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https://www.readbyqxmd.com/read/28098254/nanoscale-measurement-of-trace-element-distributions-in-spartina-alterniflora-root-tissue-during-dormancy
#1
Huan Feng, Yu Qian, J Kirk Cochran, Qingzhi Zhu, Wen Hu, Hanfei Yan, Li Li, Xiaojing Huang, Yong S Chu, Houjun Liu, Shinjae Yoo, Chang-Jun Liu
This paper reports a nanometer-scale investigation of trace element (As, Ca, Cr, Cu, Fe, Mn, Ni, S and Zn) distributions in the root system Spartina alterniflora during dormancy. The sample was collected on a salt marsh island in Jamaica Bay, New York, in April 2015 and the root was cross-sectioned with 10 μm resolution. Synchrotron X-ray nanofluorescence was applied to map the trace element distributions in selected areas of the root epidermis and endodermis. The sampling resolution was 60 nm to increase the measurement accuracy and reduce the uncertainty...
January 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28097742/differential-dehydration-effects-on-globular-proteins-and-intrinsically-disordered-proteins-during-film-formation
#2
Juliana Sakamoto Yoneda, Andew J Miles, Ana Paula Ulian de Araujo, B A Wallace
Globular proteins composed of different secondary structures and fold types were examined by synchrotron radiation circular dichroism spectroscopy to determine the effects of dehydration on their secondary structures. They exhibited only minor changes upon removal of bulk water during film formation, contrary to previously reported studies of proteins dehydrated by lyophilisation (where substantial loss of helical structure and gain in sheet structure was detected). This near lack of conformational change observed for globular proteins contrasts with intrinsically disordered proteins (IDPs) dried in the same manner: the IDPs, which have almost completely unordered structures in solution, exhibited increased amounts of regular (mostly helical) secondary structures when dehydrated, suggesting formation of new intra-protein hydrogen bonds replacing solvent-protein hydrogen bonds, in a process which may mimic interactions that occur when IDPs bind to partner molecules...
January 18, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28096523/x-ray-imaging-of-spin-currents-and-magnetisation-dynamics-at-the-nanoscale
#3
Stefano Bonetti
Understanding how spins move in time and space is the aim of both fundamental and applied research in modern magnetism. Over the past three decades, research in this field has led to technological advances that have had a major impact on our society, while improving the understanding of the fundamentals of spin physics. However, important questions still remain unanswered, because it is experimentally challenging to directly observe spins and their motion with a combined high spatial and temporal resolution...
January 18, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28094926/the-room-temperature-superionic-conductivity-of-silver-iodide-nanoparticles-under-pressure
#4
Takayuki Yamamoto, Mitsuhiko Maesato, Naohisa Hirao, Saori I Kawaguchi, Shogo Kawaguchi, Yasuo Ohishi, Yoshiki Kubota, Hirokazu Kobayashi, Hiroshi Kitagawa
We performed variable-temperature synchrotron powder X-ray diffraction measurements and impedance spectroscopy under pressure for silver iodide (AgI) nanoparticles with a diameter of 11 nm. The superionic conducting α-phase of AgI nanoparticles was successfully stabilized down to at least 20 °C by applying a pressure of 0.18 GPa, whereas the transition temperature was 147 °C in bulk AgI at ambient pressure. To our knowledge, this is the first example of the α-phase of AgI existing stably at room temperature...
January 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28094374/combined-in-and-ex-situ-studies-of-pyrazine-adsorption-into-the-aliphatic-mof-al-cau-13-structures-dynamics-and-correlations
#5
Helge Reinsch, Jannik Benecke, Martin Etter, Niclas Heidenreich, Norbert Stock
The intercalation of different pyrazines (pyrazine, methylpyrazine, 2,5-dimethylpyrazine, 2,3-dimethylpyrazine, trimethylpyrazine and tetramethylpyrazine) into the trans-1,4-cyclohexanedicarboxylate (CDC(2-)) based Al-MOF [Al(OH)(CDC)], denoted as CAU-13, was investigated. The adsorption of the guest molecules into the flexible MOF was carried out from an aqueous solution or via vapour phase adsorption, starting with the hydrated narrow-pore form of the framework [Al(OH)(O2C-C6H10-CO2)]·H2O (CAU-13-np). The obtained host-guest systems were characterised by thermogravimetry and vibrational spectroscopy and their crystal structures were elucidated using powder X-ray diffraction (PXRD) data...
January 17, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28093591/hidden-negative-linear-compressibility-in-lithium-l-tartrate
#6
Hamish H-M Yeung, Rebecca Kilmurray, Claire L Hobday, Scott C McKellar, Anthony K Cheetham, David R Allan, Stephen A Moggach
By decoupling the mechanical behaviour of building units for the first time in a wine-rack framework containing two different strut types, we show that lithium l-tartrate exhibits NLC with a maximum value, Kmax = -21 TPa(-1), and an overall NLC capacity, χNLC = 5.1%, that are comparable to the most exceptional materials to date. Furthermore, the contributions from molecular strut compression and angle opening interplay to give rise to so-called "hidden" negative linear compressibility, in which NLC is absent at ambient pressure, switched on at 2 GPa and sustained up to the limit of our experiment, 5...
January 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28091651/composition-dependent-charge-transfer-and-phase-separation-in-the-v1-xrexo2-solid-solution
#7
D Mikhailova, N N Kuratieva, Y Utsumi, A A Tsirlin, A M Abakumov, M Schmidt, S Oswald, H Fuess, H Ehrenberg
The substitution of vanadium in vanadium dioxide VO2 influences the critical temperatures of structural and metal-to-insulator transitions in different ways depending on the valence of the dopant. Rhenium adopts valence states between +4 and +7 in an octahedral oxygen surrounding and is particularly interesting in this context. Structural investigation of V1-xRexO2 solid solutions (0.01 ≤ x ≤ 0.30) between 80 and 1200 K using synchrotron X-ray powder diffraction revealed only two polymorphs that resemble VO2: the low-temperature monoclinic MoO2-type form (space group P21/c), and the tetragonal rutile-like form (space group P42/mnm)...
January 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28088575/a-study-on-growth-and-pyrolysis-characteristics-of-microalgae-using-thermogravimetric-analysis-infrared-spectroscopy-and-synchrotron-fourier-transform-infrared-spectroscopy
#8
Fanghua Li, Srikanth Chakravartula Srivatsa, Warren Batchelor, Sankar Bhattacharya
This two-part study firstly investigated Tetraselmis suecica grown in different CO2 (0.04-15%v/v) concentration through indoor and outdoor cultivation systems. A high CO2 concentration led to a high lipid content, and low nitrogen and oxygen content, which are desirable for transport fuel production. Pyrolysis characteristics were investigated by TG-IR and synchrotron IR microscopy. The results show Tetraselmis suecica grown in 10%CO2 had the highest decomposition rate corresponding to more volatile products produced during the main thermal cracking stage and derived from protein-and lipid-corresponding functional groups...
January 7, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28087363/membrane-restructuring-following-in-situ-sialidase-digestion-of-gangliosides-complex-model-bilayers-by-synchrotron-radiation-reflectivity
#9
Valeria Rondelli, Paola Brocca, Giovanna Fragneto, Jean Daillant, Cristina Tringali, Laura Cantu', Elena Del Favero
Synchrotron radiation reflectometry was used to access the transverse structure of model membranes under the action of the human sialidase NEU2, down to the Ångström length scale. Model membranes were designed to mimic the lipid composition of so-called Glycosphingolipids Enriched Microdomains (GEMs), which are membrane platforms specifically enriched in cholesterol and sphingolipids, where also typical signalling molecules are hosted. Gangliosides, glycosphingolipids containing one or more sialic acid residues, are asymmetrically embedded in GEMs, in the outer membrane leaflet...
January 10, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28081011/spectrum-reconstruction-method-based-on-the-detector-response-model-calibrated-by-x-ray-fluorescence
#10
Ruizhe Li, Liang Li, Zhiqiang Chen
Accurate estimation of distortion-free spectra is important but difficult in various applications, especially for spectral computed tomography. Two key problems must be solved to reconstruct the incident spectrum. One is the acquisition of the detector energy response. It can be calculated by Monte Carlo simulation, which requires detailed modeling of the detector system and a high computational power. It can also be acquired by establishing a parametric response model and be calibrated using monochromatic x-ray sources, such as synchrotron sources or radioactive isotopes...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28079203/complexation-of-short-ds-rna-dna-oligonucleotides-with-gemini-micelles-a-time-resolved-saxs-and-computational-study
#11
Sara Falsini, Emanuela Di Cola, Martin In, Maria Giordani, Stefano Borocci, Sandra Ristori
Gene therapy is based on nucleic acid delivery to pathogenic cells in order to modulate their gene expression. The most used non viral vectors are lipid-based nanoaggregates, which are safer than viral carriers and have been shown to assemble easily with both DNA and RNA. However, the transfection efficiency of non viral carriers still needs to be improved before intensive practise in clinical trials can be implemented. For this purpose, the in depth characterization of the complexes formed by nucleic acids and their transporters is of great relevance...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28079120/in-situ-imaging-of-microstructure-formation-in-electronic-interconnections
#12
M A A Mohd Salleh, C M Gourlay, J W Xian, S A Belyakov, H Yasuda, S D McDonald, K Nogita
The development of microstructure during melting, reactive wetting and solidification of solder pastes on Cu-plated printed circuit boards has been studied by synchrotron radiography. Using Sn-3.0Ag-0.5Cu/Cu and Sn-0.7Cu/Cu as examples, we show that the interfacial Cu6Sn5 layer is present within 0.05 s of wetting, and explore the kinetics of flux void formation at the interface between the liquid and the Cu6Sn5 layer. Quantification of the nucleation locations and anisotropic growth kinetics of primary Cu6Sn5 crystals reveals a competition between the nucleation of Cu6Sn5 in the liquid versus growth of Cu6Sn5 from the existing Cu6Sn5 layer...
January 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28075578/probing-structural-perturbation-in-a-bent-molecular-crystal-with-synchrotron-infrared-microspectroscopy-and-periodic-density-functional-theory-calculations
#13
Ljupco Pejov, Manas K Panda, Taro Moriwaki, Pance Naumov
The range of unit cell orientations generated at the kink of a bent single crystal poses unsurmountable challenges with diffraction analysis and limits the insight into the molecular-scale mechanism of bending. On a plastically bent crystal of hexachlorobenzene it is demonstrated here that spatially resolved microfocus infrared spectroscopy using synchrotron radiation can be applied in conjunction with periodic density functional theory calculations to predict spectral changes or to extract information on structural changes that occur as a consequence of bending...
January 11, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28074852/initiation-and-growth-kinetics-of-solidification-cracking-during-welding-of-steel
#14
L Aucott, D Huang, H B Dong, S W Wen, J A Marsden, A Rack, A C F Cocks
Solidification cracking is a key phenomenon associated with defect formation during welding. To elucidate the failure mechanisms, solidification cracking during arc welding of steel are investigated in situ with high-speed, high-energy synchrotron X-ray radiography. Damage initiates at relatively low true strain of about 3.1% in the form of micro-cavities at the weld subsurface where peak volumetric strain and triaxiality are localised. The initial micro-cavities, with sizes from 10 × 10(-6) m to 27 × 10(-6 )m, are mostly formed in isolation as revealed by synchrotron X-ray micro-tomography...
January 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28072542/insights-into-the-distinct-lithiation-sodiation-of-porous-cobalt-oxide-by-in-operando-synchrotron-x-ray-techniques-and-ab-initio-molecular-dynamics-simulations
#15
Gui-Liang Xu, Tian Sheng, Lina Chong, Tianyuan Ma, Chengjun Sun, Xiaobing Zuo, Di-Jia Liu, Yang Ren, Xiaoyi Zhang, Yuzi Liu, Steve M Heald, Shi-Gang Sun, Zonghai Chen, Khalil Amine
Sodium-ion batteries (SIBs) have been considered as one of the promising power source candidates for the stationary storage industries owing to the much lower cost of sodium than lithium. It's well known that the electrode materials largely determine the energy density of the battery systems. However, recent discoveries on the electrode materials showed that most of them present distinct lithium and sodium storage performance, which is not yet well understood. In this work, we performed a comparative understanding on the structural changes of porous cobalt oxide during its electrochemical lithiation and sodiation process by in operando synchrotron small angel X-ray scattering, X-ray diffraction and X-ray absorption spectroscopy...
January 10, 2017: Nano Letters
https://www.readbyqxmd.com/read/28071810/deer-leather-analysis-of-the-microstructure-affecting-pebble
#16
Hannah C Wells, Katie Sizeland, Sue M Cooper, Nigel Kirby, Adrian Hawley, Stephen Mudie, Richard G Haverkamp
BACKGROUND: Deer leather has a characteristic pattern, referred to as "pebble", that is accorded such importance that a lack of it renders a leather defective. Synchrotron-based small angle X-ray scattering (SAXS), ultrasonic imaging, scanning electron microscopy, and tear tests are used to investigate the structural characteristics of well pebbled and poorly pebbled cervine leathers. RESULTS: Poorly pebbled leather has a less open structure in the upper grain region than well pebbled leather...
January 10, 2017: Journal of the Science of Food and Agriculture
https://www.readbyqxmd.com/read/28068671/high-spatial-resolution-mapping-of-catalytic-reactions-on-single-particles
#17
Chung-Yeh Wu, William J Wolf, Yehonatan Levartovsky, Hans A Bechtel, Michael C Martin, F Dean Toste, Elad Gross
The critical role in surface reactions and heterogeneous catalysis of metal atoms with low coordination numbers, such as found at atomic steps and surface defects, is firmly established. But despite the growing availability of tools that enable detailed in situ characterization, so far it has not been possible to document this role directly. Surface properties can be mapped with high spatial resolution, and catalytic conversion can be tracked with a clear chemical signature; however, the combination of the two, which would enable high-spatial-resolution detection of reactions on catalytic surfaces, has rarely been achieved...
January 11, 2017: Nature
https://www.readbyqxmd.com/read/28067993/on-the-structure-property-relationships-of-cation-exchanged-zk-5-zeolites-for-co2-adsorption
#18
Trong Pham, Raul Lobo, Matthew Hudson, Craig Brown
The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites are correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibit high isosteric heats of adsorption (Qst) at low CO2 coverage, with Na-ZK-5 having the highest Qst (≈49 kJ/mol). Mg2+ is located at the center of the zeolite hexagonal prism, with the cation inaccessible to CO2, leading to a much lower Qst (≈30 kJ/mol) and lower overall uptake capacity...
January 9, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28067927/dependence-of-the-ce-iii-ce-iv-ratio-on-intracellular-localization-in-ceria-nanoparticles-internalized-by-human-cells
#19
Daniela Ferraro, Ilenia G Tredici, Paolo Ghigna, Hiram Castillio-Michel, Andrea Falqui, Cristiano Di Benedetto, Giancarla Alberti, Vittorio Ricci, Umberto Anselmi-Tamburini, Patrizia Sommi
CeO2 nanoparticles (CNPs) have been investigated as promising antioxidant agents with significant activity in the therapy of diseases involving free radicals or oxidative stress. However, the exact mechanism responsible for CNP activity has not been completely elucidated. In particular, in situ evidence of modification of the oxidative state of CNPs in human cells and their evolution during cell internalization and subsequent intracellular distribution has never been presented. In this study we investigated modification of the Ce(iii)/Ce(iv) ratio following internalization in human cells by X-ray absorption near edge spectroscopy (XANES)...
January 9, 2017: Nanoscale
https://www.readbyqxmd.com/read/28067639/germanium-terminated-100-diamond
#20
Michael Jeffrey Sear, Alex Schenk, Anton Tadich, Benjamin Spencer, Christopher Wright, Alastair Stacey, Christopher Pakes
An ordered germanium terminated (100) diamond surface has been formed and characterised using a combination of low energy electron diffraction and synchrotron-based core level photoemission spectroscopy. A number of preparation methods are explored, in each case inducing a two domain (3x1) surface reconstruction. The surface becomes saturated with bonded germanium such that each (3x1) unit cell hosts 1.26 Ge atoms on average, and possesses a negative electron affinity of -0.71 eV.
January 9, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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