The character of structural changes in the surface layer of titanium carbide (TiC) with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The...The character of structural changes in the surface layer of titanium carbide (TiC) with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The thermal influence of the electron-beam irradiation on the surface layer microstructure of the composite fine-grained material was mathematically analyzed. Quantitative estimations of the depth of the zone in microstructural phase transformations were carried out. The microstructure and concentration profile of Ti distribution in the metallic binder over the cross section of the surface layer with microstructural phase transformations after electron-pulse treatment of the hard metal surface were experimentally investigated.展开更多
The effects of concentration and an oriented external electric field on the transformations of hydrogenbonded structures of trimesic acid(TMA) and terephthalic acid(TPA) have been investigated at a liquidsolid interfa...The effects of concentration and an oriented external electric field on the transformations of hydrogenbonded structures of trimesic acid(TMA) and terephthalic acid(TPA) have been investigated at a liquidsolid interface by scanning tunneling microscopy(STM).The triangular periodic TMA framework can be transformed into a flower-like structure by changing the STM sample bias sign in situ.Networks of TMA and TPA are porous at a negative substrate bias,but typically change to relatively compact forms when the polarity of the applied bias is reversed.This change is reversible if the applied bias is reversed.The effects have potentials to locally control the capture and release of analytes in host-guest systems and the 2D morphology in multicomponent layers.展开更多
Ni^(2+)/Cu^(2+)/SO_(4)^(2-)/polyvinyl alcohol precursor fibers with uniform diameters were prepared through electrospinning.Nickel-based composite nanoalloys containing Ni,Cu,and S were prepared through heat treatment...Ni^(2+)/Cu^(2+)/SO_(4)^(2-)/polyvinyl alcohol precursor fibers with uniform diameters were prepared through electrospinning.Nickel-based composite nanoalloys containing Ni,Cu,and S were prepared through heat treatment in an Ar atmosphere.The experimental results show that the main components of the prepared nanoalloys are NiCu,Ni_(3)S_(2),Ni,and C.The nanoalloys exhibit fine grain sizes about 200-500 nm,which can increase with increasing heat treatment temperature.Electrochemical test results show that the nickel sulfidemodified NiCu nanoalloy composites exhibit excellent oxygen evolution reaction properties,and the oxygen evolution reaction properties gradually improve with the increasing heat treatment temperature.The sample prepared at 1 000℃ for 40 min show a low overpotential of 423 mV and a small Tafel slope of 134 mV·dec^(-1) at a current density of 10 mA·cm^(-2).展开更多
Induction of tumor cell senescence has become a promising strategy for anti-tumor immunotherapy,but fibrotic matrix severely blocks senescence inducers penetration and immune cells infiltration.Herein,we designed a ca...Induction of tumor cell senescence has become a promising strategy for anti-tumor immunotherapy,but fibrotic matrix severely blocks senescence inducers penetration and immune cells infiltration.Herein,we designed a cancer-associated fibroblasts(CAFs)triggered structure-transformable nano-assembly(HSD-P@V),which can directionally deliver valsartan(Val,CAFs regulator)and doxorubicin(DOX,senescence inducer)to the specific targets.In detail,DOX is conjugated with hyaluronic acid(HA)via diselenide bonds(Se-Se)to form HSD micelles,while CAFs-sensitive peptide is grafted onto the HSD to form a hydrophilic polymer,which is coated on Val nanocrystals(VNs)surface for improving the stability and achieving responsive release.Once arriving at tumor microenvironment and touching CAFs,HSD-P@V disintegrates into VNs and HSD micelles due to sensitive peptide detachment.VNs can degrade the extracellularmatrix,leading to the enhanced penetration of HSD.HSD targets tumor cells,releases DOX to induce senescence,and recruits effector immune cells.Furthermore,senescent cells are cleared by the recruited immune cells to finish the integrated anti-tumor therapy.In vitro and in vivo results show that the nanoassembly remarkably inhibits tumor growth as well as lungmetastasis,and extends tumorbearing mice survival.This work provides a promising paradigm of programmed delivering multi-site nanomedicine for cancer immunotherapy.展开更多
The synergy effect of alloy elements in bimetallic clusters can be used to tune the chemical and physical properties. Research on the influences of alloy concentration and distribution on the frozen structure of bimet...The synergy effect of alloy elements in bimetallic clusters can be used to tune the chemical and physical properties. Research on the influences of alloy concentration and distribution on the frozen structure of bimetallic clusters plays a key rolc in exploring new structural materials. In this paper, we study the influence of Ag concentration on the frozen structure of the (AgCo)561 cluster by using molecular dynamics simulation with a general embedded atom method. The results indicate that tt^e structure and chemical ordering of the (AgCo)561 cluster are strongly related to Ag concentration. Hcp-icosahedron structural transformation in the frozen (CoAg)561 cluster can be induced by changing Ag concentration. The chemical ordering also transforms to Janus-like Co Ag from core-shell Co-Ag.展开更多
The high-pressure polymorphs and structural transformation of Sn were experimentally investigated using angle- dispersive synchrotron x-ray diffraction up to 108.9 GPa. The results show that at least at 12.8 GPa β-Sn...The high-pressure polymorphs and structural transformation of Sn were experimentally investigated using angle- dispersive synchrotron x-ray diffraction up to 108.9 GPa. The results show that at least at 12.8 GPa β-Sn→bct structure transformation was completed and no two-phase coexistence was found. By using a long-wavelength x-ray, we resolved the diffraction peaks splitting and discovered the formation of a new distorted orthorhombic structure bco from the bct structure at 31.8 GPa. The variation of the lattice parameters and their ratios with pressure further validate the observation of the bco polymorph. The bcc structure appears at 40.9 GPa and coexists with the bco phase throughout a wide pressure range of 40.9 GPa-73.1 GPa. Above 73.1 GPa, only the bcc polymorph is observed, The systematically experimental investigation confirms the phase transition sequence of Sn asβ-Sn→bct→bco→bco + bcc→bcc upon compression to 108.9 GPa at room temperature.展开更多
A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction(OER)during the water oxidation process.In particular,Ni oxide incorporated with even a small amount of Fe lea...A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction(OER)during the water oxidation process.In particular,Ni oxide incorporated with even a small amount of Fe leads to substantively enhanced OER activity.However,the critical role of Fe species during the electrocatalytic process is still under evaluation.Herein,we report nickel(oxy)hydroxide incorporated with Fe through the surface reconstruction of a bimetallic metal-organic framework(NiFe-MOF)during the water oxidation process.The spectroscopic investigations with theoretical calculations reveal the critical role of Fe in promoting the formation of highly oxidized Ni^(4+),which directly correlates with an enhanced OER activity.Both the geometric and electronic structu res of the as-reconstructed Ni_(1-x)Fe_(x)OOH electrocatalysts can be delicately tuned by the Ni-Fe ratio of the bimetallic NiFe-MOF,further affecting the catalytic activity.As a result,the Ni_(1-x)Fe_(x)OOH derived from Ni_(0.9)Fe_(0.1)-MOF delivers low overpotentials of 260 mV at 10 mA cm^(-2)and 400 mV at 300 mA cm^(-2).展开更多
Fe100-xPtx(x=30at.%-60at.%) nanocomposite films were deposited on natural-oxidized Si(100) substrates by magnetron sputtering. The as-deposited films were annealed between 373 and 1073 K. In situ X-ray diffraction sho...Fe100-xPtx(x=30at.%-60at.%) nanocomposite films were deposited on natural-oxidized Si(100) substrates by magnetron sputtering. The as-deposited films were annealed between 373 and 1073 K. In situ X-ray diffraction shows that the FePt nanocomposite films undergo a phase transformation from a disordered FCC phase to an ordered L10 phase between 673 and 773 K. The coercivity is 306 kA·m-1 whiles the average grain sizes is about 10 nm in the optimized FePt alloy film sample annealed at 673 K. The adjustable coercivity and fine grain size suggest that this FePt nanocomposites system is suitable as recording media at extremely high areal density.展开更多
In this paper,we performed an empirical study on the TFP effect of structural transformation based on panel data of economic growth in 169 countries across the world.Our findings are threefold:First,structural transfo...In this paper,we performed an empirical study on the TFP effect of structural transformation based on panel data of economic growth in 169 countries across the world.Our findings are threefold:First,structural transformation has an inverted U-shaped effect on TFP.When the degree of structural transformation is on the left side of the inflection point,structural transformation is conducive to softening industrial structure and inducing TFP;when the degree of structural transformation is on the right side of the inflection point,structural transformation will induce industrial hollowing out and inhibit TFP.Second,since the reform and opening up program was launched in 1978,China’s structural transformation has evolved from the stage of adaptation to the stage of strategic adjustment with an increasingly evident trend towards a service-based economy,but structural transformation remains on the left side of the inflection point of the inverted U-shaped curve,i.e.the TFP effect of structural transformation is positive.Third,TFP improvement lies at the heart of high-quality development.In pursuing high-quality development,China should lower growth rate expectations,attach greater importance to supply-side structural reforms,and accelerate structural transformation to promote TFP improvement.展开更多
Rural transformation can improve poverty reduction,living standards,and health outcomes in developing countries.However,impacts associated with rural transformation vary by region,household,and individual trait(includ...Rural transformation can improve poverty reduction,living standards,and health outcomes in developing countries.However,impacts associated with rural transformation vary by region,household,and individual trait(including gender).While research on rural transformation has been increasing over the last decade,there has been no comprehensive review conducted on the relationships between gender and rural transformation.Here,we conduct a systematic literature review to investigate the impacts of rural transformation on gender and the influence of gender inclusiveness on rural transformation.We reviewed 82 studies from 1960-2021 that explore the relationships between rural transformation and gender.We then developed a framework that captures incidences and flow directions between indicators.Results show that most studies examined the impacts of rural transformation on women and between gender indicators.Few investigated the role of women and the influence of gender inclusiveness on rural transformation.Overall,studies showed that rural transformation typically leads to positive outcomes for women regarding employment,income,and empowerment.However,negative impacts on women’s control over income,stability of new income sources,and access to healthy food are also common.Tailoring future development policies and programs to explicitly account for gender inclusiveness can lead to more successful rural transformation.展开更多
It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate.However,its mechanism is still not well unde...It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate.However,its mechanism is still not well understood yet.In this research,structure-Ⅱ(sⅡ)hydrate is synthesized using a methanepropane gas mixture with an initial mole ratio of 99:1,and it is found that large(5~(12)6~4)cages are cooccupied by multiple gases based on the rigid structure analysis of neutron diffraction data.The first principles calculation and molecular dynamics simulation are conducted to uncover the molecular mechanism for sⅡmethane-propane hydrate formation,revealing that the presence of propane inhibits the formation of structure-Ⅰ(sⅠ)hydrate but promotes sⅡhydrate formation.The results help to understand the accumulation mechanism of natural gas hydrate and benefit to optimize the condition for gas storage and transportation in hydrate form.展开更多
The intimate host-anion interactions will regulate thermodynamics and kinetics in the self-assembly of cationic cages mimicking biological counterparts.Herein,we report construction and transformation of three Pd(Ⅱ)-...The intimate host-anion interactions will regulate thermodynamics and kinetics in the self-assembly of cationic cages mimicking biological counterparts.Herein,we report construction and transformation of three Pd(Ⅱ)-based metal-organic cages(MOCs)depending on different anions.Stoichiometric conversions of the lantern-shaped MOC-34 into either octahedral MOC-35 or tricapped trigonal prism MOC-36 are induced by BF_(4)^(–)or NO_(3)^(–),respectively.MOC-36 is kinetically favored and can undergo quantitative conversion to the thermodynamically preferred MOC-35 upon heating,accelerated by excess BF_(4)^(–)to motivate dissociative dynamics of Pd-vertices and lower activation barrier of cage transformation.The guest encapsulation behaviors of MOC-35 and MOC-36 have also been tested.These results manifest a significance of host-anion dynamics beyond complementary anion template,shedding light on the understanding of intricate anion recognition in nature.展开更多
Atomically dispersed single-atom catalysts(SACs)have been extensively studied over the past decade because of their high atom utilization efficiencies and specific selectivities.Although numerous strategies have been ...Atomically dispersed single-atom catalysts(SACs)have been extensively studied over the past decade because of their high atom utilization efficiencies and specific selectivities.Although numerous strategies have been proposed to obtain SACs with high densities and stabilities,the transformation mechanism that occurs during the reaction is still unclear.This review summarizes the structural evolution of SACs in the preparation process and reaction with various electron microscopy techniques at atomic scale under environmental conditions.Current state-of-the-art environmental electron microscopy studies on SACs mainly focus on porous carbons,metals or metal oxides,and some specific composite materials.The dynamic evolution of SACs under various reaction conditions is also investigated in this study.Finally,we highlight the challenges and drawbacks of the current studies and the prospects for the future exploration of SACs with environmental strategies.展开更多
In search of new mineral raw materials with industrial potential, we identified a deposit located in the southwest of Oujda (in the Northeastern Morocco). The physicochemical analyses indicate that the ore consists ma...In search of new mineral raw materials with industrial potential, we identified a deposit located in the southwest of Oujda (in the Northeastern Morocco). The physicochemical analyses indicate that the ore consists mainly of diaspore, topaz and quartz, and also secondary minerals. The presence of topaz in the ore is explained by hydrothermal action on the structure of diaspore. The investigation of structural transformations reveals complex reaction mechanisms that result in a mixture of corundum-mullite at 1200℃, which is of great industrial interest. Thus, the peculiarity of this ore is the presence of fluorine and secondary minerals.展开更多
The low efficiency of oxygen evolution reaction(OER) is regarded as one of the major roadblocks for metal-air batteries and water electrolysis.Herein,a high-performance OER catalyst of NiFe_(0.2)(oxy)hydroxide(NiFe_(0...The low efficiency of oxygen evolution reaction(OER) is regarded as one of the major roadblocks for metal-air batteries and water electrolysis.Herein,a high-performance OER catalyst of NiFe_(0.2)(oxy)hydroxide(NiFe_(0.2)-O_(x)H_(y)) was developed through topotactic transformation of a Prussian blue analogue in an alkaline solution,which exhibits a low overpotential of only 263 mV to reach a current density of 10 mA cm^(-2) and a small Tafel slope of 35 mV dec-1.Ex-situ/operando Raman spectroscopy results indicated that the phase structure of NiFe_(0.2)-O_(x)H_(y) was irreversibly transformed from the type of α-Ni(OH)_(2) to γ-NiOOH with applying an anodic potential,while ex-situ/operando 57Fe Mossbauer spectroscopic studies evidenced the in-situ production of abundant high-valent iron species under OER conditions,which effectively promoted the OER catalysis.Our work elucidates that the amount of high-valent iron species in-situ produced in the NiFe(oxy)hydroxide has a positive correlation with its water oxidation reaction performance,which further deepens the understanding of the mechanism of NiFe-based electrocatalysts.展开更多
Nonlayered two-dimensional(2D)materials have attracted increasing attention,due to novel physical properties,unique surface structure,and high compatibility with microfabrication technique.However,owing to the inheren...Nonlayered two-dimensional(2D)materials have attracted increasing attention,due to novel physical properties,unique surface structure,and high compatibility with microfabrication technique.However,owing to the inherent strong covalent bonds,the direct synthesis of 2D planar structure from nonlayered materials,especially for the realization of large-size ultrathin 2D nonlayered materials,is still a huge challenge.Here,a general atomic substitution conversion strategy is proposed to synthesize large-size,ultrathin nonlayered 2D materials.Taking nonlayered CdS as a typical example,large-size ultrathin nonlayered CdS single-crystalline flakes are successfully achieved via a facile low-temperature chemical sulfurization method,where pre-grown layered CdI2 flakes are employed as the precursor via a simple hot plate assisted vertical vapor deposition method.The size and thickness of CdS flakes can be controlled by the CdI2 precursor.The growth mechanism is ascribed to the chemical substitution reaction from I to S atoms between CdI2 and CdS,which has been evidenced by experiments and theoretical calculations.The atomic substitution conversion strategy demonstrates that the existing 2D layered materials can serve as the precursor for difficult-to-synthesize nonlayered 2D materials,providing a bridge between layered and nonlayered materials,meanwhile realizing the fabrication of large-size ultrathin nonlayered 2D materials.展开更多
Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel struct...Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel structure LiMn2O4 and rock-salt structure Li2MnO3, whereas in argon single-phase orthorhombic LiMnO2 could obtain at the range of 750℃ to 920℃. The substitution of Mn by Zn2+ or Co3+ in LiMnO2 led to the structure of LiMnO2 transiting to Qα-LiFeO2. The results of electrochemical cycles indicated that the discharged capacity of orthorhombic-LiMnO2 was smaller at the initial stages, then gradually increased with the increasing of cycle number, finally the capacity stabilized to certain value after about 10th cycles. This phenomenon reveals that there is an activation process for orthorhombic LiMnO2 cathode materials during electrochemical cycles, which is a phase transition process from orthorhombic LiMnO2 to tetragonal spinel Li2Mn2O4. The capacity of orthorhombic LiMnO2 synthesized at lower temperature is larger than that synthesized at high temperature.展开更多
Metal-organic frameworks(MOFs)have been widely studied as efficient electrocatalysts for water oxidation due to their tunable structure and easy preparation.However,the rational design of MOFs-based electrocatalysts a...Metal-organic frameworks(MOFs)have been widely studied as efficient electrocatalysts for water oxidation due to their tunable structure and easy preparation.However,the rational design of MOFs-based electrocatalysts and fundamental understanding of their structural evolution during oxygen evolution reaction(OER)remain critical challenges.Here,we report a facile approach to tune the structural transformation process of the Co-based zeolitic imidazolate framework(ZIF)during the OER process by using water molecules as a vacancy promoter.The modified ZIF catalyst accelerates the structural transformation from MOF precursor to electrochemical active species and simultaneously enhances the vacancy density during the electrochemical activation process.The optimized electrocatalyst exhibits an extremely low overpotential 175 mV to deliver 10 mA cm^(-2) and superior durability(100 h)at 100 mA cm^(-2).The comprehensive characterization results reveal the structural transformation from the initial tetrahedral Co sites to cobalt oxyhydroxide(CoOOH)and the formation process of oxygen vacancies(CoOOH-Vo)at a high anodic potential.These findings represent a promising way to achieve highly active MOF-based electrocatalysts for water oxidation.展开更多
Scarcity of land resources and transformation of industrial structure is a pair of contradictory elements.We derive the characteristics of land use structure and industrial structure transformation in Xining City usin...Scarcity of land resources and transformation of industrial structure is a pair of contradictory elements.We derive the characteristics of land use structure and industrial structure transformation in Xining City using Transformation Coefficient(TC):first,in the period 1999-2000,the land use structure coefficient(θ1) declined by 79.55%,but the overall evolution trend is gentle;second,the transformation coefficient of industrial structure(θ2) tended to decline ceaselessly on the whole,a decrease of 36.09%(overall,the transformation coefficient of industrial structure is slightly greater than the land use structure coefficient);third,the inter-annual variation of the two experienced ups and downs(in the period 1999-2007,the inter-annual variation was great and in the period 2008-2010,the inter-annual variation tended to be gentle).On the basis of autocorrelation and co-integration model,we draw the following conclusions through analysis:first,the land use structure in Xining City plays a role in promoting industrial structure transformation;second,there is a long-term equilibrium relationship between the two.Finally,relevant policy recommendations are put forward for the industrial development in Xining City.展开更多
Designing multicomponent integration catalysts(MICs)has been a promising strategy for improving electrocatalytic hydrogen evolution reaction(HER)due to the highly active interfaces as well as electronic synergy.Nevert...Designing multicomponent integration catalysts(MICs)has been a promising strategy for improving electrocatalytic hydrogen evolution reaction(HER)due to the highly active interfaces as well as electronic synergy.Nevertheless,many fundamental questions such as their actual active species and the influence on long-term stability remain to be answered.Herein,we present the structural evolution from a pseudotri-component electrocatalyst of nitrogen-doped carbon supported nickel/vanadium nitride/vanadium oxide(Ni-VN-V_(2)O_(3)/NC)nanorods to the heterostructural nickel/vanadium nitride(Ni-VN/NC)nanosheets during chemical or electrochemical processes.The self-reconstructed Ni-VN/NC exhibits a robust stability under alkaline conditions,while maintaining initial efficient HER activity with a low overpotential of 76 mV at the current density of 10 mA cm^(-2).Theoretical calculations and quasi-in-situ spectroscopic technology unveil the redistribution of electrons on the synergistic active interface,which synchronously optimizes the affinities for hydrogen,hydroxide,and water molecules,thereby remarkably accelerating the HER kinetics by reducing the barrier of Volmer step.展开更多
文摘The character of structural changes in the surface layer of titanium carbide (TiC) with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The thermal influence of the electron-beam irradiation on the surface layer microstructure of the composite fine-grained material was mathematically analyzed. Quantitative estimations of the depth of the zone in microstructural phase transformations were carried out. The microstructure and concentration profile of Ti distribution in the metallic binder over the cross section of the surface layer with microstructural phase transformations after electron-pulse treatment of the hard metal surface were experimentally investigated.
基金supported by Science and Technology Project of Jiangxi Provincial Education Department(Nos.GJJ180942 and GJJ180941)National Natural Science Foundation of China(No.11664026)。
文摘The effects of concentration and an oriented external electric field on the transformations of hydrogenbonded structures of trimesic acid(TMA) and terephthalic acid(TPA) have been investigated at a liquidsolid interface by scanning tunneling microscopy(STM).The triangular periodic TMA framework can be transformed into a flower-like structure by changing the STM sample bias sign in situ.Networks of TMA and TPA are porous at a negative substrate bias,but typically change to relatively compact forms when the polarity of the applied bias is reversed.This change is reversible if the applied bias is reversed.The effects have potentials to locally control the capture and release of analytes in host-guest systems and the 2D morphology in multicomponent layers.
基金Funded by the Doctoral Fund of Chengdu University(No.2081919131)the Sichuan Science and Technology Program(No.2023YFG0229)。
文摘Ni^(2+)/Cu^(2+)/SO_(4)^(2-)/polyvinyl alcohol precursor fibers with uniform diameters were prepared through electrospinning.Nickel-based composite nanoalloys containing Ni,Cu,and S were prepared through heat treatment in an Ar atmosphere.The experimental results show that the main components of the prepared nanoalloys are NiCu,Ni_(3)S_(2),Ni,and C.The nanoalloys exhibit fine grain sizes about 200-500 nm,which can increase with increasing heat treatment temperature.Electrochemical test results show that the nickel sulfidemodified NiCu nanoalloy composites exhibit excellent oxygen evolution reaction properties,and the oxygen evolution reaction properties gradually improve with the increasing heat treatment temperature.The sample prepared at 1 000℃ for 40 min show a low overpotential of 423 mV and a small Tafel slope of 134 mV·dec^(-1) at a current density of 10 mA·cm^(-2).
基金was supported by National Natural Science Foundation of China(81972893,82172719)Natural Science Foundation of Henan(212300410071)Training program for young key teachers in Henan Province(2020GGJS019).
文摘Induction of tumor cell senescence has become a promising strategy for anti-tumor immunotherapy,but fibrotic matrix severely blocks senescence inducers penetration and immune cells infiltration.Herein,we designed a cancer-associated fibroblasts(CAFs)triggered structure-transformable nano-assembly(HSD-P@V),which can directionally deliver valsartan(Val,CAFs regulator)and doxorubicin(DOX,senescence inducer)to the specific targets.In detail,DOX is conjugated with hyaluronic acid(HA)via diselenide bonds(Se-Se)to form HSD micelles,while CAFs-sensitive peptide is grafted onto the HSD to form a hydrophilic polymer,which is coated on Val nanocrystals(VNs)surface for improving the stability and achieving responsive release.Once arriving at tumor microenvironment and touching CAFs,HSD-P@V disintegrates into VNs and HSD micelles due to sensitive peptide detachment.VNs can degrade the extracellularmatrix,leading to the enhanced penetration of HSD.HSD targets tumor cells,releases DOX to induce senescence,and recruits effector immune cells.Furthermore,senescent cells are cleared by the recruited immune cells to finish the integrated anti-tumor therapy.In vitro and in vivo results show that the nanoassembly remarkably inhibits tumor growth as well as lungmetastasis,and extends tumorbearing mice survival.This work provides a promising paradigm of programmed delivering multi-site nanomedicine for cancer immunotherapy.
基金supported by the Science Foundation of Chongqing Committee of Education of China (Grant No. KJ111206)the Fund of Chongqing University of Arts and Sciences (Grant No. Z2011RCYJ05)
文摘The synergy effect of alloy elements in bimetallic clusters can be used to tune the chemical and physical properties. Research on the influences of alloy concentration and distribution on the frozen structure of bimetallic clusters plays a key rolc in exploring new structural materials. In this paper, we study the influence of Ag concentration on the frozen structure of the (AgCo)561 cluster by using molecular dynamics simulation with a general embedded atom method. The results indicate that tt^e structure and chemical ordering of the (AgCo)561 cluster are strongly related to Ag concentration. Hcp-icosahedron structural transformation in the frozen (CoAg)561 cluster can be induced by changing Ag concentration. The chemical ordering also transforms to Janus-like Co Ag from core-shell Co-Ag.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11304294 and 11274281)the Science Fund from the National Laboratory of Shock Wave and Detonation Physics of China(Grant Nos.9140C670201140C67281 and 9140C670102150C67288)
文摘The high-pressure polymorphs and structural transformation of Sn were experimentally investigated using angle- dispersive synchrotron x-ray diffraction up to 108.9 GPa. The results show that at least at 12.8 GPa β-Sn→bct structure transformation was completed and no two-phase coexistence was found. By using a long-wavelength x-ray, we resolved the diffraction peaks splitting and discovered the formation of a new distorted orthorhombic structure bco from the bct structure at 31.8 GPa. The variation of the lattice parameters and their ratios with pressure further validate the observation of the bco polymorph. The bcc structure appears at 40.9 GPa and coexists with the bco phase throughout a wide pressure range of 40.9 GPa-73.1 GPa. Above 73.1 GPa, only the bcc polymorph is observed, The systematically experimental investigation confirms the phase transition sequence of Sn asβ-Sn→bct→bco→bco + bcc→bcc upon compression to 108.9 GPa at room temperature.
基金supported by the National Natural Science Foundation of China(22105060)the Natural Science Foundation of Hebei Province(E2020205004)+1 种基金Funding from the Science Foundation of Hebei Normal University(L2020B13)the Science and Technology Project of Hebei Education Department(BJ2021028)。
文摘A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction(OER)during the water oxidation process.In particular,Ni oxide incorporated with even a small amount of Fe leads to substantively enhanced OER activity.However,the critical role of Fe species during the electrocatalytic process is still under evaluation.Herein,we report nickel(oxy)hydroxide incorporated with Fe through the surface reconstruction of a bimetallic metal-organic framework(NiFe-MOF)during the water oxidation process.The spectroscopic investigations with theoretical calculations reveal the critical role of Fe in promoting the formation of highly oxidized Ni^(4+),which directly correlates with an enhanced OER activity.Both the geometric and electronic structu res of the as-reconstructed Ni_(1-x)Fe_(x)OOH electrocatalysts can be delicately tuned by the Ni-Fe ratio of the bimetallic NiFe-MOF,further affecting the catalytic activity.As a result,the Ni_(1-x)Fe_(x)OOH derived from Ni_(0.9)Fe_(0.1)-MOF delivers low overpotentials of 260 mV at 10 mA cm^(-2)and 400 mV at 300 mA cm^(-2).
基金This work was financially supported by the National Science Fund for Distinguished Young Scholars and the National Natural Science Foundation of China (No. 50325209, 50232030).
文摘Fe100-xPtx(x=30at.%-60at.%) nanocomposite films were deposited on natural-oxidized Si(100) substrates by magnetron sputtering. The as-deposited films were annealed between 373 and 1073 K. In situ X-ray diffraction shows that the FePt nanocomposite films undergo a phase transformation from a disordered FCC phase to an ordered L10 phase between 673 and 773 K. The coercivity is 306 kA·m-1 whiles the average grain sizes is about 10 nm in the optimized FePt alloy film sample annealed at 673 K. The adjustable coercivity and fine grain size suggest that this FePt nanocomposites system is suitable as recording media at extremely high areal density.
文摘In this paper,we performed an empirical study on the TFP effect of structural transformation based on panel data of economic growth in 169 countries across the world.Our findings are threefold:First,structural transformation has an inverted U-shaped effect on TFP.When the degree of structural transformation is on the left side of the inflection point,structural transformation is conducive to softening industrial structure and inducing TFP;when the degree of structural transformation is on the right side of the inflection point,structural transformation will induce industrial hollowing out and inhibit TFP.Second,since the reform and opening up program was launched in 1978,China’s structural transformation has evolved from the stage of adaptation to the stage of strategic adjustment with an increasingly evident trend towards a service-based economy,but structural transformation remains on the left side of the inflection point of the inverted U-shaped curve,i.e.the TFP effect of structural transformation is positive.Third,TFP improvement lies at the heart of high-quality development.In pursuing high-quality development,China should lower growth rate expectations,attach greater importance to supply-side structural reforms,and accelerate structural transformation to promote TFP improvement.
基金supported by the Australian Centre for International Agricultural Research(ACIAR,ADP/2017/024)。
文摘Rural transformation can improve poverty reduction,living standards,and health outcomes in developing countries.However,impacts associated with rural transformation vary by region,household,and individual trait(including gender).While research on rural transformation has been increasing over the last decade,there has been no comprehensive review conducted on the relationships between gender and rural transformation.Here,we conduct a systematic literature review to investigate the impacts of rural transformation on gender and the influence of gender inclusiveness on rural transformation.We reviewed 82 studies from 1960-2021 that explore the relationships between rural transformation and gender.We then developed a framework that captures incidences and flow directions between indicators.Results show that most studies examined the impacts of rural transformation on women and between gender indicators.Few investigated the role of women and the influence of gender inclusiveness on rural transformation.Overall,studies showed that rural transformation typically leads to positive outcomes for women regarding employment,income,and empowerment.However,negative impacts on women’s control over income,stability of new income sources,and access to healthy food are also common.Tailoring future development policies and programs to explicitly account for gender inclusiveness can lead to more successful rural transformation.
基金supported by the National Key Research and Development Program of China(2016YFA0401503 and 2018YFA0305700)the National Natural Science Foundation of China(11575288,91934303,21935001 and 11775011)+4 种基金the Strategic Priority Research ProgramKey Research Program of Frontier Sciences of the Chinese Academy of Sciences(XDB33000000,XDB25000000 and QYZDBSSW-SLH013)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y202003)the China Geological Survey(DD20190234)the Scientific Instrument Developing Project(ZDKYYQ20170001)of the Chinese Academy of Sciences。
文摘It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate.However,its mechanism is still not well understood yet.In this research,structure-Ⅱ(sⅡ)hydrate is synthesized using a methanepropane gas mixture with an initial mole ratio of 99:1,and it is found that large(5~(12)6~4)cages are cooccupied by multiple gases based on the rigid structure analysis of neutron diffraction data.The first principles calculation and molecular dynamics simulation are conducted to uncover the molecular mechanism for sⅡmethane-propane hydrate formation,revealing that the presence of propane inhibits the formation of structure-Ⅰ(sⅠ)hydrate but promotes sⅡhydrate formation.The results help to understand the accumulation mechanism of natural gas hydrate and benefit to optimize the condition for gas storage and transportation in hydrate form.
基金supported by the NKRD Program of China(No.2021YFA1500401)the National Natural Science Foundation of China(Nos.21821003,21890380)the LIRTP of Guangdong Pearl River Talents Program(No.2017BT01C161)。
文摘The intimate host-anion interactions will regulate thermodynamics and kinetics in the self-assembly of cationic cages mimicking biological counterparts.Herein,we report construction and transformation of three Pd(Ⅱ)-based metal-organic cages(MOCs)depending on different anions.Stoichiometric conversions of the lantern-shaped MOC-34 into either octahedral MOC-35 or tricapped trigonal prism MOC-36 are induced by BF_(4)^(–)or NO_(3)^(–),respectively.MOC-36 is kinetically favored and can undergo quantitative conversion to the thermodynamically preferred MOC-35 upon heating,accelerated by excess BF_(4)^(–)to motivate dissociative dynamics of Pd-vertices and lower activation barrier of cage transformation.The guest encapsulation behaviors of MOC-35 and MOC-36 have also been tested.These results manifest a significance of host-anion dynamics beyond complementary anion template,shedding light on the understanding of intricate anion recognition in nature.
基金the National Natural Science Foundation of China(52204255)Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization(PCSX202201)+1 种基金China Postdoctoral Science Foundation(2020M682764)the Yangzhou University Start-up Foundation.
文摘Atomically dispersed single-atom catalysts(SACs)have been extensively studied over the past decade because of their high atom utilization efficiencies and specific selectivities.Although numerous strategies have been proposed to obtain SACs with high densities and stabilities,the transformation mechanism that occurs during the reaction is still unclear.This review summarizes the structural evolution of SACs in the preparation process and reaction with various electron microscopy techniques at atomic scale under environmental conditions.Current state-of-the-art environmental electron microscopy studies on SACs mainly focus on porous carbons,metals or metal oxides,and some specific composite materials.The dynamic evolution of SACs under various reaction conditions is also investigated in this study.Finally,we highlight the challenges and drawbacks of the current studies and the prospects for the future exploration of SACs with environmental strategies.
文摘In search of new mineral raw materials with industrial potential, we identified a deposit located in the southwest of Oujda (in the Northeastern Morocco). The physicochemical analyses indicate that the ore consists mainly of diaspore, topaz and quartz, and also secondary minerals. The presence of topaz in the ore is explained by hydrothermal action on the structure of diaspore. The investigation of structural transformations reveals complex reaction mechanisms that result in a mixture of corundum-mullite at 1200℃, which is of great industrial interest. Thus, the peculiarity of this ore is the presence of fluorine and secondary minerals.
基金financially supported by the National Natural Science Foundation of China(21476232,21961142006)the International Partnership Program of Chinese Academy of Sciences(121421KYSB20170020)the State Key Laboratory of Catalysis in Dalian Institute of Chemical Physics(N-16-07)。
文摘The low efficiency of oxygen evolution reaction(OER) is regarded as one of the major roadblocks for metal-air batteries and water electrolysis.Herein,a high-performance OER catalyst of NiFe_(0.2)(oxy)hydroxide(NiFe_(0.2)-O_(x)H_(y)) was developed through topotactic transformation of a Prussian blue analogue in an alkaline solution,which exhibits a low overpotential of only 263 mV to reach a current density of 10 mA cm^(-2) and a small Tafel slope of 35 mV dec-1.Ex-situ/operando Raman spectroscopy results indicated that the phase structure of NiFe_(0.2)-O_(x)H_(y) was irreversibly transformed from the type of α-Ni(OH)_(2) to γ-NiOOH with applying an anodic potential,while ex-situ/operando 57Fe Mossbauer spectroscopic studies evidenced the in-situ production of abundant high-valent iron species under OER conditions,which effectively promoted the OER catalysis.Our work elucidates that the amount of high-valent iron species in-situ produced in the NiFe(oxy)hydroxide has a positive correlation with its water oxidation reaction performance,which further deepens the understanding of the mechanism of NiFe-based electrocatalysts.
基金This work was supported by National Natural Science Foundation of China(21825103,11774044,52072059)the Hubei Provincial Natural Science Foundation of China(2019CFA002)+1 种基金the Fundamental Research Funds for the Central Universities(2019kfyXMBZ018 and 2020kfyXJJS050)We also thank the technical support from Analytical and Testing Center in Huazhong University of Science and Technology.
文摘Nonlayered two-dimensional(2D)materials have attracted increasing attention,due to novel physical properties,unique surface structure,and high compatibility with microfabrication technique.However,owing to the inherent strong covalent bonds,the direct synthesis of 2D planar structure from nonlayered materials,especially for the realization of large-size ultrathin 2D nonlayered materials,is still a huge challenge.Here,a general atomic substitution conversion strategy is proposed to synthesize large-size,ultrathin nonlayered 2D materials.Taking nonlayered CdS as a typical example,large-size ultrathin nonlayered CdS single-crystalline flakes are successfully achieved via a facile low-temperature chemical sulfurization method,where pre-grown layered CdI2 flakes are employed as the precursor via a simple hot plate assisted vertical vapor deposition method.The size and thickness of CdS flakes can be controlled by the CdI2 precursor.The growth mechanism is ascribed to the chemical substitution reaction from I to S atoms between CdI2 and CdS,which has been evidenced by experiments and theoretical calculations.The atomic substitution conversion strategy demonstrates that the existing 2D layered materials can serve as the precursor for difficult-to-synthesize nonlayered 2D materials,providing a bridge between layered and nonlayered materials,meanwhile realizing the fabrication of large-size ultrathin nonlayered 2D materials.
基金supported by the National Natural Science Foundation of China under grant No.59972026.
文摘Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel structure LiMn2O4 and rock-salt structure Li2MnO3, whereas in argon single-phase orthorhombic LiMnO2 could obtain at the range of 750℃ to 920℃. The substitution of Mn by Zn2+ or Co3+ in LiMnO2 led to the structure of LiMnO2 transiting to Qα-LiFeO2. The results of electrochemical cycles indicated that the discharged capacity of orthorhombic-LiMnO2 was smaller at the initial stages, then gradually increased with the increasing of cycle number, finally the capacity stabilized to certain value after about 10th cycles. This phenomenon reveals that there is an activation process for orthorhombic LiMnO2 cathode materials during electrochemical cycles, which is a phase transition process from orthorhombic LiMnO2 to tetragonal spinel Li2Mn2O4. The capacity of orthorhombic LiMnO2 synthesized at lower temperature is larger than that synthesized at high temperature.
基金supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0206700,2017YFA0402802)the National Natural Science Foundation of China(Grant Nos.21776265,51902304)+1 种基金Anhui Provincial Natural Science Foundation(Grant No.1908085ME122)the Fundamental Research Funds for the Central Universities(Wk2060140026)。
文摘Metal-organic frameworks(MOFs)have been widely studied as efficient electrocatalysts for water oxidation due to their tunable structure and easy preparation.However,the rational design of MOFs-based electrocatalysts and fundamental understanding of their structural evolution during oxygen evolution reaction(OER)remain critical challenges.Here,we report a facile approach to tune the structural transformation process of the Co-based zeolitic imidazolate framework(ZIF)during the OER process by using water molecules as a vacancy promoter.The modified ZIF catalyst accelerates the structural transformation from MOF precursor to electrochemical active species and simultaneously enhances the vacancy density during the electrochemical activation process.The optimized electrocatalyst exhibits an extremely low overpotential 175 mV to deliver 10 mA cm^(-2) and superior durability(100 h)at 100 mA cm^(-2).The comprehensive characterization results reveal the structural transformation from the initial tetrahedral Co sites to cobalt oxyhydroxide(CoOOH)and the formation process of oxygen vacancies(CoOOH-Vo)at a high anodic potential.These findings represent a promising way to achieve highly active MOF-based electrocatalysts for water oxidation.
基金Supported by National Natural Science Foundation Project(41101098)Youth Project of Xianning University(KY10044,KY10043)
文摘Scarcity of land resources and transformation of industrial structure is a pair of contradictory elements.We derive the characteristics of land use structure and industrial structure transformation in Xining City using Transformation Coefficient(TC):first,in the period 1999-2000,the land use structure coefficient(θ1) declined by 79.55%,but the overall evolution trend is gentle;second,the transformation coefficient of industrial structure(θ2) tended to decline ceaselessly on the whole,a decrease of 36.09%(overall,the transformation coefficient of industrial structure is slightly greater than the land use structure coefficient);third,the inter-annual variation of the two experienced ups and downs(in the period 1999-2007,the inter-annual variation was great and in the period 2008-2010,the inter-annual variation tended to be gentle).On the basis of autocorrelation and co-integration model,we draw the following conclusions through analysis:first,the land use structure in Xining City plays a role in promoting industrial structure transformation;second,there is a long-term equilibrium relationship between the two.Finally,relevant policy recommendations are put forward for the industrial development in Xining City.
基金supported by the National Natural Science Foundation of China(21901089,21901088,22161021 and 91622105)the Jiangxi Provincial Department of Science and Technology(20192BBEL50017,20172BCB22008 and 20192ACB20013)+1 种基金the support of Jiangxi Province(jxsq2018106041)the‘‘Young Elite Scientists Sponsorship Program”by CAST。
文摘Designing multicomponent integration catalysts(MICs)has been a promising strategy for improving electrocatalytic hydrogen evolution reaction(HER)due to the highly active interfaces as well as electronic synergy.Nevertheless,many fundamental questions such as their actual active species and the influence on long-term stability remain to be answered.Herein,we present the structural evolution from a pseudotri-component electrocatalyst of nitrogen-doped carbon supported nickel/vanadium nitride/vanadium oxide(Ni-VN-V_(2)O_(3)/NC)nanorods to the heterostructural nickel/vanadium nitride(Ni-VN/NC)nanosheets during chemical or electrochemical processes.The self-reconstructed Ni-VN/NC exhibits a robust stability under alkaline conditions,while maintaining initial efficient HER activity with a low overpotential of 76 mV at the current density of 10 mA cm^(-2).Theoretical calculations and quasi-in-situ spectroscopic technology unveil the redistribution of electrons on the synergistic active interface,which synchronously optimizes the affinities for hydrogen,hydroxide,and water molecules,thereby remarkably accelerating the HER kinetics by reducing the barrier of Volmer step.