Miniaturized laser heterodyne radiometer for measurements of CO2 in the atmospheric column

We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO₂) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO₂ in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH₄) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H₂O) and nitrous oxide (N₂O).     

The effect of screening on entropy production in pattern formation

Information theory is used to study the effects of screening on the rate of entropy production during pattern formation. Screening is an effect where the outermost parts of a growing fractal pattern influence the growth probability at interior sites. The results demonstrate that a state of maximum entropy production does exist for dynamical systems which generate patterns based on simple screening rules alone. This state corresponds to a critical point where the pattern exhibits self-similarity and fractal properties typical of random aggregates. Scaling occurs because the screening transmits information from the smallest to the largest scales of the system.     

Electrochemical irreversibility of ion transfers at liquid/liquid interfaces: Part II. Quasi-thermodynamic analysis and time dependences for single ion transfers

Structure of the double layer at immiscible liquid electrolyte interfaces is a controversial topic. and is essential to correct interpretation of ion-crossing kinetics. For single partitioned salt systems, (NR₄⁺X^? at H₂O/PhNO₂ interfaces for example. single ion free energies in each phase determine equilibrium charge and control pds in part. For non-equilibrium applied pds and currents. the overpotential may be entirely accounted for in space-charge perturbations, or as pds in compact layers in each phase, or as combinations of both. Experimental results for irreversible and quasi-reversible ion transfers, at constant current, suggest a pd across a compact layer. New results in the absence of supporting electrolyte are crucial to the argument. Log analytical plots are now available for pd dependences on time for various cases, including a compact layer whose order and capacitance depends upon charge. These plots are described and used in the analysis of experimental data.