The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe^0 system at 70-150 GPa and 800-2600 Kin a laser-heated diamond anvil cell.Using in situ...The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe^0 system at 70-150 GPa and 800-2600 Kin a laser-heated diamond anvil cell.Using in situ synchrotro n X-ray diffraction and ex situ transmission electron microscopy we show that the reduction of Mg-carbonate can be exemplified by:6 MgCO3+19 Fe=8 FeO+10(Mg0.6Fe^0.4)O+Fe7 C3+3 C.The presented results suggest that the interaction of carbonates with Fe^0 or Fe^0-bearing rocks can produce Fe-carbide and diamond,which can accumulate in the D"region,depending on its carbon to Fe ratio.Due to the sluggish kinetics of the transformation,diamond can remain metastable at the core-mantle boundary(CMB)unless it is in a direct contact with Fe-metal.In addition,it can be remobilized by redox melting accompanying the generation of mantle plumes.展开更多
Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majori...Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majority of these volatiles are hidden in the deep interior, where the high pressure–temperature conditions drastically and categorically alter the physics and chemistry of the volatiles. Like the bloodstream of an organism, the circulations and interactions of volatiles in the deep Earth modulate climate, resources, energy, natural hazards, and other factors that define the Earth as a unique living and changing planet.展开更多
Ultrahigh-temperature-pressure experiments are crucial for understanding the physical and chemical properties of matter.The recent development of boron-doped diamond(BDD)heaters has made such melting experiments possi...Ultrahigh-temperature-pressure experiments are crucial for understanding the physical and chemical properties of matter.The recent development of boron-doped diamond(BDD)heaters has made such melting experiments possible in large-volume presses.However,estimates of temperatures above 2600 K and of the temperature distributions inside BDD heaters are not well constrained,owing to the lack of a suitable thermometer.Here,we establish a three-dimensional finite element model as a virtual thermometer to estimate the temperature and temperature field above 2600 K.The advantage of this virtual thermometer over those proposed in previous studies is that it considers both alternating and direct current heating modes,the actual sizes of cell assemblies after compression,the effects of the electrode,thermocouple and anvil,and the heat dissipation by the pressure-transmitting medium.The virtual thermometer reproduces the power-temperature relationships of ultrahigh-temperature-pressure experiments below 2600 K at press loads of 2.8-7.9 MN(~19 to 28 GPa)within experimental uncertainties.The temperatures above 2600 K predicted by our virtual thermometer are within the uncertainty of those extrapolated from power-temperature relationships below 2600 K.Furthermore,our model shows that the temperature distribution inside a BDD heater(19-26 K/mm along the radial direction and<83 K/mm along the longitudinal direction)is more homogeneous than those inside conventional heaters such as graphite or LaCrO_(3) heaters(100-200 K/mm).Our study thus provides a reliable virtual thermometer for ultrahigh-temperature experiments using BDD heaters in Earth and material sciences.展开更多
The recent discovery of type-Ⅶboron-carbon clathrates with calculated superconducting transition temperatures approaching~100 K has sparked interest in exploring new conventional superconductors that may be stabilize...The recent discovery of type-Ⅶboron-carbon clathrates with calculated superconducting transition temperatures approaching~100 K has sparked interest in exploring new conventional superconductors that may be stabilized at ambient pressure.The electronic structure of the clathrate is highly tunable based on the ability to substitute different metal atoms within the cages,which may also be large enough to host small molecules.Here we introduce molecular hydrogen(H_(2))within the clathrate cages and investigate its impact on electron-phonon coupling interactions and the superconducting transition temperature(T_(c)).Our approach involves combining molecular hydrogen with the new diamond-like covalent framework,resulting in a hydrogen-encapsulated clathrate,(H_(2))B_(3)C_(3).A notable characteristic of(H_(2))B_(3)C_(3)is the dynamic behavior of the H_(2)molecules,which exhibit nearly free rotations within the B-C cages,resulting in a dynamic structure that remains cubic on average.The static structure of(H_(2))B_(3)C_(3)(a snapshot in its dynamic trajectory)is calculated to be dynamically stable at ambient and low pressures.Topological analysis of the electron density reveals weak van der Waals interactions between molecular hydrogen and the B-C cages,marginally influencing the electronic structure of the material.The electron count and electronic structure calculations indicate that(H_(2))B_(3)C_(3)is a hole conductor,in which H_(2)molecules donate a portion of their valence electron density to the metallic cage framework.Electron-phonon coupling calculation using the Migdal-Eliashberg theory predicts that(H_(2))B_(3)C_(3)possesses a T_(c) of 46 K under ambient pressure.These results indicate potential for additional light-element substitutions within the type-Ⅶclathrate framework and suggest the possibility of molecular hydrogen as a new approach to optimizing the electronic structures of this new class of superconducting materials.展开更多
Plant growth is controlled by integration of hormonal and light-signaling pathways. BZS1 is a B-box zinc finger protein previously characterized as a negative regulator in the brassinosteroid （BR）-signaling pathway ...Plant growth is controlled by integration of hormonal and light-signaling pathways. BZS1 is a B-box zinc finger protein previously characterized as a negative regulator in the brassinosteroid （BR）-signaling pathway and a positive regulator in the light-signaling pathway. However, the mechanisms by which BZS1/BBX20 integrates light and hormonal pathways are not fully understood. Here, using a quantitative proteomic workflow, we identified several BZSl-associated proteins, including light-signaling compo- nents COP1 and HY5. Direct interactions of BZS1 with COPI and HY5 were verified by yeast two-hybrid and co-immunoprecipitation assays. Overexpression of BZS1 causes a dwarf phenotype that is sup- pressed by the by5 mutation, while overexpression of BZSI fused with the SRDX transcription repressor domain （BZS1-SRDX） causes a long-hypocotyl phenotype similar to by5, indicating that BZSI＇s function requires HY5. BZSI positively regulates HY5 expression, whereas HY5 negatively regulates BZS1 protein level, forming a feedback loop that potentially contributes to signaling dynamics. In contrast to BR, strigolactone （SL） increases BZS1 level, whereas the SL responses of hypocoryl elongation, chlorophyll and HY5 accumulation are diminished in the BZSI-SRDX seedlings, indicating that BZS1 is involved in these SL responses. These results demonstrate that BZS1 interacts with HY5 and plays a central role in integrating light and multiple hormone signals for photomorphogenesis in Arabidopsis.展开更多
Large and growing data resources on the diversity, distribution, and properties of minerals are ushering in a new era of data-driven discovery in mineralogy. The most comprehensive international mineral database is th...Large and growing data resources on the diversity, distribution, and properties of minerals are ushering in a new era of data-driven discovery in mineralogy. The most comprehensive international mineral database is the IMA database, which includes information on more than 5400 approved mineral species and their properties, and the mindat.org data source, which contains more than 1 million species/locality data on minerals found at more than 300 000 localities. Analysis and visualization of these data with diverse techniques—including chord diagrams, cluster diagrams, Klee diagrams, skyline diagrams, and varied methods of network analysis—are leading to a greater understanding of the co-evolving geosphere and biosphere. New data-driven approaches include mineral evolution, mineral ecology, and mineral network analysis—methods that collectively consider the distribution and diversity of minerals through space and time. These strategies are fostering a deeper understanding of mineral co-occurrences and, for the first time, facilitating predictions of mineral species that occur on Earth but have yet to be discovered and described.展开更多
We performed spectral analyses on the ages of 89 well-dated major geological events of the last 260 Myr from the recent geologic literature. These events include times of marine and non-marine extinctions,major ocean-...We performed spectral analyses on the ages of 89 well-dated major geological events of the last 260 Myr from the recent geologic literature. These events include times of marine and non-marine extinctions,major ocean-anoxic events, continental flood-basalt eruptions, sea-level fluctuations, global pulses of intraplate magmatism, and times of changes in seafloor-spreading rates and plate reorganizations. The aggregate of all 89 events shows ten clusters in the last 260 Myr, spaced at an average interval of ~ 26.9 Myr, and Fourier analysis of the data yields a spectral peak at 27.5 Myr at the ≥96% confidence level. A shorter period of ~ 8.9 Myr may also be significant in modulating the timing of geologic events.Our results suggest that global geologic events are generally correlated, and seem to come in pulses with an underlying ~ 27.5-Myr cycle. These cyclic pulses of tectonics and climate change may be the result of geophysical processes related to the dynamics of plate tectonics and mantle plumes, or might alternatively be paced by astronomical cycles associated with the Earth’s motions in the Solar System and the Galaxy.展开更多
In the first part of this paper,four different Cassegrain optical systems with their correctors are designed and studied for multi-object fiber slit spectroscopic survey.The aperture in 6.5 m and field of view 3°...In the first part of this paper,four different Cassegrain optical systems with their correctors are designed and studied for multi-object fiber slit spectroscopic survey.The aperture in 6.5 m and field of view 3°are taken for these optical systems.Assuming observation wavelength range is 0.365-0.95μm,the maximum zenith distance for observing is 60°,the maximum diameter of these lenses is 1.66 m,the altitude of the telescope site is 2500 m,two correctors are composed of 4-piece lenses and the other two are 5-piece lenses.The results obtained are:f-ratio about 3.7,the image quality for all four systems with EE80D≤0.60″,the linear diameter of the focal surface is about 1.2 m and 11 000 fibers can be set on it.Considering the limit of size of fused silica and optical glass,the maximum diameter for lens is about 1.7 m.Such a 6.5 m telescope is about the largest one if using the above correctors.Considering the multiobject spectroscopic survey is greatly important,we also studied some telescope optical systems having their aperture near or larger than 10 m used for the multi-object fiber spectroscopic survey.Such ideas are introduced in the last section of this paper.展开更多
Spectral analyses of past relative sea-level oscillations as represented by the ages of 57 Phanerozoic(the last 545 Myr)stratigraphic sequence boundaries from the Canadian Arctic show a strong spectral peak at 32 Myr(...Spectral analyses of past relative sea-level oscillations as represented by the ages of 57 Phanerozoic(the last 545 Myr)stratigraphic sequence boundaries from the Canadian Arctic show a strong spectral peak at 32 Myr(>99.9%confidence).These findings concur with previous reports of significant cycles with periods of around 30 Myr in various records of fluctuations of sea level,and in potentially related episodes of tectonism,volcanism,climate,and biotic extinctions.Sequence boundaries commonly coincide with stage boundaries based on biostratigraphy,and are correlated with episodes of extinction and times of flood-basalt volcanism.The connection between tectonics and sea-level variations may come from changes in rates of ocean-floor spreading and subduction,intraplate stresses from plate-reorganizations,and pulsations of hotspot volcanism.These coordinated periodic fluctuations in tectonics,sea level and climate may be modulated by cyclical activity in the Earth’s mantle,although some pacing by astronomical cycles is suspected.展开更多
Heterotopic ossification(HO)is a pathological process resulting in aberrant bone formation and often involves synovial lined tissues.During this process,mesenchymal progenitor cells undergo endochondral ossification.N...Heterotopic ossification(HO)is a pathological process resulting in aberrant bone formation and often involves synovial lined tissues.During this process,mesenchymal progenitor cells undergo endochondral ossification.Nonetheless,the specific cell phenotypes and mechanisms driving this process are not well understood,in part due to the high degree of heterogeneity of the progenitor cells involved.Here,using a combination of lineage tracing and single-cell RNA sequencing(sc RNA-seq),we investigated the extent to which synovial/tendon sheath progenitor cells contribute to heterotopic bone formation.For this purpose,Tppp3(tubulin polymerization-promoting protein family member 3)-inducible reporter mice were used in combination with either Scx(Scleraxis)or Pdgfra(platelet derived growth factor receptor alpha)reporter mice.Both tendon injury-and arthroplasty-induced mouse experimental HO models were utilized.Sc RNA-seq of tendon-associated traumatic HO suggested that Tppp3 is an early progenitor cell marker for either tendon or osteochondral cells.Upon HO induction,Tppp3 reporter^(+)cells expanded in number and partially contributed to cartilage and bone formation in either tendon-or joint-associated HO.In double reporter animals,both Pdgfra^(+)Tppp3^(+)and Pdgfra^(+)Tppp3^(-) progenitor cells gave rise to HO-associated cartilage.Finally,analysis of human samples showed a substantial population of TPPP3^(-) expressing cells overlapping with osteogenic markers in areas of heterotopic bone.Overall,these data demonstrate that synovial/tendon sheath progenitor cells undergo aberrant osteochondral differentiation and contribute to HO after trauma.展开更多
Serving as a host factor for human immunodeficiency virus(HIV)integration,LEDGF/p75 has been under extensive study as a potential target for therapy.However,as a highly conserved protein,its physiological function rem...Serving as a host factor for human immunodeficiency virus(HIV)integration,LEDGF/p75 has been under extensive study as a potential target for therapy.However,as a highly conserved protein,its physiological function remains to be thoroughly elucidated.Here,we characterize the molecular function of dP75,the Drosophila homolog of LEDGF/p75,during oogenesis.dP75 binds to transcriptionally active chromatin with its PWWP domain.The C-terminus integrase-binding domain-containing region of dP75 physically interacts with the histone kinase Jil-1 and stabilizes it in vivo.Together with Jil-1,dP75 prevents the spreading of the heterochromatin mark-H3 K9 me2-onto genes required for oogenesis and piRNA production.Without dP75,ectopical silencing of these genes disrupts oogenesis,activates transposons,and causes animal sterility.We propose that dP75,the homolog of an HIV host factor in Drosophila,partners with and stabilizes Jil-1 to ensure gene expression during oogenesis by preventing ectopic heterochromatin spreading.展开更多
1.Objective The Sepon Au-Cu deposit(Fig.1)is the largest polymetal deposit ever discovered in Laos,of which the resources of gold and copper is 102 t(Au:1.6 g/t)and 1.96×10^6 t(TCu:2%)(Zhu HP et al.,2013)respecti...1.Objective The Sepon Au-Cu deposit(Fig.1)is the largest polymetal deposit ever discovered in Laos,of which the resources of gold and copper is 102 t(Au:1.6 g/t)and 1.96×10^6 t(TCu:2%)(Zhu HP et al.,2013)respectively.Sepon Au-Cu deposit is one of the most important super large deposits of the Truong Son Fold Belt.The Truong Son Fold Belt,located at the northeastern margin of the Indo-China terrane,is considered to be tectonically linked to the subduction of the Paleotethys Ocean and subsequent collision.The granodiorite porphyry samples from the Sepon deposit belong to I-type calc-alkaline series and tectonic settings are continental arc environment(Cromie PW,2010).LA-ICP MS zircon U-Pb dating results show that granodiorite porphyry samples from the Sepon deposit have ages of 302.1±2.9 Ma.The in situ zirconεHf(t)values range from+4.32 to+9.64,and TDM2(Hf)has an average age of 914 Ma(Wang XY et al.,2018).In this study,the authors present new in situ zircon oxygen isotopic data to identify the source of the magma.展开更多
The key to answering many compelling and complex questions in Earth,planetary,and life science lies in breaking down the barriers between scientific fields and harnessing the integrated,multi-disciplinary power of Ear...The key to answering many compelling and complex questions in Earth,planetary,and life science lies in breaking down the barriers between scientific fields and harnessing the integrated,multi-disciplinary power of Earth,planetary,and bioscience data resources.We have a unique opportunity to integrate large and rapidly expanding"big data"resources,to enlist powerful analytical and visualization methods,and to answer multi-disciplinary questions that cannot be addressed by one field alone.展开更多
The six largest known impact craters of the last 250 Myr(≥70 km in diameter),which are capable of causing significant environmental damage,coincide with four times of recognized extinction events at 36(with 2 craters...The six largest known impact craters of the last 250 Myr(≥70 km in diameter),which are capable of causing significant environmental damage,coincide with four times of recognized extinction events at 36(with 2 craters),66,and 145 Myr ago,and possibly with two provisional extinction events at 168 and215 Myr ago.These impact cratering events are accompanied by layers in the geologic record interpreted as impact ejecta.Chance occurrences of impacts and extinctions can be rejected at confidence levels of99.96%(for 4 impact/extinctions)to 99.99%(for 6 impact/extinctions).These results argue that several extinction events over the last 250 Myr may be related to the effects of large-body impacts.展开更多
1. Overview The Deep Carbon Observatory (DCO) is a ten-year research program to investigate the quantities, movements, forms, and origins of carbon in Earth. More than 90% of Earth’s carbon may reside in the planet’...1. Overview The Deep Carbon Observatory (DCO) is a ten-year research program to investigate the quantities, movements, forms, and origins of carbon in Earth. More than 90% of Earth’s carbon may reside in the planet’s deep interior, and DCO’s overarching mission is to understand Earth’s entire carbon cycle—beyond the atmosphere, oceans, and shallow crustal environments, which have drawn most previous research attention—to include the deep carbon cycle [1,2]. A decade of focused research has led to major discoveries by DCO scientists on the physical, chemical, and biological roles of carbon in Earth.展开更多
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 n...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 10^(2)–10^(5) 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^(47−49) erg s^(−1) showed 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 3×10^(49) erg s^(−1) to around 1044 erg s^(−1) within 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.展开更多
Radially arranged cortical microtubules are a prominent feature of guard cells. Guard cells expressing GFP- tubulin showed consistent changes in the appearance of microtubules when stomata opened or closed. Guard cell...Radially arranged cortical microtubules are a prominent feature of guard cells. Guard cells expressing GFP- tubulin showed consistent changes in the appearance of microtubules when stomata opened or closed. Guard cells showed fewer microtubule structures as stomata closed, whether induced by transfer to darkness, ABA, hydrogen per- oxide, or sodium hydrogen carbonate. Guard cells kept in the dark （closed stomata） showed increases in microtubule struc- tures and stomatal aperture on light treatment. GFP-EB1, marking microtubule growing plus ends, showed no change in number of plus ends or velocity of assembly on stomatal closure. Since the number of growing plus ends and the rate of plus-end growth did not change when microtubule structure numbers declined, microtubule instability and/or rearrange- ment must be responsible for the apparent loss of microtubules. Guard cells with closed stomata showed more cytosolic GFP-fluorescence than those with open stomata as cortical microtubules became disassembled, although with a large net loss in total fluorescence. Microtubule-targeted drugs blocked guard-cell function in Vicia and Arabidopsis. Oryzalin dis- rupted guard-cell microtubules and prevented stomatal opening and taxol stabilized guard-cell microtubules and delayed stomatal closure. Gas exchange measurements indicated that the transgenes for fluorescent-labeled proteins did not dis- rupt normal stomatal function. These dynamic changes in guard-cell microtubules combined with our inhibitor studies provide evidence for an active role of microtubules in guard-cell function.展开更多
Cold-induced changes of gene expression and metabolism are critical for plants to survive freezing. Largely by changing gene expression, exposure to a period of non-freezing low temperatures increases plant tolerance ...Cold-induced changes of gene expression and metabolism are critical for plants to survive freezing. Largely by changing gene expression, exposure to a period of non-freezing low temperatures increases plant tolerance to freezing--a phenomenon known as cold acclimation. Cold also induces rapid metabolic changes, which provide instant protection before temperature drops below freezing point. The molecular mechanisms for such rapid metabolic responses to cold remain largely unknown. Here, we use two-dimensional difference gel electrophoresis （2-D DIGE） analysis of sub-cellular fractions ofArabidopsis thaliana proteome coupled with spot identification by tandem mass spectrometry to identify early cold-responsive proteins in Arabidopsis. These proteins include four enzymes involved in starch degradation, three HSP100 proteins, several proteins in the tricarboxylic acid cycle, and sucrose metabolism. Upon cold treatment, the Disproportio- nating Enzyme 2 （DPE2）, a cytosolic transglucosidase metabolizing maltose to glucose, increased rapidly in the centrifugation pellet fraction and decreased in the soluble fraction. Consistent with cold-induced inactivation of DPE2 enzymatic activity, the dpe2 mutant showed increased freezing tolerance without affecting the C-repeat binding transcription factor （CBF） transcriptional pathway. These results support a model that cold-induced inactivation of DPE2 leads to rapid accumulation of maltose, which is a cold-induced compatible solute that protects cells from freezing damage. This study provides evidence for a key role of rapid post-translational regulation of carbohydrate metabolic enzymes in plant protection against sudden temperature drop.展开更多
To understand and engineer plant metabolism, we need a comprehensive and accurate annotation of all metabolic information across plant species. As a step towards this goal, we generated genome-scale metabolic pathway ...To understand and engineer plant metabolism, we need a comprehensive and accurate annotation of all metabolic information across plant species. As a step towards this goal, we generated genome-scale metabolic pathway databases of 126 algal and plant genomes, ranging from model organisms to crops to medicinal plants(https://plantcyc.org).Of these, 104 have not been reported before.We systematically evaluated the quality of the databases, which revealed that our semi-automated validation pipeline dramatically improves the quality. We then compared the metabolic content across the 126 organisms using multiple correspondence analysis and found that Brassicaceae,Poaceae, and Chlorophyta appeared as metabolically distinct groups. To demonstrate the utility of this resource, we used recently published sorghum transcriptomics data to discover previously unreported trends of metabolism underlying drought tolerance. We also used single-cell transcriptomics data from the Arabidopsis root to infer cell typespecific metabolic pathways. This work shows the quality and quantity of our resource and demonstrates its wide-ranging utility in integrating metabolism with other areas of plant biology.展开更多
基金supported byRussian Science Foundation,project No 17-17-01177.AGsupport of the Deep Carbon Observatory through the Alfred P.Sloan Foundation
文摘The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe^0 system at 70-150 GPa and 800-2600 Kin a laser-heated diamond anvil cell.Using in situ synchrotro n X-ray diffraction and ex situ transmission electron microscopy we show that the reduction of Mg-carbonate can be exemplified by:6 MgCO3+19 Fe=8 FeO+10(Mg0.6Fe^0.4)O+Fe7 C3+3 C.The presented results suggest that the interaction of carbonates with Fe^0 or Fe^0-bearing rocks can produce Fe-carbide and diamond,which can accumulate in the D"region,depending on its carbon to Fe ratio.Due to the sluggish kinetics of the transformation,diamond can remain metastable at the core-mantle boundary(CMB)unless it is in a direct contact with Fe-metal.In addition,it can be remobilized by redox melting accompanying the generation of mantle plumes.
基金Alfred P. Sloan Foundation (G-2016-7065) to the DCO Secretariatthe National Natural Science Foundation of China (U1530402) to HPSTAR.
文摘Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majority of these volatiles are hidden in the deep interior, where the high pressure–temperature conditions drastically and categorically alter the physics and chemistry of the volatiles. Like the bloodstream of an organism, the circulations and interactions of volatiles in the deep Earth modulate climate, resources, energy, natural hazards, and other factors that define the Earth as a unique living and changing planet.
基金supported financially by the National Key R&D Program of China(Grant No.2022YFB3706602)the National Natural Science Foundation of China(Grant Nos.42272041,41902034,and 12011530063)the Jilin University High-Level Innovation Team Foundation,China(Grant No.2021TD-05).
文摘Ultrahigh-temperature-pressure experiments are crucial for understanding the physical and chemical properties of matter.The recent development of boron-doped diamond(BDD)heaters has made such melting experiments possible in large-volume presses.However,estimates of temperatures above 2600 K and of the temperature distributions inside BDD heaters are not well constrained,owing to the lack of a suitable thermometer.Here,we establish a three-dimensional finite element model as a virtual thermometer to estimate the temperature and temperature field above 2600 K.The advantage of this virtual thermometer over those proposed in previous studies is that it considers both alternating and direct current heating modes,the actual sizes of cell assemblies after compression,the effects of the electrode,thermocouple and anvil,and the heat dissipation by the pressure-transmitting medium.The virtual thermometer reproduces the power-temperature relationships of ultrahigh-temperature-pressure experiments below 2600 K at press loads of 2.8-7.9 MN(~19 to 28 GPa)within experimental uncertainties.The temperatures above 2600 K predicted by our virtual thermometer are within the uncertainty of those extrapolated from power-temperature relationships below 2600 K.Furthermore,our model shows that the temperature distribution inside a BDD heater(19-26 K/mm along the radial direction and<83 K/mm along the longitudinal direction)is more homogeneous than those inside conventional heaters such as graphite or LaCrO_(3) heaters(100-200 K/mm).Our study thus provides a reliable virtual thermometer for ultrahigh-temperature experiments using BDD heaters in Earth and material sciences.
基金supported by Carnegie Canada and Natural Sciences and Engineering Research Council of Canada(NSERC)support from the U.S.Department of Energy(DOE),Office of Science,Basic Energy Sciences,under Award No.DESC0020683。
文摘The recent discovery of type-Ⅶboron-carbon clathrates with calculated superconducting transition temperatures approaching~100 K has sparked interest in exploring new conventional superconductors that may be stabilized at ambient pressure.The electronic structure of the clathrate is highly tunable based on the ability to substitute different metal atoms within the cages,which may also be large enough to host small molecules.Here we introduce molecular hydrogen(H_(2))within the clathrate cages and investigate its impact on electron-phonon coupling interactions and the superconducting transition temperature(T_(c)).Our approach involves combining molecular hydrogen with the new diamond-like covalent framework,resulting in a hydrogen-encapsulated clathrate,(H_(2))B_(3)C_(3).A notable characteristic of(H_(2))B_(3)C_(3)is the dynamic behavior of the H_(2)molecules,which exhibit nearly free rotations within the B-C cages,resulting in a dynamic structure that remains cubic on average.The static structure of(H_(2))B_(3)C_(3)(a snapshot in its dynamic trajectory)is calculated to be dynamically stable at ambient and low pressures.Topological analysis of the electron density reveals weak van der Waals interactions between molecular hydrogen and the B-C cages,marginally influencing the electronic structure of the material.The electron count and electronic structure calculations indicate that(H_(2))B_(3)C_(3)is a hole conductor,in which H_(2)molecules donate a portion of their valence electron density to the metallic cage framework.Electron-phonon coupling calculation using the Migdal-Eliashberg theory predicts that(H_(2))B_(3)C_(3)possesses a T_(c) of 46 K under ambient pressure.These results indicate potential for additional light-element substitutions within the type-Ⅶclathrate framework and suggest the possibility of molecular hydrogen as a new approach to optimizing the electronic structures of this new class of superconducting materials.
基金supported by a grant from National Institute of Health (NIH, R01GM066258)“One-hundred Talents Project” of Hebei province, China (E2013100004)supported by the China Scholarship Council
文摘Plant growth is controlled by integration of hormonal and light-signaling pathways. BZS1 is a B-box zinc finger protein previously characterized as a negative regulator in the brassinosteroid （BR）-signaling pathway and a positive regulator in the light-signaling pathway. However, the mechanisms by which BZS1/BBX20 integrates light and hormonal pathways are not fully understood. Here, using a quantitative proteomic workflow, we identified several BZSl-associated proteins, including light-signaling compo- nents COP1 and HY5. Direct interactions of BZS1 with COPI and HY5 were verified by yeast two-hybrid and co-immunoprecipitation assays. Overexpression of BZS1 causes a dwarf phenotype that is sup- pressed by the by5 mutation, while overexpression of BZSI fused with the SRDX transcription repressor domain （BZS1-SRDX） causes a long-hypocotyl phenotype similar to by5, indicating that BZSI＇s function requires HY5. BZSI positively regulates HY5 expression, whereas HY5 negatively regulates BZS1 protein level, forming a feedback loop that potentially contributes to signaling dynamics. In contrast to BR, strigolactone （SL） increases BZS1 level, whereas the SL responses of hypocoryl elongation, chlorophyll and HY5 accumulation are diminished in the BZSI-SRDX seedlings, indicating that BZS1 is involved in these SL responses. These results demonstrate that BZS1 interacts with HY5 and plays a central role in integrating light and multiple hormone signals for photomorphogenesis in Arabidopsis.
基金grants from the Alfred P. Sloan Foundation (G-2016-7065)the W. M. Keck Foundation (grant entitled ‘‘Co-Evolution of the Geosphere and Biosphere”), the John Templeton Foundation (60645)the NASA Astrobiology Institute (1-NAI8_2-0007), a private foundation, and the Carnegie Institution for Science. Sergey V. Krivovichev acknowledges support from the Russian Science Foundation (19-17-00038).
文摘Large and growing data resources on the diversity, distribution, and properties of minerals are ushering in a new era of data-driven discovery in mineralogy. The most comprehensive international mineral database is the IMA database, which includes information on more than 5400 approved mineral species and their properties, and the mindat.org data source, which contains more than 1 million species/locality data on minerals found at more than 300 000 localities. Analysis and visualization of these data with diverse techniques—including chord diagrams, cluster diagrams, Klee diagrams, skyline diagrams, and varied methods of network analysis—are leading to a greater understanding of the co-evolving geosphere and biosphere. New data-driven approaches include mineral evolution, mineral ecology, and mineral network analysis—methods that collectively consider the distribution and diversity of minerals through space and time. These strategies are fostering a deeper understanding of mineral co-occurrences and, for the first time, facilitating predictions of mineral species that occur on Earth but have yet to be discovered and described.
基金Research was partly funded by an NYU Research Challenge Fund Grant。
文摘We performed spectral analyses on the ages of 89 well-dated major geological events of the last 260 Myr from the recent geologic literature. These events include times of marine and non-marine extinctions,major ocean-anoxic events, continental flood-basalt eruptions, sea-level fluctuations, global pulses of intraplate magmatism, and times of changes in seafloor-spreading rates and plate reorganizations. The aggregate of all 89 events shows ten clusters in the last 260 Myr, spaced at an average interval of ~ 26.9 Myr, and Fourier analysis of the data yields a spectral peak at 27.5 Myr at the ≥96% confidence level. A shorter period of ~ 8.9 Myr may also be significant in modulating the timing of geologic events.Our results suggest that global geologic events are generally correlated, and seem to come in pulses with an underlying ~ 27.5-Myr cycle. These cyclic pulses of tectonics and climate change may be the result of geophysical processes related to the dynamics of plate tectonics and mantle plumes, or might alternatively be paced by astronomical cycles associated with the Earth’s motions in the Solar System and the Galaxy.
文摘In the first part of this paper,four different Cassegrain optical systems with their correctors are designed and studied for multi-object fiber slit spectroscopic survey.The aperture in 6.5 m and field of view 3°are taken for these optical systems.Assuming observation wavelength range is 0.365-0.95μm,the maximum zenith distance for observing is 60°,the maximum diameter of these lenses is 1.66 m,the altitude of the telescope site is 2500 m,two correctors are composed of 4-piece lenses and the other two are 5-piece lenses.The results obtained are:f-ratio about 3.7,the image quality for all four systems with EE80D≤0.60″,the linear diameter of the focal surface is about 1.2 m and 11 000 fibers can be set on it.Considering the limit of size of fused silica and optical glass,the maximum diameter for lens is about 1.7 m.Such a 6.5 m telescope is about the largest one if using the above correctors.Considering the multiobject spectroscopic survey is greatly important,we also studied some telescope optical systems having their aperture near or larger than 10 m used for the multi-object fiber spectroscopic survey.Such ideas are introduced in the last section of this paper.
基金partially funded by an NYU Research Challenge Grant。
文摘Spectral analyses of past relative sea-level oscillations as represented by the ages of 57 Phanerozoic(the last 545 Myr)stratigraphic sequence boundaries from the Canadian Arctic show a strong spectral peak at 32 Myr(>99.9%confidence).These findings concur with previous reports of significant cycles with periods of around 30 Myr in various records of fluctuations of sea level,and in potentially related episodes of tectonism,volcanism,climate,and biotic extinctions.Sequence boundaries commonly coincide with stage boundaries based on biostratigraphy,and are correlated with episodes of extinction and times of flood-basalt volcanism.The connection between tectonics and sea-level variations may come from changes in rates of ocean-floor spreading and subduction,intraplate stresses from plate-reorganizations,and pulsations of hotspot volcanism.These coordinated periodic fluctuations in tectonics,sea level and climate may be modulated by cyclical activity in the Earth’s mantle,although some pacing by astronomical cycles is suspected.
基金funded by the NIH/NIAMS (R01 AR070773,R01 AR068316,R01 DE031028,R21 AR078919)USAMRAA through the Peer Reviewed Medical Research Program (W81XWH-18-1-0121,W81XWH-18-1-0336)+4 种基金the Peer Reviewed Orthopaedic Research Program (W81XWH-20-10795)Broad Agency Announcement (W81XWH-1810613)the American Cancer Society (Research Scholar Grant,RSG-18-027-01-CSM)the Maryland Stem Cell Research Foundationfunded by the NIH (R01 AR079171,R01 AR078324,and R01 AR071379)。
文摘Heterotopic ossification(HO)is a pathological process resulting in aberrant bone formation and often involves synovial lined tissues.During this process,mesenchymal progenitor cells undergo endochondral ossification.Nonetheless,the specific cell phenotypes and mechanisms driving this process are not well understood,in part due to the high degree of heterogeneity of the progenitor cells involved.Here,using a combination of lineage tracing and single-cell RNA sequencing(sc RNA-seq),we investigated the extent to which synovial/tendon sheath progenitor cells contribute to heterotopic bone formation.For this purpose,Tppp3(tubulin polymerization-promoting protein family member 3)-inducible reporter mice were used in combination with either Scx(Scleraxis)or Pdgfra(platelet derived growth factor receptor alpha)reporter mice.Both tendon injury-and arthroplasty-induced mouse experimental HO models were utilized.Sc RNA-seq of tendon-associated traumatic HO suggested that Tppp3 is an early progenitor cell marker for either tendon or osteochondral cells.Upon HO induction,Tppp3 reporter^(+)cells expanded in number and partially contributed to cartilage and bone formation in either tendon-or joint-associated HO.In double reporter animals,both Pdgfra^(+)Tppp3^(+)and Pdgfra^(+)Tppp3^(-) progenitor cells gave rise to HO-associated cartilage.Finally,analysis of human samples showed a substantial population of TPPP3^(-) expressing cells overlapping with osteogenic markers in areas of heterotopic bone.Overall,these data demonstrate that synovial/tendon sheath progenitor cells undergo aberrant osteochondral differentiation and contribute to HO after trauma.
基金supported by the grant from the NIH to Z.Z.(DP5OD021355)the National Natural Science Foundation of China(91940302 and 31870741 to Y.H.)。
文摘Serving as a host factor for human immunodeficiency virus(HIV)integration,LEDGF/p75 has been under extensive study as a potential target for therapy.However,as a highly conserved protein,its physiological function remains to be thoroughly elucidated.Here,we characterize the molecular function of dP75,the Drosophila homolog of LEDGF/p75,during oogenesis.dP75 binds to transcriptionally active chromatin with its PWWP domain.The C-terminus integrase-binding domain-containing region of dP75 physically interacts with the histone kinase Jil-1 and stabilizes it in vivo.Together with Jil-1,dP75 prevents the spreading of the heterochromatin mark-H3 K9 me2-onto genes required for oogenesis and piRNA production.Without dP75,ectopical silencing of these genes disrupts oogenesis,activates transposons,and causes animal sterility.We propose that dP75,the homolog of an HIV host factor in Drosophila,partners with and stabilizes Jil-1 to ensure gene expression during oogenesis by preventing ectopic heterochromatin spreading.
基金This work was supported by the National Science Foundation of China(41373036,41002027)the geological survey project of China Geological Survey(DD20190437).
文摘1.Objective The Sepon Au-Cu deposit(Fig.1)is the largest polymetal deposit ever discovered in Laos,of which the resources of gold and copper is 102 t(Au:1.6 g/t)and 1.96×10^6 t(TCu:2%)(Zhu HP et al.,2013)respectively.Sepon Au-Cu deposit is one of the most important super large deposits of the Truong Son Fold Belt.The Truong Son Fold Belt,located at the northeastern margin of the Indo-China terrane,is considered to be tectonically linked to the subduction of the Paleotethys Ocean and subsequent collision.The granodiorite porphyry samples from the Sepon deposit belong to I-type calc-alkaline series and tectonic settings are continental arc environment(Cromie PW,2010).LA-ICP MS zircon U-Pb dating results show that granodiorite porphyry samples from the Sepon deposit have ages of 302.1±2.9 Ma.The in situ zirconεHf(t)values range from+4.32 to+9.64,and TDM2(Hf)has an average age of 914 Ma(Wang XY et al.,2018).In this study,the authors present new in situ zircon oxygen isotopic data to identify the source of the magma.
基金supported by the W.M.Keck Foundation’s Deep-Time Data Infrastructure projectsupport by the Deep Carbon Observatory+1 种基金the Alfred P.Sloan Foundationa private foundation,and the Carnegie Institution for Science.
文摘The key to answering many compelling and complex questions in Earth,planetary,and life science lies in breaking down the barriers between scientific fields and harnessing the integrated,multi-disciplinary power of Earth,planetary,and bioscience data resources.We have a unique opportunity to integrate large and rapidly expanding"big data"resources,to enlist powerful analytical and visualization methods,and to answer multi-disciplinary questions that cannot be addressed by one field alone.
基金Support for Rampino came from an NYU Research Challenge grant
文摘The six largest known impact craters of the last 250 Myr(≥70 km in diameter),which are capable of causing significant environmental damage,coincide with four times of recognized extinction events at 36(with 2 craters),66,and 145 Myr ago,and possibly with two provisional extinction events at 168 and215 Myr ago.These impact cratering events are accompanied by layers in the geologic record interpreted as impact ejecta.Chance occurrences of impacts and extinctions can be rejected at confidence levels of99.96%(for 4 impact/extinctions)to 99.99%(for 6 impact/extinctions).These results argue that several extinction events over the last 250 Myr may be related to the effects of large-body impacts.
文摘1. Overview The Deep Carbon Observatory (DCO) is a ten-year research program to investigate the quantities, movements, forms, and origins of carbon in Earth. More than 90% of Earth’s carbon may reside in the planet’s deep interior, and DCO’s overarching mission is to understand Earth’s entire carbon cycle—beyond the atmosphere, oceans, and shallow crustal environments, which have drawn most previous research attention—to include the deep carbon cycle [1,2]. A decade of focused research has led to major discoveries by DCO scientists on the physical, chemical, and biological roles of carbon in Earth.
文摘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 10^(2)–10^(5) 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^(47−49) erg s^(−1) showed 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 3×10^(49) erg s^(−1) to around 1044 erg s^(−1) within 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.
文摘Radially arranged cortical microtubules are a prominent feature of guard cells. Guard cells expressing GFP- tubulin showed consistent changes in the appearance of microtubules when stomata opened or closed. Guard cells showed fewer microtubule structures as stomata closed, whether induced by transfer to darkness, ABA, hydrogen per- oxide, or sodium hydrogen carbonate. Guard cells kept in the dark （closed stomata） showed increases in microtubule struc- tures and stomatal aperture on light treatment. GFP-EB1, marking microtubule growing plus ends, showed no change in number of plus ends or velocity of assembly on stomatal closure. Since the number of growing plus ends and the rate of plus-end growth did not change when microtubule structure numbers declined, microtubule instability and/or rearrange- ment must be responsible for the apparent loss of microtubules. Guard cells with closed stomata showed more cytosolic GFP-fluorescence than those with open stomata as cortical microtubules became disassembled, although with a large net loss in total fluorescence. Microtubule-targeted drugs blocked guard-cell function in Vicia and Arabidopsis. Oryzalin dis- rupted guard-cell microtubules and prevented stomatal opening and taxol stabilized guard-cell microtubules and delayed stomatal closure. Gas exchange measurements indicated that the transgenes for fluorescent-labeled proteins did not dis- rupt normal stomatal function. These dynamic changes in guard-cell microtubules combined with our inhibitor studies provide evidence for an active role of microtubules in guard-cell function.
文摘Cold-induced changes of gene expression and metabolism are critical for plants to survive freezing. Largely by changing gene expression, exposure to a period of non-freezing low temperatures increases plant tolerance to freezing--a phenomenon known as cold acclimation. Cold also induces rapid metabolic changes, which provide instant protection before temperature drops below freezing point. The molecular mechanisms for such rapid metabolic responses to cold remain largely unknown. Here, we use two-dimensional difference gel electrophoresis （2-D DIGE） analysis of sub-cellular fractions ofArabidopsis thaliana proteome coupled with spot identification by tandem mass spectrometry to identify early cold-responsive proteins in Arabidopsis. These proteins include four enzymes involved in starch degradation, three HSP100 proteins, several proteins in the tricarboxylic acid cycle, and sucrose metabolism. Upon cold treatment, the Disproportio- nating Enzyme 2 （DPE2）, a cytosolic transglucosidase metabolizing maltose to glucose, increased rapidly in the centrifugation pellet fraction and decreased in the soluble fraction. Consistent with cold-induced inactivation of DPE2 enzymatic activity, the dpe2 mutant showed increased freezing tolerance without affecting the C-repeat binding transcription factor （CBF） transcriptional pathway. These results support a model that cold-induced inactivation of DPE2 leads to rapid accumulation of maltose, which is a cold-induced compatible solute that protects cells from freezing damage. This study provides evidence for a key role of rapid post-translational regulation of carbohydrate metabolic enzymes in plant protection against sudden temperature drop.
基金This work was supported by grants from the National Science Foundation(IOS-1546838,IOS-1026003)the US Department of Energy,Office of Science,Office of Biological and Environmental Research,Genomic Science Program grant nos.DE-SC0018277,DE-SC0008769,DE-SC0020366,and DE-SC0021286.
文摘To understand and engineer plant metabolism, we need a comprehensive and accurate annotation of all metabolic information across plant species. As a step towards this goal, we generated genome-scale metabolic pathway databases of 126 algal and plant genomes, ranging from model organisms to crops to medicinal plants(https://plantcyc.org).Of these, 104 have not been reported before.We systematically evaluated the quality of the databases, which revealed that our semi-automated validation pipeline dramatically improves the quality. We then compared the metabolic content across the 126 organisms using multiple correspondence analysis and found that Brassicaceae,Poaceae, and Chlorophyta appeared as metabolically distinct groups. To demonstrate the utility of this resource, we used recently published sorghum transcriptomics data to discover previously unreported trends of metabolism underlying drought tolerance. We also used single-cell transcriptomics data from the Arabidopsis root to infer cell typespecific metabolic pathways. This work shows the quality and quantity of our resource and demonstrates its wide-ranging utility in integrating metabolism with other areas of plant biology.
