Empfehlungen des Arbeitskreises 6.1 “Geotechnik der Deponiebauwerke” der Deutschen Gesellschaft für Geotechnik e.V. (DGGT)

Der Arbeitskreis Geotechnik der Deponiebauwerke hat in fünf Themengruppen bisher 76 Empfehlungen zur Planung, zum Bau und zur Qualitätsüberwachung von Abfalldeponien veröffentlicht. In diesem Bericht werden zwei überarbeitungen vorgestellt, eine grundsätzliche Neubarbeitung der E 2‐4, Oberflächenabdichtungssysteme und die an neuere Erfahrungen angepasste E 2‐33, Kapillarsperren in Oberflächenabdichtungen. Recommendations of the DGGT Committee “Geotechnics of Landfill Structures”. The Technical Committee ”Geotechnics of Landfill Structures” of the German Geotechnical Society published up to now 76 recommendations (GDA‐Geotechnical Landfill Recommendations) structured in 5 main issues. This paper introduces two new editions of currently important recommendations, the fundamentally reviewed E 2‐4, Capping Systems, and a new edition of E 2‐33, Capillary Barriers in Landfill Capping Systems.     

Standsicherheitsnachweis für Oberflächenabdichtungssysteme von Deponien

Verification of slope stability of surface sealing systems of landfill structures. According to national and european standards slope stability of capping systems should be verified with the concept of partial safety factors. The revised german recommendation E 2‐7 “Analysis of planar surface failure in lining systems” of the TC “Geotechnics of Landfill Structures” requires design approach 3, where actions are treated as geotechnical actions and partial safety factors are applied to the shear resistance of the soil in the potential slip surfaces. The tension force of a geogrid in case of reinforcement should be designed according to this approach. The paper describes the different failure modes of rupture and excessive deformations, the fundamentals of the verification procedure with partial safety factors, the limit state conditions in infinite slope analysis of stratified final capping systems as well as the design of reinforced structures. Hence, central point of the analysis is less the method of calculation as rather the determination of the effective shear parameters, which can be mobilised for a long period of time considering changing conditions and material ageing effects in the contact plane of the system.     

Use of electron spin resonance for the determination of staling of roast coffee in polyethylene bag packs

Summary Arabica roasted beans packed in polyethylene bags were investigated at intervals by chemical analysis (acidity index) and by electron spin resonance (ESR) over a period of 30 days. The ESR measurements were repeated on the same samples after being exposed to air over a period of 30 days. Simultaneously, the acidity index of beans in an open bag was determined at regular intervals. ESR studies were also performed on ground beans, which were maintained in contact with air in two different containers. For all samples, the ESR intensity decreased as a function of time, whereas the acidity index increased simultaneously. The rate of change depended upon the treatment of the sample as well as on the storage time in the bag. On the basis of the ESR results an ageing velocity is defined, which allows for the quantification of the staling of roast coffee.

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Elektronenspinresonanz-Untersuchung des Alterungsprozesses von Röstkaffee in Polyäthylen-Verpackung

Zusammenfassung Kaffeebohnen der SorteArabica wurden unmittelbar nach der Röstung in Beuteln aus Polyäthylen verpackt. In Abständen von 30 Tagen wurde jeweils eine Packung geöffnet und der Säuregrad und die Elektronenspinresonanz (ESR) der Kaffeebohnen untersucht. Die ESR-Messungen wurden an den gleichen Proben nach 30 Tagen offener Lagerung wiederholt. Außerdem wurde in regelmäßigen Intervallen der Säuregrad von Bohnen aus der zuerst geöffneten Packung bestimmt. ESR-Untersuchungen erfolgten auch an gemahlenen Kaffeebohnen, die in verschieden großen offenen Behältern gelagert wurden. Bei allen Proben wird eine Abnahme der ESR-Signalintensität mit der Zeit beobachtet, die mit einer Zunahme des Säuregrades verbunden ist. Die Änderungsrate hängt sowohl von der Vorbehandlung der Proben, als auch von der Lagerungsdauer ab. Auf der Basis der ESR-Ergebnisse wird eine Alterungsgeschwindigkeit definiert, die es erlaubt, den Alterungsprozeß des gerösteten Kaffees zu quantifizieren.

     

The influence of nanoadditives on surface, permeability and mechanical properties of self-organized organic–inorganic nanocomposite coatings

Transparent and colorless nanocomposite coatings were prepared from a hybrid organic–inorganic matrix and several inorganic nanofillers. The products are characterized by a high degree of self-assembling of the matrix which was prepared from an epoxy-functional organosilicon precursor and an oligomeric diamine. Unmodified and chemically modified montmorillonite, bentonite, laponite, and colloidal silica were used as nanofillers, differing in shape, size, and origin. The nanoadditive concentration in coatings was always 0.5 wt%. Solid-state NMR (¹³C and ²⁹Si CP/MAS) spectroscopy was used for estimation of polyaddition and polycondensation degree in the polymer matrix in order to evaluate its structure changes caused by interaction with the nanoadditives. The influence of the kind of additive on the dynamic mechanical properties, gas permeability, and surface properties (topography, roughness) is discussed.     

Synthesis of Cholesterol‐Substituted Glycopeptides for Tailor‐Made Glycocalyxification of Artificial Membrane Systems

Synthetic minimal membrane systems are extremely useful for better understanding of complex cellular structures and cell surface processes. We have developed a facile method for synthesis of cholesterylated peptides, each bearing a carbohydrate moiety and a fluorescent tag. The position of the cholesterol moiety on the peptide can be controlled by using a new Fmoc‐protected cholesterol‐triazole‐lysine group, which we constructed by means of solid‐phase peptide synthesis. We succeeded in integrating the glyco modules into giant unilamellar vesicles by electroformation or infusion in buffer solution. The glyco‐decorated liposomes were recognized by a lectin and had unique topological membrane features. In conclusion, this work is a proof of principle for the functionalization of artificial membranes with a primitive synthetic glycocalyx useful for studying carbohydrate–protein interactions on a simplified cell‐like membrane surface.     

Influence of cooking and microwave heating on microstructure and mechanical properties of transgenic potatoes

The transgenic potato clones of cultivar Irga with improved resistance to a necrotic strain of potato virus Y (PVY(N)) were subjected to heat treatment in order to determine their technological quality. The technological quality was determined on the basis of differences between mechanical properties of unmodified potato and transgenic clones during cooking and microwave heating. The compression test was applied in order to evaluate the mechanical resistance of raw, cooked and microwave-treated potatoes. Compression resistance was expressed by fracture stress F (kPa), fracture strain D (mm/mm), and Young modulus E (kPa). The differences in microstructure of potato tubers (unmodified and modified) were investigated using scanning electron microscopy (SEM). The observed differentiation in the mechanical properties of heat-treated potatoes was less connected with genetic modification but most of all with a kind of the process used. The heat processes caused a distinct decrease in mechanical resistance in all the examined tubers. However, the process of microwave heating resulted in more significant changes in mechanical properties of tubers than cooking. Deformation of parenchyma cells during cooking was directly connected with starch, gelatinisation and gel formation. Microwave heating affected significantly cellular water evaporation which resulted in intercellular failure, collapsing of cells, and limitation of starch gelatinisation.     

Lignin Chromophores,Part IV∗ Syntheses of 1,4-Diarylbuta-1,3-dienes∗∗

Hydroxy- and methoxy-substituted 1,4-diarylbuta-1,3-dienes, models for potential chromophores assumed to be present in residual lignins, have been prepared using Wittig, Knoevenagel and Perkin syntheses.

     

High-Molecular-Weight Polycyclic Aromatic Hydrocarbons in the Area and Vicinity of the Deza Chemical Plant,Czech Republic

Polycyclic aromatic hydrocarbons (PAHs) with molecular weight exceeding 278 amu were analyzed in air, water, and soils from the area and vicinity of the DEZA Chemical Plant (Vala w ské Mezi q í ) í, Czech Republic). Air and water were sampled using semipermeable membrane devices (SPMDs); grab sampling was applied for soils. Laser desorption/ionization-time-of-flight mass spectrometry (LDI-TOF MS) and liquid chromatography/ion trap mass spectrometry with atmospheric pressure chemical ionization (LC/APCI-ITMS) were employed for the quick assessment of PAH distribution and for the identification and quantification of some high-molecular-weight PAHs. Compounds with molecular mass up to 450 u were found. LDI-TOF mass spectra and selected LC/APCI-ITMS profiles (m/z 303, m/z 327, and m/z 351) were compared to identify potential source of contamination in this locality. High-molecular-weight PAHs were found in all environmental compartments in the area studied; their levels were quite high close to their source and decreased sharply with increasing distance from it.