Anisotropy Effects in the Shape-Memory Performance of Polymer Foams

Isotropic and anisotropic shape-memory polymer foams are prepared by supercritical carbon dioxide foaming from a multiblock copolymer (PDLCL) consisting of poly(ω-pentadecalactone) and poly(ε-caprolactone) segments. Analysis by micro-computed tomography reveals for the anisotropic PDLCL foam cells a high shape anisotropy ratio of R = 1.72 ± 0.62 with a corresponding Young's compression moduli ratio between longitudinal and transversal direction of 4.3. The experimental compression data in the linear elastic range can be well described by the anisotropic open foam model of Gibson and Ashby. A micro-morphological analysis for single pores using scanning electron microscopy images permits the correlation between the macroscopic stress-compression behavior and microscale structural changes.     

Cutaneous Adverse Events Associated with Interferon-β Treatment of Multiple Sclerosis

Interferons are widely used platform therapies as disease-modifying treatment of patients with multiple sclerosis. Although interferons are usually safe and well tolerated, they frequently cause dermatological side effects. Here, we present a multiple sclerosis (MS) patient treated with interferon-β who developed new-onset psoriasis. Both her MS as well as her psoriasis finally responded to treatment with fumarates. This case illustrates that interferons not only cause local but also systemic adverse events of the skin. These systemic side effects might indicate that the Th17/IL-17 axis plays a prominent role in the immunopathogenesis of this individual case and that the autoimmune process might be deteriorated by further administration of interferons. In conclusion, we think that neurologists should be aware of systemic cutaneous side effects and have a closer look on interferon-associated skin lesions. Detection of psoriasiform lesions might indicate that interferons are probably not beneficial in the individual situation. We suggest that skin lesions may serve as biomarkers to allocate MS patients to adequate disease-modifying drugs.     

Application of the Electrodiffusion Method to Measure Wall Shear Stress: Integrating Theory and Practice

The electrodiffusion method has been used in fluid dynamic research for the past 50 years. It allows the measurement of wall shear stress, a crucial parameter, e.g., for the cleaning of membrane modules used in water filtration. Various authors have published articles dealing with the theory behind this technique. But no paper collects all the knowledge assembled over five decades of application. Here, comprehensive summary of the theory of steady flow, unsteady flow, and transient voltage step experiments is given. Factors influencing the accuracy of the measurements are discussed. Furthermore, a new approach to calibrate the system from voltage step experiments is introduced, and practical issues related to its application in flow measurements are discussed for an exemplary signal response to a near‐wall flow.     

Porous Perovskite Fibers – Preparation by Wet Phase Inversion Spinning and Catalytic Activity

Porous perovskite (LaMnO₃) fibers were prepared by means of wet phase inversion spinning. The influence of different spinning procedures, slurry and coagulation bath composition on fiber shape and pore morphology was studied. The catalytic activity of the prepared fibers was tested for carbon monoxide oxidation as a model reaction in a differential recycle reactor. The results revealed that by suitable choice of process conditions porous catalytically active fibers can be prepared. Catalytic measurements confirmed that the catalytic fibers exhibit an open structure that allows full utilization of the catalytically active surface without intraparticle diffusional limitations.     

Structure‐Based Mechanism of Oleate Hydratase from Elizabethkingia meningoseptica

Hydratases provide access to secondary and tertiary alcohols by regio‐ and/or stereospecifically adding water to carbon‐carbon double bonds. Thereby, hydroxy groups are introduced without the need for costly cofactor recycling, and that makes this approach highly interesting on an industrial scale. Here we present the first crystal structure of a recombinant oleate hydratase originating from Elizabethkingia meningoseptica in the presence of flavin adenine dinucleotide (FAD). A structure‐based mutagenesis study targeting active site residues identified E122 and Y241 as crucial for the activation of a water molecule and for protonation of the double bond, respectively. Moreover, we also observed that two‐electron reduction of FAD results in a sevenfold increase in the substrate hydration rate. We propose the first reaction mechanism for this enzyme class that explains the requirement for the flavin cofactor and the involvement of conserved amino acid residues in this regio‐ and stereoselective hydration.     

From Isonitriles to Unsaturated NHC Complexes of Gold,Palladium and Platinum

In a modular template synthesis, unsaturated NHC complexes of gold, palladium and platinum were synthesized from simple metal salts, isonitriles and amines with acetal or ketal groups. Upon the addition of amines with tethered acetal or ketal moieties to the metal‐activated isonitrile, first nitrogen acyclic carbene (NAC) complexes are formed. These undergo ring closure and elimination to the unsaturated NHC complexes upon addition of acid. This simple strategy opens an attractive and fast approach to NHC complexes of gold, palladium and platinum. The modular approach allows a fast modification and is well‐suited for the synthesis of unsymetrically and symmetrically substituted unsaturated NHC complexes.

     

Towards a Practical and Efficient Copper-Catalyzed Trifluoromethylation of Aryl Halides

The first copper-catalyzed trifluoromethylation of aryl halides was developed that utilizes inexpensive trifluoroacetates. Providing low concentrations of the most economically attractive and atom-efficient trifluoromethylation reagent this new protocol is advantageous compared to known procedures both economically and ecologically.     

Large Eddy Simulation of Turbulent Reacting Mixing of Liquids in a Coaxial Jet Mixer

Large eddy simulation is used to investigate passive and reactive scalar mixing at high Reynolds Re and Schmidt Sc numbers in order to prove capability of the LES‐SGS micromixing approaches based on the eddy dissipation and DQMOM‐IEM models properly simulating liquid reacting flows. Simulations were performed for a fast neutralization reaction in a confined jet reactor. The mean profiles for passive scalar agree well with measurements. It was shown that the most contribution to the scalar variance is made by large scale motions whereas the contribution of fine scales smaller than typical inertial range scales is negligible. Thus, the existing LES models are capable of predicting the scalar variance at large Sc numbers. The results obtained for reactive transport revealed discrepancies in the determination of micromixing rate and product concentration. A special study was performed to investigate the dynamics of fine structures using locally refined box embedded into global grid. Typical statistical properties of fine structures were reproduced numerically.     

Oxygen permeation of various archetypes of oxygen membranes based on BSCF

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3‐δ tubes, capillaries, capillary modules, and asymmetric membranes were prepared and tested for oxygen permeation in a dead‐end vacuum operation mode at temperatures up to 850^°C. The capillary module was built up by reactive air brazing using seven capillaries and a supply tube. Two machined discs were used as an end cap and as a connector plate. The oxygen permeation behaves according to Wagner at small driving forces, but significant negative deviations were observed for asymmetric membranes and single capillaries at higher ones. This is caused by pressure drops at the vacuum side for single capillaries. The highest oxygen flux was revealed for the capillary module with 175.5 mL(STP)/min at a low‐vacuum pressure of 0.042 bar at 850^°C, but the asymmetric membrane showing a little bit higher flux at moderate vacuum pressures above 0.07 bar. © 2012 American Institute of Chemical Engineers AIChE J, 58: 3195–3202, 2012     

Easy access to pharmaceutically relevant heterocycles by catalytic reactions involving α-imino gold carbene intermediates

This review summarizes recent advances in the field of gold-catalyzed synthesis of pharmaceutically relevant aza-heterocycles via in situ generated α-imino gold carbene complexes as intermediates.