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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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Jill Bradshaw (1968-2018)

[Jill Bradshaw]We are sorry to report the passing of Jill Bradshaw, following a long illness. Jill was a key member of staff in the IUCr Editorial Office in Chester, where she was the Managing Editor of Acta Crystallographica Section B. Jill joined us in the summer of 1993, following a spell as a production editor at Pergamon Press, where she worked after graduating from the University of Sheffield. Jill mainly acted as an editor on Acta Crystallographica Section B, and authors of this journal in particular will remember her for the efficient way that she handled their papers and the kind and diplomatic way in which she handled correspondence and queries.

In the summer this year, we celebrated Jill's 25th anniversary with the IUCr. Jill was determined to attend and, despite being unwell, was able to be cheerful and positive during a long afternoon of celebrations. All the staff in Chester will miss Jill - we have lost a highly valued colleague and friend.

Posted 10 Oct 2018 

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Gautam Desiraju awarded ISA Medal for Science 2018

[Gautam Desiraju]The Academic Board of the Institute of Advanced Studies (ISA) of the University of Bologna, Italy, has awarded the ISA Medal for Science 2018 to Professor Gautam R. Desiraju (IIS, Bangalore, India). The ISA Medal for Science is the highest honour awarded by the Institute to scholars who are acknowledged worldwide for their scientific stature and the broad impact of their research.

The award ceremony will take place on 12 October 2018 in the VIII centenario lecture hall. After receiving the ISA Medal from the Magnifico Rettore, Professor Desiraju will deliver the Lectio Magistralis "Science and society. What do they owe each other?". More information is available here.

Professor Desiraju served on the IUCr Executive Committee as President from 2011 to 2014 and as Immediate Past President until 2017, and was Chair of the 2017 IUCr Congress in Hyderabad, India. As a structural chemist, he has played a fundamental role in the development and growth of crystal engineering, bringing his expertise to IUCr Journals Acta Cryst. B and currently as Main Editor of IUCrJ.

Posted 09 Oct 2018 

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The importance of careful refinement

[fabry]

A large number of structural determinations of compounds containing 2-hydroxy-3,5-dinitrobenzoic acid and its various deprotonated forms, 2-hydroxy-3,5-dinitrobenzoate or 2-carboxy-4,6-dinitrophenolate, are biased. The reason for this follows from incorrectly applied constraints or restraints on the bridging hydrogen, which is involved in an intramolecular hydrogen bond between neighbouring carboxylic/carboxylate and oxo/hydroxy groups. This hydrogen bond belongs to the category of resonance-assisted hydrogen bonds. The position of the bridging hydrogen seems to be dependent on the pKa(base), though with some exceptions. A stronger basicity enhances the probability of the presence of a phenolate. The problem of the location and refinement of such a bridging hydrogen, as well as that of the hydrogen atoms involved in the hydroxy group, and primary and secondary amine groups, is discussed in a recent article by Fábry [Acta Cryst. (2018). E74, 1344-1357]. It appears that the best model, in many cases, is obtained by fixing the hydrogen-atom positions found in a difference electron-density map while refining its isotropic displacement parameter.

"It is almost futile to state that modern automated diffractometers have enabled single-crystal X-ray structure analysis to become widely applied even by non-experts," commented Dr Fábry. "At the same time, however, it is important to emphasize that a large number of structure determinations of even simple molecules suffer from defects that are caused by inappropriately applied constraints or restraints. These defects bias not only the structure determinations themselves but also - more importantly - the overall information contained in the crystallographic databases. The present study of a whole family of the title molecules demonstrates the importance of careful refinement as well as of inspection of difference electron-density maps. I hope that this experience will reach especially those scientists for whom crystallography is not their specialization but nevertheless use it in their studies."

Posted 14 Sep 2018

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Structural bioinformatics is shaping its community

[3D-BioInfo logo]A new initiative to form an ELIXIR community of structural bioinformaticians in Europe, named 3D-BioInfo, has been proposed. A launch meeting is being held on 19 October 2018 in Basel, Switzerland, and anyone interested in participating is invited to attend.

Structural bioinformatics has a broad impact across the life sciences and provides tools to archive, visualise, analyse, annotate and predict molecular structures. The science of structural bioinformatics is traditionally very strong in Europe offering many software tools, methodologies and databases, as well as community-wide prediction challenges. Its applications cover research activities from structural biology to drug discovery and personalised medicine. It is envisaged that establishing an ELIXIR Community will facilitate deeper integration of the broad range of tools and services already available.

See here for more information.

Posted 07 Sep 2018 

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Simulating cold aqueous environments on Earth and other planetary bodies

[gj5209]Liquid oceans and ice caps, along with ice crusts, have long been considered defining features of the Earth, but space missions and observations have shown that they are in fact common features among many of the solar system's outer planets and their satellites. Interactions with rock-forming materials have produced saline oceans not dissimilar in many respects to those on Earth, where mineral precipitation within frozen seawater plays a significant role in both determining global properties and regulating the environment in which a complex ecosystem of extremophiles exists. As water is considered an essential ingredient for life, the presence of oceans and ice on other solar system bodies is of great astrobiological interest. However, the details surrounding mineral precipitation in freezing environments are still poorly constrained, owing to the difficulties of sampling and ex situ preservation for laboratory analysis, meaning that predictive models have limited empirical underpinnings.

To address this, the design and performance characterization of a transmission-geometry sample cell for use in long-duration synchrotron X-ray powder diffraction studies of in situ mineral precipitation from aqueous ice–brine systems are presented in a recent article in Journal of Applied Crystallography [Thompson et al. (2018). J. Appl. Cryst. 51, 1197-1210]. The cell is capable of very slow cooling rates (e.g. 0.3 °C per day or less), and its performance is demonstrated with the results from a year-long study of the precipitation of the hydrated magnesium sulfate phase meridianiite (MgSO4·11H2O) from the MgSO4–H2O system. Evidence from the Mars Rover mission suggests that this hydrated phase is widespread on the present-day surface of Mars. However, as well as the predicted hexagonal ice and meridianiite phases, an additional hydrated sulfate phase and a disordered phase are observed.

Cold-cell experiments will produce the first in situ observations of mineral formation in freezing aquatic environments that are characteristic of oceans on Earth and other planetary objects. Such novel results will contribute to our understanding of the global processes that occur on, and shape, such bodies.

Posted 14 Aug 2018

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Sine Larsen awarded the Tenth Max Perutz Prize of the ECA

[Sine Larsen]From the website of the European Crystallographic Association:

The Tenth Max Perutz Prize of the European Crystallographic Association (ECA) has been awarded to Professor Sine Larsen from the Department of Chemistry, University of Copenhagen, Denmark.

The Max Perutz Prize is awarded in recognition of Sine Larsen’s multi-faceted contributions to crystallography, including crystal structure analyses of organic molecules and proteins, charge density studies, and the development of synchrotron radiation facilities. Sine Larsen has served crystallographic science and related disciplines in important leadership roles.

Sine Larsen will receive the Prize at the Opening Ceremony of the 31st European Crystallographic Meeting in Oviedo (Spain) on 22 August 2018. On this occasion she will present her Award Lecture.

Professor Larsen served on the IUCr Executive Committee as General Secretary and Treasurer from 1993 to 2005, as President from 2008 to 2011 and as Immediate Past President until 2014.
Posted 07 Aug 2018