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Toshiro Oda, Tomoki Aihara, Katsuzo Wakabayashi
Nucleators generating new F-actin filaments play important roles in cell activities. Detailed information concerning the events involved in nucleation of actin alone in vitro is fundamental to understanding these processes, but such information has been hard to come by. We addressed the early process of salt-induced polymerization of actin using the time-resolved synchrotron small-angle X-ray scattering (SAXS). Actin molecules in low salt solution maintain a monomeric state by an electrostatic repulsive force between molecules...
October 24, 2016: Scientific Reports
A D Surowka, M Töpperwien, M Bernhardt, J D Nicolas, M Osterhoff, T Salditt, D Adamek, M Szczerbowska-Boruchowska
Human dopaminergic system in general, and substantia nigra (SN) neurons, in particular, are implicated in the pathologies underlying the human brain aging. The interplay between aberrations in the structural organization and elemental composition of SN neuron bodies has recently gained in importance as selected metals: Fe, Cu, Zn, Ca were found to trigger oxidative-stress-mediated aberration in their molecular assembly due to concomitant protein (alpha-synuclein, tau-protein) aggregation, gliosis and finally oxidative stress...
December 1, 2016: Talanta
Alexandra R McNeill, Adam R Hyndman, Roger J Reeves, Alison J Downard, Martin Ward Allen
ZnO is a prime candidate for future use in transparent electronics however development of practical materials requires attention to factors including control of its unusual surface band bending and surface reactivity. In this work, we have modified the O polar (000(1)over bar), Zn-polar (0001), and m-plane (10(1)over bar0) surfaces of ZnO with phosphonic acid (PA) derivatives and measured the effect on the surface band bending and surface sensitivity to atmospheric oxygen. Core level and valence band synchrotron X-ray photoemission spectroscopy were used to measure the surface band bending introduced by PA modifiers with substituents of opposite polarity dipole moment: octadecylphosphonic acid (ODPA) and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctylphosphonic acid (F13OPA)...
October 21, 2016: ACS Applied Materials & Interfaces
Shashidhara Marathe, Xianbo Shi, Michael J Wojcik, Albert T Macrander, Lahsen Assoufid
A procedure for a technique to measure the transverse coherence of synchrotron radiation X-ray sources using a single phase grating interferometer is reported. The measurements were demonstrated at the 1-BM bending magnet beamline of the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). By using a 2-D checkerboard π/2 phase-shift grating, transverse coherence lengths were obtained along the vertical and horizontal directions as well as along the 45° and 135° directions to the horizontal direction...
October 11, 2016: Journal of Visualized Experiments: JoVE
P S Whitfield, N Herron, W E Guise, K Page, Y Q Cheng, I Milas, M K Crawford
We have examined the crystal structures and structural phase transitions of the deuterated, partially deuterated and hydrogenous organic-inorganic hybrid perovskite methyl ammonium lead iodide (MAPbI3) using time-of-flight neutron and synchrotron X-ray powder diffraction. Near 330 K the high temperature cubic phases transformed to a body-centered tetragonal phase. The variation of the order parameter Q for this transition scaled with temperature T as Q ∼ (Tc-T)(β), where Tc is the critical temperature and the exponent β was close to ¼, as predicted for a tricritical phase transition...
October 21, 2016: Scientific Reports
Alessandra Souza Barbosa, Filipe Ferreira da Silva, Andre Rebelo, Søren Vrønning Hoffmann, Marcio H F Bettega, Paulo Limao-Vieira
Here we report novel comprehensive investigations on the electronic state spectroscopies of isolated 2,4- and 2,6-difluorotoluene in the gas phase by high-resolution vacuum ultraviolet (VUV) photoabsorption measurements in the 4.4-10.8 eV energy-range, with absolute cross-section values derived. We also present the first set of ab initio calculations (vertical energies and oscillator strengths), which we have used in the assignment of valence transitions of the difluorotoluene molecules, together with calculated ionisation energies to obtain the Rydberg transitions for both molecules...
October 21, 2016: Journal of Physical Chemistry. A
Sebastien F Barre, David Haberthür, Tiziana P Cremona, Marco Stampanoni, Johannes C Schittny
The pulmonary airways are subdivided into conducting and gas-exchanging airways. The small tree of gas-exchanging airways which is fed by the most distal conducting airway represents an acinus. Very little is known about the development of the number of acini. The goal of this study was to estimate their number throughout rat postnatal development. Right middle rat lung lobes were obtained at postnatal day 4-60, stained with heavy metals, paraffin embedded, and scanned by synchrotron radiation based X-ray tomographic microscopy or imaged using micro computed tomography after critical point drying...
October 19, 2016: American Journal of Physiology. Lung Cellular and Molecular Physiology
Petra Edlund, Heikki Takala, Elin Claesson, Léocadie Henry, Robert Dods, Heli Lehtivuori, Matthijs Panman, Kanupriya Pande, Thomas White, Takanori Nakane, Oskar Berntsson, Emil Gustavsson, Petra Båth, Vaibhav Modi, Shatabdi Roy-Chowdhury, James Zook, Peter Berntsen, Suraj Pandey, Ishwor Poudyal, Jason Tenboer, Christopher Kupitz, Anton Barty, Petra Fromme, Jake D Koralek, Tomoyuki Tanaka, John Spence, Mengning Liang, Mark S Hunter, Sebastien Boutet, Eriko Nango, Keith Moffat, Gerrit Groenhof, Janne Ihalainen, Emina A Stojković, Marius Schmidt, Sebastian Westenhoff
Phytochromes are a family of photoreceptors that control light responses of plants, fungi and bacteria. A sequence of structural changes, which is not yet fully understood, leads to activation of an output domain. Time-resolved serial femtosecond crystallography (SFX) can potentially shine light on these conformational changes. Here we report the room temperature crystal structure of the chromophore-binding domains of the Deinococcus radiodurans phytochrome at 2.1 Å resolution. The structure was obtained by serial femtosecond X-ray crystallography from microcrystals at an X-ray free electron laser...
October 19, 2016: Scientific Reports
Rabi Chhantyal-Pun, Oliver Welz, John David Savee, Arkke J Eskola, Edmond P F Lee, Lucy Blacker, Henry R Hill, Matilda Ashcroft, M Anwar H H Khan, Guy C Lloyd-Jones, Louise A Evans, Brandon Rotavera, Haifeng Huang, David L Osborn, Daniel K W Mok, John M Dyke, Dudley E Shallcross, Carl John Percival, Andrew J Orr-Ewing, Craig Allen Taatjes
The Criegee intermediate acetone oxide, (CH3)2COO, is formed by laser photolysis of 2,2-diiodopropane in the presence of O2 and characterized by synchrotron photoionization mass spectrometry and by cavity ringdown ultraviolet absorption spectroscopy. The rate coefficient of the reaction of the Criegee intermediate with SO2 was measured using photoionization mass spectrometry and pseudo-first order methods to be (7.3 ± 0.5) × 10 11 cm3 s 1 at 298 K and 4 Torr and (1.5 ± 0.5) × 10 10 cm3 s 1 at 298 K and 10 Torr (He buffer)...
October 18, 2016: Journal of Physical Chemistry. A
Do Young Noh, Chan Kim, Yoonhee Kim, Changyong Song
Achieving a resolution near 1 nm is a critical issue in coherent x-ray diffraction imaging (CDI) for applications in materials and biology. Albeit with various advantages of CDI based on synchrotrons and newly developed x-ray free electron lasers, its applications would be limited without improving resolution well below 10 nm. Here, we review the issues and efforts in improving CDI resolution including various methods for resolution determination. Enhancing diffraction signal at large diffraction angles, with the aid of interference between neighboring strong scatterers or templates, is reviewed and discussed in terms of increasing signal-to-noise ratio...
October 18, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Anders Sandell, Davide Ragazzon, Andreas Schaefer, Mari Helene Farstad, Anne Borg
We present a dedicated synchrotron radiation photoelectron spectroscopy (SR-PES) study of a photochemical reaction on the surface of rutile TiO2(110). The photoreaction kinetics of carboxylate species (trimethyl acetate, TMA) upon irradiation by UV and soft x-rays were monitored and we show that it is possible to control the reaction rates from UV light and soft x-rays independently. We directly observe Ti4+ → Ti3+ conversion upon irradiation, attributed to electron trapping at Ti sites close to surface OH groups formed by deprotonation of the parent molecule, trimethyl acetic acid (TMAA)...
October 18, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Thrinathreddy Ramireddy, Neeraj Sharma, Tan Xing, Ying Chen, Jeremie Leforestier, Alexey M Glushenkov
Sodium-ion batteries are in the spotlight as viable alternatives to lithium-ion batteries in stationary storage and power grid applications. Among possible anode materials, Sb is one of the interesting candidates due to a combination of battery-type potential plateaus in the charge-discharge profiles, high capacity (theoretical capacity of 660 mAh g(-1)) and demonstrated good cyclic stability. The influence of Sb particle size (particularly at the nanoscale range) and the composition of Sb-carbon composites on the electrode performance, stability and charge storage mechanism is systematically evaluated here for the first time...
October 18, 2016: ACS Applied Materials & Interfaces
Kristian J Tangso, Paulo Henrique C D da Cunha, Patrick T Spicer, Jian Li, Ben J Boyd
Infections arising in hospitalized patients, particularly those who have undergone surgery and are reliant on receiving treatment through biomedical devices, continue to be a rising concern. It is well known that aqueous mixtures of oppositely charged surfactant and polymer molecules can self-assemble to form liquid crystalline structures primarily via electrostatically-driven interactions which have demonstrated great potential as tailored release nanomaterials. Colistin is a re-emerging antibiotic used against multidrug-resistant Gram negative bacteria...
October 17, 2016: ACS Applied Materials & Interfaces
Donglei Chen, Henning Blom, Sophie Sanchez, Paul Tafforeau, Per E Ahlberg
The teeth of gnathostomes (jawed vertebrates) show rigidly patterned, unidirectional replacement that may or may not be associated with a shedding mechanism. These mechanisms, which are critical for the maintenance of the dentition, are incongruently distributed among extant gnathostomes. Although a permanent tooth-generating dental lamina is present in all chondrichthyans, many tetrapods and some teleosts, it is absent in the non-teleost actinopterygians. Tooth-shedding by basal hard tissue resorption occurs in most osteichthyans (including tetrapods) but not in chondrichthyans...
October 17, 2016: Nature
Chris Jeynes, Julien L Colaux
The analysis of thin films is of central importance for functional materials, including the very large and active field of nanomaterials. Quantitative elemental depth profiling is basic to analysis, and many techniques exist, but all have limitations and quantitation is always an issue. We here review recent significant advances in ion beam analysis (IBA) which now merit it a standard place in the analyst's toolbox. Rutherford backscattering spectrometry (RBS) has been in use for half a century to obtain elemental depth profiles non-destructively from the first fraction of a micron from the surface of materials: more generally, "IBA" refers to the cluster of methods including elastic scattering (RBS; elastic recoil detection, ERD; and non-Rutherford elastic backscattering, EBS), nuclear reaction analysis (NRA: including particle-induced gamma-ray emission, PIGE), and also particle-induced X-ray emission (PIXE)...
October 17, 2016: Analyst
Dohyun Moon, Jong-Ha Choi
In the asymmetric unit of the title compound, [CrCl2(C10H24N4)][Cr(C2O4)(C10H24N4)](ClO4)2 (C10H24N4 = 1,4,8,11-tetra-aza-cyclo-tetra-decane, cyclam; C2O4 = oxalate, ox), there are two independent halves of the [CrCl2(cyclam)](+) and [Cr(ox)(cyclam)](+) cations, and one perchlorate anion. In the complex cations, which are completed by application of twofold rotation symmetry, the Cr(III) ions are coordinated by the four N atoms of a cyclam ligand, and by two chloride ions or one oxalate bidentate ligand in a cis arrangement, displaying an overall distorted octa-hedral coordination environment...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
Jong Won Shin, Dong Won Lee, Dae-Woong Kim, Dohyun Moon
The title compound, [CuCl2(C10H16N2O)], has been synthesized and characterized by synchrotron single-crystal X-ray diffraction and FT-IR spectroscopy. The 2-methyl-2-[(pyridin-2-ylmeth-yl)amino]-propan-1-ol (mpmapOH) ligand, including pyridine, amine and hy-droxy groups, was synthesized by the reaction of 2-amino-2-methyl-propan-1-ol with pyridine-2-carbaldehyde and was characterized by NMR spectroscopy. In its Cu(II) complex, the metal ion has a distorted square-pyramidal coordination geometry with two N and one O atom of the mpmapOH ligand and one chloride anion in the equatorial plane, and the second chloride in an axial position...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
Lorenzo Massimi, Michela Fratini, Inna Bukreeva, Francesco Brun, Alberto Mittone, Gaetano Campi, Raffaele Spanò, Milena Mastrogiacomo, Nicole Kerlero de Rosbo, Alberto Bravin, Antonio Uccelli, Alessia Cedola
High resolution Synchrotron-based X-ray Phase Contrast Tomography (XPCT) allows the simultaneous detection of three dimensional neuronal and vascular networks without using contrast agents or invasive casting preparation. We show and discuss the different features observed in reconstructed XPCT volumes of the ex vivo mouse spinal cord in the lumbo-sacral region, including motor neurons and blood vessels. We report the application of an intensity-based segmentation method to detect and quantitatively characterize the modification in the vascular networks in terms of reduction in experimental visibility...
October 12, 2016: Physica Medica: PM
Thomas Walker, Christos Michaelides, Antigoni Ekonomou, Kalotina Geraki, Harold G Parkes, Maria Suessmilch, Amy H Herlihy, William R Crum, Po-Wah So
Despite regulation, brain iron increases with aging and may enhance aging processes including neuroinflammation. Increases in magnetic resonance imaging transverse relaxation rates, R2 and R2*, in the brain have been observed during aging. We show R2 and R2* correlate well with iron content via direct correlation to semi-quantitative synchrotron-based X-ray fluorescence iron mapping, with age-associated R2 and R2* increases reflecting iron accumulation. Iron accumulation was concomitant with increased ferritin immunoreactivity in basal ganglia regions except in the substantia nigra (SN)...
October 12, 2016: Aging
Karin Kornmueller, Bernhard Lehofer, Claudia Meindl, Eleonore Fröhlich, Gerd Leitinger, Heinz Amenitsch, Ruth Prassl
Self-assembling amphiphilic designer peptides have been successfully applied as nanomaterials in biomedical applications. Understanding molecular interactions at the peptide-membrane interface is crucial, since interactions at this site often determine (in)compatibility. The present study aims to elucidate how model membrane systems of different complexity (in particular single-component phospholipid bilayers and lipoproteins) respond to the presence of amphiphilic designer peptides. We focused on two short anionic peptides, V₄WD₂ and A₆YD, which are structurally similar, but showed a different self-assembly behavior...
October 14, 2016: Biomacromolecules
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