Optische Methoden zur Charakterisierung von hochpolymeren Fasern. 1. Methodik der Interferenzmikroskopie

Density and orientation describe, besides other characteristics, the structure of high polymers. They can be obtained as a function of the radius by measurement of the refraction index of the fibre. The influence of refraction of light on the obtained index of refraction n(r) is demonstrated by an optical model of the fibre. For fibres having a radius R < 30 μm and changes in the refraction index < 0.02 the influence of refraction is less than ± 0.0002 and therefore of no significance for most textile fibres. Important is the exact adaption of the refraction index of the embeding medium to the margin of the fibre. The computed index at the margin of the fibre takes always the refraction index of the embeding medium. An incorrect adaption can be traced up to 0.2·R into the fibre. A spline function used for the approximation of the relative displacement of interference fringes gives the opportunity to calculate extreme variations in refractive index, this is demonstrated using hollow fibres filled with paraffin-oil. Using a HeNe-laser interference-holographie became possible.     

RNA helicases: versatile ATP-driven nanomotors

RNA helicases are a large family of molecular motors that utilize nucleoside triphosphates to unwind RNA duplexes and to remodel RNA protein complexes. In this review, we discuss the structure and function of RNA helicases with an emphasis on the potential application of these enzymes to control conformational changes in nanoassemblies that contain RNA.     

Aktuelle Probleme bei der Ultraschallprüfung von Freiformschmiedestücken

Die routinemäßige Ultraschallprüfung von Schmiedestücken und ihre Grenzen. Festlegungen in Regelwerken, Forderungen hinsichtlich Registrier- und Zulässigkeitsgrenzen. Prüfung austenitischer Bauteile, Einsatz spezieller Prüfköpfe und Geräte. Möglichkeiten der Automatisierung, Ausblick auf zukünftige Entwicklungen.     

Ermittlung des Aufbaus und der Stoffkennwerte von Außenbauteilen mit Hilfe von In‐situ‐Messungen und FEM‐Berechnungen

Determination of the construction and the material identity values of outside building components with the help of in‐situ measuring procedures and FEM‐simulation calculations. The aims formulated nationwide and internationally to the climate protection can be achieved by combining of the energy‐efficient construction and rehabilitation of the existing buildings. Knowledge about the construction and the material identity values of the warmth‐transferring outside components is a condition for the energetic balance of buildings. The essential information to this can frequently be no more taken from the construction documents particularly for older buildings since they are no longer traceable or incomplete. At the example by univalve and bivalve out‐wall construction it is shown that the thermophysical qualities can be determined with the help of in‐situ measuring procedures and FE‐simulation calculations without destruction.     

Solidification behaviour of binary sitosteryl esters mixtures

Phytosterol esters are known for their blood cholesterol lowering effect and have consequently been incorporated into vegetable oil table-spread products. In furtherance to gaining knowledge about these materials in a fat-blend environment, the current work describes the phase-diagram based thermal characteristics of a series of β-sitosterol alkyl-ester homologues prepared as binary mixtures and observed using differential scanning calorimetry. A scanning speed of 10 K min⁻¹ was chosen and, whilst not representing true equilibrium conditions, was more indicative of the likely dynamic melting or cooling conditions found in a fat-blend product during processing. The thermal behaviours presented reflect therefore this concept. Long-chain saturated esters showed ideal solubility behaviour of immiscible solids. In contrast, the shorter-chain homologues produced complex and dynamic phase behaviours, including some mesophase development. In all cases, supercooling was observed on cooling due to retarded crystallisation, which could equally result in two crystal conformations, depending on the actual composition.     

功能性纺织材料用超声装置

本研究的目的在于开发利用超声喷嘴浸渍纺织材料的新方法,使纺织品具有既定的功能性,并为进一步应用纳米技术以获得功能化产业用纺织品,以及服装用和装饰用纺织品打下技术基础。     

The effect of water temperature on the adsorption equilibrium of dissolved organic matter and atrazine on granular activated carbon

The influence of water temperature on the adsorption of natural dissolved organic matter (DOM) on activated carbon has not been investigated intensively yet. In this study, batch experiments with granular activated carbon (GAC) have been carried out at three temperatures (5 degrees C, 20 degrees C, 35 degrees C) using a humic acid model water and different types of surface water (lake, river, canal). Furthermore, the adsorption of an anthropogenic contaminant, atrazine, was quantified in the absence and presence of DOM. The results indicate a significant influence of water temperature on the adsorption equilibrium of DOM and atrazine. Contrary to expectations, DOM and atrazine adsorption in surface water tends to be increased with increasing water temperature, whereas the extent of this effect is dependent on the type and concentration of DOM. Furthermore, the temperature effect on atrazine adsorption is controlled by competition of DOM and atrazine on adsorption sites. Some assumptions are proposed and discussed for explaining the temperature effects observed in the batch studies.