ECM29

Rovinj, Croatia, August 2015
http://ecm29.ecanews.org

Venue of ECM29, the Adris exhibition and convention centre, a renovated old tobacco factory complex which is listed as a historical monument of fin-de-siècle industrial architecture.

Aleksandar Višnjevac, Chair of the Organizing Committee, officially opened the Meeting.

The 29th European Crystallographic Meeting took place in Rovinj, Croatia, August 23-28, 2015, and was extremely successful. A total of 1052 crystallographers from 52 countries met in Rovinj to attend the scientific sessions in the fascinating location of a renovated old tobacco factory complex representing an extraordinary example of the fin-de-siècle industrial architecture of the late 19th century. A high participation of young researchers was registered, with over 200 students, and 80 exhibitors who contributed to profitable discussions and a very lively atmosphere aside the lectures. The Congress was opened with the Ode to Joy performed by A. Rucner (Croatia), followed by welcome addresses given by the ECA President A. Roodt (South Africa), the chair of the organizing committee A. Višnjevac (Croatia) and the Assistant Minister of the Ministry of Science, Education and Sports of the Republic of Croatia, R. B. Lučić (Croatia).

John R. Helliwell, recipient of the 8th Max Perutz Prize.

During the opening ceremony the 8th Max Perutz Prize was awarded to J. R. Helliwell (UK) for his long, generous and fruitful dedication to developing all aspects of the use of synchrotron radiation for crystallography and for his boosting support to global development of synchrotron and neutron facilities. The Opening Ceremony was animated by traditional Croatian songs a capella performed by klapa 'Motovun'.

Plenary speaker Henry Chapman.

Plenary speaker Andrea Ferrari.

The scientific program was opened by the plenary lecture 'Serial crystallography with X-ray free-electron laser pulses' by H. Chapman (Germany), and was closed with the plenary lecture 'Graphene future emerging technology' by A. Ferrari (UK). Over the four days of the conference, 50 microsymposia and 16 keynote lectures embraced the latest advances in all aspects of crystallography; a very well attended special session 'How to' was devoted to give young crystallographers hints and suggestions on their next future career outside academia. Besides the main conference, ten well-attended satellite meetings were run, among them the very successful young crystallographers' satellite meeting.

IUCr President, Marv Hackert (left), with IUCr Poster Prize winners Anton Brausemann (Germany) and Eleonora Conterosito (Italy).

Poster Prize winner Matteo Alvaro (Italy).

Marijana Đaković

Participants at the Welcome Reception.

Student mixer for Young Crystallographers

The Gala dinner.

The IUCr Executive Committee met during ECM29. (l to r) Front row: Santiago García-Granda, Malcolm Cooper, Mitchell Guss, Marvin Hackert, Jane Robinson, Hanna Dabkowska and Michael Dacombe; back row: Luc Van Meervelt, Radomir Kuzel, Wulf Depmeier, Mike Glazer, Masaki Takata, Brian McMahon and Peter Strickland.

There were 20 poster prizes awarded at the closing ceremony which was officiated by M. Đaković, Co-chair of the Organizing Committee. Additional photos can be found at http://ecm29.ecanews.org

MS4: Advances in phasing, refinement and autobuilding

Speakers in this session on macromolecule techniques included:

I. Uso (Italy), developer of ARCIMBOLDO. This software (i) uses molecular replacement techniques to find positions of small structural fragments in the unit cell, and (ii) tests how well they kick-start autobuilding. The procedure works in cases where the resolution is 2 Å (or better) and there are sufficient computing resources to run the multiple tests.

V. Lamzin (Germany) described new developments in Arp/Warp. The detection of NCS at early stages of the rebuilding process means it has been successful at resolutions down to 3 Å. Another powerful feature is the detection of ligand density. Likely 'shapes' are evaluated against a library of common fragments.

A. D. Finke (Switzerland). As synchrotrons allow more seamless data-collection protocols, old methods can be reintroduced. It is possible with careful crystal alignment on a multi-axis goniometer to collect high-multiplicity data of equivalent Bijvoet pairs at much the same time, reducing the systematic errors in the anomalous signal introduced by radiation damage and enhancing the chance to solve the phase problem.

K. Diederichs (Germany) urged the community to beware of RULES for data-quality evaluation, which can be useful but need to be re-examined in the light of first principles. He gave two examples: (i) Data-processing statistics such as R_merge measure the precision of data (i.e. how well multiple observations agree) and not their inherent accuracy. For instance, measuring multiple reflections with different absorption pathways will increase R_merge but improve the accuracy of the observation. (ii) R values based on different selections of observations cannot be validly compared.

A. Thorn (UK) raised the issue of the relatively poor agreement between observed and calculated F_obs. She showed how plots of F_obs versus resolution did not fully fit the predicted Wilson plot features, and sparked a vigorous debate on why this might be so - suggestions included 'Ice rings?', 'Poor solvent modelling?' 'Secondary structure artefacts?'

MS5: Structure and function of enzymes

It is now possible to visualize successive steps of an enzymatic reaction via the use of XFEL, where one can collect serial femtosecond X-ray data. P. Fromme (USA), 'SFX - The dawn of a new era in structural biology'. In parallel, the development of general photoactive reagents makes it easier to trigger enzymatic reactions in crystals. D. Monteiro (UK), 'Towards a general approach for the time-resolved crystallographic study of enzymes'. As more enzymes are found in integral membranes, it has become very exciting to compare their structure and functions to equivalent soluble enzymes. A. Goldman (UK), 'New structures of T. Marittima integral membrane pyrophosphatase suggest a conserved coupling mechanism for proton and sodium transport'. Finally, it has now become standard practice to combine crystallography with a multitude of additional techniques to fully characterize the targets of interest, if in healthy systems or disease. M. Cygler (Canada), 'Effector proteins from pathogenic bacteria: focus on kinases' and A. Wang (Taiwan), 'An integrative approach targeting phophatase substrate complexes for new cancer drug design strategy'.

MS13: New instrumentation, methods and approaches in inorganic crystallography

The symposium covered a broad range of topics from X-ray powder diffraction analysis (R. Cerny, Switzerland) to the ultimate electron diffraction analysis, based on statistical approaches (A. Eggeman, UK) or dynamical refinement of 3D data (L. Palatinus, Czech Rep.). Applications of the free electron laser snapshot crystallography at the SwissFEL (C. Dejoie, Switzerland), and the benefit of the 'cluster approach' for the X-ray analysis of intermetallic compounds (D. Proserpio, Italy) were also described. Six posters concerned both X-ray and electron diffraction developments.

MS14: Mineralogical crystallography: Nature as a source of inspiration for new materials

The papers presented in this symposium ranged from the hydrothermal synthesis and structural characterization of new phases, to the study of imogolite nanotubes and naturally occurring metal-organic framework (MOF) compounds. Several papers were focused on the use of porous materials in different applications, such as the treatment of nuclear waste or the polymerization of organic molecules. Many non-ambient studies, HT and HP, on various mineral and mineral-like phases were presented.

MS15: Structure property relationships

Detailed understanding of structure-property relationships is a key motivation for many crystallographic studies and this session attracted attention from practically all branches of the community. It highlighted the overlap between different areas of crystallography and covered neutron and X-ray diffraction, physical and chemical properties, as well as hard, soft and hybrid materials. The session included contributions with variation of sample composition, pressure and temperature for materials as diverse as molecular materials, metal oxynitrates, borohydrides/boranes and metal-organic frameworks.

M. Lusi (U. of Limerick) talked about 'Design and synthesis of molecular materials: mixed crystals for finer engineering' and emphasized the possibilities of solvent-free synthesis of mixed crystals. J. P. Attfield (U. of Edinburgh) discussed the 'Structure property relationships arising from anion order in solid oxynitrides', an emerging class of materials with interesting optical, photocatalytic, dielectric and magnetoresistive properties that may be sensitive to oxide-nitrade order.

P. Schouwink's (U. of Geneva) talk 'Energy-related aspects of complex metal borohydrides and higher boranes: beyond hydrogen storage' demonstrated that there is a great potential for achieving high ionic conductivity and that the numerous compounds studied for their hydrogen sorption properties are promising candidates for other energy-related applications. A. Comotti (U. of Milano Bicocca) 'Molecular rotors in nonporous periodic architectures' provided insight into the dynamics of molecular rotating dipoles. I. Collings (U. of Bayreuth) 'Structure-property relations in multiferroic metal-organic frameworks at high pressure' discussed how the magnetic metals MOFs couple to the ferroelectric guest ions and how physical pressure studies can guide the design of the MOFs with improved multiferroic properties.

MS18: Thermoelectric materials - from fundamental science to applications

For the first time an ECM featured a symposium on thermoelectric materials. These materials are challenging for crystallographers, due to their complex crystallographic structures and the impact of micro/nanostructure on thermoelectric properties. Methods covered included neutron and X-ray diffraction, theoretical calculations and electron microscopy. Y. Grin (Switzerland) demonstrated the crucial role of the inhomogeneity and anisotropy of chemical bonding in thermoelectric materials. The problem of 'rattling atoms' was addressed by M. Koza (France) who used neutron spectroscopy to show that the classical view on the vibration of rattlers is much too simplified.

MS20: High-pressure solid-state chemistry

Contributions to this symposium included studies of inorganic and organic solids, minerals, polymers, pharmaceuticals and other materials. 25 scientists from 10 countries took part in MS20 and related poster sessions: four oral presentations were given by representatives of Austria, Denmark, Germany, Japan, and UK; 21 posters were on display presenting research in Austria, Croatia, Denmark, Germany, Italy, Poland, Russian Federation, South Africa and UK. Young scientists made great contributions. M. Schmitt (Austria) presented high-pressure synthesis and characterization of the new nickel borate HP-NiB₄O₇, whose structure type was hitherto unknown in the field of borate chemistry, underlining the importance of the parameter 'pressure' in synthetic solid-state chemistry. J. Sotelo (UK) presented high-pressure structural data on the microporous scandium framework, Sc₂BDC₃ (BDC = benzene-1,4-dicarboxylate) with included methane molecules from 2 to 25 kbar. This research is providing in-depth structural insight into the adsorption/desorption mechanism of metal-organic frameworks (MOFs) that might have important implications for the development of new methods of storing, trapping or separating light gases, such as CO₂ or CH₄. An invited talk delivered by U. Schwarz (Germany) on high-pressure high-temperature synthesis of new covalent metals offered insight into recent preparation, results and physical properties of binary compounds comprising covalent framework patterns.

MS23: Nanoscale structures

The symposium featured many high-quality contributions, with 27 abstracts in total. The subjects of the oral and poster presentations extended from electron microscopy via X-ray diffraction, absorption and scattering studies to theoretical modeling and software development, with a strong focus on nanoscale diffraction techniques. Metal nanoparticles, semiconductor nanowires and quantum dots, functional oxides, electronic materials and organic-inorganic hybrid nanostructures were highlighted. The important contribution of crystallography to this emerging field of science became obvious.

During recent years, substantial instrumental developments in electron diffraction, such as aberration-corrected TEM and STEM, X-ray analysis and X-ray nanoprobe beamlines at various synchrotrons worldwide, have revolutionized the possibility of crystallography on nanoscale structures. The invited talks at the microsymposium, given by internationally recognized experts (P. Boullay, France, and U. Pietsch, Germany), provided an exciting overview including excellent examples of the novel potential within both fields. Contributed talks covered total scattering (A. Guagliardi, Italy), coherent diffraction imaging and ptychography (V. Favre-Nicolin, France) and in situ studies of nanoparticles in liquid environments (M. Zobel, Germany). The symposium included experienced senior scientists and promising young researchers.

MS26: Modulated, modular and composite materials

Aperiodic structures were the focus of this symposium. A. Abakumov (Belgium) presented a superspace description of a complex superstructure of a perovskite, supporting the displacive-like origin of the distortion instead of a phase separation proposed in previous models. C. Müller (Sweden) reported a superspace model of the intermetallic compound Cu₃Sn, which shows an intriguing feature: only odd satellites are observed. She was able to explain this fact using triangle-like occupation domains.

C. Mariette (France) analyzed critical phenomena in a composite compound where alkane chains are confined in honeycomb-like urea sublattices. Together with the phonon branches in incommensurately modulated composite structures, the low-frequency phason excitations could explain the large length correlations along the direction of the misfit. B. Stöger (Austria) focused on the phenomenon of allo-twinning, the oriented association of two or more polytypes of the same compound. Some examples of structure determination of allo-twinnings were presented. Finally, A. Gagor (Poland) analyzed the commensurate-incommensurate phase transition of the semiconducting hybrid (2-MI_m)BiI₄. The possible relation between the variation on the Bi-Bi distance coming from the sinusoidal modulation and the physical properties of the material were also discussed.

MS27: Electron crystallography methods

Invited lectures covered the extreme ends of the field, with J. P. Abrahams (Netherlands) discussing techniques for imaging and diffraction of biological and biomedical samples, while David Cooper (LETI, Grenoble) highlighted the current state-of-the-art for strain mapping in semiconductor samples.

R. Beanland (UK) showed the latest developments from digital LACBED measurements, combining automated beam controls, image processing and fast simulations for accurate refinement of diffraction data. M. Gemmi (Italy) contrasted the various protocols for 3D electron diffraction measurements to optimize the amount of information recorded for a given electron dose. Finally, T. Gorelick (Germany) reported the application of PDF analysis to electron diffraction data.

The poster sessions continued to highlight the range of research in electron crystallography, with presentations on the methods for 3D electron crystallography of a wide range of organic, inorganic and hybrid materials. A special mention should be made of the two electron crystallography poster prizewinners: D. Johnstone (UK) and C. Correa (Czech Republic).

MS29: Quasi-crystals and aperiodic materials

This microsymposium focused on the latest theoretical and methodological advances with structure determination and analysis of aperiodic crystals and how structural features influence their physical properties.

In his talk on 'Statistical description of icosahedral quasicrystals,' R. Strzalka (Poland) proposed three-dimensional structure modeling in physical space as an alternative to modeling in higher-dimensional space. In 'Long-range ordered magnetic and atomic structures of the quasicrystal approximant in the Tb-Au-Si system,' G. Gebresenbut (Sweden) described a new strategy for crystal synthesis with first results on atomic and magnetic structures. S. Ben-Abraham (Israel) addressed in 'Three-dimensional eight-color structure' a two-dimensional chair substitution tiling based on eight cubic prototiles, and showed how to generalize the structure to additional dimensions. In 'Quasiperiodic canonical-cell tiling with cubic symmetry,' N. Fujita (Japan) discussed a new inflation rule for the canonical cells, proposing an inflation step factor (being the golden mean); E. Zupanič (Slovenia) considered 'Unit-cell twinning in quasi-crystals', an alternative understanding of the unit cell to recover quasi-crystalline reciprocal space.

MS33: Mechanical effects and properties of ordered matter

Elastic materials that are capable of mechanical reconfiguration induced by external stimuli are indispensable for the fabrication of mechanically tunable elements for actuation and energy harvesting, including flexible electronics, artificial muscles and microfluidic elements. The most challenging practical difficulties with structural analysis of deformations of macroscopic-size single crystals are those caused by the large molecular structural changes and the significant strain that develops over the long-range structural order in these closely packed structures. Accumulation of strain can cause deterioration, sublimation, twinning and other forms of undesirable crystal disintegration. In order to maximize the performance of the mechanical response while keeping the fatigue at a minimum, these issues can be resolved by a combined approach that includes both intrinsic and external factors. This microsymposium included lectures that reflect the historical developments as well as the current status in the emerging field of mechanically-responsive crystalline materials. By including talks both from some of the leading researchers as well by some rising stars in the field, the symposium highlighted the recent interest in mechanical characterization of molecular crystals.

E. Boldyreva (Russia) opened the symposium with a wonderful overview of over three decades of research on mechanical effects in crystals, focusing on bending of single crystals induced by linkage isomerization. L. Alimi (South Africa) presented a report on a new compound that shows the thermosalient effect, where crystals explode as they undergo thermal phase transition. D. Levendis (South Africa) described an interesting case where a new mechanical effect is observed with a 'classical' photochemical reaction - photodimerization of o-ethoxycinnamic acid whose crystals undergo multiple mechanical effects during the reaction. P. Zolotarev (Russia) gave an in-depth overview of the topological and energetic aspects of identification of cleavage planes in crystals. G. Ramon (South Africa) concluded the session with a beautiful example of a solvent-responsive coordination network that 'breathes' by uptake and release of solvent.

MS39: Recent advances in diffraction instruments, detectors and data processing

S. Capelli (UK) described recent developments for 2D detectors, data collection and data-processing software in single-crystal neutron diffraction. M. Brunelli (France) addressed structural disorder in doped ceria compounds. Defects were investigated by following the structural evolution of doped ceria compounds at different length scales. M. Blakeley (France) discussed neutron macromolecular crystallography at the Inst. Laue-Langevin and exciting new details of protein-ligand interactions relevant to HIV, and protonation shifts related to enzyme pathways. A. Casanas (Switzerland) described the advantages of the EIGER detector for combining fast frame-rate, very short dead-time and higher rotation speeds in collecting data, and highlighted the numerous advantages associated with higher rotation speeds data collection on challenging crystals. Finally, S. Smeets (Switzerland) described the collection of data, in broad-bandpass mode, and a new algorithm for the indexing of data collected in single-snapshot mode with either monochromatic or broad-band pass radiation.

MS44: New applications of old algorithms in crystallography

This symposium revisited classical algorithms that with new twists are being applied to current crystallographic problems. It covered structure solution, refinement and validation in macromolecular, chemical and materials crystallography. Both single-crystal and powder diffraction methods were presented.

D. Turk (Slovenia) addressed the problems that are caused by omitting the test set of reflections that is used to calculate the free R factor. This has been used for almost 30 years to validate macromolecular structure refinements. The test set is also used to parameterize maximum likelihood (ML) refinement. As an alternative that does not require data to be omitted, he presented the ML free-kick refinement algorithm that removes model bias by small random displacement of atomic positions.

C. Jelsch (France) presented subatomic charge-density refinement of small macromolecules against ultra-high resolution data, now extended to predict molecular properties through developments in the program MoPro that has its roots in the Hansen and Coppens program MOLLY. MoPro is endowed with automation, visualization and analysis tools, a charge-density database and a graphical user interface.

R. Oeffner (UK) convincingly illustrated progress in the most widely used macromolecular phasing method, molecular replacement, targeted to increase the success in difficult cases with borderline models. He described and evaluated improvement of the located models by occupancy refinement against the ML target. He showed how to rescue solutions that would have been eliminated by phantom packing clashes. The resulting solutions provide superior starting structures for model building and refinement by removing the model bias burden of the incorrect regions.

M. Schmidt (USA) imparted a clear and engaging exposition of the use of cross-correlation functions on non-indexed powder data for the structure solution of nano-crystalline organic compounds. Successful solution of this challenging problem by global optimization of all parameters, including the cell constants, from random starts is implemented in his program FIDEL.

C. Millán (USA) presented the use of clustering algorithms in reciprocal space, evaluating mean phase differences and correlation coefficients using methods stemming from the low-resolution phasing context. Her implementation attempts to combine partial molecular replacement solutions from small fragments and has already succeeded in phasing some macromolecular structures that had resisted all previous attempts to solve them.

MS45: Chemical information as prior knowledge in crystallography

The symposium addressed the use of prior knowledge in macromolecular and small-molecule crystallography. In the opening talk, 'Fitting ensemble models of disorder using a priori chemical structure information', R.Cooper (U. of Oxford, UK) discussed the Squeeze algorithm. Rather than using an explicit atomic model of disorder, Squeeze adds a reciprocal space correction, improving geometry and parameter estimates in modelled regions. He discussed fitting ensemble models of disorder involving random sampling of occupancies, conformations and positions, utilizing prior information from known structures, providing a detailed description of disordered regions.

Addressing 'Chemical restraints in Phenix', N. Moriarty (USA) discussed the use of eLBOW for the generation of ligand restraints, derived from various sources, for use in refinement and validation, and the Conformation Dependent Library, used to generate main chain restraints based on protein backbone conformation.

In the third talk, 'SEQUENCE SLIDER: a multi-sequence evaluator and its application in venomics', R. Borges (Spain and Brazil) described how to ascertain a protein sequence from a list of possibilities. Starting from a partial model, side chains are modelled and results evaluated against diffraction data, utilizing complementary experimental information.

D. Kratzert (Germany) described 'DSR-enhanced modelling and refinement of disordered structures with SHELXL', which performs automatic fitting of models in disordered regions. This utilizes a database of fragments and restraints, allowing multiple conformations with varying occupancies.

In the final talk, 'Deriving a chemical context for protein-bound monosaccharides', J. Agirre (UK) discussed using structural fingerprinting to assess monosaccharides in the PDB, revealing the prevalence of errors in sugar conformations. Privateer utilizes such knowledge for validation.

MS47: History of crystallography and the ECA

The European Crystallographic Association (ECA) has a General Interest Group organized by Senior Crystallographers (GIG-SC). The GIG-SC addresses the needs and interests of enthusiastic but ageing crystallographers. GIG-SC has distributed a written statement addressed to the organizers of crystallographic meetings. A further document is in preparation concerning the means for senior crystallographers to publish scientific articles as open-access and to access crystallographic databases. The GIG-SC also organizes microsymposia at ECMs. At ECM29 a microsymposium entitled 'History of Crystallography and the ECA' was organized. B. Kojic-Prodic (Croatia) gave a lively talk on the development of crystallography in Croatia. S. Popovic (England) enlightened us on scientific activities of the Croatian-born physicist and engineer, N. Tesla (Croatia), who was very active at the time of the discovery of X-rays. D. Viterbo (Italy) gave a personal account of well known crystallographers that he had known. A similar theme could be found in the poster presentation of Mike Glazer, which presented the crystallographic lives of Kathleen Lonsdale and H. Megaw. J.-Louis Hodeau (Germany) took us further back in time by talking about crystallography before the discovery of X-ray diffraction. A. Wlodawer (USA) gave us a fascinating talk on the history of macromolecular crystallography.

For ECM30 in Basel, Switzerland, 2016, the organization of a microsymposium on 'Contributions to the development of crystallography' is already underway. More complete information on the GIG-SC may be found on its website.

MS48: Teaching and outreach of crystallography

In the wake of the IYCr, distinguished teachers and popularizers of crystallography from academic institutions and industry presented accounts of their work related to IYCr.

A. Linden (Switzerland) provided an overview of the well known Zurich School of Crystallography, 'Bring your own crystals' (www.chem.uzh.ch/linden/zsc/), which was launched in 2007 and is organized and directed by Linden and H.-Beat Bürgi.

V. Stilinović (Croatia), co-editor of a Croatian popular science journal Priroda (Nature) and an avid science historian, presented 'History as a tool for a crystallographic storyteller'.

D. Šišak-Jung (Switzerland), on behalf of M. Fark (Germany), described a joint project of the IUCr and several companies. They sponsored a series of worldwide admission-free schools and workshops designed to quicken the development of crystallography in less-privileged regions. After being introduced to the basics of crystallography, the students receive hands-on tutorials using modern instruments and software.

M. Zema (Italy) described an initiative of the IUCr and UNESCO. The OpenLab project was to develop crystallography in Africa, South America and Southeast Asia. A total of 15 OpenLabs, each with 20 to 30 selected participants, were organized, providing high-level educational opportunities to local students and young professors, taking advantage of the scientific and educational expertise of the IUCr, the diplomatic and educational channels of UNESCO and the partnership of crystallographic instrument manufacturers.

N. Eremin (Russia) described a Russian initiative to teach crystallography to school children. Many workshops throughout Russia were attended by hundreds of students. Since school curricula lack instruction in crystallography, the authors have created a textbook, 'Entertaining Crystallography', aimed at primary- and high-school students.

MS50: Cultural and historical aspects of crystallography

G. Cavallo (Italy) explained the role of X-ray powder diffraction in mineralogical studies of various ochres useful in dating archaeological artifacts. G. Artioli (Italy) gave a lecture about the contributions of crystallography and archaeometric approaches to understanding cultural heritage. C. Groom (UK) presented an overview of the scientific life of Frank Allen and his critical role in the creation, maintenance and use of the Cambridge Structural Database system.

In the corresponding poster session, M. Wildner (Austria) presented his 'pattern zoo' - the 17 plane groups and related periodic tilings and patterns that played and still play an important role in art and cultural history over the centuries, and P. Bezdička (Czech Rep.) explained the role of X-ray powder diffraction and Raman spectroscopy in studying the naturally irradiated fluorite, called antozonite, a rare violet pigment used in Europe in the Middle Ages.