Porous conducting polymer/heteropolyoxometalate hybrid material for electrochemical supercapacitor applications

A porous conducting polymer/heteropolyoxometalate hybrid material that displays high specific capacitance and low ionic resistance has been prepared for electrochemical supercapacitor applications. Polypyrrole/phosphomolybdate composite films were chemically synthesized in tetrahydrofuran in the presence of sodium sulfate, which acts as a porogen. While the phosphomolydic acid could be removed from the film upon rinsing with pure tetrahydrofuran or acetone, rinsing with water or methanol resulted in retention of the heteropolyoxometalate at a level high enough to easily observe its electrochemistry. The retained phosphomolybdate exhibits fast and reversible redox behavior, adding a significant amount of pseudocapacitance to the polymer. Porous films were obtained by leaching out the sodium sulfate porogen from the films using water. The morphology obtained using this method is altered by varying the monomer-to-porogen ratio. Increasing the porosity increases the rate at which the hybrid material can be charged/discharged (i.e., oxidized/reduced) by increasing the ionic conductivity and in turn lowering the resistor-capacitor time constant of the material. The ability to tune the porosity of the material allows the optimization of performance characteristics for use in supercapacitor applications. Impedance measurements indicate that the ionic conductivity of these porous structures can be increased more than an order of magnitude over that observed for standard conducting polymer films and that the hybrid material displays peak specific capacitance of around 700 F/g as well as excellent reversibility and cyclability.     

Simulation of Catalyzed Urethane Polymerization: An Approach to Expedite Commercialization of Bio-based Materials

A MATLAB program was developed to simulate polyurethane foaming reaction. Key reactions (including isocyanate–polyol and isocyanate–water) and dozens of primary side reactions were taken consideration into the simulation of polymerization. The model tracks reaction rates, component concentration profiles and the temperature profile for the reactions under different conditions respect to different catalyst types, amount of catalyst loading, reaction temperature and the reactivities of the monomers with each other. Tin based catalysts and amine based catalysts were applied into gel and foam recipes separately to evaluate the impact of each catalyst on both gel and blow reactions. The model predicts performances of diverse foam recipes and can be effective for “sensitivity studies” useful in designing form formulations. The simulations have been validated for estimating catalyst loadings, identifying the tradeoff between higher catalyst loadings versus preheating of reagents, and providing insight into fundamental mechanisms/reactions.     

Invariance, Symmetry and Meaning

The role of the concept of invariance in physics and geometry is analyzed, with attention to the closely connected concepts of symmetry and objective meaning. The question of why the fundamental equations of physical theories are not invariant, but only covariant, is examined in some detail. The last part of the paper focuses on the surprising example of entropy as a complete invariant in ergodic theory for any two ergodic processes that are isomorphic in the measure-theoretic sense.     

Violation of bell's inequalities with a local theory of photons

We use a local theory of photons purely as particles to model the single-photon experiment proposed by Tan, Walls, and Collett. Like Tanet al. we are able to derive a violation of Bell's inequalities, but our local probabilistic theory does not use any specific quantum mechanical assumptions or calculations.     

New Bell-type inequalities forN > 4 necessary for existence of a hidden variable

The purpose of this paper is to extend Bell's inequalities to obtain some general necessary conditions for the existence of a joint probability distribution for any finite collection of Bell-type random variables. Our results show that forN > 4 many new elementary inequalities beyond those of Bell must be satisfied by any hidden variable theory.     

A random-walk approach to interference

In this paper we sketch a probabilistic particle approach requiring no separate concept of wave to obtain interference. We describe in some detail how things work from a physical standpoint and show with a number of figures how the standard wave concepts are developed from purely particle random walks. For the wave concepts we have in each case a matching probability concept. The preliminary theory developed here is qualitative and stresses the physical character of the assumptions. In particular, we show that the periodic behavior of light is derived from the source and not from individual photons.