Silk, shown here in reeled form and cocoons, can be fused under carefully controlled conditions of temperature and pressure to make exceptionally strong materials. | Photo Credit: Qichen ZhouTurning silk fibres into supermaterialsTHE versatility and strength of silk is well known. Humans have used it for textiles and clothing for thousands of years. In nature, insects, including moths, and spiders use silk to form ropes, nets, glue, armour, and sensors. More recently, silk has been successfully engineered for biomedical implants, electronic devices, and other advanced applications by dissolving silk fibres and rebuilding them into new forms. However, the process involves the use of large amounts of water, chemicals, energy, and time.Now, a collaboration between Tufts University (Massachusetts), Imperial College London, and the University of Michigan has led to the development of a significantly improved method of transforming silk into solid materials that preserves and enhances the natural strength of silk fibres. These materials were made by fusing silk fibres under carefully controlled conditions of temperature and pressure without synthetic additives. These were found to outperform bone and wood and come close to Kevlar in tensile toughness. The research work was published in Nature Sustainability.“The [old] process breaks down the natural fibres into the individual silk fibroin proteins before processing them into new shapes, so we lose a lot of the inherent strength of the original fibres,” said Chunmei Li of the Tufts School of Engineering. “With this new method, there’s no need to dissolve the silk; we simply align the fibres and apply heat and pressure, and they fuse together in one step.”This seemingly simple change was shown to preserve the original structure of the silk fibres and retain the features that give the resulting material exceptional strength, thus marking a significant improvement. The fused silk material was produced in the laboratory for multifunctional and sustainable polymer composites at Imperial College London by Emiliano Bilotti in collaboration with Li and David Kaplan of Tufts University.The new process begins with reels of commercially available silk moth cocoon fibres from textile manufacturing supplies. These are then treated with a mild sodium carbonate solution to remove sericin, the sticky adhesive covering the fibres that helps insects build the cocoon structure. The fibres are pulled from the bath to help align them and then subjected to hot-pressing. During the heating, parts of the silk’s molecular structure become mobile, allowing neighbouring fibres to bond together.“The silk is like a composite,” Kaplan explained. “There is a more mobile, amorphous phase of the fibre proteins, and there is the part of the protein chain that folds to form sheet-like surfaces that stack up into crystalline structures. Together, they give silk fibres their strength, toughness, and flexibility. But it’s the mobile part that allows the fibres to fuse together under heat and pressure.”The extent of fusion between fibre bundles depends on the amount of heat and pressure applied. While lower temperatures and pressures lead to a looser structure, higher temperatures and pressures result in a denser, generally stronger material. Too high temperatures result in a breakdown of the fibres and brittleness. The optimal processing window was found to be between 1250C and 2150C and pressures of between 1,900 and 9,800 atmospheres. The final product is a remarkably strong material that retains most of the molecular organisation of the original silk along with a macrostructure of bundled and fused fibres.This fused silk has a hierarchical structure similar to wood. In both the materials, fibre bundles align in a common direction and bind together: ligin in wood and amorphous protein regions in fused silk. The bonding between the fibre bundles helps transfer stress between them, creating enormous strength throughout the structure, said the release from Tufts University.While the material is transparent to visible light, researchers at the University of Michigan found it has the unique property to polarise terahertz radiation, which has wavelengths between infrared and microwave. The Michigan team, led by Michael Kotov, is interested in its possible applications to 6G communications, which can transmit data hundreds of times faster than 5G. Polarisation could also increase the density of encoded information, the release said.Units 1&2 of the Tarapur Atomic Power Station. | Photo Credit: Tata Consulting EngineersRestart of Unit 2 of Tarapur Atomic Power Station after refurbishment approvedON May 7, the Atomic Energy Regulatory Board (AERB) approved the restart and continued operation of unit 2 of the Tarapur Atomic Power Station (TAPS) in Maharashtra following the successful completion of major refurbishment work undertaken by Nuclear Power Corporation of India Limited.The present refurbishment included complete replacement of reactor coolant recirculation piping with forged piping and fittings made of advanced corrosion-resistant stainless steel, the AERB press release said. The other safety upgrades included commissioning of the reactor Containment Filtered Venting System, Alternate Cooling Water System, etc.The AERB reviewed the results of the refurbishment, safety upgrades, and inspection-related assessments of TAPS unit 2 through its multi-tiered safety review process. Further, during the ongoing outage, inspection of critical reactor components such as the reactor pressure vessel welds was carried out towards assessment of ageing status and residual life. Significantly, the evaluations have shown that the reactor can continue safe operation with the normal maintenance and surveillance programme.TAPS unit 1 underwent a similar refurbishment and reviews after which the AERB permitted its restart at the end of December 2025.TAPS 1&2 are India’s first commercial nuclear power reactors and started their operation in 1969. These were constructed under a 1963 agreement between India and the US and were built by GE and Bechtel on the basis of the boiling water reactor design. Originally rated at 210 MWe, in 1989, their power capacities were downrated to 160 MWe due to several technical issues both units faced in the 1980s.(B5H10)Os(B5H10) sandwich and its isomer. | Photo Credit: Suvam SahaCarbon-free ferrocene opens up new possibilities for future materialsABOUT 75 years ago, scientists accidentally synthesised a compound called ferrocene in which the iron (Fe) atom is sandwiched between two carbon-hydrogen rings of the cyclopentadienyl group (C5H5): (C5H5)Fe(C5H5). This compound opened up a new era in transition metal chemistry and became an important reagent in catalysis, materials, biology, and medicine.Researchers at IIT Madras and the Indian Institute of Science (IISc) have successfully created for the first time a carbon-free boron alternative to ferrocene. The work was published in Science.The team used osmium (Os), a metal that falls in the same group of elements as Fe in the periodic table, to hold together rings made of boron and hydrogen. This new compound—(B5H10)Os(B5H10)—was seen to be very similar to the original ferrocene sandwich. It was also found that the bond holding the boron sandwich together is stronger than the carbon version because the boron rings have B-H and BHB hydrogen atoms so placed in the compound structure that they hold the metal atom more effectively than carbon rings.The new compound shows that boron can mimic carbon’s ability to form stable rings and complex structures. Understanding how such elements bond could also lead to the development of new types of materials in the future, the IISc press release said.For years, researchers, including Eluvathingal Jemmis of the IISc and Sundargopal Ghosh of IITM, have been working on the possibility of replacing carbon in ferrocene with B-1 (anion of boron atom, which has the same number of electrons as carbon). For over 15 years, the researchers have been investigating ways of stabilising polyhedral boranes (compounds made of boron and hydrogen) with other elements, including transition metals. Ideas from orbital engineering led them to try this new borane-osmium sandwich as a preferred target, which could be successfully synthesised in the laboratory.In the new structure, the flat borane rings, between which the osmium atom sits, are closer together than those in the carbon version, rendering the bonding stronger. While synthesising the compound, the team also discovered a different version of the molecule (isomer) in which a ring is attached in a unique way that was not seen in the carbon original, indicating that boron molecules can connect to metals in more ways than carbon can.“With the renaissance in the 2D chemistry of boron during the last decade—with borophenes, bilayer borophenes, and multilayer borophenes on the horizon—the possibility of metal sandwiched/intercalated bilayers and multilayers will be a reality soon,” said Jemmis. These materials can potentially rival graphene in many applications, the researchers believe.Also Read | Animal quirksAlso Read | A message from TarapurCONTRIBUTE YOUR COMMENTS