Phys.org May 10, 2023 Topological semimetals have advantages in achieving highly sensitive, low energy photodetection with ultrafast operation. Although various semimetals have been explored recently, new semimetals are still being pursued for high-responsivity photodetectors with broadband response. Researchers in China reported a pressure-induced semiconductor–semimetal transition in two-dimensional wide-band semiconducting lead iodide (PbI2). The photocurrent under visible light showed abrupt increases by two orders of magnitude at ≈25 GPa, where the crystalline structure transforms from the Pnma to I4/MMM phase. The responding band expanded from visible light to at least the telecom wavelength 1550 nm. The spectra of PbI2 suggested that […]
Scientists find link between photosynthesis and ‘fifth state of matter’
Science Daily May 3, 2023 Bose-Einstein condensation of excitons enables frictionless energy transfer, but typically occurs under extreme conditions in highly ordered materials, such as graphene double layers. Photosynthetic light-harvesting complexes demonstrate extremely efficient transfer of energy in disordered systems under ambient conditions. Researchers at the University of Chicago established a link between the two phenomena by investigating the potential for exciton-condensate-like amplification of energy transport in room-temperature light harvesting. Using a model of the Fenna-Matthews-Olson complex and accounting for intrachromophore electron correlation explicitly through the addition of multiple sites to the individual chromophores, they observed amplification of the exciton […]
‘Super-resolution’ imaging technology
Science Daily May 9, 2023 A team of researchers in the US (University of Oklahoma, Yale University) exposed mammalian cells to metallic nanoparticles and then embedded them within different swellable hydrogels to enable quantitative 3D imaging approaching electron-microscopy-like resolution using a standard light microscope. Using the nanoparticles’ light scattering properties, they demonstrated quantitative label-free imaging of intracellular nanoparticles with ultrastructural context and confirmed the compatibility of two expansion microscopy protocols, protein retention and pan-expansion microscopy, with nanoparticle uptake studies. The relative differences between nanoparticle cellular accumulation for various surface modifications were validated using mass spectrometry and determined the intracellular nanoparticle […]
Supercomputers have revealed the giant ‘pillars of heat’ funneling diamonds upward from deep within Earth
Phys.org May 9, 2023 Most diamonds have been transported to Earth’s surface from depths between ~120 km and ~660 km by volatile-rich magmas called kimberlites. The reconstructed locations of kimberlites erupted in the past 320 million years have been shown to be correlated with seismically imaged large basal mantle structures at ~2,800 km depth. This correlation has been interpreted as requiring basal mantle structures to be stationary over time. However, the geodynamic process responsible for this correlation remains to be identified. Researchers in Australia developed global mantle convection models including a basal layer of dense material and driven by surface plate motions to […]
Training machines to learn more like humans do
MIT News May 9, 2023 Unlike humans, computer vision models don’t typically exhibit perceptual straightness, so they learn to represent visual information in a highly unpredictable way. But if machine-learning models had this ability, it might enable them to better estimate how objects or people will move. Researchers at MIT explored the relationship between network architecture, differing types of robustness, biologically-inspired filtering mechanisms, and representational straightness in response to time-varying input; they identified strengths and limitations of straightness as a useful way of evaluating neural network representations. They found that adversarial training leads to straighter representations in both convolutional neural […]
Top 10 Science and Technology Inventions for the Week of May 5, 2023
01. Better understanding soft material behavior 02. ‘Gluing’ soft materials without glue 03. MIT engineers “grow” atomically thin transistors on top of computer chips 04. More power from waste heat 05. New germanium-tin transistor as alternative to silicon 06. Newly developed hydrogel nanocomposite for the mass production of hydrogen 07. Newly observed effect makes atoms transparent to certain frequencies of light 08. Paradoxical quantum phenomenon measured 09. Researchers call for a new approach to studying academic progress 10. Researchers detect and classify multiple objects without images And others Researchers use AI to explore potential zoonotic diseases Silver nanoparticles spark key […]
Better understanding soft material behavior
Science Daily May 1, 2023 The direct connections between the macroscopic flow/deformation and microscopic structure or dynamics has not been determined. An international team of researchers (USA – University of Illinois, Argonne National Laboratory, South Korea, Canada) They probed the microstructural yielding dynamics of a concentrated colloidal system by performing creep/recovery tests with simultaneous collection of coherent scattering data via X-ray Photon Correlation Spectroscopy (XPCS). This combination of rheology and scattering allowed for time-resolved observations of the microstructural dynamics as yielding occurred, which could be linked back to the applied rheological deformation to form structure–property relations. Under sufficiently small, applied […]
‘Gluing’ soft materials without glue
Science Daily May 3, 2023 Electroadhesion can involve chemical bonds, like ionic bonds, or more physical connections, like ensnaring polymer chains together. Researchers at the University of Maryland have demonstrated a universal, ‘electroadhesion’ technique that can adhere any soft materials to each other just by running electricity through them. They tested a gel in addition to three types of capsules made of alginate or chitosan that were either positively or negatively charged. When attached to graphite electrodes and exposed to a 10-V electric field for around 10 seconds, the oppositely charged materials stuck together strong enough to withstand gravity. By […]
MIT engineers “grow” atomically thin transistors on top of computer chips
MIT News April 27, 2023 Semiconductor chips are traditionally made with bulk materials, which are boxy 3D structures, so stacking multiple layers of transistors to create denser integrations is very difficult. Semiconductor transistors made from ultrathin 2D materials, each only about three atoms in thickness, could be stacked up to create more powerful chips. Using a low-temperature growth process that does not damage the chip, an international team of researchers (USA – MIT, Oak Ridge National Laboratory, Sweden) has demonstrated a novel technology that can effectively and efficiently “grow” layers of 2D transition metal dichalcogenide (TMD) materials directly on top […]
More power from waste heat
Nanowerk April 29, 2023 An international team of researchers (Germany, USA – Northwestern University) studied an alloy of niobium, iron and antimony that converts waste heat into electricity at temperatures ranging from about 70 to more than 700 degrees Celsius with an efficiency of eight percent. To further increase the efficiency of the thermoelectric made of niobium, iron and antimony, the researchers focused on its microstructure. As grain boundaries reduce both the thermal and electrical conductivity of the material, for the highest possible efficiency, the thermal conductivity should be as low as possible so that the heat in the material […]