Effect of soluble polymer binder on particle distribution in a drying particulate coating.

Soluble polymer is frequently added to inorganic particle suspensions to provide mechanical strength and adhesiveness to particulate coatings. To engineer coating microstructure, it is essential to understand how drying conditions and dispersion composition influence particle and polymer distribution in a drying coating. Here, a 1D model revealing the transient concentration profiles of particles and soluble polymer in a drying suspension is proposed. Sedimentation, evaporation and diffusion govern particle movement with the presence of soluble polymer influencing the evaporation rate and solution viscosity. Results are summarized in drying regime maps that predict particle accumulation at the free surface or near the substrate as conditions vary. Calculations and experiments based on a model system of poly(vinyl alcohol) (PVA), silica particles and water reveal that the addition of PVA slows the sedimentation and diffusion of the particles during drying such that accumulation of particles at the free surface is more likely.

Adults' knowledge and behaviors related to human papillomavirus infection.

BACKGROUND: Our objective was to assess adults' knowledge, risk behaviors, and preference for information about human papillomavirus (HPV). METHODS: A cross-sectional study using a self-administered questionnaire given in 3 locations (a university health service and 2 community family practice offices); 289 people completed the questionnaire. The primary outcome measure was a knowledge score calculated from the responses on specific items in the questionnaire. This knowledge score was developed by other investigators and has acceptable psychometric properties. RESULTS: Knowledge about HPV was low, with an average knowledge score of 5.50 (possible scores ranged from 0 to 14) and a mode of 0. Knowledge scores were significantly higher in women (P =.001) and married adults (P =.001). Knowledge scores were inversely related to age (P =.004) and positively correlated with years of education (P =.001) and self-assessment of knowledge (P <.001). Knowledge scores were positively correlated with condom use (P =.05) but not significantly associated with other risk behaviors. The most frequently desired time to receive information about HPV was before becoming sexually active. CONCLUSIONS: Adults seen in a typical family physician's office have limited knowledge of HPV. One tool family physicians can use to identify those with the least amount of knowledge is to ask patients how informed they are about HPV. The preferred time to receive information about HPV was before a patient became sexually active. However, it remains unclear whether educational intervention or knowledge changes risky behaviors.