A building's architectural plans map out what's needed to keep it from falling down. But design is not just functional: often, it's also beautiful, with lines and shapes that can amaze and inspire.
Beautifully crafted architecture isn't limited to human-made structures. Nature is rife with ornate structures, from the spiraling fractal patterns of seashells to the intricately woven array of neurons in the brain.
These are four sets of pollen grains (from top left to bottom right: Alisma lanceolatum, Galium wirtgenii, Gaillardia aristata, Gomphrena globosa), showing the scanning electron microscopy image alongside the simulation of the physical model for the same geometry.
Credit: PalDat.org (SEM images) and Asja Radja (simulations)
Usage Restrictions: May only be used with appropriate caption or credit.
The microscopic world contains its fair share of intricate patterns and designs, such as the geometric patterns on individual grains of pollen. Scientists have been fascinated by these intricate structures, which are smaller than the width of a human hair, but have yet to determine how these patterns form and why they look the way they do.
Researchers from the University of Pennsylvania's Department of Physics & Astronomy have developed a model that describes how these patterns form, and how pollen evolved into a diverse range of structures.
Graduate student Asja Radja was the first author of the study, and worked with fellow graduate student Eric M. Horsley and former postdoc Maxim O. Lavrentovich, who is now working at the University of Tennessee. The study was led by associate professor Alison Sweeney.
Radja analyzed pollen from hundreds of flowering plant species in a microscopy database, including iris, pigweed, amaranth, and bougainvillea. She then developed an experimental method that involved removing the external layer of polysaccharide "snot" from the pollen grains, and taking high-resolution microscopic images that revealed the ornate details of the pollen as they formed at a micrometer scale.
Sweeney and Radja's original hypothesis was that the pollen spheres are formed by a buckling mechanism. Buckling occurs when materials are strong on the outside but pliable on the inside, causing the structure to shrink inwards and form divots, or "buckles," on the surface. But the data they collected didn't align with their initial idea.
"Alison taught me that with any biological system, you have to really stare at it in order to figure out exactly what's going on," Radja says about the hours she spent studying pollen images.
One of the key challenges with studying pollen was looking at the problem with a fresh perspective in order to think about what underlying physics could explain the structures.
The solution, published in Cell, represents the first theoretical physics-based framework for how pollen patterns form. The model states that pollen patterns occur by a process known as phase separation, which physicists have found can also generate geometric patterns in other systems.
An everyday example of phase separation is the separation of cream from milk; when milk sits at room temperature, cream rises to the top naturally without any additional energy, like mixing or shaking.
Radja was able to show that the "default" tendency of developing pollen spores is to undergo a phase separation that then results in detailed and concave patterns. "These intricate patterns might actually just be a happy consequence of not putting any energy into the system," says Radja.
However, if plants pause this natural pattern-formation process by secreting a stiff polymer that prevents phase separation, for example, they can control the shapes that form. These plants tend to have pollen spores that are smoother and more spherical.
Surprisingly, the smooth pollen grains, which require additional energy, occur more frequently than ornate grains, suggesting that smooth grains may provide an evolutionary advantage.
This biophysical framework will now enable researchers to study a much larger class of biological materials. Sweeney and her group will see if the same rules can explain much more intricate architectures in biology, like the bristles of insects or the cell walls of plants.
Sweeney's group is also working with materials engineer Shu Yang of Penn's School of Engineering and Applied Science to develop pollen-inspired materials. "Materials that are like pollen often have super-hydrophobicity, so you can very intricately control how water will interact with the surface," says Sweeney. "What's cool about this mechanism is that it's passive; if you can mimic the way pollen forms, you can make polymers go where you want them to go on their own without having to do complicated engineering that's expensive and hard to replicate."
The research was supported by the Kaufman Foundation New Initiative Award, the Packard Foundation Fellowship, the National Science Foundation CAREER Award 1351935, and a Simons Investigator Grant.
Erica K. Brockmeier | EurekAlert!
Convenient location of a near-threshold proton-emitting resonance in 11B
29.05.2020 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences
A special elemental magic
28.05.2020 | Kyoto University
In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".
Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...
Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.
researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...
Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.
When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...
Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.
Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...
Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.
A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...
19.05.2020 | Event News
07.04.2020 | Event News
06.04.2020 | Event News
29.05.2020 | Materials Sciences
29.05.2020 | Materials Sciences
29.05.2020 | Power and Electrical Engineering