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Atomic oxygen in low Earth orbit erodes polyimide, increasing surface roughness and degrading performance. The reactive species scission polymer chains and remove surface material, exposing fresh sites that accelerate further attack and disrupt thermal, electrical, and mechanical functions. In this paper, we evaluate nanoscale reinforcements of polyimide with graphene and metal oxides under controlled atomic oxygen exposure equivalent to 145 days at a 550 km orbit. Graphene with a thickness of few nanometers and particle size less than 2 µm, and metal oxides zirconia, zinc oxide, and titania with particle size less than 100 nm were investigated. Hybrids containing graphene plus metal oxide at a 1:1 ratio and a total loading of 0.75 wt% increased roughness relative to neat polyimide, with graphene-zirconia showing a rise of +121 percent, graphene-zinc oxide +10 percent, and graphene-titania +20 percent. The behavior is consistent with agglomeration, incomplete dispersion, and interfacial mismatch that hinder uniform blocking of atomic oxygen and limit formation of protective oxygenated groups. In contrast, single-filler composites at 0.75 wt% reduced average roughness, with graphene lowering Sa by about 59 percent, zirconia by about 51%, titania by about 47%, and zinc oxide by about 47%. Varying graphene loading from 0.25 to 0.75 wt% diminished erosive features at the higher end, but atomic force microscopy revealed isolated tall peaks at 0.75 wt%, indicating localized restacking or agglomeration. Mechanical testing of graphene-reinforced coatings on fiberglass showed a similar trade-off, with tensile strength around 23 MPa and peak load greater than 50 N at 0.5 wt% compared to about 21 MPa and 40 N at 0.75 wt%, while strain at break remained comparable. These results define practical limits for nanoparticle reinforcement in polyimide, linking filler identity, loading, and dispersion quality to atomic oxygen response and sustained function in LEO.

Gold nanoparticles (AuNPs) emerge as promising neuromodulatory biomaterials due to their tunable optical properties, biocompatibility, and ability to cross the blood-brain barrier. Here, we investigated the behavioral and neuroprotective effects of citrate-stabilized AuNPs (~ 19 nm) coated with PEG3350 and irradiated under white (AuWL+PEG) or green light (AuGL+PEG), compared with non-irradiated PEGylated AuNPs (AuNP+PEG). Comprehensive physicochemical analyses demonstrated that green-light irradiation enhanced surface plasmon resonance (SPR) activity, improved PEG adsorption, and yielded superior colloidal stability relative to white-light irradiation. In vivo evaluation in Wistar rats revealed that AuGL+PEG produced robust anxiolytic-like effects in the elevated plus maze, significantly enhanced spatial working memory in the Y-maze, and improved performance in the radial arm maze, approaching the efficacy of donepezil. In the forced swimming test, AuGL+PEG also produced the most favorable antidepressant-like profile, reducing immobility without locomotor confounds. Biochemically, AuGL+PEG markedly enhanced antioxidant capacity, increasing SOD, CAT, GPX, and GSH levels while reducing lipid peroxidation (MDA), consistent with restored redox homeostasis. Acetylcholinesterase inhibition was significantly greater in irradiated groups, supporting improved cholinergic signaling. Toxicological evaluation indicated no major systemic or hematological toxicity at the administered doses. Collectively, the findings demonstrate that light-engineered PEGylated AuNPs, particularly those activated with green light, exhibit potent neuroprotective and cognition-enhancing effects mediated by plasmonic surface optimization, antioxidant defense reinforcement, and cholinergic modulation. These results identify AuGL+PEG as a promising candidate nanomaterial for future applications in neuromodulation, cognitive enhancement, and the treatment of neurodegenerative diseases.

We present the tightest cosmic microwave background (CMB) lensing constraints to date on the growth of structure by combining CMB lensing measurements from the Atacama Cosmology Telescope (ACT), the South Pole Telescope (SPT), and Planck. Each of these surveys individually provides lensing measurements with similarly high statistical power, achieving signal-to-noise ratios of approximately 40. The combined lensing band powers represent the most precise CMB lensing power spectrum measurement to date with a signal-to-noise ratio of 61 and an amplitude of A_{lens}^{recon}=1.025±0.017 with respect to the theory prediction from the best-fit CMB Planck-ACT cosmology. The band powers from all three lensing datasets, analyzed jointly, yield a 1.6% measurement of the parameter combination S_{8}^{CMBL}≡σ_{8}(Ω_{m}/0.3)^{0.25}=0.825_{-0.013}^{+0.015}. Including dark energy spectroscopic instrument baryon acoustic oscillation (BAO) data improves the constraint on the amplitude of matter fluctuations to σ_{8}=0.829±0.009 (a 1.1% determination). When combining with uncalibrated supernovae from Pantheon+, we present a 4% sound-horizon-independent estimate of H_{0}=66.4±2.5  km s^{-1} Mpc^{-1}. The joint lensing constraints on structure growth and present-day Hubble rate are fully consistent with a ΛCDM model fit to the primary CMB data from Planck and ACT. While the precise upper limit is sensitive to the choice of data and underlying model assumptions, when varying the neutrino mass sum within the ΛCDM cosmological model, the combination of primary CMB, BAO, and CMB lensing drives the probable upper limit for the mass sum towards lower values, comparable to the minimum mass prior required by neutrino oscillation experiments.

The binary black hole signal GW250114, the loudest gravitational wave detected to date, offers a unique opportunity to test Einstein's general relativity (GR) in the high-velocity, strong-gravity regime and probe whether the remnant conforms to the Kerr metric. Upon perturbation, black holes emit a spectrum of damped sinusoids with specific, complex frequencies. Our analysis of the postmerger signal shows that at least two quasinormal modes are required to explain the data, with the most damped remaining statistically significant for about one cycle. We probe the remnant's Kerr nature by constraining the spectroscopic pattern of the dominant quadrupolar (ℓ=m=2) mode and its first overtone to match the Kerr prediction to tens of percent at multiple postpeak times. The measured mode amplitudes and phases agree with a numerical-relativity simulation having parameters close to GW250114. By fitting a parametrized waveform that incorporates the full inspiral-merger-ringdown sequence, we constrain the fundamental (ℓ=m=4) mode to tens of percent and bound the quadrupolar frequency to within a few percent of the GR prediction. We perform a suite of tests-spanning inspiral, merger, and ringdown-finding constraints that are comparable to, and in some cases 2-3 times more stringent than those obtained by combining dozens of events in the fourth Gravitational-Wave Transient Catalog. These results constitute the most stringent single-event verification of GR and the Kerr nature of black holes to date, and outline the power of black-hole spectroscopy for future gravitational-wave observations.

We report on a high-precision measurement of the D(γ,n)p photodisintegration reaction at the newly commissioned Shanghai Laser Electron Gamma Source, employing a quasimonochromatic γ-ray beam from Laser Compton Scattering. The cross sections were determined over E_{γ}=2.327-7.089  MeV, achieving up to a factor of 2.2 improvement in precision near the neutron separation threshold. Combined with previous data in a global Markov chain Monte Carlo analysis using dibaryon effective field theory, we obtained the unprecedentedly precise p(n,γ)D cross sections and thermonuclear rate, with a precision up to ≈4 times higher than previous evaluations. Implemented in a standard Big Bang nucleosynthesis framework, this new rate decreases uncertainty of the key cosmological parameter of baryon density Ω_{b}h^{2} by up to ≈16% relative to the Laboratory for Underground Nuclear Astrophysics (LUNA) result. A residual ≈1.2σ tension between Ω_{b}h^{2} constrained from primordial D/H observations and cosmic microwave background measurements persists, highlighting the need for improved dd reaction rates and offering potential hints of new physics beyond the standard model of cosmology.

The amplification of magnetic fields is crucial for understanding the observed magnetization of stars and galaxies. Turbulent dynamo is the primary mechanism responsible for that but the understanding of its action in a collapsing environment is still rudimentary and relies on limited numerical experiments. We develop an analytical framework and perform numerical simulations to investigate the behavior of small-scale and large-scale dynamos in a collapsing turbulent cloud. This approach is also applicable to expanding environments and facilitates the application of standard dynamo theory to evolving systems. Using a supercomoving formulation of the magnetohydrodynamic equations, we demonstrate that dynamo action in a collapsing background leads to a superexponential growth of magnetic fields in time, significantly faster than the exponential growth seen in stationary turbulence. The enhancement is mainly due to the increasing eddy turnover rate during the collapse, which boosts the instantaneous growth rate of the dynamo. We also show that the scaling of final saturated magnetic field strength with density robustly exceeds the expectation from considerations of pure flux-freezing. Apart from establishing a formal framework for studying magnetic field evolution in collapsing (or expanding) turbulent plasmas, these findings suggest that during star and galaxy formation magnetic fields can become dynamically relevant much earlier than previously thought.

The hierarchical interplay among gravity, magnetic fields, and turbulence in forming massive protostellar clusters remains elusive. We present high-resolution (~14 arc seconds ≃ 0.05 parsecs), 850-micrometer dust polarization and C18O line observations of Cepheus A using JCMT SCUBA-2/POL-2 and HARP. Our analysis reveals aligned gravitational (G), magnetic (B), and velocity fields (K), with an energy hierarchy of [Formula: see text]. Gravity, as the primary driver, induces gas flows and drags in B-field lines. Magnetic tension, as a secondary force, regulates turbulence, enabling ordered flows with an accretion rate of ~2.1 ± 0.4 × 10-4 M⊙ per year. This challenges the conventional view of B-fields resisting collapse in the clump/hub scale, instead showing cooperation with gravity. The ~0.6-parsec clump-scale B-field (with a mean position angle of ~45°) aligns coherently with fields at cloud (~5 parsecs), core (~0.05 parsecs), and disk (~2000 astronomical units) scales, offering key insights into the role of magnetic fields in multiscale star formation dynamics.

M31 UCXB-1 is one of the brightest X-ray point sources in the bulge of M31, with a peak X-ray luminosity L 0.5 - 10 keV = 2 . 9 - 0.2 + 0.2 × 10 38 erg s - 1 . Both XMM-Newton and Chandra observations have detected an eclipsing signal with a period of about 465 s from this source, and we note that the periodic signal is detected exclusively during the source's high-luminosity states. This signal probably originates from its orbital motion; therefore, it is an ultra-compact X-ray binary (UCXB) candidate with the highest X-ray luminosity. Our theoretical analyses show that M31 UCXB-1 is in good agreement with the luminosity-orbital period relation (L 2-10 keV-P orb) of the black hole/neutron star-white dwarf (BH/NS-WD) UCXB system. Moreover, our spectral analyses indicate that the primary in M31 UCXB-1 is more likely to be a BH than an NS. The results show that M31 UCXB-1 is a BH-WD system, with the shortest orbital period, the possibly strongest gravitational wave emission, and the most massive WD among the known UCXBs.

The traditional definition of the circumstellar habitable zone (HZ) focuses on liquid water, but neglects the crucial role of ultraviolet (UV) radiation in prebiotic chemistry. Low-mass stars typically emit insufficient UV radiation for photochemistry throughout the liquid water HZs (LW-HZs) during quiescent states. However, frequent flares can provide substantial UV fluxes, potentially fostering habitable conditions. We refine the concept of a UV radiation HZ (UV-HZ) by incorporating a temperature-dependent model for RNA precursor synthesis. Furthermore, we explore a parameterized spectral energy distribution model and adopt an empirical flare frequency distribution for flares on different stars to quantify their UV contribution. Applying this framework to different flaring stars, we find that the UV-HZ around low-mass stars can extend to inner regions and overlap with the traditional HZ in wide ranges. Applying the analysis to 9 planets around Kepler flaring stars, three planets are located within both the refined UV-HZ and the LW-HZ without causing ozone depletion. Our findings highlight the significant role of flares in expanding the potential for life around low-mass stars, offering a revised perspective on exoplanet habitability criteria.

Cosmic voids, the large underdense regions of our Universe, have emerged over the past decade as powerful cosmological laboratories: their simple dynamics, sensitivity to local gravitational effects and cosmic expansion, and ability to span large volumes, make them uniquely suited to test fundamental physics. Fueled by advances in theory, simulations, and observations, void science has matured into a precision tool for constraining the parameters of the standard cosmological model and its possible extensions. In this review, we provide a comprehensive description of the statistical tools developed to characterize voids, the theoretical models that link them to cosmological parameters, and the methodologies used to extract information from survey data. We highlight the growing synergy between void-based observables and other cosmological probes, and showcase the increasingly stringent constraints derived from voids measured from current and expected for upcoming surveys' data. With the advent of the next generation of galaxy surveys, voids are poised to play a central role in the future of cosmology, turning what was once regarded as emptiness into one of the most promising frontiers of fundamental science.

Tidal disruption events (TDEs), which occur when stars enter the tidal radii of supermassive black holes (SMBHs) and are subsequently torn apart by their tidal forces, represent intriguing phenomena that stimulate growing research interest and pose an increasing number of puzzles in the era of time-domain astronomy. Here, we report an unusual X-ray transient, XID 935, discovered in the 7 Ms Chandra Deep Field-South, the deepest X-ray survey ever. XID 935 experienced an overall X-ray dimming by a factor of more than 40 between 1999 and 2016. Not monotonically decreasing during this period, its X-ray luminosity increased by a factor > 27 within 2 months, from L 0.5 - 7 keV < 10 40.87 erg s-1 (October 10, 2014-January 4, 2015) to L 0.5 - 7 keV = 10 42.31 &#xb1; 0.20 erg s-1 (March 16, 2015). The X-ray position of XID 935 is located at the center of its host galaxy with a spectroscopic redshift of 0.251, whose optical spectra do not display emission characteristics associated with an active galactic nucleus. The peak 0.5-2.0 keV flux is the faintest among all the X-ray-selected TDE candidates to date. Thanks to a total exposure of &#x223c; 9.5 Ms in the X-ray bands, we manage to secure relatively well-sampled, 20-year-long X-ray light curves of this deepest X-ray-selected TDE candidate. We find that a partial TDE model could not explain the main declining trend. An SMBH binary TDE model is in acceptable accordance with the light curves of XID 935; however, it fails to match short-timescale fluctuations exactly. Therefore, the exceptional observational features of XID 935 provide a key benchmark for refining quantitative TDE models and simulations.

Novae are thermonuclear eruptions on accreting white dwarfs in interacting binaries. Although most of the accreted envelope is expelled, the mechanism-impulsive ejection, multiple outflows or prolonged winds, or a common-envelope interaction-remains uncertain. Gigaelectronvolt &#x3b3;-ray detections from >20 Galactic novae establish these eruptions as nearby laboratories for shock physics and particle acceleration, underscoring the need to determine how novae eject their envelopes. Here we report on near-infrared interferometry, supported by multiwavelength observations, of two &#x3b3;-ray-detected novae. The images of the very fast 2021 nova V1674 Her, taken just 2-3&#x2009;days after discovery, reveal the presence of two perpendicular outflows. The interaction between these outflows probably drives the observed &#x3b3;-ray emission. Conversely, the images of the very slow 2021 nova V1405 Cas suggest that the bulk of the accreted envelope was ejected more than 50&#x2009;days after the eruption began, as the nova slowly rose to its visible peak, during which the envelope engulfed the system in a common-envelope phase. These images offer direct observational evidence that the mechanisms driving mass ejection from the surfaces of accreting white dwarfs are not as simple as previously thought, revealing multiple outflows and delayed ejections.

The depletion of Antarctic stratospheric ozone since the 1970s, and the resulting increase in UV radiation reaching the Earth's surface, have posed a well-recognized threat to polar aquatic and terrestrial ecosystems. Although this phenomenon is primarily driven by anthropogenic emissions, natural processes linked to volcanic activity and changes in solar irradiance can also influence ozone levels over time. Understanding past ozone changes over Antarctica is therefore essential for constraining the amplitude of its natural variability. Given the sensitivity of diatoms to different environmental conditions, we investigated the potential of these organisms as proxies for ozone variability by analyzing their relative abundance along a proglacial lake sediment profile dated using excess 210Pb. We found that a specific diatom assemblage dominated by Gomphonema sp., Nitzschia cf. kleinteichiana, Humidophila tabellariaeformis, and Pinnularia borealis shows significant responses to measured ozone data from Faraday/Vernadsky station, allowing the development of a quantitative reconstruction model for the modern epoch. Applying this model to a Holocene sediment core from the same ice-free area, we obtained a millennial-scale reconstruction of past ozone variability. Our results indicate that the magnitude of recent ozone depletion is unprecedented over the past 7,700 years. These findings demonstrate the value of lake-sediment diatom assemblages as proxies for reconstructing past stratospheric ozone dynamics in Antarctica and contribute to a deeper understanding of long-term atmosphere-biosphere interactions in polar regions.

The elemental compositions of exoplanets encode information about their formation environments and internal structures. While volatile ratios such as carbon-to-oxygen (C/O) are used to trace formation location, the rock-forming elements-magnesium (Mg), silicon (Si), and iron (Fe)-govern interior mineralogy and are commonly assumed to reflect the host star's abundances. Yet this assumption remains largely untested. Ultra-hot Jupiters, gas-giant exoplanets with dayside temperatures above 3000 K, provide rare access to refractory elements that remain gaseous. Here we present high-resolution thermal emission spectroscopy of the exoplanet WASP-189b ( T e q = 335 4 - 34 + 27 K) obtained with the Immersion Grating Infrared Spectrometer (IGRINS) on Gemini South. We detect neutral iron (Fe I), magnesium (Mg I), silicon (Si I), water (H2O), carbon monoxide (CO), and hydroxyl (OH) at signal-to-noise ratios exceeding 4, and retrieve their elemental abundances. We show that the Mg/Si, Fe/Mg, and Si/Fe ratios are consistent with stellar values, while the refractory-to-volatile ratio is enhanced by roughly a factor of 2. These findings demonstrate that giant-planet atmospheres can preserve stellar-like rock-forming ratios, providing an empirical validation of the stellar-proxy assumption that underpins planetary composition and formation models across exoplanet systems.

Type II-P supernovae (SNeII-P) are the most common class of core-collapse SNe in the local Universe and play critical roles in many aspects of astrophysics. Since decades ago theorists have predicted that SNeII-P may originate not only from single stars but also from interacting binaries. While &#x223c;20 SNII-P progenitors have been directly detected on pre-explosion images, observational evidence still remains scarce for this speculated binary progenitor channel. In this work, we report the discovery of a red supergiant progenitor for the Type II-P SN2018gj. While the progenitor resembles those of other SNeII-P in terms of effective temperature and luminosity, it is located in a very old environment, and SN2018gj has an abnormally short plateau in the light curve. With state-of-the-art binary evolution simulations, we find these characteristics can only be explained if the progenitor of SN2018gj is the merger product of a close binary system, which developed a different interior structure and evolved over a longer timescale compared with single-star evolution. This work provides the first compelling evidence for the long-sought binary progenitor channel toward SNeII-P, and our methodology serves as an innovative and pragmatic tool to motivate further investigations into this previously hidden population of SNeII-P from binaries.

Here we present results from an experiment performed at the GSI Helmholtz Center for Heavy Ion Research. A mono-energetic beam of chromium ions with initial energies of &#xa0;~&#xa0;450 MeV was fired through a magnetized interaction region formed by the collision of two counter-propagating laser-ablated plasma jets. While laser interferometry revealed the absence of strong fluid-scale turbulence, acceleration and diffusion of the beam ions was driven by wave-particle interactions. A possible mechanism is particle acceleration by electrostatic, short scale length kinetic turbulence, such as the lower-hybrid drift instability.

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This paper investigates the degradation mechanism of the photon-number-encoded entanglement swapping protocol under the amplitude damping noise channel. By establishing a beam splitter physical model to simulate the energy dissipation process, the evolution density matrix of the input states [Formula: see text] and [Formula: see text] under independent noise channels is analytically derived, and the density matrix, fidelity, and concurrence of the target particle pair after entanglement swapping are presented. Furthermore, for the case where the initial states are maximally entangled states, this paper numerically simulates the variation curves of the fidelity and concurrence of the system after entanglement swapping with the noise parameter. The results show that as the noise intensity increases, both the fidelity and concurrence of the target system exhibit a decreasing trend. Simultaneously, due to the presence of noise, even if the input states are maximally entangled, the entanglement of the target system after swapping may be destroyed. Based on this, the study further deduces the constraint conditions required to maintain system entanglement in this scenario. Given the restrictive effect of these constraints on entanglement maintenance, this paper also specifically examines the fidelity and concurrence of the target state output from entanglement swapping in the case of 50&#xa0;:&#xa0;50 beam splitters when the input states are both maximally entangled. The research finds that in this case, since the constraints are not satisfied, even if the input states are maximally entangled, the entanglement of the output state completely disappears.

A significant performance inhibitor of free-space continuous variable quantum key distribution (CVQKD) is turbulence, which gives rise to wavefront phase and amplitude aberrations. We demonstrate that in a turbulent channel, during coherent state transmissions from a continuous-wave laser, that the interferometric visibility between the local oscillator (LO) and quantum signal decreases. A solution to this is incorporating adaptive optics at the receiver to correct phase and amplitude aberrations in the wavefronts of the received quantum signal. We demonstrate the increased interferometric visibility and decrease in its fluctuations in a 60 cm and 30 m turbulent channel when using adaptive optics through channel characterisation. In an ideal CVQKD system, we show that this leads to more precise and larger positive secret key rates, improving the performance of free-space CVQKD in turbulent channels.