Enzyme electrode for the determination of glucose.
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Blood Glucose↗
Biomedical subjects
J Rishpon
Publications and source records attributed to J Rishpon.
Smectite clays in Mars soil: evidence for their presence and role in Viking biology experimental results.
Various chemical, physical and geological observations indicate that smectite clays are probably the major components of the Martian soil. Satisfactory ground-based chemical simulation of the Viking biology experimental results was obtained with the smectite clays nontronite and montmorillonite when they contained iron and hydrogen as adsorbed ions. Radioactive gas was released from the medium solution used in the Viking Labeled Release (LR) experiment when interacted with the clays, at rates and quantities similar to those measured by Viking on Mars. Heating of the active clay (mixed with soluble salts) to 160 degrees C in CO2 atmosphere reduced the decomposition activity considerably, again, as was observed on Mars. The decomposition reaction in LR experiment is postulated to be iron-catalyzed formate decomposition on the clay surface. The main features of the Viking Pyrolytic Release (PR) experiment were also simulated recently (Hubbard, 1979) which the iron clays, including a relatively low '1st peak' and significant '2nd peak'. The accumulated observations on various Martian soil properties and the results of simulation experiments, thus indicate that smectite clays are major and active components of the Martian soil. It now appears that many of the results of the Viking biology experiments can be explained on the basis of their surface activity in catalysis and adsorption.
Chemical Phenomena↗
Amperometric biosensors based on microflow injection system.
Novel electrochemical cells based on a microflow system combined with amperometric enzyme electrodes were developed and served for quantitative determination of various compounds, such as organophosphates and lactose. The resulting biosensors are selective and efficient owing to immobilization of the sensing elements on the electrodes. The sensors are easy to operate, and the procedures are rapid, accurate, reproducible, and inexpensive, requiring neither special skills and training nor complicated instrumentation. The use of a microflow cell ensures the continuous flux of a new substrate, thus preventing the accumulation or adsorption of products to the electrode. Miniaturization of the sensor has two main advantages: (1) it is easy to carry and therefore can be used outdoors as well, and (2) it allows working with low volumes of compounds and reagents, which is highly important when dealing with hazardous compounds.
Acetylthiocholine↗