Social learning is a key factor in the transmission of technological behaviours amongst primates. We studied chimpanzee (Pan troglodytes verus) social interactions in the context of tool and proto-tool use behaviours in the savanna site of Dindefelo, Senegal. Between 2017 and 2025, we obtained 14 h 58 min of camera trap footage at 14 locations where chimpanzees performed tool-use behaviours, namely algae fishing (for filamentous green algae: Zygnemataceae), ant dipping (for army ants: Dorylus sp.), and termite fishing (for termites: Macrotermitinae). We also obtained 30 min of camera trap footage at 11 locations where chimpanzees carried baobab (Adansonia digitata) fruit, which they pound against stationary anvils (i.e., proto-tools), a behaviour called baobab pounding. In total, we recorded 33 tool transfers and four fruit transfers. Transfers occurred mostly between mothers and their offspring. Most tool transfers were recoveries and tolerated takes. We compared the behaviour of initial tool possessors and tool recipients 30 s after and 30 s before each transfer. We excluded recoveries because in these cases the initial possessor does not interact with the recipient before abandoning the tool. We fitted Linear Mixed-Effects Models to test whether initial possessors and recipients exhibited different proportions of time using tools, insertions per second, and mouthfuls per second, after versus before a transfer. Initial possessors spent a significantly lower proportion of time using tools and performed significantly fewer insertions per second after transferring a tool, whereas recipients spent a significantly higher proportion of time using tools, and performed significantly more insertions and mouthfuls per second after receiving a tool. In addition, we detail two cases that highlight social learning of technological behaviours, in the context of ant dipping and baobab pounding, respectively. In line with previous research, we found that tool transfer constitutes a type of teaching in Dindefelo. Our results support the idea that teaching and facilitation, mainly from mothers, contribute to the acquisition of technological skills in immature chimpanzees.

Internally resistance-heated diamond anvil cell (IHDAC) enables long-duration, thermally stable experiments at high pressure and high temperature conditions and is, therefore, well suited for physical property measurements implicating the Earth's deep interior. A potential limitation of conventional direct current (DC) operation is the formation of a steady electric potential gradient within the sample, which can induce electromigration and thereby drive time-dependent compositional changes during heating. To address this issue, here we introduce alternating current (AC) operation in IHDAC experiments. We demonstrate the influence of constant voltage bias by comparing DC- and AC-IHDAC for Fe-H and Fe-C alloys. In the Fe-H system, ramp laser heating under constant voltage bias produces a reduction in lattice volume, consistent with substantial hydrogen loss. In contrast, 1-kHz AC-internal heating does not show apparent hydrogen depletion up to ∼2350 K and allows stable tracking of the hcp-(hcp + fcc)-fcc transition, consistent with reported phase relations. For Fe-4 wt. % C, cross-sectional chemical analyses of recovered samples reveal carbon inhomogeneity after constant-voltage-biased heating, whereas AC heating yields uniform Fe and C distributions. These results demonstrate that AC-IHDAC can effectively reduce the net electrical bias in IHDAC experiments and suppress electromigration-driven redistribution of light elements, thereby improving chemical stability in high-P-T measurements on Fe-light element alloys.

Carbonic acid (H2CO3) has been detected on the surfaces of icy moons and has been suggested to occur in the interior of ice giants. Hence, understanding structure-property relations of phases in the H-C-O system is of significant interest to astrophysics and solid-state chemistry. Here we show, that at low pressures (≈9 GPa) two H2CO3 polymorphs can occur simultaneously at different temperatures. The two H2CO3 phases were obtained in different areas of a sample chamber of a diamond anvil cell after laser-heating a H2O + CO2 mixture. The orthorhombic crystal structure of H2CO3-Pnma was refined from synchrotron single crystal X-ray diffraction, including the position of the hydrogen atoms. The structure had previously been predicted, but had not been confirmed experimentally. Our density functional theory-based calculations reproduce the experimental Raman spectrum, confirming that the structural model of H2CO3-Pnma is appropriate. From the spatial phase distribution in the sample chamber we infer that H2CO3-Pnma is the low temperature polymorph of H2CO3-P21/n, implying that the p,T-diagram of carbonic acid is more complex at low pressures than previously assumed.

Distinguishing topological from trivial phases is central to condensed matter physics, yet resolving distinct nontrivial regimes that share the same Z 2 classification remains challenging. Here, using first-principles calculations, we show that monoclinic BaIn2As2 undergoes two successive pressure-driven topological phase transitions within the same P2/m structural phase, evolving from a topological insulator at ambient pressure to a trivial insulator at 16 GPa and then to a high-pressure topological semimetal at 26 GPa. The two nontrivial phases share the same Z 2 = 1 classification but exhibit distinct surface spectra and opposite low-energy optical anisotropy. We establish a two-level identification scheme in which spin Hall conductivity provides a fingerprint for separating nontrivial phases from the trivial phase, with possible inverse spin Hall electrical readout, whereas monoclinic symmetry-enabled in-plane reflectance anisotropy resolves the two nontrivial phases. We further propose a diamond-anvil-cell platform combining yttrium-iron-garnet-based spin pumping with polarization-resolved infrared reflectance.

Using synchrotron x-ray diffraction in laser-heated diamond anvil cells, we report the observation of a hexagonal close-packed (hcp) phase of water ice at high pressure and temperature conditions. Above 200 GPa and 1800 K, the hcp phase becomes dominant upon entering the superionic regime, as evidenced by anomalous thermal expansion. Observations are consistent with the hcp phase becoming thermodynamically more stable than the face-centered cubic (fcc) phase via a martensitic transition extending across the 130-200 GPa pressure range, within the superionic regime. Hcp ice is also observed to emerge from stacking disorder developing within the fcc oxygen lattice upon cooling, during its reversion to the body-centered cubic phase. The presence of an fcc-hcp martensitic transition in the superionic regime of warm dense ice may have implications for planetary models of Uranus and Neptune.

Highly siderophile elements (HSEs) are expected to be extensively depleted in the mantle due to their affinity for metal during core formation. Yet, their abundances in the mantle far exceed the predictions based on low pressure and low temperature partitioning experiments. In addition, all HSEs are present in similar chondritic relative proportion in the mantle. This has traditionally been attributed to the late accretion of chondritic material, the late veneer. We present laser-heated diamond anvil cell experiments that quantify the partitioning behavior of five HSEs (rhenium, osmium, iridium, palladium, and gold) under pressure-temperature conditions directly relevant to early Earth's magma ocean. Our results demonstrate a substantial decrease in metal-silicate partition coefficients with increasing temperature. Multistage accretion models reproduce the observed HSE abundances and ratios in the mantle without invoking a late veneer. This resolves the longstanding paradox of HSEs excess' in the mantle and suggests that the delivery of volatile compounds to the young Earth is primarily explained by early accretion and differentiation processes.

Rare-earth medium-entropy alloys provide a platform for investigating how chemical disorder modifies the well-established pressure-induced structural evolution of close-packed 4flanthanides. Here, we study TbHoEr and TbHoDy using synchrotron x-ray diffraction in diamond anvil cells. Both alloys transform from the ambient hexagonal close-packed (hcp) structure to a double hexagonal close-packed (dhcp) phase, while no well-resolved bulkSm-typeintermediate phase is observed. For TbHoEr, compression to 70 GPa further reveals a high-pressure rhombohedralhR24phase. Unlike the constituent heavy lanthanides, however, both alloys bypass the intermediateSm-typephase. Two-dimensional diffraction images further reveal streak-like diffuse scattering in the transition region, indicating stacking disorder and limited stacking coherence along the close-packed direction. These observations indicate that the transformation proceeds through a stacking-disordered close-packed state rather than through a well-ordered bulkSm-typephase. We propose that configurational disorder, local lattice distortion, stacking-fault energetics, and transformation kinetics collectively suppress the development of long-rangeSm-typeorder. The results demonstrate that medium-entropy alloying can fundamentally modify pressure-induced stacking pathways in rare-earth materials under extreme conditions.

High-pressure, high-temperature experiments were conducted in a multi-anvil press using seven different starting compositions to investigate the phase relations of Fe-C-S liquids at pressures up to 6 GPa and temperatures up to 2000 K. Quenched samples revealed immiscible C-rich and S-rich metallic liquids at 2 and 4 GPa, manifesting as either large immiscible zones or emulsified smaller droplets. On the contrary, no immiscibility was observed at 5 or 6 GPa. At these higher pressures, the carbon solubility limit, significantly reduced by increasing sulfur content in the ternary liquid, prevents the formation of a liquid phase rich in both C and S. Our findings thus indicate that super-liquidus immiscibility in Fe-rich compositions does not occur at pressures above 5 GPa, due to the differential pressure dependence of C solubility and miscibility. The limited C solubility in S-rich liquids at higher pressures effectively suppresses immiscibility. Based on these results, terrestrial planetary bodies with fluid cores at pressures exceeding 5 GPa are unlikely to experience liquid-liquid immiscibility, even when both carbon and sulfur are abundant, as sulfur limits carbon solubility and promotes its exsolution. For the Moon, immiscibility-induced core stratification is not expected, though local emulsification could occur near the core-mantle boundary (CMB). In smaller bodies, a two-liquid Fe-C-S core may form at high temperatures, but progressive cooling may lead to graphite crystallization and the potential development of a graphitic crust.

Multispecific, multivalent antibodies (Abs) are a burgeoning class of drugs that dramatically expand the pharmacological repertoire beyond traditional therapeutic Abs. Here, we present a simple, modular approach to developing multispecific, multivalent Abs based on a Fab-phage library with a single light chain. Using this library, we created three Abs targeting unique sites on programmed death-ligand 1 (PD-L1) and another antibody targeting CD30. Biophysical and cellular characterization of these Abs demonstrated their functional equivalence to clinically relevant Abs targeting PD-L1 or CD30. We then combined these paratopes into a series of bispecific, tetravalent, triparatopic Abs that retained the functionality of the parental Abs. Structural analysis of each of the Abs in complex with their cognate antigens demonstrated the adaptability of the common light chain to form diverse paratopes with an array of distinct heavy chains.

Fonsecaea species cause chromoblastomycosis and phaeohyphomycosis, but links between environmental exposure and infection are poorly defined. We describe a 4-year-old boy with finger swelling after oak tree laceration in Houston, Texas. Broad-range polymerase chain reaction identified F. pedrosoi or F. monophora, and metagenomic sequencing of tree bark and soil detected Fonsecaea DNA.

The mineralogy of the Earth's lower mantle is fundamental to understanding the planet's formation, composition, evolution, and dynamics. However, uncertainties in the elastic properties and phase transitions of CaSiO3 davemaoite-the third most abundant phase in a pyrolitic lower mantle-have hindered quantitative links between seismic observations and lower-mantle mineralogy. Here we combine Brillouin spectroscopy with resistively heated diamond anvil cell experiments to measure the sound velocities of CaSiO3 davemaoite up to 80 GPa and 973 K. We show that the tetragonal-cubic phase transition occurs below 900 K throughout the entire lower mantle. Fitting the thermoelastic properties of cubic davemaoite reveals substantially reduced shear-wave velocities at deep lower-mantle conditions. Because of these intrinsically slow velocities, increasing bridgmanite abundance alone cannot reconcile seismic observations for a normal lower mantle containing even small amount of davemaoite. Our results therefore suggest that davemaoite is depleted in the ambient lower mantle but concentrated within LLSVPs, likely as a consequence of late-stage crystallization during magma-ocean differentiation.

The integration of nitrogen-vacancy color centers into diamond anvil cells has opened the door to quantum sensing at megabar pressures. Despite a multitude of experimental demonstrations and applications ranging from quantum materials to geophysics, a detailed microscopic understanding of how stress affects the NV center remains lacking. In this work, using a combination of first principles calculations as well as high-pressure NV experiments, we develop a complete description of the NV's optical properties under general stress conditions. In particular, our ab initio calculations reveal the complex behavior of the NV's intersystem crossing rates under stresses that both preserve and break the defect's symmetry. Crucially, our proposed framework immediately resolves a number of open questions in the field, including (i) the microscopic origin of the observed contrast enhancement in (111)-oriented anvils, and (ii) the surprising observation of NV contrast inversion in certain high-pressure regimes. Our work lays the foundation for optimizing the performance of NV high-pressure sensors by controlling the local stress environment, and more generally, suggests that symmetry-breaking stresses can be utilized as a novel tuning knob for generic solid-state spin defects.

Structural deformation of single-walled carbon nanotubes (SWNTs) under harsh conditions can profoundly modify their physical and mechanical properties. However, the intrinsic transformation mechanism and consequent electronic transitions at the individual SWNT level with identified (n, m) remain challenging, despite much effort devoted to nanotube bundles and solutions with significant tube-tube interactions. Herein, we experimentally demonstrated that radial compression of individual SWNTs follows a universal and reversible deformation pathway: circular-elliptical-racetrack-peanut shaped-nanoribbon, through in situ electrical and Raman measurements under high pressure. The critical pressures exhibited a general diameter dependence based on the modified Lévy-Carrier model. Furthermore, we provided direct electrical evidence that this structural collapse can trigger the semiconducting to metallic transition of SWNTs, potentially driven by pressure-induced σ-π orbital hybridization and bandgap closure. This established transformation mechanism can shed light on structural transitions of various nanomaterials and further evoke their potential applications in nanoelectronics and nanomechanics.