Climate change is expected to increase the frequency and magnitude of river floods1. Floods not only cause damage by inundation and loss of life2,3 but also jeopardize infrastructure because of bank failure and riverbed erosion processes that are poorly understood. Common flood safety programs include dike reinforcement and river widening4-9. The 2021 flood in the Meuse Basin caused 43 fatalities and a multibillion-dollar damage to infrastructure10. Based on analysis of the Meuse flood, we show how uneven widening of the river and heterogeneity of sediment deposits under the river can cause massive erosion. A recent flood safety program widened the river11, but created bottlenecks where widening was either prevented by infrastructure, or not yet implemented. Riverbed erosion was exacerbated by tectonic uplift that had produced a thin top gravel layer above fine-grained sediment. Greatly enhanced flow velocities produced underwater dunes with troughs that broke through the gravel armour in the bottlenecks, exposing easily erodible sands, resulting in extreme scour holes, one over 15 m deep. Our investigation highlights the challenges of re-engineering rivers in the face of climate change, increased flood risks, competition for river widening space, and calls for a better understanding of the subsurface.

Fine particulate matter (particulate matter with a diameter of 2.5 μm or less; PM2.5) causes millions of premature deaths globally1, but not all particles are equally harmful2-4. Current air-pollution control strategies, prioritizing PM2.5 mass reduction, have provided considerable health benefits but further refinements based on differences in the toxicity of various emission sources may provide greater benefits5-7. Here we integrated field measurements with air-quality modelling to assess the unequal toxicities of PM2.5 from various anthropogenic sources. Our findings revealed that the toxicity per unit of PM2.5 mass differed substantially between major sources, differing by up to two orders of magnitude. PM2.5 from solid fuel combustion in residential stoves had the highest toxicity, followed by those from the metallurgy industry, brake wear, diesel vehicles, petrol vehicles, the cement industry and power plants. We further analysed the source contributions of toxicity-adjusted PM2.5 emissions and population exposures in China. From 2005 to 2021, both the PM2.5 mass and relative-potency-adjusted emissions substantially decreased. Although industrial sources contributed 57.5% to the reduction in PM2.5 mass emissions, the reduction in relative potency-adjusted emissions was driven by residential combustion (approximately 80%). Clean-air policies should consider the differing toxicities of PM2.5 when formulating source-specific emission control regulations. This study proposes a cellular toxicity-based framework for PM2.5 reduction that could address the specific health risks in diverse regions, but further epidemiological studies will be required to confirm their relevance to human health outcomes and their application to public policy.

When two monolayer materials are stacked with a relative twist, an effective moiré translation symmetry emerges, leading to fundamentally different properties in the resulting heterostructure. As such, moiré materials have recently provided highly tunable platforms for exploring strongly correlated systems1,2. However, previous studies have focused almost exclusively on monolayers with triangular lattices and low-energy states near the Γ (refs. 3,4) or K (refs. 5-9) points of the Brillouin zone (BZ). Here we introduce a new class of moiré systems based on monolayers with triangular lattices but low-energy states at the M points of the BZ. These M-point moiré materials feature three time-reversal-preserving valleys related by threefold rotational symmetry. We propose twisted bilayers of exfoliable 1T-SnSe2 and 1T-ZrS2 as realizations of this new class. Using extensive ab initio simulations, we identify twist angles that yield flat conduction bands, provide accurate continuum models, analyse their topology and charge density and explore the platform's rich physics. Notably, the M-point moiré Hamiltonians exhibit emergent momentum-space non-symmorphic symmetries and a kagome plane-wave lattice structure. This represents, to our knowledge, the first experimentally viable realization of projective representations of crystalline space groups in a non-magnetic system. With interactions, these systems act as six-flavour Hubbard simulators with Mott physics. Moreover, the presence of a momentum-space non-symmorphic in-plane mirror symmetry renders some of the M-point moiré Hamiltonians quasi-one-dimensional in each valley, suggesting the possibility of realizing Luttinger-liquid physics.

Plastic pollution is a pervasive and growing global problem1-4. Chemicals in plastics are often not sufficiently considered in the overall strategy to prevent and mitigate the impacts of plastics on human health, the environment and circular economy5-7. Here we present an inventory of 16,325 known plastic chemicals with a focus on their properties, presence in plastic and hazards. We find that diverse chemical structures serve a small set of functions, including 5,776 additives, 3,498 processing aids, 1,975 starting substances and 1,788 non-intentionally added substances. Using a hazard-based approach, we identify more than 4,200 chemicals of concern, which are persistent, bioaccumulative, mobile or toxic. We also determine 15 priority groups of chemicals, for which more than 40% of their members are of concern. Finally, we examine data gaps regarding the basic properties, hazards, uses and exposure potential of plastic chemicals. Our work maps the chemical landscape of plastics and contributes to setting the baseline for a transition towards safer and more sustainable materials and products. We propose that removing known chemicals of concern, disclosing the chemical composition and simplifying the formulation of plastics can provide pathways towards this goal.

Lunar mare basalts illuminate the nature of the Moon's mantle, the lunar compositional asymmetry and the early lunar magma ocean (LMO)1-3. However, the characteristics of the mantle beneath the vast South Pole-Aitken (SPA) basin on the lunar farside remain a mystery. Here we present the petrology and geochemistry of basalt fragments from Chang'e-6 (CE6), the first returned lunar farside samples from the SPA basin4-7. These 2.8-billion-year-old CE6 basalts8 share similar major element compositions with the most evolved Apollo 12 ilmenite basalts. They exhibit extreme Sr-Nd depletion, with initial 87Sr/86Sr ratios of 0.699237 to 0.699329 and εNd(t) values (a measure of the neodymium isotopic composition) of 15.80 to 16.13. These characteristics indicate an ultra-depleted mantle, resulting from LMO crystallization and/or later depletion by melt extraction. The former scenario implies that the nearside and farside may possess an isotopically analogous depleted mantle endmember. The latter is probably related to the SPA impact, indicating that post-accretion massive impacts could have potentially triggered large-scale melt extraction of the underlying mantle. Either way, originating during the LMO or later melt extraction, the ultra-depleted mantle beneath the SPA basin offers a deep observational window into early lunar crust-mantle differentiation.

Plastic pollution of the marine realm is widespread, with most scientific attention given to macroplastics and microplastics1,2. By contrast, ocean nanoplastics (<1 μm) remain largely unquantified, leaving gaps in our understanding of the mass budget of this plastic size class3-5. Here we measure nanoplastic concentrations on an ocean-basin scale along a transect crossing the North Atlantic from the subtropical gyre to the northern European shelf. We find approximately 1.5-32.0 mg m-3 of polyethylene terephthalate (PET), polystyrene (PS) and polyvinyl chloride (PVC) nanoplastics throughout the entire water column. On average, we observe a 1.4-fold higher concentration of nanoplastics in the mixed layer when compared with intermediate water depth, with highest mixed-layer nanoplastic concentrations near the European continent. Nanoplastic concentrations at intermediate water depth are 1.8-fold higher in the subtropical gyre compared with the open North Atlantic outside the gyre. The lowest nanoplastic concentrations, with about 5.5 mg m-3 on average and predominantly composed of PET, are present in bottom waters. For the mixed layer of the temperate to subtropical North Atlantic, we estimate that the mass of nanoplastic may amount to 27 million tonnes (Mt). This is in the same range or exceeding previous budget estimates of macroplastics/microplastics for the entire Atlantic6,7 or the global ocean1,8. Our findings suggest that nanoplastics comprise the dominant fraction of marine plastic pollution.

In the past decade, ancient protein sequences have emerged as a valuable source of data for deep-time phylogenetic inference1-4. Still, even though ancient proteins have been reported from the Middle-Late Miocene5,6, the recovery of protein sequences providing subordinal-level phylogenetic insights does not exceed 3.7 million years ago (Pliocene)1. Here, we push this boundary back to 21-24 million years ago (Early Miocene) by retrieving enamel protein sequences of a rhinocerotid (Epiaceratherium sp.; CMNFV59632) from Canada's High Arctic. We recover partial sequences of seven enamel proteins and more than 1,000 peptide-spectrum matches, spanning at least 251 amino acids. Endogeneity is in line with thermal age estimates and is supported by indicators of protein damage, including several spontaneous and irreversible chemical modifications accumulated during prolonged diagenesis. Bayesian tip-dating places the divergence time of CMNFV59632 in the Middle Eocene-Oligocene, coinciding with a phase of high rhinocerotid diversification7. This analysis identifies a later Oligocene divergence for Elasmotheriinae, weakening alternative models suggesting a deep basal split between Elasmotheriinae and Rhinocerotinae8,9. The findings are consistent with hypotheses on the origin of the enigmatic fauna of the Haughton Crater, which, in spite of considerable endemism, has similarity to distant Eurasian faunas10,11. Our findings demonstrate the potential of palaeoproteomics in obtaining phylogenetic information from a specimen that is approximately ten times older than any sample from which endogenous DNA has been obtained so far.

Spontaneous two-photon emission (STPE) is a second-order quantum radiation process with implications in astrophysics1, atomic physics2 and quantum technology3. In particular, on-demand STPE from single quantum emitters has long been predicted to revolutionize photonic quantum science and technology4,5. Here we report STPE with brightness comparable to that of competing single-photon radiation from a single semiconductor quantum dot deterministically coupled to a high-quality micropillar cavity. This is because of strong vacuum fluctuations in the microcavity, which drive a biexciton directly to the ground state. We show the quantum nature associated with STPE in the cavity quantum electrodynamics regime using photon statistics measurements. Furthermore, STPE is exploited to build unconventional entangled quantum light sources that can simultaneously achieve near-unity entanglement fidelity for spontaneous parametric down-conversion sources and on-demand photon emission for atomic quantum emitters. Our work provides insights into the two-photon process in the quantum regime, which could empower photonic quantum technology with nonlinear quantum radiation.

Decreased brain levels of coenzyme Q10 (CoQ10), an endogenously synthesized lipophilic antioxidant1,2, underpin encephalopathy in primary CoQ10 deficiencies3,4 and are associated with common neurodegenerative diseases and the ageing process5,6. CoQ10 supplementation does not increase CoQ10 pools in the brain or in other tissues. The recent discovery of the mammalian CoQ10 headgroup synthesis pathway, in which 4-hydroxyphenylpyruvate dioxygenase-like protein (HPDL) makes 4-hydroxymandelate (4-HMA) to synthesize the CoQ10 headgroup precursor 4-hydroxybenzoate (4-HB)7, offers an opportunity to pharmacologically restore CoQ10 synthesis and mechanistically treat CoQ10 deficiencies. To test whether 4-HMA or 4-HB supplementation promotes CoQ10 headgroup synthesis in vivo, here we administered 4-HMA and 4-HB to Hpdl-/- mice, which model an ultra-rare, lethal mitochondrial encephalopathy in humans. Both 4-HMA and 4-HB were incorporated into CoQ9 and CoQ10 in the brains of Hpdl-/- mice. Oral treatment of Hpdl-/- pups with 4-HMA or 4-HB enabled 90-100% of Hpdl-/- mice to live to adulthood. Furthermore, 4-HB treatment stabilized and improved the neurological symptoms of a patient with progressive spasticity due to biallelic HPDL variants. Our work shows that 4-HMA and 4-HB can modify the course of mitochondrial encephalopathy driven by HPDL variants and demonstrates that CoQ10 headgroup intermediates can restore CoQ10 synthesis in vivo.

The ability to detect and respond appropriately to ingested nutrients is essential for an organism's survival and to ensure its metabolic demands are met. Nutrient signals from the gut lumen trigger local intestinal reflexes in the enteric nervous system (ENS) to facilitate digestion and absorption1-4, but the precise cellular pathways that are involved in the initial neuronal sensory process remain unclear. The extent to which the ENS is capable of discerning different luminal chemicals is also unknown. Here we use calcium imaging to identify specific enteric pathways that are activated in response to luminal nutrients applied to mouse jejunum. Notably, we show that different nutrients activate neurochemically defined ensembles of myenteric and submucosal neurons. Furthermore, we find that enteric neurons are not directly sensitive to nutrients but detect different luminal chemicals through the epithelium, mainly via a serotonin signalling pathway. Finally, our data reveal a spatial distribution of luminal information along the radial axis of the intestine, whereby some signals that originate from the villus epithelium are transmitted first to the myenteric plexus, and then back to the submucosal plexus, which is closer to the lumen.

Infectious diseases have had devastating effects on human populations throughout history, but important questions about their origins and past dynamics remain1. To create an archaeogenetic-based spatiotemporal map of human pathogens, we screened shotgun-sequencing data from 1,313 ancient humans covering 37,000 years of Eurasian history. We demonstrate the widespread presence of ancient bacterial, viral and parasite DNA, identifying 5,486 individual hits against 492 species from 136 genera. Among those hits, 3,384 involve known human pathogens2, many of which had not previously been identified in ancient human remains. Grouping the ancient microbial species according to their likely reservoir and type of transmission, we find that most groups are identified throughout the entire sampling period. Zoonotic pathogens are only detected from around 6,500 years ago, peaking roughly 5,000 years ago, coinciding with the widespread domestication of livestock3. Our findings provide direct evidence that this lifestyle change resulted in an increased infectious disease burden. They also indicate that the spread of these pathogens increased substantially during subsequent millennia, coinciding with the pastoralist migrations from the Eurasian Steppe4,5.

Research into the palaeobiology of extinct taxa through ancient DNA and proteomics has been mostly limited to Plio-Pleistocene fossils1-9, due to molecular breakdown over time, which is exacerbated in tropical settings1-3. Here we sample small proteomes from the interior enamel of fossils at palaeontological sites from the Pleistocene to the Oligocene in the Turkana Basin, Kenya, which has produced a rich record of Cenozoic mammalian evolution10. Through a mass-spectrometry-based proteomic workflow, and using criteria to locate diagenetiforms derived from enamel, we recover fragments of enamelin, ameloblastin, matrix metalloprotease-20 and dentin matrix acidic phosphoprotein 1 from an Early Miocene rhinocerotid and several proboscideans collected from the sites of Buluk (16 million years ago; Ma) and Loperot (18 Ma). Diagenetiform counts decline in progressively older fossils, and we observe variability in Early Miocene preservation across sites. Phylogenetic analyses reveal the contribution of these sequences to the systematic placement of extinct taxa, although we caution that this approach must account for sparse fragments, uncertainty in fragment identification and possible sequence diagenesis. We identify likely modifications that support the ancient age of these proteins, and some of the oldest examples of advanced glycation end-products yet known. The discovery of protein sequences within dense enamel tissues in one of the persistently warmest regions on Earth promises the discovery of much older proteomes that will aid in the study of the palaeobiology and evolutionary relationships of extinct taxa.

Deuterated acids/bases are high-value bulk chemicals used for synthesizing deuterated pharmaceuticals1,2, modifying optoelectronic materials3 and mediating hydrogen isotope exchange reactions4,5. However, conventional synthesis methods require harsh reaction conditions with high energy consumption6,7. Here we propose a versatile platform that takes advantage of heavy water dissociation in bipolar membranes (BPMs) to produce deuterated acids and bases under particularly mild conditions. Specifically, D2SO4 (2.75 mol l-1) and KOD (5.82 mol l-1), which are comparable with commercial products, were prepared using inexpensive D2O and K2SO4. We find that the deuteron generation rate is approximately 1.25 times greater than that of the protons, which is attributed to less co-ion leakage of D+ than H+ through the anion-exchange membrane (AEM), lower salt leakage within BPMs in D2O than in H2O and lower dehydration barrier of deuterons than proton clusters in the membrane phase. Compared with other contributing factors, salt leakage plays a relatively minor role in the observed H+/D+ concentration difference. This flexible and robust platform facilitates the synthesis of various deuterium-labelled compounds.

Over the last two decades, ocean warming and rapid loss of sea ice have dramatically changed the Pacific Arctic marine environment1-3. These changes are predicted to increase harmful algal bloom prevalence and toxicity, as rising temperatures and larger open water areas are more favourable for growth of some toxic algal species4. It is well known that algal toxins are transferred through food webs during blooms and can have negative impacts on wildlife and human health5-7. Yet, there are no long-term quantitative reports on algal toxin presence in Arctic food webs to evaluate increasing exposure risks. In the present study, algal toxins were quantified in bowel samples collected from 205 bowhead whales harvested for subsistence purposes over 19 years. These filter-feeding whales served as integrated food web samplers for algal toxin presence in the Beaufort Sea as it relates to changing environmental conditions over two decades. Algal toxin prevalences and concentrations were significantly correlated with ocean heat flux, open water area, wind velocity and atmospheric pressure. These results provide confirmative oceanic, atmospheric and biological evidence for increasing algal toxin concentrations in Arctic food webs due to warming ocean conditions. This approach elucidates breakthrough mechanistic connections between warming oceans and increasing algal toxin exposure risks to Arctic wildlife, which threatens food security for Native Alaskan communities that have been reliant on marine resources for subsistence for 5,000 years (ref. 8).

Wild plants can contribute valuable genes to their domesticated relatives1. Fertility barriers and a lack of genomic resources have hindered the effective use of crop-wild introgressions. Decades of research into barley's closest wild relative, Hordeum bulbosum, a grass native to the Mediterranean basin and Western Asia, have yet to manifest themselves in the release of a cultivar bearing alien genes2. Here we construct a pangenome of bulbous barley comprising 10 phased genome sequence assemblies amounting to 32 distinct haplotypes. Autotetraploid cytotypes, among which the donors of resistance-conferring introgressions are found, arose at least twice, and are connected among each other and to diploid forms through gene flow. The differential amplification of transposable elements after barley and H. bulbosum diverged from each other is responsible for genome size differences between them. We illustrate the translational value of our resource by mapping non-host resistance to a viral pathogen to a structurally diverse multigene cluster that has been implicated in diverse immune responses in wheat and barley.

Cell functions across eukaryotes are driven by specific gene expression programs, which are dependent on chromatin structure1-3. Here we report a single-cell multi-omics atlas of rice, one of the world's major crops. By simultaneously profiling chromatin accessibility and RNA expression in 116,564 cells from eight organs, we identified cell-type-specific gene regulatory networks and described novel cell states, such as a 'transitional state' in floral meristems. On the basis of our network analyses, we uncovered the function of the cell-type-specific regulatory hubs RSR1, F3H and LTPL120 during rice development. Our analysis revealed correlations between cell type and agronomic traits, as well as conserved and divergent cell-type functions during evolution. In summary, this study not only offers a unique single-cell multi-omics resource for a major crop but also advances our understanding of cell-type functions and the underlying molecular programs in rice.

Advances in deep learning and AlphaFold2 have enabled the large-scale prediction of protein structures across species, opening avenues for studying protein function and evolution1. Here we analyse 11,269 predicted and experimentally determined enzyme structures that catalyse 361 metabolic reactions across 225 pathways to investigate metabolic evolution over 400 million years in the Saccharomycotina subphylum2. By linking sequence divergence in structurally conserved regions to a variety of metabolic properties of the enzymes, we reveal that metabolism shapes structural evolution across multiple scales, from species-wide metabolic specialization to network organization and the molecular properties of the enzymes. Although positively selected residues are distributed across various structural elements, enzyme evolution is constrained by reaction mechanisms, interactions with metal ions and inhibitors, metabolic flux variability and biosynthetic cost. Our findings uncover hierarchical patterns of structural evolution, in which structural context dictates amino acid substitution rates, with surface residues evolving most rapidly and small-molecule-binding sites evolving under selective constraints without cost optimization. By integrating structural biology with evolutionary genomics, we establish a model in which enzyme evolution is intrinsically governed by catalytic function and shaped by metabolic niche, network architecture, cost and molecular interactions.

The ability of coronaviruses to recombine and cross species barriers affects human and animal health globally and is a pandemic threat1,2. FCoV-23 is a recently emerged, highly pathogenic recombinant coronavirus responsible for a widespread outbreak of feline infectious peritonitis. Here we report cryogenic electron microscopy structures of two FCoV-23 spike isoforms that correspond to the in-host loss of domain 0 observed in clinical samples. The loss of domain 0 markedly enhances the fusogenicity and kinetics of entry into cells and possibly enables biotype switching and lethality. We show that FCoV-23 can use several aminopeptidase N orthologues as receptors and reveal the molecular determinants of receptor species tropism, including a glycan that modulates human receptor engagement. We define antigenic relationships among alphacoronaviruses that infect humans and other mammalian species and identify a cross-reactive alphacoronavirus monoclonal antibody that inhibits FCoV-23 entry. Our results pave the way for the development of vaccines and therapeutics that target this highly pathogenic virus.

Changing atmospheric circulations shift global weather patterns and their extremes, profoundly affecting human societies and ecosystems. Studies using atmospheric reanalysis and climate model data1-9 indicate diverse circulation changes in recent decades but show discrepancies in magnitude and even direction, underscoring the urgent need for validation with independent, climate-quality measurements3. Here we show statistically significant changes in tropospheric circulation over the past two decades using satellite-observed, height-resolved cloud motion vectors from the Multi-angle Imaging SpectroRadiometer (MISR)10,11. Upper tropospheric cloud motion speeds in the mid-latitudes have increased by up to about 4 m s-1 decade-1. This acceleration is primarily because of the strengthening of meridional flow, potentially indicating more poleward storm tracks or intensified extratropical cyclones. The Northern and Southern Hemisphere tropics shifted poleward at rates of 0.42 ± 0.22 and 0.02 ± 0.14° latitude decade-1 (95% confidence interval), respectively, whereas the corresponding polar fronts shifted at rates of 0.37 ± 0.31 and 0.31 ± 0.21° latitude decade-1. We also show that the widely used ERA5 (ref. 12) reanalysis winds subsampled to the MISR are in good agreement with the climatological values and trends of the MISR but indicate probable ERA5 biases in the upper troposphere. These MISR-based observations provide critical benchmarks for refining reanalysis and climate models to advance our understanding of climate change impacts on cloud and atmospheric circulations.

Integrated nanolasers have been explored for decades owing to their important role in many applications, ranging from optical information processing and communications to medical treatments1-6. Although polarization, orbital angular momentum and directivity of nanolasers have been successfully manipulated7-9, neither their laser wavefront nor radiation characteristics can be customized at will. More optical elements are often required to further modify the laser characteristics, making the lasing system bulky and restricted by inevitable speckle noise. Here we suggest and realize a new type of laser, a metalaser, by using the interplay between local and nonlocal responses of dielectric resonant metasurfaces. The lasing mode is confined by nonlocal interaction between meta-atoms of a planar structure and the beam wavefront is precisely shaped by locally varying dipole momenta. Consequently, the metalaser emission can directly have any desired profile, including focal spots, focal lines, vector beams, vortex beams and even holograms. Notably, the scattered waves of the metalaser do not undergo resonant amplification like laser modes, being orders of magnitude weaker. As a consequence, the speckle noise becomes negligibly small in our metalaser holograms, providing a viable solution to the speckle noise problem of conventional laser holograms. This finding enriches our understanding of lasers and promotes their performance for various optical and photonic applications.