Shuttle mark

Woven, shuttle mark A fine filling line caused by damage to a group of warp yarns by weaving shuttle abrasion. 

C. WiUiams and L. RonquiUo, Thermal Protection System for the Space Shuttle External Tanks, 6th SPI Inti., Tech. /Mark. Conf, 1983, pp. 90—100. 

By comparing the electrochemical behavior of 10(4) 1 and that of 7(4) +, it is obvious that there exists a pronounced kinetic biisoquinoline effect. This ligand leads to a markedly more mobile electrochemically driven machine than the previous copper-based shuttle. The endocyclic but nonsterically protecting nor hindering nature of dpbiiq is with no doubt responsible for this spectacular improvement. 

The Baylis-Hillmann reaction is another bench-mark reaction in which ionic liquids have been successfully tested. The catalytic cycle of the Baylis-Hillmann reaction is reported in Figure 7. The catalyst is a highly nucleophilic tertiary amine, generally DABCO, or a tertiary phosphine, which adds to the oc,p-unsaturated electrophile in a 1,4 fashion to deliver an enolate which, in turn, adds to the aldehyde. The critical step is now a proton transfer from the enolisable position to the oxygen atom this process is catalysed by an alcohol which plays the role of a proton shuttle between the two foregoing positions. Once a P-ammonium enolate is formed, a rapid P-elimination takes place, delivering the Baylis-Hillmann condensation product. 

Figure 36-4. The activation of fatty acids and transport into the mitochondrion via the carnitine shuttle. (Reproduced, with permission, from D.B. Marks, et al, Basic Medical Biochemistry A Clinical Approach, Philadelphia Lippincott...

Support for this explanation came inadvertently in 1991, when astronauts aboard Discovery released various gases, including carbon dioxide, neon, xenon, and nitric oxide, from the cargo bay in the course of an unrelated experiment. Expelled one at a time, these gases scattered onto the surface of the shuttle s tail. The nitric oxide caused the normal shuttle glow to intensify markedly, but the other gases had no effect on it. 

Let s not kid ourselves, even a seasoned engineer can miss the mark by a fair amount. Whenever I make a presentation, I start by showing the graph in Fig. 39.1. This material was taken from the Report of the Presidential Commission on the Space Shuttle Challenger Accident, June 6, 1986, Washington, D.C. 

Box mark n. A fine line parallel to the filling caused by shuttle damage to a group of filling yarns. 

Shuttle chafe mark n. A fabric defect that is usually seen as groups of short, fine lines across the fabric, often running for some... 

Shuttle-based CFM LN2 demo was far too high to justify building a full flight demonstration. Therefore, the end of Challenger nearly marked the end of design and analysis of CFME, CFMF, and all other Shuttle-based CFM demonstrations. 

Chafe Mark See Abrasion Mark and Shuttle Chafe Mark. 

Shuttle Chafe Mark n A fabric defect that is usually seen as groups of short, fine lines across the fabric, often running for some distance in the piece and usually in the same area. Although these marks nm in the direction of the filling, they are actually caused by the shuttle rubbing across and damaging the warp ends, producing a duU, chalky appearance. 

Coupling Reactions. Palladium pivalate is an effective catalyst for mild and efficient direct arylation reactions. One account described the intramolecular arylation phenolic ethers (eq 1). Initial optimization with Pd(OAc)2 in conjunction with electron-deficient phosphines led to the desired biphenyl in low yield. Upon the addition of carboxylic acid additives, the yield improved markedly with the optimal additive being pivalic acid. Indeed it was determined that the additive was not needed when Pd(OPiv)2 was errqtloyed as a catalyse although improved yields were observed when the title compound was used in conjunction with the acid additive. The role of the pivalate is believed to be that of a proton shuttle in a concerted metallation-deprotonation (CMD) sequence. A further advantage of using Pd(OPiv)2 was the rate enhancement of the arylation with most reactions complete in less than 6 h (vs. 12 or more hours with Pd(OAc)2). The catalyst was applied to a range of electron-rich and -deficient arenes with good to excellent yields. 

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