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排序方式: 共有178条查询结果,搜索用时 31 毫秒
31.
Dr. Artur Ciesielski Jürgen Weippert Dr. Artur Böttcher Yuyoung Shin Georgian Melinte Prof. Dr. Ovidiu Ersen Dr. Cinzia Casiraghi Prof. Dr. Xinliang Feng Prof. Dr. Klaus Müllen Prof. Dr. Manfred M. Kappes Prof. Dr. Paolo Samorì Dr. Marco Cecchini 《Chemphyschem》2016,17(3):352-357
Providing a quantitative understanding of the thermodynamics involved in molecular adsorption and self‐assembly at a nanostructured carbon material is of fundamental importance and finds outstanding applications in the graphene era. Here, we study the effect of edge perchlorination of coronene, which is a prototypical polyaromatic hydrocarbon, on the binding affinity for the basal planes of graphite. First, by comparing the desorption barrier of hydrogenated versus perchlorinated coronene measured by temperature‐programmed desorption, we quantify the enhancement of the strength of physisorption at the single‐molecule level though chlorine substitution. Then, by a thermodynamic analysis of the corresponding monolayers based on force‐field calculations and statistical mechanics, we show that perchlorination decreases the free energy of self‐assembly, not only enthalpically (by enhancing the strength of surface binding), but also entropically (by decreasing the surface concentration). The functional advantage of a chemically modulated 2D self‐assembly is demonstrated in the context of the molecule‐assisted liquid‐phase exfoliation of graphite into graphene. 相似文献
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Dr. Zhengxing Qin Dr. Georgian Melinte Prof. Jean‐Pierre Gilson Prof. Maguy Jaber Prof. Krassimir Bozhilov Dr. Philippe Boullay Dr. Svetlana Mintova Prof. Ovidiu Ersen Dr. Valentin Valtchev 《Angewandte Chemie (International ed. in English)》2016,55(48):15049-15052
Zeolites are widely used in many commercial processes, mostly as catalysts or adsorbents. Understanding their intimate structure at the nanoscale is the key to control their properties and design the best materials for their ever increasing uses. Herein, we report a new and controllable fluoride treatment for the non‐discriminate extraction of zeolite framework cations. This sheds new light on the sub‐structure of commercially relevant zeolite crystals: they are segmented along defect zones exposing numerous nanometer‐sized crystalline domains, separated by low‐angle boundaries, in what were apparent single‐crystals. The concentration, morphology, and distribution of such domains analyzed by electron tomography indicate that this is a common phenomenon in zeolites, independent of their structure and chemical composition. This is a milestone to better understand their growth mechanism and rationally design superior catalysts and adsorbents. 相似文献
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Nicolae Aldea Rodica Turcu Alexandrina Nan Izabella Craciunescu Ovidiu Pana Xie Yaning Zhonghua Wu Doina Bica Ladislau Vekas Florica Matei 《Journal of nanoparticle research》2009,11(6):1429-1439
In this article, we focus on the structural peculiarities of nanosized Fe3O4 in the core-shell nanocomposites obtained by polymerization of conducting polypyrrole shell around Fe3O4 nanoparticles. The local structure of Fe atoms was determined from the Extended X-ray Absorption Fine Structure analysis
using our own package computer programs. An X-ray diffraction method that is capable to determine average particle size, microstrains,
as the particle size distribution of Fe3O4 nanoparticles is presented. The method is based on the Fourier analysis of a single X-ray diffraction profile using a new
fitting method based on the generalized Fermi function facilities. The crystallites size obtained by X-ray diffraction spectra
analysis was estimated between 3.2 and 10.3 nm. Significant changes in the first and the second Fe coordination shell in comparison
with standard bulk were observed. The global and local structure of the nanosized Fe3O4 are correlated with the synthesis conditions of the core-shell polypyrrole nanocomposites. 相似文献
36.
Sandu Ion Dumitrache Florian Fleaca Claudiu Cretu Ovidiu Morjan Ion 《Solid State Sciences》2009,11(10):1793-1796
In this work we report the synthesis of free-standing films of polymer/nanocarbon composites. The method consists in forming a thin film of carbon nanoparticles onto the water's surface. Through the free infiltration of the polymer between the nanoparticles which form the film, after the polymer is cured, we obtain free-standing films of polymer/nanocarbon composites. The composite films are homogeneous; they have 5 wt.% carbon nanoparticles within the polymer matrix and are a few micrometers in thickness. 相似文献
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Scott R. Kennedy Michael J. Brett Hernan Miguez Ovidiu Toader Sajeev John 《Photonics and Nanostructures》2003,1(1):37-42
We report the fabrication and optical characterization of a tetragonal square spiral photonic crystal with a three-dimensional relative band gap of approximately 10% using the glancing angle deposition (GLAD) technique. This thin film structure is produced in a one-step process that is highly versatile as a wide range of crystal structures can be created simply through the variation of deposition parameters. Measurements indicate upper and lower frequency band edges at vacuum wavelengths of 2.50 and 2.75 μm, in the infrared region of the spectrum. 相似文献
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Andreas Zerr Nikolay Chigarev Ovidiu Brinza Sergey M. Nikitin Alexey M. Lomonosov Vitalyi Gusev 《固体物理学:研究快报》2012,6(12):484-486
The elastic moduli of the dense polycrystalline oxygen‐bearing η‐Ta2N3, a novel hard and tough high‐pressure (HP) material, were measured using the laser ultrasonic technique. The bulk modulus was determined to be B0 = 281(15) GPa which is only ~11% below that from HP compression measurements. Our value of the shear modulus G0 = 123(2) GPa is below those ones predicted theoretically for model structures. The discrepancies in G0 could be due to a substitution of an‐ ions and the formation of cation vacancies in η‐Ta2N3. Self‐healing behaviour of η‐Ta2N3 by mechanical polishing was observed and confirmed by two independent experimental methods. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
39.
Anne Siegel Carito Guziolowski Philippe Veber Ovidiu Radulescu Michel Le Borgne 《PAMM》2007,7(1):1121803-1121804
We advocate the use of qualitative models for the analysis of shift equilibria in large biological systems. We present a mathematical method, allowing qualitative predictions to be made of the behaviour of a biological system. These predictions are not dependent on specific values of the kinetic constants. We show how these methods can be used to improve understanding of a complex regulatory system. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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