Entschwefelung von gerührtem und ungerührtem Roheisen mit kalkreicher Schlacke unter oxidierender Gasatmosphäre

Aus Betriebsergebnissen bei der Pfannenentschwefelung ist ein negativer Einfluß oxidierender Gasphasen bekannt. Daher war es das Ziel der eigenen Untersuchungen in einer geeigneten Apparatur die Wirkung oxidierender Bedingungen in der Gasphase sowohl auf den Verlauf des Schwefelabbaues in der Schlacke als auch des Schwefeltransportes aus dem Roheisen in die Schlacke zu untersuchen. Oxidierende Gasphasen erwirken bei der Pfannenentschwefelung an der Phasengrenze Schlacke/Gas eine Oxidation des Schwefels aus der Schlacke, ohne jedoch bei ruhender Schlackenschicht ein Oxidationspotential in der Schlacke aufzubauen, das bis zur Phasengrenze Roheisen/Schlacke durchgreift und dort die Entschwefelung des Roheisens durch die Siliciumgehalte stört. Sowohl die Entschwefelung des Roheisens als auch die Oxidation des Schwefels aus der Schlacke werden durch höhere Temperaturen und durch eine Rührwirkung gefördert. Der Schwefeltransport wird bei den ungerührten wie bei den gerührten Schmelzen durch Diffusionsvorgänge gesteuert und auch hier durch steigende Temperaturen und rührende Kräfte begünstigt.     

Formation and retention of local melted films in AZ91 friction stir spot welds

The formation of local melted films during friction stir spot welding of as-cast AZ91D and thixomolded AZ91 material is investigated. The average temperatures close to the tip of the rotating pin vary from 438 to 454 °C during the dwell period in friction stir spot welding. These measured temperature values are higher than the melting temperature of α-Mg + Mg₁₇Al₁₂ eutectic (437 °C). It is suggested that the temperature in the stir zone during the dwell period is determined by the relative proportions of α-Mg and (α-Mg + Mg₁₇Al₁₂) eutectic material, which are incorporated during friction stir spot welding. Based on the stir zone temperature measurements and a detailed examination of material located at the root of the pin thread it is suggested that material is moved downwards via the pin thread and into the stir zone during the dwell period in friction stir spot welding. Evidence of local melted film formation is observed in the stir zone of AZ91 spot welds. It is suggested that melted films are retained since their dissolution rate is much slower in the high temperature stir zone than it is when melted films is formed in the stir zone during Al 7075-T6 friction stir spot welding. The spontaneous melting temperature, solute diffusion rate and the thermodynamic driving force for droplet dissolution are much higher during Al 7075-T6 friction stir spot welding.     

Glyconanoparticle-DNA interactions: an atomic force microscopy study.

Glyconanoparticles which present carbohydrate and amino groups motifs at their surface were produced. These particles were highly stable and soluble in aqueous solutions. The presence of the carbohydrate groups also allowed the inclusion of more strongly binding groups, without affecting solubility. The binding of a model DNA, plasmid by these nanoparticles was studied by atomic force microscopy, transmission electron microscopy, and gel electrophoresis. Significant differences between the nanoparticles based on their affinities for the DNA were found, with implications for their potential use as nonviral gene delivery agents.     

What are the key elements of a sustainable university?

Nowadays, the principles of sustainable development are becoming increasingly important and universities are acting as agents in promoting these principles within society. In the future, universities will inevitably play crucial role in propagating these principles. This paper highlights important documents and discusses definitions of the term education for sustainable development. Elements, based on continuous feedback loop (Deming spiral) are discussed, in order to incorporate sustainability principles into university activities. The University of Maribor has been used as a case study to test the effectiveness of the proposed integration of sustainable development principles.     

Imaging the domain pattern of the canted magnetization state in Co/Pt multilayer films

The exact magnetization pattern of magnetic films close to a spin-reorientation transition is difficult to analyze due to the intrinsically three-dimensional (3d) variation of the orientation of the local magnetization. We present a technique how this can be performed, based on the analysis of high quality 2d polarization maps from a single scanning electron microscope with polarization analysis (SEMPA) measurement with tilted sample. The key tool is the statistical distribution of all occurring polarization doublets, visualized in a 2d histogram plot. From the shape of the distribution the type of transition—canted-phase, or coexisting phases—can be inferred. For the canted-phase state, the canting angle can be accurately determined from geometrical considerations. With help of the histogram the image data can be analyzed and the three components of the magnetization can be calculated for most points of the image. For a Co/Pt multilayer film we found a cone state. The magnetization forms a complex pattern consisting of out-of-plane domains while the in-plane magnetization shows a maze pattern.     

Response Selection in Visual Search: The Influence of Response Compatibility of Nontargets.

The authors used visual search tasks in which components of the classic flanker task (B. A. Eriksen & C. W. Eriksen, 1974) were introduced. In several experiments the authors obtained evidence of parallel search for a target among distractor elements. Therefore, 2-stage models of visual search predict no effect of the identity of those distractors. However, clear compatibility effects of the distractors were obtained: Responses were faster when the distractors were compatible with the response than when they were incompatible. These results show that even in parallel search tasks identity information is extracted from the distractors. In addition, alternative interpretations of the results in terms of the occasional identification of a distractor before or after the target was identified could be ruled out. The results showed that flat search slopes obtained in visual search experiments provide no benchmark for preattentive processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification and modelling of aerobic hydrolysis – application of optimal experimental design

Hydrolysis mechanism plays a dominant role in the delicate balance of electron donor/electron acceptor ratios in BNR and EBPR systems as an important carbon source. In this study, the surface‐saturation‐type hydrolysis kinetics was investigated based on respirometric measurements, within the context of the theoretical and the practical identifiability of mathematical models. The identifiable parameters of a selected model were derived from respirograms. In addition, the information from the experiments was evaluated on the basis of Optimal Experimental Design (OED) methodology for different initial conditions of the batch respirometric experiment. © 2003 Society of Chemical Industry     

The effects of glycol methacrylate as a dehydrating agent on the dimensional changes of liver tissue

The dimensional changes of liver sections during the course of processing with glycol methacrylate (GMA) or with ethanol are described. Tissue processing with ethanol served as a control. During prolonged processing steps (24 h each), linear shrinkage of tissue specimens dehydrated with GMA at room temperature was 13.2%. Subsequent infiltration with GMA resulted in trivial swelling, and polymerization in slight shrinkage (2.3%). In comparison, processing with cold GMA resulted in shrinkage during dehydration (about 10.8%), a slight swelling in pure GMA, followed by shrinkage during polymerization (2.2%). Short routine processing schedules resulted in similar shrinkage/swelling patterns, although precise values differed slightly. In all experiments, ethanolic dehydration resulted in smaller dimensional tissue changes than did GMA dehydration. The dimensional changes of tissue sections during stretching on water, mounting and drying compensated for the major part of the shrinkage manifested during processing.