Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2021 Jan 8;126:126001. doi: 10.6028/jres.126.001

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

The Journal of Research of the National Institute of Standards and Technology is a publication of the U.S. Government. The papers are in the public domain and are not subject to copyright in the United States. Articles from J Res may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.

PMC Copyright notice

graphic file with name jres-Image032.jpg — Notched Rectangle (2D) Tetrahedron (3D)

graphic file with name jres-Image020.jpg — Notched Rectangle (2D) Tetrahedron (3D)