11 widely used nickel alloys were investigated with respect to corrosion stability and reactivity in nickel-sensitive individuals. Alloys with a nickel release in synthetic sweat exceeding 1 microgram/cm2/week gave a strong patch test reaction in nickel-sensitive persons; those with a release below 0.5 microgram/cm2/week showed weak reactivity with one exception. Nickel allergy is a health problem. It may be minimized by using nickel alloys with a corrosion level below 0.5 microgram/cm2/week. Action should be taken by dermatologists, industry and authorities to solve this neglected problem.

The impact of occlusion and the rôle of the counter ion on the permeation of nickel ions through skin have been examined using excised human skin. A highly sensitive electrochemical method was used to quantify the amount of nickel permeating the skin. The investigations show that nickel ions are capable of permeating the skin barrier when applied under occlusion. The process is slow, having a lag time of approximately 50 h. The permeation rate, and thus the physical amount being bioavailable, is considerably increased when aqueous nickel chloride is used in comparison with aqueous nickel sulphate. With respect to nickel permeation of the skin, we conclude that the choice of salt is an important consideration in patch testing.

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We report the transport properties (longitudinal and transverse conductivity, magnetoresistance and thermopower) of TMTSF-DMTCNQ for pressures up to 13 kbar and temperatures down to 1.2 K together with the phase diagram which results from these measurements. The most striking results are the occurrence of a first order insulator-metal low temperature transition as pressure is increased above 9.75 kbar and the properties of the metallic state. At pressures sufficiently high to quench the Peierls transition the helium temperature conductivity is greater than that found in any organic conductor at any temperature (σ∥ ≳ 105 (Ωcm)-1) and an enormous magnetoresistance (Δρ/ρ0 ~ 15) is found for a field of 75 kOe perpendicular to the conducting chains

The effect of the vehicle on the permeation rate of nickel ions through excised human skin was evaluated. Different hydrogels were compared with the standard patch test in petrolatum. A hydroxypropyl methylcellulose gel seemed to be the most promising alternative to petrolatum. It gave high bioavailability of the nickel and had good film forming properties leaving the nickel spread across the skin surface as a thin film without microscopically detectable crystals. The content of nickel in the various skin layers after cutaneous application was determined, and nickel was found to accumulate in the epidermis, probably due to epidermal binding. A significant amount of nickel was found also in the dermis. Occlusion and application of higher nickel concentrations increased the transport rate and must be considered in patch testing using this hydrogel. We conclude that nickel permeation is highly dependent of the choice of vehicle and the vehicle should, therefore, be an important consideration in patch testing with nickel.