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International Union of Crystallography

The IUCr is an International Scientific Union. Its objectives are to promote international cooperation in crystallography and to contribute to all aspects of crystallography, to promote international publication of crystallographic research, to facilitate standardization of methods, units, nomenclatures and symbols, and to form a focus for the relations of crystallography to other sciences.

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CODATA Prize 2014 awarded to Professor Sydney Hall

[Professor Sydney R. Hall]Professor Sydney R. Hall, now Emeritus Professor at the University of Western Australia in Perth, Australia, through life-long leadership has resoundingly produced outstanding achievements in the world of scientific and technical data. His efforts have reached beyond crystallographic data and into many other science disciplines. He devised a universal self-defining text archive and retrieval (STAR) file format that evolved into the Crystallographic Information Framework (CIF), a momentous contribution in the area of data characterisation, and well known to structural chemists and biologists in particular as both a data and publications standard.  It enables data validation for articles published by IUCr journals, an approach pioneered by Professor Hall in his role during the 1990s as Editor of Acta Crystallographica Section C: Crystal Structure Communications. The CIF standard has been adopted by journals publishing crystal structure results. It also forms the essential core for data in prominent databases such as the Cambridge Structural Database (> half a million entries, growing by more than 40,000 each year) and the Protein Data Bank (> 100,000 entries, growing by ~ 10,000 per year). These databases are widely used by researchers from many science disciplines. In addition, the STAR File approach is being applied to such diverse applications as botanical taxonomy, quantum chemistry, chemical informatics and biographical databases.

Sydney Hall will receive the Prize at SciDataCon 2014, the International Conference on Data Sharing and Integration for Global Sustainability, in New Delhi, 2-5 November 2014.  This is the continuation of the CODATA Conference series, now co-organised with CODATA’s sister organisation, the ICSU World Data System.

John R. Helliwell and Brian McMahon

From the CODATA web site:

The CODATA Prize is a major biennial award which acknowledges outstanding achievement in the world of scientific and technical data.  The work of Professor Sydney Hall certainly meets these criteria and the CODATA Prize Committee is very pleased to recognise his outstanding contribution.  It is particularly fitting that a crystallographer should be so recognised during the International Year of Crystallography.
Posted 15 Oct 2014 

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Towards controlled dislocations

Crystallographic defects or irregularities (known as dislocations) are often found within crystalline materials. Two main types of dislocation exist: edge and screw type. However, dislocations found in real materials tend to be a mix of these two types, resulting in a complex atomic arrangement not found in bulk crystals. The study of these dislocations in semiconductors is probably as old as the science of semiconductors itself, and the technological importance of dislocations can hardly be overstated. From their roles in the way crystals form to their effects on a material’s mechanical, thermal and opto-electronic properties, dislocation and defects govern many aspects of a material’s behaviour. Therefore, it is of great scientific interest to identify and study these structures, and understand their impact on the properties of technologically important materials and devices, such as solar cells, photon detectors and similar semiconductor devices.  

lk5001thumbnail.gifDespite the large amount of theoretical work in this field, experimental knowledge detailing the atomically resolved chemical structure of even the most basic dislocations has just begun to be accessible. A group of scientists from the United States has combined state-of-the-art atomic-resolution Z-contrast imaging and X-ray spectroscopy in a scanning transmission electron microscope (STEM) to analyse two low-elastic-energy stair-rod dislocations in the binary II-VI semiconductor CdTe. CdTe is commercially used in thin-film photovoltaics owing to its ideal electrical properties. The conversion efficiency of CdTe solar cells, which is critical for the industry, has only seen minor developments and improvements over the last 20 years despite intense research activity. Current laboratory records are still shy of the theoretical limits quoted as far back as 1961.  

In the current issue of Acta Crystallographica Section A: Foundations and Advances, Klie and co-workers demonstrate how, with the use of atomic-resolution STEM images and specially tailored Burgers circuits, the structure of these dislocations can be identified [Paulauskas et al. (2014). Acta Cryst. A70; doi:10.1107/S2053273314019639]. The results may lead to the eventual improvement in the conversion efficiency of CdTe solar cells. The analysis presented by the authors can also be applied to study and predict similar structures in other zinc-blende and diamond materials. This study further demonstrates how the new generation of aberration-corrected electron microscopes can advance our understanding of seemingly basic crystal-structure defects.

Posted 17 Oct 2014 

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The Zürich School of Crystallography 2015: Bring Your Own Crystals

[Zurich School 2013]Time is running out to get your applications in to attend the ever popular Zürich School of Crystallography.

The School, organized and directed by Anthony Linden and Hans-Beat Bürgi, is being hosted by the Department of Chemistry at the University of Zürich, Switzerland. The next course will be taking place from 7 to 20 June 2015. The course is ideally suited to Masters and PhD students and postdocs in the molecular and solid-state sciences who do not have access to crystallographic courses at their own institution.

Participants will gain hands-on experience in the science and art of a routine crystal and molecular structure determination of small molecules through lectures, computer exercises and practical work. Theoretical topics in crystal growth, unit cells, space groups, the phase problem, structure refinement and strategies for dealing with difficult structures will be covered. Practical sessions will cover instrumentation, crystal selection and mounting, data collection and exposure to commonly used software and interpretation of program output to name but a few. During the School, students will have the unique opportunity to use one of the five available X-ray diffractometers to collect data and determine the structure of one of their own compounds that they are currently interested in and that they have not worked on before.

Ten tutors experienced in all aspects of chemical crystallography will be on hand to teach the theoretical and practical aspects of this sometimes complex science. The class usually contains no more than 20 students ensuring plenty of individual tuition and guidance throughout the School. This personal attention is probably one of the most unusual aspects of the School. At the end of the School, participants give a ten minute presentation of the results of their analysis.

Comments from a past student of the School include, “Now I feel more confident in evaluating my crystal structure solutions”. Successfully completing the course also has the added bonus of offering 3 ECT credit points, equivalent to 90 contact hours.

To find out more about the School and to apply please visit here.

Posted 15 Oct 2014 

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Crystallography in Africa

ry5062thumnail.jpgAt present there are active crystallographers in only about 80 countries. The IUCr Executive Committee is keen to change this and promote crystallography globally and in particular in developing regions. The IUCr Crystallography in Africa initiative sets out to increase the number of African countries active in crystallography.

During IYCr2014 another project was mounted to build capacity in crystallography not only in Africa but also in Asia and Latin America. IUCr and UNESCO are running open laboratories (OpenLabs) in more than a dozen developing countries throughout the year in partnership with diffractometer manufacturers. These OpenLabs demonstrate how a diffractometer works to university students and their professors and particularly promote crystallography, which supports most scientific research today. Currently OpenLabs have taken place in Pakistan, Argentina, Morocco, Ghana, Cambodia, Uruguay, Indonesia and Turkey, with more scheduled for this year and with plans to continue the programme once IYCr2014 comes to an end.

See details of the forthcoming IYCr Pan African and South African Summit meeting on Crystallography taking place in Bloemfontein, South Africa between 12 and 17 October 2014.

A recent paper resulting in part from the initiative in Africa has been published in Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials entitled "Two-dimensionally stacked heterometallic layers hosting a discrete chair dodecameric ring of water clusters: synthesis and structural study" [Kenfack Tsobnang et al. (2014). Acta Cryst. B70, 900-902; doi:10.1107/S2052520614019921]. The crystallographers from Cameroon and France have characterized the self-assembly of ionic complexes built around an original water cluster.

Despite numerous research projects over the years, many of the properties of water are still misunderstood. Considering water is one of the simplest compounds in existence and so essential to life, it is fascinating and puzzling at the same time that so little is actually known about its behaviour and properties. The paper published by Patrice Kenfack Tsobnang and colleagues may provide further insight into some of the fascinating properties of water due to its infinite hydrogen-bonded network. This may help researchers understand some of the mystery that still exists in the behaviour of water in nature.

Posted 09 Oct 2014 

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IUCr news digest 6 October 2014

The IUCr-UNESCO OpenLab Uruguay was held in Montevideo on 23-31 July 2014 in partnership with Bruker. The successful meeting was attended by 20 young professors and advanced PhD students from Argentina, Brazil, Costa Rica, Colombia, Perú and Uruguay. During the Opening Ceremony of the OpenLab, the official inauguration of the Single Crystal X-ray Diffraction Laboratory of the Facultad de Quimica, Universidad de la República, took place. The intensive OpenLab included 14 hours of lectures and 12 hours of practical sessions on the history and fundamentals of crystallography. One full day was devoted to the collection of data and a number of the group brought their own single crystals and were able to collect data and make structure determinations and refinement of their own structures on site. For the more advanced student there was a special topic lecture on charge-density analysis, which was very well received. The final morning of the event was devoted to presentations by the participants themselves. Those who had solved their structures showed their results, discussed their problems and received advice on how to finalize their work from other participants and lecturers.

The IUCr-UNESCO OpenFactory took place between 10 and 19 September with sponsorship and active[participants at STOE HQ] participation from STOE, DECTRIS and Xenocs. It involved 20 young scientists from 15 different countries, some of whom had come from the immensely successful First European Crystallography School in Pavia a few days before. A highlight of the meeting was a keynote talk by Professor Gautam Desiraju (IUCr Immediate Past President) on the topic "100 years of crystallography: seen through 15 small molecule crystal structures". More information about the OpenFactory can be found in a STOE press release and in a recent article in Wiley's ChemViews Magazine.

[Delegates group photo]

IUCr-UNESCO Latin American Summit took place in Campinas, Brazil from 22 to 24 September with support from a number of organisations and bodies. This was the second Summit Meeting of the IYCr and this time the scientific theme was biological crystallography and complementary methods. Over 100 senior scientists, young researchers, postdoctoral fellows and students from 12 countries met at the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas.

Delegates enjoyed a mix of lectures on the history of Latin American crystallography and examples of current, cutting-edge research and the collaborative programmes that are taking place in Latin America. Professor Marvin Hackert (President, IUCr) gave the opening lecture on IYCr2014 and the role and benefits of the OpenLabs and Summit Meetings. Dr Lidia Brito (Regional Director for Latin American for UNESCO) spoke about the partnership of UNESCO with the IUCr on IYCr2014. Professor Glaucius Oliva (IFSC/USP) presented an overview of the history of crystallography in Latin America, while Dr Antônio José Roque da Silva (LNLS) presented a glimpse of the future with the construction of a fourth-generation synchrotron (Sirius) at Campinas.

A memorable highlight of the Summit was the keynote lecture given by Nobel Laureate Ada Yonath who discussed the progress to design better therapeutics from our understanding of the structure of the ribosome.

Another highlight was a Roundtable discussion mediated by Professor Samar Hasnain (Editor-in-Chief of IUCr Journals) where the panelists reflected on the changes, opportunities and challenges facing the further development of crystallography in Latin America. At the close of the final session, a petition was presented and unanimously approved by those attending to ask for continued support from the IUCr and UNESCO to promote regional scientific collaborations in Latin America, with a pledge to partner in supporting these activities from regional resources. More information and a full description of the programme can be found here.

Posted 06 Oct 2014 

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Fingerprinting haemprotein crystal structures

A group of scientists from Europe and the USA have successfully used high-resolution X-ray crystallography alongside resonance Raman Spectroscopy to “fingerprint” and validate different redox and ligand states in crystal structures of proteins in order to gain maximum functional information and to avoid, for example, the misinterpretation of reaction mechanisms. This breakthrough may prevent future inaccurate predictions in the structure and role of proteins. [Kekilli et al. (2014), Acta Cryst. D70, 1289-1296; doi: doi:10.1107/S1399004714004039]

[resonance Raman spectra]The combined resonance Raman (RR) and crystallographic data described in the paper demonstrate that online RR spectroscopy is a powerful tool for fingerprinting both redox and ligand states in single crystals of haemproteins.This approach allows information on vibrational states to be gained and, if performed on-axis, is particularly useful for large crystals, where UV-visible absorption micro-spectrophotometry is not feasible owing to the opacity of the haemprotein crystals.

Single-crystal spectroscopies particularly when applied in situ at macromolecular crystallography beamlines, allow spectroscopic investigations of redox and ligand states and the identification of reaction intermediates in protein crystals during the collection of structural data. This complementary combined approach to structure determination has proved to be a powerful tool to obtain useful data and correctly assign the true oxidation and ligand state(s) in redox-protein crystals.

In this study the scientists successfully present a comprehensive, correlated single-crystal resonance Raman and structural study of Alcaligenes xylosoxidans cytochrome c prime (AxCYTcp) in its ferric, ferrous and gas ligand-bound forms as well as characterizing X-ray induced changes to these states. The researchers went on to demonstrate that redox and ligand states in crystal structures can quite effectively be spectroscopically fingerprinted in situ on a macromolecular crystallography beamline, in this case at Swiss Light Source beamline X10SA.

This methodology, if applied routinely to structural studies of haemproteins, has the potential to radically increase and complement the biological significance of the results gained from crystallographic experiments, such as redox-dependent biological mechanisms.

Lead researcher Dr Mike Hough at the School of Biological Sciences, University of Essex, commented, "The resonance Raman technique is applicable to many protein crystals that contain chromophores. UV-visible spectroscopy has been used quite successfully for similar purposes however as a surface technique, resonance is very useful for larger crystals which are often opaque to light and also gives information on vibrational properties".

The technique is robust and could be rolled-out across many X-ray crystallography beamlines or more importantly as an integral part of future beamlines.

Posted 30 Sep 2014