Differential Cyclic Voltammetry - a Novel Technique for Selective and Simultaneous Detection using Redox Cycling Based Sensors

Redox cycling (RC) is an effect that is used to amplify electrochemical signals. However, traditional techniques such as cyclic voltammetry (CV) do not provide clear insight for a mixture of multiple redox couples while RC is applied. Thus, we have developed a new measurement technique which delivers electrochemical spectra of all reversible redox couples present based on concentrations and standard potentials. This technique has been named differential cyclic voltammetry (DCV). We have fabricated micrometer-sized interdigitated electrode (IDE) sensors to conduct DCV measurements in mixtures of 1mM catechol and 4mM [Ru(NH3)6]Cl3. To simulate the electrochemical behavior of these sensors we have also developed a finite element model (FEM) in Comsol®. The\ud experimental data corresponds to the calculated spectra obtained from simulations. Additionally, the measured spectra can be used to easily derive standard potentials and concentrations simultaneously and selectively.\u

The Canonical Perfect Bose Gas in Casimir Boxes

We study the problem of Bose-Einstein condensation in the perfect Bose gas in the canonical ensemble, in anisotropically dilated rectangular parallelpipeds (Casimir boxes). We prove that in the canonical ensemble for these anisotropic boxes there is the same type of generalized Bose-Einstein condensation as in the grand-canonical ensemble for the equivalent geometry. However the amount of condensate in the individual states is different in some cases and so are the fluctuations.Comment: 23 page

A micro CO2 gas sensor based on sensing of pH-sensitive hydrogel swelling by means of a pressure sensor

In this paper a sensor is presented for the detection of carbon dioxide gas inside the stomach in order to diagnose gastrointestinal ischemia. The operational principle of the sensor is measuring the CO/sub 2/ induced pressure generation of a confined pH-sensitive hydrogel by means of a micro pressure sensor. The sensor is capable of measuring CO/sub 2/ with a response time between 2 and 4 minutes and a maximum pressure of 0.29/spl times/10/sup 5/ Pa at 20 kPa CO/sub 2/. The sensor is able to resist up to 1 M HCl acid as can be present inside the stomach. The results are very promising for real application and clinical trials are planned

Toward a hydrogen peroxide sensor for exhaled breath analysis

In this contribution a chip-integrated amperometric sensor for the detection of H2O2 in exhaled breath condensate (EBC) is reported. The electrode chip is characterized, and detection of H2O2 in an aqueous phase is shown by means of cyclic voltammetry (CV) and amperometry. Variation of conditions such as the composition of the supporting electrolyte largely influences the obtained electrochemical response. Also it is found that electrochemical pretreatment of the platinum working electrode aiming at surface oxidation improves the detection limit of the sensor. Finally, the device is applied to measurement of H2O2 in the gaseous phase

MATCHED ARCHITECTURES FOR SIGNAL PROCESSING AND CONTROL

Fast processing environments for real-time data acquisition, data processing and control applications may be realised using very different architectures. State of the art systems generally employ multiprocessors and parallel processing having a dedicated architecture such as systolic arrays to support computation-intensive signal processing tasks such as, for instance, convolution, filtering, FFT. etc. Mostly, general purpose rather than application driven architectures are used whenever possible and the available literature is heavily concentrated on the first configuration. At TPD-TNO, the research emphasis is on application driven architectures. and the objectives for the so-called 'matched' architecture designs are: - Capability for a wide range of sizes, starting from small systems. The objective here is design for scalability - Design for systems to be used in harsh environments - Design for minimum connectivity. reduced communication bandwidth, incorporation of dedicated preprocessing. multibus systems, etc. The real-time behaviour of general purpose architectures is not sufficiently predictable and they are not designed to perform acquisition tasks or data-intensive processing with high performance. Matched architectures, on the contrary, are designed for well defined applications and optimized for each application, The key effort in matched architecture research is directed towards efficiently mapping algorithms to processing steps in hardware (and software) architectures. Essentially. the design process is iterative

Evolutionary bi-stability in pathogen transmission mode

Many pathogens transmit to new hosts by both infection (horizontal transmission) and transfer to the infected host's offspring (vertical transmission). These two transmission modes require speci®c adap- tations of the pathogen that can be mutually exclusive, resulting in a trade-off between horizontal and vertical transmission. We show that in mathematical models such trade-offs can lead to the simultaneous existence of two evolutionary stable states (evolutionary bi-stability) of allocation of resources to the two modes of transmission. We also show that jumping between evolutionary stable states can be induced by gradual environmental changes. Using quantitative PCR-based estimates of abundance in seed and vege- tative parts, we show that the pathogen of wheat, Phaeosphaeria nodorum, has jumped between two distinct states of transmission mode twice in the past 160 years, which, based on published evidence, we interpret as adaptation to environmental change. The ®nding of evolutionary bi-stability has impli- cations for human, animal and other plant diseases. An ill-judged change in a disease control programme could cause the pathogen to evolve a new, and possibly more damaging, combination of transmission modes. Similarly, environmental changes can shift the balance between transmission modes, with adverse effects on human, animal and plant health