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A Model for the Binding of Fluorescently Labeled Anti-Human CD4 Monoclonal Antibodies to CD4 Receptors on Human Lymphocytes
No full textThe CD4 glycoprotein is a component of the T cell receptor complex which plays an important role in the human immune response. This manuscript describes the measurement and modeling of the binding of fluorescently labeled anti-human CD4 monoclonal antibodies (mAb; SK3 clone) to CD4 receptors on the surface of human peripheral blood mononuclear cells (PBMC). CD4 mAb fluorescein isothiocyanate (FITC) and CD4 mAb allophycoerythrin (APC) conjugates were obtained from commercial sources. Four binding conditions were performed, each with the same PBMC sample and different CD4 mAb conjugate. Each binding condition consisted of the PBMC sample incubated for 30 min in labeling solutions containing progressively larger concentrations of the CD4 mAb-label conjugate. After the incubation period, the cells were re-suspended in PBS-based buffer and analyzed using a flow cytometer to measure the mean fluorescence intensity (MFI) of the labeled cell populations. A model was developed to estimate the equilibrium concentration of bound CD4 mAb-label conjugates to CD4 receptors on PBMC. A set of parameters was obtained from the best fit of the model to the measured MFI data and the known number of CD4 receptors on PBMC surface. Divalent and monovalent binding had to be invoked for the APC and FITC CD4 mAb conjugates, respectively. This suggests that the mAb binding depends on the size of the label, which has significant implications for quantitative flow cytometry. The study supports the National Institute of Standards and Technology program to develop quantitative flow cytometry measurements
ITL-Cybersecurity_2018-02-07_Transcript
No full textITL Oral history interview of Dennis Branstad, Miles Smid, and Stuart Katzke all of whom were principle players in the establishment and implementation of the NBS/NIST program in data encryption and cyber security
Bourdon F. Scribner
No full textBOURDON F. SCRIBNER
NBS/NIST: 1927–1973
INDUCTED: 2018
B: 1910, Westernport, Maryland
D: 2007, Annapolis, Maryland
EDUCATION:
George Washington University, BS (Chemistry), 1933
University of Maryland, MS (Chemistry), 1939
CITATION:
For leadership in advancing atomic spectroscopy into a critical scientific quantitative chemical analysis method. His analyses of uranium ores significantly advanced U.S. efforts to build nuclear reactors during World War II.
POSITIONS HELD AT NBS/NIST:
Physicist, Spectroscopy Section, Optics Division, 1927-1947
Chief, Spectrochemical Analysis Section, Analytical Chemistry Division, Institute for Materials Research (IMR), 1947-1971
Deputy Chief, Analytical Chemistry Division, IMR, 1971-1973
HONORS:
U.S. Department of Commerce Silver Medal (1951) and Gold Medal (1969)
American Society for Testing and Materials, Award of Merit (1958)
Award of the Spectroscopy Society of Pittsburgh (1959)
Gold Medal of the New York Section of the Society for Applied Spectroscopy (1961)
B. F. Scribner Award, ASTM Committee E02 on Emission Spectroscopy (1983)
Fellow, Optical Society of America
Honorary Member, Society for Applied Spectroscopy
Honorary Member, Groupement pour l’Avancement des Méthodes Spectrographiques
MEMBERSHIPS:
American Society for Testing and Materials, E02 Secretary (1938-1944), Chair (1946-1954)
Society for Applied Spectroscopy
PUBLICATIONS:
More than 85 publications including:
Meggers, W.F. and Scribner, B.F., "Arc and Spark Spectra of Technetium", J. Res. Natl. Bur. Stds. 45, 476 (1950)
Corliss, C.H. and Scribner, B.F., "Spectrochemical Determination of Minor Constituents of Stainless Steel", Analytical Chemistry 24, 603 (1952)
Margoshes, M., and Scribner, B.F., "The Plasma Jet as a Spectroscopic Source", Spectrochimica Acta 15, 138 (1959)
Scribner, B.F., "The Impact of Computer Techniques on Atomic Spectroscopy", Applied Spectroscopy 21, 375 (1967)
Scribner, B.F., "Future Standards for Instrumental Analysis", Applied Spectroscopy 22, 229 (1968)
Meggers,W.F., Corliss, C.H., and Scribner, B.F., "Tables of Spectral Line Intensities", NBS Monograph 145 (1975
It's a trap!
No full textBut don’t worry, you’re not likely to get caught in it. Researchers at the NIST Center for Neutron Research are using this proton trap to measure the neutron’s lifespan, or the amount of time it takes for a neutron to decay into its component parts (a proton, an electron and an electron antineutrino). Scientists shoot a beam of neutrons into the proton trap. As the neutrons decay, the protons are caught and counted. From the number of trapped protons, the neutron lifetime can be calculated. This device is at the center of a current scientific debate: Is the neutron lifetime 14 minutes and 39 seconds or 14 minutes and 48 seconds? Those 9 seconds may not seem like much, but they could hold the key to discovering the origin and identity of dark matter. While the verdict is still out on what dark matter is or which count is correct, we do know that precisely measuring the neutron lifetime will give us a better understanding of fundamental physics, the Big Bang and our future
A selection of the 1-kg stainless steel weights used in a study to determine why precision mass standards
No full textA selection of the 1-kg stainless steel weights used in a study to determine why precision mass standards that are supposed to be identical drift over time. Such drift was one of the reasons behind the redefinition of the kilogram in terms of unvarying constants of nature in November 2018
Newton apple tree on the NIST campus in Gaithersburg, MD
No full textNIST Gaithersburg’s Newton apple tree on a spring morning. Like its more famous ancestor, the tree continues to produce apples, although they taste terrible. The deer don’t seem to mind, though
Baseline Tailor
No full textBaseline Tailor is an innovative web application for users of the National Institute of Standards and Technology (NIST) Cybersecurity Framework [1] and Special Publication (SP) 800-53 [2]. Baseline Tailor makes the information in these widely referenced publications easily accessible to both security professionals and downstream software by addressing the following barriers:
• Complexity of the rules for tailoring SP 800-53 security controls,
• Differences in the Framework's and SP 800-53 organizational approach,
• Lack of a computer-readable data format for representing tailored security controls.
The NIST Engineering Laboratory’s Cybersecurity for Smart Manufacturing Systems project used Baseline Tailor to help develop a Cybersecurity Framework profile for the manufacturing environment [3]. This “manufacturing profile” uses guidance from NIST SP 800-53 and from NIST SP 800-82 Guide to Industrial Control Systems Security [4] to provide manufacturers with a roadmap for reducing
cybersecurity risk
Calibration Fluids and Calibration Equations: How Choices May Affect the Results of Density Measurements Made with U-Tube Densimeters
No full textData on the calibration fluids water and toluene individually, and the combination of those two sets of data, were correlated with two different equations (resulting in six sets of calibration equation parameters) to analyze data measured with a vibrating-tube densimeter on the lubricants pentaerythritol tetrapentanoate (POE5), pentaerythritol tetraheptanoate (POE7), and pentaerythritol tetranonanoate (POE9) at temperatures from 270 K to 470 K and pressures from 0.5 MPa to 50 MPa. The objective was to explore how the calculated densities of the lubricants would differ based on the calibration equations and calibration fluid(s). The viscosities of the measured lubricants are much greater than those of the calibration fluids, and because there has long been a question of how measurements of higher viscosity fluids are affected when measured with a vibrating-tube densimeter, combinations of calibration fluid(s) and equations were tested to explore the role they play in obtaining accurate results. For the lubricants studied herein, more accurate results were obtained with a calibration fitted to multiple calibration fluids, while the consistency of results was more equation dependent
How to Define the Units of the Revised SI Starting from Seven Constants with Fixed Numerical Values
No full textAs part of a revision to the International System of Units (SI) approved in 2018 and to take effect in May 2019, the seven base units will be defined by giving fixed numerical values to seven defining constants. This article shows how the definitions of all seven base units can be derived efficiently from the defining constants, with the result appearing as a table. The table’s form makes evident a number of connections between the defining constants and the base units. Appendices show how the same methodology could have been used to define the same base units in the present SI, as well as the mathematics that underpins the methodology. Since the base units are now defined in terms of constants, then all units in the SI are now defined in terms of those constants
Measurements of Scatter Peaks in 137Cs and 60Co Sources
No full textResults from tests of radiation detection instruments with radionuclide identification capabilities will depend on the sources used for the tests. Radionuclide identification detectors are designed to measure photons and provide an identification of the source being measured. High-resolution spectra need to be acquired to determine all the observable peaks in the source spectra before testing these types of instruments. These peaks may be due to impurities and/or scatter peaks in the sources. This paper discusses the issues encountered with the response of a radioisotope identification device due to scatter peaks in one type of source used for testing. In addition, it provides spectra for different source types and source constructions to compare the differences in scatter, allowing for a better source type selection for instrument testing