00:00:30 After simulating weightlessness, NASA technicians connect experimental hollow struts that one

00:00:34 day may be the external frame of a space station or huge communications array.

00:00:40 Each two-piece strut weighs less than eight pounds.

00:00:43 Developed at NASA's Langley Research Center in Virginia, they're molded of what chemists

00:00:47 call a composite, laminated plies of a plastic glue and reinforcing fibers.

00:00:53 In the aerospace community, composites have a tremendous advantage.

00:00:58 They're lightweight, and they're very strong, and they're very stiff.

00:01:02 In composites, different fibers and chemical mixes offer different qualities and economies.

00:01:07 Some are stronger than steel, but a fraction of the weight.

00:01:10 For the space struts, NASA prefers a graphite composite.

00:01:14 The struts were turned out by automation, but the same principles are demonstrated in

00:01:17 making a panel by hand.

00:01:20 As they wrap around a drum, the graphite fibers are saturated by a resin.

00:01:24 Sheets of the material are then crisscrossed atop each other.

00:01:27 After pressurized heat curing, the composite comes out a strong, chemically bonded, lightweight

00:01:32 panel.

00:01:33 The struts have the same properties.

00:01:36 Graphite composites are lighter, stiffer, and stronger, and will not expand when heated

00:01:44 or contract when cooled.

00:01:47 Composites aren't just for space.

00:01:49 They're substituting for metal in products from cars to army helmets to golf clubs.

00:01:53 But many aerospace chemists consider them the material of tomorrow for their many potential

00:01:58 uses.

00:02:00 Composites now form tail and wing sections of some airliners and jet fighters, and the

00:02:04 space shuttle doors are made of a composite.

00:02:07 Soon, the shuttle's booster rocket casings will be switched to a composite.

00:02:12 Composites strong and lightweight.

00:02:14 How light?

00:02:15 Well, consider the struts that may be used to form the frame of a station in space.

00:02:20 Put together, 16,000 two-piece sections could be carried by a single space shuttle.

00:02:27 On the Science Scene, I'm Alan Smith.

00:02:50 This computerized image is a cross-section of a normally functioning human brain.

00:03:09 This shows reduced brain activity from Alzheimer's disease, senility caused by the death of nerve

00:03:14 cells in the brain.

00:03:16 Both pictures were produced by Positron Emission Tomography, PET for short, a donut-shaped

00:03:21 scanner that detects and shows the brain's chemical activity or lack of it.

00:03:26 Quite often in disease states, the brain anatomically looks normal.

00:03:30 The brain looks normal on a CAT scan.

00:03:33 It even looks normal after death under the microscope.

00:03:37 But while the patient is alive and having severe neurologic difficulties, his brain

00:03:42 isn't metabolizing.

00:03:43 It's not working properly.

00:03:45 The PET scanner can show us where these problems are in the brain.

00:03:50 In this demonstration by the National Institutes of Health in Maryland, a volunteer has received

00:03:55 an injection of radioactively labeled molecules of glucose, a sugar.

00:04:00 The brain uses glucose for energy so that when brain cells work, glucose is being metabolized,

00:04:06 is being used up in order for the neurons, the brain cells, to do their job.

00:04:12 And that glucose, if it's tagged with a positron emitting isotope, gives off its location under

00:04:18 the scanner, and we can see what parts of the brain are involved.

00:04:22 On the PET screen, the heaviest chemical action shows up in red.

00:04:25 This is a scan of a normal person, and you can see that on both sides of the brain, the

00:04:33 metabolic rates are equal.

00:04:35 That's not the case in this scan of an elderly person with memory loss.

00:04:39 In this patient with Alzheimer's disease, this particular area and the whole left side

00:04:45 is not working as well as the right side, not working as well as it should be.

00:04:50 Of itself, PET can't explain why we think or the causes of mental problems, but as a

00:04:55 research tool that sees the chemical activities of the brain, PET may eventually provide insights

00:05:01 that could lead to a greater understanding of the workings of the human mind.

00:05:06 On Science Scene, I'm Alan Smith.

00:05:38 Music

00:05:45 After 70 years or so, many of our library books look like this.

00:05:49 They've disintegrated from within, largely from the very acids used in making their paper

00:05:54 and ink.

00:05:55 Forty percent of the books in a major library typically are so brittle, they cannot be read.

00:06:03 Libraries have been able to do little to prevent this slow self-destruction, except to preserve

00:06:07 a special few books by hand at $200 each, too expensive for treating thousands.

00:06:12 But the chemical engineer we just heard, Richard Smith of Witeau Associates in Madison, Illinois,

00:06:18 has developed for Canada's National Library and Public Archives the first major online

00:06:23 system for mass-preserving books chemically by deacidification.

00:06:27 In full production, says conservator Jan Padek, it can treat some 120,000 books a year for

00:06:33 but a few dollars each.

00:06:35 This is a liquefied gas process using alkaline chemicals that permeate the books and neutralize

00:06:42 the acids in paper and ink.

00:06:45 The treatment begins with racks of books vacuum-dried 24 hours to remove moisture, then two racks

00:06:51 at a time into a pressure tank for an hour.

00:06:54 There the books are saturated by a liquefied gas solution of the neutralizing alkaline

00:06:58 chemicals.

00:07:00 After excess solution is drained off, the neutralizers are flash-dried into the paper

00:07:04 and the books are ready for a ripe old age.

00:07:07 If we can get to it in time, we can prolong the book's life three to four times from

00:07:12 100 to 400 years.

00:07:14 With Canada operating the Witeau chemical process and the Library of Congress developing

00:07:18 another type of system, it reflects a concern that the important works we pass down amount

00:07:24 to more than crumbling pages.

00:07:27 Think of the United States today with no copies of William Shakespeare's works.

00:07:33 We have similar authors living today, and future generations will not have those available

00:07:40 unless we have nasty acidification processes.

00:07:43 On the science scene, this is Alan Smith.

00:08:03 What we have just formed is molten iron.

00:08:23 Chemistry Showman, Dr. Bassam Chakashiri.

00:08:26 Dr. Chakashiri heads the University of Wisconsin's Institute for Chemical Education.

00:08:32 As a way to spark an early interest in chemistry among youngsters and perhaps also provide

00:08:36 adults with a greater understanding of the science, he believes in making it fun.

00:08:41 He's performed for hundreds of schoolchildren in Wisconsin and has taken his show on the

00:08:45 road around the country to rave reviews.

00:08:50 We call this an oscillating chemical reaction because the colors continue to oscillate.

00:08:56 And one of the fascinating things about chemistry is that we try to understand why this behavior

00:09:01 takes place, and that's why we do research.

00:09:04 In his hour-long performances, Dr. Chakashiri entertains his audience with more than a dozen

00:09:09 demonstrations, each aimed at showing how chemicals react under different circumstances.

00:09:15 In this case, liquid oxygen poured over a giant magnet.

00:09:18 You see that the liquid is held between the poles of the magnet, indicating that this

00:09:23 liquid has paramagnetic properties similar to the properties of the knife that I, the

00:09:28 pocket knife that I used before.

00:09:30 Whether demonstrating the force and color of various kinds of gases set to the torch,

00:09:34 or how pieces of rubber tubing frozen hard by liquid nitrogen can be nailed into wood,

00:09:40 Chakashiri teaches as he entertains, often involving the youngsters in experiments so

00:09:46 they'll better understand chemical processes, like why spaghetti bubbles up in water with

00:09:51 vinegar and baking soda.

00:09:53 And this showstopper is a popular finale with the kids.

00:09:57 Chemi-luminescence, a chemical reaction producing light, but little heat.

00:10:01 Here we go.

00:10:08 Holy smokes!

00:10:10 And with that, Dr. Chakashiri caps his performance.

00:10:13 For some, he hopes it may lead to a career in science, and for all, a better understanding.

00:10:19 I want to thank you for being here today, and I want you to all think about why chemistry

00:10:24 can be fun.

00:10:25 Thank you.

00:10:26 On the Science Scene, I'm Alan Smith.

00:10:57 Chemists sometimes spend years making and testing thousands of compounds before hitting

00:11:08 on that precise molecular mix that produces a new medicine, or a stronger plastic, perhaps.

00:11:14 Now though, with computers, they're beginning to telescope much of that laboratory time,

00:11:19 using computers to model three-dimensional images of molecules and atoms for predicting

00:11:24 or simulating chemical reactions.

00:11:26 What we're modeling here is a reaction actually as it takes place at the transition state.

00:11:31 The color coding is by atomic type, so the carbons are black, the hydrogens are white.

00:11:36 This group comes in and attacks the middle of this group, and as the reaction takes place,

00:11:41 this group is expelled out the side.

00:11:43 David Penzak of DuPont's Computational Chemistry Unit, one of the most advanced in this still-developing

00:11:48 field.

00:11:49 Computer graphics, he says, are beginning to open up a whole new range of research possibilities

00:11:54 in chemistry.

00:11:55 With the computer, you have the ability to show a variety of three-dimensional aspects

00:12:00 of your molecule, which includes the shape, the electronic features, things which make

00:12:04 a molecule attractive to another molecule.

00:12:07 You can't do this very well on a sheet of paper.

00:12:10 But more than that, Dr. Penzak goes on, chemists can visually test theories.

00:12:15 With animation ability, fly molecules around the screen, dock them with others, rotate

00:12:20 them, even see inside, all for a better understanding of chemical properties and how they interplay.

00:12:26 We can produce a semi-transparent effect, so you get a feeling for where the surface

00:12:30 of the atoms are, but you can still see the wire frame that shows where everything is

00:12:34 tied together.

00:12:35 So now we can include a variety of additional information we've never been able to do before,

00:12:41 and let our chemists see property-space relationships that they have not been able to do to date.

00:12:47 Any new thing they can see gives them a chance to be more creative.

00:12:51 And that's the whole point of modeling molecules by computer, giving the chemist an extra dimension

00:12:56 that allows him to expand his own creativity in ways never before possible.

00:13:01 On the Science Scene, I'm Alan Smepp.

00:13:04 Dr. Chandra and other biochemists believe that with adequate resources and today's

00:13:21 advances in technology, within five to ten years, homegrown Wyoli could be supplying

00:13:27 us with all the material we need for all our rubber products.

00:13:31 On the Science Scene, I'm Alan Smepp.