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Journal ArticleDOI

J. Appl. Cryst.の発刊に際して

10 Mar 1970-Vol. 12, Iss: 1, pp 1-1
About: The article was published on 1970-03-10 and is currently open access. It has received 8159 citations till now.
Citations
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Journal ArticleDOI
TL;DR: VT crystallography, DFT calculations and magnetic susceptibility studies reveal a strong temperature dependence of the intra-dimer exchange interaction with J/k ~ -254 + 0.0007T(2) ; a first example of a hydrazyl radical dimer with a thermally accessible triplet state.

44 citations

Journal ArticleDOI
TL;DR: The coordination chemistry of a series of pro-ligands ([L¹]-[L⁶]) with cobalt and zinc derivatives has been studied to yield polymers under solvent free conditions with controlled molecular masses and narrow polydispersities.
Abstract: The coordination chemistry of a series of pro-ligands ([L¹]-[L⁶]) with cobalt and zinc derivatives has been studied. All complexes have been characterized by multinuclear NMR, elemental analysis, and by single-crystal X-ray diffraction studies. Polymerization of rac-lactide takes place at 130 °C in the presence of cobalt and zinc complexes to yield polymers under solvent free conditions with controlled molecular masses and narrow polydispersities.

43 citations

Journal ArticleDOI
TL;DR: The beamline performance is illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr-doped manganites and the structural deformation in nickel perovskites under high applied pressure.
Abstract: An energy-dispersive X-ray absorption spectroscopy beamline mainly dedicated to X-ray magnetic circular dichroism (XMCD) and material science under extreme conditions has been implemented in a bending-magnet port at the Brazilian Synchrotron Light Laboratory. Here the beamline technical characteristics are described, including the most important aspects of the mechanics, optical elements and detection set-up. The beamline performance is then illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr-doped manganites and the structural deformation in nickel perovskites under high applied pressure.

43 citations


Cites background from "J. Appl. Cryst.の発刊に際して"

  • ...…J. Carvalho,a Régis T. Neueschwander,a Aline Y. Ramos,b Hélio C. N. Tolentino,b* Alberto Caneiro,c Nestor E. Massa,d Maria Jesus Martinez-Lope,e Jose Antonio Alonsoe and Jean-Paul Itiéf aLaboratório Nacional de Luz Sı́ncrotron – LNLS, CP6192, 13084-971 Campinas, SP, Brazil, bInstitut Néel,…...

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  • ...The peculiar capability of an EDXAS spectrometer is to collect full absorption spectra through a parallel detection scheme over an extended range of photon energies without any mechanical movement (Phizackerley et al., 1983; Dartyge et al., 1986)....

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  • ...17, 93–102 doi:10.1107/S0909049509041119 93 Journal of Synchrotron Radiation ISSN 0909-0495 Received 16 May 2009 Accepted 8 October 2009 # 2010 International Union of Crystallography Printed in Singapore – all rights reserved Energy-dispersive X-ray absorption spectroscopy at LNLS: investigation on strongly correlated metal oxides Júlio C. Cezar,a‡2Narcizo M. Souza-Neto,a}4Cı́nthia Piamonteze,a§6 Edilson Tamura,a‡‡8Flávio Garcia,a Edson J. Carvalho,a Régis T. Neueschwander,a Aline Y. Ramos,b Hélio C. N. Tolentino,b* Alberto Caneiro,c Nestor E. Massa,d Maria Jesus Martinez-Lope,e Jose Antonio Alonsoe and Jean-Paul Itiéf aLaboratório Nacional de Luz Sı́ncrotron – LNLS, CP6192, 13084-971 Campinas, SP, Brazil, bInstitut Néel, CNRS and UJF, BP 166, 38042 Grenoble, France, cComision Nacional de Energia Atómica, Centro Atomico Bariloche and Instituto Balseiro, Bariloche, Argentina, dLaboratorio Nacional de Investigacion y Servicios en Espectroscopia Optica – CEQUINOR, Universidad Nacional de La Plata, La Plata, Argentina, eInstituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, Madrid, Spain, and fSynchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, France....

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Journal Article
TL;DR: The International Union of Crystallography (IOUC) developed an ontology for the crystallization community as mentioned in this paper, which is based on the XDX workshop organized by several international large scale crystallization screening laboratories.
Abstract: When crystallization screening is conducted many outcomes are observed but typically the only trial recorded in the literature is the condition that yielded the crystal(s) used for subsequent diffraction studies. The initial hit that was optimized and the results of all the other trials are lost. These missing results contain information that would be useful for an improved general understanding of crystallization. This paper provides a report of a crystallization data exchange (XDX) workshop organized by several international large-scale crystallization screening laboratories to discuss how this information may be captured and utilized. A group that administers a significant fraction of the worlds crystallization screening results was convened, together with chemical and structural data informaticians and computational scientists who specialize in creating and analysing large disparate data sets. The development of a crystallization ontology for the crystallization community was proposed. This paper (by the attendees of the workshop) provides the thoughts and rationale leading to this conclusion. This is brought to the attention of the wider audience of crystallographers so that they are aware of these early efforts and can contribute to the process going forward. © 2012 International Union of Crystallography All rights reserved.

43 citations

Journal ArticleDOI
TL;DR: Hardware and software solutions for MX data-collection strategies using the EMBL/ESRF miniaturized multi-axis goniometer head are presented.
Abstract: Most macromolecular crystallography (MX) diffraction experiments at synchrotrons use a single-axis goniometer. This markedly contrasts with small-molecule crystallography, in which the majority of the diffraction data are collected using multi-axis goniometers. A novel miniaturized κ-gonio­meter head, the MK3, has been developed to allow macromolecular crystals to be aligned. It is available on the majority of the structural biology beamlines at the ESRF, as well as elsewhere. In addition, the Strategy for the Alignment of Crystals (STAC) software package has been developed to facilitate the use of the MK3 and other similar devices. Use of the MK3 and STAC is streamlined by their incorporation into online analysis tools such as EDNA. The current use of STAC and MK3 on the MX beamlines at the ESRF is discussed. It is shown that the alignment of macromolecular crystals can result in improved diffraction data quality compared with data obtained from randomly aligned crystals.

43 citations


Cites background from "J. Appl. Cryst.の発刊に際して"

  • ...In addition, an experimental phasing protocol incorporating the anisotropy of anomalous scattering contributions from the intrinsic polarization of synchrotron radiation has been reported (Bricogne et al., 2005; Schiltz & Bricogne, 2008)....

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  • ...Such -goniometers maximize the reciprocal-space coverage and allow all reflections to be accurately measured....

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References
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Journal ArticleDOI
TL;DR: The goals of the PDB are described, the systems in place for data deposition and access, how to obtain further information and plans for the future development of the resource are described.
Abstract: The Protein Data Bank (PDB; http://www.rcsb.org/pdb/ ) is the single worldwide archive of structural data of biological macromolecules. This paper describes the goals of the PDB, the systems in place for data deposition and access, how to obtain further information, and near-term plans for the future development of the resource.

34,239 citations

Journal ArticleDOI
TL;DR: New features added to the refinement program SHELXL since 2008 are described and explained.
Abstract: The improvements in the crystal structure refinement program SHELXL have been closely coupled with the development and increasing importance of the CIF (Crystallographic Information Framework) format for validating and archiving crystal structures. An important simplification is that now only one file in CIF format (for convenience, referred to simply as `a CIF') containing embedded reflection data and SHELXL instructions is needed for a complete structure archive; the program SHREDCIF can be used to extract the .hkl and .ins files required for further refinement with SHELXL. Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. SHELXL is available free to academics for the Windows, Linux and Mac OS X operating systems, and is particularly suitable for multiple-core processors.

28,425 citations

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TL;DR: CCP4mg is a project that aims to provide a general-purpose tool for structural biologists, providing tools for X-ray structure solution, structure comparison and analysis, and publication-quality graphics.
Abstract: CCP4mg is a project that aims to provide a general-purpose tool for structural biologists, providing tools for X-ray structure solution, structure comparison and analysis, and publication-quality graphics. The map-fitting tools are available as a stand-alone package, distributed as `Coot'.

27,505 citations

Journal ArticleDOI
TL;DR: The PHENIX software for macromolecular structure determination is described and its uses and benefits are described.
Abstract: Macromolecular X-ray crystallography is routinely applied to understand biological processes at a molecular level. How­ever, significant time and effort are still required to solve and complete many of these structures because of the need for manual interpretation of complex numerical data using many software packages and the repeated use of interactive three-dimensional graphics. PHENIX has been developed to provide a comprehensive system for macromolecular crystallo­graphic structure solution with an emphasis on the automation of all procedures. This has relied on the development of algorithms that minimize or eliminate subjective input, the development of algorithms that automate procedures that are traditionally performed by hand and, finally, the development of a framework that allows a tight integration between the algorithms.

18,531 citations

Journal ArticleDOI
TL;DR: A description is given of Phaser-2.1: software for phasing macromolecular crystal structures by molecular replacement and single-wavelength anomalous dispersion phasing.
Abstract: Phaser is a program for phasing macromolecular crystal structures by both molecular replacement and experimental phasing methods. The novel phasing algorithms implemented in Phaser have been developed using maximum likelihood and multivariate statistics. For molecular replacement, the new algorithms have proved to be significantly better than traditional methods in discriminating correct solutions from noise, and for single-wavelength anomalous dispersion experimental phasing, the new algorithms, which account for correlations between F+ and F−, give better phases (lower mean phase error with respect to the phases given by the refined structure) than those that use mean F and anomalous differences ΔF. One of the design concepts of Phaser was that it be capable of a high degree of automation. To this end, Phaser (written in C++) can be called directly from Python, although it can also be called using traditional CCP4 keyword-style input. Phaser is a platform for future development of improved phasing methods and their release, including source code, to the crystallographic community.

17,755 citations