Six rearranged nor-diterpenoids with 5/6/6-fused tricyclic system(1–6),and one unprecedented dimer with 5/6/6/6/6/5-fused carbon core(7)were isolated from Strophioblachia glandulosa.Spectroscopic techniques,electroni...Six rearranged nor-diterpenoids with 5/6/6-fused tricyclic system(1–6),and one unprecedented dimer with 5/6/6/6/6/5-fused carbon core(7)were isolated from Strophioblachia glandulosa.Spectroscopic techniques,electronic circular dichroism(ECD),quantum chemical calculations,and single-crystal X-ray diffraction analysis were used to elucidate their structures.A preliminary bioactivity assay revealed compounds 2 and 3 exhibited potent anti-myocardial hypertrophy effect in vitro by significantly inhibiting the expression levels of atrial natriuretic peptide(ANP)and myosin heavy chain 7(MYH7)proteins.Additionally,mitogen-activated protein kinase 14(Mapk14)may be involved in the regulation of compound3 on cardiac hypertrophic disease by network pharmacology prediction and experimental verification.展开更多
The research on metal dimer clusters is of great importance,owing to the potential in modulating the adsorption behavior towards reaction intermediates.Here,we develop a loading heightening strategy to obtain a 32.5wt...The research on metal dimer clusters is of great importance,owing to the potential in modulating the adsorption behavior towards reaction intermediates.Here,we develop a loading heightening strategy to obtain a 32.5wt%Fe-dimer catalyst(Fe-32.5).The co-anchoring of two Fe atoms in a single triazine ring of carbon nitride with an atomic spacing of∼0.23nm is proved.Fe atoms occupy the pores of the triazine ring in the lower iron content sample(Fe-12.9 and Fe-17.1).However,with the increase of iron content to 32.5wt%,two Fe atoms simultaneously occupy one triazine ring.For Fe-32.5,besides the main peak located at∼1.5Åcorresponding to the Fe–N interaction,a peak attributed to Fe–Fe bonding is observed at∼2.2Åin Fourier-transformed k3-weithted extended X-ray absorption fine structure.Density functional theoretical calculations reveal that Fe-dimer in Fe-32.5 induces a charge redistribution compared with that in Fe-12.9 and Fe-17.1.H_(2)O^(∗)is adsorbed on O^(∗)via hydrogen bonding in Fe-12.9 and Fe-17.1.However,H_(2)O^(∗)and O^(∗)in Fe-32.5 are adsorbed on Fe–Fe dimer,resulting in a decrease in the total energy of the reaction process.For the two former,O_(2)^(-)∗adsorbs on individual Fe atoms.Fe-dimer in Fe-32.5 adsorbs O_(2)^(-)∗in the form of bridge bonds,which facilitates the·O_(2)^(-)release.Furthermore,an enhanced affinity for the substrate 3,3′,5,5′-tetramethylbenzidine and higher peroxidase-like activity were displayed.This work provides an effective mean to synthesize metal dimer clusters through high loading.展开更多
Exploring a new and robust material for proton conduction is of significant importance to the scientific interest and technological importance.Polyoxometalates(POMs)are a class of molecular anion metal oxide clusters ...Exploring a new and robust material for proton conduction is of significant importance to the scientific interest and technological importance.Polyoxometalates(POMs)are a class of molecular anion metal oxide clusters with well-defined structures and diverse properties.Therefore,the design and synthesis of a POM-based material for proton conduction is extremely vital.Herein,a dimeric four tartaric acid-bridged tetra-Zr-incorporated arsenotungstate.展开更多
Biocompatible amphiphilic nanoparticles(NPs)with tunable particle morphology and surface property are important for their applications as functional materials.However,previously developed methods to prepare amphiphili...Biocompatible amphiphilic nanoparticles(NPs)with tunable particle morphology and surface property are important for their applications as functional materials.However,previously developed methods to prepare amphiphilic NPs generally involve several steps,especially an additional step for surface modification,greatly hindering their largescale production and widespread applications.Here,a versatile one-step strategy is developed to prepare biocompatible amphiphilic dimer NPs with tunable particle morphology and surface property.The amphiphilic dimer NPs,which consist of a hydrophobic shellac bulb and a hydrophilic poly(lactic acid)(PLA)bulb with PLA-poly(ethylene glycol)(PEG)on the bulb surface,are prepared in a single step by controlled co-precipitation and self-assembly.Amphiphilic PLA-PEG/shellac dimer NPs demonstrate excellent tunability in particle morphology,thus showing good performances in controlling the interfacial curvature and emulsion type.In addition,temperatureresponsive PLA-poly(N-isopropyl acrylamide)(PNIPAM)/shellac dimer NPs are prepared following the same method and emulsions stabilized by them show temperature-triggered response.The applications of PLA-PEG-folic acid(FA)/shellac dimer NPs for drug delivery have also been demonstrated,which show a very good performance.The strategy of preparing the dimer NPs is green,scalable,facile and versatile,which provides a good platform for the design of dimer NPs with tunable particle morphology and surface property for diverse applications.展开更多
We compared a range of BODIPY dimer derivatives without installing blocking groups by optimizing geometry structures and analyzing energies,frontier mo-lecular orbitals,Chole&Cele map,electron density difference,s...We compared a range of BODIPY dimer derivatives without installing blocking groups by optimizing geometry structures and analyzing energies,frontier mo-lecular orbitals,Chole&Cele map,electron density difference,spin-orbit coupling(SOC)matrix and decay rate constants from excited states.The dihedral angles of theβ-β-linked BODIPY dimer and theα-α-linked BODIPY dimer tend to flatten in the T_(1)state,which is detrimental to the occurrence of the intersystem crossing(ISC).Conversely,the dihedral angle of the meso-β-linked BODIPY dimer,the meso-meso-linked BODIPY dimer andα-γ-linked BODIPY dimer is within the range of 125°-143°in the T_(1)state,facilitating ISC and the generation of singlet oxygen.Notably,the transition from S1 to S0 involving lowest unoccupied mo-lecular orbital to highest occupied molecular orbital with long-wavelength emis-sion and moderate oscillator strength underpins the remarkable long emission peaks observed experimentally forα-γ-linked BODIPY dimer.Moreover,the apparent SOC matrix enhances the ISC process,resulting in a respectable effi-ciency in generating singlet oxygen for this dimer.In meso-β-linked BODIPY,meso-meso-linked BODIPY,andα-γ-linked BODIPY,the S_(1)→T_(1)process is characterized by a significant charge transfer,specifically transitioning from the^(1)CT state to the^(3)LE state,indicative of a spin-orbit charge transfer ISC(SOCTISC)mechanism.The ability to regulate the photosensitivity of BODIPY dimers by adjusting the dihedral angle between the two units in the T_(1)state unveils new avenues for designing high-performance photosensitizers for both therapeutic and imaging applications.展开更多
In continuation of research aimed at identifying anti-inflammatory agents from natural sesquiterpenoids,an activity-guided fractionation approach utilizing lipopolysaccharide(LPS)-mediated RAW264.7 cells was employed ...In continuation of research aimed at identifying anti-inflammatory agents from natural sesquiterpenoids,an activity-guided fractionation approach utilizing lipopolysaccharide(LPS)-mediated RAW264.7 cells was employed to investigate chemical constituents from Inula Britannica(I.britannica).Seven novel sesquiterpenoid dimers inulabritanoids A−G(1−7)and two novel sesquiterpenoid monomers inulabritanoids H(8)and I(9)were isolated from I.britannica together with eighteen known compounds(10−27).The structural elucidation was accomplished through comprehensive analysis of 1D and 2D nuclear magnetic resonance(NMR),high-resolution mass spectrometry(HR-MS),and electronic circular dichroism(ECD)spectra,complemented by quantum chemical calculations.Compounds 1,2,12,16,19,and 26 demonstrated inhibitory effects on NO production,with IC50 values of 3.65,5.48,3.29,6.91,3.12,and 5.67μmol·L^(−1),respectively.Mechanistic studies revealed that compound 1 inhibited IκB kinaseβ(IKKβ)phosphorylation,thereby blocking nuclear factorκB(NF-κB)nuclear translocation,and activated the kelch-like ECH-associated protein 1(Keap1)/nuclear factor erythroid 2-related factor 2(Nrf2)signal pathway,leading to decreased expression of NADPH oxidase 2(NOX-2),inducible nitric oxide synthase(iNOS),tumor necrosis factorα(TNF-α),interleukin-6(IL-6),monocyte chemotactic protein-1(MCP-1),IL-1β,and IL-1αand increased expression of NAD(P)H:quinone oxidoreductase 1(NQO-1)and heme oxygenase-1(HO-1),thus exhibiting anti-inflammatory effects in vitro.These results indicate that dimeric sesquiterpenoids may serve as promising candidates for anti-inflammatory drug development.展开更多
Manipulating catalyst structures to control product selectivity while maintaining high activity presents a considerable challenge in CO_(2)hydrogenation.Combining density functional theory calculations and microkineti...Manipulating catalyst structures to control product selectivity while maintaining high activity presents a considerable challenge in CO_(2)hydrogenation.Combining density functional theory calculations and microkinetic analysis,we proposed that graphene-supported isolated Pt atoms(Pt1/graphene)and Pt_(2)dimers(Pt_(2)/graphene)exhibited distinct selectivity in CO_(2)hydrogenation.Pt_(1)/graphene facilitated the conversion of CO_(2)into formic acid,whereas Pt_(2)/graphene favored methanol generation.The variation in product selectivity arose from the synergistic interaction of Pt_(2)dimers,which facilitated the migration of H atoms between two Pt atoms and promoted the transformation from*COOH intermediates to*C(OH)_(2)intermediates,altering the reaction pathways compared to isolated Pt atoms.Additionally,an analysis of the catalytic activities of three Pt_(1)/graphene and three Pt_(2)/graphene structures revealed that the turnover frequencies for formic acid generation on Pt_(1ii)/graphene and methanol generation on Pt_(2i)/graphene were as high as 744.48 h-1and 789.48 h^(-1),respectively.These values rivaled or even surpassed those previously reported in the literature under identical conditions.This study provides valuable insights into optimizing catalyst structures to achieve desired products in CO_(2)hydrogenation.展开更多
We investigate the quantum dynamics of the 1D spinless Fermi-Hubbard model with a linear-tilted potential.Surprisingly in a strong resonance regime,we show that the model can be described by the kinetically constraine...We investigate the quantum dynamics of the 1D spinless Fermi-Hubbard model with a linear-tilted potential.Surprisingly in a strong resonance regime,we show that the model can be described by the kinetically constrained effective Hamiltonian,and it can be spontaneously divided into two commuting parts dubbed Hamiltonian dimerization,which are composed of two distinct sets of constrained nearest-neighbor hopping terms:one set acting exclusively on odd bonds and the other on even bonds.Specifically it is shown that each part can be independently mapped onto the well-known PXP model;therefore the dimerized Hamiltonian is equivalent to a two-fold PXP model.As a consequence,we numerically demonstrate this system can host the so-called quantum many-body scars,which present dynamical revivals and ergodicity-breaking behaviors.However,in sharp contrast with traditional quantum many-body scars,here the scarring states in our model driven by different parts of the Hamiltonian will revive in different periods,and those of double parts can display a biperiodic revival pattern,both originating from the Hamiltonian dimerization.Besides,the condition of off-resonance is also discussed,and we show the crossover from quantum many-body scar to ergodicity breaking is diagnosed via level statistics.Our model provides a platform for understanding the interplay of Hilbert space fragmentation and the constrained quantum systems.展开更多
Two racemic pairs of new stilbenoid dimers,(±)-heterosmilaxones A(1)and B(2),with unique 6/6/6and 6/5/7 tricyclic core systems,respectively,were isolated from the rhizomes of Heterosmilax yunnanensis.Their struct...Two racemic pairs of new stilbenoid dimers,(±)-heterosmilaxones A(1)and B(2),with unique 6/6/6and 6/5/7 tricyclic core systems,respectively,were isolated from the rhizomes of Heterosmilax yunnanensis.Their structures were elucidated through comprehensive spectroscopic analyses,quantum chemical calculations and X-ray diffraction crystallography.Compound(+)-1,initially reported as syagrusin A with a 1,4,4a,9a-tetrahydrofluoren-9-one skeleton,is now revised to a new structure characteristic with a benzo bicyclo[3.3.1]nonene scaffold.And compound 2 bears an unprecedented carbon skeleton with four continuous chiral centers in the central benzo bicyclo[4.2.1]nonene motif.Biogenetically,both 1 and2 were proposed to derive from 3,3',4,5,5'-pentahydroxy stilbene and could be generated through key inverse-electron-demand[4+2]and[5+2]cycloadditions,respectively.Interestingly,both(±)-1 and(±)-2 showed significant inhibition againstα-glucosidase.(±)-1 and its pure enantiomers could modulate protein tyrosine phosphatase-1B(PTP1B)enzyme activities and increased glucose consumption in HepG2 cells in a dose-dependent manner.展开更多
Decoupling electrical and thermal properties to enhance the figure of merit of thermoelectric materials underscores an in-depth understanding of the mechanisms that govern the transfer of charge carriers.Typically,a f...Decoupling electrical and thermal properties to enhance the figure of merit of thermoelectric materials underscores an in-depth understanding of the mechanisms that govern the transfer of charge carriers.Typically,a factor that contributes to the optimization of thermal conductivity is often found to be detrimental to the electrical transport properties.Here,we systematically investigated 26 dimeric MX_(2)-type compounds(where M represents a metal and X represents a nonmetal element)to explore the influence of the electronic configurations of metal cations on lattice thermal transport and thermoelectric performance using first-principles calculations.A principled scheme has been identified that the filled outer orbitals of the cation lead to a significantly lower lattice thermal conductivity compared to that of the partly occupied case for MX_(2),due to the much weakened bonds manifested by the shallow potential well,smaller interatomic force constants,and higher atomic displacement parameters.Based on these findings,we propose two ionic compounds,BaAs and BaSe_(2),to realize reasonable high electrical conductivities through the structural anisotropy caused by the inserted covalent X_(2) dimers while still maintaining the large lattice anharmonicity.The combined superior electrical and thermal properties of BaSe_(2) lead to a high n-type thermoelectric ZT value of 2.3 at 500 K.This work clarifies the structural origin of the heat transport properties of dimeric MX_(2)-type compounds and provides an insightful strategy for developing promising thermoelectric materials.展开更多
基金supported financially by the National Natural Science Foundation of China(Nos.82260682,22477108,81960662,82200550)the Project of Yunnan Characteristic Plant Screening and R&D Service CXO Platform(No.2022YKZY001)+9 种基金the Yunnan Provincial Science and Technology Department(Nos.202101AT070154,202301AT0–70270 and 202401AY070001–303)the Scientific Research Fund Project of Yunnan Provincial Department of Education(No.2023Y0–797)the Program Innovative Research Team in Science and Technology in Kunming Medical University(No.CXTD202202)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT-17R94)the Project of Innovative Research Team of Yunnan Province(No.202005AE160005)the Open Research Foundation of Yunnan Key Laboratory of Bioactive Peptides in Yunnan Province(No.HXDT-2022–1)a grant(No.2023KF007)from YNCUBFirst-Class Discipline Team of Kunming Medical University(No.2024XKTDPY12)Yunnan Revitalization Talent Support Programthe Yun Ling Scholar Project to W.-L.Xiao。
文摘Six rearranged nor-diterpenoids with 5/6/6-fused tricyclic system(1–6),and one unprecedented dimer with 5/6/6/6/6/5-fused carbon core(7)were isolated from Strophioblachia glandulosa.Spectroscopic techniques,electronic circular dichroism(ECD),quantum chemical calculations,and single-crystal X-ray diffraction analysis were used to elucidate their structures.A preliminary bioactivity assay revealed compounds 2 and 3 exhibited potent anti-myocardial hypertrophy effect in vitro by significantly inhibiting the expression levels of atrial natriuretic peptide(ANP)and myosin heavy chain 7(MYH7)proteins.Additionally,mitogen-activated protein kinase 14(Mapk14)may be involved in the regulation of compound3 on cardiac hypertrophic disease by network pharmacology prediction and experimental verification.
基金financially supported by National Natural Science Foundation of China(No.52301011)Hainan Provincial Natural Science Foundation of China(No.524QN226)the Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices,Ministry of Education,Jianghan University(No.JDGD-202315).
文摘The research on metal dimer clusters is of great importance,owing to the potential in modulating the adsorption behavior towards reaction intermediates.Here,we develop a loading heightening strategy to obtain a 32.5wt%Fe-dimer catalyst(Fe-32.5).The co-anchoring of two Fe atoms in a single triazine ring of carbon nitride with an atomic spacing of∼0.23nm is proved.Fe atoms occupy the pores of the triazine ring in the lower iron content sample(Fe-12.9 and Fe-17.1).However,with the increase of iron content to 32.5wt%,two Fe atoms simultaneously occupy one triazine ring.For Fe-32.5,besides the main peak located at∼1.5Åcorresponding to the Fe–N interaction,a peak attributed to Fe–Fe bonding is observed at∼2.2Åin Fourier-transformed k3-weithted extended X-ray absorption fine structure.Density functional theoretical calculations reveal that Fe-dimer in Fe-32.5 induces a charge redistribution compared with that in Fe-12.9 and Fe-17.1.H_(2)O^(∗)is adsorbed on O^(∗)via hydrogen bonding in Fe-12.9 and Fe-17.1.However,H_(2)O^(∗)and O^(∗)in Fe-32.5 are adsorbed on Fe–Fe dimer,resulting in a decrease in the total energy of the reaction process.For the two former,O_(2)^(-)∗adsorbs on individual Fe atoms.Fe-dimer in Fe-32.5 adsorbs O_(2)^(-)∗in the form of bridge bonds,which facilitates the·O_(2)^(-)release.Furthermore,an enhanced affinity for the substrate 3,3′,5,5′-tetramethylbenzidine and higher peroxidase-like activity were displayed.This work provides an effective mean to synthesize metal dimer clusters through high loading.
基金supported by the National Natural Science Foundation of China(Nos.22071043 and 22203027)Shanxi Province Science Foundation(No.202303021211194)the program for the(Reserved)Discipline Leaders of Taiyuan Institute of Technology.
文摘Exploring a new and robust material for proton conduction is of significant importance to the scientific interest and technological importance.Polyoxometalates(POMs)are a class of molecular anion metal oxide clusters with well-defined structures and diverse properties.Therefore,the design and synthesis of a POM-based material for proton conduction is extremely vital.Herein,a dimeric four tartaric acid-bridged tetra-Zr-incorporated arsenotungstate.
基金supported by National Natural Science Foundation of China(No.22278352)National Key Research and Development Program of China(No.2021YFC3001100)+3 种基金Longyan City Science and Technology Plan Project(No.2020LYF17043)Longyan City Science and Technology Plan Project(No.2020LYF17042)ARC Discovery Project(No.DP200101238)and NHMRC Investigator Grant(No.APP2008698)supported by the Harvard Materials Research Science and Engineering Center(No.DMR2011754)。
文摘Biocompatible amphiphilic nanoparticles(NPs)with tunable particle morphology and surface property are important for their applications as functional materials.However,previously developed methods to prepare amphiphilic NPs generally involve several steps,especially an additional step for surface modification,greatly hindering their largescale production and widespread applications.Here,a versatile one-step strategy is developed to prepare biocompatible amphiphilic dimer NPs with tunable particle morphology and surface property.The amphiphilic dimer NPs,which consist of a hydrophobic shellac bulb and a hydrophilic poly(lactic acid)(PLA)bulb with PLA-poly(ethylene glycol)(PEG)on the bulb surface,are prepared in a single step by controlled co-precipitation and self-assembly.Amphiphilic PLA-PEG/shellac dimer NPs demonstrate excellent tunability in particle morphology,thus showing good performances in controlling the interfacial curvature and emulsion type.In addition,temperatureresponsive PLA-poly(N-isopropyl acrylamide)(PNIPAM)/shellac dimer NPs are prepared following the same method and emulsions stabilized by them show temperature-triggered response.The applications of PLA-PEG-folic acid(FA)/shellac dimer NPs for drug delivery have also been demonstrated,which show a very good performance.The strategy of preparing the dimer NPs is green,scalable,facile and versatile,which provides a good platform for the design of dimer NPs with tunable particle morphology and surface property for diverse applications.
基金financially supported by the Fundamental Research Funds for the Central Universities(DUT20RC(3)076)Natural Science Foundation of Liaoning Province(2020-MS-293).Thanks Shuoqi Sun from HZWTECH for help and discussions regarding this study.
文摘We compared a range of BODIPY dimer derivatives without installing blocking groups by optimizing geometry structures and analyzing energies,frontier mo-lecular orbitals,Chole&Cele map,electron density difference,spin-orbit coupling(SOC)matrix and decay rate constants from excited states.The dihedral angles of theβ-β-linked BODIPY dimer and theα-α-linked BODIPY dimer tend to flatten in the T_(1)state,which is detrimental to the occurrence of the intersystem crossing(ISC).Conversely,the dihedral angle of the meso-β-linked BODIPY dimer,the meso-meso-linked BODIPY dimer andα-γ-linked BODIPY dimer is within the range of 125°-143°in the T_(1)state,facilitating ISC and the generation of singlet oxygen.Notably,the transition from S1 to S0 involving lowest unoccupied mo-lecular orbital to highest occupied molecular orbital with long-wavelength emis-sion and moderate oscillator strength underpins the remarkable long emission peaks observed experimentally forα-γ-linked BODIPY dimer.Moreover,the apparent SOC matrix enhances the ISC process,resulting in a respectable effi-ciency in generating singlet oxygen for this dimer.In meso-β-linked BODIPY,meso-meso-linked BODIPY,andα-γ-linked BODIPY,the S_(1)→T_(1)process is characterized by a significant charge transfer,specifically transitioning from the^(1)CT state to the^(3)LE state,indicative of a spin-orbit charge transfer ISC(SOCTISC)mechanism.The ability to regulate the photosensitivity of BODIPY dimers by adjusting the dihedral angle between the two units in the T_(1)state unveils new avenues for designing high-performance photosensitizers for both therapeutic and imaging applications.
基金supported by the National Natural Science Foundation of China(Nos.82274069,82030116,and 82141212)the Young Scientific and Technological Talents(Level Two)in Tianjin(No.QN20230212)+1 种基金Tianjin Education Commission Research Program Project(No.2024KJ004)the Eaglet Plan Project of Tianjin University of Traditional Chinese Medicine(No.XJS2024101).
文摘In continuation of research aimed at identifying anti-inflammatory agents from natural sesquiterpenoids,an activity-guided fractionation approach utilizing lipopolysaccharide(LPS)-mediated RAW264.7 cells was employed to investigate chemical constituents from Inula Britannica(I.britannica).Seven novel sesquiterpenoid dimers inulabritanoids A−G(1−7)and two novel sesquiterpenoid monomers inulabritanoids H(8)and I(9)were isolated from I.britannica together with eighteen known compounds(10−27).The structural elucidation was accomplished through comprehensive analysis of 1D and 2D nuclear magnetic resonance(NMR),high-resolution mass spectrometry(HR-MS),and electronic circular dichroism(ECD)spectra,complemented by quantum chemical calculations.Compounds 1,2,12,16,19,and 26 demonstrated inhibitory effects on NO production,with IC50 values of 3.65,5.48,3.29,6.91,3.12,and 5.67μmol·L^(−1),respectively.Mechanistic studies revealed that compound 1 inhibited IκB kinaseβ(IKKβ)phosphorylation,thereby blocking nuclear factorκB(NF-κB)nuclear translocation,and activated the kelch-like ECH-associated protein 1(Keap1)/nuclear factor erythroid 2-related factor 2(Nrf2)signal pathway,leading to decreased expression of NADPH oxidase 2(NOX-2),inducible nitric oxide synthase(iNOS),tumor necrosis factorα(TNF-α),interleukin-6(IL-6),monocyte chemotactic protein-1(MCP-1),IL-1β,and IL-1αand increased expression of NAD(P)H:quinone oxidoreductase 1(NQO-1)and heme oxygenase-1(HO-1),thus exhibiting anti-inflammatory effects in vitro.These results indicate that dimeric sesquiterpenoids may serve as promising candidates for anti-inflammatory drug development.
基金supported by the National Key Research and Development Program(No.2022YFA1505800)the National Natural Science Foundation of China(No.22373092)+5 种基金CAS Project for Young Scientists in Basic Research(No.YSBR-051)China Association for Science and Technology(No.YESS20200031)the Start-up Funding of Central South University(No.502045005)Industry-University-Research Cooperation Projects with Zhejiang NHU Co.,Ltd.Ningbo Fengcheng Advanced Energy Materials Research Institutesupported by USTC Tang Scholarship。
文摘Manipulating catalyst structures to control product selectivity while maintaining high activity presents a considerable challenge in CO_(2)hydrogenation.Combining density functional theory calculations and microkinetic analysis,we proposed that graphene-supported isolated Pt atoms(Pt1/graphene)and Pt_(2)dimers(Pt_(2)/graphene)exhibited distinct selectivity in CO_(2)hydrogenation.Pt_(1)/graphene facilitated the conversion of CO_(2)into formic acid,whereas Pt_(2)/graphene favored methanol generation.The variation in product selectivity arose from the synergistic interaction of Pt_(2)dimers,which facilitated the migration of H atoms between two Pt atoms and promoted the transformation from*COOH intermediates to*C(OH)_(2)intermediates,altering the reaction pathways compared to isolated Pt atoms.Additionally,an analysis of the catalytic activities of three Pt_(1)/graphene and three Pt_(2)/graphene structures revealed that the turnover frequencies for formic acid generation on Pt_(1ii)/graphene and methanol generation on Pt_(2i)/graphene were as high as 744.48 h-1and 789.48 h^(-1),respectively.These values rivaled or even surpassed those previously reported in the literature under identical conditions.This study provides valuable insights into optimizing catalyst structures to achieve desired products in CO_(2)hydrogenation.
基金supported by the National Key R&D Program of China(Grant No.2023YFA1406002)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301200)。
文摘We investigate the quantum dynamics of the 1D spinless Fermi-Hubbard model with a linear-tilted potential.Surprisingly in a strong resonance regime,we show that the model can be described by the kinetically constrained effective Hamiltonian,and it can be spontaneously divided into two commuting parts dubbed Hamiltonian dimerization,which are composed of two distinct sets of constrained nearest-neighbor hopping terms:one set acting exclusively on odd bonds and the other on even bonds.Specifically it is shown that each part can be independently mapped onto the well-known PXP model;therefore the dimerized Hamiltonian is equivalent to a two-fold PXP model.As a consequence,we numerically demonstrate this system can host the so-called quantum many-body scars,which present dynamical revivals and ergodicity-breaking behaviors.However,in sharp contrast with traditional quantum many-body scars,here the scarring states in our model driven by different parts of the Hamiltonian will revive in different periods,and those of double parts can display a biperiodic revival pattern,both originating from the Hamiltonian dimerization.Besides,the condition of off-resonance is also discussed,and we show the crossover from quantum many-body scar to ergodicity breaking is diagnosed via level statistics.Our model provides a platform for understanding the interplay of Hilbert space fragmentation and the constrained quantum systems.
基金financially supported by the CAMS Innovation Fund for Medical Sciences(CIFMS,No.2021-I2M-1-028)。
文摘Two racemic pairs of new stilbenoid dimers,(±)-heterosmilaxones A(1)and B(2),with unique 6/6/6and 6/5/7 tricyclic core systems,respectively,were isolated from the rhizomes of Heterosmilax yunnanensis.Their structures were elucidated through comprehensive spectroscopic analyses,quantum chemical calculations and X-ray diffraction crystallography.Compound(+)-1,initially reported as syagrusin A with a 1,4,4a,9a-tetrahydrofluoren-9-one skeleton,is now revised to a new structure characteristic with a benzo bicyclo[3.3.1]nonene scaffold.And compound 2 bears an unprecedented carbon skeleton with four continuous chiral centers in the central benzo bicyclo[4.2.1]nonene motif.Biogenetically,both 1 and2 were proposed to derive from 3,3',4,5,5'-pentahydroxy stilbene and could be generated through key inverse-electron-demand[4+2]and[5+2]cycloadditions,respectively.Interestingly,both(±)-1 and(±)-2 showed significant inhibition againstα-glucosidase.(±)-1 and its pure enantiomers could modulate protein tyrosine phosphatase-1B(PTP1B)enzyme activities and increased glucose consumption in HepG2 cells in a dose-dependent manner.
基金financial support from the Natural Science Foundation of China(No.11904089,12174092,11674087)the Overseas Expertise Introduction Center for Discipline Innovation(D18025)+1 种基金the Program for Key Research and Development of Science and Technology in Hubei Province(grant No.2023BEB002)supported by the Young Science Foundation of Hubei University(Grant No.430/184303000047).
文摘Decoupling electrical and thermal properties to enhance the figure of merit of thermoelectric materials underscores an in-depth understanding of the mechanisms that govern the transfer of charge carriers.Typically,a factor that contributes to the optimization of thermal conductivity is often found to be detrimental to the electrical transport properties.Here,we systematically investigated 26 dimeric MX_(2)-type compounds(where M represents a metal and X represents a nonmetal element)to explore the influence of the electronic configurations of metal cations on lattice thermal transport and thermoelectric performance using first-principles calculations.A principled scheme has been identified that the filled outer orbitals of the cation lead to a significantly lower lattice thermal conductivity compared to that of the partly occupied case for MX_(2),due to the much weakened bonds manifested by the shallow potential well,smaller interatomic force constants,and higher atomic displacement parameters.Based on these findings,we propose two ionic compounds,BaAs and BaSe_(2),to realize reasonable high electrical conductivities through the structural anisotropy caused by the inserted covalent X_(2) dimers while still maintaining the large lattice anharmonicity.The combined superior electrical and thermal properties of BaSe_(2) lead to a high n-type thermoelectric ZT value of 2.3 at 500 K.This work clarifies the structural origin of the heat transport properties of dimeric MX_(2)-type compounds and provides an insightful strategy for developing promising thermoelectric materials.
