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.
How heartwood differs—spectral view of heartwood formation. (a) Average spectra of the cell corner and (b) cell wall from sapwood, transition zone and heartwood of pine and (c, d) a zoom into the two most important aromatic wavenumber regions for pinosylvins.
