ADVANCED MATERIALS & PROCESSES | NOVEMBER/DECEMBER 2023 6 METALS | POLYMERS | CERAMICS has eliminated the need for harmful chemicals. The microbe selectively adsorbs—or clings—to these rare earth elements, making it an ideal candidate to carry out an environmentally friendly purification procedure. Generally, S. oneidensis feeds on f-block elements residing in the sixth row of the periodic table, known as the lanthanides. Characterizing the S. oneidensis’s genome allows scientists to tweak its preference for processing the other rare earth elements. The researchers screened 3373 parts of the S. oneidensis genome and found 242 genes that influence it. The mutant genes found in the bacteria by the scientists can reduce the length of that rare earth element purification process by almost one-third— compared with the wild variety of S. oneidensis—and offers a roadmap for honing this green method. “Our work points to key genes that control membrane composition that are traditionally responsible for cell adhesion and biofilm formation in rare earth element biosorption,” says lead researcher Sean Medin. He says their work has the potential to make processing rare earths cleaner and scalable. “Currently all the purification of rare earth elements is done abroad, due to stringent environmental regulations and high infrastructure costs of building a separations plant,” he continues. IMPROVING WEARABLE ELECTRONICS A new self-healing, super flexible, and highly conductive material suitable for stretchable electronic circuitry was created by researchers at the National University of Singapore. This breakthrough could significantly improve the performance of wearable technologies, soft robotics, smart devices, and more. The newly engineered material, called the Bilayer Liquid-Solid Conductor (BiLiSC), can stretch up to a remarkable 22 times its original length without sustaining a significant drop in its electrical conductivity. Achieving this mechano-electrical property enhances the comfort and effectiveness of the human-device interface and opens up a wide array of opportunities for its use in healthcare wearables and other applications. According to the researchers, the liquid metal circuitry using BiLiSC allows these devices to withstand significant deformation and even self-heal to ensure electronic and functional integrity. nus.edu.sg. MICROBES REFINE RARE EARTH ELEMENTS To date, rare earth element purification processes have relied heavily on organic solvents and harsh chemicals. Now, scientists from Cornell University, Ithaca, N.Y., recently characterized the genome of Shewanella oneidensis—a metal-loving bacteria with an affinity for rare earth elements— to replace harsh chemical processing with a benign practice called biosorption. Using microbes to selectively adsorb and purify rare earth elements, the research team Prof Lim Chwee Teck (le ) and Dr. Chen Shuwen have developed a novel liquid-metal material suitable for stretchable electronics. Scientists at Columbia University, the University of Connecticut, and the DOE’s Brookhaven National Laboratory fabricated a pure form of glass and coated specialized pieces of DNA with it. The result is a material that is four times stronger than steel with a density roughly five times lower, making it both incredibly strong and lightweight. bnl.gov. BRIEF These Petri dishes containing microbes will eventually be used to dissolve the mineral monazite for extracting rare earth elements.
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