An Intelligent Universal Virtual Laboratory (UVL)

The Universal Virtual Laboratory (UVL) is a realistic, real-time, electrical engineering virtual laboratory. The software developed targets individuals who do not have adequate mobility of their upper bodies to perform laboratory experiments. To provide a more realistic and enhanced learning experience, the users of the virtual laboratory are allowed the freedom to build and test a wide variety of realistic electrical circuits, and be able to perform curriculum-based experiments. Typically, this laboratory would accompany an introductory electrical circuits course sequence. The virtual laboratory also contains an intelligent lab assistant that can guide the student and answer student queries.     

First results on ion micro-tomography at LIPSION

At the nanoprobe LIPSION ion micro-tomography can be used to determine the 3D distribution information of a sample’s mass density and elemental composition. For ion micro-tomography the two analytical techniques scanning transmission ion microscopy tomography (STIM-T) and particle induced X-ray emission tomography (PIXE-T) are combined. The required data are collected in two consecutive series of measurements, during which the sample is rotated by 180°/360° in small steps. Because all ions have to traverse the sample, the upper limit of the sample size is given by the range of the ions in the material. The tomogram is obtained using the discrete image space reconstruction algorithm (DISRA) by Sakellariou (1997) [1]. This algorithm iteratively corrects a sketchy initial tomogram estimated from the experimental reconstruction – obtained by backprojection of filtered projections (BFP) – and an a priori elemental composition. The necessary correction factors are calculated comparing the reconstruction of the experimental data with the reconstruction of simulated data. For the simulated data sets of STIM projections and PIXE maps are computed from the tomogram. These data sets are proceeded with the BFP algorithm to get simulated reconstruction data. Using the DISRA for ion micro-tomography, one can benefit from the high resolution of STIM-T by transferring it to the elemental distribution given by PIXE-T. This article presents first results of this technique applied on a phantom at the LIPSION facility.     

Determination of free reduced and total glutathione in wheat flours by an isotope dilution assay

Summary An isotope dilution assay (IDA) for free reduced glutathione (GSH) and total glutathione (GSH, oxidised glutathione and protein-bound glutathione) was developed and its accuracy and sensitivity were established. The new method for GSH required extraction of flour samples with a buffer at pH 4.5 containingN-ethyl maleimide (NEMI) and¹⁴C-labelled S-(N-ethylsuccinimido) glutathione ([¹⁴C]GS-NEMI), purification of the labelled and unlabelled GS-NEMI by three Chromatographic steps and assay of the specific radioactivity of the GS-NEMI isolated. Total glutathione was assayed after reduction with dithioerythritpl. Applications of the IDA indicated that the levels of GSH (16–41 nmol/g) and total glutathione (170–185 nmol/g) were relatively low in flours with low ash contents, but increased with increasing extraction grade. The level of GSH was higher in a flour obtained from kernels that were ground in the absence of gaseous oxygen. Storage of flours reduced the GSH concentration. IDA of fractions obtained from flour showed that the extraction residue, mainly consisting of starch and glutelins, contained most of the bound glutathione.

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Bestimmung von freiem reduziertem und vom gesamten Glutathion in Weizenmehlen durch Isotopenverdünnungsanalyse

Zusammenfassung Eine Isotopenverdünnungsanalyse (IVA) wurde für das freie reduzierte (GSH) und das gesamte Glutathion (GSH, GSSG proteingebundenes Glutathion) entwickelt und auf seine Genauigkeit und Empfindlichkeit überprüft. Die neue Methode für GSH erfordert die Extraktion der Mehlprobe mit einem Puffer bei pH 4,5, der N-Ethylmaleinsäureimid (NEMI) und [¹⁴C]-GS-NEMI enthält, Reinigung des markierten und unmarkierten GS-NEMI durch drei chromatographische Schritte sowie die Bestimmung der spezifischen Radioaktivität von dem isolierten GS-NEMI. Das gesamte Glutathion wird nach Reduktion mit Dithioerythrit bestimmt. Anwendungen der IVA zeigten, daß die Konzentrationen von GSH (16 bis 41 nmol) und von gesamtem Glutathion (170 bis 185 nmol/g) relativ gering waren in Mehlen mit niedrigen Aschegehalten, aber daß sie mit steigendem Ausmahlungsgrad zunahmen. Die GSH-Konzentration war in einem Mehl höher, das aus Körnern stammte, die in Abwesenheit von Sauerstoff gemahlen worden waren. Die Lagerung von Mehlen erniedrigte den GSH-Gehalt. Die IVA von Mehlfraktionen zeigte, daß der Extraktionsrückstand, der hauptsächlich aus Stärke und Glutelinen bestand, das meiste gebundene Glutathion enthielt.

     

Higher order derivatives of Liapunov functions

The problem considered is that of inferring asymptotic stability by examining higher order derivatives of a Liapunov function when examination of only the first derivative does not permit such an inference. It is shown that a seemingly plausible approach using onlydot{V}andddot{V}is vacuous. It is also shown that it is possible to infer asymptotic stability by examiningdot{V}andddot{V}, and perhapsddot{V}.     

The tantalum hyperfine interaction in the charge density wave state of 2HTaS2

We report on the observation of the ¹⁸¹Ta nuclear quadrupole interaction in 2HTaS₂ in the temperature range from 5.5 K up to 453 K studied by time differential perturbed angular correlations. Our results for the charge density wave (CDW) state are at variance with all triple-ov|h?aruq CDW models and suggest a highly non harmonic electron density perturbation.     

Bemessungskonzept für fußgängerinduzierte Brückenschwingungen

Design concept for the analysis of pedestrian‐induced bridge vibration. Unexpected vibrations of footbridges, e.g. during inauguration of Millennium Bridge in London and Passerelle Solferino in Paris, have drawn engineers' attention to more accurate forecast models to determine pedestrian‐induced vibrations and especially pedestrian‐structure‐interaction of light and slightly damped footbridges in the design phase. This contribution presents a programme to simulate bridge vibrations with realistic ‘numerical pedestrians’, which is calibrated against measured response under real pedestrian loading. By means of this simulation tool observed vibrations and pedestrian‐structure‐interaction phenomena can be analysed. In a second step an engineering model based on a spectral approach is derived, which enables to determine characteristic pedestrian‐induced structural response. Hence, if necessary the design of the footbridge can be adjusted or damping measures can be planned to fulfill serviceability requirements. A design concept for the dynamic analysis of the reversible serviceability limit state, which fulfills the Eurocode requirements, is described and an innovative consideration and definition of comfort criteria are proposed.     

Fully Patterned Low‐Voltage Transparent Metal Oxide Transistors Deposited Solely by Chemical Spray Pyrolysis

All‐inorganic transparent thin‐film transistors deposited solely by the solution processing method of spray pyrolysis are reported. Different precursor materials are employed to create conducting and semiconducting species of ZnO acting as electrodes and active channel material, respectively, as well as zirconium oxide as gate dielectric layer. Additionally, a simple stencil mask system provides sufficient resolution to realize the necessary geometric patterns. As a result, fully functional low‐voltage n‐type transistors with a mobility of 0.18 cm² V^?1 s^?1 can be demonstrated via a technique that bears the potential for upscaling. A detailed microscopic evaluation of the channel region by electron diffraction, high‐resolution and analytical TEM confirms the layer stacking and provides detailed information on the chemical composition and nanocrystalline nature of the individual layers.     

Proton beam writing of microstructures in Agar gel for patterned cell growth

A rather useful prerequisite for many biological and biophysical studies, e.g., for cell-cell communication or neuronal networks, is confined cell growth on micro-structured surfaces. Solidified Agar layers have smooth surfaces which are electrically neutral and thus inhibit receptor binding and cell adhesion. For the first time, Agar microstructures have been manufactured using proton beam writing (PBW). In the irradiated Agar material the polysaccharides are split into oligosaccharides which can easily be washed off leaving Agar-free areas for cell adhesion. The beam diameter of 1 μm allows the fabrication of compartments accommodating single cells which are connected by micrometer-sized channels. Using the external beam the production process is very fast. Up to 50 Petri dishes can be produced per day which makes this technique very suitable for biological investigations which require large throughputs.