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NOVA scienceNOW: Profile: Naomi Halas
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Viewing Ideas
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Before Watching
Play a game to understand the size of a nanometer. A nanometer
is one-billionth (10-9 or 0.000000001) of a meter, which is about
25-millionths of an inch. Objects that are a few to several hundred nanometers
in width are called a nanoparticles, and nanotechnology is the
science of manipulating nanoparticles. Relating objects that are nanometers in
size to larger, more familiar objects can help students understand just how
small this measurement is. One nanometer is about the size of 10 hydrogen or 5
silicon atoms, and the width of a human hair is about 80,000 nanometers. Have
students visit the Web sites listed in the Resource section and find four
pictures (or draw four images) of objects at each of the following sizes:
meter, millimeter (one-thousandth of a meter), micrometer (one-millionth of a
meter), and nanometer. For example:
Meter—two-year-old child, medium-sized dog, poster, height of some
plants and shrubs Millimeter—pin, thickness of a dime, thickness of some cardboard Micrometer—human hairs (about 200 micrometers), pollen, red blood
cells, baker's yeast, some bacteria Nanometer—viruses, width of strands of DNA and RNA, thickness of a
cell membrane
Have students mount each picture on a separate index card. For each of these
cards, have them make a corresponding card that either names the appropriate
unit of measure (e.g., meter, millimeter, micrometer, or nanometer) or states
the number of the appropriate unit of measure (e.g., 1 meter or one-thousandth,
millionth, or billionth of a meter). Have student pairs use the cards to play a
matching game, like Concentration.
Examine the periodic table of elements. Naomi Halas uses gold
nanoshells in her cancer research. Gold has unique properties and research
applications that make it an ideal material for her to use. Have students study
the periodic table and identify the metals, nonmetals, and metalloids. Have
them locate gold (atomic number 79). On the board, list the physical and
chemical properties of metals.
Physical properties: Metals are usually solids that conduct heat
and electricity well, are ductile, have high luster and densities, and are
malleable. Chemical properties: Metals lose electrons easily and corrode
State some of the properties that make gold such a useful metal for
nanotechnology:
Resistant to surface oxidation (i.e., corrosion) A gold nanoparticle's size influences its behavior. For example,
different sized particles have different melting temperatures, different
electrical conductivity properties, and can be different colors (ranging from
red to purple). Gold nanoparticles can be manipulated to absorb or scatter light in
different ways.
Research careers in engineering. Engineers design such items as cars,
planes, computers, buildings, bridges, roller coasters, movie special effects,
sports equipment, spacecraft, and medical devices. Yet while engineering shapes
our world, most students have a limited understanding of engineering.
Typically, they think engineers need to be expert in both mathematics and
science, and they perceive it to be a man's profession, very difficult, and
nerdy. Rarely do they see that engineering can be a rewarding, enjoyable career
that pays well, provides flexibility, and enables people to make a difference.
To help students learn about the field of engineering, assign different
engineering careers to student pairs and have each pair produce a poster that
includes related pictures (from magazines) and the following information:
Branch of engineering (e.g., biomedical, chemical, civil, electrical,
computer, nuclear, aeronautical, agricultural, robotic, etc.) The kinds of problems engineers in this field solve The ways engineers in this field make the world a better place The academic subjects someone might study to become this kind of
engineer The groups or local efforts that might support an interest in this kind
of engineering Some of the advantages of a career in engineering Some of the obstacles for people wanting to enter the field of
engineering
If possible, invite a parent or guest speaker who works in an engineering field
to discuss his or her career with the class.
After Watching
Conduct a survey on attitudes toward engineering. Naomi
Halas noted that she only started studying calculus and physics in college.
Yet she found that she did well in these subjects and enjoyed them enough to
become an engineer rather than a musician. Have the class develop and conduct a
survey to explore the attitudes of students at their school toward physics and
mathematics. Use the following items or modify them as appropriate:
On a scale of 1-10, indicate how strongly people in your survey agree
with the following statements. (10 = strongly agree)
Engineers enjoy what they do. Engineers make a meaningful difference in the world. Engineering is challenging. Engineering enables you to work with others in enjoyable ways. Engineering is a flexible career. Engineers earn high salaries.
On a scale of 1-10 (10 = very high), rate your interest in science. On a scale of 1-10, rate your interest in mathematics. How many people do you know well who have careers in science and/or
mathematics?
Have student teams collect, analyze, and present their survey data. What (if
any) patterns do you see in terms of age and gender? If possible, arrange to
have the class's findings published in your school newspaper or school
bulletin.
Discuss how character traits relate to work and career choices. Naomi
Halas expressed that engineering is sometimes a difficult field, particularly
for women. What personal qualities and character traits does Dr. Halas have
that make it possible for her to not only stay in this field but to lead and
inspire a team of engineers, do work that matters to herself and others, and
live a satisfying, fulfilling life?
Demonstrate that metal is an effective conductor of heat. One
potential application of Halas's work is as a treatment for some forms of
cancer. She and her team of scientists have been able to direct gold nanoshells
to cancerous tissue. They then shine light on these tissues. The concentration
of gold in cancerous tissues causes them to heat up to about 55 degrees Celsius
(131 degrees Fahrenheit), killing the cancerous cells but not the healthy cells
around them, which contain no gold nanoshells. Gold has many properties that
make it invaluable to Halas's research. One property is its ability to conduct
heat well. Another is its ability to reflect infrared (heat) energy well. These
two properties, and Halas's ability to direct the gold to cancer tissue, make
it an excellent material for killing cancerous cells. Have students perform the
following activity to explore how different materials absorb and transfer heat.
In a 250 ml beaker, heat about 150 ml of water to about 85 degrees Celsius.
Stick a pat of butter at the top of rods made from different materials (i.e.,
plastic, glass, wooden, and metal). Place the rods into the water, butter-end
up. Make sure the rods stand at a tilt so the heat rising from the surface of
the water does not melt the butter. Have students observe when the butter falls
off each rod, and rank the materials in terms of how well they conduct heat. (From best to worst conductor, the ranking will be: Metal, glass, plastic, wood.)
Web Sites
Attracting and Retaining Women in Science and Engineering
http://www.aaup.org/publications/Academe/2003/03ja/jaross.thm
Summarizes issues related to the under-representation of women in science and engineering.
Exploring Careers
http://www.enc.org/features/focus/archive/
engineerweek/document.shtm?input=FOC-003414-index
Directs users to information on a variety of engineering careers.
Metals, Nonmetals and Metalloids
http://www.web.buddyproject.org/web017/web017/metals.html
Presents information about the physical and chemical properties of metals and nonmetals.
Properties of Gold
http://www.gold.org/discover/sci_indu/properties/
Reviews the chemical and mechanical properties of gold.
Books
Morrison, Phillip and Morrison, Phylis. Powers of Ten.
New York: Scientific American Library, 1982.
Explores the scale of things in our universe and shows what objects look like at different scales.
Reid, Des, editor. Eyewitness Visual Dictionary: Chemistry.
New York: Dorling Kindersley, 1996.
Presents the periodic table of elements and describes element groups in detail.
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