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Ultracold polar molecules offer strong electric dipole moments and rich internal structure, which makes them ideal building blocks to explore exotic quantum matter 1 – 9 , implement quantum information schemes 10 – 12 and test the fundamental symmetries of nature 13 . Realizing their full potential requires cooling interacting molecular gases deeply into the quantum-degenerate regime. However, the intrinsically unstable collisions between molecules at short range have so far prevented direct cooling through elastic collisions to quantum degeneracy in three dimensions. Here we demonstrate evaporative cooling of a three-dimensional gas of fermionic sodium–potassium molecules to well below the Fermi temperature using microwave shielding. The molecules are protected from reaching short range with a repulsive barrier engineered by coupling rotational states with a blue-detuned circularly polarized microwave. The microwave dressing induces strong tunable dipolar interactions between the molecules, leading to high elastic collision rates that can exceed the inelastic ones by at least a factor of 460. This large elastic-to-inelastic collision ratio allows us to cool the molecular gas to 21 nanokelvin, corresponding to 0.36 times the Fermi temperature. Such cold and dense samples of polar molecules open the path to the exploration of many-body phenomena with strong dipolar interactions. A general and efficient approach to evaporatively cool ultracold polar molecules through elastic collisions to create a degenerate quantum gas in three dimensions is demonstrated using microwave shielding.

Many-body entanglement is often created through the system evolution, aided by nonlinear interactions between the constituting particles. These very dynamics, however, can also lead to fluctuations and degradation of the entanglement if the interactions cannot be controlled. Here, we demonstrate near-deterministic generation of an entangled twin-Fock condensate of ~11,000 atoms by driving a rubidium-87 Bose-Einstein condensate undergoing spin mixing through two consecutive quantum phase transitions (QPTs). We directly observe number squeezing of 10.7 ± 0.6 decibels and normalized collective spin length of 0.99 ± 0.01. Together, these observations allow us to infer an entanglement-enhanced phase sensitivity of ~6 decibels beyond the standard quantum limit and an entanglement breadth of ~910 atoms. Our work highlights the power of generating large-scale useful entanglement by taking advantage of the different entanglement landscapes separated by QPTs.

The interplay of quantum statistics and interactions in atomic Bose–Fermi mixtures leads to a phase diagram markedly different from pure fermionic or bosonic systems. However, investigating this phase diagram remains challenging when bosons condense due to the resulting fast interspecies loss. Here we report observations consistent with a phase transition from a polaronic to a molecular phase in a density-matched degenerate Bose–Fermi mixture. The condensate fraction, representing the order parameter of the transition, is depleted by interactions, and the build-up of strong correlations results in the emergence of a molecular Fermi gas. The features of the underlying quantum phase transition represent a new phenomenon complementary to the paradigmatic Bose–Einstein condensate/Bardeen–Cooper–Schrieffer crossover observed in Fermi systems. By driving the system through the transition, we produce a sample of sodium–potassium molecules exhibiting a large molecule-frame dipole moment in the quantum-degenerate regime.Tuning interspecies interactions in atomic Bose–Fermi mixtures is shown to drive the system through a quantum phase transition. This enables the generation of heteronuclear molecules in the quantum-degenerate regime.

Aim Description of the driving forces for genetic divergence is important for understanding spatial pattern of biodiversity and development of conservation plans. Paleo‐climate, geographical barriers and habitat heterogeneity are considered to be the main influential factors; however, an integrative study is still lacking to reveal their interactions. Location Eastern North America. Methods Here, we generated MIG‐seq SNPs of 403 Sanguinaria canadensis samples and seven plastome data. The methods of phylogeography and landscape genomics were applied to infer their genetic divergence, demography, species distribution modelling, ecological differentiation and local adaptation. Results We identified three distinct genetic lineages corresponding to geographical distributions isolated by the Appalachian Mountains and the Mississippi River. Ecological niche modelling and population demographic inference demonstrated that the response of S. canadensis to Pleistocene climate changes was consistent with the pattern of southward contraction during the ice age and northward recolonization during the inter−/postglacial period. Isolation in multiple southern refugia was a key factor resulting in the genetic divergence, whereas secondary contact triggered by repeated range shifts allowed gene flow among different lineages. A greater effect of isolation‐by‐environment than isolation‐by‐distance was founded, which suggested heterogeneous environment was also a promotor of genetic differentiation. Candidate adaptive loci related to transposable elements were identified under the influence of divergent environmental selection. Ecological niche divergence also reflected adaptation to different environments. Main Conclusions This study revealed that genetic divergence has occurred within S. canadensis populations under the combined effect of paleo‐climate, geographical barriers and habitat heterogeneity, and emphasized the necessity of establishing different conservation units in future biological conservation and management work.

Inorganic mixed‐halide CsPbX3‐based perovskite solar cells (PeSCs) are emerging as one of the most promising types of PeSCs on account of their thermostability compared to organic–inorganic hybrid counterparts. However, dissatisfactory device performance and high processing temperature impede their development for viable applications. Herein, a facile route is presented for tuning the energy levels and electrical properties of sol–gel‐derived ZnO electron transport material (ETM) via the doping of a classical alkali metal carbonate Cs2CO3. Compared to bare ZnO, Cs2CO3‐doped ZnO possesses more favorable interface energetics in contact with the CsPbI2Br perovskite layer, which can reduce the ohmic loss to a negligible level. The optimized PeSCs achieve an improved open‐circuit voltage of 1.28 V, together with an increase in fill factor and short‐circuit current. The optimized power conversion efficiencies of 16.42% and 14.82% are realized on rigid glass substrate and flexible plastic substrate, respectively. A high thermostability can be simultaneously obtained via defect passivation at the Cs2CO3‐doped ZnO/CsPbI2Br interface, and 81% of the initial efficiency is retained after aging for 200 h at 85 °C. An all‐inorganic mixed‐halide perovskite solar cell with a power conversion efficiency of 16.42% is realized by using a Cs2CO3‐doped ZnO electron transport layer, which ascribes to the interfacial energy level tuning for reducing ohmic loss at the contact and enlarging the built‐in potential. A high thermostability is simultaneously obtained via surface defect passivation for improving the CsPbI2Br film against phase transformation.

China’s East Asia monsoon zone is undergoing rapid land-use conversion and urbanization. Safeguarding remaining biodiversity requires reducing, mitigating, and/or eliminating the negative impacts of human-induced landscape modification. In this study, we sampled ground-dwelling ants at 40 plots over 12 continuous months in a suburban area in southwestern China to examine whether and how vegetation composition and habitat fragmentation affected species richness and assemblage composition for the general ant community and, specifically, for principal functional groups (including Opportunists and Generalized Myrmicinae). Warmer seasons were associated with a higher capture rate for all functional groups. Patterns of ant species richness among Opportunists were more sensitive to vegetation and fragmentation than for Generalized Myrmicinae, and these effects generally varied with season. Patterns of ant assemblage composition for Opportunists were exclusively sensitive to vegetation, whereas Generalized Myrmicinae were sensitive to both vegetation and fragmentation with variation among seasons. Overall, our findings highlight the important role of seasonality, vegetation composition, and habitat fragmentation in mediating the impacts of human-induced landscape modification on urbanized ant communities, which make an essential functional contribution to biodiversity in the East Asia monsoon zone.

With the rapid process of urbanization at a global scale, university campuses have been viewed as important urban green spaces for biodiversity conservation. However, little is known about the role of university campuses in protecting ecological specialists, the species usually vulnerable to anthropogenic disturbance. We assessed the associations between several ecological variates and ecological specialization of bird communities across 198 Chinese university campuses. A total of 398 bird species were recorded, including 109 diet specialist species and 104 foraging stratum specialist species. We found that the elevation of campuses was positively related to diet specialist species richness, and the campus area was positively related to foraging stratum specialist species richness. NDVI was positively associated with the community-wide foraging stratum specialization index, but negatively associated with the community-wide diet specialization index. Our results suggest that campuses with larger areas or located at high elevations play an important role in maintaining ecological specialization of bird communities.

One of the most effective strategies for modifying the surface properties of nano-fillers and enhancing their composite characteristics is through polymer grafting. In this study, a coprecipitation method was employed to modify hydroxyapatite (HAP) with epoxidized soybean oleic acid (ESOA), resulting in ESOA-HAP. Subsequently, oligomeric poly(lactic acid) (OPLA) was grafted onto the surface of ESOA-HAP, yielding OPLA-ESOA-HAP. HAP, ESOA-HAP, and OPLA-ESOA-HAP were comprehensively characterized. The results demonstrate the progressive grafting of ESOA and OPLA onto the surface of HAP, resulting in enhanced hydrophobicity and improved dispersity in organic solvent for OPLA-ESOA-HAP compared to HAP. The vitality and adhesion of Wistar rat mesenchymal stem cells (MSCs) were assessed using HAP and modified HAP materials. Following culture with MSCs for 72 h, the OPLA-ESOA-HAP showed an inhibition rate lower than 23.0% at a relatively high concentration (1.0 mg/mL), which is three times lower compared to HAP under similar condition. The cell number for OPLA-ESOA-HAP was 4.5 times higher compared to HAP, indicating its superior biocompatibility. Furthermore, the mechanical properties of the OPLA-ESOA-HAP/PLLA composite almost remained unaltered ever after undergoing two stages of thermal processing involving melt extrusion and inject molding. The increase in the biocompatibility and relatively high mechanical properties render OPLA-ESOA-HAP/PLLA a potential material for the biodegradable fixation system.

(1) Background: Mitochondrial genomes are important markers for the study of phylogenetics and systematics. Triozidae includes some primary pests of Populus euphratica. The phylogenetic relationships of this group remain controversial due to the lack of molecular data. (2) Methods: Mitochondria of Egeirotrioza Boselli were sequenced and assembled. We analyzed the sequence length, nucleotide composition, and evolutionary rate of Triozidae, combined with the 13 published mitochondrial genomes. (3) Results: The evolutionary rate of protein-coding genes was as follows: ATP8 > ND6 > ND5 > ND2 > ND4 > ND4L > ND1 > ND3 > APT6 > CYTB > COX3 > COX2 > COX1. We reconstructed the phylogenetic relationships of Triozidae based on 16 triozid mitochondrial genomes (thirteen ingroups and three outgroups) using the maximum likelihood (ML) and Bayesian inference (BI) approaches. The phylogenetic analysis of the 16 Triozidae mitochondrial genomes showed that Egeirotrioza was closely related to Leptynoptera. (4) Conclusions: We have identified 13 PCGs, 22 tRNAs, 2 rRNAs, and 1 control region (CR) of all newly sequenced mitochondrial genomes, which were the mitochondrial gene type in animals. The results of this study provide valuable genomic information for the study of psyllid species.

Scattering resonances are an essential tool for controlling the interactions of ultracold atoms and molecules. However, conventional Feshbach scattering resonances 1 , which have been extensively studied in various platforms 1 – 7 , are not expected to exist in most ultracold polar molecules because of the fast loss that occurs when two molecules approach at a close distance 8 – 10 . Here we demonstrate a new type of scattering resonance that is universal for a wide range of polar molecules. The so-called field-linked resonances 11 – 14 occur in the scattering of microwave-dressed molecules because of stable macroscopic tetramer states in the intermolecular potential. We identify two resonances between ultracold ground-state sodium–potassium molecules and use the microwave frequencies and polarizations to tune the inelastic collision rate by three orders of magnitude, from the unitary limit to well below the universal regime. The field-linked resonance provides a tuning knob to independently control the elastic contact interaction and the dipole–dipole interaction, which we observe as a modification in the thermalization rate. Our result provides a general strategy for resonant scattering between ultracold polar molecules, which paves the way for realizing dipolar superfluids 15 and molecular supersolids 16 , as well as assembling ultracold polyatomic molecules. A type of universal scattering resonance between ultracold microwave-dressed polar molecules associated with field-linked tetramer bound states in the long-range potential well is observed, providing a general strategy for resonant scattering between ultracold polar molecules.