Lab’s aerogel sets world record
An aerogel developed by researchers in Livermore’s Chemistry
and Materials Science (CMS) Directorate has taken the record for
the world’s least dense solid. The Laboratory’s aerogel,
which is listed in Guinness World Records 2004, has a density of
only 1.9 milligrams per cubic centimeter. It replaces the 2003
record holder—an aerogel developed by Jet Propulsion Laboratory
having a density of 3 milligrams per cubic centimeter.
Discovered in 1931, aerogel is a translucent solid that looks much
heavier than it is. Early scientific application of aerogels was
limited by the high densities of the samples and the small amount
of materials available for production. Today, less dense samples
are used in electronics, acoustics, thermal insulation, and optical
devices as well as for physics experiments.
Livermore scientists have been working with aerogels for more than
two decades. Not only have they reduced the density of aerogel,
but they also have improved material composition and clarity.
According to chemist John Poco, the Laboratory is a leader in aerogel
technology. “We use more materials to create it and more
innovative procedures than most anyone else.” But he adds, “Setting
a world record was never on our radar screen.” When CMS researchers
determined that others had claimed the lowest density, they wanted
to set the record straight. They contacted Guinness World Records,
sent documentation and samples, and received confirmation that
they now hold the world record.
Contact: John Poco (925) 423-9976 (email@example.com).
Cargo industry briefed on threats
At this summer’s International Cargo Security Summit in Chicago,
Livermore’s Executive Officer Ron Cochran described some
of the technology solutions being developed at the Laboratory to
address the threats that confront the freight transportation industry.
He noted that, in addition to the Laboratory’s unique capabilities
in assessing nuclear threats, it also has developed breakthrough
technologies in radiation and biological detection, information
analysis, and infrastructure protection systems.
Topics at the summit included regulatory requirements, how the
transportation industry can prepare for and respond to terrorist
attacks, and some of the technologies now available to improve
security. Participants also discussed the practicality of managing
security risks throughout the supply chain and how counterterrorism
measures can be implemented by all cargo transporters and related
container security is one of the nation’s most difficult
technical and practical challenges in preparing for and countering
terrorist threats,” says Cochran. “This [summit] was
an opportunity for the top experts in this area to get together
to discuss the issues and priorities as well as identify better
ways to keep their industry safe.”
Contact: Ron Cochran (925) 422-5153 (firstname.lastname@example.org).
Study confirms human effects on tropopause
A collaborative study including Livermore scientists has shown
that human-induced changes in ozone and well-mixed greenhouse gases
are the primary drivers of recent changes in the height of the
tropopause. The team—which included scientists from Lawrence
Livermore and Lawrence Berkeley national laboratories, the National
Center for Atmospheric Research, the Institut für Physik der
Atmosphäre in Germany, and the University of Birmingham in
the United Kingdom—focused its research on understanding
how different mechanisms affect atmospheric temperatures and, hence,
The tropopause is the boundary between the lowest layer of the
atmosphere—the turbulently mixed troposphere—and the
more stable stratosphere. It lies about 16 kilometers above the
Earth’s surface at the equator and 8 kilometers above it
at the poles. Its altitude is sensitive to changes in vertical
profiles of atmospheric temperature.
This collaborative study is the first to show that a model-predicted “fingerprint” of
tropopause height changes can be identified in observations. Earlier
research showed that increases in the height of the tropopause
over the past two decades are directly linked to stratospheric
ozone depletion and increased greenhouse gases.
The research team used climate models to provide quantitative estimates
of the relative contributions of natural and human influences to
overall tropopause height changes. From 1979 to 1999, tropopause
height increased about 200 meters, and according to the model calculations,
80 percent of that increase is directly linked to human activities.
In the first half of the 20th century, tropopause height increases
were smaller and were caused primarily by natural variations in
volcanic aerosols and solar irradiance.
describing this work appeared in the July 25, 2003, issue of Science.
Output from the climate models is available on the National
Energy Research Scientific Computing Center Web site.
Contact: Benjamin Santer (925) 422-7638 (email@example.com).