Influence of Initial High Shearing on Electrical and Rheological Properties and Formation of Percolating Agglomerates for MWCNT/Epoxy Suspensions

We report on shear‐induced nanotube agglomerate formation in low viscous multiwalled carbon nanotube/epoxy suspensions during steady shear rate step tests. A combined setup allows monitoring of the electrical, rheological, and optical properties of the system. High initial shearing was found to be necessary to achieve the insulator‐to‐conductor transition as well as low shear rate viscosity enhancement. Depending on the applied pre‐shear, conductivity improvement of about four orders of magnitude was observed. Different morphologies for shear‐induced agglomerates were detected before and after high shear. The critical minimal shear rate for the system was determined and a simple model using phase separation due to high shear forces is proposed.

     

"DNA traffic lights": concept of wavelength-shifting DNA probes and application in an aptasensor

Add it and see it: The concept of "DNA traffic lights" for wavelength-shifting DNA probes has a great potential in the application of biosensors, for example, in DNA aptamers. A visual color change in the DNA aptasensor fluorescence from green to red occurs after specific target binding.     

In-line monitoring of printing processes in an offset printing press by NIR spectroscopy: Correlation between the conversion and the content of extractable acrylate in UV-cured printing inks

Near-infrared (NIR) reflection spectroscopy was used for in-line monitoring of the conversion in printed layers of a UV-curable cyan printing ink at an offset printing press. Quantitative analysis of the spectra was based on the calibration of the method with chemometric approaches using reference data for the conversion obtained by FTIR/ATR spectroscopy. In this way, the conversion in ink layers with a thickness of 0.8 g m⁻² was determined with a precision of 5%. Moreover, it was shown that the specific migration of the acrylate components in the binder of the printing ink was linearly dependent on the conversion in the studied range between about 80% and 100%, which allowed an estimation of the specific migration from conversion data. The strict linear relation between both parameters was used for indirect in-line monitoring of the acrylate migration during the printing process by predicting it from the conversion data derived from the NIR spectra. For comparison, off-line measurements on random samples by HPLC were carried out. The error of the predicted migration data in comparison with the results of the analytic measurements was found to be about 0.03 mg dm⁻². The proposed indirect prediction of the migration will allow a better and more direct control of technical printing processes.     

In-line monitoring of the conversion in UV-cured printed layers by NIR spectroscopy in an offset printing press

In this study, it was demonstrated that the conversion in printed layers of UV-cured printing inks and varnishes can be determined in-line in a printing press by NIR reflection spectroscopy supported by chemometric methods. Layers were printed with a thickness of ∼1.2 g m⁻² for a printing ink and ∼2.8 g m⁻² for a printing varnish. Quantitative analysis of the spectral data was carried out with calibration models based on the partial least squares (PLS) algorithm. In-line monitoring tests were performed at a large-scale sheet-fed offset printing press in order to evaluate the predicting performance of the calibration models under process conditions. Different conversions in the layers were induced by variation of the irradiation dose. The predicting errors were 4.5% for the ink and 4.0% for the varnish. The printing speed was found to have no significant influence on the precision of the measurements.     

Periodic open-cell foams: Pressure drop measurements and modeling of an ideal tetrakaidecahedra packing

Periodic open-cell foams of ideal tetrakaidecahedron geometry were manufactured by selective electron beam melting (SEBM) and characterized with respect to the morphological parameters, namely strut diameter, window diameter and porosity. The pressure drop over these periodic foam samples of different pore size and porosity was determined experimentally. The basic form of the Ergun equation (which contains no empirical coefficients) was modified to develop a new correlation for the prediction of the pressure drop in periodic open-cell foams of ideal tetrakaidecahedron geometry. The correlation was successfully validated by the experimental results of the pressure drop measured for the periodic open-cell foam samples. With the new correlation it is possible to predict the pressure drop in periodic open-cell foams by using only two geometrical parameters, namely the open porosity and the window diameter.The applicability of the new correlation for a large range of porosities was examined by comparing the experimental and simulated friction factors for the porous media with both high (foam structure) and low porosities (packed beds) for a large range of the Reynolds number. It was demonstrated that the correlation can successfully predict the pressure drop of foam structures as well as packed beds.     

Relative validation of a food frequency questionnaire for national health and nutrition monitoring

Background  

Validation of a food frequency questionnaire (FFQ) is important as incorrect information may lead to biased associations. Therefore the relative validity of an FFQ developed for use in the German Health Examination Survey for Adults 2008-2011 (DEGS) was examined.     

Spatial variation of nitrogen mineralization as a guide for variable application of nitrogen fertilizer to cereal crops

The site specific management of variable rate nitrogen (N) fertiliser application to crops is a cost-effective system that optimises outputs and reduces environmental impact. However, its implementation requires information on the spatial variability of soil and crop variables and, especially, of the N supply from the soil, measured as the available N and the N mineralized from organic matter. The objective of this study was to obtain the spatial structure of the variation of net N mineralization, within the field scale in a cereal cropping system, in order to improve site specific N management. A nested sampling survey was conducted in the field using scales of variation at 1.5, 4.5, 13.5, 40.5 and 121.5 m, arranged in hierarchical order with n = 96 samples. Samples were collected in autumn and spring and N mineralization measured by aerobic incubation. The components of variance of the N mineralized were calculated using residual maximum likelihood and used to produce an approach to the variogram. The within-field spatial variation was almost all (92–93%) encompassed by the scales of variation measured, all occurring within 40.5 m in both seasons. However, there was a significant amount of fine scale variation at 1.5 m in autumn and 4.5 m in spring. These results will guide future spatial sampling of the N supply, and soil monitoring in general.     

Development and Standardization of Testing Equipment and Methods for Spacer Fabrics

Applied Composite Materials - Spacer fabrics are three-dimensional textile structures consisting of two textile cover surfaces and a spacer thread. Up to now, spacer fabrics have been tested...     

The Soluble Fms-like Tyrosine Kinase-1 Contributes to Structural and Functional Changes in Endothelial Cells in Chronic Kidney Disease

Endothelial cells are a critical target of the soluble Fms-like tyrosine kinase-1 (sFlt-1), a soluble factor increased in different diseases with varying degrees of renal impairment and endothelial dysfunction, including chronic kidney disease (CKD). Although the mechanisms underlying endothelial dysfunction are multifactorial and complex, herein, we investigated the damaging effects of sFlt-1 on structural and functional changes in endothelial cells. Our results evidenced that sera from patients with CKD stiffen the endothelial cell cortex in vitro, an effect correlated with sFlt-1 levels and prevented by sFlt-1 neutralization. Besides, we could show that recombinant sFlt-1 leads to endothelial stiffening in vitro and in vivo. This was accompanied by cytoskeleton reorganization and changes in the endothelial barrier function, as observed by increased actin polymerization and endothelial cell permeability, respectively. These results depended on the activation of the p38 MAPK and were blocked by the specific inhibitor SB203580. However, sFlt-1 only minimally affected the expression of stiffness-sensitive genes. These findings bring new insight into the mechanism of action of sFlt-1 and its biological effects that cannot be exclusively ascribed to the regulation of angiogenesis.