Prescribed fire has now become the usual management practice in the Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） plantation in southern China. Heat generated during fire may affect carbon （C） dynam- ics i...Prescribed fire has now become the usual management practice in the Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） plantation in southern China. Heat generated during fire may affect carbon （C） dynam- ics in soils. We investigated the microbial biomass C （MBC） and microbial respiration in two Chinese fir forest soils （one is not exposed to fire for the past 88 years, and the other is recently exposed to prescribed fire） after soil heating （100 and 200 ℃） under three moisture regimes [25, 50 and 75 % of water holding capacity （WHC）]. For both soils, significant reduction in MBC with increasing heating temperature was found. Soils without exposing to fire previously had significantly greater MBC concentra- tion than the fire-exposed soils when heated at 100 or 200 ℃. Lower soil water content resulted in higher MBC concentrations in both soils. In contrast, both soils had the highest soil microbial respiration rate at 50 % WHC. Soils without exposing to fire previously had the greatest microbial respiration rates at 200 ℃, while the fire-ex- posed soils when heated at 100 ℃ had greatest microbialrespiration rates. During 14-days post-heat incubation, soil MBC in both soils was greatest after heating at 200 ℃ and 25 % WHC. However, soil previously exposed to fire had the lowest CO2 evolution when incubated at 25 % WHC.展开更多
To address the corrosion and dendrite issues of lithium metal anodes, a protective layer was ex-situ constructed by P4S10 modification. It was determined by X-ray photoelectron spectroscopy and Raman spectra that the ...To address the corrosion and dendrite issues of lithium metal anodes, a protective layer was ex-situ constructed by P4S10 modification. It was determined by X-ray photoelectron spectroscopy and Raman spectra that the main constituents of the protective layer were P4S10, Li3PS4 and other LixPySztype derivatives. The protective layer was proved to be effective to stabilize the interphase of lithium metal. With the modified Li anodes, symmetric cells could deliver stable Li plating/stripping for 16000 h;Li–S batteries exhibited a specific capacity of 520 m A h g-1 after 200 cycles at 1000 m A g-1 with average Coulombic efficiency of 97.9%. Therefore, introducing LixPySzbased layer to protect Li anode provides a new strategy for the improvement of Li metal batteries.展开更多
Various nanostructured architectures have been demonstrated to be effective to address the issues of high capacity Si anodes. However, the scale-up of these nano-Si materials is still a critical obstacle for commercia...Various nanostructured architectures have been demonstrated to be effective to address the issues of high capacity Si anodes. However, the scale-up of these nano-Si materials is still a critical obstacle for commercialization. Herein, we use industrial ferrosilicon as low-cost Si source and introduce a facile and scalable method to fabricate a micrometer-sized ferrosilicon/C composite anode, in which ferrosilicon microparticles are wrapped with multi-layered carbon nanosheets. The multi-layered carbon nanosheets could effectively buffer the volume variation of Si as well as create an abundant and reliable conductivity framework, ensuring fast transport of electrons. As a result, the micrometer-sized ferrosilicon/C anode achieves a stable cycling with 805.9 m Ah g-1 over 200 cycles at 500 mA g-1 and a good rate capability of455.6 mAh g-1 at 10 A g-1. Therefore, our approach based on ferrosilicon provides a new opportunity in fabricating cost-effective, pollution-free, and large-scale Si electrode materials for high energy lithium-ion batteries.展开更多
Mid-subtropical forests are the main vegetation type of global terrestrial biomes, and are critical for maintaining the global carbon balance. However, estimates of forest biomass increment in mid-subtropical forests ...Mid-subtropical forests are the main vegetation type of global terrestrial biomes, and are critical for maintaining the global carbon balance. However, estimates of forest biomass increment in mid-subtropical forests remain highly uncertain. It is critically important to determine the relative importance of different biotic and abiotic factors between plants and soil, particularly with respect to their influence on plant regrowth. Consequently,it is necessary to quantitatively characterize the dynamicspatiotemporal distribution of forest carbon sinks at a regional scale. This study used a large, long-term dataset in a boosted regression tree（BRT） model to determine the major components that quantitatively control forest biomass increments in a mid-subtropical forested region（Wuyishan National Nature Reserve, China）. Long-term,stand-level data were used to derive the forest biomass increment, with the BRT model being applied to quantify the relative contributions of various biotic and abiotic variables to forest biomass increment. Our data show that total biomass（t） increased from 4.62 9 106 to 5.30 9 106 t between 1988 and 2010, and that the mean biomass increased from 80.19 ± 0.39 t ha-1（mean ± standard error） to 94.33 ± 0.41 t ha-1in the study region. The major factors that controlled biomass（in decreasing order of importance） were the stand, topography, and soil. Stand density was initially the most important stand factor, while elevation was the most important topographic factor. Soil factors were important for forest biomass increment but have a much weaker influence compared to the other two controlling factors. These results provide baseline information about the practical utility of spatial interpolationmethods for mapping forest biomass increments at regional scales.展开更多
An investigation was performed on the suitability of carbon materials, metallic lead and its alloys as substrates for zinc negative electrode in acid PbO2-Zn single flow batteries. The zinc deposition process was carr...An investigation was performed on the suitability of carbon materials, metallic lead and its alloys as substrates for zinc negative electrode in acid PbO2-Zn single flow batteries. The zinc deposition process was carried out in the mediumofl mol.L 1H2SO4 at room temperature. No maximum current appears on the potentiostatic current transients for the zinc deposition on lead and its alloys. With increasing overpotential, the progressive nucleation turns to be a 3D-instantaneous nucleation process for the resin-graphite composite. Hydrogen evolution on the graphite composite is effectively suppressed with the doping of a polymer resin. The hydrogen evolution reaction on the lead is relatively weak, while on the lead alloys, it becomes serious to a certain degree. Although the ex- change current density of zinc deposition and dissolution process on the graphite composite is relatively low, the zinc corrosion is weakened to a great extent. With the increase of deposition time, zinc deposits are more compact. The cyclings of zinc galvanostatic charge-discharge on the graphite composite provide more than 90% of coulombic and 80% of energy efficiencies, and exhibit superior cycling stability during the first 10 cycles.展开更多
Aims Biomass allocation to different organs is a fundamental plant ecophysiological process to better respond to changing environments;yet,it remains poorly understood how patterns of biomass allocation respond to nit...Aims Biomass allocation to different organs is a fundamental plant ecophysiological process to better respond to changing environments;yet,it remains poorly understood how patterns of biomass allocation respond to nitrogen(N)additions across terrestrial ecosystems worldwide.Methods We conducted a meta-analysis using 5474 pairwise observations from 333 articles to assess how N addition affected plant biomass and biomass allocation among different organs.We also tested the'ratio-based optimal partitioning'vs.the'isometric allocation,hypotheses to explain potential N addition effects on biomass allocation.Important Findings We found that(i)N addition significantly increased whole plant biomass and the biomass of different organs,but decreased rootrshoot ratio(RS)and root mass fraction(RMF)while no effects of N addition on leaf mass fraction and stem mass fraction at the global scale;(ii)the effects of N addition on ratio-based biomass allocation were mediated by individual or interactive effects of moderator variables such as experimental conditions,plant functional types,latitudes and rates of N addition and(iii)N addition did not affect allometric relationships among different organs,suggesting that decreases in RS and RMF may result from isometric allocation patterns following increases in whole plant biomass.Despite alteration of ratio-based biomass allocation between root and shoot by N addition,the unaffected allometric scaling relationships among different organs(including root vs.shoot)suggest that plant biomass allocation patterns are more appropriately explained by the isometric allocation hypothesis rather than the optimal partitioning hypothesis.Our findings contribute to better understand N-induced effects on allometric relationships of terrestrial plants,and suggest that these ecophysiological responses should be incorporated into models that aim to predict how terrestrial ecosystems may respond to enhanced N deposition under future global change scenarios.展开更多
This work presents a new method for preparation of samarium alloy. Using A1 rod as anode, electrochemical formation of Sm-A1 alloy on Mo electrode from Sm203 in LiC1- KC1-MgC12-KF molten salts was investigated. Samari...This work presents a new method for preparation of samarium alloy. Using A1 rod as anode, electrochemical formation of Sm-A1 alloy on Mo electrode from Sm203 in LiC1- KC1-MgC12-KF molten salts was investigated. Samarium mainly exists in the form of A12Sm in Li-Mg matrix, and the concentration of Sm in this alloy runs up to be as high as 34.7%. The reaction of samarium preparation appears like a replacement reaction. The new preparation method makes possible a high samarium content in electrochemical deposition of Sm-A1 alloy. Using A1 rod as anode consumedly decreased, the electrolytic cell voltage, and facilitated Sm deposition from Sm203. This preparation method uses 8m203 as raw materials to gain samarium alloy directly, which could revolutionize the industrial production of samarium alloys.展开更多
The electrochemical behavior of Mg, Li, AI and Er were investigated by electrochemical techniques in LiCI- KCI-MgCI2-AICI3-ErCI3 melts at 823 K. The cyclic voltammetry and chronopotentiometry indicated that the co-red...The electrochemical behavior of Mg, Li, AI and Er were investigated by electrochemical techniques in LiCI- KCI-MgCI2-AICI3-ErCI3 melts at 823 K. The cyclic voltammetry and chronopotentiometry indicated that the co-reduction of Mg, Li, AI and Er occurs at current densities more negative than -0.89 A.cm-2. Er（lll） under-potential deposited on pre-reduced AI electrode formed AI-RE alloys. X-ray diffraction （XRD） results indicated that Mg17Al12, Al2Er, Al2Er3 and Al4Li9 phases were prepared by galvanostatic electrolysis. ICP analyses of samples showed that lithium and aluminum contents of Mg-Li-AI-Er alloys could be controlled by concentration of AICI3 and cathodic current density.展开更多
Over the years,electroconductive hydrogels(ECHs)have been extensively applied for stimulating nerve regeneration and restoring locomotor function after peripheral nerve injury(PNI)with diabetes,given their favorable m...Over the years,electroconductive hydrogels(ECHs)have been extensively applied for stimulating nerve regeneration and restoring locomotor function after peripheral nerve injury(PNI)with diabetes,given their favorable mechanical and electrical properties identical to endogenous nerve tissue.Nevertheless,PNI causes the loss of locomotor function and inflammatory pain,especially in diabetic patients.It has been established that bone marrow stem cells-derived exosomes(BMSCs-Exos)have analgesic,anti-inflammatory and tissue regeneration properties.Herein,we designed an ECH loaded with BMSCs-Exos(ECH-Exos)electroconductive nerve dressing to treat diabetic PNI to achieve functional recovery and pain relief.Given its potent adhesive and self-healing properties,this laminar dressing is convenient for the treatment of damaged nerve fibers by automatically wrapping around them to form a size-matched tube-like structure,avoiding the cumbersome implantation process.Our in vitro studies showed that ECH-Exos could facilitate the attachment and migration of Schwann cells.Meanwhile,Exos in this system could modulate M2 macrophage polarization via the NF-κB pathway,thereby attenuating inflammatory pain in diabetic PNI.Additionally,ECH-Exos enhanced myelinated axonal regeneration via the MEK/ERK pathway in vitro and in vivo,consequently ameliorating muscle denervation atrophy and further promoting functional restoration.Our findings suggest that the ECH-Exos system has huge prospects for nerve regeneration,functional restoration and pain relief in patients with diabetic PNI.展开更多
At present,effective fixation and anti-infection implant materials represent the mainstay for the treatment of open fractures.However,external fixation can cause nail tract infections and is ineffective for fixing sma...At present,effective fixation and anti-infection implant materials represent the mainstay for the treatment of open fractures.However,external fixation can cause nail tract infections and is ineffective for fixing small fracture fragments.Moreover,closed reduction and internal fixation during the early stage of injury can lead to potential bone infection,conducive to bone nonunion and delayed healing.Herein,we designed a bone adhesive with anti-infection,osteogenic and bone adhesion fixation properties to promote reduction and fixation of open fractures and subsequent soft tissue repair.It was prepared by the reaction of gelatin(Gel)and oxidized starch(OS)with vancomycin(VAN)-loaded mesoporous bioactive glass nanoparticles(MBGNs)covalently cross-linked with Schiff bases.Characterization and adhesion experiments were conducted to validate the successful preparation of the Gel-OS/VAN@MBGNs(GOVM-gel)adhesive.Meanwhile,in vitro cell experiments demonstrated its good antibacterial effects with the ability to stimulate bone marrow mesenchymal stem cell(BMSCs)proliferation,upregulate the expression of alkaline phosphatase(ALP)and osteogenic proteins(RunX2 and OPN)and enhance the deposition of calcium nodules.Additionally,we established a rat skull fracture model and a subcutaneous infection model.The histological analysis showed that bone adhesive enhanced osteogenesis,and in vivo experiments demonstrated that the number of inflammatory cells and bacteria was significantly reduced.Overall,the adhesive could promote early reduction of fractures and antibacterial and osteogenic effects,providing the foothold for treatment of this patient population.展开更多
Background:China’s terrestrial ecosystems have been receiving increasing amounts of reactive nitrogen(N)over recent decades.External N inputs profoundly change microbially mediated soil carbon(C)dynamics,but how elev...Background:China’s terrestrial ecosystems have been receiving increasing amounts of reactive nitrogen(N)over recent decades.External N inputs profoundly change microbially mediated soil carbon(C)dynamics,but how elevated N affects the soil organic C that is derived from microbial residues is not fully understood.Here,we evaluated the changes in soil microbial necromass C under N addition at 11 forest,grassland,and cropland sites over China’s terrestrial ecosystems through a meta-analysis based on available data from published articles.Results:Microbial necromass C accounted for an average of 49.5%of the total soil organic C across the studied sites,with higher values observed in croplands(53.0%)and lower values in forests(38.6%).Microbial necromass C was significantly increased by 9.5%after N addition,regardless of N forms,with greater stimulation observed for fungal(+11.2%)than bacterial(+4.5%)necromass C.This increase in microbial necromass C under elevated N was greater under longer experimental periods but showed little variation among different N application rates.The stimulation of soil microbial necromass C under elevated N was proportional to the change in soil organic C.Conclusions:The stimulation of microbial residues after biomass turnover is an important pathway for the observed increase in soil organic C under N deposition across China’s terrestrial ecosystems.展开更多
Neodymium oxyfluoride has received much attention in the fields of anionic solid electrolytes.luminescent,catalytic and magnetic materials because of its structure combined advantages of rareearth cations with F^(-)an...Neodymium oxyfluoride has received much attention in the fields of anionic solid electrolytes.luminescent,catalytic and magnetic materials because of its structure combined advantages of rareearth cations with F^(-)and O_(2)^(-)anions.In this work,neodynium oxyfluoride was synthesized by the reaction between neodymium oxide and four fluoride media with different fluoride ion activities.The synthesis processes in molten LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),NaF-CaF_(2)-NdF_(3)and NaF-KF-NdF_(3)are observed in situ by a confocal scanning laser microscope.The expansion of neodymium oxide particle is observed in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts,and the growth of needle crystals on neodymium oxide particle is clearly observed in molten NaF-CaF_(2)-NdF_(3).Based on scanning electron microscopy(SEM)-energy dispersive X-ray spectroscopy(EDS)and X-ray diffraction(XRD)analyses of products,neodynium oxyfluoride was successfully synthesized in the four fluoride media.The neodynium oxyfluoride generated in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts is a tetragonal structure.However,in molten NaF-CaF_(2)-NdF_(3),neodynium oxyfluoride with a rhombohedral structure is formed.It is suggested that the substitution of Na(Ⅰ)and Ca(Ⅱ)for Nd(Ⅲ)can transform NdOF from tetragonal structure to rhombohedral structure.The growth rate of needle crystals generated in molten NaF-CaF_(2)-NdF_(3)was calculated based on the result of a confocal scanning laser microscope,and it is found that the reaction kinetics of crystal formation is zero-order reaction.The effect of fluoride media on the structure and morphology of formed NdOF were evaluated by XRD,X-ray photoelectron spectroscopy(XPS)and SEM.The neodymium oxyfluoride prepared in the fluoride media with high fluoride ion activity has low binding energy of F 1 s.The ratio of adsorbed oxygen to lattice oxygen for neodymium oxyfluoride prepared in molten LiF-NdF_(3)is larger than those in the other three fluoride media,so it can have better catalytic performance.展开更多
Ultrafine NdFeB waste is a relatively clean waste produced during NdFeB magnet processing.Fluorinecontaining wastewater is a common type of industrial wastewater,such as stainless steel pickling wastewater.In this wor...Ultrafine NdFeB waste is a relatively clean waste produced during NdFeB magnet processing.Fluorinecontaining wastewater is a common type of industrial wastewater,such as stainless steel pickling wastewater.In this work,rare earth element neodynium was recycled from ultrafine NdFeB waste by capturing fluorine ions in the fluorine-containing wastewater and prepared into neodynium oxyfluoride.The reaction process was investigated through UV-Vis-NIR,thermogravimetry/differential thermogravimetry(TG/DTG),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The neodymium hydroxide in the ultrafine NdFeB waste reacted with fluorine ions to form Nd(OH)_(2) F,and Nd(OH)_(2) F was then transformed into neodymium oxyfluoride after decomposition.The formed neodymium oxyfluoride is found to be particles with rhombohedral structure and a particle size of around 50 nm.The reaction kinetics of forming Nd(OH)_(2) F was investigated.The reaction kinetic equation was established and the reaction activation energy was calculated.The effect of fluorine ion concentration on the reaction rate and products was evaluated.The results show that the reaction rate increases with the increase of fluorine ion concentration in the range of 0.01-1.5 mol/L,but it has little effect.In addition,the fluorine ion concentration affects the crystallinity of formed neodymium oxyfluoride.The recycling process not only realizes the sustainable utilization of rare earths,but also reduces the concentration of fluorine ions in the fluorine-containing wastewater,achieving two goals with one stone.展开更多
A numerical framework was proposed for the seismic analysis of underground structures in layered ground under inclined P-SV waves.The free-field responses are first obtained using the stiffness matrix method based on ...A numerical framework was proposed for the seismic analysis of underground structures in layered ground under inclined P-SV waves.The free-field responses are first obtained using the stiffness matrix method based on plane-wave assumptions.Then,the domain reduction method was employed to reproduce the wavefield in the numerical model of the soil–structure system.The proposed numerical framework was verified by providing comparisons with analytical solutions for cases involving free-field responses of homogeneous ground,layered ground,and pressure-dependent heterogeneous ground,as well as for an example of a soil–structure interaction simulation.Compared with the viscous and viscous-spring boundary methods adopted in previous studies,the proposed framework exhibits the advantage of incorporating oblique incident waves in a nonlinear heterogeneous ground.Numerical results show that SV-waves are more destructive to underground structures than P-waves,and the responses of underground structures are significantly affected by the incident angles.展开更多
基金financed by the National Natural Science Foundation of China(No.31370615 and 31130013)National Key Basic Research Program of China(2014CB954003)
文摘Prescribed fire has now become the usual management practice in the Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） plantation in southern China. Heat generated during fire may affect carbon （C） dynam- ics in soils. We investigated the microbial biomass C （MBC） and microbial respiration in two Chinese fir forest soils （one is not exposed to fire for the past 88 years, and the other is recently exposed to prescribed fire） after soil heating （100 and 200 ℃） under three moisture regimes [25, 50 and 75 % of water holding capacity （WHC）]. For both soils, significant reduction in MBC with increasing heating temperature was found. Soils without exposing to fire previously had significantly greater MBC concentra- tion than the fire-exposed soils when heated at 100 or 200 ℃. Lower soil water content resulted in higher MBC concentrations in both soils. In contrast, both soils had the highest soil microbial respiration rate at 50 % WHC. Soils without exposing to fire previously had the greatest microbial respiration rates at 200 ℃, while the fire-ex- posed soils when heated at 100 ℃ had greatest microbialrespiration rates. During 14-days post-heat incubation, soil MBC in both soils was greatest after heating at 200 ℃ and 25 % WHC. However, soil previously exposed to fire had the lowest CO2 evolution when incubated at 25 % WHC.
基金financially supported by the National Key Research and Development Program of China(no.2016YFB0100200)Beijing Municipal Science and Technology Project(no.Z181100004518001)。
文摘To address the corrosion and dendrite issues of lithium metal anodes, a protective layer was ex-situ constructed by P4S10 modification. It was determined by X-ray photoelectron spectroscopy and Raman spectra that the main constituents of the protective layer were P4S10, Li3PS4 and other LixPySztype derivatives. The protective layer was proved to be effective to stabilize the interphase of lithium metal. With the modified Li anodes, symmetric cells could deliver stable Li plating/stripping for 16000 h;Li–S batteries exhibited a specific capacity of 520 m A h g-1 after 200 cycles at 1000 m A g-1 with average Coulombic efficiency of 97.9%. Therefore, introducing LixPySzbased layer to protect Li anode provides a new strategy for the improvement of Li metal batteries.
基金the National Natural Science Foundation of China(No:21703285)。
文摘Various nanostructured architectures have been demonstrated to be effective to address the issues of high capacity Si anodes. However, the scale-up of these nano-Si materials is still a critical obstacle for commercialization. Herein, we use industrial ferrosilicon as low-cost Si source and introduce a facile and scalable method to fabricate a micrometer-sized ferrosilicon/C composite anode, in which ferrosilicon microparticles are wrapped with multi-layered carbon nanosheets. The multi-layered carbon nanosheets could effectively buffer the volume variation of Si as well as create an abundant and reliable conductivity framework, ensuring fast transport of electrons. As a result, the micrometer-sized ferrosilicon/C anode achieves a stable cycling with 805.9 m Ah g-1 over 200 cycles at 500 mA g-1 and a good rate capability of455.6 mAh g-1 at 10 A g-1. Therefore, our approach based on ferrosilicon provides a new opportunity in fabricating cost-effective, pollution-free, and large-scale Si electrode materials for high energy lithium-ion batteries.
基金supported by National Forestry Public Welfare Foundation of China(201304205)National Science Foundation of China(31470578 and 31200363)+2 种基金Fujian Provincial Department of S&T Project(2016Y0083,2013YZ0001-1,2014J05044 and 2015Y0083)Xiamen Municipal Department of Science and Technology(3502Z20130037 and 3502Z20142016)Youth Innovation Promotion Association CAS
文摘Mid-subtropical forests are the main vegetation type of global terrestrial biomes, and are critical for maintaining the global carbon balance. However, estimates of forest biomass increment in mid-subtropical forests remain highly uncertain. It is critically important to determine the relative importance of different biotic and abiotic factors between plants and soil, particularly with respect to their influence on plant regrowth. Consequently,it is necessary to quantitatively characterize the dynamicspatiotemporal distribution of forest carbon sinks at a regional scale. This study used a large, long-term dataset in a boosted regression tree（BRT） model to determine the major components that quantitatively control forest biomass increments in a mid-subtropical forested region（Wuyishan National Nature Reserve, China）. Long-term,stand-level data were used to derive the forest biomass increment, with the BRT model being applied to quantify the relative contributions of various biotic and abiotic variables to forest biomass increment. Our data show that total biomass（t） increased from 4.62 9 106 to 5.30 9 106 t between 1988 and 2010, and that the mean biomass increased from 80.19 ± 0.39 t ha-1（mean ± standard error） to 94.33 ± 0.41 t ha-1in the study region. The major factors that controlled biomass（in decreasing order of importance） were the stand, topography, and soil. Stand density was initially the most important stand factor, while elevation was the most important topographic factor. Soil factors were important for forest biomass increment but have a much weaker influence compared to the other two controlling factors. These results provide baseline information about the practical utility of spatial interpolationmethods for mapping forest biomass increments at regional scales.
基金Supported by the National Basic Research Program(973 Program)of China(2010CB227201)the State Key Program of National Natural Science of China(21236003)+2 种基金the National Natural Science Foundation of China(21476022)the Fundamental Research Funds for the Central Universities(JD1515 and YS1406)Beijing Higher Education Young Elite Teacher Project(YETP0509)
文摘An investigation was performed on the suitability of carbon materials, metallic lead and its alloys as substrates for zinc negative electrode in acid PbO2-Zn single flow batteries. The zinc deposition process was carried out in the mediumofl mol.L 1H2SO4 at room temperature. No maximum current appears on the potentiostatic current transients for the zinc deposition on lead and its alloys. With increasing overpotential, the progressive nucleation turns to be a 3D-instantaneous nucleation process for the resin-graphite composite. Hydrogen evolution on the graphite composite is effectively suppressed with the doping of a polymer resin. The hydrogen evolution reaction on the lead is relatively weak, while on the lead alloys, it becomes serious to a certain degree. Although the ex- change current density of zinc deposition and dissolution process on the graphite composite is relatively low, the zinc corrosion is weakened to a great extent. With the increase of deposition time, zinc deposits are more compact. The cyclings of zinc galvanostatic charge-discharge on the graphite composite provide more than 90% of coulombic and 80% of energy efficiencies, and exhibit superior cycling stability during the first 10 cycles.
基金This research was financially supported by the National Natural Science Foundation of China(31922052,31800373,32022056 and 31800521).
文摘Aims Biomass allocation to different organs is a fundamental plant ecophysiological process to better respond to changing environments;yet,it remains poorly understood how patterns of biomass allocation respond to nitrogen(N)additions across terrestrial ecosystems worldwide.Methods We conducted a meta-analysis using 5474 pairwise observations from 333 articles to assess how N addition affected plant biomass and biomass allocation among different organs.We also tested the'ratio-based optimal partitioning'vs.the'isometric allocation,hypotheses to explain potential N addition effects on biomass allocation.Important Findings We found that(i)N addition significantly increased whole plant biomass and the biomass of different organs,but decreased rootrshoot ratio(RS)and root mass fraction(RMF)while no effects of N addition on leaf mass fraction and stem mass fraction at the global scale;(ii)the effects of N addition on ratio-based biomass allocation were mediated by individual or interactive effects of moderator variables such as experimental conditions,plant functional types,latitudes and rates of N addition and(iii)N addition did not affect allometric relationships among different organs,suggesting that decreases in RS and RMF may result from isometric allocation patterns following increases in whole plant biomass.Despite alteration of ratio-based biomass allocation between root and shoot by N addition,the unaffected allometric scaling relationships among different organs(including root vs.shoot)suggest that plant biomass allocation patterns are more appropriately explained by the isometric allocation hypothesis rather than the optimal partitioning hypothesis.Our findings contribute to better understand N-induced effects on allometric relationships of terrestrial plants,and suggest that these ecophysiological responses should be incorporated into models that aim to predict how terrestrial ecosystems may respond to enhanced N deposition under future global change scenarios.
基金supported by the National Natural Science Foundation of China (Grant No.21173060)the Basic Research Foundation of Harbin Engineering University of China (No.HEUFT08030)
文摘This work presents a new method for preparation of samarium alloy. Using A1 rod as anode, electrochemical formation of Sm-A1 alloy on Mo electrode from Sm203 in LiC1- KC1-MgC12-KF molten salts was investigated. Samarium mainly exists in the form of A12Sm in Li-Mg matrix, and the concentration of Sm in this alloy runs up to be as high as 34.7%. The reaction of samarium preparation appears like a replacement reaction. The new preparation method makes possible a high samarium content in electrochemical deposition of Sm-A1 alloy. Using A1 rod as anode consumedly decreased, the electrolytic cell voltage, and facilitated Sm deposition from Sm203. This preparation method uses 8m203 as raw materials to gain samarium alloy directly, which could revolutionize the industrial production of samarium alloys.
基金financially supported by High Technology Research and Development Program of China(No.2011AA03A409)the National Natural Science Foundation of China(Nos.21173060 and 21271054)+1 种基金the Major Research Plan of the National Natural Science Foundation of China(No.91226201)the Fundamental Research Funds for the Central Universities(No.HEUCF201310012)
文摘The electrochemical behavior of Mg, Li, AI and Er were investigated by electrochemical techniques in LiCI- KCI-MgCI2-AICI3-ErCI3 melts at 823 K. The cyclic voltammetry and chronopotentiometry indicated that the co-reduction of Mg, Li, AI and Er occurs at current densities more negative than -0.89 A.cm-2. Er（lll） under-potential deposited on pre-reduced AI electrode formed AI-RE alloys. X-ray diffraction （XRD） results indicated that Mg17Al12, Al2Er, Al2Er3 and Al4Li9 phases were prepared by galvanostatic electrolysis. ICP analyses of samples showed that lithium and aluminum contents of Mg-Li-AI-Er alloys could be controlled by concentration of AICI3 and cathodic current density.
基金supported by the President Foundation of Nanfang Hospital,Southern Medical University(2020C024)the Natural Science Foundation of Fujian Province(2021J011156).
文摘Over the years,electroconductive hydrogels(ECHs)have been extensively applied for stimulating nerve regeneration and restoring locomotor function after peripheral nerve injury(PNI)with diabetes,given their favorable mechanical and electrical properties identical to endogenous nerve tissue.Nevertheless,PNI causes the loss of locomotor function and inflammatory pain,especially in diabetic patients.It has been established that bone marrow stem cells-derived exosomes(BMSCs-Exos)have analgesic,anti-inflammatory and tissue regeneration properties.Herein,we designed an ECH loaded with BMSCs-Exos(ECH-Exos)electroconductive nerve dressing to treat diabetic PNI to achieve functional recovery and pain relief.Given its potent adhesive and self-healing properties,this laminar dressing is convenient for the treatment of damaged nerve fibers by automatically wrapping around them to form a size-matched tube-like structure,avoiding the cumbersome implantation process.Our in vitro studies showed that ECH-Exos could facilitate the attachment and migration of Schwann cells.Meanwhile,Exos in this system could modulate M2 macrophage polarization via the NF-κB pathway,thereby attenuating inflammatory pain in diabetic PNI.Additionally,ECH-Exos enhanced myelinated axonal regeneration via the MEK/ERK pathway in vitro and in vivo,consequently ameliorating muscle denervation atrophy and further promoting functional restoration.Our findings suggest that the ECH-Exos system has huge prospects for nerve regeneration,functional restoration and pain relief in patients with diabetic PNI.
基金This work was supported by the Guangzhou Science and Technology Program Key Projects(No.202002020001)Science and Technology Planning Project of Guangdong Province(No.2020A0505100039)+1 种基金Autonomous region science and technology branch Xinjiang project plan(No.2022E02040)Clinical Key Specialty in Ningde City,Fujian Province.
文摘At present,effective fixation and anti-infection implant materials represent the mainstay for the treatment of open fractures.However,external fixation can cause nail tract infections and is ineffective for fixing small fracture fragments.Moreover,closed reduction and internal fixation during the early stage of injury can lead to potential bone infection,conducive to bone nonunion and delayed healing.Herein,we designed a bone adhesive with anti-infection,osteogenic and bone adhesion fixation properties to promote reduction and fixation of open fractures and subsequent soft tissue repair.It was prepared by the reaction of gelatin(Gel)and oxidized starch(OS)with vancomycin(VAN)-loaded mesoporous bioactive glass nanoparticles(MBGNs)covalently cross-linked with Schiff bases.Characterization and adhesion experiments were conducted to validate the successful preparation of the Gel-OS/VAN@MBGNs(GOVM-gel)adhesive.Meanwhile,in vitro cell experiments demonstrated its good antibacterial effects with the ability to stimulate bone marrow mesenchymal stem cell(BMSCs)proliferation,upregulate the expression of alkaline phosphatase(ALP)and osteogenic proteins(RunX2 and OPN)and enhance the deposition of calcium nodules.Additionally,we established a rat skull fracture model and a subcutaneous infection model.The histological analysis showed that bone adhesive enhanced osteogenesis,and in vivo experiments demonstrated that the number of inflammatory cells and bacteria was significantly reduced.Overall,the adhesive could promote early reduction of fractures and antibacterial and osteogenic effects,providing the foothold for treatment of this patient population.
基金The National Natural Science Foundation of China(31800521,32022056,31800373,and 31922052).
文摘Background:China’s terrestrial ecosystems have been receiving increasing amounts of reactive nitrogen(N)over recent decades.External N inputs profoundly change microbially mediated soil carbon(C)dynamics,but how elevated N affects the soil organic C that is derived from microbial residues is not fully understood.Here,we evaluated the changes in soil microbial necromass C under N addition at 11 forest,grassland,and cropland sites over China’s terrestrial ecosystems through a meta-analysis based on available data from published articles.Results:Microbial necromass C accounted for an average of 49.5%of the total soil organic C across the studied sites,with higher values observed in croplands(53.0%)and lower values in forests(38.6%).Microbial necromass C was significantly increased by 9.5%after N addition,regardless of N forms,with greater stimulation observed for fungal(+11.2%)than bacterial(+4.5%)necromass C.This increase in microbial necromass C under elevated N was greater under longer experimental periods but showed little variation among different N application rates.The stimulation of soil microbial necromass C under elevated N was proportional to the change in soil organic C.Conclusions:The stimulation of microbial residues after biomass turnover is an important pathway for the observed increase in soil organic C under N deposition across China’s terrestrial ecosystems.
基金Project supported by National Key Research and Development Program of China(2020YFC1909102)Natural Science Foundation of Inner Mongolia(2020BS05033)+1 种基金Inner Mongolia Major Basic Research Open Project(0406091701)Major Projects of Natural Science Foundation of Inner Mongolia of China(2018ZD07)。
文摘Neodymium oxyfluoride has received much attention in the fields of anionic solid electrolytes.luminescent,catalytic and magnetic materials because of its structure combined advantages of rareearth cations with F^(-)and O_(2)^(-)anions.In this work,neodynium oxyfluoride was synthesized by the reaction between neodymium oxide and four fluoride media with different fluoride ion activities.The synthesis processes in molten LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),NaF-CaF_(2)-NdF_(3)and NaF-KF-NdF_(3)are observed in situ by a confocal scanning laser microscope.The expansion of neodymium oxide particle is observed in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts,and the growth of needle crystals on neodymium oxide particle is clearly observed in molten NaF-CaF_(2)-NdF_(3).Based on scanning electron microscopy(SEM)-energy dispersive X-ray spectroscopy(EDS)and X-ray diffraction(XRD)analyses of products,neodynium oxyfluoride was successfully synthesized in the four fluoride media.The neodynium oxyfluoride generated in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts is a tetragonal structure.However,in molten NaF-CaF_(2)-NdF_(3),neodynium oxyfluoride with a rhombohedral structure is formed.It is suggested that the substitution of Na(Ⅰ)and Ca(Ⅱ)for Nd(Ⅲ)can transform NdOF from tetragonal structure to rhombohedral structure.The growth rate of needle crystals generated in molten NaF-CaF_(2)-NdF_(3)was calculated based on the result of a confocal scanning laser microscope,and it is found that the reaction kinetics of crystal formation is zero-order reaction.The effect of fluoride media on the structure and morphology of formed NdOF were evaluated by XRD,X-ray photoelectron spectroscopy(XPS)and SEM.The neodymium oxyfluoride prepared in the fluoride media with high fluoride ion activity has low binding energy of F 1 s.The ratio of adsorbed oxygen to lattice oxygen for neodymium oxyfluoride prepared in molten LiF-NdF_(3)is larger than those in the other three fluoride media,so it can have better catalytic performance.
基金Project supported by the Natural Science Foundation of Inner Mongolia(2020BS05033,2020MS05012)Inner Mongolia Major Basic Research Open Project(0406091701)。
文摘Ultrafine NdFeB waste is a relatively clean waste produced during NdFeB magnet processing.Fluorinecontaining wastewater is a common type of industrial wastewater,such as stainless steel pickling wastewater.In this work,rare earth element neodynium was recycled from ultrafine NdFeB waste by capturing fluorine ions in the fluorine-containing wastewater and prepared into neodynium oxyfluoride.The reaction process was investigated through UV-Vis-NIR,thermogravimetry/differential thermogravimetry(TG/DTG),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The neodymium hydroxide in the ultrafine NdFeB waste reacted with fluorine ions to form Nd(OH)_(2) F,and Nd(OH)_(2) F was then transformed into neodymium oxyfluoride after decomposition.The formed neodymium oxyfluoride is found to be particles with rhombohedral structure and a particle size of around 50 nm.The reaction kinetics of forming Nd(OH)_(2) F was investigated.The reaction kinetic equation was established and the reaction activation energy was calculated.The effect of fluorine ion concentration on the reaction rate and products was evaluated.The results show that the reaction rate increases with the increase of fluorine ion concentration in the range of 0.01-1.5 mol/L,but it has little effect.In addition,the fluorine ion concentration affects the crystallinity of formed neodymium oxyfluoride.The recycling process not only realizes the sustainable utilization of rare earths,but also reduces the concentration of fluorine ions in the fluorine-containing wastewater,achieving two goals with one stone.
基金supported by the National Natural Science Foundation of China(Grant Nos.41922059,42177134,and 51778487)Fundamental Research Funds for the Central Universities,CHD(300102262506)Top Discipline Plan of Shanghai Universities-Class I.
文摘A numerical framework was proposed for the seismic analysis of underground structures in layered ground under inclined P-SV waves.The free-field responses are first obtained using the stiffness matrix method based on plane-wave assumptions.Then,the domain reduction method was employed to reproduce the wavefield in the numerical model of the soil–structure system.The proposed numerical framework was verified by providing comparisons with analytical solutions for cases involving free-field responses of homogeneous ground,layered ground,and pressure-dependent heterogeneous ground,as well as for an example of a soil–structure interaction simulation.Compared with the viscous and viscous-spring boundary methods adopted in previous studies,the proposed framework exhibits the advantage of incorporating oblique incident waves in a nonlinear heterogeneous ground.Numerical results show that SV-waves are more destructive to underground structures than P-waves,and the responses of underground structures are significantly affected by the incident angles.
