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Genetic variants in the GP1BAand ITGA2genes have been proposed as potential modifiers for arterial vascular disease and bleeding disorders. Since ancestry may play an important role in the prevalence of these variants, we sought to determine their allele frequency and linkage disequilibrium in a collection of 1064 DNA samples from 51 ethnic groups. We studied haplotypes of ITGA2defined by single nucleotide substitutions at positions −52, 807, and 1648, and GP1BAvariants defined by sequence changes in positions −5 (Kozak), 1018 (T145M, HPA‐2) and 1285 (VNTR A, B, C and D). Frequency of haplotypes of ITGA2showed considerable variation across the different groups, with a higher prevalence of the haplotype −52C or T/807C/1648A observed in African compared with caucasian and Asian populations. The haplotypes 52C/807T/1648A and −52T/807T/1648A were not observed in caucasians or South Americans. While relative frequencies of the GP1BAKozak alleles were comparable across groups, the methionine allele (HPA‐2b) showed a higher frequency in Africa (0.26) than in the other groups. We also observed a high prevalence of the VNTR B allele in the African and Israeli populations. Haplotype analysis revealed incomplete linkage disequilibrium between the HPA‐2 and VNTR alleles. Incorporation of GP1BAvariants into the set of SNPs already genotyped by the HapMap project disrupted the pre‐existing haplotype block. These data provide a valuable resource for optimal selection of variants best tailored for association studies of vascular disease or bleeding disorders when examining individuals of different ancestral origins.

The low-dose gamma irradiation of dilute aqueous pectin solutions after appropriate adjustment of pH with hydrochloric or certain other inorganic acids leads to the formation of thermoreversible gels. Maximum gel strength is attained only under optimum conditions of pH, concentration, temperature, radiation dose, and exposure time, and only in the absence of oxygen and a number of radiation protectants.

Conjugated polymers (CPs) continue to be of interest for use as components of corrosion control coatings. For aluminum alloys, however, there is controversy and uncertainty regarding the protection mechanism(s), or indeed even whether corrosion protection by a CP is possible. Recent results from our laboratory indicate that, for an aluminum alloy coated with the oxidized form of polypyrrole (PPy), a passivation mechanism is not likely and that the dopant release mechanism may not be effective, especially in the presence of oxygen. An alternative approach is to utilize the neutral or reduced (n-doped) form of a conjugated polymer to cathodically protect the alloy and/or to serve as an oxygen scavenging coating. The CP coatings and alloy studied were neutral PPy and neutral or n-doped poly(2,3-dihexylthieno[3,4-b]pyrazine) on AA 2024-T3. Results from the scanning vibrating electrode technique and galvanic coupling measurements are presented to demonstrate the efficacy of this approach.

Protective multilayer coatings are designed, with each layer providing distinctive features to reduce the transport of water, ions, and oxygen from the environment to the substrate. The top coat provides the barrier, whereas the base coat/primer provides adhesion to the substrate as well as galvanic or passivation protection. The change in the coating capacitance during the ingress or egress of water is associated with the change in the dielectric property of the coating and can be monitored using the electrochemical impedance spectroscopy response of a high-frequency signal applied to the coating. The wetting and drying behaviors of epoxy and urethane single-layer coatings and epoxy primer/urethane top-coat two-layer coatings were experimentally measured. A hydrophilic room-temperature ionic liquid was used to simulate drying while maintaining a nonaqueous electrical contact to the coating. Embedded electrodes were used to access the top-coat–primer interface in the two-layer coating. Mathematical models were developed based on Fick’s second law for water transport in single-layer and two-layer coatings. Comparison of measured and simulated water uptake demonstrated that the assumptions used in the single-layer model were appropriate while the assumptions used for transport across the interface between the layers in the two-layer coating were inadequate.

Nonaqueous room-temperature ionic liquids (RTILs) offer a method of using electrochemical impedance spectroscopy (EIS) to analyze coatings without the confounding effects, such as plasticization, associated with an aqueous working fluid. Thermal cycling has been used as an accelerated testing method for ranking the corrosion protection of coatings. The influence of thermal cycling on the degradation of a coating was investigated using a hydrophilic RTIL as the electrolyte for the drying cycle of EIS experiments. The change in diffusion coefficient, saturated water volume fraction, and activation energy for the absorption and desorption of water by the coating was obtained.

The capacitance evolution of an organic coating undergoing cyclic wetting and drying conditions was monitored by single frequency electrochemical impedance spectroscopy. Monitoring of the drying condition was possible with the use of a hydrophilic room temperature ionic liquid and the methodology employed is presented. Experimental results associated with cyclic dilute NaCl wetting and ionic liquid drying are presented for an epoxy coating on an AA 2024-T3 substrate. The calculated capacitance evolutions associated with wetting and drying were generally consistent with Fick’s second law. The calculation of the water ingress and egress diffusion coefficients using a short-time approximate solution and a series solution to Fick’s second law are presented. The latter solution is shown to address the capacitance evolution better than the former with the ingress coefficient larger than the egress coefficient for a given exposed coating surface. There was agreement between the calculated diffusion coefficient ingress values for coating areas exposed to cyclic NaCl wetting—ionic liquid drying and cyclic NaCl wetting—natural drying conditions. Comparison of the impedance spectra for test areas indicated that the use of the ionic liquid as a drying medium influenced the electrochemical properties of the coating only after a number of cycles.