1,721,484 research outputs found
Oberflächenmodifiziertes Schichtsystem
No full textGölzhäuser A, Geyer W, Grunze M, Eck W, Stadler V, Zharnikov M. Oberflächenmodifiziertes Schichtsystem. 1999
Formation of self-assembled monolayers of n-alkanethiols on gold: a scanning tunneling microscopy study on the modification of substrate morphology
Get PDFEdinger K, Gölzhäuser A, Demota K, Wöll C, Grunze M. Formation of self-assembled monolayers of n-alkanethiols on gold: a scanning tunneling microscopy study on the modification of substrate morphology. Langmuir. 1993;9(1):4-8
Low-energy configurations of methoxy triethylene glycol terminated alkanethiol self-assembled monolayers and their relevance to protein adsorption
No full textMethoxy triethylene glycol terminated alkanethiol monolayers self-assembled on Au and Ag have recently been found to exhibit a striking difference in protein resistance, which has been interpreted in terms of the transition of the ethylene glycol tails from a helical to an all-trans conformation (Harder, P.; Grunze, M.; Dahint, R.; Whitesides, G. M.; Laibinis, P. E. J. Phys. Chem. 1998, 102, 426−436. Wang, R. L. C.; Kreuzer, H. J.; Grunze, M. J. Phys. Chem. 1997, 101, 9767−9773). To gain further arguments in favor of such a conformational transition, we undertake a search for the lowest energy monolayer configurations on Au and Ag by combining the methods of stochastic global search and static energy minimization. The conformational and intermolecular contributions to the monolayer lattice energy are calculated using a classical atomistic force field fitted to ab initio MP2 level calculation results for 1,2-dimethoxyethane. It is found that in the lowest energy monolayer configuration on Au the methoxy triethylene glycol tails really assume a helix-like conformation, with the three constituent O−C−C−O bond sequences being in the trans−gauche−trans form. The helical conformation is mainly stabilized by the intra- and intermolecular electrostatic interactions between the ethylene glycol units. In the Ag-supported monolayer, characterized by a perceptibly higher packing density, the helical conformer loses its stability due to conformational strains and becomes less favorable than a nearly planar all-trans conformer. The calculation results provide support to the view that the origin of the gauche effect observed in poly- and oligo(ethylene glycols) is in the influence of a polar environment and not in intrinsic properties of the ethylene glycol unit
Quasistatic computer simulation study of the shear behavior of Bi- and trilayer water films confined between model hydrophilic surfaces
No full textIn this paper, our previous simulations of the shear behavior of confined water monolayers (Pertsin, A.; Grunze, M. Langmuir 2008, 24, 135) are extended to water films two and three monolayers thick. The shear response of the films is studied in the quasistatic regime corresponding to the infinitely low shear rate. In certain ranges of wall-to-wall separations, bilayer films are found to be capable of sustaining shear stress, as is characteristic of solids, while remaining fluidlike in respect of the lateral order and molecular mobility. The relation between the solidlike and fluidlike properties of the films is dependent on the relative alignment of the walls and on the period of the wall lattice. The films become more fluid when the walls are moved out of alignment and when the wall lattice is uniformly compressed or stretched with respect to the "optimum" lattice that favors crystal-like packing. Trilayer films do not sustain shear stress in the whole range of wall-to-wall separations where these films are formed
Generation of surface amino groups on aromatic self-assembled monolayers by low energy electron beams - A first step towards chemical lithography
No full textEck W, Stadler V, Geyer W, Zharnikov M, Gölzhäuser A, Grunze M. Generation of surface amino groups on aromatic self-assembled monolayers by low energy electron beams - A first step towards chemical lithography. Advanced Materials. 2000;12(11):805-808
Freestanding nanosheets from crosslinked biphenyl self-assembled monolayers
No full textEck W, Küller A, Grunze M, Völkel B, Gölzhäuser A. Freestanding nanosheets from crosslinked biphenyl self-assembled monolayers. ADVANCED MATERIALS. 2005;17(21):2583-2587.Freestanding nanosheets (see Figure) with the thickness of a single molecule and lateral dimensions in the micrometer range have been obtained by the release of self-assembled monolayers from the underlying surface by dissolution of the substrate or by scission of the anchor group-substrate bonds. The self-assembled monolayers are composed of biphenyl units that are crosslinked by electron irradiation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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