Stabilitätsanalyse eines aufgelassenen Gipsbergbaus – von der geologisch-hydrogeologisch-geotechnischen Datenerfassung zur numerischen 3D-Simulation

The assessment of the stability of underground structures is an interdisciplinary task which consists of geology, hydrogeology, surveying and geotechnical engineering. This paper gives an example of how these disciplines, their methods and the acquisition of data work together to create a complex three-dimensional computer-model of underground structures. It demonstrates, that especially the complex layout of old and “grown” underground structures cannot be represented accurately in two-dimensional analyses or models and provide no realistic results for stability investigations. Related to the stability of underground structures, a non-negligible factor is the influence of water, whether surface, rain or groundwater. The occurring leaching process of gypsum leads to a weakening of the surrounding rock which causes a strength reduction. This softening of the material must be considered in long-term simulations. The presented comprehensive approach tries to provide a possibility to predict the time-dependent occurrence of vulnerabilities in the rock mass and thus gives the possibility to install support measures in an early stage.     

Entwicklung und Erprobung eines Verfahrens zur Untergrundentsäuerung von Kippengrundwässern

Sulfate-reducing processes were initiated in an aquifer with AMD-laden groundwater orthogonally to the located main groundwater flow direction. Groundwater was intermittently circulated between two wells. Substrate (methanol) and nutrients were added to this flow. After one year a sulphate-reducing reactor was formed in the aquifer, that precipitated FeS and decreased the acidity. These effects could still be observed one year after cessation of substrate amendment.     

Spiro‐Bridged Ladder‐Type Oligo(para‐phenylene)s: Fine Tuning Solid State Structure and Optical Properties

A set of ladder‐type quaterphenyls with an incremental number of spiro‐bifluorene units in the bridge positions as well as an in‐plane bent quaterphenyl carrying all bridges on one and the same side of the ribbon are synthesized and characterized. While spiro‐bifluorene substituents lead to bathochromically shifted maxima in the UV–vis absorption spectra, this effect can be compensated by in‐plane bending. The influence of different deposition techniques on the solid state structure is analyzed by X‐ray diffraction of single crystals obtained by crystallization from solution as well as sublimation. An increasing number of spiro‐bifluorene substituents are found to aid thin‐film formation.     

Glucosinolate and Trichome Defenses in a Natural Arabidopsis lyrata Population

Glucosinolates (GS) and trichomes contribute to plant resistance against insect herbivores in the model Arabidopsis thaliana. The functional and genetic characteristics of herbivore defense, however, can differ even between closely related species. In a quantitative genetic experiment with the out-crossing perennial Arabidopsis lyrata spp. petraea, we measured constitutive GS composition, trichome density, leaf thickness, and plant resistance in four different herbivore interactions. In a single population of A. lyrata, we found heritable variation for trichome density as well as GS amount and carbon side-chain elongation ratios associated with activity in methylthioalkylmalate synthase (MAM). Unexpectedly, heritabilities for indole GS in A. lyrata were high and less affected by differences in plant age and environment than aliphatic GS. We found significant heritability in plant resistance to the specialist Plutella xylostella and generalist Trichoplusia ni, but not to the specialists Pieris brassicae and Phyllotreta cruciferae. Analyses of phenotypic and genetic correlations between candidate defense traits and insect resistance suggested that A. lyrata resistance was conferred by a combination of indole GS amount and trichome density, and, to a lesser extent, aliphatic GS ratios and leaf thickness. Variation in the most abundant compound, the aliphatic 3-hydroxypropyl GS, had little impact on A. lyrata herbivore resistance. The contribution of defense traits to resistance depended on the experimental herbivory context, and resistances were weakly correlated. A diversified defense strategy is likely to be important for long-lived individuals of A. lyrata that are subject to attack by many different herbivores in nature.     

Green Emission in Ladder‐Type Quarterphenyl: Beyond the Fluorenone‐Defect

In polyfluorenes it is generally accepted that (photo)degradation leads to fluorenone type defects that accept the excitation energy and emit green‐to‐yellow light with rather low efficiency. Although initial spectroscopic studies suggest the same to hold true for ladder‐type poly(para‐phenylene)s (LPPPs), kinetic studies of the degradation process are not compatible with the established mechanism. In general, the observed green emission can be caused by the introduction of carbonyl groups; however, only if associated with an additional disruption of the backbone rigidity and hence planarity of the entire π‐system. This is clearly shown by comparison with synthesized model compounds, which are bearing the fluorenone motif yet possess very different optical properties as compared to the defects, which are actually formed. Degradation can be caused by solvent specific, yet substrate nonspecific aromatic formylation but mainly originates from reaction with in‐situ generated singlet oxygen, both in solution as well as in thin films. Time‐dependent photoluminescence measurements on thin films show that green emission is enhanced by energy transfer from intact molecules to defect centers.     

Hydroresin dispersions: tailoring morphology of latex particles and films

Hydroresin dispersions are a new class of emulsifier free polyacrylate secondary dispersions. They are prepared by the emulsification of self-emulsifying polymer blends in water. The blends typically consist of two polymers, one is a salt group containing copolymer, the other is a hydrophobic polymer without salt groups. The particle diameters can be controlled by the amount of salt group containing polymer and the concentration of salt groups in this polymer. One advantage over conventional secondary dispersions is the fact that they are not only water dilutable but free of organic solvents. Another advantage is the extremely low content of hydrophilic salt groups in the resulting polymer mixture, which leads to very hydrophobic films. The application properties of these aqueous systems are more similar to those of organic polymer solutions than to conventional emulsion polymers. Applications of these surfactant free binders are in areas such as solvent face road marking paints and corrosion protection coatings without active pigments. The technique for the preparation of hydroresin dispersions is also useful for the creation of latex particles with core-shell structures. Two examples are given, which differ in the glass transition temperature of both the cores and the shells. From these dispersions, films with defined morphology can be prepared. A blending of the polymers with hydrophobic low molecular weight compounds, before the emulsification step, is also possible. It can be used for the incorporation of additional functions into the latex particles. As an example, the loading of latexes with a hydrophobic fluorescent dye is given.     

Grundwasser in ehemaligen deutschen Steinkohlenrevieren – ein wissenschaftlicher Blickwinkel auf Grubenflutungen

Grundwasser - Zum Ende des Jahres 2018 wurde in Deutschland der Steinkohlenbergbau eingestellt. Damit beginnt auch in den bis zuletzt aktiven Revieren die Phase des Nachbergbaus inklusive einer...     

Hydrogeologie im Tauernfenster – Fallbeispiel Rauristal,Salzburg

Grundwasser - Die Fallstudie in einem kleinräumigen Einzugsgebiet im Salzburger Rauristal diente dazu, die Hydrogeologie einiger für das Tauernfenster typischer Lithologien und Strukturen...