Academy of Science and Technology

Chongqing, China

Academy of Science and Technology

Chongqing, China

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News Article | May 9, 2017
Site: phys.org

Crystal structure of Pb2+Pb4+3Co2+2Co3+2O12 where Pb and Co have charge orderings despite the simple PbCoO3 chemical composition and the valence distribution changes for PbMO3 (M: 3d transition metal). Credit: Journal of the American Chemical Society Scientists at Tokyo Institute of Technology, the Kanagawa Academy of Science and Technology have reported an unusual charge distribution of Pb2+Pb4+3Co2+2Co3+2O12 for a perovskite PbCoO3 synthesized at 12 GPa, with charge orderings in the A and B sites of an ABO3 perovskite. This strategy can possibly lead to the production of next-generation materials with fascinating properties such as superconductivity, colossal magnetoresistance, and high thermopower. Transition metals (TMs) exhibit charge degree of freedom, resulting in interesting properties, such as charge ordering related to metal-insulator transitions, high-temperature superconductivity, colossal magnetoresistance, and high thermopower. Metal ions with half-integer valence tend to split into two spatially ordered integer valence ions. To realize a half-integer valence state and charge ordering in the B site of a perovskite ABO3, two or more elements with different valences need to be mixed in the A site. A group of researchers, Prof. Masaki Azuma from Tokyo Institute of Technology, and Dr.Yuki Sakai at the Kanagawa Academy of Science and Technology and colleagues, have reported an unusual half-integer average charge system Pb3.5+M2.5+O3 with charge ordering in the A and B sites of a perovskite PbCoO3. Furthermore, the charge orderings in these sites were stabilized by tuning the energy levels of the Pb 6s and TM 3d orbitals. Bond valence sum calculations revealed a valence distribution of Pb2+Pb4+3Co2+2Co3+2O12, with Pb and Co exhibiting charge ordering despite the chemical composition of PbCoO3. As expected, the average oxidation state was Pb3.5+Co2.5+O3, with half-integer valences in both A and B sites of the perovskite structure stabilized by the balanced Pb 6s and Co 3d levels. The valence distribution of PbMO3 was controlled by tuning the depth of the d level of M. The complex valence distribution is expected to change on perturbations, e.g., pressure and chemical modification. For instance, when the Co charge ordering is melted, Pb2+0.25Pb4+0.75Co2.5+O3 is formed, Pb2+0.5Pb4+0.5Co3+O3 is first formed by the intermetallic charge transfer between Pb and Co and then possibly Pb2+Co4+O3 under pressure. In the future, the application of the strategy of realizing mixed valence states in the A and B sites of perovskite compounds via the tuning of the energy difference between Pb 6s and transition metal 3d orbitals will be reported for other systems with valence-skipping elements, e.g., Au, Tl, and Sb. Explore further: Revealing the ligand-hole localization behaviors in oxides with unusual high-valence Fe More information: Yuki Sakai et al, A-Site and B-Site Charge Orderings in anLevel Controlled Perovskite Oxide PbCoO, Journal of the American Chemical Society (2017). DOI: 10.1021/jacs.7b01851


News Article | May 9, 2017
Site: www.eurekalert.org

Transition metals (TMs) exhibit charge degree of freedom, resulting in interesting properties, such as charge ordering related to metal-insulator transitions, high-temperature superconductivity, colossal magnetoresistance, and high thermopower. Metal ions with half-integer valence tend to split into two spatially ordered integer valence ions. To realize a half-integer valence state and charge ordering in the B site of a perovskite ABO3, two or more elements with different valences need to be mixed in the A site. A group of researchers, Prof. Masaki Azuma from Tokyo Institute of Technology, and Dr.Yuki Sakai at the Kanagawa Academy of Science and Technology and colleagues, have reported an unusual half-integer average charge system Pb3.5+M2.5+O3 with charge ordering in the A and B sites of a perovskite PbCoO3. Furthermore, the charge orderings in these sites were stabilized by tuning the energy levels of the Pb 6s and TM 3d orbitals. Bond valence sum calculations revealed a valence distribution of Pb2+Pb4+3Co2+2Co3+2O12, with Pb and Co exhibiting charge ordering despite the chemical composition of PbCoO3. As expected, the average oxidation state was Pb3.5+Co2.5+O3, with half-integer valences in both A and B sites of the perovskite structure stabilized by the balanced Pb 6s and Co 3d levels. The valence distribution of PbMO3 was controlled by tuning the depth of the d level of M. The complex valence distribution is expected to change on perturbations, e.g., pressure and chemical modification. For instance, when the Co charge ordering is melted, Pb2+0.25Pb4+0.75Co2.5+O3 is formed, Pb2+0.5Pb4+0.5Co3+O3 is first formed by the intermetallic charge transfer between Pb and Co and then possibly Pb2+Co4+O3 under pressure. In the future, the application of the strategy of realizing mixed valence states in the A and B sites of perovskite compounds via the tuning of the energy difference between Pb 6s and transition metal 3d orbitals will be reported for other systems with valence-skipping elements, e.g., Au, Tl, and Sb.


News Article | October 26, 2016
Site: www.eurekalert.org

OAK RIDGE, Tenn., Oct. 25, 2016 -- Six researchers from the Department of Energy's Oak Ridge National Laboratory have been elected fellows of the American Physical Society (APS). The APS is one of the largest physics organizations in the world with more than 51,000 members in academia, government and industry. Fellows of the APS are recognized for their exceptional contributions to the physics enterprise in outstanding research, applications and leadership in or service to physics and physics education. John Galambos, director of the Spallation Neutron Source Second Target Station Project Office, was cited by the APS Division of Physics of Beams for "outstanding leadership and vision in the design, commissioning and effective operation of high power hadron accelerators." Galambos has been involved in the design, construction, commissioning and operation of the Spallation Neutron Source, a DOE Office of Science User Facility, since 1996 and led the Source Engineering and Design Analysis group and Accelerator Physics, Beam Instrumentation and Ion Source group until 2015. Robert Grzywacz, physicist and director of the University of Tennessee (UT)-ORNL-Vanderbilt University Joint Institute for Nuclear Physics and Applications, was elected by the APS Division of Nuclear Physics for the "pioneering use of digital signal processing for decay studies of exotic nuclei to identify extremely short-lived proton emitters and, through its unique triggering capabilities, to discover super-allowed alpha decay." Grzywacz is also a physics professor at UT and helped develop the data acquisition technology used to confirm the existence of element 117, Tennessine. Ho Nyung Lee, distinguished scientist and leader of the Thin Films and Nanostructures group in ORNL's Materials Science and Technology Division, was recommended by the APS Division of Materials Physics for "pioneering contributions in achieving atomic-scale growth control in pulsed laser deposition, and for significant advances towards discovery of functional oxide materials by epitaxial design of thin films and heterostructures." Lee is also an associate fellow of the Korean Academy of Science and Technology and an adjunct professor at UT and at POSTECH in South Korea. Satoshi Okamoto, a researcher in ORNL's Materials Science and Technology Division, was elected by the APS Division of Condensed Matter Physics for "contributions to the theory of interacting electrons in solids, including foundational work on orbital waves and on correlated-electron superlattices." Okamoto studies novel properties of strongly-correlated electron systems in bulk or heterostructures, such as unconventional superconductivity, magnetism, topological insulators and charge and spin transport. He is a member of ORNL's Complex Collective Materials Phenomena team and has worked as a visiting scientist for the Center for Emergent Matter Science at Riken, the Japanese Institute of Physical and Chemical Research. Athena Safa Sefat, a researcher in ORNL's Materials Science and Technology Division, was recognized by the APS Division of Materials Physics for "major contributions in developing new and pure iron-based superconducting crystals, and advancing the understanding of structure-composition-property relations on multi-length scales in high temperature superconductors and antiferromagnets." Sefat researches energy-related correlated materials, investigating the relationship between atomic structures and physical properties. She was an ORNL Wigner Fellow in 2008, a DOE Early Career Award winner in 2010 and was named a high-cited researcher in the top one percent of condensed matter physicists by Thompson Reuters in 2014. Donald Spong, a distinguished research staff member and plasma physicist in ORNL's Fusion & Materials for Nuclear Systems Division, was honored by the APS Division of Plasma Physics for "insightful analysis of energetic particle instabilities and confinement in general 3-D toroidal configurations and contributions to the physics optimization of stellarators." Spong has more than 40 years of research experience in the physics of energetic particle populations in toroidal fusion plasmas, stellarator optimization, plasma transport in 3-D configurations and plasma kinetic stability simulation methods. He is the deputy leader of the Energetic Particle Physics group of the ITER International Tokamak Physics Activity. Each researcher will receive their fellowship award at their respective division's annual meeting and will be featured in the December issue of APS News. UT-Battelle manages ORNL for the DOE's Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov. High resolution images are available at https:/ NOTE TO EDITORS: You may read other press releases from Oak Ridge National Laboratory or learn more about the lab at http://www. . Additional information about ORNL is available at the sites below:


Chen Y.,Jiangnan University | Wang Y.,Academy of Science and Technology | Liu L.,Jiangnan University | Wu X.,Jiangnan University | And 4 more authors.
Nanoscale | Year: 2015

A novel gold immunochromatographic assay (GICA) based on anti-β-lactam receptors was innovatively developed that successfully allowed rapid and simultaneous detection of fifteen β-lactams in milk samples in 5-10 minutes. By replacing the antibodies used in traditional GICA with anti-β-lactam receptors, the difficulty in producing broad specific antibodies against β-lactams was overcome. Conjugates of ampicillin with BSA and goat anti-mouse immunoglobulin (IgG) were immobilized onto the test and control lines on the nitrocellulose membrane, respectively. Since goat anti-mouse IgG does not combine with receptors, negative serum from mice labelled with gold nanoparticles (GNP) was mixed with GNP-labelled receptors. Results were obtained within 20 min using a paper-based sensor. The utility of the assay was confirmed by the analysis of milk samples. The limits of detection (LOD) for amoxicillin, ampicillin, penicillin G, penicillin V, cloxacillin, dicloxacillin, nafcillin, oxacillin, cefaclor, ceftezole, cefotaxime, ceftiofur, cefoperazone, cefathiamidine, and cefepime were 0.25, 0.5, 0.5, 0.5, 1, 5, 5, 10, 25, 10, 100, 10, 5, 5, and 2 ng mL-1, respectively, which satisfies the maximum residue limits (MRL) set by the European Union (EU). In conclusion, our newly developed GICA-based anti-β-lactam receptor assay provides a rapid and effective method for one-site detection of multiple β-lactams in milk samples. © The Royal Society of Chemistry.


Osaki T.,Kanagawa Academy Of Science And Technology | Osaki T.,University of Tokyo | Osaki T.,Academy of Science and Technology | Kamiya K.,Kanagawa Academy Of Science And Technology | And 3 more authors.
Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) | Year: 2014

This paper describes a batch release technique for monodisperse liposomes immobilized on a substrate (Fig. 1). A single short-time pulsed voltage to the substrate induced detachment of the arrayed liposomes previously developed. Simultaneous release was observed shortly after the electrical stimulation. The release technique produced monodisperse and solvent-free liposomes freely suspended on the substrate, and allowed manipulation of the liposomes. The technique extends the application of our liposome array platform regarding collection/selection of the liposomes interested. © 2014 IEEE.


Dong H.,Chongqing University | Dong H.,Academy of Science and Technology | Pan F.,Chongqing University | Pan F.,Academy of Science and Technology | And 4 more authors.
Materials and Design | Year: 2015

Mg-3Li and Mg-3Li-2Zn alloys were prepared by metal model casting method and extruded at 573. K with the extrusion ratio of 79, and samples of both cast alloys were also conducted to compression with ratios of 5% and 10%. Microstructures and mechanical properties were evaluated. The results showed that both the Zn element and the extruding were beneficial to microstructures and mechanical properties of Mg-3Li alloy. Zn addition has also affected the solidification style of the as-cast hexagonal Mg-Li alloy and resulted in the alteration of the texture. There was a descent of the gradient of the linear sections in each compressive strain-stress curve of the as-cast alloys at the strain of about 10%. This was attributed to the presentation of {10-11} compression twins, which presented after {10-12} tension twins. © 2014 Elsevier Ltd.


Gu J.F.,Ecole Polytechnique de Montréal | Grmela M.,Ecole Polytechnique de Montréal | Bousmina M.,Academy of science and Technology
Journal of Non-Newtonian Fluid Mechanics | Year: 2010

Doi-Ohta rheological model of immiscible blends is extended by replacing the fluid interface with an elastic membrane. A symmetric tensor characterizing the in-membrane deformations joins the surface area and the orientation tensor (used in the Doi-Ohta theory) to provide morphological state variables. The governing equations of the model are solved numerically and the morphological and rheological predictions are presented. As an illustration, we regard the model as a first step in mesoscopic rheological modeling of suspensions of red blood cells. The material properties of the membrane enclosing the red blood cells, that are inferred from rheology, are indeed found to be close to the ones seen in direct experimental measurements. A more realistic model of human blood has to include additional morphological state variables describing larger structures (in particular whole red blood cells). © 2009 Elsevier B.V. All rights reserved.

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