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Security
NIST
‘Phantom Material’ May Help Improve Metal Detectors
To
ensure that security at the nation’s airports is as strong
as it can be, metal detectors for detecting concealed weapons
must be as sensitive as they can be. However, no one wants these
devices to cause problems for innocent passengers using lifesaving
personal medical electronic devices (PMEDs) such as cardiac pacemakers.
The National Institute of Standards and Technology (NIST) soon
may be able to help solve the dilemma.
Providing
the solution to this problem may be a new, NIST-developed semisolid
“phantom material” that can simulate the electromagnetic
characteristics of different human body tissues over a range of
frequencies. Created by researchers in NIST’s Radio-Frequency
Technology Division, the moldable material (a carbon black-silicone
composite) could be embedded with PMEDs, and then sent through
a metal detector to determine the effect of the generated magnetic
fields on the function of pacemakers, hearing aids, infusion pumps
and the like.
Currently,
some metal detector manufacturers insert test objects in a liquid
that mimics the conductivity of different body tissues, but the
objects can shift within the liquid and produce varying readings.
Additionally, many test liquids evaporate or are unstable over
time.
The
new NIST semisolid material can be made to match the conductivity
of any body tissue and, because of its rigidity, keeps the PMEDs
in a test sample fixed. This material can be made to emulate the
electrical properties of a human for the frequencies over which
walk-through and handheld metal detectors operate.
This
research was funded by the Office of Science and Technology at
the National Institute of Justice through NIST’s Office of
Law Enforcement Standards.
Media
Contact:
Fred
McGehan (Boulder), (303) 497-7000
Historical
Restoration 
NIST
Helps U.S. Capitol with ‘Overhead’ Problem
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| 1859
Cross-Section Drawing of the U.S. Capitol Dome and Rotunda
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Repairing
a leaky roof usually doesn’t require the expertise and
skills of researchers at the National Institute of Standards
and Technology (NIST)—unless the building in need of help
is one of the nation’s most treasured edifices.
When the
150-year-old
dome of the U.S. Capitol in Washington, D.C., began leaking
during heavy rainstorms a few years ago, the Office of the Architect
of the Capitol consulted with engineers involved in welding
research at NIST. The daunting task handed them: return the
cast-iron supporting structure of the dome’s outer shell
to its original condition without replacing the cracked castings
or losing any of the iron work’s historical integrity.
That request
sparked a search for the right weld that would integrate with
1850s technology. An initial attempt in 1998 failed when the
test welds cracked. NIST engineers went back to the drawing
board (and the lab) to develop and test other options. The best-working
technique turned out to be oxyacetylene braze welding (a flame
repair process where the filler metal melts at a temperature
below that of the casting) combined with a copper-zinc alloy
called low-fuming bronze. The bronze forms joints that are very
similar in strength to the original castings.
NIST’s
experts have submitted their recommendation to the Architect’s
office.
Media
Contact:
Fred
McGehan (Boulder), (303) 497-7000
Environment
Improved
Ocean Color Mapping When the NIST SIRCUS Is in Town
As
a result of recent measurement corrections made possible by the
National Institute of Standards and Technology (NIST), the Earth’s
oceans may look a bit bluer than they did before in satellite
images—meaning there may be less carbon in the oceans than
previously thought.
A
unique NIST tabletop-sized instrument, called the “traveling
SIRCUS” (a miniature version of the agency’s Spectral
Irradiance and Radiance Calibrations with Uniform Sources facility),
was transported to Hawaii last year to calibrate the Marine Optical
Buoy systems (known as MOBY) that measure the color and magnitude
of light reflected from and within the ocean. Data from these
systems are used to calibrate satellite-borne color mapping instruments.
Ocean
color is important in climate research because variations in the
visible light spectrum reflect the concentration of microscopic
marine plants, which utilize carbon dioxide from the ocean/atmosphere
system for photosynthesis. These phytoplankton absorb blue light
and reflect predominantly green light, whereas water reflects
predominantly blue.
The
satellite observations are used to produce global assays of biomass
and carbon production in the world’s oceans.
The
laser-based traveling SIRCUS helped correct errors in the buoy’s
measurements.
The
corrections are having an impact on scientists’ calculations
of the biomass and carbon concentrations present in the oceans,
which will provide a more accurate understanding of Earth’s
carbon balance and its effect on climate.
Media
Contact:
Laura
Ost, (301) 975-4034
Law
Enforcement
New NIST
Standards Say ‘Hairs’ to Better Drug Testing
Traditional
methods of screening job applicants, athletes and others for illicit
drug use increasingly are being supplanted or complemented by
hair analysis, which offers several testing advantages. The accuracy
of such hair tests now can be quality assured through the use
of two new Standard Reference Materials (SRMs) from the National
Institute of Standards and Technology (NIST).
The
new NIST standards, which consist of human hair segments that
have been soaked in solutions containing target drugs, help validate
the accuracy of test methods for detecting those drugs. The first,
SRM 2379, is designed for tests of stimulants (“uppers”)
such as cocaine and PCP. Its companion SRM, number 2380, checks
tests for depressants (“downers”), such as codeine and
THC (the active ingredient in marijuana).
As
new hair tissue forms in the roots, drugs and other chemicals
from the bloodstream may be absorbed into and retained by the
growing follicles. Hair’s advantages in drug testing—when
compared to using fluids such as urine—are that it can be
collected more easily, is more difficult to switch or contaminate,
and retains traces of drugs for at least 90 days (not just two
or three). However, hair analysis generally is not applicable
to the detection of drug use initiated within the past 10 days.
Therefore, it may be favored as a complement to, rather than a
substitute for, traditional methods.
NIST
began researching the analysis of drugs in hair in 1990 and has
conducted seven interlaboratory comparison exercises to see how
well different methods work, and in some cases, how well different
laboratories conduct such tests.
Media
Contact:
Laura
Ost, (301) 975-4034
NIST/ISMT
Laboratory Puts the ‘Force' With Chipmakers
S
tar Wars fans know that things go better when the force is with
you. While that force helps solve galaxy-sized problems for the
Jedi Knights, scientists and engineers at the National Institute
of Standards and Technology (NIST) have teamed up with the semiconductor
industry to put the force—atomic force microscopy (AFM),
that is—to work at the other end of the size spectrum.
Microchip
manufacturers frequently need to measure dimensions of only 100
nanometers (four-millionths of an inch or about one-thousandth
the width of a human hair) within the devices they create. This
is especially true for “critical dimensions” (known
as CD in the industry), the smallest size that can be etched into
a computer chip uniformly. To ensure that chipmakers can accurately
and consistently assess CD, NIST has set up a special semiconductor
chip processing laboratory with AFM at International SEMATECH
(ISMT) in Austin, Texas. The outputs of this lab are reference
standards for the industry—standards contained in microchips
that have dimensional features measured with accuracy approaching
the level of the distances between atoms in a silicon crystal.
NIST’s
CD reference standards consist of micro-machined silicon crystal
materials that act as “rulers” for calibrating instruments
that make minuscule measurements during the chip manufacturing
process. A one-of-a-kind atomic force microscope, operated by
NIST personnel assigned to ISMT, can reveal important information
about tiny surface features on a chip with unprecedented clarity.
Media
Contact:
Philip
Bulman, (301) 975-5661
Physics
'Stone
Cold' Video Showcases NIST's Hunt for New State of Matter
It
was a scientific milestone that many said would never be realized.
Some called it the “Holy Grail of physics.” But on June
5, 1995, physicists Eric Cornell of the National Institute of
Standards and Technology (NIST) and Carl Wieman of the University
of Colorado at Boulder observed the Bose-Einstein condensate (BEC)
for the first time. It had been 71 years since Albert Einstein
predicted that a new state of matter would be created if individual
atoms melded into a “superatom” at temperatures approaching
absolute zero.
For
their breakthrough, Cornell and Wieman shared the 2001 Nobel Prize
in Physics with Wolfgang Ketterle of MIT.
Recently,
Cornell gave a public lecture at NIST’s Gaithersburg, Md.,
headquarters on his research entitled “Stone Cold Science.”
The lecture was videotaped, and the VHS-format program is now
available at no charge from NIST.
In
the 74-minute video, Cornell chronicles the search for the BEC,
describing in detail just what the “weird world of physics
at a billionth of a degree from absolute zero” is like. The
program will be of great interest to high school, college and
graduate-level physics students and teachers, as well as anyone
fascinated by the process leading to scientific discovery.
To
request a free copy of the educational video, write to NIST Public
Inquiries, 100 Bureau Dr., Stop 3460, Gaithersburg, Md. 20899-3460,
fax a request to (301) 926-1630, or send an e-mail message to
inquiries@nist.gov.
