α-Fe2O3 nanotubes with superior lithium storage capability

Polycrystalline α-Fe(2)O(3) nanotubes with thin walls have been synthesized by one-step template-engaged precipitation of Fe(OH)(x) followed by thermal annealing. In virtue of the unique structural features, these α-Fe(2)O(3) nanotubes exhibit superior lithium storage capabilities with exceptional high-rate capacity retention as a potential anode material for lithium-ion batteries.     

Three-dimensional image reconstruction of an Hα flare on 26 March 2001

Three-dimensional (3D) image reconstruction of an Hα flare near the solar disk center, is done by a series of line-center and off-line-center filtering observation, according to the physical meaning of contribution function based on the line formation theory. The contribution function represents the contribution from stellar atmospheric layers to the emergent specific intensity and describes the depth distribution of escape photons. In this paper, an Hα flare of 26 March 2001 is used to illustrate the 3D line-of-sight reconstruction and its development     

Analysis of lateral-spread photorefractive planar lenses

The photorefractive planar lens for converting a vertical incident plane wave to a lateral-spread spherical wave and vice versa, is suggested. Using the two-beam coupled-wave theory, the coupled wave equations are derived and their half-analytical solutions are also given in terms of an infinite series. The diffraction properties (beam profiles, diffraction efficiency) of the local volume grating in the lens are presented. And the focusing property of the lens is discussed and compared with that of an ideal convergent spherical wave. It is demonstrated that the suggested photorefractive planar lens shows a good focusing effect.     

Diameter control of electrospun polyacrylonitrile/iron acetylacetonate ultrafine nanofibers

Electrospinning is the process of producing ultrafine fibers by overcoming the surface tension of a polymer solution using high voltage. In this work, the effects of both solution properties (viscosity, conductivity, and surface tension) and operational conditions (voltage, feed rate, and spinneret‐collector distance), on the structure of electrospun polyacrylonitrile nanofibers, were systematically investigated. Iron acetylacetonate was added to the electrospinning solution to control fiber diameter by selectively adjusting solution properties. It was found that, with increased salt concentration, the fiber diameter increases and then passes through a maximum due to changes in solution viscosity, conductivity, and surface tension. In addition, the fiber diameter increases with increase in voltage, feed rate, and spinneret‐collector distance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1611–1618, 2008     

聚合公理系统的布尔值模型

本文以ＺＦｃ聚合公理系统为基础，构造了ＺＦｃ的布尔值模型，证明了关键定理９、定理１５，使得ＺＦ集合公理系统的布尔值模型ＶＯｎ＾（Ｂ）是聚合公理系统的布尔值模型〔ＶＯＮ＾（Ｂ）〕的子模型，并且ＺＦ集合公理组在〔ＶＯＮ＾（Ｂ）〕中满足。     

Polarization phase-shifting Jamin shearing interferometer

The Jamin shearing interferometer is very useful in wavefront testing, especially for the low coherent light. Based on this interferometer, a polarization phase-shifting Jamin shearing interferometer is proposed to improve the performance. In the interferometer, two interference beams are linearly polarized and a polarization phase shifter is applied to realize the phase shifting. Different types of configurations of the interferometer are given. With phase-shifting interferograms, the precision of the interferometer can be improved. The interferometer is kept as an equal optical path system and its shearing amount remains changeable with simple structure and easy operation. In experiments, phase-shifting interferograms are obtained by rotating the analyzer. The usefulness of the interferometer is verified.     

Optimal dividend strategies in a dual model with capital injections

We study three types of practical optimization problems faced by a firm that can control its liquid reserves by paying dividends and by issuing new equity. In the first problem, we consider the classical dividend problem without equity issuance. The second problem aims at maximizing the expected discounted dividend payments minus the expected discounted costs of issuing new equity over strategies associated with positive reserves at all times. The third problem has the same objective as the second one, but with no constraints on the reserves. Under the assumption of proportional transaction costs, we identify the value functions and the optimal strategies. We also present the relationship between three problems.     

Chung’s law of the iterated logarithm for anisotropic Gaussian random fields

In this paper we establish Chung’s law of the iterated logarithm for a class of anisotropic Gaussian random fields with stationary increments. This result is applicable to space–time Gaussian random fields and solution to the stochastic fractional heat equation.