Name: ESS Symposium on Crystallography for Soft Matter
Start: 2015-09-07T08:15:00+02:00
End: 2015-09-08T16:25:00+02:00
Location: Institute for Macromolecular Chemistry, Prague

ESS Symposium on Crystallography for Soft Matter

from Monday, 7 September 2015 (08:15) to Tuesday, 8 September 2015 (16:25)

Monday, 7 September 2015

08:55 registration
registration
08:55 - 09:30

09:30 Welcome to the IMC
Welcome to the IMC
09:30 - 09:40
09:40 Hello and Welcome Everybody - Christopher Garvey (ANSTO)
Hello and Welcome Everybody
- Christopher Garvey (ANSTO)
09:40 - 10:00
10:00 Status of ESS and Instrumentation - Markus Strobl (ESS-AB)
Status of ESS and Instrumentation
- Markus Strobl (ESS-AB)
10:00 - 10:40
In fall 2014 construction of the European Spallation Source (ESS) started with breaking ground and laying the foundation stone. The long planned and designed ESS long pulse spallation neutron source and major European neutron science center is since becoming a reality, though the path to first neutrons in instruments in 2019 and producing cutting edge science is still a long one. However, first Neutron scattering instruments have entered their construction phase and many others have been decided upon after a long conceptual design phase involving many partner labs form the 17 European states realising this project together. The status of this process and examples of instruments in different project stages designed for this novel source with it s particular time structure will be introduced together with the current developments concerning final solutions serving the realisation of the complete suite of 22+ instruments.
10:40 Morning Tea
Morning Tea
10:40 - 11:00
11:00 Self-assembly of anisotropic colloids: microradian x-ray diffraction - Andrei Petukhov (Utrecht University, Netherlands)
Self-assembly of anisotropic colloids: microradian x-ray diffraction
- Andrei Petukhov (Utrecht University, Netherlands)
11:00 - 12:00
TBA
12:00 Challenges In Mapping Structural Uniformity And Texture Of The Cubic Phases In Butterfly And Beetle Wing Scales With Synchrotron Pin-Hole Ultra Small Angle X-Ray Scattering - Christopher Garvey (ANSTO)
Challenges In Mapping Structural Uniformity And Texture Of The Cubic Phases In Butterfly And Beetle Wing Scales With Synchrotron Pin-Hole Ultra Small Angle X-Ray Scattering
- Christopher Garvey (ANSTO)
12:00 - 12:30
Wing scales of some butterfly and beetle species contain bicontinuous phases of polymer, largely chitin, and air filled voids. The single network gyroid phase I4132 has been identified as the structure present in butterfly wing scales of several butterfly species with green wing scales [1,2,3]. We have also identified the diamond phase in the wings of in the diamond weevil, Entimus imperialis.. The periodic length scales of these phases is such that it produces optical responses that may relate to insect communication, such as discriminating response to circularly polarized light [4]. In principle diffraction techniques have the possibility of mapping the characteristic length-scales and orientation(s) of the unit cells, but also the nature of defects in crystalline lattice, on the wings of butterflies. This information will provide insight into the mechanism and, potentially, the technological control of such photonic structures. Such information may be characterized by obtaining a sufficient angular range to obtain the position of all diffraction peaks and sufficient angular resolution to characterize their shape. These cubic phases have very large unit cells (> 200 nm) and so measurements push the limits of conventional pin-hole SAXS instrumentation both in terms of the minimum angle but also angular resolution close to the beam stop. [1] Michielsen, K., D.G Stavenga. J. R. Soc. Interface: 5(18) 85-94 (2008) [2] Saranathan, V., C. O. Osuji, S. G. J. Mochrie, H. Noh, S. Narayanan, A. Sandy, E. R. Dufresne, and R. O. Prum. PNAS: 107(26) 11676-11681 (2010) [3] Schröder-Turk GE, Wickham S, Averdunk H, Brink F, Fitz Gerald JD, Poladian L, Large MC, Hyde ST. J Struct Biol: 174(2) 290-5 (2011) [4] Saba, M, M. Thiel, M. D. Turner, S. T. Hyde, M. Gu, K. Grosse-Brauckmann, D. N. Neshev, K. Mecke, and G. E. Schröder-Turk, Phys. Rev. Lett. 106, 103902 (2011)
12:30 Large channels in cationic PEGylated cubosomes - Borislav Angelov (Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, CZ-16206 Prague, Czech Republic)
Large channels in cationic PEGylated cubosomes
- Borislav Angelov (Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, CZ-16206 Prague, Czech Republic)
12:30 - 13:00
The formation of large nanochannels in cationic lipid cubosomes is demonstrated by cryogenic transmission electron microscopy (Cryo-TEM) and small-angle X-ray scattering (SAXS). The swollen cubic structure is stabilized by the polymer polyethylene glycol (PEG) and a cationic amphiphile. These cubosomes are of interest for multi-drug nanoencapsulation, mitochondrial mimetics, or nanocrystallization of membrane proteins. They possess high biocompatibility and biodegradability.
13:00 Lunch
Lunch
13:00 - 14:00
14:00 Probing lipid-disaccharide interaction with neutron membrane diffraction - Ben Kent (Helmholtz-Zentrum Berlin)
Probing lipid-disaccharide interaction with neutron membrane diffraction
- Ben Kent (Helmholtz-Zentrum Berlin)
14:00 - 14:30
Sugars, particularly disaccharides, are widely recognised for their ability to protect cellular membranes in environments with scarce liquid water. Despite widespread acceptance, there remain competing theories over the mechanism responsible for this effect. The water replacement hypothesis[1], based on both (indirect) experimental evidence and molecular dynamics simulations[2], suggests that a specific interaction between sugar molecules and lipid headgroups is the primary mechanism of protection. An alternative mechanism ascribes a key role to non-specific volumetric and osmotic effects of the sugars which mediate the compressive stresses induced in membranes brought into close contact by dehydration[3]. This explanation is supported by (indirect) experimental evidence that sugars tend to be excluded from the regions close to the membranes. Phenomenologically, the sugar membrane protection theories differ in the predicted sugar concentration profile between bilayers: in the case of the water replacement hypothesis the sugar concentration should be enhanced at the interface between the water and lipid bilayer; by contrast in the case of the non-specific volumetric based hypothesis, sugar molecules are likely to be more concentrated in the solvent phase constrained by the barrier of the bilayer. In this work we use neutron membrane diffraction of highly orientated samples, effectively one dimensional crystals, and Fourier methods[4] to reconstruct scattering density profiles of lipid bilayer membranes in the presence of sucrose and trehalose. Deuterated sugars have been used to enhance contrast, and variation of the H2O:D2O ratio has been used to phase the reconstruction of the unit cell. Difference profiles calculated from scattering density profiles with selective deuteration show the average position and distribution of sugars within the bilayer unit cell. Sugar distribution profiles, measured over a range of sugar concentrations and hydrations show that sugars impart a cryoprotective effect on lipid bilayer membranes without specific interaction between the sugars and the lipids. (1) Crowe, J. H.; Crowe, L. M.; Chapman, D. Preservation of Membranes in Anhydrobiotic Organisms: The Role of Trehalose. Science 1984, 223 (4637), 701-703. (2) Sum, A. K.; Faller, R.; Pablo, J. J. d. Molecular Simulation Study of Phospholipid Bilayers and Insights of the Interactions with Disaccharides. Biophys. J. 2003, 85 (5), 2830-2844. (3) Bryant, G.; Koster, K. L.; Wolfe, J. Membrane behaviour in seeds and other systems at low water content: the various effects of solutes. Seed Science Research 2001, 11, 17-25. (4) Kent, B.; Hunt, T.; Darwish, T. A.; Hauß, T.; Garvey, C. J.; Bryant, G. Localization of trehalose in partially hydrated DOPC bilayers: insights into cryoprotective mechanisms. Journal of the Royal Society Interface 2014, 11 (95). [1]: http://D:%5CProfile%5Cjih%5CEigene%20Dateien%5CTalks%20and%20posters%5Cfor_abstract.JPG
14:30 Small-Angle Neutron Diffraction from Biological Membrane Systems - Volker Urban (Oak Ridge National Laboratory)
Small-Angle Neutron Diffraction from Biological Membrane Systems
- Volker Urban (Oak Ridge National Laboratory)
14:30 - 15:10
The biophysics of lipid bilayer membrane systems is one of the essential prerequisites that enable the complex functions of living systems. The roles provided by membranes include compartmentalization and sub-cellular structures, the possibility for maintaining gradients of concentration or chemical potential, and the involvement in signal transduction, to name a few. Lipid bilayer systems build on the self-assembly properties of lipid molecules, but in nature they also exhibit higher forms of organization and quasi-periodic structures such as those that are observable in the light-harvesting apparatus of cyanobacteria. Moreover, quasi-elastic scattering or diffraction techniques allow us to explore the motions and nano-scale mechanical properties of these soft materials and their relation to the response of organisms to changes in environmental parameters. This presentation will give examples of exploring these facets with neutron diffraction or scattering techniques, and it will include a discussion of recent technical developments and ongoing projects in small- and wide-angle scattering and grazing incidence techniques at the Oak Ridge National Laboratory.
15:10 Afternoon Tea
Afternoon Tea
15:10 - 15:30
15:30 SANS/USANS determination of hierarchical structure of self-organized polymer microemulsions - Petr Štěpánek (institute for Macromolecular chemistry)
SANS/USANS determination of hierarchical structure of self-organized polymer microemulsions
- Petr Štěpánek (institute for Macromolecular chemistry)
15:30 - 16:00
TBA
16:00 Application of membrane diffraction and small angle scattering in photosynthesis research - Jörg Pieper (University of Tartu)
Application of membrane diffraction and small angle scattering in photosynthesis research
- Jörg Pieper (University of Tartu)
16:00 - 16:30
The effect of dehydration on the lamellar spacing of photosystem II (PS II) membrane fragments from spinach has been investigated using neutron membrane diffraction at room temperature. The diffraction data reveal a repeat distance D of about 129 Å at 90% r.h. which shifts to about 103.7±2.5 Å at 44% r.h.. Within experimental error, the latter repeat distance remains almost the same at hydration levels below 44% r.h. indicating that most of the hydration water is removed. This result is consistent with the earlier finding that hydration-induced conformational protein motions in PS II membrane fragments are observed above 44% r.h. and correlated with the onset electron transfer in PS II. Furthermore, we have used small-angle neutron scattering (SANS) to study the structure of photosynthetic complexes in buffer solution at room temperature.
16:30 Neutron scattering from photosynthetic membranes in living cyanobacteria - Robert Corkery (KTH Royal Institute of Technology)
Neutron scattering from photosynthetic membranes in living cyanobacteria
- Robert Corkery (KTH Royal Institute of Technology)
16:30 - 17:00
TBA
17:00 Ordered amphiphilic systems at planar interfaces - Henrich Frielinghaus (JCNS, Forschungszentrum Jülich GmbH)
Ordered amphiphilic systems at planar interfaces
- Henrich Frielinghaus (JCNS, Forschungszentrum Jülich GmbH)
17:00 - 17:40
A planar hydrophilic interface induces particular order and orientation in amphiphilic systems that then can be observed using grazing incidence scattering methods. Different systems such as microemulsions and lipid bilayer systems are discussed, where we identified lamellar, hexagonal and other structures. Apart from structure, the dynamics of such systems also display highly interesting insight. For instance the lubrication effect of lamellar microemulsions is connected to faster dynamics, and dynamics of lipid systems can be connected to biological function and mechanisms of medications. The grazing incidence technique at neutron spin echo spectrometers (GINSES) was successfully applied at the SNS spallation source, and a first principle test of a neutron resonator with constructive interference for the evanescent wave for increased intensities has been performed.
18:30 Dinner
Dinner
18:30 - 20:30
Tuesday, 8 September 2015
09:00 The Ordered Structure of Block-Copolymer Systems Studied by Combined Small-Angle Scattering and Rheology. - Kell Mortensen (Niels Bohr Institute, University of Copenhagen)
The Ordered Structure of Block-Copolymer Systems Studied by Combined Small-Angle Scattering and Rheology.
- Kell Mortensen (Niels Bohr Institute, University of Copenhagen)
09:00 - 10:00
Determination of the crystalline structure of many soft-matter materials is often limited by a correlation-length that is relative short compared to the size of the unit cell and a molecular form factor that significantly reduces the scattering intensity at larger scattering angles. The crystallographic studies are therefore often limited to only few orders of relative broad Bragg-reflections. To make such crystallographic study more unique, it is desirable to transform the samples with random orientations of crystal-domains into a mono-domain crystal. In soft matter materials, this can often be done successfully by exposing the system to a high electric, magnetic or shear-field. We have in particular studied the effect of shear to soft matter systems, and will review some of our results. The texture of ordered phases of soft matter melts, gels or emulsions is usually highly sensitive to shear. In the body-centered-cubic phase of a block copolymer system, for example, a given textures can be controlled to very high degree with the application of a specific shear rate and amplitude. The low-amplitude shear texture is dominated by {001} planes perpendicular to the shear gradient and by the [110] axis parallel to the flow direction, that is, the {001}/[110] slip system. Detailed crystallographic studies show that both intermediate-amplitude oscillatory shear and large-amplitude oscillatory shear lead to twin structures with {112} planes sharing neighboring twins and [111] axes parallel to the shear flow. At an intermediate shear amplitude, the ve shear plane, defined by the shear flow direction (v) and shear vorticity direction (e), is parallel to the {112} twin planes. At a high shear amplitude, the orientation is rotated 90°, and this makes the ve shear plane parallel to the {110} crystallographic planes. The crystalline slip system is accordingly ({112}/[111]+{(112}/[111]) under intermediate-amplitude shear and ({110}/[111]+{110}/[111]) under large-amplitude shear. In other systems, like the bi-continuous gyroid phase, similar low degree of texture has not been obtained, however, by shear-aligning the system in the neighboring hexagonal rod-phase, the three-dimensional powder can be reduced to a two-dimensional system with unique characterization.
10:00 Hierarchical Ordering in Star Polyphiles - Liliana De Campo (ANSTO)
Hierarchical Ordering in Star Polyphiles (Self-Assembly)
- Liliana De Campo (ANSTO)
10:00 - 10:30
TBA
10:30 Morning tea
Morning tea
10:30 - 10:50
10:50 Heavy water effect on hydrated lipid systems in bicontinuous cubic phase - Hiroshi TAKAHASHI (Biophysics Laboratory, Gunma University, JAPAN)
Heavy water effect on hydrated lipid systems in bicontinuous cubic phase
- Hiroshi TAKAHASHI (Biophysics Laboratory, Gunma University, JAPAN)
10:50 - 11:25
Various effects of heavy water (D2O) on life processes have been reported since the discovery of D2O. Heavy water decreases the growth rates of some bacteria and retards the circadian rhythm of some animals. High concentrations of D2O are believed to be toxic for most mammals. Detailed molecular mechanisms in these effects, however, have still remained unknown. Several physicochemical properties of D2O slightly differ from those of H2O. In order to understand the heavy water effect on living things at a molecular level, it is indispensable to clarify the molecular interaction between D2O and biological molecules. Experimental studies on the stability of proteins in D2O have suggested that D2O alters hydrophobic interactions in proteins [1]. In addition, D2O-H2O isotope effect has been also observed in lipid bilayer membrane systems. The substitute of H2O by D2O clearly alters the phase transition temperatures of lipid systems. On the other hand, the substitute of H2O by D2O causes a relatively small alternation on the structures of lipid systems. For example, the lamellar repeat distance of dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles in D2O has been reported to be only about 0.1 nm smaller than that in H2O. Recently we have found D2O-induced relatively large changes in the lattice constants of bicontinuous cubic phases of hydrated monoolein (MO) systems [2]. In the present study, by using a simple model proposed by Garstecki and Hołyst [3], we analyzed X-ray diffraction data of Pn3m bicontinuous cubic phase of MO in D2O and H2O in order to estimate the thickness of a MO bilayer in the cubic phase. Our analysis showed that D2O reduces the interfacial area of MO, by assuming that the replacement of H2O with D2O does not change the molecular volume of MO. [1] Y. Cho, L. B. Sagle, S. Iimura, Y. Zhang, J. Kherb, A. Chilkoti, J. M. Scholtz, P. S. Cremer, *J. Am. Chem. Soc.* **2012** , 131,15188 [2] H. Takahashi, K. Jojiki, *Chem. Lett*. **2012**, 41, 1101. [3] P. Garstecki, R. Hołyst, *Langmuir*, **2002**, 18, 2519.
11:25 Structure Factor in Hard Sphere Suspensions - Gary Bryant (RMIT University)
Structure Factor in Hard Sphere Suspensions
- Gary Bryant (RMIT University)
11:25 - 12:25
Hard sphere colloidal suspensions are widely used experimental model systems for studying phase behaviour and dynamics in condensed matter. These colloidal suspensions undergo a crystallization transition at concentrations above the freezing volume fraction of 0.494, allowing the study of the kinetics and dynamics of crystallization. As these colloidal particles are orders of magnitude larger than atoms, processes are correspondingly slower, and metastable states can be studied in real-time using the established techniques, such as dynamic light scattering (DLS) or x-ray photon correlation spectroscopy (XPCS) [eg 1-2]. In this paper we explore the use of modern Synchrotron Small Angle X-ray (SAXS) and Neutron (SANS) scattering for the study of structure in colloidal suspensions near the freezing volume fraction, focusing on the advantages and disadvantages relative to light scattering techniques. For the study of such colloidal suspension, SAXS has a number of advantages: SAXS allows access to a much broader range of scattering vectors than light scattering; the small beam diameter allows the probing of different parts of the sample to explore inhomogeneities; and measurement times are short, allowing the study of fast kinetics. The chief disadvantages are potential beam damage, and the need for very thin samples (and therefore small sample volumes), although the latter can be an advantage in some cases. SANS also has a number of advantages: it allows an expanded beam [3], which can be used to obtain averaging over large volumes, providing excellent statistics, ideal for styding the early stages of crystallization [4]; it provides the ability to contrast match, particularly relevant to the study of binary systems [5] - although contrast matching can be done using light scattering and very specialized particles [6], deuteration offers more flexibility in the types of particles that can be used. In this paper we will present the results of recent experiments at the ESRF and ANSTO designed to explore the possibilities and limitations of these techniques for the study of hard sphere suspensions. References [1] L.B. Lurio, et al., Phys. Rev. Lett. 84, 785 (2000). [2] V.A. Martinez, et al., J. Chem. Phys. 134, 054505 (2011). ESRF Highlights 2011, p56. [3] E.P. Gilbert et al., Physica B: Condensed Matter 2006, 385, 1180 (2006). [4] H.J. Schöpe, et al., Phys. Rev. Lett. 96m 175701 (2006). [5] P. Bartlett and R.H. Ottewill, J. Chem. Phys. 96, 3306 (1992). [6] S.M. Underwood and W. van Megen, Coll. Polym. Sci. 274:1072 (1996).
12:25 Structural and functional characterization of three closely related intrinsically disordered LEA proteins from Arabidopsis thaliana - Anne Bremer (Max Planck Institute for Molecular Plant Physiology)
Structural and functional characterization of three closely related intrinsically disordered LEA proteins from Arabidopsis thaliana
- Anne Bremer (Max Planck Institute for Molecular Plant Physiology)
12:25 - 12:45
The significance of intrinsically disordered proteins (IDPs) has been underestimated for a long time in spite of their high abundance in nature. In fact, it has been predicted that more than 30% of all eukaryotic proteins are IDPs. IDPs have no stable secondary structure in dilute solutions, but instead exist as dynamic ensembles of conformations. We are focusing on the structural and functional characterization of three closely related IDPs from the model plant *Arabidopsis thaliana*. The three IDPs belong to the group of Late Embryogenesis Abundant (LEA) proteins. We expressed the three proteins recombinantly in *E. coli* and found that they are disordered in solution, but mostly α-helical in the dry state, as shown by CD spectroscopy. We showed a linear increase of the α-helical content upon dehydration using a glycerol gradient. Interestingly, the gain of α-helix content was further increased in the presence of artificial membranes. The three LEA proteins protected liposomes from leakage of an encapsulated fluorescent dye during freezing and thawing. Furthermore, X-ray scattering results indicated direct protein-membrane interactions. The interchain distances between the lipids were increased in the presence of the LEA proteins upon dehydration, indicating penetration of the proteins into the membranes. FTIR spectra showed interactions of the proteins with the lipid head groups in the dry state, suggesting a positioning of the proteins in this region parallel to the membrane surface. Recently, we have used neutron membrane diffraction measurements to elucidate the position of the LEA proteins relative to the membranes at different dehydration levels. Detailed data analysis is currently on-going.
12:45 Instrumentation and Analysis for Characterization of New Graphene-Based Soft Materials - Ashley Roberts (Monash University)
Instrumentation and Analysis for Characterization of New Graphene-Based Soft Materials (Colloids & General Soft Condensed Matter)
- Ashley Roberts (Monash University)
12:45 - 13:10
Engineered membranes that are selectively ion-, gas-, or liquid- permeable are key aspects of emerging technology especially in the fields of gas separation (1), water purification (2), and energy storage (3). Recent reports have shown that graphene-based membranes consisting of graphene, chemically converted graphene (CCG), graphene oxide (GO), or partially reduced GO sheets have unique membrane properties and exhibit responsive behavior and tunable structures. Currently, no definitive models exist to describe the structure of these multi-layer graphene-based materials and initial results presented here are discussed in relation to a disordered lamellar system. The two-dimensional sheets are not rigid, and specific material properties of the membrane are determined by the pore size and pore size distribution arising from the disorder induced by corrugation (Figure 1). The graphene-based lamellar systems contain features such as wrinkles, buckles, curves, and corrugation along with defects and/or functional groups – all of which can be more or less controlled during the fabrication process. Accurate characterization of the structure of these materials is of importance and the field could benefit from more widespread information on crystallography methods as applied to more disordered systems seen in soft matter. A typical XRD curve for these graphene-based systems has a broad peak attributed the shift in lamellar spacing from that of pure graphite. This broadening can be attributed to wrinkling and distributed bonding which is strain within the lattice: thus, both strain and crystallite size should be incorporated into the interpretation of peak broadening. Without higher order peaks, the line profile alone is not enough to distinguish between these properties and other methods can be used to extract useful information from the peaks. Further, advances in 2D detectors allow for more detailed analysis of orientation within the material (Figure 2), and *in-situ* studies of hydration have shown interesting information about the dynamic behaviour of these materials, showing a need for soft-matter focused sample environments. ![XRD Line Profiles for GO and CCG Membranes][1] ![Area Detector Image Through the Edge of CCG Membrane][2] 1. Li, H., et al. Science, 2013, 342, 95-98; Kim, H.W., et al. Science, 2013, 342, 91-95. 2. Joshi, RK, et al. Science, 2014, 343, 752-754; Shih, CJ, et al. Nat. Mater. 2013, 12, 866-869. 3. Yang, X.W., Li, D., et al. Adv. Mater. 2011, 23, 2833-2838. [1]: http://Desktop/AbstractFig1.jpg [2]: http://Desktop/AbstractFig2.jpg
13:10 Lunch
Lunch
13:10 - 14:05
14:05 Monolithic mesophase polymer membrane templated from ternary hexagonal lytropic liquid crystal system - Guang WANG (Deakin University)
Monolithic mesophase polymer membrane templated from ternary hexagonal lytropic liquid crystal system
- Guang WANG (Deakin University)
14:05 - 14:25
The hexagonal lyotropic liquid crystal (LLC) mesophase is an ideal template for the fabrication of monolithic mesophase polymer membrane. Desirable characteristics imbued from the template are uniform nano-pore size, large surface area for water purification and reorientation of the mesochannels with long range perpendicular to the surface of membrane. However the binary hexagonal LLC system is too viscous at up to 100 ℃ to realize the reorientation process. In the study we examine a ternary hexagonal system which is vulnerable to the temperature: dodecyltrimethylammonium bromide (DTAB), water and hydrophilic monomers Poly(ethylene glycol) diacrylate (PEGDA) and/or 2-Hydroxyethyl methacrylate (HEMA). When PEGDA was added into system, the transition from hexagonal to isotropic micellar phase was observed at about 60℃. The transition temperature gradually decreases to 42℃ when the PEGDA was replaced with HEMA. More importantly, this transition is reversible. We conclude that the addition of polymerizable monomers into binary hexagonal system of DTAB and water make it easier to align mesochannels under an applied external field. Our current work focuses on the locus of solubilisation of the monomer in the template and the structural changes in the membrane during polymerisation.
14:25 Opportunities for soft matter diffraction experiments on ESS reflectometers and SANS instruments - Hanna Wacklin (European Spallation Source ESS AB)
Opportunities for soft matter diffraction experiments on ESS reflectometers and SANS instruments
- Hanna Wacklin (European Spallation Source ESS AB)
14:25 - 15:05
TBA
15:05 NMX – A Macromolecular Diffractometer at the European Spallation Source - Esko Oksanen (European Spallation Source ESS AB)
NMX – A Macromolecular Diffractometer at the European Spallation Source
- Esko Oksanen (European Spallation Source ESS AB)
15:05 - 15:40
The NMX macromolecular diffractometer planned at the European Spallation Source in Lund is a time-of-flight (TOF) quasi-Laue diffractometer optimised for small samples and large unit cells in order to locate the hydrogen atoms relevant for the function macromolecules. The ESS long pulse source with its highly brilliant neutron moderator is ideally suited for a macromolecular diffractometer. We estimate that a macromolecular diffractometer at the ESS could be used to collect data from crystals of ~200 µm dimension in some days, which represents an order of magnitude improvement over currently available sources. More importantly it broadens the range of systems that can be investigated to many biologically very interesting molecules, including membrane proteins such as proton pumps. One of the limiting factors with current neutron instruments is that the fixed detector geometry only allows a maximal unit cell edge of ~150 Å to be resolved without a compromise in the diffraction resolution (dmin). The NMX detectors will be mounted on robotic arms, allowing larger unit cells to be resolved by increasing the crystal-to-detector distance. This incurs an increase in the data collection time, but reflections to the same dmin can still be observed by moving the detectors. Many of the scientifically most interesting systems, such as proton pumping membrane proteins, crystallise in large unit cells, so being able to resolve a large unit cell edge is a unique advantage. The combination of a neutron flux higher than leading high flux reactor instruments, such as LADI-III, together with the ability to resolve large unit cells and the ability to separate signal from background by time-of-flight leads to world-leading performance particularly with the experimentally most challenging systems. This would transform neutron crystallography into a technique that could answer a significantly larger number of hydrogen related questions in biomolecular science than before.
15:40 Afternnon Tea
Afternnon Tea
15:40 - 16:00