Comparison of the effectiveness of different silver-containing textile products on bacteria and human cells

This paper reports on the antibacterial properties of several silver-containing textile products commercially available in Europe. The antimicrobial properties are evaluated against two different types of bacteria, Escherichia coli and Staphylococcus aureus. In a similar experimental set-up, the toxicity of these textile products was also investigated against three different types of human leukocytes (Jurkat, MonoMac-1, and Epstein-Barr virus-transformed human B cells). The antimicrobial activity of the textiles commercialized as antimicrobial fabrics varies in a broad range; for some fabrics, no antimicrobial activity was detectable under the applied test conditions. For comparison, the effect of some fabrics against human cells was also investigated, finding that the ones with high bactericidal activity did also impair the viability of human cells.     

Elektrische Netzwerke aus Ohmwiderständen mit vorgeschriebenen äußeren Widerständen

Übersicht Für ein gegebenes Netzwerk, dasn Knoten und jeweils zwischen zwei Knoteni undk als Zweig den Ohm-Widerstandr _ik besitzt, kann man bekanntlich alle zwischen zwei Knoteni undk meßbaren äußeren WiderständeR _ik berechnen.In dieser Arbeit wird die umgekehrte Aufgabe behandelt: Vorgegeben seien alle äußeren WiderständeR _ik . Hieraus sollen alle Zweigwiderständer _ik des zugehörigen Netzwerks berechnet werden. Außerdem sind noch die Bedingungen anzugeben, denen die vorgeschriebenen äußeren WiderständeR _ik genügen müssen, damit sich das Netzwerk ausführen läßt.

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Electrical networks of ohmic resistances by given external resistances

Contents As is known, for a given network withn nodes, whose branches between two nodesi andk consist of ohmic resistancesr _ik we can determine all external resistancesR _ik measurable between two nodesi andk.This paper deals with the inverse problem: all external resistancesR _ik are given and in dependence of them the branch resistancesr _ik of the corresponding network will be determined. Furthermore some conditions will be specified, which have to be fullfilled by the given external resistancesR _ik in order to receive a realizable network.

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Zu meinem 80. Geburtstag haben meine beiden Nachfolger unter ehemaligen Schülern für ein Geburtstagsgeschenk eine Sammlung veranstaltet. Deren Ertrag — ergänzt durch einen Beitrag der Vereinigung der Freunde—wurde nach meinem Vorschlag für einen Wilhelm-Bader-Preis verwendet, den die Fakultät für Elektrotechnik der Universität Stuttgart für die Lösung einer von mir gestellten Aufgabe ausgelobt hat.Herrn Jürgen Haase wurde der erste Preis zuerkannt. Ich habe ihn veranlaßt, die von ihm eingereichte Lösung in freier Gestaltung für das AfE darzustellen. W. Bader, em. Ordinarius für Theorie der Elektrotechnik, Universität Stuttgart     

Evaluation of a Novel Thiol–Norbornene-Functionalized Gelatin Hydrogel for Bioprinting of Mesenchymal Stem Cells

Introduction: Three-dimensional bioprinting can be considered as an advancement of the classical tissue engineering concept. For bioprinting, cells have to be dispersed in hydrogels. Recently, a novel semi-synthetic thiolene hydrogel system based on norbornene-functionalized gelatin (GelNB) and thiolated gelatin (GelS) was described that resulted in the photoclick hydrogel GelNB/GelS. In this study, we evaluated the printability and biocompatibility of this hydrogel system towards adipose-tissue-derived mesenchymal stem cells (ASCs). Methods: GelNB/GelS was synthesized with three different crosslinking densities (low, medium and high), resulting in different mechanical properties with moduli of elasticity between 206 Pa and 1383 Pa. These hydrogels were tested for their biocompatibility towards ASCs in terms of their viability, proliferation and differentiation. The extrusion-based bioprinting of ASCs in GelNB/GelS-high was performed to manufacture three-dimensional cubic constructs. Results: All three hydrogels supported the viability, proliferation and chondrogenic differentiation of ASCs to a similar extent. The adipogenic differentiation of ASCs was better supported by the softer hydrogel (GelNB/GelS-low), whereas the osteogenic differentiation was more pronounced in the harder hydrogel (GelNB/GelS-high), indicating that the differentiation fate of ASCs can be influenced via the adaption of the mechanical properties of the GelNB/GelS system. After the ex vivo chondrogenic differentiation and subcutaneous implantation of the bioprinted construct into immunocompromised mice, the production of negatively charged sulfated proteoglycans could be observed with only minimal inflammatory signs in the implanted material. Conclusions: Our results indicate that the GelNB/GelS hydrogels are very well suited for the bioprinting of ASCs and may represent attractive hydrogels for subsequent in vivo tissue engineering applications.     

New Approach to High-Pressure Nuclear Magnetic Resonance with Anvil Cells

A novel approach that uses radio-frequency microcoils in the high-pressure region of anvil cells with Nuclear Magnetic Resonance (NMR) experiments is described. High-sensitivity Al NMR data at 70 kbar for Al metal are presented for the first time. An expected decrease in the Al Knight shift at 70 kbar is observed, as well as an unexpected change in the local charge symmetry at the Al nucleus. The latter is not predicted by chemical structure analysis under high pressure.     

Cardiovascular phenotype characterization in mice by high resolution magnetic resonance imaging

9. Conclusion Due to its high temporal and spatial resolution, magnetic resonance imaging meets the requirements for accurate and robust in vivo visualization of the murine cardiovascular system. As an intrinsically three-dimensional imaging technique, it allows for quantification of LV volumes without relying on geometric models. Therefore, MRI is uniquely suited for the investigation of morphologic and functional changes in models of heart failure. The potential application of MRI in the mouse comprises visualization of cardiovascular anatomy and pathology in newborn and adult mice, detection of LV geometric and functional changes both acutely and chronically, visualization of cardiac microstructures such as cardiac valves and coronary arteries, and characterization and quantification of arteriosclerotic plaques in major murine arteries. Furthermore, MR spectroscopy applied to the mouse heart can give important information on in vivo myocardial metabolism. Thus, we feel confident that high resolution MRI may substantially contribute to the understanding of the basic mechanisms of a variety of cardiovascular diseases.     

Magnetization transfer short inversion time inversion recovery enhanced 1H MRI of the human lung

The unique characteristics of the human lung arising from low proton density and multiple air-tissue interfaces of the alveoli cause difficulty in¹H lung magnetic resonance imaging. In addition, the dominating signal from sources such as the thoracic muscle and subcutaneous fat hampers the visualization of the lung parenchyma. In this contribution, an efficient tissue suppression technique is presented which allows one to significantly enhance lung parenchyma visibility. A short inversion time inversion recovery (STIR) experiment combined with a magnetization transfer (MT) experiment was used for magnetization preparation in order to suppress the signal from muscle. A half-Fourier single-shot turbo spin-echo sequence was used as acquisition module. This approach was used to perform lung anatomical imaging in eight healthy human subjects and five patients withcystic fibrosis. The results obtained demonstrate that with MT-STIR approach high quality human lung images can be obtained and that this approach has the potential for the evaluation of lung pathologies.     

Preprocessing for 2D FE–BE domain decomposition methods

The non-overlapping Domain Decomposition (DD) method is a powerful tool for the coupling of Finite Element (FE) and Boundary Element (BE) methods. Moreover it provides a natural basis for constructing efficient parallel solvers. However, both, the efficiency and the robustness of DD–solvers depends heavily on the underlying decomposition of the domain of interest into subdomains. In this paper, we introduce the Adaptive Domain Decomposition Preprocessor ADDPre which realizes an automatic decomposition of the computational domain into p subdomains, where p is the number of processors to be used. We discuss the codes being involved, the algorithms which they are based on and the data–formats being used for describing the decomposition of the problem. Numerical examples, demonstrating the performance of the preprocessor are presented. Received: 20 January 1999 / Accepted: 12 May 1999