The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Kazumasa Ohsumi - One of the best experts on this subject based on the ideXlab platform.
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development of a microarea diffraction system by polychromatic synchrotron radiation with the Laue Method
Review of Scientific Instruments, 1995Co-Authors: Kazumasa Ohsumi, Kenji Hagiya, Masaya Uchida, Noboru Suda, Masamichi Miyamoto, Masao Kitamura, Masaaki OhmasaAbstract:Microarea diffraction equipment has been developed with a micropinhole and an imaging plate using the Laue Method combined with polychromatic synchrotron radiation. The crystal structure of 8 μm diam area of olivine [(Mg,Fe)2SiO4] grain included in a thin section of meteorite was successfully refined based on the intensities of Laue spots.
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characterization of polycrystalline al and cu metal films sputtered on sio2 si substrate using the Laue Method with synchrotron x radiation
Applied Physics Letters, 1994Co-Authors: S Yasuami, T Takase, Kazumasa OhsumiAbstract:Reflection spots from granular aluminum and copper films were recorded on imaging plates. By comparing the reflection spots with the overall illuminated area, it was estimated that the aluminum granules were several microns in dimensions. The copper granules were much smaller. The spots spread and exhibited contrast, proving that stress was present in the aluminum granules. Assuming constant lattice parameters, the orientation shift between specific points in a single granule was determined to be around half a degree. It is highly likely that the granules have suffered plastic deformation.
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characterization of 5 μm sized icosahedral chemical vapor deposited diamond by synchrotron x ray diffraction with Laue Method
Review of Scientific Instruments, 1992Co-Authors: Kazumasa Ohsumi, Kenji Hagiya, Masamichi Miyamoto, T Takase, Y Shimizugawa, Y Mitsuda, Masaaki OhmasaAbstract:A system for analyzing and refining the crystal structure of a submicrometer‐sized specimen has been developed at the Photon Factory, KEK, employing a Laue Method with an imaging plate. The system was evaluated using two molybdenum spheres with diameters of 0.8 μm and 0.27 μm3 in volume. The result showed that the isotropic temperature factors of both spheres were successfully refined, and that one of the samples was found to be twinned. The smaller domain of the twin was determined to be 0.02 μm3 in volume, which means that the smaller domain is composed of only 109 Mo atoms. The system was applied to a 5‐μm‐sized icosahedral CVD diamond as a first application. Analysis of several Laue patterns revealed that the sample is composed of more than 17 domains. Among them, 16 domains are twinned with each other, and the mode of twinning is of the spinel twin type.
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Characterization of 5‐μm‐sized icosahedral chemical vapor deposited diamond by synchrotron x‐ray diffraction with Laue Method
Review of Scientific Instruments, 1992Co-Authors: Kazumasa Ohsumi, Kenji Hagiya, Masamichi Miyamoto, T Takase, Y Shimizugawa, Y Mitsuda, Masaaki OhmasaAbstract:A system for analyzing and refining the crystal structure of a submicrometer‐sized specimen has been developed at the Photon Factory, KEK, employing a Laue Method with an imaging plate. The system was evaluated using two molybdenum spheres with diameters of 0.8 μm and 0.27 μm3 in volume. The result showed that the isotropic temperature factors of both spheres were successfully refined, and that one of the samples was found to be twinned. The smaller domain of the twin was determined to be 0.02 μm3 in volume, which means that the smaller domain is composed of only 109 Mo atoms. The system was applied to a 5‐μm‐sized icosahedral CVD diamond as a first application. Analysis of several Laue patterns revealed that the sample is composed of more than 17 domains. Among them, 16 domains are twinned with each other, and the mode of twinning is of the spinel twin type.
T Takase - One of the best experts on this subject based on the ideXlab platform.
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characterization of polycrystalline al and cu metal films sputtered on sio2 si substrate using the Laue Method with synchrotron x radiation
Applied Physics Letters, 1994Co-Authors: S Yasuami, T Takase, Kazumasa OhsumiAbstract:Reflection spots from granular aluminum and copper films were recorded on imaging plates. By comparing the reflection spots with the overall illuminated area, it was estimated that the aluminum granules were several microns in dimensions. The copper granules were much smaller. The spots spread and exhibited contrast, proving that stress was present in the aluminum granules. Assuming constant lattice parameters, the orientation shift between specific points in a single granule was determined to be around half a degree. It is highly likely that the granules have suffered plastic deformation.
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characterization of 5 μm sized icosahedral chemical vapor deposited diamond by synchrotron x ray diffraction with Laue Method
Review of Scientific Instruments, 1992Co-Authors: Kazumasa Ohsumi, Kenji Hagiya, Masamichi Miyamoto, T Takase, Y Shimizugawa, Y Mitsuda, Masaaki OhmasaAbstract:A system for analyzing and refining the crystal structure of a submicrometer‐sized specimen has been developed at the Photon Factory, KEK, employing a Laue Method with an imaging plate. The system was evaluated using two molybdenum spheres with diameters of 0.8 μm and 0.27 μm3 in volume. The result showed that the isotropic temperature factors of both spheres were successfully refined, and that one of the samples was found to be twinned. The smaller domain of the twin was determined to be 0.02 μm3 in volume, which means that the smaller domain is composed of only 109 Mo atoms. The system was applied to a 5‐μm‐sized icosahedral CVD diamond as a first application. Analysis of several Laue patterns revealed that the sample is composed of more than 17 domains. Among them, 16 domains are twinned with each other, and the mode of twinning is of the spinel twin type.
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Characterization of 5‐μm‐sized icosahedral chemical vapor deposited diamond by synchrotron x‐ray diffraction with Laue Method
Review of Scientific Instruments, 1992Co-Authors: Kazumasa Ohsumi, Kenji Hagiya, Masamichi Miyamoto, T Takase, Y Shimizugawa, Y Mitsuda, Masaaki OhmasaAbstract:A system for analyzing and refining the crystal structure of a submicrometer‐sized specimen has been developed at the Photon Factory, KEK, employing a Laue Method with an imaging plate. The system was evaluated using two molybdenum spheres with diameters of 0.8 μm and 0.27 μm3 in volume. The result showed that the isotropic temperature factors of both spheres were successfully refined, and that one of the samples was found to be twinned. The smaller domain of the twin was determined to be 0.02 μm3 in volume, which means that the smaller domain is composed of only 109 Mo atoms. The system was applied to a 5‐μm‐sized icosahedral CVD diamond as a first application. Analysis of several Laue patterns revealed that the sample is composed of more than 17 domains. Among them, 16 domains are twinned with each other, and the mode of twinning is of the spinel twin type.
Masaaki Ohmasa - One of the best experts on this subject based on the ideXlab platform.
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development of a microarea diffraction system by polychromatic synchrotron radiation with the Laue Method
Review of Scientific Instruments, 1995Co-Authors: Kazumasa Ohsumi, Kenji Hagiya, Masaya Uchida, Noboru Suda, Masamichi Miyamoto, Masao Kitamura, Masaaki OhmasaAbstract:Microarea diffraction equipment has been developed with a micropinhole and an imaging plate using the Laue Method combined with polychromatic synchrotron radiation. The crystal structure of 8 μm diam area of olivine [(Mg,Fe)2SiO4] grain included in a thin section of meteorite was successfully refined based on the intensities of Laue spots.
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characterization of 5 μm sized icosahedral chemical vapor deposited diamond by synchrotron x ray diffraction with Laue Method
Review of Scientific Instruments, 1992Co-Authors: Kazumasa Ohsumi, Kenji Hagiya, Masamichi Miyamoto, T Takase, Y Shimizugawa, Y Mitsuda, Masaaki OhmasaAbstract:A system for analyzing and refining the crystal structure of a submicrometer‐sized specimen has been developed at the Photon Factory, KEK, employing a Laue Method with an imaging plate. The system was evaluated using two molybdenum spheres with diameters of 0.8 μm and 0.27 μm3 in volume. The result showed that the isotropic temperature factors of both spheres were successfully refined, and that one of the samples was found to be twinned. The smaller domain of the twin was determined to be 0.02 μm3 in volume, which means that the smaller domain is composed of only 109 Mo atoms. The system was applied to a 5‐μm‐sized icosahedral CVD diamond as a first application. Analysis of several Laue patterns revealed that the sample is composed of more than 17 domains. Among them, 16 domains are twinned with each other, and the mode of twinning is of the spinel twin type.
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Characterization of 5‐μm‐sized icosahedral chemical vapor deposited diamond by synchrotron x‐ray diffraction with Laue Method
Review of Scientific Instruments, 1992Co-Authors: Kazumasa Ohsumi, Kenji Hagiya, Masamichi Miyamoto, T Takase, Y Shimizugawa, Y Mitsuda, Masaaki OhmasaAbstract:A system for analyzing and refining the crystal structure of a submicrometer‐sized specimen has been developed at the Photon Factory, KEK, employing a Laue Method with an imaging plate. The system was evaluated using two molybdenum spheres with diameters of 0.8 μm and 0.27 μm3 in volume. The result showed that the isotropic temperature factors of both spheres were successfully refined, and that one of the samples was found to be twinned. The smaller domain of the twin was determined to be 0.02 μm3 in volume, which means that the smaller domain is composed of only 109 Mo atoms. The system was applied to a 5‐μm‐sized icosahedral CVD diamond as a first application. Analysis of several Laue patterns revealed that the sample is composed of more than 17 domains. Among them, 16 domains are twinned with each other, and the mode of twinning is of the spinel twin type.
John R Helliwell - One of the best experts on this subject based on the ideXlab platform.
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Laue crystallography: coming of age
Journal of Synchrotron Radiation, 1999Co-Authors: Dominique Bourgeois, Keith Moffat, John R Helliwell, Vukica Šrajer, Barry L. StoddardAbstract:A renewed interest in the Laue diffraction technique has been brought about by the development of new, more intense and brilliant synchrotron sources along with their insertion devices such as wigglers and undulators, and by the prospect of using these sources to study structural dynamics by time-resolved crystallography. Theoretical studies during the past decade have identified unique features of the polychromatic diffraction geometry and greatly improved our understanding of the Laue Method. This led to innovative approaches to Laue data processing and its software implementation. Most of the problems in Laue data processing, considered for a long time to limit the applicability of the technique, have been solved. Significant advances have also been made in the development of synchrotron sources, beamline optics and instrumentation, and the X-ray detectors. Static Laue experiments yield structure amplitudes that equal those from monochromatic data in quality. When coupled with careful consideration of data-collection strategies and reaction initiation in crystals, a series of successful time-resolved Laue experiments on biological systems have been conducted. These have revealed information on structural dynamics inaccessible to any other conventional diffraction Method. These static and time-resolved experiments demonstrate that the Laue Method is coming of age. They also suggest avenues for future improvements: a correct treatment of finite mosaic spread and the associated energy width of Laue spots; consideration of diffuse scattering; and determination of intermediate structures in time-resolved experiments in which those intermediates do not attain a high concentration.
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the emergence of the synchrotron Laue Method for rapid data collection from protein crystals
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 1993Co-Authors: A Cassetta, John R Helliwell, A Deacon, C Emmerich, J Habash, Sean Mcsweeney, Edward H Snell, A W Thompson, S WeisgerberAbstract:Synchrotron X-radiation (SR) is intense, polychromatic and collimated. It is widely exploited, in macromolecular crystallography, particularly using a monochromatized short wavelength beam. The spectral curve of SR, however, ideally lends itself to use of Laue geometry, i. e. the original diffraction experimental arrangement based on a stationary crystal and a polychromatic X-ray beam. Rapid exposure times and time-resolved crystallography studies, e. g. of enzymes, are now possible. Historical objections to the use of Laue diffraction data, particularly the multiplicity distribution, have been found not to be as limiting as once thought. The credentials of the Laue Method have been established through a variety of Laue crystal structure analyses, involving photographic film as detector. Recently a three-dimensional arrangement of films, known as a toast-rack, has been used to alleviate problems with spatially overlapping spots. This paper provides a review of these results and then reports several developments. In particular, one of the first Laue analyses using an image plate as detector, namely of a cobalt substituted concanavalin A crystal, is discussed. Recent experimental developments, also at the Daresbury synchrotron, are then described. First, a large toast-rack has been used to record Laue data from a protein crystal. Secondly, a transmission X-ray mirror has been constructed from thin mylar (1.5 μm) and used to provide a λ max filter instead of using aluminium foils. Thirdly, since the Laue Method suffers from poor sampling of the low resolution data, a new Method (known as LOT) has been introduced.
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Macromolecular Crystallography with Synchrotron Radiation
1992Co-Authors: John R HelliwellAbstract:Preface Introduction 1. Fundamentals of macromolecular crystallography 2. Fundamentals of macromolecular structure 3. Sources and properties of synchrotron radiation 4. Synchrotron radiation instrumentation 5. Monochromatic data collection 6. The Laue Method 7. Diffuse X-ray scattering from macromolecular crystals 8. Variable wavelength anomalous dispersion Methods and applications More applications Conclusions and future possibilities Appendixes Bibliography References Index.
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Macromolecular crystallography using synchrotron radiation: progress on station 9.5 and a novel (toast-rack) detector scheme for Laue diffraction
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 1991Co-Authors: John R HelliwellAbstract:Abstract Synchrotron radiation is widely applied in the study of macromolecular structure using crystallographic Methods. The combined properties of the high intensity at short wavelengths and the collimation are strikingly successful in prolonging sample lifetime, improving peak to background of the intensity measurements, considerably reducing sample absorption errors, and optimising anomalous scattering of high atomic number elements bound to macromolecules for phase determination. The full polychromatic beam is used in Laue diffraction and is being perfected for quantitative X-ray crystal structure analysis. The synchrotron Laue Method allows the study of time resolved or perturbation phenomena in crystals.
Roger S Goody - One of the best experts on this subject based on the ideXlab platform.
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crystallographic studies on p21h ras using the synchrotron Laue Method improvement of crystal quality and monitoring of the gtpase reaction at different time points
Acta Crystallographica Section D-biological Crystallography, 1994Co-Authors: Axel J Scheidig, Antonieta Sanchezllorente, Alfred Lautwein, John E T Corrie, Gordon P Reid, Alfred Wittinghofer, Roger S GoodyAbstract:The parameters affecting the crystal quality of complexes between p21H-ras and caged GTP have been investigated. The use of pure diastereomers of caged GTP complexed to the more stable p21(G12P)′ mutant of p21 and the addition of n-octyl-β-d-glucopyranoside improved the reproducibility and decreased the mosaicity of the crystals significantly. Furthermore, the crystallization technique was changed from the batch Method to the sitting-drop technique. With the availability of a larger yield of well ordered crystals, it was possible to extend the time-resolved crystallographic investigations on p21H-ras. A structure of p21(G12P)′:GTP could be obtained 2 min after photolytic removal of the cage group and led to the identification of a previously unidentified conformation for the so-called catalytically active loop L4. The refinement of five data sets collected within 2 min at different times (2–4, 11–13, 20–22, 30–32 and 90–92 min) after the initiation of the intrinsic GTPase reaction of the protein indicates that the synchrotron Laue Method can be used to detect small structural changes and alternative conformations, but is presently limited in the analysis of larger rearrangements since these produce diffuse and broken electron density.
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Crystallographic studies on p21H−ras using the synchrotron Laue Method: improvement of crystal quality and monitoring of the GTPase reaction at different time points
Acta Crystallographica Section D-biological Crystallography, 1994Co-Authors: Axel J Scheidig, Alfred Lautwein, John E T Corrie, Gordon P Reid, Alfred Wittinghofer, Antonieta Sanchez-llorente, Roger S GoodyAbstract:The parameters affecting the crystal quality of complexes between p21H-ras and caged GTP have been investigated. The use of pure diastereomers of caged GTP complexed to the more stable p21(G12P)′ mutant of p21 and the addition of n-octyl-β-d-glucopyranoside improved the reproducibility and decreased the mosaicity of the crystals significantly. Furthermore, the crystallization technique was changed from the batch Method to the sitting-drop technique. With the availability of a larger yield of well ordered crystals, it was possible to extend the time-resolved crystallographic investigations on p21H-ras. A structure of p21(G12P)′:GTP could be obtained 2 min after photolytic removal of the cage group and led to the identification of a previously unidentified conformation for the so-called catalytically active loop L4. The refinement of five data sets collected within 2 min at different times (2–4, 11–13, 20–22, 30–32 and 90–92 min) after the initiation of the intrinsic GTPase reaction of the protein indicates that the synchrotron Laue Method can be used to detect small structural changes and alternative conformations, but is presently limited in the analysis of larger rearrangements since these produce diffuse and broken electron density.
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Crystallographic studies on p21(H-ras) using the synchrotron Laue Method: improvement of crystal quality and monitoring of the GTPase reaction at different time points.
Acta crystallographica. Section D Biological crystallography, 1994Co-Authors: Axel J Scheidig, Alfred Lautwein, John E T Corrie, Gordon P Reid, Alfred Wittinghofer, Antonieta Sanchez-llorente, Roger S GoodyAbstract:The parameters affecting the crystal quality of complexes between p21(H-ras) and caged GTP have been investigated. The use of pure diastereomers of caged GTP complexed to the more stable p21(G12P)' mutant of p21 and the addition of n-octyl-beta-D-glucopyranoside improved the reproducibility and decreased the mosaicity of the crystals significantly. Furthermore, the crystallization technique was changed from the batch Method to the sitting-drop technique. With the availability of a larger yield of well ordered crystals, it was possible to extend the time-resolved crystallographic investigations on p21(H-ras). A structure of p21(G12P)':GTP could be obtained 2 min after photolytic removal of the cage group and led to the identification of a previously unidentified conformation for the so-called catalytically active loop L4. The refinement of five data sets collected within 2 min at different times (2-4, 11-13, 20-22, 30-32 and 90-92 min) after the initiation of the intrinsic GTPase reaction of the protein indicates that the synchrotron Laue Method can be used to detect small structural changes and alternative conformations, but is presently limited in the analysis of larger rearrangements since these produce diffuse and broken electron density.