We investigate the effective interaction between two heavy impurities immersed in a quasi-twodimensional dipolar Bose-Einstein condensate via a variation approach.We show that the mediated interaction is highly tunabl...We investigate the effective interaction between two heavy impurities immersed in a quasi-twodimensional dipolar Bose-Einstein condensate via a variation approach.We show that the mediated interaction is highly tunable via the contact and the dipole-dipole interactions between the background gas atoms.Interestingly,the mediated interaction potential may become an oscillating function of inter-impurity distance when roton excitation emerges under sufficiently strong dipolar interaction.Our system therefore provides an efficient way for tuning the mediated interaction between impurities.展开更多
In this work, we explore the statistical physics of colloidal particles that interact with electrolytes via ion-specific interactions. Firstly we study particles interacting weakly with electrolyte using linear respon...In this work, we explore the statistical physics of colloidal particles that interact with electrolytes via ion-specific interactions. Firstly we study particles interacting weakly with electrolyte using linear response theory. We find that the mean potential around a particle is linearly determined by the effective charge distribution of the particle, which depends both on the bare charge distribution and on ion-specific interactions. We also discuss the effective interaction between two such particles and show that, in the far field regime, it is bilinear in the effective charge distributions of two particles. We subsequently generalize the above results to the more complicated case where particles interact strongly with the electrolyte.Our results indicate that in order to understand the statistical physics of non-dilute electrolytes, both ion-specific interactions and ionic correlations have to be addressed in a single unified and consistent framework.展开更多
This paper is a short revisit to Kuo-Brown effective interaction derived from the Hamada-Johnston nucleon-nucleon potential, done by Gerry Brown and Tom Kuo. This effective interaction, derived in year 1966, is the fi...This paper is a short revisit to Kuo-Brown effective interaction derived from the Hamada-Johnston nucleon-nucleon potential, done by Gerry Brown and Tom Kuo. This effective interaction, derived in year 1966, is the first attempt to describe nuclear structure properties from the free nucleon-nucleon potential. Nowadays much progress has been achieved for the effective interactions in shell model. We would compare the effective interactions obtained in the 1966 paper with up-to-date shell-model interactions in sd-shell and pf-shell model space. Recent knowledge of effective interactions on nuclear structure, can also be traced in the KuoBrown effective interaction, i.e., the universal roles of central and tensor forces, which reminds us that such discovery should be noticed much earlier.展开更多
We investigate many-body correlations caused by two- and three-body （2-, 3bd） forces. Shell-model effective interactions derived from ab initio methods （coupled-cluster method, no-core shell model） are adopted. Vl...We investigate many-body correlations caused by two- and three-body （2-, 3bd） forces. Shell-model effective interactions derived from ab initio methods （coupled-cluster method, no-core shell model） are adopted. Vlow-k potentials, based on many-body perturbation theory, are also tested, especially for their cut-off dependence. We compare the central, tensor and spin-orbit interactions from microscopic theory to the fitted interactions. After the inclusion of the three-body force, the matrix elements become fairly close to those fitted directly to experimental data. Calculations of neutron-rich oxygen isotopes are performed, to clarify the effects of 3bd forces, tensor, and spin-orbit interactions on the nuclear binding and excitation energies. We find that the 3bd force can influence the binding energies greatly, which also determines the drip line position, while its effect on excitation energies is not very pronounced. The spin-orbit force, which is part of the 2bd force, can affect the shell structure explicitly, at least for neutron-rich systems.展开更多
The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nick...The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nickel-based catalysts have great application prospects in the industrialization process of olefin coordination polymerization.In this work,various N-aryl substituents with different electronic effects were synthesized and introduced intoα-diimine ligands.The aspreparedα-diimine nickel catalysts showed high polymerization activity(0.9×10^(7)–3.0×10^(7)g·mol^(−1)·h^(−1))in ethylene polymerization,generating polyethylene products with adjustable molecular weights(Mn values:7.4×10^(4)–146.9×10^(4)g·mol^(−1))and branching densities(31/1000 C–68/1000 C).The resulting polyethylene products showed excellent mechanical properties,with high tensile strength(up to 25.0 MPa)and high strain at break values(up to 3890%).The copolymerization of ethylene and polar monomers can also be achieved by these nicekel complexes,ultimately preparing functionalized polyolefins.展开更多
Grain cooking and nutrient qualities are the most important components of rice （Oryza sativa L.） quality. A doubled haploid （DH） population from a cross between two japonica cultivars was used to examine the pheno...Grain cooking and nutrient qualities are the most important components of rice （Oryza sativa L.） quality. A doubled haploid （DH） population from a cross between two japonica cultivars was used to examine the phenotypic values and potential QTLs for the quality traits. The cooking and nutrient quality traits, including the amylose content （AC）, the gel consistency （CJC）, the gelatinization temperature （GT）, and the protein content （PC）, in rice grown under upland and lowland environments were evaluated. Significant differences for AC, GC, GT, and PC between upland and lowland environments were detected. The phenotypic values of all four traits were higher under upland environment than lowland environment. The value of PC under upland environment was significantly higher （by 37.9%） than that under lowland environment. This suggests that upland cultivation had large effect on both cooking and nutrient qualifies. A total of seven QTLs and twelve pairs of QTLs were detected to have significant additive and epistatic effects for the four traits. Significant Q x E interaction effects of two QTLs and two pairs of QTLs were also discovered. The general contribution of additive QTLs ranged from 1.91% to 19.77%. The Q × E interactions of QTLs QGt3 and QAc6 accounted for 8.99% and 47.86% of the phenotypic variation, respectively, whereas those of the 2 pairs of epistatic QTLs, QAc6-QAcllb and QAc8-QAc9, accounted for 32.54% and 11.82%, respectively. Five QTLs QGt6b, QGt8, QGt11, QGcl, and QPc2, which had relatively high general contribution and no Q x E interactions, were selected to facilitate the upland rice grain quality breeding.展开更多
Fertilization or atmospheric deposition of nitrogen(N)and phosphorus(P)to terrestrial ecosystems can alter soil N(P)availability and the nature of nutrient limitation for plant growth.Changing the allocation of leaf P...Fertilization or atmospheric deposition of nitrogen(N)and phosphorus(P)to terrestrial ecosystems can alter soil N(P)availability and the nature of nutrient limitation for plant growth.Changing the allocation of leaf P fractions is potentially an adaptive strategy for plants to cope with soil N(P)availability and nutrient-limiting conditions.However,the impact of the interactions between imbalanced anthropogenic N and P inputs on the concentrations and allocation proportions of leaf P fractions in forest woody plants remains elusive.We conducted a metaanalysis of data about the concentrations and allocation proportions of leaf P fractions,specifically associated with individual and combined additions of N and P in evergreen forests,the dominant vegetation type in southern China where the primary productivity is usually considered limited by P.This assessment allowed us to quantitatively evaluate the effects of N and P additions alone and interactively on leaf P allocation and use strategies.Nitrogen addition(exacerbating P limitation)reduced the concentrations of leaf total P and different leaf P fractions.Nitrogen addition reduced the allocation to leaf metabolic P but increased the allocation to other fractions,while P addition showed opposite trends.The simultaneous additions of N and P showed an antagonistic(mutual suppression)effect on the concentrations of leaf P fractions,but an additive(summary)effect on the allocation proportions of leaf P fractions.These results highlight the importance of strategies of leaf P fraction allocation in forest plants under changes in environmental nutrient availability.Importantly,our study identified critical interactions associated with combined N and P inputs that affect leaf P fractions,thus aiding in predicting plant acclimation strategies in the context of intensifying and imbalanced anthropogenic nutrient inputs.展开更多
Excellent nitrogen(N)management techniques can improve crop yields while mitigating reactive N(Nr)losses.The synergistic effects of applying paired N management techniques have important implications for designing exc...Excellent nitrogen(N)management techniques can improve crop yields while mitigating reactive N(Nr)losses.The synergistic effects of applying paired N management techniques have important implications for designing excellent N management strategies,but the interaction effects remain poorly known.Here,a meta-analysis was conducted to quantify the effects of optimized N management techniques(optimized N application rate,optimized topdressing,and applying enhanced-efficiency fertilizers)on wheat yield,N use efficiency(NUE),and Nr losses,as well as the interactive effects of paired N management techniques(combining an optimized N rate with topdressing or enhanced-effciency fertilizers).The results demonstrated that an optimized N fertilizer rate reduced Nr losses by 28-31%while the wheat yield declined by 2%;however,the wheat yield increased by 2%when the reduction of N fertilizer was less than 20%.The adoption of topdressing and enhancedeffciency fertilizers signifcantly increased wheat yields by 4-8%and NUE by 8-14%,while reducing Nr losses by 28-40%,and high topdressing frequency and nitrifcation inhibitors showed stronger positive effects on wheat yield.Paired N management techniques increased wheat yields by 3-4%and NUE by 37-38%,with additive or synergistic effects;and they also reduced Nr losses by 5-66%but showed an antagonistic effect.Such nonadditive interactions amplifed the positive effects on wheat production,but the benefts in terms of environmental risk reduction were weakened.Overall,this study highlights the importance of synergistic effects in innovative N management to address the trade-off between crop yield and Nr losses.展开更多
Global warming and nitrogen(N)deposition have a profound impact on greenhouse gas(GHG)fluxes and consequently,they also affect climate change.However,the global combined effects of warming and N addition on GHG fluxes...Global warming and nitrogen(N)deposition have a profound impact on greenhouse gas(GHG)fluxes and consequently,they also affect climate change.However,the global combined effects of warming and N addition on GHG fluxes remain to be fully understood.To address this knowledge gap,a globalmeta-analysis of 197 datasets was performed to assess the response of GHG fluxes to warming and N addition and their interactions under various climate and experimental conditions.The results indicate that warming significantly increased CO_(2)emissions,while N addition and the combined warming and N addition treatments had no impact on CO_(2)emissions.Moreover,both warming and N addition and their interactions exhibited positive effects on N_(2)O emissions.Under the combined warming and N addition treatments,warming was observed to exert a positive main effect on CO_(2)emissions,while N addition had a positive main effect on N_(2)O emissions.The interactive effects of warming and N addition exhibited antagonistic effects on CO_(2),N_(2)O,and CH_(4)emissions,with CH_(4)uptake dominated by additive effects.Furthermore,we identified biome and climate factors as the two treatments.These findings indicate that both warming and N addition substantially impact soil GHG fluxes and highlight the urgent need to investigate the influence of the combination of warming and N addition on terrestrial carbon and N cycling under ongoing global change.展开更多
Due to space constraints in urban areas,metro tunnels are typically constructed in pairs,with a small clearance.The interaction between twin tunnels leads to a significantly more complex ground deformation and stress ...Due to space constraints in urban areas,metro tunnels are typically constructed in pairs,with a small clearance.The interaction between twin tunnels leads to a significantly more complex ground deformation and stress distribution than that observed in a single tunnel scenario,particularly if the tunnels are excavated in sequence.A series of physical model tests were conducted to investigate soil deformation and stress disturbances caused by the excavation of twin tunnels.The test results indicate that the interaction between the twin tunnels was observed.Due to the soil arching effect,the excavation of Tunnel 2 increases the soil stress acting on Tunnel 1.An analytical method was proposed to determine soil stress considering the soil arching effect and the interaction between twin tunnels.The method categorized the relative locations between twin tunnels into non-influenced,partially influenced,and fully influenced scenarios.For non-influenced and fully influenced scenarios,the soil stresses above twin tunnels were calculated based on a symmetric major principal stress trace.For the partially influenced scenario,however,the soil arch above Tunnel 2 was asymmetric due to the interaction,and the stress distribution was obtained based on a new asymmetric major principal stress trace.The soil stress on Tunnel 1 was influenced by the load transferred from Tunnel 2 and calculated based on the force equilibrium.A comparison of the analytical and test results indicates that the proposed method effectively predicts the soil stress in the cover layer above twin tunnels excavated sequentially,considering the interaction and soil arching effects.展开更多
The present article provides supplementary information of previous works of analytic models for predicting conductivity enhancements of carbon nanotube composites. The models, though fairly simple, are able to take ac...The present article provides supplementary information of previous works of analytic models for predicting conductivity enhancements of carbon nanotube composites. The models, though fairly simple, are able to take account of the effects of conductivity anisotropy, nonstraightness, and aspect ratio of the CNT additives on the conductivity enhancement of the composite and to give predictions agreeing well with existing experimental data. The omitted detailed derivation of this model is demonstrated in the present article with a more systematical analysis, which may help with further development in this direction. Furthermore, the effects of various orientation distributions of CNTs are reported here for the first time. The information may be useful in design or fabrication technology of CNT composites for better or specified conductivities.展开更多
A comparative optimal design of fluid-saturated prismatic cellular metal honeycombs （PCMHs） having different cell shapes is presented for thermal management applications. Based on the periodic topology of each PCMH,...A comparative optimal design of fluid-saturated prismatic cellular metal honeycombs （PCMHs） having different cell shapes is presented for thermal management applications. Based on the periodic topology of each PCMH, a unit cell （UC） for thermal transport analysis was selected to calculate its effective thermal conductivity. Without introducing any empirical coefficient, we modified and extended the analytical model of parallel-series thermal-electric network to a wider porosity range （0.7 ~ 0.98） by considering the effects of two-dimensional local heat conduction in solid ligaments inside each UC. Good agreement was achieved between analytical predictions and numerical simulations based on the method of finite volume. The concept of ligament heat conduction efficiency （LTCE） was proposed to physically explain the mechanisms underlying the effects of ligament configuration on effective thermal conductivity （ETC）. Based upon the proposed theory, a construct strategy was developed for designing the ETC by altering the equivalent interaction angle with the direction of heat flow： relatively small average interaction angle for thermal conduction and relatively large one for thermal insulation.展开更多
In a three-sphere system, the middle sphere is acted upon by two opposite depletion forces from the other two spheres. It is found that, in this system, the two depletion forces are coupled with each other and result ...In a three-sphere system, the middle sphere is acted upon by two opposite depletion forces from the other two spheres. It is found that, in this system, the two depletion forces are coupled with each other and result in a strengthened depletion force. So the difference of the depletion forces of the three-sphere system and its corresponding two two-sphere systems is introduced to describe the coupling effect of the depletion interactions. The numerical results obtained by Monte- Carlo simulations show that this coupling effect is affected by both the concentration of small spheres and the geometrical confinement. Meanwhile, it is also found that the mechanisms of the coupling effect and the effect on the depletion force from the ~eometry factor are the same.展开更多
The neuroimmune system of the brain:Early studies(1990’s)on the neurological consequences of human immunodeficiency virus-1(HIV-1)infection in the brain were instrumental in establishing that specific brain cell type...The neuroimmune system of the brain:Early studies(1990’s)on the neurological consequences of human immunodeficiency virus-1(HIV-1)infection in the brain were instrumental in establishing that specific brain cell types can function as an innate immune system within the brain and in that role influence cognitive function(Kaul et al.,2005).展开更多
Samples of undoped, and CuO, CaO, Al2O3 as well as V2O5 doped MnZn ferrite were prepared using standard ceramic method. The X-ray diffraction results for the base and doped ferrite samples show a single phase with spi...Samples of undoped, and CuO, CaO, Al2O3 as well as V2O5 doped MnZn ferrite were prepared using standard ceramic method. The X-ray diffraction results for the base and doped ferrite samples show a single phase with spinel cubic structure. The Mossbauer spectrum of the base sample indicates line broadening and overlapping due to relaxation of magnetic dipoles. The temperature dependence of DC-electrical conductivity has been discussed on the basis of electronic conduction (electron hopping) and ionic conduction mechanism.展开更多
The efficient development of the urban economy is a major concern of scholars in the fields of geography and urban science.In the context of globalization,informatization,industrialization,and urbanization,the externa...The efficient development of the urban economy is a major concern of scholars in the fields of geography and urban science.In the context of globalization,informatization,industrialization,and urbanization,the external relationships of China's cities are experiencing the joint action of urban scale hierarchies and connection networks(“hierarchy-network”).However,under the interactive effect of the two,the mechanism of urban economic efficiency(UEE)is unclear.Therefore,based on Baidu migration data,the regionalization with dynamically constrained agglomerative clustering and partitioning(REDCAP)method,and a spatial simultaneous equation model,this paper analyzes the UEE spatial pattern and mechanism in China.The results indicate that:(1)the urban economy has a superlinear relationship with the population size.However,the benefit of this superlinear growth is in marginal decline.(2)The UEE shows a pattern of differentiation between China's eastern,then central,and then western region.Also,local differences are found within the three major sub-regions.(3)The increase of urban network centrality can promote UEE,while the impact of urban scale is negative.(4)There is regional heterogeneity of the interactive effect of“hierarchy-network”on UEE.This study reveals the influencing mechanism of UEE and also provides policy implications for the development of UEE.展开更多
A genetic model was proposed for simultaneously analyzing genetic effects of nuclear, cytoplasm, and nuclear-cytoplasmic interaction （NCI） as well as their genotype by environment （GE） interaction for quantitative...A genetic model was proposed for simultaneously analyzing genetic effects of nuclear, cytoplasm, and nuclear-cytoplasmic interaction （NCI） as well as their genotype by environment （GE） interaction for quantitative traits of diploid plants. In the model, the NCI effects were further partitioned into additive and dominance nuclear-cytoplasmic interaction components. Mixed linear model approaches were used for statistical analysis. On the basis of diallel cross designs, Monte Carlo simulations showed that the genetic model was robust for estimating variance components under several situations without specific effects. Random genetic effects were predicted by an adjusted unbiased prediction （AUP） method. Data on four quantitative traits （boll number, lint percentage, fiber length, and micronaire） in Upland cotton （Gossypium hirsutum L.） were analyzed as a worked example to show the effectiveness of the model.展开更多
The shell model calculations in the sdgh major shell for the neutron-deficient ^106,107,108,109Sn isotopes have been carried out by using CD-Bonn and Nijmegenl two-body effective nucleon-nucleon interactions. The sing...The shell model calculations in the sdgh major shell for the neutron-deficient ^106,107,108,109Sn isotopes have been carried out by using CD-Bonn and Nijmegenl two-body effective nucleon-nucleon interactions. The singleshell states and the corresponding matrix elements needed for describing Sn isotopes are reconstructed to calculate the coefficient of fractional parantage by reducing the calculation requirements. This reconstruction allows us to do the shell model calculations of the neutron deficient Sn isotopes in very reasonable time. The results are compared to the recent high-resolution experimental data and found to be in good agreement with experiments.展开更多
The combined and interactive effects of the bolt-hole fit conditions and the preloads of the fasteners on the load carrying capacity of single-lap composite-to-titanium bolted joints have been investigated both experi...The combined and interactive effects of the bolt-hole fit conditions and the preloads of the fasteners on the load carrying capacity of single-lap composite-to-titanium bolted joints have been investigated both experimentally and numerically. Quasi-static tests of the hybrid joints with different fit conditions are implemented, and a three dimensional finite element progressive failure analysis model is proposed to predict the influences of the bolt-hole fit conditions and fastener＇s pre- loads on the mechanical behaviors of the joints. Based on the experimental validated simulation method, a multi-factor, mixed levels orthogonal design table and the analysis of variance method are used to arrange the simulation conditions and to further study the interactive effects of preloads and fit conditions. Through the analysis of the results, for the researched double bolt, single-lap composite-titanium joints, it is found that： the effects of both the interference fit and the preloads change from positive into negative mode with the increase of the interference fit values or preload values; appropriate bolt-hole fit conditions and preloads can improve the bolt-hole contact conditions of the loaded joints, and then retard the fiber failures around the fastener holes, and increase the load carrying capacity of the joints eventually; the interactive effect of the bolt-hole interference fit conditions and preloads cannot be ignored and the parameters need to be considered together and synthetically as the joints are being optimized.展开更多
Mega-urban agglomerations are strategic core areas for national economic development and the main regions of new urbanization. They also have important roles in shifting the global economic center of gravity to China....Mega-urban agglomerations are strategic core areas for national economic development and the main regions of new urbanization. They also have important roles in shifting the global economic center of gravity to China. However, the development of mega-urban agglomerations has triggered the interactive coercion between resources and the eco-envi- ronment. The interactive coupled effects between urbanization and the eco-environment in mega-urban agglomerations represent frontier and high-priority research topics in the field of Earth system science over the next decade. In this paper, we carried out systematic theo- retical analysis of the interactive coupling mechanisms and coercing effects between ur- banization and the eco-environment in mega-urban agglomerations. In detail, we analyzed the nonlinear-coupled relationships and the coupling characteristics between natural and human elements in mega-urban agglomerations. We also investigated the interactive coercion intensities between internal and external elements, and the mechanisms and patterns of local couplings and telecouplings in mega-urban agglomeration systems, which are affected by key internal and external control elements. In addition, we proposed the interactive coupling theory on urbanization and the eco-environment in mega-urban agglomerations. Furthermore we established a spatiotemporal dynamic coupling model with multi-element, multi-scale, multi-scenario, multi-module and multi-agent integrations, which can be used to develop an intelligent decision support system for sustainable development of mega-urban agglomera- tions. In general, our research may provide theoretical guidance and method support to solve problems related to mega-urban agglomerations and maintain their sustainable development.展开更多
基金the NSFC(Grants No.11674334,No.11974363,and No.11947302)the Strategic Priority Research Program of CAS(Grant No.XDB28000000)the Thousand-Youth-Talent Program of China。
文摘We investigate the effective interaction between two heavy impurities immersed in a quasi-twodimensional dipolar Bose-Einstein condensate via a variation approach.We show that the mediated interaction is highly tunable via the contact and the dipole-dipole interactions between the background gas atoms.Interestingly,the mediated interaction potential may become an oscillating function of inter-impurity distance when roton excitation emerges under sufficiently strong dipolar interaction.Our system therefore provides an efficient way for tuning the mediated interaction between impurities.
基金supported by the National Natural Science Foundation of China(Grant Nos.11174196 and 91130012)
文摘In this work, we explore the statistical physics of colloidal particles that interact with electrolytes via ion-specific interactions. Firstly we study particles interacting weakly with electrolyte using linear response theory. We find that the mean potential around a particle is linearly determined by the effective charge distribution of the particle, which depends both on the bare charge distribution and on ion-specific interactions. We also discuss the effective interaction between two such particles and show that, in the far field regime, it is bilinear in the effective charge distributions of two particles. We subsequently generalize the above results to the more complicated case where particles interact strongly with the electrolyte.Our results indicate that in order to understand the statistical physics of non-dilute electrolytes, both ion-specific interactions and ionic correlations have to be addressed in a single unified and consistent framework.
基金supported by the National Natural Science Foundation of China(Grant Nos.11275067 and 11447109)the support from the Helmholtz Association(HGF)through the Nuclear Astrophysics Virtual Institute(VH-VI-417)
文摘This paper is a short revisit to Kuo-Brown effective interaction derived from the Hamada-Johnston nucleon-nucleon potential, done by Gerry Brown and Tom Kuo. This effective interaction, derived in year 1966, is the first attempt to describe nuclear structure properties from the free nucleon-nucleon potential. Nowadays much progress has been achieved for the effective interactions in shell model. We would compare the effective interactions obtained in the 1966 paper with up-to-date shell-model interactions in sd-shell and pf-shell model space. Recent knowledge of effective interactions on nuclear structure, can also be traced in the KuoBrown effective interaction, i.e., the universal roles of central and tensor forces, which reminds us that such discovery should be noticed much earlier.
基金Supported by National Natural Science Foundation of China(11505056,U1732138,11605054,11790325,11305108,11575290,11675148,11747312,11775316)the Outstanding Young Talent Research Fund of Zhengzhou University(1521317002)
文摘We investigate many-body correlations caused by two- and three-body （2-, 3bd） forces. Shell-model effective interactions derived from ab initio methods （coupled-cluster method, no-core shell model） are adopted. Vlow-k potentials, based on many-body perturbation theory, are also tested, especially for their cut-off dependence. We compare the central, tensor and spin-orbit interactions from microscopic theory to the fitted interactions. After the inclusion of the three-body force, the matrix elements become fairly close to those fitted directly to experimental data. Calculations of neutron-rich oxygen isotopes are performed, to clarify the effects of 3bd forces, tensor, and spin-orbit interactions on the nuclear binding and excitation energies. We find that the 3bd force can influence the binding energies greatly, which also determines the drip line position, while its effect on excitation energies is not very pronounced. The spin-orbit force, which is part of the 2bd force, can affect the shell structure explicitly, at least for neutron-rich systems.
基金supported by the National Key R&D Program of China(2021YFA1501700)Fundamental Research Funds for the Central Universities(WK9990000142).
文摘The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nickel-based catalysts have great application prospects in the industrialization process of olefin coordination polymerization.In this work,various N-aryl substituents with different electronic effects were synthesized and introduced intoα-diimine ligands.The aspreparedα-diimine nickel catalysts showed high polymerization activity(0.9×10^(7)–3.0×10^(7)g·mol^(−1)·h^(−1))in ethylene polymerization,generating polyethylene products with adjustable molecular weights(Mn values:7.4×10^(4)–146.9×10^(4)g·mol^(−1))and branching densities(31/1000 C–68/1000 C).The resulting polyethylene products showed excellent mechanical properties,with high tensile strength(up to 25.0 MPa)and high strain at break values(up to 3890%).The copolymerization of ethylene and polar monomers can also be achieved by these nicekel complexes,ultimately preparing functionalized polyolefins.
基金This work was supported by the State Key Basic Research and Development Plan of China (973)the Hi-Tech Research and De-velopment Program of China (863) National Natural Science Foundation of China.
文摘Grain cooking and nutrient qualities are the most important components of rice （Oryza sativa L.） quality. A doubled haploid （DH） population from a cross between two japonica cultivars was used to examine the phenotypic values and potential QTLs for the quality traits. The cooking and nutrient quality traits, including the amylose content （AC）, the gel consistency （CJC）, the gelatinization temperature （GT）, and the protein content （PC）, in rice grown under upland and lowland environments were evaluated. Significant differences for AC, GC, GT, and PC between upland and lowland environments were detected. The phenotypic values of all four traits were higher under upland environment than lowland environment. The value of PC under upland environment was significantly higher （by 37.9%） than that under lowland environment. This suggests that upland cultivation had large effect on both cooking and nutrient qualifies. A total of seven QTLs and twelve pairs of QTLs were detected to have significant additive and epistatic effects for the four traits. Significant Q x E interaction effects of two QTLs and two pairs of QTLs were also discovered. The general contribution of additive QTLs ranged from 1.91% to 19.77%. The Q × E interactions of QTLs QGt3 and QAc6 accounted for 8.99% and 47.86% of the phenotypic variation, respectively, whereas those of the 2 pairs of epistatic QTLs, QAc6-QAcllb and QAc8-QAc9, accounted for 32.54% and 11.82%, respectively. Five QTLs QGt6b, QGt8, QGt11, QGcl, and QPc2, which had relatively high general contribution and no Q x E interactions, were selected to facilitate the upland rice grain quality breeding.
基金supported by the National Natural Science Foundation of China(No.41473068)supported by China Postdoctoral Science Foundation(No.2022M722667)。
文摘Fertilization or atmospheric deposition of nitrogen(N)and phosphorus(P)to terrestrial ecosystems can alter soil N(P)availability and the nature of nutrient limitation for plant growth.Changing the allocation of leaf P fractions is potentially an adaptive strategy for plants to cope with soil N(P)availability and nutrient-limiting conditions.However,the impact of the interactions between imbalanced anthropogenic N and P inputs on the concentrations and allocation proportions of leaf P fractions in forest woody plants remains elusive.We conducted a metaanalysis of data about the concentrations and allocation proportions of leaf P fractions,specifically associated with individual and combined additions of N and P in evergreen forests,the dominant vegetation type in southern China where the primary productivity is usually considered limited by P.This assessment allowed us to quantitatively evaluate the effects of N and P additions alone and interactively on leaf P allocation and use strategies.Nitrogen addition(exacerbating P limitation)reduced the concentrations of leaf total P and different leaf P fractions.Nitrogen addition reduced the allocation to leaf metabolic P but increased the allocation to other fractions,while P addition showed opposite trends.The simultaneous additions of N and P showed an antagonistic(mutual suppression)effect on the concentrations of leaf P fractions,but an additive(summary)effect on the allocation proportions of leaf P fractions.These results highlight the importance of strategies of leaf P fraction allocation in forest plants under changes in environmental nutrient availability.Importantly,our study identified critical interactions associated with combined N and P inputs that affect leaf P fractions,thus aiding in predicting plant acclimation strategies in the context of intensifying and imbalanced anthropogenic nutrient inputs.
基金financially support by the Shaanxi Province Key R&D Program,China(2024NC2-GJHX-28)the National Natural Science Foundation of China(31902120)the National Key R&D Program of China(2021YFD1900700)。
文摘Excellent nitrogen(N)management techniques can improve crop yields while mitigating reactive N(Nr)losses.The synergistic effects of applying paired N management techniques have important implications for designing excellent N management strategies,but the interaction effects remain poorly known.Here,a meta-analysis was conducted to quantify the effects of optimized N management techniques(optimized N application rate,optimized topdressing,and applying enhanced-efficiency fertilizers)on wheat yield,N use efficiency(NUE),and Nr losses,as well as the interactive effects of paired N management techniques(combining an optimized N rate with topdressing or enhanced-effciency fertilizers).The results demonstrated that an optimized N fertilizer rate reduced Nr losses by 28-31%while the wheat yield declined by 2%;however,the wheat yield increased by 2%when the reduction of N fertilizer was less than 20%.The adoption of topdressing and enhancedeffciency fertilizers signifcantly increased wheat yields by 4-8%and NUE by 8-14%,while reducing Nr losses by 28-40%,and high topdressing frequency and nitrifcation inhibitors showed stronger positive effects on wheat yield.Paired N management techniques increased wheat yields by 3-4%and NUE by 37-38%,with additive or synergistic effects;and they also reduced Nr losses by 5-66%but showed an antagonistic effect.Such nonadditive interactions amplifed the positive effects on wheat production,but the benefts in terms of environmental risk reduction were weakened.Overall,this study highlights the importance of synergistic effects in innovative N management to address the trade-off between crop yield and Nr losses.
基金supported by Ningxia Key Research and Development Fund Project of China(No.2023BCF01048)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2023-JC-YB-182).
文摘Global warming and nitrogen(N)deposition have a profound impact on greenhouse gas(GHG)fluxes and consequently,they also affect climate change.However,the global combined effects of warming and N addition on GHG fluxes remain to be fully understood.To address this knowledge gap,a globalmeta-analysis of 197 datasets was performed to assess the response of GHG fluxes to warming and N addition and their interactions under various climate and experimental conditions.The results indicate that warming significantly increased CO_(2)emissions,while N addition and the combined warming and N addition treatments had no impact on CO_(2)emissions.Moreover,both warming and N addition and their interactions exhibited positive effects on N_(2)O emissions.Under the combined warming and N addition treatments,warming was observed to exert a positive main effect on CO_(2)emissions,while N addition had a positive main effect on N_(2)O emissions.The interactive effects of warming and N addition exhibited antagonistic effects on CO_(2),N_(2)O,and CH_(4)emissions,with CH_(4)uptake dominated by additive effects.Furthermore,we identified biome and climate factors as the two treatments.These findings indicate that both warming and N addition substantially impact soil GHG fluxes and highlight the urgent need to investigate the influence of the combination of warming and N addition on terrestrial carbon and N cycling under ongoing global change.
基金supported by the National Natural Science Foundation of China(Grant No.52308463)the Shanghai Rising-Star Program(Grant No.23YF1449100)the Fundamental Research Funds for the Central Universities(Grant No.2023-2-ZD08).
文摘Due to space constraints in urban areas,metro tunnels are typically constructed in pairs,with a small clearance.The interaction between twin tunnels leads to a significantly more complex ground deformation and stress distribution than that observed in a single tunnel scenario,particularly if the tunnels are excavated in sequence.A series of physical model tests were conducted to investigate soil deformation and stress disturbances caused by the excavation of twin tunnels.The test results indicate that the interaction between the twin tunnels was observed.Due to the soil arching effect,the excavation of Tunnel 2 increases the soil stress acting on Tunnel 1.An analytical method was proposed to determine soil stress considering the soil arching effect and the interaction between twin tunnels.The method categorized the relative locations between twin tunnels into non-influenced,partially influenced,and fully influenced scenarios.For non-influenced and fully influenced scenarios,the soil stresses above twin tunnels were calculated based on a symmetric major principal stress trace.For the partially influenced scenario,however,the soil arch above Tunnel 2 was asymmetric due to the interaction,and the stress distribution was obtained based on a new asymmetric major principal stress trace.The soil stress on Tunnel 1 was influenced by the load transferred from Tunnel 2 and calculated based on the force equilibrium.A comparison of the analytical and test results indicates that the proposed method effectively predicts the soil stress in the cover layer above twin tunnels excavated sequentially,considering the interaction and soil arching effects.
文摘The present article provides supplementary information of previous works of analytic models for predicting conductivity enhancements of carbon nanotube composites. The models, though fairly simple, are able to take account of the effects of conductivity anisotropy, nonstraightness, and aspect ratio of the CNT additives on the conductivity enhancement of the composite and to give predictions agreeing well with existing experimental data. The omitted detailed derivation of this model is demonstrated in the present article with a more systematical analysis, which may help with further development in this direction. Furthermore, the effects of various orientation distributions of CNTs are reported here for the first time. The information may be useful in design or fabrication technology of CNT composites for better or specified conductivities.
基金supported by the National Natural Science Foundation of China(51506160,11472208,11472209)China Post-Doctoral Science Foundation Project(2015M580845)+1 种基金the Fundamental Research Funds for Xi’an Jiaotong University(xjj2015102)the Beijing Key Lab of Heating,Gas Supply,Ventilating and Air Conditioning Engineering(NR2016K01)
文摘A comparative optimal design of fluid-saturated prismatic cellular metal honeycombs （PCMHs） having different cell shapes is presented for thermal management applications. Based on the periodic topology of each PCMH, a unit cell （UC） for thermal transport analysis was selected to calculate its effective thermal conductivity. Without introducing any empirical coefficient, we modified and extended the analytical model of parallel-series thermal-electric network to a wider porosity range （0.7 ~ 0.98） by considering the effects of two-dimensional local heat conduction in solid ligaments inside each UC. Good agreement was achieved between analytical predictions and numerical simulations based on the method of finite volume. The concept of ligament heat conduction efficiency （LTCE） was proposed to physically explain the mechanisms underlying the effects of ligament configuration on effective thermal conductivity （ETC）. Based upon the proposed theory, a construct strategy was developed for designing the ETC by altering the equivalent interaction angle with the direction of heat flow： relatively small average interaction angle for thermal conduction and relatively large one for thermal insulation.
基金Project supported by the Scientific Research Fund of Hunan Provincial Education Department, China (Grant Nos. 08B028 and 10A075)the Natural Science Foundation of Hunan Province, China (Grant No. 08jj6043)
文摘In a three-sphere system, the middle sphere is acted upon by two opposite depletion forces from the other two spheres. It is found that, in this system, the two depletion forces are coupled with each other and result in a strengthened depletion force. So the difference of the depletion forces of the three-sphere system and its corresponding two two-sphere systems is introduced to describe the coupling effect of the depletion interactions. The numerical results obtained by Monte- Carlo simulations show that this coupling effect is affected by both the concentration of small spheres and the geometrical confinement. Meanwhile, it is also found that the mechanisms of the coupling effect and the effect on the depletion force from the ~eometry factor are the same.
基金supported by National Institutes of Health Grant AA024484(to DLG)。
文摘The neuroimmune system of the brain:Early studies(1990’s)on the neurological consequences of human immunodeficiency virus-1(HIV-1)infection in the brain were instrumental in establishing that specific brain cell types can function as an innate immune system within the brain and in that role influence cognitive function(Kaul et al.,2005).
文摘Samples of undoped, and CuO, CaO, Al2O3 as well as V2O5 doped MnZn ferrite were prepared using standard ceramic method. The X-ray diffraction results for the base and doped ferrite samples show a single phase with spinel cubic structure. The Mossbauer spectrum of the base sample indicates line broadening and overlapping due to relaxation of magnetic dipoles. The temperature dependence of DC-electrical conductivity has been discussed on the basis of electronic conduction (electron hopping) and ionic conduction mechanism.
基金National Natural Science Foundation of China,No.42371222,No.41971167Fundamental Scientific Research Funds of Central China Normal University,No.CCNU24ZZ120,No.CCNU22JC026。
文摘The efficient development of the urban economy is a major concern of scholars in the fields of geography and urban science.In the context of globalization,informatization,industrialization,and urbanization,the external relationships of China's cities are experiencing the joint action of urban scale hierarchies and connection networks(“hierarchy-network”).However,under the interactive effect of the two,the mechanism of urban economic efficiency(UEE)is unclear.Therefore,based on Baidu migration data,the regionalization with dynamically constrained agglomerative clustering and partitioning(REDCAP)method,and a spatial simultaneous equation model,this paper analyzes the UEE spatial pattern and mechanism in China.The results indicate that:(1)the urban economy has a superlinear relationship with the population size.However,the benefit of this superlinear growth is in marginal decline.(2)The UEE shows a pattern of differentiation between China's eastern,then central,and then western region.Also,local differences are found within the three major sub-regions.(3)The increase of urban network centrality can promote UEE,while the impact of urban scale is negative.(4)There is regional heterogeneity of the interactive effect of“hierarchy-network”on UEE.This study reveals the influencing mechanism of UEE and also provides policy implications for the development of UEE.
基金This work was supported by Chinese National Programs for High Technology Research and Development(973 Program)(No.2004CB117306).
文摘A genetic model was proposed for simultaneously analyzing genetic effects of nuclear, cytoplasm, and nuclear-cytoplasmic interaction （NCI） as well as their genotype by environment （GE） interaction for quantitative traits of diploid plants. In the model, the NCI effects were further partitioned into additive and dominance nuclear-cytoplasmic interaction components. Mixed linear model approaches were used for statistical analysis. On the basis of diallel cross designs, Monte Carlo simulations showed that the genetic model was robust for estimating variance components under several situations without specific effects. Random genetic effects were predicted by an adjusted unbiased prediction （AUP） method. Data on four quantitative traits （boll number, lint percentage, fiber length, and micronaire） in Upland cotton （Gossypium hirsutum L.） were analyzed as a worked example to show the effectiveness of the model.
基金supported in part by the Scientific and Technological Council of Turkey under Grant No.TUBITAK 105T092Süleyman Demirel University under Grant No.SDUBAP 1075-m-05
文摘The shell model calculations in the sdgh major shell for the neutron-deficient ^106,107,108,109Sn isotopes have been carried out by using CD-Bonn and Nijmegenl two-body effective nucleon-nucleon interactions. The singleshell states and the corresponding matrix elements needed for describing Sn isotopes are reconstructed to calculate the coefficient of fractional parantage by reducing the calculation requirements. This reconstruction allows us to do the shell model calculations of the neutron deficient Sn isotopes in very reasonable time. The results are compared to the recent high-resolution experimental data and found to be in good agreement with experiments.
文摘The combined and interactive effects of the bolt-hole fit conditions and the preloads of the fasteners on the load carrying capacity of single-lap composite-to-titanium bolted joints have been investigated both experimentally and numerically. Quasi-static tests of the hybrid joints with different fit conditions are implemented, and a three dimensional finite element progressive failure analysis model is proposed to predict the influences of the bolt-hole fit conditions and fastener＇s pre- loads on the mechanical behaviors of the joints. Based on the experimental validated simulation method, a multi-factor, mixed levels orthogonal design table and the analysis of variance method are used to arrange the simulation conditions and to further study the interactive effects of preloads and fit conditions. Through the analysis of the results, for the researched double bolt, single-lap composite-titanium joints, it is found that： the effects of both the interference fit and the preloads change from positive into negative mode with the increase of the interference fit values or preload values; appropriate bolt-hole fit conditions and preloads can improve the bolt-hole contact conditions of the loaded joints, and then retard the fiber failures around the fastener holes, and increase the load carrying capacity of the joints eventually; the interactive effect of the bolt-hole interference fit conditions and preloads cannot be ignored and the parameters need to be considered together and synthetically as the joints are being optimized.
基金The Major Program of National Natural Science Foundation of China, No.41590840, No.41590842
文摘Mega-urban agglomerations are strategic core areas for national economic development and the main regions of new urbanization. They also have important roles in shifting the global economic center of gravity to China. However, the development of mega-urban agglomerations has triggered the interactive coercion between resources and the eco-envi- ronment. The interactive coupled effects between urbanization and the eco-environment in mega-urban agglomerations represent frontier and high-priority research topics in the field of Earth system science over the next decade. In this paper, we carried out systematic theo- retical analysis of the interactive coupling mechanisms and coercing effects between ur- banization and the eco-environment in mega-urban agglomerations. In detail, we analyzed the nonlinear-coupled relationships and the coupling characteristics between natural and human elements in mega-urban agglomerations. We also investigated the interactive coercion intensities between internal and external elements, and the mechanisms and patterns of local couplings and telecouplings in mega-urban agglomeration systems, which are affected by key internal and external control elements. In addition, we proposed the interactive coupling theory on urbanization and the eco-environment in mega-urban agglomerations. Furthermore we established a spatiotemporal dynamic coupling model with multi-element, multi-scale, multi-scenario, multi-module and multi-agent integrations, which can be used to develop an intelligent decision support system for sustainable development of mega-urban agglomera- tions. In general, our research may provide theoretical guidance and method support to solve problems related to mega-urban agglomerations and maintain their sustainable development.
