Continuum Modeling and Analysis of the Frictional Interaction Between a CNT and a Substrate During Dragging

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
George G. Adams ◽  
Palaniappan Nagappan ◽  
Nicol E. McGruer
Keyword(s):  
Steady State ◽  
Partial Slip ◽  
Simple Method ◽  
Modeling And Analysis ◽  
Aspect Ratios ◽  
Atomic Force ◽  
Frictional Interaction ◽  
Potential Applications ◽  
The Relationship

A simple method to determine the frictional interaction between a carbon nanotube (CNT) and a substrate is analyzed for feasibility. In this technique an atomic force microscope (AFM) tip is used to drag a CNT along a substrate. Then the deformed shape of the CNT can be viewed either with the AFM or in a scanning electron microscope. An analysis of the steady-state deformed shape allows the determination of the frictional interactions, which occurred during dragging. It is important to quantify these interactions in a variety of potential applications of nanotechnology. In one such example, a CNT based nanoswitch consists of a CNT bridging over a trench. Actuation of the CNT causes it to stretch and can lead to partial slip at the interface. This slip causes hysteresis, which has been observed in the mechanical actuation of a CNT bridge. In this paper continuum level modeling of the frictional interaction is used to determine the relationship between the steady-state deformed shape of the CNT and the frictional interaction, which occurred between the CNT and substrate during dragging. The model and analysis indicate that this method should be feasible for CNTs with aspect ratios approximately in the 100–250 range.

Continuum Modeling and Analysis of the Frictional Interaction Between a CNT and a Substrate During Dragging

2008 ◽  
Author(s):  
George G. Adams ◽  
Palaniappan Nagappan ◽  
Nicol E. McGruer
Keyword(s):  
Partial Slip ◽  
Simple Method ◽  
Modeling And Analysis ◽  
Aspect Ratios ◽  
Atomic Force ◽  
Frictional Interaction ◽  
Potential Applications ◽  
The Relationship ◽  
Mechanical Actuation

A simple method to determine the frictional interaction between a carbon nanotube (CNT) and a substrate is analyzed for feasibility. In this technique an atomic force microscope (AFM) tip is used to drag a CNT along a substrate. Then the deformed shape of the CNT can be viewed either with the AFM or in an SEM. An analysis of the deformed shape allows the determination of the frictional interactions which occurred during dragging. It is important to quantify these interactions in a variety of potential applications of nanotechnology. In one such example, a CNT based nanoswitch consists of a CNT bridging over a trench. Actuation of the CNT causes it to stretch and can lead to partial slip at the interface. This slip causes hysteresis which has been observed in the mechanical actuation of a CNT bridge. In this paper continuum level modeling of the frictional interaction is used to determine the relationship between the shape of the CNT and the frictional interaction which occurred between the CNT and substrate during dragging. The model and analysis indicate that this method should be feasible for CNTs with aspect ratios approximately in the 100–250 range.

An Experimental Determination of the Relationship between Lift and Aerodynamic Power in Calliphora Erythrocephala and Phormia Regina

1972 ◽  
Vol 56 (1) ◽  
pp. 31-36
Author(s):  
JAMES WOOD
Keyword(s):  
Steady State ◽  
Experimental Determination ◽  
Insect Flight ◽  
Phormia Regina ◽  
Calliphora Erythrocephala ◽  
The Relationship

Lift and aerodynamic power were calculated for Calliphora and Phormia using assumptions which maximized and minimized the ratio of aerodynamic power to lift. The ratios of aerodynamic power to lift calculated by these methods, which do not rely on the assumption that steady-state aerodynamics applies to insect flight, are in agreement with results calculated by others using steady-state aerodynamics.

scholarly journals Mechanical Characterization of Torsional Micropaddles Using Atomic Force Microscopy

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
N. Mahmoodi ◽  
A. Sabouri ◽  
J. Bowen ◽  
C. J. Anthony ◽  
P. M. Mendes
Keyword(s):  
Atomic Force Microscopy ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Spring Constant ◽  
Simple Method ◽  
Force Microscopy ◽  
Atomic Force ◽  
Torsional Spring

The reference cantilever method is shown to act as a direct and simple method for determination of torsional spring constant. It has been applied to the characterization of micropaddle structures similar to those proposed for resonant functionalized chemical sensors and resonant thermal detectors. It is shown that this method can be used as an effective procedure to characterize a key parameter of these devices and would be applicable to characterization of other similar MEMS/NEMS devices such as micromirrors. In this study, two sets of micropaddles are manufactured (beams at centre and offset by 2.5 μm) by using LPCVD silicon nitride as a substrate. The patterning is made by direct milling using focused ion beam. The torsional spring constant is achieved through micromechanical analysis via atomic force microscopy. To obtain the gradient of force curve, the area of the micropaddle is scanned and the behaviour of each pixel is investigated through an automated developed code. The experimental results are in a good agreement with theoretical results.

Nanoscale craters in poly(methyl methacrylate) formed by exposure to condensing solvent vapor

2007 ◽  
Vol 22 (12) ◽  
pp. 3360-3370 ◽  
Author(s):  
C.M. Bates ◽  
F. Stevens ◽  
S.C. Langford ◽  
J.T. Dickinson
Keyword(s):  
Methyl Methacrylate ◽  
Large Scale ◽  
Ammonia Vapor ◽  
Solvent Vapor ◽  
Acid Vapor ◽  
Poly Methyl Methacrylate ◽  
Aspect Ratios ◽  
Atomic Force ◽  
Large Numbers ◽  
Potential Applications

We report atomic force microscope observations of small pits formed on thin poly(methyl methacrylate) films after exposure to formic acid vapor, which condenses to form small drops on the surface and then evaporates. This procedure produces large numbers of small pits, 50–5000 nm in diameter, with aspect ratios (depth-to-diameter) as high as 0.5. About 25% of the volume removed from high-aspect-ratio pits has been transported to form a raised ring around the rim of the pit. We attribute the remaining 75% of the volume loss to densification of the surrounding polymer. Nanoindentation measurements show that material inside the pits is harder and stiffer than material outside the pits, consistent with densification. The effects of solvent concentration, exposure time, and exposure to ammonia vapor are described. Similar treatments with volatile solvents have potential applications in large-scale surface patterning, submicron hole formation, and controlled alteration of surface properties.

scholarly journals A comparison of metal and Ly-α absorption in galactic haloes

1998 ◽  
pp. 9-13
Author(s):  
M.M. Cirkovic
Keyword(s):  
Neutral Hydrogen ◽  
Observational Cosmology ◽  
Simple Method ◽  
Large Samples ◽  
Gaseous Component ◽  
Absorption Studies ◽  
Statistical Determination ◽  
The Relationship ◽  
Galactic Haloes

The metallicity structure of galactic haloes is one of the major unknowns in modern galactic astrophysics and observational cosmology. Hereby we outline a very simple method for obtaining at least a crude picture of gas abundances, based on recent important statistical determination of the relationship between neutral hydrogen absorbing column density and galaxy impact parameter. It is a fine illustration of the great theoretical and observational power of low-redshift Ly? absorption studies. Future detailed analyses of large samples of absorption-selected galaxies will certainly provide us with more data on the abundance structure of extended gaseous component of galaxies.

Development of a simple method for the determination of single nucleotide polymorphisms

2010 ◽  
Vol 34 (8) ◽  
pp. S75-S75
Author(s):  
Weifeng Zhu ◽  
Zhuoqi Liu ◽  
Daya Luo ◽  
Xinyao Wu ◽  
Fusheng Wan
Keyword(s):  
Single Nucleotide Polymorphisms ◽  
Nucleotide Polymorphisms ◽  
Simple Method ◽  
Single Nucleotide

Thromboplastin Related Differences in the Determination of International Normalised Ratio: A Cause for Concern?

1994 ◽  
Vol 72 (03) ◽  
pp. 426-429 ◽  
Author(s):  
S Kitchen ◽  
I D Walker ◽  
T A L Woods ◽  
F E Preston
Keyword(s):  
Patient Management ◽  
External Quality Assessment ◽  
Oral Anticoagulant Therapy ◽  
Warfarin Dosage ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
International Normalised Ratio ◽  
The Uk ◽  
The Relationship

SummaryWhen the International Normalised Ratio (INR) is used for control of oral anticoagulant therapy the same result should be obtained irrespective of the laboratory reagent used. However, in the UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation INRs determined using different reagents have been significantly different.For 18 NEQAS samples Manchester Reagent (MR) was associated with significantly lower INRs than those obtained using Diagen Activated (DA, p = 0.0004) or Instrumentation Laboratory PT-Fib HS (IL, p = 0.0001). Mean INRs for this group were 3.15, 3.61, and 3.65 for MR, DA, and IL respectively. For 61 fresh samples from warfarin-ised patients with INRs of greater than 3.0 the relationship between thromboplastins in respect of INR was similar to that observed for NEQAS data. Thus INRs obtained with MR were significantly lower than with DA or IL (p <0.0001). Mean INRs for this group were 4.01, 4.40, and 4.59 for MR, DA, and IL respectively.We conclude that the differences between INRs measured with the thromboplastins studied here are sufficiently great to influence patient management through warfarin dosage schedules, particularly in the upper therapeutic range of INR. There is clearly a need to address the issues responsible for the observed discrepancies.

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