edwin Kukk
Photofragmentation of gas-phase acetamide and acetic acid clusters produced by a supersonic expansion source has been studied using time-of-flight mass spectrometry and the partial ion yield (PIY) technique combined with tunable vacuum-ultraviolet synchrotron radiation. Appearance energies of the clusters and their fragments were experimentally determined from the PIY measurements. The effect of clusterization conditions on the formation and fragmentation of acetic acid clusters was investigated. Ab initio quantum mechanical calculations were performed on both samples' dimers to find their neutral and ionized geometries as well as proton transfer energy barriers leading to the optimal geometries...
November 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29164237/feasibility-study-of-the-3d-visualization-at-high-resolution-of-intra-cranial-rabbit-eyes-with-x-ray-ct-phase-contrast-imaging
#17
Yury Ivanishko, Alberto Bravin, Sergey Kovalev, Polina Lisutina, Mikhail Lotoshnikov, Alberto Mittone, Sergey Tkachev, Marina Tkacheva
Purpose: The intracranial three-dimensional (3D) visualization of the whole volume of the eyeball at micrometric resolution has not been achieved yet either in clinical nor in preclinical diagnostic research. Overcoming this limitation may provide a new tool for clinical and preclinical studies of different pathologies of the various sections of the eye. The aim of this work is to give the first insight of a volumetric visualization at the high resolution of the entire enucleated and intracranial postmortem rabbit eyeballs...
November 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29163140/simultaneous-imaging-of-cerebrovascular-structure-and-function-in-hypertensive-rats-using-synchrotron-radiation-angiography
#18
Liping Wang, Zhihao Mu, Xiaojie Lin, Jieli Geng, Ti Qiao Xiao, Zhijun Zhang, Yongting Wang, Yongjing Guan, Guo-Yuan Yang
Hypertension has a profound influence on the structure and function of blood vessels. Cerebral vessels undergo both structural and functional changes in hypertensive animals. However, dynamic changes of cerebrovasculature and the factors involved in this process are largely unknown. In this study, we explored the dynamic changes of vascular structure in hypertensive rats using novel synchrotron radiation angiography. Twenty-four spontaneously hypertensive rats (SHR) and 24 Sprague-Dawley (SD) rats underwent synchrotron radiation (SR) angiography...
2017: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/29160311/microstructure-variations-induced-by-excess-pbx2-or-ax-within-perovskite-thin-films
#19
Guanhaojie Zheng, Cheng Zhu, Yihua Chen, Juchen Zhang, Qi Chen, Xingyu Gao, Huanping Zhou
We systematically investigated the impact of stoichiometric ratio variation between PbX2 and AX on hybrid perovskite films from the perspective of microstructure, especially on the plane stacking directions, using the two-dimensional synchrotron radiation grazing incidence wide-angle X-ray scattering (GIWAXS) technique. The tuned crystal plane stacking in perovskite films can consequently enlighten further explorations about the relationship between microstructure and solar cell performance.
November 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29154311/precise-measurement-of-inner-diameter-of-mono-capillary-optic-using-x-ray-imaging-technique
#20
Soonmu Kwon, Jae Hong Lim, Yoshiharu Namba, Kwon Su Chon
BACKGROUND: Mono-capillary optics have been applied to increase the performance of X-ray instruments. However, performance of a mono-capillary optic strongly depends on the shape accuracy, which is determined by the diameters of the inner hollow of the capillary along the axial direction. OBJECTIVE: To precisely determine the inner diameter of the capillary optic used in X-ray imaging technique, which aims to replace the conventional method using a visible microscope...
November 16, 2017: Journal of X-ray Science and Technology
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