The theme "dynamics" addresses time dependent phenomena, such as biological processes, motion of biomolecules and colloids, or transport processes in hard matter, utilizing the accessible time and length scales with neutrons and X-rays, and the coherent properties of MAX IV. Systems and processes studied include equilibrium as well as non-equilibrium phenomena, reversible and irreversible processes, order-disorder transitions, dynamics on different length and time scales, as well as transient states that could for example be studied with pump-probe experiments. We focus in particular on the application and future development of experimental tools such as quasi-elastic neutron scattering (for example neutron spin echo or backscattering experiments), x-ray photon correlation spectroscopy or fast pump probe experiments, and computer simulations performed in order to help und understand experimental data.
HAPPENING IN DYNAMICS
DYNAMICS WG 1
Dynamics and structure of biological macromolecules
The working group will address the need to educate future users of ESS, MAX IV and other major research infrastructures in topics related to dynamics of biological macromolecules. We bring together leading scientists from soft matter physics, biology and pharmaceutical sciences, with expertise in experiments, theory and computer simulations and showcase what can be achieved at MAX IV and synchrotrons worldwide.
Research Programme 1: Simulation, theory, and software development for anisotropic systems
Research programme 2: Antibodies in Solution
DYNAMICS WG 2
Characterizing soft matter with X-ray Photon Correlation Spectroscopy
X-ray Photon Correlation Spectroscopy (XPCS) is a technique which allows access to the dynamics of molecules and particles in a sample. It has been applied in condensed matter systems, for example in glasses, but is under-exploited in biological and soft matter samples where it could bridge the gap between the timescales accessible by neutron spectroscopy and light scattering. The technique examines the temporal variation in the coherent speckle patterns and thus is of relevance for following collective processes such as diffusion, relaxation, reorganization. As such, it will benefit greatly from the new synchrotron X-ray sources that will provide high coherent flux. These facilities are either nearing operation (CoSAXS at MAX IV) or about to be upgraded to deliver higher coherent flux (ESRF and APS), thus there is a timeliness to exploring what needs to be done to develop the potential of XPCS to move from idealized samples to biological and soft matter systems and address relevant scientific questions. It is apparent that difficulties to be addressed include: detector speed, signal to noise and beam damage. For this reason, XPCS will benefit from a concerted effort by key groups within Europe and world-wide, organized and hosted by LINXS.
DYNAMICS WG 3
Dynamics and structure of Membranes and their Constituents
Recent years have seen strong research efforts on the lipid component of biological membranes. While many studies have been focused on the membrane structure, the dynamics of such systems are crucial for the function of the membrane including membrane bound proteins.
The relevant time scales are wide, from seconds to nanoseconds, and therefore a combination of techniques and modeling tools are requires. To some extent and for longer timescales ”traditional” neutron and x-ray scattering techniques can be used. However this often requires a particular sample environment like stopped-flow set-up or temperature and pressure jumps.
Inelastic neutron scattering techniques and X-ray Photon Correlation Spectroscopy (XPCS) has emerged as promising techniques, which will particularly benefit from the new powerful neutron and synchrotron facilities, ESS and Max IV, built up in Lund.
This will be particularly useful for membrane dynamics studies. Increasingly, synchrotron and neutron users as well as large scale facilities have realised the strength of combining large-scale facilities techniques with lab instruments. This includes fluorescence, NMR, surface chemistry techniques and light scattering. They do not only allow better planning of experiments at the large scale facilities, but also provide complementary information that sometimes are essential for the evaluation of neutron and synchrotron x-ray and neutron data.
The development of coarse graining strategies and other modeling tools has allowed us to develop relevant in silico models of the dynamics of rather complex membranes. Although these simulation have given us insight on the dynamics, the combination with in particular Quasielastic neutron scattering (QENS) and other inelastic neutron scattering techniques such as neutron spin-echo with modeling have emerged as powerful tool box do study dynamics in life science systems. The experimental studies will give the needed relevant parameters for the simulations and inversely the simulations will help interpret the experimental data. It is clear that neutron and synchrotron x-ray techniques are powerful techniques to study dynamics in biomembrane systems.
Research programme 1: Structure and dynamics utilizing the GISANS technique
Research programme 2: Sample environment and data evaluation of biological membranes