介绍了Kirk—Othmer Encyclopedia of Chemical Technology（化工技术百科全书）（第五版）电子图书网络版数据库，并对该数据库使用方法和检索途径作出了说明，且结合实例简单地介绍了该数据库的检索方法。

Kirk-Othmer Encyclopedia of Chemical Technology数据库介绍及实例

Supported Catalysts Weiting Yu,† Marc D. Porosoff,† and Jingguang G. Chen*,†,‡,§ †Catalysis Center for Energy Innovation, Department of Chemical and Bimolecular Engineering, University of Delaware, Newark, Delaware 19716, United States ‡Department of Chemical Engineering, Columbia University, New York, New York 10027, United States Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, United States

Review of Pt-based bimetallic catalysis: from model surfaces to supported catalysts.

The electronic properties of Pt nanoparticles deposited on CeO(2)(111) and CeO(x)/TiO(2)(110) model catalysts have been examined using valence photoemission experiments and density functional theory (DFT) calculations. The valence photoemission and DFT results point to a new type of "strong metal-support interaction" that produces large electronic perturbations for small Pt particles in contact with ceria and significantly enhances the ability of the admetal to dissociate the O-H bonds in water. When going from Pt(111) to Pt(8)/CeO(2)(111), the dissociation of water becomes a very exothermic process. The ceria-supported Pt(8) appears as a fluxional system that can change geometry and charge distribution to accommodate adsorbates better. In comparison with other water-gas shift (WGS) catalysts [Cu(111), Pt(111), Cu/CeO(2)(111), and Au/CeO(2)(111)], the Pt/CeO(2)(111) surface has the unique property that the admetal is able to dissociate water in an efficient way. Furthermore, for the codeposition of Pt and CeO(x) nanoparticles on TiO(2)(110), we have found a transfer of O from the ceria to Pt that opens new paths for the WGS process and makes the mixed-metal oxide an extremely active catalyst for the production of hydrogen.

A new type of strong metal-support interaction and the production of H2 through the transformation of water on Pt/CeO2(111) and Pt/CeO(x)/TiO2(110) catalysts.

Surface Chemistry of Ruthenium Dioxide in Heterogeneous Catalysis and Electrocatalysis: From Fundamental to Applied Research

Monolayer bimetallic surfaces: Experimental and theoretical studies of trends in electronic and chemical properties

Reaction of atomic oxygen with a Pt(1 1 1) surface: chemical and structural determination using XPS, CAICISS and LEED

Objective The objective of this study was to evaluate the relative level of dentin tubule occlusion and dentin mineralization conferred by a 5% w/w calcium sodium phosphosilicate (45S5)/1450 ppm fluoride toothpaste in comparison to a range of commercial toothpastes reported to occlude dentin tubules. Methods Two separate experiments were employed to (i) determine the level of dentin tubule occlusion, and (ii) explore the change in dentin mineralization conferred by a number of marketed toothpastes and controls, following twice-daily brushing in a longitudinal, acid challenge-based, dentin disc model. In Study I, 192 bovine dentin discs, polished and etched in citric acid to provide a smooth dentin surface with patent tubules, were divided into eight treatment groups and subjected to brushing with one of seven test toothpastes or deionized water over four days. Prior to and between treatments, the dentin samples were stored in saliva. The test products were fluoridated toothpastes containing: calcium sodium phosphosilicate (45S5); strontium acetate; arginine/calcium carbonate; amine fluoride; calcium sulphate/diphosphate; stannous fluoride; casein stabilized amorphous calcium phosphate toothpaste; and a non-occluding negative control, deionized water. At the end of each treatment day (1 though 4), one group of samples was removed for scanning electron microscopy (SEM) analysis and graded on a categorical visual scale to assess the level of dentin tubule occlusion. A subset of samples from Study I was also cross-sectioned and examined using SEM. For the exploratory mineralization study (Study II), 120 dentin specimens were prepared as previously described and divided into four treatment groups consisting of A, C, F, and a tooth sealant varnish (I), and subjected to the treatment regimen described in Study I. The dentin samples were assessed for changes in surface microhardness using an indenter fitted with a Knoop probe and the level of dentin occlusion. Results In Study I, the 5% w/w calcium sodium phosphosilicate/1450 ppm fluoride-containing toothpaste (A), the stannous fluoride-containing toothpaste (F), and the strontium acetate-containing toothpaste (B) delivered the highest level of occlusion following four days of twice-daily brushing and a twice-daily acid challenge on days 3 and 4. Surface analysis of a subset of Study I samples, following four days of treatment, indicated that the 5% w/w calcium sodium phosphosilicate/1450 ppm fluoride-containing toothpaste formed a distinct layer at the surface of dentin. For Study II, surface microhardness analysis revealed that the 5% w/w calcium sodium phosphosilicate/1450 ppm fluoride-containing toothpaste (A) delivered significantly more surface hardening then the control or competitor toothpastes on days 2 and 4. Conclusion Desensitizing toothpastes reported to operate by an occlusion mechanism have been observed to confer varying degrees of dentin tubule occlusion and dentin mineralization over four days in an acid challenge-based in vitro model. A 5% w/w calcium sodium phosphosilicate/1450 ppm fluoride-containing toothpaste was observed to impart a significant level of dentin tubule occlusion and surface hardening, and form durable occlusive deposits following four days of twice-daily brushing in vitro.

A comparative in vitro study investigating the occlusion and mineralization properties of commercial toothpastes in a four-day dentin disc model.

https://escholarship.org/content/qt5fz1r3k7/qt5fz1r3k7.pdf?t=osxbn1

Strontium effects on root dentin tubule occlusion and nanomechanical properties.

This Article reports the use of scanning electrochemical microscopy (SECM) for the quantitative study of acid-induced dissolution. An ultramicroelectrode (UME) is used to generate a flux of protons galvanostatically just above a sample surface, creating controlled acid challenges relevant to acid erosion. The electrochemical technique produces etch features in the sample, which are characterized by white light interferometry (WLI). The technique has been applied to bovine enamel where understanding the kinetics of dissolution is important in the context of acid erosion. Dissolution has been observed as a fast process, but the high rates of mass transport in SECM allow the surface kinetics of dissolution to be evaluated. Key attributes of SECM for these studies are the ability to deliver high, controllable, and local acid challenges in a defined way and that multiple dissolution measurements can be performed on one sample, eliminating intersample variability effects. A novel moving boundary finite element model has been designed to describe the etching process, which allows the etch kinetics to be evaluated quantitatively, simply by measuring the size and shape of etch features over time.

Charles R. Parkinson

Papers

Reaction of atomic oxygen with a Pt(1 1 1) surface: chemical and structural determination using XPS, CAICISS and LEED

A comparative in vitro study investigating the occlusion and mineralization properties of commercial toothpastes in a four-day dentin disc model.

Strontium effects on root dentin tubule occlusion and nanomechanical properties.

Scanning electrochemical microscopy as a quantitative probe of acid-induced dissolution: theory and application to dental enamel.

High-resolution non-destructive 3D interrogation of dentin using X-ray nanotomography.