Powerful X-ray technique finds new degradation-inducing materials in
British shipwreck

Date:
October 27, 2021
Source:
Cell Press
Summary:
In 1545, King Henry VIII's favorite ship, the Mary Rose,
capsized and sank in the Battle of the Solent defending England
and Portsmouth from a French invasion fleet. The wreck remained
on the seabed until 1982 when it was salvaged in a widely viewed
televised event. Now, it is a time capsule for 16th century Tudor
society, and conservators are working to preserve it for future
generations. Scientists use X-ray analysis to identify previously
undetected products in the wood -- nanoparticles originating from
underwater bacterial activity.



FULL STORY ==========================================================================
In 1545, King Henry VIII's favorite ship, the Mary Rose, capsized and
sank in the Battle of the Solent defending England and Portsmouth from
a French invasion fleet. The wreck remained on the seabed until 1982
when it was salvaged in a widely viewed televised event. Now, it is
a time capsule for 16th century Tudor society, and conservators are
working to preserve it for future generations. In research published
in the journal Matter on October 27th, scientists use X-ray analysis
to identify previously undetected products in the wood -- nanoparticles originating from underwater bacterial activity.


==========================================================================
"It is remarkable that this technique at the ESRF allows us not
only to image and locate these nanoparticles in Mary Rose wood, but
also to evaluate their structure. This is the first time zinc sulfide nanostructures -- the bacterial byproducts -- have been observed in Mary
Rose wood," says senior author Serena Cussen, head of the Department of Materials Science and Engineering at the University of Sheffield, UK.

As Eleanor Schofield (@E_Schofield), co-author on this work and deputy
chief executive at the Mary Rose Trust explains, "Centuries spent
under the seabed saw the uptake of harmful iron and sulfur species
by the Mary Rose hull, which were produced through degradation of
metal fixtures and artifacts and anaerobic sulfur-reducing bacteria, respectively." To compensate for degradation of the wood and loss of
material, conservators impregnated the Mary Rose with a polymer called poly-ethylene glycol (PEG).

This prevents shrinkage upon drying and gives the ship mechanical
stability so it can be displayed for the public. In the final stage
of active conservation, the Mary Rose was dried, and this exposure to
oxygen has led to the formation of acidic species which can create even
more damage to the wood.

"Up to now, it has not been possible to obtain quantitative structural information about the nature of these potentially harmful species
residing within Mary Rose wood," says Cussen. "This is because it is
really challenging to assess the range of materials present within archaeological samples, which can include amorphous, nanostructured,
and polycrystalline materials." When characterizing precious cultural artifacts like the Mary Rose, it is important to use a method that does
not damage the material. Cussen and her colleagues used a technique at
the ESRF called X-ray computed tomography to provide detailed structural information about the wide range of materials present in the Mary Rose
hull without destroying the sample.

The researchers mapped out where compounds were lodged in the material
by combining X-ray computed tomography with pair distribution function
analysis (ctPDF). Using these two methods together allows them to
determine the distance between the PEG and the nanoparticle products
and therefore assess where potential threats lie within the wood.

"What our results have done is alert conservators to these previously
unknown deposits and expand the study of degradation-inducing
materials. Knowing the structure of these potentially harmful species
also allows us to design targeted treatments for their future removal,"
says Cussen. In collaboration with the Mary Rose Trust, her team is also developing a series of magnetic nanoparticle-based treatments to target
and remove these harmful deposits within artifacts.

========================================================================== Story Source: Materials provided by Cell_Press. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Kirsten M.O/. Jensen, Esther Rani Aluri, Enrique Sanchez Perez,
Gavin
B.M. Vaughan, Marco Di Michel, Eleanor J. Schofield, Simon
J.L. Billinge, Serena A. Cussen. Location and characterization
of heterogeneous phases within Mary Rose wood. Matter, 2021; DOI:
10.1016/j.matt.2021.09.026 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211027121945.htm

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