Phys.org November 4, 2024 The Atlantic meridional overturning circulation (AMOC) and the Amazon forest are viewed as connected tipping elements in a warming climate system. If global warming exceeds a critical threshold, the AMOC may slow down substantially, changing atmospheric circulation and leading to Amazonia becoming drier in the north and wetter in the south. An international team of researchers (Brazil, Morocco, Germany, Switzerland, the Netherlands, UK, France, China, USA – Keller Science Action Center) used pollen and microcharcoal data from a marine sediment core to assess changes in Amazon vegetation from 25,000 to 12,500 years ago and modeled vegetation […]
Successful development of a perfect diamagnetic conducting polymer
Phys.org October 28, 2024 Researchers in Japan synthesized Fe-doped polyaniline (D-PANI) in which they observed diamagnetism at T < 24 K under a weak external magnetic field. D-PANI was air-stable and showed the Peierls transition, as its resistivity increased rapidly at low temperatures, behaving as an electromagnetic insulator. It showed high sensitivity to magnetic fields, with its diamagnetic character changing under a relatively low magnetic field at 4 K. Its resistivity remained almost constant at high temperatures, and the nearest neighbor electron hopping conduction. Polarons in D-PANI showed perfect diamagnetism at low temperatures. After purification, D-PANI contained C, N, O, […]
Survey highlights ‘publish or perish’ culture as key factor in research irreproducibility
Phys.org November 5, 2024 An international team of researchers (Canada, Australia, USA – Stanford University) conducted an international cross-sectional survey of biomedical researchers’ perspectives on the reproducibility of research building on the 2016 survey and provided a biomedical-specific and contemporary perspective on reproducibility. Using 400 journals indexed in MEDLINE, they extracted the author names and emails from all articles published between 2020 and 2021. Participants survey included perceptions about a reproducibility crisis, perceived causes of irreproducibility of research results, knowledge of funding and training for research on reproducibility, etc. The data showed that 72% of participants agreed there was a […]
Unlocking next-gen chip efficiency: Researchers confirm thermal insights for tiny circuits
Phys.org November 4, 2024 As metallic nanostructures shrink towards the size of the electronic mean free path, thermal conductivity decreases due to increased electronic scattering rates. Matthiessen’s rule is commonly applied to assess changes in electron scattering rates, although this rule has not been validated experimentally at typical operating temperatures for most of the electronic systems. A team of researchers in the US (University of Virginia, University of Rhode Island, Oak Ridge National Laboratory, Intel Corporation) experimentally evaluated the validity of Matthiessen’s rule in determining the thermal conductivity of thin metal films by measuring the in-plane thermal conductivity and electronic […]
Volcanic ash as a source of nutrients: How the Hunga Tonga eruption affected ecosystems in the South Pacific
Phys.org November 6, 2024 The January 2022 eruption of the Hunga Tonga-Hunga Ha’apai (HTHH) volcano discharged 2,900 teragrams of ejecta, most of which was deposited in the South Pacific Ocean. An international team of researchers (UK, China) investigated its impact on the biogeochemistry of the South Pacific Gyre (SPG) using samples collected in February-April 2022. Surface water neodymium isotopes and rare earth element compositions showed a marked volcanic impact in the western SPG, potentially extending to the eastern region. Increasing trace metal concentrations in surface waters and chlorophyll-a inventories in euphotic layers between the eastern and western SPG suggested that […]
Top 10 Science and Technology Inventions for the Week of November 1, 2024
01. Specially designed transistors allow researchers to ‘hear’ defects in a promising nanomaterial 02. MXene nanomaterials enable wireless charging in textiles 03. New partially coherent unidirectional imaging system enhances visual data transmission 04. Quantum simulator could help uncover materials for high-performance electronics 05. Scientists discover molecules that store much of the carbon in space 06. Sliver of cool surface water helps the ocean absorb more carbon, study shows 07. Engineered bacterial protein offers efficient rare earth metal separation 08. New method successfully recycles carbon fiber composite into reusable materials 09. New machine learning model quickly and accurately predicts dielectric function […]
Capturing carbon from the air just got easier
Nanowerk October 24, 2024 The development of a durable material with high capacity, fast kinetics and low regeneration temperature for CO2 capture, especially from the intricate and dynamic atmosphere, is still lacking. An international team of researchers (USA – University of California, Saudi Arabia, Germany) synthesized a porous, crystalline covalent organic framework (COF) with olefin linkages structurally characterized and post-synthetically modified by the covalent attachment of amine initiators for producing polyamines within the pores. The COF could capture CO2 from open air with a capacity of 0.96 mmol g–1 under dry conditions and 2.05 mmol g–1 under 50% relative humidity, both from 400 ppm CO2. […]
Chemists just broke a 100-year-old rule and say it’s time to rewrite the textbooks
Phys.org October 31, 204 One hundred years ago, Julius Bredt published an observation that certain molecules that constrained several adjacent carbon centers in a particular nonplanar arrangement could not form double bonds between them. These hypothetical double bonds became known as “anti-Bredt” olefins, and the doctrine that they were inaccessible remains widespread even with the occasional hint to the contrary. Researchers at UCLA reported a general strategy to prepare these olefins as fleeting intermediates that could be captured in cycloaddition reactions. The protocol relies on the driving force of silicon-fluorine bond formation from a precursor, which is akin to approaches […]
Discovery challenges existing theories of magnetism in kagome metals
Phys.org October 30, 2024 The rare earth RMn6Sn6 (R = rare earth) family magnetic kagome systems, where their kagome flat bands are calculated to be near the Fermi level in the paramagnetic phase have been reported. While partially filling a kagome flat band is predicted to give rise to a Stoner-type ferromagnetism, experimental visualization of the magnetic splitting across the ordering temperature has not been reported for any of these systems leaving the nature of magnetism in kagome magnets an open question. An international team of researchers (USA – Rice University, Brookhaven National Lab, Los Alamos National Laboratory, Israel, Czech Republic) probed […]
Engineered bacterial protein offers efficient rare earth metal separation
Phys.org October 28, 2024 Elucidating details of biology’s selective uptake and trafficking of rare earth elements, particularly the lanthanides, has the potential to inspire sustainable biomolecular separations of these essential metals for many modern technologies. Researchers at The Pennsylvania State University biochemically and structurally characterized Methylobacterium (Methylorubrum) extorquens LanD from a bacterial gene cluster for lanthanide uptake. The protein provided only four ligands at its surface-exposed lanthanide-binding site, allowing for metal-centered protein dimerization that favored the largest lanthanide, LaIII. Selective dimerization enriched high-value PrIII and NdIII relative to low-value LaIII and CeIII in an all-aqueous process, achieved higher separation factors […]