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This Letter describes the generation of 2D colloidal lattices in microchannels by coupling the laminar flow of dispersions of spherical colloids and geometrical confinement. We describe a nonequilibrium, convective, mechanism leading to formation of ordered 2D structures of both closed-packed hexagonal and non-closed-packed rhombic symmetries. The number and types of possible lattices is determined by the ratio of the width of the channel to the diameter of the particle. The structures tend to return to a regular lattice after a defect is introduced; that is, for example, they tend to self-repair disorder induced by particle polydispersity, contaminants, and flow instabilities. The stability of different lattices is analyzed numerically for particles with different polydispersity.
Current affairs: The electron-transport properties of a metal–molecule–metal junction based on two contacting redox-active self-assembled monolayers of [Ru(NH3)5(NC5H4-4-CH2NHCO(CH2)10SH](PF6)2 (see picture) is described. The junction becomes conductive when the electrode potentials are adjusted to the formal potential of the redox centers and shows diode- and transistor-like characteristics analogous to those of solid-state devices. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2004/z53945_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
No abstract is provided for this article.
No abstract is provided for this article.
Elastic spherical shells loaded under uniform pressure are subject to equal and opposite compressive probing forces at their poles to trigger and explore buckling. When the shells support external pressure, buckling is usually axisymmetric; the maximum probing force and the energy barrier the probe must overcome are determined. Applications of the probing forces under two different loading conditions, constant pressure or constant volume, are qualitatively different from one another and fully characterized. The effects of probe forces on both perfect shells and shells with axisymmetric dimple imperfections are studied. When the shells are subject to internal pressure, buckling occurs as a nonaxisymmetric bifurcation from the axisymmetric state in the shape of a mode with multiple circumferential waves concentrated in the vicinity of the probe. Exciting new experiments by others are briefly described.
Three loci were recently identified for central adiposity from a genome wide association study (MSRA [rs545854; G/C], LYPLAL1 [rs2605100; G/A], TFAP2B [rs987237; A/G]). Central obesity is a strong risk factor for type 2 diabetes (T2D). Therefore, we hypothesized that these single nucleotide polymorphisms (SNPs) would be associated with increased risk of T2D and may influence circulating adipokine concentrations. Participants from two large case control studies nested in the Nurses' Health Study (3394 women, 1245 cases) and the Health Professionals Follow-up Study (2154 men, 862 cases) were genotyped for these SNPs. The association of these SNPs with plasma adipokine concentrations was determined among a subgroup of women without diabetes (n=987). After adjustment for age and other risk factors of diabetes, the MSRA variant was associated with an increased T2D risk in men only, with an adjusted OR of 1.30 (95% CI: 1.09-1.56) associated with each copy of the variant allele. In pooled analyses of men and women, each additional copy of the LYPLAL1 allele (G) was associated with 9% increased T2D risk (adjusted OR 1.09; 95%CI: 0.99-1.19). No significant associations were seen with the TFAP2B SNP with a pooled adjusted OR of 1.05 (95% CI: 0.95-1.17) per allele copy. In addition, carriers of the MSRA risk variant had lower percent high molecular weight adiponectin (-2.1%, p=0.04). Carriers of the TFAP2B risk variant, however, had lower leptin levels (-2.7 ng/ml, p=0.005). These findings suggest potential associations of novel central obesity genes with T2D risk and adipokine regulation.
Abstract The study of the ionization of carboxylic acid groups at the interface between organic solids and water demonstrates broad similarities to the ionizations of these groups in homogeneous aqueous solution, but with important systematic differences. Creation of a charged group from a neutral one by protonation or deprotonation (whether -NH3 + from -NH2 or -CO2- from -CO2H) at the interface between surface-functionalized polyethylene and water is more difficult than that in homogeneous aqueous solution. This difference is probably related to the low effective dielectric constant of the interface (ε≃9) relative to water (ε≃80). It is not known to what extent this difference in ε (and in other properties of the interphase, considered as a thin solvent phase) is reflected in the stability of the organic ions relative to their neutral forms in the interphase and in solution, and to what extent in differences in the concentration of H+ and OH- in the interphase and in solution. Self-assembled monolayers (SAMs)-especially of terminally functionalized alkanethiols (HS(CH2)nX) adsorbed on gold-provide model systems with relatively well-ordered structures that are useful in establishing the fundamentals of ionization of protic acids and bases at the interface between organic solids and water. These systems, coupled with new analytical methods such as photoacoustic calorimetry (PAC) and contact angle titration, may make it possible to disentangle some of the complex puzzles presented by proton-transfer reactions in the environment of the organic solid-water interphase. Keywords: Contact angle titrationphotoacoustic calorimetrypolyethylene carboxylic acidcontact anglepolymer surfaceswettingself-assembled monolayers
Molten deposits based on calcium-magnesium alumino-silicates (CMAS), originating from siliceous debris ingested with the intake air, represent a fundamenta
