Tiny diatoms boast enormous strength

February 8, 2016 by Lori Dajose, California Institute of Technology
The diatom species Thalassiosira pseudonana

Diatoms are single-celled algae organisms, around 30 to 100 millionths of a meter in diameter, that are ubiquitous throughout the oceans. These creatures are encased within a hard shell shaped like a wide, flattened cylinder—like a tambourine—that is made of silica. Researchers in the lab of Julia Greer, professor of materials science and mechanics in Caltech's Division of Engineering and Applied Science, have recently found that these shells have the highest specific strength—the strength at which a structure breaks with respect to its density—of any known biological material, including bone, antlers, and teeth.

The findings have been published in the February 9 issue of Proceedings of the National Academy of Science.

The shell, or frustule, of a diatom is porous, perforated by a honeycomb-like pattern of holes. There are several theories about the function of these intricate shell designs, including that they evolved to control fluid flow, for example, or to help the organisms acquire nutrients. Greer and her group propose that the holes also act as stress concentrators—"flaws" in the material that can suppress the propagation of cracks, which would lead to failure of the entire organism.

"Silica is a strong but brittle material. For example, when you drop a piece of glass, it shatters," says Greer. "But architecting this material into the complex design of these diatom shells actually creates a structure that is resilient against damage. The presence of the holes delocalizes the concentrations of stress on the structure."

The group plans to use design principles from diatoms to create resilient, bioinspired artificial structures.

Explore further: Deformation of 3-D hierarchical nanolattices

More information: Microstructure provides insights into evolutionary design and resilience of Coscinodiscus sp. frustule, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1519790113

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Whydening Gyre
5 / 5 (2) Feb 08, 2016
designed, manufactured and just plopped right on the organism?
Fossil record doesn't show they just showed up fully formed, one day...
not rated yet Feb 08, 2016
I think I would have to go with some sort of biological reason for them. Stress is probably not the answer since there really wouldn't be any mechanical stress on them while just floating around in the oceans.
5 / 5 (2) Feb 09, 2016
There are several theories about the function of these intricate shell designs....that they evolved to control fluid flow, for example....

Using the word "evolve" is not science; it is junk science.
A scientific working for this sentence would be:
"There are several theories about the function of these intricate shell designs....that they are designed to control fluid flow, for example....

So when bacteria develops resistance using the word evolves is junk science?
Your faith is clouding your reason.

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