Three workshops will be held on Saturday, May 24, 2014,
within the Albuquerque Convention Center. Pre-registration is mandatory and
should be indicated on your registration form. The cost for each
workshop is separate from the meeting registration fee.
WK.01 Joint Neutron and X-‐ray Structure Refinement using Joint Refine in PHENIX.
This half-day workshop is intended as a
somewhat informal and hands-‐on tutorial We will have 4
organizers/hosts with extensive knowledge and experience in neutron crystallographic refinement. There has been a
resurgence in macromolecular neutron diffraction over the last decade
in the USA, starting with the construction of the LANL Protein Crystallography Station in ~2001. Since the
early 2000s we now have another diffraction instrument, Imagine at ORNL, with a third, MaNDi at ORNL, being commissioned in 2014. This increase reflects the massive user demand for neutron diffraction instrumentation and while beam time and
data collection is becoming more routine, there has been a lack of
computational programs to handle the non-‐trivial refinement approach to dealing
with explicit H and D atoms. The current incarnation Joint refinement in PHENIX
is expected to be heavily used by a crystallographic community that is rapidly
shifting to PHENIX for most refinements. The introductory lecture will frame the context of the workshop.This will explain the "why" of joint X-‐ray and neutron refinement for neutron studies, as well as some of the technical "how". The bulk of the workshop
will focus on all the steps after
neutron data collection: from preparing an appropriate PDB (is your protein
hydrogenous, H/D exchangedor fully deuterated) to the finer nuances of a proper
neutron/X-‐ray refinement. There will also be a
focus on careful model building in Coot, taking proper hydrogen bonding and
chemistry into account. more
WK.02 Grazing Incidence SAXS Theory and Data Analysis
GISAXS is a unique method for characterizing the nanostructural features of materials, particularly at surfaces and interfaces, which would otherwise be impossible using traditional transmission-based scattering techniques[ i ]. It is a surface-sensitive tool for probing simultaneously the sample morphology both in-plane and out-of-plane, and is being increasingly utilized to measure the size, shape and spatial organization of nanoscale objects located on top of surfaces or embedded in mono- or multi- layered thin-film materials. Individual GISAXS images serve as static snapshots of nanoscale structure,while successive images provide a means to monitor and probe dynamical processes, including self-assembly or other reorganization events, which occur at nanometer length scales.
The success of GISAXS relies on the unique information that can be extracted from the data. Although microscopy techniques provide very valuable local information on the structure, GISAXS is the only technique able to provide statistical information on nanometer features averaged over square centimeters. Consequently, the method is quickly attracting strong interest as the scattering technique of choice for characterizing nanostructures and is complementary to direct imaging methods such as AFM, SEM or TEM. more
WK.03 Reciprocal Space Visualization - MAX3D
When we use an area detector to collect diffraction data for single crystal structure analysis or polycrystalline solid or film texture analysis we rotate the sample around the φ or ω diffractometer axis and store the 3D pattern as distorted slices of reciprocal space. MAX3D is a visualization program which allows us to compile and view the data as a single object - a 3D plot of intensity vs. radial 2θ. Seeing the full diffraction pattern allows us to better determine crystal or film quality, identify weak super-lattice reflections or twinning, observe the details of diffuse or incommensurate scattering, monitor phase changes, enhance student understanding, etc.
The workshop will open with a discussion of reciprocal space and a description of how the all of the information on an area detector frame (not just Bragg spots) maps into RS. We will look at examples of "single crystal" diffraction showing crystal quality, protein diffraction, twinning, incommensurate scattering, diffuse scattering, quasicrystal diffraction. We will briefly discuss the origins of various scattering features and how scanning strategies can be viewed and optimized to observe targeted diffraction features. more
Financial support for WK.02 workshop provided by