Search

In recent years Intrinsically Conducting Polymers (ICPs), such as polyaniline and polypyrrole, have become key materials in the search for high-performance coatings for the protection of metals from corrosion. In this work, by means of dedicated model samples, we have found that disconnected ICP particles in composite coatings applied on iron and zinc are capable of inhibiting the oxygen reduction in their vicinity, establishing a region where no or only very slow delamination occurs, i.e. a "protection zone" is created, which relies on the ICP's high potential and its redox activity. The efficiency of this novel protection mechanism may depend on the ICP type, thickness or counter-anion, and is here analyzed by means of Kelvin probe based investigations. [ABSTRACT FROM AUTHOR]

The accuracy of regional or mesoscale carbon budgeting by means of inverse modelling depends strongly on the ability of the atmospheric model to capture relevant atmospheric transport processes. In order to analyze the influence of terrain‐induced flow dynamics and intense local anthropogenic emissions, we present high‐resolution (forward) simulations of spatio‐temporal CO2 variations using a recent biosphere–atmosphere model. The selected region is characterized by complex terrain and both rural and densely populated areas. The results indicate that, in situations with weak synoptic forcing, the nocturnal near‐surface CO2 distribution is strongly affected by terrain‐induced turbulent kinetic energy (TKE) above mountain ridges and by local convergent downslope winds. By increasing the grid spacing from ≈ 1 to ≈ 3 km, we show that, due to the smoothed model topography, the atmospheric flow causing the CO2 heterogeneity cannot be resolved any more. Finally, we quantify the influence of intense anthropogenic CO2 sources on atmospheric CO2 concentrations. A significant anthropogenic signal can be identified around and downstream of industrial and urban areas, especially in the morning but also within a well‐mixed planetary boundary layer in the daytime. The results provide valuable information for including non‐background CO2 observations in mesoscale inverse modelling studies using coarser resolutions than in this study. [ABSTRACT FROM AUTHOR]

The scanning Kelvin probe (SKP) is a versatile method for the measurement of the Volta potential difference between a sample and the SKP-tip (ΔψsampleSKP-tip). Based on suitable calibration, this technique is highly suited for the application in corrosion science due to its ability to serve as a very sensitive noncontact and nondestructive method for determining the electrode potential, even at buried interfaces beneath coatings or on surfaces covered by ultrathin electrolyte layers, which are not accessible by standard reference electrodes. However, the potential of the reference (i.e., the SKP-tip) will be influenced by variations of the surrounding atmosphere, resulting in errors of the electrode potential referred to the sample. The objective of this work is to provide a stable SKP-tip which can be used in different or changing atmosphere, e.g., within a wide range of relative humidity (approximately 0-99%-rh) or varying O2 partial pressure, without showing a change of its potential (note that the work functions measured in non-UHV atmospheres are electrochemical in nature [Hausbrand et al. J. Electrochem. Soc. 2008, 155 (7), C369-C379], and hence in the following we will refer to the potential of the SKP-tip instead of its work function). In that regard, the SKP-tip is in a first approach modified with self-assembled monolayers (SAMs) in order to create a hydrophobic barrier between the metallic surface and the surrounding atmosphere. The changes in potential upon varying relative humidity (ΔErh) of different bare metallic substrates are quantified, and it is shown that these potential differences cannot be minimized by SAMs. On the contrary, the ΔErh increases for every examined material system modified with SAMs. The major explanation for this observation is the dipole layer at the interface metal|SAM, causing an interfacial adsorption of water molecules even in a preferred orientation of their dipole moments, which leads to a changed work function and consequently to the correlated electrode potential. However, thin paraffin coatings were found to lead to a strongly reduced ΔErh, finally validated with novel robust Ag/Ag+ reference electrodes. It is also shown that nickel as SKP-tip material is seemingly more stable in varying atmospheric conditions compared to widely used Ni/Cr, stainless steel, or gold as SKP-tip material. [ABSTRACT FROM AUTHOR]

A new coupled high-resolution biosphere-atmosphere model (TerrSysMP-CO2) is applied to simulate mesoscale and diurnal variations of atmospheric CO2 mixing ratios. The model is characterized by process-based parametrization calculating atmospheric dynamics and biogenic processes considering the prognostically varying CO2 content at the surface. An advanced parametrization of soil respiration is used distinguishing between heterotrophic and autotrophic respiration and explicitly considering the effect of varying soil moisture. In addition to biogenic CO2 fluxes, high-resolution anthropogenic emissions are included in the simulations. The model performance is verified with eddy-covariance fluxes and meteorological and CO2 concentration measurements at various heights of a tower. It is found that a correct representation of turbulent mixing is most critical for a precise prediction of near-surface CO2 mixing ratios and respective vertical gradients. High-resolution simulations were performed for a region with complex terrain, heterogeneous land use and densely populated areas. The relative influence of diverse land use, orography as well as of synoptic and mesoscale transport on the spatio-temporal CO2 distribution is analyzed. The results indicate that, in regions with hilly terrain at night and in the morning, the CO2 patterns are strongly influenced by terrain-induced local circulations. Moreover, in densely populated regions, fossil fuel emissions are an important source of atmospheric CO2. Finally, the simulated canopy fluxes and atmospheric conditions, calculated using two different crop physiological parameter sets, are compared. [ABSTRACT FROM AUTHOR]

This study examines a fast-propagating squall line over Western and Central Europe. A high-resolution regional weather prediction model is used to analyze the three-dimensional wind field and the corresponding air mass transport induced by the mesoscale convective system. The squall line can be divided into a bow-shaped strong part with a continuous line of heavy convective precipitation, and a weaker part exhibiting several isolated multi-cell storms. In the strong part, a deep and intense rear inflow jet occurs with relative wind speeds of 12-18 m s−1. This part is also characterized by moderate to strong wind shear, in contrast to the weaker part of the squall line where a shallow cold pool surges under the potentially unstable presquall air. To investigate the air mass transport along the squall line, in the model simulations passive fluid tracers are initialized in several vertical layers with different thermodynamic conditions. At the strong part of the squall line a very efficient vertical tracer transport occurs. Potentially warm low-level air is lifted from the lowermost 2 km to the upper troposphere where an organized horizontal outflow is observed. The potentially coldest presquall air descends just in front of the updraught region and partly penetrates the convective precipitation area. In the weaker part of the squall line, the potential instability is not significantly reduced because the vertical air mass transport is less effective there. Additionally, passive tracers are used to analyze the composition of the cold pool which turns out to be a very heterogeneous mixture of descending post-frontal cold air and presquall air originating at different heights. [ABSTRACT FROM AUTHOR]

This chapter describes the case management process-a process for assisting individuals and families with multiple service needs-and its use in various fields of practice including mental health, human immunodeficiency virus and acquired immune deficiency syndrome (HIV/AIDS), and services for older adults. It addresses the role of the case manager as the person responsible for ensuring the timely and adequate delivery of suitable community-based services. The integration of formal services with informal care by family and friends as an intervention strategy is also discussed. [ABSTRACT FROM AUTHOR]