NIST Tech Beat, December 1998

The Second Sprung—by David Lovering

In UTC at midnight
On December Thirty-One,
You’ll find you get an extra
Second full of fun.
If you’re not in Greenwich England
When the moment comes about,
You’ll need to make adjustments
To the interval in doubt
At seven in the evening
(For those on EST),
Or six p.m. in Central,
Or five for MST.
Or four p.m. Pacific
Or wherever you may be,
Please thank your friendly NISTite
In Time and Frequency!
For our globe is spinning slower
(As we all are, I’m afraid),
While the Earth Rotation Service
Notes the seconds it’s delayed.
Since we cannot speed the planet
We must compensate the clock,
And leap an extra second
To match our slowing rock.

Leap Second

Leap Second Scheduled for New Year's Eve

On December 31, 1998, a leap second will be inserted into the world’s Coordinated Universal Time scale, known as UTC, to keep it synchronized with the rotation of the Earth. The leap second will be added to the last minute before 7 p.m. EST, 6 p.m. CST, 5 p.m. MST and 4 p.m. PST, making that minute 61 sec-onds long. This adjustment will be made to precise clocks all over the world that keep UTC time or local time based on UTC. In the U.S., UTC is kept by the National Institute of Standards and Technology and the U.S. Naval Observatory.

Building and Fire Research

NIST Scientists Study High-Strength Concrete Failure in Fires

Scientists at the National Institute of Standards and Technology are studying the performance of high-strength concrete under fire conditions to find ways to use it safely. HSC is a state-of-the-art material that is increasingly popular in the construction industry. The study includes testing HSC specimens at elevated temperatures by researchers at NIST’s Building and Fire Research Laboratory. Past experiments have shown that high temperatures significantly weaken HSC. It has higher potential for sudden failure than normal strength concrete when exposed to temperatures of 350 degrees Celsius or higher.

These temperatures are well below the range of a typical building fire, and researchers believe the sudden failure of HSC in fires potentially could trigger catastrophic building collapses. HSC has been gaining in use in recent decades in buildings ranging from the Trump Tower in New York to the Chicago Mercantile Exchange. Designers and building owners favor HSC because it allows the use of smaller beams and columns, resulting in more usable space, lighter structures and lower foundation costs. The results of the NIST study may be incorporated into future building codes to guide designers in the safe use of HSC.

Biotechnology

Want Your Medication Scrambled or Over Easy?

Sometimes when an R&D project lays an egg, it’s a success. That’s the hope anyway at AviGenics, Inc., a small research company in Athens, Ga. AviGenics has launched a research program to genetically engineer chickens, enabling them to produce pharmaceutically valuable proteins in their eggs.

Several researchers have investigated the possibility of genetically engineering animals to produce important proteins in their milk, but, says AviGenics, it may be faster and more effective to develop hens that lay eggs with the desired proteins in the egg whites. AviGenics recently received a $1.5 million cost-sharing award from the National Institute of Standards and Technology’s Advanced Technology Program to investigate a new technique for inserting bits of tailored DNA into the chickens’ chromosomes. Their initial goal is a chicken that produces eggs with large amounts of human serum albumin, an important therapeutic protein. Currently, human serum albumin is isolated from human blood at a cost of $750 to $1,500 per kilogram. AviGenics estimates that a single large henhouse could produce about 22,000 kilograms annually—5 percent of the global demand—at a cost of about $80 per kilogram. Other possible products, they say, are human blood factors such as those used to treat hemophiliacs, antibodies and most other biopharmaceuticals.

Physics

Is it Half Enough? NIST Measures Titanium-44 Half-Life

We are stardust,” according to a 1970s song. Most elements making up the Earth, including many critical for life, were produced by ancient supernova explosions. Scientists studying exploding stars recently received an unexpected boost from National Institute of Standards and Technology measurements of radioactivity for medical and environmental applications.

Scientists measure new elements formed in supernova explosions by counting gamma rays from the decay of the resulting radioactive elements. Unfortunately, most radioactive elements produced in significant amounts decay either too quickly or too slowly to permit useful gamma ray measurements. One radioactive element, titanium-44, has a half-life just right for studying relatively recent explosions, such as Cassiopeia A, which in 1680 was the most recent supernova in our galaxy. But until recently, the half-life was so poorly known that estimates of the amount of titanium-44 produced differed by a factor of three, not good enough to reconcile various computer models of supernova explosions.

Physicists at NIST made a very accurate measurement of the titanium-44 half-life (60.7 years) by analyzing radioactivity measurements of a single titanium-44 sample made over a period of twenty years. The most reliable way to measure a half-life is to observe the decay for a time period comparable to the half-life. The NIST determination was the first long-term titanium-44 measurement ever made, and it improved the half-life measurement by about a factor of ten. Astrophysicists already have used this result to improve models of supernova explosions.

Electronics

New Devices Might Bring Giant Advances

Scientists are making progress in harnessing “giant magnetoresistance,” a phenomenon at the heart of a new class of electronic devices that promise to dramatically increase the storage density of computer hard drives and improve the performance of video equipment. But industry must develop new processing techniques and find better materials to fully exploit the potential benefits of GMR, which might be used to design devices that are extremely sensitive to magnetic fields within tiny regions. When such GMR devices are incorporated into the read heads of hard drives and video equipment, the heads can pick up magnetically stored data in smaller units than is possible with conventional technology. The GMR technology almost certainly will lead to a 10-fold increase—and could eventually lead to a 100-fold increase—in hard-disk capacity, as well as a wide range of electronics innovations, including pocket-size camcorders and super-sensitive magnetic detectors with industrial and military applications.

Recently, in ongoing work at the National Institute of Standards and Technology, researchers have developed methods to optimize the properties of GMR materials. NIST scientists, who produce and analyze experimental GMR materials using a one-of-a-kind apparatus built five years ago, have discovered recently that performance can be improved by producing GMR materials in the presence of a tiny amount of pure oxygen in a vacuum chamber. The findings were detailed in a research paper delivered during a scientific meeting in June 1998.

Time

Do As the Romans Do ... or Don’t?

While the Year 2000 problem has people worldwide fearing what will happen to their computers on that Jan. 1, another calendar-related controversy will begin 365 days earlier. The dilemma faced on Jan. 1, 1999: how will one write out the year in Roman numerals?

Because the National Institute of Standards and Technology is one of two official timekeepers for the United States (the U.S. Naval Observatory is the other atomic clock operator), the agency’s Research Library often addresses questions on how to correctly express times and dates. Recently, the NIST librarians were asked to tackle the issue of whether the year 1999 should be written as MCMXCIX or MIM.

Their response was that while MIM is more convenient, MCMXCIX probably will be favored because of earlier precedents with numbers such as 49 (written as XLIX rather than IL). However, the librarians point out that purists will use neither MIM nor MCMXCIX, opting instead for MCMXCVIIII. The ancient Romans, they explain, did not use the 20th century convention of IX for the number nine.

Calls to the U.S. Copyright Office, the Motion Picture Association of America, the Directors Guild of America and the American Institute of Architects revealed that none of the bodies controlling copyright notices, film credits and cornerstone inscriptions—all of which use Roman numeral dates—has an action plan for dealing with the “Year 1999 problem.”

Tech Trivia

During WWII, variations in the threads on bolts and screws manufactured in the United States and Great Britain often delayed fitting parts and repairing military hardware. By the early 1950s, the United States, Britain and Canada, with assistance from the National Bureau of Standards (now NIST) agreed to standardize fastener threads.

Research on dental materials at the National Bureau of Standards (now NIST) has improved greatly the quality and duration of amalgam fillings. Tests at NBS contributed to new dental materials that don’t shrink, break or dissolve in the mouth as they once did. Dental materials research continues today in NIST’s Dental and Medical Materials Program.

Tests on the strength of human bone conducted by the National Bureau of Standards (now NIST) and the U.S. Navy helped determine how much force could be used in a jet fighter pilot’s ejection seat.