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Friedrich-Wilhelm-Lubke-Koog, Germany

Clauss S.,ETH Zurich | Gabriel J.,Purbond AG | Karbach A.,Currenta GmbH | Matner M.,Bayer AG | Niemz P.,ETH Zurich
Holzforschung | Year: 2011

Only small amounts of additives are needed to formulate one-component polyurethane (1C PUR) adhesives for various applications. The current study illuminates the effects of the formulation on the mechanical properties of pure adhesives, on the one hand, and their performance in bonded wood joints on the other. Tensile shear tests on bonded wood joints, tensile tests on adhesive films, and nanoindentation measurements in the interphase region of the bond were performed. Analyses by means of infrared, atomic force, and electron microscopy provided the explanatory basis for the results obtained. Additionally to laboratory made 1C PUR, unmodified commercial 1C PUR, melamine-urea- formaldehyde (MUF), and phenol-resorcinol-formaldehyde (PRF) were tested for comparison. The results obtained confirm that the mechanical properties of 1C PUR adhesives are significantly affected by their prepolymer composition. The adhesive formulation by means of additives, on the other hand, does not affect the mechanical properties but is to a large extent responsible for the bonding performance. © 2011 by Walter de Gruyter Berlin Boston. Source

Kreiss W.,Currenta GmbH | Frode R.,Bayer AG | Mohrle V.,Bayer AG
Analytical and Bioanalytical Chemistry | Year: 2010

By employing a novel technique for the direct coupling of a bacterial bioassay with chromatography, we discovered a gyrA promotor active compound in myxobacterial extracts and elucidated the structure directly without any isolation step. As a result, we identified inthomycin A as the bioactive substance. Our method is based on a whole-cell bioluminescent reporter gene assay coupled with thin-layer chromatography for primary hit detection and with liquid chromatography (LC)/mass spectrometry or LC/NMR for dereplication and structure elucidation. Previously, inthomycin A has been isolated from Streptomycetes and was associated with the inhibition of cellulose biosynthesis and herbicidal activity. Thus, our findings support the basic principle that completely different microbial phyla are able to synthesize the same natural product. Moreover, our results indicate that inthomycin A affects bacterial DNA supercoiling, which reveals an unexpected bioactivity for this compound. These results can possibly promote further investigation of the biosynthesis as well as the biological activity of inthomycins and related natural products. © 2010 Springer-Verlag. Source

Wetzstein H.-G.,Bayer Animal Health GmbH | Schneider J.,Bayer CropScience | Karl W.,Currenta GmbH
AMB Express | Year: 2012

Liquid cultures of the basidiomycetous fungus Gloeophyllum striatum were employed to study the biodegradation of pradofloxacin, a new veterinary fluoroquinolone antibiotic carrying a CN group at position C-8. After 16 days of incubation, metabolites were purified by micro-preparative high-performance liquid chromatography. Four metabolites could be identified by co-chromatography with chemically synthesized standards. The chemical structures of three compounds were resolved by 1H-nuclear magnetic resonance spectroscopy plus infrared spectroscopy in one case. All metabolites were confirmed by high resolution mass spectrometry-derived molecular formulae. They comprised compounds in which the carboxyl group or the fluorine atom had been exchanged for a hydroxyl group. Furthermore, replacement of the CN group and the intact amine moiety by a hydroxyl group as well as degradation of the amine substituent were observed. The chemical structure of a catechol-type fluoroquinolone metabolite (F-5) could be fully defined for the first time. The latter initiated a hypothetical degradation sequence providing a unique metabolite, F-13, which consisted of the cyclopropyl-substituted pyridone ring still carrying C-7 and C-8 of pradofloxacin, now linked by a double bond and substituted by a hydroxyl and the CN group, respectively. Most likely, all reactions were hydroxyl radical-driven. Metabolite F-13 proves fungal cleavage of the aromatic fluoroquinolone core for the first time. Hence, two decades after the emergence of the notion of the non-biodegradability of fluoroquinolones, fungal degradation of all key structural elements has been proven. © 2012 Springer-Verlag Berlin Heidelberg. Source

Leng G.,Currenta GmbH | Koch H.M.,Ruhr University Bochum | Gries W.,Currenta GmbH | Schutze A.,Ruhr University Bochum | And 3 more authors.
Toxicology Letters | Year: 2014

Di(2-propylheptyl) phthalate (DPHP), a high molecular weight phthalate, is primarily used as a plasticizer in polyvinyl chloride and vinyl chloride copolymers for technical applications, as a substitute for other phthalates currently being scrutinized because of endocrine disrupting effects.We determined urinary excretion fractions of three specific DPHP metabolites (mono-2-(propyl-6-hydroxy-heptyl)-phthalate (OH-MPHP), mono-2-(propyl-6-oxoheptyl)-phthalate (oxo-MPHP) and mono-2-(propyl-6-carboxy-hexyl)-phthalate (cx-MPHxP)) after oral dosing of five volunteers with 50 mg labelled DPHP-d4 and subsequent urine sampling for 48 h. These excretion fractions are used to back calculate external intakes from metabolite measurements in spot urine analysis. Following enzymatic hydrolysis to cleave possible conjugates, we determined these urinary metabolites by HPLC-NESI-MS/MS with limits of quantification (LOQ) between 0.3 and 0.5 μg/l.Maximum urinary concentrations were reached within 3-4 h post dose for all three metabolites; elimination half-lives were between 6 and 8 h. We identified oxo-MPHP as the major oxidized metabolite in urine representing 13.5 ± 4.0% of the DPHP dose as the mean of the five volunteers within 48 h post dose. 10.7 ± 3.6% of the dose was excreted as OH-DPHP and only 0.48 ± 0.13% as cx-MPHxP. Thus, within 48 h, 24.7 ± 7.6% of the DPHP dose was excreted as these three specific oxidized DPHP metabolites, with the bulk excreted within 24 h post dose (22.9 ± 7.3%).These secondary, oxidized metabolites are suitable and specific biomarkers to determine DPHP exposure. In population studies, however, chromatographic separation of these metabolites from other isomeric di-isodecyl phthalate (DIDP) metabolites is warranted (preferably by GC-MS) in order to distinguish DPHP from general DIDP exposure. Palatinol®, Hexamoll® and DINCH® are registered trademarks of BASF SE, Germany. © 2014 The Authors. Source

Schutze A.,Ruhr University Bochum | Gries W.,Currenta GmbH | Kolossa-Gehring M.,Federal Environment Agency UBA | Apel P.,Federal Environment Agency UBA | And 5 more authors.
International Journal of Hygiene and Environmental Health | Year: 2015

Bis-(2-propylheptyl)-phthalate (DPHP) has been introduced as a substitute for other high molecular weight phthalates primarily used in high temperature applications (e.g. cable wires, roofing membranes). The aim of this study was to investigate how the increased usage of DPHP is reflected in urine samples collected over the last 14 years and to evaluate the current extent of exposure.We analyzed 300 urine samples (24. h voids) from the German Environmental Specimen Bank collected in the years 1999, 2003, 2006, 2009 and 2012, 60 samples per year, from 30 male and 30 female volunteers (age: 20-30 years) for three specific, secondary oxidized DPHP metabolites (with hydroxy, oxo and carboxy modifications of the alkyl side chain). We determined DPHP metabolites with a previously developed GC-HRMS method, enabling us to unambiguously distinguish DPHP metabolites from co-eluting, structurally isomeric di- iso-decyl phthalate (DIDP) metabolites. All samples were blinded before analysis.We detected no DPHP metabolites in urine samples from the years 1999, 2003 and 2006. Thereafter, detection rates increased from 3.3% in 2009 to 21.7% in 2012. Mono-oxo-propylheptylphthalate (oxo-MPHP) was the most abundant metabolite, with concentrations between Source

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