Author correction to a spectral test of the butterfly effect in GenCast ensembles

Nature has published an Author Correction to a paper titled «A spectral test of the butterfly effect and physical consistency in the diffusion-based GenCast's ensembles». The correction concerns a study proposing a spectral test to assess the butterfly effect and the physical consistency of forecast ensembles generated by GenCast, a diffusion-based weather prediction model. GenCast belongs to the new generation of deep-learning models competing with traditional numerical prediction systems from the ECMWF and other operational centres. These models generate forecast ensembles through a diffusion process, and one open question is whether they faithfully reproduce uncertainty propagation and the spectral properties of the atmosphere, that is, whether they respect the expected physical consistency across scales. The text available for the correction does not include technical details of the amendments, the affected data or the corrected figures. In Nature, an Author Correction indicates that the authors themselves have identified errors in the original paper and that the journal has published the corresponding amendment; the specific scope of the changes should be consulted in the full correction. The correction is relevant to the community evaluating machine-learning weather prediction models, where spectral validation and the physical consistency of ensembles are key criteria for judging whether these systems can be used operationally. NewsPhysics will update this story if more details on the affected figures are published.

Nanocapillary filling is controlled by the interface and evaporation pinning

A study of nanocapillary filling from ambient temperatures up to those typical of serpentinization examines how the interface between the liquid and the capillary wall, together with evaporation, determines the advance of the liquid front. The work addresses an open problem in the behaviour of fluids confined at the nanometre scale, where surface forces dominate over gravity and classical descriptions of capillarity no longer hold. The phenomenon investigated, evaporation front pinning, describes how the liquid can become fixed at a particular position within the capillary when mass loss through evaporation exactly balances the capillary supply. This equilibrium is especially relevant under geological conditions such as those of serpentinization, where water interacts with olivine-rich rocks at elevated temperatures and triggers reactions that release hydrogen. The results show that the interfacial control of filling depends critically on temperature, and that the pinning regime persists from ambient conditions up to the thermal range associated with serpentinization. The transition between free filling and a pinned front is set by the competition between capillary pressure and the evaporation rate inside the channel. The implications range from understanding fluid migration in the Earth's crust to designing microfluidic devices and membranes that operate at high temperature. Knowing when a nanocapillary fills and when it becomes blocked also allows models of hydrogen production in hydrothermal environments to be refined, a process relevant both to planetary geochemistry and to the search for biosignatures.

Silicone/Bi₂O₃ nanocomposites could measure diagnostic X-ray doses in real time

A research team has investigated the dosimetric characteristics of silicone nanocomposites loaded with Bi₂O₃ (bismuth oxide) nanoparticles for use as real-time dosimeters at diagnostic-level X-ray energies. The goal is to develop flexible materials that record the absorbed dose during conventional medical scans, an energy range in which commercial detectors face limitations in sensitivity and physical form. The appeal of polymer nanocomposites loaded with high-atomic-number compounds lies in combining the flexibility and ease of shaping of silicone with the increase in photoelectric attenuation provided by bismuth (Z = 83). Unlike traditional rigid dosimeters, these materials could conform to the patient's body surface and provide an immediate readout of the dose during the diagnostic procedure itself. The study evaluates how the material's response varies with Bi₂O₃ concentration and with X-ray beam energy within the range used in diagnostic imaging. Among the dosimetric quantities typically characterised in this kind of work are sensitivity, dose-response linearity, energy dependence and measurement reproducibility. Validation of these nanocomposites as real-time dosimeters for diagnostic radiology will require verifying their long-term stability and their behaviour under environmental factors such as temperature and humidity. If they pass these tests, they could be used in quality control of X-ray equipment and in personalised dose monitoring for patients.

MXene polymer nanocomposite conductivity optimized by contact number and size

A theoretical and simulation study addresses how to maximize the electrical conductivity of polymer nanocomposites loaded with MXenes, a class of highly conductive two-dimensional sheets. The work focuses on two geometric parameters of the contact network between adjacent sheets: the number of contact points and their diameter. The central result is that conductivity does not grow indefinitely with the number of contacts; instead, there is an optimal combination of number and size that maximizes it. MXenes are two-dimensional layered materials derived from metallic carbides and nitrides, with high metallic conductivities that make them prime candidates for filling insulating polymers and turning them into conductors. The open problem is that, once the percolation threshold is passed, the conductivity of the composite depends on the contact resistance between sheets as much as on the filler volume fraction. Earlier work had characterized that threshold, but the optimization of the contact microstructure beyond percolation had not been quantified in detail. The method combines modelling of the contact network between sheets with effective-medium conductivity calculations. Rather than treating sheets as ideal point contacts, the study explicitly parameterizes the number of contact points per pair of neighbouring sheets and the diameter of each one, and evaluates how the global conductivity varies across that parameter space. This description allows the contribution of contact geometry to be separated from the contribution of filler fraction. The key result is the existence of a conductivity maximum for an intermediate contact configuration: increasing the number of contact points beyond that value, or increasing their diameter, does not improve conductivity and can degrade it, because the sheet ceases to behave as an efficient conductor or because the network distribution is altered. Joint optimization of both parameters therefore offers a design rule for fabricating conductive composites with lower MXene loading. The implications are practical: it would allow conductive coatings, adhesives or elastomers to be formulated with less filler, reducing cost and preserving the polymer's mechanical properties. As modelling work, experimental validation of the predictions and extension to sheets with realistic size distributions remain as next steps.

HDPE–Sb₂O₃ composites boost X-ray shielding in the dental diagnostic range

A recent study evaluates high-density polyethylene (HDPE) composites loaded with antimony trioxide (Sb₂O₃) as shielding material against X-rays in the energy range typical of diagnostic dental radiology. The combination aims to exploit the lightness and easy processing of the polymer together with the high atomic number of antimony, which raises the probability of photon interaction in that energy interval. The motivation stems from a known limitation of conventional protectors: lead is effective but toxic, heavy and environmentally problematic, while many polymers on their own provide insufficient attenuation at the energies used in dental X-rays. Adding high-Z inorganic fillers to a polymer matrix makes it possible to tune shielding capacity without giving up the flexibility or ease of shaping of the composite material. In the study, HDPE specimens with different Sb₂O₃ fractions were fabricated and their behaviour characterised against X-ray beams in the dental diagnostic energy range. The assessment of attenuation capacity allows comparison of the performance of each formulation and determination of how protection varies as the inorganic filler content in the matrix increases. The results show that adding Sb₂O₃ improves the shielding behaviour of HDPE compared with the unloaded polymer in the energy interval studied, confirming the potential of these composites as an alternative to lead-based protectors for dental radiology applications. Combining a lightweight polymer with a high-atomic-number compound thus strikes a balance between attenuation efficiency, weight and toxicological safety. Beyond dentistry, this line of work falls within the broader search for lead-free shielding materials for healthcare and industrial settings. Evaluating long-term performance, the stability of the composite and its behaviour at other energy ranges remains pending before considering routine clinical use.