Impact of the Wall Conditioning Program on Plasma Performance in NSTX

High performance operating regimes have been achieved on NSTX (National Spherical Torus Experiment) through impurity control and wall-conditioning techniques. These techniques include HeGDC-aided boronization using deuterated trimethylboron, inter-discharge HeGDC, 350 C PFC bake-out followed by D2 and HeGDC, and experiments to test fueling discharges with either a He-trimethylboron mixture or pure trimethylboron. The impact of this impurity and density control program on recent advances in NSTX plasma performance is discussed

Validation of the High Performance Conduction-Cooled Prototype LTS Pulse Coil for UPS-SMES

A conduction-cooled low temperature superconducting (LTS) pulse coil has been developed as a key technology for UPS-SMES. We have been developing a 1 MW, 1 s UPS-SMES for a protection from a momentary voltage drop and an instant power failure. A conduction-cooled LTS pulse coil has excellent characteristics, which are adequate for a short-time uninterruptible power supply (UPS). The LTS coil has better cost performance over the HTS coil at present and the conduction cooling has higher reliability and easier operation than the conventional cooling schemes such as pool boiling with liquid helium or forced flow of supercritical helium. To demonstrate the high performances of the LTS pulse coil, we have fabricated a prototype coil with stored energy of 100 kJ and have conducted cooling and excitation tests. The successful performance test results including current shut-off test with a time constant of 1.3 s and repeated excitation of a triangular waveform with high ramp rate are reporte

Thiol-Based Redox Switches in Eukaryotic Proteins

Abstract For many years, oxidative thiol modifications in cytosolic proteins were largely disregarded as in vitro artifacts, and considered unlikely to play significant roles within the reducing environment of the cell. Recent developments in in vivo thiol trapping technology combined with mass spectrometric analysis have now provided convincing evidence that thiol-based redox switches are used as molecular tools in many proteins to regulate their activity in response to reactive oxygen and nitrogen species. Reversible oxidative thiol modifications have been found to modulate the function of proteins involved in many different pathways, starting from gene transcription, translation and protein folding, to metabolism, signal transduction, and ultimately apoptosis. This review will focus on three well-characterized eukaryotic proteins that use thiol-based redox switches to influence gene transcription, metabolism, and signal transduction. The transcription factor Yap1p is a good illustration of how oxidative modifications affect the function of a protein without changing its activity. We use glyeraldehyde-3-phosphate dehydrogenase to demonstrate how thiol modification of an active site cysteine re-routes metabolic pathways and converts a metabolic enzyme into a pro-apoptotic factor. Finally, we introduce the redox-sensitive protein tyrosine phosphatase PTP1B to illustrate that reversibility is one of the fundamental aspects of redox-regulation. Antioxid. Redox Signal. 11, 997-1014.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78110/1/ars.2008.2285.pd

Impact of the Wall Conditioning Program on Plasma Performance in NSTX

High performance operating regimes have been achieved on NSTX (National Spherical Torus Experiment) through impurity control and wall-conditioning techniques. These techniques include HeGDC-aided boronization using deuterated trimethylboron, inter-discharge HeGDC, 350 C PFC bake-out followed by D2 and HeGDC, and experiments to test fueling discharges with either a He-trimethylboron mixture or pure trimethylboron. The impact of this impurity and density control program on recent advances in NSTX plasma performance is discussed

Disulfide relays and phosphorylative cascades: Partners in redox-mediated signaling pathways

Modifications of specific amino-acid residues of proteins are fundamental in order to modulate different signaling processes among which the cascade of phosphorylation represents the most effective example. Recently, also, the modification of the redox state of cysteine residues of certain proteins, which is a widespread mechanism in the regulation of protein function, has been proposed to be involved in signaling pathways. Growing evidence shows that some transcription factors could be modulated by both oxidation and phosphorylation. In particular, the pathways regulated by the mitogen activated protein (MAP) kinases represent well-established examples of the cross talk between redox-mediated signaling and phosphorylative cascades. This review will compare the two modes of signal transduction and propose an evolutionary model of a partnership of the two mechanisms in the eukaryotic cell, with redox-mediated signals being more specific and ancestral and phosphorylative signals being more diffuse but predominant in signal propagation. © 2005 Nature Publishing Group All rights reserved