Effects of Hydrogen Peroxide on Common Aviation Textiles
Modern transportation systems are subject to unintentional contamination from infected passengers, as well as deliberate contamination from criminals and political adversaries. Hydrogen peroxide has been used for years as a disinfectant in the medical community and is under consideration in the dilute vapor form as a decontaminant/disinfectant/sterilant for transportation vehicles like aircraft, buses, subway trains, ambulances, etc. Although the biological efficacy of STERIS Corporation’s Vaporized Hydrogen Peroxide (VHP® a registered trademark of the STERIS Corporation, Mentor, OH) technology has been demonstrated elsewhere, the compatibility of the process with typical aircraft materials has not been rigorously established. The present report documents a materials compatibility evaluation involving the effects of hydrogen peroxide exposure on the mechanical properties and flammability of the following commercial-grade textile materials: wool, nylon, polyester, Nomex®, and leather.
Controlling Shrinkage in Wool Fabrics: Effective Hydrogen Peroxide Systems
Alkaline hydrogen peroxide (H2O2) systems, including dicyandiamide, gluconic acid, and Triton X surfactant, used alone or followed by enzyme treatments, are investigated for their effectiveness in imparting shrinkage resistance to wool fabrics. Fractional factorial analysis shows that H2O 2 is the most important factor and enzyme the second contributing factor in shrinkage control. An effective H2O2, nonenzymatic system with Triton X-114 limits structural changes to surface smoothing of the fibers and yields a relative area shrinkage of 2.95%. Another effective H2O2 system, using the same pretreatment but followed by an enzymatic treatment with additives—polyacrylamide to restrict enzyme activity to the fiber surface and sodium sulfite to reduce disulfide linkages—yields 1.16% area shrinkage. The most important factor in shrinkage control is replacing the hydro phobicity of the wool's surface with an anionic charge through the formation of cysteic acid. This leads to the release of 18-methyleicosanoic (18-MEA) acid from the fiber surface and underlying cell membrane complex attached to the surface scales of wool through thioester linkages. TLC, FTIR, and EI-MS are used to prove the presence of fatty acids and 18-MEA in spent baths and in extracts of the treated fabrics. Imparting hydrophilicity to wool by conferring an anionic charge suggests new possibilities for wool reactivity.
Electrophysiological Studies of Penticainide (CM 7857), a New Antiarrhythmic Agent, in Mammalian Myocardium
The intracellular electrophysiologic properties of a new antiarrhythmic substance, penticainide, were studied in isolated rabbit, dog, and guinea pig myocardial preparations superfused or perfused with oxygenated Tyrode's solution. “Therapeutic” concentrations of penticainide (1.5 to 3 x 10-5 M) had little effect on sinus node automaticity; sinoatrial conduction was slightly delayed. In atrial, Purkinje and ventricular fibers, amplitude, and maximal rate of rise of phase 0 (dV/dtmax) were decreased by penticainide; Purkinje-ventricle conduction velocity was depressed. Penticainide did not significantly modify action potential duration (APD) of rabbit atria and dog ventricle and reduced APD and effective refractory period (ERP) of dog Purkinje and guinea pig ventricular fibers. Penticainide reduced APD heterogeneity of Purkinje-ventricle junction with a preferential effect at the gate and decreased tension amplitude of perfused papillary muscle in dog heart. The effect of penticainide on dV/dtmax was voltage and rate dependent; the resting block was weak. Thus, penticainide is a class 1 antiarrhythmic agent with properties of class 1B agents such as APD reduction and properties of class 1C agents such as slow recovery kinetic of rate-dependent block.