Anionic Polymerization of the Barium Salt of One-Ended Living Polystyrene. I. Conductance and Kinetic Studies

1975 ◽  
Vol 8 (4) ◽  
pp. 396-400 ◽  
Author(s):  
B. De Groff ◽  
M. Van Beylen ◽  
M. Szwarc
Keyword(s):  
Anionic Polymerization ◽  
Kinetic Studies ◽  
Barium Salt

Anionic Polymerization of the Barium Salt of One-Ended Living Polystyrene. 2. The Effect of Added Barium Tetraphenylboride

1977 ◽  
Vol 10 (3) ◽  
pp. 598-602 ◽  
Author(s):  
B. De Groof ◽  
W. Mortier ◽  
M. Van Beylen ◽  
M. Szwarc
Keyword(s):  
Anionic Polymerization ◽  
Barium Salt

Novel Ether Modifiers for Anionic Polymerization of Isoprene

1998 ◽  
Vol 71 (1) ◽  
pp. 62-69 ◽  
Author(s):  
W. L. Hsu ◽  
A. F. Halasa ◽  
T. T. Wetli
Keyword(s):  
Anionic Polymerization ◽  
Kinetic Studies ◽  
Polymerization Rate ◽  
Skid Resistance ◽  
Large Excess ◽  
Tire Industry ◽  
Rate Difference ◽  
Alkyl Groups ◽  
Alkyl Ethers ◽  
Isoprene Polymerization

Abstract Because of demands on tire skid resistance, polyisoprenes with high 3,4-content are of particular interest to the tire industry due to their inherently better grip properties. Polar bidentate modifiers such as TMEDA and DIGLYME are widely used in organo-lithium catalyzed isoprene polymerization to increase 3,4-content. However, neither modifier is very effective for making high Tg polyisoprenes due to the fact that a retarded polymerization rate was found for the former while a large excess of modifier was needed for the latter. The new modifiers based on the alkyl ethers of tetrahydrofurfuryl alcohol with alkyl groups from one to six carbon atoms were found to be very effective for producing polyisoprenes with high 3,4-contents. Kinetic studies on both TMEDA and the new ether modified isoprene polymerizations were conducted. The results and the plausible explanation of the rate difference for both systems are discussed.

Kinetic Studies of Anionic Polymerization of Polystyryl Salts in Tetrahydropyran and 2-Methyltetrahydrofuran

1969 ◽  
Vol 2 (6) ◽  
pp. 575-580 ◽  
Author(s):  
M. Van Beylen ◽  
M. Fisher ◽  
J. Smid ◽  
M. Szwarc
Keyword(s):  
Anionic Polymerization ◽  
Kinetic Studies

Fluorocitrate Neural Dystrophy of the Guinea Pig Cochlea

1975 ◽  
Vol 33 ◽  
pp. 368-369
Author(s):  
G.J. Spector ◽  
C.D. Carr ◽  
I. Kaufman Arenberg ◽  
R.H. Maisel
Keyword(s):  
Hearing Loss ◽  
Hair Cells ◽  
Sodium Phosphate ◽  
Sensory Cells ◽  
Barium Salt ◽  
Perfusion Medium ◽  
Cochlear Hair Cells ◽  
Neural Degeneration ◽  
Sodium Phosphate Buffer ◽  
Cochlear Neurons

All studies on primary neural degeneration in the cochlea have evaluated the end stages of degeneration or the indiscriminate destruction of both sensory cells and cochlear neurons. We have developed a model which selectively simulates the dystrophic changes denoting cochlear neural degeneration while sparing the cochlear hair cells. Such a model can be used to define more precisely the mechanism of presbycusis or the hearing loss in aging man.Twenty-two pigmented guinea pigs (200-250 gm) were perfused by the perilymphatic route as live preparations using fluorocitrate in various concentrations (15-250 ug/cc) and at different incubation times (5-150 minutes). The barium salt of DL fluorocitrate, (C6H4O7F)2Ba3, was reacted with 1.0N sulfuric acid to precipitate the barium as a sulfate. The perfusion medium was prepared, just prior to use, as follows: sodium phosphate buffer 0.2M, pH 7.4 = 9cc; fluorocitrate = 15-200 mg/cc; and sucrose = 0.2M.

Flavin radicals, conformational sampling and robust design principles in interprotein electron transfer: the trimethylamine dehydrogenase-electron-transferring flavoprotein complex

2004 ◽  
Vol 71 ◽  
pp. 1-14
Author(s):  
David Leys ◽  
Jaswir Basran ◽  
François Talfournier ◽  
Kamaldeep K. Chohan ◽  
Andrew W. Munro ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Kinetic Studies ◽  
Molecular Assembly ◽  
Conformational Sampling ◽  
Trimethylamine Dehydrogenase ◽  
Key Residues ◽  
Electron Transferring Flavoprotein ◽  
Electron Transfer Complex

TMADH (trimethylamine dehydrogenase) is a complex iron-sulphur flavoprotein that forms a soluble electron-transfer complex with ETF (electron-transferring flavoprotein). The mechanism of electron transfer between TMADH and ETF has been studied using stopped-flow kinetic and mutagenesis methods, and more recently by X-ray crystallography. Potentiometric methods have also been used to identify key residues involved in the stabilization of the flavin radical semiquinone species in ETF. These studies have demonstrated a key role for 'conformational sampling' in the electron-transfer complex, facilitated by two-site contact of ETF with TMADH. Exploration of three-dimensional space in the complex allows the FAD of ETF to find conformations compatible with enhanced electronic coupling with the 4Fe-4S centre of TMADH. This mechanism of electron transfer provides for a more robust and accessible design principle for interprotein electron transfer compared with simpler models that invoke the collision of redox partners followed by electron transfer. The structure of the TMADH-ETF complex confirms the role of key residues in electron transfer and molecular assembly, originally suggested from detailed kinetic studies in wild-type and mutant complexes, and from molecular modelling.

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