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.     

The Lithiation Reactivity and Selectivity of Differentially Branched Alkyldiphenylphosphine Oxides – A Simple and Versatile Approach to ortho‐Functionalized Arylphosphine Oxides

Alkyldiphenylphosphine oxides typically undergo α‐deprotonation with alkyllithium reagents. Here, the lithiation of differentially branched alkyldiphenylphosphine oxides was investigated and a diverse, but predictable reactivity was found. γ‐Branched derivatives undergo selective directed ortho‐metalation (DoM) using butyllithium and TMEDA as an additive. With decreasing degree of γ‐branching α‐lithiation becomes predominant. The ortho‐phosphinoyllithium intermediates are subject to functionalization and C C bond forming reactions, thus providing a convenient approach to new phosphine oxides and phosphine‐borane complexes, which have a good potential for an approach to new ligands for catalysis.

     

Lignin from Annual Plants as Raw Material Source for Flavors and Basic Chemicals

The enzymatic conversion of lignins, possibly in combination with electrochemical oxidation, makes aromatics such as syringol, guaiacol, vanillin and catechol available in the qualities required by the fragrance industry. The lignins were obtained by soda digestion from wheat straw and Miscanthus, characterized and then converted with laccases. The overall yield amounted up to 9 wt % with a product spectrum confined to four substances. Catechol was the major product, with a fraction of ≈75 %. It can easily be isolated by extraction with acetone.     

Studies of a thermomechanically treated Al-Zn-Mg alloy

The influence of subgrain structure on the precipitation process in an Al-4.2 wt% Zn-1.6 wt% Mg alloy was studied and correlated with its mechanical properties for ageing temperatures of 110, 142 and 165° C.     

Comparison of methods for determination of microbial biomass in wastewater

Microbial biomass in wastewater was determined by methods used in environmental microbiology and by a method used in wastewater engineering based on a conceptual model simulating fundamental microbial processes in wastewater from measured oxygen uptake rates. The methods originating from environmental microbiology are based on staining and counting of cells for the determination of total cell biomass (acridine orange and DAPI), physiological state of cells (LIVE/DEAD BacLight) and activity of cells (reduction of the redox dye CTC and microautoradiography). Depending on the staining method applied, cell biomasses yielded 15-86% of the biomass defined by the model, and good correlations between cell biomass and model biomass were found. Cell biomass, oxygen uptake and acetate uptake were measured in wastewater, where acetate was added. Substrate uptake rates were found not to be proportional to the increases in cell biomass, suggesting that only a small fraction of the cell biomass was responsible for the main part of the substrate uptake. Despite the differences found between cell biomass and model biomass, it was recommended to use the conceptual model as an engineering tool for simulation of microbial processes and wastewater quality changes. However, there should be a clear distinction between the terms 'model biomass', 'cell biomass' and different activity measurements of cells.     

Test methods for polymeric insulating materials for outdoor HVinsulation

The paper describes an analysis of standardized and non-standardized test methods for polymeric insulating materials, either suitable or applied for, outdoor HV insulation. The analysis particularly considers the increasing use of silicone elastomers for composite insulators. In the first part, test methods covering erosion/tracking performance and hydrolysis phenomena are discussed. These are inclined plane test (IPT) and arc test (AT) for the evaluation of the tracking and erosion behavior as well as boiling water test (BWT) for the evaluation of the HV diffusion-breakdown-strength. These tests have a long tradition in the field of material research. Secondly, the resistance of hydrophobicity under accelerating aging conditions using simultaneous moisture and voltage stress is considered. Results from the rotating wheel dip test (RWDT) are presented and related to results from an equivalent salt-fog test. The third part of the paper deals with the regeneration of hydrophobicity after sample exposure to moisture and corona discharges. Recovery includes also the transfer of hydrophobicity into pollution layers, which is quantified by measurement of dynamic contact angle