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Observations: rolling versus sliding

Observations beyond the range of the naked eye require more deliberate and cautioned interpretation of what isobserved. Specifically, factual and accurate information must be discerned out of various interferences that can lead tounsubstantiated conclusions. The Tour group had to surmount these uncertainties to conclusively show that the nanocars underwentrolling, rather than sliding, translational motion.

Nanocar translational movement across a gold surface at 200°C. The pivoting of the molecule’s motion is due to out-of-sync rotation of wheel movement. Thepicture indicated path occurred over a minute period (images captured ever minute by STM). Reprinted with kindpermission from Dr. Kevin Kelly<picture courtesy of Rice University Office of Media Relations>.

The choice of a gold surface enabled temperature dependent adhesion to the surface, and allowed targetedobservation of specific molecules. In the picture to the left, you see several nanocars spread out along the Au(111) surface. As theresearchers increased the temperature to 200°C, the cars began to move at such a rate that they noticeably displaced from their originalposition in a period of one minute (figure 8). This indicates that 200°C is a viable temperature for imaging nanocars on gold with STM. However, imaging of the cars at temperatures above 225°C is currently impossible due to the rapid motion of the molecules at thattemperature. The nanocars are moving too quickly to be imaged by the one-minute capture rate of the STM. Once the system was heated to300-350°C, the car began to decompose. These observations indicated that motion of the nanocars was dependent on temperature.

It was also observed that the cars did not exclusively undergo translational motion, but also rotated. In theimage to the right, it can be observed that the cars pivot as they move across the frame, changing direction without moving forward. TheTour Group explained this rotation as an inability to synchronize the rotation of each wheel.

The Tour Group also observed three-wheeled molecules, or trimers, which they found useful inproving rotational motion of the C60 molecules. If the cars’ movement were in fact due to rotation, then the trimer would not be able tomove translationally due to the fact that the three wheels cannot rotate in a coordinated manner, that is no two wheels can rotate thesame parallel plane. This supports the idea that the C60 molecules are rotating, as opposed to sliding. To strengthen their assertion, theresearchers heated a sample of the trimer molecules on the same gold surface to 225°C—a temperature at which the four-wheeled molecules rapidly moved out of the scanning range of the STM. Upon doing so,they observed that the trimers did not undergo significant translational motion, and remained within nanometers of their originalposition. This showed that both the wheels and axels of the trimer and nanocar allow for rotational motion, therefore substantiating theassertion that translational motion of the nanocar is due to rolling.

The researchers used an STM to pull the nanocar in order to see if there was preferential motion (ie. Due torolling). When the molecules were pulled perpendicular to the axles (Figure 9; frame a) the molecule moved in the direction of thepull. But, pulling parallel to the axles resulted in no translational motion in the direction of the pull (frame b). Lastly, by pullingperpendicular to the axles, the nanocar resumed its forward path (frame c).

Translational Motion of Pulled Nanocars on Gold Surface at 200°C. Frame (a) depicts the movement of a nanocar pulled perpendicular to its axles. Frame (b) indicates theinhibited motion that results from pulling parallel to the axles. Frame (c) is another instance of a pulling force perpendicular tothe axles. Reprinted with kind permission from Dr. Kevin Kelly<picture courtesy of Rice University Office of Media Relations>.

These experiments carried out by the Tour Group combined to substantiate the claim that the nanocars wererolling on the C60 wheels as opposed to sliding. This observation designates the molecule as the first nanocar capable of executing apredetermined, engineered motion. These experiments lay down a foundation of knowledge on the molecular mechanics of motion.Particularly, these experiments conclusively demonstrate rolling motion of the C60 on gold surfaces at a given temperature. This marksthe first step in a greater understanding of molecular motion as it applies to molecular manufacturing.

The future of the development of molecular manipulation

Molecular manipulation as a science has developed in steps. Its early steps involved movement of atoms and molecules,along with the ability to observe those movements. Later came engineered molecular components that carried out predeterminedfunctions, such as bearings and axles. At the present, nanocars are an example of the developments in motility and function of integratedcomponents that serve a unified purpose. But more importantly, nanocars are an indicator of developments to come. They are usheringin an era of deliberate and controlled motion at the molecular level.

Questions & Answers

how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
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it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
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oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
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The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
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Differences Between Laspeyres and Paasche Indices
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No. 7x -4y is simplified from 4x + (3y + 3x) -7y
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. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
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I start with an easy one. carbon nanotubes woven into a long filament like a string
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Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
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good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
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how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
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I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
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Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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the Beer law works very well for dilute solutions but fails for very high concentrations. why?
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how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, Nanotechnology: content and context. OpenStax CNX. May 09, 2007 Download for free at http://cnx.org/content/col10418/1.1
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