Bochum, Germany
Bochum, Germany

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Schumacher J.,IBBP | Simon A.,French National Institute for Agricultural Research | Cohrs K.C.,IBBP | Traeger S.,IBBP | And 6 more authors.
Molecular Plant-Microbe Interactions | Year: 2015

Botrytis cinerea, the gray mold fungus, is an important plant pathogen. Field populations are characterized by variability with regard to morphology, the mode of reproduction (conidiation or sclerotia formation), the spectrum of secondary metabolites (SM), and virulence. Natural variation in bcvel1 encoding the ortholog of Aspergillus nidulans VeA, a member of the VELVET complex, was previously shown to affect lightdependent differentiation, the formation of oxalic acid (OA), and virulence. To gain broader insight into the B. cinerea VELVET complex, an ortholog of A. nidulans LaeA, BcLAE1, a putative interaction partner of BcVEL1, was studied. BcVEL1 but not its truncated versions interacts with BcLAE1 and BcVEL2 (VelB ortholog). In accordance with the expected common as well as specific functions of BcVEL1 and BcLAE1, the deletions of both genes result in similar though not identical phenotypes. Both mutants lost the ability to produce OA, to colonize the host tissue, and to form sclerotia. However, mutants differ with regard to aerial hyphae and conidia formation. Genome-wide expression analyses revealed that BcVEL1 and BcLAE1 have common and distinct target genes. Some of the genes that are underexpressed in both mutants, e.g., those encoding SM-related enzymes, proteases, and carbohydrate-active enzymes, may account for their reduced virulence. © 2015 The American Phytopathological Society.

Gomes J.M.,University of Porto | Papaderos P.,University of Porto | Vilchez J.M.,Institute Astrofisica Of Andalucia Csic | Kehrig C.,Institute Astrofisica Of Andalucia Csic | And 24 more authors.
Astronomy and Astrophysics | Year: 2016

Based on a combined analysis of SDSS imaging and CALIFA integral field spectroscopy data, we report on the detection of faint (24 <μr mag/□″< 26) star-forming spiral-arm-like features in the periphery of three nearby early-type galaxies (ETGs). These features are of considerable interest because they document the still ongoing inside-out growth of some local ETGs and may add valuable observational insight into the origin and evolution of spiral structure in triaxial stellar systems. A characteristic property of the nebular component in the studied ETGs, classified i+, is a two-radial-zone structure, with the inner zone that displays faint (EW(Hα) ≃ 1 Å) low-ionization nuclear emission-line region (LINER) properties, and the outer one (3 Å

Trovo M.,Ruhr University Bochum | Trovo M.,Universitatsstr 150 | Trovo M.,Federal University of Rio de Janeiro | Stutzel T.,Ruhr University Bochum
Feddes Repertorium | Year: 2012

Although diaspores and the dispersal mechanisms are keystones to tackle the evolution of Eriocaulaceae, most of the useful information is lost in taxonomic and morphological papers in a more or less unstructured way. This survey intends thus to summarize and organize the relevant information available and point new insights. Observations and photographs were made in the field, together with complementary experiments. The seeds are the smallest dispersal units and are released by the shrinkage of the pericarp. They are rarely dispersed alone but normally within the fruits or parts of it. The fruits can be released from the capitula by different systems: shrinkage of the dry receptacle and consequent release of all flowers and fruits or only the fruits, anemoballistic mechanism, catapult mechanism, and elevator mechanism. The capitula, with scapes or not, may serve as dispersal units as well. The different dispersal mechanisms seem to be deeply related to the geographic distribution of Eriocaulaceae species and may serve also to taxonomic and phylogenetic purposes. From the current stand point we encourage future studies in this area, explicitly associated with molecular studies on the population level. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zenger C.T.,Universitatsstr 150 | Zenger C.T.,Ruhr University Bochum | Zimmer J.,Ruhr University Bochum | Pietersz M.,Universitatsstr 150 | And 4 more authors.
WiSec 2016 - Proceedings of the 9th ACM Conference on Security and Privacy in Wireless and Mobile Networks | Year: 2016

In this work, we constructively combine adaptive wormholes with channel-reciprocity based key establishment (CRKE), which has been proposed as a lightweight security solution for IoT devices and might be even more important for the 5G Tactile Internet and its embedded low-end devices. We present a new secret key generation protocol where two parties compute shared cryptographic keys under narrow-band multi-path fading models over a delayed digital channel. The proposed approach furthermore enables distance-bounding the key establishment process via the coherence time dependencies of the wireless channel. Our scheme is thoroughly evaluated both theoretically and practically. For the latter, we used a testbed based on the IEEE 802.15.4 standard and performed extensive experiments in a real-world manufacturing environment. Additionally, we demonstrate adaptive wormhole attacks (AWOAs) and their consequences on several physical-layer security schemes. Furthermore, we proposed a countermeasure that minimizes the risk of AWOAs. © 2016 ACM.

Tymoczko J.,Universitatsstr 150 | Tymoczko J.,Ruhr University Bochum | Schuhmann W.,Universitatsstr 150 | Schuhmann W.,Ruhr University Bochum | Bandarenka A.S.,Universitatsstr 150
Electrochemistry Communications | Year: 2013

Using one of the most understood and well-characterized electrochemical systems, Pt(111) surface in contact with H2SO4, we provide evidences that specific adsorption, 2D phase transitions in the adsorbate layers and, in general, structural effects in the double layer are largely responsible for the so-called frequency dispersion of the double layer. The results also show promise that parameters of the constant phase element (which is used in impedance spectroscopy to account for the frequency dispersion) obtained as a function of the electrode potential can be reasonably used to detect 2D phase transitions at the electrode/electrolyte interfaces. This would provide a better insight into the interface, increasing the impact of measurements made by electrochemical impedance spectroscopy. © 2012 Elsevier B.V. All rights reserved. All rights reserved.

Tymoczko J.,Universitatsstr 150 | Tymoczko J.,Ruhr University Bochum | Schuhmann W.,Universitatsstr 150 | Schuhmann W.,Ruhr University Bochum | Bandarenka A.S.,Universitatsstr 150
Physical Chemistry Chemical Physics | Year: 2013

An electrochemical cell for the controllable modification and comprehensive electrochemical characterisation of model electro-catalytic surfaces has been developed. In-depth electrochemical characterisation of stationary electrodes as well as rotating disc electrode (RDE) measurements in hanging meniscus configuration becomes possible. Additionally, the temperature of the electrodes in contact with electrolytes can be accurately controlled between room temperature and 70-80 °C. It is of particular importance for model electro-catalytic studies that in one experimental set-up (i) electrochemical metal and non-metal deposition to adjust the amount of the foreign atoms at the surface, (ii) controllable thermal treatment to vary the position of these atoms at the surface and subsurface regions, and (iii) state-of-the-art techniques common in electrocatalysis to characterise the resulting samples are possible. The deposition and annealing procedures under various atmospheres allow accurate control over the position of the foreign atoms at the electrode surface as overlayers, surface alloys and sub-surface (or near-surface) alloys, where the solute element is preferentially located in the second atomic layer of the host metal. The cell enables us to perform all operations without exposing the samples to the laboratory atmosphere at any of the experimental stages. To demonstrate the performance and advantages of the developed cell, we use model experiments with Pt(111) single crystal electrodes and Pt(111) surfaces modified with (sub)monolayer amounts of copper. © the Owner Societies 2013.

Zenger C.T.,Universitatsstr 150 | Zenger C.T.,Ruhr University Bochum | Pietersz M.,Universitatsstr 150 | Pietersz M.,Ruhr University Bochum | And 4 more authors.
Computer Networks | Year: 2016

Authenticated key establishment is a central requirement for securing IoT devices. For efficiency and management reasons, it might be desirable to avoid public-key-based solutions that are ubiquitous in traditional Internet settings but have many drawbacks for resource-constrained (RC) nodes. We introduce a novel Vicinity-based Pairing (VP) mechanism that allows authenticating arbitrary 'unloaded' RC-nodes by delegating trust from already authenticated and secured, we call it 'loaded', RC-nodes. For authenticating RC-nodes, VP exploits the correlation between channel profiles from devices that are in close physical proximity. In our setting, only devices that are within a few centimetres from the 'loaded' RC-nodes are authenticated after a user initiates such a process. Subsequently, the embedded end device can extract an unique shared symmetric key with another device such as a SCADA gateway, again by exploiting channel parameters. Based on extensive experiments, we propose new techniques for extracting time-varying randomness from channel parameters for use in VP. We describe the first MITM-resistant device pairing protocol purely based on a single wireless interface with an extensive adversarial model and protocol analysis. We show that existing wireless devices can be retro-fitted with the VP protocol via software updates, i.e. without changes to the hardware. Implementation results of our embedded prototype demonstrates that the approach has the potential to dramatically reduce the cost and efforts of securing low-resource devices that are common in the IoT. © 2016 Elsevier B.V.

Fourmond V.,Aix - Marseille University | Stapf S.,Universitatsstr 150 | Stapf S.,Ruhr University Bochum | Li H.,Universitatsstr 150 | And 7 more authors.
Journal of the American Chemical Society | Year: 2015

The use of synthetic inorganic complexes as supported catalysts is a key route in energy production and in industrial synthesis. However, their intrinsic oxygen sensitivity is sometimes an issue. Some of us have recently demonstrated that hydrogenases, the fragile but very efficient biological catalysts of H2 oxidation, can be protected from O2 damage upon integration into a film of a specifically designed redox polymer. Catalytic oxidation of H2 produces electrons which reduce oxygen near the film/solution interface, thus providing a self-activated protection from oxygen [Plumeré et al., Nat Chem. 2014, 6, 822-827]. Here, we rationalize this protection mechanism by examining the time-dependent distribution of species in the hydrogenase/polymer film, using measured or estimated values of all relevant parameters and the numerical and analytical solutions of a realistic reaction-diffusion scheme. Our investigation sets the stage for optimizing the design of hydrogenase-polymer films, and for expanding this strategy to other fragile catalysts. © 2015 American Chemical Society.

Bandarenka A.S.,Universitatsstr 150 | Hansen H.A.,Technical University of Denmark | Rossmeisl J.,Technical University of Denmark | Stephens I.E.L.,Technical University of Denmark
Physical Chemistry Chemical Physics | Year: 2014

The unexpectedly high measured activity of Pt[n(111) × (111)] and Pt[n(111) × (100)] stepped single crystal surfaces towards the oxygen reduction reaction (ORR) is explained utilizing the hydroxyl binding energy as the activity descriptor. Using this descriptor (estimated using experimental data obtained by different groups), a well-defined Sabatier-type volcano is observed for the activities measured for the Pt[n(111) × (111)] and Pt[n(111) × (100)] stepped single crystals, in remarkable agreement with earlier theoretical studies. We propose that the observed destabilisation of *OH species at these surfaces is due to the decreased solvation of the adsorbed hydroxyl intermediates on adjacent terrace sites. This journal is © the Partner Organisations 2014.

Voelskow K.,Institute of Chemical Process Engineering | Nickelsen L.,Institute of Chemical Process Engineering | Becker M.J.,Universitatsstr 150 | Xia W.,Universitatsstr 150 | And 4 more authors.
Chemical Engineering Journal | Year: 2013

A setup for optically monitoring the agglomerate growth of multiwalled carbon nanotubes (MWCNTs) by catalytic chemical vapor deposition on single Co-Mn-Al-Mg oxide catalyst particles with ethene as carbon precursor has been developed. Ethene concentrations and temperatures were varied between 5. -75. Vol.% and 550-770. °C, respectively. It could be shown that the agglomerate growth is rapid and the final diameter is reached after a few ten seconds to about 3. min depending on the reaction conditions. The average enlargement factor of the agglomerates over all experiments was found to be 6.5. ±. 1.2 compared to the original diameter of the catalyst particle. The growth rate is enhanced by both, reaction temperature and ethene concentration. Hence it is concluded that the agglomerate growth rate is associated with the reaction rate of MWCNT synthesis. Short time experiments and analysis of the resulting agglomerates have confirmed an earlier proposed growth mechanism. © 2013 Elsevier B.V.

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