A series of photochromic spironaphthoxazine derivatives has been designed, synthesized, and characterized by using 1H NMR spectroscopy, FAB mass spectrometry, and elemental analysis. Their photophysical and photochromic behavior have been investigated. Two of the compounds (G12‐en‐SA‐SO and G16‐en‐SA‐SO) have been shown to be capable of forming stable thermoreversible organogels in organic solvents, tested by the “stable‐to‐inversion of a test tube” method. Addition of p‐toluenesulfonic acid was found to induce the formation of stable organogels at concentrations below that of the critical gelation concentration (c.g.c.), with a concomitant change in color from colorless to purple. Transmission electron microscopy and scanning electron microscopy of the xerogels showed typical fibrous structures in the micrometer scale. The activation parameters for the bleaching reaction of G8‐en‐SA‐SO in the solution state and G16‐en‐SA‐SO in the gel state have been determined in ethanol through kinetic studies at various temperatures. The results showed that the rate of the bleaching reaction in the gel state was much slower than that in the solution state. 相似文献
A low-noise, ultra-short linear-cavity distributed feedback fiber laser (DFB-FL) with extremely narrow linewidth is presented.
The FL has a total length of 17 mm, which is, to our knowledge, the shortest DFB-FL being reported. It has a measured linewidth
of merely 250 Hz without active stabilization. It has a polarization beat frequency of 101 MHz, which is several times lower
than that of most FLs. The relaxation oscillation frequency and relative peak are 110 kHz and −76.5 dB/Hz, respectively. The
FL exhibited low-noise characteristics, with an intensity noise of −107 dB/Hz at 1 MHz. Due to low dopant concentration of
the EDF and low splice loss with ordinary single-mode fibers, the net insertion loss amounts to only 0.45 dB. Such low pump
power loss greatly enhances the capability of multiplexing a large number of FL sensors. Thus, these ultra-short DFB-FLs open
up new opportunities for the development of compact-sized point sensor array systems for large-scale high sensitivity sensing
applications. 相似文献
We study an SU(2) lattice gauge field system on a 104 symmetric and on a 103 × 2 asymmetric lattice in order to learn about the equation of state. 相似文献
For an nonnegative matrix , an isomorphism is obtained between the lattice of initial subsets (of ) for and the lattice of -invariant faces of the nonnegative orthant . Motivated by this isomorphism, we generalize some of the known combinatorial spectral results on a nonnegative matrix that are given in terms of its classes to results for a cone-preserving map on a polyhedral cone, formulated in terms of its invariant faces. In particular, we obtain the following extension of the famous Rothblum index theorem for a nonnegative matrix: If leaves invariant a polyhedral cone , then for each distinguished eigenvalue of for , there is a chain of distinct -invariant join-irreducible faces of , each containing in its relative interior a generalized eigenvector of corresponding to (referred to as semi-distinguished -invariant faces associated with ), where is the maximal order of distinguished generalized eigenvectors of corresponding to , but there is no such chain with more than members. We introduce the important new concepts of semi-distinguished -invariant faces, and of spectral pairs of faces associated with a cone-preserving map, and obtain several properties of a cone-preserving map that mostly involve these two concepts, when the underlying cone is polyhedral, perfect, or strictly convex and/or smooth, or is the cone of all real polynomials of degree not exceeding that are nonnegative on a closed interval. Plentiful illustrative examples are provided. Some open problems are posed at the end.
We investigate families of quadrics all of which have the same intersection with two given hyperplanes. The cases when the two hyperplanes are parallel and when they are nonparallel are discussed. We show that these families can be described with only one parameter and describe how the quadrics are transformed as the parameter changes. This research was motivated by an application in mixed integer conic optimization. In that application, we aimed to characterize the convex hull of the union of the intersections of an ellipsoid with two half-spaces arising from the imposition of a linear disjunction. 相似文献
We have measured the variation of atmospheric pressure and of 222Rn activity concentration in the air of a wine cellar with an AlphaGAURD type ionization chamber radon monitor. We have found
that the 222Rn activity concentration varies inversely with pressure. To explain this behavior we have done model calculations. We have
compared the results of model calculations with the results of experimental measurements, and we have found that the model
is capable to reproduce some part of the variation of 222Rn activity concentration. 相似文献