Colorimetric assay for a fast parallel screening of NOx storage

A fast parallel method for determining the capacity of an automotive catalyst to trap and especially store NOx has been established. A three-step approach, including parallel adsorption of NO onto the catalyst samples, water extraction of trapped NOx in the form of NO2- and NO3- in an aqueous solution, and colorimetric assay based on the sensitive and dramatic color change from colorless to deep red of the organic dye through the Griess diazotation reaction has been performed sequentially to give a fast parallel and quantitative evaluation of the amount of NOx trapped over promising automotive catalysts. The results correlate well with those obtained by means of traditional, time-consuming techniques, such as temperature-programmed desorption. (c) 2006 Elsevier Inc. All rights reserved.X115sciescopu

Critical factors governing vertical phase separation in polymer–PCBM blend films for organic solar cells

In organic bulk-heterojunction solar cells, the vertical distribution of the composition of the active layers as well as the lateral morphology is one of the critical issues that can significantly affect charge transport and recombination characteristics. Here we studied the critical parameters that can affect the formation of vertically stratified bulk heterojunction organic solar cells based on various polymers with different side chains, and investigated the effect of the miscibility of the polymer-fullerene blend and the crystallinity of the polymer on vertical morphology. The major factor that affected the vertical phase separation was the interaction parameter chi between the polymer and phenyl-C-61-butyric acid methyl ester (PCBM). Polymer-PCBM blends with high values of chi tended to trigger surface-directed vertical phase separation during rapid solvent evaporation. However, strong aggregation of polymers with low solubility counteracted this surface-directed vertical stratification. Moreover, solvent additives strongly affected the vertical phase separation processes, and caused the composition of the active layer to fluctuate dramatically. We also found the photovoltaic characteristics, including charge recombination time, to be strongly affected by the vertical distribution of the composition. The modulation of the composition in the vertical direction should therefore be optimized to increase the efficiency of charge collection and hence achieve high-efficiency organic solar cells.11135sciescopu

Uniform strong law of large numbers for random signed measures

We prove a strong law of large numbers for random signed measures on Euclidean space that holds uniformly over a family of arguments (sets) scaled by diagonal matrices. Applications to random measures generated by sums of random variables, marked point processes and stochastic integrals are also presented

Neural Mechanisms of Encoding Binaural Localization Cues in the Auditory Brainstem

When an animal hears a sound in its environment, there are several important tasks that the auditory system must try to accomplish. Two major jobs are to determine what it was that produced the sound and where it comes from. Understanding how the nervous system can accomplish these tasks is a majo