Thermal stability of chloroform in the steam-condensate cycle of CANDU-PHW nuclear power plant

Analysis of samples taken at the Gentilly 2 (Québec) CANDU-PHW (CANadian Deuterium Uranium - Pressurized Heavy Water) plant after chlorination and demineralization revealed the presence of all four trihalomethanes (THMs) (CHCl₃, CHBrCl₂, CHBr₂Cl and CHBr₃) and other unidentified halogenated volatile compounds. Among the THMs, chloroform was the major contaminant. A study of its thermal stability in water at different temperatures confirmed the degradation of the CHCl₃ molecule according to the equation CHCl₃ + H₂O → CO + 3 HCl. The reaction follow a first order kinetics and has an activation energy of 100 kJ/mol. The estimated half-life is six seconds at 260°C, the maximum temperature of the steam-condensate cycle.     

Homology Model Adjustment and Ligand Screening with a Pseudoreceptor of the Human Histamine H4 Receptor

A new pseudoreceptor modeling method (PRPS) was applied to the refinement of a homology model of the human histamine H₄ receptor (H₄R), the prediction of a ligand binding site, and virtual screening. Retrieval of two new H₄R ligands demonstrates the biological relevance of the pseudoreceptor model and provides a means for finding new hits and leads in the early phases of drug discovery.

     

Grauwasserreinigung mit einer Sumpfpflanzenmatte unter Praxisbedingungen

There is increasing interest worldwide in the decentralized treatment of gray water. Since ground‐level areas are generally costly, gray‐water treatment can also be carried out using helophyte mats on the roofs of buildings as an alternative. Alongside the water treatment itself, this process also has a positive effect on the indoor climate in the building. In a test carried out under realistic conditions, it was shown that a helophyte mat with a root‐layer depth of 0.1 m and with hydraulic loads per unit up to 15 L m^?2d^?1 is suitable for treating typical gray water from a residential building.     

Assessment of alimentary histamine exposure of consumers in Austria and development of tolerable levels in typical foods

Although alimentary intake of histamine can cause intoxication, legal limits for histamine content in the EU, exist for certain seafish species only. The present study suggests tolerable levels for fermented sausage, fish and cheese which are based on relating the amount of histamine not expected to cause any health effects after ingestion to typically consumed amounts of food. Limits of 500 and 400 mg/kg would seem to be justifiable for fermented sausage and cheese, respectively. For fish species other than those already regulated in EU, the “m”/”M” limits of 100 and 200 mg/kg can be adopted. These limits can be met by current food technology.     

Atomic Friction Investigations on Ordered Superstructures

We review recent friction measurements on ordered superstructures performed by atomic force microscopy. In particular, we consider ultrathin KBr films on NaCl(001) and Cu(001) surfaces, single and bilayer graphene on SiC(0001), and the herringbone reconstruction of Au(111). Atomically resolved friction images of these systems show periodic features spanning across several unit cells. Although the physical mechanisms responsible for the formation of these superstructures are quite different, the experimental results can be interpreted within the same phenomenological framework. A comparison between experiments and modeling shows that, in the cases of KBr films on NaCl(001) and of graphene films, the tip-surface interaction is well described by a potential with the periodicity of the substrate which is modulated or, respectively, superimposed with a potential with the symmetry of the superstructure.     

Thermodynamic models for vapor-liquid equilibria of nitrogen + oxygen + carbon dioxide at low temperatures

For the design and optimization of CO₂ recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry’s law constants, are proposed for the ternary mixture N₂ + O₂ + CO₂. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry’s law constants of N₂ and O₂ in CO₂ are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry’s law constants, is developed to reliably describe the VLE in the CO₂-rich region.     

Fabrikation und Anwendung von metallischen Schichtverbundwerkstoffen

Through a clever combination of different materials, tailor-made composite materials can be fabricated which are able to fulfil high requirements often set by modern applications. Laminated composites of materials with different yield strengths, promising due to their damage tolerance, are discussed, and selected manufacturing methods suited for their production are presented. Utilizing the press bonding method, Ferrite/Martensite composites with 7 and 13 layers were manufactured and the influence of geometry and friction was assessed by layer thickness measurements. It could be shown that the gradient in degree of deformation inherent to the process can be reduced by lubrication, which results in improved parallelism and more even bond strengths.