Structural engineering of nanoporous anodic aluminium oxide by pulse anodization of aluminium

Nanoporous anodic aluminium oxide has traditionally been made in one of two ways: mild anodization or hard anodization. The first method produces self-ordered pore structures, but it is slow and only works for a narrow range of processing conditions; the second method, which is widely used in the aluminium industry, is faster, but it produces films with disordered pore structures. Here we report a novel approach termed "pulse anodization" that combines the advantages of the mild and hard anodization processes. By designing the pulse sequences it is possible to control both the composition and pore structure of the anodic aluminium oxide films while maintaining high throughput. We use pulse anodization to delaminate a single as-prepared anodic film into a stack of well-defined nanoporous alumina membrane sheets, and also to fabricate novel three-dimensional nanostructures.     

Querung des Elbe‐Seitenkanals und des Mittellandkanals mittels Horizontal‐Directional‐Drilling für eine 380‐km‐Pipeline

Crossing of the Elbe‐Seitenkanal and the Mittellandkanal using HDD‐Technology for a 380 km long pipeline. The federal network of waterways and canals today comprises approximately 7500 km of inland waterways. Not restricted to economic use in transportation, the waterways also have a function in the water supply and distribution (water for industry and agriculture, flood protection etc.). As owner of federal waterways, the Federal Republic of Germany, according to the Basic law, section 87 and 89, manages these by an independent administrative authority, the Wasser‐ und Schifffahrtsverwaltung des Bundes (WSV), localy represented by the appropriate office, the Wasser‐ und Schifffahrtsamt (WSA). The WSA acts according to § 31 WaStrG as authorizing agency for river‐ and navigation‐specific police approval of third‐party installations intended for crossing or culverting the Federal Waterway route, as in this case. In the course of constructing a 380 km long pipeline from Stade to Teutschenthal (PST) a total of 203 horizontal directional drillings (HDD) were carried out. 24 of them concerned the crossing of big rivers and channels. Two technically extremely demanding projects proved to be the crossing of the Elbe‐Seitenkanal (ESK) and the crossing of the Mittellandkanal (MLK).     

Acetylation of faba bean legumin: conformational changes and aggregation

The effect of progressive acetylation upon the conformation of the 11S globulin legumin from faba bean has been studied using chemical analysis, UV, fluorescence and CD spectroscopy, viscometry and analytical ultracentrifugation. The modification did not induce complete dissociation of the oligomeric protein. Only 30% of the protein was found to be a dissociated 3S subunit after excessive acetylation, whereas 70% was a dimeric legumin aggregate with a molecular mass of about 700 kDa. The aggregation of the highly modified legumin in high‐ionic‐strength buffer solution leads to soluble higher legumin oligomers. The acetylation resulted in a moderate molecular expansion of legumin due to a changed tertiary structure, whereas the far‐UV circular dichroism spectra did not provide definitive evidence of a decrease in domain‐stabilizing β‐sheet conformations in their secondary structure. © 2000 Society of Chemical Industry     

Solid immiscibility in milk fat fractions and methods to determine their occurrence

In this work, the occurrence of solid phase immiscibility during the fractionation process of milk fat is documented. It is shown that solid phase immiscibility occurs in normal fractionation procedures, upon crystallisation at low temperatures and in particular on further fractionation of narrow melting fractions. This phenomenon results in distinct phases of crystallisation. In some cases, the initial phase yields intermediate solid levels independent of increasing supersaturation. The subsequent increase of solids content is solely a contribution of a second, independent crystallisation event. Furthermore, it could be shown that the induction time for the second crystallisation event is not influenced by the presence or absence of the first triacylglyceride group. These results clearly indicate the independence of the crystallisation of the different immiscible fractions in terms of kinetics and thermodynamics. The different processes during the crystallisation process are monitored simply by viscosimetry.     

PGSS-drying: Mechanisms and modeling

Micronization of polyethylene glycol from aqueous solutions has been successfully performed with particles from gas-saturated solutions (PGSS)-drying process, producing spherical PEG particles with average particle size of 10 μm and residual water content below 1 wt%. Based on experimental results, an analysis of the fundamentals of the process has been developed, discussing mass and energy balances, phase equilibrium conditions, mass transfer rates and atomization mechanisms. Some discrepancies between experimentally observed moisture concentration in powder and calculations based on the mass balance and the phase equilibrium have been observed, which have been attributed to the kinetic evolution of pressure and temperature along the expansion path. The static mixer used to saturate the solution with CO₂ has been analyzed with phase equilibrium and mass transfer calculations, concluding that a significant fraction of water is extracted to the gas phase already in the static mixer, and high CO₂ concentrations are achieved in the liquid due to the high solubility of CO₂ in PEG. All experimental trends of variation of particle size with process parameters can be explained considering a flash-boiling atomization mechanism dependant on the concentration of CO₂ in the solution after the static mixer.     

Reaction calorimetric investigation of the ring-opening polymerization of ε-caprolactone

The ring-opening polymerization of ε-caprolactone was investigated by means of the Mettler RC1 reaction calorimeter. In the range of small and medium monomer conversions this method can successfully be used for the determination of the course of the bulk polymerizations. The experimental results obtained by calorimetric and gravimetric method, respectively, are compared and the course of the polymerization is discussed in dependence on the reaction parameters (initiator, temperature).     

Strategie für eine Konversion der Chlorchemie

Strategy for Conversion of Chlorine Chemistry . After years of discussion about ?cessation of chlorine chemistry”?, the study entitled ?Conversion of Chlorine Chemistry”? [1] commissioned by the Environmental Ministry of the State of Hesse in Germany and undertaken by Prognos AG provides the very first detailed comparative ecological and economical assessment of production process and products of ?chlorine chemistry”? and industrially feasible alternatives and presents a strategy for partial transformation. This accomplished on the basis of a systematic assessment of risks and benefits, as demanded by the Geman parliametary commission ?Protection of Humankind and the Environment”?.