Synthesis and magnetorheological characteristics of ribbon‐like,polypyrrole‐coated carbonyl iron suspensions under oscillatory shear

One of the crucial problems of classical magnetorheological (MR) fluids is their high rate of sedimentation. This disadvantage may be substantially eliminated using core‐shell particles. The aim of this study is to prepare spherical carbonyl iron (CI) particles coated with conducing polymer polypyrrole (PPy) with ribbon‐like morphology. Scanning electron microscopy proved the formation of the ribbon‐like layer onto CI particles while Fourier transform infrared spectroscopy confirmed the chemical structure of PPy. The magnetic properties observed via vibrating sample magnetometer showed decreased magnetization saturation of core‐shell‐structured particles due to the existence of non‐magnetic surface layer. MR measurements performed under oscillatory shear flow as a function of the applied magnetic flux density, temperature, and particle concentration showed that core‐shell particle‐based MR suspension exhibits sufficient MR performance for practical applications. Moreover, the suspension stability is promoted significantly when core‐shell particles are used as a dispersed phase. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Tracing enteric viruses in the European berry fruit supply chain

In recent years, numerous foodborne outbreaks due to consumption of berry fruit contaminated by human enteric viruses have been reported. This European multinational study investigated possible contamination routes by monitoring the entire food chain for a panel of human and animal enteric viruses.     

Silicate Release from Sand-Manipulated Sediment Cores: Biogenic or Adsorbed Si?

The influence of an addition of either sand and/or spring-bloom algae on the efflux of nutrients from intact sediment cores from the Baltic Sea was studied in a flow-through experiment. The addition of sand significantly increased the efflux of silicon (Si) from sediment, but the algal addition did not. The effects on phosphorus (P) were not as clear, and fluxes of nitrogen (NH₄ and NO_2?+?3) remained relatively unaffected by the additions. The small effect of the algal addition was caused by the short time-period covered by the experiment and possibly by adsorption of released Si by the sediment. A follow-up bottle experiment showed that despite the apparently lower content of easily available Si and biogenic silica, BSi, in the sand, the sand-induced Si efflux was caused by release of Si from the sand itself, rather than by indirectly increasing the dissolution of BSi present in the sediment.     

Age differences in saccadic averaging.

Younger and older adults were asked to saccade to an orientation-defined target that was presented alone, with a more central distractor, or with a more peripheral distractor. Both age groups exhibited saccadic averaging that was more pronounced in the central distractor condition, wherein older adults had the larger effect. These results are relevant to questions of oculomotor control and also have implications for the study of age differences in other visually guided behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Algorithmen zum automatischen Zeichnen von Graphen

Zusammenfassung   Das Zeichnen von Graphen ist ein junges aufblühendes Gebiet der Informatik. Es befa?t sich mit Entwurf, Analyse, Implementierung und Evaluierung von neuen Algorithmen für ?sthetisch sch?ne Zeichnungen von Graphen. Anhand von selektierten Anwendungsbeispielen, Problemstellungen und L?sungsans?tzen wollen wir in dieses noch relativ unbekannte Gebiet einführen und gleichzeitig einen überblick über die Aktivit?ten und Ziele einer von der DFG im Rahmen des Schwerpunktprogramms „Effiziente Algorithmen für Diskrete Probleme und ihre Anwendungen“ gef?rderten Arbeitsgruppe aus Mitgliedern der Universit?ten Halle, K?ln und Passau und des Max-Planck-Instituts für Informatik in Saarbrücken geben. Eingegangen am 22.05.1996, in überarbeiteter Form am 19.02.1997     

Characterization of laser-beam surface treated cold and hot working steels

In order to increase the wear resistance of metal forming tools, four different cold and hot working steels were laser-beam surface melted and alloyed with titanium carbide and vanadium carbide. The layers were investigated concerning chemical composition, microstructure, hardness profiles, wear behaviour measured by pin-on-disk-tests with different counterbodies and plastic behaviour of the surface by a new developed repeated impact testing machine. It turned out to be more useful to take a substrate which is already quenched and tempered prior to the laser-beam surface treatment than to carry out the tool hardening heat treatment afterwards. A tempering step after the laser-beam alloying offers the advantage of carbide precipitates in the layer connected with an increase in the hardness and a reduction of residual stresses. By means of laser-beam surface alloying the wear protection of the layer can be increased while the alloying content of the substrate is reduced with respect to the core fracture toughness. The optimal alloying addition depends on the demands of the envisaged application.     

Responding to the Global Challenges: Regional Entrepreneurship within the Change Society

In this paper, some fundamental aspects of societal change processes are described, leading to proposals of how to cope with such changes through continuous learning within society. This change society is presently emerging worldwide. It is very much shaped by advanced networked information and communication technology. Correspondingly, certain trends are identified in this paper which indicate the change processes towards this new emerging society. Subsequently, different personal skills are described which are required for all members of society to cope with these trends. The paper finishes with a case study which deals with regional development through open networked business processes. The aim of the project described was to develop a joint family vacation concept in the former socialist East German state of Saxonia. Thus, it illustrates the change and learning processes across society which have taken place in many countries after the socialist era.     

Base Flip in DNA Studied by Molecular Dynamics Simulations of Differently-Oxidized Forms of Methyl-Cytosine

Distortions in the DNA sequence, such as damage or mispairs, are specifically recognized and processed by DNA repair enzymes. Many repair proteins and, in particular, glycosylases flip the target base out of the DNA helix into the enzyme’s active site. Our molecular dynamics simulations of DNA with intact and damaged (oxidized) methyl-cytosine show that the probability of being flipped is similar for damaged and intact methyl-cytosine. However, the accessibility of the different 5-methyl groups allows direct discrimination of the oxidized forms. Hydrogen-bonded patterns that vary between methyl-cytosine forms carrying a carbonyl oxygen atom are likely to be detected by the repair enzymes and may thus help target site recognition.