Long-term stability of an Au/Al2O3 catalyst prepared by incipient wetness in continuous-flow glucose oxidation

A 0.3% Au/Al₂O₃ catalyst prepared by the incipient wetness (IW) method was investigated in the continuous-flow liquid-phase glucose oxidation. Therefore, a continuous stirred tank reactor (CSTR) system equipped with an ultrasonic separator was used. The continuous-flow glucose oxidation was carried out at 40 °C, pH 9 and 1 bar oxygen partial pressure. Residence time and glucose concentration were varied. The IW gold catalyst showed very high activity and selectivity to gluconic acid within its 110 days of operation and, thus, an excellent long-term stability. Even after severe microbial contaminations of the catalyst, its activity could be completely restored by in situ regeneration with 2-propanol.     

Influence of the preparation conditions on the properties of gold catalysts for the oxidation of glucose

In this work, two deposition–precipitation methods for the preparation of gold catalysts for glucose oxidation were investigated. Thus far, gold colloids immobilized on carbon have been used for catalytic glucose oxidation, but the long-term stability of these systems was not sufficient. To improve the long-term stability we used the deposition–precipitation methods using NaOH (DP NaOH) or urea (DP urea) as precipitation agents as they were described by Haruta and Dekkers, respectively, using alumina as a support material. With these methods, it was possible to prepare highly active and selective catalysts which showed an excellent long-term stability. DP urea was found to be the preferred method, because in contrast to DP NaOH, no losses of gold occurred during the preparation, and it was possible to adjust various gold contents up to 10 wt% Au.     

Comparing Control Constructs by Double-Barrelled CPS

We investigate call-by-value continuation-passing style transforms that pass two continuations. Altering a single variable in the translation of -abstraction gives rise to different control operators: first-class continuations; dynamic control; and (depending on a further choice of a variable) either the return statement of C; or Landin's J-operator. In each case there is an associated simple typing. For those constructs that allow upward continuations, the typing is classical, for the others it remains intuitionistic, giving a clean distinction independent of syntactic details. Moreover, those constructs that make the typing classical in the source of the CPS transform break the linearity of continuation use in the target.     

Fast and precise positioning of single cells on planar electrodesubstrates

For cell biosensors and for studying neural networks using planar electrode substrates, a suitable technique for positioning single cells on electrodes was needed. We reported a new method for fast and efficient positioning of single cells on ring electrodes by controlled suction through holes. We described the microfabrication of electrode substrates with microholes and the cell positioning procedure. L929 cells and Neuro 2A cells could be positioned in parallel without cell damage.     

Convergence of Broadcast and New Telecom Networks

The demand of the new telecom industry for cost efficient provision of mobile multimedia services is faced with the reality of scarce radio resources. The requirement of spectrum efficiency has driven the development of various digital radio technologies that have been optimized for specific services, namely for broadcast or for mobile communication. However, existing and emerging multimedia services exhibit challenging requirements in terms of asymmetry, interactivity, real-time, and multicast communication. This paper describes an IP based multi-radio infrastructure that enables the co-operation of existing radio networks to combine their capabilities to ensure a spectrum efficient provision of high-quality mobile multimedia services. Further the need for a dynamic allocation of spectrum to radio services is motivated. The basic functionality and the architecture of a multi-radio system is outlined, with a special emphasis on the cooperation between different radio systems. Further an evolution path for the convergence of broadcast and new telecom is desribed, starting from today's systems and leading to a fully coordinated system.     

Qualification of a precise and easy-to-handle sweat casting imprint method for the prediction and quantification of anti-perspirant efficacy

A time‐ and cost‐effective sweat casting method using the forearm as test site to assess the efficacy of several anti‐perspirant formulations with a low number of test subjects has been evaluated and qualified. The imprint sweat casting method is based on a 2‐component silcone‐imprint technique to measure the efficacy of more than eight products in parallel with the same test subject. In studies using aluminum chlorohydrate (ACH) formulations as test anti‐perspirants, a clear‐cut correlation could be demonstrated between sweat gland activities measured by the imprint method and gravimetric measurement of sweat gland activities. Concentration‐dependent inhibition of sweat gland activity could be observed with the imprint technique up to an ACH concentration of 15%, and all formulations containing 2% ACH or above resulted in statistically significant reduction of sweat gland activity (P < 0.001) when compared with untreated control areas. Furthermore, the SDs of individual studies using the imprint technique were in a range of ±20% of sweat gland activity, which can be regarded rather low for in vivo measurements of a complex process like sweat secretion. A group‐wise comparison between the measurements of anti‐perspirant activity as determined by the imprint protocol and the Food and Drug Administration (FDA) Guideline compliant gravimetric hot‐room protocol revealed that the test results for anti‐perspirant activity obtained with the imprint protocol are similar to those obtained with the hot‐room protocol. Moreover, the data generated with the imprint protocol have a high predictive value for the outcome of a later guideline‐compliant hot‐room test. As the imprint casting method tends to be a little more sensitive for formulations with low anti‐perspirant activity, and seems to be associated with less interassay variability than the standard gravimetric hot‐room test, the imprint casting method may select products which later fail to pass the standard gravimetric hot‐room test. Meanwhile the imprint sweat casting has proven to be a robust method useful to support efficacy‐oriented product development. Therefore, in later stages of utilization it might even evolve into an efficient claim substantiation tool.     

Biocompatible micro-sized cell culture chamber for the detection of nanoparticle-induced IL8 promoter activity on a small cell population

In most conventional in vitro toxicological assays, the response of a complete cell population is averaged, and therefore, single-cell responses are not detectable. Such averaging might result in misinterpretations when only individual cells within a population respond to a certain stimulus. Therefore, there is a need for non-invasive in vitro systems to verify the toxicity of nanoscale materials. In the present study, a micro-sized cell culture chamber with a silicon nitride membrane (0.16 mm²) was produced for cell cultivation and the detection of specific cell responses. The biocompatibility of the microcavity chip (MCC) was verified by studying adipogenic and neuronal differentiation. Thereafter, the suitability of the MCC to study the effects of nanoparticles on a small cell population was determined by using a green fluorescence protein-based reporter cell line. Interleukin-8 promoter (pIL8) induction, a marker of an inflammatory response, was used to monitor immune activation. The validation of the MCC-based method was performed using well-characterized gold and silver nanoparticles. The sensitivity of the new method was verified comparing the quantified pIL8 activation via MCC-based and standard techniques. The results proved the biocompatibility and the sensitivity of the microculture chamber, as well as a high optical quality due to the properties of Si₃N₄. The MCC-based method is suited for threshold- and time-dependent analysis of nanoparticle-induced IL8 promoter activity. This novel system can give dynamic information at the level of adherent single cells of a small cell population and presents a new non-invasive in vitro test method to assess the toxicity of nanomaterials and other compounds.PACS: 85.35.Be, 81.16.Nd, 87.18.Mp     

Characterisation of the deflection of thin perforated SiN membranes of micro-hole array chips used for the cell selection

An automated and reliable isolation of single cells is increasingly important for applications in the rapidly growing life science sector. Traditional methods, like limited dilution or cell-seeding in semi-solid media, are time-consuming, significantly limited by the number of clones that can be feasibly screened and not suitable for reliable generation of monoclonal cell lines. To enable a reliable isolation of single cell out of a high number of cells, a micro-hole array based fluidic system has been developed. Here single cells are positioned by using a suction pressure on the holes of a nitride membrane. The entrapped cells can be optically analysed and picked by a capillary system mounted on a micromanipulator. This picking process is working with small distances or contact between the capillary tip and the membrane of the micro-hole array chip. In this article the bending of the silicon nitride membrane is analysed in dependence of the applied suction pressure in order to know the resulting deflection offset (z-axis offset) at any position of the membrane. This enables a more reliable control of the picking procedure.     

Adaptive Herd- und Fahnencharakterisierung als Voraussetzung für einen effizienten Modellaufbau unter heterogenen Standortbedingungen

The Voigtl?nder camera production site in Braunschweig was operated until 1972. The facility??s use of chlorinated solvents for grease removal led to significant soil and groundwater contamination. The investigation and remediation methods that have been used at the site have not resulted in an acceptable level of remediation. Given the heterogeneous conditions, the site appears to be an excellent location for assessing the effectiveness of adaptive characterization strategies for investigations of contamination by chlorinated solvents. The Voigtl?nder source area no. V is being used as a demonstration site to assess the efficiency of different investigation and remediation methods under heterogeneous conditions. An iterative (adaptive) investigation process was conducted with sequential improvements based on increased site understanding. The lithologic and hydraulic features that could create potential migration pathways were identified, and the spatial extent of the contaminant body within the source area and, by means of control planes, within the plume was delineated. Related 2D and 3D images of the site model provide solid support for assessments of the relative effectiveness of various remediation alternatives.     

Inhibition by ethanol of noradrenaline output from peripheral sympathetic nerves: possible interaction of ethanol with neuronal receptors

The sympathetic nerve terminals of the isolated rabbit heart perfused with Tyrode solution were used to study the action of ethanol on the noradrenaline uptake and release. The uptake of exogenous noradrenaline (10 ng/ml) into the sympathetic nerve endings, the noradrenaline output evoked by raising the concentration of potassium ions in the perfusion fluid, and the release in response to electrical stimulation of the nerve axons were inhibited only by lethal concentrations of the alcohol; the concentrations which caused 50% inhibition (IC50) amounted to 760 mM, 830mM, and 1150 mM respectively. However, ethanol at concentrations compatible with moderate intoxication reduced the noradrenaline release in response to activation of the nicotine receptors on the nerve terminals by dimethylphenylpiperazine; the threshold concentration was 36 mM and the IC50 was 129 mM. It is suggested that this effect is due to hydrophobic interaction of the alcohol with receptor proteins, thus inhibiting stimulus formation.