Influence of Polymer Concentration and Nozzle Material on Centrifugal Fiber Spinning

Centrifugal fiber spinning has recently emerged as a highly promising alternative technique for the production of nonwoven, ultrafine fiber mats. Due to its high production rate, it could provide a more technologically relevant fiber spinning technique than electrospinning. In this contribution, we examine the influence of polymer concentration and nozzle material on the centrifugal spinning process and the fiber morphology. We find that increasing the polymer concentration transforms the process from a beaded-fiber regime to a continuous-fiber regime. Furthermore, we find that not only fiber diameter is strongly concentration-dependent, but also the nozzle material plays a significant role, especially in the continuous-fiber regime. This was evaluated by the use of a polytetrafluoroethylene (PTFE) and an aluminum nozzle. We discuss the influence of polymer concentration on fiber morphology and show that the choice of nozzle material has a significant influence on the fiber diameter.

Electrophysiological study of the posterior accessory optic tract

Electrophysiological methods were used to detect the presence of the posterior accessory optic tract—transpeduncular tract in the rabbit. Photic stimulation gave rise to mainly an ‘on’ response from the contralateral nucleus of the transpeduncular tract. Electrical stimulation of the optic nerve fibers evoked a response from this nucleus with a latency of 1–3 msec. A response could not be elicited from the nucleus of the transpeduncular tract, the lateral geniculate nucleus, or the superior colliculus by ipsilateral stimulation. Encéphale isolé preparations showed that the responses recorded under urethane anesthesia were not altered by the drug. The nucleus of the posterior accessory optic tract is situated between the optic nerve and the nucleus of the transpeduncular tract, and lies on the dorsolateral aspect of the midbrain between the superior colliculus and the medial geniculate nucleus. No centrifugal fiber responses have been found which originate from the nucleus of the transpeduncular tract and pass to the retina via the optic nerve.