To reveal the influence of coupled effects of dry-wet cycling and precompression stress(CEDWCPS)on the damage evolution of limestone with horizontal fissure(LHF),a series of degradation and uniaxial compression tests ...To reveal the influence of coupled effects of dry-wet cycling and precompression stress(CEDWCPS)on the damage evolution of limestone with horizontal fissure(LHF),a series of degradation and uniaxial compression tests were conducted,and a corresponding piecewise damage constitutive model(PDCM)was established.We found that both dry-wet cycling and precompression stress deteriorate the physical properties,alter the microscopic characteristics,and reduce the mechanical properties of the LHF.These degradations are particularly pronounced under the CEDWCPS,although the magnitude of these changes gradually diminishes with the progression of dry-wet cycling.Meanwhile,they also reduce the deformation degree,prolong the micropore compaction stage,shorten the unstable crack propagation stage,lower the frequency and intensity of AE events,decrease the high-amplitude and high-frequency AE signals,enlarge crack scales,and shorten the crack initiation time.Among the changes of these indicators,the dry-wet cycling plays a dominant role.The crack types of LHF under the CEDWCPS(LHFCEDWCPS)are predominantly tensile cracks,supplemented by shear cracks.The failure mode can be defined as tensileshear composite failure.Finally,the established PDCM effectively captures the nonlinear deformation of micropore and the linear deformation of the matrix in LHFCEDWCPS,with all corresponding R^(2) consistently exceeding 0.97.展开更多
The construction of lunar bases represents a crucial goal for long-term human residence on the Moon and future deep-space exploration. Vacuum sintering of lunar regolith for in-situ resource utilization(ISRU) is consi...The construction of lunar bases represents a crucial goal for long-term human residence on the Moon and future deep-space exploration. Vacuum sintering of lunar regolith for in-situ resource utilization(ISRU) is considered one of the most feasible strategies for early lunar infrastructure development. However, the extreme temperature fluctuations on the lunar surface pose potential threats to the structural stability of sintered regolith materials. To investigate the mechanical deterioration and damage mechanism of vacuum-sintered lunar regolith under extreme cryogenic-thermal cycling, lunar regolith simulants are used to fabricate specimens through vacuum sintering. A series of cryogenic-thermal cycling tests is designed, combined with uniaxial compression and X-ray CT scanning, to systematically analyze their macro-micro responses. The results show that with increasing extreme cryogenic-thermal cycles, the stress-strain curves evolve from typical brittle failure to quasiductile behavior, with uniaxial compressive strength and elastic modulus decreasing by approximately 33.86% and 61.98%, respectively. CT analyses reveal that the pore structure transforms from isolated pores to connected networks, with the pore volume fraction increasing from 13.33% to 22.64%, and the fractal dimension increases from 2.465 to 2.544, and stabilizes after multiple cycles. A significant negative correlation(R^(2)> 0.96) exists between pore structural complexity and mechanical performance. Based on these findings, a thermal fatigue damage mechanism dominated by thermal stress concentration due to mismatched thermal expansion coefficients among mineral phases is proposed. This study provides scientific insights for the design, durability evaluation, and ISRU-based construction of lunar surface infrastructure.展开更多
The rapid cycling synchrotron(RCS)at the China spallation neutron source operates as a high-intensity proton accelerator.The coupled bunch instability was observed during RCS beam commissioning,which significantly lim...The rapid cycling synchrotron(RCS)at the China spallation neutron source operates as a high-intensity proton accelerator.The coupled bunch instability was observed during RCS beam commissioning,which significantly limited the beam power.To investigate the dynamics of instability under an increased beam power,a pulsed octupole magnet with a gradient of 900 T/m^(3) was developed.The magnet system integrated an octupole magnet with a pulsed power supply.The field was carefully measured to examine the performance before its installation into the tunnel.After the installation of the magnets,beam measurements were performed to confirm the effectiveness of the instability mitigation on an actual proton beam.The measurement results show that the instability can be suppressed using the pulsed octupole magnet,particularly at the highenergy stage in an acceleration cycle,meeting the requirements for stable operation of the accelerator.Additionally,when the instability is completely suppressed through chromaticity optimization,octupole magnets can significantly enhance the RCS transmission efficiency,which is crucial for controlling beam loss.The pulsed octupole magnet offers significant progress in beam stability in the RCS,providing valuable experience for further beam power enhancement.展开更多
The efficient recycling of poly(ethylene terephthalate)and poly(butylene terephthalate),the most extensively produced plastics,is essential for reducing global carbon emissions and the current dependence on fossil res...The efficient recycling of poly(ethylene terephthalate)and poly(butylene terephthalate),the most extensively produced plastics,is essential for reducing global carbon emissions and the current dependence on fossil resources.However,the chemical recycling of polyesters primarily involves polymer-to-monomer and monomer-to-polymer processes,resulting in significant greenhouse gas emissions owing to significant electricity and fuel consumption.Herein,this research reports a simple and efficient one-pot polymer-to-polymer upcycling process that directly converts these two polyester wastes into biodegradable thermoplastic poly(ether ester)s using poly(tetramethylene ether)glycol(PTMG).The synthesized series of poly((ET-co-BT)-mb-PTMG)(PEBTG)exhibit a maximum tensile strength of 68 MPa,with 85%weight loss after 20 weeks in composted soil.Techno-economic analysis and life cycle assessment indicate that PEBTG is more cost-competitive and environmentally beneficial than currently existing plastics derived from fossil fuels,such as polypropylene and polybutylene adipate terephthalate.Once de-risked,the proposed upcycling strategy for polymer waste can be extended to expedite the development of a sustainable plastic economy.展开更多
The properties of electrolytes are critical for fast-charging and stable-cycling applications in lithium metal batteries(LMBs).However,the slow kinetics of Li^(+)transport and desolvation in commercial carbonate elect...The properties of electrolytes are critical for fast-charging and stable-cycling applications in lithium metal batteries(LMBs).However,the slow kinetics of Li^(+)transport and desolvation in commercial carbonate electrolytes,cou pled with the formation of unstable solid electrolyte interphases(SEI),exacerbate the degradation of LMB performance at high current densities.Herein,we propose a versatile electrolyte design strategy that incorporates cyclohexyl methyl ether(CME)as a co-solvent to reshape the Li^(+)solvation environment by the steric-hindrance effect of bulky molecules and their competitive coordination with other solvent molecules.Simulation calculations and spectral analysis demonstrate that the addition of CME molecules reduces the involvement of other solvent molecules in the Li solvation sheath and promotes the formation of Li^(+)-PF_(6)^(-)coordination,thereby accelerating Li^(+)transport kinetics.Additionally,this electrolyte composition improves Li^(+)desolvation kinetics and fosters the formation of inorganic-rich SEI,ensuring cycle stability under fast charging.Consequently,the Li‖LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)battery with the modified electrolyte retains 82% of its initial capacity after 463 cycles at 1 C.Even under the extreme fast-charging condition of 5 C,the battery can maintain 80% capacity retention after 173 cycles.This work provides a promising approach for the development of highperformance LMBs by modulating solvation environment of electrolytes.展开更多
1 A few decades ago,it was common to see groups of chil-dren riding bikes down quiet American streets.However,this scene is less likely to be seen today.In the 1990s,an average of 20.5 million children aged 7 to 17 ro...1 A few decades ago,it was common to see groups of chil-dren riding bikes down quiet American streets.However,this scene is less likely to be seen today.In the 1990s,an average of 20.5 million children aged 7 to 17 rode bikes six or more times a year,according to the National Sporting Goods Association.By 2023,this number had dropped to about 10.9 million,with less than 5%of them riding frequently.展开更多
MgH_(2) has been extensively studied as one of the most ideal solid hydrogen storage materials.Nevertheless,rapid capacity decay and sluggish hydrogen storage kinetics hamper its practical application.Herein,a Ni/C na...MgH_(2) has been extensively studied as one of the most ideal solid hydrogen storage materials.Nevertheless,rapid capacity decay and sluggish hydrogen storage kinetics hamper its practical application.Herein,a Ni/C nano-catalyst doped MgH_(2)(MgH_(2)–Ni/C)shows an improved hydrogen absorption kinetics with largely reduced activation energy.Particularly,the MgH_(2)–Ni/C displays remarkable cycling stability,which maintains a high capacity of 6.01 wt.%(98.8%of initial capacity)even after 50 full hydrogen ab/desorption cycles,while the undoped MgH_(2) counterpart retains only 85.2%of its initial capacity.Detailed microstructure characterizations clearly reveal that particle sintering/growth accounts primarily for the deterioration of cycling performance of undoped MgH_(2).By comparison,MgH_(2)–Ni/C can maintain a stable particle size with a growing porous structure during long-term cycling,which effectively increases the specific surface of the particles.A novel carbon-induced-porosity stabilization mechanism is proposed,which can stabilize the proportion of rapid hydrogen absorption process,thus dominating the excellent cycling performance of MgH_(2)–Ni/C.This study provides new insights into the cycling stability mechanism of carbon-containing Mg-based hydrogen storage materials,thus promoting their practical applications.展开更多
Magnesium ion batteries(MIBs)are a promising alternative to lithium-ion batteries,which suffer from the short cycling life and sluggish Mg^(2+)diffusion kinetics of cathodes.Nano morphologies are used to shorten Mg^(2...Magnesium ion batteries(MIBs)are a promising alternative to lithium-ion batteries,which suffer from the short cycling life and sluggish Mg^(2+)diffusion kinetics of cathodes.Nano morphologies are used to shorten Mg^(2+)diffusion path for diffusion kinetics acceleration,but the cycling life is still unsatisfactory.Herein,the anisotropy of layered V_(3)O_(7)·1.9H_(2)O nanobelts is utilized to stabilize their structure during discharging/charging.The V_(3)O_(7)·1.9H_(2)O nanobelts grow along the preponderant migration direction of Mg^(2+),and the resulted axial migration of Mg^(2+)enables the stress caused by Mg^(2+)insertion to be decentralized in large zone,thus improving the cycling stability of V_(3)O_(7)·1.9H_(2)O nanobelts.The inserted Mg^(2+)cations bond with O atoms in adjacent V3O8 layers of V_(3)O_(7)·1.9H_(2)O,further stablizing the layered structure.Meanwhile,the axial migration of Mg^(2+)significantly reduces the charge transfer resistance at electrode/electrolyte interface,which accelerates the Mg^(2+)diffusion kinetics.Thus,the symmetric RMB assembled from V_(3)O_(7)·1.9H_(2)O nanobelts exhibits an ultralong cycling life of 11,000 cycles at 4 A g^(-1),alongside a high specific capacity of 137 mAh g^(-1)at 0.05 A g^(-1).According to our knowledge,this ultralong cycling life surpasses those of reported full RMBs.This strategy provides insight into the design of cathode materials with improved cycling lives.展开更多
Lithium and manganese-rich layered oxides(LMROs)have attracted extensive attention and are promising cathode materials for next-generation lithium ion batteries due to their high capacities and high energy densities.H...Lithium and manganese-rich layered oxides(LMROs)have attracted extensive attention and are promising cathode materials for next-generation lithium ion batteries due to their high capacities and high energy densities.However,LMRO cathode suffers from severe capacity and voltage fading originating from irreversible surface oxygen evolution.Herein,we propose a facile redox couple strategy by introducing nitroxyl radicals species to regulate the surface anionic redox reaction of LMRO cathode.Differential electrochemical mass spectroscopy,X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses demonstrate that during charge process,the peroxide ion O_(2)^(2−)on the surface generated from the oxidation of lattice O^(2-)could be reduced back to stable O^(2-)by redox couple in time,thus avoiding oxygen evolution and structure degradation,as well as enhancing bulk oxygen redox activity.The enhanced LMRO electrode delivers a high capacity of 220.3 mAh g^(−1)at 1 C.An excellent cycling stability with a capacity retention of 94.4%is achieved after 500 cycles,as well as a suppressed voltage decay with only 1.12 mV per cycle.展开更多
Microstructures and properties of mortar using ammonium phosphate and potassium phosphate were tested and compared in this case.Moreover,two cementitious additions and two lightweight aggregates,including fly ash,redi...Microstructures and properties of mortar using ammonium phosphate and potassium phosphate were tested and compared in this case.Moreover,two cementitious additions and two lightweight aggregates,including fly ash,redispersible latex powder,ceramsite sand,and rubber powder,were respectively tried to be applied in magnesium ammonium phosphate cement mortar in order to modify the microstructures and properties.The experimental results show that potassium phosphate is not suitable for magnesium phosphate cement mortar for cold region construction purpose.Although fly ash can bring positive modification in the condition of normal temperature curing,it brings negative effects in the condition of sub-zero temperature curing.Either redispersible latex powder or ceramsite sand can improve the freeze-thaw cycling resistance of magnesium phosphate cement mortar in the conditions of low temperature coupled with freeze-thaw cycling,but only the ceramsite sand can improve both mechanical properties and freeze-thaw cycling resistance.The modification caused by ceramsite sand is mainly due to the exceptional bonding strength between hardened cement paste and the porous surface of ceramsite and the porous structure of ceramsite for the release of frost heave stress.展开更多
Phosphorus(P)is crucial for plant growth.However,its low availability in subtropical soils necessitates that trees rely on microorganisms for effective P acquisition.The introduction of broadleaf trees has been shown ...Phosphorus(P)is crucial for plant growth.However,its low availability in subtropical soils necessitates that trees rely on microorganisms for effective P acquisition.The introduction of broadleaf trees has been shown to facilitate P acquisition in coniferous plantations by altering the rhizosphere fungal communities.Despite this,functional shifts in these communities and the expression of root phosphorus cycling genes(PCGs)remain inadequately understood.This study investigated coniferous Pinus massoniana and Cunninghamia lanceolata plantations interplanted with broadleaf species associated with arbuscular mycorrhizal(AM)or ectomycorrhizal(ECM)fungi.Rhizosphere soil and fine roots from the conifers were analyzed to examine soil bioavailable P fractions,root mycorrhizal colonization,rhizosphere fungal community composition,enzyme function predictions,and root PCGs expression.We found that citric-P in rhizospheric soil of P.massoniana increased with the introduction of Quercus gilva(an ECM-associated tree species),whereas Bray-P content in the rhizosphere of C.lanceolata decreased upon the introduction of either Q.gilva or Phoebe zhennan(an ECM-associated tree species).Moreover,the relative abundance of saprophytic fungi(e.g.,Mortierella)increased following the introduction of broadleaf trees.Specifically,the introduction of Q.gilva was associated with elevated levels of organic P mineralization genes(e.g.,phoA)and enzymes(e.g.,phytases and acid phosphatase(ACP))in conifers.In contrast,the introduction of P.zhennan increased the expression of inorganic P solubilization genes(such as qppC in P.massoniana roots and ppa in C.lanceolata roots).Key contributors to P absorption in conifer roots included Cenococcum,Rhizopogon,and Glomus.This study advances our understanding of P cycling in coniferous rhizospheres and the dynamics of coexisting mycorrhizal tree systems,yielding valuable insights into sustainable management of plantation ecosystems.展开更多
Subducted sediments,as an integral part of subducted slab,can strongly influence the chemistry of volcanic arc lavas,and clarify the relationship between subduction input and arc output,which is the focus of the subdu...Subducted sediments,as an integral part of subducted slab,can strongly influence the chemistry of volcanic arc lavas,and clarify the relationship between subduction input and arc output,which is the focus of the subduction factory theory in the context of plate tectonics.In this study,we analyzed major and trace element compositions of the subducting sediments from two sites[Deep Sea Drilling Program(DSDP)Site 495 and Ocean Drilling Program(ODP)Site 1039]at the different locations along the Middle America Trench.The results showed that the sediments from these two sites are mainly composed of terrigenous material,carbonate components,and biogenic silicate in different proportions.In order to reduce the effects of the variations in subduction topography on the chemical composition of sediments,we recalculated the bulk subducted sediment composition at northern and southern Central America subduction zone,and identified the Nicaragua Fracture Zone as the dividing line for northern and southern subducting sediments at Middle America Trench.Compared to the global trench subducting sediment,both the subducting sediments from northern and southern Central America subduction zone exhibit lower contents of terrigenous material-controlled elements and are more enriched in the biogenic components-controlled elements.We suggested that the variations in both chemical compositions for sediments and subduction angles are responsible for the different contributions of subducting sediments to volcanic arc magmatism in the northern Central America.展开更多
Recently,lithium metal batteries (LMBs) have been intensively explored owing to its high capacity and low potential of Li as the anode [1].However,challenging problems for LMBs easily occur during cycling process [2],...Recently,lithium metal batteries (LMBs) have been intensively explored owing to its high capacity and low potential of Li as the anode [1].However,challenging problems for LMBs easily occur during cycling process [2],e.g.,the growth of Li dendrites,the formation of unstable electrode-electrolyte interphases and side reactions inside the battery [3].These problems can lead to reduced battery performances and short circuit [4],which are tried to be solved by some strategies including various threedimensional (3D) supports for Li deposition,electrolyte additives and Li alloys.However,it is still difficult to solve the stability of Li cycling effectively.3D supports are demonstrated to be effective for tolerating the volume change during Li deposition.展开更多
In the original publication,incorrect version of Corresponding authors has been published.You-Yuan Huang and Bo Wang should be corresponding authors.The corrected Correspondingg authors are provided in this correction.
Lithium-ion batteries(LIBs)with high energy and power densities are extensively applied in various fields,such as portable electronic devices and electric vehicles.Compared with traditional inorganic electrode materia...Lithium-ion batteries(LIBs)with high energy and power densities are extensively applied in various fields,such as portable electronic devices and electric vehicles.Compared with traditional inorganic electrode materials,which confront the challenges of resource scarcity and restrained energy density,covalent organic frameworks(COFs)are attractive candidates as electrode materials for the next-generation LIBs.Herein,rational Schiff-base condensation of tetraphenyl-pphenylenediamine(TPPDA)and 5,12-bis(4-(5,5-dimethyl-1,3-dioxan-2-yl)phenyl)-5,12-dihydroquinolino[2,3-b]acridine-7,14-dione(QA-PCHO)yields a two-dimensional(2D)QT-COF as the cathode.2D QT-COF features a high crystalline nature with kgm topology and hierarchically micro-/meso-porous structure,which can strengthen the stability of the chemical structure and promote the fast Li^(+)diffusion under large current densities.These merits make the QT-COF cathode exhibit 110,000 ultralong cycling stability with~100%retention at 10,000 mA g^(-1)upon running for 150 days,exceeding all the thus far reported COF-based electrodes.Additionally,the combination of ex situ X-ray photoelectron spectroscopy,in-situ Raman investigation,and theoretical calculation exhaustively unveils the ion storage mechanism and the rationale underlying the exceptional property of QT-COF.The present result offers an advanced COF with enormous potential as organic electrodes for LIBs,hopefully solving the challenges of ultrahigh cycling stability with superb capacity preservation at high current densities.展开更多
In this study,cryogenic cycling treatment was used to process the hot-rolled Mg-4.5Al-2.5Zn alloy sheets to research the influence on mechanical properties and microstructure.Optical microscopy,electron back-scatter d...In this study,cryogenic cycling treatment was used to process the hot-rolled Mg-4.5Al-2.5Zn alloy sheets to research the influence on mechanical properties and microstructure.Optical microscopy,electron back-scatter diffraction and transmission electron microscopy were applied to characterize the microstructures and analyze the mechanisms.The consequences indicate that the cryogenic cycling treatment has significantly influence on improving the mechanical properties.With the cycle of cryogenic cycling treatment increasing to 5 cycles,the sample processed by 3 cycles presents the highest ductility(~18.6%),while the 4-cycle one shows the highest strength(~311.8 MPa).The improvement can be attributed to fine grains,introduced high-density dislocation,9.8%-fraction low-angle grain boundaries(LAGBs),the precipitation of Mg17Al12 phase and the texture with the intensity of 17.5.Although the average grain sizes of the samples processed by cryogenic cycling treatment have no obvious difference,internal stress variations induced by cryogenic cycling treatment significantly influence LAGBs,the basal texture evolution,and the prismaticslip,pyramidal<c>slip and pyramidal<c+a>slip activation.展开更多
With the aim of maximizing nitrogen use efficiency(NUE)of wheat in the North China Plain by optimizing irrigation and nitrogen application,a field experiment with a split-plot design was conducted.The main plots were ...With the aim of maximizing nitrogen use efficiency(NUE)of wheat in the North China Plain by optimizing irrigation and nitrogen application,a field experiment with a split-plot design was conducted.The main plots were subjected to three irrigation levels:bringing soil water content in the 0–40 cm profile to 65%(I1),75%(I2)and 85%(I3)of field water capacity.The subplots were subjected to three nitrogen application rates:150(N150),210(N210)and 270(N270)kg N ha−1.Compared with the N270,N210 treatment enhanced grain yield,NUE,and net income by 4.5%,6.2%,and 5.8%,respectively(two-year averages).Additionally,it reduced soil nitrate reductase activity,the abundance of denitrification-related bacteria,and loss rate of fertilizer nitrogen by 12.9%,53.3%,and 16.3%,respectively.Compared with the N150,N210 treatment increased grain yield,grain nitrogen accumulation,and net income by 15.9%,14.2%,and 26.3%.Relative to I1 and I3,I2 treatment increased root length density in the 20–60 cm soil layer,uptake rate of fertilizer nitrogen,grain yield,and net income.Overall,the combination of irrigation to 75%of field capacity with nitrogen application at 210 kg N ha^(−1)increased wheat’s capacity for nitrogen uptake and remobilization and thereby grain nitrogen accumulation,and increased NUE by reducing nitrogen loss rate.展开更多
Subduction zones are critical interfaces for lithospheric volatile fluxes,where complex tectonic and geochemical interactions facilitate the release of gases and fluids from deep-seated reservoirs within the Earth’s ...Subduction zones are critical interfaces for lithospheric volatile fluxes,where complex tectonic and geochemical interactions facilitate the release of gases and fluids from deep-seated reservoirs within the Earth’s crust.Mud volcanism,as a dynamic manifestation of these processes,contributes CH_(4)emissions that influence the global methane budget and impact marine ecosystems.Although∼2000 CH_(4)-rich mud extrusions have been documented in subduction zones globally,the geological origins and subduction-related geochemical and tectonic mechanisms driving these emissions remain poorly understood.This research examines the Makran subduction zone which hosts one of the world’s largest accretionary wedge and extensive CH_(4)-rich mud extrusions,as a model system.Integrated geochemical,geophysical,and geological observations reveal that thermogenic CH_(4)and clay-rich fluidized muds originate from deeply buried Himalayan turbidites(underthrusted sediments),driven by organic-rich sediment maturation and high fluid overpressure.Key tectonic features,including thrust faults,overburden pressure of wedge-top sediments,normal faults,brittle fractures,and seismicity,facilitate CH_(4)-rich mud extrusions into the hydrosphere and atmosphere.The extruded gases are predominantly CH_(4),with minor C_(2)H_(6),C_(3)H_(8),i-C_(4)H_(10),and n-C_(4)H_(10)while the mud breccia exhibits a chemical composition dominated by SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3),enriched with trace elements(Rb,Zr,and V)and clay minerals,quartz,and carbonates.Geochemical indicators suggest intense chemical weathering and mature sediments classifying the mud breccia as litharenite and sub-litharenite,indicative of deep burial and compaction.These findings model the evolution of CH_(4)-rich mud extrusions through three geological stages:(i)Eocene to Early Miocene pre-thermogenic formation of the CH_(4)-rich source,(ii)Middle Miocene to Pliocene syn-thermogenic CH_(4)and fluidized mud generation,and(iii)Pleistocene to Recent post-thermogenic CH_(4)-rich fluidized mud migration.These findings underscore the critical yet often overlooked role of subduction-related geochemical and tectonic processes in CH_(4)generation and emission,with significant implications for the global CH_(4)budget and marine ecosystems.展开更多
Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This ...Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)exposure.The results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)concentrations.Denitrifying microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 phyla.Further,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite reduction.Functional gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species.The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).展开更多
Effects of film-forming additive on stability of electrode and cycling performance of LiFePO4/graphite cell at elevated temperature were studied. Two 18650 cells with and without VC additive were investigated by galva...Effects of film-forming additive on stability of electrode and cycling performance of LiFePO4/graphite cell at elevated temperature were studied. Two 18650 cells with and without VC additive were investigated by galvanostatic cycling, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis and Raman spectroscopy. The results show that in the presence of VC additive, dissolution of Fe from LiFePO4 material is greatly depressed and stability of graphite structure is improved; the additive can not only reduce reaction of electrolyte on surface of LiFePO4 electrode but also suppress reduction of solvent and thickening of the solid electrolyte interface （SEI） layer on graphite surface. Electrolyte with VC is considered to be a good candidate for improving cycling performance of the LiFePOa/graphite cell at elevated temperature.展开更多
基金supported by the Yunnan Province Science and Technology Plan Project(No.202403AA080001-4)the Key Research and Development Project of Guangxi,China(No.guikeAB24010144)the National Key Research and Development Project of China(Nos.2021YFB3901402 and 2018YFC1504802)。
文摘To reveal the influence of coupled effects of dry-wet cycling and precompression stress(CEDWCPS)on the damage evolution of limestone with horizontal fissure(LHF),a series of degradation and uniaxial compression tests were conducted,and a corresponding piecewise damage constitutive model(PDCM)was established.We found that both dry-wet cycling and precompression stress deteriorate the physical properties,alter the microscopic characteristics,and reduce the mechanical properties of the LHF.These degradations are particularly pronounced under the CEDWCPS,although the magnitude of these changes gradually diminishes with the progression of dry-wet cycling.Meanwhile,they also reduce the deformation degree,prolong the micropore compaction stage,shorten the unstable crack propagation stage,lower the frequency and intensity of AE events,decrease the high-amplitude and high-frequency AE signals,enlarge crack scales,and shorten the crack initiation time.Among the changes of these indicators,the dry-wet cycling plays a dominant role.The crack types of LHF under the CEDWCPS(LHFCEDWCPS)are predominantly tensile cracks,supplemented by shear cracks.The failure mode can be defined as tensileshear composite failure.Finally,the established PDCM effectively captures the nonlinear deformation of micropore and the linear deformation of the matrix in LHFCEDWCPS,with all corresponding R^(2) consistently exceeding 0.97.
基金supported by the National Natural Science Foundation of China (Grant Nos.U23A6018,42362034)the Applied Basic Research Foundation of Yunnan Province,China (Grant No.202401AS070068)。
文摘The construction of lunar bases represents a crucial goal for long-term human residence on the Moon and future deep-space exploration. Vacuum sintering of lunar regolith for in-situ resource utilization(ISRU) is considered one of the most feasible strategies for early lunar infrastructure development. However, the extreme temperature fluctuations on the lunar surface pose potential threats to the structural stability of sintered regolith materials. To investigate the mechanical deterioration and damage mechanism of vacuum-sintered lunar regolith under extreme cryogenic-thermal cycling, lunar regolith simulants are used to fabricate specimens through vacuum sintering. A series of cryogenic-thermal cycling tests is designed, combined with uniaxial compression and X-ray CT scanning, to systematically analyze their macro-micro responses. The results show that with increasing extreme cryogenic-thermal cycles, the stress-strain curves evolve from typical brittle failure to quasiductile behavior, with uniaxial compressive strength and elastic modulus decreasing by approximately 33.86% and 61.98%, respectively. CT analyses reveal that the pore structure transforms from isolated pores to connected networks, with the pore volume fraction increasing from 13.33% to 22.64%, and the fractal dimension increases from 2.465 to 2.544, and stabilizes after multiple cycles. A significant negative correlation(R^(2)> 0.96) exists between pore structural complexity and mechanical performance. Based on these findings, a thermal fatigue damage mechanism dominated by thermal stress concentration due to mismatched thermal expansion coefficients among mineral phases is proposed. This study provides scientific insights for the design, durability evaluation, and ISRU-based construction of lunar surface infrastructure.
基金supported by the Guangdong Basic and Applied Basic Research Foundation,China(No.2021B1515140007).
文摘The rapid cycling synchrotron(RCS)at the China spallation neutron source operates as a high-intensity proton accelerator.The coupled bunch instability was observed during RCS beam commissioning,which significantly limited the beam power.To investigate the dynamics of instability under an increased beam power,a pulsed octupole magnet with a gradient of 900 T/m^(3) was developed.The magnet system integrated an octupole magnet with a pulsed power supply.The field was carefully measured to examine the performance before its installation into the tunnel.After the installation of the magnets,beam measurements were performed to confirm the effectiveness of the instability mitigation on an actual proton beam.The measurement results show that the instability can be suppressed using the pulsed octupole magnet,particularly at the highenergy stage in an acceleration cycle,meeting the requirements for stable operation of the accelerator.Additionally,when the instability is completely suppressed through chromaticity optimization,octupole magnets can significantly enhance the RCS transmission efficiency,which is crucial for controlling beam loss.The pulsed octupole magnet offers significant progress in beam stability in the RCS,providing valuable experience for further beam power enhancement.
基金supported by grants from the National Research Foundation of Korea(NRF),funded by the Korean government(RS-2024-00408795 and RS-2024-00466473).
文摘The efficient recycling of poly(ethylene terephthalate)and poly(butylene terephthalate),the most extensively produced plastics,is essential for reducing global carbon emissions and the current dependence on fossil resources.However,the chemical recycling of polyesters primarily involves polymer-to-monomer and monomer-to-polymer processes,resulting in significant greenhouse gas emissions owing to significant electricity and fuel consumption.Herein,this research reports a simple and efficient one-pot polymer-to-polymer upcycling process that directly converts these two polyester wastes into biodegradable thermoplastic poly(ether ester)s using poly(tetramethylene ether)glycol(PTMG).The synthesized series of poly((ET-co-BT)-mb-PTMG)(PEBTG)exhibit a maximum tensile strength of 68 MPa,with 85%weight loss after 20 weeks in composted soil.Techno-economic analysis and life cycle assessment indicate that PEBTG is more cost-competitive and environmentally beneficial than currently existing plastics derived from fossil fuels,such as polypropylene and polybutylene adipate terephthalate.Once de-risked,the proposed upcycling strategy for polymer waste can be extended to expedite the development of a sustainable plastic economy.
基金supported by the Lithium Resources and Lithium Materials Key Laboratory of Sichuan Province(LRMKF202405)the National Natural Science Foundation of China(52402226)+3 种基金the Natural Science Foundation of Sichuan Province(2024NSFSC1016)the Scientific Research Startup Foundation of Chengdu University of Technology(10912-KYQD2023-10240)the opening funding from Key Laboratory of Engineering Dielectrics and Its Application(Harbin University of Science and Technology)(KFM202507,Ministry of Education)the funding provided by the Alexander von Humboldt Foundation。
文摘The properties of electrolytes are critical for fast-charging and stable-cycling applications in lithium metal batteries(LMBs).However,the slow kinetics of Li^(+)transport and desolvation in commercial carbonate electrolytes,cou pled with the formation of unstable solid electrolyte interphases(SEI),exacerbate the degradation of LMB performance at high current densities.Herein,we propose a versatile electrolyte design strategy that incorporates cyclohexyl methyl ether(CME)as a co-solvent to reshape the Li^(+)solvation environment by the steric-hindrance effect of bulky molecules and their competitive coordination with other solvent molecules.Simulation calculations and spectral analysis demonstrate that the addition of CME molecules reduces the involvement of other solvent molecules in the Li solvation sheath and promotes the formation of Li^(+)-PF_(6)^(-)coordination,thereby accelerating Li^(+)transport kinetics.Additionally,this electrolyte composition improves Li^(+)desolvation kinetics and fosters the formation of inorganic-rich SEI,ensuring cycle stability under fast charging.Consequently,the Li‖LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)battery with the modified electrolyte retains 82% of its initial capacity after 463 cycles at 1 C.Even under the extreme fast-charging condition of 5 C,the battery can maintain 80% capacity retention after 173 cycles.This work provides a promising approach for the development of highperformance LMBs by modulating solvation environment of electrolytes.
文摘1 A few decades ago,it was common to see groups of chil-dren riding bikes down quiet American streets.However,this scene is less likely to be seen today.In the 1990s,an average of 20.5 million children aged 7 to 17 rode bikes six or more times a year,according to the National Sporting Goods Association.By 2023,this number had dropped to about 10.9 million,with less than 5%of them riding frequently.
基金supported by the National Natural Science Foundation of China(Nos.22279111,51971195,and 11935004)the Natural Science Foundation of Hebei Province(No.B2020203037)Subsidy for Hebei Key Laboratory of Applied Chemistry after Operation Performance(No.22567616H).
文摘MgH_(2) has been extensively studied as one of the most ideal solid hydrogen storage materials.Nevertheless,rapid capacity decay and sluggish hydrogen storage kinetics hamper its practical application.Herein,a Ni/C nano-catalyst doped MgH_(2)(MgH_(2)–Ni/C)shows an improved hydrogen absorption kinetics with largely reduced activation energy.Particularly,the MgH_(2)–Ni/C displays remarkable cycling stability,which maintains a high capacity of 6.01 wt.%(98.8%of initial capacity)even after 50 full hydrogen ab/desorption cycles,while the undoped MgH_(2) counterpart retains only 85.2%of its initial capacity.Detailed microstructure characterizations clearly reveal that particle sintering/growth accounts primarily for the deterioration of cycling performance of undoped MgH_(2).By comparison,MgH_(2)–Ni/C can maintain a stable particle size with a growing porous structure during long-term cycling,which effectively increases the specific surface of the particles.A novel carbon-induced-porosity stabilization mechanism is proposed,which can stabilize the proportion of rapid hydrogen absorption process,thus dominating the excellent cycling performance of MgH_(2)–Ni/C.This study provides new insights into the cycling stability mechanism of carbon-containing Mg-based hydrogen storage materials,thus promoting their practical applications.
基金supported by the National Natural Science Foundation of China(52222407).
文摘Magnesium ion batteries(MIBs)are a promising alternative to lithium-ion batteries,which suffer from the short cycling life and sluggish Mg^(2+)diffusion kinetics of cathodes.Nano morphologies are used to shorten Mg^(2+)diffusion path for diffusion kinetics acceleration,but the cycling life is still unsatisfactory.Herein,the anisotropy of layered V_(3)O_(7)·1.9H_(2)O nanobelts is utilized to stabilize their structure during discharging/charging.The V_(3)O_(7)·1.9H_(2)O nanobelts grow along the preponderant migration direction of Mg^(2+),and the resulted axial migration of Mg^(2+)enables the stress caused by Mg^(2+)insertion to be decentralized in large zone,thus improving the cycling stability of V_(3)O_(7)·1.9H_(2)O nanobelts.The inserted Mg^(2+)cations bond with O atoms in adjacent V3O8 layers of V_(3)O_(7)·1.9H_(2)O,further stablizing the layered structure.Meanwhile,the axial migration of Mg^(2+)significantly reduces the charge transfer resistance at electrode/electrolyte interface,which accelerates the Mg^(2+)diffusion kinetics.Thus,the symmetric RMB assembled from V_(3)O_(7)·1.9H_(2)O nanobelts exhibits an ultralong cycling life of 11,000 cycles at 4 A g^(-1),alongside a high specific capacity of 137 mAh g^(-1)at 0.05 A g^(-1).According to our knowledge,this ultralong cycling life surpasses those of reported full RMBs.This strategy provides insight into the design of cathode materials with improved cycling lives.
基金support from the National Key Research and Development Program of China(No.2022YFB2502000)the National Natural Science Foundation of China(Grant Nos.52201277)+1 种基金the key program of the National Natural Science Foundation of China(Grant Nos.51831009)the National Outstanding Youth Foundation of China(No.52125104).
文摘Lithium and manganese-rich layered oxides(LMROs)have attracted extensive attention and are promising cathode materials for next-generation lithium ion batteries due to their high capacities and high energy densities.However,LMRO cathode suffers from severe capacity and voltage fading originating from irreversible surface oxygen evolution.Herein,we propose a facile redox couple strategy by introducing nitroxyl radicals species to regulate the surface anionic redox reaction of LMRO cathode.Differential electrochemical mass spectroscopy,X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses demonstrate that during charge process,the peroxide ion O_(2)^(2−)on the surface generated from the oxidation of lattice O^(2-)could be reduced back to stable O^(2-)by redox couple in time,thus avoiding oxygen evolution and structure degradation,as well as enhancing bulk oxygen redox activity.The enhanced LMRO electrode delivers a high capacity of 220.3 mAh g^(−1)at 1 C.An excellent cycling stability with a capacity retention of 94.4%is achieved after 500 cycles,as well as a suppressed voltage decay with only 1.12 mV per cycle.
基金Funded by the National Natural Science Foundation of China(No.51878227)。
文摘Microstructures and properties of mortar using ammonium phosphate and potassium phosphate were tested and compared in this case.Moreover,two cementitious additions and two lightweight aggregates,including fly ash,redispersible latex powder,ceramsite sand,and rubber powder,were respectively tried to be applied in magnesium ammonium phosphate cement mortar in order to modify the microstructures and properties.The experimental results show that potassium phosphate is not suitable for magnesium phosphate cement mortar for cold region construction purpose.Although fly ash can bring positive modification in the condition of normal temperature curing,it brings negative effects in the condition of sub-zero temperature curing.Either redispersible latex powder or ceramsite sand can improve the freeze-thaw cycling resistance of magnesium phosphate cement mortar in the conditions of low temperature coupled with freeze-thaw cycling,but only the ceramsite sand can improve both mechanical properties and freeze-thaw cycling resistance.The modification caused by ceramsite sand is mainly due to the exceptional bonding strength between hardened cement paste and the porous surface of ceramsite and the porous structure of ceramsite for the release of frost heave stress.
基金supported by the National Natural Science Foundation of China (No. 32271731)Research Project of Education Department of Hunan Province (Nos. 21A0164 and 22B0241)+7 种基金Furong Scholar (Young Scholar) of Education Department of Hunan Provincethe Changsha Outstanding Innovative Youth Training Program (No. kq2209018) to Chen NingThe National Natural Science Foundation of China (No. U21A20187)the China Postdoctoral Science Foundation (No. 2023M743973)the Hunan Provincial Natural Science Foundation of China (No. 2023JJ41033)the Changsha Municipal Natural Science Foundation (No. kq2208409)the Talent Research Initiation Fund of Central South University of Forestry and Technology (No. ZK2023YJ001) to Ting LiuThe Creative Research Groups of Provincial Natural Science Foundation of Hunan (No. 2024JJ1016) to Wende Yan
文摘Phosphorus(P)is crucial for plant growth.However,its low availability in subtropical soils necessitates that trees rely on microorganisms for effective P acquisition.The introduction of broadleaf trees has been shown to facilitate P acquisition in coniferous plantations by altering the rhizosphere fungal communities.Despite this,functional shifts in these communities and the expression of root phosphorus cycling genes(PCGs)remain inadequately understood.This study investigated coniferous Pinus massoniana and Cunninghamia lanceolata plantations interplanted with broadleaf species associated with arbuscular mycorrhizal(AM)or ectomycorrhizal(ECM)fungi.Rhizosphere soil and fine roots from the conifers were analyzed to examine soil bioavailable P fractions,root mycorrhizal colonization,rhizosphere fungal community composition,enzyme function predictions,and root PCGs expression.We found that citric-P in rhizospheric soil of P.massoniana increased with the introduction of Quercus gilva(an ECM-associated tree species),whereas Bray-P content in the rhizosphere of C.lanceolata decreased upon the introduction of either Q.gilva or Phoebe zhennan(an ECM-associated tree species).Moreover,the relative abundance of saprophytic fungi(e.g.,Mortierella)increased following the introduction of broadleaf trees.Specifically,the introduction of Q.gilva was associated with elevated levels of organic P mineralization genes(e.g.,phoA)and enzymes(e.g.,phytases and acid phosphatase(ACP))in conifers.In contrast,the introduction of P.zhennan increased the expression of inorganic P solubilization genes(such as qppC in P.massoniana roots and ppa in C.lanceolata roots).Key contributors to P absorption in conifer roots included Cenococcum,Rhizopogon,and Glomus.This study advances our understanding of P cycling in coniferous rhizospheres and the dynamics of coexisting mycorrhizal tree systems,yielding valuable insights into sustainable management of plantation ecosystems.
基金The Laoshan Laboratory Project under contract No.LSKJ202204103the National Natural Science Foundation of China under contract Nos 41322036 and 41776070+1 种基金the Qingdao Postdoctoral Sustentation Foundation under contract No.QDBSH20220202147the Taishan Scholarship from Shandong Province under contract No.tstp20230643.
文摘Subducted sediments,as an integral part of subducted slab,can strongly influence the chemistry of volcanic arc lavas,and clarify the relationship between subduction input and arc output,which is the focus of the subduction factory theory in the context of plate tectonics.In this study,we analyzed major and trace element compositions of the subducting sediments from two sites[Deep Sea Drilling Program(DSDP)Site 495 and Ocean Drilling Program(ODP)Site 1039]at the different locations along the Middle America Trench.The results showed that the sediments from these two sites are mainly composed of terrigenous material,carbonate components,and biogenic silicate in different proportions.In order to reduce the effects of the variations in subduction topography on the chemical composition of sediments,we recalculated the bulk subducted sediment composition at northern and southern Central America subduction zone,and identified the Nicaragua Fracture Zone as the dividing line for northern and southern subducting sediments at Middle America Trench.Compared to the global trench subducting sediment,both the subducting sediments from northern and southern Central America subduction zone exhibit lower contents of terrigenous material-controlled elements and are more enriched in the biogenic components-controlled elements.We suggested that the variations in both chemical compositions for sediments and subduction angles are responsible for the different contributions of subducting sediments to volcanic arc magmatism in the northern Central America.
基金financially supported by Henan Provincial Science and Technology Research Project(No.242102230103)。
文摘Recently,lithium metal batteries (LMBs) have been intensively explored owing to its high capacity and low potential of Li as the anode [1].However,challenging problems for LMBs easily occur during cycling process [2],e.g.,the growth of Li dendrites,the formation of unstable electrode-electrolyte interphases and side reactions inside the battery [3].These problems can lead to reduced battery performances and short circuit [4],which are tried to be solved by some strategies including various threedimensional (3D) supports for Li deposition,electrolyte additives and Li alloys.However,it is still difficult to solve the stability of Li cycling effectively.3D supports are demonstrated to be effective for tolerating the volume change during Li deposition.
文摘In the original publication,incorrect version of Corresponding authors has been published.You-Yuan Huang and Bo Wang should be corresponding authors.The corrected Correspondingg authors are provided in this correction.
基金financially supported by the Natural Science Foundation of China(22235001,22175020 and 22001015)the Fundamental Research Funds for the Central Universities(No.2050205)+2 种基金the Guizhou Provincial Key Laboratory Platform Project(ZSYS[2025]008)the Talent Program of Guizhou University(No.[2024]11)the Science and Technology Project of Jiangsu Province(BZ2022056)。
文摘Lithium-ion batteries(LIBs)with high energy and power densities are extensively applied in various fields,such as portable electronic devices and electric vehicles.Compared with traditional inorganic electrode materials,which confront the challenges of resource scarcity and restrained energy density,covalent organic frameworks(COFs)are attractive candidates as electrode materials for the next-generation LIBs.Herein,rational Schiff-base condensation of tetraphenyl-pphenylenediamine(TPPDA)and 5,12-bis(4-(5,5-dimethyl-1,3-dioxan-2-yl)phenyl)-5,12-dihydroquinolino[2,3-b]acridine-7,14-dione(QA-PCHO)yields a two-dimensional(2D)QT-COF as the cathode.2D QT-COF features a high crystalline nature with kgm topology and hierarchically micro-/meso-porous structure,which can strengthen the stability of the chemical structure and promote the fast Li^(+)diffusion under large current densities.These merits make the QT-COF cathode exhibit 110,000 ultralong cycling stability with~100%retention at 10,000 mA g^(-1)upon running for 150 days,exceeding all the thus far reported COF-based electrodes.Additionally,the combination of ex situ X-ray photoelectron spectroscopy,in-situ Raman investigation,and theoretical calculation exhaustively unveils the ion storage mechanism and the rationale underlying the exceptional property of QT-COF.The present result offers an advanced COF with enormous potential as organic electrodes for LIBs,hopefully solving the challenges of ultrahigh cycling stability with superb capacity preservation at high current densities.
基金partly supported by the National Natural Science Foundation of China(Grant No.52174362)the Natural Science Foundation of Hunan Province(Grant No.2023JJ10020)+2 种基金the Science and Technology Innovation Program of Hunan Province(Grant No.2022RC4012)the Shaanxi Provincial Key R&D Program(2024CY2-GJHX-71)the Hunan Innovative Province Construction Special Program(2019GK1012).
文摘In this study,cryogenic cycling treatment was used to process the hot-rolled Mg-4.5Al-2.5Zn alloy sheets to research the influence on mechanical properties and microstructure.Optical microscopy,electron back-scatter diffraction and transmission electron microscopy were applied to characterize the microstructures and analyze the mechanisms.The consequences indicate that the cryogenic cycling treatment has significantly influence on improving the mechanical properties.With the cycle of cryogenic cycling treatment increasing to 5 cycles,the sample processed by 3 cycles presents the highest ductility(~18.6%),while the 4-cycle one shows the highest strength(~311.8 MPa).The improvement can be attributed to fine grains,introduced high-density dislocation,9.8%-fraction low-angle grain boundaries(LAGBs),the precipitation of Mg17Al12 phase and the texture with the intensity of 17.5.Although the average grain sizes of the samples processed by cryogenic cycling treatment have no obvious difference,internal stress variations induced by cryogenic cycling treatment significantly influence LAGBs,the basal texture evolution,and the prismaticslip,pyramidal<c>slip and pyramidal<c+a>slip activation.
基金supported by the National Natural Science Foundation of China(32172114)China Agriculture Research System of MOF and MARA(CARS-03)Taishan scholar Project Special Funds(202211094).
文摘With the aim of maximizing nitrogen use efficiency(NUE)of wheat in the North China Plain by optimizing irrigation and nitrogen application,a field experiment with a split-plot design was conducted.The main plots were subjected to three irrigation levels:bringing soil water content in the 0–40 cm profile to 65%(I1),75%(I2)and 85%(I3)of field water capacity.The subplots were subjected to three nitrogen application rates:150(N150),210(N210)and 270(N270)kg N ha−1.Compared with the N270,N210 treatment enhanced grain yield,NUE,and net income by 4.5%,6.2%,and 5.8%,respectively(two-year averages).Additionally,it reduced soil nitrate reductase activity,the abundance of denitrification-related bacteria,and loss rate of fertilizer nitrogen by 12.9%,53.3%,and 16.3%,respectively.Compared with the N150,N210 treatment increased grain yield,grain nitrogen accumulation,and net income by 15.9%,14.2%,and 26.3%.Relative to I1 and I3,I2 treatment increased root length density in the 20–60 cm soil layer,uptake rate of fertilizer nitrogen,grain yield,and net income.Overall,the combination of irrigation to 75%of field capacity with nitrogen application at 210 kg N ha^(−1)increased wheat’s capacity for nitrogen uptake and remobilization and thereby grain nitrogen accumulation,and increased NUE by reducing nitrogen loss rate.
基金funded by the National Natural Science Foundation of China(Grants No.92058213 and No.U22A20581)the Specific Research Fund of the Innovation Platform for Academicians of Hainan Province(Grant No.YSPTZX202204)key R&D projects of Hainan Province(ZDYF2024GXJS022).
文摘Subduction zones are critical interfaces for lithospheric volatile fluxes,where complex tectonic and geochemical interactions facilitate the release of gases and fluids from deep-seated reservoirs within the Earth’s crust.Mud volcanism,as a dynamic manifestation of these processes,contributes CH_(4)emissions that influence the global methane budget and impact marine ecosystems.Although∼2000 CH_(4)-rich mud extrusions have been documented in subduction zones globally,the geological origins and subduction-related geochemical and tectonic mechanisms driving these emissions remain poorly understood.This research examines the Makran subduction zone which hosts one of the world’s largest accretionary wedge and extensive CH_(4)-rich mud extrusions,as a model system.Integrated geochemical,geophysical,and geological observations reveal that thermogenic CH_(4)and clay-rich fluidized muds originate from deeply buried Himalayan turbidites(underthrusted sediments),driven by organic-rich sediment maturation and high fluid overpressure.Key tectonic features,including thrust faults,overburden pressure of wedge-top sediments,normal faults,brittle fractures,and seismicity,facilitate CH_(4)-rich mud extrusions into the hydrosphere and atmosphere.The extruded gases are predominantly CH_(4),with minor C_(2)H_(6),C_(3)H_(8),i-C_(4)H_(10),and n-C_(4)H_(10)while the mud breccia exhibits a chemical composition dominated by SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3),enriched with trace elements(Rb,Zr,and V)and clay minerals,quartz,and carbonates.Geochemical indicators suggest intense chemical weathering and mature sediments classifying the mud breccia as litharenite and sub-litharenite,indicative of deep burial and compaction.These findings model the evolution of CH_(4)-rich mud extrusions through three geological stages:(i)Eocene to Early Miocene pre-thermogenic formation of the CH_(4)-rich source,(ii)Middle Miocene to Pliocene syn-thermogenic CH_(4)and fluidized mud generation,and(iii)Pleistocene to Recent post-thermogenic CH_(4)-rich fluidized mud migration.These findings underscore the critical yet often overlooked role of subduction-related geochemical and tectonic processes in CH_(4)generation and emission,with significant implications for the global CH_(4)budget and marine ecosystems.
基金supported by the National Natural Science Foundation of China(No.41977029).
文摘Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)exposure.The results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)concentrations.Denitrifying microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 phyla.Further,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite reduction.Functional gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species.The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).
基金Project(2007BAE12B01)supported by the National Key Technology Research and Development Program of ChinaProject(20803095)supported by the National Natural Science Foundation of China
文摘Effects of film-forming additive on stability of electrode and cycling performance of LiFePO4/graphite cell at elevated temperature were studied. Two 18650 cells with and without VC additive were investigated by galvanostatic cycling, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis and Raman spectroscopy. The results show that in the presence of VC additive, dissolution of Fe from LiFePO4 material is greatly depressed and stability of graphite structure is improved; the additive can not only reduce reaction of electrolyte on surface of LiFePO4 electrode but also suppress reduction of solvent and thickening of the solid electrolyte interface （SEI） layer on graphite surface. Electrolyte with VC is considered to be a good candidate for improving cycling performance of the LiFePOa/graphite cell at elevated temperature.
