Diffusion skin effect

Numerical search based on the known temperature dependence of the thermal diffusion coefficient a(0) and the skin effect revealed the following (1) the skin supersolidity enables the Mpemba effect (2) heat convection alone only raises the skin temperature (3) the critical ratio of the thermal diffusion coefficient s/ au > p /ps — 4/3 [24] and (4) the crossing temperature is sensitive to the volume of the hquid and the temperature of the drain. 

In the case of less reactive pofymer ems, sudi as the meta-isomer of the PMDA/ODA based pol>(amic ethyl ester), mbmd results were obtained when investigating the pofymer imidization behavior of this pofymer in the presence of various amines as illustrated in Table 3. All spedmens were soft-baked at 80 C for S minutes, treated with the amine for 10 minutes and finalfy cured at 200 for IS minutes. Although imidization levels of base-treated spedmens are significantly higher as compared to the non-treated spedmen, no distinctive trend in the data is observable. This is most likety due to factors sudi as the ability of the amine to effectivety diffuse into the polymer film or the actual residence time of the amine in the film at elevated temperatures as determined by volatility considerations. Another aq[>ect not reflected tty the experimental IR imidization data relates to surface effects. Since the IR measurement determines bulk imidization levels, skin-core effects are completely ne ected. Thus, it is quite conceivable that in case of low imidization levels, the surface of the film could actually be completely imidized with little or no imidization in the underlying material. This skin-effect may then prevent the diffusion of catalyst into the bulk of the polymer film. 

Dermal Effects. Some of the people in Woburn, Massachusetts, who had been chronically exposed to trace amounts of trichloroethylene and other substances in the drinking water reported skin lesions (Byers et al. 1988). These were maculopapular rashes that were said to occur approximately twice yearly and lasted 2-4 weeks. These skin conditions generally ceased 1-2 years after cessation of exposure to contaminated water. The limitations of this study are discussed in Section 2.2.2.8. A case study was published of a 63-year-old rural South Carolina woman exposed to trichloroethylene and other chlorinated hydrocarbons in her well water, who developed diffuse fascitis, although her husband did not (Waller et al. 1994). The level of trichloroethylene measured in the well water was 19 mg/L. Substitution of bottled water for drinking resulted in improved symptoms. 

The extent of hydration or solvation of a molecule also has a profound effect on the transport of the substance. The apparent solubility of the drug in both aqueous and nonaqueous media may be influenced by the absence or presence of moisture. Diffusion of drugs in polymeric systems may also be influenced by the hydration of the polymers and hydration of the membrane through which transport is occurring for example, skin hydration may enhance the diffusion of drug molecules significantly. 

Adverse effects include sedation, vivid dreams, dry mouth, depression, hallucinations, anxiety, dizziness, psychosis, and confusion. Livedo reticularis (a diffuse mottling of the skin in upper or lower extremities) is a common but reversible side effect. 

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