Electrochemical removal of p-nonylphenol from dilute solutions using a carbon fiber anode

p-Nonylphenol, which is widely used as raw material in industrial activities has been regarded as an environmental endocrine disrupter. In an effort to develop a new treatment method for p-nonylphenol, we initially investigated the electrochemical behavior of p-nonylphenol by voltammetric techniques. The electrochemical oxidation of p-nonylphenol led to the formation of electropolymerized film on the glassy carbon electrode surface. The fouling on the electrode surface by the electropolymerized film was evaluated by monitoring the electrode response of ferrocyanide ions as the redox marker. The electrochemical removal of p-nonylphenol based on the formation of the electropolymerized film on an anode surface was performed using a carbon fiber (CF) with a very large surface area. The high removal efficiency for p-nonylphenol was obtained by applying a potential at 0.7 V. The maximum surface coverage of electropolymerized p-nonylphenol on the CF was about 5 x 10(-9) mol/cm2. The presence of humic acid hardly inhibited the removal of p-nonylphenol. Furthermore, the application to the removal of phenol, o-chlorophenol, p-chlorophenol, 2,4-dichlorophenol, and 2,4,5-trichlorophenol was attempted by using this method.     

Molecular dynamics simulation of 〈<Emphasis Type="Bold">c</Emphasis>+<Emphasis Type="Bold">a</Emphasis>〉 dislocation core structure in hexagonal-close-packed metals

The core structures of 〈c+a〉 dislocations in hexagonal-close-packed (hcp) metals have been investigated by molecular dynamics (MD) simulation using a Lennard-Jones-type pair potential. The 〈c + a〉 edge dislocation has two types of core at 0 K; one is a perfect dislocation (type A), and the other has two 1/2 〈c+a〉 partials (type B). Type A transforms to type B by abruptly increasing temperature from 0 K to 293 K, while type B is stable in temperature range from 0 K to 293 K. In contrast, type A extends parallel to (0001) at 30 K, and this extended core is still stable at 293 K. These results suggest that the 〈c+a〉 edge dislocation glides on the {11 2} as two 1/2 〈c+a〉 partial dislocations and becomes sessile due to changes of the core structure. The 〈c+a〉 screw dislocation spreads over two {10 1} planes at 0 K. The core transforms into a unsymmetrical structure at 293 K, which is spread over {11 2} and {10 1}, and core spreading occurs parallel to {11 2} at 1000 K. A critical strain to move screw dislocations depends on the sense of shear strain. The dependence of the yield stress on the shear direction can be explained in terms of these core structures. This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals and Alloys” at the TMS Annual Meeting, February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following ASM committees: Materials Science Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee.     

A Novel Approach to the Polaronic Metallic State of Cuprate Superconductors and the d-Wave Pairing Mechanism

The present novel approach consists of two stages: in the first stage the many-electron states of a CuO₆ octahedron or a CuO₅ pyramid are calculated by the first-principles variational method, by taking into account the local distortions of a CuO₆ octahedron or a CuO₅ pyramid. In the second stage a metallic state is constructed in the presence of the local AF ordering constructed by the localized spins. In this metallic state the local distortions are treated in the mean field approximation, so that a pseudopolaronic effect is taken into account. Based on this approach, the hole-concentration dependence of T _c and the isotope effect are calculated for LSCO, and compared with experimental results. This approach leads to d-wave pairing mechanism.     

Simultaneous three-dimensional step-height measurement and high-resolution tomographic imaging with a spectral interferometric microscope

A noncontact, nonmechanical scanning, wide-field spectral interference microscope is developed for simultaneous measurement of three-dimensional step-height of discontinuous objects and tomographic imaging. A superluminescent diode (SLD) is used as a broadband light source and a liquid-crystal Fabry-Perot interferometer (LC-FPI) as a frequency-scanning device. By means of changing the injection current to the SLD, the spectral profile of the SLD is equalized, and a constant light input to the interferometer is achieved over the entire frequency-scan range. The Fourier-transform technique is used to determine both the amplitude and the phase of spectral fringe signals. Three-dimensional height distribution of a discontinuous object is obtained from the phase information, whereas optically sectioned images of the object are obtained either from the amplitude information alone or from the combination of both the amplitude and phase information. Experimental results with submicrometer resolution are presented for both step-height measurement and tomographic sectioning.     

基于长度的扩展方法的汉英句子对齐

本文提出了一种用于汉英平行语料库对齐的扩展方法。该扩展方法以基于长度的统计对齐方法为主,然后根据双语词典引入了词汇信息,而基于标点的方法作为对齐的后处理部分。这种扩展方法不仅避免了复杂的中文处理,例如,汉语分词和词性标注,而且在统计方法中引入了关键词信息,以提高句子对齐的正确率。本文中所用的双语语料是LDC 的关于香港的双语新闻报道。动态规划算法用于系统的实现。和单纯的基于长度的方法和词汇方法相比,我们的扩展方法提高了句子对齐的正确率,并且结果是比较理想的。     

MRF-based texture segmentation using wavelet decomposed images

In recent textured image segmentation, Bayesian approaches capitalizing on computational efficiency of multiresolution representations have received much attention. Most of the previous researches have been based on multiresolution stochastic models which use the Gaussian pyramid image decomposition. In this paper, motivated by nonredundant directional selectivity and highly discriminative nature of the wavelet representation, we present an unsupervised textured image segmentation algorithm based on a multiscale stochastic modeling over the wavelet decomposition of image. The model, using doubly stochastic Markov random fields, captures intrascale statistical dependencies over the wavelet decomposed image and intrascale and interscale dependencies over the corresponding multiresolution region image.     

Dipolar-decoupled carbon-13 NMR study of highly oriented polyethylene films

Summary High-resolution solid-state ¹³C NMR spectra and ¹³C relaxation times T₁ and T₁ have been measured at 40–100° C for uniaxially oriented polyethylene films with the drawing direction parallel to the magnetic field; this sample has a unique morphological structure that the noncrystalline chains are nearly disordered irrespective of the high degree of drawing. A sharp resonance line(line A) appears at the position corresponding to the principal value ₃₃ of the chemical shift tensor for the CH₂ carbons with the trans-trans conformation. Another sharp linedine B) is observed at almost the same chemical shift as for the CH₂ carbons of polyethylene in solution. Although these observations are similar to those for a cold-drawn polyethylene sample reported previously, line B is much enhanced in intensity and the linewidth is narrower in the present sample, reflecting the disorientation of the noncrystalline component. It is found from T₁ measurements that line A contains two components with different molecular mobility, both being assigned to the crystalline components. On the other hand, the line B is composed of a single component assignable to the noncrystalline component with liquid-like molecular mobility.