ADVANCED MATERIALS & PROCESSES | APRIL 2024 12 SYNTHETIC SPIDER SILK In Japan, a group of interdisciplinary researchers at RIKEN successfully created a device that produces artificial spider silk. The artificial silk gland recreates the complex molecular structure of silk by mimicking the various chemical and physical changes that naturally occur in a living spider’s silk gland. Famous for its strength, flexibility, and light weight, spider silk has a tensile strength that is comparable to steel of the same diameter, and a strength-to-weight ratio that is unparalleled. In addition, it is biocompatible as well as biodegradable. However, the large-scale harvesting of spider silk has proven impractical for several reasons, leaving scientists with the challenge of synthesizing a similar material in the laboratory. Spider silk is a biopolymer fiber made from large proteins with highly repetitive sequences, called spidroins. Within the silk fibers are molecular substructures called beta sheets, which must be aligned properly for the fibers to possess their unique mechanical properties. Rather than trying to devise the process from scratch, RIKEN scientists took a biomimicry approach using microfluidics. The device developed by the researchers looks like a small rectangular box with tiny channels grooved into it. Precursor spidroin solution is placed at one end and then pulled toward the other end by means of negative pressure. As the spidroins flow through the microfluidic channels, they’re exposed to precise changes in the chemical and physical environment, which are made possible by the design of the microfluidic system. Under the correct conditions, the proteins self- assemble into silk fibers with their characteristic complex structure. The ability to artificially produce silk fibers using this method could provide numerous benefits, the researchers say, like reducing environmental impacts from current textile manufacturing practices. The silk material also has promising potential for biomedical applications such as sutures and artificial ligaments. www.riken.jp/en. VISUALIZING ATOMIC NUCLEI A new way to study the shapes of atomic nuclei and their internal building blocks was developed by a team of scientists from Brookhaven National Lab, Upton, N.Y., Wayne State University, Detroit, and the University of Jyvaskyla in EMERGING TECHNOLOGY Finland. The method relies on modeling the production of certain particles from high-energy collisions of electrons with nuclear targets. Such collisions will take place at the future Electron-Ion Collider (EIC) at Brookhaven. According to the researchers’ theoretical framework, results show that collisions that exclusively produce single mesons— a particle made of a quark and antiquark—offer insights into the largescale structure of the nucleus, such as its size and shape. Higher-momentum mesons can visualize nuclear structure at shorter length scales, including the arrangement of quarks and gluons within protons and neutrons. Because the measurements are done at much higher collision energy than traditional nuclear structure experiments, the interactions are sensitive to the gluon distributions inside the protons and neutrons of the nucleus. Measuring gluon distributions inside the nucleus—rather than the distribution of electric charge—will provide new insights into how these two distributions differ. This technique opens a new direction for research at the future EIC and could lead to important information that complements data from traditional nuclear structure experiments. It will help scientists understand how nuclear shapes evolve with energy and provide new information on nuclear structure that was previously inaccessible. bnl.gov, wayne.edu, www.jyu.fi/en. Mercury Systems Inc., Andover, Mass., signed a $96 million three-year subcontract with Raytheon. Mercury will deliver high-performance signal processing subsystems for the U.S. Army’s Lower Tier Air and Missile Defense Sensor, the latest air and missile defense sensor that will operate on the Army’s defense network. mrcy.com. BRIEF This microfluidic device is used for creating silk fibers. An electron collides with a deformed nucleus and produces a single vector meson (J/Psi).
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