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https://www.readbyqxmd.com/read/28543976/structure-induced-switching-of-the-band-gap-charge-order-and-correlation-strength-in-ternary-vanadium-oxide-bronzes
#1
Thomas Tolhurst, Justin Andrews, Brett Leedahl, Peter Marley, Sarbajit Banerjee, Alexander Moewes
Recently, V2O5 nanowires have been synthesized as several different polymorphs, and as correlated bronzes with cations intercalated between the layers of edge- and corner-sharing VO6 octahedra. Unlike extended crystals, which tend to be plagued by substantial local variations in stoichiometry, nanowires of correlated bronzes exhibit precise charge ordering, thereby giving rise to pronounced electron correlation effects. These developments have greatly broadened the scope of research, and promise applications in several frontier electronic devices that make use of novel computing vectors...
May 21, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28543631/a-three-dimensional-placoderm-stem-group-gnathostome-pharyngeal-skeleton-and-its-implications-for-primitive-gnathostome-pharyngeal-architecture
#2
Martin D Brazeau, Matt Friedman, Anna Jerve, Robert C Atwood
The pharyngeal skeleton is a key vertebrate anatomical system in debates on the origin of jaws and gnathostome (jawed vertebrate) feeding. Furthermore, it offers considerable potential as a source of phylogenetic data. Well-preserved examples of pharyngeal skeletons from stem-group gnathostomes remain poorly known. Here, we describe an articulated, nearly complete pharyngeal skeleton in an Early Devonian placoderm fish, Paraplesiobatis heinrichsi Broili, from Hunsrück Slate of Germany. Using synchrotron light tomography, we resolve and reconstruct the three-dimensional gill arch architecture of Paraplesiobatis and compare it with other gnathostomes...
May 23, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28541929/pressure-induced-structural-modifications-of-rare-earth-hafnate-pyrochlore
#3
Katlyn M Turner, Dylan R Rittman, Rachel A Heymach, Cameron L Tracy, Madison L Turner, Antonio F Fuentes, Wendy L Mao, Rodney C Ewing
Complex oxides with the pyrochlore (A2B2O7) and defect-fluorite ((A,B)4O7) structure-types undergo structural transformations under high-pressure. Rare-earth hafnates (A2Hf2O7) form the pyrochlore structure for A  =  La-Tb and the defect-fluorite structure for A  =  Dy-Lu. High-pressure transformations in A2Hf2O7 pyrochlore (A  =  Sm, Eu, Gd) and defect-fluorite (A  =  Dy, Y, Yb) were investigated up to ~50 GPa and characterized by in situ Raman spectroscopy and synchrotron x-ray diffraction (XRD)...
May 25, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28541662/in-operando-quantification-of-three-dimensional-water-distribution-in-nanoporous-carbon-based-layers-in-polymer-electrolyte-membrane-fuel-cells
#4
Saad Alrwashdeh, Ingo Manke, Henning Markötter, Merle Klages, Martin Göbel, Jan Haußmann, Joachim Scholta, John Banhart
Understanding the function of nanoporous materials employed in polymer electrolyte membrane fuel cells (PEMFCs) is crucial to improve their performance, durability and cost efficiency. Up to now, the water distribution in the nm-sized pore structures was hardly accessible during operation of the cells. Here we demonstrate that phase contrast synchrotron X-ray tomography allows for an in-operando quantification of the three-dimensional water distribution within the nm-sized pores of carbon-based micro porous layers (MPLs)...
May 25, 2017: ACS Nano
https://www.readbyqxmd.com/read/28537706/sodium-rivals-silver-as-single-atom-active-centers-for-catalyzing-abatement-of-formaldehyde
#5
Yaxin Chen, Jiayi Gao, Zhiwei Huang, Meijuan Zhou, Junxiao Chen, Chao Li, Zhen Ma, Jianmin Chen, Xingfu Tang
The development of efficient alkali-based catalysts for the abatement of formaldehyde (HCHO), a ubiquitous air pollutant, is economically desirable. Here we comparatively study the catalytic performance of two single-atom catalysts, Na1/HMO and Ag1/HMO (HMO = Hollandite manganese oxide), in the complete oxidation of HCHO at low temperatures, in which the products are only CO2 and H2O. These catalysts are synthesized by anchoring single sodium ions or silver atoms on HMO(001) surfaces. Synchrotron X-ray diffraction patterns with structural refinement together with transmission electron microscopy images demonstrate that single sodium ions on the HMO(001) surfaces of Na1/HMO have the same local structures as silver atoms of Ag1/HMO...
May 24, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28537382/in-situ-monitoring-of-the-mechanosynthesis-of-the-archetypal-metal-organic-framework-hkust-1-effect-of-liquid-additives-on-the-milling-reactivity
#6
Tomislav Stolar, Lisa Batzdorf, Stipe Lukin, Dijana Žilić, Cristina Motillo, Tomislav Friščić, Franziska Emmerling, Ivan Halasz, Krunoslav Užarević
We have applied in situ monitoring of mechanochemical reactions by high-energy synchrotron powder X-ray diffraction to study the role of liquid additives on the mechanochemical synthesis of the archetypal metal-organic framework (MOF) HKUST-1, which was one of the first and is still among the most widely investigated MOF materials to be synthesized by solvent-free procedures. It is shown here how the kinetics and mechanisms of the mechanochemical synthesis of HKUST-1 can be influenced by milling conditions and additives, yielding on occasion two new and previously undetected intermediate phases containing a mononuclear copper core, and that finally rearrange to form the HKUST-1 architecture...
May 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28537310/tailoring-phase-transition-temperatures-in-perovskites-via-a-site-vacancy-generation
#7
Thomas A Whittle, William R Brant, James R Hester, Qinfen Gu, Siegbert Schmid
The structures across the Sr0.8Ti0.6-xZrxNb0.4O3, 0 ≤ x ≤ 0.6, defect perovskite series were investigated using complementary synchrotron X-ray and neutron powder diffraction data. The locations of second order compositional and temperature dependent phase transitions between the high symmetry cubic Pm3[combining macron]m phase and the lower symmetry tetragonal I4/mcm phase were determined. Deviation of the oxygen x coordinate from the high symmetry value and the B-O-B bond angle from 180° as well as the tetragonal strain squared were each found to be suitable order parameters to monitor the transitions...
May 24, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28537223/structural-evolution-behavior-of-manganese-monophosphide-under-high-pressure-experimental-and-theoretical-study
#8
Zhenhai Yu, Wei Wu, Pengchao Lu, Jinggeng Zhao, Jinguang Cheng, Qingyang Hu, Ye Yuan, Xin Li, Cuiying Pei, Fengjiao Chen, Zhipeng Yan, Shuai Yan, Ke Yang, Jian Sun, Jianlin Luo, Lin Wang
The influence of external pressure on the structural properties of manganese monophosphides (MnP) at room temperature has been studied using in situ angle dispersive synchrotron x-ray powder diffraction (AD-XRD) with a diamond anvil cell. The crystal structure of MnP is stable between 0 to 15 GPa. However, the compressibility of b-axis is much larger than those of a- and c-axes. From this result we suggested that the occurrence of superconductivity in MnP was induced by suppression of the long-range antiferromagnetically ordered state rather than a structural phase transition...
May 24, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28537193/isolated-potato-virus-a-coat-protein-possesses-unusual-properties-and-forms-different-short-virus-like-particles
#9
Alexander L Ksenofontov, Eugeny N Dobrov, Natalia V Fedorova, Marina V Serebryakova, Andrei N Prusov, Ludmila A Baratova, Viiu Paalme, Lilian Järvekülg, Eleonora V Shtykova
In our previous study, we have observed that the isolated coat proteins (CP) of the Potyvirus Potato Virus A (PVA) virions exhibit an intrinsic tendency of to self-associate into various multimeric forms containing some fractions of cross-β-structure. In this report, we studied the effect of solution conditions on the structure and dissociation of isolated PVA CP using a number of complementary physicochemical methods. Analysis of the structure of PVA CP in solution was performed by limited proteolysis with MALDI-TOF Mass Spectrometry analysis, transmission electron microscopy, intrinsic fluorescence spectroscopy and synchrotron small angle X-ray scattering (SAXS)...
May 24, 2017: Journal of Biomolecular Structure & Dynamics
https://www.readbyqxmd.com/read/28536389/an-abraded-surface-of-doxorubicin-loaded-surfactant-containing-drug-delivery-systems-effectively-reduces-the-survival-of-carcinoma-cells
#10
Christian Schmidt, Fabiano Yokaichiya, Nurdan Doğangüzel, Margareth K K Dias Franco, Leide P Cavalcanti, Mark A Brown, Melissa I Alkschbirs, Daniele R de Araujo, Mont Kumpugdee-Vollrath, Joachim Storsberg
An effective antitumor remedy is yet to be developed. All previous approaches for a targeted delivery of anticancer medicine have relied on trial and error. The goal of this study was to use structural insights gained from the study of delivery systems and malignant cells to provide for a systematic approach to the development of next-generation drugs. We used doxorubicin (Dox) liposomal formulations. We assayed for cytotoxicity via the electrical current exclusion method. Dialysis of the samples yielded information about their drug release profiles...
September 15, 2016: Biomedicines
https://www.readbyqxmd.com/read/28535460/a-synchrotron-infrared-absorption-study-of-pressure-induced-polymerization-of-acrylamide
#11
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
https://www.readbyqxmd.com/read/28535074/synchrotron-imaging-shows-effect-of-ventilator-settings-on-intra-breath-cyclic-changes-in-pulmonary-blood-volume
#12
Liisa Porra, Ludovic Broche, Loïc Dégrugilliers, Gergely Albu, Iliona Malaspinas, Camille Doras, Mats Wallin, Magnus Hallbäck, Walid Habre, Sam Bayat
RATIONALE: Despite the importance of dynamic changes in the regional distributions of gas and blood during the breathing cycle for lung function in the mechanically ventilated patient, no quantitative data on such cyclic changes is currently available. METHODS: We used a novel gated synchrotron CT-imaging to quantitatively image regional lung gas (Vg), tissue density and blood volume (Vb) in 6 anaesthetized, paralyzed and mechanically ventilated rabbits with normal lungs...
May 23, 2017: American Journal of Respiratory Cell and Molecular Biology
https://www.readbyqxmd.com/read/28533391/thoracic-vertebral-count-and-thoracolumbar-transition-in-australopithecus-afarensis
#13
Carol V Ward, Thierra K Nalley, Fred Spoor, Paul Tafforeau, Zeresenay Alemseged
The evolution of the human pattern of axial segmentation has been the focus of considerable discussion in paleoanthropology. Although several complete lumbar vertebral columns are known for early hominins, to date, no complete cervical or thoracic series has been recovered. Several partial skeletons have revealed that the thoracolumbar transition in early hominins differed from that of most extant apes and humans. Australopithecus africanus, Australopithecus sediba, and Homo erectus all had zygapophyseal facets that shift from thoracic-like to lumbar-like at the penultimate rib-bearing level, rather than the ultimate rib-bearing level, as in most humans and extant African apes...
May 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28533266/non-linearity-of-the-collagen-triple-helix-in-solution-and-implications-for-collagen-function
#14
Kenneth T Walker, Ruodan Nan, David W Wright, Jayesh Gor, Anthony C Bishop, George I Makhatadze, Barbara Brodsky, Stephen J Perkins
Collagen adopts a characteristic supercoiled triple helical conformation which requires a repeating (Xaa-Yaa-Gly)n sequence. Despite the abundance of collagen, a combined experimental and atomistic modelling approach has not so far quantitated the degree of flexibility seen experimentally in the solution structures of collagen triple helices. To address this question, we report an experimental study on the flexibility of varying lengths of collagen triple helical peptides, composed of six, eight, ten and twelve repeats of the most stable Pro-Hyp-Gly (POG) units...
May 22, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28530304/visualization-of-structural-evolution-and-phase-distribution-of-a-lithium-vanadium-oxide-li1-1v3o8-electrode-via-an-operando-and-in-situ-energy-dispersive-x-ray-diffraction-technique
#15
Qing Zhang, Andrea M Bruck, David C Bock, Jing Li, Varun Sarbada, Robert Hull, Eric A Stach, Kenneth J Takeuchi, Esther S Takeuchi, Amy C Marschilok
Li1+nV3O8 (n = 0-0.2) has been extensively investigated as a cathode material for Li ion batteries because of its superior electrochemical properties including high specific energy and good rate capability. In this paper, a synchrotron based energy dispersive X-ray diffraction (EDXRD) technique was employed to profile the phase transitions and the spatial phase distribution of a Li1.1V3O8 electrode during electrochemical (de)lithiation in situ and operando. As annealing temperature during the preparation of the Li1...
May 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28529791/crystal-structure-of-1-4-8-11-tetra-azonia-cyclo-tetra-decane-bis-dichromate-monohydrate-from-synchrotron-data
#16
Dohyun Moon, Jong-Ha Choi
The asymmetric unit of the hydrated title salt, (C10H28N4)[Cr2O7]2·H2O [C10H28N4 = H4(cyclam) = 1,4,8,11-tetra-azonia-cyclo-tetra-deca-ne], contains two half-cations (both completed by crystallographic inversion symmetry), two dichromate anions and one water mol-ecule. The two [CrO7](2-) anions exhibit a nearly staggered conformation, with bridging angles of 133.37 (11) and 136.28 (12)°. The distortions of the dichromate anions are due to their participation in hydrogen-bonding inter-actions with the water mol-ecule and the cations...
May 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28527394/elucidation-of-penetration-enhancement-mechanism-of-emu-oil-using-ftir-microspectroscopy-at-emira-laboratory-of-sesame-synchrotron
#17
Randa S H Mansour, Alsayed A Sallam, Imad I Hamdan, Enam A Khalil, Ibraheem Yousef
It has been proposed that Emu oil possesses skin permeation-enhancing effect. This study aimed to address its possible penetration enhancement mechanism(s) using IR microscopy, in accordance with LPP theory. The penetration of Emu oil through the layers of human skin was accomplished by monitoring oil-IR characteristic feature at 3006cm(-1). The unsaturated components of Emu oil accumulated at about 270μm depth of skin surface. The interaction of Emu oil with lipid and protein constituents of SC was investigated in comparison with a commonly used enhancer, IPM...
May 12, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28524209/understanding-the-biomimetic-properties-of-gallium-in-pseudomonas-aeruginosa-an-xas-and-xps-study
#18
F Porcaro, C Bonchi, A Ugolini, E Frangipani, G Polzonetti, P Visca, C Meneghini, C Battocchio
Pyochelin (PCH) is a siderophore (extracellular chelator) produced by the pathogenic bacterium Pseudomonas aeruginosa (PAO). PCH is implicated in iron (Fe(3+)) transport to PAO, and is crucial for its metabolism and pathogenicity. Due to the chemical similarity with Fe(3+), gallium (Ga(3+)) interferes with vital iron-dependent processes in bacterial cells, thereby opening new perspectives for the design of specific metal-based antibacterial drugs. However, the structural basis for the Fe(3+)-mimetic properties of Ga(3+) complexed with the PCH siderophore is still lacking...
May 19, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28521258/synchrotron-based-x-ray-microscopy-for-sub-100nm-resolution-cell-imaging
#19
REVIEW
Ying Zhu, Jichao Zhang, Aiguo Li, Yuanqing Zhang, Chunhai Fan
Microscopic imaging provides a straightforward approach to deepen our understanding of cellular events. While the resolution of optical microscopes is generally limited to 200-300nm due to the diffraction limit, there has been ever growing interest in studying cells at the sub-100nm regime. By exploiting the short wavelength, long penetration depth and elemental specificity of X-rays, synchrotron-based X-ray microscopy (XRM) has demonstrated its power in exploring the structure and function of cells at the nanometer resolution...
May 15, 2017: Current Opinion in Chemical Biology
https://www.readbyqxmd.com/read/28521096/photoionization-efficiencies-of-five-polycyclic-aromatic-hydrocarbons
#20
K Olof Johansson, Matthew F Campbell, Paolo Elvati, Paul E Schrader, Judit Zádor, Nicole K Richards-Henderson, Kevin R Wilson, Angela Violi, Hope A Michelsen
We have measured photoionization-efficiency curves for pyrene, fluoranthene, chrysene, perylene, and coronene in the photon-energy range 7.5-10.2 eV and derived their photoionization cross-section curves in this energy range. All measurements were performed using tunable vacuum ultraviolet (VUV) radiation generated at the Advanced Light Source synchrotron at Lawrence Berkeley National Laboratory. The VUV radiation was used for photoionization and detection was performed using a time-of-flight mass spectrometer...
May 18, 2017: Journal of Physical Chemistry. A
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