Bioraffinerien auf Basis schwach verholzter Biomasse

Weakly lignified biomass, like brewers' spent grain and grass silage, is good feedstock for biorefineries. The biomass can be separated and converted into valuable products in different ways. In this study, brewers' spent grain is used to investigate solid state fermentations with Cellulomonas uda. Additionally, hydrothermal pretreatment and subsequent enzymatic saccharification, as well as formation of inhibitory compounds, is demonstrated. Hydrothermal pretreatment combined with simultaneous saccharification and fermentation is shown as an example for the utilization of grass silage.     

Dissolution,Transport and Reaction at a DICY/DGEBA Interface

The curing of an epoxy consisting of the solid hardener dicyandiamide (DICY) and the resin diglycidyl ether of bisphenol A (DGEBA) is studied in a system consisting of a tablet of DICY embedded in liquid DGEBA. Dissolution of DICY within the liquid DGEBA in combination with the transport of dissolved DICY from the tablet border into DGEBA and the chemical reaction of both reactants is studied by scanning Brillouin microscopy and infrared spectroscopy. Scanning Brillouin microscopy demonstrates the spatial and temporal evolution of the static and dynamic hypersonic properties in the course of curing in the vicinity of the DICY tablet. Infrared spectroscopy performed on epoxy pieces extracted from the final sample at different distances from the tablet surface give information about the spatial evolution of the curing process. The results achieved by both techniques are finally combined to yield a better understanding of the curing of DICY-based epoxies, which transform upon curing from strongly heterogeneous systems towards increasingly homogeneous systems.     

Extraction of heavy metals from soils using biodegradable chelating agents

Metal pollution of soils is widespread across the globe, and the clean up of these soils is a difficulttask. One possible remediation technique is ex-situ soil washing using chelating agents. Ethylenediaminetetraacetic acid (EDTA) is a very effective chelating agent for this purpose but has the disadvantage that it is quite persistent in the environment due to its low biodegradability. The aim of our work was to investigate the biodegradable chelating agents [S,S]-ethylenediaminedisuccinic acid (EDDS), iminodisuccinic acid (IDSA), methylglycine diacetic acid (MGDA), and nitrilotriacetic acid (NTA) as potential alternatives and compare them with EDTA for effectiveness. Kinetic experiments showed for all metals and soils that 24 h was the optimum extraction time. Longer times only gave minor additional benefits for heavy metal extraction but an unwanted increase in iron mobilization. For Cu at pH 7, the order of the extraction efficiency for equimolar ratios of chelating agent to metal was EDDS > NTA> IDSA > MGDA > EDTA and for Zn it was NTA > EDDS > EDTA >MGDA > IDSA. The comparatively low efficiency of EDTA resulted from competition between the heavy metals and co-extracted Ca. For Pb the order of extraction was EDTA > NTA >EDDS due to the much stronger complexation of Pb by EDTA compared to EDDS. At higher concentration of complexing agent, less difference between the agents was found and less pH dependence. There was an increase in heavy metal extraction with decreasing pH, but this was offset by an increase in Ca and Fe extraction. In sequential extractions EDDS extracted metals almost exclusively from the exchangeable, mobile, and Mn-oxide fractions. We conclude that the extraction with EDDS at pH 7 showed the best compromise between extraction efficiency for Cu, Zn, and Pb and loss of Ca and Fe from the soil.     

Short communication: Evaluation of an automated in-house hematology analyzer for bovine blood

The objective of this study was to evaluate the suitability of the V-Sight hematology analyzer (A. Menarini Pharma GmbH, Vienna, Austria) for bovine blood by a comparison with a reference device (Advia 2120i, Siemens AG, Erlangen, Germany). In total, 97 blood samples were obtained from 75 dairy cows. Analyzed parameters included counts of white blood cells (WBC), lymphocytes, monocytes, granulocytes, red blood cells (RBC), and platelets (PLT), as well as hemoglobin concentration (HGB), hematocrit (HCT), mean corpuscular volume, mean corpuscular hemoglobin (MCH), MCH concentration (MCHC), mean platelet volume (MPV), and plateletcrit (PCT). Based on Passing-Bablok regression, the V-Sight provided accurate and precise results for MCH and MCHC only. The PCT results were comparable to the reference method, but precision was inconclusive. Significant proportional differences were detected for monocytes, granulocytes, HCT, and PLT. For all other analytes, significant proportional and systemic differences were observed. The WBC and lymphocyte results from the V-Sight were characterized by poor accuracy, poor precision, and a high number of false positive outliers. Bland-Altman analysis indicated negative biases for all WBC parameters, the erythrocyte indices, and PLT. Positive biases were observed for RBC, HGB, HCT, MPV, and PCT. Correlation coefficients of >0.9 between the V-Sight and the reference method were found only for RBC, HGB, HCT, and MPV. Intraassay precision of the V-Sight analyzer was acceptable (coefficient of variation <5%) for granulocytes, the erythrocyte indices, and MPV. It was unacceptable (coefficient of variation ≥5%) for WBC, lymphocytes, monocytes, as well as RBC, and inconclusive for HGB, HCT, PLT, and PCT. Sensitivity was high for all RBC counts and indices as well as PLT, but low for monocytes, granulocytes, and MPV. Specificity was high for monocytes and granulocytes, but low for RBC, HCT, MCH, and MCHC. With accurate and precise results for only 2 out of 13 parameters, the V-Sight cannot be recommended for analysis of bovine blood.     

Zur Kenntnis des thermoplastischen Verhaltens von Holz

Ohne Zusammenfassung Mitteilung aus der Bundesanstalt für Forst- und Holzwirtschaft, Reinbek bei Hamburg.     

Assessment of alimentary histamine exposure of consumers in Austria and development of tolerable levels in typical foods

Although alimentary intake of histamine can cause intoxication, legal limits for histamine content in the EU, exist for certain seafish species only. The present study suggests tolerable levels for fermented sausage, fish and cheese which are based on relating the amount of histamine not expected to cause any health effects after ingestion to typically consumed amounts of food. Limits of 500 and 400 mg/kg would seem to be justifiable for fermented sausage and cheese, respectively. For fish species other than those already regulated in EU, the “m”/”M” limits of 100 and 200 mg/kg can be adopted. These limits can be met by current food technology.     

Atomic Friction Investigations on Ordered Superstructures

We review recent friction measurements on ordered superstructures performed by atomic force microscopy. In particular, we consider ultrathin KBr films on NaCl(001) and Cu(001) surfaces, single and bilayer graphene on SiC(0001), and the herringbone reconstruction of Au(111). Atomically resolved friction images of these systems show periodic features spanning across several unit cells. Although the physical mechanisms responsible for the formation of these superstructures are quite different, the experimental results can be interpreted within the same phenomenological framework. A comparison between experiments and modeling shows that, in the cases of KBr films on NaCl(001) and of graphene films, the tip-surface interaction is well described by a potential with the periodicity of the substrate which is modulated or, respectively, superimposed with a potential with the symmetry of the superstructure.     

Optimal sensor placement for joint parameter and state estimation problems in large-scale dynamical systems with applications to thermo-mechanics

We consider large-scale dynamical systems in which both the initial state and some parameters are unknown. These unknown quantities must be estimated from partial state observations over a time window. A data assimilation framework is applied for this purpose. Specifically, we focus on large-scale linear systems with multiplicative parameter-state coupling as they arise in the discretization of parametric linear time-dependent partial differential equations. Another feature of our work is the presence of a quantity of interest different from the unknown parameters, which is to be estimated based on the available data. In this setting, we employ a simplicial decomposition algorithm for an optimal sensor placement and set forth formulae for the efficient evaluation of all required quantities. As a guiding example, we consider a thermo-mechanical PDE system with the temperature constituting the system state and the induced displacement at a certain reference point as the quantity of interest.     

Thermodynamic models for vapor-liquid equilibria of nitrogen + oxygen + carbon dioxide at low temperatures

For the design and optimization of CO₂ recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry’s law constants, are proposed for the ternary mixture N₂ + O₂ + CO₂. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry’s law constants of N₂ and O₂ in CO₂ are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry’s law constants, is developed to reliably describe the VLE in the CO₂-rich region.     

Fabrikation und Anwendung von metallischen Schichtverbundwerkstoffen

Through a clever combination of different materials, tailor-made composite materials can be fabricated which are able to fulfil high requirements often set by modern applications. Laminated composites of materials with different yield strengths, promising due to their damage tolerance, are discussed, and selected manufacturing methods suited for their production are presented. Utilizing the press bonding method, Ferrite/Martensite composites with 7 and 13 layers were manufactured and the influence of geometry and friction was assessed by layer thickness measurements. It could be shown that the gradient in degree of deformation inherent to the process can be reduced by lubrication, which results in improved parallelism and more even bond strengths.