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Volume 100, Number 4, JulyAugust 1995Journal of Research of the National Institute of Standards and Technology

General DevelopmentsInquiries about News Briefs, where no contact personis identified, should be referred to the Managing Editor,Journal of Research, National Institute of Standardsand Technology, Building 416, Room 119, Gaithersburg,MD 20899-0001; telephone: 301/975-3572 .

NEW WEB SITE SERVES AS GUIDE TO NIIThe Clinton Administrations Information Infrastruc-ture Task Force recently launched an online resource tohelp people better understand benefits of the NationalInformation Infrastructure, sometimes referred to as theinformation superhighway. The NII Virtual Libraryhome page provides any user with explanations of theNII and how it works and provides system developerswith information on NII applications. The new WorldWide Web site, co-sponsored by the IITF and theCouncil on Competitiveness, features links to informa-tion sites developed by universities, museums, largecorporations, small businesses, government agencies,non-profit groups and other organizations with an inter-est in using the NII. It was developed by the IITF Com-mittee on Applications and Technology with the supportof the Office of Enterprise Integration at NIST. The sitecan be reached at http://nii.nist.gov by anyone with aproperly equipped computer running World Wide Webbrowsing software, such as Mosaic or Netscape. Fortechnical assistance when accessing the home page,contact Rick Kuhn at (301) 975-4601 or e-mail:[email protected] (via Internet).

PHOTOVOLTAIC HOT WATER SYSTEMEXCEEDS EXPECTATIONSA full-scale prototype of a novel solar water heatingsystemthe first to use photovoltaic cells in combina-tion with computer technology to capture the sunsenergyhas performed better than expected duringtesting at NISTs headquarters in Gaithersburg, MD.PV cells are semiconductor devices that convert the

News Briefs

energy in sunlight into electricity. These cells allow theNIST system to directly heat water in its tank, a distinctadvantage over traditional devices that pump water to arooftop solar collector and then return the heated liquidto storage. The NIST tests used a computer-based dataacquisition method to withdraw hot water from thesystem as if used by a typical family of four. During arecent 3 month monitoring period, the NIST solar waterheater provided 67 % of the total energy required versusa projected 50 % contribution. As a result, NISTengineers currently are reducing the size of the PV arrayby 25 % and making other modifications to yield a lessexpensive system. Monitoring of the revised waterheater began in June. Industry partners on this projectare welcomed. Contact Hunter Fanney, B320 BuildingResearch Building, NIST, Gaithersburg, MD 20899-0001, (301) 975-5864, e-mail: [email protected](via Internet).

STRESS MEASUREMENTS ASSESS RAILROADWHEEL SAFETYRailroad wheel failure is commonly caused by cracksthat propagate from the rim toward the hub. Wheels aremanufactured to put the rim under residual compressivestress, which tends to close these cracks and preventwheel failure. However, heavy braking can heat thewheel enough to make the rim stress become tensile,promoting the propagation of cracks. Detecting thisreversed stress condition traditionally has been done byvisual inspection of discolorations. NIST has collabo-rated with the Association of American Railways andtwo Polish research groups to develop ultrasonicmethods for detecting stress in wheels. The results ofthis work are promising and are reported in two papers(numbers 13-95a and 13-95b) available from SarabethHarris, Div. 104, NIST, Boulder, CO 80303-3328, (303)497-3237, e-mail: [email protected] (via Inter-net). For technical information, contact Ray Schramm,Div. 853, NIST, Boulder, CO 80303-3328, (303) 497-3232, e-mail: [email protected] (via Internet).

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AUGUST CONFERENCE FOCUSES ONDIAMOND APPLICATIONSRapid progress in processing technologies soon couldlead to new diamond materials applications in sensors,flat-panel displays, wear-resistant surfaces, cuttingtools, electronics and opto-electronic devices. Diamond,the hardest known natural material, also has the highestthermal conductivity. Its physical and chemical proper-ties make it ideal for use in aerospace products,electronics and industrial equipment. To identify techni-cal barriers hindering the development of large-scalecommercial applications of diamond and diamondfilms, the Third International Conference on theApplications of Diamond Films and Related Materialswas held Aug. 21-24, 1995, at NIST headquarters inGaithersburg, MD. Manufacturers and users of diamondand related materials discussed recent technologicaladvances with materials researchers. For technicalinformation, contact Albert Feldman, A329 MaterialsBuilding, NIST, Gaithersburg, MD 20899-0001,(301) 975-5740, fax: (301) 990-8729, e-mail:[email protected] (via Internet).

ACCURATE PRICES GOAL OF NEWNCWM PROCEDUREState and local government officials attending the 80thAnnual Meeting of the National Conference on Weightsand Measures in Portland, Maine, July 16-20, 1995,voted on the adoption of a procedure for verifying theaccuracy of retail store prices. The procedure, whichinvolves checking the prices of products scanned at astores checkout counter against the advertised prices forthe products, helps ensure that consumers are correctlycharged for items they purchase. The proposed proce-dure represents a cooperative effort among more than500 retailers, consumer representatives, and state andlocal weights and measures officials. The proceduremust be adopted officially by individual states to be-come law. NCWM is an organization of state, countyand city weights and measures enforcement officialsand associated business, federal and consumer represen-tatives. Through its Office of Weights and Measures,NIST provides technical assistance to NCWM. For moreinformation on the conference and the 80th AnnualMeeting, contact the NCWM at P.O. Box 4025,Gaithersburg, MD 20885, (301) 975-4004, fax: (301)926-0647.

USDA ADOPTS UPDATED VERSIONS OF TWONIST HANDBOOKSOn March 9, 1995 the Food Safety and InspectionService of the U.S. Department of Agriculture pub-lished a final rule amending the federal meat and poul-try products inspection regulations to adopt updatededitions of two NIST handbooks. The rule, which wentinto effect May 8, adopts applicable portions of NISTHandbook 44, Specifications, Tolerances, and OtherTechnical Requirements for Measuring Devices, 1994Edition, and NIST Handbook 133, Checking the NetContents of Packaged Goods, Third Edition and supple-ments 1-4. The handbooks are published by the Weightsand Measures Program in the Office ofStandards Services in cooperation with the NationalConference on Weights and Measures.

ENERGY-RELATED INVENTIONS PROGRAMRECOMMENDATIONSThe NIST Office of Technology Evaluation and Assess-ment recommended these innovative technologies forcommercialization to its DOE partner under the Energy-Related Inventions Program during February andMarch:

Clemson Camshaftan innovative design for acamshaft for internal combustion engines that willallow variable intake or exhaust valve timing. Twoconcentric shafts carry separate components of thecams so that relative rotation of the two shafts canchange the action of the cams. A novel feature is theuse of a single shaft to perform the timing events andtheir duration, which is important to domestic manu-facturers who want to extend the design life of theirpushrod engines.

Apparatus for Removing Bark from Whole Logsan apparatus designed to remove bark from delimb-ed tree stems by raising stems from the bottom of amass of stems and dropping them back on top of thepile. Abrasion from moving the logs into position todrop onto the pile, and compressive forces from theimpact of the stems, loosen and remove the bark.Innovative features include the degree of controafforded the operator in terms of early removal of

logs that have been debarked to specification or therecycling of logs that are not, and the tailoring of thedebarking process to a particular species of tree.

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NIST HELPS COMPANY WITH MEASUREMENTOF PULSE ENERGY FOR INKJETPRINT-HEADSA NIST scientist has helped a private company in anassessment of methods for measuring the pulse energydelivered to print-heads marketed by the company foruse in inkjet printers. The worldwide print-head marketnow tops $1 billion annually, with a high growth rate.Print quality is critically dependent on the amount oftotal energy delivered by well-defined electrical pulsesto the load resistor in each of an array of little reservoirs;these pulses are typically a few microseconds in dura-tion and several volts in amplitude (the resistor heats theink to the boiling point, and as a result droplets areejected through a small orifice onto the paper). Thescientist initially applied the NIST-developed samplingcomparator system to determine if the method presentlyused by the company could achieve the desired uncer-tainty in energy measurement of 61 %. Errors due tofrequency response of the load resistor, short-term in-stability of the pulse generator, noise and residual gain/offset errors, errors in the sampling system time-base,and frequency response errors of the sampling probeswere taken into account. The scientist then evaluated anapproach for assuring traceability for these measure-ments using a root-mean-square voltmeter, but he foundthis method had insufficient accuracy and repeatability.Finally, he was able to demonstrate that a sufficientlysmall uncertainty could be achieved by using the wave-forms from a calibrated commercial pulse generator tocalibrate the sampling oscilloscope used in the compa-nies test system. To maintain traceability to NIST stan-dards, the scientists recommended that a reference pulsegenerator for each test system periodically be sent toNIST for calibration. The results of this evaluation weredocumented in a report prepared for the private com-pany.

BIOELECTRICAL IMPEDANCE ANALYZERSSTUDIEDA NIST scientist has completed a project to evaluate theperformance of six commercial bioelectrical impedanceanalyzers (BIAs). BIAs are widely used to measurebody composition by health-researchers, hospitals andclinics, as well as diet and fitness centers. NIH (NationalInstitutes of Health) had some concerns about themeasurement consistency of these instruments, in partbecause most of the clinical studies that relate bodyimpedance to disease assume that the BIAs are errorfree. The NIST scientist found that the disagreementbetween analyzers ranged from 1 % to as high as 20 %for measurements of known artifacts that simulate bodyimpedance components. He described his results last

December at NIH at the Technology AssessmentConference on Bioelectrical Impedance Analysis inBody Composition Measurement in the paperOverview of Bioelectrical Impedance Analyzers.The paper now has been submitted for publication in theAmerican Journal of Clinical Nutrition.

There have been several thousand technical paperspublished on the application of BIAs, with several hun-dred new papers each year.

A typical BIA measures complex body impedancebetween the wrist and ankle at 50 kHz. Algorithms inthe BIA software use this information, along with bodyheight, to determine total body water, assuming that theapplied current is conducted primarily in extracellularbody water. Body fat is predicted using algorithms thatincorporate additional body parameters such as bodyweight.

PARTIAL DISCHARGE MEASUREMENTLABORATORY ESTABLISHEDA new laboratory for developing methods for detectingand characterizing partial discharges (PDs) has beenconstructed by NIST. The laboratory is equipped withseveral high-voltage sources and can study PDs originat-ing in a variety of insulation systems, including gases,liquids, and solids. Excitation voltages can be generatedfor sinusoidal test voltages up to 40 kV from 50 Hz to1000 Hz, as well as dc voltages of either polarity, alsoup to 40 kV. When equipment on order arrives, labora-tory capabilities will encompass arbitrary waveformswith amplitudes up to 120 kV and frequencies betweendc and 15 kHz. All sources are under computer controland monitoring. PD data is collected using both theNIST analog stochastic analyzer and the new NIST PDdigitizer. The latter allows continuous real-time mea-surement and recording on a computer diskette of theamplitude and phase of all PD pulses. The resulting datafiles are processed with custom stochastic analysis soft-ware to gain further insight into the PD phenomena.Comparison with the same analysis made independentlywith the analog system provides validation of the com-puter-based process. The new laboratory is already host-ing several projects. The U.S. Nuclear Regulatory Com-mission is supporting an investigation into using PD toevaluate the quality of low-voltage cables that have beenused in nuclear power plants, and the Air Force WrightLaboratory has contracted with NIST to design andfabricate a modified PD digitizer, as well as supply theneeded control and analysis software, for the testing ofPD at low air pressures. The lab also recently hosted aweek of PD testing in collaboration with a visitingscientist from the Instytut Elektrotechniki in Warsaw,Poland.

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NIST FACILITATES INTERNATIONALWORKSHOP ON ULTRA-SHALLOW PROFILESIN SEMICONDUCTORSThe Third International Workshop on the Measurementand Characterization of Ultra-Shallow Doping Profilesin Semiconductors was held recently in ResearchTriangle Park, NC, drawing over 130 participants. Theworkshop was sponsored by several organizationsincluding NIST. The topic of dopant profile measure-ment has long been important for process developmentand process monitoring. Rapid shrinking of devicedimensions, now requiring vertical junction depths of100 nm or less, has continually challenged the best ofprofiling techniques in one dimension. Now the needsfor accurate two-dimensional profiles on the part ofdevice designers, as articulated in the SemiconductorIndustry Association National Technology Roadmap forSemiconductors, and consequently on the part of thosewho develop computer-aided device design software,have added significant complexity to the challenge.There is concern that insufficient progress in dopantprofiling capability could be a show-stopper in meet-ing roadmap goals. The workshop featured four keynotetalks and an additional 47 papers and posters by authorsfrom ten different countries, in sessions on processmodel verification, electrical characterization, depthprofiling using sputter techniques to remove material,and electron and scanning-probe microscopies.Peer-reviewed versions of the workshop manuscriptswill be published in the January/February 1996issue of the Journal of Vacuum Science and Tech-nology B.

NIST TESTING MACHINING CENTERSFOR INDUSTRYNIST scientists have begun evaluating the NIST InterimTesting Artifact (ITA) for use in error diagnostics ofmachining centers. Originally developed for rapid in-terim testing of coordinate measuring machines, theITA may be used to characterize the performance ofnumerically controlled machine tools using touchprobes in place of the normal tooling. NIST personnelhave used the ITA in preliminary field testing at a privatecompanys large-scale composite fabrication facility.The tests involved three large machines which are usedfor final shaping of carbon fiber composite componentsthat are assembled to form the sound-suppression enginecasings for the new Boeing 777 twinjet commercialairliner. Data collected from the machines at the com-pany is electronically transmitted to NIST for process-ing and analysis. The types of machine errors that aredetected include those caused by temperature gradients,squareness and angular motions of the machines linear

axes, and errors in the calibration procedures andmechanical adjustments of the touch probes used. Thesetests will provide valuable baseline data on factory-floorapplications of the high-accuracy testing artifact andmay lead to routine machine tool interim testing as apart of standard quality control procedures.

NIST AND PRIVATE COMPANY COLLABORATEIN PRESENTING THE PRACTICALAPPLICATION OF SCANNED PROBEMICROSCOPYA NIST scientist presented a paper entitled Progress inAccurate Metrology of Pitch, Height, Roughness, andWidth Measurements Using an Atomic Force Micro-scope at the Society of Photo-Optical InstrumentationEngineers (SPIE) Microlithography Conference. TheNIST scientist and a private company scientist alsotaught a course on scanned probe microscopy tocommercial metrologists. The course was designed forcommercial metrologists who are interested in begin-ning and expanding their use of scanned probemicroscopy in a semiconductor environment. The scien-tists presented the calibration of commercial instru-ments as they relate to accuracy and repeatability andvarious technical operational practical issues that indus-try personnel, who use this new technology for processdevelopment and control, face. The private companyscientist provided information on the use of scannedprobe microscopy in a manufacturing environment.NIST provided the laboratory standards and calibrationperspective.

NISTS PARTICIPATION IN THE NEWLYLAUNCHED APPAREL RESEARCHNETWORK PROGRAMThe Defense Logistics Agency (DLA) recently haslaunched a 7-year R&D program to support the apparelindustry. The program is named the Apparel ResearchNetwork (ARN). The primary objective of ARN is tostrengthen the U.S. apparel industrys ability to meetDOD requirements through a program of research, edu-cation, industrial extension, and factory implementation.The goal of the ARN program is to get the uniform onthe customer at the right time, right place, right cost, andright fit. Through DLAs Broad Agency Announcement,the agency has selected 24 partners including educa-tional institutions, apparel manufacturers, equipmentsuppliers, and software developers. A special arrange-ment has been made to extend the partnership to includeNIST, the only non-DOD government agency involvedin the program. Three workshops have been held sincethe November 1994 kick-off meeting. The purpose ofthese workshops is to coordinate the process of the

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overall ARN technical strategy, in particular a roadmapof ARN, and management. NIST is actively involvedwith the development of the roadmap for ARN. It isexpected that a complete roadmap will soon be defined.Research projects then will be proposed and started.NISTs primary interests in ARN include integration,product data definition and exchange, and specialmeasurements.

X-RAY SPECTROMETRY IN ELECTRON BEAMINSTRUMENTSX-Ray Spectrometry in Electron Beam Instruments,edited by two University scientists and a NISTscientistand published in May, 1995 by Plenum Press, N.Y., isthe record of a topical symposium held by theMicrobeam Analysis Society in honor of a deceasedNIST scientist. The contributors include many of theworlds leading experts in the field of analytical x-rayspectrometry for microanalysis. The topics covered spanthe entire range of the field and include design ofsilicon-based energy dispersive detectors, detectorwindows, germanium-based detectors, modeling detec-tor response, special problems in low-energy x-rayspectrometry, digital pulse processing, multiple linearregression peak fitting, EDS detector artifacts, EDSdetector operation in the analytical electron microscopeenvironment, detector operation in ultra-high vacuumenvironments, wavelength dispersive x-ray spectrome-try, synthetic multilayer diffraction crystals, fittingwavelength dispersive x-ray spectra with NIST/NIHDesktop Spectrum Analyzer, and an evaluation of quan-titative analysis methods. This volume should provide animportant reference for practical x-ray microanalysisand should serve to stimulate discussion and research toadvance the state of the art in x-ray spectrometry.

NEW PUBLICATION FOCUSES ONANALYTICAL METHODS FOR CANCERCHEMOPREVENTIVE AGENTSNIST Special Publication 874, Methods for Analysis ofCancer Chemopreventive Agents in Human Serum, is acompilation of methods developed and critically evalu-ated at NIST for the measurement of selected vitamins,carotenoids, and other micronutrients in human serum.These compounds are under investigation world-widefor their efficacy in reducing the risk of developingcertain types of cancers. This reference manual wasestablished as a result of NIST efforts in providingconsultative services and analytical-measurementquality assurance for 50 laboratories that participate ina Micronutrients Measurement Quality AssuranceProgram co-sponsored by the National Cancer Institute.

This document serves as a means of transferring NISTmeasurement expertise to clinical laboratories involvedin epidemiological studies and clinical trials to establishthe cancer-preventive efficacy of these compounds.

WORKSHOP ON THE TREATMENT OFGASEOUS EMISSIONS VIA PLASMATECHNOLOGY HOSTED BY NISTA workshop on the use of non-thermal plasma technol-ogy for treatment of gaseous emissions was held March20-21, 1995 in Gaithersburg, MD. The workshop, sub-titled Present Status and Future Needs, was co-sponsored by NIST, Battelle Pacific Northwest Labora-tory, and the Strategic Environmental Research andDevelopment Program. Attendees were 120 scientistsand engineers from U.S. and foreign industrial, govern-ment, and academic laboratories.

The purpose of the workshop was to examine thecommon issues facing industry with regard to the use ofplasma chemistry and engineering for treatment ofgaseous emissions, and to evaluate the role of plasmatechnologies in meeting the demand for control andtreatment of gases with adverse environmental impacts.The workshop consisted of invited talks and breakoutsessions with particular focus on the status and needs forchemical data, predictive modeling, and device develop-ment as well as the cost and commercialization ofplasma technologies.

The workshop report now being generated willdescribe the potential applications, current status, andresearch and development needs which must beaddressed in order to accelerate the development ofplasma technology into commercial products useful forchemical processing and environmental cleanup andcontrol.

NIST PARALLEL APPLICATIONSDEVELOPMENT ENVIRONMENT (PADE)RELEASEDA major trend in high-performance computing ismessage-passing parallelism, in which independentprocessors work on parts of a common problem andcommunicate with each other by exchanging messagesover a network. Rapid growth of message-passing paral-lelism has been stimulated by the widespread use of asoftware package, PVM, with which an ordinary usercan connect any number of networked Unix work-stations to form a parallel virtual machine.

However, programming such a machine is a complextask, especially when it is made of workstations withdifferent file and operating systems. NIST scientists havewritten a software package to simplify this process. This

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software, the NIST Parallel Applications DevelopmentEnvironment (PADE), provides a virtual console, in theform of a graphical interface program running on asingle workstation, which utilizes a parallel makeutility to support all phases of parallel application devel-opment: editing, compilation, execution, debugging,and performance monitoring.

NANODETECTOR PRODUCES FIRST IMAGESThe nanodetector, a unique EUV/x-ray microscopefor high-resolution imaging, has produced its firstimages. This instrument converts an EUV or x-rayimage into a photoelectron image which is then magni-fied by a low-energy electron microscope. In one modeof operation, a sample is placed on the transmissionphotocathode membrane (the element that converts thex-rays to electrons) where differential absorption by thevarious structures of the sample causes varying amountsof EUV to be transmitted to the underlying photo-cathode surface. A magnified image of the resultantphotoelectron shadowgraph of the sample is thenprojected onto a phosphor screen which is viewed by aCCD camera to give essentially real time viewing of thesample. When fully operational, the microscope shouldbe capable of resolving structures as small as 20 nm, thepresent state-of-the-art for x-ray microscopy. The nan-odetector was designed for several measurement appli-cations. One is soft x-ray biological microscopy, arapidly growing field where the advantages over elec-tron microscopy are less sample preparation and lessdamaging radiation. Another application is high-resolu-tion compositional mapping of nanostructures, espe-cially nonconductors where electron microscopytechniques are hampered by charging effects. A thirdplanned application employs the use of x-ray magneticdichroism as a contrast mechanism for the mapping ofmagnetic domains with both elemental and spatialresolution.

CRADA SIGNED WITH PRIVATE COMPANY TOSHARE PARALLEL COMPUTING SOFTWARENIST has signed a CRADA with a private companyto share parallel computing software. The NISTresearchers will develop a new set of computer codes tocalculate atomic wave functions using parallel comput-ers. The company will provide access to their parallelcomputers and new mathematical software specificallydesigned for parallel computing. Algorithms developedand results obtained by the NIST researchers will beincorporated into the molecular wave function codes thecompany is developing for applications to complexmolecules and catalysts. The atomic structure codes to

be developed by the NIST scientists will provide predic-tive capabilities far superior to any existing computercodes. They will be used to predict transition probabili-ties and collision cross sections of heavy elements usedin mercury-free fluorescent lamps, fusion plasmadiagnosis, x-ray lasers, magnetic materials, pollutiondetectors, and catalysts. The atomic theory groupalready has succeeded in reducing the computing timeof one of their codes by a factor of 10 using 15 nodeson NISTs SP2 computer.

NIST AND THE COUNCIL ON IONIZINGRADIATION MEASUREMENTS ANDSTANDARDS HOST WORKSHOP ON RADIATIONPROTECTIONNIST and the Council on Ionizing Radiation Measure-ments and Standards (CIRMS) jointly sponsored aworkshop held at NIST March 1-2, 1995. The purposeof this workshop was to review the status of the NISTNational Voluntary Laboratory Accreditation Program(NVLAP) for personnel protection dosimetry, particu-larly in view of recent revisions of the American Na-tional Standard for Personnel Dosimetry PerformanceCriteria for Testing (ANSI N13.112 1993). A NISTscientist participated in the development of the currentrevisions to this standard and has advised NVLAP ontheir implementation.

More than 20 participants discussed the impact of therevised standard and the new direction being pursuedboth by the NVLAP and by the Department of EnergyLaboratory Accreditation Program. The dosimetry forall U.S. radiation workers is traceable to NIST throughone of these two programs. Representatives from thetwo programs administration and performance testinglaboratories attended, along with representatives fromgroups directly affected by the programs, such as theNuclear Regulatory Commission, the nuclear power in-dustry, and personnel dosimetry service companies. Theworkshop also included discussion of anticipateddosimetry performance issues, including extremitydosimetry testing and electronic dosimetry testing. Theconvening of those who set the standards, those whoadminister them, and those who use them resulted in ahighly constructive workshop.

PHOTONIC FILMSSingle crystal electro-optic films have potential applica-tions in miniaturizing future photonic telecommunica-tion and image-processing systems. Because of its largeelectro-optic coefficient, barium titanate is an importantelectro-optic material. Devices fabricated from bariumtitanate, such as optical switches and modulators, could

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be made much smaller than current commercial devicesmade from lithium niobate. However, success in produc-ing single crystal barium titanate films has been limitedto date. A milestone to success is the deposition ofepitaxial barium titanate on other inexpensive singlecrystal substrates.

NIST scientists succeeded in depositing by thermalmetal-organic chemical vapor deposition, state-of-the-art barium titanate thin films epitaxially onto singlecrystal magnesium oxide substrates at 600 8C, a temper-ature at least 200 8C lower than that reported by otherinvestigators. The advantages of depositing at a lowertemperature are better compatibility with standardsilicon device processing technology, less interdif-fusion with the substrate, and lower concentrations ofthermally activated defects. All of these factors are crit-ical to developing thin film electro-optic photonicdevices.

WORKSHOP ON MATERIALS PROPERTYMEASUREMENTSA workshop to identify technology gaps in detecting thedegradation of materials used in electric power genera-tion was conducted by NIST in cooperation with theDepartment of Energy and the Electric Power ResearchInstitute (EPRI) at the EPRI NDE Center in Charlotte,NC, April 11-13, 1995. Since 80 % of the electric powerused in the United States comes from fossil fuel plantsthat expose materials to high temperatures in corrosiveenvironments for long periods of time, the detection ofgeneralized degradation and the prediction of remaininglife have potential to reduce maintenance and operatingbudgets. These same problems also appear in oil re-fineries, chemical processing plants, and paper mills.The workshop concluded that three areas of researchneed to be addressed: (1) the detection and characteriza-tion of void clusters and microcracks during the earlystages of creep, stress corrosion, and fatigue; (2) themeasurement and monitoring of stress distributions; and(3) the development of non-destructive tests for suchmechanical properties as fracture toughness, hardness,and ultimate tensile strength.

X-RAY DIFFRACTION IMAGING OF ZnSeSUBSTRATES FOR BLUE-GREEN LEDsThe commercial application of ZnSe depends on theability to grow high-quality crystals as substrates for thegrowth of device heterostructures. A private company,a grower of ZnSe crystals, has been collaborating withNIST to characterize single-crystal substrates to relategrowth conditions and processing parameters to defect

generation. The ultimate goal is to improve crystalperfection and, therefore, the yield of device material.

Using synchrotron-radiation diffraction imaging,NIST scientists have observed defects in ZnSe crystalssuch as subgrain boundaries, inclusions, inhomoge-neous strain, and residual subsurface damage. Surfacereflection images show a texture which is directlyrelated to the bulk defect density. Subsurface damageresults from the processing of wafers from the as-grownboule and chemo-mechanical polishing produces anorange peel texture in the microstructure. Imagesfrom the best crystal allowed NIST scientists to countindividual dislocations. The measured defect density,between 640/cm2 and 1300/cm2, compares favorablywith other compound semiconducting materials. Thedevelopment of prototype green LEDs on undopedsubstrates has allowed verification of the relationshipbetween substrate quality and device lifetime.

THERMAL BARRIER COATINGS WORKSHOPOn March 28-29, 1995 NIST, NASA, and DOE coorga-nized and sponsored a two-day workshop on the statusof ceramic thermal barrier coatings (TBCs). The objec-tive of the workshop was to benchmark the status ofthese materials through invited presentations by indus-trial, academic, and government researchers; proces-sors; and designers. More than 200 attendees partici-pated and proceedings will be issued. Following theworkshop, government and industrial sponsors and par-ticipants in research and development involving thesematerials formed an interagency working group for thepurpose of exchanging programmatic information.Yearly meetings of the interagency group are planned.The next TBC workshop will be held in 1997.

NIST WORK FEATURED AT AUTOMOTIVECONFERENCEThe Liquid Composite Molding program at NIST wasfeatured at the ASM/ESD International Advanced Com-posites Conference and Exhibition in Detroit, MI. Areport of the conference in the February issue of PlasticsTechnology highlighted NIST advances in on-lineprocess control and in-mold monitoring. Sensors forin-mold monitoring are important to the development oflarge liquid molding processes because real-time flowand cure information is essential to understand and con-trol the process. NIST scientists developed a fluores-cence sensor based on evanescent wave fiber optics tomonitor the flow and cure of resin in a mold. The NISTsensor simplifies the process interface to a single opticalconnection, while still providing sensor informationfrom various locations throughout the mold.

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According to the Plastics Technology article, the lackof on-line process control is identified as one barrier toimplementation of liquid composite molding in demand-ing, higher-volume applications areas, such as automo-tive parts. The aim of the NIST on-line process controlwork is to develop a control methodology capable ofrelating processing parameters such as resin flow,viscosity, cure rates, temperature, and pressure to finalpart properties. The approach incorporates a model-based high-level control system. The model-basedcontroller is divided into an off-line component, inwhich the intensive non-linear computations areperformed, and an on-line component that performsonly linear computations or table lookup operations. Inaddition, a neural network-based control system also isunder investigation at NIST.

THERMAL BEHAVIOR OF POLYMERULTRATHIN FILMSNIST Scientists report the first observations of thethermal properties of an ultrathin polymer film that isstrongly attached to a substrate. Ultrathin polymer filmsdeposited on dissimilar materials are a common featureof integrated circuits where they provide electrical insu-lation. Thus far, designers of microelectronic devicesrely on materials data obtained from bulk propertymeasurements even though it is suspected that the prop-erties of materials in the size scales in actual productsmay differ from those of the bulk. Of particular interestto designers is the thermal expansion behavior of poly-mers. The high thermal expansion of polymers as com-pared to those of silicon or metals may lead to debond-ing during thermal excursions.

Scientists were able to show from x-ray reflectivitymeasurements that when the polymer has a strongchemical affinity for the surface, as with poly-(2)-vinylpyridine on acid-cleaned silicon, then the polymerat the surface responds differently to temperature thanthe rest of the material. It is found that the coefficient ofthermal expansion decreases with decreasing film thick-ness to a minimum value at thicknesses of approxi-mately 20 nm. This corresponds to the physical dimen-sion of an isolated polymer molecule. The results implya region near the interface where the thermal expansionis significantly smaller than the rest of the film. Thisfinding shows that the mismatch of coefficients ofthermal expansion at the interface between dissimilarmaterials is altered by the forces of attraction betweenthe materials. Such phenomena are important to con-sider in computational models used to predict thestresses which develop in electronic packages whensubjected to temperature change during manufactureand use.

THERMAL DIFFUSIVITY MEASUREMENTSIN MULTILAYER THERMAL BARRIERCOATINGSThe high thermal resistance of interfaces in multilayerthin films permits the design of ultrathin, ultralightthermal barrier coatings that are better insulators thaneither of the material components used. To make a quan-titative determination of the effectiveness of multilayersas thermal barriers, NIST scientists have developed alaser flash system for measuring their thermal diffusivi-ties at sample temperatures from 1000 8C to 2500 8C,simulating the high temperature environment encoun-tered in commercial applications. A Q-switchedlaser pulse and fast electronics give a response time ofless than 1 ms , permitting the study of thermal barriercoatings that are only micrometers thick.

NSF RENEWS SUPPORT FOR THE CENTERFOR HIGH RESOLUTION NEUTRONSCATTERINGThrough a 1989 cooperative agreement establishing theCenter for High Resolution Neutron Scattering(CHRNS) at NISTs Cold Neutron Research Facility(CNRF), the National Science Foundation has sup-ported, for use by the general scientific community, thedevelopment and operation of two state-of-the-art neu-tron scattering instruments with broad application inmaterials research. The CHRNS comprises a 30 m,high-resolution, small-angle neutron scattering (SANS)instrument, for the characterization of nanoscale struc-ture in a wide range of materials, and a spin polarizedinelastic neutron scattering (SPINS) spectrometer, apowerful probe of low-frequency dynamical processesin condensed matter. Over 150 visiting scientists haveused the CHRNS SANS instrument in its nearly 2 yearsof operation, making it the most heavily utilized instru-ment at the CNRF by visiting researchers.

The NSF recently completed a thorough review of theprogress of the CHRNS and, as a result, has agreed tocontinue and expand its support. Under the terms of anew, 5 year cooperative agreement, the NSF will con-tinue to provide support for the staff and equipmentneeded to operate the SANS and SPINS instruments asuser-oriented facilities, and will, in addition, provideone-half of the support required to build and operate anew double perfect crystal diffractometer (DCD) forvery-high-resolution SANS. The DCD will extend theupper size limit of the 30 m SANS instrument by morethan one order of magnitude, to nearly 10 mm, toprovide overlap and complementarity with optical tech-niques. Up to 75 % of the beam time on the CHRNSinstruments is allocated based solely on the scientificmerit of submitted proposals that undergo external peerreview.

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NIST DEVELOPS NEW METHOD FORMEASURING REFRIGERANT FLAMMABILITYUnder sponsorship of the Air Conditioning and Refrig-eration Technology Institute and the U.S. Department ofEnergy, a NIST team has developed an improved ap-proach to determining the flammability properties ofpotential alternative refrigerants. Commonly used, non-flammable chlorofluorocarbons are no longer accept-able due to their deleterious effect on stratosphericozone. In the search for replacements, some of thecandidates pose a potential fire hazard. Both theinvolved industries and the U.S. Government recognizedthe need for reliable determination of the ignitability ofa refrigerant that has leaked into the ambient environ-ment. A recent study showed that the conventional testmethod, ASTM E-681, is subject to excessive variationand some risk of explosion. NIST scientists, and astudent at the University of Maryland have shown thatan alternative approach can reduce the variation whileproviding for easier measurement of the key property,the lean flammability measurement. In ASTM E-681, aclosed vessel is filled with a refrigerant/air mixture.Following generation of a central spark, the testerobserves whether a flame propagates to the wall of thevessel. The new method uses a premixed, opposed-flowdiffusion flame. Two jets of premixed refrigerant (orany other fuel) and air are directed at each other, form-ing a stagnation plane with twin flames on either side.The fundamental ignition properties of the refrigerantare the lean and rich flammability limits at zero flamestrain, i.e., the lowest and highest flame-propagatingconcentrations of refrigerant in air in a totally quiescentenvironment. One cannot establish a zero strain rateflame, so the limits at various measured strain rates areextrapolated to zero. The flames strain rate is varied bychanging the flow velocities. The method safely pro-duces flammability limit data that is unambiguous andof reduced uncertainty. Continuing work will reduce theuncertainty further, refine the apparatus and procedure,and minimize the amount of refrigerant needed for thedetermination.

NIST PARTICIPATES IN DEVELOPMENT OFREMOTE DATABASE ACCESS STANDARDNIST has been active for a number of years in the devel-opment of the International Standard for Remote Data-base Access (RDA), ISO/IEC 9579:1993. The standardis a foundation for building a logically integrated data-base of diverse data stored in geographically separateddata banks under the management and control of hetero-geneous database management systems. With the RDA

standard and its associated specialization for DatabaseLanguage SQL, ISO/IEC 9075:1992, diverse data man-agers are able to communicate with one another andprovide shared access to data and data operations andmethods under appropriate security, integrity, andaccess control mechanisms

To encourage commercial development of RDAimplementations, NIST joined with the U.S. NavalResearch and Development Laboratory (NRaD), andothers, to establish an RDA Testbed at NIST. Majorgoals of this testbed are to demonstrate RDA interoper-ability of a wide variety of client and server products, toincorporate solutions over both Open Systems Intercon-nection (OSI) and Internet communications transportmechanisms, to provide technical solutions for applica-tion areas, to demonstrate the integration of legacy datainto modern data management applications, and todevelop proposed implementor agreements in areasbeyond the scope of the formal standards.

To achieve these goals, NIST is building on NRaDsresearch and development work for the DistributedQuery Processor (DQP), the RDA Client, and the RDAServer. Building on NRaDs research work saved at least3 years in bringing RDA to fruition. Additionally, havingaccess to NRaDs Server node on the West Coast fromNISTs Client node on the East Coast, NIST can show tomany potential RDA users the value of real-time inter-operability. To date, NIST has demonstrated RDA tomore than 40 industry organizations, government agen-cies, academic institutions, and industry consortia.

SECRETARY OF COMMERCE APPROVESFEDERAL INFORMATION PROCESSINGSTANDARD (FIPS) FOR DOCUMENTAPPLICATION PROFILEFIPS 194, Office Document Architecture (ODA) RasterDocument Application Profile (DAP), has beenapproved for federal agency use. FIPS 194 adopts theInternational Organization for Standardization (ISO)/International Electrotechnical Commission (IEC)12064-1 International Standard Profile (ISP) FOD112,Open Document Format: Image ApplicationsSimpleDocument StructureRaster Graphics content architec-ture, Part 1: Document Application Profile (DAP). TheFIPS adopts a functional profile or DAP which is asubset of the ODA standard. The DAP was initiated byan ad hoc task group for the Continuous Acquisition andLife Cycle Support (CALS) program. Effective Sept. 1,1995, FIPS 194 will enable federal agencies to exchangeformatted structured documents between systemsdesigned for raster graphics applications.

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NEW PUBLICATION LOOKS ATOBJECT-ORIENTED TECHNOLOGYNISTIR 5600, Object-Oriented Technology ResearchAreas, discusses some of the issues surrounding objecttechnology, including object-oriented developmentmethodologies, measuring the quality of object-orientedsoftware, testing, the use of object-oriented technologyin high-integrity systems, and distributed object com-puting. The report identifies research topics in object-oriented technology for NIST.

INFORMATION SECURITY TRAININGATTRACTS LARGE FEDERAL AUDIENCEOn March 29-30, 1995 NIST co-sponsored the Invita-tional Workshop on Information Technology (IT)Security Techniques and Tools for Government Informa-tion Technology Services. Co-sponsors includedDefense Information Systems Agency, General ServicesAdministration, Government Information TechnologyServices Working Group, and National Communica-tions System. More than 200 federal participantsattended the workshop.

The goal of the workshop was to assist agencies inmeeting their current information technology securityrequirements by facilitating the exchange of informationamong agencies regarding solutions to the securitychallenges they face. Sessions ranged from the Office ofManagement and Budget presentation outlining the revi-sions to OMB Circular A-130 to the Central IntelligenceAgency briefing on implementing Lotus Notes in asecure environment. NIST presentations included fire-walls, an overview of the Forum of Incident ResponseTeams (FIRST), the use of standards in acquisitions, anupdate on the Computer Security Resource Clearing-house, and the upcoming publication of the NISTSecurity Handbook. Several agencies also demonstratedsecurity products or tools they were implementing.NIST demonstrated the Computer Security ResourcesClearinghouse and an implementation example of adigital signature.

NVCASE PUBLIC WORKSHOP HELDThe Office of Standards Services held a public work-shop on the National Voluntary Conformity AssessmentSystems Evaluation (NVCASE) Program on March 9 todescribe the operation of the program and to obtainpublic input regarding the development of generic crite-ria for evaluating applicants.

NIST proposed use of ISO/IEC documents, e.g.,Guides 25 and 58, for laboratory accreditation applica-tions; draft CASCO 226 and 227 for quality systemregistration applications; and draft CASCO 226 and 228for product certification applications. The 40 workshop

participants generally agreed with these proposals.Copies of the CASCO documents were distributed, andcomments regarding implementation were requested.

To date, four organizations have requested evaluationunder NVCASE: the American National StandardsInstitute (ANSI) applied for recognition of its productcertification accreditation program for selected indus-trial sectors; ANSI also requested recognition for itsjoint program with the Registrar Accreditation Board asan accreditor of quality system registrars; the AmericanAssociation for Laboratory Accreditation applied forrecognition as an accreditor of testing laboratories forEMC and telecom terminal equipment; and the NationalMarine Manufacturers Association requested NVCASEaccreditation as a certification body for recreationalboats and accessories. These applications are being pro-cessed, including consideration of public comments.

CALIBRATION ACCREDITATIONThe National Voluntary Laboratory AccreditationProgram (NVLAP) has issued its first certificates andscopes of accreditation under its new CalibrationAccreditation Program (CALLAB). The following labo-ratories were accredited as of April 1: the GeorgiaDepartment of Agriculture Weights and MeasuresLaboratory, accredited for mass and volume; the OakRidge Metrology Center, accredited for step gages andend gages using a coordinate measuring machine; RiceLake Weighing System, accredited for mass; and theSouthern California Edison Metrology, accredited forDC voltage and mass. Two laboratories previouslyaccredited under the NVLAP Secondary CalibrationIonizing Radiation Program were accredited underCALLAB. They are the Center for Devices and Radio-logical Health X-Ray Calibration Laboratory and thePacific Northwest Laboratory, each accredited forIonizing Radiation.

CRYPTOGRAPHIC MODULE VALIDATIONThe National Voluntary Laboratory AccreditationProgram has announced a program to accredit indepen-dent third-party laboratories to test cryptographicmodules. NIST and the Communications SecurityEstablishment of the Government of Canada have devel-oped a conformance test method to validate products toFederal Information Processing Standard (FIPS) 140-1,Security Requirements for Cryptographic Modules.Products found to conform to the standard will beaccepted for use both by U.S. federal agencies and theCanadian government for the protection of sensitive,unclassified information. Details about the NISTCryptographic Module Validation Program are availablefrom NIST.

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PATENT ISSUED ON THE APPLICATION OFARRAYS OF MINIATURE HOTPLATESTO MATERIALS PROCESSINGNIST scientists have been awarded a second patent num-ber (5,356,756, Application of Microsubstrates forMaterials Processing) relating to the design, manufac-ture, and use of arrays of miniature hot plates, originallydeveloped to test infrared imaging systems. NISTscien-tists collaborated to develop miniature devices capableof analyzing chemical mixtures. The devices are manu-factured by standard complementary metal oxide-semi-conductor foundry techniques, which allow the produc-tion of a range of devices that have improved sensingperformance. The last etch step is carried out locally.

The patent describes a procedure to use an array ofminiature hotplates to separately, but simultaneously,process deposited films. The key to the wide range ofpotential applications is that the temperature of eachhotplate can be controlled separately both in an initialfilm deposition step and later in use (for example, as asensor for a specific gas). Properties of the film ele-ments may be measured using electrical contact pads.The array of processed films may be used for sensors,electronic devices, greatly accelerated materials devel-opment processes, and solid-state physics, biology, andchemistry studies.

LATEST GAGE BLOCK CALIBRATIONSYSTEM AT NISTA NIST scientists successfully completed a new calibra-tion system for the NIST Gage Block Laboratory. Theuser-friendly system allows NIST laboratory personnelto routinely carry out a substantive measurement assur-ance program using efficient and practical stand-alonePC-based workstations for all NIST reference standardmaster gage blocks. With present measurement designs,typical uncertainty estimates for steel gage blockcalibrations by mechanical intercomparison are 25 nmfor gage block sizes shorter than 50 mm and between28 nm to 122 nm for sizes 50 mm through 500 mm.These figures reflect a steady reduction over past yearsand are in part a direct result of improved and frequentsurveillance of the complete NIST gage block calibra-tion history. The new system continues to use a specialdatabase and exclusive analysis software to record andmonitor customers gage block measurement histories,reduce risks of reporting inaccurate measurements, andimprove complete measurement confidence.

NIST ASSERTS NEW APPROACH TO UNIFYINGROCKWELL HARDNESS STANDARDSAn ISO Technical Committee meeting on Rockwellhardness standards (ISO/TC164/SC3) was held March28-29, 1995 at NIST. Two NIST scientists were invitedto attend as non-voting delegates. The delegates visitedthe NIST Rockwell hardness calibration laboratory, aswell as the NIST surface and microform calibrationlaboratory. A round-table discussion on the strategy ofunifying international Rockwell hardness standards wasalso held on March 27 before the committee meeting. Inthat discussion, a NIST scientist pointed out that theunified European Rockwell Hardness Standard Scale isa performance-based standard system with thefollowing disadvantages: it does not have traceability tofundamental metrology; and it has an unknown system-atic offset with respect to a properly definedRockwell hardness scale.

The NIST approach of establishing a Metrology-Based Standard System to unifying internationalRockwell hardness standards also was introduced.According to the NIST approach, the properlydefined scale is established through fundamentalmetrology. The metrology-based Rockwell hardnessreference standards include a standard dead-weighttesting machine (developed by the Instituto di Metrolo-gia G. Colonnetti, Italy, and in operation at NIST)and a standard class of Rockwell diamond indenters,which are more tightly controlled for dimension andform than previous classes of such indenters. Theseindenters are to be measured with a high-accuracymicroform calibration system, such as the one developedat NIST. Their uncertainties are established throughprocedures recently developed at NIST. The testingmachine and the indenters are used to create, maintain,and reproduce the Rockwell hardness scale and to unifythe international Rockwell hardness standards.

The response to the NIST approach was positive.It was suggested that a subcommittee be formed toinvestigate the NIST approach. In addition, extensivetesting of the microform and the performance of severaltypes of indenters, including those from Italy, Germany,Japan, and the United States, was initiated during themeeting. A research paper entitled A MetrologyApproach to Unifying Rockwell Hardness Standardsby three NIST scientists has been accepted by theInternational Hardness Conference to be held inGermany in November 1995.

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FIRST TECHNICAL MEETING OFCOMPUTER-AIDED MANUFACTURINGFORUM HELDThe Computer-Aided Manufacturing EngineeringForum held its first technical meeting in Gaithersburg,MD March 21-22, 1995. The focus of the meeting wasa review of requirements for the Navy-sponsoredManufacturing Engineering Tool Kit (METK) project.The METK will integrate commercial product datamanagement, process planning, and manufacturingsimulation systems. The technical focus of the project isvalidating engineering data using simulation.

Working sessions at the forum meeting prioritized themachines and processes to be included in a simulatedmachine shop, specified types of errors that most oftenoccur in engineering data, and identified mechanismsfor detecting and correcting errors. A draft proceedingsof the meeting has been prepared and will be publishedas a NISTIR.

INTERNATIONAL COMPARISON OFHUMIDITY STANDARDS AT NISTIn collaboration with the Instituto Nacional de TecnicaAeroespacial (INTA) of Spain, NIST has begun an inter-national comparison of humidity measurement stan-dards. A representative of INTA, the Spanish agencydevoted to aerospace research and technological devel-opment, visited NIST for preliminary comparison ofstandards in anticipation of the intercomparison for theEuropean Union (EU) region.

A precision optical dew-point hygrometer, providedby INTA for use as a transfer standard for the EU region,was calibrated in the NIST Two-Pressure HumidityGenerator, which is currently the NIST humidity cali-bration standard for dew-points in the range from 70 8Cto 40 8C. This INTA hygrometer, with repeatabillity ofbetter than 60.01 8C, was previously calibrated in theNational Physical Laboratory (NPL) Two-TemperatureHumidity Generator in Great Britain. For dew-pointsabove 20 8C, the NIST and NPL calibrations are inexcellent agreement, with discrepancies in dew-pointtemperature no larger than 0.03 8C. In this range theexpanded uncertainty of the NIST standard is 60.04 8Cwhile that of the NPL standard is 60.06 8C. For dew-points below 20 8C, the discrepancy between the NISTand NPL calibrations increases to a maximum of0.25 8C at 70 8C, where the expanded uncertainty ofthe NIST standard is 60.10 8C while that of the NPLstandard is 60.11 8C. Since this discrepancy is not ex-pected to be associated with the transfer standard, thereis a strong motivation for further testing and intercom-parisons.

As part of the current phase of the internationalomparison of humidity standards, comparisons usingthe INTA instrument will be conducted among the EUnational laboratories of Germany, France, Italy, theNetherlands, and Spain. In the North American region,NIST will provide a precision dew-point hygrometer foruse as a transfer standard for comparisons in Canadaand the United States. In the Asian-Pacific region, anintercomparison is being organized with the nationallaboratories of China, Hong Kong, Japan, Korea,Malaysia, New Zealand, Singapore, Taiwan, andThailand. A dew-point hygrometer from Singapore willbe used as a transfer standard. The second phase of theintercomparison will be the testing of the three regionalinstruments at NIST.

SYNTHESIS AND IN SITUCHARACTERIZATION OFSUPERPARAMAGNETICNANOCOMPOSITES FROM VAPOR PHASECONDENSATION IN A FLAMERecent work on the magnetic characteristics of nanome-ter-scale materials has suggested that such materialshave novel properties which vary with size. In particu-lar, magnetically isolated nanometer magnetic particlesshow superparamagnetic behavior rather than the ferro-magnetic behavior found in bulk. Such behavior hasbeen demonstrated to be important for magnetic refrig-eration applications. Because of expensive productiontechniques, it is desirable to find a single method thatnot only synthesizes these materials in sufficient quanti-ties for study but also allows the isolation of the mag-netic particles from each other via encapsulation withina non-magnetic host.

To this end NIST has investigated application of flamegrowth technology for the synthesis of this class of ma-terials. A pre-mixed methane/oxygen flame dilutedwith nitrogen is used as the reacting environment inwhich iron carbonyl and hexamethyldisiloxane is addedas the magnetic and nonmagnetic precursor materials.The regulation of the combustion process enables thecontrol of the morphology and chemical composition ofthe resulting composite particles so that:

Nanometer composite particles are formed contain-ing 5 nm to 10 nm Fe3O4/g-Fe2O3, encased in asilica particle whose diameter ranged from 30 nm to100 nm depending on loading and flame tempera-ture.

The iron oxide clusters are magnetically isolated andshow superparamagnetic behavior.

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In-situ characterization of both vapor phase species aswell as the particle phase has been conducted using 2-Dlaser-induced fluorescence and MIE imaging in order tobetter understand how to control the process.

The results indicate that particle nucleation of theironand silicon components occurs independently,which allows for the formation of the encapsulationprocess.

COMPUTATIONAL THERMOCHEMISTRY OFSix Hy Oz REACTIONSScientists at NIST have produced the first set of datausing ab initio molecular orbital calculations for morethan 60 silicon-oxy-hydride species and transition statesfor reactions important to silane combustion and chemi-cal vapor deposition of SiO2 in the semiconductor man-ufacturing industry. Geometries, vibration frequencies,and heats of formation for both equilibrium and transi-tion state species have been obtained using a bond addi-tivity corrected procedure to calibrate molecular orbitalcalculations. The correction procedure allows the use ofa lower level of ab initio theory, necessary to obtain alarge body of data, while still obtaining the neededaccuracy. Furthermore, this new approach allows asystematic generation of a self-consistent set of thermo-chemical and kinetic data when no substantial experi-mental data are available. From the calculated transitionstate properties, rate expression for some 40 reactionshave been derived from well-known master equationsolutions. The derived thermochemistry and kineticsform the basis from which a comprehensive detailedchemical kinetic model may be built for subsequentreactor simulations.

ROLE OF RADIOCARBON MEASUREMENTTECHNOLOGY IN MEETING URBAN AIRQUALITY STANDARDSUrban areas in the United States that fail to meet theNational Ambient Air Quality Standards (NAAQS) arerequired by the Clean Air Act to implement controlstrategies. A common approach to identifying sourcesof ambient pollutants is to study their spatial and tempo-ral distributions and compare these concentrations tosource profile concentrations using various modelingtechniques. The models used to estimate the impact ofemission sources on ambient air quality generally relyon assumptions and must be tested and validated. Radio-carbon analyses provides definitive data for evaluatingcarbon models that rely heavily on chemical informationand/or surrogate tracer species only. Over the past 2decades, NIST has been a leader in advancing the stateof separation science and radiocarbon isotopic measure-ments using accelerator mass spectrometry on small

(sub milligram) environmental samples to discriminatequantitatively fossil from contemporary carbon.

Recently, NIST researchers have applied radiocarbonmeasurement technologies to assist local municipalitiesin quantifying major carbonaceous pollutant sourcesduring episodes when carbon monoxide concentrationsand aerosol exceeded their respective NAAQS. Thesestudies included: (1) carbon monoxide concentrations inAlbuquerque, NM, where mandatory no-woodburningdays had been implemented as a CO emission controlstrategy; (2) wintertime sources of PM10 aerosol inDenver, CO, which in 1992-1993, 1995 had failed tomeet the NAAQS for the first time since 1987; and (3)14C characterizations of primary sources that contributegreater than 80 % of the ambient carbon aerosol massin Los Angeles.

Radiocarbon results for the Albuquerque study indi-cated that fossil CO was the dominant source of ambientCO, and in Denver that fossil carbon was the dominantsource of carbon. In Los Angeles, emission inventoriesconstructed based on 14C measurements indicated thatseveral anthropogenic sources, e.g., fireplaces andcharbroilers, emit significant quantities of contemporarycarbon. These data, combined with meteorological data,were used to evaluate an atmospheric transport model.Overall consistency between model predictions andambient 14C measurements was demonstrated. Resultsof these studies will be used by state and local agenciesresponsible for developing future emission control plans.

EIGHTH ANNUAL WORKSHOP ONSECONDARY ION MASS SPECTROMETRYThe 8th Annual Workshop on Secondary Ion MassSpectrometry (SIMS) was held in Lake Harmony, PA,May 7-10, 1995. This yearly workshop is organized byNIST, the Naval Research Laboratory, and the ArmyResearch Laboratory. This year the workshop was at-tended by close to 100 SIMS researchers from theUnited States, Canada, and Europe.

The first day of the meeting was devoted to invitedtutorial presentations given by noted experts on variousaspects of SIMS and related techniques. Topics includedmolecular dynamics simulations of sputtering, ioniza-tion effects, semiconductor characterization, isotope ra-tio analysis, biological analysis, organic analysis, ionsource design, and the use of focused ion beam systemsfor materials characterization. The second day of theworkshop was devoted to new developments in SIMSinstrumentation, which included sessions on instrumen-tal repair and troubleshooting and tutorials on instru-ment operation. The final day of the meeting wasdevoted to contributed presentations on various aspectsof SIMS, including isotopic ratio analysis, laser post-

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ionization, semiconductor characterization, and analysisof organic molecules. It was announced at this meetingthat the organizers of the SIMS Workshop would behosting/organizing the 11th International Conference onSIMS to be held in 1997 at a site as yet to be deter-mined.

WORKSHOP ON INFRAREDMICROSPECTROSCOPY WITHSYNCHROTRON RADIATION SOURCESInfrared microspectroscopy has become a widely usedanalytical technique for determining the chemical com-position of small samples and for elucidating the rela-tionship between chemical properties and microstruc-ture of materials. The technique involves thespectroscopy of very small samples using an infraredsource of radiation, a low-resolution Fourier transformspectrometer, and an infrared microscope. Severalthousand infrared microscopes are in use around theworld, in forensic and pathological analysis, mineralogy,polymers science, and many other applications.Synchrotron radiation can be several orders of magni-tude brighter than the conventional sources used forinfrared microscopy. Recent work at the NationalSynchrotron Light Source (NSLS) has shown that thishigher brightness can be achieved in a standard commer-cial microscope interfaced to a synchrotron beamline.

The surge of interest in this approach led NIST tosponsor a one-day workshop on infrared microscopywith synchrotron radiation, May 4, 1995, with the goalof gauging interest by the user community in a micro-scope facility at the NIST SURF II Synchrotron Ultravi-olet Radiation Facility. The workshop drew a diversemix of 50 participants, with representatives from privateindustry and Government agencies among others. Inde-pendent studies reported by NIST and by NSLS indi-cated that SURF II has excellent prospects as a infraredsource for microspectroscopy. The workshop resulted inthe formation of a users group that will provide input tothe design of a microscope facility at SURF II; thisgroup also was offered a block of beam time at theNSLS facility so that its members can accumulate expe-rience in working at a synchrotron facility.

OCEAN RADIOMETRY WORKSHOP AT NISTOn May 3-10, 1995 NIST and the National Aeronauticsand Space Administration co-hosted the fourthSeaWiFS Intercalibration Round-Robin Experiment(SIRREX-4). SeaWiFS (Sea-viewing Wide Field-of-view Sensor) is an ocean color radiometer that willlaunch in the near future with a five-year mission to

determine the water-leaving radiances and chlorophyll-aconcentrations in the worlds oceans. The accuracy ofthe results are critically dependent on the accuracy ofmultiple in situ field measurements. This year SIRREXfocused on the techniques and procedures NIST uses tocalibrate and characterize radiometric artifacts (princi-pally lamps, spheres, and plaques). Presentations madeby NIST scientists were organized as lectures that set thestage for afternoon practicals.

Other presentations laid out the requirements of sev-eral national and international ocean color projects. Inaddition to SeaWiFS, scientists associated with the U.S.moderate resolution imaging spectroradiometer, theGerman marine optical spectroradiometer, the Japaneseocean color temperature sensor, the European mediumresolution imaging spectrometer, and the Taiwaneseocean color imager projects briefed the participants ontheir individual projects and calibration requirements.Scientists working in the field projects in support ofthese missions, e.g., the Pan-European investigationsinto calibration of atmosphere and sea surface opticsand the Plymouth atmospheric correction experimentalso presented their plans and current capabilities.

CRADA INVESTIGATES RADIATIONENGINEERING FOR ENVIRONMENTALCLEANUPUnder a Cooperative Research and Development Agree-ment between NIST and the University of MarylandDepartment of Materials Science and Nuclear Engineer-ing, NIST scientists are using the Medical-IndustrialRadiation Facility (MIRF) to investigate the feasibilityof electron-beam treatment of wastes and environmentalcontaminants. With support from the EnvironmentalEngineering Division of the National Science Founda-tion, the University of Maryland is using high-energyelectrons to destroy halogenated hydrocarbons and toprecipitate toxic heavy metals from waste streams.

The faculty researchers and graduate students on thisproject are using high-energy electron beams (7 MeV to32 MeV) from the MIRF electron linac, as well as2 MeV electrons from our 50 ns pulsed Febetron accel-erator. After irradiation of the halogenated hydrocar-bons (PCBs), measurements are made on the degrada-tion products by mass spectrometry. Preliminarymeasurements suggest that the high-energy electronsoffer an effective method of dechlorinating halocarbonsin thick samples. A novel irradiation design also is beingtested for solutions of heavy metals such as lead. Prelim-inary results of irradiating lead solutions with 16 MeVelectrons are very encouraging.

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NIST ASSISTS INDUSTRY INTHERMOPLASTICS ENGINEERING DESIGNResearch engineers from two major U.S. companiesrecently met with NIST researchers to discuss needs indata and constitutive modeling. The two companies arecollaborating to develop better methods for designingmolds for injection molded parts. A major thrust of thework involves developing superior methods of estimat-ing residual stresses imparted in molded parts duringthe molding process in order to avoid warpage andshrinkage errors and premature failures. In particular,significant savings are possible if molds can be designedright the first time to avoid expensive, iterativerework of the molds.

Currently, researchers from the two companies areperforming computer simulations assuming a linearvisco-elastic material behavior to estimate part dimen-sions and molded in stresses. As a result of the meeting,NIST will provide data on the viscoelastic response of amodel polycarbonate material being used in the jointprogram. The data obtained by NIST will be used in thecomputer simulations and the results compared directlywith the two companies experiments using a one-of-a-kind instrumented mold. NIST scientists briefed partici-pants on concurrent work at NIST that addresses limita-tions of prevailing simulation models arising from theassumption of linear viscoelastic material behavior. TheNIST work uses finite-element modeling with advancedconstitutive equations for the same polycarbonatematerial and develops efficient means to use laboratoryexperiments to obtain materials data in the non-linearregime of mechanical behavior.

METHOD DEVELOPED TO MEASUREMATERIAL DENSITY AT SURFACESScientists at NIST have developed a technique that im-proves the accuracy in measuring the density of materi-als at flat surfaces by at least a factor of five. Thetechnique uses the reflection of x rays to determinedensity to a depth on the order of tens of nanometers.The method is expected to be particularly useful in thestudy of thin dielectric layers used in microelectronics.Density is a property that is often critical in determiningperformance in service. However, near-surface and thin-film density is difficult to measure, primarily due to thesmall amount of material involved. The new methodcould be adapted to measure density in situ during filmdeposition and, thus, serve as a useful process diagnos-tic.

Currently, the most direct way to measure near-surface density is single-wavelength x-ray reflectivity.The uncertainty in the density determination by this

method is largely controlled by the alignment of thesample with respect to the incident x-ray beam. Forexample, a misalignment of 23104 rad in sample tiltcan change the measured density by 10 % of the den-sity. Methods to improve sample alignment are possible,but would be tedious and difficult to implement. NISTscientists have demonstrated that a fivefold improvementin accuracy can be attained by measuring the x-rayreflectivity at many different wavelengths simulta-neously. This is accomplished by replacing the conven-tional detector with an energy-dispersive detector. Mis-alignment of the sample will result in a differentcalculated density for each wavelength, but the extrapo-lation of the resultant density-versus-wavelength to in-finite wavelength yields the correct value. The techniquehas been tested successfully on samples with well-char-acterized densities, e.g., silicon single-crystal surfaces,as well as on thin films with unknown densities, e.g.,spin-on-glass dielectrics. Discussions are under waywith a major manufacturer of x-ray reflectivity instru-mentation to incorporate this measurement technologyinto commercial instrumentation.

MICROMAGNETIC MODELING WORKSHOPThe micromagnetic modeling activity group, sponsoredby NIST held a workshop in conjunction with the 1995IEEE International Magnetics Conference. The purposeof the workshop was to bring together representativesfrom industry, academia, and government labs to ad-dress fundamental problems and challenges in micro-magnetic modeling. The field of micromagnetics is con-cerned with the configuration of magnetic moments inmagnetic domains and domain walls on a mesoscopicscale, which is larger than the atomic length scale but istoo small to be adequately described by bulk materialproperties.

The digital data storage industry relies on micromag-netic modeling for the design of read/write heads andmedia for high-density magnetic data storage, and otherindustries use micromagnetic modeling for the design ofmagnetic field sensors for a variety of commercialapplications.

The workshop drew an estimated 100 magnetismexperts from around the world, and fully half of the 30people indicating interest in further participation werefrom U.S. companies. Three main needs were identi-fied: the need for accurate materials data, the need forquantitative checks for micromagnetic computer codedevelopment, and the need for portable public code formicromagnetic calculations. In response to this discus-sion, two working groups, which will include industrial,academic, and government scientists, are being formed.

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NIST RESEARCHERS RECEIVE PATENT FORA WELDING CONTROL SYSTEMPatent 5,349,156, Sensing of Gas Metal Arc WeldingProcess Characteristics for Welding Process Control,was granted to two NIST researchers. The patent coversa system to sense and control the arc length in gas metalarc welding, a dominant welding process, with yearlysales of more than 100 000 000 kg of welding electrode.The system goes beyond previous technology bycombining a light intensity sensor (to measure the arcintensity) with a current sensor (to correct for changesin the arc diameter). Tests show that the system is ableto control the arc length to within 1 mm, when thecontact-tube-to-work distance changes by 10 mm. Suchprecision in an automatic sensor allows robotic produc-tion lines to correct for part variations and distortion,leading to higher quality and fewer rejects. This systemwill be added to the previously developed arc sensingand control systems that are being evaluated for indus-trial applications under Cooperative Research andDevelopment Agreements with two private companies.

NIST HOSTS JOINT MEETING WITH NSFCENTER FOR SCIENCE AND TECHNOLOGYOF ADVANCED CEMENT-BASED MATERIALSA joint meeting of the National Science FoundationCenter for Science and Technology of AdvancedCement-Based Materials (ACBM) and the NIST High-Performance Construction Materials and SystemsProgram was held April 5-6, 1995. The primary objec-tive was to introduce industry to the latest developmentsin cement and concrete materials research that couldprovide the technical basis for new products with signif-icant commercial potential.

The meeting was attended by more than 50 individ-uals representing the 18 industrial affiliates of theACBM, federal agencies, Washington, DC-based indus-try organizations, as well as NIST and ACBMresearchers. ACBM is a consortium of NorthwesternUniversity, the University of Illinois, the University ofMichigan, Purdue University, and NIST.

The agenda included 15 technical presentations onboth center and NIST projects, including those by NISTstaff. These addressed the following topics: hydrationand shrinkage of cements; concrete rheology; mecha-nisms of transport and environmental degration; compo-sitional and phase analysis of cement-based materials;performance of fiber-reinforced concrete composites;and mechanical testing, structural performance, andfield curing of high-strength concretes.

NIST MODELS RADON TRANSPORT INLARGE MULTIZONE BUILDINGSNIST has performed computer simulations of airflowand radon transport in four large buildings using themultizone airflow and indoor air quality model CON-TAM developed at NIST. These buildings include a12-story multifamily residential building, a five-storymechanically ventilated office building with an atrium,a seven-story mechanically ventilated office buildingwith an underground parking garage, and a one-storyschool building. These simulations were performed tostudy the impact of weather conditions, building charac-teristics, and ventilation system design and operation onradon entry rates and indoor radon concentrations.

One important finding of this effort is the importanceof vertical shafts, such as elevators and stairways, intransporting radon from ground-contact floors to theupper floors of a building. When the indoor air temper-ature is above the outdoor temperature, air will tend toflow into these shafts on lower floors and out on upperfloors. This airflow pattern will result in low radonconcentrations on the first few floors of a building andelevated concentrations on the upper floors. In addition,unexpected relationships between building pressure andwind speed were found when mechanical ventilationsystems were operating.

The project was not undertaken to estimate humanexposure to radon but instead to demonstrate the abilityof these models to account for the complexities of air-flow and contaminant transport in multizone buildingsystems. The CONTAM program provides designers andothers with new capabilities for predicting ventilationrates and indoor pollutant concentrations at a high levelof technical sophistication and with an extremely user-friendly interface. In the future, designers, equipmentmanufacturers, and others involved in the constructionand operation of buildings will use these programs topredict indoor pollutant levels, make decisions on build-ing equipment and furnishings, and implement indoorair quality controls. The results of this effort, performedfor the Office of Radiation and Indoor Air of the U.S.Environmental Protection Agency, are reported inNISTIR 5611, Computer Simulations of Air Flow andRadon Transport in Four Large Buildings.

FAULT DETECTION AND DIAGNOSIS USINGARTIFICIAL NEURAL NETWORKSNIST researchers have completed preliminary researchon fault detection and diagnosis (FDD) of building me-chanical systems. This was done collaboratively with

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researchers from 10 countries to evaluate a wide varietyof FDD methods using simulation studies, laboratorytest rigs, and real building data. Applications have in-cluded variable air volume (VAV) air handling systems,chillers and heat pumps, oil burners and boilers, districtheating systems, and thermal storage systems.

One of the most promising methods investigated is theuse of an artificial neural network (ANN) for FDD of aVAV air handling unit. The approach involves selectinga set of residuals of system variables that can be used toquantify the dominant symptoms of different faultmodes of operation. The residuals are normalized, andidealized steady-state patterns of these normalizedresiduals are used to define each mode of operation. Thesteady-state relationship between the dominant symp-toms and the faults are learned by an ANN using aback-propagation algorithm. The ANN network is thenapplied to real data and identifies both normal and ab-normal operation and the type of fault when one arises.The method has been applied successfully to both simu-lated and laboratory data and has been implemented ona real VAV air handling unit in a NIST laboratory.Eight types of faults have been studied to date. Theresults have been very encouraging. Future researchwill develop separate ANNs for each mechanicalsubsystem and use an expert system to identifythe appropriate subsystem to examine the existence offaults.

PROCEEDINGS OF TEXT RETRIEVALCONFERENCE PUBLISHEDNIST Special Publication 500-225, Overview of theThird Text REtrieval Conference (TREC-3), presentsthe proceedings of a workshop held in November 1994in Gaithersburg, MD. Co-sponsored by NIST and theAdvanced Research Projects Agency, TREC-3 was thethird in an ongoing series of workshops, which bringtogether researchers to explore different approaches tosearching and retrieving unstructured text. About 150people involved in 32 participating research groups fromindustry and academia attended the conference.

Using the same large test collection in their evalua-tions, participants reported on a wide variety of retrievaltechniques, including methods using automaticthesauri, sophisticated term weighting, natural languagetechniques, relevance feedback, and advanced patternmatching. Since results were obtained through a com-mon evaluation package, groups were able to comparethe effectiveness of different techniques and to discusshow differences among the systems affected perfor-mance.

NEW PUBLICATION GIVES BLUEPRINT FORELECTRONIC ACCESS TO HISTORICALINFORMATIONNIST Special Publication 500-227, ELECTRONICACCESS: BLUEPRINT for the National Archives andRecords Administration, describes an electronic accesssystem that would allow citizens in remote areas to re-ceive historical information maintained by the NationalArchives and Records Administration (NARA). The1994 Electronic Access Study (described in NIST Spe-cial Publication 500-221) identified four priority needsof users: information on locating information andservices available through NARA; a catalog of recordsand related material held by NARA; the capability foronline ordering; and the ability to download NARAdocuments. NIST Special Publication 500-227 presentsa blueprint for meeting these needs.

REPORT DETAILS BENEFITS OF ELECTRONICWORKSHOPAutomating the operations of the Open Systems Envi-ronment Implementors Workshop (OIW) resulted insubstantial cost savings as well as improved timelinessand accessibility of information to the OIW member-ship and the public. NISTIR 5623, An Electronic Imple-mentors Workshop, describes the various elements ofan electronic workshop and provides a list of capabili-ties needed to operate one. The primary requirement isuse of the Internet for basic communications such aselectronic mail, public forums, and distribution of publi-cations using computer-based media.

COMMERCE, ENERGY JOIN FORCES TO AIDMANUFACTURERSThe Departments of Commerce and Energy haveannounced the signing of two separate agreements tocombine their resources to help American textile andother manufacturers improve their competitiveness, andpreserve and create jobs. The memoranda of understand-ing build upon the success of existing technologycommercialization programs. In the first, the standardsdevelopment and computer-integrated manufacturingactivities of NISTs Apparel Technology Program arecoordinated with DOEs AMTEX Program. AMTEX isa partnership that links DOE laboratories and universi-ties to the textile industry. The second agreementbetween DOC and DOE links Energys laboratorieswith the NIST-managed Manufacturing ExtensionPartnership nationwide network of 42 centers. The jointeffort will better disseminate technical information andexpertise in areas including pollution prevention, wasteminimization, and energy efficiency to the nations381,000 smaller manufacturers.

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FIRST FULL-SCALE FIRE TESTS FORHIGH CEILINGS DONESmoke detectors, automatic sprinklers and other fireprotection systems are common sights in buildingsthroughout the United States. However, building codesmandating their use are limited to structures withceilings less than 9 m in height. The reason: a lack ofresearch data on the behavior and movement of flame,heat and smoke in high-ceiling spaces. To remedy thisproblem and help spur the development of fire protec-tion systems for high-ceiling spaces, NIST is part of aresearch team that also includes NASA, the U.S. Navyand five fire equipment manufacturers. NASA and theU.S. Navy are concerned because many of their facili-ties cannot use fire plans designed for lower-ceilingstructures. One towering example is NASAs 158 mVehicle Assembly Building in Cape Canaveral, FL. Overthe past 4 years, NIST researchers have created three-dimensional computer models to simulate flame, heatand smoke behavior in high-ceiling spaces. The firstfull-scale testing of these models, as well as prototypefire detection and suppression equipment designed forhigh-ceiling structures, recently occurred at Navy air-craft hangars in Hawaii and Iceland. Thirty-five fires,ranging from 0.3 sm2 to 67.5 sm2 in area, were studiedin the hangars under varying conditions. Each fireyielded data on 200 separate measurement points. Theteam hopes to publish a report on the fire tests in early1996. For technical information, contact KathyNotarianni, B356 Polymer Building, NIST,Gaithersburg, MD 20899-0001, (301) 975-6883,e-mail: [email protected] (via Internet).

DISTRIBUTION AMPLIFIERS YIELD LOWNOISE, HIGH ISOLATIONNew low-noise amplifiersdesigned for distributingstandard time and frequency signals within a labora-toryhave been developed by NIST and researchers atthe Technical University of Torino (Italy). The devicesprovide exceptionally low environmental sensitivity andremarkably high isolation among all outputs and input.One model is designed for 5 MHz to 10 MHz, whileanother goes up to 100 MHz. These unity-gain amplifi-ers accept input signals of up to 1 V root-mean-squareand supply five independent outputs. There is typicallya 120 dB isolation between channels, and between inputand outputs, which means that shorting or disconnectingone channel changes the phase of another channel byless than 40 fs at 5 MHz or 2 fs at 100 MHz. Phase delaysensitivity to temperature is less than 0.3 ps/K, resultingin a fractional frequency error of less than 3310218/K

for a measurement time of one day. This error is at least1000 times smaller than those associated with todaysfrequency standards. These properties assure that thefull accuracy and stability of the standard driving theamplifier is delivered to the multiple output ports, andcan make the acquisition of additional standards unnec-essary in some metrology laboratories. For technicalinformation, contact Fred Walls, Div. 847.30, NIST,Boulder, CO 80303-3328, (303) 497-3207, e-mail:[email protected] (via Internet).

Standard Reference Materials

SRM 2391PCR-BASED DNA PROFILINGSTANDARDDNA profiling has been a revolutionary developmentin the field of human identity testing. The PCR(poly-merase chain reaction) process is capable oftyping biological evidence containing old, degraded, orminute amounts of human DNA, with more distinctidentification of alleles, enhanced sensitivity, andgreater efficiency than other conventional techniques. Ithas proven invaluable to the forensics, paternity testing,and molecular biology communities, and has been afocus of discussion with the FBI for several years. Thetechnology is at a point where standards are required foruniversal acceptance in the legal community. To date,several court cases already have been decided based onthis technology.

The Standard Reference Materials Program an-nounces the availability of SRM 2391PCR-BasedDNA Profiling Standard. This SRM was developed withfunding by the National Institute of Justice throughNISTs Office of Law Enforcement Standards and theNIST Standard Reference Materials Program. SRM2391 is intended for use by forensic and paternitylaboratories for PCR-based DNA genetic testing as wellas for instructional law enforcement and nonclinicalresearch purposes.

SRM 2391 is a 20-component SRM comprised ofeight well-characterized human genomic DNAs, fourPCR-amplified products for the D1S80 locus, an allelicladder for the D1S80 locus, and a 100 base-pair molec-ular weight ladder (known as a DNA Analysis Marker),which is calibrated with DNA band sizes that rangefrom 100 to 1500 base-pairs of DNA.

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EIGHT THOUSAND SERIES RMS FORFINE GOLD, FINE SILVER, AND GOLDBULLION FROM THE RO

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