Measurements of pitting corrosion currents of zinc in near neutral media

Using a simple model cell the susceptibility of the zinc electrode to pitting corrosion by SO₄²⁻, SO₃²⁻, S₂O₃²⁻ and S²⁻ anions were examined in naturally aerated carbonate solutions. It was found that, pitting started after an induction period, τ, which depended on the type and concentration of the aggressive and passivating anions. The pitting corrosion current increased with time until steady state values were attained. These values depended on both the type and the concentration of the passivating and pitting anions. For the same concentration of the passivating anions, the corrosion current varied with the concentration of the aggressive anion according to the relation: logi_pit.=a₁+b₁logC_agg. At a constant concentration of the aggressive anion, the corrosion current varied with the concentration of the passivating anions according to: logi_pit.=a₂−b₂logC_pass. The constants a₁ (a₂) and b₁ (b₂) were determined for all the systems studied. From the values of a₁ the corrosivity of the sulphur-containing anions is found to decrease in the order SO₄²⁻>SO₃²⁻>S₂O₃²⁻>S²⁻.     

Hydrogen doping effects in the sulfidation of molybdenum

The kinetics of molybdenum sulfidation have been studied in H₂S/H₂ gas mixtures at 1173 K. Sulphur partial pressures were controlled by the equilibrium reaction between H₂S, H₂, and S₂. Pure molybdenum metal was sulfidized at a fixed value of 133 Pa with varying H₂S and H₂ partial pressures, and at fixed H₂S partial pressures of 5.06×10 pa⁴ and 5.06×10³ Pa with varying hydrogen and sulfur partial pressures. The gravimetric sulfidation kinetics were parabolic under all conditions. X-ray diffraction analysis of the reaction product scale revealed the presence of MoS₂ only. The sulfide scales were of uniform thickness, had a compact morphology, and were tightly adherent to the metal. The sulfidation rates at a fixed sulfur partial pressure increased with increasing hydrogen partial pressure. At fixed values, the rate was almost constant at high values, but increased substantially as was decreased. Defect models for hydrogen dissolution in MoS₂ are developed and compared with the experimental results. It is concluded that the sulfidation rate effects are due to hydride anion occupation of interlayer sites in MoS₂.     

大体积直接进样-离子色谱法测定高纯水中痕量阴离子

建立了一种采用大体积直接进样－离子色谱测定高纯水中痕量阴离子的新方法。采用高容量的IonPac AS9HC阴离子交换色谱柱，以11.5mmol/L Na2CO3为淋洗液，流速1.0mL/min,可在20min内同时测定7种常见阴离子，采用新型的阴离子Atlas电解抑制器，可显著降低基线噪音，结合500μL定量环，对F^-,Cl^-,NO2^-,Br^-，NO3^2-，PO4^3-,SO4^2-的检测限分别为0.09μg/L，0.20μg/L,0.46μg/L,0.89μg/L,0.76μg/L,0.96μg/L,0.92μg/L。应用此方法对高纯水中的痕量阴离子进行了测定。     

Bis-imidazolium type ion-exchange resin with poly(HIPE) structure for the selective separation of anions from aqueous solutions

ABSTRACT

The aim of this work was to obtain and characterize the selectivity of a new type of ion-exchanger – porous highly basic monolith with high internal phase emulsion (HIPE) structure. Poly(HIPE)ViM monolith of bis-vinylimidazolium salts was prepared in a water-in-oil-in-water emulsion (W₁/O/W₂). The structure of the resulting HIPE polymer was confirmed using scanning electron microscopy (SEM). Ion-exchange ability and the selectivity of monolithic anion-exchanger were tested towards the following inorganic anions: F^?, Br, Cl^?, NO₃^?, SO₄^2-, Mo₇O₂₄^6-, PO₄^3-; and organic anions: malate, citrate, malonate, tartate, lactate and oxalate. The concentration of anions before and after the sorption was measured using ion chromatography.     

Effect of monovalent anions on cationic Gemini micro-emulsion

Micro-emulsion usually consists of water, oil, surfactants and co-surfactants, and each component has an effect on the phase behavior and solubilization of the micro-emulsion. When the surfactant in the micro-emulsion system is quaternary ammonium cationic Gemini surfactant, the surfactant mainly combines with the anions in the salt. With the increase of salt concentration, the phase transformation of Winsor I → Winsor Ⅲ → Winsor Ⅱ occurred, but the optimum salinity and salt width are different because of the type of salt. The effects of 5 different kinds of monovalent anions, including C₆H₅SO₃^-, I^-, Br^-, NO₃^- and Cl^-, on the phase behavior and solubilization of quaternary ammonium cationic Gemini micro-emulsion are researched by Winsor phase diagram. It is found that the effects of organic anions C₆H₅SO₃^- and I^- on the phase behavior and solubilization of quaternary ammonium cationic Gemini micro-emulsion are most significant, and the effects of Br^-, NO₃^- and Cl^- are less significant. Meanwhile, when the optimum solubilization is achieved, the amount of sodium benzoate is the least, indicating that the organic anion has stronger self-organization behavior with quaternary ammonium cationic Gemini surfactants.     

Hybrid plasma bonding of germanium and glass wafers at low temperature

Hybrid plasma bonding (i.e., sequentially plasma activation followed by anodic bonding) has been demonstrated for germanium and glass wafers for the first time. Void-free interface with high bonding strength has been observed at 200 °C. This improved quality is attributed to reduced surface roughness and increased hydrophilicity of sequentially activated germanium and glass. Three layers caused by reactions of OH molecules between the highly reactive surfaces after plasma activation and opposite migration of cations and anions are observed across the interface.     

铈诱导细胞凋亡过程中O-2·对ERK-like激酶的调控

对1 mmol·L^-1Ce⁴⁺诱导东北红豆杉细胞凋亡中ERK-like和O^-₂·的变化规律及其信号调控进行了分析和研究.结果表明,一相对分子质量约为46×10³的ERK-like激酶在诱导5 min时被快速激活,60 min时达到对照水平的2.1倍,并在120 min内持续激活,诱导240 min后ERK-like下调到对照水平的43%,到48 h下调到对照的25%.Ce⁴⁺诱导O^-₂·迅速产生,并有两次迸发峰分别出现在3.7～4 h和7 h.在Ce⁴⁺诱导前2 h分别加入5 μmol·L^-1和10 μmol·L^-1DPI有效抑制了O^-₂·迸发, 并且显著提高和延长了ERK-like磷酸化水平, 诱导60 min时ERK-like达到对照水平的7.3和18.8倍, 240 min时达到对照的9.6和10.5倍.这些结果揭示ERK-like的激活和O^-₂·迸发在诱导早期应是相互独立的信号事件,诱导约4 h后O^-₂·大量迸发对ERK-like的激活有明显信号负调控作用,并通过ERK-like的下调介导了凋亡信号传递.     

A comparison of the change from inhibiting to enhancing anions in the electrochemical oxidations of ethylene glycol and formaldehyde

Techniques dealing with inhibiting anions have previously been employed to measure their properties. The present approach is to change the behavior of inhibiting anions. Anions, which have long been considered to inhibit reactions, are shown to enhance some electrochemical reaction rates. Fluoroborate, nitrate, and (hydrogen) sulfate are separately shown to increase the current response of the electrochemical oxidation of formaldehyde. The reaction rate of the oxidation of ethylene glycol is increased but for a restrictive set of conditions. Experimental data, as well as theoretical considerations lead to the conclusion that adsorption of the added anions is the slow step of the process that increases the reaction rate. The differences in the response of ethylene glycol and formaldehyde follow well-documented changes of surface CO. These observations are consistent with general properties of the step in the part of the mechanism on the electrode surface that enhances the reaction rate.     

Performance of Chelating Resins Containing Calixpyrroles in Sorption of Anions

Abstract

Characteristics and sorptive properties of three series of chelating resins having incorporated calixpyrrole ligands within their structures is reported. Two sets of resins were obtained by immobilization of calix[4]pyrrole or calix[4]pyrrole[2]thiophene on the beads of crosslinked (vinylbenzyl chloride)/divinylbenzene copolymer. The third series was synthesized by condensation of calix[4]pyrrole with formaldehyde. All resins displayed sorptive properties towards halide anions and cyanides in a non‐aqueous medium (acetonitrile). The resins displayed superior selectivity for fluoride anions and the selectivity sequence for the uptake of other anions depended on their ionic radii. The bigger ligand, calix[4]pyrrole[2]thiophene, showed an enhanced affinity for bigger anions, including iodide, which was not observed in the case of calix[4]pyrroles. Thus, the resin containing the larger ligand complexes the whole range of anions, but with poorer selectivities.     

Planning of Accelerated Life Tests With Dependent Failure Modes Based on a Gamma Frailty Model

Accelerated life tests (ALT) provide timely information on product reliability. As product complexity increases, ALT often generate multiple dependent failure modes. However, the planning of an ALT with dependent failure modes has not been well studied in the literature. This article investigates the statistical modeling and planning of ALT with multiple dependent failure modes. An ALT model is constructed. Associated with each failure mode there is a latent lifetime described by a log-location-scale distribution, and the statistical dependence between different failure modes is described by a Gamma frailty model. The proposed model incorporates the ALT model with independent failure modes as a special limiting case. We obtain the c-optimal test plans by minimizing the large-sample approximate variance of the maximum likelihood estimator of a certain life quantile at use condition. The method is illustrated by developing ALT plans for field-effect transistors with competing gate oxide breakdown. A sensitivity analysis is performed to investigate the robustness of the optimal ALT plan against misspecification of model parameter values. This article has supplementary materials that are available online.