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Martin V.I.,University of Seville | Rodriguez A.,University of Seville | Laschewsky A.,University Postdam | Laschewsky A.,Fraunhofer Institute for Applied Polymer Research | Moya M.L.,University of Seville
Journal of Colloid and Interface Science | Year: 2014

The micellization of four dimeric cationic surfactants ("gemini surfactants") derived from N-dodecyl-N,N,N-trimethylammonium chloride was studied in pure water and in water-ionic liquid (IL) solutions by a wide range of techniques. The dimeric surfactants are distinguished by their rigid spacer groups separating the two surfactant motifs, which range from C3 to C5 in length. In order to minimize organic ion pairing effects as well as the role of the ionic liquids as potential co-surfactants, ILs with inorganic hydrophilic anions and organic cations of limited hydrophobicity were chosen, namely ethyl, butyl, and hexyl-3-imidazolium chlorides. 1H NMR two-dimensional, 2D, rotating frame nuclear Overhauser effect spectroscopy measurements, ROESY, supported this premise. The spacer nature hardly affects the micellization process, neither in water nor in water-IL solutions. However, it does influence the tendency of the dimeric surfactants to form elongated micelles when surfactant concentration increases. In order to have a better understanding of the ternary water-IL surfactant systems, the micellization of the surfactants was also studied in aqueous NaCl solutions, in water-ethylene glycol and in water-formamide binary mixtures. The combined results show that the ionic liquids play a double role in the mixed systems, operating simultaneously as background electrolytes and as polar organic solvents. The IL role as organic co-solvent becomes more dominant when its concentration increases, and when the IL alkyl chain length augments. © 2014 Elsevier Inc. Source


Camps C.,Institut Universitaire de France | Camps C.,French National Institute for Agricultural Research | Kappel C.,Institut Universitaire de France | Kappel C.,University Postdam | And 8 more authors.
Plant Pathology | Year: 2014

Eutypa lata is the causal agent of eutypa dieback, a highly damaging trunk disease affecting all grape-growing areas, with currently neither an efficient curative treatment nor an early non-destructive diagnostic method. The present work was carried out to discover grapevine genes expressed in response to the presence of E. lata that could be useful to develop an early (before visible foliar symptoms) and non-destructive (using grapevine leaves) diagnostic tool. Microarray analyses were carried out from (i) infected plants showing characteristic E. lata foliar and vascular symptoms and positive pathogen recovery from vascular lesions (S+R+), (ii) infected plants showing no symptoms (S-R+), and (iii) symptomless plants with negative pathogen recovery (S-R-). Vineyard and greenhouse-grown plants, naturally or artificially infected respectively, and uninoculated controls were characterized and leaf RNA was hybridized with 15k operon grapevine oligonucleotide microarrays. Among the grapevine genes differentially expressed between S-R+ and S-R- plants in greenhouse and vineyard conditions, 10 were highlighted as robust candidate genes for diagnosis: seven were specifically involved in response to infection and three were associated with symptom absence. Five were confirmed to be effective diagnostic marker genes usable in a qRT-PCR-based test performed on RNA extracted from grapevine leaves cultivated in either greenhouse or vineyard conditions. Furthermore, their expression profiles in response to infection with E. lata or other major grapevine fungi (Erysiphe necator, Plasmopara viticola, Botrytis cinerea) could be distinguished. The usefulness of these genes to develop an early and non-destructive method for diagnosis of E. lata infection is discussed with regard to the advantages and drawbacks of previous E. lata diagnostic studies. Plant Pathology © 2013 British Society for Plant Pathology. Source


Zerball M.,TU Berlin | Laschewsky A.,Fraunhofer Institute for Applied Polymer Research | Laschewsky A.,University Postdam | Kohler R.,Helmholtz Center Berlin | Von Klitzing R.,TU Berlin
Polymers | Year: 2016

The study addresses the effect of thermal treatment on the internal structure of polyelectrolyte multilayers (PEMs). In order to get insight into the internal structure of PEMs, Neutron Reflectometry (NR) was used. PEMs with a deuterated inner block towards the substrate and a non-deuterated outer block were prepared and measured in 1% RH and in D2O before and after a thermal treatment. Complementarily, PEMs with the same number of layers but completely non-deuterated were investigated by ellipsometry. The analysis for the overall thickness (d), the average scattering length density (SLD) and the refractive index (n) indicate a degradation of the PEM. The loss in material is independent of the number of layers, i.e., only a constant part of the PEM is affected by degradation. The analysis of the internal structure revealed a more complex influence of thermal treatment on PEM structure. Only the outermost part of the PEM degenerates, while the inner part becomes denser during the thermal treatment. In addition, the swelling behavior of PEMs is influenced by the thermal treatment. The untreated PEM shows a well pronounced odd-even effect, i.e., PDADMAC-terminated PEMs take up more water than PSS-terminated PEMs. After the thermal treatment, the odd-even effect becomes much weaker. © 2016 by the authors. Source


Brewka G.,University of Leipzig | Delgrande J.,Simon Fraser University | Romero J.,University Postdam | Schaub T.,University Postdam | Schaub T.,French Institute for Research in Computer Science and Automation
Proceedings of the National Conference on Artificial Intelligence | Year: 2015

In this paper we describe asprin, a general, flexible, and extensible framework for handling preferences among the stable models of a logic program. We show how complex preference relations can be specified through user-defined preference types and their arguments. We describe how preference specifications are handled internally by so-called preference programs, which are used for dominance testing. We also give algorithms for computing one, or all, optimal stable models of a logic program. Notably, our algorithms depend on the complexity of the dominance tests and make use of multi-shot answer set solving technology. Copyright © 2015, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. Source


Zerball M.,TU Berlin | Laschewsky A.,University Postdam | Laschewsky A.,Fraunhofer Institute for Applied Polymer Research | Von Klitzing R.,TU Berlin
Journal of Physical Chemistry B | Year: 2015

The odd-even effect, i.e., the influence of the outermost layer of polyelectrolyte multilayers (PEMs) on their swelling behavior, is investigated. For that purpose poly(styrene sodium sulfonate) (PSS)/poly(diallyl-dimethylammonium chloride) (PDADMAC) polyelectrolyte multilayers are studied in air with 1% relative humidity (RH), 30% RH, 95% RH, and in liquid water by ellipsometry, atomic force microscopy (AFM), and X-ray reflectometry (XRR). Since the total amount of water uptake in swollen PEMs is divided into two fractions, the void water and the swelling water, a correct evaluation of the odd-even effect is only possible if both fractions are examined separately. In order to allow measuring samples over a larger thickness regime the investigation of a larger amount of samples is required. Therefore, the concept of separating void water from swelling water using neutron reflectometry is for the first time transferred to ellipsometry. The subsequent analysis of swelling water, void water, and roughness revealed the existence of two types of odd-even effects: an odd-even effect which addresses only the surface of the PEM (surface-odd-even effect) and an odd-even effect which addresses also the bulk of the PEM (bulk-odd-even effect). The appearance of both effects is dependent on the environment; the surface-odd-even effect is only detectable in humid air while the bulk-odd-even effect is only detectable in liquid water. The bulk-odd-even effect is related to the osmotic pressure between the PEM and the surrounding water. A correlation between the amount of void water and both odd-even effects is not found. The amount of void water is independent of the terminated layer and the thickness of PEMs. © 2015 American Chemical Society. Source

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