Corrosion behavior of 316 stainless steel for advanced high-temperature water-cooled nuclear plant

Corrosion occurs widely in the supercritical water system materials under high temperature and pressure. To select reliable candidate materials, corrosion behavior of many alloys was investigated. This study focused on investigating the corrosion behavior of 316 stainless steel (316 SS) in supercritical water (798 K/24 MPa). After exposed to SCW for 200 h, the oxidation kinetics, surface morphology, and diffusion of elements were investigated by weight measurement, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The surface of 316 SS showed isolated and discontinued oxide scales. The oxide scale was determined to be a monolayer layer, and the main composition was determined to be Fe–Cr-rich spinel with a few amounts of magnetite attached to the surface. A few pores due to pitting corrosion were found on the surface, and the oxidation mechanism was also investigated.     

A CASSCF/CASPT2 study on the low‐lying electronic states of the CH3SS and its cation

Complete active space self‐consistent field (CASSCF) and multiconfiguration second‐order perturbation theory (CASPT2) calculations with contracted ANO‐RCC basis set were performed for low‐lying electronic states of CH₃SS and its cation in C_s symmetry. For the ground state X²A″ of CH₃SS, the calculated S‐S stretching mode is in good agreement with experimental reports. The electron transitions of CH₃SS⁺, X¹A′ → 1¹A″, X¹A′ → 2¹A′, and X¹A′ → 2¹A″, are predicted at 1.055, 3.247, and 3.841 eV. Moreover, the calculated adiabatic and vertical ionization potential and adiabatic affinity are in reasonable agreement with the experimental data. The CASSCF/CASPT2 potential energy curves (PECs) were calculated for S₂‐loss dissociation from the X²A″, 1²A′, and 2²A″ states. The electronic states of the CH₃ radical and S₂ molecule as the dissociation products were carefully determined by checking energies and geometries of the asymptote products. The S₂‐loss PEC for CH₃SS indicate that S₂‐loss dissociation occurs from the X²A″ state leading to CH₃ (1²A″) + S₂ (X³Σ), the 1²A′ and 2²A″ leading to CH₃ (1²A″) + S₂ (¹Δ_g). © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012.     

Statistical approach to the code acquisition problem in direct-sequence spread-spectrum communication systems

^** Email: eshima{at}med.oita-u.ac.jp In direct-sequence spread-spectrum (DS/SS) communication, users'original signals are modulated into higher frequencies withthe users' codes. DS/SS communication has the attractive propertythat multiple users' signals can be simultaneously transmitted;however, communication cannot be performed without synchronizationof users' spread-spectrum (SS) signal. Synchronization is typicallyperformed in two steps, i.e. code acquisition and tracking.This paper gives a statistical solution to the question as tohow code acquisition can be performed effectively and precisely.First, properties of matched-filter outputs of SS signal arediscussed. Second, a theoretical method of code acquisitionis proposed according to statistical decision theory. The methoduses all matched-filter outputs for code acquisition. Third,matched-filter outputs are dichotomized with a threshold valueand the dichotomous outputs are used for code acquisition. Asimple and effective method for code acquisition is proposed.Numerical simulations are also given to illustrate the effectivenessof the proposed method. Finally, a further discussion and conclusionto this study are provided.     

几乎周期性与SS混沌集

引进正则移位不变集的概念,证明了有正则移位不变集的紧致系统在几乎周期点集中存在SS混沌集,特别地,具有正拓扑熵的区间映射在几乎周期点集中存在SS混沌集.     

Dual color emitting Eu doped strontium orthosilicate phosphors synthesized by bio-template assisted ultrasound for solid state lightning and display applications

A novel Sr₂SiO₄:Eu (1–5 mol %) superstructures (SS) were synthesized using bio-sacrificial A.V. gel assisted ultrasound method. Powder X-ray diffraction patterns confirmed the presence of both α and β phase formation. It was evident that the morphological growth was highly reliant on A.V. gel concentration, sonication time, pH and sonication power. The formation mechanisms for different hierarchical SS were proposed. From diffuse reflectance spectra, the energy band gap was estimated and found to be ∼4.70–5.11 eV. The photoluminescence emission spectra for the excitation at 392 nm, shows characteristic emission peaks at 593, 613, 654 and 702 nm which were attributed to ⁵D₀ → ⁷F₀, ⁷F_1, ⁷F₂ and ⁷F₃ transitions of Eu³⁺ ions respectively. Conversely, when the samples were subjected to the heat treatment at 850 °C for 3 h under argon atmosphere, display an intense broad emission peak with two de-convoluted peaks at 490 and 550 nm due to 4f⁶5d¹→4f¹ (⁸S_7/2) transitions of Eu²⁺ ions. The concentration quenching phenomenon was discussed which attributes to energy transfer, electron–phonon coupling and ion–ion interaction. The Judd–Ofelt intensity parameters and other radiative properties were estimated by using emission spectra. The CIE chromaticity coordinate values of Sr₂SiO₄:Eu²⁺ and Eu³⁺ nanophosphors were located in green and red regions respectively. The calculated CCT and CRI values specify that the present phosphor can be fairly useful for both green and red components of white LED’s. Luminescence decay and quantum yield suggest the suitability of this phosphor as an efficient luminescent medium for light emitting diodes. Overall, the results elucidated a rapid, environmentally benign, cost-effective and convenient method for Sr₂SiO₄:Eu³⁺ synthesis and for the possible applications such as solid state lighting and display devices.     

Simultaneous Determination of Fluoxetine,Estrone, Pesticides,and Endocrine Disruptors in Wastewater by Gas Chromatography–Mass Spectrometry (GC–MS) Following Switchable Solvent–Liquid Phase Microextraction (SS–LPME)

A simple and sensitive analytical method for the determination of fluoxetine, estrone and selected pesticides and endocrine disruptors has been proposed for wastewater analysis by gas chromatography–mass spectrometry (GC–MS). A switchable solvent was produced with N,N-dimethylbenzylamine by changing its hydrophobic properties by the addition of CO₂ for protonation. Sodium hydroxide was added to switch the solubility of the extraction solvent and to allow phase separation in the sample/standard medium. Analytical parameters affecting the extraction outputs such as volume of switchable solvent, concentration and volume of sodium hydroxide, mixing type and period were investigated to improve the extraction recovery of the selected analytes. Under the optimum conditions, limits of detection and limits of quantification for the analytes were calculated in the ranges of 0.16–8.6?ng mL^?1 and 0.54–29?ng mL^?1, respectively. The developed method was successfully applied to synthetic wastewater and two municipal wastewater samples. None of the selected analytes were detected in the samples. High recovery values demonstrated that the proposed method was reliable and applicable to complex matrices.     

Quantitative, dynamic and noninvasive determination of skeletal muscle perfusion in mouse leg by NMR arterial spin-labeled imaging

Because mouse may relatively easily be genetically tailored to develop equivalent of human muscular diseases or to present controlled alterations of mechanisms involved in vasoregulation, it has become the prevalent species to explore such questions. However, the very small size of the animals represents a serious limitation when evaluating the functional consequences of these genetic manipulations. In this context, the recourse to arterial spin labeling (ASL) nuclear magnetic resonance (NMR) methods in which arterial water spins act as an endogenous and freely diffusible tracer of perfusion is tempting but challenging. This article shows that despite the small size of the animal, mouse muscle perfusion may be measured, at rest and in conditions of reactive hyperemia, using saturation inversion recovery sequence, a pulsed ASL variant, combined with NMR imaging. Baseline perfusion values in the mouse leg were 17+/-11 ml.min(-1).100 g(-1) (n=11) and were comparable to microsphere data from the literature. Under ischemia, leg perfusion was 1.2+/-9.3 ml.min(-1).100 g(-1) (n=11). The difference observed between basal and ischemic measurements was statistically different (P=.0001). The temporal pattern of hyperemia in mouse muscle was coherent with previously published measurements in humans and in rats. The mean peak perfusion was 62+/-24 ml.min(-1).100 g(-1) (n=6) occurring 48+/-27 s after the end of occlusion. In conclusion, this study demonstrated the ability of ASL combined to NMR imaging to quantify skeletal muscle perfusion in mice legs, both at rest and dynamically.     

一种消象旋传动机构的设计与精度分析

本文提出了一种消象旋机构的结构形式.并对齿轮传动的结构方式做了重点介绍.通过对齿轮传动进行精度分析,可以得出传动过程中齿轮精度及传动误差对棱镜消旋系统正象精度的影响.     

Environmental application of elemental speciation analysis based on liquid or gas chromatography hyphenated to inductively coupled plasma mass spectrometry—A review

In recent years the number of environmental applications of elemental speciation analysis using inductively coupled plasma mass spectrometry (ICP-MS) as detector has increased significantly. The analytical characteristics, such as extremely low detection limits (LOD) for almost all elements, the wide linear range, the possibility for multi-elemental analysis and the possibility to apply isotope dilution mass spectrometry (IDMS) make ICP-MS an attractive tool for elemental speciation analysis. Two methodological approaches, i.e. the combination of ICP-MS with high performance liquid chromatography (HPLC) and gas chromatography (GC), dominate the field. Besides the investigation of metals and metalloids and their species (e.g. Sn, Hg, As), representing “classic” elements in environmental science, more recently other elements (e.g. P, S, Br, I) amenable to ICP-MS determination were addressed. In addition, the introduction of isotope dilution analysis and the development of isotopically labeled species-specific standards have contributed to the success of ICP-MS in the field. The aim of this review is to summarize these developments and to highlight recent trends in the environmental application of ICP-MS coupled to GC and HPLC.     

Nanoindentation studies and modeling of surface layers on austenitic stainless steels by extreme electrochemical treatments

The nanoindentation studies were performed on two austenitic stainless steels, AISI 304L and 316L. The steel samples have undergone two different electrochemical treatments, standard (EP50) and a high‐current density electropolishing (EP1000). Firstly, the observations of the steels' surfaces were done with the optic images of the AISI 304L and 316L SS after these two treatments displayed. Presented in the paper results have shown clearly that the high‐current density close to 1000 A/dm² allows for obtaining the passive nanolayers with other mechanical properties than those obtained after a standard electropolishing (EP50). The prediction of these results has been confirmed by the preliminary XPS studies allowing for modeling of the steels' surface layers. The main finding of the study is revealing a new method of electrochemical treatment (EP1000) allowing to obtain the reduced Young's modulus of the stainless steels lower than that obtained after EP50. This feature is of high importance regarding the use of these steels as biomaterials. Copyright © 2015 John Wiley & Sons, Ltd.