Bookmark and Share

International Union of Crystallography XVII Congress and General Assembly

Computing Advances and Applications (03.02)

This Open Commission Meeting of the IUCr Comm. on Crystallographic Computing provided a general overview of new developments in the field. New software (by G. Cascarano) and algorithms (G. Zanotti) for the direct solution and the refinement of small and macro-molecules from single-crystal data and of small molecules from powder and electron diffraction data were presented. The most outstanding development reported is the possibility of extending automatic direct-methods techniques from the traditional small-molecule field to more difficult problems, including single isomorphous protein data. The second general topic was databases and data exchange. The lively presentation of B. McMahon on the usefulness and versatility of the CIF files, as a standard means for exchanging crystallographic data, was followed with great interest. The two last communications were on software for charge density studies (T. Richter), which are becoming more and more popular with the increased availability of accurate low temperature data, and techniques for deriving force-field parameters (S. J. Maginn) for the modeling of weak interactions which are essential for crystal engineering and structure prediction.

Davide Viterbo
At the "very pricey" banquet. Seated (l to r): Martine Cox, Clifford G. Shull, David Cox, Terry Sabine, standing (l to r): Julie Bouckaert, Hans Overeem, Adrian Lapthorn, Aina Cohen, Jason O'Neill.

Biological Small Molecules

Ligand control of biological processes was emphasized in the Microsymposium Small Molecule Based Drug Design (5.01). Topics discussed included glycogen phosphorylase inhibitors, conformational analyses of ligands, and ligand-receptor databases. The session highlight was J. Clardy's fascinating report of a complex between an immunosuppressive drug (rapamycin) and a binding protein (FKBP12) and a binding domain for the complex (FRAP). Rapamycin occupies hydrophobic binding pockets in both proteins at the same time. Since the proteins have few interactions with each other, it is the rapamycin molecule that holds them together. Human FRAP is a very large protein involved in cell cycle progression. When rapamycin and FKBP12 binds to human FRAP, it can interrupt signals from the interleukin-2 receptor and suppress immune response. Rapamycin's "matchmaker" function has exciting implications for gene therapy because the induced dimerization of proteins could be used to regulate cellular processes.

Connie Chidester

Organic, Organometallic and Coordination Compounds (07.00)

A provocative talk by C. Krüger concerned electron deformation density studies that suggested errors in published Structures. The most stunning results were those on disordered metal atoms in simple phosphine structures. While many of the errors discussed had only minor effect on geometric parameters, the distortions that arose as a result of not considering the errors were often non-trivial. Krüger astonished the audience with the claim that up to 10% of published structures could be in error. Equally controversial was a demonstration that data collected on a SMART system was of little use when applied to electron density calculations. Krüger presented a phosphine structure in which experiment, calculation and CAD-4 data led to the assignment of a partial negative charge on the phosphorus; using SMART data resulted in a partial positive charge! The strength of SMART data was illustrated in elegant studies of hydrogen-bonding in organometallic chemistry (L. Brammer), and some beautiful metal clusters containing up to 40 atoms (C. Campana).

Simon Bott

Inorganic and Mineral Compounds

The compact representation of space group symmetry by orbifolds presented in the Microsymposium on Inorganic and Mineral Compounds (08.00) by C. Johnson led naturally into D. Brown's attempt to match the chemical properties of atoms with those of Wyckoff positions, and the demonstration by S. Borisov (reported by L. Aslanov) that the heavy ions in inorganic crystals often lie on cubic face- or body-centered lattices with a spacing of around 5Å. Techniques for finding similar structures in databases were addressed by H. Burzlaff (an algebraic approach, using similarity matrices), and E. Makovicky's geometric approach, in which coordination polyhedra are replaced by spheres. B. Zvyagin showed that many structures could be generated out of smaller modular units such as those found in spinel and pyroxene, and L. Cook explored the relationship between perchlorate ions and the volumes of the cavities they occupy.

I. D. Brown

Charge, Spin and Momentum Density

Comparison of Theory with Experiment (09.02) Following a thought-provoking introductory lecture by Spackman combined theory and experiment results were presented for an inorganic system, and organometallic and bio-organic crystals. For Al2O3, recent LAPW and Hartree-Fock calculations (Schwarz) were compared with results obtained from a recent synchrotron X-ray study of corundum (VanBeek). A detailed joint exp./theory study of chromium carbene complexes (Wang) focused on deformation densities, atomic charges and d-orbital populations. Lecomte discussed the application of topological analysis to H-bond interactions in biologically important systems, and convincingly demonstrated that consistent and meaningful results are now being obtained. In an excellent conclusion to the session, the chairman invited presenters of related posters to speak briefly on their work, and this provided everyone with the opportunity to familiarize themselves with the variety of work in the area, and also to get to know the presenters.

K. Schwarz
At the "Weight Watchers" banquet. Seated (l to r): Durward Cruickshank, Audrey Rossmann, Philip Coppens, Carol Huber, Henk Schenk; standing (l to r): Michael Rossmann, Bebe Bugg, Jan Boeyens, Marguerite Coppens, and Charlie Bugg.

Materials Science

The very enlightening Keynote Address, Sensors and Actuators: Smart Crystals (10), of R. E. Newnham described how smart crystal materials find applications in cars and household appliances as well as in space and military technology. Newnham described the properties of electrostrictive, magnetostrictive and shape memory sensitive materials and discussed the tremendous potential for engineering new devices. He stressed a growing trend toward miniaturization and mimicking biological functions.

A. Authier

J. M. DuBois began his Keynote Address, Applied Physics of Quasi Crystals and Applications (10.01), with a short history of quasi-crystals. He followed this with a description of the current state of the art of material preparation and structure determination using Al-Mg alloys to illustrate. He described spectroscopic experiments, and presented the theoretical background concerning electronic structure, and the physical (electric and thermal conductivity), mechanical (unusual hardness, small frictional coefficient) and chemical (resistance to corrosion} properties of quasi crystals that make them of great potential interest to industry.

Norio Kato

D. Louer began his Keynote Address, Modern Powder Diffraction In Materials Science (10.08) with a review of powder diffraction from the Debye-Hull papers (1916) to the First Int'l Powder Diffraction conf. (1995). He went on to describe his recent use of a tuneable synchrotron source in a study of InSb at 5.1 GPa using In Kα radiation. He describes important innovations in powder diffraction methods including time resolution studies with neutron diffraction (an in situ study of α-MnO2 during electrochemical reduction), a 3rd generation Search-Match routine that uses the completely digitized diffraction pattern, and the application of the Rietveld method to quantitative analysis. Most noteworthy was progress in ab initio structure determination using direct methods, Patterson and Fourier maps, the maximum entropy principle, simulated annealing, Monte Carlo method, and the atom-atom potential method. The complexity of the structures that can be solved may eventually rival those from single crystal data.

Hugo Steinfink

Stress levels and strain measurement are very important issues in the growth of thin films. Whether introduced by design, or unwanted artefacts, it is of considerable interest to establish reliable methods for their evaluation. Techniques can be used include Raman or luminescence spectroscopy, curvature measurement, computer modelling, and diffraction techniques based on neutron, X-ray or electron crystallography. The Microsymposium Strain and Stress Measurements (10.03) concentrated on the two last mentioned techniques. Convergent beam electron diffraction techniques offer modest strain sensitivities at very high spatial resolution whereas X-ray diffraction gives very high strain sensitivity with modest resolution. The X-ray strain measurements of P. Fewster (Philips Research), using a high resolution multiple-crystal multiple-reflection diffractometer on GaAs, gave absolute values of the lattice parameter, accurate to better than 1 in 105. At this level of sensitivity even reference crystals were found to be potentially unreliable standards because the lattice parameters varied with the scattering depth of the measurement. It becomes necessary to make careful choice of the Bragg reflections used in the measurements. When strained layers were grown on the substrate it was found that substrate distortions also occur and had to be taken into account. J. M. Zuo showed that in order to achieve the highest spatial resolutions in electron diffraction careful choice of zone axis is required. High symmetry axes give rise to channelling effects that actually reduce the size of an existing beam relative to that of the incident focused probe and allow measurements to be made with 1 nm spatial resolution. J. Mayer gave an impressive demonstration of measurement of strains in aluminium on silicon substrates at the 1 in 104 level using electron diffraction. He introduced Hough transforms and stressed the need for full dynamical theory calculations for work at this level of accuracy. A. Armigliato (CNR, Bologna) gave a beautiful demonstration of the utility of more routine sensitivities (5 in 104) and spatial resolutions (10 nm) in studying strains introduced into silicon by LOPOS technology. His results showed impressive agreement with model calculations.

J. W. Steeds

The Microsymposium and poster session on Aperiodic Structures and Incommensurate Phases (10.04) covered quasicrystals, incommensurate and misfit or composite structures and some polytypes. Many cases of disorder revealed by diffuse scattering patterns have been studied in icosahedral and decagonal crystals. The presentations of F. Denoyer and P. Gibbons included discussion of arcs of diffuse scattering and their interpretation and modeling. R. Colella described a dynamical scattering experiment carefully designed to obtain absolute values of structure factors. The problem of structural resolution of decagonal phases was solved by T. Haibach by successful combination of maximum entropy and N-dimensional Patterson methods. S. Schmid revealed the consistent appearance of similar modulation functions despite variability of chemical compositions. Molecular dynamical techniques used to understand the origin of incommensurate structures of inorganic compounds presented by V. B. Gaillard seemed very promising.

G. Chapuis
At the "outrageously overpriced" banquet seated (l to r): Lotte Brehm, Rolf Norrestam, Jan-Eric Berg, Berit Fjaertoft-Pedersen; standing (l to r): Ingeborg Csoregh, Niels Thorup, Yuhui Yin, Eric De La Fortelle, Graziella Gramaccioli, and Carlo Gramaccioli.

S. Abrahams began the session on Optic/Electronic Materials (10.07) with a discussion on how to search for new ferroelectric and ferroelastic materials. He showed that approximately 8% of all inorganic structures are polar and thus a look through the inorganic database reveals at least another 200 potential ferroelectric crystals to be studied. P. Thomas then gave a spirited talk on periodic domain inverted (PDI) crystals. The formation of PDI crystals is an important development in the field of optical second harmonic generation (SHG). These structures have the capability of virtually eliminating phase mismatching that normally limits the use of optical crystals in SHG applications. Pam showed that crystallography has an important role to play in both developing PDI and in studying what happens when domains are inverted. E. Belokoneva discussed a family of non-linear optical crystals based on KTiOPO4, with illustrations of many related structures of germanates and silicates. D. Keszler followed the non-linear optical theme by showing that aluminium borate crystals had high non-linearities which could even be predicted by simple theory. Finally, L. Bohaty demonstrated the occurrence of a truly huge number of potential electroptic crystals simply by studying the known space groups of many hundreds of chemical species.

A. M. Glazer

The Microsymposium Powder Diffraction (10.08) spanned topics from limits on precision and accuracy, to data collection protocols, uses of magnetic neutron diffraction and anomalous X-ray dispersion, characterization of multilayers, depth profiling, and the determinations of polymer electrolyte structures. A highlight was the presentation by W. David who described the achievement of markedly superior fits of observed and calculated diffraction profiles in Rietveld refinement through the use of independent peak shape and width parameters. The method very effectively deals with the issue of anisotropic peak characteristics and allows the determination of structural results that are independent of (and therefore unbiased by) the peak shape model. Evidence for the 'saturation' of esd's at long counting times was provided, along with a strong recommendation for the use of variable step counting time protocols during data collection. A method of decoupling the structure and peak contributions was described by D. Cox of BNL, this time through the fixing of peak parameters at the values determined during a pre-Rietveld LeBail-type refinement. M. Kovalchuk presented a comprehensive description of the use of X-ray standing waves as a sensitive probe for the characterization of multilayers on single crystal surfaces, while F. Bouree gave a comprehensive description of the key steps in the determination of magnetic structures from powder neutron diffraction data. P. Lightfoot presented an elegant and visually stunning description of the ab initio determination of the crystal structures of polymeric materials through the use of Monte Carlo and constrained Rietveld refinement methods.

R. J. Hill

The Microsymposium Fullerenes (10.11) illustrated that fullerenes continue to excite the imagination and stimulate creative research. One is reminded about the tale of several blind men and an elephant; each one described the elephant as something vastly different, depending upon whether they touched its leg, trunk, ear, tail, etc. The first view came from M. Takata , who described powder x-ray experiments using image plates at Photon Factory, in conjunction with maximum entropy analysis of the data. His group has been able to locate Y and Sc atoms inside the fullerene cages, as well as to resolve the atomic structure of the carbon cage. R. Moret spoke on diffuse X-ray scattering from orientational fluctuations in C60 crystals. H. Terrones discussed a model for the nearly spherical graphitic onions which have been observed, explaining a mechanism of shell growth that would suppress the expected faceting of successive layers. A. Balch described the work in his laboratory on chemical modifications; while everybody seems to like fullerenes, it takes a synthetic chemist to hug and kiss them. G. Faigel spoke about some alkali fullerides, comparing the conducting polymer and insulating dimer phases of [K,Rb,Cs]C60. Finally, K. Prassides discussed the crystallographic properties of heterofullerenes C59N and their fullerides.

Peter Stephens

The Microsymposium on Advanced Battery and Fuel Cell Materials (10.13) focused on the structures of transition metal oxide insertion electrodes for rechargeable lithium batteries which are finding increasing application as power sources for laptop computers, cellular phones and camcorders. Structures of oxygen-ion conductors for high temperature fuel cells also featured prominently in the program. The presentations highlighted the importance of understanding structure-property relationships on a fundamental level; such knowledge is being successfully used to tailor the structures of electroactive materials to improve their performance in electrochemical cells. M. Mansuetco of Argonne National Lab. demonstrated with neutron diffraction data how the framework structure of α-manganese dioxide could be stabilized by reaction with lithium oxide (rather than a cation, such as Ba2+ or K+) to provide an electrode with significantly improved electrochemical stability over conventional α-MnO2 materials. Other highlights of the conference included contributions from Per and Kia Onnerud. Per gave an elegant description of cation and anion disorder in pyrochlore structures, e.g. Y2(ZryTi1-y)O7 and discussed the relationship between these structures and high oxygen-ion conductivity at elevated temperature (1000°C). Kia gave detailed accounts of lithiated V6O13 structures and the development of a very rapid processing method to produce crystalline LiMn2O4 (spinel) electrode structures. R. Kanno extended the discussion of spinel electrode materials to spinel solid electrolytes Li2MX4 (X-halogen) that showed high Li-ion conductivity at elevated temperatures. A highlight of the poster session was G. Burr's presentation of an in situ structure analysis of deuterated LaNi5Dx and Al-substituted LaNi5-yAlyDx electrodes that were obtained during the discharge of nickel-metal hydride cells, the first time that such experiments on metal hydride electrodes have been successfully undertaken. The data showed remarkable agreement between the amount of deuterium within the electrode determined electrochemically during discharge and structurally by profile refinement of the neutron data.

Michael Thackeray
At the "disgracefully expensive" banquet seated (l to r): Sandy Blake, Joyce Buchanan, Peter Young, Helen Berman, Janet Thornton; standing (l to r): Kenneth Shankland, Chuji Katayama, Philip Lightfoot, Michael Bolte, and Peter Keller.

Structure Property Relationship

Chemical crystallography is such a broad field that it is impossible to address all topics in a single session. The Microsymposium Chemical Crystallography of the Future (11.02) addressed a few of the most interesting and timely topics. R. Boese described two new crystallization techniques, an in situ IR-laser miniature zone refining procedure for low melting samples and a cooling device, equipped with a video system, which controls the seeding/growth process. In a multi-media-moving-picture lecture, A. Pinkerton described the ability of CCD area detector systems to collect data from 20-50 micron crystals with sufficient accuracy to allow electrostatic potential studies. Y. Ohashi also described collection of full data sets in 2 hours using a double-imaging-plate diffractometer allowing him to trace time-resolved solid state reactions. Even faster data set collection will be possible when a new CCD system is completed. B. Kahr presented a fascinating discussion of the colors of crystals, the mechanisms of the dyeing process and the structures of the "dyed" crystals. Antipin presented charge density maps with 'inverted bent bond' non-classical three-center-two-electron and classical two-electron-two-center bonds existing side by side. Finally, S. Motherwell discussed perspectives on future data retrieval from the Cambridge Database and techniques being used to check crystal structures for errors.

R. Boese

Molecular motions of atoms in crystals have been modeled on data from low-temperature X-ray and neutron crystallography, X-ray and energy dispersive diffuse scattering, neutron and far-infrared spectroscopy, and solid-state nuclear magnetic resonance. Applications described in the Microsymposium Dynamic Properties in Molecular Crystals (11.03) ranged from molecular to biomacromolecular crystals with particular regard to: calculated motions and side-chain dynamics in protein crystals, n-fold reorientational dynamics in substituted cubane crystals, rigid and non-rigid motion in highly flexible nitrogen compounds, rotational disorder in adamantane, order-disorder phenomena in cyclodextrine and calix[4]arene inclusion compounds, and thermal motion in crystals displaying antiferroelectric-paraelectric transitions. A number of common aspects of the dynamical behaviour of molecules in crystals could be discerned in the various presentations.

G. Gilli

The Microsymposium Solid State Reactions: Structural Therm. and Kinetics Aspects (11.04) covered studies of a wide range of reactions within organic, inorganic and metallic crystals. The first lecture was concerned with problems of methyl transfer, which occur sometimes in the solid state but more usually in the melt. Experiment showed that the methyl groups were transferred in an intermolecular fashion, and that sometimes a particular overall reaction occurred by more than one mechanism. Photochemical reactions initiated by light at absorption maxima generally take place on the surface of the crystals but can be induced to occur within the bulk of the crystal if the initiating light comes from the tail of the absorption band. This gives many advantages in the study of photochemical reactions in crystals. A unifying factor for the solid state reactions of inorganic crystals was found to be provided by the strain induced in a crystal as a result of a reaction. This determines the kinetics and spatial pattern of the reaction as well as the structure and morphology of the solid state products. Phase equilibria in metallic systems have recently been predicted co be composition dependent if the precipitated phase is coherent, and high temperature in situ experiments have demonstrated this effect for a Ni-24 atomic % V alloy. Finally, the thermal decomposition of alkali metal salts of halogenocarboxylic acids has been shown to give the metal salt and a polymeric product, and experiments have shown how the detailed structure and composition of the polymer depends on the decomposition conditions.

Frank Herbstein
At the "pathetic rabbit food" banquet seated (l to r): Nick Grichine, Hong Zhang, Betsy Goldsmith, Tony Santoro; standing (l to r): Michal Harel, Steven Sheriff, Adnan Goldman, Alan Mighell, Eva Holzel, and Alexander Holzel.

Surfaces

In his Keynote Address Structures of Surfaces Studied By X-ray Diffraction (12) R. Feidenhans'l reviewed the general principles of X-ray diffraction from crystal surfaces and described the techniques used to measure and analyze the spectrum and discussed interesting examples of crystal surface structures analysis.

J. Harada

In the Microsymposium Surface and Interface Crystallography (12.01) S. Ferrer described (he low-temperature structure of Ge(001) in which dimers were found to interact laterally, K. Akimoto showed the formation of ordered structures at the AgSi (111) interface, and H. Schultz had convincing evidence of vacancy and interstitial defects in the InSb(111) surface. The application of maximum-entropy analysis methods was pursued for the Si (111) 7 × 7 surface by C. Cavartho, with a comparison of Fourier and ME maps. C. Lucas reported a study of coabsorption structures of Cu and Br electrochemically deposited on Pt (111), including an interesting CuBr monolayer phase. Finally, D. Walko analyzed diffuse scattering around truncation rods of Cu (110) in terms of island distributions arising from deposition of Cu at low temperatures.

I. Robinson

Fiber Diffraction

In the second session on fiber diffraction, Methods of Structure Determination (13.02), M. Tsuji described how 'lattice images' from high resolution electron microscopy of drawn fibers could be used to characterize local variations of crystallinity. Using relatively radiation-resistant aromatic polymers and aliphatic chains in a liquid helium-cooled sample holder, high resolution images and fiber diffraction data were used by I. G. Voight-Martin to characterize liquid crystalline polymers and demonstrate that electron crystallographic structure analyses of monomers could provide new insights into the nature of mesogenic polymer solids. Crystal structures of polymers based on single crystal electron or fiber X-ray diffraction data were discussed by S. V. Meille, D. L. Dorset and M. P. McCourt. In the first talk in the series, polymorphs of poly (pivalolactone) and isotactic polypropylene were described and their quantitative crystal structures analyzed by conformational search procedures. The second talk dealt with the applicability of direct phasing methods for determining structures without the use of molecular models. The last talk showed how model fitting could be used to resolve atomic structure after direct phase determination, when data sampling was incomplete. N. S. Murthy described how two dimensional profile fitting could be used to determine the distribution of crystallites in a drawn sample. A complete description of the types of disorder in fiber samples and their effect on experimental diffraction data was given by R. P. Millane.

D.L. Dorset
At the "I nearly starved to death" banquet seated (l to r): Sieglinde Kuppers, Horst Kuppers, Marie Louise Jeitschko and Wolfgang Jeitschko, Peter Paufler, standing (l to r): Norbert Wiehl, Lenore Wiehl, Gisela Klapper, Helmut Klapper, and Wolfgang Schmahl.

Small Angle Scattering

In the first of two SAS microsymposia (14.01), we were treated to a tantalizing treatise on the tools and techniques of small angle scattering. The application of these tools and techniques was the focus of the second Microsymposium, Applications (14.02), which drew a large, attentive, and participatory audience. Here we were introduced to an array of SAS applications with material subjects ranging from ribosomes, eye lens cataracts and muscle to mesogens, alkanes, micelles, peptides and proteins. H. Stuhrmann led the charge with a masterfully gesticulated discussion of polarized neutron scattering and its use in deciphering ribosome structure. Hot on Heinrich's heels was A. M. Levelut with her announcement and colorful description of a novel class of mesophases composed of "crystals of defects" observed in chiral thermotropic mesogens. Next up was S. Perkins, who delighted the crowd with a most convincing protocol for automated SAS curve modeling as applied to a variety of multidomain proteins. It works! A. Tardieu, the next speaker, spell-bound the audience when she introduced her topic with a rather graphic photograph of eye lenses. At one point in the presentation, I could have sworn I saw one of them wink. But I must admit that my new bifocals are taking some getting used to. Undaunted, Annette went on to describe how SAS is being used to understand the nature of the interactions of the crystallins, proteins responsible for transparency in the healthy eye lens and for opacity in cataracts. The mechanism of muscle contraction and how this is being investigated at a structural level using state-of-the-art synchrotron X-ray sources was addressed by T. Irving. Tom presented a convincing case for undulation based beam lines at third generation synchrotron facilities. Now, aJl we have to hope for is that radiation damage does not compromise these measurements. Phase separation at a microscopic level in binary long chain alkanes was reported on by E. Gilbert. This fascinating process, referred to as microphase separation, involves the slippage of molecules along their long axis to form interleaved lamellae of distinct compositions in bulk alkanes. Next on the mat was J. Pedersen who introduced us to his pet giant worm-like micelles, composed of lecithin, organic solvent, and water. Jan showed how SAS and Monte Carlo simulations have been used to characterize the structure of these polymer-like micelles at the level of cylindrical cross-sectional profile, size distribution and persistence length. The session ended with a tour-de-force examination of the structures that the anti-microbial peptides, alamethicin and magainin in solid substrate supported lipidic bilayers. In this study, the power of in-plane neutron scattering as a tool for investigating membrane structure was demonstrated convincingly by D. Worcester, co-chair of the Microsymposium. The session closed with a photo opportunity for speakers and chair alike. There was unanimous agreement among the subjects and the photographer that Prof. Stuhrmann not display his infamous, signature hand-wave (see, for example, photo of Prof. Stuhrmann on Page 12 of IUCr Newsletter Vol. 3, No.3) during this very serious occasion.

M. Caffrey

Diffraction Physics

T. Koetzle starred his Keynote Address, Neutron Diffraction Studies of Coordination and Organometallic (15), with a brief comparison of the similarities and differences between the scattering of X-rays and neutrons by solid samples. He emphasized the potential uses of neutron radiation for the discrimination of different isotopes, the analysis of magnetic structures for the precise positioning of light atoms, and stressed that neutrons and X-rays can be complementary in crystallographic research. Most of the examples he presented involved elastic scattering measurements on single crystals of organometallic and coordination complexes. Koetzle showed how neutron diffraction experiments have been crucial in discovering new types of bonding systems, for example, interactions involving metals and two atoms linked by an s-bond. He described the characterization of classical and non-classical transition metal polyhydrides and the discrimination between types of complexes and mechanisms.

F. Lahoz

Information on the XVIII Congress and General Assembly of the IUCr is available at chem.gla.ac.uk/iucr99/. Inquiries and suggestions can be sent to the local chair, C. Gilmore at iucr99@chem.gla.ac.uk. The winner of the logo competition was M. McMahon (Dept of Physics, Edinburgh U., and Daresbury Lab). The dual themes are the thistle for Scotland and the C60 molecule, which was found by H. Kroto (Sussex U.) in collaboration with others, and many British Crystallographers have since worked on its crystal structure.

Winning Logo Losing Logo