Nature, May 27, 2026, Vol.593, No.7860.

Nature, vol. 593, No.7860, May 27th, 2002/KLOC-0.

Astronomy astronomy

Evidence of immiscibility of hydrogen and helium under Jupiter's internal conditions

Evidence of immiscibility of hydrogen and helium under Jupiter's internal conditions

Authors: S. Bhrigu, P. Loubere, M. Milot, J. R. Riggs, P. M. Cyrus, J. H. eggert, etc.

Link:

/articles/s 4 1586-02 1-035 16-0

abstract

The phase behavior of warm and dense hydrogen-helium mixture affects people's understanding of Jupiter and Saturn and their internal structural evolution. However, although the H-He phase is of great significance, its phase behavior is still difficult to constrain under the conditions of related planets, because it is extremely challenging to determine it by calculation, and extreme temperatures and pressures are also difficult to achieve through experiments.

The research team reported that the 2He sample pre-compressed in the diamond anvil can reach the appropriate temperature and pressure by laser-driven impact compression. This enabled the research team to detect the properties of the H-He mixture under Jupiter's internal conditions, and revealed the immiscible region along the Yugongniu curve.

The obvious discontinuous change of sample reflectivity shows that at 10200 K, the region ends above 150 GePa; At 4700 K, the reflectivity above 93 GPa has changed more subtly. Considering the pressure-temperature distribution of Jupiter, the experimental immiscibility constraints of these near-Taiyang Yuan mixtures show that the H-He phase separation affects a large part of Jupiter, and the research team estimates that this part accounts for about 65,438+05% of Jupiter's radius.

This discovery provides microphysical support for Jupiter model, which uses layered interior to explain the observations of Juno and Galileo spacecraft.

abstract

The phase state of warm and dense hydrogen-helium mixture affects our understanding of the evolution and internal structure of Jupiter and Saturn. However, despite its importance, the phase behavior under the relevant planetary conditions is still rarely limited, because it is difficult to determine by calculation, and because the limits of temperature and pressure are difficult to achieve by experiments. Here, we report that proper temperature and pressure can be obtained by laser-driven impact compression of H2 helium samples pre-pressed in diamond anvil. This enables us to explore the properties of the mixture under Jupiter's internal conditions, revealing the immiscible region along the Chamois Niortais Fc of Hugo. The obvious discontinuous change of the reflectivity of the sample shows that the region ends above 6543 8+050 gigapascals at10,200 Kelvin, and the reflectivity changes more subtly above 93 gigapascals at 4700 Kelvin. Considering the pressure-temperature curve of Jupiter, the experimental immiscibility constraints of these near-Taiyang Yuan mixtures show that phase separation affects a large part of Jupiter's interior-we estimate that the radius is about 15%. This discovery provides microphysical support for Jupiter models, which call for layered interior to explain the observations of Juno and Galileo spacecraft.

materials science

Long-range Non-topological Edge Current in Charge Neutral Graphene

Long-range Non-topological Edge Current in Charge Neutral Graphene

Authors: A. Aharon-Steinberg, A. Margaret, D. J. Pereiro, K. Bagani, T. Holder, Y. Mia Sudov, etc.

Link:

/articles/s 4 1586-02 1-0350 1-7

abstract

Van der Waals heterostructure shows many unique electronic properties. Single-layer, double-layer and thin-layer graphene, transition metal dihalides and Mohr superlattices all show obvious nonlocal effects.

However, the origin of these effects has aroused heated debate. Graphene, in particular, shows great nonlocality when the charge is neutral, which attracts various explanations.

Using SQUID on the tip for nano-scale thermal imaging and scanning gate imaging, the research team proved that the common charge accumulation at the edge of graphene would lead to huge nonlocality and narrow conductive channels supporting long-range current.

Unexpectedly, although the edge conductance has little effect on the current under zero magnetic field, it will lead to field-induced decoupling between the edge and the bulk transport under medium magnetic field. The resulting huge nonlocality, when the charge is neutral and far away from the edge disorder, produces a strange flow pattern sensitive to the edge disorder, in which the charge can resist the global electric field flow.

The observed one-dimensional edge transport is universal and non-topological, which is expected to support the non-local transport in many electronic systems, provide clues for many controversial in-depth studies, and link it with the remote guided electronic state at the edge of the system.

abstract

Van der Waals heterostructure shows many unique electronic properties. It has been found that monolayer, bilayer and several layers of graphene, transition metal disulfide and moire superlattice show significant nonlocal effects. However, the origin of these influences is hotly debated. Graphene, in particular, shows great nonlocality when it is electrically neutral, and this amazing behavior has caused different explanations. The superconducting quantum interference device (SQUID-on-tip) on the tip is used for nano-scale thermal and scanning gate imaging. Here, we prove that the charge accumulation that often occurs at the edge of graphene leads to huge nonlocality and produces a narrow conductive channel that supports long-range current. Unexpectedly, although the edge conductance has little effect on the current in the zero magnetic field, it leads to the field-induced decoupling between the edge and the bulk transport in the medium magnetic field. When it is electrically neutral and far away from it, the huge nonlocality will produce a strange flow mode sensitive to edge disorder, in which the charge can flow against the overall electric field. The observed one-dimensional edge transport is general and non-topological, and it is expected to support non-local transport in many electronic systems, which provides many controversial opinions and relates them to the long-range electronic States at the edge of the system.

Perovskite superlattice from lead halide perovskite nanocubes

Perovskite superlattice of lead halide perovskite nanocubes

Authors: ihor cherniukh, Gabriele rainò, thilo st? Ferle, Max Burian, Alex Travesset, Denys Naumenko, etc.

Link:

/articles/s 4 1586-02 1-03492-5

abstract

Cesium-lead halide perovskite nanocrystals are promising building blocks for long-range ordered superlattices, because they have high oscillation intensity of bright triplet excitons, slow dephasing (coherence time up to 80 picoseconds) and uneven broadening of minimum emission lines. So far, only single-component superlattices and simple cubic stacks have been designed by these nanocrystals.

The research group proposed perovskite-type (ABO3 _ 3 _ 3) binary and ternary nanocrystalline superlattices, which were assembled by the shape orientation of cubic CsPbBr3 _ 3 _ 3 nanocrystals (occupying B and/or O lattice sites), spherical Fe3O4 or NaGdF4 _ 4 nanocrystals (A site) and truncated cubic PbS nanocrystals (B site).

These ABO3 _ 3 superlattices, as well as the binary NaCl and Al _ B2 superlattices displayed by the research group, indicate that the CsPbBr3 _ 3 nanocubes are highly oriented and ordered. They also show superfluorescence, which is a kind of collective emission, leading to photon burst, with ultrafast radiation attenuation (22 picoseconds), and can be used to customize ultra-bright (quantum) light sources.

The work of this research group laid a foundation for further exploring the complex and orderly perovskite mesostructure with useful functions.

abstract

Cesium-lead halide perovskite nanocrystals are promising building blocks for long-range ordered superlattices, which are due to the high oscillator strength of bright triplet excitons, slow dephasing (coherence time up to 80 picoseconds) and the minimum uneven broadening of emission lines. So far, only simple cubic stacked single-component superlattices have been designed from these nanocrystals. Here, we propose perovskite-type (ABO3 _ 3) binary and ternary nanocrystal superlattices, which are generated by shape-oriented co-assembly of spatially stable high-emission cubic CsPbBr3 _ 3 nanocrystals (occupying B and/or O lattice positions), spherical Fe3O4 or NaGdF4 _ 4 nanocrystals (A position) and truncated cubic PbS nanocrystals (B position). These ABO3 _ 3 superlattices, as well as the binary NaCl and AlB2 superlattices we have shown, show the high orientation and order of CsPbBr3 _ 3 nanocubes. They also show superfluorescence-a kind of collective emission, which leads to photon bursts with ultrafast radiation attenuation (22 picoseconds), and can be customized for ultra-bright (quantum) light sources. Our work paves the way for further exploration of complex, ordered and functionally useful perovskite mesostructures.

earth sciences

From 2003 to 2009, the global land evapotranspiration increased by 10%.

From 2003 to 20 19, the global land evapotranspiration increased by 10%.

Authors: Madeleine Pascalini-Campbell, John T. Reger, Chris Keshikesh Chandler Dan Poole Ka&; Matthew Radell

Link:

/articles/s 4 1586-02 1-03503-5

abstract

Accurate quantification of global land evapotranspiration is necessary to understand the variability of global water cycle, which is expected to intensify under climate change. At present, there are many sources of global evapotranspiration products, including models, remote sensing and field observation.

However, the existing methods contain a lot of uncertainties; For example, it is related to the model structure, or the observation value rises to the global level. Therefore, the changes and trends of global evapotranspiration are still unclear.

The research of the research group shows that from 2003 to 20 19, the global land evapotranspiration increased by10.2%, and the land precipitation was increasingly divided into evapotranspiration rather than runoff.

The result is an independent water balance set time series based on global land evapotranspiration and the corresponding uncertainty distribution. The data used are from Gravity Recovery and Climate Experiment (GRACE) and GRACE-FO satellite.

The change of global land evapotranspiration is positively related to El Nino-Southern Oscillation. However, the main driving force of this trend is the rise of surface temperature.

The findings of the research team provide an observation constraint for global land evapotranspiration, which is consistent with the assumption that global evapotranspiration will increase under climate warming.

abstract

Accurate quantification of global land evapotranspiration is necessary to understand the variability of global water cycle, which is expected to intensify under climate change. At present, global evapotranspiration products come from various sources, including models, remote sensing and field observation. However, the existing methods contain a lot of uncertainties; For example, it involves model structure or raising the observation results to the global level. Therefore, the changes and trends of global evapotranspiration are still unclear. Here, we show that the global land evapotranspiration increased by 102/cent between 2003 and 20 19, and land precipitation is increasingly divided into evapotranspiration rather than runoff. Our results are based on the global independent water balance time series of land evapotranspiration and the corresponding uncertainty distribution, using data from the Gravity Recovery and Climate Experiment (GRACE) and the GRACE-FO satellite. Is the change of global land evapotranspiration positively related to El Nino? O- southern oscillation. However, the main driving force of this trend is the rising surface temperature. Our findings provide an observational constraint for global land evapotranspiration, and are consistent with the hypothesis that global evapotranspiration should increase in a warming climate.

Groundwater level control for controlling greenhouse gas emission in peat land

Groundwater level controls greenhouse gas emissions from peatlands.

Authors: C.D. Evans, M.Peacock, A.J. Baird, R.R.E. Artz, A.Burden, N.Callaghan, etc.

Link:

/articles/s 4 1586-02 1-03523- 1

abstract

Peatlands around the world store more carbon than the carbon naturally existing in the atmosphere. However, many peatlands are under the pressure of agriculture, planting development and fire based on drainage, and the greenhouse gases emitted by drainage peatlands only account for about 3% of all man-made greenhouse gases. By protecting undrained peatlands and re-wetting the drainage system, people are stepping up their efforts to curb such emissions.

The research team reported the covariance data of CO2 eddy at 6 stations in Britain and Ireland1and the static box measurement data of CH4 at 4 stations1,and combined these data with the published data of all major peat biomes.

The results show that the annual average effective groundwater level (WTDE) exceeds all other ecosystems and management controls related to greenhouse gas emissions.

The research team estimated that for every reduction in WTDe of10cm, the net warming effect of CO2 and CH4 emissions (global warming potential is 100) will be reduced by at least 3 tons of CO2 per hectare every year until the WTDe is less than 30cm. Further increasing the water level will continue to produce a net cooling effect until WTDe is within the surface 10 cm.

The results show that the greenhouse gas emissions can be greatly reduced without stopping the productive utilization of agricultural peat land. For example, halving the WTDe of all drained agricultural peatlands can reduce the global anthropogenic emissions equivalent to more than 65,438+0%.

abstract

The global peatlands store more carbon than the carbon naturally existing in the atmosphere. However, many peatlands are under the pressure of agriculture, plantation development and fire based on drainage, which is equivalent to about 3% of all man-made greenhouse gases emitted by drained peatlands. Efforts to curb such emissions are being strengthened by protecting undrained peatlands and re-wetting drainage systems. Here, we report the eddy covariance data of carbon dioxide from UK and Ireland 16 and the static box measurement of methane from 4 1. We combine these data with published data from all major peat biomes. We find that the annual average effective groundwater depth (WTDe) exceeds all other controls on greenhouse gas flow related to ecosystem and management. We estimate that for every 65,438+00 cm reduction in WTDe, the net warming impact of CO2 and CH4 emissions (65,438+000 global warming potential) can be reduced, which is equivalent to at least 3 tons of CO2 per hectare per year until the WTDe is less than 30 cm. Further increasing the water level will continue to produce a net cooling effect until WTDe is within the surface 10 cen time. Our results show that the greenhouse gas emissions of peatlands used for agriculture can be greatly reduced without stopping their productive use. For example, halving WTDe in all drained agricultural peatlands can reduce the global anthropogenic emissions equivalent to more than 1%.

sociology

Universe access law of human flow

Universal law of crowd flow

Author: Markus Schl? Pfeiffer, Dong Lei, Kevin O'Keefe, Paul Santi, Michael Searle, Hadrian Salat, and so on.

Link:

/articles/s 4 1586-02 1-03480-9

abstract

Population mobility affects many aspects of cities, from the spatial structure of cities to the response of cities to epidemics. It is ultimately the key to social interaction, innovation and productivity.

The research team revealed a simple and robust scaling law, which captured the temporal and spatial spectrum of population movement based on large-scale population movement data in different cities around the world. According to this law, the number of tourists anywhere will decrease in inverse proportion to the square of the product of their visit frequency and travel distance.

The research group further proved that the spatio-temporal abortion flowing to different places has produced significant spatial clusters, and its regional distribution follows Ziff's law. Finally, an individual flow model based on exploration and preferential return is established, which provides a mechanism explanation for the discovered scaling law and emerging spatial structure.

The results of this study confirmed the long-standing conjecture of human geography and allowed to predict the repeated movement of people, which provided a basis for the application in urban planning, traffic engineering and reducing epidemics.

abstract

Population mobility affects many aspects of a city, from its spatial structure to its response to epidemics. It is ultimately the key to social interaction, innovation and productivity. However, our quantitative understanding of the total population flow is still incomplete. Existing models, such as gravity law or radiation model, focus on the pure spatial dependence of population movement and fail to capture the different frequencies of repeated visits to the same place. Here, we reveal a simple and robust law of proportionality, which captures the time and space spectrum of population movement based on the large-scale population movement data of cities around the world. According to this law, the number of tourists in any place decreases in inverse proportion to the square of the product of their visit frequency and travel distance. We further show that the spatio-temporal abortion flowing to different locations produces significant spatial clusters, and their regional distribution follows Zipf's law. Finally, we establish an individual migration model based on exploration and preferential return, which provides a mechanical explanation for the discovered scaling law and the emerging spatial structure. Our findings confirm the long-term speculation of human geography, and allow the prediction of regular flow, which provides a basis for urban planning, traffic engineering and the application of reducing epidemics.