Electrochemical and ellipsometric study of the oxide films formed on copper in borax solution: Part I: Effect of oxygen

The formation and reduction of passive layers on copper in weakly alkaline solutions saturated with N2 and O2 were studied. Voltammetric and ellipsometric techniques were employed to examine the structural characteristics of the layers formed in the –0.32 to 0.75 V vs RHE potential region. Optical measurements at open circuit potentials (Eoc) were also made to simulate operational conditions. The passive layer consists of a duplex structure: an outer hydrated copper oxide film and an inner dehydrated film. This inner layer is composed of Cu2O with a surface excess of Cu(ii) ions. The growth rate of the oxide layers at controlled potentials is higher in O2 saturated solution. The corrosion resistance of copper depends on the presence of O2 in the electrolyte, on the stirring rate and on the Eoc value.     

Micro-Analysis of ＂Sulfate Salt Weathering Distress on Concrete＂：Ⅱ.Concrete

运用环境扫描电镜、能谱仪和X射线衍射等微观分析手段研究了稳定环境中,半浸泡混凝土试件在硫酸钠和硫酸镁溶液中的劣化破坏特征,以及混凝土碳化对＂混凝土硫酸盐结晶破坏＂的影响。结果表明：粗骨料界面过渡区生成的大量钙矾石和石膏等晶体是引起混凝土试件劣化的原因;在碳化混凝土内发现了硫酸钠结晶破坏现象。     

Coating evaluation and validation of accelerated test conditions using an in-situ corrosion sensor

An in-situ corrosion sensor was used to obtain electrochemical impedance spectroscopy (EIS) measurements on coated panels under a variety of accelerated laboratory test conditions as well as ambient exposure at a Florida beach. Three studies are reported. The first compared the sensor (EIS) measurements taken in a salt fog chamber to those obtained using a clamp-on cell and the conventional remote electrode/immersion approach. For coatings with minimal edge defects, the two methods gave equivalent results. For coatings with edge defects, the sensor was able to detect the defects provided the surface was wet, as in the salt fog chamber. In contrast, the conventional approach was unable to detect defects unless they were within the confines of the clamp-on cell. In the second case, sensor measurements were used to compare coating degradation during salt fog, a cyclic corrosion test, humidity, and immersion to that occurring at a Florida beach. The cyclic corrosion test showed an excellent correlation with beach exposure while the salt fog and other test showed very little correlation, suggesting that the cyclic test is more valid for discriminating coating performance for seacoast exposure. The sensor also indicated that the test could be short-ened by up to 40% without significantly reducing the validity of the test. In the final example, a series of primers and appliqués were evaluated using the cyclic corrosion test. The sensor EIS results allowed a discrimination between the materials sets even though there was little or no visual difference between the specimens. 10260 Old Columbia Rd., Columbia, MD 21046.     

氨合成塔选型

介绍了在合成氨改扩建工程中，选择氨合成塔时应着重考虑的工艺参数和结构设计，并在实际工作中得到验证。     

THEORETICAL ANALYSIS OF THE DIFFUSION PROCESS INSIDE PROLATE SPHEROIDAL SOLIDS

ABSTRACT

A numerical solution of the diffusion equation to describe solute transport inside ellipsoids, assuming a constant difiusion coefficient and a corrective boundary condition, is presented. The difiusion equation in a prolate spheroidal coordinate system was used for a hidimensional case. The finite volume method was employed to discretize the basic equation, utilizing a uniform grid size. The equation was solved irteratively using the Gauss-Seidel method. The effect of Biot number and the aspect ratio of the body on diffusion rate and concentration during the process is presented. Plots are presented for Biot numbers from 0.05 to infinity and aspect ratios of 1.1, 2.0 and 5.0. To investigate the effect of the aspect ratio, different results changing the aspect ratio for Bi= 1.0 are shown. The results show that the model is consistent and it may be used to solve other cases such as those that include cylinder and sphere geometry, and/ or those with variable diffusion coefficients with small modifications.     

Electrochemical Sensors for Nondestructive Evaluation of Adhesive Bonds

An in-situ corrosion sensor based on electrochemical impedance spectroscopy (EIS) has been used to detect moisture ingress into aluminum-aluminum and aluminum-composite adhesive bonds. Both wedge tests and tensile button tests (aluminum-aluminum bonds only) were performed. Upon moisture absorption, the impedance spectra change shape with the low-frequency region becoming resistive. The low-frequency impedance decreases by several orders of magnitude, depending on the adhesive and the experimental conditions. For bonds with stable interfaces, such as phosphoric acid anodized (PAA) aluminum, the absorbed moisture causes an initial weakening of the adhesive resulting in reduced strength or small crack propagation. A substantial incubation time prior to substrate hydration and bond degradation allows warning of potential joint deterioration and enables condition-based maintenance. For bonds with smooth interfaces with little or no physical bonding (mechanical interlocking), crack propagation can proceed interfacially with minimal moisture absorption. A comparison of the incubation times for Forest Products Laboratory (FPL, or sulfuric acid-sodium dichromate) etched surfaces, both bonded to epoxy adhesives and freely exposed to water or humidity at different temperatures, shows that hydration occurs with the same activation energy and, hence, the same mechanism, independent of whether or not the surface is covered with adhesive. However, the pre-exponential factor in the rate constant is dependent on the concentration of free moisture at the interface so that the hydration rate varies by several orders of magnitude.     

Synthesis of 6,6- and 7,7-Difluoro-1-acetamidopyrrolizidines and Their Oxidation Catalyzed by the Nonheme Fe Oxygenase LolO

LolO, a 2-oxoglutarate-dependent nonheme Fe oxygenase, catalyzes both the hydroxylation of 1-exo-acetamidopyrrolizidine (AcAP), a pathway intermediate in the biosynthesis of the loline alkaloids, and the cycloetherification of the resulting alcohol. We have prepared fluorinated AcAP analogues to aid in continued mechanistic investigation of the remarkable LolO-catalyzed cycloetherification step. LolO was able to hydroxylate 6,6-difluoro-AcAP (prepared from N,O-protected 4-oxoproline) and then cycloetherify the resulting alcohol, forming a difluorinated analogue of N-acetylnorloline and providing evidence for a cycloetherification mechanism involving a C(7) radical as opposed to a C(7) carbocation. By contrast, LolO was able to hydroxylate 7,7-difluoro-AcAP (prepared from 3-oxoproline) but failed to cycloetherify it, forming (1R,2R,8S)-7,7-difluoro-2-hydroxy-AcAP as the sole product. The divergent LolO-catalyzed reactions of the difluorinated AcAP analogues provide insight into the LolO cycloetherification mechanism and indicate that the 7,7-difluorinated compound, in particular, may be a useful tool to accumulate and characterize the iron intermediate that initiates the cycloetherification reaction.     

ANTENNAL AND BEHAVIORAL RESPONSES OF GRAPEVINE MOTH <Emphasis Type="Italic">Lobesia botrana</Emphasis> FEMALES TO VOLATILES FROM GRAPEVINE

Grapevine moth Lobesia botrana is the economically most important insect of grapevine Vitis vinifera in Europe. Flower buds, flowers, and green berries of Chardonnay grapevine are known to attract L. botrana for oviposition. The volatile compounds collected from these phenological stages were studied by gas chromatography—mass spectrometry, and the antennal response of L. botrana females to these headspace collections was recorded by gas chromatography—electroantennography. The compounds found in all phenological stages, which consistently elicited a strong antennal response, were pentadecane, nonanal, and -farnesene. In a wind tunnel, gravid L. botrana females flew upwind to green grapes, as well as to headspace collections from these berries released by a piezoelectric sprayer release device. However, no females landed at the source of headspace volatiles, possibly due to inappropriate concentrations or biased ratios of compounds in the headspace extracts.     

Evaluation of interconnected production sites taking into account multidimensional uncertainties

The production sites of international companies are becoming increasingly interconnected. Due to the uncertainty of multiple factors, determining a location is a strategic choice entailing high financial risk. For this reason, a method for site evaluation was developed allowing multidimensional, i.e., both quantitative and qualitative, uncertainties to be taken into account. The uncertainties are modeled with both probability and fuzzy-set theory and integrated into a modular-structured monetary calculation model. For the analysis and interpretation of evaluation results, methods have been developed which allow risk assessment. The developed method provides a way to handle existing location risks and can thus ensure the success of manufacturing companies in the long term.     

卤代烃的制备工艺

介绍了一种液相法生产分子式为ＣＡＲ＾１Ｒ＾２ＣＢＲ＾３Ｒ＾４（此外的Ｒ＾１,Ｒ＾２、Ｒ＾３和Ｒ＾４指代意义如专项说明中所定义）的卤代烷加成物的工艺,是将相应的卤代烷烃（ＡＢ）与相应的烃（ＣＲ＾１Ｒ＾２＝ＣＲ＾３Ｒ＾３）在催化的存在下于溶剂中进行反应,所用的催化剂组成：（１）至少有一种含一价铜;（２）至少有一种为离子促进剂,选自卤代铵、吡啶或卤代吡啶及（ＭＱ４）Ｙ型的四价盐（Ｍ是元素周期表中ＶＡ族元素,如Ｎ、Ｐ、Ａｓ、Ｓｂ或Ｂｉ,Ｑ为Ｃ１－Ｃ１８烷烃、Ｙ为氯、溴或碘）。还介绍了用上述工艺制得的加成产物与ＨＦ反应制备一些氢氟烃的工艺,该工艺是在二晴或环化碳酸酯溶剂中进行,使反应混合物分成两相。