Molecular structure and rheological properties of a poly(ethylene terephthalate) modified by two different chain extenders

This paper compares the molecular structure and rheological properties of a commercial poly(ethylene terephthalate) (PET) after reactive processing with different concentrations of either pyromellitic dianhydride (PMDA) or a multifunctional epoxide (Joncryl®ADR-4368) as a chain extender. By size exclusion chromatography with triple detection, an increase of molar mass, a broadening of molar mass distribution, and the generation of long-chain branched molecules were found for both chain extenders. While gel-free materials were obtained with PMDA, the processing with Joncryl leads to the formation of gels. The effect of branching, indicated by the Mark–Houwink exponent, is more pronounced for materials with Joncryl compared to PMDA and points to a more compact branching structure of the PET/Joncryl molecules. Rheological measurements in shear and elongation support the analysis from SEC and reveal a complex tree-like branching structure for both chain extenders. In addition, the role of the two modifiers with respect to processing was assessed.     

Newly Isolated Animal Pathogen Corynebacterium silvaticum Is Cytotoxic to Human Epithelial Cells

Corynebacterium silvaticum is a newly identified animal pathogen of forest animals such as roe deer and wild boars. The species is closely related to the emerging human pathogen Corynebacterium ulcerans and the widely distributed animal pathogen Corynebacterium pseudotuberculosis. In this study, Corynebacterium silvaticum strain W25 was characterized with respect to its interaction with human cell lines. Microscopy, measurement of transepithelial electric resistance and cytotoxicity assays revealed detrimental effects of C. silvaticum to different human epithelial cell lines and to an invertebrate animal model, Galleria mellonella larvae, comparable to diphtheria toxin-secreting C. ulcerans. Furthermore, the results obtained may indicate a considerable zoonotic potential of this newly identified species.     

The anode effect as a fluid dynamic problem

The so-called anode effect, particularly important in industrial alumina electrolysis, has mostly been interpreted as the consequence of altered wettability of the electrode surface by the melt. By means of a mathematical model assuming isolated large bubbles in contact with the electrode it is shown that the anode effect is the result of the combined action of fluid dynamics and wettability. The interpretation of the incipience of the anode effect obtained by means of a previous, completely different mathematical model is confirmed. The theoretical results are compared with experimental data by various authors.     

DIMENSIONLESS REPRESENTATION OF PARTICLE SEPARATION CHARACTERISTIC OF CYCLONES

In particular the collection efficiencies were measured as a function of flow rate, cyclone dimensions and particle size. For this purpose a fast, accurate and problem adapted measuring technique has been used, which enables the determination of grade efficiency curves by measuring the size distributions in the cyclone up- and downstream with optical particle counters. The extended experimental data from this parameter study were analysed by the methods of dimensional analysis and theory of models. An evaluation of all measuring results for two cyclone designs has been resulted in an empirical, nondimensional correlation of the collection characteristic, a dimensionless grade efficiency curve. Deviating from geometric similarity this correlation includes a variation of cyclone outlet diameter. Grade efficiencies of the cyclones are a definite function of the dimensionless numbers Stokes and Reynolds number and of the dimensionless cyclone outlet diameter. Analysis of own and published data has shown that this experimental correlation includes the influence of the temperature and that cyclone body diameter do not influence efficiency. The influence of cyclone height on flow behaviour and collection characteristic could be quantified as well. The range, in which prediction of collection efficiencies is possible, is marked in a state diagram Reynolds number versus dimensionless cyclone height.     

Etablierung einer nationalen Rohstoffbuchhaltung und dafür notwendige Informationen und Informationsgüte

The influence of anthropogenic processes on global material flow systems increasingly dominates the influence of natural processes. In this context, the provision of detailed knowledge on material flow systems is relevant for decision makers in resource policy. This information can be provided in the form of one-year material balances or, if repeated over a period of consecutive years, in the form of national resource budgets. In national resource budgets, all relevant flows of a material through a national economy are balanced and displayed in neatly arranged diagrams. By updating these material balances over a series of years, the development of material stocks can be estimated. Upcoming challenges both regarding supply and disposal of materials can be identified. Comprehensive balances are useful for decision makers in resource policy and, moreover, as an information basis for future exploitation of anthropogenic resources. However, both availability of data and possibilities for assessing the reliability of data are very limited. In this work, a methodology for investigating and evaluating the information basis of national resource budgets is presented. The methodology includes procedures for systematic characterization of resource budget data and formal procedures for evaluating their reliability. From a scientific perspective, the methodology contributes to understanding material flow systems better. It also enables implementing procedures towards national resource budgets in an administrative context.     

Anteil erneuerbarer Energien und klimarelevante CO2-Emissionen aus der thermischen Verwertung von Abfällen in Österreich

Since combustible wastes usually consist of biogenic (e.g. paper, wood, food waste) and fossil organic matter (plastics), their thermal recovery results in climate neutral and climate relevant CO₂ emissions. Moreover, the fraction of biogenic materials in the waste feed is relevant for the amount of renewable energy produced. The latter has to be reported and might be subsidized according to national laws (e.g. based on European directive 2009/28/EG). The present study represents the first comprehensive evaluation of the share of biogenic and fossil materials in the waste feed of waste-to-energy (WTE) plants on a national basis. The Balance Method, which is patented on a European level by TU Wien, was applied to 10 out of 13 Austrian WTE plants (around 2.3 Mio tons of waste corresponding to around 88 % of the overall waste feed in Austrian WTE plants). The method is based on the mathematical reconciliation of the material properties (e.g. mean chemical composition of biogenic and fossil materials) and routinely recorded operating data of WTE plants (e.g. flue gas volume, CO₂ and O₂-content in the dry flue gas, steam production). The results demonstrate large variations for the share of energy from biogenic sources in the different WTE plants, ranging from 35.7 ± 2.4 % to 61.2 ± 2.7 % (based on annual averages). Additionally, for several WTE plants large temporal variations can be observed based on monthly mean values. Thus, a plant-specific and continuous evaluation of the waste composition in WTE plants (which the Balance Method allows to do at reasonable efforts) can be recommended for a reliable reporting of the renewable share of energy or fossil CO₂ emissions from waste incineration. The energy input which stems from fossil and biogenic sources can be estimated to 11,450 ± 120 TJ and 10,730 ± 110 TJ, respectively for the year 2014 (for the 10 WTE plants). In total 1060 ± 24 kt fossil CO₂ emissions from the thermal recovery of waste in Austria’s WTE plants in 2014 could be determined (estimation for all 13 WTE plants).     

Innovative Methoden zum Geschiebemonitoring am Beispiel der Donau

In this article, new and innovative methods for bedload transport monitoring and their application in the context of a restoration project on the Danube River are described. Using an adapted basket sampler, a first comprehensive monitoring campaign for measuring bedload transport on the Danube was conducted and the temporal and spatial variability was shown. The development of a methodology for tracing artificial pebbles made it possible to track 40 pebble tracers of three different sizes on the Danube over the course of an entire year. Combining the two methods it could be determined that bedload already moves at low flow conditions and that bedload transport only increases slightly or even remains constant after reaching bank-full discharge. The tracer study identified size-selective transport ?C larger sizes were moving less often and over shorter distances than smaller sizes ?C with a mean transport distance of 3?km per year for the current bed material at Bad Deutsch-Altenburg. Detailed bathymetry and the analysis of the layer succession of the riverbed using the Freeze Core methodology complemented the other insights into the processes of sediment transport on the Danube River. These methods successfully characterized gravel sheets and allowed us to make predictive statements about bed armoring. We were also able to confirm a mean bed degradation of 2?cm per year using a combination of methods.     

Innovationen in der Modellierung von Sedimenttransport und Morphodynamik basierend auf dem Simulationsmodell iSed

This work presents recent developments in the simulation of sediment transport and morphodynamics on the basis of the simulation model iSed, which was developed at the University of Natural Resources and Life Sciences, Vienna. The computer model is coupled with external hydrodynamic models to obtain the flow field as the basis for the simulation of sediment transport processes. The paper first defines the physical processes that must be captured by a model as well as their underlying equations. Thereafter the general model validation based on data from a laboratory flume with a 180° bend under unsteady flow conditions is shown, a model that has also been applied to study a section of the Danube River east of Vienna. The calculated bedload transport rates as well as their spatio-temporal variability showed a very good agreement with measurement data. Moreover the model allowed for the first time a successful simulation of the bed forms present in the Danube as well as their downstream movement. In order to achieve this, non-uniform calculations including grain sorting, as well as detailed field measurement data for the model setup and calibration, constitute essential prerequisites.     

Water quality in the southern Tibetan Plateau: chemical evaluation of the Yarlung Tsangpo (Brahmaputra)

Yarlung Tsangpo (Brahmaputra) is the largest river system draining the northern slopes of the Himalayan ranges on the southern Tibetan Plateau. It remains one of only two large non‐regulated rivers in China. In this paper the chemical composition of Yarlung Tsangpo and its major tributaries (Raga Tsangpo, Nyangchu and Lhasa River) are studied. Water samples (n = 55) were collected and measured for major ions, trace elements and nutrients in order to: (1) define the present chemical quality of this water course; (2) address possible mechanisms governing the water chemical compositions, and (3) identify potential sources for contaminants. Multivariable analysis shows that geology and climate are the major explanatory variables for the spatial variation in water chemistry in this river system. In general, water chemistry is mainly controlled by carbonate weathering, with Ca²⁺ and HCO being the dominant ions. In addition, runoff from brackish/saline lakes and geothermal waters, enriched in Na⁺, Cl^?, SO, Mg²⁺ and Li, are major contributors of elevated concentrations of these solutes in the headwater regions resulting in a relatively high loading of total dissolved solids (TDS, 146–397 mg L^?1). Levels of most heavy metals and total dissolved nutrients were generally found to be low. However, elevated As concentration (avg. 95 μg L^?1) in the headwaters and additions from untreated wastewater were evident at some locations. Copyright © 2009 John Wiley & Sons, Ltd.