G. Panaccione1
Consiglio Nazionale delle Ricerche - Milano Italy
High resolution Hard X-Ray (¿ 5 keV of kinetic energy) PhotoEmission (HAXPES) has proven to be an excellent tool not only to reach high bulk sensitivity but also to directly access the electronic states near the Fermi level, i.e., to the energy scale of the electronic correlation. In this talk, a review of the recent results obtained within the VOLPE (VOLume PhotoEmission from solids) project, operational at beamline ID16 of ESRF, will be presented, together with a review of selected results from other HAXPES experimental setups. In particular, we will report results obtained on strongly correlated systems (cuprates, vanadates, manganites), where the comparison between truly bulk sensitive core level and valence band spectra i) allows a reliable estimate of the correlation term and ii) reveals new screening mechanism in transition metal oxides. Furthermore, HAXPES data from buried interfaces will be presented, where exploiting a depth sensitivity as high as 150 Angstrom, a reliable spectroscopic access to real devices or capped samples is obtained.
Acknowledgements:
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The Macromolecular Crystallography Village at the Diamond Light Source: High-throughput and automation from microfocus to MAD
G. Evans1
Diamond Light Source - Didcot Oxfor United Kingdom
Diamond Light Source is a 3rd generation synchrotron offering significant facilities for structural life science research. One component of the life sciences is a suite of six beamlines for macromolecular crystallography (MX), five of which are now in either full operation or being commissioned and one that is at the design stage. The three fully operational beamlines are high throughput MAD beamlines satisfying the majority of scientific demand. The fourth line, now in early operation, is a dedicated tuneable microfocus MX work. The fifth line is a fixed wavelength high throughput beamline. The presentation outlines these beamline facilities paying particular attention to the design and use of the I24 microfocus beamline and how it integrates with the nearby Wellcome Membrane Protein Laboratory to create a unique facility for producing diffraction quality crystals and diffraction data from very challenging structural biology projects. Results from the first year of the I24 beamline will be presented along with future plans and requirements.
Acknowledgements:
Synchrotron based X-ray microprobes: Towards a multimodal approach
J. Susini1
European Syncrotron Radiation Facility - Grenoble Cedex France
The dramatic growth of nanoscience and nanotechnologies is currently fostering the development of high spatial resolution analytical techniques [1]. In this context, syn- chrotron based techniques have the potential to become mainstream tools for anal- ysis, imaging and spectroscopy in a number of applications, as exemplified by the current evolution of hard X-ray microscopy. Hence, considering the concomitant de- velopments of laboratory instruments and dedicated synchrotron beamlines world- wide [2], a very competitive context can be anticipated for the coming years. Within this perspective, synchrotron based analytical techniques (diffraction, imaging and micro-spectroscopies) will play an important role by offering unique capabilities in the study of complex systems. Ultimately, this complexity can be envisioned in three dimensions: composition, time and space. The main fields of applications are driven by the unique attributes of X-ray microscopy in this spectral range [3]: i) access to K-absorption edges and fluorescence emission lines of medium-light ele- ments and L,M-edges of heavy materials for microspectroscopy, chemical or trace element mapping; ii) higher penetration depths compared to soft X-rays allowing imaging of thicker samples; iii) favorable wavelengths for diffraction studies and iv) generally large focal lengths and depths of focus which are advantageous for the use of specific sample environments (in-situ, high pressure, controlled temperatures.).
Typical experiments can be broadly divided into two categories: i) morphologi- cal studies which require high spatial resolution and are therefore well adapted to 2D or 3D transmission full-field microscopy. ii) studies dealing with co-localization and/or speciation of trace elements in heterogeneous matrices at the sub-micron scale. Scanning X-ray microscopy, in transmission and/or X-ray fluorescence modes, tends to be better suited for the latter cases, which often require both low detec- tion limits and spectroscopic analysis capabilities. Compared to other techniques, synchrotron X-ray fluorescence microprobes display a unique combination of fea- tures. Associated with high detection efficiency, the radiation damage is minimized and accurate quantification is possible [4]. The possibility of in-situ experiments
6 J. Susini
quality and therefore its interpretation. Compared to the standard absorption Xray Computed Tomography, Fluo-tomography is more challenging since it is limited by self-absorption and matrix effect. A multimodal strategy has been developed to overcome these physical limitations and is based on an algorithm solution which relies on the combination of several signals (transmission, fluorescence and scatter- ing) to derive the volumetric distribution of elements [9-10]. Similar approach has been used for X-ray diffraction computed tomography as local structural probe for heterogeneous diluted materials [11]. This lecture aims at giving a short overview of the main development trends of synchrotron based X-ray microscopy and spectro- microscopy. Following a brief description of their characteristics, the strengths and weaknesses of spectro-microscopy techniques will be discussed and illustrated by examples of applications in materials sciences, biology and environmental science.
Acknowledgements: The Author wishes to thank M. Salom´e, R. Tucoulou, G. Criado- Martinez, P. Bleuet, M. Cotte, J. Cauzid, S. Bohic, P. Cleotens and A. Sol´e for their contributions.
Referˆ encias
[1] Adams,Van Vaek, R, Barret, Spectrochim Acta B60 (2005) [2] M. Howells, C. Ja- cobsen and T. Warwick in Science of Microscopy, Vol. II, ed. P.W. Hawkes and J.
C.H. Spence, (Springer) (2007). [3] J. Susini, M. Salom´e,, B. Fayard, R. Ortega and B. Kaulich, Surf. Rev. Lett., 9 (2002). [4] B. Fayard, M. Salom´e, K. Takemoto, H. Ki- hara, J. Susini, Journal of Electron Spectroscopy and Related Phenomena, 170, 19-24 (2009). [5] P. Bleuet, A. Simionivichi, L. Lemelle, T, Ferroir, P. Cloetens, R. Tocoulou and J. Susini, Applied Physic Letters, 92 (2008). [6] E. Lombi and J. Susini, Plant Soil, MARSCHNER REVIEW, 17 January (2009). [7] S. Bohic, K. Murphy, W. Paulus, P.
Cloetens, M, Salom´e, J. Susini and K. Double, Analytica Chemistry, 80 (24) (2008). [8]
M. Cotte, J. Susini, J. Dik, K. Janssens, Accounts of Chemical Research, in press. [9] B.
Golosio, A. Somogyi, A. Simionivici, P. Bleuet, J. Susini, Applied Physics Letters 84(12) (2002). [10] P. Bleuet, P. Cloetens, P. Gergaud, D. Mariolle, N. Chevallier, R, Tucoulou, J. Susini ans A. Chabli, Review of Scientific Instruments, 80 (2009). [11] P. Bleuet, E.
Welcomme, E.Dooryhee, J. Susini, J-L Hodeau and Ph. Walter, Nature Materials 7(6) (2008).
Pretreatment technologies for production of 2G bioethanol from Agricultural waste and crops
Bjerre AB1
Ris National Laboratory
2nd generation (2G) bioethanol is on the verge of industrialisation and compa- nies around the world are starting up demonstration plants. One of the heaviest economical posts of the processes involved in 2G bioethanol production is the pretreatment of biomass, which is needed to open the rigid structure of lignocellu- lose facilitating further enzymatic hydrolysis to fermentable sugars. In Denmark, Ris DTU has studied and developed different pretreatment technologies for more than 20 years with special emphasis on conversion of agriculture waste and crops to ethanol. Among the most significant results from this research is development of two promising pretreatment systems, the wet oxidation process, which is now close to commercialization by the company BioGasol and the IBUS (hydrother- mal) pretreatment, which is now ready for demonstration (4000 kg/hour capacity) in Kalundborg in Denmark. The IBUS facility is a milestone in Danish bio-ethanol research and was presented at the climate conference COP15 as a main event. New pretreatment technologies are still under development. One of the more promising is plasma pretreatment being a pure chemical treatment at ambient temperature and pressure using ozone as reagent for oxidizing lignin and improving the fol- lowing enzymatic hydrolysis and fermentation. Ensiling (or silage treatment) is another promissing pretreatment technology being an anaerobic biological process that conserves biomass and at the same time degrades lignin and opens for en- zymatic hydrolysis of polysaccharides to simple sugars. The advantage in both methods is the high dry matter loading being more than 50
Acknowledgements:
A.B. Thomsen
Riso National Laboratory
The different pretreatment technologies will be presented and discussed for their future utilisation in bioethanol production and biorefinery concepts.
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Parte II
Biologia Estrutural
An´ alises estruturais do estado oligom´ erico do receptor
ativador da prolifera¸c˜ ao de peroxissomo isotipo α atrav´ es de SAXS
Bernardes, A.1, Oliveira Neto M.1, and Polikarpov, I.1 Universidade de S˜ao Paulo - S˜ao Carlos - S˜ao Carlos SP Brazil
Os receptores ativadores da prolifera¸c˜ao de peroxissomos (PPARs) possuem um im- portante papel no controle de diversos processos biol´ogicos relacionados, principal- mente ao metabolismo lip´ıdico e ao processo inflamat´orio, desempenhando pap´eis- chave em v´arias doen¸cas cardiovasculares. Na express˜ao gˆenica, os PPARs se ligam a elementos responsivos espec´ıficos ap´os a heterodimeriza¸c˜ao com receptores X retin´oides e ativam a transcri¸c˜ao em resposta a uma variedade de ligantes end´ogenos e ex´ogenos, incluindo certos ´acidos graxos e fibratos. A caracteriza¸c˜ao desse receptor pode levar ao melhor entendimento de sua fun¸c˜ao e o desenvolvimento de mol´eculas alvos para o tratamento de muitas doen¸cas metab´olicas. Como o modo de dimer- iza¸c˜ao afeta diretamente as interfaces dispon´ıveis para intera¸c˜ao com correguladores e, portanto, diretamente o processo de regula¸c˜ao transcricional realizada pelos re- ceptores nucleares, estudos mais detalhados de oligomeriza¸c˜ao dos receptores nucle- ares est˜ao sendo necess´arios, pois homo- e heterodimeriza¸c˜oes s˜ao alternativas que podem representar um n´ıvel adicional (e pouco estudado at´e agora) de regula¸c˜ao de funcionamento de receptores nucleares. Para melhorar nossa compreens˜ao do funcionamento do PPARα, assim como as intera¸c˜oes entre receptor:ligante e re- ceptor:receptor, estudos oligom´ericos foram realizados com a prote´ına em solu¸c˜ao atrav´es do uso de espalhamento de raios-X a baixo ˆangulo (SAXS). Como resultado, n´os apresentamos an´alises estruturais do estado oligom´erico do PPARαLBD em solu¸c˜ao, para diferentes concentra¸c˜oes de prote´ına e a forma¸c˜ao de heterod´ımeros na presen¸ca de seu parceiro obrigat´orio de heterodimeriza¸c˜ao, RXR. Esses resul- tados mostraram claramente que a prote´ına apresenta-se monom´erica em solu¸c˜ao, diferente dos outros membros desta superfam´ılia de receptores nucleares, podendo ser este um estado inativo da prote´ına no processo de regula¸c˜ao transcricional.
Acknowledgements: Este trabalho foi suportado pela FAPESP
Structural Studies of Selenocysteine Synthase (SELA) from Escherichia coli
Cassago, A.1, Manzine, LR1, Pereira, H.M1, Horjales,E.1, and Thiemann, O. H.1 Universidade de S˜ao Paulo - S˜ao Carlos - S˜ao Carlos SP Brazil
The biosynthesis of the 21thamino acid, selenocysteine (Sec or U) requires a com- plex enzymatic machinery composed of Selenocysteine Synthase (SELA), Seleno- cysteine Elongation Factor (SELB or EFSec), Selenophosphate Synthetase (SELD) and a specific tRNAsec (SELC). The selenocysteine residue is incorporated into a nascent protein at a UGA stop codon that is marked as a Sec incorporation site by the presence of a Selenocysteine Insertion Sequence (SECIS). SELA plays a central role in this pathway by modifying the serine residue in the tRNAsec and converting it into selenocysteine. This enzyme forms a homodecameric com- plex that specifically recognizes and binds to tRNAsec. The specific interaction of SELA and its cognate tRNA remains unclear. Our aim is to elucidate the SELA- tRNAsec molecular recognition mechanism. For this purpose, we have initiated a crystallization screening program to identify the conditions of obtaining SELA and SELA-tRNAseccrystals. As preliminary results we have crystals of SELA protein and SELA-tRNAsec complex diffracting at a resolution ranging from 7 to 20. This data was collected at the Laborat´orio Nacional de Luz S´ıncrotron (LNLS) located in Campinas, SP. Since these results, we are trying new conditions to increase the quality of the crystals to a better resolution. Our first analysis suggest a trigonal or hexagonal symmetry from the data so far collected.
Acknowledgements: This work was supported by IFSC, LNLS and FAPESP.