Verkleinerung verfahrenstechnischer Versuchsanlagen — was ist erreichbar?

Scale-down of chemical engineering pilot plant – what is attainable? The use of fully automated experimental laboratory-scale plantoffer interesting possibilities for assessment of the economic operation and technical feasibility of new or modified processes. An important condition for the success of this kind of experimental approach is the availability of miniaturized equipment, machines, and sensors. The goal of such experimental plant can be both the process engineering development of individual process steps and also integrated running to model complete processes. Moreover, questions of scale-up can be studied and typical quantities can be provided. The state of the art is reported with the aid of selected examples of equipment and mechanical components and measurement and control units.     

Simultaneous measurement of weight loss by DTG combustion and SO2-formation for different coals

Burning profiles and SO₂-formation profiles were measured simultaneously for four different coals by slowly heating coal samples in a flow of air in a thermobalance. The profiles of weight loss and SO₂ formation have the same shape with anthracite combustion. The SO₂-formation profiles of bituminous coals usually display two peaks that approximately correspond to the release of volatile matter and combustion of char in the burning profiles. No correlations could be found between either the types of sulphur present in the raw coals or the ratio of volatile matter to fixed carbon and the shape of the SO₂-formation profiles for the bituminous coals.     

A High Legume Low Glycemic Index Diet Improves Serum Lipid Profiles in Men

Clinical studies have shown that fiber consumption facilitates weight loss and improves lipid profiles; however, the beneficial effects of high fermentable fiber low glycemic index (GI) diets under conditions of weight maintenance are unclear. In the Legume Inflammation Feeding Experiment, a randomized controlled cross-over feeding study, 64 middle-aged men who had undergone colonoscopies within the previous 2 years received both a healthy American (HA) diet (no legume consumption, fiber consumption = 9 g/1,000 kcal, and GI = 69) and a legume enriched (1.5 servings/1,000 kcal), high fiber (21 g/1,000 kcal), low GI (GI = 38) diet (LG) in random order. Diets were isocaloric and controlled for macronutrients including saturated fat; they were consumed each for 4 weeks with a 2–4 week break separating dietary treatments. Compared to the HA diet, the LG diet led to greater declines in both fasting serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) (P < 0.001 and P < 0.01, respectively). Insulin-resistant (IR) subjects had greater reductions in high density lipoprotein cholesterol (HDL-C; P < 0.01), and triglycerides (TAG)/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. Insulin-sensitive (IS) subjects had greater reductions in TC (P < 0.001), LDL-C (P < 0.01), TC/HDL-C (P < 0.01), and LDL-C/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. In conclusion, a high legume, high fiber, low GI diet improves serum lipid profiles in men, compared to a healthy American diet. However, IR individuals do not achieve the full benefits of the same diet on cardiovascular disease (CVD) lipid risk factors.     

Lithological and pedological influences on the magnetic susceptibility of soil: their consideration in magnetic pollution mapping

Magnetic susceptibility measurements are widely used to map and monitor the heavy metal pollution of soils. However, the magnetic properties of soils are influenced significantly by the bedrock lithology and soil-forming processes. Therefore, a main challenge in the data interpretation is to filter out the anthropogenic pollution signal. In this study we address this problem by analysing susceptibility values, heavy metal concentrations, as well as pedological parameters in a large soil data set from the eastern segment of Austria, covering a wide range of different lithologies and soil types. The statistic assessment demonstrates an influence of lithology and soil type on the magnetic susceptibility signal. Therefore anomalies are defined in sub sets of different soil types separately. Three different methods were applied to detect susceptibility anomalies: the median absolute deviation method, the boxplot method, and the population modelling method. These methods evaluate topsoil data only and can therefore also be applied to field measurements of magnetic susceptibility. The results were compared to the conventional method of calculating the difference of topsoil and subsoil susceptibility. All three approaches identify the main anomalies in the study area and are successful in circumventing the problem of erroneous anomaly definition due to pedological processes. However, knowledge of the lithological background is still necessary for a meaningful interpretation and can only be substituted by a large amount of data. The tested methods lead to thresholds of different height and therefore act as filters of different strength for the definition of anomalies.     

Plasmonic dimer antennas for surface enhanced Raman scattering

Electron beam induced deposition (EBID) has recently been developed into a method to directly write optically active three-dimensional nanostructures. For this purpose a metal-organic precursor gas (here dimethyl-gold(III)-acetylacetonate) is introduced into the vacuum chamber of a scanning electron microscope where it is cracked by the focused electron beam. Upon cracking the aforementioned precursor gas, 3D deposits are realized, consisting of gold nanocrystals embedded in a carbonaceous matrix. The carbon content in the deposits hinders direct plasmonic applications. However, it is possible to activate the deposited nanostructures for plasmonics by coating the EBID structures with a continuous silver layer of a few nanometers thickness. Within this silver layer collective motions of the free electron gas can be excited. In this way, EBID structures with their intriguing precision at the nanoscale have been arranged in arrays of free-standing dimer antenna structures with nanometer sized gaps between the antennas that face each other with an angle of 90°. These dimer antenna ensembles can constitute a reproducibly manufacturable substrate for exploiting the surface enhanced Raman effect (SERS). The achieved SERS enhancement factors are of the order of 10? for the incident laser light polarized along the dimer axes. To prove the signal enhancement in a Raman experiment we used the dye methyl violet as a robust test molecule. In future applications the thickness of such a silver layer on the dimer antennas can easily be varied for tuning the plasmonic resonances of the SERS substrate to match the resonance structure of the analytes to be detected.     

A Note on the Energy Norm for a Singularly Perturbed Model Problem

This paper considers a singularly perturbed reaction diffusion problem. It is investigated whether adaptive approaches are successful to design robust solution procedures. A key ingredient is the a posteriori error estimator. Since robust and mathematically analysed error estimation is possible in the energy norm, the focus is on this choice of norm and its implications. The numerical performance for several model problems confirms that the proposed adaptive algorithm (in conjunction with an energy norm error estimator) produces optimal results. Hence the energy norm is suitable for the purpose considered here. The investigations also provide valuable justification for forthcoming research. Received October 25, 2001; revised July 12, 2002 Published online: October 24, 2002     

In situ Characterization of SiO2 Nanoparticle Biointeractions Using BrightSilica

By adding a gold core to silica nanoparticles (BrightSilica), silica‐like nanoparticles are generated that, unlike unmodified silica nanoparticles, provide three types of complementary information to investigate the silica nano‐biointeraction inside eukaryotic cells in situ. Firstly, organic molecules in proximity of and penetrating into the silica shell in live cells are monitored by surface‐enhanced Raman scattering (SERS). The SERS data show interaction of the hybrid silica particles with tyrosine, cysteine and phenylalanine side chains of adsorbed proteins. Composition of the biomolecular corona of BrightSilica nanoparticles differs in fibroblast and macrophage cells. Secondly, quantification of the BrightSilica nanoparticles using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) micromapping indicates a different interaction of silica nanoparticles compared to gold nanoparticles under the same experimental conditions. Thirdly, the metal cores allow the investigation of particle distribution and interaction in the cellular ultrastructure by cryo nanoscale X‐ray tomography (cryo‐XT). In 3D reconstructions the assumption is confirmed that BrightSilica nanoparticles enter cells by an endocytotic mechanism. The high SERS intensities are explained by the beneficial plasmonic properties due to agglomeration of BrightSilica. The results have implications for the development of multi‐modal qualitative and quantitative characterization in comparative nanotoxicology and bionanotechnology.     

Gas transport through ceramic membranes under super-critical conditions

In order to select and to apply a porous membrane under supercritical conditions, it is necessary to understand the transport mechanism affecting the permeation behaviour.This paper describes the investigation of gas transport through micro porous ceramic membranes consisting of several layers. The separation layer is made from TiO² with a nominal pore size diameter of 0.9 nm. Single gas permeation of helium, nitrogen, argon, methane, and carbon dioxide was measured in the temperature range of 293-443 K and in the pressure range of 1-10 MPa.Observation of the permeability of these membranes revealed that the transport of non?adsorbing gases under these conditions is governed by Knudsen diffusion and viscous flow.     

Investigations of silica scaling on reverse osmosis membranes

In reverse osmosis systems with high silica water severe and irreversible membrane scaling can be observed. But suitable test methods to find an appropriate antiscalant agent and the optimal dosage are missing. Usually only the silicate concentration in the feed water is regarded.In this paper the results of laboratory experiments about the influence of Ca²⁺- and Mg²⁺-ions on the behaviour of supersaturated solutions of silica in different test waters are discussed first. After that the new developed membrane-based test method to determine the effectiveness of antiscalants is presented.The applied different methods of analysis enabled the differentiation of three groups of silicates: ‘monomeric’, ‘polymeric’ and ‘filterable’.With the test method the strong impact of silicate scaling was proven, even if only small amounts of scale had been formed. It could be shown, that the ‘polymeric silica’ is mainly responsible for the membrane scaling. The kinetic of the formation of ‘polymeric silica’ is strongly influenced by the cations and the pH-value. It could be demonstrated that the use of a suitable antiscalant makes it possible to operate the plant at significantly higher recovery rates.