Technische Strömungslehre. Band 1: Grudlagen

Ohne Zusammenfassung     

Resilient urban drainage – Options of an optimized area-management

There is a need for an integrated approach for all involved stakeholders to adapt urban infrastructures to climate change effects and to take into account uncertainties of future developments. By integrating all relevant planning disciplines, a first step towards implementation of resilient technical and social infrastructures can be achieved. With the major goal of optimizing area-management as part of water sensitive urban design, the water sector and its area requirements build the main focus of this study. After identifying local flood hazards and potential surficial retention areas, the additional usage of decentralized stormwater management facilities for flood protection is tested in selected sectors. The results of the study confirm that the combined usage of decentralized facilities for pluvial flooding is a first step to protect urban infrastructure. It shows that decentralized facilities are more flexible than centralized facilities and, thus, have a higher adaptation capacity which is needed considering the various effects of climate change.     

Cs Promoted Triglyceride Transesterification Over MgO Nanocatalysts

The influence of Cs on the structure and basicity of nanocrystalline MgO was assessed via electron microscopy, CO₂ chemisorption, XRD and XPS. Caesium incorporation via co-precipitation under supercritical conditions generates Cs₂Mg(CO₃)₂ nanocrystallites with an enhanced density and strength of surface base sites. Wet impregnation proved less effective for modifying MgO nanocrystals. A strong synergy between Cs and Mg components in the co-precipitated material dramatically enhanced the rate of tributyrin transesterification with methanol relative to undoped MgO and homogeneous Cs₂CO₃ catalysts. On-stream deactivation of Cs-doped MgO reflects heavy surface carbon deposition and loss of the high activity Cs₂Mg(CO₃)₂ phase due to limited Cs dissolution.     

Reprint of: Improved cytotoxicity testing of magnesium materials

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.     

Improved cytotoxicity testing of magnesium materials

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.     

Context processing in schizotypal personality disorder: Evidence of specificity of impairment to the schizophrenia spectrum.

Working memory abnormalities, which are particularly pronounced on context processing tasks, appear relatively specific to schizophrenia spectrum illnesses compared with other psychotic disorders. However, the specificity of context processing deficits to schizotypal personality disorder (SPD), a prototype of schizophrenia, has not been studied. The authors administered 3 versions of the modified AX Continuous Performance Test and an N-back working memory test to 63 individuals with SPD and 25 with other personality disorders, as well as 42 healthy controls. For the AX Continuous Performance Test standard and degraded versions, there was a significant Trial Type × Delay × Group interaction, as SPDs made significantly more errors reflecting poor maintenance of context and fewer errors reflecting good maintenance of context. SPDs also demonstrated poor performance on the N-back, especially at the 2-back condition. Context processing errors and N-back accuracy scores were related to disorganization symptoms. These findings, which are quite similar to those previously reported in patients with schizophrenia, suggest that context processing deficits are specific to the schizophrenia spectrum and are not a reflection of overall psychopathology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimentelle Untersuchung von Eigenschwingungsformen nichtmischbarer Fluide in einer zylindrischen,schnell rotierenden,axial angeregten Küvette

Zusammenfassung Die Eigenschwingungsformen und Eigenfrequenzen von zweiphasigen, nichtmischbaren Stoff-systemen in einer axial angeregten, schnell rotierenden zylindrischen Küvette werden in Abh?ngigkeit vom Stoffsystem und vom Geometrie- und Füllungsverh?ltnis untersucht. Die ungest?rte, zylindrische, parallel zur Erdbeschleunigung verlaufende Grenzfl?che (Trennfl?che) wird durch eine hohe Drehfrequenz erzeugt. Durch Aufpr?gen einer axialen Anregung wird die Trennfl?che gest?rt und die enstehenden Eigenformen fotografisch dokumentiert. Zur Interpretation der Me?ergebnisse werden die dimensionslosen Kennzahlen Weber-Zahl und Bond-Zahl herangezogen und auf doppelt-logarithmischem Papier in Abh?ngigkeit von der Drehfrequenz und der Fluidschichtdicke aufgetragen. Es ergibt sich ein linearer Zusammenhang. Me?verfahren und Resultate werden kritisch diskutiert. Dipl.-Ing.A. Himmel, Dr.-Ing.D. Raake, und Prof. Dr.-Ing.J. Siekmann, Lehrstuhl für Mechanik, Universit?t-GH-Essen.     

Biological scanning electrochemical microscopy and its application to live cell studies

Progress in instrumental design continues to pave the way for high-resolution, real-time electrochemical measurements with living cells.     

Fabrication and characterization of laser pulled platinum microelectrodes with controlled geometry

The development of a reproducible procedure for the fabrication of Pt disk-shaped microelectrodes with characteristic dimensions ranging from 50 nm to 1 μm in diameter was carried out using a laser pulling technique. The governing physical phenomena involved in their fabrication are discussed, and the importance of adding a critical quartz thinning step in the general procedure is demonstrated. The preparation of the microelectrodes involves sealing a platinum wire inside a quartz tubing using a pipet puller, thinning the composite material (platinum/quartz assembly), and laser pulling it to obtain two microelectrodes. The resulting microelectrodes display reproducible well-controlled geometry, which is important to downstream quantitative scanning electrochemical studies and imaging. Mechanical polishing of the microelectrode is required and remains the critical step in the fabrication of nanometer size electrodes. Following production, the microelectrodes are characterized by electron microscopy, scanning electrochemical microscopy, and cyclic voltammetry. Development of these microelectrodes is motivated by their subsequent application to electrocatalysis and their potential in theoretical study because of their well-defined geometry.