Ion gates

The Mechanism of Long-Distance Radical Cation Transport in Duplex DNA Ion-Gated Hopping of Polaron-Like Distortions... 

Keywords Long-distance charge transport DNA damage Polaron hopping Ion gated base sequence effects... 

Schuster GB, Landman U (2004) The Mechanism of Long-Distance Radical Cation Transport in Duplex DNA Ion-Gated Hopping of Polaron-Like Distortions. 236-. 139-161 Schwarz H, see Schroder D (2003) 225 129-148... 

Burgmayer and Murray [40] reported electrically controlled resistance to the transport of ions across polypyrrole membrane. The membrane was formed around a folded minigrid sheet by the anodic polymerization of pyrrole. The ionic resistance, measured by impedance, in 1.0 M aqueous KC1 solution was much higher under the neutral (reduced) state of the polymers than under the positively charged (oxidized) state. The redox state of polypyrrole was electrochemically controlled this phenomenon was termed an ion gate, since the resistance was varied from low to high and vice versa by stepwise voltage application. 

P Burgmayer, RW Murray. An ion gate membrane Electrochemical control of ion permeability through a membrane with an embedded electrode. J Am Chem Soc 104 6139-6140, 1982. 

Because long acquisition times are required for maximum resolution, it is essential that the ions can survive in the trap for extended periods of time. A main reason for ion loss is collisions with residual gas in the cell. Therefore, it is essential to keep the pressure as low as possible, preferably in the region of 10-9 torr or below. It is also important not to allow too many ions to enter the cell. When more than 106 to 107 ions are present in the cell, the coulomb repulsion can shift or broaden peaks in the mass spectra. By using an ion gate, the number of ions entering the cell can be limited in a controlled way. 

Acetylcholine released by an excited neuron diffuses a few micrometers across the synaptic cleft or neuromuscular junction to the postsynaptic neuron or myocyte, where it interacts with the acetylcholine receptor and triggers electrical excitation (depolarization) of the receiving cell. The acetylcholine receptor is an allosteric protein with two high-affinity binding sites for acetylcholine, about 3.0 nm from the ion gate, on the two a... 

Ion gating, 234 Immunofluorescence, 54, 269 Immunoglobulin, class, 55-63 switching, 59-63 C region, 26-29 genes, 23... 

Schuster GB, Landman U (2004) The mechanism of long-distance radical cation transport in duplex DNA Ion-gated hopping of polaron-like distortions. Top Curr Chem 236 139-161 Schussler H, Jung E (1989) Protein-DNA crosslinks induced by primary and secondary radicals. Int J Radiat Biol 56 423-435... 

The collimated (focused) ion beam leaves the hexapole and enters the ion gating system—the push and pull electrodes (Fig. 27). It is this system which provides the pulse of ions necessary for TOF analysis. When the region in front of the push electrode is filled by the ion beam, the ions are pushed towards the extraction electrodes. As this packet of ions leaves the gate it is reopened and another packet is admitted. At the extraction electrodes, ions are accelerated... 

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