Bureau researchers testing human eyeballs donated to eye banks for research purposes.

continued development of predictive methods which will be used in establishing standards for protective headgear, such as football helmets.

technical assistance by the NBS Law Enforcement Standards Laboratory (LESL) on tests of body armor worn by police officers. Based on a LESLdeveloped voluntary standard, tests conducted by the International Association of Chiefs of Police and the Law Enforcement Assistance Administration determined that nearly half of the commercially-available vests tested did not meet performance levels claimed by manufacturers.

⚫ completion of guidelines on window and door security by LESL. These guides are intended to acquaint the general public, architects, and building code officials with the window and door security standards developed by LESL for the Law Enforcement Assistance Administration.

assistance to CPSC in evaluating safety tests for miniature Christmas tree lights. NBS proposed several of its own tests in addition to those previously recommended to CPSC by the National Consumers League, a group which had drafted test standards for the Commission. CPSC adopted the proposed NBS changes as part of its possible standard for the lights. Underwriters Laboratories, a nationally recognized testing firm, independently adopted the NBS methods for use in its testing.

The Bureau's Law Enforcement Standards Laboratory develops standards and guidelines for law enforcement and criminal justice

equipment. Ralph Gorden is shown with

laboratory arrangement used to test

performance of body armor worn by police officers.

Particularly important to such applications is resistance to wear, a characteristic dependent in part on the molecular weight of the plastic. In collaboration with a guest worker from the Food and Drug Administration (FDA), NBS researchers in the Center for Materials Science have shown that a commonly used method for measuring the plastic's molecular weight is unreliable. They are currently working on a more accurate measurement method.

In cooperation with the American Dental Association Health Foundation

through its long-standing Research Associate Program at NBS, the dental materials and products group within the Center for Materials Science completed several major projects. With the rising cost of gold, the need for alternative dental alloys has become more critical. Titanium alloys, used extensively in the aerospace industry and lately for artificial hip joints, have been considered for dental applications because of their resistance to corrosion and compatibility with body tissues. Recent efforts in the dental program demonstrated for the first time that a

titanium alloy could be used in dental castings by employing conventional dental laboratory equipment. This leads the way for use of this less expensive alloy to supplement or replace gold as a basic dental material.

As part of the same program, researchers developed a new fabrication procedure for dental porcelain that promises better quality control and a reduction in space and labor requirements. They also demonstrated a method for significantly improving the storage stability of certain dental composites used in fillings and developed an inexpensive analytical technique to measure the low levels of fluoride concentration encountered in dental applications.

NBS has developed and produced more than 70 Standard Reference Materials (SRM's) for medical measurement applications. SRM's are well characterized materials or measuring devices which have one or more physical or chemical properties certified

by NBS. They come in many different forms, from fine crystals or powders to sealed vials and thermometers. SRM's are used widely for calibrating or testing all kinds of measuring instruments and are an important Bureau service to many users (see page 67). The Bureau's SRM's are especially needed in the clinical chemistry area, where 4 billion measurements are made annually and where accurate measurements are essential to aid physicians in diagnosing disease. Working through the NBS Office of Standard Reference Materials, the Center for Analytical Chemistry has completed several projects of immediate usefulness in clinical analysis.

A newly developed SRM will assist physicians in monitoring anti-epilepsy drugs in the serum of patients under therapy. Serum is the clear substance. remaining after red blood cells, fibrinogen, and various other components of blood samples are separated out. In the case of epilepsy, knowledge of the exact concentrations of anti-epilepsy drugs in the patient's serum is very important, especially in the treatment of patients whose disease is difficult to control. Yet, comparisons among laboratories have documented disturbingly large variations in measurement accuracy. The new NBS SRM consists of freeze-dried human serum containing four anti-epilepsy drugs at various accurately determined concentrations. Another new SRM, for use in determining iron in serum, was issued by NBS and will be relied upon in the diagnosis of hepatitis, obstructive jaundice, and various anemias.

During FY 1978, a new definitive method was developed by NBS for the accurate analysis of cholesterol in serum. Based on a special technique (isotope dilution mass spectroscopy),

The SonoChromoscope is a unique medical diagnostic tool which projects sonic pulses into living tissue and analyzes the response. The signals are processed into pictures with the aid of a computer. Thomas Shawker (foreground) of NIH is testing the device, aided by NBS developer Melvin Linzer.

this method will be used with previously developed NBS definitive methods for other serum constituents in the certification of a human serum SRM. This SRM will be useful in the accurate diagnosis, monitoring, and treatment of a range of medical conditions in patients. Like all clinical analysis SRM's, it will be particularly important to patients who move from one part of the country to another or to those who travel and need assurances that the laboratory serum measurements are correct and based upon comparable equipment and procedures.

areas.

The Bureau is working in other measurement-related health Techniques using ultrasonic waves outside the hearing range of the human ear have been introduced in medical and industrial applications over the past several years and are providing the medical community with new and exciting diagnostic and therapeutic tools. NBS has helped to foster use of this technology. A new Bureau device, known as the SonoChromoscope was developed by a scientist in the Center for Materials Science. It is being evaluated by the National Institutes of Health (NIH) and is receiving close attention as an aid in detecting tumors and fetal defects. It may also prove to be a safer way to screen for breast cancer than the currently used method of x-ray mammography.

Other Safety Research

Many other projects at NBS designed to protect public health and safety were completed or reached significant milestones during the fiscal year. For example:

Scientists in the Center for Thermodynamics and Molecular Science calibrated and characterized pressure transducers that will help aircraft pilots keep better track of their altitudes.

• A new instrument which uses lowpower microwave radar to monitor coal seam thickness in mines was developed in the Center for Electronics and Electrical Engineering. Use of the instrument is expected to help improve mine safety and coal mining productivity. Also, the Center for Applied Mathematics devised a statistical plan for testing coal mine dust samplers in collaboration with the Bureau of Mines and the Mine Safety and Health Administration.

Test methodologies and data have been developed to assess the mechanical durability of plastic shipping containers used for hazardous materials transportation. This work was conducted in the Center for Materials Science.

• An extensive investigation of an overthe-highway steel pressure vessel that ruptured while being filled with natural gas was conducted by the Center for Materials Science for the Department of Transportation. The NBS investigation of the accident, which killed two people, has pointed to the critical need for developing a data base to evaluate the susceptibility of pressure vessel steels to hydrogen enbrittlement caused by harmful chemicals.

Ultrasound offers safety, cost, and application advantages over conventional equipment for some purposes. But, like x-ray techniques, ultrasonic methods require that the dosage be known accurately if its users are to receive correct information about the area examined. Furthermore, studies of possible biological effects and the development of safety standards for medical uses of ultrasound rely on ac

curate measurements.

Researchers in the Center for Materials Science have constructed a prototype transducer which gives a

more accurate measurement of ultrasound dose and will help to calibrate other transducers-critical components of ultrasound devices which send out sonic radiation and receive the return sonic signal which bounces off and helps characterize the targeted body area. The new transducer is made of piezoelectric polymers, materials which can deliver an electrical charge that is related to the pressure placed on the polymer. NBS is one of a handful of laboratories in the United States studying the basic theory, materials properties, and applications of piezoelectric

polymers. A pioneer in applying these materials, the Bureau has developed a number of piezoelectric devices useful to the medical community.

NBS work on the polymer transducer prompted FDA to send a guest worker to the Bureau to investigate the design and construction of the device. The report: the polymer transducer offers a number of advantages over its currently used crystal or ceramic counterparts and facilitates more accurate measurement of ultrasound dose. While the total and average dose delivered by an ultrasonic beam may be considered

Nuclear Safeguards

A number of notable achievements in the area of nuclear safeguards were registered last year as part of a continuing, interdisciplinary program involving several NBS centers. Coordinated by the Office of Measurements for Nuclear Safeguards, NBS work in this area is supported by the U.S. Nuclear Regulatory Commission and the Departments of Energy and State. This research aims to improve the quality of nuclear fuel measurements, thus providing sensitive and timely methods for detecting and determining diversion of nuclear materials from government and industrial facilities in the United States and abroad. Accomplishments in FY 1978 include:

⚫ development of a method for calibrating the volume of storage tanks for nuclear materials that is 10 to 100 times more accurate than existing methods. This work by the Center for Mechanical Engineering and Process Technology is of the utmost importance since accurate knowledge of the volume of these tanks is essential for the determination of the mass of stored nuclear material and for subsequent accounting of this material as it passes through the processing facility. The Center for Applied Mathematics contributed to the improved volume calibration by providing

a new methodology for handling the large amounts of data involved in the calibrations.

⚫ substantial improvement in the determination of the half-life of plutonium 239 in the Center for Radiation Research as part of a concentrated national effort in this area.

demonstration of the feasibility of a technique newly developed by the NBS Center for Radiation Research for identifying plutonium and uranium content in nuclear fuel materials. Based on resonance neutron radiography, this technique can reveal differences not only among elements but also among isotopes, providing a more accurate indication of the nuclear material. In a related project, Center for Materials Science researchers, in conjunction with the Los Alamos Scientific Laboratory, made progress in the development of a resonance neutron tomography technique that also could provide greater accuracy in the same difficult measure

ment area.

⚫ development of an improved uranium assay Standard Reference Material (SRM). This is one of a series of SRM's being developed by the Center for Analytical Chemistry that will bring about an improvement in the calibration

of instruments used to measure nuclear materials.

completion of a study to determine whether infrared thermography techniques would be useful for measuring plutonium accumulating in pipes and other segments of the nuclear fuel cycle. Thermography, which measures temperature differentials due to heat liberated from plutonium, has been considered a promising measurement method. However, this research in the Center for Absolute Physical Quantities indicated that the technique has major limitations and is not likely to be useful for quantitative plutonium measurement applications.

development of methods to evaluate the performance of pressure transducers used to measure the volume of nuclear materials in fuel tanks. This work was performed in the Center for Thermodynamics and Molecular Science.

publication and field demonstration of a diversion path analysis handbook written by scientists in the Center for Radiation Research for operators of government-owned nuclear facilities.