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synchrotron radiation

Kai Schlage, Liudmila Dzemiantsova, Lars Bocklage, Hans-Christian Wille, Matthias Pues, Guido Meier, Ralf Röhlsberger
Nuclear resonant x-ray diffraction in grazing incidence geometry is used to determine the lateral magnetic configuration in a one-dimensional lattice of ferromagnetic nanostripes. During magnetic reversal, strong nuclear superstructure diffraction peaks appear in addition to the electronic ones due to an antiferromagnetic order in the nanostripe lattice. We show that the analysis of the angular distribution together with the time dependence of the resonantly diffracted x rays reveals surface spin structures with very high sensitivity...
June 9, 2017: Physical Review Letters
David Ayuso, Alicia Palacios, Piero Decleva, Fernando Martín
The combination of attosecond pump-probe techniques with mass spectrometry methods has recently led to the first experimental demonstration of ultrafast charge dynamics in a biomolecule, the amino acid phenylalanine [Calegari et al., Science, 2014, 346, 336]. Using an extension of the static-exchange density functional theory (DFT) method, the observed dynamics was explained as resulting from the coherent superposition of ionic states produced by the broadband attosecond pulse. Here, we have used the static-exchange DFT method to investigate charge migration induced by attosecond pulses in the glycine molecule...
June 20, 2017: Physical Chemistry Chemical Physics: PCCP
Jiangtao Zhao, Mei Liu, Li Fang, Shenlong Jiang, Jingtian Zhou, Huaiyi Ding, Hongwen Huang, Wen Wen, Zhenlin Luo, Qun Zhang, Xiaoping Wang, Chen Gao
Understanding the big discrepancy in the photoluminesence quantum yields (PLQYs) of nanoscale colloidal materials with varied morphologies is of great significance to its property optimization and functional application. Using different shaped CsPbBr3 nanocrystals with the same fabrication processes as model, quantitative synchrotron radiation X-ray diffraction analysis reveals the increasing trend in lattice strain values of the nanocrystals: nanocube, nanoplate, nanowire. Furthermore, transient spectroscopic measurements reveal the same trend in the defect quantities of these nanocrystals...
June 22, 2017: Journal of Physical Chemistry Letters
W C Stolte, A C F Santos, G G B de Souza, M M Sant'Anna, K T Leung
The fragmentation of the tetrachloromethane molecule following core-shell photoexcitation and photoionization in the neighborhood of the chlorine K-edge has been studied by using time-of-flight mass spectroscopy and monochromatic synchrotron radiation. Branching ratios for ionic dissociation were derived for all the detected ions, which are informative of the decay dynamics and photofragmentation patterns of the core-excited species. In addition, the absorption yield has been measured with a new assignment of the spectral features...
June 7, 2017: Journal of Chemical Physics
Robert W Koch, Mai Elfarnawany, Ning Zhu, Hanif M Ladak, Sumit K Agrawal
HYPOTHESIS: Evaluation of cochlear duct length (CDL) using novel imaging techniques will help improve the accuracy of existing CDL equations. BACKGROUND: Various relationships relating A value measured from a patient's computed tomography scan and CDL have been proposed to aid in preoperative electrode selection and frequency mapping. METHODS: Ten cadaveric temporal bones were scanned using synchrotron radiation phase-contrast imaging. Reference CDL values were calculated by placing points representing the organ of Corti (OC), lateral wall (LW), and electrode location (I) on the synchrotron radiation phase-contrast imaging slices along the length of the cochlea...
July 2017: Otology & Neurotology
Zhen Zhang, Changsong Hou, Dexing Lian, Zhongjian Ma, Junquan Tao, Weiguo Zhu
Some therapeutic proton synchrotron accelerators will be built for cancer treatment in China. The radiation produced by proton must be carefully evaluated and shielded for occupational disease hazard assessment and environmental impact assessment. Adopting the FLUKA code, a therapeutic room model, a synchrotron hall model and a high energy transport line tunnel model are constructed to get the ambient dose equivalent rate distributions. The ambient dose equivalent rates are also calculated with an empirical formula in some regions...
June 7, 2017: Radiation Protection Dosimetry
Bjarne R S Hansen, Nikolay Tumanov, Antonio Santoru, Claudio Pistidda, Jozef Bednarcik, Thomas Klassen, Martin Dornheim, Yaroslav Filinchuk, Torben R Jensen
A series of ammine metal-dodecahydro-closo-dodecaboranes, MxB12H12·nNH3 (M = Li, Na, Ca) were synthesized and their structural and thermal properties studied with in situ time-resolved synchrotron radiation powder X-ray diffraction, thermal analysis, Fourier transformed infrared spectroscopy, and temperature-programmed photographic analysis. The synthesized compounds, Li2B12H12·7NH3, Na2B12H12·4NH3 and CaB12H12·6NH3, contain high amounts of NH3, 43.3, 26.6 and 35.9 wt% NH3, respectively, which can be released and absorbed reversibly at moderate conditions without decomposition, thereby making the closo-boranes favorable 'host' materials for ammonia or indirect hydrogen storage in the solid state...
June 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Alessandra Giuliani, Giovanna Iezzi, Serena Mazzoni, Adriano Piattelli, Vittoria Perrotti, Antonio Barone
OBJECTIVES: Recently, it has been reported that heterologous biomaterials, where the collagen matrix is preserved, seem to facilitate blood clotting and the subsequent invasion of repairing and regenerative cells. This study aimed at evaluating the healing of human extraction sockets grafted with a collagenated cortico-cancellous porcine bone (mp3®, OsteoBiol®, Tecnoss®, Giaveno, Italy) by synchrotron radiation X-ray microtomography (microCT) and histology in order to have a 3D quantitative characterization over time...
June 2, 2017: Clinical Oral Investigations
Isaac Rodríguez-Ruiz, Dimitri Radajewski, Sophie Charton, Nhat Phamvan, Martha Brennich, Petra Pernot, Françoise Bonneté, Sébastien Teychené
The relevance of coupling droplet-based Photonic Lab-on-a-Chip (PhLoC) platforms and Small-Angle X-Ray Scattering (SAXS) technique is here highlighted for the performance of high throughput investigations, related to the study of protein macromolecular interactions. With this configuration, minute amounts of sample are required to obtain reliable statistical data. The PhLoC platforms presented in this work are designed to allow and control an effective mixing of precise amounts of proteins, crystallization reagents and buffer in nanoliter volumes, and the subsequent generation of nanodroplets by means of a two-phase flow...
June 2, 2017: Sensors
Elspeth F Garman, Martin Weik
Radiation damage inflicted on macromolecular crystals during X-ray diffraction experiments remains a limiting factor for structure solution, even when samples are cooled to cryotemperatures (~100 K). Efforts to establish mitigation strategies are ongoing and various approaches, summarized below, have been investigated over the last 15 years, resulting in a deeper understanding of the physical and chemical factors affecting damage rates. The recent advent of X-ray free electron lasers permits "diffraction-before-destruction" by providing highly brilliant and short (a few tens of fs) X-ray pulses...
2017: Methods in Molecular Biology
Ruslan Sanishvili, Robert F Fischetti
Micro-diffraction tools for macromolecular crystallography, first developed at the end of 1990s and now an integral part of many synchrotron beamlines, enable some of the experiments which were not feasible just a decade or so ago. These include data collection from very small samples, just a few micrometers in size; from larger, but severely inhomogeneous samples; and from samples which are optically invisible. Improved micro-diffraction tools led to improved signal-to-noise ratio, to mitigation of radiation damage in some cases, and to better-designed diffraction experiments...
2017: Methods in Molecular Biology
Joanna L Denbigh, David Perez-Guaita, Robbin R Vernooij, Mark J Tobin, Keith R Bambery, Yun Xu, Andrew D Southam, Farhat L Khanim, Mark T Drayson, Nicholas P Lockyer, Royston Goodacre, Bayden R Wood
Acute myeloid leukaemia (AML) is a life threatening cancer for which there is an urgent clinical need for novel therapeutic approaches. A redeployed drug combination of bezafibrate and medroxyprogesterone acetate (BaP) has shown anti-leukaemic activity in vitro and in vivo. Elucidation of the BaP mechanism of action is required in order to understand how to maximise the clinical benefit. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Synchrotron radiation FTIR (S-FTIR) and Raman microspectroscopy are powerful complementary techniques which were employed to probe the biochemical composition of two AML cell lines in the presence and absence of BaP...
June 1, 2017: Scientific Reports
Gerbaix Maude, Gnyubkin Vasily, Farlay Delphine, Olivier Cécile, Ammann Patrick, Courbon Guillaume, Laroche Norbert, Gential Rachel, Follet Hélène, Peyrin Françoise, Shenkman Boris, Gauquelin-Koch Guillemette, Vico Laurence
The weightless environment during spaceflight induces site-specific bone loss. The 30-day Bion-M1 mission offered a unique opportunity to characterize the skeletal changes after spaceflight and an 8-day recovery period in mature male C57/BL6 mice. In the femur metaphysis, spaceflight decreased the trabecular bone volume (-64% vs. Habitat Control), dramatically increased the bone resorption (+140% vs. Habitat Control) and induced marrow adiposity invasion. At the diaphysis, cortical thinning associated with periosteal resorption was observed...
June 1, 2017: Scientific Reports
John R Helliwell
Since the Protein Data Bank was founded in 1971 there are now over 120,000 depositions, the majority of which are from X-ray crystallography and 90% of those made use of synchrotron beamlines. At the Cambridge Structure Database, founded in 1965, there are more than 800,000 'small molecule' crystal structure depositions, and a very large number of those are relevant in the biosciences as ligands or cofactors. The technology for crystal structure analysis is still developing rapidly both at synchrotrons and in home labs...
June 1, 2017: Bioscience Reports
W B Doriese, P Abbamonte, B K Alpert, D A Bennett, E V Denison, Y Fang, D A Fischer, C P Fitzgerald, J W Fowler, J D Gard, J P Hays-Wehle, G C Hilton, C Jaye, J L McChesney, L Miaja-Avila, K M Morgan, Y I Joe, G C O'Neil, C D Reintsema, F Rodolakis, D R Schmidt, H Tatsuno, J Uhlig, L R Vale, J N Ullom, D S Swetz
We describe a series of microcalorimeter X-ray spectrometers designed for a broad suite of measurement applications. The chief advantage of this type of spectrometer is that it can be orders of magnitude more efficient at collecting X-rays than more traditional high-resolution spectrometers that rely on wavelength-dispersive techniques. This advantage is most useful in applications that are traditionally photon-starved and/or involve radiation-sensitive samples. Each energy-dispersive spectrometer is built around an array of several hundred transition-edge sensors (TESs)...
May 2017: Review of Scientific Instruments
Tim Hartman, Ralf Wehlitz
We have studied the double-photoionization process of tropone (C7H6O) and cyclooctatetraene (C8H8) as a function of photon energy using monochromatized synchrotron radiation between 18 and 270 eV. We compare our results with previously published data for partially deuterated benzene (C6H3D3), which exhibits three distinct features in the ratio of doubly to singly charged parent ions, whereas pyrrole (C4H4N) exhibits only two of these features. The question that we address in this paper is how molecules with different molecular structures (pentagonal, hexagonal, heptagonal, and octagonal carbon rings) affect the photon-energy dependence of this ratio...
May 28, 2017: Journal of Chemical Physics
Fei Zhang, Yuan Wu, Hongbo Lou, Zhidan Zeng, Vitali B Prakapenka, Eran Greenberg, Yang Ren, Jinyuan Yan, John S Okasinski, Xiongjun Liu, Yong Liu, Qiaoshi Zeng, Zhaoping Lu
Polymorphism, which describes the occurrence of different lattice structures in a crystalline material, is a critical phenomenon in materials science and condensed matter physics. Recently, configuration disorder was compositionally engineered into single lattices, leading to the discovery of high-entropy alloys and high-entropy oxides. For these novel entropy-stabilized forms of crystalline matter with extremely high structural stability, is polymorphism still possible? Here by employing in situ high-pressure synchrotron radiation X-ray diffraction, we reveal a polymorphic transition from face-centred-cubic (fcc) structure to hexagonal-close-packing (hcp) structure in the prototype CoCrFeMnNi high-entropy alloy...
June 1, 2017: Nature Communications
Ugras Kaplan, Samer Amayri, Jakob Drebert, Andre Rossberg, Daniel Grolimund, Tobias Reich
Plutonium plays an important role within nuclear waste materials because of its long half-life and high radiotoxicity. The aim of this study was to investigate with high spatial resolution the reactivity of the more oxidized forms of Pu(V,VI) within Opalinus Clay (OPA) rock, a heterogeneous, natural argillaceous rock considered as potential repository host. A combination of synchrotron based X-ray microprobe and bulk techniques were used to study the spatial distribution and molecular speciation of Pu within OPA after diffusion and sorption processes...
May 30, 2017: Environmental Science & Technology
Jun Liang, Guorong Shan, Pengju Pan
A novel double network (DN) hydrogel with highly enhanced toughness has been prepared using reversible addition-fragmentation transfer (RAFT)-modified poly(2-acrylamide-2-methylpropane sulfonic acid) (PAMPS) as the first network, and polyacrylamide (PAM) as the second network. The mechanical properties of the first-network-modified PAMPS/PAM DN hydrogels have been studied and the new DN hydrogel shows remarkably high fracture energy (3.3 MJ m(-3)) in tensile deformation, which is nearly 9 times larger than that of the unmodified PAMPS/PAM DN hydrogel...
June 7, 2017: Soft Matter
Himal Bhatt, M N Deo
The hydrogen bonded dimeric structure of the model amide based molecular crystal acrylamide has been investigated under pressure using micro-spectroscopy, employing synchrotron infrared radiation up to 24GPa at room temperature. The high pressure spectra indicate systematic evolution of new features above 4GPa, which have been identified to be due to the emergence of a polymeric phase. The polymerization gets completed up to 16.8GPa and the observed changes are found to be irreversible upon the release of pressure...
May 1, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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