Experimental and theoretical modeling of Fe-, Co-, Cu-, Mn-based electrocatalysts for oxygen reduction

Experience gained during efforts towards optimization of noble-metal-free electrocatalysts for oxygen reduction is simultaneously used to understand the chemical and morphological necessities for inducing efficient multi-electron transfer catalysis. The analysis of many preparative experimental steps between the moderately performing metal porphyrines and the highly efficient transition metal- and sulfur-containing pyrolized catalyst material contributes to the following model of the catalyst: The metals function enclosed in nitrogen or graphitic environment where they are shielded against irreversible oxidation. The metals can be exchanged but are not identical in their efficiency. Higher efficiency is achieved, when the function of a binary reaction center is warranted. The carbonization of the environment is critical and provides intercalated metal centers and attached metal complexes in graphite environment for interaction with the nitrogen-chelated partner center in the simultaneously obtained graphene layers. Three alternatives for the binary catalytic center are presented and their relevance discussed on the basis of EXAFS, RAMAN, EPR, Mössbauer and X-ray spectroscopy. A parallel is drawn with the cytochrome oxidase oxygen reduction catalysis, which is proposed to proceed according to roughly the same mechanism.     

金属矿中钨钼铋检测方法研究综述

我国多金属矿中钨钼铋能否高效率的开发利用,提高其检测水平是至关重要的一部分。对金属矿中钨、钼及铋的检测方法进行了综述,为其检测提供有效参考。     

Drying,storage, and preparation of copra for extraction of oil

Various methods are used in drying copra. Because of costs, fuel oil and electricity are avoided by copra producers. Sun-drying remains as a cheap practical way of drying. Direct drying kilns rely on direct contact of combustion gases with coconut meat and produce a generally inferior grade of copra. Indirect drying kilns produce excellent copra. Various preparatory equipment may be used satisfactorily. A new copra oil mill will be most economically designed for handling copra as the main raw material. If, however, an existing oil mill is to diversify to include copra as new raw material, only minor equipment changes are needed. By 1980, copra will almost disappear as an export item, because the coconut producing countries will press and extract coconut oil domestically. The coconut-producing countries hope to obtain better quality of products, improve profit, and contribute to local economy by using local resources.     

Novel,one-step,chromate-free coatings containing anticorrosion pigments for metals—An overview and mechanistic study

The concept of superprimers, i.e., primers for metals with the conversion coating built in, has proven to be feasible. Such primers do not require a chromate (or other) conversion treatment of the metal and can be applied on any bare metal. The VOC content in the primer is kept low by using water-dispersed organic resins. Because of the high concentration of organofunctional silanes contained in the superprimer, its adhesion, both to the substrate and to overcoats, is excellent. The corrosion resistance of the primer can further be improved by adding corrosion-inhibiting pigments such as micronized zinc phosphate into the formulation. The corrosion protection performance of these coatings has been evaluated using performance tests and electrochemical methods. The primers have also been characterized with a variety of surface analytical methods. It will be shown that 2000 h of salt spray resistance has been obtained with the primers both on AA2024-T3 and HDG steel. This study will mainly present an overview of the chromate-free primers studied in our laboratory and will attempt to explain the mechanism by which one of the coatings, the epoxy–acrylate-based primer deposited onto aluminum, protects the metal from corrosion.     

Melting point,solidification, and consistency

Summary There are probably as many methods or variations of methods for melting points, solidification, and consistency as there are producers in the fats and oil industry. I have tried to review the more important ones. The interpretation of results and importance attached to each test will vary widely from producer to producer. My presentation and interpretation have been primarily of methods used by our company and related to the shortening field. In our experience the data obtained from Wiley Melting Points, Penetration Values, and % solids from dilations are the primary controls for the consistency of our products.     

A Review of Research in Materials,Modeling and Simulation,Design Factors,Testing, and Measurements Related to Electromagnetic Interference Shielding

This paper summarizes and reviews research in electromagnetic interface (EMI) shielding based on the review of over 300 articles which are presented in four separate categories. It will be noticed, however, that some articles are cited in more than one category. At the end of each subcategory. a summary is given for easy reference. A table relating each subcategory to the given references at the end of this paper is also supplied. The document comprises a comprehensive study of basic concepts in EMI shielding, analytical and numerical modeling techniques, test methods and instrumentations, material selection, and factors involved in shielding degradation. Cost comparison for various shielding techniques, and the advantages and disadvantages of using the different types of shielding materials and testing methods are reviewed.     

Growth,doping and applications of cubic boron nitride thin films

This article reviews the growth techniques and growth parameters for the formation of cubic boron nitride (c-BN) thin films. It is generally accepted that the impact of energetic ions or neutral atoms is crucial to achieve c-BN film growth. Furthermore, c-BN nucleation is only observed within certain thresholds for the deposition parameters, including the substrate temperature. However, the temperature threshold exists only for the nucleation and not for the growth of c-BN. We will show that three independent characterization methods are necessary for the non-ambiguous identification of the c-BN phase within BN films. The cylindrical thermal spike model developed to describe the formation of diamond-like phases by ion deposition can be used to explain the c-BN nucleation and growth. A short introduction and the basic ideas of this model will be given. Finally, possible tribological applications of c-BN films and the doping of c-BN films will be discussed.     

Importance,Organization and Evaluation of Interlaboratory Tests

The importance of "precise"test values and their verification is growing in every industry throughout the world. Interlaboratory studies constitute a basis for this.The high expenses and mathematical work required to carry out proper interlaboratory studies are frequently considered reasons not to conduct such studies. This makes it all the more important to emphasize the various advantages of an accurate interlaboratory study. In addition to providing precision data for the test method,it is also possible to carry out laboratory evaluations,which is important for accredited test laboratories. Furthermore,existing test methods can be optimized,reference material can be obtained,and test methods can be compared. Optimized test instructions can also be generated using the findings and precision data. These advantages will be described in detail by means of examples below.     

Circular Nucleic Acids: Discovery,Functions and Applications

Circular nucleic acids (CNAs) are nucleic acid molecules with a closed-loop structure. This feature comes with a number of advantages including complete resistance to exonuclease degradation, much better thermodynamic stability, and the capability of being replicated by a DNA polymerase in a rolling circle manner. Circular functional nucleic acids, CNAs containing at least a ribozyme/DNAzyme or a DNA/RNA aptamer, not only inherit the advantages of CNAs but also offer some unique application opportunities, such as the design of topology-controlled or enabled molecular devices. This article will begin by summarizing the discovery, biogenesis, and applications of naturally occurring CNAs, followed by discussing the methods for constructing artificial CNAs. The exploitation of circular functional nucleic acids for applications in nanodevice engineering, biosensing, and drug delivery will be reviewed next. Finally, the efforts to couple functional nucleic acids with rolling circle amplification for ultra-sensitive biosensing and for synthesizing multivalent molecular scaffolds for unique applications in biosensing and drug delivery will be recapitulated.     

SHS-produced Fe-(TiMo)C master alloy for reinforcement of manganese steel

Some steels and alloys, such as the austenite of Hadfield-type manganese steels, are very ductile, tough, and deformable, so that the industrial parts made of these materials often suffer marked geometric deformations during their service life. The problem can be resolved by reinforcing the austenitic matrix with hard, microscopically dispersed ceramic particles such as TiC. Titanium monocarbide, TiC, very hard and stable at room/high temperatures, can be readily fabricated by SHS from elementary Ti-C powders as raw materials. However, these ceramic products are prone to coalescence and have poor wettability in a molten bath, so that the product yield and subsequent property improvement are very low. These drawbacks have been overcome by synthesizing the Fe-(TiMo)C master alloy, that is, (TiMo)C complex carbide particles embedded into a metallic (Fe) matrix, which will significantly improve the mechanical properties of final product. Another goal of this work is substituting expensive raw materials (titanium, molybdenum, and iron powders) by low-cost FeTi and FeMo alloys. The results showed that manganese steels can be successfully reinforced with particles of the SHS-produced master alloy. It has been proved that the use of FeTi and FeMo for the synthesis of master alloy not only satisfies all technical requirements but also significantly reduces the production cost, thus satisfying rigorous economical needs.     

Optimal Conditions for Fatty Acid Distillation and Fractionation in Relation to Energy Consumption,Product Quality,Yield and Environmental Load

Fatty acid quality in industrial distilling and fractionating depends to our observations on precut conditions in relation to deaeration, dehydration, decoloring and deodorisation as well as on sensitive heating methods in main and pitch stages. For precut separation effective counter current film type evaporation dephlegmation system is running at 100 to 200 torr, so that used open steam will be condensed. So far as separation stages are needed, film type columns of very low pressure drop will be used.     

Remarks on the passivation of reduced Cu-, Ni-, Fe-, Co-based catalysts

Catalysts containing metals such as Cu, Ni, Fe, Co in their reduced state are often subjected to passivation procedures prior to characterization. Passivation with N₂O or O₂ to create a protective oxide layer also results in a certain degree of sub-surface oxidation. The heat released during oxidation is a critical parameter. The extent of bulk oxidation depends on the type of oxidant as well as on the size of the metal particles, as shown for copper catalysts. The final, meta-stable passivation layer requires a certain thickness to sustain exposure to ambient atmosphere. The encapsulation of metal particles in carbon is an efficient method for preserving the metallic state, as demonstrated for metallic nickel and iron with carbon nanofibers. The use of passivated samples for characterization of the active, i.e., reduced, catalyst has limited value.     

燃煤电厂镁法脱除烟气中SO2的研究现状与展望

目前,火力发电是许多国家主要的发电方式,控制SO₂排放是治理烟气中污染物的重要工作。本文介绍了目前电厂有应用业绩的几种镁法脱硫技术,并指出现有镁法脱硫方法的弊端,继而提出未来镁法脱硫的发展方向,即基于氧化镁脱硫剂的干法以及半干法脱硫可能会在未来电厂脱硫中得到较大规模的应用。文章指出脱硫效率低是阻碍干法发展的一大问题,而对脱硫剂改性则是提高干法脱硫效率的根本办法之一,将副产品资源化是降低脱硫成本,弥补吸附剂改性费用的有效方法。针对目前日趋严峻的环保要求,现有电厂污染物治理方法针对性过强,未来,实现多烟气一体化脱除是烟气污染物治理的发展方向,干法脱硫可以为多污染物一体化脱除打下基础。本文旨在为推动氧化镁法脱硫提供参考。     

Qualitative and quantitative analysis of multilayer coextruded and laminated films

The packaging industry is undergoing a period of rapid expansion in the use of multilayer and coextruded containers. This presents a challenge to the analytical chemist, who must characterize these extremely complex structures. The state of the art for the production of the new generation of containers, including methods, materials and structures, will be briefly reviewed. The applications of such containers and the motivations for the analysis of the structures involved will also be reviewed. The methods for the analysis of these multilayer and coextruded structures will then be considered in detail. The characterization of the surfaces involved will be emphasized. Techniques to identify, quantify, and determine the orientation of the structures will be discussed. The use of infrared spectroscopy (with emphasis on internal reflection spectroscopy) for the identification of the materials in these structures will be discussed. Also, the use of infrared spectroscopy in quantitatively determining the composition and orientation of the structures will be presented. The use of optical microscopy and combined microscopy/infrared spectroscopy for the quantification of the layer structures will be discussed. The use of auxiliary techniques for the completion of the analysis of the complex layer structures will be presented.     

Photopolymerization of biomaterials: issues and potentialities in drug delivery,tissue engineering,and cell encapsulation applications

Photopolymerization is a widely explored technology that has recently been recognized to have also great potentialities in the biomedical field. This paper aims to provide a general overview of this technology by briefly describing materials and methods used to produce linear or crosslinked polymer networks for drug delivery, tissue engineering and cell encapsulation. In addition, potentialities and areas of investigation that are not fully explored but that could provide solutions for better control over the technology when applied to the biomedical field will be indicated as well. Copyright © 2006 Society of Chemical Industry     

Characterization of nanostructured pristine and Fe- and V-doped titania synthesized by atomization and bubbling

Pristine titania and vanadium- or iron-doped titania particles were synthesized in a tubular furnace reactor. Each sample was synthesized by different injection methods either by the atomizer or bubbler. Titania, which was made by the bubbling method, showed agglomerates with around 10 nm primary particles. Atomization, on the other hand, resulted in the mixture of 100 nm particles and 10 nm particles. Iron dopants introduced by the atomizer showed hematite crystals along with anatase while vanadium did not show any vanadium related crystals. Atomized vanadium formed stable particles and the collision with titania resulted in V-doped titania. Substituted vanadium promoted sintering of titania even at a low concentration. Bubbled vanadium condensed on the surface of titania particles because of its low melting point and small size, and hence it did not affect the morphology of titania significantly.     

Relations between pulsed NMR,wide-line NMR,and dilatometry

Hitherto, solid fat contents often have been expressed as dilatations. Since the development of pulsed NMR into a quick and accurate method for the determination of the solid fat content, while wide-line NMR still is being used, accurate equations are needed to enable conversion from dilatations to NMR values and vice versa. The inaccuracies arising when NMR values are converted into dilatations are almost equal for the various NMR methods. The direct pulse method in which one mean solid fat factor f is used is the most attractive method to replace dilatometry. For further reduction of the standard deviation when converting NMR values into dilations and vice versa, it will be necessary to split up the fats into groups with similar compositions.     

Report of the instrumental techniques committee AOCS, 1971–72

Summary As described in this report, the Instrumental Techniques Committee has in various stages of progress several methods which will be proposed for adoption as official methods of the AOCS. For convenience, these proposed methods and their present status are summarized in Table II. Report of collaborative work from Government, Industrial and Academic Laboratories by members of ARS, USDA, Southern and Eastern Marketing and Nutrition Divisions; Anderson Clayton and Co., Food Division; Unilever Research; and A.E. Staley Mfg. Co.     

Harmonised standards for mechanical testing of composites,

Abstract

The long awaited harmonisation of international standards for composite materials is being achieved. Six new EN ISO Standards (EN ISO 527–4; 527–5; 14 125; 14 126; 14 129; and 14 130) have been extensively harmonised with equivalent ASTM standards for mechanical properties. In the drafting of these standards, a common format was adopted to aid understanding and by using a common procedure for, for example, end tabbing, data quality can be improved and costs reduced. Considerable savings can be achieved by the use of a single evaluation based on international test methods, compared with undertaking 10 similar evaluations. In addition, the data are available earlier and to a wider audience. For European countries these standards are particularly important as they will replace equivalent national standards. However, for all users the cost savings, improved databases, and earlier availability of data will have significant commercial and technical benefits. Future refinements to the harmonised test standards can be referenced against the new standards. Further methods are in progress to provide improved databases.     

Identification and quantification of oxidized organic aerosol compounds using derivatization,liquid chromatography,and chemical ionization mass spectrometry

A systematic approach for identifying and quantifying molecular components of complex organic aerosol mixtures is presented. The approach combines methods developed previously for derivatizing carbonyl, hydroxyl, carboxyl, and ester functional groups, which are commonly present in oxidized organic aerosol, with liquid chromatography, UV detection, and chemical ionization-ion trap mass spectrometry. The original derivatization-spectrophotometric methods were modified for compatibility with liquid chromatography and then evaluated by analyzing a variety of standard compounds that contain one or more functional groups. Detection limits for carbonyl, hydroxyl, carboxyl, and ester analysis are approximately 0.003, 0.02, 0.01, and 1 nmole, respectively. Mass spectral analysis of derivatives using isobutane and ammonia as reagent gases for chemical ionization can be used to determine compound molecular weight, and characteristic fragmentation patterns provide structural information for use in compound identification. The methods will be useful for analyzing the chemical composition of secondary organic aerosol (SOA) formed in laboratory studies to obtain information needed to develop quantitative reaction mechanisms that can be incorporated into atmospheric models to better predict the formation, composition, and fate of SOA.

Copyright © 2017 American Association for Aerosol Research