Produced by a multitude of mollusk species, nacre is widely used in jewelry and art. It is inlaid into musical instruments, furniture and decorative boxes. Fashioned into buttons, beads and a host of functional objects from pens to flatware, mother of pearl lends a lustrous iridescence to everyday objects.
In recent years, subjecting the material to the modern tools of scientific analysis, scientists have divined the fine points of nacre architecture and developed models to help explain its astonishing durability: 3,000 times more fracture resistant than the mineral from which it is made, aragonite.
Now, in a new report (Thursday, Feb. 16) in the Journal of the American Chemical Society (JACS), scientists from the University of Wisconsin-Madison show that nacre can also be deployed in the interest of science as a hard-wired thermometer and pressure sensor, revealing both the temperature and ocean depth at which the material formed.
"We found a strong correlation between the temperature at which nacre was deposited during the life of the mollusk and water temperature," explains Pupa Gilbert, a UW-Madison professor of physics and chemistry and the senior author of the new JACS report. "All other (temperature) proxies are based on chemical analyses and the relative concentration of different elements or isotopes. This could be our first physical proxy, in which the microscopic structure of the material tells us the maximum temperature and maximum pressure at which the mollusk lived."
The new study was conducted using mother of pearl from modern mollusks, but Gilbert notes that nacre is widespread in the fossil record going back 450 million years. If the techniques used by the Wisconsin group can be applied to fossil nacre, scientists can begin to accurately reconstruct a global record of ancient environments and environmental change.
"If the correlation holds, we would have a thermometer that goes back in time, a paleothermometer of how hot or cold water temperatures were when the nacre formed," says Gilbert.
The material also holds a distinctive signature—the thickness of the nacre layers — for the water depth at which the material was assembled by a mollusk, potentially providing even more insight into environmental conditions of the present and past.
"These are two independent parameters, measured by different aspects of nacre structure," the Wisconsin physicist explains. "The maximum temperature can be measured by how disordered the nacre crystal orientations are, while the maximum pressure can be taken from the thickness of the nacre layers."
Working with UW-Madison graduate student Ian C. Olson, the lead author of the JACS report, Gilbert subjected nacre from eight mollusk species from different environments to a technique capable of mapping the orientation of nacre crystals. From the different shells, they observed uneven thicknesses, widths and angles of the crystalline "bricks" that, together with an organic mortar, are laid down by the mollusk to form mother of pearl.
"We wondered why the shells were so different and concluded that the key parameters to test were the environmental ones, including maximum, minimum and mean annual temperatures as well as maximum and minimum water pressure, which depends on water depth," says Gilbert.
Comparing the structural maps of nacre from the different mollusks and environmental data from the places where the animals were collected, Olson, Gilbert and their collaborators found an extremely high correlation between the microscopic structural characteristics of their nacre specimens and the temperature and pressure data obtained from the various environments where they were collected.
Contributing to the new study were Reinhard Kozdon and John Valley, both of the UW-Madison department of geoscience. The work was funded by the U.S. National Science Foundation.
-- Terry Devitt (608) 262-8282, email@example.com
Pupa Gilbert | EurekAlert!
Typhoon changed earthquake patterns
03.07.2020 | GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre
Groundwater protection on Spiekeroog Island - first installation of a salt water monitoring system
01.07.2020 | Leibniz-Institut für Angewandte Geophysik (LIAG)
Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.
Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....
Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.
Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...
A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...
Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"
The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...
With an X-ray experiment at the European Synchrotron ESRF in Grenoble (France), Empa researchers were able to demonstrate how well their real-time acoustic monitoring of laser weld seams works. With almost 90 percent reliability, they detected the formation of unwanted pores that impair the quality of weld seams. Thanks to a special evaluation method based on artificial intelligence (AI), the detection process is completed in just 70 milliseconds.
Laser welding is a process suitable for joining metals and thermoplastics. It has become particularly well established in highly automated production, for...
02.07.2020 | Event News
19.05.2020 | Event News
07.04.2020 | Event News
03.07.2020 | Life Sciences
03.07.2020 | Studies and Analyses
03.07.2020 | Power and Electrical Engineering