Transition metals to sulfur binding energies relationship to catalytic activities in HDS: back to Sabatier with first principle calculations

We have undertaken systematic calculations of transition metal sulfides bulk crystal structures, electronic and energetic properties at the first principles level (DFT, GGA, PW-USPP, PBC, implemented in the Vienna Ab initio Simulation Package, VASP). Relaxed cell parameters and ionic positions showed an excellent agreement with the experimental values. Computed and experimental cohesive energies agreed within 3%. We re-defined the metal–sulfur (M–S) bond strength as the cohesive energy per metal–sulfur bond: we show that all experimental HDS activities (Pecoraro and Chianelli, 1981) fit nicely on a single volcano master curve when plotted against this simple energetic parameter. Metallic (i.e. zero gap) ionic sulfides consistently exhibit the weakest M–S bonds and semi-conductor iono-covalent sulfides the strongest. However, the Sabatier principle suggests a simple kinetic interpretation of this master curve. This new interpretation also accounts for the well known synergetic effects in mixed sulfides and therefore opens new prospects for exploratory applied research.     

Effektivität von Maßnahmen zur Reduktion der Phosphorbelastung der oberösterreichischen Fließgewässer

Assessing the effectiveness of measures to reduce the phosphorus loads in bodies of water in the plains of catchment areas requires a comprehensive grasp of the interactions between human activities, resulting emissions, and their effects on those waters. A quantitative representation of the connection between emissions loads over different pathways and emissions concentrations, and which takes into account the retention in both land and water, is called for as an essential basis. Once this has been established, in the next phase the effects of local emission reduction measures can be evaluated, the suitability of said measures for implementation in a given region on the basis of the predominant local conditions and land use management can be determined, and the effectiveness of the respective models can be represented in the context of overall emissions and retention. The findings of related studies in Upper Austria show that erosion protection measures and/or measures to avoid erosive phosphorus emissions in running water bodies have the best potential for reducing phosphorus loads when they are precisely targeted (used in areas with a high degree of connectedness to bodies of water or adjacent to running waters).     

50. Sitzung des AK Technik der DSB

Ohne Zusammenfassung     

Zur physikalischen Chemie des Chlorcalciumserums der Milch

Ohne ZusammenfassungMitteilung aus dem Laboratorium für Chemie und Bakteriologie der Milch am Landwirtschaftlichen Institut der Universität Göttingen.     

Employing industrial standards in software engineering for W7X

The stellarator W7X is a large complex experiment designed for continuous operation and planned to be operated for about 20 years. Software support is highly demanded for experiment preparation, operation and data analysis which in turn induces serious non-functional requirements on the software quality like, e.g.:

• high availability, stability, maintainability vs.

• high flexibility concerning change of functionality, technology, personnel

• high versatility concerning the scale of system size and performance

These challenges are best met by exploiting industrial experience in quality management and assurance (QM/QA), e.g. focusing on top-down development methods, developing an integral functional system model, using UML as a diagramming standard, building vertical prototypes, support for distributed development, etc., which have been used for W7X, however on an ‘as necessary’ basis. Proceeding in this manner gave significant results for control, data acquisition, corresponding database-structures and user applications over many years.As soon as production systems started using the software in the labs or on a prototype the development activity demanded to be organized in a more rigorous process mainly to provide stable operation conditions. Thus a process improvement activity was started for stepwise introduction of quality assuring processes with tool support taking standards like CMMI, ISO-15504 (SPICE) as a guideline. Experiences obtained so far will be reported.We conclude software engineering and quality assurance has to be an integral part of systems engineering right from the beginning of projects and be organized according to industrial standards to be prepared for the challenges of nuclear fusion research.     

A hierarchical tree layout algorithm with an application to corporate management in a change process

This work presents a hierarchical tree layout algorithm based on iterative rearrangement of subtrees. Using a greedy heuristic, all subtrees of a common parent are rearranged into a forest such that gaps between them are minimized. This heuristic is used to build a rearranged tree from bottom-up, starting with forests of the single leafs, and ending with the complete tree. Different cost measures for arrangement operations are discussed, which are based on the shape of a subtree. This shape can be characterized by the subtree’s leftmost and rightmost vertices, which determine how gapless this subtree can be combined with another one. The layout algorithm is used to display an organisational hierarchy. Such a hierarchical layout aids leadership when organisational structures are complex. In particular, it can be used to monitor the performance of organisational units undergoing change, e.g. restructuring. This improves the effectiveness of leadership instruments.     

Determination of geosmin and 2,4,6-trichloroanisole in white and red Austrian wines by headspace SPME-GC/MS and comparison with sensory analysis

This paper describes the development and application of a fast and simple headspace solid phase microextraction GC–MS method for simultaneous determination of geosmin and 2,4,6-trichloroanisole (2,4,6-TCA), two main contributors to off-flavors in wine. The compounds were adsorbed onto a polydimethoxysiloxane (PDMS) fiber at 35 °C for 40 min without prior equilibration, thermally desorbed and analyzed by GC–MS in the selected ion monitoring mode. The parameters for adsorption onto and desorption from the fiber were optimized. This method was applied to analysis of 118 Austrian white and red wines, which were also characterized by sensory analysis. Geosmin was above the limit of detection (0.5 ng/L) in 110 wines (93%) and additionally quantified (>2 ng/L) in 65 wines (55%). It could be detected in wines of each off-flavor (moldy, corky, damp, musty, rotten, woody, grassy) in concentrations up to 16.7 ng/L and even in 90% of the sensorially faultless wines (up to 6.5 ng/L). On the other hand, 2,4,6-trichloroanisole was detected only in 24 wines (20% of all investigated wines) and above the limit of quantitation (2 ng/L) only in 5 wines (4%) sensorially classified as corky; corky and moldy plus other defects; or faultless in concentrations up to 14.3 ng/L. These results show that geosmin is more prevalent than 2,4,6-TCA and that chemical analysis is required especially when other wine characteristic flavors cover beginning off-flavors.     

Insulation capability of the bark of trees with different fire adaptation

When exposed to a surface fire, the probability of a tree to survive widely varies, depending on its capability to protect the cambium from lethal temperatures above 60 °C. Thereby, the bark, the entirety of all tissues outside the cambium, serves as an insulation layer. In laboratory experiments, the heat production of a surface fire was simulated and the time span τ₆₀ until the temperature of 60 °C is reached in the inner bark surface was measured. Thereby, τ₆₀—as a measure of the fire resistance—was quantitatively determined for seven tree species. In addition, the influence of bark thickness and moisture content on bark heat insulation capacities was examined. Independent of the tree species and bark moisture content a power function correlation between bark thickness and τ₆₀ was found. Our results also show that fire resistance increases with decreasing bark density. The seven tree species examined can be classified in two groups differing highly significant in their bark structure: (1) tree species with a faintly structured bark, which show a low fire resistance, and (2) tree species with an intensely structured bark, showing a high fire resistance. Furthermore a mathematical model simulating heat conduction was applied to describe the experimental results, and some ideas for a transfer into biomimetic materials are presented.