Publications by authors named "Alexander C Johnson"

Micro free-flow electrophoresis (μFFE) is a continuous separation technique in which analytes are streamed through a perpendicularly applied electric field in a planar separation channel. Analyte streams are deflected laterally based on their electrophoretic mobilities as they flow through the separation channel. A number of μFFE separation modes have been demonstrated, including free zone (FZ), micellar electrokinetic chromatography (MEKC), isoelectric focusing (IEF) and isotachophoresis (ITP).

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Two-dimensional (2D) separations are able to generate significantly higher peak capacities than their one-dimensional counterparts. Unfortunately, current hyphenated 2D separations are limited by the speed of the second dimension separation and the consequent loss of peak capacity due to under sampling of peaks as they elute from the first dimension separation. Continuous micro free flow electrophoresis (μFFE) separations eliminate under sampling as a limitation when incorporated as the second dimension of a 2D separation.

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Guest induced shape change of the cucurbit[8]uril cavity is likely rate limiting in the supramolecular photocatalytic cycle for CB8 mediated photodimerization of 6-methylcoumarin.

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Magnetic resonance imaging of hyperpolarized nuclei provides high image contrast with little or no background signal. To date, in vivo applications of prehyperpolarized materials have been limited by relatively short nuclear spin relaxation times. Here, we investigate silicon nanoparticles as a new type of hyperpolarized magnetic resonance imaging agent.

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Coumarin derivatives with non-polar substituents at the 6 or 7 position undergoes photodimerization in the presence of CB[8] in water to give the syn dimer as the major product. It is postulated that these neutral coumarins form dynamic complexes in the presence of CB[8] and the product selectivity is reflective of the type of complex, available volume in the CB[8] cavity and relative rate of photodimerization inside and outside the CB[8] cavity.

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