Dynamics of Spreading of Chainlike Molecules with Asymmetric Surface Interactions

In this work we study the spreading dynamics of tiny liquid droplets on solid surfaces in the case where the ends of the molecules feel different interactions with respect to the surface. We consider a simple model of dimers and short chainlike molecules that cannot form chemical bonds with the surface. We use constant temperature Molecular Dynamics techniques to examine in detail the microscopic structure of the time dependent precursor film. We find that in some cases it can exhibit a high degree of local order that can persist even for flexible chains. Our model also reproduces the experimentally observed early and late-time spreading regimes where the radius of the film grows proportional to the square root of time. The ratios of the associated transport coefficients are in good overall agreement with experiments. Our density profiles are also in good agreement with measurements on the spreading of molecules on hydrophobic surfaces.Comment: 12 pages, LaTeX with APS macros, 21 figures available by contacting [email protected], to appear in Phys. Rev.

Food Packages for Senior Consumers – Preferences on Information and Labelling

Senior consumers are a heterogenic group covering a wide range of ages, physical capabilities, lifestyles and purchasing power. Only little research is published about the ageing consumers’ expectations and experiences regarding food packaging. However, defining key packaging factors might provide a valuable tool to improve consumption of suitable food for older people. Therefore, the present study aims to explore possible relationships between packaging preferences and type of product information among senior consumers. In this paper results of a quantitative consumer study are presented. The study was done in the Netherlands using the SenTo (Seniors of the Future) internet panel (age = 55+, n=400). All participants had at least some influence on the grocery shopping in their household. The questionnaire included questions on which information the consumers would be interested in reading on a food packaging and how appealing they experienced certain labels and hallmarks. Seniors did not find all packaging labels included in this study equally appealing. They expressed a special interest in reading product quality related information. In contrast, only limited interest was expressed in the information that a product is designed especially for seniors. Age related issues, such as difficulties with opening packages, seems not recommendable for communicating product information to seniors. Instead, it seems advisable to ensure that packaging design communicates a positive image of older age and personal benefits