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NOVA scienceNOW: Profile: Naomi Halas

Viewing Ideas

Before Watching

1. 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.

2. 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.

3. 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

1. 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.

2. 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?

3. 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.