A D V A N C E D M A T E R I A L S & P R O C E S S E S | S E P T E M B E R 2 0 2 2 5 COPPER NANOMESH MURDERS MICROBES Scientists from the University of Tokyo, the Korea Research Institute of Bioscience and Biotechnology, and the RIKEN Center for Emergent Matter Science, Japan, developed a wearable antimicrobial nanomesh material that sticks to skin, killing microbes almost instantly. The team first created tiny copper strands and spun them together randomly to build a mesh, then applied pressure to flatten it. At three microns thick, the result is so thin that it cannot be seen by the human eye or felt when touched. But it is bendable and stretchy, making it suitable for a variety of uses. One of the main products the team envisions is a surface cover for smartphones and tablets. Testing shows that the nanomesh does not affect device performance. The mesh could also be applied to surfaces that serve as common bacteria and virus transfer sites such as doorknobs and light switches. Another idea is to develop a coated glove that is so thin the user is unaware of its presence. This could provide the best protection possible because so many microbes are transferred through RESEARCH TRACKS hands. The researchers say their nanomesh is superior to copper films already in use because it is more potent due to its larger surface area, giving it more opportunity to kill microbes. www.u-tokyo.ac.jp/en. MEASURING MAGNETIZATION Researchers from Lancaster University, U.K., University of California San Diego, Moscow Institute for Physics and Technology, and Radboud University, the Netherlands, are discovering how quickly magnetization can be created in amaterial. The team studied iron and rhodium (FeRh), a common magnetic alloy that exhibits a transition in both its structure andmagnetismwhen heated just above room temperature. The scientists found that FeRh undergoes a transition into its ferromagnetic phase in three stages: the excitation of the laser pulse induces a large number of tiny magnetic domains in the material; magnetization A newly developed antimicrobial copper mesh kills microbes nearly instantly. of all domains aligns along one particular direction; and individual domains grow into a large single domain, completing the transition into its ferromagnetic phase. Understanding these stages in regard to inducing a well-defined magnetization with a light pulse enables the possibility of using FeRh in future data storage technology. The study involved using intense, ultrashort laser pulses to rapidly heat FeRh with a brief artificial stimulus lasting a quadrillionth of a second. When interacting with the material, the laser pulse raised the temperature by a few hundred degrees Celsius at timescales shorter than a billionth of a second. The team used a novel double pump time-resolved spectroscopy technique developed at Radboud University. Two laser pulses were used for double pumping: The first acts as an ultrafast heater while the second pulse one helps generate the electric field. By detecting this field at multiple time lapses between the two pulses, researchers were able to observe how quickly magnetization emerges in the material. www.lancaster.ac.uk. The temperature hysteresis of the FeRh magnetization shows a characteristic first-order phase transition. Courtesy of Nature Communications.
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