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Full-Text Articles in Physical Sciences and Mathematics

Interaction Of Pyridine With Ba2casr2cu20x, Juana Acrivos, C. Lin Jan 1991

Interaction Of Pyridine With Ba2casr2cu20x, Juana Acrivos, C. Lin

Faculty Publications, Chemistry

The adsorption of of pyridine on single crystals of Bi2CaSr2Cu2Ox has been followed by optical microscopy on the crystal surface, where a blue solution is formed as a first step of reaction. The superconducting properties of the single crystal and its structure were monitored by ac susceptibility and by x-ray diffraction measurements. The results (as observed by the growth of the blue solution boundary versus time with Daa = 3.7x10-10 cm2/s.) indicate that the reaction starts at nucleation sites on the basal surface of the crystal. The edges of the crystal also show blue nucleation sites but these do not …


Nonequilibrium Processes In Polymers Undergoing Interchange Reactions. Part 2: Reaction-Diffusion Processes, Alejandro Garcia, J. Pojman, D. Kondepudi, C. Van De Broeck Jan 1991

Nonequilibrium Processes In Polymers Undergoing Interchange Reactions. Part 2: Reaction-Diffusion Processes, Alejandro Garcia, J. Pojman, D. Kondepudi, C. Van De Broeck

Faculty Publications

A reactiodffusion system of polymers undergoing interchange reactions is studied. The equation that describes the dynamics of the system is similar to the Boltzmann equation for a gas of hard spheres. We consider a one-dimensionsl system in which the average length and the concentrations at the boundaries are fixed. The resulting steady states are obtained analytically and with numerical integration of equations obtained by using a local equilibrium approximation. Monte Carlo simulations of experimentally realizable conditions were performed and compared. The results reveal a nonlinear distribution of molecular concentration and mass. The entropy of the polymer distributions is calculated as …


Determination Of Rate Distributions From Kinetic Experiments, Todd B. Sauke, P. J. Steinback, K. Chu, H. Frauenfelder, J. B. Johnson, D. C. Lamb, G. U. Nienhaus, R. D. Young Jan 1991

Determination Of Rate Distributions From Kinetic Experiments, Todd B. Sauke, P. J. Steinback, K. Chu, H. Frauenfelder, J. B. Johnson, D. C. Lamb, G. U. Nienhaus, R. D. Young

Faculty Publications

Rate processes in proteins are often not adequately described by simple exponential kinetics. Instead of modeling the kinetics in the time domain, it can be advantageous to perform a numerical inversion leading to a rate distribution function f(lambda). The features observed in f(lambda) (number, positions, and shapes of peaks) can then be interpreted. We discuss different numerical techniques for obtaining rate distribution functions, with special emphasis on the maximum entropy method. Examples are given for the application of these techniques to flash photolysis data of heme proteins.


Critical Phenomena From Diamagnetic Signal In High Tc Perovskites, Juana Acrivos, M. Chen Lei Jan 1991

Critical Phenomena From Diamagnetic Signal In High Tc Perovskites, Juana Acrivos, M. Chen Lei

Faculty Publications, Chemistry

Critical phenomena in nearly two-dimensional high Tc superconductors are detected by induction measurements of the shielding current produced by bulk quantization of flux vs Hz.


Nonequilibrium Processes In Polymers Undergoing Interchange Reactions. Part 2: Reaction-Diffusion Processes, Alejandro Garcia, J. Pojman, D. Kondepudi, C. Van De Broeck Jan 1991

Nonequilibrium Processes In Polymers Undergoing Interchange Reactions. Part 2: Reaction-Diffusion Processes, Alejandro Garcia, J. Pojman, D. Kondepudi, C. Van De Broeck

Alejandro Garcia

A reactiodffusion system of polymers undergoing interchange reactions is studied. The equation that describes the dynamics of the system is similar to the Boltzmann equation for a gas of hard spheres. We consider a one-dimensionsl system in which the average length and the concentrations at the boundaries are fixed. The resulting steady states are obtained analytically and with numerical integration of equations obtained by using a local equilibrium approximation. Monte Carlo simulations of experimentally realizable conditions were performed and compared. The results reveal a nonlinear distribution of molecular concentration and mass. The entropy of the polymer distributions is calculated as …