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Mixed aromatic-isobutene clusters (Am*In, where A = toluene, p-xylene, mesitylene, 1,2,4-trimethylbenzene, styrene, and alpha-methylstyrene) were ionized by resonant two-photon ionization in the vicinity of the aromatic's 0(sub 0)(super 0) transition and by two-photon ionization using 248 nm and 193 nm photons. Findings were consistent with the distonic structure of the alpha-methylstyrene-isobutene radical cation which can initiate either cationic or radical propagation.

Iron–sulfur cluster ions FenSm+ (n=1–13, m=1–13) were produced by direct laser ablation on a solid sample containing a mixture of iron and sulfur powder. UV photodissociation of the cluster ions was studied with a tandem time-of-flight mass spectrometer. It was found that all the cluster ions with compositions of m=n, m=n-1, or m=n+5 were relatively more abundant, indicating that they were stable. The photodissociation results of the FenSm+ ions showed that, for parent ions with n≪m, the main channels were sequential losses of neutral S atoms until n∼m, while for parent ions with n∼m, the main product ions had compositions of smaller m=n or m=n-1. From these experimental results, it is proposed that the FenSn+ cluster ions might have structures similar to those of the FenS*n cores in iron–sulfur proteins, while the FenSm+ (m>=n) cluster ions could be considered to have structures with the FenSn+ cores surrounded by some peripheral S atoms. [ABSTRACT FROM AUTHOR]

This paper discusses the relationship between stimulating pulse width and the threshold of electrically evoked compound action potential (ECAP). Firstly, the rheobase and chronaxy from strength-duration curve of nerve fiber was computed using the shepherd's experiment results. Secondly, based on the relationship between ECAP and the action potential of nerve fiber, a mathematical expression to describe the relationship between stimulating pulse width and ECAP threshold was proposed. Thirdly, the parameters were obtained and the feasibility was proved to the expression with the results of experiment using guinea pigs. Research result showed that with ECAP compared to the action potential of nerve fiber, their threshold function relationship with stimulating pulse width was similar, and rheobase from the former was an order smaller in the magnitude than the latter, but the chronaxy was close to each other. These findings may provide meaningful guidance to clinical ECAP measurement and studying speech processing strategies of cochlear implant.