Blog Arasys Perfector - Xanya Sofra Weiss

Abstract Previous studies suggest that bulk fluid flow by electroosmosis is a significant factor in iontophoresis and may provide an explanation for the observed enhanced transport of neutral species. In a charged membrane, the solution carries a net charge and thus experiences a volume force in an electric field, which causes volume flow (J _v in the direction of counterion flow. J _v data were obtained for hairless mouse skin (HM) as a function of pH, concentration of NaCl, current density, and time. Volume flow was measured by timing fluid movement in horizontal capillary tubes attached to the anode and cathode (Ag/AgCl) compartments. By convention, the sign of J _v is taken as positive when the volume flow is in the same direction as positive current flow. Experimental mean values were in the range 0 to + 37 µl/cm² hr, depending on the experimental conditions. Volume flow of this magnitude is large enough to have significant impact on flow of both ions and neutral species. The positive sign for J _v indicates that HMS is negative in the pH range studied (3.8–8.3). J _v decrease with time, decrease with increasing NaCl concentration, are much lower at pH 3.8 than at the higher pH’s, and increase with current density. Effective transference numbers, determined from membrane potential measurements, showed significant pH dependence, consistent with a small negative charge on the membrane at mid pH’s and charge reversal around pH 4. Both electrical resistance and J _v data indicate changes in transport properties occur when HMS is subjected to an electric field.

Abstract Latex gloves are used by surgical staff to avoid exposure to patient body fluids, thus reducing the risk of contracting bloodborne viral diseases, such as hepatitis C and HIV. We studied the efficacy of the surgical barrier provided by latex gloves, before and after use in the operating theater. The electrical conductivity, insulation and mechanical resistance of glove latex were investigated, using routine supplies of surgical gloves. Latex structure was assessed by scanning electron microscopy and by mercury intrusion porosimetry. Latex is subject to hydration, a phenomenon associated in the laboratory with the loss of its electrical insulation properties. Such glove latex properties were found to be highly variable, with latex hydration times varying between 2 and more than 30 min. Rapidly hydrating gloves showed increased permeability to methylene blue, associated with higher levels of porosity. Thirty min of surgical use was associated with measurable hydration of glove latex and a statistically significant loss of electrical and mechanical resistance, with rupture load decreasing by 24%. Electronic control of the insulation properties of gloves during surgery permits early detection of hydration, and allows prompt correction by glove change, before the gloves lose their electrical and mechanical competence.