No abstract

No abstract

We have designed, fabricated, and characterized a self-closed parylene cuff electrode for peripheral nerve recording, whose curliness and closeness is realized by the difference in self-stress of different parylene layers due to the heat treatments. Compared with the conventional cuff electrodes, the self-closed structure without any additional mechanical locking structure minimizes the mechanical structure of the cuff electrode. Moreover, the self-closed structure made of thin and flexible parylene film minimizes mechanical damage to the nerve and the surrounding tissues. The zero insertion force interface facilitates the connection of 16 channels with external circuits through the integrated parylene bonding pads. To reduce the impedance and increase the charge storage capacity of the electrode, the electrodeposited iridium oxide film is electrodeposited on the electrode sites. Using the fabricated self-closed parylene cuff electrode, acute neural recoding of 16 channels was performed on the rat sciatic nerve to verify the capability of recording the neural activities. The present self-closed parylene cuff electrode is promising to be used as an neural interface for peripheral nerve recording.[ 2014-0100]Index Terms-Cuff electrode, self-closed, MEMS, self-stress, electrodeposited iridium oxide film (EIROF), neural interface.

No abstract

Sarpagine-Ajmaline-Koumine type monoterpenoid indole alkaloids represent a fascinating class of natural products with polycyclic and cage-like structures, interesting biological activities, and related biosynthetic origins. Herein we report a unified approach towards the asymmetric synthesis of these three types of alkaloids, leading to a collective synthesis of 14 natural alkaloids. Among them, akuammidine, 19-Z-akuammidine, vincamedine, vincarine, quebrachidine, vincamajine, alstiphylianine J, and dihydrokoumine are accomplished for the first time. Features of our synthesis are a new Mannich-type cyclization to construct the key indole-fused azabicyclo[3.3.1]nonane common intermediate, a SmI2 mediated coupling to fuse the aza-bridged E-ring, stereoselective olefinations to install either the 19-E or 19-Z terminal alkenes presented in the natural alkaloids, and an efficient iodo-induced cyclization to establish the two vicinal all-carbon quaternary centers in the Koumine-type alkaloids.