The properties of Pbn（n=2―30） clusters including binding energies,second differences in energy,and HOMO-LUMO gaps,especially fragmentation energies and ionization potentials,have been studied by ab initio calculati...The properties of Pbn（n=2―30） clusters including binding energies,second differences in energy,and HOMO-LUMO gaps,especially fragmentation energies and ionization potentials,have been studied by ab initio calculation.The main fragmentation products of Pbn＋ are shown to be Pb＋Pbn-1＋ for n≤14 and two small cluster fragments for larger ones with n14.The Pb13＋ appears frequently as the products in the fragmentations of large clusters.Also,the calculated ionization potentials of the clusters are consistent with the experiment data.展开更多
Mixed matrix membranes(MMMs)could combine the advantages of both polymeric membranes and porousfillers,making them an effective alternative to conventional polymer membranes.However,interfacial incompatibility issues,s...Mixed matrix membranes(MMMs)could combine the advantages of both polymeric membranes and porousfillers,making them an effective alternative to conventional polymer membranes.However,interfacial incompatibility issues,such as the presence of interfacial voids,hardening of polymer chains,and blockage of micropores by polymers between common MMMsfillers and the polymer matrix,currently limit the gas sep-aration performance of MMMs.Ternary phase MMMs(consisting of afiller,an additive,and a matrix)made by adding a third compound,usually functionalized additives,can overcome the structural problems of binary phase MMMs and positively impact membrane separation performance.This review introduces the structure and fabrication processes for ternary MMMs,categorizes various nanofillers and the third component,and summarizes and analyzes in detail the CO_(2) separation performance of newly developed ternary MMMs based on both rubbery and glassy polymers.Based on this separation data,the challenges of ternary MMMs are also discussed.Finally,future directions for ternary MMMs are proposed.展开更多
As a significant semiconductor,nickel selenide shows enormous potential and extensive application pro spects in the field of sensor,photocatalysis and supercapacito r.In this paper,nickel selenide(Ni3Se2,NiSe) thin fi...As a significant semiconductor,nickel selenide shows enormous potential and extensive application pro spects in the field of sensor,photocatalysis and supercapacito r.In this paper,nickel selenide(Ni3Se2,NiSe) thin films were successfully fabricated on stainless-steel sheet using a facile,effective electrodeposition technique.The morphologies,microstructures and chemical compositions of the thin films are characterized systematically.Electrochemical tests exhibit that the Ni3Se2 and NiSe possess high specific capacitance of 581.1 F/g and 1644.7 F/g,respectively.A flexible,all-solid-state asymmetric supercapacitor is assembled by utilizing NiSe film as positive electrode and activated carbon as negative electrode.The solid device delivers a high areal capacitance of 27.0 mF/cm2 at the current density of 0.7 mA/cm2.The maximum volumetric energy density and powerdensity of the NiSe//AC asymmetric SCs can achieve 0.26 mWh/cm3 and 33.35 mW/cm3,respectively.The device shows robust cycling stability with 84.6% capacitance retention after 10,000 cycles,outstanding flexibility and satis factory mechanical stability.Moreover,two devices in series can light up a red light-emitting diode,which displayed great potential applications for energy storage.展开更多
Dynamics are intricately linked with activity and selectivity when it comes to catalysis,as noted for instance in the enzymatic principles of induced fit and allostery,and yet the range of motions heterogeneous cataly...Dynamics are intricately linked with activity and selectivity when it comes to catalysis,as noted for instance in the enzymatic principles of induced fit and allostery,and yet the range of motions heterogeneous catalytic sites are able to undergo is poorly understood.Solid-state nuclear magnetic resonance(NMR)spectroscopy is perhaps the only tool capable of probing the rapid conformational dynamics found in heterogeneous catalysts but has historically been restricted by its low sensitivity,limiting the detail with which structures can be resolved.Here,we apply solid-state NMR and dynamic nuclear polarization,in combination with density functional theory modeling,to reveal the high-resolution structure and motional freedom of a scandium supported complex in three dimensions.The results are contrasted with the study of the analogous homoleptic complex in the crystalline state,highlighting the impacts that surface structure may have on the dynamics of supported complexes.展开更多
Here we show the effect of Li chemical pressure on the structure of layered polymorphs with LiNiB composition:RT-LiNiB(room temperature polymorph)and HT-LiNiB(high temperature polymorph),resulting in stabilization of ...Here we show the effect of Li chemical pressure on the structure of layered polymorphs with LiNiB composition:RT-LiNiB(room temperature polymorph)and HT-LiNiB(high temperature polymorph),resulting in stabilization of the novel RT-Li_(1+x)NiB(x∼0.17)and HT-Li_(1+y)NiB(y∼0.06)phases.Depending on the synthesis temperature and initial Li content,precisely controlled via hydride route synthesis,[NiB]layers undergo structural deformations,allowing for extra Li atoms to be accommodated between the layers.In situ variable temperature synchrotron and time-dependent laboratory powder X-ray diffraction studies suggest Li step-wise deintercalation processes:RT-Li_(1+x)NiB→RT-LiNiB(high temp.)→LiNi_(3)B_(1.8)→binary Ni borides and HT-Li_(1+y)NiB→HT-LiNiB(high temp.)→LiNi_(3)B_(1.8)→binary Ni borides.Quantum chemistry calculations and solid state^(7)Li and^(11)B NMR spectroscopy shed light on the complexity of real superstructures of these compounds determined from high resolution synchrotron powder diffraction data.展开更多
Fast-neutron （FN） irradiation has been used to create mutagen- ized collections of many plant species （Bolon et al., 2014）, FN- induced mutagenesis has clear advantages： it is an efficient means of saturating the...Fast-neutron （FN） irradiation has been used to create mutagen- ized collections of many plant species （Bolon et al., 2014）, FN- induced mutagenesis has clear advantages： it is an efficient means of saturating the genome, and it does not involve time- consuming plant transformation or tissue culture. In rice, most mutant collections, although highly valuable, were generated us- ing either T-DNA insertion or transposon tagging approaches that often induce mutations unlinked to the insertion and complicating analysis （Wang et al., 2013）. Another disadvantage of some of these collections is that they were created in rice varieties that are photoperiod-sensitive and often have long generation times.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.20773047 and 21043001)
文摘The properties of Pbn（n=2―30） clusters including binding energies,second differences in energy,and HOMO-LUMO gaps,especially fragmentation energies and ionization potentials,have been studied by ab initio calculation.The main fragmentation products of Pbn＋ are shown to be Pb＋Pbn-1＋ for n≤14 and two small cluster fragments for larger ones with n14.The Pb13＋ appears frequently as the products in the fragmentations of large clusters.Also,the calculated ionization potentials of the clusters are consistent with the experiment data.
基金support from Sichuan Science and Technology Program(2021YFH0116)National Natural Science Foundation of China(No.52170112)DongFang Boiler Co.,Ltd.(3522015).
文摘Mixed matrix membranes(MMMs)could combine the advantages of both polymeric membranes and porousfillers,making them an effective alternative to conventional polymer membranes.However,interfacial incompatibility issues,such as the presence of interfacial voids,hardening of polymer chains,and blockage of micropores by polymers between common MMMsfillers and the polymer matrix,currently limit the gas sep-aration performance of MMMs.Ternary phase MMMs(consisting of afiller,an additive,and a matrix)made by adding a third compound,usually functionalized additives,can overcome the structural problems of binary phase MMMs and positively impact membrane separation performance.This review introduces the structure and fabrication processes for ternary MMMs,categorizes various nanofillers and the third component,and summarizes and analyzes in detail the CO_(2) separation performance of newly developed ternary MMMs based on both rubbery and glassy polymers.Based on this separation data,the challenges of ternary MMMs are also discussed.Finally,future directions for ternary MMMs are proposed.
基金supported by the Fundamental Research Funds for the Central Universities(Nos.2018B19714 and 2019B02614)Natural Science Foundation of China(No.51775253)supported by the Department of Energy,Division of Materials Sciences&Engineering(No.DE-AC0207CH11358)。
文摘As a significant semiconductor,nickel selenide shows enormous potential and extensive application pro spects in the field of sensor,photocatalysis and supercapacito r.In this paper,nickel selenide(Ni3Se2,NiSe) thin films were successfully fabricated on stainless-steel sheet using a facile,effective electrodeposition technique.The morphologies,microstructures and chemical compositions of the thin films are characterized systematically.Electrochemical tests exhibit that the Ni3Se2 and NiSe possess high specific capacitance of 581.1 F/g and 1644.7 F/g,respectively.A flexible,all-solid-state asymmetric supercapacitor is assembled by utilizing NiSe film as positive electrode and activated carbon as negative electrode.The solid device delivers a high areal capacitance of 27.0 mF/cm2 at the current density of 0.7 mA/cm2.The maximum volumetric energy density and powerdensity of the NiSe//AC asymmetric SCs can achieve 0.26 mWh/cm3 and 33.35 mW/cm3,respectively.The device shows robust cycling stability with 84.6% capacitance retention after 10,000 cycles,outstanding flexibility and satis factory mechanical stability.Moreover,two devices in series can light up a red light-emitting diode,which displayed great potential applications for energy storage.
基金supported by the U.S.Department of Energy(DOE),Office of Basic Energy Sciences,Division of Chemical Sciences,Geosciences,and Biosciences through a DOE Early Career Project(FAP and ALP).Molecular dynamics calculations(DJL)were supported by the Ames Laboratory Chemical Physics program and synthesis(ADS and UK)by the Ames Laboratory Catalysis program.Ames Laboratory is operated for the DOE by Iowa State University under Contract No.DE-AC02-07CH11358Initial work for FAP was supported by an Ames Laboratory Laboratory-Directed Research and Development(LDRD)program.
文摘Dynamics are intricately linked with activity and selectivity when it comes to catalysis,as noted for instance in the enzymatic principles of induced fit and allostery,and yet the range of motions heterogeneous catalytic sites are able to undergo is poorly understood.Solid-state nuclear magnetic resonance(NMR)spectroscopy is perhaps the only tool capable of probing the rapid conformational dynamics found in heterogeneous catalysts but has historically been restricted by its low sensitivity,limiting the detail with which structures can be resolved.Here,we apply solid-state NMR and dynamic nuclear polarization,in combination with density functional theory modeling,to reveal the high-resolution structure and motional freedom of a scandium supported complex in three dimensions.The results are contrasted with the study of the analogous homoleptic complex in the crystalline state,highlighting the impacts that surface structure may have on the dynamics of supported complexes.
基金Financial support from the National Science Foundation(DMR-1944551)CAREER award is gratefully acknowledgedsupported by the U.S.Department of Energy(DOE),Office of Science,Basic Energy Sciences,Materials Science and Engineering Division+5 种基金The Ames Laboratory is operated for the U.S.Department of Energy by Iowa State University under contract#DE-AC02-07CH11358supported by the U.S.Department of Energy(DOE),Office of Science,Basic Energy Sciences,Materials Science and Engineering Division including a grant of computer time at the National Energy Research Scientific Computing Centre(NERSC)in Berkeley,CAsupported by NSF Awards No.EAR-1918134 and No.EAR-1918126supported by NSF Awards No.EAR-1918134supported by the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant GBMF4411Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under contract no.DE-AC02-06CH11357.
文摘Here we show the effect of Li chemical pressure on the structure of layered polymorphs with LiNiB composition:RT-LiNiB(room temperature polymorph)and HT-LiNiB(high temperature polymorph),resulting in stabilization of the novel RT-Li_(1+x)NiB(x∼0.17)and HT-Li_(1+y)NiB(y∼0.06)phases.Depending on the synthesis temperature and initial Li content,precisely controlled via hydride route synthesis,[NiB]layers undergo structural deformations,allowing for extra Li atoms to be accommodated between the layers.In situ variable temperature synchrotron and time-dependent laboratory powder X-ray diffraction studies suggest Li step-wise deintercalation processes:RT-Li_(1+x)NiB→RT-LiNiB(high temp.)→LiNi_(3)B_(1.8)→binary Ni borides and HT-Li_(1+y)NiB→HT-LiNiB(high temp.)→LiNi_(3)B_(1.8)→binary Ni borides.Quantum chemistry calculations and solid state^(7)Li and^(11)B NMR spectroscopy shed light on the complexity of real superstructures of these compounds determined from high resolution synchrotron powder diffraction data.
文摘Fast-neutron （FN） irradiation has been used to create mutagen- ized collections of many plant species （Bolon et al., 2014）, FN- induced mutagenesis has clear advantages： it is an efficient means of saturating the genome, and it does not involve time- consuming plant transformation or tissue culture. In rice, most mutant collections, although highly valuable, were generated us- ing either T-DNA insertion or transposon tagging approaches that often induce mutations unlinked to the insertion and complicating analysis （Wang et al., 2013）. Another disadvantage of some of these collections is that they were created in rice varieties that are photoperiod-sensitive and often have long generation times.
