Distribution of ions around a charged sphere

Using a new method of calculating the effects of excluded volume, the authors evaluate the distribution of counterions around a charged sphere in thermal equilibrium. In regions of high concentration a saturation of the ion density is found, which is absent in the more conventional Gouy-Chapman model. At the same time the saturation effect of the potential (a property of the Gouy-Chapman model) is removed, giving significant corrections to the values of the potential and concentration at the surface of the sphere

Transport coefficients for rigid spherically symmetric polymers or aggregates

In this paper we investigate the transport properties for rigid spherically symmetric macromolecules, having a segment density distribution falling off as r- lambda . We calculate the rotational and translational diffusion coefficient for a spherically symmetric polymer and the shear viscosity for a dilute suspension of these molecules, starting from a continuum description based on the Debye-Brinkman equation. Instead of numerical methods for solving equations we use perturbative methods, especially methods from boundary-layer analysis. The calculations provide simple analytical formulae for the shear viscosity eta , and the translational and rotational diffusion coefficients DT and DR. The results can also be applied to suspensions of other porous objects, such as aggregates of colloidal particles in which D=3- lambda is called the fractal dimension of the aggregate

Parallel efficiency of a boundary integral equation method for nonlinear water waves

We describe the application of domain decomposition on a boundary integral method for the study of nonlinear surface waves on water in a test case for which the domain decomposition approach is an important tool to reduce the computational effort. An important aspect is the determination of the optimum number of domains for a given parallel architecture. Previous work on hetero- geneous clusters of workstations is extended to (dedicated) parallel platforms. For these systems a better indication of the parallel performance of the domain decomposition method is obtained because of the absence of varying speed of the processing elements

Effects of excluded volume on the electrolyte distribution around a charged sphere

A recently developed method is used to calculate the main effects of excluded volume on the distribution of ions around a charged central sphere in thermal equilibrium. The authors find significant corrections to the results of the conventional Gouy-Chapman theory when the electrostatic energy due to the charge of the sphere is large compared with the thermal energy. The concentration shows a distinct saturation effect, while at the surface of the sphere the known saturation of the potential is lifted. Furthermore, the effect of excluded volume is found to be strongly dominated by the excluded volume of ions with a charge opposite to the charge of the sphere

Norms for creativity and implementation in healthcare teams: testing the group innovation inventory

Abstract OBJECTIVE: To test to what extent the four-factor structure of the group innovation inventory (GII) is confirmed for improvement teams participating in a quality improvement collaborative. DESIGN: Quasi-experimental design with baseline and end-measurement after intervention. SETTING: This study included quality improvement teams participating in the Care for Better improvement programme for home care, care for the handicapped and the elderly in the Netherlands between 2006 and 2008. PARTICIPANTS: As part of a larger evaluation study, 261 written questionnaires from team members were collected at baseline (pre-project sample) and 129 questionnaires at end-measurement (post-project sample). MAIN OUTCOME MEASURE: Group innovation inventory. RESULTS: Confirmatory factor analyses revealed the expected four-factor structure and good fit indices. The subscales 'group functioning' and 'speed of action' showed acceptable Cronbach's alphas and high inter-item correlations. The subscales 'support for risk taking' and 'tolerance of mistakes' showed insufficient reliability and validity. CONCLUSIONS: The group functioning and speed of action subscales of the GII showed acceptable psychometric properties and are applicable to quality improvement teams in health care. In order to understand how social expectations within teams working in health care organizations exert influence over attitudes and behaviours thought to stimulate creativity, further conceptualization of the norms for enhancing creativity within health care is needed

Metal Enhanced Fluorescence With Gold Nanoparticles

A novel hybrid nanocomposite of Au nanoparticle-modified silicon nanowire was developed for surface enhanced fluorescence applications. The designed nanocomposite contained a silicon nanowire, gold nanoparticles and a silica layer doped with dye molecules. The hybrid nanomaterial was characterized using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), fluorescence measurements, Fourier transform infrared (FT-IR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDS). The results showed that the gold nanoparticles were uniformly adhered on the silicon nanowires and covered by a thin silica layer. The nanostructure exhibited strong capacity for surface enhanced fluorescence. Different enhancement factors were obtained by changing synthetic conditions. The second goal of the project was to determine if the shape of gold nanoparticles affects the extent of its fluorescence enhancement under constant external factors. Two shapes of gold nanoparticles were synthesized and characterized by SEM, STEM, zeta potential and absorbance measurements. Then they were coated with fluorescent dye-doped silica and the fluorescence intensity was measured and compared to the pure fluorescent dye. Gold nanorods enhanced fluorescence more than gold nanostars and that the fluorescent dye Alexafluor 700 showed a greater fluorescence intensity change in the presence of nanoparticles than methylene blue