The Art of Dating Silk Textiles
A new mass spectrometry method will allow museum scientists to date ancient silks from samples that are far smaller than what is consumed during carbon-14 dating, the only other method that can date silk.
Mehdi Moini, a research scientist at the Smithsonian Institution’s Museum Conservation Institute (Suitland, Maryland), in collaboration with colleagues Kathryn Klauenberg and Mary Ballard, has developed a new mass spectrometry method that will allow museum scientists to date ancient silks from samples that are far smaller than what is consumed during carbon-14 dating, the only other method that can date silk.
To develop the technique, the Smithsonian team looked closely at aspartic acid residues in the silk protein extruded by silk worms. Over decades, these aspartic acid residues can turn into their mirror images, switching from the L-form to the D-form in a process called racemization. Moini’s team used mass spectrometry to calculate the ratio of D- to L-forms, and to thereby determine the age of silk textiles. They performed the analysis on 100 μg samples and smaller.
The researchers evaluated their technique on samples that included fresh silk from 2010; American civil war flags; a man’s silk suit from the 1700s; Turkish tapestries from the late 1500s; Egyptian silk yarns from 993 A.D.; and silk artifacts from China’s Warring States period, which occurred between 475 and 221 B.C.
Getting accurate IR spectra on monolayer of molecules
April 18th 2024Creating uniform and repeatable monolayers is incredibly important for both scientific pursuits as well as the manufacturing of products in semiconductor, biotechnology, and. other industries. However, measuring monolayers and functionalized surfaces directly is. difficult, and many rely on a variety of characterization techniques that when used together can provide some degree of confidence. By combining non-contact atomic force microscopy (AFM) and IR spectroscopy, IR PiFM provides sensitive and accurate analysis of sub-monolayer of molecules without the concern of tip-sample cross contamination. Dr. Sung Park, Molecular Vista, joined Spectroscopy to provide insights on how IR PiFM can acquire IR signature of monolayer films due to its unique implementation.
