Hard carbon bends, an electrolyte nucleates, and a chip releases its signal
Medium-range order in carbon, nanometre-scale nucleation in a solid electrolyte and a wettability threshold in a diagnostic chip turn small structures into visible performance.
Science··Midday
Hardness and bending share one network
Compressing C60 crystals until they graphitised locally created a three-dimensional network of graphite-like clusters meeting at angles of roughly 70 degrees. This form of carbon reached 33.7 gigapascals of hardness in every direction and endured 12 per cent plastic strain before failure. Its conductivity remained semimetallic, changing by less than 12 per cent between 4 and 450 kelvin. Structural measurements and reverse Monte Carlo simulation point to medium-range order, rather than a perfect crystal lattice, as the structure carrying this unusual pairing of properties.[1]
A metastable phase survives by starting small
Alpha-Li3PS4 conducts lithium better than its sister phases, yet it should convert to the stable gamma form on cooling; rapid cooling can preserve it. Calculations showed that low surface energy at nanometre size lowers the alpha phase's nucleation barrier across a wide temperature range. Sub-second synchrotron X-ray diffraction and electron microscopy then watched small alpha nuclei form quickly and transform slowly. Producing the desired metastable structure can therefore be approached through size and time together, rather than treated as a lucky consequence of cooling rate alone.[2]
A molecular threshold becomes a visible result
In a single-use diagnostic chip, CRISPR-Cas13a finding its target changes the wettability of a molecular barrier, allowing liquid to cross a preset threshold and drain visibly. One target registered at 10 attomolar within two minutes, and two targets at 100 attomolar within five. With room-temperature sample preparation, results from 40 nasal swabs for SARS-CoV-2, influenza A and influenza B agreed with RT-PCR. The reported cost is 0.20 US dollars for one target and 0.30 US dollars for two; forty samples do not replace broad validation across different settings.[3]
