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Intermediate-mass planets, from super-Earth to Neptune-sized bodies, are the most common types of planet in the Galaxy 1 . The prevailing theory of planet formation—core accretion 2 —predicts the existence of substantially fewer intermediate-mass giant planets than have been observed 3 , 4 . The competing mechanism for planet formation—disk instability—can produce massive gas giant planets on wide orbits, such as HR 8799 5 , by direct fragmentation of the protoplanetary disk 6 . Previously, fragmentation in magnetized protoplanetary disks has been considered only when the magneto-rotational instability is the driving mechanism for magnetic field growth 7 . However, this instability is naturally superseded by the spiral-driven dynamo when more realistic, non-ideal magneto-hydrodynamic conditions are considered 8 , 9 . Here, we report on magneto-hydrodynamic simulations of disk fragmentation in the presence of a spiral-driven dynamo. Fragmentation leads to the formation of long-lived bound protoplanets with masses that are at least one order of magnitude smaller than in conventional disk instability models 10 , 11 . These light clumps survive shear and do not grow further owing to the shielding effect of the magnetic field, whereby magnetic pressure stifles the local inflow of matter. The outcome is a population of gaseous-rich planets with intermediate masses, while gas giants are found to be rarer, in qualitative agreement with the observed mass distribution of exoplanets. The formation mechanism of the most common type of planet in the Galaxy, those with masses between those of the Earth and Neptune, is far from clear. However, simulations of disk fragmentation presented here, which incorporate a spiral-driven dynamo, produce protoplanets of the right mass and longevity.

Gravitational instability (GI) has long been considered a viable pathway for giant planet formation in protoplanetary disks (PPDs), especially at wide orbital separations or around low-mass stars where core accretion faces significant challenges. However, a primary drawback is that disk fragmentation from GI is generally found to produce overmassive clumps, typically in the mass range of brown dwarfs, although most numerical studies adopt simplified cooling prescriptions or those with limited numerical resolution. We conduct a suite of global three-dimensional radiation hydrodynamics simulations of self-gravitating PPDs using the meshless finite-mass method. By implementing radiation transport via the M1 closure and systematically varying disk mass and opacity, we show that increasing disk mass and lowering opacity promote fragmentation by enhancing radiative cooling. Nonfragmenting disks settle into a gravitoturbulent state with low-order spiral structures and effective angular momentum transport characterized by α∼βcool−1 . In fragmenting disks, a subset of gravitationally bound clumps survives as long-lived fragments. Their initial masses form a consistent distribution around Σ · λT · 2(cs/ΩK) (with λT denoting the Toomre wavelength), corresponding to ∼0.3–10 MJ in our simulations, consistent with the masses of gas giants. These results demonstrate that GI can produce planet-mass fragments under more realistic conditions, reinforcing it as a viable gas giant formation pathway and motivating further studies of fragment evolution and observational signatures.

Tidal disruption events (TDEs) in active galactic nuclei (AGNs) mark a regime where traditional vacuum models fail to capture the full dynamics, especially due to interaction between stellar debris and preexisting accretion disks. We perform meshless hydrodynamic simulations incorporating both general relativistic (GR) effects and radiative cooling to study TDEs in AGNs with different orbital inclinations (θinc) of the disrupted star, ranging from projected prograde to retrograde orbits. We postprocess the simulations to derive multiwavelength light curves and identify several distinct features in the light curves, including a precursor flare from early debris-disk collision and a major flare driven by fallback. The dynamics of the stellar debris and accretion disk, and subsequently the light-curve features, are strongly affected by θinc and GR effects. Retrograde orbits (θinc = 135°) yield a more luminous, shorter major flare and a more prominent precursor than prograde ones (θinc = 22 .° 5). During fallback, prograde cases (θinc = 22 .° 5, 45°) develop a central cavity with spirals in the inner region of the AGN disk, leading to transient UV/X-ray suppression accompanied by oscillations, while higher inclinations (θinc = 90°, 135°) form a gradually tilting inner disk, potentially causing UV/X-ray dips via geometric effects at certain viewing angles. Relativistic apsidal precession alters stream collisions, producing structural differences in the inner disk, outer disk, and debris compared to Newtonian cases, and drives quasi-periodic signals in prograde configurations. These results provide predictive diagnostics for identifying AGN TDEs and interpreting observed light-curve diversity.

In the core accretion model, planetesimals grow by mutual collisions and engulfing millimeter-to-centimeter particles, i.e., pebbles. Pebble accretion can significantly increase the accretion efficiency and help explain the presence of planets on wide orbits. However, the pebble supply is typically parameterized as a coherent pebble mass flux, sometimes being constant in space and time. Here we solve the dust advection and diffusion within viciously evolving protoplanetary disks to determine the pebble supply self-consistently. The pebbles are then accreted by planetesimals interacting with the gas disk via gas drag and gravitational torque. The pebble supply is variable with space and decays with time quickly, with a pebble flux below 10 M ⊕ Myr−1 after 1 Myr in our models. As a result, only when massive planetesimals (>0.01 M ⊕) are luckily produced by the streaming instability or the disk has low viscosity (α ∼ 0.0001) can the herd of planetesimals grow over a Mars mass within 2 Myr. By then, planetesimals only capture pebbles about 50 times their mass and as little as 10 times beyond 20 au due to limited pebble supply. Further studies considering multiple dust species in various disk conditions are warranted to fully assess the realistic pebble supply and its influence on planetesimal growth.

Background The complex physical structure and abundant repeat sequences make it difficult to assemble the mitogenomes of seed plants, especially gymnosperms. Only approximately 33 mitogenomes of gymnosperms have been reported. However, as the most widely distributed and the second largest family among gymnosperms, Cupressaceae has only six assembled mitogenomes, including five draft mitogenomes and one complete mitogenome, which has greatly hindered the understanding of mitogenome evolution within this large family, even gymnosperms. Results In this study, we assembled and validated the complete mitogenome of Thuja sutchuenensis , with a size of 2.4 Mb. Multiple sequence units constituted its complex structure, which can be reduced to three linear contigs and one small circular contig. The analysis of repeat sequences indicated that the numbers of simple sequence repeats increased during the evolutionary history of gymnosperms, and the mitogenome of Thuja sutchuenensis harboured abundant extra-long repeats (more than 5 kb). Additionally, the longest repeat sequence identified in these seven gymnosperms also came from the mitogenome of Thuja sutchuenensis , with a length of up to 47 kb. The analysis of colinear blocks and gene clusters both revealed that the orders of mitochondrial genes within gymnosperms was not conserved. The comparative analysis showed that only four tRNAs were shared by seven gymnosperms, namely, trnD-GUC, trnE-UUC, trnI-CAU and trnY-GUA . Furthermore, four genes have undergone potential positive selection in most gymnosperm species, namely, atp8 , ccmB , mttB and sdh4 . Conclusion We successfully assembled the second complete mitogenome within Cupressaceae and verified that it consisted of multiple sequence units. Our study also indicated that abundant long repeats may contribute to the generation of the complex conformation of the mitogenome of Thuja sutchuenensis . The investigation of Thuja sutchuenensis ’s mitogenome in our study provides new insight into further understanding the complex mitogenome architecture within gymnosperms.

Global climate problems and the sharp decline in biodiversity have attracted widespread attention. Orchids, as the “flagship” species of biodiversity, are important indicators of ecological changes. This study took Chongqing as the study area and conducted a comprehensive survey of orchids through field investigation combined with data review to clarify Chongqing’s diversity distribution pattern. The distribution of orchids was characterized by “high in the east and low in the west, high in the north and low in the south” horizontally. Vertically, the distribution was characterized by an obvious “unimodal distribution”, with higher abundance in the low and middle altitude areas of 500–1499 m. The minimum temperature of the coldest month (Bio6), isothermality (Bio3), altitude (Bio20), and precipitation of the wettest season (Bio16) were the main environmental factors affecting the distribution of the orchid habitat. The suitable habitat of orchids would be greatly reduced in the future (2070SSP-585), and the suitable habitat tends to migrate to the high-altitude areas; therefore, we should pay more attention to the conservation and sustainable use of orchid plant resources.

Calcium-aluminum-rich inclusions (CAIs) in carbonaceous chondritic meteorites are the oldest relics in the solar system. Notably, their radiogenic ages indicate a brief (100 kyr) condensation episode. In contrast, the reservoirs of the short-lived isotopes in CAIs, presumably supernovae or asymptotic giant stars, pollutes star-forming regions in giant molecular cloud complexes (GMC) over much longer (Myr) timescales. Through a series of numerical simulations, we show here the possibility that, within an extended region (~2–3 au), nearly all “presolar” CAI-loaded grains in the infalling clouds were sublimated and subsequently recondensed during the early (≲105 yr) infall and formation phases of Class 0 disks. We adopt a set of initial conditions from a previous hydrodynamic simulation of GMC collapse and young stellar cluster formation. We analyze the evolution of the disk’s thermal distribution and dynamical structure resulting from the interaction between circumstellar disks and infalling gas. Our follow-up simulations, performed at much higher resolution, show significant and rapid changes in disk orientation and morphology due to the dynamic infall of external streamers. Warps and global spiral density waves commonly emerge, leading to intense dissipation that heats the gas to sufficiently high temperatures to sublimate prior-generation CAIs. This solid-to-gas phase transition is followed by subsequent cooling and recondensation. The CAIs contained in meteorites today may therefore be relics of the last major episode of infall onto Class 0 disks.

Background Medicinal plants have always played an important role in the history of human health. However, the populations and sustainable use of medicinal plants have been severely affected by human activities and climate change. Little is known about the current conservation status and distribution pattern of medicinal plants. In this study, based on accurate geographical distribution information of 9756 medicinal plants, we identified diversity hotspots and conservation gaps, evaluated conservation effectiveness of nature reserves, and predicted suitable habitat areas for medicinal plants in China to provide scientific guidance for their long-term conservation and sustainable use. Results A total of 150 diversity hotspot grid cells, mainly concentrated in central and southern China, were identified. These only accounted for 5% of the total distribution area but contained 96% of the medicinal plants of the country. The hotspot grid cells included all traditional hotspot areas, but we also detected three new hotspots, namely Mufu-Lushan Mountains, Tianshan-Altai Mountains, and Changbai Mountains. The current national and provincial nature reserves protect 125 hotspot grid cells, which harbor 94% of all medicinal plants. However, 25 hotspot grid cells, distributed in the Tianshan-Altai Mountains and Hengduan Mountains, are located outside the national and provincial nature reserves. An analysis of the predicted effects of climate change indicated that the suitable habitat areas will shift from southern to northern China, and that southern China will face a considerable loss of suitable habitat areas, while the east and west parts of China will encompass remarkably more suitable habitat areas in the future. Conclusions The current conservation networks have achieved high conservation effectiveness with regard to medicinal plants; however, the conservation gaps we identified should not be neglected, and conservation planning needs to take into account the predicted shifts of some hotspots of medicinal plants due to climate change.

Background The co-occurrence of cardiometabolic diseases (CMDs) is increasingly prevalent and has been associated with an additive risk of dementia in older adults, but the extent to which this risk can be offset by a healthy lifestyle is unknown. We aimed to examine the associations of cardiometabolic multimorbidity and lifestyle with incident dementia and related brain structural changes. Methods This prospective study extracted health and lifestyle data from 171 538 UK Biobank participants aged 60 years or older without dementia at baseline between 2006 and 2010 and followed up until July 2021, as well as brain structural data in a nested imaging subsample of 11 972 participants. Cardiometabolic multimorbidity was defined as the presence of two or more CMDs among type 2 diabetes, coronary heart disease, stroke, and hypertension. Lifestyle patterns were determined based on 7 modifiable lifestyle factors including smoking, alcohol consumption, physical activity, diet, sleep duration, sedentary behavior, and social contact. Results Over a median follow-up of 12.3 years, 4479 (2.6%) participants developed dementia. The presence of CMDs was dose-dependently associated with an increased risk of dementia. Compared with participants with no CMDs and a favourable lifestyle, those with ≥ 3 CMDs and an unfavourable lifestyle had a five times greater risk of developing dementia (HR 5.33, 95% CI 4.26–6.66). A significant interaction was found between CMD status and lifestyle ( P interaction =0.001). The absolute difference in incidence rates of dementia per 1000 person years comparing favourable versus unfavourable lifestyle was − 0.65 (95% CI − 1.02 to − 0.27) among participants with no CMDs and − 5.64 (− 8.11 to − 3.17) among participants with ≥ 3 CMDs, corresponding to a HR of 0.71 (0.58–0.88) and 0.42 (0.28–0.63), respectively. In the imaging subsample, a favourable lifestyle was associated with larger total brain, grey matter, and hippocampus volumes across CMD status. Conclusion Our findings suggest that adherence to a healthy lifestyle might substantially attenuate dementia risk and adverse brain structural changes associated with cardiometabolic multimorbidity.