A symbiotic culture of specialized yeast and bacteria can generate tough materials able to perform a variety of functions.
Category: materials – Page 82
Why It’s Hard to Break Plastics
Posted in materials
The crack resistance of polymer materials is explained by a new model that incorporates a network of stretchable polymer chains.
Plastics and other polymer materials are often very resistant to cracking—a fact that models have not been able to accurately capture. Now a research team has developed a model of polymer fracture that explains how these materials remain intact under intense stretching. [1]. The key to the model is that it accounts for polymer chains that extend deep within the material and that can share the strain that would break a material with more localized chains. The insights could lead to the development of new structures with an enhanced resistance to shocks.
Researchers typically study fracture by cutting a small notch or crack into a material and then pulling it apart. The amount of work required to enlarge the crack is called the fracture energy. For most materials, the fracture energy is equal to the energy it takes to break the molecular bonds located along the crack tip, where the enlargement occurs. For polymers, the situation is more complex, as the molecules are long chains. In the 1960s, theorists came up with a model of polymer fracture based on the rupture of individual chains at the crack tip [2]. “The problem is that this model underestimates by a factor of 10 to 100 the energy required to fracture a polymer material,” says Xuanhe Zhao from the Massachusetts Institute of Technology.
A dynamical tension model captures how cells swap places with their neighbors in epithelial tissues, explaining observed phase transitions and cellular architectures.
Epithelial tissues line the surfaces of every organ in our bodies. In the earliest stages of organ development and in wound healing, the cells that make up these simple sheets constantly rearrange themselves, exchanging positions like molecules in a liquid. But this fluidization is often hindered by the formation of multicell clusters, whose origins remain unclear. Using a dynamical structural model, Fernanda Pérez-Verdugo and Shiladitya Banerjee of Carnegie Mellon University in Pennsylvania now identify the mechanical prerequisites that lead to the formation and dissolution of these stabilized clusters [1]. They show how dynamic feedback between tension and strain controls the tissue’s material properties.
Existing models of tissue fluidity treat epithelial tissues as foam-like, polygonal networks of cells whose edges join at triple points. However, these models fail to explain the mechanisms underpinning cell neighbor exchanges. In particular, they oversimplify such exchanges by treating them as an instantaneous process, thereby avoiding the impact of exchanges that stall midprocess. One resulting discrepancy with experimental results is the absence of stable “rosette” structures that are observed in developing tissues where four or more cells meet.
The material could also be used in water filters.
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Now, ETH Zurich researchers at the Laboratory of Soft and Living Materials, led by former ETH Professor Eric Dufresne, have managed to replicate the material in the laboratory to be used in applications such as batteries and water filters.
Insider Brief.
Scientists report on a new approach that can significantly improve the study and understanding of entanglement in quantum materials.
The researchers were led by Peter Zoller at the University of Innsbruck and the Institute of Quantum Optics and Quantum Information of the Austrian Academy of Sciences.
Monolithic 3D integration of electronics based on fully 2D materials is demonstrated in the performance of artificial intelligence tasks.
Multifunctional computer chips have evolved to do more with integrated sensors, processors, memory and other specialized components. However, as chips have expanded, the time required to move information between functional components has also grown.
“Think of it like building a house,” said Sang-Hoon Bae, an assistant professor of mechanical engineering and materials science at the McKelvey School of Engineering at Washington University in St. Louis. “You build out laterally and up vertically to get more function, more room to do more specialized activities, but then you have to spend more time moving or communicating between rooms.”
To address this challenge, Bae and a team of international collaborators, including researchers from the Massachusetts Institute of Technology, Yonsei University, Inha University, Georgia Institute of Technology and the University of Notre Dame, demonstrated monolithic 3D integration of layered 2D material into novel processing hardware for artificial intelligence (AI) computing.
The new study estimates $25.7 billion lost annually in waste management and damage to marine ecosystems.
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Cigarette filters were marketed under the guise of addressing health concerns by providing a false impression of safety. These filters, made of a material called cellulose acetate, don’t actually reduce health risks and can even harm the lungs. The cellulose acetate fibers have been shown to deposit into the lungs of smokers.
Google DeepMind and Lawrence Berkeley National Laboratory researchers recently introduced Graph Networks for Materials Exploration (GNoME), an AI tool to discover new materials and predict material stability.
“We are releasing 381K stable materials to help scientists pursue materials discovery breakthroughs,” said Pushmeet Kohli, head of research (AI for science, robustness and reliability) at DeepMind.
Check out the GitHub repository here.
A recent study published in Communications Earth & Environment examines how lunar samples collected and returned by Apollo astronauts contain traces of hydrogen produced by the solar wind. The samples, labeled 79221, were collected during surface activities on Apollo 17 in 1972, and holds the potential to help scientists and engineers better understand how hydrogen within these samples can be used for future space exploration, specifically pertaining to in-situ resource utilization (ISRU).
The practice of ISRU involves using resources directly available at a location without the need of resupply from an outside source. In this case, future lunar astronauts would want to use resources already present on the Moon for their survivability needs rather than having constant resupply from the Earth, which can be both costly and risky.
“Hydrogen has the potential to be a resource that can be used directly on the lunar surface when there are more regular or permanent installations there,” said Dr. Katherine D. Burgess, who is a geologist in the U.S. Naval Research Laboratory (NRL) Materials Science and Technology Division and lead author of the study. “Locating resources and understanding how to collect them prior to getting to the Moon is going to be incredibly valuable for space exploration.”