This paper studies a spin ladder model which possesses frustrating interactions. By using both the bosonization and the density matrix renormalization group techniques, it shows that the intermediate columnar dimerize...This paper studies a spin ladder model which possesses frustrating interactions. By using both the bosonization and the density matrix renormalization group techniques, it shows that the intermediate columnar dimerized phase, which exists in a narrow parameter region of the so-called ~/1 - J2 model, vanishes if the interchain frustration is weak and anisotropic. Therefore, it concludes that the frustrating interaction indeed plays an important role in producing such a phase. As a complementary to our previous investigation, it reaches a more complete picture of the quantum phase transition in the frustrated spin ladder systems.展开更多
Entanglement transfer is investigated in a dimerized Heisenberg system. Concurrence as the measure of entanglement is calculated by the time-evolved state starting from an initially entangled state of spin pair. It is...Entanglement transfer is investigated in a dimerized Heisenberg system. Concurrence as the measure of entanglement is calculated by the time-evolved state starting from an initially entangled state of spin pair. It is shown that perfect entanglement transfer can be realized at some special time and suitable interacting.展开更多
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
We study the multistability of fixed points for a dimerized system of Rydberg atoms driven by two laser fields and trapped in a two-dimensional(2D)square lattice.For identical driving fields,the fixed points of this s...We study the multistability of fixed points for a dimerized system of Rydberg atoms driven by two laser fields and trapped in a two-dimensional(2D)square lattice.For identical driving fields,the fixed points of this system exhibit stable uniform,unstable uniform,stable nonuniform,or oscillating nonuniform phases in the presence of a bistable region.For different driving fields,however,all(stable,unstable,or oscillating)phases become nonuniform instead,which then results in two islets isolated from the mainland of Rydberg excitation.We also show that a tristable region may stretch out from the(nonuniform)bistable region near the islets,indicating that a richer phase diagram can be attained by tuning the Rabi frequencies and/or detunings of the driving fields.Last but not least,the fixed points can adiabatically evolve from the islets to the mainland but can not inversely evolve from the mainland to the islets.展开更多
Multi-site coupling is a promising strategy for developing highly efficient and CO-resistant hydrogen oxidation reaction(HOR)catalysts for proton exchange membrane fuel cells(PEMFCs).However,designing multifunctional ...Multi-site coupling is a promising strategy for developing highly efficient and CO-resistant hydrogen oxidation reaction(HOR)catalysts for proton exchange membrane fuel cells(PEMFCs).However,designing multifunctional synergistic schemes for single-atom sites remains a significant challenge.Herein,we propose a dual-template-confined oxophilic engineering strategy to construct well-dispersed iridium-nickel(IrNi)atomic dimers adjacent to IrNi nanoclusters on porous nitrogen-doped carbon(IrNi_(Dimer/NC1.8)-PNC).The paired IrNi dimer features an asymmetric Ir-N_(3)configuration coordinated with heteroatomic Ni-N_(3)O via an N-bridge.Remarkably,IrNi_(Dimer/NC1.8)-PNC exhibits a~23-fold enhancement in mass activity(4.36 A mg-1Ir at 20 mV)and 5-fold longer stability compared to benchmarking Pt/C toward HOR,while achieving a high rated power density of 1.18 W cm^(-2)in PEMFC anode applications.Furthermore,IrNi_(Dimer/NC1.8)-PNC demonstrates superior CO tolerance over monometallic Ir and Pt/C in both half-cell and full-cell devices.Combined experimental and density functional theory studies reveal that oxophilic Ni modulates the electronic environment of Ir through alloying and dimer interactions,thereby enhancing HOR activity.Importantly,the asymmetric IrNi dimer enables efficient CO^(*)and OH^(*)co-adsorption while facilitating CO_(2)^(*)desorption,synergistically mitigating CO poisoning and improving atom utilization efficiency.This work provides a design strategy and fundamental insights for multi-site synergistic catalysts in PEMFC anodes.展开更多
The viscoelastic micelle systems formed by novel anionic-nonionic dimeric surfactant and conventional cationic surfactant cetyltrimethylammonium(1631) were studied.The viscoelasticity,thixotropy,flow curves and consti...The viscoelastic micelle systems formed by novel anionic-nonionic dimeric surfactant and conventional cationic surfactant cetyltrimethylammonium(1631) were studied.The viscoelasticity,thixotropy,flow curves and constitutive equation for the novel viscoelastic micelle systems were investigated.The results show that the micelle systems possess viscoelasticity,thixotropy,and shear thinning property.Some micelle systems possess hysteresis loops showing both viscoelasticity and thixotropy.It is proved that the flow curves are characterized by the co-rotational Jeffreys constitutive equation correctly.展开更多
In this paper, we study the phase diagram of a frustrated spin ladder model by applying the bosonization technique and the density-matrix renormalization-group （DMRG） algorithm. Effect of the intra-ehain next-neares...In this paper, we study the phase diagram of a frustrated spin ladder model by applying the bosonization technique and the density-matrix renormalization-group （DMRG） algorithm. Effect of the intra-ehain next-nearest- neighbor （NNN） super-exchange interaction is investigated in detail and the order parameters are calculated to detect the emergence of the dimerized phases. We find that the intra-chain NNN interaction plays a key role in inducing dimerized phases.展开更多
In order to gain a deeper understanding of the quantum criticality in the explicitly staggered dimerized Heisenberg models, we study a generalized staggered dimer model named the J0 J1 J2 model, which corresponds to t...In order to gain a deeper understanding of the quantum criticality in the explicitly staggered dimerized Heisenberg models, we study a generalized staggered dimer model named the J0 J1 J2 model, which corresponds to the staggered j-j′ model on a square lattice and a honeycomb lattice when J1/J0 equals 1 and O, respectively. Using the quantum Monte Carlo method, we investigate all the quantum critical points of these models with J1/J0 changing from 0 to 1 as a function of coupling ratio a = J2/J0. We extract all the critical values of the coupling ratio ac for these models, and we also obtain the critical exponents v,β/ν, and η using different finite-size scaling ansatz,. All these exponents are not consistent with the three-dimensional Heisenberg universality class, indicating some unconventional quantum ciriteial points in these models.展开更多
The construction of all-carbon molecule frameworks remains challenging. Herein, we report a facile and efficient one-pot synthesis of a novel all-carbon stair containing dimerized pentalene core using inexpensive cycl...The construction of all-carbon molecule frameworks remains challenging. Herein, we report a facile and efficient one-pot synthesis of a novel all-carbon stair containing dimerized pentalene core using inexpensive cyclopropyl alkyne catalyzed by in situ generated Cu(I) from the comproportionation reaction of Cu(II) salt and Cu powder under mild reaction conditions. The reaction proceeds via sequential acetylenic coupling, followed by cyclization and [2 + 2] cycloaddition to directly produce pentalene dimer, which is difficult to access by other established methods. Different mechanistic paths were studied for the pentalene formation using density functional theory, suggesting that the reaction also proceeds through acetylenic coupling followed by cyclization and [2 + 2] cycloaddition. Based on the activation energy barriers, Path 1 has the rate-determining step of 38.63 kcal/mol, which is the most thermodynamically preferred one among the four paths.展开更多
The quasi-one-dimensional spin-Peierls(SP)systems with impurities are studied in their bosonized form.The spins of the dimerized state are bounded into singlets with an SP gap,while the impurities of doped systems wil...The quasi-one-dimensional spin-Peierls(SP)systems with impurities are studied in their bosonized form.The spins of the dimerized state are bounded into singlets with an SP gap,while the impurities of doped systems will induce fluctuations of the coupling strength between the spins at different sites and break some pairs of spin singlets.The doping suppresses the dimerized SP state and induces a Kosterlitz-Thouless phase transition from the dimerized state into the undimerized one.展开更多
A simple one-dimensional subwavelength plasmonic grating can support symmetry protected bound states in the continuum(BICs),but not necessarily for the non-symmetry protected BICs.By dimerizing the lattice,nonsymmetry...A simple one-dimensional subwavelength plasmonic grating can support symmetry protected bound states in the continuum(BICs),but not necessarily for the non-symmetry protected BICs.By dimerizing the lattice,nonsymmetry protected BIC can be supported on the dimerized grating and can be tuned readily.The mechanism for the BICs in the dimerized grating is interpreted in the viewpoint of interference between the electromagnetic multipoles.展开更多
A mixed drug self-delivery system(DSDS)with high drug content(>50%)was developed to regulate pHtriggered drug release,based on two doxorubicin(DOX)-DOX dimmers:D-DOX_(ADH) and D-DOX_(car) conjugated with acid-labil...A mixed drug self-delivery system(DSDS)with high drug content(>50%)was developed to regulate pHtriggered drug release,based on two doxorubicin(DOX)-DOX dimmers:D-DOX_(ADH) and D-DOX_(car) conjugated with acid-labile dynamic covalent bonds(hydrazone and carbamate,respectively)and stabilized with PEGylated D-DOX_(ADH)(D-DOX_(ADH)-PEG).Owing to the different stability of the dynamic covalent bonds in the two dimers and the noncovalent interaction between them,pH-triggered drug release could be easily regulated by adjusting the feeding ratios of the two DOX-DOX dimers in the mixed DSDS.Similar in vitro cellular toxicity was achieved with the mixed DSDS nanoparticles prepared with different feeding ratios.The mixed DSDS nanoparticles had a similar DOX content and diameter but different drug releasing rates.The MTT assays revealed that a high anti-tumor efficacy could be achieved with the slowrelease mixed DSDS nanoparticles.展开更多
The influences of Dzyaloshinskii Moriya （DM） interaction and Kaplan-Shekhtman-Entinwohlman-Aharony （KSEA） interaction on the dimerization of a spin-Peierls system are investigated theoretically by using the Lanczo...The influences of Dzyaloshinskii Moriya （DM） interaction and Kaplan-Shekhtman-Entinwohlman-Aharony （KSEA） interaction on the dimerization of a spin-Peierls system are investigated theoretically by using the Lanczos numerical method. The ground state of the spin-Peierls system is still dimerized phase when both of the DM and the KSEA interactions have the same value with Heisenberg interaction. It is found that the KSEA interaction and uniform DM interaction are always against systemic dimerization, but the staggered DM interaction acts in favour of dimerization. Furthermore, the influences of the DM and the KSEA interactions are also studied in terms of the ground state index rate and the energy gap index rate of the dimerized Heisenberg system. The results show that the DM interaction makes the index rates larger, while the KSEA interaction makes them smaller.展开更多
On the example of tetraantraquinoporphyrazines—potential photosensitizers for photodynamic therapy, thermodynamic approach to the choice of exogenous transport system was demonstrated. By means of isothermal titratio...On the example of tetraantraquinoporphyrazines—potential photosensitizers for photodynamic therapy, thermodynamic approach to the choice of exogenous transport system was demonstrated. By means of isothermal titration calorimetry and electron absorption spectroscopy, the state of TAP in aqueous solutions was studied. The possibility of aggregation equilibrium displacement due to the pyridine adding was evaluated.展开更多
Tens of thousands of protein-protein interactions (PPIs) have been found in human cells and many of these macromolecular partnerships could determine the cell growth and death. Thus there is a need to develop the meth...Tens of thousands of protein-protein interactions (PPIs) have been found in human cells and many of these macromolecular partnerships could determine the cell growth and death. Thus there is a need to develop the methods to catalogue these macromolecules by detecting their interactions, modifications, and cellular locations. It will be helpful for scientists to compare the difference between a diseased cellular state and its normal state and to find the potential therapy treatment to intervene this status. One technology called split-protein reassembly or protein fragment complementation has been developed in the last two decades. This technology makes use of appropriate fragmentation of some protein reporters and the refolding of these reports could be detected by their function to confirm the interaction of interest. This system has been set up in cell-free systems, </span><i><span style="font-family:Verdana;">E.</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">coli</span></i><span style="font-family:""><span style="font-family:Verdana;">, yeast, mammalian cells, plants and live animals. Herein, I present the development in fluorescence- and bioluminescence-based split-protein biosensors in both binary and ternary systems. In addition, some people developed the split-protein system by combining it with chemical inducer of dimerization strategy (CID). This has been applied for identifying the enzyme inhibitors and regulating the activity of protein kinases and phosphatases. With effort from many laboratories from the world, a variety of split-protein systems have been developed for studying the PPI </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;">, monitoring the biological process, and controlling the activity of the enzyme of interest.展开更多
Green hydrogen from water splitting has emerged as a critical energy vector with the potential to spearhead the global transition to a fossil fuel-independent society.The field of catalysis has been revolutionized by ...Green hydrogen from water splitting has emerged as a critical energy vector with the potential to spearhead the global transition to a fossil fuel-independent society.The field of catalysis has been revolutionized by single-atom catalysts(SACs),which exhibit unique and intricate interactions between atomically dispersed metal atoms and their supports.Recently,bimetallic SACs(bimSACs)have garnered significant attention for leveraging the synergistic functions of two metal ions coordinated on appropriately designed supports.BimSACs offer an avenue for rich metal–metal and metal–support cooperativity,potentially addressing current limitations of SACs in effectively furnishing transformations which involve synchronous proton–electron exchanges,substrate activation with reversible redox cycles,simultaneous multi-electron transfer,regulation of spin states,tuning of electronic properties,and cyclic transition states with low activation energies.This review aims to encapsulate the growing advancements in bimSACs,with an emphasis on their pivotal role in hydrogen generation via water splitting.We subsequently delve into advanced experimental methodologies for the elaborate characterization of SACs,elucidate their electronic properties,and discuss their local coordination environment.Overall,we present comprehensive discussion on the deployment of bimSACs in both hydrogen evolution reaction and oxygen evolution reaction,the two half-reactions of the water electrolysis process.展开更多
Hylocereus polyrhizus,also known as pitaya or dragon fruit,is a climbing cactus grown worldwide because of its excellent performance under drought stress and appealing red-purple fruits.In practice,accelerating flower...Hylocereus polyrhizus,also known as pitaya or dragon fruit,is a climbing cactus grown worldwide because of its excellent performance under drought stress and appealing red-purple fruits.In practice,accelerating flower formation and inducing more flowers usually result in higher yield.However,the genes for this purpose have not been well characterized in pitaya.Previously,FLOWERING BHLHs(FBHs)have been identified as positive regulators of flower formation.In the present work,a total of eight FBHs were identified in pitaya.This is a greater number than in beet and spinach,possibly because of the recent whole-genome duplication that occurred in the pitaya genome.The phylogenetic tree indicated that the FBHs could be divided into three groups.In TYPEⅡ,the genes of Caryophyllales encode atypical FBHs and are generated by dispersed duplication.The K_(a)/K_(s) ratios indicated that HpFBHs are under purifying selection.Promoter and expression analysis of HpFBHs revealed that they are spatiotemporally activated in flower-related tissues and responsive to multiple abiotic stresses.These results indicated that HpFBHs are involved in the flower formation of pitaya.Therefore,typical HpFBH1/3 from TYPEⅡI and an atypical HpFBH8 from TYPEⅡwere selected for functional verification.HpFBH3 was found to heterodimerize with HpFBH1 in the nucleus using subcellular localization,yeast two-hybrid and luciferase complementation assays.With bioinformatic analysis,all HpFBHs were predicted to transactivate downstream genes via binding to the E-boxes,which were frequently detected in the promoters of HpCOs,HpFTs and HpSOC1s.RNA-Seq datasets showed that these flowering accelerators were expressed in coordination with HpFBH3.Yeast one-hybrid and dual-luciferase reporter assays further verified that HpFBH3 transactivated HpCO7 by selectively binding to the E-boxes in the promoter.Moreover,ectopic overexpression of HpFBH3 accelerated flower formation in Arabidopsis.In summary,this study systematically characterized the typical HpFBHs,especially HpFBH3,as positive regulators of flower formation,which could be target genes for the genetic improvement of pitaya.展开更多
From the seeds of Peganum harmala L.,three new alkaloids ofβ-carboline were isolated.Among them,peganumiums A(1)and B(2)were dimers with specific new scaffolds,all with long conjugated systems.Peganumium A and peganu...From the seeds of Peganum harmala L.,three new alkaloids ofβ-carboline were isolated.Among them,peganumiums A(1)and B(2)were dimers with specific new scaffolds,all with long conjugated systems.Peganumium A and peganumium C(3)were ionic alkaloid salts and peganumium B was a hexacycliccondensed alkaloid.The biosynthetic pathways of the three compounds above were also speculated.A preliminary cytotoxicity assay revealed that peganumium B had strong in vitro antiproliferative ability against a variety of cancer cells.The analysis of^(1)H nuclear magnetic resonance(NMR)metabolomics suggested that the antiproliferative mechanism of peganumium B could be associated with the biosynthesis of phenylalanine,tyrosine and tryptophan,the metabolism of glycine,serine,and threonine,the metabolism of taurine and hypotaurine,and the metabolism of nicotinate and nicotinamide.In addition,peganumium B could reduce the mitochondrial content of body-wall muscle cells of a Caenorhabditis elegans(C.elegans)strain in vivo.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
Nanomedicine holds considerable promise for advancing cancer therapy,however,effective delivery of drugs to solid tumors remains a challenge due to rapid systemic clearance and inefficient cellular uptake.Herein,we ha...Nanomedicine holds considerable promise for advancing cancer therapy,however,effective delivery of drugs to solid tumors remains a challenge due to rapid systemic clearance and inefficient cellular uptake.Herein,we have developed a novel charge-reversible nanogel to deliver paclitaxel(PTX)dimers(DPP)with enhanced stability and targeting precision.The nanogels exhibit a dynamic charge-reversal mechanism responsive to the acidic tumor microenvironment(TME),optimizing the cellular uptake of prodrugs.In the high glutathione(GSH)conditions within cancer cells,the disulfide bonds in the DPP are cleaved,resulting in the intracellular release of active PTX and reduced drug toxicity to normal cells.In vivo pharmacokinetic studies revealed an extended plasma elimination half-life for the charge-reversible nanocarriers,and antitumor efficacy studies demonstrated superior tumor suppression with minimal systemic toxicity.This research underscores the potential of integrating charge-reversal and responsive release mechanisms into one nanocarrier system,balancing the long circulation and high tumor cell internalization capacity of the nanocarrier,and providing a promising strategy for targeted delivery of nanomedicine.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 10874003)Ministry of Science and Technology of China (Grant No. 2006CB921300)
文摘This paper studies a spin ladder model which possesses frustrating interactions. By using both the bosonization and the density matrix renormalization group techniques, it shows that the intermediate columnar dimerized phase, which exists in a narrow parameter region of the so-called ~/1 - J2 model, vanishes if the interchain frustration is weak and anisotropic. Therefore, it concludes that the frustrating interaction indeed plays an important role in producing such a phase. As a complementary to our previous investigation, it reaches a more complete picture of the quantum phase transition in the frustrated spin ladder systems.
基金the National Natural Science Foundation of China(10374007 604720210)
文摘Entanglement transfer is investigated in a dimerized Heisenberg system. Concurrence as the measure of entanglement is calculated by the time-evolved state starting from an initially entangled state of spin pair. It is shown that perfect entanglement transfer can be realized at some special time and suitable interacting.
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Project supported by the National Natural Science Foundation of China(Grant Nos.11534002 and 11674049)
文摘We study the multistability of fixed points for a dimerized system of Rydberg atoms driven by two laser fields and trapped in a two-dimensional(2D)square lattice.For identical driving fields,the fixed points of this system exhibit stable uniform,unstable uniform,stable nonuniform,or oscillating nonuniform phases in the presence of a bistable region.For different driving fields,however,all(stable,unstable,or oscillating)phases become nonuniform instead,which then results in two islets isolated from the mainland of Rydberg excitation.We also show that a tristable region may stretch out from the(nonuniform)bistable region near the islets,indicating that a richer phase diagram can be attained by tuning the Rabi frequencies and/or detunings of the driving fields.Last but not least,the fixed points can adiabatically evolve from the islets to the mainland but can not inversely evolve from the mainland to the islets.
基金supported by the National Natural Science Foundation of China(22279079 and 22472101)Guangdong Science and Technology Department Program(2021QN02L252,2023A1515010021,and 2024A1515011543)Research Team Cultivation Program of Shenzhen University(2023QNT007)。
文摘Multi-site coupling is a promising strategy for developing highly efficient and CO-resistant hydrogen oxidation reaction(HOR)catalysts for proton exchange membrane fuel cells(PEMFCs).However,designing multifunctional synergistic schemes for single-atom sites remains a significant challenge.Herein,we propose a dual-template-confined oxophilic engineering strategy to construct well-dispersed iridium-nickel(IrNi)atomic dimers adjacent to IrNi nanoclusters on porous nitrogen-doped carbon(IrNi_(Dimer/NC1.8)-PNC).The paired IrNi dimer features an asymmetric Ir-N_(3)configuration coordinated with heteroatomic Ni-N_(3)O via an N-bridge.Remarkably,IrNi_(Dimer/NC1.8)-PNC exhibits a~23-fold enhancement in mass activity(4.36 A mg-1Ir at 20 mV)and 5-fold longer stability compared to benchmarking Pt/C toward HOR,while achieving a high rated power density of 1.18 W cm^(-2)in PEMFC anode applications.Furthermore,IrNi_(Dimer/NC1.8)-PNC demonstrates superior CO tolerance over monometallic Ir and Pt/C in both half-cell and full-cell devices.Combined experimental and density functional theory studies reveal that oxophilic Ni modulates the electronic environment of Ir through alloying and dimer interactions,thereby enhancing HOR activity.Importantly,the asymmetric IrNi dimer enables efficient CO^(*)and OH^(*)co-adsorption while facilitating CO_(2)^(*)desorption,synergistically mitigating CO poisoning and improving atom utilization efficiency.This work provides a design strategy and fundamental insights for multi-site synergistic catalysts in PEMFC anodes.
基金Project(20276016) supported by the National Natural Science Foundation of China
文摘The viscoelastic micelle systems formed by novel anionic-nonionic dimeric surfactant and conventional cationic surfactant cetyltrimethylammonium(1631) were studied.The viscoelasticity,thixotropy,flow curves and constitutive equation for the novel viscoelastic micelle systems were investigated.The results show that the micelle systems possess viscoelasticity,thixotropy,and shear thinning property.Some micelle systems possess hysteresis loops showing both viscoelasticity and thixotropy.It is proved that the flow curves are characterized by the co-rotational Jeffreys constitutive equation correctly.
基金Supported by the Chinese National Science Foundation of China under Grant Nos.10874003,11074004,and 11047160Numerical Computation of This Work was Carried out on the Parallel Computer Cluster of Institute for Condensed Matter Physics(ICMP) at School of Physics,Peking University
文摘In this paper, we study the phase diagram of a frustrated spin ladder model by applying the bosonization technique and the density-matrix renormalization-group （DMRG） algorithm. Effect of the intra-ehain next-nearest- neighbor （NNN） super-exchange interaction is investigated in detail and the order parameters are calculated to detect the emergence of the dimerized phases. We find that the intra-chain NNN interaction plays a key role in inducing dimerized phases.
基金Project supported by the National Natural Science Foundation of China (Grants Nos. 11174359 and 10874232)the National Basic Research Program of China (Grant No. 2012CB932302)
文摘In order to gain a deeper understanding of the quantum criticality in the explicitly staggered dimerized Heisenberg models, we study a generalized staggered dimer model named the J0 J1 J2 model, which corresponds to the staggered j-j′ model on a square lattice and a honeycomb lattice when J1/J0 equals 1 and O, respectively. Using the quantum Monte Carlo method, we investigate all the quantum critical points of these models with J1/J0 changing from 0 to 1 as a function of coupling ratio a = J2/J0. We extract all the critical values of the coupling ratio ac for these models, and we also obtain the critical exponents v,β/ν, and η using different finite-size scaling ansatz,. All these exponents are not consistent with the three-dimensional Heisenberg universality class, indicating some unconventional quantum ciriteial points in these models.
基金financially supported by the National Natural Science Foundation of China (Nos. 91961105, 21822107,21571115, 21827801)the Natural Science Foundation of Shandong Province (Nos. ZR2019ZD45, JQ201803 and ZR2017MB061)+2 种基金the Taishan Scholar Project of Shandong Province of China (Nos.tsqn201812003 and ts20190908)Project for Scientific Research Innovation Team of Young Scholar in Colleges and Universities of Shandong Province (No. 2019KJC028)Natural Science Foundation of Shandong Province (No. ZR2020ZD35)。
文摘The construction of all-carbon molecule frameworks remains challenging. Herein, we report a facile and efficient one-pot synthesis of a novel all-carbon stair containing dimerized pentalene core using inexpensive cyclopropyl alkyne catalyzed by in situ generated Cu(I) from the comproportionation reaction of Cu(II) salt and Cu powder under mild reaction conditions. The reaction proceeds via sequential acetylenic coupling, followed by cyclization and [2 + 2] cycloaddition to directly produce pentalene dimer, which is difficult to access by other established methods. Different mechanistic paths were studied for the pentalene formation using density functional theory, suggesting that the reaction also proceeds through acetylenic coupling followed by cyclization and [2 + 2] cycloaddition. Based on the activation energy barriers, Path 1 has the rate-determining step of 38.63 kcal/mol, which is the most thermodynamically preferred one among the four paths.
基金Supported by the National Natural Science Foundation of China under Grants No.19975031RFDP under Grants No.1999024833.
文摘The quasi-one-dimensional spin-Peierls(SP)systems with impurities are studied in their bosonized form.The spins of the dimerized state are bounded into singlets with an SP gap,while the impurities of doped systems will induce fluctuations of the coupling strength between the spins at different sites and break some pairs of spin singlets.The doping suppresses the dimerized SP state and induces a Kosterlitz-Thouless phase transition from the dimerized state into the undimerized one.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11804288 and 91750102)the Projects of President Foundation of Chongqing University(Grant No.2019CDXZWL002)。
文摘A simple one-dimensional subwavelength plasmonic grating can support symmetry protected bound states in the continuum(BICs),but not necessarily for the non-symmetry protected BICs.By dimerizing the lattice,nonsymmetry protected BIC can be supported on the dimerized grating and can be tuned readily.The mechanism for the BICs in the dimerized grating is interpreted in the viewpoint of interference between the electromagnetic multipoles.
文摘A mixed drug self-delivery system(DSDS)with high drug content(>50%)was developed to regulate pHtriggered drug release,based on two doxorubicin(DOX)-DOX dimmers:D-DOX_(ADH) and D-DOX_(car) conjugated with acid-labile dynamic covalent bonds(hydrazone and carbamate,respectively)and stabilized with PEGylated D-DOX_(ADH)(D-DOX_(ADH)-PEG).Owing to the different stability of the dynamic covalent bonds in the two dimers and the noncovalent interaction between them,pH-triggered drug release could be easily regulated by adjusting the feeding ratios of the two DOX-DOX dimers in the mixed DSDS.Similar in vitro cellular toxicity was achieved with the mixed DSDS nanoparticles prepared with different feeding ratios.The mixed DSDS nanoparticles had a similar DOX content and diameter but different drug releasing rates.The MTT assays revealed that a high anti-tumor efficacy could be achieved with the slowrelease mixed DSDS nanoparticles.
文摘The influences of Dzyaloshinskii Moriya （DM） interaction and Kaplan-Shekhtman-Entinwohlman-Aharony （KSEA） interaction on the dimerization of a spin-Peierls system are investigated theoretically by using the Lanczos numerical method. The ground state of the spin-Peierls system is still dimerized phase when both of the DM and the KSEA interactions have the same value with Heisenberg interaction. It is found that the KSEA interaction and uniform DM interaction are always against systemic dimerization, but the staggered DM interaction acts in favour of dimerization. Furthermore, the influences of the DM and the KSEA interactions are also studied in terms of the ground state index rate and the energy gap index rate of the dimerized Heisenberg system. The results show that the DM interaction makes the index rates larger, while the KSEA interaction makes them smaller.
文摘On the example of tetraantraquinoporphyrazines—potential photosensitizers for photodynamic therapy, thermodynamic approach to the choice of exogenous transport system was demonstrated. By means of isothermal titration calorimetry and electron absorption spectroscopy, the state of TAP in aqueous solutions was studied. The possibility of aggregation equilibrium displacement due to the pyridine adding was evaluated.
文摘Tens of thousands of protein-protein interactions (PPIs) have been found in human cells and many of these macromolecular partnerships could determine the cell growth and death. Thus there is a need to develop the methods to catalogue these macromolecules by detecting their interactions, modifications, and cellular locations. It will be helpful for scientists to compare the difference between a diseased cellular state and its normal state and to find the potential therapy treatment to intervene this status. One technology called split-protein reassembly or protein fragment complementation has been developed in the last two decades. This technology makes use of appropriate fragmentation of some protein reporters and the refolding of these reports could be detected by their function to confirm the interaction of interest. This system has been set up in cell-free systems, </span><i><span style="font-family:Verdana;">E.</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">coli</span></i><span style="font-family:""><span style="font-family:Verdana;">, yeast, mammalian cells, plants and live animals. Herein, I present the development in fluorescence- and bioluminescence-based split-protein biosensors in both binary and ternary systems. In addition, some people developed the split-protein system by combining it with chemical inducer of dimerization strategy (CID). This has been applied for identifying the enzyme inhibitors and regulating the activity of protein kinases and phosphatases. With effort from many laboratories from the world, a variety of split-protein systems have been developed for studying the PPI </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;">, monitoring the biological process, and controlling the activity of the enzyme of interest.
基金support from the Czech Science Foundation,project EXPRO,No 19-27454Xsupport by the European Union under the REFRESH—Research Excellence For Region Sustainability and High-tech Industries project number CZ.10.03.01/00/22_003/0000048 via the Operational Programme Just Transition from the Ministry of the Environment of the Czech Republic+1 种基金Horizon Europe project EIC Pathfinder Open 2023,“GlaS-A-Fuels”(No.101130717)supported from ERDF/ESF,project TECHSCALE No.CZ.02.01.01/00/22_008/0004587).
文摘Green hydrogen from water splitting has emerged as a critical energy vector with the potential to spearhead the global transition to a fossil fuel-independent society.The field of catalysis has been revolutionized by single-atom catalysts(SACs),which exhibit unique and intricate interactions between atomically dispersed metal atoms and their supports.Recently,bimetallic SACs(bimSACs)have garnered significant attention for leveraging the synergistic functions of two metal ions coordinated on appropriately designed supports.BimSACs offer an avenue for rich metal–metal and metal–support cooperativity,potentially addressing current limitations of SACs in effectively furnishing transformations which involve synchronous proton–electron exchanges,substrate activation with reversible redox cycles,simultaneous multi-electron transfer,regulation of spin states,tuning of electronic properties,and cyclic transition states with low activation energies.This review aims to encapsulate the growing advancements in bimSACs,with an emphasis on their pivotal role in hydrogen generation via water splitting.We subsequently delve into advanced experimental methodologies for the elaborate characterization of SACs,elucidate their electronic properties,and discuss their local coordination environment.Overall,we present comprehensive discussion on the deployment of bimSACs in both hydrogen evolution reaction and oxygen evolution reaction,the two half-reactions of the water electrolysis process.
基金supported by the National Natural Science Foundation of China(32160681 and 32060663)the National Guidance Foundation for Local Science and Technology Development of China(2023-009)+1 种基金the Guizhou Provincial Basic Research Program(Natural Science)(ZK[2022]YB132)the Foundation of Postgraduate of Guizhou Province,China(YJSKYJJ[2021]057)。
文摘Hylocereus polyrhizus,also known as pitaya or dragon fruit,is a climbing cactus grown worldwide because of its excellent performance under drought stress and appealing red-purple fruits.In practice,accelerating flower formation and inducing more flowers usually result in higher yield.However,the genes for this purpose have not been well characterized in pitaya.Previously,FLOWERING BHLHs(FBHs)have been identified as positive regulators of flower formation.In the present work,a total of eight FBHs were identified in pitaya.This is a greater number than in beet and spinach,possibly because of the recent whole-genome duplication that occurred in the pitaya genome.The phylogenetic tree indicated that the FBHs could be divided into three groups.In TYPEⅡ,the genes of Caryophyllales encode atypical FBHs and are generated by dispersed duplication.The K_(a)/K_(s) ratios indicated that HpFBHs are under purifying selection.Promoter and expression analysis of HpFBHs revealed that they are spatiotemporally activated in flower-related tissues and responsive to multiple abiotic stresses.These results indicated that HpFBHs are involved in the flower formation of pitaya.Therefore,typical HpFBH1/3 from TYPEⅡI and an atypical HpFBH8 from TYPEⅡwere selected for functional verification.HpFBH3 was found to heterodimerize with HpFBH1 in the nucleus using subcellular localization,yeast two-hybrid and luciferase complementation assays.With bioinformatic analysis,all HpFBHs were predicted to transactivate downstream genes via binding to the E-boxes,which were frequently detected in the promoters of HpCOs,HpFTs and HpSOC1s.RNA-Seq datasets showed that these flowering accelerators were expressed in coordination with HpFBH3.Yeast one-hybrid and dual-luciferase reporter assays further verified that HpFBH3 transactivated HpCO7 by selectively binding to the E-boxes in the promoter.Moreover,ectopic overexpression of HpFBH3 accelerated flower formation in Arabidopsis.In summary,this study systematically characterized the typical HpFBHs,especially HpFBH3,as positive regulators of flower formation,which could be target genes for the genetic improvement of pitaya.
基金Financial support from Beijing Natural Science Foundation(No.7232283)。
文摘From the seeds of Peganum harmala L.,three new alkaloids ofβ-carboline were isolated.Among them,peganumiums A(1)and B(2)were dimers with specific new scaffolds,all with long conjugated systems.Peganumium A and peganumium C(3)were ionic alkaloid salts and peganumium B was a hexacycliccondensed alkaloid.The biosynthetic pathways of the three compounds above were also speculated.A preliminary cytotoxicity assay revealed that peganumium B had strong in vitro antiproliferative ability against a variety of cancer cells.The analysis of^(1)H nuclear magnetic resonance(NMR)metabolomics suggested that the antiproliferative mechanism of peganumium B could be associated with the biosynthesis of phenylalanine,tyrosine and tryptophan,the metabolism of glycine,serine,and threonine,the metabolism of taurine and hypotaurine,and the metabolism of nicotinate and nicotinamide.In addition,peganumium B could reduce the mitochondrial content of body-wall muscle cells of a Caenorhabditis elegans(C.elegans)strain in vivo.
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supported by the Natural Science Foundation of Jilin Province(No.20240101003JJ)the National Natural Science Foundation of China(Nos.22275065,52073116)。
文摘Nanomedicine holds considerable promise for advancing cancer therapy,however,effective delivery of drugs to solid tumors remains a challenge due to rapid systemic clearance and inefficient cellular uptake.Herein,we have developed a novel charge-reversible nanogel to deliver paclitaxel(PTX)dimers(DPP)with enhanced stability and targeting precision.The nanogels exhibit a dynamic charge-reversal mechanism responsive to the acidic tumor microenvironment(TME),optimizing the cellular uptake of prodrugs.In the high glutathione(GSH)conditions within cancer cells,the disulfide bonds in the DPP are cleaved,resulting in the intracellular release of active PTX and reduced drug toxicity to normal cells.In vivo pharmacokinetic studies revealed an extended plasma elimination half-life for the charge-reversible nanocarriers,and antitumor efficacy studies demonstrated superior tumor suppression with minimal systemic toxicity.This research underscores the potential of integrating charge-reversal and responsive release mechanisms into one nanocarrier system,balancing the long circulation and high tumor cell internalization capacity of the nanocarrier,and providing a promising strategy for targeted delivery of nanomedicine.
