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Reference work by virtue of its nature deals with all kinds of information in all disciplines and attempts to provide it to all sorts of people for all sorts of reasons. While the very definition of reference service is a matter of controversy, we will open with an arbitrary one—the actions, and the administration of those actions, by which we assist patrons in their discovery and use of appropriate portions of mankind's graphic record. Note that the definition doesn't say appropriate to what—appropriate to the education, entertainment, edification, growth, etc. of the patron. These are intentionally left out because they are all relevant to our role, and the role of the library. Further, it is very difficult to separate them— who is to say a person well entertained isn't learning something? Who is to say there is not entertainment value in something learned? With this much diversity in the character of reference work, how can its literature be anything but diverse? Therefore we looked at the topic carefully but selectively to provide some semblance of order. Breadth is emphasized more than exhaustive depth. This will not be an enumeration of research studies, publications, or names of all writers on the subject. Instead, it is an overview of the primary issues that have been prominent in the literature and in the field during the last 10–15 years.
Sputtering was utilized to deposit polycrystalline Cu and CrN films sequentially onto Si(100) substrates, forming specimen assemblies in which predominantly 〈 111 〉 oriented Cu thin films of varying thicknesses were confined between Si and CrN. Cylindrical micro-pillars of CrN/Cu/Si(100) were fabricated through focused ion beam milling, with the interfaces either normal to the axial direction or at an inclination of 45°. Axial compression loading of the micro-pillars produced extensive plasticity within the thin Cu interlayers in both cases, but with distinctly different responses involving combined compression and shear when the interfaces are normal to the compression axis and constrained shear when the interfaces are inclined. Significant size effects were observed, offering new experimental evidence of scale-dependent plasticity for thin film layers, and new experimental test cases for non-local plasticity theories.
Die Peptidlänge beeinflusst die Form der mit Kraftmikroskopie (AFM) aufgenommenen Grate der Langmuir-Blodgett-Filme aus amphiphilen Peptiden: Wohlgeordnete LB-Filme (links) können aus einem 14-gliedrigen amphiphilen Peptid, weniger geordnete LB-Filme mit einem breiteren Gitter (rechts) aus einem 18-gliedrigen Peptid hergestellt werden. Die gezeigten Bilder mit einer Auflösung von 100×100 nm wurden mit AFM unter Verwendung von Spitzen aus Kohlenstoff-Nanoröhren erhalten. Supporting information for this article is available on the WWW under http://www.angewandte.com or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
The plastic buckling of columns is explored in a regime where plastic wave propagation and lateral buckling are nonlinearly coupled. Underlying the work is the motivation to understand and quantify the dynamic crushing resistance of truss cores of all-metal sandwich plates where each truss member is a clamped column. Members are typically fairly stocky such that they buckle plastically and their load carrying capacity decreases gradually as they buckle, even at slow loading rates. In the range of elevated loading rates of interest here, the columns are significantly stabilized by lateral inertia, resisting lateral motion and delaying buckling and loss of load carrying capacity to relatively large overall plastic strains. The time scale associated with dynamic axial behavior, wherein deformation spreads along the column as a plastic wave, is comparable to the time scale associated with lateral buckling such that the two phenomena are coupled. Several relevant problems are analyzed using a combination of analytical and numerical procedures. Material strain-rate dependence is also taken into account. Detailed finite element analyses are performed for axially loaded columns with initial imperfections, as well as for inclined columns in a truss core of a sandwich plate, with the aim of determining the resistance of the column to deformation as dependent on the loading rate and the relevant material and geometric parameters. In the range of loading rates of interest, dynamic effects result in substantial increases in the reaction forces exerted by core members on the faces of the sandwich plate with significant elevation in energy absorption.
The utility and robustness of the mechanics of materials is illustrated through a review of several recent applications to fracture phenomena, including adhesive failures, the role of plasticity in enhancing toughness in films and multilayers, and crack growth resistance in ductile structural alloys. The commonalty among the approaches rests in a reliance on experiments to provide calibration of the failure process at the smallest scale.
Abstract Endständige Olefine (I) werden durch Behandlung mit Hg(II)‐ Salzen über die Zwischenstufen (II) mit Jonesreagens über (III) zu den Methylketonen (IV) oxidiert.
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCrystallization of Millimeter-Scale Objects with Use of Capillary ForcesJoe Tien, Tricia L. Breen, and George M. WhitesidesView Author Information Department of Chemistry and Chemical Biology Harvard University, Cambridge Massachusetts 02138 Cite this: J. Am. Chem. Soc. 1998, 120, 48, 12670–12671Publication Date (Web):November 18, 1998Publication History Received29 June 1998Published online18 November 1998Published inissue 1 December 1998https://pubs.acs.org/doi/10.1021/ja982246yhttps://doi.org/10.1021/ja982246yrapid-communicationACS PublicationsCopyright © 1998 American Chemical SocietyRequest reuse permissionsArticle Views460Altmetric-Citations68LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Crystal structure,Crystallization,Crystals,Hydrophobicity,Liquids Get e-Alerts
The contribution of plastic deformation to the effective work of fracture is computed for a crack lying along one of the interfaces of a thin ductile layer joining two elastic solids. A model is proposed for the joint whose major parameters are the layer thickness, the elastic-plastic properties of material in the layer, and the work of separation and peak separation stress of the local interface fracture process. A symmetric mode I loading of the joint is considered under conditions where the thickness of the layer and the extent of the plastic zone are small compared with the crack length. The crack growth resistance behaviour is computed, with special emphasis on the steady-state work of fracture. The role of the layer thickness in the development of the plasticity contribution to toughness is detailed. Plastic dissipation is fully realized for layers above a certain thickness, characteristic of a plastic zone dimension, and is negligible when the layer is thin relative to this dimension. Other factors which may effect the effective toughness of the joint, such as modulus mismatch of the layer and adherends and residual stress in the layer, are discussed together with limitations and possible extensions of the model.
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