Microfluidic arrays for bioimprint of cancer cells

We report the development and characterization of a microfluidics-based bioimprint process using high-density microchannel arrays for cell-culture and polymer delivery. The tubeless PDMS arrays consist of multiple independent microchannels and allow for parallelized bioimprint via automated dispensing and passive pumping. Using the microchannels, a 400 nm thin test pattern was replicated into a methacrylate biopolymer to demonstrate process applicability. Bioimprints of cobalt chloride stimulated Ishikawa endometrial cancer cells exhibiting exocytosis-like pore structures were compared with controls using AFM to exemplify a process application. The devices can be used for high-throughput cell assays, cell developmental studies and the formation of phenotype-specific biomimetic scaffolds.     

Microstructural Evolution of Silica on Single Crystal Silicon Carbide. Part II: Influence of Impurities and Defects

Passive oxidation of single crystal silicon carbide (6H–SiC) resulted in the formation of a vitreous silica layer which crystallized gradually at temperatures near 1300°–1400°C. During this process, statistically distributed devitrification centers appeared and disk-like aligned crystal plates (radialites) formed. The crystallization process did not necessarily start at structural defects although these often act as areas of preferred nucleation. A second structural transition from disk-like radialites to small crystalline spheres (globulites) was not connected to structural defects but a consequence of the presence of impurities. Alkaline and earth-alkaline elements are common contaminations within the atmospheres of typical furnaces fitted with alumina tubes. Globulite formation was a process of recrystallization catalyzed by an impurity-related melt formed on top of the devitrified areas. Crystallization caused exsolution of reaction gas and local impurity enrichments as the solubility for these phases is much higher in the devitrifying vitreous silica matrix. Both clean and impurity-loaded oxidation produced specific morphologies of scales and interfaces.     

Ontological approach for the semantic recovery of traceability links between software artefacts

Traceability links provide support for software engineers in understanding relations and dependencies among software artefacts created during the software development process. The authors focus on re-establishing traceability links between existing source code and documentation to support software maintenance. They present a novel approach that addresses this issue by creating formal ontological representations for both documentation and source code artefacts. Their approach recovers traceability links at the semantic level, utilising structural and semantic information found in various software artefacts. These linked ontologies are supported by ontology reasoners to allow the inference of implicit relations among these software artefacts.     

Efficient shape optimization for certain and uncertain aerodynamic design

In this paper, we present novel developments in aerodynamic shape optimization based on shape calculus as well as the proper treatment of aleatoric uncertainties in the field of aerodynamic design.     

Entwicklung einer kontinuierlichen Mikrowellen‐Vakuumtrocknungsanlage mit hexagonalem Verfahrensraum

A continuous microwave vacuum drying processor with a hexagonal cross‐section of the cavity was constructed. Due to the geometry of the cavity and the continuous movement of the product, homogeneous microwave power absorption of the product can be favored. By the expansion and simultaneous dehydration of non‐expanded, starch‐based extrudates, the applicability of the constructed processor could be shown.     

Polystyrol und styrolcopolymere

Polystyrene is with a present day sales volume of 8,5 million tons a year one of the most important thermoplastics worldwide. Its unique property profile makes polystyrene an ideal material for housings, refrigerator inliners and demanding packaging applications, when transparency and/or surface quality as well as stiffness are important. Its economic success is due to its favourable price/performance ratio and also not least to its excellent processability as an amorphous material. In this contribution the versatility and potential for innovation of polystyrene and its copolymers are discussed. Using standard and impact modified polystyrene, it is shown how the maturity of the polymerisation process, the broad spectrum of product modifications as well as processing know how of this class of materials have helped to promote the breakthrough of this product to an acknowledged plastic material. Modern polystyrene variations are increasingly meeting the special property requirements of other materials, like for example high heat resistant PPE/PS-I blends, weather resistant ASA and AES plastics, tough and crystal clear star polymers or hydrogenated and unhydrogenated elastomers. A special feature of polystyrene is that it is one of the few monomers which can be polymerised using all the known methods for vinyl monomers to produce high molecular weight products. Thus the newest polymerisation techniques using metallocene catalysed and anionic polymerisation methods lead to products with the property profile of engineering plastics. Polystyrene will continue to grow in the future and thus increase in importance, especially while it can be easily depolymerised and in the form of styrene monomer recycled.     

Optimal control for unstructured nonlinear differential-algebraic equations of arbitrary index

We study optimal control problems for general unstructured nonlinear differential-algebraic equations of arbitrary index. In particular, we derive necessary conditions in the case of linear-quadratic control problems and extend them to the general nonlinear case. We also present a Pontryagin maximum principle for general unstructured nonlinear DAEs in the case of restricted controls. Moreover, we discuss the numerical solution of the resulting two-point boundary value problems and present a numerical example. This research was supported through the Research-in-Pairs Program at Mathematisches Forschungsinstitut Oberwolfach. V. Mehrmann’s research was supported by Deutsche Forschungsgemeinschaft, through Matheon, the DFG Research Center “Mathematics for Key Technologies” in Berlin.     

Rankings und „Wo studieren die Besten?“

Ein Ranking beruht meist auf einer Abbildung einer endlichen Menge von (hochkomplexen) Strukturen auf die reelle Achse.