Comparative analysis of thermally modified and native spruce loaded perpendicular to the grain

The aim of this work was to analyse the material behaviour of thermally modified and native spruce by load applied perpendicularly to the grain. Therefore, thermally modified and native samples were prepared for bending tests with the load in tangential direction. The bending strength in radial direction decreases significantly with the thermal treatment. The fracture surfaces in the tangential section of the bending samples after testing were analysed with a scanning electron microscope. For native samples, the typical failure was found in the intercellular area. For thermally modified samples, failure of the entire cell wall was observed. The material behaviour is more brittle, as demonstrated by the load-deflection curves, but also by anatomical studies of the fracture surfaces.     

Positive Effect of Periodic Micropatterns on Compression Ring Friction

Internal combustion engines are increasingly regulated in regard to efficiency and environmental impact, which requires advanced optimization strategies of engine components. The contact between the top ring and the cylinder liner is critical to the efficiency of an internal combustion engine. As shown in a previous study, an amorphous carbon coating can greatly improve the friction properties of piston rings. This work expands on these results by fabricating laser-interference-induced microchannels on the coating perpendicular to the direction of movement with a mean depth of 0.97 and 3.13 μm spatial period to further optimize the tribology. Fired single-cylinder engine measurements of the microtextured rings show a significant reduction in mean piston assembly friction of 5% for operation points that are relevant for urban transportation and up to 10% for specific operation points. Subsequent multibody elastohydrodynamic simulations prove that measured friction changes result from the compression ring microtexture. In particular, the microtexture increases the hydrodynamic pressure, reduces hydrodynamic losses, and leads to 20% lowered compression ring losses for an entire combustion cycle of the investigated operation point. In the future, such tribological concepts can be deployed in internal combustion engines that are powered by sustainable hydrogen or methanol.     

On Limitations of Structured (Deterministic) DNNFs

Theory of Computing Systems - The study of representations for propositional theories has been a central subject in knowledge compilation. Many known representations of propositional knowledge...     

Non-destructive monitoring of ethylene vinyl acetate crosslinking in PV-modules by luminescence spectroscopy

This work reports on the prospects of using luminescence spectroscopy as a non-destructive method for the characterization of ethylene vinyl acetate copolymer (EVA) crosslinking in photovoltaic (PV) modules. Luminescence has the potential to be easily applied in-line for monitoring purposes, e.g. during manufacturing. We investigate the correlation of luminescence, Raman spectroscopy and differential scanning calorimetry with the EVA crosslinking. We show that all these methods, including the luminescence method, show a good correlation with the hold time during the lamination process. Furthermore, time-dependent luminescence measurements are introduced. These make use of the fact that the luminescence decreases upon the ultraviolet irradiation during the measurement. In contrast to steady-state luminescence, this facilitates measurements that are inherently less dependent on possible interfering signal artifacts, as these may occur in industrial PV modules due to other components of the PV module.     

Dispersability of multiwalled carbon nanotubes in polycarbonate-chloroform solutions

The dispersion of commercial multiwalled carbon nanotubes (MWCNTs, Nanocyl™ NC7000) in chloroform and in polycarbonate (PC)-chloroform solutions was investigated by variation of the polymer concentration, MWCNT amount and sonication time and compared with PC/MWCNT composites, which were processed by melt mixing, subsequently dissolved in chloroform and dispersed via sonication under the same conditions. The sedimentation behaviour was characterised under centrifugal forces using a LUMiSizer^® separation analyser. The space and time resolved extinction profiles as a measure of the stability of the dispersion and the particle size distribution were evaluated. Sonication up to 5 min gradually increases the amount of dispersed particles in the solutions. A significant improvement of the MWCNT dispersion in chloroform was achieved by the addition of PC indicating the mechanism of polymer chain wrapping around the MWCNTs. In dispersions of melt mixed PC/MWCNT composites the dispersion of MWCNTs is significantly enhanced already at a low sonication time of only 0.5 min due to very efficient polymer wrapping during the melt mixing process. However, the best dispersion quality does not lead to the highest electrical conductivity of thin composite films made of these PC/MWCNT dispersions.     

The Gut-Brain Axis in Inflammatory Bowel Disease—Current and Future Perspectives

The gut–brain axis is a bidirectional communication system driven by neural, hormonal, metabolic, immunological, and microbial signals. Signaling events from the gut can modulate brain function and recent evidence suggests that the gut–brain axis may play a pivotal role in linking gastrointestinal and neurological diseases. Accordingly, accumulating evidence has suggested a link between inflammatory bowel diseases (IBDs) and neurodegenerative, as well as neuroinflammatory diseases. In this context, clinical, epidemiological and experimental data have demonstrated that IBD predisposes a person to pathologies of the central nervous system (CNS). Likewise, a number of neurological disorders are associated with changes in the intestinal environment, which are indicative for disease-mediated gut–brain inter-organ communication. Although this axis was identified more than 20 years ago, the sequence of events and underlying molecular mechanisms are poorly defined. The emergence of precision medicine has uncovered the need to take into account non-intestinal symptoms in the context of IBD that could offer the opportunity to tailor therapies to individual patients. The aim of this review is to highlight recent findings supporting the clinical and biological link between the gut and brain, as well as its clinical significance for IBD as well as neurodegeneration and neuroinflammation. Finally, we focus on novel human-specific preclinical models that will help uncover disease mechanisms to better understand and modulate the function of this complex system.     

HPLC with light scatter detector and chemometric data evaluation for the analysis of cocoa butter and vegetable fats

High performance liquid chromatography equipped with an evaporative light scatter detector was carried out in order to proof the authenticity of cocoa butter. Signals of 17 characteristic triglycerides have been used to develop two chemometric models. PLS was applied for quantitation while neural nets were used for classification. The sample pool was divided in a training set of 18 and a prediction set of 14 samples. The samples included mixtures of several vegetable fats with cocoa butter. A 15 × 4 × 1 feed forward net could be trained and within the prediction set only 2 samples were not correctly assigned. A PLS model with 9 factors was applied and the mean prediction error was found to be 2.5%. The small number of samples was found to be sufficient to show the potential of this data evaluation. Results are expected to improve with a greater data pool.