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Ce travail de thèse décrit les mesures de propriétés mécaniques à l'échelle nanométrique. Trois différents objets tubulaires de taille mésoscopiques ont été étudiés : des nanotubes de MoS2, nanotubes de carbone et microtubules biologiques. L'objectif principal a été l'étude de la relation entre la structure fine de ces objets et leurs propriétés mécaniques. Les mesures ont été effectuées par déformation élastique des tubes sur une surface poreuse à l'aide d'une pointe de Microscope à Force Atomique (AFM). La première partie expérimentale traite de la caractérisation mécanique des fagots de nanotubes de MoS2. La déformation élastique de ces derniers peut être modélisée, par analogie avec les fagots de nanotubes de carbone en utilisant deux modules élastiques : le module de Young et le celui de cisaillement, décrivant le faible couplage ...
A diplomamunka felépítése Első ízben a Windows Server 2008 történetét tekintem át, ezen belül a kiadásait és az újdonságokat nagyvonalakban. Ezt követően sorra veszem a biztonságot közvetlenül vagy közvetve érintő elemeket, különös hangsúlyt fektetve a Server Core-ra, az Active Directory szerepkörökre, a terminálszolgáltatásokra, a Hyper-V virtualizációs rendszerre és a Server Manager-re. Végül említést teszek még néhány rendszerbiztonsággal összefüggő újdonságról.
Some of the most important potential applications of carbon nanotubes are related to their mechanical properties. Stiff sp(2) bonds result in a Young's modulus close to that of diamond, while the relatively weak van der Waals interaction between the graphitic shells acts as a form of lubrication. Previous characterization of the mechanical properties of nanotubes includes a rich variety of experiments involving mechanical deformation of nanotubes using scanning probe microscopes. These results have led to promising prototypes of nanoelectromechanical devices such as high-performance nanomotors, switches and oscillators based on carbon nanotubes.
Single-layer MoS2 is a newly emerging two-dimensional semiconductor with a potentially wide range of applications in the fields of nanoelectronics and energy harvesting. The fact that it can be exfoliated down to single-layer thickness, makes MoS2 interesting both for practical applications and for fundamental research, where the structure and crystalline order of ultrathin MoS2 will have a strong influence on electronic, mechanical and other properties. Here, we report on the transmission electron microscopy study of suspended single and few-layer MoS2 membranes with thicknesses previously determined using both optical identification and atomic force microscopy. Electron microscopy shows that monolayer MoS2 displays long-range crystalline order although surface roughening has been observed with ripples which can reach 1 nm in height, ...
Logic circuits and the ability to amplify electrical signals form the functional backbone of electronics along with the possibility to integrate multiple elements on the same chip. The miniaturization of electronic circuits is expected to reach fundamental limits in the near future. Two-dimensional materials such as single-layer MoS2 represent the ultimate limit of miniaturization in the vertical dimension, are interesting as building blocks of low-power nanoelectronic devices, and are suitable for integration due to their planar geometry. Because they are less than 1 nm thin, 2D materials in transistors could also lead to reduced short channel effects and result in fabrication of smaller and more power-efficient transistors. Here, we report on the first integrated circuit based on a two-dimensional semiconductor MoS2. Our integrated c...
We report on measurements of the stiffness and breaking strength of monolayer MoS2, a new semiconducting analogue of graphene. Single and bilayer MoS2 is exfoliated from bulk and transferred to a substrate containing an array of microfabricated circular holes. The resulting suspended, free-standing membranes are deformed and eventually broken using an atomic force microscope. We find that the in-plane stiffness of monolayer MoS2 is 180 ± 60 Nm-1, corresponding to an effective Young’s modulus of 270 ± 100 GPa which is comparable to that of steel. Breaking occurs at an effective strain between 6-11% with the average breaking strength of 15 ± 3 Nm-1 (23GPa). The strength of strongest monolayer membranes is 11% of its Young’s modulus, corresponding to the upper theoretical limit which indicates that the material can be highly crystalline a...
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