The role of instrument compliance in normal force measurements of polymer melts

Schweizer et al. [J Rheol 48(6):1345-1363, 2004] showed nonlinear step shear rate data for a polystyrene melt (M w=200kg/mol, M w/M n=1.06, T=175°C). For different rheometers, cone angles, and sample sizes, the delayed normal force rise observed therein relative to a compliance-free reference N 1 (from a thermodynamically consistent reptation model) is shown to depend on rheometer compliance characterized by the instrument stiffness K A. K A can be obtained from mapping N 1 on the measured N 1,meas. or directly from mechanical contact measurement with a mismatch of 20-30%. The ranking of the stiffnesses found is K A(RMS 800)>K A(MCR 300)>K A(ARES LR2). Once K A is known, N 1,meas.-data can be corrected by solving the ill-posed Volterra equation involved in it. The correction shown for experiments with the 0.15-rad cone angle gives very good results. The characteristic decay time of the normal force after cessation of flow scales linearly with the axial response time t a calculated from K A, cone angle, and sample radius. The torque decay time is practically independent of t

A long-term analysis of the declining population of the Egyptian vulture in the Italian peninsula: Distribution, habitat preference, productivity and conservation implications

Between the beginning of the 1970s and the early 1990s the breeding population of the Egyptian vulture (Neophron percnopterus) in the Italian peninsula declined from 29 to nine breeding pairs. We analysed the main aspects of the decline of this population during the last 30 years, namely: (1) landscape structure and composition of active and extinct nesting sites; (2) changes in the land use and number of cattle within the breeding range; (3) productivity (1986-1999) of the last nine pairs breeding in the Italian peninsula. Further decline in the breeding population was probably stopped by creating artificial feeding sites and protecting the last nesting sites from direct persecution. Nearly two-thirds of the pairs laid at least one egg per year, and half of the pairs fledged at least one young per year. The mean number of fledged young was 0.99±0.66 per breeding pair, and 1.27±0.45 per successful pair. About 75% of the breeding failures occurred during incubation, and 71% were related to human activities and direct persecution. The nesting cliff occupation rate, percentage of breeding attempts that fledged at least one chick and mean number of fledged young were negatively correlated with the distance to an artificial feeding site. © 2001 Elsevier Science Ltd. All rights reserved.Peer Reviewe

Caries affected by calcium and fluoride in drinking water and family income

Abstract Water quality and socioeconomics influence caries in populations. This study broadens previous studies on how caries is associated with fluoride and calcium in drinking water and with family income by quantifying the combined effect of the three independent variables. The effects of calcium and fluoride can be described as independent effects of the two ions or, alternatively, in the form of saturation with respect to fluorite (CaF2). A general linear model describes this relationship with high significance and the model confirms the important protective effect of calcium and fluoride, independently against caries. From the model, the relative importance of fluoride and calcium to protect against caries is quantified. The relationship between caries and family income is also highly significant. It is illustrated how the linear model can be applied in planning and analyzing drinking water softening in relation to caries.</jats:p

Phase Transformation Modeling of Medium-Carbon Forging Steel

THERMEC 2006The kinetics of phase transformations in medium-carbon forging steels (MCFS) have been modeled based on CALPHAD multicomponent thermodynamics and the classical nucleation-growth theory. New treatments include the time dependency of parabolic growth rate of proeutectoid ferrite (α) , which account for the soft impingement effect by carbon enrichment in austenite (γ). And a potential transition of γ/α interface equilibrium has also been considered depending on temperatures and velocity of the moving interface. To make a realistic prediction of the onset of pearlite (P) transformation, a normal distribution of γ grain size has been assumed and successive α→P transformation kinetics in each grain size have been summated. The developed program coupled with thermodynamic solver, 'ThermoCalc', calculated the isothermal kinetics of MCFS and has been found to predict well the effect of minor difference of chemical composition / holding temperaturesPeer reviewe