Influence of pressure release rate and protein concentration on the formation of pressure-induced casein structures

The formation of pressure-induced casein structures (600 MPa for 30 min at 30 degrees C) was investigated for different pressure release rates (20 to 600 MPa min-1) and casein contents (1 to 15 g/100 ml). Structures from liquid (sol) to solid (gel) were observed. The higher the protein content and the pressure release rate, the higher was the dynamic viscosity. A firm gel was built up at a casein content of 7 g/100 ml for a pressure release rate of 600 MPa min-1, while lower release rates resulted in less firm gels (200 MPa min-1) or liquid structures (20 MPa min-1). In a 5 g/100 ml casein solution and at a pressure release rate of 600 MPa min-1, casein aggregates were generated which were built from smaller casein particles with a larger hydrodynamic diameter and higher voluminosity than in the untreated solution. After a slow release rate casein micelles had a smaller hydrodynamic diameter and a lower voluminosity, but were similar in shape and diameter as compared with the micelles in solution before high pressure treatment.     

Zum Einfluss der Nietkopfabrostung auf die Nietvorspannung und Dauerhaftigkeit alter Stahlkonstruktionen

The influence of rivet corrosion on the durability of riveted connections. Rivets are often particular locations of accelerated corrosion in riveted bridges. In particular the heads of the rivets are subject of rust and corrosion. Therefore the question is whether and how much the pre‐stressing effect of the rivet will be affected by the material degradation of the rivet's head, such that the load deformation and the fatigue behaviour will be reduced. The following paper presents latest investigations on the effect of rivet head corrosion on the pre‐stressing of the rivet by means of milling the rivet head and numerical simulations. Taking the results of further experiments into account a prediction of fatigue strength in dependence of the material reduction and therefore the pre‐stressing will be possible, as stress peakes in the plate are the more the less the pre‐stress is.     

Synthetic Hydrophilic Materials with Tunable Strength and a Range of Hydrophobic Interactions

The ability to vary, adjust, and control hydrophobic interactions is crucial in manipulating interactions between biological objects and the surface of synthetic materials in aqueous environment. To this end a grafted polymer layer (multi‐component mixed polymer brush) is synthesized that is capable of reversibly exposing nanometer‐sized hydrophobic fragments at its hydrophilic surface and of tuning, turning on, and turning off the hydrophobic interactions. The reversible switching occurs in response to changes in the environment and alters the strength and range of attractive interactions between the layer and hydrophobic or amphiphilic probes in water. The grafted layer retains its overall hydrophilicity, while local hydrophobic forces enable the grafted layer to sense and attract the hydrophobic domains of protein molecules dissolved in the aqueous environment. The hydrophobic interactions between the material and a hydrophobic probe are investigated using atomic force microscopy measurements and a long‐range attractive and contact‐adhesive interaction between the material and the probe is observed, which is controlled by environmental conditions. Switching of the layer exterior is also confirmed via protein adsorption measurements.     

The sol–gel transition temperature of skim milk concentrated by microfiltration as affected by pH and protein content

This study aimed at determining sol–gel transition temperatures of microfiltered skim milk retentates for different protein levels (6, 8 and 10% (w/w)) and a wide pH range (native pH to 4.6) by means of small‐amplitude oscillatory shear rheology. For a pH of 5.4 to 5.0, the sol–gel transition temperatures decreased significantly with increasing protein content, which did not differ for pH 4.8 and 4.6. The sol–gel transition temperatures of retentates with 10% (w/w) protein at pH 5.4 and 4.6 were 58.4 °C and 10.9 °C, respectively.     

Leukoencephalomalacia in two horses--moldy corn poisoning in Germany?

Moldy corn poisoning is a mycotoxicosis of Fusarium sp. causing a disease termed equine leukoencephalomalacia (ELEM). This article reviews the literature on ELEM and describes two cases with clinical signs and morphological findings comparable with fusariotoxicosis. Since in both cases neither a fungus nor a toxin proof were performed, the different causes of leukoencephalomalacia in horses are discussed.     

Hochtemperaturkorrosion von Nickel in Chlor und Chlor-Sauerstoffgemischen

High temperature corrosion of nickel in chlorine and chloride oxygen mixtures Investigation of the chlorination and oxychlorination of nickel in a quartz ap-paratus at 600 to 850°C. In chlorine a surface layer of Ni chloride is formed which adheres well to the metal surface up to 75O°C, while it is damaged by spalling at higher temperatures. The reaction rate depends from temperature, chlorine partial pressure and flow velocity. The kinetic law is parabolic but undergoes a pronounced change at higher temperatures because of the sublimation of nickel chloride. In chlorine-oxygen mixtures there may be processes similar to combustion at chlorine contents as low as about 1.2 Vol.-%. This fact can be attributed to the hinderance by oxy-gen of the normally occurring dissociation of NiCl; this reaction is substituted by another one yielding on the one hand NiO, on the other hand chlorine.