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NIST Authors in Bold

Displaying 5751 - 5775 of 74178

A fast negative impedance converter for JAWS load compensation

September 10, 2020
Author(s)
Jason Underwood, Stephen Pfeiffer, Geoffrey Palo
For accurate realization of the ac volt, the Josephson Arbitrary Waveform Synthesizer (JAWS) must not be overly loaded by the electrical network in which it is used. The interaction between the on-chip inductance and the stray capacitance in the network

Continued Growth of IEEE RAS Standards Efforts

September 10, 2020
Author(s)
Craig I. Schlenoff
This has been a very eventful quarter for standardization efforts within the IEEE Robotics and Automation Society (RAS). Even the virtual nature of the 2020 International Conference on Robotics and Automation (ICRA) could not slow down the momentum of the

Direct DC Voltages Comparison between two Programmable Josephson Voltage Standards at SCL

September 10, 2020
Author(s)
S. Yang, Stefan Cular, Alain Rufenacht, Charles J. Burroughs, Paul Dresselhaus, Samuel Benz, M. N. Ng
Standards and Calibration Laboratory (SCL) setup in 2018 a liquid helium based programmable Josephson voltage standard (PJVS) developed by the National Institute of Standards and Technology (NIST). The system was validated by direct comparison with a NIST

Electric-field imaging using polarized neutrons

September 10, 2020
Author(s)
Y.- Y. Jau, Daniel S. Hussey, Thomas R. Gentile, Wangchun Chen
We experimentally demonstrate that electrically neutral particles, neutrons, can be used to directly visualize the electrostatic field inside a target volume that can be physically isolated or occupied. Electric field images are obtained using a spin

Graphene/Polymer Nanocomposite Degradation by Ultraviolet Light: The Effects of Graphene Nanofillers and their Potential for Release

September 10, 2020
Author(s)
David Goodwin, Shih Jia Shen, Ronald S. Lankone, Wendel Wohlleben, Tinh Nguyen, Li Piin Sung, Francois Perreault, Ana Barrios
The ultraviolet (UV)-induced degradation of graphene/polymer nanocomposites was investigated in this study. Specifically, the effect of few-layer graphene nanofillers on the degradation of a thermoplastic polyurethane (TPU) and the release potential of

In Situ Monitoring of Cu/Al Laser Welding using Laser Induced Fluorescence

September 10, 2020
Author(s)
Brian Simonds, Tran N. Tran, Paul A. Williams
We investigate laser spot welding of 200 µm thick Cu and Al foils using laser-induced fluorescence (LIF). The key to strong Cu/Al welds is limited intermetallic compound formation through controlled molten metal interaction time. For laser lap welds, Cu in

Radiation Pressure Laser Power Meter for Industrial Laser Machining

September 10, 2020
Author(s)
Aly Artusio-Glimpse, Ivan Ryger, Natalia A. Azarova, Paul A. Williams, John H. Lehman
Demonstration and validation of a linear radiation pressure-based high-power laser power meter is presented. To date, this device is the most promising real-time, absolute power meter for laser material processing where power monitoring is crucial.

Simultaneous High-speed X-ray Transmission Imaging and Absolute Dynamic Absorptance Measurements during High-power Laser-metal Processing

September 10, 2020
Author(s)
Brian Simonds, Jack R. Tanner, Alexandra B. Artusio-Glimpse, Paul A. Williams, Niranjan Parab, Cang Zhao, Tao Sun
During high-power laser metal processing, the absorbed light is intimately related to the molten metal cavity shape. For the first time, we directly and simultaneously observe this relationship by implementing state-of-the-art techniques of high-speed x

Accelerating Bubble Detachment in Porous Transport Layers with Patterned Through-Pores

September 9, 2020
Author(s)
Jason K. Lee, ChungHyuk Lee, Kieran F. Fahy, Pascal J. Kim, Kevin Krause, Jacob LaManna, Eli Baltic, Daniel S. Hussey, David L. Jacobson, Aimy Bazylak
Mass transport losses ultimately suppress gas evolving electrochemical energy conversion technologies, such as fuel cells and carbon dioxide electrolyzers, from reaching the high current densities needed to realize commercial success. In this work, we

Optical and electrical properties in Na and Rh co-doped Ruddlesden-Popper layered Ca3Ti2O7

September 9, 2020
Author(s)
Qiang Gu, Weifang Liu, Winnie Wong-Ng, Xingxing Wu, Yao Jiang, Chao Wang, Shuang Ma, Shouyu Wang
Layered perovskite Ca2.91Na0.09Ti2-xRhxO7 (x=0.00, 0.02, 0.04, 0.06) were synthesized by a conventional solid-state reaction. The two strongest peaks of XRD shift to the lower 2θ region with an increase of Rh content, demonstrating changing of lattice

Electrically Conductive 3D Metal-Organic Framework Featuring p-Acidic Hexaazatriphenylene Hexacarbonitrile Ligands with Anion-p Interaction and Efficient Charge-Transport Capabilities

September 8, 2020
Author(s)
Ashok Yadav, Dillip K. Panda, Shiyu Zhang, Wei Zhou, Sourav Saha
Owing to their unparalleled synthetic simplicity, structural tunability, and functional versatility, electrically conductive metal–organic frameworks (MOFs) have emerged as one of the most promising electronic materials of the 21 st century. With much of

Optical and Mechanical Design of a Telescope for Lunar Spectral Irradiance Measurements from a High-Altitude Aircraft

September 8, 2020
Author(s)
Clarence Zarobila, Steven Grantham, Steven W. Brown, John T. Woodward IV, Stephen Maxwell, Dana R. Defibaugh, Thomas C. Larason, Kevin Turpie
We have designed a non-imaging telescope for measurement of the spectral irradiance of the moon. The telescope was integrated into a wing pod of a NASA ER-2 research aircraft to measure lunar spectral irradiance during flight. The telescope and support

Protocol for Light-Shift Compensation in a Continuous-Wave Microcell Atomic Clock

September 8, 2020
Author(s)
Moustafa A. Hafiz, Remy Vicarini, Nicolas Passilly, Claudio Calosso, Vincent N. Maurice, Juniper Pollock, V Yudin, John Kitching, Rodolphe Boudot
Light shifts are known to be an important limitation to the mid- and long-term fractional frequency stability of different types of atomic clocks. In this article, we demonstrate the experimental implementation of an anti-light-shift interrogation protocol

Lymphatic Vessel on a Chip with Capability for Exposure to Cyclic Fluidic Flow

September 7, 2020
Author(s)
Parinaz Fathi, Glenn E. Holland, Dipanjan Pan, Mandy B. Esch
Lymph nodes comprise a complex organ system that is essential in regulating the development of host immune responses. Due to the complexity of lymph nodes and the lack of animal models that can accurately replicate the lymphatic functionality of humans

Development of NIST Atomic Databases and OnlineTools

September 5, 2020
Author(s)
Yuri Ralchenko, Alexander Kramida
Over the last 25 years, the atomic standard reference databases and online tools developed at the National Institute of Standards and Technology (NIST) provide users around the world with the highest-quality data on various atomic parameters (e.g., level

Restricting Orbital Angular Momentum by Transverse Coherence

September 5, 2020
Author(s)
Ronald L. Cappelletti, John T. Vinson
A traveling wave or wave packet may possess orbital angular momentum in the form of a phase vortex about its axis of propagation. These orbital angular momentum states are a general wave phenomenon, and, as such, can be realized for individual wave packets

Dynamic Compression Strength of Ceramics: What was Learned from an Interlaboratory Round Robin Exercise

September 4, 2020
Author(s)
Jeffrey Swab, Wayne Chen, James Hogan, Hangjie Liao, Calvin Lo, Steven Mates, Christopher Meredith, John Pittari, Richard Rhorer, George Quinn
The dynamic compressive strength of a commercial alumina was determined by five participants using the Split-Hopkinson pressure bar (SHPB) method with a dumbbell-shaped specimen. Each participant used their own SHPB test apparatus and imaging set-up to

Measurement and Standardization Challenges for Exosome-Based Delivery Vectors

September 4, 2020
Author(s)
Bryant C. Nelson, Lili Wang, Samantha D. Maragh, Paul C. DeRose, Elzafir B. Elsheikh, Wyatt N. Vreeland, Ionita Ghiran, Jennifer Jones
Extracellular vesicles (EVs), and in particular exosomes, have the potential to revolutionize the development and efficient delivery of clinical therapeutics. In this Perspective, we focus on providing a brief introduction to the landscape of exosome-based
Displaying 5751 - 5775 of 74178