Anaerobically aged

On extended overcure, which can be considered as an anaerobic aging process, the compound containing the antireversion agent exhibits a higher tensile strength as shown in Table 14.57 together with additional physical properties. 

The Tg-value development during anaerobic ageing of six differently formulated foam systems was then measured. Formulation 2 (MDI index 115) and formulation 1 (MDI index 135) show the effect of a MDI index decrease from the standard value of 135 to 115. These two systems also containted some glycerol next to the standard polyol. Formulation 3 is equal to formulation 1 but contains no glycerol. The formulations 3 to 6 (MDI index 135) were added to show the effect of a partial replacement of isocyanate by respectively 10% (4), 15% (5) and 20% (6) of a liquid epoxy resin. 

Polymer Solutions Solutions were made up to approximately 0.2 wt% with deionized, distilled water, or NaCI containing aqueous brine as indicated. Oxygen was not excluded since similar PAM hydrolysis characteristics were observed in previous aerobic vs. anaerobic aging studies. 

Air ageing and anaerobic ageing were carried out on vulcanisates under severe conditions and changes in ultimate strength properties and De Mattia cut growth performance were recorded (Table 10). 

The characteristics of high c/ -polyisoprene compounds in anaerobic ageing conditions show improved aged property retention for certain types of formulations (see Section 7). Such compounds are particularly interesting in tyre carcass constructions where the ingress of air is minimal. Internal temperatures in heavy duty truck and bus tyres exceed the levels normally considered practical for either natural or synthetic polyisoprene. The retention of physical properties and the extended flex life of high cis-polyisoprene under these anaerobic conditions can be beneficial to the tyre constructer. 

BIS(CITRACONIMIDOMETHYL)BENZENEON THE AEROBIC AND ANAEROBIC AGEING OF DIENE RUBBER VULCANIZATES... 

Reversion of sulphur-based crosslinks continues to a problem for NR compounders. Reversion is the thermal degradation of polysulphidic crosslinks leading to a reduction of crosslink density and an introduction of main chain modifications. In practice, reversion leads to a decline in compound physical properties. Reversion occurs when compounds are overcured or when vulcanisates are exposed to anaerobic ageing. Ideally, a... 

Demonstration of the anaerobic degradation of purines belongs to the golden age of microbiology and was appropriately discovered in Beijerinck s laboratory in Delft. Liebert (1909) obtained a pure culture of an organism that was able to grow anaerobically with 2,6,8-trihydroxypurine (uric acid). 

Cholecystectomy Enteric gram-negative bacilli, anaerobes Cefazolin 1 g x 1 for high-risk patients Laparoscopic None High-risk patients only (acute cholecystitis, common duct stones, previous biliary surgeiy, jaundice, age >60 years, obesity, diabetes mellitus) IA... 

Svendsen and Jollick (1978) studied the microbes in the castor sacs and anal glands of the beaver, C. canadensis. No bacteria cultured from the castor sacs, while the anal sacs contained the aerobe Escherichia coli and the anaerobe Bacteroidesfragilis. Species and numbers of bacteria did not differ between the sexes, age classes, or beaver colonies. 

L D. Doxycycline is the preferred parenteral tetracycline for the primary state of Lyme disease in adults and children older than 8 years of age. Penicillin V (A) would be ineffective. Erythromycin (B) and clarithromycin (C) also are not effective against Borrelia burgdorferi, the gram-negative anaerobe organism responsible for Lyme disease. 

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