For fabrication of arc-discharged single walled carbon nanotubes (arc-SWCNTs) based FET array, controllable deposition of SWNTs is an important issue. In this study highly purified arc-SWCNTs are deposited on the high...
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ISBN:
(纸本)9781424435432;9781424435449
For fabrication of arc-discharged single walled carbon nanotubes (arc-SWCNTs) based FET array, controllable deposition of SWNTs is an important issue. In this study highly purified arc-SWCNTs are deposited on the high-throughput screening FET array via the addressable dielectrophoresis method. The electrodes array are designed with different electrode gaps, from 3 to 20 ¿m, every electrode has its own address. In order to limit the SWCNTs to be deposited within the electrodes area, we designed a deposition window on the silicon chip surface by the optical lithography. Then the diluted SWCNTs solution was dropped onto the limited window. By setting a voltage (10 V, 100 kHz) between a specific source electrode and the shared drain electrode, the SWCNTs can be aligned evenly within the pair of electrodes via the dielectrophoresis process. This method might facilitate the controllable fabrication of high throughput screening SWCNTs-FET arrays for biosensors.
Silicon is an important material not only for semiconductor applications, but also for the development of novel bioinspired and biomimicking materials and structures or drug delivery systems in the context of nanomedi...
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Silicon is an important material not only for semiconductor applications, but also for the development of novel bioinspired and biomimicking materials and structures or drug delivery systems in the context of nanomedicine. For these applications, a thorough understanding of the fracture behavior of the material is critical. In this paper we address this issue by investigating a fundamental issue of the mechanical properties of silicon, its behavior under extreme mechanical loading. Earlier experimental work has shown that at low temperatures, silicon is a brittle material that fractures catastrophically like glass once the applied load exceeds a threshold value. At elevated temperatures, however, the behavior of silicon is ductile. This brittle-to-ductile transition (BDT) has been observed in many experimental studies of single crystals of silicon. However, the mechanisms that lead to this change in behavior remain questionable, and the atomic-scale phenomena are unknown. Here we report for the first time the direct atomistic simulation of the nucleation of dislocations from a crack tip in silicon only due to an increase of the temperature, using large-scale atomistic simulation with the first principles based ReaxFF force field. By raising the temperature in a computational experiment with otherwise identical boundary conditions, we show that the material response changes from brittle cracking to emission of a dislocation at the crack tip, representing evidence for a potential mechanisms of dislocation mediated ductility in silicon.
The acidic strength of a liquid acid catalyst,a measure of its ability to either donate protons or accept electron pairs,is normally characterized by conventional acid-base titration method under aqueous solution[1],l...
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The acidic strength of a liquid acid catalyst,a measure of its ability to either donate protons or accept electron pairs,is normally characterized by conventional acid-base titration method under aqueous solution[1],leading to a scaled pKa *** the other hand,the acidic strengths of non-aqueous and solid acids are commonly classified by amine titration method using Hammett indicators,which may be quantitatively expressed by the Hammett acidity function(Ho)[2].In the past few decades,many attempts have been adopted for the analyses of acidic strengths using calorimetric measurements[3],infrared[4],and NMR[5] spectroscopy,and thermal desorption of adsorbed probe molecules,or application of indicator dyes[6].Previously,we have demonstrated that detailed acid features,***(BrФnsted ***),distributions(location and concentration),and strengths,of various solid acid catalysts can be simultaneously obtained by solid-state 31P MAS NMR of adsorbed trialkylphosphine oxides(R3PO)[7].We have also conducted theoretical quantum chemical DFT calculations to interpret the observed 31P NMR chemical shifts(CSs)in various solid acid catalysts[8].
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