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Show moreBackground of the invention: The present invention relates to the analytical chemistry arts. It finds particular application in conjunction with the titrimetric analysis of microliter size samples. It also finds application in conjunction with instrumentation for electrochemical studies of microliter size samples and in studies where the rapid achievement of steady state conditions is desirable. Further, it finds application in conjunction with the electrochemical analysis of non-homogeneous samples. The invention is also applicable to other chemical procedures where precise microdelivery of a reagent is desirable.I. Routine analysis of the chemical composition of fluids is important in a wide range of fields, including clinical diagnosis, food and drug industries, industrial process control, and environmental studies. Due to the accuracy and reliability that titrimetric methods provide, they are widely used in diagnostic tests. For accurate results laboratory expertise, relatively large sample volumes, and often devices with expensive micromechanical elements are required for titrimetric studies. In many areas, for example in forensic testing and clinical diagnosis, large quantities of a sample to be studied may be costly or not readily available. To maintain the accuracy of measurements as the size of the sample decreases, the cost of the titration equipment, and the level of skill required, generally increase. Automated addition of reagents further adds to the cost, particularly when delivering microliter size volumes or less.II. Another analytical technique, the investigation of basic electrochemical reactions, is very important for industrial development in many fields, including semiconductors, the fuel industry, corrosion, quality control, and process monitoring. The rate of electrochemical reactions is limited by the rate of mass transport over the surface of the electrode. However, the natural processes of diffusion can be accelerated by hydrodynamic electrochemical techniques. Hydrodynamic electrochemical techniques with enhanced convective mass transport exhibit a number of advantageous voltammetric characteristics. The relative contribution of mass transport limitations with respect to electron kinetics is less pronounced. (Bard, A. J.; Faulkner, L. R.: Electrochemical Methods; John Wiley, (1980)). Steady state conditions (where the current is independent of potential scan direction and time) are attained quickly. Thus, measurements can be carried out with high precision. In addition, at steady state, double layer charging is not a factor. Traditionally, one of the best methods of obtaining efficient convective mass transport uses a rotating electrode system, such as a rotating disc or ring-disc electrodes. In the latter case, the electrochemically generated species at the disc are swept by laminar flow past the ring, where they can be monitored.
http://www.google.com/patents?vid=USPAT6043878
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Show moreBackground of the invention: 1. Field of the Invention: The invention relates to a method for solving deconvolution problems where it is desired to reconstruct a signal over a time range or another variable of interest. It finds particular application in determining a flux from a source which is spaced from a detector, such as determining flux from a biological cell or layer of cells, and will be described with particular reference thereto. The invention is equally applicable to a wide range of deconvolution problems, curve fitting problems, spectral shape recognition and analysis, calibration, and the like, where the independent variable may be time or spatial or other coordinates. 2. Discussion of the Articles: Transport at the cellular level is an essential element for sustaining life. Anomalies in cellular transport have been associated with a host of conditions, ranging from Cystic Fibrosis to Multidrug Resistance (MDR) in cancer cells. In order to treat such life threatening conditions, it is desirable to develop a qualitative and quantitative understanding of the underlying transport mechanisms and their anomalies. Cellular release is a very common mode of transport used by cells to make adjustments to changes in their environment in order to maintain homeostasis and to respond to external stimuli. Hence, understanding of the type and quantities of species released by a particular cell type can assist in understanding the associated biological processes taking place. Transport at a cell cluster, or at single cells, may involve release, cellular efflux, uptake, mass transport in the extracellular medium, or any combination of these processes. The quantity characterizing these processes is generally called a flux, or a flux density, and is expressed in units of moles (or weight) per unit area per unit time. The ability to provide accurate plots of flux over time has particular application in the study of cellular transport mechanisms. There are many applications when it is desirable to reconstruct flux values from signals detected some distance from the source of the flux. For example, in studying efflux of a chemical, such as an ion or drug, from a monolayer of biological cells, such as human or other animal cells, the monolayer is covered by a liquid, such as a cell medium or buffer. A sensor, such as an electrode system, is placed in contact with the liquid, at a finite distance from the monolayer. The sensor measures a concentration of the drug or ion (hereinafter chemical species) in the adjacent liquid, rather than the actual flux of the drug or ion secreted from the monolayer. This is because the measured concentration depends on not only the efflux at the monolayer surface, but also on the diffusion of the chemical species, and the distance of the sensor from the monolayer.
http://www.google.com/patents?vid=USPAT6859767
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