Über die Bestimmung des Zirkoniums in hochlegierten Stählen

Übersicht über die im Schrifttum aufgeführten Verfahren zur Zirkoniumbestimmung und deren Schwierigkeiten. Nacharbeitung der photometrischen Bestimmung mit Arsenazo III und Einsatz bei hohen Legierungsgehalten. Anwendung des Verfahrens auf geringere Zirkoniumgehalte ohne Vortrennung.     

Dekontamination von Primärverpackungen mittels Atmosphärendruckplasmen

Decontamination of primary packaging by means of atmospheric plasmas The increasing demand of perishable products in urban areas as well as the globalisation of the markets also rises up the requirements for packaging. The storage life of these products is provided by microbial reduction in food and packaging, which is realized by aseptic filling or diffusion barriers. Furthermore, in pharmaceutical products it is recommended that preserving agents should not be added to avoid allergic reactions. Therefore packaging with low microbial load up to sterility is needed. Sterilization in wet (peracetic acid) or dry (hydrogen peroxide) set ups are currently available and used in the beverage industry. Pharmaceutical and food industry would prefer decontamination methods without hazardous substances. The possibility of plasma to generate antimicrobial effective components such as UV light, charged particles (ions, electrons) and reactive radicals offers an alternative to common decontamination methods. Plasmas can be separated in two main groups, the low‐pressure plasma and the atmospheric pressure plasma which have advantages and disadvantages. However, both are expected to require lower total process times than the current chemical methods. The construction for bottle treatment used in this study is based on microwave‐driven self propagating discharge. A careful design of the plasma source by using simulation tools is necessary to avoid hot spots during the bottle treatment. Minimization of process times before and after the decontamination treatment is necessary for industrial processes. The lock in and lock out of the bottles into the microwave area may be a limitative factor. Therefore the development of a barrier‐free transport system for 200 ml PET bottles was realized in this work. Temperature investigations of the material PET showed a critical temperature range above 60 °C at 4 cycles of 1000 W. After an 1 second plasma treatment a maximal reduction rate of 2 log10 was observed. A longer treatment time of 5 minutes led to an inactivation of 4 to 5 log10 for vegetative bacteria and of 2 to 3 log10 for Bacillus spores. Moreover an optimization of plasma generation inside the bottles may increase the microbiological inactivation. An optimization of the antimicrobial efficiency is necessary and detailed investigations of inactivation mechanisms of atmospheric pressure plasma should follow.     

Shoe soles for the gripping robot: Searching for polymer-based materials maximising friction

The development of light-weight climbing robots capable of operating in various environments is a growing area in robotics. That is why there is a strong need for new tribologically-optimised materials at their gripping devices that may lead to the enhancement of the attachment force while reducing energy expenditure. Since insects are equipped with a set of very efficient attachment systems, enabling them to grip a variety of substrates, they may provide approaches for the innovation of climbing robots’ grippers. The goal of our study was a broad screening of polymeric materials to find out those with similar structure and functional principles to biological examples known from insect smooth attachment systems. Friction, adhesion and stiffness measurements were carried out. Rubber foamy materials covered with thin polymeric films and sandwich-like materials provided excellent compliant properties and the best performance in experiments (friction coefficients up to 3.2).     

Effect of octene content on peroxide crosslinking of ethylene–octene copolymers

Various ethylene–octene copolymers were crosslinked by dicumyl peroxide. Octene content was 16, 20, 30, 35 and 38 wt% and melt flow index was 1 or 3 g/10 min. The concentration of dicumyl peroxide was 0.3, 0.5 and 0.7 wt%. Crosslinking was analyzed by a rubber process analyzer in the temperature range 150–200 °C. Cross‐linkability was evaluated from the real part modulus s'_max versus peroxide level plots as the slope of the line. With decreasing octene content and increasing melt flow index the crosslinkability increased. This was confirmed also by tan δ analysis. The network density was measured by the gel content. A higher gel content was found for melt flow index 3 and low octene content. The melting points T_m and the crystallinities were evaluated by DSC. © 2012 Society of Chemical Industry     

Geochemistry of fly ash from desulphurisation process performed by sodium bicarbonate

The application of NEUTREC^® technology - desulphurisation by means of sodium bicarbonate - has been tested at the Trebovice coal-fired power plant (Ostrava, Czech Republic). This technology significantly influences the chemical composition of fly ash and the leachability of total dissolved substances (TDS), e.g., sulphates, fluorides and oxyanions (Se, Sb, Cr, As), which are monitored according to the Council of the European Union Decision 2003/33/EC. An increase of TDS in the water leachate from the fly ash obtained at 60% desulphurisation was influenced by sodium content, which is present in the form of Na⁺ ions (85-90%). The percentages of sodium sulphate and sodium carbonate were between 5 and 10% of the total sodium content. In order to decrease the leachability of TDS, sodium, sulphates and oxyanion mixtures were prepared containing a sorbent (60% bentonite) and mixed with desulphurised and non-desulphurised fly ash in various ratios. The addition of CaO resulted in the formation of a new mineral phase, burkeite. None of the applied technologies tested for the processed fly ash resulted in the preparation of a water leachate which complied in all monitored parameters to the requirements of Council Decision 2003/33 EC for nonhazardous wastes.     

Utilization of the Linear Mode of MALDI‐TOF Mass Spectrometry in the Study of Glycation During the Malting Process

The process of glycation during the malting process was monitored by the linear mode of matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐TOF MS). Water‐soluble proteins were investigated and two hulled barley varieties, Jersey and Tolar, were compared to the hulless line KM 1910. The crude extracts of the proteins obtained from the grain, the malt, and aliquots collected every 24 h during the malting process, were mixed with the matrix (2,6‐dihydroxyacetophenone) and analyzed by mass spectrometry. The protein composition of the barley changed during the malting process. The protein patterns did not differ significantly between the three varieties of the barley grains. However, significant differences between the malts were evident. Results showed the influence of the malting process on the glycation of certain water‐soluble barley proteins, nonspecific lipid transfer protein 1 (LTP1) and protein Z, of which the glycated forms survived the brewing process. These major barley proteins are very important for the formation and stability of beer foam and glycation may prevent their precipitation. Analysis results indicated that slight glycation of the proteins had occurred on the second day of malting. The linear mode of MALDI‐TOF mass spectrometry was used as a fast and simple method for monitoring the patterns of low‐molecular weight barley proteins with regard to barley variety discrimination. This procedure also enables the selection of barley varieties suitable for the malting industry.     

Evolution of Microstructure of Cold‐Spray Aluminum Coatings on Al2O3 Substrates

Electron backscatter diffraction is used to study the microstructural evolution of cold‐spray aluminum coatings on Al₂O₃ substrates. The influence of powder purity and substrate heating on the kernel average misorientation and the distribution of low‐angle grain boundaries in as‐sprayed and annealed coatings are discussed in terms of dynamic recovery and dynamic recrystallization.