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https://www.readbyqxmd.com/read/29775319/operando-evidence-for-a-universal-oxygen-evolution-mechanism-on-thermal-and-electrochemical-iridium-oxides
#1
Viktoriia A Saveleva, Li Wang, Detre Teschner, Travis E Jones, Aldo S Gago, K Andreas Friedrich, Spyridon Zafeiratos, Robert Schloegl, Elena R Savinova
Progress in the development of the proton exchange membrane (PEM) water electrolysis technology requires decreasing the anode overpotential, where the sluggish multistep oxygen evolution reaction (OER) occurs. This calls for the understanding of the nature of the active OER sites and reaction intermediates, which are still being debated. In this work, we apply synchrotron radiation - based near ambient pressure X-ray photoelectron and absorption spectroscopies under operando conditions in order to unveil the nature of the reaction intermediates and shed light on the OER mechanism on electrocatalysts most widely used in PEM electrolyzers - electrochemical and thermal iridium oxides...
May 18, 2018: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29773822/origin-of-magnetic-properties-in-carbon-implanted-zno-nanowires
#2
Y F Wang, Y C Shao, S H Hsieh, Y K Chang, P H Yeh, H C Hsueh, J W Chiou, H T Wang, S C Ray, H M Tsai, C W Pao, C H Chen, H J Lin, J F Lee, C T Wu, J J Wu, Y M Chang, K Asokan, K H Chae, T Ohigashi, Y Takagi, T Yokoyama, N Kosugi, W F Pong
Various synchrotron radiation-based spectroscopic and microscopic techniques are used to elucidate the room-temperature ferromagnetism of carbon-doped ZnO-nanowires (ZnO-C:NW) via a mild C+ ion implantation method. The photoluminescence and magnetic hysteresis loops reveal that the implantation of C reduces the number of intrinsic surface defects and increases the saturated magnetization of ZnO-NW. The interstitial implanted C ions constitute the majority of defects in ZnO-C:NW as confirmed by the X-ray absorption spectroscopic studies...
May 17, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29772895/reversible-assembly-of-a-drug-peptide-into-amyloid-fibrils-a-dynamic-circular-dichroism-study
#3
Frédéric Gobeaux, Frank Wien
The common view on the amyloid fibril formation is that it is a multistep process that involves many oligomeric intermediate species, which leads to a high degree of polymorphism. This view derives from numerous kinetic studies whose vast majority was carried out with amyloid β fragments or other pathological amyloidogenic sequences. Yet, it is not clear whether the mechanisms inferred from these studies are universal and also apply to functional amyloids, in particular to peptide hormones which form reversible amyloid structures...
May 18, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29772689/fabrication-and-characterization-of-nanoenergetic-hollow-spherical-hexanitrostibene-hns-derivatives
#4
Xiong Cao, Peng Deng, Shuangqi Hu, Lijun Ren, Xiaoxia Li, Peng Xiao, Yu Liu
The spherization of nanoenergetic materials is the best way to improve the sensitivity and increase loading densities and detonation properties for weapons and ammunition, but the preparation of spherical nanoenergetic materials with high regularization, uniform size and monodispersity is still a challenge. In this paper, nanoenergetic hollow spherical hexanitrostibene (HNS) derivatives were fabricated via a one-pot copolymerization strategy, which is based on the reaction of HNS and piperazine in acetonitrile solution...
May 16, 2018: Nanomaterials
https://www.readbyqxmd.com/read/29765420/a-feasible-method-of-angiogenesis-assessment-in-gastric-cancer-using-3d-microvessel-density
#5
Lu Zhang, Fei Zheng, Zhigang Peng, Zijing Hu, Zhi Yang
Background: Cancer stem cell (CSC) promotes angiogenesis which plays an important role in tumor occurrence, growth, and metastasis. Accurately, quantifying the tumor vasculature can help understanding CSC characteristics and improve cancer diagnosis, therapy planning, and evaluation. The objective of this study is to present a method for improved angiogenesis assessment. Methods: We proposed a three-dimensional microvessel density (3D MVD) to evaluate tumor angiogenesis and tested it in animal models...
2018: Stem Cells International
https://www.readbyqxmd.com/read/29764149/vacuum-ultraviolet-photoionization-cross-section-of-the-hydroxyl-radical
#6
Leah G Dodson, John D Savee, Samer Gozem, Linhan Shen, Anna I Krylov, Craig A Taatjes, David L Osborn, Mitchio Okumura
The absolute photoionization spectrum of the hydroxyl (OH) radical from 12.513 to 14.213 eV was measured by multiplexed photoionization mass spectrometry with time-resolved radical kinetics. Tunable vacuum ultraviolet (VUV) synchrotron radiation was generated at the Advanced Light Source. OH radicals were generated from the reaction of O(1 D) + H2 O in a flow reactor in He at 8 Torr. The initial O(1 D) concentration, where the atom was formed by pulsed laser photolysis of ozone, was determined from the measured depletion of a known concentration of ozone...
May 14, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29762050/dl-3-n-butylphthalide-attenuates-ischemic-reperfusion-injury-by-improving-the-function-of-cerebral-artery-and-circulation
#7
Chuan Qin, Panting Zhou, Liping Wang, Muyassar Mamtilahun, Wanlu Li, Zhijun Zhang, Guo-Yuan Yang, Yongting Wang
Dl-3-N-butylphthalide (NBP) is approved in China for the treatment of ischemic stroke. Previous studies have shown that NBP promotes recovery after stroke via multiple mechanisms. However, the effect of NBP on vascular function and thrombosis remains unclear. Here, we aim to study the effect of NBP on vascular function using a rat model of transient middle cerebral artery occlusion (MCAO) and a state-of-the-art high-resolution synchrotron radiation angiography. Eighty SD rats underwent MCAO surgery. NBP (90 mg/kg) was administrated daily by gavage...
January 1, 2018: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/29761824/impact-of-cardio-synchronous-brain-pulsations-on-monte-carlo-calculated-doses-for-synchrotron-micro-and-mini-beam-radiation-therapy
#8
Francisco Manchado de Sola, Manuel Vilches, Yolanda Prezado, Antonio M Lallena
PURPOSE: To assess the effects of brain movements induced by heartbeat on dose distributions in synchrotron micro- and mini-beam radiaton therapy and to develop a model to help guide decisions and planning for future clinical trials. METHODS: The Monte Carlo code PENELOPE was used to simulate the irradiation of a human head phantom with a variety of micro- and mini-beam arrays, with beams narrower than 100 μm and above 500 μm, respectively, and with radiation fields of 1cm × 2cm and 2cm × 2cm...
May 15, 2018: Medical Physics
https://www.readbyqxmd.com/read/29747666/survival-of-rats-bearing-advanced-intracerebral-f-98-tumors-after-glutathione-depletion-and-microbeam-radiation-therapy-conclusions-from-a-pilot-project
#9
E Schültke, E Bräuer-Krisch, H Blattmann, H Requardt, J A Laissue, G Hildebrandt
BACKGROUND: Resistance to radiotherapy is frequently encountered in patients with glioblastoma multiforme. It is caused at least partially by the high glutathione content in the tumour tissue. Therefore, the administration of the glutathione synthesis inhibitor Buthionine-SR-Sulfoximine (BSO) should increase survival time. METHODS: BSO was tested in combination with an experimental synchrotron-based treatment, microbeam radiation therapy (MRT), characterized by spatially and periodically alternating microscopic dose distribution...
May 10, 2018: Radiation Oncology
https://www.readbyqxmd.com/read/29743480/femtosecond-x-ray-coherent-diffraction-of-aligned-amyloid-fibrils-on-low-background-graphene
#10
Carolin Seuring, Kartik Ayyer, Eleftheria Filippaki, Miriam Barthelmess, Jean-Nicolas Longchamp, Philippe Ringler, Tommaso Pardini, David H Wojtas, Matthew A Coleman, Katerina Dörner, Silje Fuglerud, Greger Hammarin, Birgit Habenstein, Annette E Langkilde, Antoine Loquet, Alke Meents, Roland Riek, Henning Stahlberg, Sébastien Boutet, Mark S Hunter, Jason Koglin, Mengning Liang, Helen M Ginn, Rick P Millane, Matthias Frank, Anton Barty, Henry N Chapman
Here we present a new approach to diffraction imaging of amyloid fibrils, combining a free-standing graphene support and single nanofocused X-ray pulses of femtosecond duration from an X-ray free-electron laser. Due to the very low background scattering from the graphene support and mutual alignment of filaments, diffraction from tobacco mosaic virus (TMV) filaments and amyloid protofibrils is obtained to 2.7 Å and 2.4 Å resolution in single diffraction patterns, respectively. Some TMV diffraction patterns exhibit asymmetry that indicates the presence of a limited number of axial rotations in the XFEL focus...
May 9, 2018: Nature Communications
https://www.readbyqxmd.com/read/29741895/structure-dependent-dissociation-of-water-on-cobalt-oxide
#11
Matthias Schwarz, Firas Faisal, Susanne Mohr, Chantal Hohner, Kristin Werner, Tao Xu, Tomáš Skála, Nataliya Tsud, Kevin Charles Prince, Vladimír Matolín, Yaroslava Lykhach, Jörg Libuda
Understanding the correlation between structure and reactivity of oxide surfaces is vital for the rational design of catalytic materials. In this work, we demonstrate the exceptional degree of structure sensitivity of the water dissociation reaction for one of the most important materials in catalysis and electrocatalysis. We have studied H2 O on two atomically-defined cobalt oxide surfaces, CoO(100) and Co3 O4 (111). Both surfaces are terminated by O2- and Co2+ in different coordination. By infrared reflection absorption spectroscopy and synchrotron radiation photoelectron spectroscopy we show that H2 O adsorbs molecularly on CoO(100), while it dissociates and forms very strongly bound OH and partially dissociated (H2 O)n (OH)m clusters on Co3 O4 (111)...
May 9, 2018: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29740671/synchrotron-and-focal-plane-array-based-fourier-transform-infrared-spectroscopy-differentiates-the-basalis-and-functionalis-epithelial-endometrial-regions-and-identifies-putative-stem-cell-regions-of-human-endometrial-glands
#12
Georgios Theophilou, Camilo L M Morais, Diane E Halliwell, Kássio M G Lima, Josephine Drury, Pierre L Martin-Hirsch, Helen F Stringfellow, Dharani K Hapangama, Francis L Martin
The cyclical process of regeneration of the endometrium suggests that it may contain a cell population that can provide daughter cells with high proliferative potential. These cell lineages are clinically significant as they may represent clonogenic cells that may also be involved in tumourigenesis as well as endometriotic lesion development. To determine whether the putative stem cell location within human uterine tissue can be derived using vibrational spectroscopy techniques, normal endometrial tissue was interrogated by two spectroscopic techniques...
May 9, 2018: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/29739941/in-situ-coherent-diffractive-imaging
#13
Yuan Hung Lo, Lingrong Zhao, Marcus Gallagher-Jones, Arjun Rana, Jared J Lodico, Weikun Xiao, B C Regan, Jianwei Miao
Coherent diffractive imaging (CDI) has been widely applied in the physical and biological sciences using synchrotron radiation, X-ray free-electron laser, high harmonic generation, electrons, and optical lasers. One of CDI's important applications is to probe dynamic phenomena with high spatiotemporal resolution. Here, we report the development of a general in situ CDI method for real-time imaging of dynamic processes in solution. By introducing a time-invariant overlapping region as real-space constraint, we simultaneously reconstructed a time series of complex exit wave of dynamic processes with robust and fast convergence...
May 8, 2018: Nature Communications
https://www.readbyqxmd.com/read/29739226/role-of-ultrafast-dissociation-in-the-fragmentation-of-chlorinated-methanes
#14
E Kokkonen, K Jänkälä, M Patanen, W Cao, M Hrast, K Bučar, M Žitnik, M Huttula
Photon-induced fragmentation of a full set of chlorinated methanes (CH3 Cl, CH2 Cl2 , CHCl3 , CCl4 ) has been investigated both experimentally and computationally. Using synchrotron radiation and electron-ion coincidence measurements, the dissociation processes were studied after chlorine 2p electron excitation. Experimental evidence for CH3 Cl and CH2 Cl2 contains unique features suggesting that fast dissociation processes take place. By contrast, CHCl3 and CCl4 molecules do not contain the same features, hinting that they experience alternative mechanisms for dissociation and charge migration...
May 7, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29720314/photoelectron-photoion-coincidence-spectroscopy-to-unveil-reaction-mechanisms-by-isomer-selective-detection-of-elusive-molecules-from-combustion-to-catalysis
#15
Patrick Hemberger, Andras Bodi
Elusive and reactive intermediates, such as radicals, play a central role in reaction mechanisms. Photoelectron photoion coincidence spectroscopy with tunable vacuum ultraviolet synchrotron radiation offers a multiplexed, sensitive, mass- and isomer-selective way to identify and, in some cases, determine mole fractions of reactive species. It thus helps to unveil the missing link(s) between reactants and products. After a brief overview of the technique, we review two systems in three different reactive environments...
April 25, 2018: Chimia
https://www.readbyqxmd.com/read/29716383/invited-article-refined-analysis-of-synchrotron-radiation-for-nist-s-surf-iii-facility
#16
Eric L Shirley, Mitchell Furst, Uwe Arp
We have developed a new method for the exact calculation of synchrotron radiation for the National Institute of Standards and Technology Synchrotron Ultraviolet Radiation Facility, SURF III. Instead of using the Schwinger formula, which is only an approximation, we develop formulae based on Graf's addition theorem for Bessel functions and accurate asymptotic expansions for Hankel functions and Bessel functions. By measuring the radiation intensity profile at two distances from the storage ring, we also confirm an apparent vertical emittance that is consistent with the vertical betatron oscillations that are intentionally introduced to extend beam lifetime by spreading the electron beam spatially...
April 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29716312/design-study-of-an-ybco-coated-beam-screen-for-the-super-proton-proton-collider-bending-magnets
#17
Pingping Gan, Kun Zhu, Qi Fu, Haipeng Li, Yuanrong Lu, Matt Easton, Yudong Liu, Jingyu Tang, Qingjin Xu
In order to reduce the beam impedance and refrigeration power dramatically, we have designed a high temperature superconductor (HTS) coated beam screen to screen the cold chamber walls of the super proton-proton collider bending magnets from beam-induced heat loads. It employs an absorber, inspired by the future circular collider studies, to absorb the immense synchrotron radiation power of 12.8 W/m emitted from the 37.5 TeV proton beams. Such a structure has the advantage of decreasing the electron cloud effect and improving the beam vacuum...
April 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29716210/photoionization-mass-spectrometry-of-%C3%AF-phenylalkylamines-role-of-radical-cation-%C3%AF-interaction
#18
Davide Corinti, Daniele Catone, Stefano Turchini, Flaminia Rondino, Maria Elisa Crestoni, Simonetta Fornarini
Linear ω-phenylalkylamines of increasing alkyl chain length have been investigated employing synchrotron radiation in the photon energy range from 7 to 15 eV. These molecules have received considerable interest because they bear the skeleton of biologically relevant compounds including neurotransmitters and because of the possible interaction between the amino moiety and the phenyl ring. Recently, the contribution of this interaction has been assayed in both neutral and protonated species, pointing to a role of the polymethylene chain length...
April 28, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29714198/x-ray-beam-position-feedback-system-with-easy-to-use-beam-position-monitor
#19
Jae Yeon Park, Yesul Kim, Sangsul Lee, Jun Lim
X-ray beam-position stability is indispensable in cutting-edge experiments using synchrotron radiation. Here, for the first time, a beam-position feedback system is presented that utilizes an easy-to-use X-ray beam-position monitor incorporating a diamond-fluorescence screen. The acceptable range of the monitor is above 500 µm and the feedback system maintains the beam position within 3 µm. In addition to being inexpensive, the system has two key advantages: it works without a scale factor for position calibration, and it has no dependence on X-ray energy, X-ray intensity, beam size or beam shape...
May 1, 2018: Journal of Synchrotron Radiation
https://www.readbyqxmd.com/read/29714197/synchrotron-radiation-external-beam-rotational-radiotherapy-of-breast-cancer-proof-of-principle
#20
Francesca Di Lillo, Giovanni Mettivier, Roberta Castriconi, Antonio Sarno, Andrew W Stevenson, Chris J Hall, Daniel Häusermann, Paolo Russo
The principle of rotational summation of the absorbed dose for breast cancer treatment with orthovoltage X-ray beams was proposed by J. Boone in 2012. Here, use of X-ray synchrotron radiation for image guided external beam rotational radiotherapy treatment of breast cancer is proposed. Tumor irradiation occurs with the patient in the prone position hosted on a rotating bed, with her breast hanging from a hole in the bed, which rotates around a vertical axis passing through the tumor site. Horizontal collimation of the X-ray beam provides for whole breast or partial breast irradiation, while vertical translation of the bed and successive rotations allow for irradiation of the full tumor volume, with dose rates which permit also hypofractionated treatments...
May 1, 2018: Journal of Synchrotron Radiation
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