A5074666676- Isotope Analysis in Ecology
- Nuclear Physics and Applications
- Mass Spectrometry Techniques and Applications
- Radioactive contamination and transfer
- Astro and Planetary Science
- Scientific Measurement and Uncertainty Evaluation
- Atmospheric and Environmental Gas Dynamics
- Nanomaterials and Printing Technologies
- Radioactive Decay and Measurement Techniques
- Innovative Microfluidic and Catalytic Techniques Innovation
- Groundwater and Isotope Geochemistry
- Planetary Science and Exploration
- Analytical chemistry methods development
- Forensic Fingerprint Detection Methods
- Graphite, nuclear technology, radiation studies
- Fluid Dynamics and Heat Transfer
- Radiation Detection and Scintillator Technologies
- Archaeology and ancient environmental studies
- Advanced Chemical Sensor Technologies
- Forensic Toxicology and Drug Analysis
- Recycling and Waste Management Techniques
- Electrohydrodynamics and Fluid Dynamics
- Particle Dynamics in Fluid Flows
- nanoparticles nucleation surface interactions
- Radioactive element chemistry and processing
National Institute of Standards and Technology
2011-2025
Material Measurement Laboratory
2011-2021
International Atomic Energy Agency
2006
United States Geological Survey
2006
Max Planck Institute for Biogeochemistry
2006
National Institute of Standards
2001
United States Department of Commerce
2001
Purdue University West Lafayette
1983-1988
Consistency of delta13C measurements can be improved 39-47% by anchoring the scale with two isotopic reference materials differing substantially in 13C/12C. It is recommended that values both organic and inorganic measured expressed relative to VPDB (Vienna Peedee belemnite) on a normalized assigning consensus -46.6 per thousand L-SVEC lithium carbonate +1.95 NBS 19 calcium carbonate. Uncertainties other material this are factors up or more, some have been notably shifted: 22 oil -30.03 thousand.
We describe gravimetric methods for measuring the mass of droplets generated by a drop-on-demand (DOD) microdispenser. Droplets are deposited, either continuously at known frequency or as burst number, into cylinder positioned on submicrogram balance. Mass measurements acquired precisely computer, and results corrected evaporation. Capabilities demonstrated using isobutyl alcohol droplets. For ejection rates greater than 100 Hz, repeatability droplet was 0.2%, while combined relative...
Abundances of major, minor, and trace elements were determined in the whole rock mineral separates two distinct lithologies present Antarctic achondrite Elephant Moraine A (EETA) 79001 via sequential instrumental (INAA) radiochemical neutron activation analysis (RNAA). Additional chalcophile, siderophile, volatile are reported for shergottites ALHA 77005, Shergotty, Zagami. The rare earth element (REE) abundances each EETA (A B) exhibit chondritic normalized patterns similar to 77005. close...
Abstract Plastic particulates in the environment pose an increasing concern for regulatory bodies due to their potential risk higher organisms (including humans) as they enter food chain. Nanoplastics (defined here smaller than 1 μm) are particularly challenging detect and analyze at environmentally relevant concentrations biological matrices. The tunicate Ciona Robusta is effective bioindicator microplastics nanoplastic contamination marine environment, its capacity filter substantial...
We report highly reproducible gravimetric and optical measurements of microdroplets that lend insights into the fundamentals drop-on-demand (DOD) printing. Baseline fluidic pressure within DOD dispenser was controlled to 0.02 hPa, enabling long-term stability in dispensed droplet mass with observed variations near 1% (RSD) for isobutanol. The were sensitive enough detect avoid unwanted effects from air bubbles dispenser. velocity enabled consistent determination kinetic energy governed...
Continuing efforts to combat the opioid crisis in U.S. require technologies that can detect presence of fentanyl and fentanyl-related substances for multiple applications, including law enforcement border protection.
Abstract The 2019 redefinition of the kilogram not only changes way mass is defined but also broadens horizon for a direct realization other standards. true becquerel project at national institute standards and technology creating new paradigm dissemination radionuclide activity. Standard reference materials radioactivity are supplied as aqueous solutions specific radionuclides which characterized by massic activity in units per gram solution, Bq/g. method requires measuring few milligrams...
The design and performance of a vapor generator for calibration testing trace chemical sensors are described. device utilizes piezoelectric ink-jet nozzles to dispense vaporize precisely known amounts analyte solutions as monodisperse droplets onto hot ceramic surface, where the generated vapors mixed with air before exiting device. Injected monitored by microscope strobed illumination, reproducibility droplet volumes is optimized adjustment wave form parameters. Complete vaporization occurs...
Commercial off-the-shelf (COTS) explosive trace detectors (ETDs) have become an integral part of security practices aimed at protecting the public, transportation, and facilities. Despite their widespread deployment, quality control procedures that can evaluate day-to-day instrument performance or differences among units same manufacture are in need for development. In this work, we describe preparation test materials (TMs) using inkjet printing fixed dosing levels two explosives;...
Receiver operating characteristic (ROC) curve framework was employed to investigate the trace detection of fentanyl and fifteen fentanyl-related compounds relative environmental background interferents.
We have developed a method to produce discrete microparticles from compounds dissolved in nonpolar or polar solvents using drop-on-demand inkjet printer technology. A piezoelectric printhead located atop drying tube produces precise droplets containing defined quantities of analyte. Droplets solidify into with known composition and size as they traverse down the tube. Because this is printing process, number are produced providing quantitative particle delivery variety substrates. Particular...
We report high-precision isotopic carbon dioxide measurements, made before and after ion source modification to gas isotope ratio mass spectrometry (IRMS) instruments. Measurement protocols were designed explore the effects of material substitution, conductance, inlet pressure, electron emission, acceleration potential, changeover equilibration time. After IRMS instruments at National Institute Standards Technology (NIST) Max-Planck-Institute for Chemistry (MPI-Mainz), immediate changes...
We report a pilot study of high-precision differential isotope ratio measurements made on replicate samples pure carbon dioxide using three instruments identical manufacture. Measurement protocols were designed to explore the effects sample size, ion source conductance, and inlet changeover equilibration time raw measurements. Our goal was better understanding factors that influence these in order establish procedures for highly reproducible accurate determinations Reference Material (RM)...
Three carbon dioxide isotopic reference materials (RM 8562, RM 8563, and 8564) have been prepared characterized for composition, heterogeneity, stability using dual-inlet isotope ratio mass spectrometry. RMs 8562−8564 are not certified, but their use as proxies carbonate standards allows users to realize precisely the Vienna PDB scale provide comparability of stable oxygen data obtained by investigators in different laboratories. Samples (∼400 μmol each) sealed borosilicate glass tubes (9-mm...
Contents of siderophilic As, Au, Co, Ga and Sb, volatile/mobile Ag, Bi, Cd, In, Se, Te, Tl Zn lithophilic Cs, Rb U determined by radiochemical neutron activation analysis in ALH A81005 are similar to those lunar highlands samples returned Apollo missions, indicating this meteorite's origin. Five elements (Co, lithophiles) reflect crustal processes while the remaining 11 siderophile mobile (including most ones) indicate 1.4 ± 0.5% micrometeorite (Cl equivalent) admixture or enrichment thermal...
We present a new paradigm for the primary standardization of radionuclide activity per mass solution (Bq/g). Two key enabling capabilities are 4π decay-energy spectrometry using chip-scale sub-Kelvin microcalorimeters and direct realization by gravimetric inkjet dispensing an electrostatic force balance. In contrast to traditional traceability, which typically relies on chemical separation single-radionuclide samples, integral counting, additional methods verify purity, system described here...