Theoretical Investigation of Wenzel and Cassie Wetting States on Porous Films and Fiber Meshes.

In this study, the wetting phenomenon on a thin, porous film covering a substrate was investigated on the basis of a classical equilibrium theory. The equilibrium contact angles of the Wenzel, hydrophobic Cassie, and hydrophilic Cassie states and the transition points between them were derived as functions of parameters, such as the porosity and specific surface area of the porous film. These expressions were applied to describe wetting on fiber mats/meshes. The equilibrium contact angles and transition points of the three wetting states on the fiber mesh covering the substrate are expressed as functions of parameters, such as fiber radius, roughness factor, and volume porosity of the fiber mesh. A fiber mesh can attain superhydrophobicity when it is composed of thin hydrophobic fibers with surface roughness and has an appropriate volume porosity.

Positive natural selection of TRIB2, a novel gene that influences visceral fat accumulation, in East Asia.

Accumulation of visceral fat increases cardiovascular mortality in industrialized societies. However, during the evolution of the modern human, visceral fat may have acted as energy storage facility to survive in times of famine. Therefore, past natural selection might contribute to shaping the variation of visceral fat accumulation in present populations. Here, we report that the gene encoding tribbles homolog 2 (TRIB2) influenced visceral fat accumulation and was operated by recent positive natural selection in East Asians. Our candidate gene association analysis on 11 metabolic traits of 5,810 East Asians revealed that rs1057001, a T/A transversion polymorphism in 3'untranslated region (UTR) of TRIB2, was strongly associated with visceral fat area (VFA) and waist circumference adjusted for body mass index (P = 2.7 × 10(-6) and P = 9.0 × 10(-6), respectively). rs1057001 was in absolute linkage disequilibrium with a conserved insertion-deletion polymorphism in the 3'UTR and was associated with allelic imbalance of TRIB2 transcript levels in adipose tissues. rs1057001 showed high degree of interpopulation variation of the allele frequency; the low-VFA-associated A allele was found with high frequencies in East Asians. Haplotypes containing the rs1057001 A allele exhibited a signature of a selective sweep, which may have occurred 16,546-27,827 years ago in East Asians. Given the predominance of the thrifty gene hypothesis, it is surprising that the apparently non-thrifty allele was selectively favored in the evolution of modern humans. Environmental/physiological factors other than famine would be needed to explain the non-neutral evolution of TRIB2 in East Asians.