Lifeboat Foundation

A combination of two techniques provides warning signs that the stress on a material will lead to failure.

Soft elastomers, such as rubber, plastic, and silicone, are used in thousands of products, such as gaskets, hoses, and inflatable rafts, but under stress, these materials tend to crack abruptly, without warning. Now, using an improved method to image structural changes in a sample under stress, researchers have shown that a subtle pattern of molecular motions at the surface of the material occurs several minutes before a final failure [1]. With development, they believe the technique may help engineers monitor materials while in use and detect failures well before they happen. The researchers also showed that their approach works for some more brittle polymer materials.

When studying the mechanical failure of a material, researchers often experiment by cutting a small notch into a thin sheet of the material and applying a slowly increasing force that pulls the notch apart. Eventually, a crack will grow and spread rapidly from the notch. Materials scientist Costantino Creton of Paris Sciences and Letters University says that over the past few years, such experiments have led to two general findings for elastomers. First, by embedding light-emitting, force-sensitive molecules into test materials, researchers have shown that, prior to crack initiation, irreversible molecular-bond damage accumulates very close to the initial notch (within 0.1 mm). Second, using sensitive spectroscopy techniques, other studies have found signs of unusual microscopic rearrangements of the polymer molecules occurring over larger regions of the material just prior to failure.

Single electrons stay stationary in superconductors with “flat-band” electronic structures, which could lead to low-energy-consumption devices made from such materials.

In 2018, researchers discovered that two layers of graphene, stacked and twisted at a specific angle, could exhibit superconductivity. Theorists have determined that the electronic structure of such a twisted material approximately resembles a “flat band,” which means that the energy of the materials’ free electrons remains constant regardless of the electrons’ momenta. This phenomenon inspired a flurry of work on systems that exhibit flat-band superconductivity. However, most of the research has focused on how such systems behave under equilibrium conditions. Now Päivi Törmä of Aalto University in Finland and her colleagues have probed the behavior of superconducting flat-band systems under nonequilibrium conditions [1]. The findings could help in the design of superconducting devices with low energy consumption.

Törmä and her colleagues considered an idealized flat-band material subjected to an applied voltage, making it a nonequilibrium system. Their predictions indicate that in this nonequilibrium system the paired and unpaired electrons follow the same behavior patterns as those in an equilibrium system: unpaired electrons form stationary quasiparticles and paired electrons flow with zero resistance. Additionally, in both types of systems the flat band helps the electrons form the bound pairs required for superconductivity.

Meet the house that diapers built.

Researchers have designed and erected a house that has shredded, disposable diapers mixed into its concrete and mortar. A single-story home of about 36 square meters can pack nearly 2 cubic meters of used diapers into its floors, columns and walls, the team reports May 18 in Scientific Reports.

Using recycled diapers as composite building materials would not only shrink landfill waste but also could make such homes more affordable, the team says, a particular need in developing countries like Indonesia where the demand for low-cost housing far outstrips the supply.

Magnetic materials with a triangular lattice have been the focus of numerous research studies, as theoretical predictions suggest that they could exhibit spin liquid states. These are quantum phases of matter that present interesting characteristics, such as quantum entanglement and fractionalized excitations.

While there have been numerous experimental efforts aimed at observing these fascinating phases in materials with a triangular lattice, this has so far proved to be very challenging. A key reason for this is that weak spin-orbit coupling and other perturbations in these materials typically result in conventional spin freezing or magnetic states.

Researchers at University of California, Boston College, Oak Ridge National Laboratory and the National Institute of Standards and Technology were recently able to produce a quantum disordered ground state in the triangular lattice-magnet NaRuO_2. Their findings, published in Nature Physics, suggest that this state was enabled by the cooperative interplay between spin-orbit coupling and correlation effects in the magnetic material.

In a ground-breaking experiment, scientists from the University of Groningen, together with colleagues from the Dutch universities of Nijmegen and Twente and the Harbin Institute of Technology (China), have discovered the existence of a superconductive state that was first predicted in 2017.

They present evidence for a special variant of the FFLO superconductive state in the journal Nature. This discovery could have significant applications, particularly in the field of superconducting electronics.

The lead author of the paper is Professor Justin Ye, who heads the Device Physics of Complex Materials group at the University of Groningen. Ye and his team have been working on the Ising superconducting state. This is a special state that can resist magnetic fields that generally destroy superconductivity, and that was described by the team in 2015.

Engineers have created a thin film that can generate millivolts of electricity from ambient air humidity thanks to water’s ‘mean free path.’

Da-kuk/iStock.

However, there’s one challenge they still face: understanding the materials they interact with.

Self-described mixed reality nerd, Brad Lynch, has tweeted out several interesting details about Apple’s yet-to-be announced VR/AR headset. He has managed to compile information from several sources — mostly reports produced by hardware analysts based in China. His summation of the leaked info states: “The Apple HMD’s Bill of Materials (BoM) cost to be about $1500–1600 (USD). This is about double the reported BoM for the (Meta) Quest Pro (which was 800 dollars including the controllers and charging pad).”

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