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【原创】International Conference on Neutron Scattering
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International Conference on Neutron Scattering May 3-7, 2009 Knoxville, Tennessee DAY 1 MONDAY, MAY 4 "When nothing else can do the job, neutrons to the rescue...!" - John H. Root, Keynote Speaker The 2009 International Conference on Neutron Scattering (ICNS2009) is being held from May 3rd through the 7th, 2009, in Knoxville, Tennessee. This is the 9th ICNS in a series beginning with ICNS 1982 in Hakone, Japan, and following the last ICNS 2005 in Sydney, Australia.The conference started on Sunday with a welcome reception in the evening. Monday morning saw the official opening of the conference with a keynote talk, followed by two plenary lectures. Technical sessions commenced on Monday afternoon with symposia A, C, D and H holding sessions. A visit to the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory was organized in the evening.  Keynote lecture CONTENTS Opening Session Keynote Lecture - John H Root Plenary Lecture - Tonya Kuhl Plenary Lecture - Omar Yaghi Technical Sessions Visit to the SNS Facility Scenes from the Welcome Reception OPENING SESSION The conference officially opened on Monday morning with a welcoming session. Gregory S. Smith (Oak Ridge National Laboratory), conference chair, first welcomed everyone to Knoxville, Tennessee. Simon Billinge, also a conference chair and vice-president of the National Scattering Society of America (NSSA) then presented a few remarks. He mentioned that there were 616 registered attendees from 29 different countries, with 219 oral presentations and 303 poster presentations scheduled for the week. He also mentioned the significance of neutron science and the broad applications of the field to science. He indicated that it is important to keep the societal impace of neutron science in mind.    (left to right) Gregory Smith, Simon Billinge and Bruce Gaulin The president of NSSA, Bruce Gaulin, followed with his welcoming remarks. He described the various recent advances in neutron facilities and tools. He mentioned that 1 MW operation of the SNS was now imminent, which the neutron scattering community has been waiting for eagerly. Various facilities around the globe are seeing advances, including newer facilities planned in places such as China. He concluded that there has never been a better time to be a member of this scientific community.  ORNL Director Thomas Mason Thomas Mason, Director of ORNL, then presented a welcoming talk. He said that the present group is at the heart of neutron science and makes things happen at the facilities end, though the various users are from the broader scientific community. He emphasized the obvious importance of energy today for society, which he described to be an overconstrained problem. Most of the issues of concern in the energy arena are materials problems. For ORNL, this is the essence of all the funding that has been put in place. The neutron scattering community is a critical part of the energy solution and he urged the community to reach out to the broader scientific community. He mentioned the heritage of the SNS and HFIR which go back to the original graphite reactor at ORNL, the first operational reactor after the "Chicago pile." He concluded by indicating that by doing difficult things, we not only accomplish a lot but also in unexpected areas and ways.  Roger Pynn, Bruce Gaulin and John Root KEYNOTE LECTURE - JOHN H. ROOT Reflections on the International Neutron Scattering Community  John Root, Director of the Canadian Neutron Beam Centre at Chalk River Laboratories, presented the Keynote lecture of the conference. He said that the purpose of his talk was to start a discussion within the neutron scattering community - those gathered here. He first overviewed the neutron scattering facilities around the globe including recent advances and enhancements. He then said that all this progress was quite encouraging. However, let’s take a step back and be sure we are seeing the whole picture, said Root. He mentioned that this was a chance for some audience participation. First, several facilities have been closed in recent times. He asked those whose primary neutron laboratory was closed, from 1998 up to now to stand up. He then asked those who were concerned that resources are not adequate and may be frequently asked to compromise the original vision for their facility to stand. Finally, he asked those concerned about the health of neutron scattering in the coming decade to stand. At the end of this exercise about 30-40% of the audience was standing. He asked everyone to look around and let the message sink in. The challenge now, he said, is how to identify those possibilities that can build and sustain a strong international neutron scattering community for decades to come.  Root then asked the question, "How can we make the value of neutron scattering into ‘common knowledge’?" He asked audience members to describe in a sentence their expectations for people/facilities, impact on science, impact on society, outreach and global networking. One comment for example was "Science is an investment and not an expenditure." Several people urged members to communicate the field more broadly to the general public in order educate them that neutron science affects them in many ways that they may not know about. He concluded by posing the questions: "How can we make the value of neutron scattering into ‘common knowledge’? What “common knowledge” would we like to see …? How shall we position our facility missions for maximum impact? What can we do to rejuvenate and strengthen neutron scattering competencies outside our facilities?" He urged everyone to talk about these during the course of the conference.  PLENARY LECTURE - TONYA KUHL Neutron and X-ray Reflectometry and Grazing Incidence Diffraction Studies of Single Phospholipid Membranes  Understanding the nature of living cell membranes gives important information on cell interaction with the environment. Tonya Kuhl of the University of California, Davis, focused her plenary talk on supported lipid bilayers as model systems for cellular membranes. The amphiphilic properties of lipids facilitate their organized assembly into bilayer structures in aqueous environments. One of the interesting properties of the membranes is their ability to provide diffusion of individual components which create functional microdomains and accommodate membrane-interacting protein complexes. Kuhl demonstrated that precise structural characterization of the membranes allows for a comprehensive understanding of the membrane organization and properties. In this respect, neutron reflectivity is a unique tool for probing membrane structure and mechanism of protein-lipid interactions as a critical step toward understanding protein-lipid interactions at a sub-nanometer resolution. With the help of neutrons, she found that the supported single membranes are identical in structure to lipid multilayers. X-rays were also utilized as a complementary technique to investigate the molecular arrangements and correlation length within the membranes. Kuhl was also interested in probing the internal structure of polymer-cushioned bilayers. She found that the polymer cushions can be made of pH or temperature responsive polylectrolytes such as PAA or PNIPAM. Moreover, she illustrates patterned polymer cushions as templates for lipid bilayers. Finally, she demonstrated that supported membranes are potential materials for bio-sensor applications. For example, the designed membranes on responsive cushions might direct protein diffusion to a specific location in response to an applied trigger, such as an eclectic field, followed by protein crystallization at the location. PLENARY LECTURE - OMAR YAGHI Reticular Chemistry Reticular chemistry is the stitching together of molecules via strong bonds to form networks. Omar Yaghi (Univ. California, Los Angeles) described using reticular chemistry to form metal-organic frameworks (MOFs) wherein inorganic joints are linked together by organic struts to yield various structures (nanoparticles) which can have very large surface areas within. For example, a 25 Angstrom cuboctohedron can be constructed from twelve Cu2(CO2)4 paddle wheel units forming porous metal-organic polyhedra. The system is very versatile and one can form 3-D networks.   He then described MOF-5 [Zn4O(O2C-C6H4-CO2)3] which is formed from zinc acetate, and which is permanently porous forming iso-reticular series. The material yields a surface area of 3300 m2/g. One of the motivations for the present work is hydrogen storage and this porosity level and volume available make this class of materials a strong candidate for this application. This has been demonstrated in several of these materials using volumetric and gravimetric measurements. Yaghi also presented kinetic profiles of hydrogen uptake and release proving that this is a viable possibility. He also described methane storage. Finally, he discussed the interesting possibility of CO2 capture from a power plant or factory using MOF materials. He closed his talk by describing a new class of Zeolitic Imidazolate Framework (ZIF) materials. These allow for isoreticular covalent functionalization. In other words, a crystal can be used as a molecule. TALKS Symposium C: Condensed Matter Physics Experimental and Theoretical Studies of the 4f Hybridization Across the (La,Ce)In3 and CeRhIn5-xSnx Series Olivier Gourdon (Juelich and SNS) described an investigation on 4f Hybridization Across (La,Ce)In3 and CeRhIn5-xSnx Series. Using a combination of high resolution neutron and X-ray diffraction, refinements of the crystal structures of a series of La1-xCexIn3 (x = 0.02, 0.2, 0.5, or 0.8) intermetallic compounds emphasize atypical atomic displacement parameters (ADP) for In and the rare-earth sites. These deformations have been understood by theoretical techniques based on band theory and are the result of hybridization between conduction electrons and 4f-electrons. Symposium D: Chemistry/Earth Sciences Negative Thermal Expansion and Local Structure in Ultra-Flexible Framework Materials  Andrew Goodwin of Cambridge University described highly flexible framework structures using extended linear molecules as bridging ligands and the unusual phenomena demonstrated by these, with specific focus on the negative thermal expansion (NTE) characteristics. While there is interest in such materials for applications such as in spacecraft, Goodwin suggested that there is more interest in the basic science. He described the ZrW2O8 and the Zn(CN)2 linkages in the framework structures. The total scattering technique using neutrons is very useful and the pair distribution function (PDF) can be calculated. This has been shown to be used to calculate EXAFS and TEM structures accurately. In NTE cyanides, peak widths in the PDF contain information on interaction energies between neighboring atoms. Goodwin then focused on the Ag3[Co(CN)6] compound. He concluded by indicating that in thermodynamics of flexibility, extreme flexibility can amplify the role of low-energy interactions, the dominant thermodynamic energy scale can be orders of magnitude lower than in "normal" materials, and these results allow for design of materials with attractive thermomechanic and elastic properties. Negative Thermal Expansion in a Coordination Framework Vanessa Kate Peterson (The Bragg Institute, ANSTO, Australia) continued the theme of negative thermal expansion for the 3-dimensional coordination framework [Cu3(btc)2] where btc= 1,3,5-benzenetricarboxylate. This structure consists of octahedral supramolecular cages that link through their vertices to form a cubic framework with a Pt3O4 net containing distorted square units (paddlewheels) and regular planar triangular units. The NTE behavior was thought to involve transverse vibrations of the btc units coupled with rotation of the paddlewheels. Inelastic neutron scattering along with molecular dynamics simulations indicated that NTE in this material arises from local relief of framework frustration through distortion of the paddlewheel units leading to a distribution of paddlewheel arrangements. While the undistorted paddlewheel arrangement is the lowest overall energy arrangement, some groups of energy levels are lower in the distorted arrangement. In summary, the NTE in this material is more complex than for other known systems. Towards High Impact, High Throughput Chemical Crystallography With Neutrons Alison J. Edwards (The Bragg Institute, ANSTO, Australia) in her talk first described chemical crystallography as those materials included in the Cambridge crystallographic database (CCDC) which continue to grow at an increasing rate. However, neutron single crystal studies in the CCDC have been decreasing recently. She speculated that perhaps there are a large number of unpublished results as for X-ray deteminations. She also discussed trends in papers published in journals and suggested that there are fewer chemists routinely pursuing neutron diffraction studies. She then discussed the new Laue diffractometer KOALA in her facility. The first data collection was done in June 2008. She described using the instrument to determine the "simple" structure of Zn(CN)2. She then discussed results for a lanthanum crown coordination polymer and a ytterbium crown coordination polymer. VISIT TO THE OAK RIDGE SPALLATION NEUTRON SOURCE FACILITY     Some of the attendees visiting the Oak Ridge Spallation Neutron Source (SNS) facility SCENES FROM THE WELCOME RECEPTION          ABOUT THE MEETING SCENE The Meeting Scene e-mails are compiled and edited by Dr. Gopal Rao, Web Science Editor, Materials Research Society  Additional contributors include Dr. Eugenia Kharlampieva (Georgia Institute of Technology) and Dr. Alice I. Smith (Acatrinei) (Los Alamos National Laboratory)  Eugenia Kharlampieva You have received this as a subscriber to the Meeting Scene or as a member of the NSSA. To Unsubscribe, please e-mail braughler@mrs.org. Archived Meeting Scene Issues are available online. View all free MRS e-newsletters and alertsand subscribe. |
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2楼2009-05-06 19:15:13