Day 1 :
Washington University in St Louis, USA
Time : 09:10-09:50
Ramesh K Agarwal is the William Palm Professor of Engineering at Washington University in St Louis from 1994 to 2001, he was the Sam Bloomfield Distinguished Professor and Executive Director of the National Institute for Aviation Research at Wichita State University in Kansas. From 1978 to 1994, he worked in various scientific and managerial positions at McDonnell Douglas Research Laboratories in St Louis. He became the Program Director and McDonnell Douglas Fellow in 1990. He received PhD in Aeronautical Sciences from Stanford University in 1975, MS in Aeronautical Engineering from the University of Minnesota in 1969 and BS in Mechanical Engineering from Indian Institute of Technology, Kharagpur, India in 1968. He is the author and co-author of over 600 publications and serves on the editorial board of 20+ journals. He has given many plenary, keynote and invited lectures at various national and international conferences worldwide. He is a Fellow of AAAS, ASME, AIAA, IEEE, SAE, and SME.
Metamaterials are rationally designed artificial materials composed of tailored functional building blocks densely packed into an effective (crystalline) material. While metamaterials historically are primarily thought to be associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, it turns out that the simple metamaterial concept also applies to many other areas of physics namely the thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics) and in principle also to the quantum mechanics. This lecture will review the basic concepts and analogies behind the thermodynamic, acoustic, elastodynamic/elastostatic, and electromagnetic metamaterials and differences among them. It will provide an overview of the theory, the current state of the art and example applications of various types of metamaterials. The review will also discuss the homogeneous as well as inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. The application examples will include laminates, thermal cloaks, thermal concentrators and inverters, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, and mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity. Finally an example of quantum-mechanical matter-wave cloaking will be provided.
University of Virginia, USA
Time : 09:50-10:30
Zygmunt Derewenda obtained PhD and DSc degrees from the University of Lodz in Poland. His Postdoctoral studies were conducted at the University of York, UK. Prior to joining the faculty of the University of Virginia, where he is currently a Harrison Distinguished Professor of Molecular Physiology and Biological Physics, he was an Associate Professor at the University of Alberta in Edmonton, Canada. He has published more than 150 papers on a range of subjects in structural biology, which were cited over 11,000 times (H-factor 58).
Protein crystallization constitutes a major bottleneck in the high-resolution structural characterization of proteins and their complexes. It is estimated that the probability of obtaining single crystals as a result of screening ranges from less than 1% to 25%, depending on the source and biophysical properties of the target protein or complex. A further complication arises if the crystals lack diffraction quality, impeding high-resolution data collection. Nearly two decades ago we proposed a new approach to protein crystallization based on rational surface engineering to generate surface patches with an enhanced propensity to form crystal contacts. The method relies on the mutational replacement of surface residues with high conformational entropy, such as Lys and Glu/Gln with Ala or other small amino acids. The design of variants with enhanced crystallization propensity is possible using a dedicated server (http://services.mbi.ucla.edu/SER/). This methodology, known as Surface Entropy Reduction (SER), has been successfully used in hundreds of studies, not only to obtain crystals of otherwise intractable proteins or complexes, but also to generate new crystal forms with improved diffraction quality allowing to collect X-ray data to much higher resolution than that recorded for the wild-type crystals. In addition, the database of protein crystal structures determined with the help of SER provides interesting insights into the mechanistic aspects of protein crystallization.
Concordia University, Canada
Time : 10:50-11:30
Georges Dénès is a Professor in the Department of Chemistry & Biochemistry at Concordia University, Canada. He has completed his Ph.D. at Universite de Rennes I. His research interests are solid-state inorganic chemistry. He has been teaching general chemistry, inorganic (main group) chemistry and he has published articles in various journals.
Crystallography is unquestionably the most powerful method for obtaining structural data about crystalline solids. However, there are some cases where even the most powerful method can benefit from help from techniques that are not used for structural determination. In the current work, 119Sn Mossbauer spectroscopy was used to assist crystallography, for finding the tin(II) positions in the unit cell and determine a tin(II) coordination in agreement with both the diffraction data and the tin electronic structure. The first case will show that even high-quality single crystal data do not always guarantee that the right solution will be obtained. A first attempt at the structure of α−SnF2 yielded the tin positions with very reasonable R and Rw residuals, 0.23-0.25. However, the fluorine positions could not be found. After many other attempts, the full crystal structure was finally solved 14 years later. The difference in the tin position between the two solutions was that, in the latter, half of the tin atoms were on special sites, however, the tin sublattice was identical. Because the tin sites in the initial solution gave very reasonable residuals, 14 years of efforts were wasted. The presentation will show that this could have been avoided using 119Sn Mossbauer spectroscopy. This was possible since the spectrum had already been recorded. It will also be shown how Mossbauer spectroscopy can help determine the tin coordination, when combined with powder diffraction data, in the case of disordered structures. The presence of tin(II), disordered with a metal ion in cubic coordination, when diffraction shows there is no lattice distortion and no superstructure, suggests that tin has also a cubic coordination. This would require the tin lone pair to be non-stereo active, however, Mossbauer spectroscopy shows it is stereo active. The same technique helps to suggest an alternate disordered structure in agreement with the X-ray powder diffraction data. Furthermore, 119Sn Mossbauer spectroscopy was also used to assist diffraction for solving the crystal structure of a compound suffering from an extreme case of preferred orientation. The presentation will show the hurdles faced by diffraction methods alone, and how we designed the use of Mossbauer spectroscopy in order to rescue crystallography.