User:Thermochap/Sandbox/size-scale awareness

Schematic of longitudinal and transverse distances and resolutions.

This is a page about size-scale awareness: awareness of how the world changes according to the size scale of your perspective. For example, large objects like the earth might be more sensitive to tidal forces than we are, while small objects like a molecule might be more likely to notice the strange effects of quantized angular momentum.

This subject is relevant because everyday life challenges us, along with the cells of which we are made, to inform our behaviors simultaneously to processes on size scales from nano to macro and beyond.

This is joint-editing space. Feel free to change, remove, add, and/or comment on anything you like, and also to put this page on your watchlist. As interest expands we'll move this discussion to other platforms and let you know about them here. For example, instance on wikibooks should make integration with material there easier. Another instance of this discussion is active for those with a University of Missouri at Saint Louis single sign-on ID on the campus' internal mediawiki site. One might expect these offspring pages to diverge evolutionarily over time.

Introduction

Nanotechnology application schematic.

One frontier that everyone has access to is "the land of the small" in their own backyard. Increasingly powerful and accessible tools are opening the door to nanoworld adventurers. These tools can give students access to a world which is their very own, and where nature behaves in ways that are sometimes amazingly familiar and sometimes amazingly strange.

Where else would one find worlds where for example

• inertia goes unnoticed,
• walking on the ceiling is easy,
• only motors with opposing axles actually work, and
• stationary objects look blurrier than moving ones?

Moreover, such small explorations are relevant to present/future invention and job opportunities in science, engineering, medicine, criminology, biology, chemistry, electronics, and space science, as well as to our lives and the lives of those around us.

The links on this page are designed to collect ideas, for teachers and students, on putting these newfound tools to use as early as is possible and appropriate in the educational process.

Size effects

Mass versus size for various objects. 1[Dalton] ~ 1.66[yoctogram].

Effects that might visit you in everyday life

• Thick-cut french fries absorb some oil, but thin-cut fries (because of their larger surface to volume ratio) may absorb much more. French-fry cutters at McDonald's have been made out of the same hard maraging steel that was used for the lunar rover's axle, because oil uptake is also an issue for the vendors. Where else is this effect important?
  • Sauce absorption by angel hair versus regular pasta.
  • Time to cook a potato versus the size of the pieces.
  • What else?
• Large objects fall quickly, feathers fall more slowly, but particles smaller than 0.1 micron may never make it to the ground ‘cause of molecule impacts. Where else is this effect important?
• Iron roofs don’t burn, steel wool burns reluctantly, but nano-iron may oxidize so fast that it catches things around it on fire when you turn on the light! Where else is this effect important?
• Ferrofluids act like liquids 'til a magnet walks by and they turn into giant leaches with spikes on their back. What causes this "Terminator 2" type of effect?
• Ballet dancers can be spun on point (it would seem) as slowly as they like, but not so with a virus particle. Why not?
• What else?

Related questions

• How do you tell when processes on small scales are involved in an experience?
• How can you guess what effect size might have on e.g.
  • making protein spheres “taste” like rich and creamy fat,
  • making a thin film change color,
  • making a rope stronger,
  • making catalyst particles more effective,
  • keeping particles from settling out of air or water, or
  • making a sno-cone more likely to give you an “ice-cream headache”.
• How to communicate an awareness of possibilities (e.g. even some of the simplest nanoscale devices have not yet been invented) and limits of our current tools for interacting with things on small size scales.

One's world according to size

Size effects cartoon. Click for more.

Macroworld

• Tides and Coriolis are weak.
• Gravity and inertia rule.
• Electrostatics distract.
• Touch is extra.
• Terminal velocity is high.
• Heat signals molecule motion.
• What else?

Microworld

• Forget tides and Coriolis.
• Gravity and inertia are weak.
• Electrostatics is scary.
• Touch is manageable.
• Terminal velocity is slow.
• Brownian motion jostles.
• What else?

Nanoworld

• Touch is extreme.
• Colloids don't settle.
• Heat careens and jiggles.
• Most atoms near surface.
• Energies are quantized.
• Electrons are fuzzy.
• Slow spins disallowed.
• Measurements alter.
• What else?

Size range table

The shift in emphasis on various processes depending on the size-scale of one's world.

Effect\Size-Range	MacroWorld	MicroWorld	NanoWorld
Tides & Coriolis	Weak	Negligible	What's that?
Gravity & inertia	Important	Weak	Negligible
Electrostatics	Distracting	Scary	Off the charts
Touch	Extra	Manageable	Extreme
Terminal velocity	High	Slow	Nearly zero
Heat/Brownian motion	Signals random motion	Jostles	Careens & jiggles
Atoms near surface	Few	Many	Most
Energies	Allowed in bands	Odd states are important	Discrete values only
Slow spins	No limit	Slow in steps	Disallowed
Electrons	Shocking	Polarizing	Fuzzy
Measurements	Possible?	Intrusive	Perturbing

Some useful numbers

Useful numbers for equidimensional (e.g. spherical) solid or liquid objects on selected size scales.

Name of scale	Minimum diameter	Min. volume in [Å3]	Number of atoms at 7×1022 [atoms/cc]	Min. surface area in [Å2]	# surface atoms at 1015 [atoms/cm2]	Max. fraction of atoms on surface	Example
Milliworld-2	1[cm]=108[Å]	(π/6)×1024	30×1021 +	π×1016	3×1015 +	0.0000001	sugar cube
Milliworld-1	1[mm]=107[Å]	(π/6)×1021	30 quintillion +	π×1014	30 trillion +	0.000001	flea
Microworld-3	100[μm]=106[Å]	(π/6)×1018	30 quadrillion +	π×1012	300 billion +	0.00001	sand grain
Microworld-2	10[μm]=105[Å]	(π/6)×1015	30 trillion +	π×1010	3 billion +	0.0001	pollen
Microworld-1	1[μm]=104[Å]	(π/6)×1012	30 billion +	π×108	30 million +	0.001	cell
Nanoworld-3	100[nm]=1000[Å]	(π/6)×109	30 million +	π×106	300 thousand +	0.01	organelle
Nanoworld-2	10[nm]=100[Å]	(π/6)×106	30 thousand +	π×104	3 thousand +	0.1	virus
Nanoworld-1	1[nm]=10[Å]	(π/6)×103	30 +	π×102	30 +	1	buckyball
Picoworld-3	1[Ångström]	(π/6)	1 +	π	1 +	1	atom

In addition to major size differences between nanoworld objects at opposite ends of the thirty to 30-billion atom continuum, there are also important practical differences. For example, Nanoworld-1 and Nanoworld-2 objects may see the walls of a blood vessel as porous and therefore in medical applications not be possible to deliver from point A to point B using the circulatory system alone. Hence packages for intravenous delivery are often designed to have sizes in the larger Nanoworld-3 (30 million to 30 billion atom) range.

On the other hand, solid objects containing fewer than 3 billion atoms may be more appropriate for ejection into the interstellar medium by radiation pressure from the sun so they can overcome both Poynting Robertson drag as well as the sun's gravitational pull. A gaggle of such tiny "spaceships" (like those our carbon atoms came here in) might fan out on their own across the Milky Way in under a billion years, although what they do beyond that (if anything) will depend on the details of their structure.

The figure below shows that for solid and liquid phases of wide-ranging density in [grams/cc] that the number η of [atoms per cubic centimeter] is remarkably constant. A typical value is η = 7×10²² [atoms/cc], which translates into a typical distance of η^-1/3 ~ 2.4 [Å] between atoms with 3D kissing-number 12. Some atoms, like carbon, accomodate directionally-correlated (e.g. tetrahedral) bond lengths which are closer to 1.5 [Å]. If such directional bonds don't shorten enough to compensate for fewer nearest neighbors, the solid floats on the liquid which is why SiO₂ continents don't sink and why fresh-water fish can avoid freezing in the winter. Thank goodness!

Atomic number densities for the elements (solids and liquids in the top row) at standard temperature 25[^oC] and pressure 101.325[kPa].

Surface interactions

Subsystem boundaries have played a key role in the natural history of invention, and in the evolution of correlation-based complexity on earth. Physical surfaces are one important example of such boundaries, and one that we turn our attention to here.

Since object surfaces are their connection to the world around, their properties are important even for macroscopic objects. The fact that smaller objects are more surface and less bulk, nonetheless, provides clues to how things change as one shrinks down.

Here we start a table of interesting surface properties. Please improve it as you get the chance.

Phases associated with surface-interaction between bulk materials and air, plus some of their applications.

Bulk solid	Surface composition	Important properties	Surface material applications
Carbon	CO, CO2	clear gases at STP	solar nebula C>O ⇒ carbide instead of silicate planets, photosynthesis reduces CO2 into carbon-based life, trapping atmospheric heat
Silicon	SiO2 glass	2nm thick fairly-hard solid at STP, good electrical insulator, optically clear, chemically stable	floating continents, glassware, windows, integrated circuit gate oxides and insulating layers
Aluminum	Al2O3 sapphire/corundum	very hard solid, good insulator, optically clear, chemically stable	polishing compound, jewelry, ceramic insulators
Copper	Cuprite (Cu2O) and tenorite (CuO)	soft solids, conductive, green	electrical circuit wiring and contacts
Gold	?
Iron	Hematite (Fe2O3), goethite (FeOOH), magnetite (Fe3O4)	conducting magnetic solids, red/yellow/black ochre	pigments, navigation, data storage, ferrofluids
Platinum	?
Silver	silver nitrate (AgNO3)	soft conductive solid	tarnish, precursor to alkali halides in film, antibacterial
Titanium	rutile, anatase and brookite (all TiO2)	white high-refractive index solids	pigments, photocatalysts
Zinc	zincite (ZnO)	white semi-conducting piezo-electric solids	vulcanization catalyst, pigment, food additive, anti-corrosion coating, nanosensors and power devices

Tales of exploration

News and notes

• Note in Technology Review on unzipping nanotubes.
• Water splitting with synthetic photosynthesis.
• Neutralizing smoke with aerosol catalysts.
• Lotus effect and other self-cleaning surfaces.
• Nanoelectronics in hand and in the works.
• Energy-producing clothes to keep your batteries charged.
• Invisibility cloaks and robotic insects.
• Catalysts that reduce manufacturing costs bigtime.
• Non-invasive aneurism and cancer treatment kits.
• Automobiles that clean the air as they run.
• The story of nanosilver and happy socks?
• Hydrogen fuel storage in a solid matrix.
• The milky-way nannite challenge.
• What else?

Lab/Web sites

Size/mobility range blindspots.

• Tina Carvalho's Microangela Gallery at University of Hawaii (Manoa)
• The David Scharf poster set at Microscopy Today
• Dennis Kunkel's watermarked bug mugs, also at UH
• A flyer on Trans-nano Electron-assisted self-Miniaturization (TEM?)
• Pics for a Post-Dispatch article on Work and Play in the Nanoworlds of St. Louis
• The Center for NanoScience MIST Lab

Cross-disciplinary texts

Books with a non-technical flavor include

• Bainbridge,
• Di Ventra, Evoy & Heflin
• and what else?

Books with more technical flavor include

• Wolf
• and what else?

Fiction

• Gulliver's Travels by Jonathan Swift, 1727
• The Nutcracker and the Mouse King by E. T. Hoffman, 1816 (Amazon)
• Alice's Adventures in Wonderland by Lewis Carroll, 1865
• Mr. Tompkins in Wonderland by George Gamow, 1940 (Amazon)
• Engines of Creation by K. Eric Drexler, 1987 (Amazon)
• Two Bad Ants by Chris Van Allsburg, Houghton Mifflin, Boston, 1988 (Amazon)
• Alice in QuantumLand by Robert Gilmore, 1995 (Amazon)
• The New World of Mr. Tompkins by Gamow and Stammard, 1999 (Amazon)
• Shrinking Mouse by Pat Hutchins, Scholastic, New York, 2000 (Amazon)

Television/Print series

• Sherlock Holmes by Sir Arthur Conan Doyle, 1859-1930 (cf. "Doyle" search here)
• Quincy (reruns on A+E Cable TV)
• Crime Scene Investigation (CBS, Fall 2000, Fri 9pm ET)

Movies and videos

• The Incredible Shrinking Man, 1957 (Amazon)
• Fantastic Voyage, 1966 (Amazon)
• Willie Wonka and the Chocolate Factory, 1971
• The Incredible Shrinking Woman, 1982 (Amazon)
• Inner Space, 1987
• Honey - I Shrunk the Kids, 1989 (Amazon)
• Honey - I Blew Up the Kid, 1992
• Honey - We Shrunk Ourselves, 1997 (Amazon)
• A Bug's Life, 1998 (Amazon)
• The inner life of a cell video.

Theatre/Dance/Music

• The Nutcracker Ballet, 1891 by Hoffman/Petipa/Tchaikovsky/Kirov

Views from asmall

Sufficiently small cameras might see things on many size scales at once!

Index	Column 1	Column 2
Row 1	Platinum atoms on graphite in the Saint Louis morning sun.	File:Dmpitlo5.jpg Etched trail of a 238U or 232Th atom recoiling from α-decay
Row 2	File:Practice3.png Pt/ssDNA/SWNT/holey carbon	Atom clusters with blood cell & Andromeda galaxy in background.

What other settings come to mind for use of "small cameras" to provide insight into processes that take place on multiple size scales?

Examples include:

• video games whose character can change size over many orders of magnitude.
• what else?

Tools for exploration

Electron microscope specimen: Microworld-3 scale.

Sites

• Wayne Rasband's open-source image analysis program ImageJ.
• Our lattice fringe practicals page.
• These Jmol diffraction simulators.
• This goniometer for lattice spacing analysis.
• These image and diffraction calculators.

Suppliers

• The Intel-Mattel QX3 (now QX5) Microscope and Notes
• Digital Instruments SPM Shop
• PASCO and other educational nanoworld tools

Training for exploration

Simulators

• Our virtual microscopy and nanoeducation pages.
• Live3D adventures with powers of 10 and spacetime explorers.
• Comparing nanoclues with Jmol molecular models.
• What might you bring back from a nanoworld visit?
• Cells Alive's how big page.
• Molecular Expressions' JAVA Tutorials and 10^N Sim
• Nestor Zaluzec's Microscape Lab at Argonne
• UM-StL HREM Focus & Astigmatism Simulator and other tools
• Toy-scale physics: Re-Volt for RC cars, AirFix for RC planes
• Small world's electron flight simulator
• Visit our weblab, where lightlocks become shrinking machines!
• Kees Boeke's universe in 40 jumps, and Eames'/Bryson's powers of ten.

Class activities

• Microscopy Society of America Activities...
• ...including Cornell's MicroWorld Extension Activities, and...
• ...the GEMS Microscopic Explorations Guide, ...
• ...and the Project Micro home page.
• FSU Activities and Links
• Using LASER Diffraction to Save a Mars Mission Crew
• The fleas on fleas journal for class peer-review of nanoworld and other extreme science investigation reports.

Assessing course knowledge beyond the model itself

How might we broaden our student assessment even in theory courses to credit for any given problem:

• insight concerning the model's choice, suitability, origin & implementation options,
• estimates of the size of prediction errors in this particular problem,
• power in the solution's narrative able to broaden the understanding of others,

as well as the student's facility with...

• relationships suggested by the model (this may be some equations if the models are mathematical), and
• the consequence of these relationships for the specific question (e.g. to solve the equations for the variable of interest)?

Instructional Goals

1) Offer empirical observation challenges patterned after real nano-world adventures.

For example, begin with applet-based "virtual-microscope" models that provide geometric information on size scales ranging from macroscopic to atomic, and access to...

(a) visceral experience with objects ranging in size from millimeters to atoms

(b) real-world characterization problems open to a wide range of problem-solving styles

(c) tasks start with description/estimation of distances, areas, volumes, and shapes...

(d) ...but can extend to molecule recognition, crystal defect analysis, even nano-assembly.

In some cases through telepresence, web-mediated access to real live structures on the micron and atomic scale will become possible in the years ahead.

2) Offer access to diverse and robust forms of data to work with...

...including a wide diversity of viewpoints, magnifications, data output formats (e.g. prints, digital images, machine estimates) and calculation tools (e.g. 2D Fourier analysis). In the long run, ability to examine a large number of different: regions (presently limited mainly by memory sizes), signals (e.g. diffraction patterns, x-ray and electron energy spectra, force and I-V curves, secondary and backscattered electron images, etc.) and contrast processes (electron phase contrast, diffraction contrast, darkfield and weak-beam contrast, z-contrast, etc.) will be offered as well.

3) Work with models that are in practice unknown, and accessible only through a window which involves some experimental uncertainty so that a "literature of discovery" on individual specimens might in fact be developed over time.

In other words, there is no one right answer or correct way, but only style and resourcefulness and credibility in putting quantitative constraints on what is present in the specimen. As with real world specimens, a literature of discovery (including responsibility for citing previous results) might develop on some of the virtual specimens.

4) Four use-formats considered:

(a) lab notebooks ⇒ scientific report ⇒ peer review (home-project format)

(b) group discovery, model development, and white boarding (modeling-workshop format)

(c) individual estimation ⇒ group estimation ⇒ class discussion (peer-instruction format)

(d) timed empirical-observation challenges for the individual explorer (exam format)

5) All of the tools (so far at least) can be made available free to web-accessible classrooms

One objective here is to let energetic teachers drive content modernization as well as pedagogy, giving book publishers an option to do something they are much better at than modernization, namely following the market.

Overview

Individual teachers, equipped with materials they and their students can access via the web, are a developing force in the modernization of both pedagogy and content. Although inquiry-based learning is oft considered a method for helping students master facts and algorithms, the perspective from the modern workplace is that empirical discovery and reporting skills in the subject matter of a course deserve to be a goal in themselves. We show here how the nano-frontier provides a robust setting for challenges that put the student in the shoes of real nano-world detectives, and how diverse challenges can be made available on the web by a single "virtual unknown" for students at home, in lecture settings, and even on timed tests.

Our group has provided industry and university researchers across the state with access to new methods, and atom-resolution microscopy capability using both electrons and scanning probes, for over a decade. In addition, we’ve also had opportunities to further regional contributions in both materials astronomy (the laboratory study of small but previously stand-alone astrophysical objects) and gigascale integrated circuit silicon manufacturing. These experiences, and our contacts as part of a robust and growing regional nano-characterization alliance, give us insight into characterization tools, methods, applications, and most importantly a large and growing list of past and future challenges.

In this context, the proposed project activities will:

• (i) expand the list of web-accessible nano-worlds that we presently make available,
• (ii) develop and deploy storylines suitable for a variety of introductory undergraduate science courses based on real (past, present, or future) characterization challenges along with evaluation rubrics in the form of nano-world WebQuests, and
• (iii) implement/evaluate the effect of these exercises during two years of introductory classes at UM-StL involving a total of about one thousand students.

The goals with respect to participating students are to:

• (a) increase understanding and ability to gather data, discern patterns, and solve problems posed by real nanoworld studies involving the subject matter of each course;
• (b) understand and successfully participate in a peer-review of their, and another student’s, report about nano-world observations specific to course subject matter; and
• (c) enhance awareness of the nano-world, and challenges posed by characterization of matter down to the atomic scale, as it may be encountered in later course work and careers.

Broader Impacts

• 1) Observation and reporting challenges for courses elsewhere: The materials being developed will be deployed on the web concurrently with their use in our courses, and hence immediately available to web connected classes everywhere. To get the word out, we are talking with regional organizations already (e.g. Saint Louis Area Physics Teachers, American Chemical Society, American Association of Physics Teachers, Central States Microscopy and Microanalysis Society). This project will convert teaching assistants into active meeting participants. It further allows us to follow through on undergraduate education committee interest in teacher workshops at national AAPT meetings, and request by an Am. J. Phys. co-editor for a paper on the strategy. A paper for J. Chem. Ed. may be prepared as well.

• 2) Web-based content-modernization generally: It is difficult for text publishers to lead content-modernization, particularly if the courses don’t directly address specific career needs of the students taking them. This project generates material for augmenting existing (and two emergent content) classes, and makes it available for use by web-connected teachers worldwide. Given the need for inquiry-based content tied to real-world challenges, it could offer a significant contribution by making figures "come to life" in a variety of intro-science classes.

Fleas on Fleas Lab

• Apparatus
  • One possible virtual microscope applet
  • How would you like to see this improved?
  • Know any students who'd like to help?

• Pre-lab discussion

• Lab performance notes

cf. these rubrics for scientific interaction.

• Post-lab discussion

Powers of Ten Lab

• Apparatus
  • A possible powers of 10 explorer applet
  • How would you like to see this improved?
  • Know any students who'd like to help?

• Pre-lab discussion

• Lab performance notes

• Post-lab discussion

See Also

• Version of this on wikibooks.
• An earlier web page on this subject.