Matthias Hübner

Brief Report: Adult Hippocampal Precursor Cells Shorten S‐Phase and Total Cell Cycle Length During Neuronal Differentiation

Cell cycle analyses of adult hippocampal neural stem and precursor cells in vivo are challenging, as there is no temporal or local discrimination of different precursor cell populations. All commonly used techniques to determine the cell cycle length of proliferating cells in the adult hippocampus do not allow discrimination between different cell types. Here, we introduce a novel procedure to precisely calculate cell cycle phase lengths of distinct precursor cell populations in vivo and thereby demonstrate a large heterogeneity of cell cycle kinetics within the pool of adult hippocampal precursor cells. Proliferating NeuroD1+ cells exhibited a significantly faster S‐phase progression (Ts = 10.1 ± 0.6 hours) and shorter total cell cycle length (Tc = 22.6 ± 0.1 hours) than NeuroD1− cells (Ts = 13.5 ± 0.8 hours, Tc = 27.0 ± 0.5 hours; p < .05). Dividing glial fibrillary acidic protein (GFAP+) cells also showed significantly shorter mean Ts of 9.7 ± 0.6 hours and Tc of 22.8 ± 0.5 hours compared to the rest of uncommitted NeuroD1− precursors (p < .01). Together, NeuroD1+ neuronal progenitors and mitotic GFAP+ radial glia‐like cells divide significantly faster than amplifying neural progenitor cells by accelerating their S‐phase. S‐phase duration seems to determine cell cycle length in the adult hippocampus. STEM CELLS 2012;30:2843–2847

Development of seamless woven node element structures for application in integral constructions

In order to advance consistent lightweight construction principles in automotive and mechanical engineering, support frame construction made from high-performance materials is becoming more commonplace. These consist of complexly structured nodular connection elements. The required connection elements have not yet been produced satisfactorily. The developed node element structures in this paper are produced on a shuttle weaving loom by flattening and weaving them as multi-surface woven fabrics. The development of the woven concept for the realization of node element structures is based on the fragmentation of the individual sub-elements. The goal of this research is development of a flexible technology for weaving fabrics and intended for the integral realization of woven nodular semi-finished products with complex geometries and connections, which are to be used to connect Fiber-reinforced Plastic components in support frame structures.

Wirkkettenanalyse der dieselmotorischen Verbrennung

Die innermotorischen Vorgange beim Dieselmotor (Einspritzung, Gemischbildung, Zundung, Verbrennung sowie Schadstoffbildung) werden besonders bei kleinvolumigen Pkw-Motoren stark von der Muldenwand im Kolben und von den Eigenschaften des Kraftstoffs beeinflusst. Diese Einflussgrosen wurden in einem gemeinsamen FVV-Forschungsvorhaben des Lehrstuhls fur Technische Thermodynamik der Universitat Erlangen-Nurnberg und des Lehrstuhls fur Verbrennungsmotoren der Universitat Dresden mittels optischer und konventioneller Messverfahren analysiert.

Geometrical design and forming analysis of three-dimensional woven node structures

Structural frames have been established in many technical applications and typically consist of interconnected profiles. The profiles are commonly joined with node elements. For lightweight structures, the use of composite node elements is expedient. Due to the anisotropic mechanical properties of the fibers, high demands are placed on the orientation of the fibers in the textile reinforcement structure. A continuous fiber course around the circumference and at the junctions is necessary for an excellent force transmission. A special binding and forming process was developed based on the weaving technology. It allows the production of near-net-shaped node elements with branches in any spatial direction, which meet the requirements of load-adjusted fiber orientation. The principles by which these three-dimensional (3D) node elements are converted into a suitable geometry for weaving as a net shape multilayer fabric are reported. The intersections of the branches are described mathematically and flattened to a plane. This is the basis for the weave pattern development. Forming simulations on the macro- and meso-scales complement the analyses. A macro-scale model based on the finite element method (FEM) is used to verify the general formability and the accuracy of the flattenings. Since yarns are pulled through the textile structure in the novel forming process, the required tensile forces and the pulling lengths of the individual yarns are analyzed with a meso-scale FEM model. The flattening for two different node structures is realized successfully, and the simulation proves formability. Furthermore, the necessary forming forces are determined. Finally, the developed method for flattening the 3D geometry is suitable for the design of a variety of spatial node structures and the simulation supports the design of automated forming processes.

Development of spatially branched woven node structures on the conventional weaving loom

The increasing need of consistent implementation of lightweight constructions in many technical fields makes the manufacture of near net-shaped node structure to be used in textile-reinforced composites a subject of great interest. The manufacture of the node structure is required to provide a strong node point whilst maintaining the circumference of each adjoining strut. Despite a variety of available methods to produce three-dimensional nodal fabric, the required geometry for the complex nodular connection element has not yet been fully achieved. Furthermore, the available methods have limitations. The developed woven concept in this work allows for maintaining the configuration of the node structure and dimensions of the tubes, especially at the node points. As a result, all tubes positioned at node points are fully open; this is accomplished without distorting the surrounding area once the flat woven node structure is removed from the loom and erected into three-dimensional configuration. In order to produce a three-dimensional structure on a conventional weaving machine, the structure must be flattened in an appropriate way. By using a mathematical algorithm, it is possible to graph the flattened structure precisely. The developed weaving concept and relating calculation are applied to create the weaving plan of the spatial nodal structures, which can be produced on a shuttle weaving loom. The developed concept in this paper will provide repeatable manufacturing of complex node structures by using the conventional weaving loom. The struts of node structures manufactured using this method can be woven at any angle and with spatial arrangements.

Niedrig viskose Öle – eine Herausforderung für die Auslegung der Zylinderlaufbahn

Neue Motorenole mit stark abgesenkter Viskositat bieten Potenziale zur Verringerung der innermotorischen Reibung von Verbrennungsmotoren. Diese Studie des Lehrstuhls Verbrennungsmotoren der Technischen Universitat Dresden beschreibt, wie die Zylinderlaufbahn fur den gefeuerten Motorbetrieb mit niedrig viskosen Motorenolen mithilfe der Messung der Reibkraft und der Simulation des Olverbrauchs der Kolbengruppe optimiert werden kann.

Combustion and pollutant formation in diesel engines

Especially in small-volume diesel engines for passenger cars all processes inside the combustion chamber (injection, fuel mixture generation, ignition, combustion and pollutant formation) are strongly influenced by the piston bowl wall and the characteristic features of the fuel. These parameters have been analyzed by both optical and conventional measuring techniques within the framework of a joint FVV research project of the University Erlangen-Nuremberg (Department of Engineering Thermodynamics) and the Technical University Dresden (Department of Internal Combustion Engines).