Wim Noorduin

Researchers formed hierarchically complex structures by controlling the growth of crystals in a solution. Here, a coral shape was nucleated on top of a spiral. (The scanning electron microscope view is false-colored, but represents the actual color of the structure.)

Imagine peering into a microscope and finding yourself in a garden.

That's the case at Harvard School of Engineering and Applied Sciences, where researchers have found a way to shape microscopic crystals into complex and often beautiful structures.

Inspired by coral reefs, seashells and other naturally occurring complex mineral structures, postdoctoral fellow Wim L. Noorduin and Harvard colleagues have been researching ways to create similar designs.

These "flowers" were created by mixing barium chloride and sodium silicate, also known as waterglass, in a beaker of water. The resulting reaction combines with carbon dioxide in the air to create crystals made of barium carbonate in the water.

Noorduin found that as the crystals self-assembled, he could control their shape, size and direction of growth by altering the temperature, the amount of carbon dioxide allowed into the reaction and the acidity of the water.

Increasing the carbon dioxide levels creates the broad, flat leaves of those mineral flowers, for example. Fluctuating the acidity level creates the ruffled wave in the petals.

Wim Noorduin

This false-colored photomicrograph shows a red coral structure with green "stems" grown inside the cavities of the coral. While the stems are growing, researchers opened them with a pulse of carbon dioxide to produce the purple structure.

Wim Noorduin

A field of microscopic tulips takes shape in this false-colored scanning electron microscope image.

Laura Hendriks / Wim Noorduin

This complex microscopic bouquet was formed by first nucleating green stems inside purple vases, after which the stems were opened during growth to form the blue part.

The curved petals, slender stems and jagged thorns, formed by the carbonate-silica crystals as they grew, demonstrate the effectiveness of Noorduin's technique. The team was able to create the structures on glass slides and metal plates as well, and even grew a "garden" of flowers in front of the Lincoln Memorial that's imprinted on the back of a penny.

The images were taken with a scanning electron microscope, which uses electrons to create images of microscopic images. The color was added digitally.

"When you look through the electron microscope, it really feels a bit like you’re diving in the ocean, seeing huge fields of coral and sponges … Sometimes I forget to take images because it's so nice to explore," Noorduin said in Harvard's press release.

Crystal manipulation has more applications than just the aesthetic. Aside from the valuable insight into the way silicon-based structures are formed in nature, this technique can be used in nanotechnology fields such as optics and electronics.

Noorduin's findings follow a similar discovery from Harvard biologist Howard Berg, who found that certain bacterial colonies take intricate geometric shapes in response to concentrations of chemicals around them.

Noorduin's paper, "Rationally Designed Complex, Hierarchical Microarchitectures," was published in the journal Science on May 17.

Email jscharr@technewsdaily.com or follow her @JillScharr. Follow us @TechNewsDaily, on Facebook or on Google+.

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U.S. Department of Agriculture Natural Resources Conservation Service / Jeff McMillian

The elegant Nerium oleander, the blossoms of which are crimson, magenta or creamy white, is one of the most toxic plants in the world. Every part of the plant, from its stem to its sap, is incredibly poisonous if ingested. That should gives the flowers something to communicate in their electrical fields.

By Jennifer Viegas
Discovery

Flowers may be silent, but scientists have just discovered that electric fields allow them to communicate with bumblebees and possibly other species, including humans.

 It’s well known that color, shape, pattern and fragrances allow flowers to connect with pollinators, but the new study, published in the journal Science, adds electricity to this already impressive lineup.

“We just now have discovered that electrical potentials, an unavoidable by-product of flying in air for bumblebees and being grounded for the flower, is being exploited to benefit both parties,” co-author Daniel Robert told Discovery News. It’s “another example of the beauty of evolution,” added Robert, a professor in the University of Bristol’s School of Biological Sciences.

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He explained that bees have a positive electrical charge because they fly in air, which is full of all kinds of tiny particles, such as dust and charged molecules. Friction from these particles causes bees to lose electrons, leaving bumblebees positively charged.

Flowers, on the other hand, “are electrically connected to ground,” he said. Unlike copper wire, which transfers charges very quickly, plants conduct electricity very slowly and tend to possess a negative charge.

For the study, Robert and his team placed petunia flowers in an area with free-flying foraging bees. The researchers then studied how interactions between the two changed the electric fields and the bees’ behavior.

They determined that when a bee lands on a flower, this generates its own electrical field, and therefore a force. It’s as though a mini spark results when the two connect.

Robert and his colleagues believe “that the bee can sense this electrically induced force.” It appears to improve the bee’s memory of flower rewards, such as pollen and nectar, affecting later foraging.

The flower, in turn, is electrically changed for a short period after the interaction.

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“Bees have what has been observed to be flower constancy, (meaning that) once they forage, they tend to keep going to one type of flower, and they keep going until they feel that the rewards are not worth it anymore,” Robert said.

“We think that flowers have their say in that strategy, and inform the bees that the supply will be back soon,” he added. This is “a dynamic interaction.”

This process of flower informing brings together all of the plant’s communication tools. It appears that electricity boosts the power of the other tools, such as color.

“We have demonstrated that when there is an electric field present, even a mild one, bees can learn the difference between two colors faster,” Robert said. “So, like in a commercial advertisement, the main and obvious message can be supported by co-lateral cues that do not necessarily convey information about the product, but are easily associated with it.”

Thomas Seeley, chairman of the Cornell University Department of Neurobiology and Behavior, is intrigued by the possibility that electric fields may facilitate rapid and dynamic communication between flowers and pollinators.

Seeley told DNews that the study "opens a window on a sensory system of the bees that we had no idea existed and no idea was used by bees during foraging."

More research is needed on this newly discovered phenomenon, but it is even possible that electrical field changes happen when humans and other animals, such as birds, interact with flowers.

As Robert said, “When you bend over to sniff a flower, it will change (the flower’s electrical) potential. What the flower makes of that, I would not know… But I do hope very much that someone will take this up and look into it.”