3. Addressing Misconceptions

1)   Shrink Rays, Small Machines, and Tiny Monsters
In order to play a video game, students need to accept some suspension of reality, namely they need to pretend that matter in a condensed state can be dramatically compacted while retaining all the properties and functions it had at its larger scale. While we know that "Fantastic Voyage" and "Honey, I shrunk the kids" do not represent reality, students will sometimes consider these as possibilities awaiting the appropriate technology. Since Geckoman has a "shrink-ray" as part of the game play, it is important to point out to students that this is fictional and done solely to allow us to experience the conditions of materials at the nanoscale.

Articles:
Nautilus to Nanobots: The Visual Construction of Nanoscience

Video links: use these clips to start discussion
Honey I Shrunk the Kids from You Tube - the important part is in the first two minutes of the clip.
Fantastic Voyage Trailer showing the shrunken voyagers inside the human body from You Tube.
Fantastic Voyage Final Scene
showing reversing the shrinking process from You Tube.

2)    Denser is NOT Heavier.
In the attachments section at the bottom of this column there is a document produced jointly by the El Paso Collaborative, the Center for Policy Research in Education, and the Consortium for Achievement in Math and Science. This is not a final publication, but a review draft. Still, it seems to be a very comprehensive overview of density and associated student misconceptions.
Colored glass poses a conundrum that most teachers and students don't realize. Students are taught that certain properties remain the same no matter how much of the material is present; the so-called "intensive properties." As seen in Geckoman, while gold is a yellow metal when in macroscopic amounts, it can be red or blue depending on the particle size because the surface area to volume ratio is vastly changed. This is a common theme among nanoparticles because when most atoms are on the surface, surface effects as described in quantum theory are more apparent than our "intuitive" Newtonian Laws.

Glass workers unknowingly made use of this in creating a stable, easily reproducible red color glass called ruby glass. Before the incorporation of gold, ruby glass was made by incorporating copper atoms suspended into the glass but this process was difficult to reproduce consistently. Gold ruby-glass, where colloidal gold particles are dispersed throughout the glass medium, was a significant advance but very costly.

Twentieth century ruby-glass  does not incorporate gold particles, but makes use of nanoscopic colloidal selenium particles. Selenium, a nonmetal, can form a variety of ions and compounds in the glass melt, but it is only the free Se atoms that give it the ruby color. For a good reference, try this British site.

The most important aspect of this is that the size of the particles (or amount of substance held together) will change the substance's color, not just the intensity of the color. This is contrary to much of what is commonly taught in secondary school text books about Intensive versus Extensive properties.

A good reference for glass is found in Bray, Charles. 2001. Dictionary of Glass: materials and techniques. 2nd Edition. University of Pennsylvania Press.

Glass is not the only material to be affected by color changing properties of nanotechonolgy. The array of nanotubes developed at Northwestern University (shown to the right) provide a new method for creating a size-tunable, colored, transparent conductor. Currently, the most common transparent conductor is indium tin oxide, commonly used for devices ranging from LEDs to flat display panels. The hurdle overcome in producing these nanotech devices has been in making consistently-sized carbon nanotubes. 

 
4)    Electrical conductivity of a material CAN change too!
Like color, electrical conductivity is not a fixed Intensive property, but rather variable based on the scale of the particle. At the nanoscale, 

Carbon is generally spoken about as a nonconducting, nonmetal, particularly when discussed in the realm of biology. We already know from experiences in the chemistry lab running redox reactions that graphite, an allotrope of carbon, is a conductor. Indeed, it is often used as the anode or cathode for experiments comparing the oxidation potential (or reduction potential) of a substance to hydrogen. This shows us that the arrangement of a substance at the atomic (nano) level can make important differences in its properties.

Still, we don't usually consider carbon a conductor. Amazingly, at the nanoscale is that carbon nanotubes are a thousand times more conductive than their equivalent in copper. (Source:  Hong, Seunghun; Sung Myung (2007). "Nanotube Electronics: A flexible approach to mobility". Nature Nanotechnology 2: 207–208)Carbon is certainly a conductor!

Videos of Nanotube Radio in action from Lawrence Berkeley National Laboratory.


5)    TRUE OR NOT?    Nanoparticles are deadly. OR      
                                Nanoparticles are proven safe.
Nanotechnology is new. This means that scientists and engineers are taking great precautions in introducing nanomaterials because we are still learning about their properties and how to use them.  We cannot make any overall claims for safety, only state that safety concerns are important. 

Safety has multiple facets. It can be seen in terms of human health, environmental impact, or economic impact. Scientists and engineers working in nanotechnology are held to scrutiny by their peers, their institutions, governmental bodies, and society at large when they introduce a new technology.

Many authors have taken advantage of people's understandable reticence with transformative technologies and created horror scenarios involving nanotechnology. One of the most popular versions of this theme is found in the 'nanite' robots from Michael Crichton’s book "Prey." This is a doomsday scenario similar to that described by Eric Drexler's 1986 book, "The Engines of Creation." 

Some of the resources which might prove useful are:
The National Nanotechnology Initiative, a US federal program established in 2001 to coordinate research efforts funded by the government, produced a February 2008 report compiling research on nanotechnology related health, evnvironmental, and safety concerns.

The American Chemical Society's Committee on Chemical Safety, which presents the current state of prudent practices for the largest professional scientific organization in the world, offers guidelines and resources for nanotechnology safety.

The (UK) Royal Society and the Royal Academy of Engineering jointly produced a report on the ethical and societal implications of nanotechnology. It was published in July 2004, but there are further updates, links, and testimony on the website.










 
 
  View of glass when held up to the light
The Lycugus Cup. This cup is made of dichroic glass that has colloidal gold and silver nano-scale particles in the glass. When held up to the light, the ordinarily green cup (from the silver particles) shows up as red due to the gold nanoparticles in the glass. More information, and the original images are available from The British Museum. 

Carbon nanotubes are arranged here in order of increasing diameter. Image from Science Daily, April 10, 2008. http://www.sciencedaily.com/releases/2008/04/080409091733.htm

 
 


 

 

 
Figure 5 (Graphic5.png)
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Matthew Corcoran,
Jul 27, 2009, 8:19 AM
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