Intramolecular carbon and nitrogen isotope analysis by quantitative dry fragmentation of the phenylurea herbicide isoproturon in a combined injector/capillary reactor prior to GC separation

Potentially, compound-specific isotope analysis may provide unique information on source and fate of pesticides in natural systems. Yet for isotope analysis, LC-based methods that are based on the use of organic solvents often cannot be used and GC-based analysis is frequently not possible due to thermolability of the analyte. A typical example of a compound with such properties is isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea), belonging to the worldwide extensively used phenylurea herbicides. To make isoproturon accessible to carbon and nitrogen isotope analysis, we developed a GC-based method during which isoproturon was quantitatively fragmented to dimethylamine and 4-isopropylphenylisocyanate. Fragmentation occurred only partially in the injector but was mainly achieved on a heated capillary column. The fragments were then chromatographically separated and individually measured by isotope ratio mass spectrometry. The reliability of the method was tested in hydrolysis experiments with three isotopically different batches of isoproturon. For all three products, the same isotope fractionation factors were observed during conversion and the difference in isotope composition between the batches was preserved. This study demonstrates that fragmentation of phenylurea herbicides does not only make them accessible to isotope analysis but even enables determination of intramolecular isotope fractionation.     

Functional testing and characterisation of (bio-)chemical sensors on wafer level

An automated computer-assisted system for the functional testing and characterisation of (bio-)chemical sensors on wafer level is developed and integrated into a commercial prober station. The system enables the identification and selection of “good” sensors on wafer level and thus, allows to avoid further expensive bonding, encapsulation and packaging processes for defective or non-functioning sensor structures. Moreover, a specifically designed flow-through electrochemical microcell offers the possibility of wafer-level characterisation of (bio-)chemical sensors in terms of sensitivity, drift, hysteresis and response time at an early process stage. The system has been exemplarily tested using wafers combining pH-sensitive capacitive electrolyte-insulator-semiconductor structures as well as ion-sensitive field-effect transistors with different geometrical sizes and gate layouts.     

Photoactivatable Mussel‐Based Underwater Adhesive Proteins by an Expanded Genetic Code

Marine mussels exhibit potent underwater adhesion abilities under hostile conditions by employing 3,4‐dihydroxyphenylalanine (DOPA)‐rich mussel adhesive proteins (MAPs). However, their recombinant production is a major biotechnological challenge. Herein, a novel strategy based on genetic code expansion has been developed by engineering efficient aminoacyl‐transfer RNA synthetases (aaRSs) for the photocaged noncanonical amino acid ortho‐nitrobenzyl DOPA (ONB‐DOPA). The engineered ONB‐DOPARS enables in vivo production of MAP type 5 site‐specifically equipped with multiple instances of ONB‐DOPA to yield photocaged, spatiotemporally controlled underwater adhesives. Upon exposure to UV light, these proteins feature elevated wet adhesion properties. This concept offers new perspectives for the production of recombinant bioadhesives.     

The Oxidative Dehydrogenation of <Emphasis Type="Italic">n</Emphasis>-Hexane over a β-NiMoO<Subscript>4</Subscript> Catalyst

Abstract  

The oxidative dehydrogenation of n-hexane over β-NiMoO₄ catalysts was performed in a fixed bed continuous flow reactor. Catalytic testing was done below and above the flammability limits for n-hexane and the effect of reaction conditions was examined to optimize hexene selectivity. The contact times (0.61-2.4 s), n-hexane/oxygen molar ratios and nitrogen dilution (31–60%) were varied. The highest selectivity to total hexenes obtained was 54.7% which was made up of 27.4% 1-hexene, 25.0% trans-2-hexene and 2.3% cis-2-hexene. These selectivities were obtained at a fuel/O₂ ratio of 2.2, a contact time of 1.0 s and 43% nitrogen dilution.     

Das digitale geologische Strukturmodell Bitterfeld als neuer Baustein in der Sanierungsforschung

Zur Erfassung, Bewertung und Behandlung gro?r?umiger Grundwasserkontaminationen ist die Kenntnis des geologischen Aufbaus des Untergrundes für eine Vorhersage des Schadstoffverhaltens eine unbedingte Voraussetzung. Im Rahmen des SAFIRA-Projektes ist für ein Modellgebiet des ?GP Bitterfeld/Wolfen die Architektur der Lockergesteinsaquifere in ein digitales geologisches Raummodell überführt worden. Basierend auf 125 Bohraufschlüssen, mit 28 vernetzten Profilschnitten, konnte die lithologische und strukturelle Heterogenit?t in 31 lithostratigraphischen Sedimentationsk?rpern plausibel auf der Basis eines 10 × 10 m-Rasters GIS-gestützt abgebildet werden. Die Zuordnung hydraulischer Parameter zu den einzelnen Sedimentk?rpern erlaubt die sp?tere Nutzung mit Str?mungs- und Transportmodellen. Das in Kombination von Profilschnitten und Fl?chendaten generierte Raummodell erm?glicht neben beliebigen Visualisierungen auch die Berechnung von Kubaturen einzelner Schichten. Dies ist z. B. bei der Restbraunkohle für die Absch?tzung von Schadstoffretentionen und -remobilisierungen im Untergrund von erheblicher Bedeutung. Das hier vorgestellte geologische 3-D-Strukturmodell ist die Grundlage für die weiteren Bearbeitungen zur Bewertung von Umweltauswirkungen und Sanierungsvarianten.     

Hydrophobic recovery of atmospheric pressure plasma treated surfaces of Wood-Polymer Composites (WPC)

In this study, the behavior of atmospheric pressure plasma treated surfaces of Wood-Polymer Composites (WPC) was investigated as a function of time and environmental conditions. The surfaces of injection molded WPC based on polypropylene (PP) and polyethylene (PE) were treated by a dielectric barrier discharge (DBD) and subsequently aged under various conditions. The wettability as an indicator for change of the composite surface was assessed using water contact angle. In addition, a calculation for half-time of the contact angles was developed to predict the time span which is needed for recovery of hydrophobicity. The results showed a major influence of temperature and time, whereas the humidity only at storing conditions of 60?°C and 75% relative humidity showed a distinct effect on the activated surface. The effect of DBD treatment was stable for more than one week in the climates 20?°C and 0% RH and 20?°C and 65% RH.