Law
Enforcement
NIST
Creates ‘Magic’ Bullets (and Casings) Against Crime
Two
robberies take place at different sites in New York City a few
days apart. Police suspect that the same person is responsible
but only have small pieces of evidence with which to make the
link: bullets and casings found at the two locations. Thanks to
new “standard bullets and casings” from the National
Institute of Standards and Technology (NIST), any forensic scientist
trying to match these bullets and casings could be confident with
his or her results.
Ballistic
evidence is considered valuable because each gun’s firing
pin and ejection mechanism imparts distinctive markings—known
as “signatures”—on fired bullets and ejected casings.
The computerized optical-imaging instruments used to examine these
signatures must be calibrated for accuracy.
To
provide the tools needed to do the critical calibrations, NIST
has manufactured standard bullets—known as NIST Reference
Material (RM) 8240—and standard casings—known as NIST
RM 8250—with identical signatures. The signatures on each
bullet and casing RM created by NIST are exactly the same as those
on every other corresponding artifact in the two series. Quality
bullets previously used in forensic laboratories were produced
by a standardized shooting procedure and, therefore, exhibited
minute changes in signatures over time due to gun wear and environmental
conditions.
NIST
researchers also are working on a “virtual” or digital
bullet signature standard that crime laboratory personnel can
access with their computer from the national laboratory center
at the Bureau of Alcohol, Tobacco and Firearms (ATF) and the Federal
Bureau of Investigation (FBI).
Media
Contact:
John
Blair, (301) 975-4261
Fire
Research
Video
Illustrates Impact of Sprinklers on Dorm Room Fires
It
may not be the MTV version of “Burnin’ Down the House”
by the Talking Heads, but a new fire research video from the
National Institute of Standards and Technology (NIST) promises
to be a hot item anyway—that is, with those concerned with
fire safety in dormitories.
The
nine-minute video of recent test fires in two scheduled-for-demolition
University of Arkansas dormitory rooms taken by in-room cameras
dramatically demonstrates how effective sprinklers can be in
controlling fires in this type of environment.
Two
fully furnished dormitory rooms are depicted in the video, one
with and one without sprinklers. A fire is ignited in the wastebasket
in each room. In the dormitory room with the sprinklers, the
devices activated in under two minutes and extinguished the
fire. In the room without fire extinguishing equipment, the
blaze reached “flashover” conditions (when all combustibles
in a room burst into flames and the fire spreads rapidly) in
less than six minutes.
The
video also includes post-fire photographs, which can be used
to compare the damage caused by each fire.
The
college dormitory experiments were sponsored by the U.S. Fire
Administration.
This
video should prove to be an effective education tool. For a
free VHS copy, send a request to NIST’s Nelson Bryner by
fax at (301) 975-4052 or by e-mail to nelson.bryner@nist.gov.
Media
Contact:
John
Blair, (301) 975-4261
Manufacturing
‘Cutting’-Edge
Technology to Better Shape Submarine Propellers
Super
smooth propellers of maximum structural integrity allow submarines
to run silently in deep water. These nickel-aluminum-bronze alloy
propulsion units take as long as 12 months to manufacture—a
production time that the US Navy feels is too long. So, National
Institute of Standards and Technology (NIST) high-speed machining
experts are working with the US Navy and the University of North
Carolina at Charlotte (UNCC) on a new machine tool and special
metal-cutting strategies to decrease that time to four months.
A
submarine propeller begins life as a greater than six-meter (20-foot)
diameter, 50,000-kilogram (55-ton) metal casting. It must be machined
down to a mass near 37,000 kilograms (41 tons) in its final form.
Current machining methods leave the propeller with a rough surface,
which if left unchanged, would betray a submarine’s movements
in the ocean. So, months of hand finishing are required.
“Such
a time-consuming process may soon be a thing of the past,”
said Tony Schmitz, a NIST engineer working on the project. “NIST’s
tool wear and surface finishing experiments have led to a better
understanding of the required parameters for high-speed machining
of the propeller alloy. These discoveries have enabled us to increase
the material removal rate during machining by a factor of 10.
Additionally, refinements in the paths that the tool follows during
metal cutting promise to substantially reduce roughness in the
final milled propeller surface.”
Media
Contact:
John
Blair, (301) 975-4261
Environment
New Tool
Promises Better Predictions of Gas Impacts
The
potential environmental impact of new fire suppressants and other
gaseous compounds, from refrigerants to industrial solvents, can
be estimated much faster now than ever before—in hours instead
of months—thanks to
a computational tool developed by the National Institute of Standards
and Technology (NIST).
The
new tool reliably estimates a compound’s atmospheric lifetime
(i.e., how long it lasts before breaking down), the starting point
in calculating the potential contribution to stratospheric ozone
depletion and global warming. Until now, laborious and costly
laboratory measurements were required to assess new classes of
compounds, such as environmentally safe replacements for the halons
long used as fire suppressants. The new approach, which relies
on several existing software programs, overcomes past difficulties
in correlating chemical structure and reactivity.
The
computational tool is based on several years of theoretical work
involving quantum mechanical calculations. NIST researchers made
calculations at three levels of theory for a large set of chemical
reactions for which the reaction rates were well known. An optimal
level of theory was found that matched experimental results closely
enough to be considered reliable—and was frugal in its use
of computational resources. This may make routine use of the tool
practical.
The
tool has been used to screen potential fire suppressants and already
has identified one with a short atmospheric lifetime, making it
a candidate for further study. Efforts are continuing to enhance
and further simplify the computations.
Media
Contact:
Michael
E. Newman, (301) 975-3025
New Standards
from NIST May Provide ‘All-Natural’ Benefits
A
new National Institute of Standards and Technology (NIST) effort
to develop standard reference materials (SRMs) for a number of
popular botanical dietary supplements will provide tools that
manufacturers can use to improve quality control during production,
that researchers can use to ensure that their laboratory analyses
of test substances are accurate, and that the Food and Drug Administration
(FDA) can use in monitoring marketed products and, when appropriate,
in enforcement actions. Ultimately, consumers benefit because
these efforts will ensure that marketed products contain what
they are supposed to contain.
NIST
was asked to develop the standards by the National Institutes
of Health (NIH) Office of Dietary Supplements and the FDA, which
are providing partial funding for the project.
NIST
will certify the concentrations of designated constituents in
botanical ingredients and finished product preparations. The standards
development program will begin with botanical sources of ephedrine
alkaloids and kava, two widely marketed ingredients in dietary
supplement products. Additional SRMs for nutriceuticals (nutritional
supplements designed for specific clinical purposes) to be provided
by NIST will be determined based on priorities provided by the
NIH and FDA.
Information
about ephedra, kava and other dietary supplements can be found
at http://ods.od.nih.gov/
and http://vm.cfsan.fda.gov/.
Media
Contact:
Michael
E. Newman, (301) 975-3025
Genetics
New NIST
Procedure Seeks Improved Diagnosis of Fragile X Syndrome
A
robust protocol for measuring a specific class of genetic elements
called “trinucleotide repeats” has been optimized at
the National Institute of Standards and Technology (NIST) to help
clinical laboratories accurately identify Fragile X syndrome,
the most common cause of inherited mental retardation. The research
is part of a NIST effort to develop standards for measuring the
expansion of these trinucleotide repeats. The NIST protocol responds
to the guidelines recently issued by the American College of Medical
Genetics, which recognized that Fragile X is one of the most frequently
ordered genetic tests and that there are many testing methods
with different strengths and weaknesses.
Fragile
X syndrome results from the repetition of a particular sequence
of three chemical units on the X chromosome. About 30 repeats
is normal; higher numbers, especially in the range of 60 to 200,
indicate an unstable “premutation” repeat length. As
the number of repeats increases in successive generations, the
production of a certain protein is shut off and symptoms of the
disease appear or become more severe. Thus, accurate measurement
of the size of the affected region of the chromosome is important
as a diagnostic indicator of the disease and likelihood in future
generations.
Current
methods become less reliable when the number of repeats exceeds
100. The NIST protocol establishes specific conditions for the
creation of multiple copies of the genetic material and their
analysis. NIST initially focused on repeat sizes of about 30 to110;
future work will assess methods for measuring larger repeat elements.
