Code: ThOB	Time Slot/Poster Number: 10:45-11:10	Session: Diffusion & Flow
Compressed Sensing and Bayesian Magnetic Resonance Techniques for Studying Single- and Two-Phase Flows
Lynn Gladden1; Andrew Sederman1; Daniel Holland1; Andrew Blake2
1University of Cambridge, Cambridge, United Kingdom; 2Microsoft Research, Cambridge, UK
Abstract
Magnetic Resonance (MR) imaging is used increasingly to study multi-phase flows in the field of chemical engineering. Understanding single-phase gas and liquid flows in porous media such as rock cores or chemical reactors, and two-phase gas-liquid flows are topics of substantial interest, since these systems are difficult to study using conventional optical or tomographic techniques. This presentation shows how different approaches based around sparse-sampling strategies can be used to extend the application of MR techniques in imaging flowing systems, thereby opening up new opportunities in chemical engineering research. In particular we are exploiting recent developments in Compressed Sensing and Bayesian design of experiments. Through collaboration with those working in medical MRI, we are also exploring opportunities in medical applications.

Code: ThOB	Time Slot/Poster Number: 11:10-11:25	Session: Diffusion & Flow
Diffusion and Alignment of Domain Repeats in Modular Proteins
Joseph D. Walsch; Katlyn Meier; Rieko Ishima; Angela Gronenborn
University of Pittsburgh, Pittsburgh, PA
Abstract
Translational and rotational diffusion influences protein behavior in signaling cascades and other activities that involve protein-protein interactions. Often, the positioning of binding sites or motional properties are intimately linked to function and the relative orientation of and flexibility between domains are pivotal properties in that respect. We therefore evaluated how individual domains in single-chain modular proteins orient relative to each, focusing on repeating domains that are almost identical in sequence. This allowed us to ask basic questions about the dependence of rotational diffusion and magnetic alignment with respect to linker lengths, linker composition etc. Our results using residual dipolar couplings and relaxation parameters as well as hydrodynamics will be presented and discussed in the context of multi-domain protein dynamics.

Code: ThOB	Time Slot/Poster Number: 11:25-11:40	Session: Diffusion & Flow
Development of NMR Methods for Heparin Purity Analysis
John Limtiaco; Cynthia Larive
University of California, Riverside, Riverside, CA
Abstract
Heparin is a negatively charged micro-heterogeneous linear polysaccharide most widely recognized as an anticoagulant in the treatment of venous thrombosis as well as for dialysis and surgery. We are developing analytical methods to evaluate heparin purity using NMR spectroscopy. WAX-HPLC is used to separate the intact GAGs based on their charges. Eluting GAGs are identified by on-flow and stop-flow LC-NMR. In addition to WAX-NMR, we are also investigating the use of diffusion NMR in the analysis of intact heparin samples. Diffusion NMR allows us to separate the resonances of heparin from those of dermatan sulfate. Additionally, with samples subjected to enzymatic digestion we can obtain a diffusion-edited 1H NMR spectrum showing only the resonances of the dermatan sulfate impurity.

Code: ThOB	Time Slot/Poster Number: 11:40-11:55	Session: Diffusion & Flow
Pure Shift DOSY Techniques
Robert Evans1; Juan Aguilar1; Stephan Haiber2; Gareth Morris1; Mattias Nilsson1
1School of Chemistry, University of Manchester, Manchester, United Kingdom; 2Givaudan, Dept. for Analytical Research, Naarden, Netherlands
Abstract
Diffusion-ordered NMR spectroscopy (DOSY) allows the spectrum of a mixture to be resolved into individual components according to their diffusion coefficients but good results require well-resolved spectra. Peak overlap, almost unavoidable in proton NMR, leads to artefacts in the DOSY spectrum such as peaks that appear at compromise positions in the diffusion dimension. Pure shift techniques reduce complicated multiplets into single lines, improving proton resolution by an order of magnitude and greatly improving the range and scope of DOSY. The introduction of the Zangger-Sterk pulse sequence element has allowed significant improvements in pure shift techniques. A range of 2D and 3D pure shift DOSY experiments have been developed and are presented here.

Code: ThOB	Time Slot/Poster Number: 11:55-12:10	Session: Diffusion & Flow
Applying a two-compartment exchange model to diffusion in tissues: When is it justified and what does it mean?
Dmitry S. Novikov; Els Fieremans; Jens H. Jensen; Joseph A. Helpern
CBI, NYU Langone Medical Center, New York, NY
Abstract
Chemical exchange models have been frequently applied to quantify measurements of transverse relaxation and diffusion in living tissues. While the simplicity of such models is attractive, the precise relationship of the model parameters to tissue properties may be difficult to ascertain. Here we discuss the justification of the two-compartment exchange (Karger) model (KM) for tissues. We develop the coarse-grained description that connects the original complicated Bloch-Torrey equation for the proton magnetization with the simple evolution of the two-component KM magnetization. Our results are supported by Monte-Carlo simulations of diffusion in a system of randomly-packed identical parallel cylinders with permeable walls.

Code: ThOB	Time Slot/Poster Number: 12:10-12:25	Session: Diffusion & Flow
Accelerated Ion Diffusion measured by PFG NMR under Electric Field referring to Electrochemical Chronoamperometry. Modified Electrophoretic NMR (ENMR)
Kikuko Hayamizu
National Institute of Advanced Industrial Science, Tsukuba, JAPAN
Abstract
Accelerated ion diffusion of ionic liquids (IL) under electric field was observed by PFG-NMR, by using a modified electrophoretic NMR (ENMR) method. The strength of the electric field was kept under 3V/cm to prevent the decomposition of the chemicals. By introducing the time interval between the application of electric field and PFG-NMR measurements, we observed the accelerated ion diffusion. The current density JNMR was calculated from the ion motilities, and compared with the current density JCA given by the chronoamperometry (CA). We point out the importance to insert proper time interval in ENMR measurement, because ions cannot drift with enough speed just after the application of electric field.