Poly oxygen uptake

We have studied the oxygenation of ferroheme bound to a polymer ligand in the solid state98. The profiles of oxygen uptake by powders of polymer-heme complexes were measured by volumetry, as shown in Fig. 22. The heme complex embedded in the porous polymer matrix or in the poly(electrolyte) aggregate takes up... 

Oxygen uptake measurements can give considerable mechanistic information. In normal peroxyl radical reactions the G(02-uptake) will range between 3 x 10 7 and 6 x 10 7 mol J1 (Table 8.2). The lower value will be found when half of the 02 is reformed (for example, the formate system), the higher value when all 02 is consumed during the decay of the peroxyl radicals. As soon as G(02-uptake) exceeds the upper limit of 6 x 10 7 mol J, a chain reaction must prevail [examples are some polymers including poly(U)]. However, there is also the interesting situation that G(02-uptake) is below 3 x 10 7 mol JThis means that some of the radicals do not react with 02. A case in point are the OH-induced reactions of purines (Chap. 10.3). 

Figure 5. Oxygen uptake of poly(phenylene oxide) and model compounds. Pyrex-filtered Hg lamp, 1-M benzene solution.

Values of p determined by the various techniques are summarized in Table II. A plot of the oxygen-uptake data and /3-values obtained by the slope-intercept method (21) appear in Figure 3. The reactivity of ds-3-hexane (ft 0.6 0.2M) was found to be about a factor of four less than that of ds-1,4-poly butadiene (p 2.3 0.2 M), whereas 1,4-polyisoprene (p 0.16 0.05M) is almost comparable in reactivity to its model olefin 3-methyl-3-hexene 0.13 0.Q4M). 

Oxygen Uptake by Cobalt Poly(ethyleneimine) Complexes and its Electroreduction at an Electrode (Section 9.4) [26,64]... 

Our current hypothesis is that the butadiyne thermopolymer is structurally related to melt polymerized substituted butadiyne polymers. The absence of substituent groups allowed us to make a direct observation of the gradual decrease in triple bond concentration with increasing temperature of heat treatment. This is consistent with the conversion of a polyene to a polyacene structure, although it does not exclude the polyphenyl structure. The presence of an aliphatic C-H band at 2935 cm and its intensity increase with heat eatment is paralleled by the poly(diphenyldiacetylene) system. There is an oxygen uptake (4% 0) on exposure to air and a strong ESR signal both of which e also characteristic of the poly(diphenyldiacetylene) system. These observations are not understood at this time. 

This oxygen uptake and release by the aqueous solution of cobalt-poly(ethyleneimine) complex provides the following practice for students to demonstrate the oxygen-separation capability from air. 

Modification of aliphatic mono- and poly-amine sorbents by incorporation of hard oxygen donor ligands, through Schiff s base reaction with carbonyl containing compounds, was found to significantly improve the uptake of Fe(in), known to act as hard acid. ... 

Amphibole (crocidol-ite and amosite), serpentine (chrysotile), wollastonite, riebeglass beads Human and rabbit mesothelial cells in vitro Oligonucleosomal DNA fragmentation, loss of membrane phospholipid asymmetry, and nuclear condensation Asbestos fibres, not control particles, induced apoptosis in mesothelial cells by all assays. Induction of apoptosis was dose-dependent for all types of asbestos, with crocidolite (5 ng/cm ) inducing 15.0 1.1 % apoptosis versus control particles <4 %. Apoptosis induced by asbestos, but not by actinomycin D, was inhibited by extracellular catalase, superoxide dismutase in the presence of catalase, hypoxia (8 % oxygen), deferoxamine, 3-aminobenzamide [an inhibitor of poly(ADP-ribosyl) polymerase], and cytochalasin B. Only catalase and cytocha-lasin B decreased fibre uptake. Broaddus et al. (1996) Escape from asbestos-induced apoptosis could allow the abnormal survival of mesothelial cells with asbestos-induced mutations... 

Koudelka [16] has introduced a planar two-electrode oxygen sensor with a planar Ag/AgCl/Cl reference electrode with a hydrogel internal electrolyte (Fig. 11.7). The electrode was covered with poly(2-hydroxyethyl methacrylate), pHEMA, by polymerisation at room temperature. After polymerisation, the pHEMA was soaked in an electrolyte solution containing potassium chloride. Finally, the entire sensor was covered with silicon rubber (50 pm) to stabilise the fragile pHEMA layer after water uptake. 

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