Synthesis of a difunctional orthogonal coupler for the preparation of carbohydrate-functionalized sP(EO-stat-PO) hydrogels

The synthesis and characterization of a new difunctional coupler (4) based on trimethylolpropane (TMP) are described. The coupler is used to connect biologically active N-acetylglucosamine (GlcNAc) on amino-reactive microtiter plates and on star-shaped poly[(ethylene oxide)-stat-(propylene oxide)] hydrogel layers in microtiter plates. The biological activity of immobilized carbohydrates is determined using an enzyme-linked lectin assay.     

Intra-operative optical diagnostics with vibrational spectroscopy

Established methods for characterization of tissue and diagnostics, for example histochemistry, magnetic resonance imaging (MRI), X-ray tomography, or positron emission tomography (PET), are mostly not suitable for intra-operative use. However, there is a clear need for an intra-operative diagnostics especially to identify the borderline between normal and tumor tissue. Currently, vibrational spectroscopy techniques (both Raman and infrared) complement the standard methods for tissue diagnostics. Vibrational spectroscopy has the potential for intra-operative use, because it can provide a biochemically based profile of tissue in real time and without requiring additional contrast agents, which may perturb the tissue under investigation. In addition, no electric potential needs to be applied, and the measurements are not affected by electromagnetic fields. Currently, promising approaches include Raman fiber techniques and nonlinear Raman spectroscopy. Infrared spectroscopy is also being used to examine freshly resected tissue ex vivo in the operating theater. The immense volume of information contained in Raman and infrared spectra requires multivariate analysis to extract relevant information to distinguish different types of tissue. The promise and limitations of vibrational spectroscopy methods as intra-operative tools are surveyed in this review.     

Nitrogen uptake of nickel free austenitic stainless steel powder during heat treatment—an XPS study

In austenitic stainless steel nitrogen stabilizes the austenitic phase, improves the mechanical properties and increases the corrosion resistance. Nitrogen alloying enables to produce austenitic steels without the element nickel which is high priced and classified as allergy inducing. A novel production route is nitrogen alloying of CrMn‐prealloyed steel powder via the gas phase. This is beneficial as the nitrogen content can be adjusted above the amount that is reached during conventional casting. A problem which has to be overcome is the oxide layer present on the powder surface which impedes both the sintering process and the uptake of nitrogen. This study focuses on whether heat treatment under pure nitrogen is an appropriate procedure to enable sintering and nitrogen uptake by reduction of surface oxides. X‐ray photoelectron spectroscopy (XPS) in combination with scanning electron microscopy (SEM) and energy dispersive X‐ray spectrometry (EDS) are used to investigate the surface of powdered FeMn19Cr17C0.4N heat treated under nitrogen atmosphere. The analyses showed reduction of iron oxides already at 500 °C leading to oxide‐free metallic surface zones. Mn and Cr oxides are reduced at higher temperatures. Distinct nitrogen uptake was registered, and successful subsequent sintering was reached. Copyright © 2014 John Wiley & Sons, Ltd.     

Organic molecular beam deposition of oligophenyls on Au111: A study by X-ray absorption spectroscopy.

Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy has been applied to reveal the molecular arrangement of ultrathin oligophenyl films [p-quaterphenyl (4P) and p-hexaphenyl (6P)] on Au(111). In the half-monolayer films the molecules lie flat on the surface but still have a considerable inter-ring twist of 30 degrees -40 degrees , similar to the gas-phase conformation. In the saturated monolayer film the second half of the molecules is side-tilted by an angle of less than 66 degrees with respect to the surface. This arrangement is already similar to that in bulk net planes of thicker films parallel to the surface, that is, the 4P(211) and 6P(21-3) planes, respectively.     

Selective Acceptorless Dehydrogenation of Primary Amines to Imines by Core–Shell Cobalt Nanoparticles

Core–shell nanocatalysts are attractive due to their versatility and stability. Here, we describe cobalt nanoparticles encapsulated within graphitic shells prepared via the pyrolysis of a cationic poly‐ionic liquid (PIL) with a cobalt(II) chloride anion. The resulting material has a core–shell structure that displays excellent activity and selectivity in the self‐dehydrogenation and hetero‐dehydrogenation of primary amines to their corresponding imines. Furthermore, the catalyst exhibits excellent activity in the synthesis of secondary imines from substrates with various reducible functional groups (C=C, C≡C and C≡N) and amino acid derivatives.     

Orchestration of discoid polyketide cyclization in the resistomycin pathway

Resistomycin is a bacterial polyphenolic metabolite from Streptomyces resistomycificus with a unique pentacyclic "discoid" ring system that clearly differs from the typical linear or angular architectures of aromatic polyketides. The first comprehensive cyclase amino acid sequence-function correlation revealed that the enzymes directing the nascent polyketide chain into a peri-fused system clearly differ from canonical linear and angular cyclases. All genes that are required and sufficent for resistomycin (rem) biosynthesis were identified through systematic dissection and reconstitution of the type II polyketide synthase (PKS) complex. The minimal rem PKS and the first cyclase were successfully cross-complemented with orthologues from the linear tetracenomycin polyketide pathway, indicating that both dekaketide pathways share early biosynthetic steps. In total three cyclases that are involved in discoid cyclization (RemI, RemF, and RemL) were identified by mutational analyses and in vivo pathway reconstitution. Analyses of the metabolic profiles of mutants expressing incomplete gene sets led to the discovery of a novel tetracenomycin derivative, TcmR1. The most surprising finding is that only the concerted action of the PKS and all three cyclases leads to the discoid ring structure. These results provide strong support for a model according to which the multienzyme complex forms a cage in which the polyketide is shaped, rather than a sequential cyclization of the polyketide chain by individual enzymes.     

Development and in-house validation of an LC-MS/MS method for the determination of stilbenes and resorcylic acid lactones in bovine urine

Stilbenes and zeranol are nonsteroidal estrogenic growth promoters which are banned in the European Union (EU) for use in food-producing animals by Council Directive 96/22/EC. A liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was developed for the screening and confirmation of stilbenes (diethylstilbestrol, dienestrol, hexestrol) and resorcylic acid lactones (zeranol and its metabolites taleranol and zearalanone as well as the mycotoxins α-zearalenol, β-zearalenol and zearalenone) in bovine urine. The method permits the confirmation and quantification of stilbenes and resorcylic acid lactones at levels below 1 μg L⁻¹ and 1.5 μg L⁻¹, respectively. The validation was carried out according to Commission Decision 2002/657/EC, Chap. 3.1.3 “alternative validation” by a matrix-comprehensive in-house validation concept. Decision limit CCα, detection capability CCβ, recovery, repeatabiliy, within-laboratory reproducibility and the uncertainty of measurement were calculated. Furthermore, a factorial effect analysis was carried out to identify factors that have a significant influence on the method. Factors considered to be relevant for the method in routine analysis (e.g. operator, matrix condition, storage duration of the extracts before measurement, different cartridge lots, hydrolysis conditions) were systematically varied on two levels. The factorial analysis showed that different cartridge lots, storage durations and matrix conditions can exert a relevant influence on the method.