Physical basis for constrained lattice density functional theory

To study nucleation phenomena in an open system, a constrained lattice density functional theory (LDFT) method has been developed before to identify the unstable directions of grand potential functional and to stabilize nuclei by imposing a suitable constraint. In this work, we answer several questions about the method on a fundamental level, and give a firmer basis for the constrained LDFT method. First, we demonstrate that the nucleus structure and free energy barrier from a volume constraint method are equivalent to those from a surface constraint method. Then, we show that for the critical nucleus, the constrained LDFT method in fact produces a bias-free solution for both the nucleus structure and nucleation barrier. Finally, we give a physical interpretation of the Lagrange multiplier in the constraint method, which provides the generalized force to stabilize a nucleus in an open system. The Lagrange multiplier is found to consist of two parts: part I of the constraint produces an effective pressure, and part II imposes a constraint to counteract the supersaturation.     

Initiation,Development and Stabilization of Cavities during Tensile Deformation of Semicrystalline Polymers

By using polybutene-1 as a typical example, we illustrate the initiation, development and stabilization of cavities in the sample during tensile deformation. Samples with the same crystallinity, long spacing and crystalline lamellar thickness but very different sizes of spherulites were prepared via changing the melt history. Dimension of cavities during stretching the samples was determined by in situ ultra small angle X-ray scattering techniques. It turned out that the size of the cavities was bigger in the sample with larger spherulites than the one with smaller spherulites. The results show clear evidence of initiating cavities within crystalline phase at the grain-boundary of crystalline blocks, growing of cavities passing through parallel stacked lamellar crystals and amorphous layers and finally stablized by tilted lamellae at both ends of the plate-like cavities within the spherulites.     

Catalytic properties of Fe/SiO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> systems,obtained via sol–gel method

The high efficacy of iron-containing catalysts based on SiO₂–Al₂O₃ systems obtained via sol–gel method in the oxidative destruction of carmoisine azo dye in aqueous solutions is demonstrated. It is found that the stability of the catalysts with respect to the leaching of iron ions into a solution during catalysis grows along with the aluminum content in the composition of aluminosilicate supports. It is concluded that the synthesized catalysts are promising materials for purifying wastewaters contaminated with organic dyes.     

Study of microimpurities and charge states in homogeneous hydrocarbon films (Redeposited from a T-10 tokamak deuterium plasma discharge) using XRF analysis, IR spectroscopy, EPR, and I-V characteristics

Microimpurities and charge states of homogeneous deuterated hydrocarbon films redeposited from a T-10 tokamak deuterium plasma discharge are studied spectroscopically using x-ray fluorescence (XRF) analysis, electron paramagnetic resonance (EPR), infrared (IR) spectroscopy; current-voltage (I-V) charachteristics are also measured. Twelve microimpurities (mainly, those of transition metals Fe, Mo, Cr, Ni, Ti, etc., with relative concentrations of 50–7000 ppm) have been discovered. The resulting broad EPR (9.9 GHz, 6000 G) line with g-factors of g = 2.053–2.093 and g = 4.3 assigned to paramagnetic impurities confirms their presence. The presence of different charge states on two sides of the film (one facing the plasma and another facing the vacuum-chamber wall) and the difference in the IR spectra of these states are established. This can be explained by the process of film formation under the influence of the tokamak plasma.     

Electronic excitations of C(60) aggregates

Excitation properties of the isolated C(60) and (C(60))(N) model clusters (N = 2, 3, 4, 6 and 13) are studied using an a priori parameterized and self-consistent Hamiltonian, the Complete Neglect of Differential Overlap considering the l azimuthal quantum number method. This method properly describes electron excitations of the isolated C(60) after the configuration interaction of singles (CIS) procedure, when those are compared with experimental data in n-hexane solution and in a molecular beam. Geometry models of (C(60))(N) clusters to model the effect of aggregation were obtained from the fullerene fcc crystal. Some peaks in the low energy edge of the absorption spectrum appear corresponding to clustering effects, as well as small increases of bandwidths in the strong bands at the UV region. An analysis of the theoretical absorption spectrum for dimer models has been carried out, taking into account the influence of the distance between fullerene centers. The density of states of CIS for fullerene clusters in the range from 2.0 to 6.5 eV shows the possibility of electron transitions as functions of the size of the clusters.     

光化学反应在分析化学中的应用研究 光激活产生碘测定食品中的抗坏血酸

本文探讨了酸性介质中于紫外光的照射下,利用光激活产生碘的光化学动力学法测定抗坏血酸的可能性。结果表明,在0.25mol/L的硫酸介质中,在过量碘化钾的存在下,抗坏血酸的含量与到达滴定终点的时间在较宽的浓度范围内呈良好的线性关系。用于蜂蜜,黄瓜、蕃茄及Vc药片等样品分析,其相对标准偏差均在1％以下,准确度令人满意。     

Weak boundedness properties for maximal operators defined on weighted spaces

The purpose of this paper is to obtain characterizations of weak type (1,q) inequalities,q ≥ 1, for maximal operators defined on weighted spaces by means of the corresponding operator acting over Dirac deltas. We present a technical theorem which allows us to obtain characterizations for a pair of weights belonging to the classA ₁ of weights by means of the fractional maximal operator. Analogous results are obtained for the one-sided fractional maximal operator.     

Stimulated Raman scattering influenced by concentration,fluorescence profile and bandwidth of β‐carotene in liquid‐core optical fiber

We demonstrated stimulated Raman scattering (SRS) of carbon disulfide (CS₂) influenced by β‐carotene in a liquid‐core optical fiber (LCOF). Owing to the double fluorescence characteristics and large third‐order optical nonlinearity of β‐carotene, the high‐order Stokes lines, such as the seventh‐order Stokes line of CS₂, can be observed at a relatively low input‐laser power. The thresholds of Stokes lines lowered with the addition of the carotenoid when the concentration of solution was within 10⁻¹² and 10⁻⁷ mol/L; the threshold increments and intensities of Stokes lines were correlative with the fluorescence profile of β‐carotene: when the fluorescence intensity of the wavenumber region on the spectrum was high, the Stokes line intensity was also high and its threshold increment was small, and vice versa. These results are expected to be worthy of the applications on the tunable laser and the seeding laser. Copyright © 2009 John Wiley & Sons, Ltd.     

Vibration-induced energy relaxation in two-level system

Energy decay in a general two-level electronic system coupled to a vibrational harmonic mode interacting with a thermal bath is studied theoretically. The model assumes a general form of the off-diagonal elements (in the electronic basis) of the vibrational-electronic interaction. The cases for constant, linear, and quadratic dependence with respect to the vibrational displacement are investigated. For short-time regime, fast oscillations corresponding to a coherent energy exchange between electrons and vibrations appear. Their frequency Ω corresponds to the energy difference (ħΩ) between electronic levels. Additionally, for the case of linear or quadratic coupling, the amplitude modulation of the oscillations with the frequency ω equal to that of vibrational motion is found.