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A new approach for a label-free electrical detection of DNA hybridization and denaturation using an array of individually addressable field-effect nanoplate SOI (silicon-on-insulator) capacitors functionalized with gold nanoparticles is presented. By using a constant-capacitance measuring setup in a differential mode, signal changes of ∼110 mV and ∼70 mV have been registered after the DNA hybridization and denaturation events, respectively.
Currently, most workflow management systems in Grid environments provide push-oriented job distribution strategies, where jobs are explicitly delegated to resources. In those scenarios the dedicated resources execute submitted jobs according to the request of a workflow engine or Grid wide scheduler. This approach has various limitations, particularly if human interactions should be integrated in workflow execution. To support human interactions with the benefit of enabling inter organizational computation and community approaches, this poster paper proposes the idea of a pull-based task distribution strategy. Here, heterogeneous resources, including human interaction, should actively select tasks for execution from a central repository. This leads to special demands regarding security issues like access control. In the established push-based job execution the resources are responsible for granting access to workflows and job initiators. In general this is done by access control lists, where users are explicitly mapped to local accounts according to their policies. In the pull-based approach the resources actively apply for job executions by sending requests to a central task repository. This means that every resource has to be able to authenticate against the repository to be authorized for task execution. In other words the authorization is relocated from the resources to the repository. The poster paper introduces current work regarding to the mentioned security aspects in the pull-based approach within the scope of the project “HiX4AGWS”.
The Newtonian regime of a recent nonlocal extension of general relativity is investigated. Nonlocality is introduced via a scalar “constitutive” kernel in a special case of the translational gauge theory of gravitation, namely, the teleparallel equivalent of general relativity. In this theory, the nonlocal aspect of gravity simulates dark matter. A nonlocal and nonlinear generalization of Poisson’s equation of Newtonian gravitation is presented. The implications of nonlocality for the gravitational physics in the solar system are briefly studied.
The development of new interfaces for (bio-)chemical sensors requires comprehensive analyses and testing. The light-addressable potentiometric sensor (LAPS) can be used as a platform to investigate the sensitivity of a newly developed interface towards (bio-)chemical agents. LAPS measurements are spatially resolved by utilisation of focused light beams to define individual measurement spots. In this work, a new digitally modulated LAPS set-up based on an FPGA design will be introduced to increase the number of measurement spots, to shorten the measurement time and to improve the measurement accuracy.
This paper develops an investment/pricing model for the deployment of basic broadband networks which, along with other applications, is applicable to public–private partnership projects. In particular, a new investment model is suggested to be used for finance deployment over a longer term by enabling both private and public investors to participate in the roll-out of next generation access (NGA) infrastructure. This so-called “long-term risk sharing concept” has several notable benefits compared with the traditional regulatory approach. Above all, the model enables both private operators and public authorities to share the risk of investing in NGA infrastructure. Thus the model offers a way for public authorities to achieve a timely and countrywide roll-out of NGA networks, including in areas where NGA investment would otherwise not occur.
In steps of the production chain of carbide inserts, such as unloading or packaging, the conformity test of the insert type is done manually, which causes a statistic increase of errors due to monotony and fatigue of the worker and the wide variety of the insert types. A machine vision system is introduced that captures digital frames of the inserts in the production line, analyses inspects automatically and measures four quality features: coating colour, edge radius, plate shape and chip-former geometry. This new method has been tested on several inserts of different types and has shown that the prevalent insert types can be inspected and robustly classified in real production environment and therefore improves the manufacturing automation.
The mission of the COMPASS-1 picosatellite is to take pictures of the earth, to validate a space-borne GPS receiver developed by the German Aerospace Center, and to verify the proper operation of the magnetic attitude control system in orbit. The spacecraft was launched on April 28, 2008 from the Indian space port Sriharikota, as part of the PSLV-C9 world record launch that simultaneously brought ten satellites into orbit. The mission operations were carried out from the ground stations in Aachen and Tainan. Arising difficulties in the communication link were overcome with the support of individuals from the amateur radio community. After several months of mission operation, abundant housekeeping and mission data has been commanded, received and analyzed and is presented in this paper.
A novel scheme for precise diagnostics and effective stabilization of currents in a fuel cell stack
(2010)
A novel scheme for detecting inhomogeneous internal currents in a fuel cell stack is presented. In this paper the scheme is investigated for the case that the flow field plates consist of graphite. Then plates of high conductivity, e.g. aluminium between the flow field plates together with small slits in these plates have three effects: (a) Whenever a local inhomogeneity of the electric current occurs at a particular cell in the stack, this will induce a surface current close to that cell perpendicular to the averaged current. This current can be detected. (b) The plates of high conductivity completely prevent the inhomogeneities from spreading to neighbouring cells. (c) Even at the particular cell the inhomogeneity is suppressed as far as possible. Thus this scheme leads to much better diagnostic possibilities and at the same time reduces electric instabilities to an extent, where they probably become harmless. This scheme will first be explained for a simple model to clarify the idea. However, very precise three dimensional computations using realistic parameters are presented, corroborating the results of the simple model.
A novel tomographic scheme for analysing the state of any single membrane electrode assembly (MEA) in a stack is suggested. Plates of very high conductivity placed between every fuel cell and slitted in an appropriate manner cause surface currents at well-defined locations of the stack. We show that knowing these surface currents, information about anomalies of the currents in a MEA can be obtained using the methods of tomography. The results are mathematically not unique. However, when assuming plausible defect structures, one can exclude improbable deficiencies by applying a special form of simulated annealing. We present numerical calculations of typical examples demonstrating that the essential defects of the MEA in any single cell of the stack can be detected and their extent can be determined.
Biomechanics studies biological soft tissue materials (growth, remodeling) in vivo. For this objective, the detailed information of material properties must be well defined to construct reliable constitutive models. In the paper, the bulge test is carried out with elastomers in order to develop a test method. Then, application of the test for soft tissue materials is straightforward due to the similarities between elastomers with soft tissue materials as proved in Holzapfel 2005, Ogden 2009. It means, after the preliminary experiments and parameter identification with rubber materials has been setup, experiments on soft tissue materials can be similarly carried out. Elastomers have a complex behavior which strongly depends on the largest previous load cycle. For simplicity we consider only the first loading.
Comparison of intravenous immunoglobulins for naturally occurring autoantibodies against amyloid-β
(2010)
Intravenous immunoglobulins (IVIG) are currently used for therapeutic purposes in autoimmune disorders. Recently, we demonstrated the presence of naturally occurring antibodies against amyloid- β (nAbs-Aβ) within the pool of IVIG. In this study, we compared different brands of IVIG for nAbs-Aβ and have found differences in the specificity of the nAbs-Aβ towards Aβ1–40 and Aβ1–42 . We analyzed the influence of a pH-shift over the course of antibody storage using ELISA and investigated antibody dimerization at acidic and neutral pH as well as differences in the IgG subclass distributions among the IVIG using both HPLC and a nephelometric assay. Furthermore, we investigated the epitope region of purified nAbs-Aβ. The differences found in Aβ specificity are not directly proportionate to the binding nature of these antibodies when administered in vivo. This information, however, may serve as a guide when choosing the commercial source of IVIG for therapeutic applications in Alzheimer's disease
Since the 80s power production with solar thermal power plants has been a way to substitute fossil fuels. By concentrating direct solar radiation from heliostats very high temperatures of a thermal fluid can be reached. The resulting heat is converted to mechanical energy in a steam cycle which generates electricity.
High efficiencies and fast start-up are reached by using air as a heat medium, as well as using porous ceramic materials as solar receiver of the concentrated sunlight.
In Germany the construction of a 1.5 MWe solar tower power plant began in 2008. It is operational since December 2008 and started production of electricity in the spring of 2009.
In Greece and Cyprus, countries with high solar potential, the development of this competitive solar thermal technology is imperative, since it has already been implemented in other Mediterranean countries.
Shakedown analysis of two dimensional structures by an edge-based smoothed finite element method
(2010)
Capacitive field-effect electrolyte-diamond-insulator-semiconductor (EDIS) structures with O-terminated nanocrystalline diamond (NCD) as sensitive gate material have been realized and investigated for the detection of pH, penicillin concentration, and layer-by-layer adsorption of polyelectrolytes. The surface oxidizing procedure of NCD thin films as well as the seeding and NCD growth process on a Si-SiO2 substrate have been improved to provide high pH-sensitive, non-porous thin films without damage of the underlying SiO2 layer and with a high coverage of O-terminated sites. The NCD surface topography, roughness, and coverage of the surface groups have been characterized by SEM, AFM and XPS methods. The EDIS sensors with O-terminated NCD film treated in oxidizing boiling mixture for 45 min show a pH sensitivity of about 50 mV/pH. The pH-sensitive properties of the NCD have been used to develop an EDIS-based penicillin biosensor with high sensitivity (65-70 mV/decade in the concentration range of 0.25-2.5 mM penicillin G) and low detection limit (5 μM). The results of label-free electrical detection of layer-by-layer adsorption of charged polyelectrolytes are presented, too.
Urinary stone formation has been evolved to a widespread disease during the last years. The reason for the formation of urinary stones are little crystals, mostly composed of calcium oxalate, which are formed in human kidneys. The early diagnosis of the risk for urinary stone formation of patients can be determined by the “Bonn-Risk-Index” method based on the potentiometric detection of the Ca2+-ion concentration and an optical determination of the triggered crystallisation of calcium oxalate in unprocessed urine. In this work, miniaturised capacitive field-effect EMIS (electrolyte-membrane-insulator-semiconductor) sensors have been developed for the determination of the Ca2+-ion concentration in human native urine. The Ca2+-sensitive EMIS sensors have been systematically characterised by impedance spectroscopy, capacitance–voltage and constant–capacitance method in terms of sensitivity, signal stability and response time in both CaCl2 solutions and in native urine. The obtained results demonstrate the suitability of EMIS sensors for the measurement of the Ca2+-ion concentration in native urine of patients.
A handheld sensor system for the online measurement of hydrogen peroxide (H2O2) in aseptic sterilisation processes has been developed. It is based on a calorimetric-type gas sensor that consists of a differential set-up of two temperature sensors, of which one is catalytically activated and the second one is passivated and used as reference. The sensor principle relies in detecting a rise in temperature on the active sensor due to the exothermic reaction of H2O2 on the catalytic surface. To characterise the sensor system towards H2O2 sensitivity and other influencing factors, measurements have been carried out both at an experimental set-up and a manufacturer's sterilisation machine. Physical sensor characterisation was done by means of the optical microscopy.
The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the spatial distribution of chemical species. For the practical application of this sensor, artifacts in the chemical images due to defects of the semiconductor substrate and contamination of the sensing surface etc. have been a major problem. An image correction method was developed to eliminate the influence of nonuniformity of individual sensor plate.