80 research outputs found
Realization and Properties of Biochemical-Computing Biocatalytic XOR Gate Based on Enzyme Inhibition by a Substrate
We consider a realization of the XOR logic gate in a process biocatalyzed by
an enzyme (here horseradish peroxidase: HRP), the function of which can be
inhibited by a substrate (hydrogen peroxide for HRP), when the latter is
inputted at large enough concentrations. A model is developed for describing
such systems in an approach suitable for evaluation of the analog noise
amplification properties of the gate. The obtained data are fitted for gate
quality evaluation within the developed model, and we discuss aspects of
devising XOR gates for functioning in "biocomputing" systems utilizing
biomolecules for information processing
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Applications of electrified dust and dust devil electrodynamics to Martian atmospheric electricity
Atmospheric transport and suspension of dust frequently brings electrification, which may be substantial. Electric fields of 10 kVm-1 to 100 kVm-1 have been observed at the surface beneath suspended dust in the terrestrial atmosphere, and some electrification has been observed to persist in dust at levels to 5 km, as well as in volcanic plumes. The interaction between individual particles which causes the electrification is incompletely understood, and multiple processes are thought to be acting. A variation in particle charge with particle size, and the effect of gravitational separation explains to, some extent, the charge structures observed in terrestrial dust storms. More extensive flow-based modelling demonstrates that bulk electric fields in excess of 10 kV m-1 can be obtained rapidly (in less than 10 s) from rotating dust systems (dust devils) and that terrestrial breakdown fields can be obtained. Modelled profiles of electrical conductivity in the Martian atmosphere suggest the possibility of dust electrification, and dust devils have been suggested as a mechanism of charge separation able to maintain current flow between one region of the atmosphere and another, through a global circuit. Fundamental new understanding of Martian atmospheric electricity will result from the ExoMars mission, which carries the DREAMS (Dust characterization, Risk Assessment, and Environment Analyser on the Martian Surface)-MicroARES (Atmospheric Radiation and Electricity Sensor) instrumentation to Mars in 2016 for the first in situ measurements
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