INquiry Science and Technology at the Ames Laboratory 2001

New superconductor

 is on the scene

Chemical separation technique

 wins R&D 100 Award

Polymers and quasicrystals —

 an unlikely mix

Novel metal filter

 cleans up

A U.S. Department of Energy laboratory operated by Iowa State University

AMES LABORATORY
(back cover) New high-performance polymers at various stages, including the starting crystalline materials, a liquid polymer reaction mixture and

a final, isolated solid polymer.

Contents

(front cover) Magnesium diboride, or MgB2, wire segments, called “angel

hair” because the growth looks like angel-hair pasta, are pictured near a

U.S. dime for scale. [Physical Review Letters 86 (2001) 2423]

2 Old Material Makes a New Debut . . . Saren Johnston

 Ames Laboratory physicists are lavishing their attention on an old material with newly discovered

 superconducting capabilities. In quick order, they have described the mechanism of superconductivity

 in the material, mapped its properties and made it into wire segments.

5 Molecular Roller Coaster Analyzes Compounds . . . Robert Mills

 An analytical method developed at the Ames Laboratory provides a powerful new tool for chemists

 and biologists — and leads to the launch of a new company.

8 Polymers Plus Quasicrystals Equals A Puzzling Interaction . . . Mary Jo Glanville

 Valerie Sheares took two materials that don’t like contact with other things, mixed them together and created

 a composite that has amazing properties.

 11 Closing in on Cancer . . . Saren Johnston

 Ames Laboratory’s novel biosensor technology could ease the process of determining an individual’s

 risk of getting cancer.

13 Dirty Coal, Clean Power . . . Kerry Gibson

 Ames Lab metallurgists are closing in on a metal filter material that can withstand the high temperatures

 and corrosive environments inside coal-fired power plants.

 16 INtouch

 Get in touch with more of Ames Lab’s successful science.

18 Building the Buckyball a Bowl at a Time . . . Kerry Gibson

 Most of us recognize carbon as a black powder, a sparkling diamond, or the graphite used

 in pencil lead and golf club shafts. But it’s a much rarer form of carbon — the buckyball —

 that intrigues Peter Rabideau.

 20 Random Acts of Brightness . . . Saren Johnston

 A computer model developed by Ames Laboratory theoretical physicists is

 lending credibility to observations of unexpected and amazing laser activity in

 materials that trap and scatter light.

23 New Life for Old Scrap . . . Kerry Gibson

 When a composite material can’t easily be broken down into its various

 components, recycling it poses a problem, especially when one of those

 components is the valuable rare-earth element, neodymium. But two Ames Lab

 scientists have found a way to keep element number 60 on the periodic table

 from winding up on the scrap heap.

MgB2 wires

polymer solution
from the Director

2001 1 INquiry

 e begin this year’s edition of Inquiry magazine with congratulations to Ed Yeung, who has won

a 2001 R&D 100 Award. Ed’s chemical separation technology potentially could revolutionize the diagnosis

of diseases and development of treatments. This is Ed’s fourth R&D 100 Award and the

14th for Ames Laboratory.

 Ryszard Jankowiak and Gerry Small are also making headway in the war on disease. Their new biosensor chip technology can be used with

urine samples to obtain immediate

information about DNA damage from

carcinogens, providing valuable

information for cancer risk-assessment.

 On the materials front, our physicists made quite a splash in the

scientific and popular press when they

became the first to describe the

mechanism of superconductivity in

magnesium diboride. Then the

physicists went a step further by

mapping the material’s properties and

creating the first-ever magnesium

diboride wire segments.

 Another material has been of special

interest to two other Lab scientists.

They have developed a process that

could finally offer industry a commercially viable way to recover neodymium from the tons of magnetic scrap piled up in warehouses

across the country awaiting recycling. The method they’ve discovered is simpler to use

and less expensive than existing technology — two attributes that are music to the ears of industry.

 Also on the environmental front, Iver Anderson has developed a new metallic filter for use in power

plants. The new filter, which is made out of a nickel-chromium-aluminum-iron alloy, would allow the

next generation of coal-fired power plants to cleanly burn high-sulfur, dirty coal. More complete

combustion in these plants removes most of the harmful gases, while the filter prevents corrosive and

abrasive particles in the exhaust gas from reaching and damaging the power-plant turbines.

 These are just a few of the fascinating research efforts underway at Ames Laboratory that you’ll

read about in this issue of Inquiry. I invite you to review the many other ways in which our scientists

are working to find solutions to our nation’s energy problems.

Inquiry is published annually by the Ames Laboratory

Office of Public Affairs. Iowa State University

operates the Laboratory for the U.S. Department of

Energy under contract W-7405-Eng-82. Located on

the ISU campus, the Ames Laboratory is a member

of the university’s Institute for Physical Research and

Technology, a network of research and technologytransfer centers and industrial-outreach programs.

Editor

Steve Karsjen

Managing Editor

Saren Johnston

Art Directors

Michael Marti

Janice Weedman

Photographer

Dennis Sailsbury

Copyright 2001 by Ames Laboratory.

All rights reserved. For additional

information about Ames Laboratory

or topics covered in this publication,

please contact:

Editor, Inquiry

Ames Laboratory

111 TASF

Ames, Iowa 50011-3020

(515) 294-9557

www.external.ameslab.gov

W
 Old Material Makes a

 New Debut

For the most part, it was a wallflower for 50 years. Plain and

simple, no one paid it much attention. No one suspected there might

be more to the nondescript tan

powder than met the eye.

Magnesium diboride is a relatively

inexpensive metal compound that

can be purchased in powder form

from most standard chemical supply

companies. Until this year, there

was nothing remarkable about it —

at least nothing that was known.

But the material had never been

investigated for superconductivity

— whether it had the ability to

conduct electricity perfectly,

without resistance, when cooled to

temperatures near absolute zero

(minus 459 degrees Fahrenheit).

 That all changed in January when

Jun Akimitsu of Aoyama Gakuin

University in Tokyo announced he

and his research team had discovered that magnesium diboride

becomes superconducting at 39

Kelvin (minus 389 F), nearly twice

the temperature of current intermetallic, low-temperature superconductors. The news had experimentalists around the world rushing to

duplicate and confirm the

Japanese findings.

 But a team of Ames Laboratory

physicists, including Paul Canfield,

Doug Finnemore and Sergey Bud’ko,

was the first to describe the mechanism of superconductivity in the

material. “One of the things that

allowed us to make progress quickly

was that we figured out how to make

high-purity powders of magnesium

diboride simply, in a two-hour,

turnaround process,” says Canfield.

“We ran several cycles a day, and

then made isotopic substitutions.”

(Isotopes of an element have the

same number of protons, but differ

by how many neutrons are within

each atomic nucleus.)

Figuring out

the superconductivity

 The physicists were very quick in

getting the highest purity samples of

MgB2 with the highest transition

temperature — the temperature at

which a material becomes superconducting. Their experiments showed

that MgB2 sample pellets containing

boron isotopes with an atomic mass

of 11 became superconducting at

39.2 K (minus 389 F), while pellets

containing boron isotopes with an

atomic mass of 10 became superconducting at 40.2 K (minus 387 F). By

changing the mass of the boron, the

physicists saw a 1.0 K upward shift

in transition temperature. “We

wanted to understand the mechanism of superconductivity in the

material,” says Canfield. “And we

found that the shift in transition

temperature caused by the change in

boron mass is consistent with

standard models of intermetallic

superconductivity.”

 Conventional intermetallic

superconductors conform to the

Bardeen, Cooper, Schrieffer theory

of superconductivity, commonly

called the BCS theory, which

explains that the electrons in

superconductors are grouped in

pairs and that the movements of all

the pairs in a single superconductor

are interrelated — they make up a

system that acts as a single entity.

When an electrical voltage is

applied to a superconductor, all the

electron pairs move together

coherently as a unit. The movement

creates a current that will flow

indefinitely, even when the voltage

is removed, because the electron

pairs meet no opposition. This

pairing takes place because the

electrons are attracted to each other

by creating and detecting vibrations

in the lattice. These vibrations

determine a material’s superconducting transition temperature. The

smaller the mass of the superconducting material, the higher the

frequency of the vibrations and the

higher the transition temperature.

by Saren Johnston

2001 2 INquiry
A cross-section of MgB2. Note:

cross section also reveals the

central tungsten boride core of

the original boron fiber.

comes down the pike,” says

Finnemore. “We wanted to see to

what fields MgB2

 remains superconducting, what types of currents it

can carry in the superconducting

state, and how much current it can

carry through the grain boundaries

in the material. So we did conventional measurements on what we

thought was an exotic material, only

it turned out to be kind of ordinary

— the exotic thing is its superconducting temperature.”

 Data the researchers collected on

the properties of the MgB2

 pellets

showed the intermetallic material

Exposing boron fibers to

magnesium vapor for

approximately 120

minutes results in MgB2

wire segments that are

approximately 98

percent dense.

would carry enormous electrical

currents, even though the currents

had to jump across a dense array of

grain boundaries. This property is

far different from that found in

ceramic high-temperature

superconductors.

Ceramic superconductors operate at higher

temperatures than the

intermetallics, some

over 100 K (minus

280 F), and they

require less costly

cooling arrangements.

But intermetallic

compounds are better

at carrying current

across grain boundaries,

making it easier to

synthesize superconducting

wires that can carry large

currents.

Wonderful wire

Soon after mapping the properties

of MgB2, the experimentalists took

on and met the challenge of creating

wire from the material, starting with

boron fibers. In essence, the

researchers came up with a way of

turning straw into gold. They

placed the boron fibers in a tantalum

tube with excess magnesium and

heated it up. “As the magnesium

vapor diffused, the boron sucked it

up — what we were able to do was

turn boron fibers into magnesium

diboride wire,” says Canfield.

“We’ve been making lengths of five

centimeters (2 inches). We call the

growth ‘angel hair’ because it looks

like angel-hair pasta.”

 The researchers found that MgB2

wire has as sharp and as high a

 If a superconductor is

allowed to warm up

past its transition

temperature, the

electron pairs

separate and the

superconductor

becomes a

normal conductor. In all

previously

studied intermetallic compounds,

the electron pairs

usually break apart

when the temperature climbs above 20 K

(minus 424 F). But,

amazingly, the electron

pairs remain together in MgB2

up to 40 K (minus 387 F).

 The 1.0 K shift in superconducting transition temperature produced

in the boron isotope experiments of

Canfield and his colleagues is strong

evidence that the electrons in MgB2

are interacting as described in the

BCS theory of superconductivity.

This would classify MgB2 as a

conventional superconductor, but

with an extremely high and unconventional transition temperature.

And this is, as Canfield says, “a big,

hairy deal.”

How good is MgB2?

 After addressing the mechanism

of superconductivity in MgB2, the

experimentalists then mapped out

the basic properties of the material.

“We do this for every material that

2001 3 INquiry
superconducting transition temperature as the powders they developed

and that the wire is at least 80

percent dense. Development of the

wire also allowed the researchers to

measure the material’s resistivity —

its ability to carry electricity in the

nonsuperconducting state. The

measurements revealed that MgB2

has a resistivity approximately 20

times lower (better) than that of the

reigning niobium-based superconductor at its transition temperature.

 “We made the wire in fivecentimeter segments, but boron

monofilaments are made in kilometer lengths. This opens the

possibility of developing a continuous process in which boron

monofilament is made and then

transformed into this wire,” says

Canfield. But he cautions, “Magnesium diboride is brittle.”

 Finnemore adds, “You can’t spool

it and give someone a mile of the

stuff. It will present challenges to

coat and protect the wire, similar to

those for previous intermetallic

superconductors containing niobium and tin.”

 The work of the Ames Lab

physicists to understand the physics

of MgB2

 progressed at an amazing

pace. Following the January 10

announcement of superconductivity

in the material, the Ames team

addressed the mechanism of superconductivity in the material, mapped

its properties and developed wire

segments along with what appears to

be a means of making long wires —

all in a month’s time.

 Canfield is quick to point out

that there is much more work to be

done, but he notes that MgB2 holds

promise for being the next lowtemperature superconductor of

choice. Because of its higher

superconducting transition temperature, wire made from the material

would not have to be cooled to

temperatures as low as for niobiumbased superconductors, reducing

cooling costs associated with the

quantities of liquid helium required

to operate such systems. Also, there

is a greater abundance of magnesium

and boron than niobium.

 The bottom line, according to

(left to right) Ames Laboratory researchers Sergey Bud’ko, Paul

Canfield and Doug Finnemore are moving forward with their research on magnesium diboride, making longer wires of the recordsetting, low-temperature superconductor.

The crystal structure of MgB2.

Canfield: “With magnesium

diboride, we have something that

maps onto the existing technology of

intermetallic wires, but with a factor

of two higher in transition temperature. However, only time will determine the material’s usefulness.” ◆

2001 4 INquiry

For more information:

Paul Canfield, (515) 294-6270

canfield@ameslab.gov

Research funded by:

DOE Office of

Basic Energy Sciences
ever, Yeung is particularly excited about this technology,

as it has wide-reaching potential.

 “Any kind of chemical measurements that involve

separation can, in principle, be fitted to use this technology,” Yeung says. Indeed, such technology has applications in several burgeoning fields, including combinatorial chemistry, drug discovery, genomics and proteomics

(the study of protein expression and function). Such

instruments are finding increasing utility in pharmaceutical, genetics, medical and forensics laboratories, and

may someday be used in doctors offices.

By size and by charge

 Capillary electrophoresis works on the same principles as gel electrophoresis, commonly used in DNA

fingerprinting. An electrical current (the invisible force)

causes molecules to migrate at different speeds, according to size and charge. The capillaries are silica tubes

about 2 feet long, with an inside diameter of 75 microns

(about the diameter of a human hair). Because these

capillaries can disperse heat so well, an electrical charge

of up to 20,000 volts can be used. The high voltage

means separations can be done in as little as 15 minutes.

“Absorbance detection” describes how the system

detects molecules. Ultraviolet light is focused through a

tiny window to illuminate the capillaries, and the

Jeremy Kenseth, a former Ames Laboratory scientist now

with CombiSep, Inc., evaluates output from the MCE 2000,

a multiplexed capillary electrophoresis machine based on

technology developed at Ames Laboratory.

Visualize a pack of various molecules in a compound, all mingling in a solution. Then imagine

molecules being whisked away from the crowd, one at

a time, into a tiny tube by an invisible force. About

halfway through this molecular roller coaster, the

molecules are flashed with ultraviolet light beamed

through a small window as they scream by.

 Although the molecules may or may not be having

fun, the ride is quite revealing from a chemical viewpoint. The type and quantity of molecules in the

compound can be determined from the time it takes

various molecules to take their ride and from the

amount of ultraviolet light they absorb. Imagine, then,

the vast quantity of information that can be gathered

by running 96 of these roller coasters at the same time.

 That, in short, describes the operation of a new

instrument created by Ed Yeung and his team of

researchers at the Ames Laboratory. Called multiplexed capillary electrophoresis using absorption

detection, this method promises to be faster, better and

cheaper than alternative technologies.

 This breakthrough is only the latest from Yeung,

director of Ames Lab’s Chemical and Biological

Sciences Program and a distinguished professor of

chemistry at Iowa State University, who has a long

history of innovations in analytical chemistry. Howby Robert Mills

2001 5 INquiry

Molecular

Roller Coaster

Analyzes

Compounds
amount of light absorbed by the migrating molecules is

detected by an array of photodiodes. Absorbance

detection makes Yeung’s approach more widely applicable than other forms of capillary electrophoresis.

 The ultraviolet absorption data, along with the time it

takes the molecules to migrate, are sent to a standard

personal computer. Custom software processes the data

to generate charts called electropherograms, revealing

the type and quantity of the separated molecules. The

data can also be exported in tabular form to standard

software packages.

 “Multiplexed” means that

the machine runs several

samples at a time by using

multiple capillaries. The

machine works with 96-well

titer plates to fit standard

laboratory equipment. The

result is automated, highthroughput analysis, a muchsought-after technology in

today’s biotech industries.

Faster, better, cheaper

 Alternatives to multiplexed

capillary electrophoresis with

absorption detection include

high-performance liquid

chromatography and capillary

electrophoresis with fluorescence detection.

 “HPLC is a widely accepted practice,” says Shelley

Coldiron, president and co-founder of CombiSep, Inc.,

a new company formed to turn Yeung’s technology into a

commercial instrument. “We have to educate people

and let them know we can operate comparable to what

they’re getting with HPLC.”

 Another factor working in CombiSep’s favor is that its

technology uses less solvent than HPLC. “We use 1,000

times less solvent than HPLC,” says Coldiron, noting

that this results in lower environmental hazards and

related costs. Although HPLC systems cost much less

than CombiSep’s machine, they are limited to one

analysis at a time. “We can take 96 of those individual

instruments and do the same analyses with one of ours,”

says Coldiron.

 Capillary electrophoresis systems that use laserexcited fluorescence detection are also made in multiplexed versions that can run 96 analyses at a time.

These machines play an essential role in DNA sequencing; in fact, Yeung won an R&D 100 Award for developing just such an instrument in

the 1990s.

 Yeung’s latest technology,

however, can handle a wider

range of compounds, thanks to

its ability to detect molecules

using ultraviolet light. “Only

about 10 percent of all compounds fluoresce naturally,” says

Coldiron, “so you have to put

optical tags on those compounds that don’t fluoresce

naturally.” The “optical tags”

are fluorescent dyes that are

expensive and may be toxic.

 What’s more, multiplexed

systems can be slow at processing all the data that results from

running 96 simultaneous

analyses. “It’s kind of selfdefeating. You’re generating all this data but you get

bottlenecked in data processing,” Coldiron says. To

sidestep this hurdle, CombiSep has written software that

can process the data in approximately 15-30 minutes,

according to Coldiron.

“Right here, and quickly”

 Yeung began his Ames Lab research on the technology

in 1998 when he realized there were limitations on

existing capillary electrophoresis technology. Things

progressed quickly from there. “At the point of publication, we realized it would be commercially viable, so we

filed for a patent,” says Yeung. Yeung soon helped start

what became CombiSep to develop and sell instruments

based on the technology. “I realized we needed to move

extremely fast,” he says. “We had to do something right

here, and quickly.”

 In addition to Yeung and Coldiron, the company’s

founders include Marc Porter, an ISU chemistry professor

and director of ISU’s Microanalytical Instrumentation

2001 6 INquiry

Ed Yeung’s quest to improve chemical separations led to development of multiplexed,

absorbance-based capillary electrophoresis.
The MCE 2000 is a multiplexed, absorbance-based

capillary electrophoresis system made by

CombiSep, Inc. The system can perform 96 separations simultaneously through its array of 96 capillary

tubes (inset).

Center, serving as vice-president; Steve Ringlee, an area

entrepreneur; and Roy Strasburg, director of R&D.

 The market for high-throughput analysis technologies

such as multiplexed capillary electrophoresis is “hot”

right now, according to Coldiron. CombiSep is striving

to get into this market as quickly as possible, especially

as it is competing with several large companies in the

fast-growing, multibillion-dollar market for these

instruments. “There’s always someone out there developing similar ideas,” Coldiron says.

Prototype to product, pronto

For such a complex technology, CombiSep has moved

extremely fast. Although officially founded in December

1999, the company really did not get rolling until April

2000. Since then, the company has made and tested

several prototypes of its MCE 2000 multiplexed capillary

electrophoresis instrument. CombiSep shipped its first

machine to Procter & Gamble Pharmaceuticals for

evaluation in late February 2001. Five instruments are

in various states of assembly. Moveover, the company

raised $1 million in start-up funds.

 CombiSep has been able to move quickly for several

reasons, according to Coldiron. First, Yeung had already

proved that the technology would work. Second,

CombiSep has been able to hire top-notch technologists.

In capillary electrophoresis, an electric charge causes

molecules to migrate down capillary tubes at different

speeds according to size and charge. A combination of

ultraviolet light and photodiodes are used to detect the

molecules. The data is then processed and displayed in

graphs called electropherograms.

2001 7 INquiry

Ed Yeung received a 2001 R&D 100 Award

for development of multiplexed capillary

electrophoresis technology, making him a

four-time R&D 100 winner. The R&D

Magazine program, now in its 39th year,

honors the top 100 products of technological

significance marketed or licensed during the

previous calendar year.

Since 1984, Ames

Laboratory has earned

14 of the prestigious

awards.

These include the technology’s co-inventor, Ho-Ming

Pang, as well as founder Strasburg and Jeremy Kenseth,

both Ph.D. chemistry graduates from ISU. Third, the

company has contracted resources and expertise from

Ames Lab and ISU to accelerate its development rather

than hiring its own staff. ISU’s Center for Advanced

Technology Development and Center for Industrial

Research and Service have both assisted the company.

CombiSep also contracted with Ames Lab’s Engineering Services Group to fabricate various components and

to design and build the electronics that go into the

machine. Jerry Hand, supervisor of the Lab’s mechanical

development shop, says the CombiSep project is “pretty

much” like the others his group tackles. Much of the

effort consists of fabricating components made of

aluminum and other materials using the shop’s lathes,

mills and wire electrical discharge machining system.

Hand says his entire group has worked on the CombiSep

project. In addition, the electronics tech shop of the Lab

helped design the electronics for the prototype. ◆

For more information:

Ed Yeung, (515) 294-8062

yeung@ameslab.gov

Research funded by:

DOE Office of Basic Energy Sciences
material are pretty outstanding,

especially considering that the

material is a combination of common metals,” Sheares says. “They

exhibit properties not found in the

constituent metals, but when you

put them together in the right

combination, under the right

conditions, you get this outstanding

set of properties.”

Enticing possibilities

 As Thiel described some of the

unique properties of quasicrystals,

Sheares started thinking about the

possible benefits of combining

quasicrystals with polymers. Polymers — large molecules that consist

of repeating chemical units joined

together — typically are filled with

all kinds of materials, such as

calcium, silica, alumina or carbon

black. “Almost no commercial

plastic is unfilled,” Sheares explains.

“There are all kinds of things mixed

into a polymer. The polymer really

becomes the matrix that is holding

the filler together. These other

things are dispersed throughout to

alter the properties.” As a result,

polymers are used in a wide array of

products, everything from grocery

sacks to automobile tires.

 In addition, polymer processing is

well understood, according to

Sheares. They are processed into

films, fibers and shapes used in

thousands of products. Even in the

planning stages, the benefits of a

material with the unique quasicrystal

properties that could be processed as

easily as polymers had enticing

possibilities.

An improbable mixture

 The fundamental question of

whether polymers and quasicrystals

would mix, however, was not

guaranteed. “We tried things that

shouldn’t have worked, but we tried

them because we were just thinking

from a polymer standpoint,” Sheares

explains.

In particular, polymers don’t like

to mix with each other, let alone

with other materials. Coupling

agents generally are used to increase

the adhesion or interaction between

by Mary Jo Glanville

Valerie Sheares examines the color and viscosity of a newly made polymer.

2001 8 INquiry

Sometimes trying something that

really shouldn’t work can lead to an

amazing discovery. That’s what

happened to Valerie Sheares, an

Ames Laboratory associate and Iowa

State University assistant professor

of chemistry. The discovery, a

polymer-quasicrystal composite, has

the best characteristics of each of the

constituent parts. It’s opened the

door for a variety of innovative uses.

Why it works, however, remains a

puzzle — one that Sheares is eager

to solve.

 It was her expertise with polymers combined with an introduction

to quasicrystals that kindled Sheares’

curiosity. Shortly after arriving at

Iowa State in 1996, she heard Pat

Thiel, Ames Lab Materials Chemistry Program director, discuss

quasicrystals and their unique

properties.

Discovered in the 1980s,

quasicrystals typically are aluminum-rich alloys of specific compositions. They are extraordinarily hard,

have low coefficients of friction

under certain test conditions, and

don’t conduct heat as well as most

metals. “All things that in one

?

Polymers

Plus

Quasicrystals

Equals

A

Puzzling

Interaction
the polymer and the filler by

attaching to both surfaces, but the

nature of the quasicrystal surface

prevents the coupling agent from

being able to attach.

“Quasicrystals have a low-surface

energy — they don’t like contact

with other things. It’s like Teflon,

that’s a low-surface energy material,

so things do not stick. That gave us

the idea that these things aren’t

going to want to mix with themselves, much less with polymers,”

she notes.

Considering these barriers,

Sheares’ experiments showed

surprising results. “We dissolved

the polymer in a solvent and added

it to a quasicrystal powder. We

wanted to see it disperse in the

liquid,” she says. Even though the

heavier, metallic powder sank, it was

evenly dispersed on the bottom with

no clumping together. That was the

first indication that the two materials

would blend rather than run away

from each other.

The next step was to mix a

polymer powder with a quasicrystal

powder and to process the mixture

using compression molding, one of

the most common techniques for

fabricating materials. The mixture

was poured into a mold, and heat and

pressure were applied, causing the

polymer to become molten or soft.

The research team of Sheares, Paul

Bloom, an ISU graduate student, and

K.G. Baikerikar, an Ames Lab scientist, worked diligently, adjusting the

timing and temperature to maximize

how evenly the particles dispersed

before the material was cooled down.

Using electron microscopy, the

researchers examined the new

composite, slicing into it to confirm

that the quasicrystals were evenly

dispersed throughout. This characteristic is key because the closer the

interaction between the polymer and

the filler, the stronger the material.

Tests confirmed that the composite’s

mechanical properties were increased,

yet the thermal properties remained

unchanged, verifying that in these

tests, the quasicrystals behaved just

like other hard fillers used in polymers.

Amazing combination

 Next, the researchers examined

the wear properties of the composite.

Essentially, the tests involve a steel

ball held in contact with the composite while the composite rotates on a

turntable. Then the composite and

steel ball are examined for wear. The

results were impressive — quasicrystals, as a filler, significantly

improved the wear-resistance of the

polymers.

Even more amazing, the composite exhibited a nonabrasive characteristic — neither the composite nor the

steel ball showed significant signs of

wear. “Almost everything that is hard

is also abrasive. If the material itself

doesn’t wear, it’s probably wearing

very hard on the other surface.

Quasicrystals in polymers are not like

that. They are not scratched, and

they don’t scratch other surfaces,”

Sheares explains.

While the first polymers tested

were high-performance, subsequent

tests with commodity polymers also

have been positive. “We have gone

through every type of polymer you

can imagine. It doesn’t really matter

what the matrix is. It performs

similarly,” Sheares adds.

With the success in the laboratory,

Sheares applied for a composition of

matter patent. “We are the first

people on record to make a polymer

quasicrystal composite, so we want to

own that composition,” she says.

Approval on the patent application is

pending.

Thiel, who also is chair of the

Iowa State chemistry department,

2001 9 INquiry

In jars, from left: a polymer solution, isolated polymer and pure

quasicrystal filler are the ingredients for a new composite that is

highly resistant to wear, nonabrasive and easy to process.
calls Sheares’ accomplishments very

exciting. “Valerie is very enthusiastic

and has clear expectations of what

she wants to do. She wasn’t afraid to

try something that nobody expected

to work. As a result, she’s opened up

a whole new area of study both in

terms of the practical ramifications

and the fundamental questions

related to the nature of the interaction between polymers and

quasicrystals,” Thiel says.

New hope for

hip replacements

 One application Sheares and her

Ames Lab colleagues currently are

working on grew out of conversations between Bloom and another

graduate student, Brian Anderson.

Surya Mallapragada, Anderson’s

major professor, is a member of the

Materials Chemistry Program and an

ISU associate professor of chemical

engineering.

 One of Mallapragada’s research

areas involves the use of ultra-highmolecular-weight polyethylene in

replacement hip joints. “The big

problem with polyethylene is that

there is a lot of wear. The polyethylene is in the form of a cup. A metal

ball rotates in the polyethylene

socket, and there is constant friction

causing wear on both materials,”

Mallapragada explains. Not only

does this impact the mechanical

integrity of the replacement joint,

but as the ball and socket wear,

particles from these materials lead to

bone loss, causing the joint to

loosen, she says.

 With its nonabrasive, wearresistant characteristics, Sheares’

composite appears to offer a solution. Her research group filled the

ultra-high-molecular-weight polyethylene with quasicrystals and did

the wear test. “They performed just

beautifully, just like they had done in

every other polymer,” Sheares says.

 The next hurdle was determin2001 10 INquiry

ing how the composite behaved with

living cells. The initial test to

establish its biological compatibility

was positive, i.e., it’s not causing cell

death. Sheares emphasizes that this

was a quick, short-term test, but it

means they can move on to much

more extensive biological testing.

“It’s pretty exciting. It is an application that you can see immediately

how it could be utilized,” she says.

Searching for clues

 The investigation into polymerquasicrystal composites is far from

over. Even as Sheares gets more

feedback from industry with ideas

for applications, she is searching for

clues that will help her answer some

very fundamental questions about

polymer-quasicrystal interactions at

surfaces. What is that interaction?

Why do the quasicrystals disperse?

 In some respects, the success in

the laboratory has hindered finding

the answers. “If it only worked with

certain types of polymers, then we

could look at why one works, but

another doesn’t. It works with every

polymer. It’s great, but it doesn’t help

us explain why,” she says.

 Unraveling this mystery is a top

priority. After all, if you know how

and why something works, you can

make it work even better. ◆

For more information:

Valerie Sheares, (515) 294-2474

vsheares@iastate.edu

Research funded by:

DOE Office of

Basic Energy Sciences

Sheares removes a sample from a polymerization mixture to isolate it for

characterization.
by Saren Johnston

New biosensor

technology may ease

cancer risk-assessment

2001 11 INquiry

tached to the DNA. If the body’s natural defense systems

do not properly repair the damage caused by these adducts,

the result can be the birth of a renegade cell. Uncontrolled

proliferation of such a cell results in cancer.

 A reliable way scientists can assess cancer risk is to keep

track of DNA adducts formed in human cells. Small and

Jankowiak are developing a novel means for detection of

certain DNA adducts that can be found in urine. The

newly developed biosensor chip technique is simpler and

potentially more practical than previous methods.

 “This scientific advance holds the promise of making it

easier and less expensive to identify cancer-causing

chemicals in the body, giving physicians a warning sign

before the cancer grows and

spreads,” says Secretary of

Energy Spencer Abraham.

 Jankowiak leads the

biosensor chip research

project, which also includes

Marc Porter, an ISU chemistry professor and director of

ISU’s Microanalytical Research Center. Jeremy

Kenseth, who recently

received his Ph.D. under

Porter’s supervision, and

Scott Duhachek, a former

postdoctoral fellow who

worked with Small and

Jankowiak, also made

significant contributions to

the project.

 The biosensor technology

is based on a unique gold

chip that was constructed by

Kenseth. The chip can be

used to detect fluorescent

DNA adducts — adducts that emit light when excited by a

laser. Bound to the chip’s surface are special antibodies,

proteins that serve as the body’s natural defense system

against infectious agents. Scientists can develop antibodies

in the laboratory to be so selective that they will preferentially bind a specific DNA adduct.

Ryszard Jankowiak (left) and Gerald Small study a

design for the second-generation biosensor chip.

The sooner you find it, the better. But the indications

that an individual may have an increased risk of getting

cancer are often difficult to spot. Tucked away, these

clues lurk in the twists and turns of the body’s DNA.

 Uncovering the clues has traditionally been a complex and time-consuming practice, but now Ames

Laboratory researchers

have come up with a

highly sensitive and

selective method to

speed that process.

 Gerald Small, an

Ames Lab senior

chemist and an Iowa

State University

distinguished professor,

and Ryszard Jankowiak,

an Ames Lab senior

scientist, have developed a unique

biosensor technology

that provides immediate

information about DNA

damage from cancercausing pollutants

called carcinogens.

Damage to DNA, which

carries the genetic code

of life, is a critical first

step in the development

of cancer.

Tracking adducts

 When carcinogens enter the body and are activated,

they can react with the DNA to form DNA adducts,

chemical compounds in which the carcinogen is at-
The chip in action

 The biosensor chip includes a single-layer linker

molecule that adsorbs to the bare gold. The chip with

the linker molecule can be exposed to a drop of solution

containing an antibody specific to the DNA adduct of

interest. The linker serves as a coupling agent, binding

the antibody to the chip. This process creates an active

surface area that can, in turn, bind molecules of those

adducts specific to the antibody when the chip is exposed

to a liquid sample. With the new biosensor chip technology, scientists could test for the presence of a certain

adduct in a sample of urine by simply dipping a chip

containing the corresponding antibody into processed

urine. The adducts of interest would bind to the antibody and fluoresce when scanned with a laser beam at

low temperature — minus 4 Kelvin (minus 452

degrees Fahrenheit). The data gathered from the laser

scanning would then be used to produce a detailed

fingerprint for adduct identification, providing vital

information for cancer risk-assessment.

 “The biosensor chip technology has the potential to

play a significant role in the advancement of cancer

research,” says Ames Laboratory Director Tom Barton.

“It demonstrates, once again, the diversity of Ames

Laboratory’s scientific efforts and the commitment of our

scientists to perform cutting-edge research that may

improve the lives of people throughout the world.”

The glycerol effect

 Jankowiak explains that initially they were unable to

detect fluorescence at room temperature. However, he

notes that the addition of a thin layer of glycerol to the

surface of the chip led to a dramatic increase in fluorescence intensity at room temperature. “Cooling the chip

further increased the intensity by a factor of 10,” he says.

 Although Jankowiak is still investigating the glycerolinduced fluorescence enhancement, some insight already

has been achieved. For example, he says, “We know that

the distance from DNA adduct to the gold surface has

increased by a factor of two, since the antibody adopts a

more upright orientation on the surface in the presence

of glycerol. This accounts for the significant increase in

the observed fluorescence intensity due to the decrease in

surface quenching by the underlying gold.” However, he

notes that a great deal more research is needed to determine whether it would be possible to take advantage of

the glycerol effect in the manufacture of biosensor chips.

2001 12 INquiry

For more information:

Ryszard Jankowiak, (515) 294-4394

jankowiak@ameslab.gov

Research funded by:

DOE Office of

 Biological and Environmental Research

National Cancer Institute

 The biosensor research team is investigating other

enhancements to the chip technology, including making

chips with upright orientation of the antibody and

increased distance between the bound DNA adduct and

the supporting surface. The team is also looking at

developing chips with several addresses for different

antibodies that bind different adducts, and using surfaces

other than gold.

 “The more adducts that can be identified, the more

complete the picture of DNA damage resulting from

exposure to mixtures of carcinogens,” says Small.

 Jankowiak adds, “We are currently looking at adducts

implicated in breast and prostate cancer. One day this

technology could lead to significant advances in precancer diagnosis.” ◆

A gold-coated silicon wafer is the starting material

for constructing Ames Lab’s new biosensor chip

that can track DNA adducts. Treating the chip

with specific chemicals allows it to bind DNA

adducts to its surface. Coating the chip with a

thin layer of glycerol greatly enhances the emission spectra produced when the chip is exposed

to a laser beam at low temperature.
2001 13 INquiry

Iver Anderson thinks the solution to

the rolling power blackouts in

California and parts of the East Coast

may lie under the rolling black soil of

Iowa’s farm country. “Iowa is sitting

on top of huge deposits of coal,” says

Anderson, an Ames Laboratory senior

metallurgist. “The problem is that it’s

high-sulfur, dirty coal.”

 That’s why trainloads of cleanerburning coal from western states

pass by every day on the Union

Pacific’s east-west line, just a couple

blocks away from Anderson’s lab in

the Metals Development building.

As those trains rumble past, Anderson and colleagues Bob Terspstra

and Brian Gleeson are closing in on

a new material to filter the nasty

ashes and dust that result from

burning “dirty” coal.

 “The technology to burn dirty coal

cleanly has existed for some time,”

Anderson says. “Demonstration

plants have proven that pressurizedfluidized bed combustion and

integrated gasification combined

cycles are highly efficient, lowemission power-plant concepts. The

high pressure and high temperature

volatilize, or burn off, most of the

pollutants, even those in the exhaust

gases.”

 But there’s a catch, quite literally,

with these systems. The flue gases

contain fine particles of fly ash.

High in sulfides, chlorides and

sodium compounds, these particles

pose an abrasive and corrosive threat

to the turbines that drive a power

plant’s generators, as well as to air

quality. To prevent these particles

from reaching the turbine blades

(and the atmosphere), the hot gas is

passed through clusters, or banks, of

cylindrical “candle” filters. Open on

the bottom end, these three-inchdiameter filter tubes are about four

feet long and currently made out of

a ceramic material that can trap

particles as small as one micron.

 “The ceramic filters do a good

job of standing up to the heat and

Metallic filter holds key to clean-burning, coal-fired power generation

by Kerry Gibson

Senior metallurgist Iver Anderson holds a high-pressure gas

atomization nozzle used to produce powdered nickel-chromiumaluminum-iron alloy (contained in the jar). The powder is spread

in shallow molds and sintered in a vacuum furnace to form porous

metal filter material (foreground) that can be shaped.

Clean Power

Coal,
2001 14 INquiry

the nasty oxidizing-sulfidizing

environment created by the gases,”

Anderson says, “but they’re very

delicate. Ceramics can crack easily

and if even a single candle filter

breaks, the filtration ability of the

whole bank is lost. So these plants

must have several banks of filters.

Switching to a fresh filter bank is

much better than shutting down the

whole power plant to change one

filter tube.”

 As more and more particles

collect inside the tube-shaped filters,

the amount of air passing through

decreases. To keep each tube

operating efficiently, the fly ash is

periodically knocked off by an

internal blast of compressed air, a

process called backflushing. Since

the flue gases are about 850 degrees

Celsius (1,562 degrees Fahrenheit),

the abrupt change in temperature

caused by the compressed air can

also crack the ceramic material. For

new combustion technologies to

move from demonstration plants to

widespread use in the power

industry, a new, tougher filter is

needed.

 “It’s the last big hurdle to seeing

this technology take off,” Anderson

explains. “Power companies are in

the business of generating power and

making money, not constantly

changing filters. You want a filter

assembly that is rugged enough and

has a long enough life that you can

essentially forget about it.”

 To find those properties,

Anderson’s research team looked at

developing rugged metal filters from

nickel-, cobalt- and iron-based

“superalloys” developed for the

aerospace industry. These highstrength metals can withstand high

temperatures and aren’t affected by

thermal shock during backflushing.

The researchers selected a nickelbased alloy that maintains its

strength at high temperatures, but

more importantly, develops a

protective scale when it oxidizes.

 “The nickel-chromium-aluminum-iron alloy we chose contains a

sufficient amount of aluminum to

form a protective film of aluminum

oxide,” Anderson says. “Once an

aluminum oxide layer forms, it

prevents further oxidation. It’s why

structural aluminum can be left

unpainted without rusting away.”

 While ceramic filters need to be

thick for strength, a superalloy metal

filter may be quite thin, giving it an

airflow efficiency advantage. To

create these thin, permeable sheets

of metal, Anderson uses a process

called tap-densified loose powder

sintering.

 He starts by converting highpurity molten superalloy into a fine

powder using a high-pressure gas

atomization system. As the hot

metal passes through a nozzle, a

high-pressure jet of nitrogen gas

breaks up the stream of liquid

superalloy into millions of tiny metal

spheres. The resulting powder is

then sorted, by screening, into

spheres only 25-45 microns in

diameter.

 After spreading the sorted metal

powder out as a thin layer

(0.5 millimeters) in a shallow

“cookie sheet,” Anderson heats the

metal in a vacuum furnace. This

sintering process bonds the powder

particles together, forming strong,

smooth joints between the spheres,

but leaving air gaps as well.

 “In tests we conducted, our alloy

experienced only a moderate drop in

yield strength going from room

temperature to operating temperature (850 C),” Anderson says. “And

Powdered nickel-chromium-aluminum-iron alloy is placed in a

test mold and struck off in preparation for sintering, a process that

bonds the spherical powder particles together.

As this micrograph shows, the

sintering process fuses the

spherical metal powder particles together, forming strong

bonds, or necks, while leaving

small gaps that allow air to pass

through.
2001 15 INquiry

For more information:

Iver Anderson, (515) 294-9791

andersoni@ameslab.gov

Research funded by:

DOE Office of

 the Deputy Assistant Secretary

 for Coal and Power Systems

our porous sample turned out to be

about six times stronger at operating

temperature than a porous sample of

an iron-aluminide material being

developed by another research

laboratory. That strength allows us

to go with a very thin filter body.”

 Given those encouraging results,

the researchers tried a series of bend

radius tests to see how well the metal

could be formed. According to

Anderson, the material was ductile

enough to enable it to be formed into

corrugated tubes, an important

feature not only for strength, but for

dramatically increasing the amount

of filter surface area.

 While the group will tinker with

the alloy mixture and conduct

additional corrosion testing, the next

big step will be to perfect a technique

for welding or crimping the longitudinal seam to close off the tube and

for adding a mounting flange and cap

on the open ends.

 As that work progresses, Anderson hopes to try out the sintering

process on high-capacity commercial

equipment with the help of Mott

Metallurgical, a Connecticut-based

metal filter manufacturer.

 “The key to getting the best

bonded neck structures — the fused

joints between the powder particles

that give the material its ductile

strength — is keeping the powder

material clean,” Anderson says.

“You have to use pure material and

keep it that way during atomizing

and sintering to permit proper

bonding of the spheres.”

 He also hopes to test the filters at

a DOE demonstration power plant

run by the University of North

Dakota. The prospects of what

could happen if that testing is

successful brings an excited grin to

Anderson’s face.

 “I think the filter could have a

great impact on the electric power

industry worldwide,” he says. “I’m a

conservationist at heart, but of the

resources available, we have a much

greater reserve of coal than anything

else. It’s even right here in Iowa.

 “Making it possible to burn dirty

coal cleanly would provide us the

stopgap that we need until we can

develop the ultraclean hydrogen

conversion (fuel-cell based) power

plants or use completely renewable

resources, such as wind or solar.”

Such filters could have an impact on

diesel combustion engines as well.

 “The technology exists to

produce highly efficient diesel

engines — two to three times more

efficient than gasoline engines,”

Anderson says, “and you’ll probably

see diesel hybrid cars very soon.

The problem is that the emissions

are either high in particulates and

low in nitrous oxides or low in

particulates and high in nitrous

oxides — but not low in both.

 “Ideally, you’d use a particulate

filter in combination with the lownitrous-oxide-producing engine,” he

adds. “Exhaust emissions from

burning common diesel fuels are

high in sulfur. We’ve already

addressed that problem, so our filter

could possibly work in this application as well. And because diesel

fuels can be formulated in so many

blends, including soy oil, we’d have

all sorts of options.” ◆

The metal filter material would be formed into candle

filters to remove corrosive and abrasive fly ash from the

exhaust gases of next-generation, coal-fired power

plants.
“Fast-talking” Clusters

 Researchers at Ames Laboratory’s Scalable Computing

Lab have extended their investigation into communication technology for cluster

computers thanks to a

National Science Foundation Major Research

Instrument grant awarded

to Iowa State University’s

Center for Physical and

Computational Mathematics. The $300,000 MRI

grant includes $190,000

from NSF and more than

$100,000 in matching

funds from ISU’s Institute

for Physical Research and

Technology, Iowa State

University and the ISU

departments of physics and

chemistry.

 Scalable Computing Lab

researchers are using the MRI funds to improve interconnect solutions for cluster computers, personal computer

or workstation networks that can operate at speeds

comparable to today’s commercial parallel computers, but

for a fraction of the cost. Making message-passing

between computers in a cluster faster and more efficient

is the primary goal of the MRI-supported research effort.

 The SCL scientists believe cluster computers could be

very appealing to the larger scientific and academic

communities. “A university department or a research

group can’t afford to buy a supercomputer, but they can

afford to put a good cluster together,” says Mark

Gordon, director of Ames Lab’s Applied Mathematics and

Computational Sciences Program and head of the SCL.

 Gordon emphasizes that solutions to grand-challenge

problems, such as the design of new materials and

catalysts, the development of viable methods for environmental remediation, and the search for the origin of life

will depend on state-of-the-art computational hardware

and applications software to take advantage of modern

computers. “The high-performance computing environment of the future will undoubtedly include scalable

cluster computing,” he says. (Scalable means the ability

to increase, or “scale up,” computer processing power to

run the same job in less time.)

INtouch

2001 16 INquiry

 “In the case of clusters, we want to figure out how to

best manage the hardware and get computers talking to

each other with a minimum amount of time used in

communicating and a maximum amount of time in

actually doing the calculations,” Gordon adds. “That’s

what the MRI grant is all about.” ◆

To increase cluster computer efficiency, Ames Laboratory researchers

are looking at ways of optimizing

communication throughput with the

Gigabit Ethernet switch as well as with

alternative switch technologies.

Building on Success

 When researchers at Ames Laboratory developed a

compact laboratory furnace, it marked a huge leap

forward in the ability to understand what happens to a

material’s crystal structure as the material is heated and

cooled. That success has led to the building of two

additional furnaces for other DOE laboratories and a

refined design intended to make the furnace easier to

operate.

 Used in conjunction with a powerful X-ray beam, such

as that produced by the synchrotron at Argonne National

Laboratory’s Advanced Photon Source, the furnace allows

researchers to capture in a few seconds the patterns

created as the crystal structure of the material diffracts the

beam. By studying changes in the diffraction patterns as

the material is heated and cooled in the furnace, scientists

quickly gain an understanding of what happens when a

material transitions from one type of solid to another or

from solid to liquid and back again.

 The original furnace is being used at the sector of the

APS facility operated by the Midwest Universities Collaborative Access Team. According to scientist Matt

Kramer, one of the developers of the furnace, two copies

of that furnace are being built by Ames Lab’s Engineering

Services Group.

 “One is being built for Systems Research and Instrumentation, which is the developmental CAT for Argonne

National Laboratory,” says Kramer. “The other one is for

the High Temperature Materials Research Laboratory at

Oak Ridge National Laboratory.”

 The furnace’s fame isn’t limited to this country.

Kramer’s group designed and built an even smaller unit

for the European Synchrotron Radiation Facility, located
2001 17 INquiry

BAM Continues Amazing Development

 A material that rivals industrial diamond in hardness

continues to amaze the researchers who developed it

and attract interest from a variety of industrial sectors.

The material represents a breakthrough technology that

could have a substantial impact on the machining

industry, which spends $300 billion each year in labor

and overhead in the United States alone.

 But hardness is only one of several unique properties

possessed by the boron-aluminum-magnesium alloy,

nicknamed “BAM.” Preliminary tests show it stands up

well in cutting both concrete and stainless steel, giving

it a definite advantage over diamond-coated cutting tools

in slicing up steel-reinforced concrete.

 “Diamond does a good job of cutting concrete and

masonry,” says researcher Bruce Cook, “but wears

quickly when cutting steel due to the chemical reaction

between the carbon in the diamond and the iron in the

workpiece. Our alloy seems to cut both concrete and

steel equally well without much wear.”

 Though Cook and fellow researchers Alan Russell and

Joel Harringa expected BAM to perform well as a cutting

tool, they were surprised to find that the material cuts

without getting hot. Even when the cutting edge is

spinning off red-hot ribbons of lathe-turned stainless

steel (somewhere around 700 degrees Celsius, or 1,292

degrees Fahrenheit), the tool stays cool enough to touch

with a bare fingertip.

 “There’s very little heat transport, and we think that’s

due to fine grain size and the complex crystal structure

within the material,” says Cook. Bruce Harmon, Ames

Lab deputy director and director of the Lab’s Condensed

Matter Physics Program, and graduate student Younben

Lee are also conducting further calculations on the

fundamental electronic structure. “We’re interested to

see if there’s a relationship between the electrical

transport and thermal transport that may help explain

how ultrahard materials perform,” Cook adds.

 Cook’s research team has also boosted the scale of

production of the material, in part to keep up with

requests for samples. Button-sized samples have been

replaced by much larger wafers, nearly 2 inches in

diameter and about three-quarters of an inch thick. But

given BAM’s low density (about 2.5 grams/cm3),the

wafers lack the expected heft of conventional tungsten

carbide used to slice through concrete and steel.

 Since discovery of the material was first announced

in October 1999, more than 100 companies and

research facilities have requested samples.

 While in-house testing continues, including recent

successful trials in machining titanium, Cook hopes to

learn as much or more from the various companies that

have received samples. For example, a manufacturer of tooling for industrial woodworking equipment

returned a sample that had been shaped using electric

spark erosion. And a producer of industrial gases and

surface coatings is investigating the material as an

extremely durable coating for various industrial applications.

 “They may not realize it, but these companies are

providing us with valuable information,” Cook says. “It

gives us a much broader perspective. At the same time,

most of the research and development is being conducted by scientific staff so they can supply test data to

support the various applications. It really helps our

understanding of the material.” ◆

(See more INtouch on inside back cover.)

in Grenoble, France. That collaborative effort was aided

by ESRF researcher Larry Margulies, a former Ames Lab

graduate student who worked with Kramer, senior

materials scientist Bill McCallum, and assistant metallurgist Kevin Dennis on the original furnace design.

 Even with the furnace’s success, Kramer’s group is

looking to improve upon it by making it quicker to set

up and easier to use.

 “With the present furnace, it takes a substantial

amount of time, up to 36 hours, to get things properly

lined up,” he says. “The new design we’re working on

will be more modular and make it easier to position the

sample in relationship to the beam, so we can spend

more time doing research instead of setting things up.

Also, if we need to swap out components, we don’t have

to go through the entire alignment process again.” ◆

A sharpened wafer of BAM, glued to a cutting

tool blank with household epoxy, shaves off

ribbons of stainless steel. Low heat transport

properties keep the cutting tool cool, even

though the stainless steel gets red-hot.
Showing a new, naturally occurring compound to a research chemist

is, in a way, like throwing down a

gauntlet. The unspoken challenge

being issued — create this in the lab.

 For Peter Rabideau, that gauntlet

has been the buckyball — a curious

hollow sphere formed by 60 atoms

of carbon. Rabideau, an Ames

Laboratory senior chemist, has

moved a step closer to meeting that

challenge by developing a practical

means of producing bowl-shaped

segments — buckybowls — that

could eventually be pieced together

to form the complete ball.

“Chemists are always interested in

being able to synthesize things

whether you need them or not,”

Rabideau says, pointing out the

synthesis of cholesterol as just one

example. “It’s a big thing just to

show you could do it, so there’s an

element of that to it.

“But there’s also the practical side

of being able to put things inside the

buckyball, such as precursors for

supertough coatings or drug-delivery

systems, that may have some real

novel properties if one could figure

out how to do that,” he says.

 Buckyballs have intrigued chemists since the uniquely structured

molecules were first discovered in

1985. The carbon atoms align to

form a hollow structure similar to

the pattern of panels found on a

soccer ball. They get their name

from architect/engineer/philosopher

Buckminster “Bucky” Fuller, who

pioneered the concept of the

geodesic dome.

 “It turns out that geodesic

stability on the molecular level is

also rather remarkable,” says

Rabideau, who also serves as dean

of Iowa State University’s College of

Liberal Arts and Sciences. “Carbon

atoms like to be arranged in this

particular formation and are

extremely stable.”

 Since the structure is very stable

and hollow, chemists have envisioned a whole new array of applications if they could find a way to put

other atoms or compounds inside

the buckyball.

 Unfortunately, the only way to

produce C60 is to replicate the

environment of interstellar space

2001 18 INquiry

with a process that basically involves

arcing carbon rods, but this reaction

takes place only at high temperatures.

The high temperatures make the

reaction hard to control, so it’s

extremely difficult to try to produce

buckyballs with something inside

them. So the search turned to finding

a way to “build” a buckyball from

scratch.

“If you took a buckyball apart, it

wouldn’t be a stable entity because it

would have dangling bonds,”

Rabideau explains. “But if you took it

apart and put hydrogen atoms on the

dangling bonds to stabilize the

structure, you’d have a chemical

compound that we call a buckybowl.”

 It’s the curved shape of these

compounds that Rabideau finds

intriguing. Most polynuclear aromatic hydrocarbons, such as graphite,

are flat. And it was these “flat” compounds that he spent the early part of

his career studying at the University

of Chicago, under the guidance of the

man who literally wrote the book on

the subject, Ron Harvey.

 As Rabideau’s research progressed,

so did his advancement through the

academic ranks. By 1990, he was a

dean at Louisiana State University

and had come to an impasse in his

research.

“We had answered a lot of the

questions that we originally asked, so

Building the

Buckyball

Ames Lab senior chemist Peter Rabideau holds a buckyball model.

A

Bowl

at a Time

by

Kerry Gibson
to study. By unlocking the properties

of these bowl-shaped compounds,

Rabideau hopes to eventually discover

a way to combine the bowls into a

sphere.

“If we could figure out a few critical

reactions, we might ultimately be able

to synthesize C60,” Rabideau says.

“That would, in principle, allow us to

build C60 with a hole in it so we could

trap something inside, such as an

atom or metal, and then close up the

ball.” ◆

2001 19 INquiry

it was a matter of where the research

was going,” Rabideau says. “I had

also become a dean, so I had to do a

reality check on whether or not I

wanted to continue to do the active

research.

“My feeling was that if I was going

to remain active in research, we

would have to revitalize our program

and find some new things to do,” he

says. “About that time I saw a

publication on corannulene (C20H10)

and some of these curved-surface

compounds, and decided that’s the

direction we would take.”

 Corannulene was first synthesized

in 1966 at the University of Michigan

by a long and difficult 17-step process

that produced quantities weighing

just a few milligrams. Then in the

early 1990s, another group of

researchers synthesized corannulene

using pyrolysis — heating a material

until it decomposes. It was this

breakthrough that grabbed Rabideau’s

attention.

“The problem with this (gas-phase)

technique is that you must do it in

vacuum, so by definition you’re still

working with very small amounts of

material,” Rabideau says.

 What Rabideau and fellow researcher Andrzej Sygula developed

was a solution-phase synthesis using

dilute sodium hydroxide in water and

acetone that produces

tetrabromocorranulene — a molecule

of 20 carbon atoms with four bromine atoms attached. This process is

detailed in the following article:

Sygula, Andrzej and Rabideau, Peter

W. 2000. A Practical Large Scale

Synthesis of the Corannulene System.

Journal of the American Chemical

Society 122 (26): 6323-6324.

The process allows production of 25-

gram samples, a thousandfold increase

over the pyrolysis method.

“The process is really pretty

simple,” Rabideau says. “In fact, the

final step could almost be done in

your garage using household chemicals.” Though it hasn’t been a particular goal of his research, Rabideau adds

that a feasible commercial synthesis

could easily be developed.

 The synthesis of tetrabromocorranulene

has also had a silver lining. While the

bromine atoms can easily be removed

to form corannulene, it’s advantageous

to leave them on and add to them.

“We now have a way of elaborating

that particular molecule in a lot of

different ways,” Radideau says,

pointing to diagrams of just eight of

the many variations. “It’s better than

if we’d discovered a way to go directly

to corannulene because we can use

the bromines to do other things,

though our focus is on the fundamental chemistry involved.”

 Though building a buckyball is still

in the distance, researchers now have

an unlimited supply of bowl material

Unlike more common polynuclear aromatic hydrocarbons, such as graphite, which are flat,

corannulene molecules and related compounds

are curved. This curved, or bowl shape, of 20

carbon atoms is aligned with five atoms in the

center. The remaining atoms form sixsided polygons, around this central

pentagon, giving the bowls their

geodesic pattern. Without hydrogen

atoms (shown here in blue), dangling

bonds on the carbon molecule would

be unstable.

The trick now for Rabideau is to figure

out a way to link or combine three

bowls together, sans the hydrogens,

to form a complete C60 buckyball, an

extremely stable molecule that has

yet to be synthesized.

Piecing the ball together could have

the added benefit of being able to

capture another atom or metal inside the

ball, which would open a whole new array

of applications.

For more information:

Peter Rabideau, (515) 294-3220

rabideau@iastate.edu

Research funded by:

DOE Office of Basic Energy Sciences
Regular lasers

 In a regular, or periodic,

laser the amplifying

substance is positioned

within the laser’s cavity. It

might be a solid, such as a

crystal or a semiconductor;

a gas or a mixture of gases,

such as helium-neon; or a

liquid dye.

 All in all, the production

of laser light might be

thought of as a continuous

round-trip journey. When

excited by an outside

energy source, perhaps a

flashlamp or another laser,

the electrons in the amplifying substance get “pumped”

to a higher energy state

where many will spontaneously emit incoherent light

waves. The excited electrons that haven’t spontaneously emitted photons of

light will begin to fall to a

lower energy level, the

metastable state, where they

“hang out” for awhile, just

waiting to release their

excess energy as light so they can return home to the

ground state. These are the electrons that will eventually

emit coherent laser light.

 The release of coherent light is called stimulated

emission. It takes place when electrons in the metastable state are stimulated to fall to the ground state by

photons coming in from other electrons that are falling

from their metastable states. When an electron falls

from this stimulation, it also produces a photon of light

in exactly the same direction and with exactly the same

energy and phase as the stimulating photon. Then, the

process repeats itself. The laser light produced is

reflected back and forth between mirrors positioned in

the laser’s cavity, a process that amplifies the light many

times. Energy gain becomes greater than energy loss,

and an intense laser beam is created.

Like musicians in a

marching band, waves of

laser light move “in step”

with one another. As a

result, the waves spread

only slightly, even over

great distances.

 Laser light differs from

the light produced by

other sources, such as

electric light bulbs or the

sun. The light from these

sources is a confusion of

many wavelengths,

traveling in all directions.

It is called incoherent

light. But a laser produces

an intense, narrow beam of

light that travels in only

one specific direction,

much like a marching band

moves in unison along a

parade route. This is

called coherent light.

 Producing laser light,

light waves of a single

frequency or just a few

frequencies that “march”

together along a straight

path, requires a gain

medium — a substance that will amplify light. The gain

medium must also have a precise and orderly atomic

structure that will allow it to store energy and then release

the energy at the right time and in the right direction.

 Although lasers are technological marvels of exactness

and order, physicists have speculated for years about the

possibility of achieving laser light with disordered systems.

 Costas Soukoulis, an Ames Laboratory senior physicist, has gone beyond speculation. He and former Iowa

State University graduate student Xunya Jiang, now

working at DiCon Fiberoptics, Inc., near Berkeley, Calif.,

have developed a theoretical model that simulates the

phenomenon of random lasing, in which photons that

follow random paths create a multiple-light-scattering

laser.

Random Acts of

2001 20 INquiry

by Saren Johnston

From disordered

systems comes

coherent light

Theoretical physicists Costas Soukoulis (left) and Xunya

Jiang look over a transparency displaying their design

of the mechanism of a laser system. The transparency

is one in a series of visuals the two researchers have

developed to accompany their popular, invited talks

on the theory of random lasing.
Random lasers — the BIG SURPRISE

 But what happens if instead of possessing an orderly

arrangement of atoms that produce synchronized,

focused wavelengths, the structure of the light-amplifying substance is one that scatters light quite efficiently in

all directions? Can such a substance produce laser light?

 Soukoulis’ and Jiang’s model says, yes it can. A new

kind of laser can be created using photons that follow

random paths. The disordered system does not impede

lasing — it accounts for it. The process goes something

like this: When light is shined into a substance that

scatters it well, the photons get bounced in random

directions. If this happens often enough, it’s likely that

the trajectory of the photons inside the gain medium will

be extremely long and that the photons will travel many

times through the same crystal grains, ricocheting from

side to side as they go. Under these conditions, light can

be amplified tremendously. The process is similar to the

way light from an ordinary laser travels back and forth

between the two mirrors in the cavity. If the electrons in

the disordered gain medium get pumped to a higher

energy level while traveling their long, random paths,

the result could be amplification to laser light. The gain

medium, whether a crystal powder or a material containing random scatterers, would, in effect, become a laser.

Explaining the experiments

 Soukoulis’ and Jiang’s theoretical work represents some

of the very first efforts to understand and describe the

mechanics of random lasing. They have interpreted the

investigations of experimentalists Hui Cao of Northwestern University, Ad Lagendijk of the University of

Amsterdam and Val Vardeny of the University of Utah,

breathing logic and reason into the laboratory observations

and giving credibility to the random-lasing phenomenon.

“The first thing we wanted to do was to see if we

could understand all the narrow, sharp lasing peaks the

experimentalists were seeing in the output spectrums of

disordered systems, such as the zinc oxide nanocrystals

Cao was studying,” says Soukoulis, who is also an Iowa

State University physics professor. “So we tried to

simulate the real experiment in the computer using a

complex numerical technique called finite difference

time domain. We did a one-dimensional version of a

three-dimensional experiment.”

 Jiang adds, “The advantage of the FDTD method is

that from our computer simulation we can see the

dynamic process of the random system and how the

electric field is building up inside. We are able to follow

the evolution of the electric field.”

Using their FDTD model, Soukoulis and Jiang

discovered that the number of lasing peaks

in a random system will increase as the

pumping rate increases. However, the

model also revealed that once the pumping

intensity reaches a maximum value, the

lasing peaks no longer increase in number,

but, instead, saturate to a constant value.

The above figure shows Soukoulis’ and

Jiang’s findings for random laser systems

based on their FDTD computer model. With

an increase in the pumping rate — a (no

lasing), b, c, d — there is an associated

increase in the intensity, or brilliance, of the

emission spectra; enhanced definition of

the lasing peaks; and an increase in the

number of lasing peaks to the point of

saturation to a constant value.

10

Number of Lasing Peaks

5

0

Pumping Rate

2

4

6

8

10

106 107 108 109 1010

L/d = 80

W = 1.4

2001 21 INquiry

(d)

(c)

40

30

20

10

0

(b)

(a)

10

15

20

5

0

460 480 500 520 540

460 480 500 520 540

Laser Wavelength (in nanometers)

Spectral Emission Intensity (arbitrary units)
 The ability to predict the lasing modes in a given

random system is critical when considering some of the

potential uses for random lasers. The novel devices hold

promising properties for brightening the pixels in flatpanel displays. By reducing the size of the phosphor

grains that emit light in these displays, it might be

possible for the electron emitter in each pixel to excite

the phosphor’s electrons and initiate lasing, which would

brighten the pixels.

 Another possible application for random lasers lies

within the medical arena. Used with chemical sensors,

these devices could provide a sophisticated, noninvasive

tool for diagnosing problems within the human body.

And paint-on random lasers may one day light the way

to more efficient and economical search-and-rescue

missions to identify downed ships and airplanes, and

even individual passengers. ◆

For more information:

Costas Soukoulis, (515) 294-2816

soukoulis@ameslab.gov

Research funded by:

DOE Office of Basic Energy Sciences

2001 22 INquiry

Teacher and student, Soukoulis (right) and Jiang,

study an image of the localized lasing peaks produced by scattered light from zinc oxide nanocrystals.

The image was supplied by experimentalist Hui Cao of

Northwestern University.

 The ability to track the

population of the electrons as they are pumped

to higher energy levels

and then fall to metastable

and ground energy states

has allowed Soukoulis and

Jiang to arrive at a number

of important results.

 Using their computer

simulation of random

lasing, the two theorists are able to determine the

threshold value of lasing for the amplifying substance.

Knowing the threshold value is critical because it is the

amount of energy needed to pump the electrons in the

amplifying substance to the intensity where lasing takes

place. “One very important thing we discovered is that

the threshold value of lasing decreases as disorder

increases,” says Soukoulis. “So, the more the concentration of scatterers, the lower the threshold of lasing.”

 Through their one-dimensional model, Soukoulis and

Jiang also found that the sharp peaks the experimentalists had observed in the output spectrums were coming

from specific lasing modes of the disordered systems.

“From our theory, we can really solve and understand

these beautiful peaks,” says Soukoulis. He explains that

for disordered systems the lasing has a greater probability of occurring in some particular regions of the system

than in others. As the electrons in the amplifying

random substance are pumped to a higher energy level,

the lightwaves retain their shape, but they become bigger

and bigger. Eventually they will start lasing.

 In addition, the model revealed that if the pumping

intensity is increased above a maximum value, the

number of lasing modes remains the same. They do not

increase anymore, rather; they saturate to a constant

value that is determined by the degree of randomness in

the system and its length.

Predictions and possibilities

 “With our one-dimensional model, we can predict

exactly where the lasing modes will be in a given

random system, which mode will lase best, and the

wavelength, which determines the color of the emission

light,” says Soukoulis.
2001 23 INquiry

Process recovers

valuable neodymium

from magnetic waste

Ever own an expensive wool suit that went out of style

or got a little too small? Even though you can’t wear it,

the price tag makes it too hard to part with. So, the suit

hangs at the back of the closet, gathering dust, on the chance that you’ll drop

some pounds or the fashion will come

back into vogue.

 In a way, that’s similar to the

situation faced by manufacturers of

high-energy neodymium-iron-boron

magnets. These rare-earth magnets

allow the production of smaller, more

powerful and more efficient electric

motors that are used to make everything from portable CD players to

automotive power windows more

compact, lighter in weight and easier

on batteries.

 Despite those good characteristics,

the magnet material is brittle and

processing it creates a larger than

normal amount of machining waste.

This leftover scrap can’t be reformed

into magnets or easily recycled. But

because it’s roughly 29 percent neodymium (by weight) that’s valued at $30

per kilogram — just slightly less per

ounce than the price of silver — it’s

worth too much to dispose of. So it’s

been stockpiled on the chance that it might someday

have a use.

Molten magnesium solution

 That day could be here thanks to Scott Chumbley

and Alan Russell. The two Ames Laboratory researchers

have refined a process that makes it commercially viable

to recover the neodymium from tons of stockpiled

magnetic scrap.

 “The neodymium-iron-boron material decomposes

peritectically — it changes composition — when heated

to its melting point,” says Chumbley, lead researcher on

the project. “So it can’t just be melted down and reused.

But it’s too valuable to throw away, so there are literally

warehouses full of 55-gallon drums of the stuff waiting

by Kerry Gibson

Researchers Scott Chumbley (right) and Alan Russell stand near the

vacuum furnace in which test samples of Nd-Fe-B magnet scraps are

immersed in molten magnesium. A cutaway view of a stainless steel

crucible (title graphic above) shows Nd-enriched magnesium surrounding the darker magnet particles.
2001 24 INquiry

to be recycled.”

 Until now, the best

separation method

available was to dissolve

the neodymium-ironboron scrap in acid,

then perform a series of

chemical extraction and

reduction steps. However, the complexity

and expense of such a

method was impractical

for large-scale, commercial recycling.

 Building on research

pioneered and patented

by Ames Laboratory

researchers Tim Ellis

and Rick Schmidt in the

mid-1990s, Chumbley

focused on using molten

magnesium to extract

the neodymium from the

magnet scrap. Neodymium is soluble in liquid magnesium. In fact, the magnesium-casting industry routinely

adds neodymium and other rare-earth elements to make

alloys that are corrosion-resistant and offer improved

weldability.

 The recovery process is relatively simple. After

receiving a solvent bath to remove machining residue,

crushed pieces of magnet scrap are immersed in liquid

magnesium that’s been heated to 800 degrees Celsius

(1,472 degrees Fahrenheit). The magnesium leaches the

neodymium from the scrap particles. The liquid magnesium-neodymium (Mg12Nd) solution can then be poured

off, leaving the iron-boron particles behind.

Two-phase zone

 What Chumbley and Russell discovered was that there

is actually a two-phase zone that forms as the magnet

material is submerged in the liquid magnesium. Initially,

most of the neodymium is still tied up in an iron compound (Nd12Fe17). Then the neodymium gradually

moves into the magnesium at the interface between the

iron compound and the liquid magnesium. Over time,

the composition of neodymium in the magnesium rises at

For more information:

Scott Chumbley, (515) 294-7903

chumbley@iastate.edu

Research funded by:

DOE Office of Basic Energy Sciences

a fairly constant rate

and is spread evenly

throughout the

liquid, while the

width of the transitional, two-phase

region increases.

 The resulting

alloy is roughly 30

percent neodymium,

making it perfect for

use as feed material

for the magnesiumcasting industry.

And it should

substantially lower

the cost. Currently, a

typical magnesium

alloy casting contains

only two percent

neodymium by

weight, yet the

neodymium accounts

for 40 percent of the raw materials cost.

 “It would give them a product that is exactly what

they’re already accustomed to using,” Chumbley says.

“They wouldn’t have to retool or change any of their

processes.”

Tweaking the process

 The researchers are looking at the effect that variables, such as the size of the magnet pieces, temperature

and duration have on the process. In addition to

recovering the neodymium, the leftover iron-boron

scrap could be recycled as well, particularly for lowgrade iron castings where composition isn’t critical.

 Russell has fielded a number of inquiries about the

process from metal producers and recyclers, but so far

“no one seems to be on the verge of licensing the

technology,” he says. One company, a magnesiumcasting firm, has requested samples of the magnet

material to take a closer look at the process. ◆

A micrograph of a Nd-Fe-B magnet particle (black

area) shows the two-phase zone, the lighter area

along the edge, in which the Nd is still tied up in an

iron compound (Nd12Fe17). The Nd then migrates from

this region and spreads evenly throughout the liquid

magnesium.
The last Saturday in January has become a tradition

at Ames Laboratory. It’s Science Bowl Saturday.

Volunteers know it; students know it; teachers know

it. And the event, although held during the coldest

month of the year, never fails to produce some hot

competition. In 2001, teams from 42 Iowa high

schools braved the unpredictable Iowa winter

weather to match wits in the annual Ames Laboratory/Iowa State University High School Science Bowl.

Ames High School won the regional competition and

advanced to the DOE National Science Bowl.

Ames Laboratory and Iowa State University’s Institute for Physical Research and Technology hosted the

second meeting of the Midwest Forensics Resource

Center in May. Just one year earlier representatives

from the two organizations had met with Iowa crime

lab officials to discuss the types of research, services

and training that would be most helpful to their

facilities and to suggest funding sources for the

proposed center.

 This year’s meeting reflected how much the effort

to establish the MFRC had grown. Attendees represented eight Midwestern state crime labs; three

universities; the Federal Bureau of Investigation; the

National Institute of Justice; the Department of

Energy; and the Bureau of Alcohol, Tobacco and

Firearms.

 The MFRC will be located at Ames Laboratory and

serve as a central point for regional training, education and research in forensic science. It will draw on

the expertise of faculty and staff members at Iowa

State University, the Institute for Physical Research

and Technology, Ames Laboratory and other professionals throughout the region.

 To carry out its mission of helping regional crime

labs develop more efficient and reliable methods of

analyzing crime-scene evidence, the MFRC will focus

on four major goals:

• Develop customized training for regional partners.

• Conduct short-term, case-related forensics

 research projects.

• Develop a forensics curriculum for ISU and

 associated universities.

• Conduct long-term research into new and

 improved forensics techniques.

From Ames Lab to Crime Lab

 Representatives from Ames Laboratory and

the Iowa Division of Criminal Investigation load

a fingerprint development “glove box” for

transportation from Ames Lab to the DCI’s crime

lab in Des Moines, Iowa. An example of the

MFRC’s effort to ease problems encountered in

the crime laboratory, the fingerprint-development glove box should improve and speed the

fingerprinting process.

 The device was designed and built by Ames

Laboratory and IPRT in cooperation with the DCI.

It provides a controlled temperature and humidity environment in which to develop latent

fingerprints and allows criminalists to view and

handle evidence during processing.

INtouch

Science Bowl

2001

Science Bowl

2001

Students collaborate on a bonus question.

Coming to the Aid of Midwest Crime Labs
Ames Laboratory is a U.S. Department of Energy laboratory seeking solutions to energy-related problems through the

exploration of chemical, engineering, materials and mathematical sciences, and physics. Established in the 1940s with

the successful development of the most efficient process to produce high-purity uranium metal for atomic energy, Ames

Lab now pursues much broader priorities than the materials research that has given the Lab international credibility.

Responding to issues of national concern, Lab scientists are actively involved in innovative research, science education

programs, the development of applied technologies and the quick transfer of such technologies to industry. Uniquely

integrated within a university environment, the Lab stimulates creative thought and encourages scientific discovery,

providing solutions to complex problems and educating tomorrow’s scientific talent.

Ames Laboratory

111 Technical and Administrative Services Facility

Ames, Iowa 50011-3020

(515) 294-9557

http://www.external.ameslab.gov

Inquiry

AMES LABORATORY

A U.S. Department of Energy

laboratory operated by

Iowa State University