This paper discusses the testing and evaluation of the Teflon FEP.įrederking, T. The results of the Teflon FEP sample evaluation and additional testing of pristine Teflon FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations, and that the damage increased with the combined total dose of electrons, protons, LTV and x-rays along with thermal cycling. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. Dever, Joyce A.ĭuring the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon' FEP (fluorinated ethylene propylene), used as the outer layer of the multi-layer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. Our results show that the function in heme iron extraction is conserved in the two orthologous systems. coli FepA ortholog (EfeO) cannot replace FepA in FepB-driven iron release from heme indicating protein specificity in these activities. coli ortholog ii) that it has low peroxidase activity, comparable to that of EfeB iii) that both FepA and FepB drive heme iron utilization, and both are required for this activity and iv) that the E.
aureus FepB protein binds both heme and PPIX with high affinity, like EfeB, the E. Results presented here indicate: i) that the S. To test this hypothesis, we undertook characterization of the Staphylococcus aureus FepABC system. Given the high level of sequence conservations between EfeUOB orthologs, we hypothesized that heme might be the physiological iron substrate for the other orthologous systems. Nevertheless, in the case of Escherichia coli, the EfeUOB system has been shown to recognize heme and to allow extracytoplasmic heme iron extraction via a deferrochelation reaction. Many bacterial EfeUOB systems have been implicated in iron uptake, but a prefential iron source remains undetermined. They consist of: EfeU, a protein similar to the yeast iron permease Ftrp1 EfeO, an extracytoplasmic protein of unknown function and EfeB, also an extracytoplasmic protein with heme peroxidase activity, belonging to the DyP family. Turlin, Evelyne Débarbouillé, Michel Augustyniak, Katarzyna Gilles, Anne-Marie Wandersman, CécileĮfeUOB-like tripartite systems are widespread in bacteria and in many cases they are encoded by genes organized into iron-regulated operons. Staphylococcus aureus FepA and FepB proteins drive heme iron utilization in Escherichia coli. Miller (1988) Adsorption of.Freon® 12 A’ A2 A A2 B’ B Freon® 22 - A A A A A Freon® 113 - A A B - Freon* TF - A A B A A Fuel Oils D A’ B A2 A A Furfural D A’ A D A B Gallic can Conference on Hydrogeology, Hazardous Wastes Jones, J.N. Because they were.Proceedings of Second Canadian/Ameri- Dekker, Inc.
Sorption of Trace-Level Organics by ABS, FEP, FRE and FRP Well CasingsĪnd there did not appear to be any controls that free energy of their surface by adsorption.