Oliver Miesbauer  Marion Schmidt  Horst‐Christian Langowski Prof. Dr. 《真空研究与实践》2008,20(6):32-40

Mass transport through layer systems consisting of polymers and thin inorganic layers Flexible layer systems from polymeric substrates, thin inorganic layers deposited by vacuum coating and additional polymeric layers are frequently in use to obtain high barrier properties, predominantly against oxygen and water vapour. Especially in cases where additional polymeric coatings are able to fill defects in the inorganic layers, barrier properties of the resulting layer systems show a stronger dependence on their thickness. For the transport of condensable substances, especially of water vapour, an additional porosity in the sub‐nm‐size can be assigned to the inorganic layers. This, however, has a negligible effect on gas permeation. Multilayer structures made from substrates and alternating polymeric and inorganic layers show much better barrier properties than single polymeric substrates coated with single inorganic layers. These improvements, however, are less than previously reported here. Moreover, also in these cases, the condensation of water vapour in sub‐nm pores gives much higher rates for the permeation of substances than expected from simple defect models.  相似文献   

    

Thomas P. McNicholas  Kyungsuk Yum  Jin‐Ho Ahn  Bin Mu  Oliver Plettenburg  Annlouise Gooderman  Sridaran Natesan  Michael S. Strano 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(22):3510-3516

Understanding the structure and function of glucose binding proteins (GBP) complexed with single walled carbon nanotubes (SWNTs) is important for the development of applications including fluorescent sensors and nanostructure particle tracking. Herein, circular dichroism (CD), thermal denaturation, photo‐absorption spectroscopy and atomic force microscopy are used to study these nanostructures. The protein retains its glucose‐binding activity after complexation and is thermally stable below 36 °C. However, the SWNT lowers the midpoint denaturation temperature (T_m) by 5 °C and 4 °C in the absence and presence of 10 mM glucose, respectively. This data highlights that using techniques such as CD and thermal denaturation may be necessary to fully characterize such protein‐nanomaterial nanostructures.  相似文献   

    

J. A. Hernández  J. Oliver  J. C. Cante  R. Weyler 《International journal for numerical methods in engineering》2011,87(8):735-767

This paper deals with the question of how to efficiently integrate a constitutive model that describes the densification of powders and the potential formation of cracks in Powder Metallurgy (P/M) cold compaction processes. The analyzed model is a large strain, elastoplastic model of the Drucker–Prager/Cap type, refined to cover also the prediction of crack formation, and featuring non‐conventional elements such as a density‐dependent Von Mises yield surface; a parabolic plastic potential function for the Drucker–Prager envelope; and a softening law whose softening modulus is dependent on the level of densification. The employed integration procedure is a non‐conventional hybrid or IMPLicit–EXplicit (IMPL‐EX) scheme, whose essence is to solve explicitly for some variables and implicitly for others, with the peculiarity of the ‘explicit’ variables being but extrapolated values of the same quantities computed, at previous time steps, by means of a fully implicit scheme. The return‐mapping equations stemming from this implicit scheme are solved using an unconditionally convergent, fractional step method‐based iterative procedure. The performance of the IMPL‐EX integration algorithm is critically assessed in two different situations: the densification of a cylindrical specimen, and the fracture process in a diametral compression test. Results obtained show conclusively that the proposed hybrid integration strategy offers an efficient solution to the trade‐off between robustness and computational time requirements. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

    

Heng‐Xing Ji  Xing‐Long Wu  Li‐Zhen Fan  Cornelia Krien  Irina Fiering  Yu‐Guo Guo  Yongfeng Mei  Oliver G. Schmidt 《Advanced materials (Deerfield Beach, Fla.)》2010,22(41):4591-4595

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Side-Chain Degradation of Ultrapure π-Conjugated Oligomers: Implications for Organic Electronics     

Abbel R  Wolffs M  Bovee RA  van Dongen JL  Lou X  Henze O  Feast WJ  Meijer EW  Schenning AP 《Advanced materials (Deerfield Beach, Fla.)》2009,21(5):597-602

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Hayden O  Björk MT  Schmid H  Riel H  Drechsler U  Karg SF  Lörtscher E  Riess W 《Small (Weinheim an der Bergstrasse, Germany)》2007,3(2):230-234

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Andreas Sternig  Slavica Stankic  Markus Müller  Johannes Bernardi  Erich Knözinger  Oliver Diwald 《Advanced materials (Deerfield Beach, Fla.)》2008,20(24):4840-4844

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Loher S  Schneider OD  Maienfisch T  Bokorny S  Stark WJ 《Small (Weinheim an der Bergstrasse, Germany)》2008,4(6):824-832

The antimicrobial activity of silver has attracted significant research interest and contributes to an exponentially growing use of this noble metal in commodity products. In this investigation, we describe a general approach to increase the antimicrobial activity of a silver-containing surface by two to three orders of magnitude. The use of 1-2-nm silver particles decorating the surface of 20-50-nm carrier particles consisting of a phosphate-based, biodegradable ceramic allows the triggered release of silver in the presence of a growing microorganism. This effect is based on the organism's requirements for mineral uptake during growth creating a flux of calcium, phosphate, and other ions to the organism. The growing micro-organism dissolves the carrier containing these nutrients and thereby releases the silver nanoparticles. Further, we demonstrate the rapid self-sterilization of polymer surfaces containing silver on calcium phosphate nanoparticles using a series of human pathogens. Colony-forming units (viable bacteria or fungi counts) have been routinely reduced below detection limit and suggest application of these self-sterilizing surfaces in hospital environments, food and pharmaceutical processing, and personal care.  相似文献   

    

Donald W. Dearholt  Kerry J. Alt  Regina F. Halpin  Richard L. Oliver 《工程教育杂志》2004,93(2):129-138

This paper presents a strategy for the design and organization of materials for Web‐based instruction (WBI) founded upon cognitive modeling for the identification and organization of the major concepts in the domain of interest, based upon the Pathfinder paradigm. The original purpose of the Pathfinder paradigm was to model aspects of human semantic (associative) memory. A brief introduction to the Pathfinder paradigm is presented, and the rationale for its use in WBI is discussed. The development of this paradigm for WBI, in the context of eliciting and representing knowledge from domain experts, and its use in a pilot study is described. The domain used for the pilot study was the A* search algorithm, embedded within an introductory course in artificial intelligence. Assessment of the paradigm is also discussed, and preliminary methods are applied to the pilot study.  相似文献   

    

Steffen Runkel  Oliver Hohn  Jens Degenhardt  Bjrn Roos 《真空研究与实践》2005,17(5):246-251

Applications of optical technologies like vision care, digital imaging or data communication play a decisive role in our daily life. Manipulation of light is mainly done using optical lenses. Beside mineral lenses, transparent plastic materials become more and more important. The optical and mechanical properties of lenses are crucially improved by high‐quality coatings. These includes primarily anti‐reflective coatings to enhance light transmission, hard coats to improve scratch resistance of the sensitive plastic substrates and finally clean coats to inhibit dusting of the lenses and to ease cleaning. In the following we present modern vacuum coating technologies for industrial refinement of optical substrates. The focal point is set to the coating of plastic eyeglass lenses using a revolutionary inline technology. On one hand the technology merges all coating steps in a fully automated system and enables on the other hand the flexible combination of different layer stacks necessary for RX‐production of ophthalmic lenses. This inline technology is available by the coating system OPTICUS. The design of the OPTICUS is described in the last chapter.  相似文献