Science Bulletin最新文献

Stars getting close enough to black holes (BHs) can be torn apart by strong tidal forces, producing electromagnetic flares. To date, more than 100 tidal disruption events (TDEs) have been observed, each involving invariably normal gaseous stars whose debris falls onto the BH, sustaining the flares over years. White dwarfs (WDs), which are the most prevalent compact stars and a million times denser-and therefore tougher-than gaseous stars, can only be disrupted by intermediate-mass black holes (IMBHs) of 10²-10⁵ solar masses. WD-TDEs are considered to generate more powerful and short-lived flares, but their evidence has been lacking. Here we report observations of a fast and luminous X-ray transient EP250702a detected by Einstein Probe. Its one-day-long X-ray peak as luminous as 10^47-49ergs^-1showed strong recurrent flares with hard spectra extending to several tens of MeV gamma-rays, as detected by Fermi/GBM and Konus-Wind, indicating relativistic jet emission. The jet's X-rays dropped sharply from 3×10⁴⁹ergs^-1 to around 10⁴⁴ergs^-1within 20 days (10 days in the source rest frame). These characteristics are inconsistent with any previously known transient phenomena. We suggest that this fast-evolving event over the unprecedentedly short timescale arises likely from disruption of a WD by an IMBH. At late times, a soft component progressively dominates the X-ray spectrum, reaching a luminosity as high as 10⁴⁴ erg s^-1, which is consistent with being extreme super-Eddington emission from an accretion disk expected to form in an IMBH-WD TDE. WD-TDEs open a new window for investigating the elusive IMBHs and their surrounding stellar environments, and they are prime sources of gravitational waves in the band of space-based interferometers.

Brain-computer interface (BCI) presented by the non-invasive electroencephalography (EEG) cap/band or implantable chips enabling people to fast and reliable control computers or mobile devices with thoughts has redefined the boundaries of human capabilities. However, the existing cap/band-adhered sticky gel usually needs to be tightly fixed on the scalp through the hair to ensure intimate contact, which inconveniences the user. And the implantable chips represented by Neuralink gave a living example of how BCI can make quadriplegic live better, but the destructive unacceptable for healthy people. Here we proposed a multichannel wearable ear-computer interface (ECI) patch worn behind the ears for direct communication and control via brain activity. The 8-channel ECI patch based on MXene electrode was prepared by a facile direct inject print approach on the soft, thin, and breathable medical film that enables superior adherence. The fatigue induction experiments tested by the ECI patch offer an average classification accuracy of 90.5%, showing effective monitoring of the fatigue state. Participants wearing the ECI patch also perform the 4-target steady state visual evoked potential (SSVEP) BCI classification offline and online experiment, the online 4-route tasks reap a comparable average accuracy of 93.5% to the commercial cap. Moreover, the complex route task relied on the subjects who gave commands while observing the unmanned vehicle completed 3 times, demonstrating the reliability and possibility of the ECI patch.

Arctic ecosystems face significant threats from chemicals of global concern. Persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) have been consistently detected in the Arctic through decades of monitoring. POPs are known to bioaccumulate in food webs, and both POPs and PAHs are toxic posing risks to wildlife and human health. While regular monitoring activities have been implemented in most Arctic countries, information from the Russian Arctic is still limited. This review synthesizes the existing knowledge on environmental fate and distribution pathways of POPs, PAHs, and Chemicals Of Emerging Arctic Concern (CEACs) in the Russian Arctic. Except for recent studies on microplastics, data on CEACs remain very limited. Considering mass exchange processes between environmental compartments, including the cryosphere, this review focuses on the Russian Arctic coastal seas, where riverine transport and atmospheric deposition are the main sources of legacy POPs and PAHs. Northward-draining Russian Arctic rivers have been loading legacy POPs from historical sources to coastal seawater. Ongoing volatilization of low-molecular-weight PAHs from both sediments and seawater in the Russian Arctic coastal seas is likely to be accelerated with the ongoing warming climate. PAH and POPs stored in the cryosphere of the Russian Arctic are expected to be released with the ice/snow melting and permafrost thaws. However, more up-to-date information on these chemicals is needed to evaluate these processes and their significance for Arctic pollution.

Nickel-based co-catalysts are attractive candidates for H₂O₂ photosynthesis via the two-electron oxygen reduction reaction (2e^- ORR). However, inherently strong O₂ adsorption and overactivation at Ni sites promote undesired O-O bond cleavage, compromising both selectivity and activity. Here, we introduce an orbital-level modulation strategy that tailors O₂ activation at Ni centers by tuning the Ni 3d-O 2p interactions through atomic ligand regulation. Specifically, incorporation of electronegative phosphorus ligands into Ni-decorated poly(triazine imide) (Ni/PTI) reconfigures the Ni 3d orbital distribution, constructing Ni₂P/PTI that suppresses excessive O₂ activation and reverses the H₂O₂ decomposition observed in Ni/PTI. This strategy achieves a 4.7-fold enhancement in H₂O₂ production under visible light in pure water. Mechanistically, phosphorus-mediated electronic tuning diminishes Ni 3 d_yz orbital contributions to O₂ π* antibonding orbitals, thereby preventing O-O bond cleavage and stabilizing key intermediates. Concurrently, phosphorus-induced Ni coordination adjustment promotes *OOH protonation and inhibits H₂O₂ decomposition, jointly reinforcing 2e^- ORR selectivity and efficiency. These findings establish atomic ligand-driven orbital modulation as a powerful principle for steering O₂ activation on Ni-based co-catalysts, offering a blueprint for designing transition-metal sites with optimized electronic structures and coordination environments for efficient H₂O₂ photosynthesis.

The optical spin Hall effect (OSHE) bridges photonics and spintronics by enabling spin-dependent manipulation of light-where the "spin" of light refers to its polarization state-which is critical for on-chip photonic technologies. While OSHE with distinct topological textures has been demonstrated separately using transverse electric-transverse magnetic (TE-TM) splitting or birefringent crystals, achieving multiple spin textures within a single system remains elusive. Here, we report the first observation of OSHE driven by the interplay between TE-TM splitting and Rashba-Dresselhaus spin-orbit coupling (RDSOC) in an organic microcavity at room temperature. Polarization-resolved measurements reveal hybrid spin textures: quadrupole patterns at high momenta from TE-TM splitting and mirror-symmetric textures at low momenta from RDSOC. This interplay generates a persistent spin bias with a polarization lifetime of ∼300 ps, indicating robust spin coherence for stable spin-photonic and polarization-preserving devices. Our findings establish organic microcavities as versatile platforms for engineering hybrid spin-orbit coupling, advancing topological photonics and integrated spin-based information processing.