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Kunpeng Cui, Zhe Ma, Nan Tian, Fengmei Su, Dong Liu, Liangbin Li
Flow-induced crystallization (FIC) is a typical nonequilibrium phase transition and a core industry subject for the largest group of commercially useful polymeric materials: semicrystalline polymers. A fundamental understanding of FIC can benefit the research of nonequilibrium ordering in matter systems and help to tailor the ultimate properties of polymeric materials. Concerning the crystallization process, flow can accelerate the kinetics by orders of magnitude and induce the formation of oriented crystallites like shish-kebab, which are associated with the major influences of flow on nucleation, that is, raised nucleation density and oriented nuclei...
January 19, 2018: Chemical Reviews
D Kaiser, E Reusch, P Hemberger, A Bodi, E Welz, B Engels, I Fischer
A recent review on the photoionisation of the C6H4 isomer ortho-benzyne suggests that bands reported in earlier photoelectron spectra might be due to side products or contaminations, while computations raise doubts, whether the cation has a planar geometry. We therefore reinvestigate the photoionisation of ortho-benzyne, generated by pyrolysis from benzocyclobutenedione, by photoion mass-selected threshold photoelectron (ms-TPE) spectroscopy using synchrotron radiation. The experiments are accompanied by a theoretical study that investigates the structure of the ortho-benzyne cation systematically as a function of the computational method, up to CASPT2(11,14) ab initio computations...
January 19, 2018: Physical Chemistry Chemical Physics: PCCP
Enyuan Hu, Xuelong Wang, Xiqian Yu, Xiao-Qing Yang
The rechargeable lithium-ion battery (LIB) is the most promising energy storage system to power electric vehicles with high energy density and long cycling life. However, in order to meet customers' demands for fast charging, the power performances of current LIBs need to be improved. From the cathode aspect, layer-structured cathode materials are widely used in today's market and will continue to play important roles in the near future. The high rate capability of layered cathode materials during charging and discharging is critical to the power performance of the whole cell and the thermal stability is closely related to the safety issues...
January 19, 2018: Accounts of Chemical Research
Henry Mosey, Juan A Núñez, Alice Goring, Claire E Clarkin, Katherine A Staines, Peter D Lee, Andrew A Pitsillides, Behzad Javaheri
SCLEROSTIN (Sost) is expressed predominantly in osteocytes acting as a negative regulator of bone formation. In humans, mutations in the SOST gene lead to skeletal overgrowth and increased bone mineral density, suggesting that SCLEROSTIN is a key regulator of bone mass. The function of SCLEROSTIN as an inhibitor of bone formation is further supported by Sost knockout (KO) mice which display a high bone mass with elevated bone formation. Previous studies have indicated that Sost exerts its effect on bone formation through Wnt-mediated regulation of osteoblast differentiation, proliferation, and activity...
September 13, 2017: Frontiers in Materials
John F Nagle
Synchrotron diffuse x-ray scattering data reveal a dramatic softening of the molecular tilt modulus K_{θ} of the model biomembrane composed of DMPC lipids as the temperature is lowered towards the main phase transition temperature at T_{M}=24^{∘}C. Spontaneous tilt occurs below T_{M}, suggesting that tilt is a symmetry breaking order parameter. Consistent with this hypothesis, it is also found that a different lipid POPS has no spontaneous tilt below its T_{M} at 14^{∘}C and correspondingly its tilt modulus did not soften as T_{M} was approached from above...
September 2017: Physical Review. E
Björn De Samber, Eline Meul, Brecht Laforce, Boel De Paepe, Joél Smet, Michiel De Bruyne, Riet De Rycke, Sylvain Bohic, Peter Cloetens, Rudy Van Coster, Peter Vandenabeele, Tom Vanden Berghe
Synchrotron radiation based nanoscopic X-ray fluorescence (SR nano-XRF) analysis can visualize trace level elemental distribution in a fully quantitative manner within single cells. However, in-air XRF analysis requires chemical fixation modifying the cell's chemical composition. Here, we describe first nanoscopic XRF analysis upon cryogenically frozen (-150°C) fibroblasts at the ID16A-NI 'Nano-imaging' end-station located at the European Synchrotron Radiation Facility (ESRF) in Grenoble (France). Fibroblast cells were obtained from skin biopsies from control and Friedreich's ataxia (FRDA) patients...
2018: PloS One
Chuanlong Lin, Xue Yong, John S Tse, Jesse S Smith, Stanislav V Sinogeikin, Curtis Kenney-Benson, Guoyin Shen
We report the results of in situ structural characterization of the amorphization of crystalline ice Ih under compression and the relaxation of high-density amorphous (HDA) ice under decompression at temperatures between 96 and 160 K by synchrotron x-ray diffraction. The results show that ice Ih transforms to an intermediate crystalline phase at 100 K prior to complete amorphization, which is supported by molecular dynamics calculations. The phase transition pathways show clear temperature dependence: direct amorphization without an intermediate phase is observed at 133 K, while at 145 K a direct Ih-to-IX transformation is observed; decompression of HDA shows a transition to low-density amorphous ice at 96 K and ∼1  Pa, to ice Ic at 135 K and to ice IX at 145 K...
September 29, 2017: Physical Review Letters
Piotr Aleksander Guńka, Michał Hapka, Michael Hanfland, Maciej Dranka, Grzegorz Chałasiński, Janusz Zachara
Investigations into the helium permeation of arsenolite, the cubic, molecular arsenic(III) oxide polymorph As₄O₆, were carried out in order to understand how and why arsenolite helium clathrate As₄O₆∙2He is formed. High-pressure synchrotron X-ray diffraction experiments on arsenolite single crystals revealed that the permeation of helium into non-porous arsenolite depends on the time during which the crystal is subjected to high pressure and on the crystal history. The single crystal was totally transformed into As₄O₆·2He within 45 h under 5 GPa...
January 17, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
C Cappuccino, P P Mazzeo, T Salzillo, E Venuti, A Giunchi, R G Della Valle, A Brillante, C Bettini, M Melucci, L Maini
This work presents a Raman based approach for the rapid identification of the molecular conformation in a series of new 2,3-thienoimide capped quaterthiophenes, whose crystal structures were determined by synchrotron radiation X-ray powder diffraction. These systems display two conformational polymorphs, known as forms A and B, as a result of the anti-anti-anti and syn-anti-syn arrangements of the quaterthiophene cores. In a micro-Raman and computational study, the spectroscopic differences between the conformers were detected and proved to be suitable markers for polymorph identification...
January 17, 2018: Physical Chemistry Chemical Physics: PCCP
D Schleier, P Constantinidis, N Faßheber, I Fischer, G Friedrichs, P Hemberger, E Reusch, B Sztáray, K Voronova
The kinetics of the combustion-relevant reaction of the allyl radical, a-C3H5, with molecular oxygen has been studied in a flow tube reactor at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source storage ring, using the CRF-PEPICO (Combustion Reactions Followed by Photoelectron Photoion Coincidence Spectroscopy) setup. The ability to measure threshold photoelectron spectra enables a background-free detection of reactive species as well as an isomer-specific analysis of reaction products. Allyl was generated by direct photodissociation of allyl iodide at 266 nm and 213 nm and indirectly by the reaction of propene with Cl atoms, which were generated by photolysis from oxalyl chloride at 266 nm...
January 17, 2018: Physical Chemistry Chemical Physics: PCCP
Luís F S Mendes, Luis G M Basso, Patricia S Kumagai, Raquel Fonseca-Maldonado, Antonio J Costa-Filho
BACKGROUND: Golgi Reassembly and Stacking Proteins (GRASPs) are widely spread among eukaryotic cells (except plants) and are considered as key components in both the stacking of the Golgi cisternae and its lateral connection. Furthermore, GRASPs were also proved essential in the unconventional secretion pathway of several proteins, even though the mechanism remains obscure. It was previously observed that the GRASP homolog in Cryptococcus neoformans has a molten globule-like behavior in solution...
January 12, 2018: Biochimica et Biophysica Acta
Francesca Cammisuli, Silvia Giordani, Alessandra Gianoncelli, Clara Rizzardi, Lucia Radillo, Marina Zweyer, Tatiana Da Ros, Murielle Salomé, Mauro Melato, Lorella Pascolo
Carbon nanotubes (CNTs) are promising products in industry and medicine, but there are several human health concerns since their fibrous structure resembles asbestos. The presence of transition metals, mainly iron, in the fibres seems also implicated in the pathogenetic mechanisms. To unravel the role of iron at mesothelial level, we compared the chemical changes induced in MeT-5A cells by the exposure to asbestos (crocidolite) or CNTs at different content of iron impurities (raw-SWCNTs, purified- and highly purified-SWCNTs)...
January 15, 2018: Scientific Reports
Rixiang Huang, Bei Zhang, Emily M Saad, Ellery D Ingall, Yuanzhi Tang
Thermal and hydrothermal treatments are promising techniques for sewage sludge management that can potentially facilitate safe waste disposal, energy recovery, and nutrient recovery/recycling. Content and speciation of heavy metals in the treatment products affect the potential environmental risks upon sludge disposal and/or application of the treatment products. Therefore, it is important to study the speciation transformation of heavy metals and the effects of treatment conditions. By combining synchrotron X-ray spectroscopy/microscopy analysis and sequential chemical extraction, this study systematically characterized the speciation of Zn and Cu in municipal sewage sludges and their chars derived from pyrolysis (a representative thermal treatment technique) and hydrothermal carbonization (HTC; a representative hydrothermal treatment technique)...
January 4, 2018: Water Research
Hamidreza Abdolvand, Jonathan Wright, Angus J Wilkinson
Anisotropy in single-crystal properties of polycrystals controls both the overall response of the aggregates and patterning of local stress/strain distributions, the extremes of which govern failure processes. Improving the understanding of grain-grain interactions has important consequences for in-service performance limits. Three-dimensional synchrotron X-ray diffraction was used to study the evolution of grain-resolved stresses over many contiguous grains in Zr and Ti polycrystals deformed in situ. In a significant fraction of grains, the stress along the loading axis was found to decrease during tensile plastic flow just beyond the macroscopic yield point; this is in the absence of deformation twinning and is a surprising behaviour...
January 12, 2018: Nature Communications
Kathryn J Ham, Yoshio Kono, Parimal J Patel, Steven M Kilczewski, Yogesh K Vohra
Pressure induced densification and compression of a reprocessed sample of borosilicate glass has been studied by X-ray radiography and energy dispersive X-ray diffraction using a Paris-Edinburgh (PE) press at a synchrotron X-ray source. The reprocessing of a commercial borosilicate glass was carried out by cyclical melting and cooling. Gold foil pressure markers were used to obtain the sample pressure by X-ray diffraction using its known equation of state, while X-ray radiography provided a direct measure of the sample volume at high pressure...
January 12, 2018: Materials
Mehmet Yesiltas
Synchrotron-based high spatial resolution hyperspectral infrared imaging technique provides thousands of infrared spectra with high resolution, thus allowing us to acquire detailed spatial maps of chemical molecular structures for many grains in short times. Utilizing this technique, thousands of infrared spectra were analyzed at once instead of inspecting each spectrum separately. Sutter's Mill meteorite is a unique carbonaceous type meteorite with highly heterogeneous chemical composition. Multiple grains from the Sutter's Mill meteorite have been studied using this technique and the presence of both hydrous and anhydrous silicate minerals have been observed...
January 6, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Pascal G Yot, Vibhav Yadav, Salem Ould Amara, Jean-Paul Itiè, Umit B Demirci, Guillaume Maurin
Crystalline B-N-H compounds of low molecular weight have been intensively investigated over the past two decades owing to their promises for chemical hydrogen storage. Hydrazine borane NH2-NH2-BH3 is one of the most recent examples of this family of materials. In the present work, we explored its structural behaviour under mechanical stimulus by synchrotron high pressure X-ray diffraction. It has been evidenced that hydrazine borane shows a gradual pressure-induced decrease of its unit cell dimension and the process is reversible when the applied pressure is released...
January 12, 2018: Physical Chemistry Chemical Physics: PCCP
James T Pearson, Nicola Collie, Regis R Lamberts, Tadakatsu Inagaki, Misa Yoshimoto, Keiji Umetani, Philip Davis, Gerard Wilkins, Pete P Jones, Mikiyasu Shirai, Daryl O Schwenke
Acute myocardial infarction (MI) triggers an adverse increase in cardiac sympathetic nerve activity (SNA). While β-adrenergic receptor (β-AR)-blockers are routinely used for the management of MI, they may also counter β-AR-mediated vasodilation of coronary vessels. We have reported that ghrelin prevents sympathetic activation following MI. Whether ghrelin modulates coronary vascular tone following MI, either through the modulation of SNA, or directly as a vasoactive mediator, has never been addressed.We utilized synchrotron microangiography to image coronary perfusion and vessel internal diameter (ID) in anesthetized Sprague Dawley rats before, and then again 30 mins after induction of an MI (left coronary artery ligation)...
January 9, 2018: Endocrinology
Nadia Mazarakis, Jitraporn Vongsvivut, Keith R Bambery, Kenneth J Snibson, Simon G Royce, Tom C Karagiannis
Asthma is a chronic respiratory disease characterised by airway inflammation, remodeling and hyperresponsiveness. The ability to replicate these asthma traits in the well-established ovalbumin induced chronic model of allergic airways disease is an important tool for asthma research and preclinical drug development. Here, spectra derived from focal plane array and Synchrotron-Fourier transform infrared maps were used to analyse biochemical changes in lung tissue from an ovalbumin-induced murine chronic allergic airways disease model...
September 2017: Hellenic Journal of Nuclear Medicine
Mattia Donzelli, Elke Brauer-Krisch, Uwe Oelfke, Jan J Wilkens, Stefan Bartzsch
Microbeam Radiation Therapy (MRT) is a still preclinical approach in radiation oncology that uses planar micrometre wide beamlets with extremely high peak doses, separated by a few hundred micrometre wide low dose regions. Abundant preclinical evidence demonstrates that MRT spares normal tissue more effectively than conventional radiation therapy, at equivalent tumour control. In order to launch first clinical trials, accurate and efficient dose calculation methods are an inevitable prerequisite. In this work a hybrid dose calculation approach is presented which is based on a combination of Monte Carlo and kernel based dose calculation...
January 11, 2018: Physics in Medicine and Biology
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