Investigation of Capillary Suspension Drying Behavior with Simultaneous Stress and Weight Measurements

Coatings and ceramic green bodies usually contain polymeric additives to prevent cracking caused by drying induced stresses, which requires subsequent removal steps. A new coating formulation using capillary suspensions was found to reduce cracking, while being absent of polymeric additives. This dissertation investigates the drying behavior of capillary suspensions. The cantilever deflection method, commonly used for investigation of drying stresses, is significantly improved. The simultaneous stress and weight measurement technique of the same coating in a temperature and humidity controlled chamber developed in this dissertation is unprecedented. Enhanced by visual observation and coating profiling, we propose liquid flow considerations to explain the observed prolonged constant drying period. Stress measurements performed at different drying conditions and suspension formulations show a decrease in peak stress by up to 40\% for the capillary suspension over the regular suspension without polymeric additives. A complex interplay between yield stress, capillary suspension formulation, and humidity that is capable of reducing the peak stress of a regular suspension is revealed. The role of water, an integral part of most capillary suspensions, was further investigated. We find that capillary suspensions can be formed from partially miscible liquid-liquid systems at low added fluid concentrations ($\mathrm{\lesssim \, }$4 vol%), just outside the miscibility gap, by adding particles followed by mixing. Even when stored in humid conditions, capillary suspension formation is observed. These findings have an effect on undesired flocculation of formulations when stored in a humid environment, but also impact stress reduction during drying

Mechanistic understanding and improvement of photochemical proton reduction catalyzed by iron carbonyl complexes for sustainable hydrogen production

Mechanistic investigation of three homogeneous, photochemical proton reduction systems that comprise Ir or Cu based photosensitizers and iron carbonyl catalysts to produce hydrogen. Operando IR spectroscopy coupled with gas volumetry was applied supported by other spectroscopic techniques. The rate determining steps, deactivation mechanisms and catalytic key species were determined, with the latter being a self-assembling [FeFe]-hydrogenase mimic in case phosphines are present as co-catalysts in the reaction mixture. These results lead to a better understanding and improvement of the systems

Scan Correlation -- Revealing distributed scan campaigns

Public networks are exposed to port scans from the Internet. Attackers search for vulnerable services they can exploit. In large scan campaigns, attackers often utilize different machines to perform distributed scans, which impedes their detection and might also camouflage the actual goal of the scanning campaign. In this paper, we present a correlation algorithm to detect scans, identify potential relations among them, and reassemble them to larger campaigns. We evaluate our approach on real-world Internet traffic and our results indicate that it can summarize and characterize standalone and distributed scan campaigns based on their tools and intention.Comment: Accepted for publication at DISSECT '2

Spatio-temporal research data infrastructure in the context of autonomous driving

In this paper, we present an implementation of a research data management system that features structured data storage for spatio-temporal experimental data (environmental perception and navigation in the framework of autonomous driving), including metadata management and interfaces for visualization and parallel processing. The demands of the research environment, the design of the system, the organization of the data storage, and computational hardware as well as structures and processes related to data collection, preparation, annotation, and storage are described in detail. We provide examples for the handling of datasets, explaining the required data preparation steps for data storage as well as benefits when using the data in the context of scientific tasks. © 2020 by the authors

To eat or not to eat—relationship of lichen herbivory by snails with secondary compounds and field frequency of lichens

Aims The biochemical defense of lichens against herbivores and its relationship to lichen frequency are poorly understood. Therefore, we tested whether chemical compounds in lichens act as feeding defense or rather as stimulus for snail herbivory among lichens and whether experimental feeding by snails is related to lichen frequency in the field. Methods In a no-choice feeding experiment, we fed 24 lichen species to snails of two taxa from the Clausilidae and Enidae families and compared untreated lichens and lichens with compounds removed by acetone rinsing. Then, we related experimental lichen consumption with the frequency of lichen species among 158 forest plots in the field (Schwäbische Alb, Germany), where we had also sampled snail and lichen species. Important findings In five lichen species, snails preferred treated samples over untreated controls, indicating chemical feeding defense, and vice versa in two species, indicating chemical feeding stimulus. Interestingly, compared with less frequent lichen species, snails consumed more of untreated and less of treated samples of more frequent lichen species. Removing one outlier species resulted in the loss of a significant positive relationship when untreated samples were analyzed separately. However, the interaction between treatment and lichen frequency remained significant when excluding single species or including snail genus instead of taxa, indicating that our results were robust and that lumping the species to two taxa was justified. Our results imply lichen-feeding snails to prefer frequent lichens and avoid less frequent ones because of secondary compound recognition. This supports the idea that consumers adapt to the most abundant food sourc

IS AVERAGE SPEED CONTROL SENSITIVE ENOUGH TO ENSURE NONACCELERATED RUNNING IN THE ANALYSIS OF RUNNING MECHANICS?

The purpose of this study was to investigate whether average speed control by means of photocells is sufficient to guarantee the absence of center of mass velocity changes (CoMVC) and possible effects of such changes on running mechanics. A standard 3D inverse dynamics model was used to calculate kinematics and kinetics of 19 subjects running at 3,5m/s over a 25m track. CoMVC were controlled by calculating the ratio of propulsive to braking impulse (RPBI) of the GRF. Higher braking forces were achieved by increased negative work of the knee extensors while greater propulsive forces were mainly the effect of increased positive work of the plantar flexors. Differences in impact force were related to CoMVC. Implementation of RPBI control is recommended especially when sagittal plane mechanics and impact forces are to be investigated