October 23, 2002
For more information on these science news and feature
story tips, please contact the public information
officer at the end of each item at (703) 292-8070.
Editor: Roberta Hotinski
Contents of this News Tip:
If chemistry professor Sheryl Tucker had her way, the
Girl Scouts would offer a chemistry badge.
In the Heart of Missouri Girl Scout Council, several
hundred Junior Girl Scouts (10-12 years old) are selected
each year to participate in Tucker's "Magic of Chemistry"
program at the University of Missouri, Columbia. Tucker
makes science fun--with hands-on projects such as
"Chemistry of Color," which involves tie-dying, secret
writing and chromatography, and "Fun with Polymers,"
in which they experiment with glue, rubber and "slime."
In October 2002, to celebrate National Chemistry Week,
the girls will solve "The Case of the Unsigned Letter"
by analyzing ink and other substances on a letter.
Tucker gives the Girl Scouts patches for their uniforms,
T-shirts and scientific notebooks.
This educational program is supported by Tucker's CAREER
grant from the National Science Foundation (NSF) and
by the American Chemistry Society (ACS), non-profit
and community groups and lots of volunteers. In 2002,
the ACS recognized one of Tucker's programs as the
best local event promoting women in chemistry. The
two programs she runs each year are timed to coincide
with National Chemistry Week, sponsored by the ACS,
and National Girl Scout Week.
"This program is designed to ignite and retain girls'
interest in science at an age when national studies
indicate they begin to lose this curiosity," said
Tucker. "I'd like to help remove the obstacles that
might prevent young women from going into the physical
sciences, particularly chemistry." Tucker attributes
her interest in providing opportunities for children
to explore science and chemistry to the educational
emphasis of NSF's CAREER program. The CAREER awards
support promising young scientists pursuing innovative
research and education projects early in their careers.
The program volunteers include female undergraduates
and professors that serve as role models, Tucker added.
For more information about "Magic of Chemistry" see:
For more information about National Chemistry Week
Top of Page
In Steven Regen's organic chemistry class at Lehigh
University, Penn., students not only carry out research,
they get their results published. For the fourth time,
all of his undergraduate lab students have been included
as co-authors of an article about original polymer
chemistry research published in a major scientific
journal. The National Science Foundation (NSF) supports
Regen's chemistry research involving undergraduates.
The recent class's research experiment on "hydrophobic
sponges" was published in the American Chemical Society's
journal Macromolecules. The class created
soap-like polymers that absorb organic molecules from
water. The soap molecules were attached to insoluble
polymer beads and thus could be removed from the water,
bringing the absorbed organic molecules along. The
technique is potentially useful for removing organic
contaminants from groundwater and drinking water.
All 70 students are cited in the paper.
"Professor Regen has created an innovative and rewarding
learning environment," said NSF program manager Tyrone
Mitchell. "What the students learn about the requirements
of research that leads to publication can be quite
different from their experience in a conventional
classroom. At the same time, these undergraduates
contribute to cutting-edge research."
"I do this to show large numbers of students how research
really works, including the publication process,"
Regen said. "It takes the laboratory class from the
ordinary to the extraordinary and shows them how class
from the ordinary to the extraordinary and shows them
how exciting science can be." [Amber Jones]
Top of Page
It makes up most of the air around us and has been
studied since the 18th century, so who
would have thought there'd be something new to learn
about nitrogen? Fortunately, Karl Christe of the Air
Force Research Laboratory at Edwards Air Force Base
in California did, and now he's added to a string
of NSF-funded discoveries at the Loker Hydrocarbon
Research Institute of the University of Southern California
by creating five-sided particles of nitrogen atoms
that have potential as powerful rocket propellants.
Pure nitrogen occurs naturally only as molecules of
two nitrogen atoms bound together in a form called
"dinitrogen." But groups of more than two nitrogen
atoms do exist bound up with other elements. If those
molecules are broken out of compounds, they explosively
revert to normal nitrogen. For example, sodium azide
contains a group of three nitrogen atoms and is used
as a solid propellant for automobile airbags. An impact
triggers an explosive release of dinitrogen gas that
expands the airbag in a few hundredths of a second.
Christe, working with colleagues at the University
of Southern California and the Air Force Research
Laboratory, has been creating molecular fragments
made of five nitrogen atoms in hope of combining them
to create a whole new form of nitrogen. When pulled
apart, all 10 atoms of this "polynitrogen" would convert
back to dinitrogen, releasing a lot of energy and
nitrogen gas that could be harnessed for propulsion.
Because they're violently explosive on their own, the
molecular fragments need to be stabilized with chemical
"wrappers." Earlier, the team successfully created
positively charged five-nitrogen atom fragments and
safely stowed them in a salt. Now they've detected
a negatively charged counterpart that's a perfect
pentagon of nitrogen atoms and are looking for another
suitable wrapper. Once they have enough of the positively
and negatively charged pieces, they hope to combine
them into polynitrogen.
Christe predicts that, if they can produce it, the
explosive power of the polynitrogen salt would be
twice that of conventional explosives. Plus it would
be very clean, having only nitrogen gas as a byproduct.
Conventional solid rocket boosters leave acid contrails,
but a polynitrogen propelled rocket's exhaust would
be practically indistinguishable from the air around
us. Because it's expensive and hard to make, though,
he says that it will only be used for specialty space
and military applications. [Roberta Hotinski]
Top of Page
Illustration of the dissolution of hydrogen
bromide – four water molecules are enough
to start the dissolution of the acid molecule.
Select image for larger version
versions (Total Size: 41KB) of all
images from this story
How many water molecules does it take to dissolve an
acid? Although this may sound like a joke from a Mensa
meeting, it's a fundamental problem for chemists.
Now with the help of a powerful laser, NSF-sponsored
researcher A. Welford Castleman, Jr. of Penn State
University and colleagues have found the answer: Five.
Knowing how substances dissolve is a basic chemistry
problem that's key to processes ranging from chemical
reactions in the body to depletion of the ozone layer.
Scientists have puzzled over the process for over
one hundred years and theorists had recently predicted
that about four molecules of water were necessary
to break an acid molecule into two charged pieces.
Until now, though, there was no experimental evidence
to compare with theory.
Postdoctoral scholar Sean Hurley, along with graduate
students Troy Dermota and Darren Hydutsky, shone light
on the subject by using a "femto-second" laser to
monitor the dissolving acid. The laser puts out pulses
one quadrillionth of a second long, letting the researchers
observe lightning-fast interactions between molecules
of the strong acid, hydrogen bromide, and water molecules.
Their results indicate that four molecules of water
are needed to start the breakup, and that five molecules
are enough to complete the process.
"We've been dissolving acids since ancient times, so
you'd think we'd know how this works already," said
Castleman. But until arrival of the femto-second laser
device, there was no way to monitor reactions in great
enough detail to know for sure. Ahmed Zewail, who
won a Nobel Prize for pioneering the field of "femtochemistry,"
calls the Penn State team's work " a welcome contribution"
and "an elegant study of a century-old problem."
The research is particularly important for studies
of ozone loss in the Arctic. Although the infamous
"ozone hole" occurs in the Antarctic, ozone depletion
also occurs at the North Pole near the Earth's surface
due to the influence of bromine. Ozone levels in the
Arctic "can drop to almost nothing in one day," says
James T. Hynes of the University of Colorado at Boulder
and the Ecole Normale Superieure, Paris. The acid
reaction the Penn State team studied, he says, is
thought to play a critical role in this loss. [Roberta
For more information on the Penn State team's research
Top of Page