NBS standard reference materials catalog 1981-83 edition /

Includes index.Editions for 1965-1969 published under title: Catalog and price list of standard reference materials issued by the National Bureau of Standards. Edition for 1970 published under title: Catalog of standard reference materials. Edition for 1973 published under title: Standard reference materials: 1973 catalog. Edition for 1975 published under title: Catalog of NBS standard reference materials.Mode of access: Internet

Chemical profiling of heroin recovered from the North Korean merchant vessel Pong Su

Heroin samples, seized from the North Korean merchant vessel Pong Su in Australian waters, were analyzed to determine geographic origin. Duplicate samples were analyzed by the National Measurement Institute`s Australian Forensic Drug Laboratory and the United States Drug Enforcement Administration`s Special Testing and Research Laboratory. Alkaloid ratios were determined by both liquid chromatography-diode array detection (LC-DAD) and capillary electrophoresis-diode array detection (CE-DAD) techniques. Acid/neutral manufacturing by-products were determined by solvent extraction followed by gas chromatography-mass spectrometry (GC-MS). Solvents, trapped in the heroin particles during manufacture, were detected by both static headspace GC-MS and purge and trap GC-MS. The alkaloid ratios obtained were consistent with heroin of a Southeast Asian (SEA) origin and principal component analysis of the alkaloid results demonstrated the presence of at least four subgroupings within the seizure. The solvent analysis detected diethyl ether and ethyl acetate, solvents typically seen in SEA heroin. However, the acid/neutral analysis revealed compounds not normally seen in heroin of a SEA origin. Furthermore, sterol-like molecules, always detected in the acid/neutral analysis of SEA heroin, were absent from the Pong Su samples. The Pong Su heroin, although similar to SEA heroin, has sufficient differences to classify it as having an unknown origin at the time of this writing

Ultrasonic materials characterization : proceedings of the first International Symposium on Ultrasonic Materials Characterization held at the National Bureau of Standards, Gaithersburg, Md., June 7-9, 1978 /

Item 247.S/N 003-003-02264-1."Issued November 1980.""National Measurement Laboratory, National Bureau of Standards."Includes bibliographical references.Mode of access: Internet

Automatic differentiation techniques and their applications

'Report to the National Measurement System Directorate, Department of Trade and Industry' - Cover. Includes bibliographical referencesAvailable from British Library Document Supply Centre- DSC:6029. 4378(26/03) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Proceedings of Workshop on Asbestos, Definitions and Measurement Methods ... held at the National Bureau of Standards, Gaithersburg, Maryland, July 18-20, 1977 /

Includes bibliographical references.Mode of access: Internet

Advanced composites : design and applications : proceedings of the 29th meeting of the Mechanical Failures Prevention Group, held at the National Bureau of Standards, Gaithersburg, Maryland, May 23-25, 1979 /

"The 29th meeting of the MFPG and these proceedings were sponsored by the Center for Materials Science of the National Bureau of Standards ... [et al.]""Issued October 1979."At head of title: MFPG.Includes bibliographical references.Mode of access: Internet

Measurements and standards for recycled oil-II : proceedings of a conference held at the National Bureau of Standards, Gaithersburg, Maryland, November 29 and 30, 1977 /

Includes bibliographical references.Mode of access: Internet

Applications of phase diagrams in metallurgy and ceramics : proceedings of a workshop held at the National Bureau of Standards, Gaithersburg, Maryland, January 10-12, 1977 /

Includes bibliographical references and indexes.Mode of access: Internet

High Free‐Tropospheric Aitken‐Mode Aerosol Concentrations Buffer Cloud Droplet Concentrations in Large‐Eddy Simulations of Precipitating Stratocumulus

A new Aitken mode aerosol microphysics scheme is developed for a large eddy simulation model in order to better investigate cloud‐aerosol interactions in the marine boundary layer and to study the Aitken buffering hypothesis of McCoy et al. (2021), https://doi.org/10.1029/2020jd033529. This scheme extends the single‐mode two‐moment prognostic aerosol scheme of Berner et al. (2013), https://doi.org/10.5194/acp-13-12549-2013. Seven prognostic variables represent accumulation and Aitken log‐normal aerosol modes in air and droplets as well as 3 gas species. Scavenging of interstitial and other unactivated aerosol by cloud and rain drops are treated using the scheme described in Berner et al. (2013), https://doi.org/10.5194/acp-13-12549-2013. The scheme includes coagulation of unactivated aerosol and a simple chemistry model with gas phase H2SO4, SO2, and DMS as prognostic variables to capture basic influences of sulfur chemistry on the model aerosols. Nucleation of H2SO4 aerosol particles from gas‐phase H2SO4 is neglected. A deep, precipitating stratocumulus case (VAMOS Ocean Cloud Atmosphere Land Study RF06) is used to test the new scheme. The presence of the Aitken mode aerosol increases the cloud droplet concentration through activation of the larger Aitken particles and delays the creation of an ultraclean, strongly precipitating cumulus state. Scavenging of unactivated accumulation and Aitken particles by cloud and precipitation droplets accelerates the collapse. Increasing either the above‐inversion Aitken concentration or the surface Aitken flux increases the Aitken population in the boundary layer and prevents the transition to an ultraclean state.Plain Language SummaryAerosols can have large effects on low‐level oceanic clouds, and cloud processes strongly affect aerosols as well. Both aerosols and clouds are a major source of uncertainty in climate projections. A standard tool for studying low altitude ocean clouds and their interactions with aerosols is large‐eddy‐simulation (LES), but this tool can be very computationally expensive when aerosols of many different sizes are included, which can restrict the geographic coverage, the model resolution, and the time extent of model simulations. We present a new numerical framework for LES that allows treatment of two size categories of aerosols and their interactions with clouds in a relatively simple and inexpensive manner. We use this framework and perform a wide range of numerical simulations where aerosol number, properties, and physics are varied in a 10‐day simulation of low clouds in a small region over the Southeast Pacific Ocean. Our simulations show that small aerosols can have large effects on low cloud survival in some circumstances.Key PointsA simple two‐mode aerosol scheme allows exploration of Aitken effects on aerosol and cloud evolutionAitken aerosols supplement the accumulation mode and can prevent boundary‐layer collapse in some casesScavenging of unactivated aerosol particles by cloud droplets has a strong effect on aerosol evolutio

Joint Conference on Measurements and Standards for Recycled Oil/Systems Performance and Durability : proceedings of a conference held at the National Bureau of Standards, Gaithersburg, MD, October 23-26, 1979 /

Item 247.S/N 003-003-02272-1."Issued November 1980.""Office of Recycled Materials, National Measurement Laboratory, National Bureau of Standards."Includes bibliographical references.Mode of access: Internet