There’s the shiny, light-scattering texture of blue morpho butterfly wings, the rough, drag-reducing texture of shark skin and the sticky, yet water-repelling texture of rose petals.

But how to use those natural textures and properties in the engineered world? Could the water-repelling, ultrahydrophobic texture of a lotus plant somehow be applied to an aircraft wing as an anti-icing device? Previous attempts have involved molding polymers and other soft materials, or etching patterns on hard materials that lacked accuracy and relied on expensive equipment. But what about making inexpensive, molded metallic biostructures?

Iowa State University’s Martin Thuo and the students in his research group have found a way in their pursuit of “frugal science/innovation,” what he describes as “the ability to minimize cost and complexity while providing efficient solutions to better the human conditions.”

For this project, they’re taking their previous development of liquid metal particles and using them to make perfectly molded metallic versions of natural surfaces, including a rose petal. They can do it without heat or pressure, and without damaging a petal.

They describe the technology they’re calling BIOMAP in a paper recently published online by Angewandte Chemie, a journal of the German Chemical Society. Thuo, an associate professor of materials science and engineering with a courtesy appointment in electrical and computer engineering, is the corresponding author. Co-authors are all Iowa State students in materials science and engineering: Julia Chang, Andrew Martin and Chuanshen Du, doctoral students; and Alana Pauls, an undergraduate.

Iowa State supported the project with intellectual property royalties generated by Thuo.

“This project comes from an observation that nature has a lot of beautiful things it does,” Thuo said. “The lotus plant, for example, lives in water but doesn’t get wet. We like those structures, but we’ve only been able to mimic them with soft materials, we wanted to use metal.”

Key to the technology are microscale particles of undercooled liquid metal, originally developed for heat-free soldering. The particles are created when tiny droplets of metal (in this case Field’s metal, an alloy of bismuth, indium and tin), are exposed to oxygen and coated with an oxidation layer, trapping the metal inside in a liquid state, even at room temperature.

The BIOMAP process uses particles of varying sizes, all of them just a few millionths of a meter in diameter. The particles are applied to a surface, covering it and form-fitting all the crevices, gaps and patterns through the autonomous processes of self-filtration, capillary pressure and evaporation.

A chemical trigger joins and solidifies the particles to each other and not to the surface. That allows solid metallic replicas to be lifted off, creating a negative relief of the surface texture. Positive reliefs can be made by using the inverse replica to create a mold and then repeating the BIOMAP process.

“You lift it off, it looks exactly the same,” Thuo said, noting the engineers could identify different cultivars or roses through subtle differences in the metallic replicas of their textures.

Importantly, the replicas kept the physical properties of the surfaces, just like in elastomer-based soft lithography.

“The metal structure maintains those ultrahydrophobic properties — exactly like a lotus plant or a rose petal,” Thuo said. “Put a droplet of water on a metal rose petal, and the droplet sticks, but on a metal lotus leaf it just flows off.”

Those properties could be applied to airplane wings for better de-icing or to improve heat transfer in air conditioning systems, Thuo said.

That’s how a little frugal innovation “can mold the delicate structures of a rose petal into a solid metal structure,” Thuo said. “This is a method that we hope will lead to new approaches of making metallic surfaces that are hydrophobic based on the structure and not the coatings on the metal.”

Researchers from the Centre de Recherches Petrographiques et Geochimiques (CRPG, CNRS/Universite de Lorraine) in Nancy, France, including one who is now a postdoctoral fellow at Washington University in St. Louis, determined that a type of meteorite called an enstatite chondrite contains sufficient hydrogen to deliver at least three times the amount of water contained in the Earth’s oceans, and probably much more.

Enstatite chondrites are entirely composed of material from the inner solar system — essentially the same stuff that made up the Earth originally.

“Our discovery shows that the Earth’s building blocks might have significantly contributed to the Earth’s water,” said lead author Laurette Piani, a researcher at CPRG. “Hydrogen-bearing material was present in the inner solar system at the time of the rocky planet formation, even though the temperatures were too high for water to condense.”

The findings from this study are surprising because the Earth’s building blocks are often presumed to be dry. They come from inner zones of the solar system where temperatures would have been too high for water to condense and come together with other solids during planet formation.

The meteorites provide a clue that water didn’t have to come from far away.

“The most interesting part of the discovery for me is that enstatite chondrites, which were believed to be almost ‘dry,’ contain an unexpectedly high abundance of water,” said Lionel Vacher, a postdoctoral researcher in physics in Arts & Sciences at Washington University in St. Louis.

Vacher prepared some of the enstatite chondrites in this study for water analysis while he was completing his PhD at Universite de Lorraine. At Washington University, Vacher is working on understanding the composition of water in other types of meteorites.

Enstatite chondrites are rare, making up only about 2 percent of known meteorites in collections.

But their isotopic similarity to Earth make them particularly compelling. Enstatite chondrites have similar oxygen, titanium and calcium isotopes as Earth, and this study showed that their hydrogen and nitrogen isotopes are similar to Earth’s, too. In the study of extraterrestrial materials, the abundances of an element’s isotopes are used as a distinctive signature to identify where that element originated.

“If enstatite chondrites were effectively the building blocks of our planet — as strongly suggested by their similar isotopic compositions — this result implies that these types of chondrites supplied enough water to Earth to explain the origin of Earth’s water, which is amazing!” Vacher said.

The paper also proposes that a large amount of the atmospheric nitrogen — the most abundant component of the Earth’s atmosphere — could have come from the enstatite chondrites.

“Only a few pristine enstatite chondrites exist: ones that were not altered on their asteroid nor on Earth,” Piani said. “In our study we have carefully selected the enstatite chondrite meteorites and applied a special analytical procedure to avoid being biased by the input of terrestrial water.”

Coupling two analytical techniques — conventional mass spectrometry and secondary ion mass spectrometry (SIMS) — allowed researchers to precisely measure the content and composition of the small amounts of water in the meteorites.

Prior to this study, “it was commonly assumed that these chondrites formed close to the sun,” Piani said. “Enstatite chondrites were thus commonly considered ‘dry,’ and this frequently reasserted assumption has probably prevented any exhaustive analyses to be done for hydrogen.”

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Materials provided by Washington University in St. Louis. Original written by Talia Ogliore. Note: Content may be edited for style and length.

Helminths are parasitic worms and they infect an estimated 1.5 billion people worldwide. The worms are transmitted through eggs that are present in human feces and can contaminate soil and water. While some infections cause only mild symptoms, others are associated with chronic malnutrition and physical impairment, particularly in children.

In the new work, Adrian Smith of the University of Oxford, UK, and colleagues analyzed 589 grave samples from 7 European sites dated between 680 and 1700 CE. Samples were taken from the pelvises of skeletons. Data associated with the sites allowed them to assess the influence of age, sex and community size on helminth infection rates.

Two soil transmitted nematodes — Ascaris spp. and Trichuris trichiura — were identified at all locations, and two food derived cestodes — Diphyllobothrium latum and Taenia spp. — were found at 4 sites. No helminths were found in any control samples. The rates of nematode infection in the medieval population were estimated at 8.5% (range 1.5%-25.6%) for T. trichiura and 25.1% (range 9.3%-42.9%) for Ascaris, similar rates to those seen in modern endemically infected populations. There were no differences in infection rates by sex or community population size, but infection rates were most common among children.

“Since the prevalence of medieval soil transmitted helminth infections mirror those in modern endemic countries, the factors affecting helminth decline in Europe may also inform modern intervention campaigns,” the researchers say. “The parasites in past communities can tell us a lot about living conditions including hygiene, sanitation and even culinary practices.”

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