Over the past four years, the field of the innate immune response has been highly influenced by the discovery of the IKB kinase (IKK)-related kinases, TANK Binding Kinase I (TBK1) and IKKi, which regulate the acti...Over the past four years, the field of the innate immune response has been highly influenced by the discovery of the IKB kinase (IKK)-related kinases, TANK Binding Kinase I (TBK1) and IKKi, which regulate the activity of interferon regulatory factor (IRF)-3/IRF-7 and NF-κB transcription factors. More recently, additional essential components of the signaling pathways that activate these IKK homologues have been discovered. These include the RNA helicases RIGi and MDA5, and the downstream mitochondrial effector known as CARDIF/MAVS/VISA/IPS-1. In addition to their essential functions in controlling the innate immune response, recent studies have highlighted a role of these kinases in cell proliferation and oncogenesis. The canonical IKKs are well recognized to be a bridge linking chronic inflammation to cancer. New findings now suggest that the IKK-related kinases TBK1 and IKKi also participate in signaling pathways that impact on cell transformation and tumor progression. This review will therefore summarize and discuss the role of TBK1 and IKKi in cellular transformation and oncogenesis by focusing on their regulation and substrate specificity.展开更多
Background: Nitrogen(N) deposition affects soil greenhouse gas(GHG) emissions, while biochar application reduces GHG emissions in agricultural soils. However, it remains unclear whether biochar amendment can alleviate...Background: Nitrogen(N) deposition affects soil greenhouse gas(GHG) emissions, while biochar application reduces GHG emissions in agricultural soils. However, it remains unclear whether biochar amendment can alleviate the promoting effects of N input on GHG emissions in forest soils. Here, we quantify the separate and combined effects of biochar amendment(0, 20, and 40 t·ha) and N addition(0, 30, 60, and 90 kg N·ha·yr) on soil GHG fluxes in a long-term field experiment at a Moso bamboo(Phyllostachys edulis) plantation.Results: Low and moderate N inputs(≤60 kg N·ha·yr) significantly increase mean annual soil carbon dioxide(CO) and nitrous oxide(NO) emissions by 17.0%–25.4% and 29.8%–31.2%, respectively, while decreasing methane(CH) uptake by 12.4%–15.9%, leading to increases in the global warming potential(GWP) of soil CHand NO fluxes by 32.4%–44.0%. Moreover, N addition reduces soil organic carbon(C;SOC) storage by 0.2%–6.5%. Compared to the control treatment, biochar amendment increases mean annual soil CO2emissions, CHuptake, and SOC storage by 18.4%–25.4%, 7.6%–15.8%, and 7.1%–13.4%, respectively, while decreasing NO emissions by 17.6%–19.2%, leading to a GWP decrease of 18.4%–21.4%. Biochar amendments significantly enhance the promoting effects of N addition on soil COemissions, while substantially offsetting the promotion of N2O emissions, inhibition of CHuptake, and decreased SOC storage, resulting in a GWP decrease of 9.1%–30.3%.Additionally, soil COand CHfluxes are significantly and positively correlated with soil microbial biomass C(MBC) and pH. Meanwhile, NO emissions have a significant and positive correlation with soil MBC and a negative correlation with pH.Conclusions: Biochar amendment can increase SOC storage and offset the enhanced GWP mediated by elevated N deposition and is, thus, a potential strategy for increasing soil C sinks and decreasing GWPs of soil CHand NO under increasing atmospheric N deposition in Moso bamboo plantations.展开更多
Background:It is still not clear whether the effects of N deposition on soil greenhouse gas(GHG)emissions are influenced by plantation management schemes.A field experiment was conducted to investigate the effects of ...Background:It is still not clear whether the effects of N deposition on soil greenhouse gas(GHG)emissions are influenced by plantation management schemes.A field experiment was conducted to investigate the effects of conventional management(CM)versus intensive management(IM),in combination with simulated N deposition levels of control(ambient N deposition),30 kg N·ha^(−1)·year^(−1)(N30,ambient+30 kg N·ha^(−1)·year^(−1)),60 kg N·ha^(−1)·year^(−1)(N60,ambient+60 kg N·ha^(−1)·year^(−1)),or 90 kg N·ha^(−1)·year^(−1)(N90,ambient+90 kg N·ha^(−1)·year^(−1))on soil CO_(2),CH_(4),and N_(2)O fluxes.For this,24 plots were set up in a Moso bamboo(Phyllostachys edulis)plantation from January 2013 to December 2015.Gas samples were collected monthly from January 2015 to December 2015.Results:Compared with CM,IM significantly increased soil CO_(2) emissions and their temperature sensitivity(Q_(10))but had no significant effects on soil CH_(4) uptake or N_(2)O emissions.In the CM plots,N30 and N60 significantly increased soil CO_(2) emissions,while N60 and N90 significantly increased soil N_(2)O emissions.In the IM plots,N30 and N60 significantly increased soil CO_(2) and N_(2)O emissions,while N60 and N90 significantly decreased soil CH_(4) uptake.Overall,in both CM and IM plots,N30 and N60 significantly increased global warming potentials,whereas N90 did not significantly affect global warming potential.However,N addition significantly decreased the Q_(10) value of soil CO_(2) emissions under IM but not under CM.Soil microbial biomass carbon was significantly and positively correlated with soil CO_(2) and N_(2)O emissions but significantly and negatively correlated with soil CH_(4) uptake.Conclusion:Our results indicate that management scheme effects should be considered when assessing the effect of atmospheric N deposition on GHG emissions in bamboo plantations.展开更多
Human impacts on Earth's ecosystems have greatly intensified in the last decades. This is reflected in unexpected disturbance events, as well as new and increasing socio-economic demands, all of which are affectin...Human impacts on Earth's ecosystems have greatly intensified in the last decades. This is reflected in unexpected disturbance events, as well as new and increasing socio-economic demands, all of which are affecting the resilience of forest ecosystems worldwide and the provision of important ecosystem services. This Anthropocene era is forcing us to reconsider past and current forest management and silvicultural practices, and search for new ones that are more flexible and better at dealing with the increasing uncertainty brought about by these accelerating and cumulative global changes. Here, we briefly review the focus and limitations of past and current forest management and silvicultural practices mainly as developed in Europe and North America. We then discuss some recent promising concepts, such as managing forests as complex adaptive systems, and approaches based on resilience, functional diversity, assisted migration and multi-species plantations, to propose a novel approach to integrate the functionality of species-traits into a functional complex network approach as a flexible and multi-scale way to manage forests for the Anthropocene. This approach takes into consideration the high level of uncertainty associated with future environmental and societal changes. It relies on the quantification and dynamic monitoring of functional diversity and complex network indices to manage forests as a functional complex network. Using this novel approach, the most efficient forest management and silvicultural practices can be determined, as well as where, at what scale, and at what intensity landscape-scale resistance, resilience and adaptive capacity of forests to global changes can be improved.展开更多
Although there has been significant progress in the seismic imaging of mantle heterogeneity, the outstanding issue that remains to be resolved is the unknown distribution of mantle temperature anomalies in the distant...Although there has been significant progress in the seismic imaging of mantle heterogeneity, the outstanding issue that remains to be resolved is the unknown distribution of mantle temperature anomalies in the distant geological past that give rise to the present-day anomalies inferred by global tomography models. To address this question, we present 3-D convection models in compressible and self-gravitating mantle initialised by different hypothetical temperature patterns. A notable feature of our forward convection modelling is the use of self-consistent coupling of the motion of surface tectonic plates to the underlying mantle flow, without imposing prescribed surface velocities (i.e., p/ate-like boundary condition). As an approximation for the surface mechanical conditions before plate tectonics began to operate we employ the no-slip (rigid) boundary condition. A rigid boundary condition dem- onstrates that the initial thermally-dominated structure is preserved, and its geographical location is fixed during the evolution of mantle flow. Considering the impact of different assumed surface boundary conditions (rigid and plate-like) on the evolution of thermal heterogeneity in the mantle we suggest that the intrinsic buoyancy of seven superplumes is most-likely resolved in the tomographic images of present-day mantle thermal structure. Our convection simulations with a plate-like boundary condition reveal that the evolution of an initial cold anomaly beneath the Java-lndonesian trench system yields a long-term, stable pattern of thermal heterogeneity in the lowermost mantle that resembles the present- day Large Low Shear Velocity Provinces (LLSVPs), especially below the Pacific. The evolution of sub- duction zones may be, however, influenced by the mantle-wide flow driven by deeply-rooted and long- lived superplumes since Archean times. These convection models also detect the intrinsic buoyancy of the Perm Anomaly that has been identified as a unique slow feature distinct from the two principal LLSVPs. We find there is no need for dense chemical 'piles' in the lower mantle to generate a stable distribution of temperature anomalies that are correlated to the LLSVPs and the Perm Anomaly. Our tomography-based convection simulations also demonstrate that intraplate volcanism in the south-east Pacific may be interpreted in terms of shallow small-scale convection triggered by a superplume beneath the East Pacific Rise.展开更多
The development of allometric biomass models is important process in biomass estimation because the reliability of forest biomass and carbon estimations largely depends on the accuracy and precision of such models.Nat...The development of allometric biomass models is important process in biomass estimation because the reliability of forest biomass and carbon estimations largely depends on the accuracy and precision of such models.National Forest Inventories(NFI)are detailed assessments of forest resources at national and regional levels that provide valuable data for forest biomass estimation.However,the lack of biomass allometric equations for each tree species in the NFI currently hampers the estimation of national-scale forest biomass.The main objective of this study was to develop allometric biomass regression equations for each tree species in the NFI of China based on limited biomass observations.These equations optimally grouped NFI and biomass observation species according to their phylogenetic relationships.Significant phylogenetic signals demonstrated phylogenetic conservation of the crown-to-stem biomass ratio.Based on phylogenetic relationships,we grouped and matched NFI and biomass observation species into 22 categories.Allometric biomass regression models were developed for each of these 22 species categories,and the models performed successfully(R^(2)=0.97,root mean square error(RMSE)=12.9t·ha^(–1),relative RMSE=11.5%).Furthermore,we found that phylogeny-based models performed more effectively than wood density-based models.The results suggest that grouping species based on their phylogenetic relationships is a reliable approach for the development and selection of accurate allometric equations.展开更多
A simple method for the fabrication of ultrathin films containing low molecular weight dye material is introduced(post-adsorption technique). The chromophore used is 4-nitro-4'-decyloxy azobenzene quaternary ammon...A simple method for the fabrication of ultrathin films containing low molecular weight dye material is introduced(post-adsorption technique). The chromophore used is 4-nitro-4'-decyloxy azobenzene quaternary ammonium salt (azo-10Q).In classical layer-by-layer (LBL) procedures, where the substrate is dipped alternately into the chromophore solution and thecomplementary polyelectrolyte, the chromophore tends to desorb from the film during subsequent immersion in thepolyanion solution, and there is little or no indication of multilayer growth. The extent of desorption depends somewhat onthe selection of polyelectrolyte, the ionic strength and the pH of solution. An alternative approach is to first prepareconventional LBL films from a pair of oppositely charged polyelectrolytes, and then to soak this film into the chromophoresolution, where adsorption by penetration into the LBL film may take place. In preliminary results, a linear dependence ofUV absorbance on layer number of LBL film thus prepared was found, demonstrating the apparent effectiveness of the post-adsorption technique for the preparation of azo-10Q-containing ultrathin films.展开更多
Over the past decade Sino-Russian cooperation in the Arctic has emerged as one of the major topics of the Russia-China negotiations on how to expand their comprehensive strategic partnership and to bring it to a new l...Over the past decade Sino-Russian cooperation in the Arctic has emerged as one of the major topics of the Russia-China negotiations on how to expand their comprehensive strategic partnership and to bring it to a new level. China considers the Arctic region important for its economic interests and desires to be included in the development of the region and its economic potential. For Russia, the Arctic is a future strategic resource base that would replace the old depleting fields and assure Russia’s status as a major worldwide energy supplier. Despite many joint statements on deepening of the Sino-Russian cooperation in the development of the Arctic energy resources, the concrete results of these ambitious plans are few. Some joint projects were dropped, as China and Russia could not agree on the conditions of the deal, others are progressing very slowly and have an uncertain future. In 2017, China has expanded its "Belt and Road Initiative"(BRI) to the Arctic thus elevating the Sino-Russian cooperation in the Artcic to a higher level. How did the relationship between Russia and China evolve in the Arctic and how do Russia and China view and respond to the new Arctic dimension of the BRI? What factors limit the strategic rapprochement between China and Russia in the Arctic?展开更多
Aminocaproic acid (ACA) mixed methanolic lead acetate-thiourea (PbAc-TU) complex as precursor for fabrication of lead sulphide (PbS) nanoparticles (NPs) has been explained. The size, structure and morphology of as-pre...Aminocaproic acid (ACA) mixed methanolic lead acetate-thiourea (PbAc-TU) complex as precursor for fabrication of lead sulphide (PbS) nanoparticles (NPs) has been explained. The size, structure and morphology of as-prepared ACA-capped PbS NPs were systematically characterized by scanning electron microscopy (SEM), Transmission electron mi-croscopy (TEM), X-ray diffraction (XRD), Uv-vis spectroscopy and Brunauer-Emmett-Teller (BET) techniques. The obtained results show that the synthesized PbS NPs are nanocrystalline, size quantized and their agglomeration shows a mesoporous network of 8.7 nm in pore size. The binding nature of ACA molecules on PbS surface was studied by thermo gravimetric analysis (TGA), Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) techniques. Results indicate that ACA acts as a soft template that restricts the growth of PbS NPs through its binding to Pb surface via nitrogen lone pair.展开更多
Aims Beta diversity is the variation in species composition among sites in a geographic region.Beta diversity is a key concept for understanding the functioning of ecosystems,for the conservation of biodiversity and f...Aims Beta diversity is the variation in species composition among sites in a geographic region.Beta diversity is a key concept for understanding the functioning of ecosystems,for the conservation of biodiversity and for ecosystem management.The present report describes how to analyse beta diversity from community composition and associated environmental and spatial data tables.Methods Beta diversity can be studied by computing diversity indices for each site and testing hypotheses about the factors that may explain the variation among sites.Alternatively,one can carry out a direct analysis of the community composition data table over the study sites,as a function of sets of environmental and spatial variables.These analyses are carried out by the statistical method of partitioning the variation of the diversity indices or the community composition data table with respect to environmental and spatial variables.Variation partitioning is briefly described herein.Important findings Variation partitioning is a method of choice for the interpretation of beta diversity using tables of environmental and spatial variables.Beta diversity is an interesting‘currency’for ecologists to compare either different sampling areas or different ecological communities cooccurring in an area.Partitioning must be based upon unbiased estimates of the variation of the community composition data table that is explained by the various tables of explanatory variables.The adjusted coefficient of determination provides such an unbiased estimate in both multiple regression and canonical redundancy analysis.After partitioning,one can test the significance of the fractions of interest and plot maps of the fitted values corresponding to these fractions.展开更多
Background:Changes in foliar nitrogen(N)and phosphorus(P)stoichiometry play important roles in predicting the efects of global change on ecosystem structure and function.However,there is substantial debate on the efec...Background:Changes in foliar nitrogen(N)and phosphorus(P)stoichiometry play important roles in predicting the efects of global change on ecosystem structure and function.However,there is substantial debate on the efects of P addition on foliar N and P stoichiometry,particularly under diferent levels of N addition.Thus,we conducted a global meta-analysis to investigate how N addition alters the efects of P addition on foliar N and P stoichiometry across different rates and durations of P addition and plant growth types based on more than 1150 observations.Results:We found that P addition without N addition increased foliar N concentrations,whereas P addition with N addition had no efect.The positive efects of P addition on foliar P concentrations were greater without N addition than with N addition.Additionally,the efects of P addition on foliar N,P and N:P ratios varied with the rate and duration of P addition.In particular,short-term or low-dose P addition with and without N addition increased foliar N concentration,and the positive efects of short-term or low-dose P addition on foliar P concentrations were greater without N addition than with N addition.The responses of foliar N and P stoichiometry of evergreen plants to P addition were greater without N addition than with N addition.Moreover,regardless of N addition,soil P availability was more efective than P resorption efciency in predicting the changes in foliar N and P stoichiometry in response to P addition.Conclusions:Our results highlight that increasing N deposition might alter the response of foliar N and P stoichiometry to P addition and demonstrate the important efect of the experimental environment on the results.These results advance our understanding of the response of plant nutrient use efciency to P addition with increasing N deposition.展开更多
Thermoresponsive core-shell microspheres are prepared and functionalized with 3-aminophenylboronic acid to make them responsive to glucose.The volume phase transition of the resulting particles is shifted to a lower t...Thermoresponsive core-shell microspheres are prepared and functionalized with 3-aminophenylboronic acid to make them responsive to glucose.The volume phase transition of the resulting particles is shifted to a lower temperature and a clear swelling is caused by the presence of glucose.The particles after the functionalization preserved their capability to form crystalline colloidal arrays.The changes of their properties may be used in the design of glucose sensors.展开更多
Despite great progress in data sharing that has been made in China in recent decades,cultural,policy,and technological challenges have prevented Chinese researchers from maximizing the availability of their data to th...Despite great progress in data sharing that has been made in China in recent decades,cultural,policy,and technological challenges have prevented Chinese researchers from maximizing the availability of their data to the global change science community.To achieve full and open exchange and sharing of scientific data,Chinese research funding agencies need to recognize that preserva-tion of,and access to,digital data are central to their mission,and must support these tasks accord-ingly.The Chinese government also needs to develop better mechanisms,incentives,and rewards,while scientists need to change their behavior and culture to recognize the need to maximize the usefulness of their data to society as well as to other researchers.The Chinese research communi-ty and individual researchers should think globally and act personally to promote a paradigm of open,free,and timely data sharing,and to increase the effectiveness of knowledge development.展开更多
New polyurethanes based on bile acids were synthesized from alcohol derivatives of cholic and lithocholic acids and hexamethylene diisocyanate, in an effort to improve the biocompatibility and biodegradability of poly...New polyurethanes based on bile acids were synthesized from alcohol derivatives of cholic and lithocholic acids and hexamethylene diisocyanate, in an effort to improve the biocompatibility and biodegradability of polyurethanes through the use of natural compounds. The hydrogen bonding in the polymers is confirmed by IR spectral analysis. The glass transition temperatures of the polymers are in the range of 82-138 ℃ and degradation temperatures in the range of 267-298 ℃ as studied by thermal analyses. Thermogravimetric studies indicate that the comonomers are of equimolar amounts in the polyurethanes derived from both bile acids.展开更多
Electronic and optical properties of materials are affected by atomic motion through the electron–phonon interaction:not only band gaps change with temperature,but even at absolute zero temperature,zero-point motion ...Electronic and optical properties of materials are affected by atomic motion through the electron–phonon interaction:not only band gaps change with temperature,but even at absolute zero temperature,zero-point motion causes band-gap renormalization.We present a large-scale first-principles evaluation of the zero-point renormalization of band edges beyond the adiabatic approximation.For materials with light elements,the band gap renormalization is often larger than 0.3 eV,and up to 0.7 eV.This effect cannot be ignored if accurate band gaps are sought.For infrared-active materials,global agreement with available experimental data is obtained only when non-adiabatic effects are taken into account.They even dominate zero-point renormalization for many materials,as shown by a generalized Fröhlich model that includes multiple phonon branches,anisotropic and degenerate electronic extrema,whose range of validity is established by comparison with first-principles results.展开更多
A strategy was developed for the synthesis of highly ordered 2D arrays of Ag-PNIPAM hybrid microgel. The highly ordered 2D arrays of PNIPAM microgel were prepared by dispersing PNIPAM microgel on a charge-reversible s...A strategy was developed for the synthesis of highly ordered 2D arrays of Ag-PNIPAM hybrid microgel. The highly ordered 2D arrays of PNIPAM microgel were prepared by dispersing PNIPAM microgel on a charge-reversible substrate. The microgel spheres self-assembled into a 3D colloidal crystal, and the first 111 plane was fixed in situ onto the substrate as a result of spontaneous charge reversal of the substrate, leaving a high-quality 2D array of PNIPAM microgel. Ag nanoparticles were then synthesized in situ inside the microgel spheres by introduction of Ag+ ions into the microgel spheres and reduction with sodium borohydride. The resulting 2D arrays are highly ordered. The inter-particle distance in the array can be tuned. In addition, the method allows the synthesis of large size arrays and the use of nonplanar substrate.展开更多
文摘Over the past four years, the field of the innate immune response has been highly influenced by the discovery of the IKB kinase (IKK)-related kinases, TANK Binding Kinase I (TBK1) and IKKi, which regulate the activity of interferon regulatory factor (IRF)-3/IRF-7 and NF-κB transcription factors. More recently, additional essential components of the signaling pathways that activate these IKK homologues have been discovered. These include the RNA helicases RIGi and MDA5, and the downstream mitochondrial effector known as CARDIF/MAVS/VISA/IPS-1. In addition to their essential functions in controlling the innate immune response, recent studies have highlighted a role of these kinases in cell proliferation and oncogenesis. The canonical IKKs are well recognized to be a bridge linking chronic inflammation to cancer. New findings now suggest that the IKK-related kinases TBK1 and IKKi also participate in signaling pathways that impact on cell transformation and tumor progression. This review will therefore summarize and discuss the role of TBK1 and IKKi in cellular transformation and oncogenesis by focusing on their regulation and substrate specificity.
基金sponsored by the National Natural Science Foundation of China,China(Grant Nos.31470529,32125027)Zhejiang A&F University Research and Development Fund,China(Nos.2022LFR006,2021LFR060).
文摘Background: Nitrogen(N) deposition affects soil greenhouse gas(GHG) emissions, while biochar application reduces GHG emissions in agricultural soils. However, it remains unclear whether biochar amendment can alleviate the promoting effects of N input on GHG emissions in forest soils. Here, we quantify the separate and combined effects of biochar amendment(0, 20, and 40 t·ha) and N addition(0, 30, 60, and 90 kg N·ha·yr) on soil GHG fluxes in a long-term field experiment at a Moso bamboo(Phyllostachys edulis) plantation.Results: Low and moderate N inputs(≤60 kg N·ha·yr) significantly increase mean annual soil carbon dioxide(CO) and nitrous oxide(NO) emissions by 17.0%–25.4% and 29.8%–31.2%, respectively, while decreasing methane(CH) uptake by 12.4%–15.9%, leading to increases in the global warming potential(GWP) of soil CHand NO fluxes by 32.4%–44.0%. Moreover, N addition reduces soil organic carbon(C;SOC) storage by 0.2%–6.5%. Compared to the control treatment, biochar amendment increases mean annual soil CO2emissions, CHuptake, and SOC storage by 18.4%–25.4%, 7.6%–15.8%, and 7.1%–13.4%, respectively, while decreasing NO emissions by 17.6%–19.2%, leading to a GWP decrease of 18.4%–21.4%. Biochar amendments significantly enhance the promoting effects of N addition on soil COemissions, while substantially offsetting the promotion of N2O emissions, inhibition of CHuptake, and decreased SOC storage, resulting in a GWP decrease of 9.1%–30.3%.Additionally, soil COand CHfluxes are significantly and positively correlated with soil microbial biomass C(MBC) and pH. Meanwhile, NO emissions have a significant and positive correlation with soil MBC and a negative correlation with pH.Conclusions: Biochar amendment can increase SOC storage and offset the enhanced GWP mediated by elevated N deposition and is, thus, a potential strategy for increasing soil C sinks and decreasing GWPs of soil CHand NO under increasing atmospheric N deposition in Moso bamboo plantations.
基金This study was funded by the National Natural Science Foundation of China(Grant Nos.31270517 and 31470529).
文摘Background:It is still not clear whether the effects of N deposition on soil greenhouse gas(GHG)emissions are influenced by plantation management schemes.A field experiment was conducted to investigate the effects of conventional management(CM)versus intensive management(IM),in combination with simulated N deposition levels of control(ambient N deposition),30 kg N·ha^(−1)·year^(−1)(N30,ambient+30 kg N·ha^(−1)·year^(−1)),60 kg N·ha^(−1)·year^(−1)(N60,ambient+60 kg N·ha^(−1)·year^(−1)),or 90 kg N·ha^(−1)·year^(−1)(N90,ambient+90 kg N·ha^(−1)·year^(−1))on soil CO_(2),CH_(4),and N_(2)O fluxes.For this,24 plots were set up in a Moso bamboo(Phyllostachys edulis)plantation from January 2013 to December 2015.Gas samples were collected monthly from January 2015 to December 2015.Results:Compared with CM,IM significantly increased soil CO_(2) emissions and their temperature sensitivity(Q_(10))but had no significant effects on soil CH_(4) uptake or N_(2)O emissions.In the CM plots,N30 and N60 significantly increased soil CO_(2) emissions,while N60 and N90 significantly increased soil N_(2)O emissions.In the IM plots,N30 and N60 significantly increased soil CO_(2) and N_(2)O emissions,while N60 and N90 significantly decreased soil CH_(4) uptake.Overall,in both CM and IM plots,N30 and N60 significantly increased global warming potentials,whereas N90 did not significantly affect global warming potential.However,N addition significantly decreased the Q_(10) value of soil CO_(2) emissions under IM but not under CM.Soil microbial biomass carbon was significantly and positively correlated with soil CO_(2) and N_(2)O emissions but significantly and negatively correlated with soil CH_(4) uptake.Conclusion:Our results indicate that management scheme effects should be considered when assessing the effect of atmospheric N deposition on GHG emissions in bamboo plantations.
基金provided in part by the Humboldt Foundation which provided money for an extensive stay in Germany to CM where part of the paper was writtenthe Swiss National Science Foundation through a post-doctoral fellowship to MM
文摘Human impacts on Earth's ecosystems have greatly intensified in the last decades. This is reflected in unexpected disturbance events, as well as new and increasing socio-economic demands, all of which are affecting the resilience of forest ecosystems worldwide and the provision of important ecosystem services. This Anthropocene era is forcing us to reconsider past and current forest management and silvicultural practices, and search for new ones that are more flexible and better at dealing with the increasing uncertainty brought about by these accelerating and cumulative global changes. Here, we briefly review the focus and limitations of past and current forest management and silvicultural practices mainly as developed in Europe and North America. We then discuss some recent promising concepts, such as managing forests as complex adaptive systems, and approaches based on resilience, functional diversity, assisted migration and multi-species plantations, to propose a novel approach to integrate the functionality of species-traits into a functional complex network approach as a flexible and multi-scale way to manage forests for the Anthropocene. This approach takes into consideration the high level of uncertainty associated with future environmental and societal changes. It relies on the quantification and dynamic monitoring of functional diversity and complex network indices to manage forests as a functional complex network. Using this novel approach, the most efficient forest management and silvicultural practices can be determined, as well as where, at what scale, and at what intensity landscape-scale resistance, resilience and adaptive capacity of forests to global changes can be improved.
基金provided by the Natural Sciences and Engineering Research Council of Canadathe Canadian Institute for Advanced Research(Earth System Evolution Program)
文摘Although there has been significant progress in the seismic imaging of mantle heterogeneity, the outstanding issue that remains to be resolved is the unknown distribution of mantle temperature anomalies in the distant geological past that give rise to the present-day anomalies inferred by global tomography models. To address this question, we present 3-D convection models in compressible and self-gravitating mantle initialised by different hypothetical temperature patterns. A notable feature of our forward convection modelling is the use of self-consistent coupling of the motion of surface tectonic plates to the underlying mantle flow, without imposing prescribed surface velocities (i.e., p/ate-like boundary condition). As an approximation for the surface mechanical conditions before plate tectonics began to operate we employ the no-slip (rigid) boundary condition. A rigid boundary condition dem- onstrates that the initial thermally-dominated structure is preserved, and its geographical location is fixed during the evolution of mantle flow. Considering the impact of different assumed surface boundary conditions (rigid and plate-like) on the evolution of thermal heterogeneity in the mantle we suggest that the intrinsic buoyancy of seven superplumes is most-likely resolved in the tomographic images of present-day mantle thermal structure. Our convection simulations with a plate-like boundary condition reveal that the evolution of an initial cold anomaly beneath the Java-lndonesian trench system yields a long-term, stable pattern of thermal heterogeneity in the lowermost mantle that resembles the present- day Large Low Shear Velocity Provinces (LLSVPs), especially below the Pacific. The evolution of sub- duction zones may be, however, influenced by the mantle-wide flow driven by deeply-rooted and long- lived superplumes since Archean times. These convection models also detect the intrinsic buoyancy of the Perm Anomaly that has been identified as a unique slow feature distinct from the two principal LLSVPs. We find there is no need for dense chemical 'piles' in the lower mantle to generate a stable distribution of temperature anomalies that are correlated to the LLSVPs and the Perm Anomaly. Our tomography-based convection simulations also demonstrate that intraplate volcanism in the south-east Pacific may be interpreted in terms of shallow small-scale convection triggered by a superplume beneath the East Pacific Rise.
基金This work was supported by the Science and Technology Innovation Program of Hunan Province(2022RC4027)the Joint Fund for Regional Innovation and Development of the National Natural Science Foundation of China(U22A20570).
文摘The development of allometric biomass models is important process in biomass estimation because the reliability of forest biomass and carbon estimations largely depends on the accuracy and precision of such models.National Forest Inventories(NFI)are detailed assessments of forest resources at national and regional levels that provide valuable data for forest biomass estimation.However,the lack of biomass allometric equations for each tree species in the NFI currently hampers the estimation of national-scale forest biomass.The main objective of this study was to develop allometric biomass regression equations for each tree species in the NFI of China based on limited biomass observations.These equations optimally grouped NFI and biomass observation species according to their phylogenetic relationships.Significant phylogenetic signals demonstrated phylogenetic conservation of the crown-to-stem biomass ratio.Based on phylogenetic relationships,we grouped and matched NFI and biomass observation species into 22 categories.Allometric biomass regression models were developed for each of these 22 species categories,and the models performed successfully(R^(2)=0.97,root mean square error(RMSE)=12.9t·ha^(–1),relative RMSE=11.5%).Furthermore,we found that phylogeny-based models performed more effectively than wood density-based models.The results suggest that grouping species based on their phylogenetic relationships is a reliable approach for the development and selection of accurate allometric equations.
基金Financially supported by the Natural Sciences and Engineering Research Council (NSERC) ofCanada Canada Research Chair Program and the Fond québécois de recherche et nature en technologie (FQRNT) ofQuebec.
基金The financial support of NSERC (Canada) and FCAR (Quebec) is gratefully acknowledged.
文摘A simple method for the fabrication of ultrathin films containing low molecular weight dye material is introduced(post-adsorption technique). The chromophore used is 4-nitro-4'-decyloxy azobenzene quaternary ammonium salt (azo-10Q).In classical layer-by-layer (LBL) procedures, where the substrate is dipped alternately into the chromophore solution and thecomplementary polyelectrolyte, the chromophore tends to desorb from the film during subsequent immersion in thepolyanion solution, and there is little or no indication of multilayer growth. The extent of desorption depends somewhat onthe selection of polyelectrolyte, the ionic strength and the pH of solution. An alternative approach is to first prepareconventional LBL films from a pair of oppositely charged polyelectrolytes, and then to soak this film into the chromophoresolution, where adsorption by penetration into the LBL film may take place. In preliminary results, a linear dependence ofUV absorbance on layer number of LBL film thus prepared was found, demonstrating the apparent effectiveness of the post-adsorption technique for the preparation of azo-10Q-containing ultrathin films.
文摘Over the past decade Sino-Russian cooperation in the Arctic has emerged as one of the major topics of the Russia-China negotiations on how to expand their comprehensive strategic partnership and to bring it to a new level. China considers the Arctic region important for its economic interests and desires to be included in the development of the region and its economic potential. For Russia, the Arctic is a future strategic resource base that would replace the old depleting fields and assure Russia’s status as a major worldwide energy supplier. Despite many joint statements on deepening of the Sino-Russian cooperation in the development of the Arctic energy resources, the concrete results of these ambitious plans are few. Some joint projects were dropped, as China and Russia could not agree on the conditions of the deal, others are progressing very slowly and have an uncertain future. In 2017, China has expanded its "Belt and Road Initiative"(BRI) to the Arctic thus elevating the Sino-Russian cooperation in the Artcic to a higher level. How did the relationship between Russia and China evolve in the Arctic and how do Russia and China view and respond to the new Arctic dimension of the BRI? What factors limit the strategic rapprochement between China and Russia in the Arctic?
基金the Natural Sciences and Engineering Research Council of Canada(NSERC)for financial support of this work.
文摘Aminocaproic acid (ACA) mixed methanolic lead acetate-thiourea (PbAc-TU) complex as precursor for fabrication of lead sulphide (PbS) nanoparticles (NPs) has been explained. The size, structure and morphology of as-prepared ACA-capped PbS NPs were systematically characterized by scanning electron microscopy (SEM), Transmission electron mi-croscopy (TEM), X-ray diffraction (XRD), Uv-vis spectroscopy and Brunauer-Emmett-Teller (BET) techniques. The obtained results show that the synthesized PbS NPs are nanocrystalline, size quantized and their agglomeration shows a mesoporous network of 8.7 nm in pore size. The binding nature of ACA molecules on PbS surface was studied by thermo gravimetric analysis (TGA), Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) techniques. Results indicate that ACA acts as a soft template that restricts the growth of PbS NPs through its binding to Pb surface via nitrogen lone pair.
基金Funding was provided by Natural Sciences and Engineering Research Council of Canada(NSERC)grant no.OGP0007738 to P.L.
文摘Aims Beta diversity is the variation in species composition among sites in a geographic region.Beta diversity is a key concept for understanding the functioning of ecosystems,for the conservation of biodiversity and for ecosystem management.The present report describes how to analyse beta diversity from community composition and associated environmental and spatial data tables.Methods Beta diversity can be studied by computing diversity indices for each site and testing hypotheses about the factors that may explain the variation among sites.Alternatively,one can carry out a direct analysis of the community composition data table over the study sites,as a function of sets of environmental and spatial variables.These analyses are carried out by the statistical method of partitioning the variation of the diversity indices or the community composition data table with respect to environmental and spatial variables.Variation partitioning is briefly described herein.Important findings Variation partitioning is a method of choice for the interpretation of beta diversity using tables of environmental and spatial variables.Beta diversity is an interesting‘currency’for ecologists to compare either different sampling areas or different ecological communities cooccurring in an area.Partitioning must be based upon unbiased estimates of the variation of the community composition data table that is explained by the various tables of explanatory variables.The adjusted coefficient of determination provides such an unbiased estimate in both multiple regression and canonical redundancy analysis.After partitioning,one can test the significance of the fractions of interest and plot maps of the fitted values corresponding to these fractions.
基金supported by the National Natural Science Foundation of China(Grant Nos.31870602,31901295,and 32071745)the Program of Sichuan Excellent Youth Sci-Tech Foundation(20JCQN0145)+2 种基金the Chinese Postdoctoral Science Foundation(2020M673278)the CAS“Light of West China”Program(Y8C2021)Chengming You also acknowledges the China Scholarship Council for supporting a Ph.D.programme Grant(201806910030)。
文摘Background:Changes in foliar nitrogen(N)and phosphorus(P)stoichiometry play important roles in predicting the efects of global change on ecosystem structure and function.However,there is substantial debate on the efects of P addition on foliar N and P stoichiometry,particularly under diferent levels of N addition.Thus,we conducted a global meta-analysis to investigate how N addition alters the efects of P addition on foliar N and P stoichiometry across different rates and durations of P addition and plant growth types based on more than 1150 observations.Results:We found that P addition without N addition increased foliar N concentrations,whereas P addition with N addition had no efect.The positive efects of P addition on foliar P concentrations were greater without N addition than with N addition.Additionally,the efects of P addition on foliar N,P and N:P ratios varied with the rate and duration of P addition.In particular,short-term or low-dose P addition with and without N addition increased foliar N concentration,and the positive efects of short-term or low-dose P addition on foliar P concentrations were greater without N addition than with N addition.The responses of foliar N and P stoichiometry of evergreen plants to P addition were greater without N addition than with N addition.Moreover,regardless of N addition,soil P availability was more efective than P resorption efciency in predicting the changes in foliar N and P stoichiometry in response to P addition.Conclusions:Our results highlight that increasing N deposition might alter the response of foliar N and P stoichiometry to P addition and demonstrate the important efect of the experimental environment on the results.These results advance our understanding of the response of plant nutrient use efciency to P addition with increasing N deposition.
基金Financial support from NSERC of Canada,FRQNT of Quebec,the Canada Research Chair program and NNSF of China (Overseas collaborativegrant# 21228401)The authors are members of CSACS funded by FRQNTGRSTB funded by FRSQ
文摘Thermoresponsive core-shell microspheres are prepared and functionalized with 3-aminophenylboronic acid to make them responsive to glucose.The volume phase transition of the resulting particles is shifted to a lower temperature and a clear swelling is caused by the presence of glucose.The particles after the functionalization preserved their capability to form crystalline colloidal arrays.The changes of their properties may be used in the design of glucose sensors.
文摘Despite great progress in data sharing that has been made in China in recent decades,cultural,policy,and technological challenges have prevented Chinese researchers from maximizing the availability of their data to the global change science community.To achieve full and open exchange and sharing of scientific data,Chinese research funding agencies need to recognize that preserva-tion of,and access to,digital data are central to their mission,and must support these tasks accord-ingly.The Chinese government also needs to develop better mechanisms,incentives,and rewards,while scientists need to change their behavior and culture to recognize the need to maximize the usefulness of their data to society as well as to other researchers.The Chinese research communi-ty and individual researchers should think globally and act personally to promote a paradigm of open,free,and timely data sharing,and to increase the effectiveness of knowledge development.
基金supported by the NSERC,FQRNT and the Canada Research Chair program
文摘New polyurethanes based on bile acids were synthesized from alcohol derivatives of cholic and lithocholic acids and hexamethylene diisocyanate, in an effort to improve the biocompatibility and biodegradability of polyurethanes through the use of natural compounds. The hydrogen bonding in the polymers is confirmed by IR spectral analysis. The glass transition temperatures of the polymers are in the range of 82-138 ℃ and degradation temperatures in the range of 267-298 ℃ as studied by thermal analyses. Thermogravimetric studies indicate that the comonomers are of equimolar amounts in the polyurethanes derived from both bile acids.
基金This work has been supported by the Fonds de la Recherche Scientifique(FRS-FNRS Belgium)through the PdR Grant No.T.0238.13-AIXPHOthe PdR Grant No.T.0103.19-ALPS+7 种基金the Fonds de Recherche du Québec Nature et Technologie(FRQ-NT)the Natural Sciences and Engineering Research Council of Canada(NSERC)under grants RGPIN-2016-06666Computational resources have been provided by the supercomputing facilities of the Universitécatholique de Louvain(CISM/UCL)the Consortium des Equipements de Calcul Intensif en Fédération Wallonie Bruxelles(CECI)funded by the FRS-FNRS under Grant No.2.5020.11the Tier-1 supercomputer of the Fédération Wallonie-Bruxelles,infrastructure funded by the Walloon Region under the grant agreement No.1117545as well as the Canadian Foundation for Innovation,the Ministère de l’Éducation des Loisirs et du Sport(Québec),Calcul Québec,and Compute Canada.This work was supported by the Center for Computational Study of Excited-State Phenomena in Energy Materials(C2SEPEM)at the Lawrence Berkeley National Laboratory,which is funded by the U.S.Department of Energy,Office of Science,Basic Energy Sciences,Materials Sciences and Engineering Division under Contract No.DE-AC02-05CH11231as part of the Computational Materials Sciences Program(advanced algorithms/codes)and by the National Science Foundation under grant DMR-1926004(basic theory and formalism)This research used resources of the National Energy Research Scientific Computing Center(NERSC),a DOE Office of Science User Facility supported by the Office of Science of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231.
文摘Electronic and optical properties of materials are affected by atomic motion through the electron–phonon interaction:not only band gaps change with temperature,but even at absolute zero temperature,zero-point motion causes band-gap renormalization.We present a large-scale first-principles evaluation of the zero-point renormalization of band edges beyond the adiabatic approximation.For materials with light elements,the band gap renormalization is often larger than 0.3 eV,and up to 0.7 eV.This effect cannot be ignored if accurate band gaps are sought.For infrared-active materials,global agreement with available experimental data is obtained only when non-adiabatic effects are taken into account.They even dominate zero-point renormalization for many materials,as shown by a generalized Fröhlich model that includes multiple phonon branches,anisotropic and degenerate electronic extrema,whose range of validity is established by comparison with first-principles results.
基金financially supported by the National Natural Science Foundation of China(Nos.21374048 and 51625302)Tianjin Committee of Science and Technology(No.16JCZDJC32900)
文摘A strategy was developed for the synthesis of highly ordered 2D arrays of Ag-PNIPAM hybrid microgel. The highly ordered 2D arrays of PNIPAM microgel were prepared by dispersing PNIPAM microgel on a charge-reversible substrate. The microgel spheres self-assembled into a 3D colloidal crystal, and the first 111 plane was fixed in situ onto the substrate as a result of spontaneous charge reversal of the substrate, leaving a high-quality 2D array of PNIPAM microgel. Ag nanoparticles were then synthesized in situ inside the microgel spheres by introduction of Ag+ ions into the microgel spheres and reduction with sodium borohydride. The resulting 2D arrays are highly ordered. The inter-particle distance in the array can be tuned. In addition, the method allows the synthesis of large size arrays and the use of nonplanar substrate.