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Nanotubular tobacco mosaic virus (TMV) particles and RNA-free lower-order coat protein (CP) aggregates have been employed as enzyme carriers in different diagnostic layouts and compared for their influence on biosensor performance. In the following, we describe a label-free electrochemical biosensor for improved glucose detection by use of TMV adapters and the enzyme glucose oxidase (GOD). A specific and efficient immobilization of streptavidin-conjugated GOD ([SA]-GOD) complexes on biotinylated TMV nanotubes or CP aggregates was achieved via bioaffinity binding. Glucose sensors with adsorptively immobilized [SA]-GOD, and with [SA]-GOD cross-linked with glutardialdehyde, respectively, were tested in parallel on the same sensor chip. Comparison of these sensors revealed that TMV adapters enhanced the amperometric glucose detection remarkably, conveying highest sensitivity, an extended linear detection range and fastest response times. These results underline a great potential of an integration of virus/biomolecule hybrids with electronic transducers for applications in biosensorics and biochips. Here, we describe the fabrication and use of amperometric sensor chips combining an array of circular Pt electrodes, their loading with GOD-modified TMV nanotubes (and other GOD immobilization methods), and the subsequent investigations of the sensor performance.
The conjunction of (bio-)chemical recognition elements with nanoscale biological building blocks such as virus particles is considered as a very promising strategy for the creation of biohybrids opening novel opportunities for label-free biosensing. This work presents a new approach for the development of biosensors using tobacco mosaic virus (TMV) nanotubes or coat proteins (CPs) as enzyme nanocarriers. Sensor chips combining an array of Pt electrodes loaded with glucose oxidase (GOD)-modified TMV nanotubes or CP aggregates were used for amperometric detection of glucose as a model system for the first time. The presence of TMV nanotubes or CPs on the sensor surface allows binding of a high amount of precisely positioned enzymes without substantial loss of their activity, and may also ensure accessibility of their active centers for analyte molecules. Specific and efficient immobilization of streptavidin-conjugated GOD ([SA]-GOD) complexes on biotinylated TMV nanotubes or CPs was achieved via bioaffinity binding. These layouts were tested in parallel with glucose sensors with adsorptively immobilized [SA]-GOD, as well as [SA]-GOD crosslinked with glutardialdehyde, and came out to exhibit superior sensor performance. The achieved results underline a great potential of an integration of virus/biomolecule hybrids with electronic transducers for future applications in biosensorics and biochips.
Tool supported requirements analysis for the user centered development of mobile enterprise software
(2008)
A user centered development method has proved satisfactory for the development of mobile enterprise software. To make use of this method, detailed information about the user and the place where the user interacts with his mobile device is required. This article describes how both can be modeled by a stereotypical and conceptual extended UML extension. Finally, a software tool is presented that supports the developed UML extension.
Von Zeichentisch und Letraset zu inhaltsbasierter Füllung und OpenType – wie sich die Werkzeuge des Grafikdesigns entwickelt und die Gestaltungsprozesse beeinflusst haben. Die Bachelorarbeit „Toolbar: Werkzeuge des Grafikdesigns“ setzt sich mit der eigenen Disziplin, dem Grafikdesign, auseinander und geht dabei seinen Wurzeln, den Werkzeugen, nach. Im Rahmen dessen werden in Gesprächen mit verschiedenen Gestalter*innen Tools und Technologien des Grafikdesigns untersucht und verglichen – angefangen vom analogen Paste-Up bis hin zu modernen Designmethoden. Dabei wird diskutiert, wie sich die Werkzeuge im Laufe der Zeit entwickelt haben und welche Auswirkungen dies auf das Grafikdesign und die Positionierung von Designer*innen hatte. Außerdem wird die Bedeutung von Werkzeugen im kreativen Prozess und ihre Auswirkungen auf die Gestaltung hinterfragt und aufgezeigt.
TOP-Energy : softwaregestützte Analyse und Optimierung industrieller Energieversorgungssysteme
(2004)
"The invention relates to a pot spinning device (1) comprising a thread guide (9) which can be moved backwards and forwards and introduced into an opening (8) on the end side of the pot (7) so as to deposit a thread on the inside wall of a spinning pot. In order to improve upon pot spinning devices of this kind, the spinning pot is connected to an electric drive mechanism (10), mounted in magnetic bearings and provided with a gastight housing. Said housing encompasses the spinning pot (7), is open in the area where there is an opening in the end side of the pot and is provided with a seal (19) to seal off the intermediate area (17) between the housing and spinning pot. The housing is also connected to a supply of light-gas via a feed line (18), thereby enabling a light-gas atmosphere to be maintained in the intermediate area."
This paper describes the implementation of topographic curvature effects within the RApid Mass MovementS (RAMMS) snow avalanche simulation toolbox. RAMMS is based on a model similar to shallow water equations with a Coulomb friction relation and the velocity dependent Voellmy drag. It is used for snow avalanche risk assessment in Switzerland. The snow avalanche simulation relies on back calculation of observed avalanches. The calibration of the friction parameters depends on characteristics of the avalanche track. The topographic curvature terms are not yet included in the above mentioned classical model. Here, we fundamentally improve this model by mathematically and physically including the topographic curvature effects. By decomposing the velocity dependent friction into a topography dependent term that accounts for a curvature enhancement in the Coulomb friction, and a topography independent contribution similar to the classical Voellmy drag, we construct a general curvature dependent frictional resistance, and thus propose new extended model equations. With three site-specific examples, we compare the apparent frictional resistance of the new approach, which includes topographic curvature effects, to the classical one. Our simulation results demonstrate substantial effects of the curvature on the flow dynamics e.g., the dynamic pressure distribution along the slope. The comparison of resistance coefficients between the two models demonstrates that the physically based extension presents an improvement to the classical approach. Furthermore a practical example highlights its influence on the pressure outline in the run out zone of the avalanche. Snow avalanche dynamics modeling natural terrain curvature centrifugal force friction coefficients.
Monitoring of organic acids (OA) and volatile fatty acids (VFA) is crucial for the control of anaerobic digestion. In case of unstable process conditions, an accumulation of these intermediates occurs. In the present work, two different enzyme-based biosensor arrays are combined and presented for facile electrochemical determination of several process-relevant analytes. Each biosensor utilizes a platinum sensor chip (14 × 14 mm²) with five individual working electrodes. The OA biosensor enables simultaneous measurement of ethanol, formate, d- and l-lactate, based on a bi-enzymatic detection principle. The second VFA biosensor provides an amperometric platform for quantification of acetate and propionate, mediated by oxidation of hydrogen peroxide. The cross-sensitivity of both biosensors toward potential interferents, typically present in fermentation samples, was investigated. The potential for practical application in complex media was successfully demonstrated in spiked sludge samples collected from three different biogas plants. Thereby, the results obtained by both of the biosensors were in good agreement to the applied reference measurements by photometry and gas chromatography, respectively. The proposed hybrid biosensor system was also used for long-term monitoring of a lab-scale biogas reactor (0.01 m³) for a period of 2 months. In combination with typically monitored parameters, such as gas quality, pH and FOS/TAC (volatile organic acids/total anorganic carbonate), the amperometric measurements of OA and VFA concentration could enhance the understanding of ongoing fermentation processes.
The metabolic activity of Chinese hamster ovary (CHO) cells was observed using a light-addressable potentiometric sensor (LAPS). The dependency toward different glucose concentrations (17–200 mM) follows a Michaelis–Menten kinetics trajectory with Kₘ = 32.8 mM, and the obtained Kₘ value in this experiment was compared with that found in literature. In addition, the pH shift induced by glucose metabolism of tumor cells transfected with the HPV-16 genome (C3 cells) was successfully observed. These results indicate the possibility to determine the tumor cells metabolism with a LAPS-based measurement device.
Sterilisation processes are compulsory in medicine, pharmacy, and food industries to prevent infections of consumers and microbiological contaminations of products. Monitoring the sterilisation by conventional microbiological methods is time- and lab-consuming. To overcome this problem, in this work a novel biosensor has been proposed. The sensor enables a fast method to evaluate sterilisation processes. By means of thin-film technology the sensor's transducer structures in form of IDEs (interdigitated electrodes) have been fabricated on a silicon substrate. Physical characterisation of the developed sensor was done by AFM, SEM, and profilometry. Impedance analyses were conducted for the electrical characterisation. As microbiological layer spores of B. atrophaeus have been immobilised on the sensing structure; spores of this type are a well-known sterilisation test organism. Impedance measurements at a fixed frequency over time were performed to monitor the immobilisation process. A sterilisation process according to aseptic filling machines was applied to demonstrate the sensor functionality. After both, immobilisation and sterilisation, a change in impedance could successfully be detected.