In-situ x-ray diffraction was used to study the response of single crystal iron under shock conditions. Measurements of the response of [001] iron showed a uniaxial compression of the initially bcc lattice along the shock direction by up to 6% at 13 GPa. Above this pressure, the lattice responded with a further collapse of the lattice by 15-18% and a transformation to a hcp structure. The in-situ measurements are discussed and results summarized.

In situ X-ray diffraction allows the determination of the structure of transient states of matter. We have used laser-plasma generated X-rays to study how single crystals of metals (copper and iron) react to uniaxial shock compression. We find that copper, as a face-centered-cubic material, allows rapid generation and motion of dislocations, allowing close to hydrostatic conditions to be achieved on sub-nanosecond timescales. Detailed molecular dynamics calculations provide novel information about the process, and point towards methods whereby the dislocation density might be measured during the passage of the shock wave itself. We also report on recent experiments where we have obtained diffraction images from shock-compressed single-crystal iron. The single crystal sample transforms to the hcp phase above a critical pressure, below which it appears to be uniaxially compressed bcc, with no evidence of plasticity. Above the transition threshold, clear evidence for the hcp phase can be seen in the diffraction images, and via a mechanism that is also consistent with recent multi-million atom molecular dynamics simulations that use the Voter-Chen potential. We believe these data to be of import, in that they constitute the first conclusive in situ evidence of the transformed structure of iron during the passage of a …

For many rocks of high economic interest such as chalk,diatomite, tight gas sands or coal, nanometer scale resolution is neededto resolve the 3D-pore structure, which controls the flow and trapping offluids in the rocks. Such resolutions cannot be achieved with existingtomographic technologies. A new 3D imaging method, based on serialsectioning and using the Focused Ion Beam (FIB) technology has beendeveloped. FIB allows for the milling of layers as thin as 10 nanometersby using accelerated Ga+ ions to sputter atoms from the sample surface.After each milling step, as a new surface is exposed, a 2D image of thissurface is generated. Next, the 2D images are stacked to reconstruct the3D pore or grain structure. Resolutions as high as 10 nm are achievableusing this technique. A new image processing method uses directmorphological analysis of the pore space to characterize thepetrophysical properties of diverse formations. In addition to estimationof the petrophysical properties (porosity, permeability, relativepermeability and capillary pressures), the method is used for simulationof fluid displacement processes, such as those encountered in variousimproved oil recovery (IOR) approaches. Computed with the new methodcapillary pressure curves are in good agreement with laboratory data. Themethod has also been applied for visualization of the fluid distributionat various saturations …

Email from Betty Jane Williams to WASP members discussing the Women Military Aviators (WMA) conference. She mentions the connection between the WMA and the WASP and encourages the recipients to show their support of the WMA by attending the event in San Diego.

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A document advertising the events hosted by the UNT Multicultural Center during Hispanic Heritage Month. There is a description of the month at the top and it lists each event by the date and time, followed by location, name, and a quick description. At the end is an informational section about the center and its work.

A document announcing the events happening at UNT to celebrate Hispanic Heritage Month in 2005. There is a flag collage background and country names in the middle. The events are all hosted by the UNT Multicultural Center.

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