Dilworth Y. Parkinson

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We used soft X-ray tomography (SXT)--a high-resolution, quantitative imaging technique--to measure cell size and organelle volumes in yeasts. Cell size is a key factor in initiating cell division in yeasts, whereas the number and volume of the organelles have a profound impact on the function and viability of a cell. Consequently, determining these cell(More)
Imaging has long been one of the principal techniques used in biological and biomedical research. Indeed, the field of cell biology grew out of the first electron microscopy images of organelles in a cell. Since this landmark event, much work has been carried out to image and classify the organelles in eukaryotic cells using electron microscopy.(More)
We report Fourier transform infrared spectro-microtomography, a nondestructive three-dimensional imaging approach that reveals the distribution of distinctive chemical compositions throughout an intact biological or materials sample. The method combines mid-infrared absorption contrast with computed tomographic data acquisition and reconstruction to enhance(More)
One- and two-color, three-pulse photon echo peak shift spectroscopy (1C and 2C3PEPS) was used to estimate the electronic coupling between the accessory bacteriochlorophyll (B) and the bacteriopheophytin (H) in the reaction center of the purple photosynthetic bacterium Rhodobacter sphaeroides as approximately 170 +/- 30 cm-1. This is the first direct(More)
Soft X-ray microscopy is ideally suited to visualizing and quantifying biological cells. Specimens, including eukaryotic cells, are imaged intact, unstained and fully hydrated, and therefore visualized in a near-native state. The contrast in soft X-ray microscopy is generated by the differential attenuation of X-rays by the molecules in the specimen-water(More)
Failure caused by dendrite growth in high-energy-density, rechargeable batteries with lithium metal anodes has prevented their widespread use in applications ranging from consumer electronics to electric vehicles. Efforts to solve the lithium dendrite problem have focused on preventing the growth of protrusions from the anode surface. Synchrotron hard X-ray(More)
Soft X-ray tomography (SXT) is a powerful imaging technique that generates quantitative, 3D images of the structural organization of whole cells in a near-native state. SXT is also a high-throughput imaging technique. At the National Center for X-ray Tomography (NCXT), specimen preparation and image collection for tomographic reconstruction of a whole cell(More)
High resolution x-ray computed tomography (HRCT) is a non-destructive diagnostic imaging technique with sub-micron resolution capability that is now being used to evaluate the structure and function of plant xylem network in three dimensions (3D) (e.g. Brodersen et al. 2010; 2011; 2012a,b). HRCT imaging is based on the same principles as medical CT systems,(More)
Ceramic matrix composites are the emerging material of choice for structures that will see temperatures above ~1,500 °C in hostile environments, as for example in next-generation gas turbines and hypersonic-flight applications. The safe operation of applications depends on how small cracks forming inside the material are restrained by its microstructure. As(More)
Two-color photon echo peak shift spectroscopy was used to study electronic coupling in a phthalocyanine homodimer. Two optical parametric amplifiers were used to produce pulses to excite the split lower states of LuPc2-. The existence of a two-color peak shift indicates the existence of correlation between these two dipole-allowed states. The nature of this(More)