X-ray scattering and optical microscopy studies have revealed a dramatic increase in the cholesteric helical pitch of liquid crystalline DNA in the transition region to a higher density mesophase. The image above illustrates the formation of batonnets within the confines of an unwinding cholesteric phase that has been aligned with a 7 tesla magnetic field. The DNA concentration in this experiment is approximately 300 milligrams per milliliter, and the photomicrograph magnification is approximately 600x. Originally recorded on Fujichrome 64T transparency film using a Nikon Optiphot-Pol microscope with crossed polarized illumination, the image above was digitized using a Nikon CoolScan transparency film scanner. Exposures were recorded about 2 f-steps under the recommended value given by an in-camera photomultiplier and were push-processed approximately 1.3 f-steps in the first E-6 developer. |
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