Experimental tomography studies include preparation of systems away from equilibrium followed by repeated imaging as a function of time and temperature as a flame retardant dissolved into polystyrene.  The challenge here was domain tracking and computation of local concentration gradients.  A preliminary account of the diffusion measurements has been published [Barnett, 2006; Barnett, 2007] and a larger work combining the simulations is in preparation.

More complicated polymer samples include materials such as fiberglass reinforcement.  We spent considerable time developing procedures and code to study the local flame retardant concentration about a fiberglass reinforcement; a priori, one could expect either no affect on the flame retardant concentration, or a increase or decrease in the local concentration as flame retardant or polymer is preferentially absorbed onto the fiberglass surface.  Here, we found flame retardant concentration rises about two-fold over the bulk concentration, indicating flame retardant precipitation onto the fiberglass.   This is an observation from tomography over many voxels containing both fiberglass and flame retardant, and shows that tomography can yield chemical information that is nominally at a smaller distance scale than the imaging resolution. [Ham, 2008; Barnett, 2009]

NMR studies of Methylaluminoxanes: Two publications were completed based on work supported during a prior NSF supported project.[Negureanu, 2006; Wu, 2007]

Dynamic tomography (mathematics):  A new 'Greek golden ratio' based data acquisition procedure (math workshop) has been  very useful for our synchrotron.  We fell in love with this procedure as soon as we heard it (June 05) and got it running at out beamline in 2 months, even though it was a complete  re- write of the acquisition and processing code.  Basically, the Greek golden ratio angle order allows the  experimentalist more flexibility in selecting time windows for slowly change 3D processes. An intellectual disclosure application has been submitted to the LSU Office of Intellectual  Property in Sept, 2008.  Their tracking number is 0907.

Dynamic tomography (experimental):  We collected tomography data of a flame retardant sample as a  function of periodic heating while on the tomography stage.  Images were collected with  both fixed angle increments and the new Greek golden ratio increments.  The former show  motion artifacts while the latter are much less susceptible to motion, though at the cost of reduced S/N, but a gain in time resolution.   A temporary downside to dynamic  tomography are the huge sample sizes, about 1.2 TB for just two samples!!  It's pushing  the code pretty hard to wade through this much raw data.  We are developing procedures  based on (a) manual tracking and (b) automatic connected component analysis.

Mathematics Workshop:  We co-hosted a mathematics workshop at the 'Institute for Mathematics and Its  Applications' with the goal (partly achieved) of acquiring new tomography tools, such as the Greek golden ratio projection acquisition.  We were amazed that 120 people showed up for a math conference in January in Minnesota.

Industrial Chemical Tomography:  A local chemical company, Albemarle Corp. is starting to get interested in tomography for analysis of  their polymer blends and catalyst structures.  We guided them to a lab tomography  company and helped with two one-day demo runs.  We converted the raw images into  movies for presentation at the internal company technology meetings.  We think the  company is getting quite eager to invest in tomography, pending economic recovery.[Ham, 2008]

Error Analysis in Chemical Tomography: The process of getting 3D chemical information from X-ray tomography data has a lot  of issues.  We wrote a 'how to' paper, including a lot of error analysis.[Ham, 2007]

Neutron Tomography:  Not all samples work well with synchrotron X-ray tomography,  and neutrons are an option.  Over the past few years, Butler has given several talks at SNS asking for a  neutron tomography beamline.  In October 23-25, 2006, SNS hosted an 'Imaging and  Neutrons -2006' workshop with 200 participants discussing the potential for neutron  tomography at SNS and HFIR.  Butler was a member of the international advisory committee for  this workshop.   To get ready, he did a week's work at FRM-II (Munich, Germany) in June,  2006, imaging a variety of samples, including a machined phantom with stainless steel,  various polymers, and the two crystallographic forms of titanium(IV) oxide.  The FRM-II  reactor source yields 'white beam' neutrons, thus we could not tell the difference between  rutile and anatase, hence the need for energy-selective imaging at a source like SNS.  The  SNS formed an Instrument Development Team for which Butler is a co-champion.

We explored neutron tomography at the FRM-II/Antares beamline at the Technical  University of Munich, Germany.  These results will feed into a neutron tomography  workshop scheduled at SNS in October (http://www.sns.gov/IAN2006/ )  We have submitted a manuscript comparing X-ray and neutron tomography on a geological sample, with and emphasis on the design parameters for a possible time-of-flight neutron tomography beamline.[Ham, 2009]

Honors Course on Tomography:  We organized a new course for tomography for the undergraduate students through the LSU  Honors College.  This course was team-taught by a chemist (Butler), a biologist, a  mathematician, a medical physicist, and a chemical engineer.  We also had great support  from the newly formed LSU visualization center.  Eleven undergraduates from biology,  physics, and mathematics took the course, offered as HNRS 3035 “3D Image Acquisition and  Analysis” in spring, 2008.

Scientific Visualization:  We have co-hosted a ``Visualization Colloquium'' in collaboration with the LSU CCT (a  supercomputing center).   This has brought about 20-30 faculty, graduate students, staff,  and undergraduates together for spring 2006 meetings, and we expect similar in the fall

In 2008, LSU supercomputing center agreed to trial fund for 3 years a multi-tiered  visualization center at LSU.  This has evolved into a Tier 1 help desk with about $200k of  equipment/software in an attractive room in the main library.  Then, there is a Tier 2  advanced visualization center at the main computer building.  Tier 3 refers to collaborations  between LSU faculty and LSU CCT staff/faculty on new visualization methods.   All in all, it is  a novel and well-formed new initiative for visualization in a university environment.

Cat Claw Shedding Mechanism:  Tomography of polymer blends day after day is tough work for the students.  As a break (and  fun), we've brought in some other imaging projects.  One that really took off was the 'cat  claw' project.  An LSU biologists is researching cornified tissues like parrot beaks, cat claws,  and horse hooves (did you know that 40% of horse deaths are related to hoof disease?).  We  imaged over 40 cat claws, and learned how to work on this interdisciplinary project.   For  example, we first tended to randomly orient the claw images.  This led to a scolding by the  biologist; she mentally connected random claw image orientations to cats on their feet, cats  upside, etc., and it was disturbing to her.  Collectively, we developed a consistent claw orientation.   The work led to new insight into the cat claw shedding mechanism. [Ham, 2006; Homberger, 2009]

References

[Barnett, 2006]  Barnett HA, Ham K, Butler LG. The 3D Chemical Distribution of a Flame Retardant in a Fiberglass-Reinforced Polymer Blend as Measured with Synchrotron X-ray Tomography. Proceedings of the SPIE. 2006;6318:Art. No. 631821.

[Barnett, 2007]  Barnett HA, Ham K, Butler LG. Synchrotron X-ray tomography for 3D chemical diffusion measurement of a flame retardant in polystyrene. Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment. 2007;582(1):202-4.

[Barnett, 2009]  Barnett HA, Ham K, Scorsone JT, Butler LG. Synchrotron X-ray Tomography for 3D Chemical Distribution Measurement of a Flame Retardant and Synergist in a Fiberglass-Reinforced Polymer Blend. Journal of Physical Chemistry. 2009(submitted).

[Hall, 2008]  Hall RW, Wolynes PG. Intermolecular forces and the glass transition. Journal of Physical Chemistry B. 2008;112(2):301-12.

[Ham, 2006]  Ham K, Barnett HA, Ogunbakin T, Homberger DG, Bragulla HH, Matthews II KL, et al. Imaging Tissue Structures:  Assessment of Absorption and Phase-Contrast X-ray Tomography Imaging at 2-nd and 3-rd Generation Synchrotrons. Proceedings of the SPIE. 2006;6318:Art. No. 631822.

[Ham, 2007]  Ham K, Butler LG. Algorithms for three-dimensional chemical analysis via multi-energy synchrotron X-ray tomography. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms. 2007;262(1):117-27.

[Ham, 2008]  Ham K, Barnett HA, Butler LG. Burning issues in tomography analysis. Computing in Science & Engineering. 2008;10(2):78-81.

[Ham, 2009]  Ham K, Barnett H, Ogunbakin T, Weber R, Scorsone JT, Henry DJ, et al. Comparison of X-ray and Neutron Tomography for Imaging Granitic Veins in Migmatite: Comments on Neutron Tomography Design Specifications. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms. 2009:submitted.

[Homberger, 2009]  Homberger D, Ham K, Ogunbakin T, Bonin J, Hopkins B, Osborn M, et al. The Structure of the Cornified Claw Sheath in the Domestic Cat(Felis catus): Implications for the Claw Shedding Mechanism. Journal of Anatomy. 2009:( In Press).

[Negureanu, 2006]  Negureanu L, Hall RW, Butler LG, Simeral LA. Methyaluminoxane (MAO) polymerization mechanism and kinetic model from ab initio molecular dynamics and electronic structure calculations. Journal of the American Chemical Society. 2006;128(51):16816-26.

[Stevenson , 2008]  Stevenson JD, Walczak AM, Hall RW, Wolynes PG. Constructing explicit magnetic analogies for the dynamics of glass forming liquids. Journal of Chemical Physics. 2008;129(19).

[Wu, 2007]  Wu FJ, Simeral LS, Mrse AA, Eilertsen JL, Negureanu L, Gan ZH, et al. Structural characterization of (Al10O6Bu16)-Bu-i(mu-H)(2), a high aluminum content cluster: Further studies of methylaluminoxane (MAO) and related aluminum complexes. Inorganic Chemistry. 2007;46(1):44-7.