How can parents make a difference? Longitudinal associations with adolescent sexual behavior.

Parents have the potential to protect against adolescent sexual risk, including early sexual behavior, inconsistent condom use, and outcomes such as pregnancy and sexually transmitted infections (STIs). Identification of the specific parenting dimensions associated with sexual risk in adolescence and young adulthood is necessary to inform and focus prevention efforts. The current study examined the relation of proximal (e.g., discussions of sexual costs) and distal (e.g., parental involvement, relationship quality) parenting variables with concurrent and longitudinal adolescent sexual behavior. The National Longitudinal Study of Adolescent Health (Add Health) provided a nationally representative sample with information about the family using adolescent and parent informants. Longitudinal information about sexual risk included adolescent condom use and adolescent sexual initiation, as well as young adult unintended pregnancy, reports of STIs, and biological assay results for three STIs. Higher parent–adolescent relationship quality was associated with lower levels of adolescent unprotected intercourse and intercourse initiation. Better relationship quality was also associated with lower levels of young adult STIs, even when accounting for prior sexual activity. Unexpectedly, more parent reports of communication regarding the risks associated with sexual activity were negatively associated with condom use and greater likelihood of sexual initiation. These results demonstrate that parents play an important role, both positive and negative, in sexual behavior, which extends to young adulthood, and underscores the value of family interventions in sexual risk prevention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fabrication of Li2TiO3 spherical microparticles from TiCl4 by a classical, inorganic sol-gel route; characteristics and tritium release properties

Medium sized spherical particles of Li₂TiO₃ (with diameters below 100 m) can be fabricated by a classical, inorganic sol-gel process, from commercially available TiCl₄. Elaborated process consists of the following main steps: (1) dissolving of TiCl₄ in concentrated aqueous HCl; (2) formation of sol emulsion in 2-ethylhexanol-1 containing the surfactant SPAN-80 (EH); (3) gelation of emulsion drops by extraction of water with partially dehydrated EH; (4) impregnation of gel to Li : Ti molar ratio (MR) = 2; (5) thermal treatment at 1200°C. This temperature can be significantly lowered (to 750°C) by chemical treatment of chloride precursors (gels or starting solution TiCl₄) with aq. ammonia or better with nitric acid. Tritium release from sol-gel made Li₂TiO₃ micro-spheres were found very close to that observed for other traditional materials, however for the first sample process starts slightly earlier.     

Control of Surface Morphology,Adhesion and Friction of Colloidal Gels with Lamellar Surface Interactions

Despite recent advances in polyelectrolyte systems, designing responsive hydrogel interfaces to meet application requirements still proves challenging. Here, semicrystalline colloidal gels composed of poly(methacrylamide-co-methacrylic acid) are investigated in water with storage moduli in the MPa range. A combination of SEM, X-ray scattering, and NMR reveals the evolution of the colloidal microstructure, crystallinity, and hydrogen bonding with varying monomer ratio. The gels with the finest colloidal microstructure exhibit the most dissipative rheological behavior and are selected for the study of their interfacial characteristics and underlying interactions. Microstructure stabilization and dynamics results from short-range (attractive) hydrogen bonding and hydrophobic forces, and long-range (repulsive) electrostatic interactions—the “SALR” pair potential. Further, the gel's surface exhibits a submicron colloidal topography that greatly determines (colloidal-like) friction as a result of the viscoelastic deformation of the colloidal network, while electrostatic near-surface interactions propagate in lamellar adhesion. The dynamic and reversible nature of the involved interactions introduces a stimulus responsive behavior that enables the electrotunability of adhesion and friction. This study advances the knowledge necessary to design complex hydrogel interfaces that enable spatial and dynamic control of surface properties, which is of relevance for applications in biomedical devices, soft tissue design, soft robotics, and other engineered tribosystems.