Strong Coulombic repulsion in small doubly charged molecular ions usually leads to fragmentation.Some of these ions,such as CO_(2)^(++),could survive and be detected if they are stable or metastable in energetics,but ...Strong Coulombic repulsion in small doubly charged molecular ions usually leads to fragmentation.Some of these ions,such as CO_(2)^(++),could survive and be detected if they are stable or metastable in energetics,but how to produce these observable doubly charged ions is a puzzling issue.Here we investigate CO_(2)^(++)production by electron-impact ionization with a supersonic molecular beam of CO_(2)under different nozzle pressures,using time-of-flight mass spectrometry measurements and ab initio calculations.The mass spectral profile of CO_(2)^(++)varies slightly with the nozzle pressure,implying different mechanisms of the ion production.The calculations indicate that the ground state of CO_(2)^(++)is 3Aʺwith a nonlinear conformation,while the linear conformer is in the first excited state 1Δ_(g).We further suggest that,besides CO_(2)^(++)(1Δ_(g))produced from CO_(2),CO_(2)^(++)(3Aʺ)could be produced by the dissociation of doubly charged dimer(C2O4^(++))in a repulsive triplet state.展开更多
Taking an image of their structure and a movie of their dynamics of small quantum systems have always been a dream of physicists and chemists. Laser-induced Coulomb explosion imaging(CEI) provides a great opportunity ...Taking an image of their structure and a movie of their dynamics of small quantum systems have always been a dream of physicists and chemists. Laser-induced Coulomb explosion imaging(CEI) provides a great opportunity to make this dream a reality for small molecules or their aggregation — clusters. The method is unique for identifying the atomic locations with angstrom spatial resolution and capturing the structural evolution with a femtosecond time scale, in particular for imaging transient state products. This review summarizes the determination of three-dimensional equilibrium geometry of molecules and molecular cluster system through the reconstruction from the fragments momenta, and also shows that the dissociation dynamics on the complex potential energy surface can be tracked in real-time with the ultrafast CEI(UCEI).Furthermore, the detailed measurement and analysis procedures of the CEI, theoretical methods, exemplary results, and future perspectives of the technique are described.展开更多
Metal-based antimicrobial materials have been extensively studied and applied over decades.While these materials are notably characterized by their superior antibacterial performance and low propensity to induce drug ...Metal-based antimicrobial materials have been extensively studied and applied over decades.While these materials are notably characterized by their superior antibacterial performance and low propensity to induce drug resistance,critical limitations such as inherent cytotoxicity,poor solubility,and instability in aqueous solution remain significant challenges requiring systematic optimization.In this study,we synthesized water-soluble molecular iron-oxo clusters(MIC)with excellent biosafety and stability of aqueous solution.Our findings demonstrate that MIC exhibits marked therapeutic efficacy in cecal ligation and puncture induced sepsis models,a critical validation given sepsis'etiology as a life-threatening infection mediated systemic inflammatory syndrome.MIC combats bacteria by enhancing humoral immune responsiveness.MIC significantly improved the survival rate,reduced bacterial burden,stabilized body temperature,and modulated cytokine profiles in mice with sepsis.Further investigations revealed that MIC promotes B cells proliferation and oxidative phosphorylation,and mitigates mitochondrial damage and apoptosis in B cells,suggesting its role in modulating cellular metabolism.RNA sequencing analysis demonstrated that MIC exerts its effects by influencing key pathways involved in humoral immunity,inflammatory responses,and metabolic adaptation.These findings establish MIC as a novel therapeutic agent for regulating immune responses in sepsis,providing innovative strategies to improve recovery from this life-threatening condition.展开更多
Molecular dynamics simulations are performed to observe the evolutions of 512 and 51262 cage-like water clusters filled with or without a methane molecule immersed in bulk liquid water at 250 K and 230 K. The lifetime...Molecular dynamics simulations are performed to observe the evolutions of 512 and 51262 cage-like water clusters filled with or without a methane molecule immersed in bulk liquid water at 250 K and 230 K. The lifetimes of these clusters are calculated according to their Lindemann index δ (t) using the criteria of δ≥0.07. For both the filled and empty clusters, we find the dynamics of bulk water determines the lifetimes of cage-like water clusters, and that the lifetime of 512 62 cage-like cluster is the same as that of 512 cage-like cluster. Although the methane molecule indeed makes the filled cage-like cluster more stable than the empty one, the empty cage-like cluster still has chance to be long-lived compared with the filled clusters. These observations support the labile cluster hypothesis on the formation mechanisms of gas hydrates.展开更多
Protons with very high kinetic energy of about lOkeV and the saturation effect of proton energy for laser intensity have been observed in the interaction of an ultrashort intense laser pulse with large-sized hydrogen ...Protons with very high kinetic energy of about lOkeV and the saturation effect of proton energy for laser intensity have been observed in the interaction of an ultrashort intense laser pulse with large-sized hydrogen dusters. Including the cluster-size distribution as well as the laser-intensity distribution on the focus spot, the theoretical calculations based on a simplified Coulomb explosion model have been compared with our experimental measurements, which are in good agreement with each other.展开更多
The urgent need for immediate personal protection against chemical warfare agents(CWAs)spurs the requirement on robust and highly efficient catalytic systems that can be conveniently integrated to wearable devices.Her...The urgent need for immediate personal protection against chemical warfare agents(CWAs)spurs the requirement on robust and highly efficient catalytic systems that can be conveniently integrated to wearable devices.Herein,as a new concept for CWA decontamination catalyst design,sub-nanoscale,catalytically active zirconium-oxo molecular clusters are covalently integrated in flexible polymer network as crosslinkers for the full exposure of catalytic sites as well as robust framework structures.The obtained membrane catalysts exhibit high swelling ratio with aqueous content as 84 wt%and therefore,demonstrate quasi-homogeneous catalytic activity toward the rapid hydrolysis of both CWA,soman(GD)(t_(1/2)=5.0 min)and CWA simulant,methyl paraoxon(DMNP)(t_(1/2)=8.9 min).Meanwhile,due to the covalent nature of cross-linkages and the high flexibility of polymer strands,the membranes possess promising mechanical strength and toughness that can stand the impact of high gas pressures and show high permeation for both CO_(2)and O_(2),enabling their extended applications in the field of collective/personal protective materials with body comfort.展开更多
This paper reports that Coulomb explosions taken place in the experiment of heteronuclear deuterated methane clusters （（CD4）n） in a gas jet subjected to intense femtoseeond laser pulses （170 mJ, 70 fs） have led ...This paper reports that Coulomb explosions taken place in the experiment of heteronuclear deuterated methane clusters （（CD4）n） in a gas jet subjected to intense femtoseeond laser pulses （170 mJ, 70 fs） have led to table-top laser driven DD nuclear fusion. The clusters produced in supersonic expansion had an average size of about 5 nm in radius and the laser intensity used was 3 × 10^17 W/cm^2.The measured maximum and average energies of deuterons produced in the laser-cluster interaction were 60 and 13.5 keV, respectively. Prom DD collisions of energetic deuterons, a yield of 2.5（±0.4） × 10^4 fusion neutrons of 2.45 MeV per shot was realized, giving rise to a neutron production efficiency of about 1.5 × 10^5 per joule of incident laser pulse energy. Theoretical calculations were performed and a fairly good agreement of the calculated neutron yield with that obtained from the present experiment was found.展开更多
Performing cluster analysis on molecular conformation is an important way to find the representative conformation in the molecular dynamics trajectories.Usually,it is a critical step for interpreting complex conformat...Performing cluster analysis on molecular conformation is an important way to find the representative conformation in the molecular dynamics trajectories.Usually,it is a critical step for interpreting complex conformational changes or interaction mechanisms.As one of the density-based clustering algorithms,find density peaks(FDP)is an accurate and reasonable candidate for the molecular conformation clustering.However,facing the rapidly increasing simulation length due to the increase in computing power,the low computing efficiency of FDP limits its application potential.Here we propose a marginal extension to FDP named K-means find density peaks(KFDP)to solve the mass source consuming problem.In KFDP,the points are initially clustered by a high efficiency clustering algorithm,such as K-means.Cluster centers are defined as typical points with a weight which represents the cluster size.Then,the weighted typical points are clustered again by FDP,and then are refined as core,boundary,and redefined halo points.In this way,KFDP has comparable accuracy as FDP but its computational complexity is reduced from O(n^(2))to O(n).We apply and test our KFDP method to the trajectory data of multiple small proteins in terms of torsion angle,secondary structure or contact map.The comparing results with K-means and density-based spatial clustering of applications with noise show the validation of the proposed KFDP.展开更多
Structure-based virtual screening（molecular docking）is now one of the most pragmatic techniques to leverage target structure for ligand discovery.Accurate binding pose prediction is critical to molecular docking.Her...Structure-based virtual screening（molecular docking）is now one of the most pragmatic techniques to leverage target structure for ligand discovery.Accurate binding pose prediction is critical to molecular docking.Here,we describe a general strategy to improve the accuracy of docking pose prediction by implementing the structural descriptor-based fltering and KGS-penalty function-based conformational clustering in an unbiased manner.We assessed our method against 150 high-quality protein–ligand complex structures.Surprisingly,such simple components are suffcient to improve the accuracy of docking pose prediction.The success rate of predicting near-native docking pose increased from 53%of the targets to 78%.We expect that our strategy may have general usage in improving currently available molecular docking programs.展开更多
The energy-localized CNDO/2 molecular orbitals have been calculated for the cluster anions of [Co_6 (CO)_(14)]￣(4-) and [Ni_2Co_4 (CO)_(14)]￣(2-)in order to get a deeper insight into the nature of their skeletal bon...The energy-localized CNDO/2 molecular orbitals have been calculated for the cluster anions of [Co_6 (CO)_(14)]￣(4-) and [Ni_2Co_4 (CO)_(14)]￣(2-)in order to get a deeper insight into the nature of their skeletal bonding. The bonding characteristics of these hexanuclear carbonyl cobaltates are described from a localization bonding viewpoint. There are two typical M-CO bondings, one of which is formed by electron donation from the terminal and capping carbonyl ligands into the vacant hybrid orbitals on the metal atoms , leading to formation ofσ(C_t→Co) and σ(C_b→{Co_3})bonds. The other typical M-CO bonding is back donation of the lone d-electron pairs on the metal atoms into the carbonyl ligands, forming π(Co→C_t) bonds, σ(Co→{C_(b2)}) bonds and π(Co→{C_(b4)} ) bonds. It is found that there are no direct metalmetal bondings in the skeletons of these two cluster anions.The delocalization situation of the skeletal bonding electrons is briefly discussed.展开更多
The new cluster[Mo_4(μ_3-O)_2O_4Cl_2(o-CH_3C_6H_4COO)_6]has been prepared by the reaction of molybdenum pentachloride and o-methylbenzoic acid.The crystal and molecular structures were determined by the X-ray diffrac...The new cluster[Mo_4(μ_3-O)_2O_4Cl_2(o-CH_3C_6H_4COO)_6]has been prepared by the reaction of molybdenum pentachloride and o-methylbenzoic acid.The crystal and molecular structures were determined by the X-ray diffraction method.It crystallizes in the orthorhombic space group Pnna with cell parameters:Mr=1361.6,a=13.792(4), b=17.957(3),c=20.974(9) ,V=5194(2) ~3,Z=4,Dc=1.74/cm^3,F(OOO)=2704,μ(MoK ) =11.0/cm,R=0.074.展开更多
Reaction of dimers of (R) thionophosphine sulfide (R = P - C6H4OMe,SMe ) with Co, (CO), yields the novel hexacobalt cluster [Co'(μ3, -S)2, (CO) 14 (μ4 -μ4- and the trinuclear clusterPSCH,)J 2' In 1, tw0 Co3...Reaction of dimers of (R) thionophosphine sulfide (R = P - C6H4OMe,SMe ) with Co, (CO), yields the novel hexacobalt cluster [Co'(μ3, -S)2, (CO) 14 (μ4 -μ4- and the trinuclear clusterPSCH,)J 2' In 1, tw0 Co3S(C0)7 units linked by a novel phosphido-thio1ato bifunc-tiona1 bridging p'-SPR ligand as backbone.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
A redshift in the wavelength of excitation spectra is experimentally measured as a function of the concentration parameter for tryptophan solutions in water. To understand the microscopic causes of this behavior, theo...A redshift in the wavelength of excitation spectra is experimentally measured as a function of the concentration parameter for tryptophan solutions in water. To understand the microscopic causes of this behavior, theoretical calculations obtained from four model clusters are carried out: (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">1</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">9</span></sub><span style="font-family:Verdana;">, (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">2</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">18</span></sub><span style="font-family:Verdana;">, (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">3</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">27</span></sub><span style="font-family:Verdana;"> and (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">4</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">36</span></sub><span style="font-family:Verdana;">, where there are interactions among 1, 2, 3 and 4 molecules of tryptophan. According to the literature, each interaction occurred with nine molecules of water to stabilize its expected zwitterionic form. In these models, the molecules of tryptophan appear at an adjacent distance among them to generate an analogous behavior when there is an experimental increase in the concentration. It is evident that </span><span style="font-family:Verdana;">the distance between adjacent molecules of tryptophan decreases as their concentration</span><span style="font-family:Verdana;"> increases. The optical properties of these clusters are obtained by studying the corresponding excited states and the molecular orbitals involved, showing charge transfers by using time-dependent density functional theory (TD-DFT) methods. The experimental spectroscopic data are obtained by using the clusters proposed, and good agreement is found by drawing a comparison with the theoretical data</span></span><span style="font-family:Verdana;">.展开更多
There are nearly 1 000 rice landrace varieties in the Taihu basin, China. To assess the genetic diversity of the rice, 24 intragenic molecular markers（representing 17 starch synthesis-related genes） were investigate...There are nearly 1 000 rice landrace varieties in the Taihu basin, China. To assess the genetic diversity of the rice, 24 intragenic molecular markers（representing 17 starch synthesis-related genes） were investigated in 115 Taihu basin rice landraces and 87 improved cultivars simultaneously. The results show that the average genetic diversity and polymorphism information content values of the landraces were higher than those of improved cultivars. In total, 41 and 39 allele combinations（of the 17 genes） were derived from the landraces and improved cultivars, respectively; only two identical allele combinations were found bet ween the two rice variety sources. Cluster analysis, based on the molecular markers, revealed that the rice varieties could be subdivided into five groups and, within these, the japonica improved rice and japonica landrace rice varieties were in two separate groups. According to the quality reference criteria to classify the rice into grades, some of the landraces were found to perform we ll, in terms of starch quality. For example, according to NY /T595-2002 criteria from the Ministry of Agriculture of China, 25 and 33 landraces reached grade 1, in terms of their apparent amylose content and gel consistency. Th e varieties that had outstanding quality could be used as breeding materials for rice quality breeding programs in the future. Our study is useful for future applications, such as genetic diversity studies, the protection of rice variety and improvment of rice quality in breeding programs.展开更多
The experimental set-up of SMBI system in HL-2A and the detail structure of the molecular beam valve with cooling trap are shown in Fig.l. The valve used for producing hydrogen cluster jet is a solenoid valve S99 with...The experimental set-up of SMBI system in HL-2A and the detail structure of the molecular beam valve with cooling trap are shown in Fig.l. The valve used for producing hydrogen cluster jet is a solenoid valve S99 with a nozzle orifice of 0.2 mm diameter. The distance between the nozzle of the valve and the edge plasma is about 1.28 m. A liquid nitrogen cryogenic trap is applied for cooling the valve body and decreasing the working gas temperature. The hydrogen cluster jet used for the experiments is in fact a free jet. For real gases, the adiabatic expansion of gas through a nozzle into vacuum results in substantial cooling in the frame of the moving gas. Atoms or molecules that interact weakly at low temperature can form clusters as a result. Attractive forces between atoms can be hydrogen bonding,展开更多
Precise identification of HIV transmission among populations is a key step in public health responses.However,the HIV transmission network is usually difficult to determine.HIV molecular networks can be determined by ...Precise identification of HIV transmission among populations is a key step in public health responses.However,the HIV transmission network is usually difficult to determine.HIV molecular networks can be determined by phylogenetic approach,genetic distance-based approach,and a combination of both approaches.These approaches are increasingly used to identify transmission networks among populations,reconstruct the history of HIV spread,monitor the dynamics of HIV transmission,guide targeted intervention on key subpopulations,and assess the effects of interventions.Simulation and retrospective studies have demonstrated that these molecular network-based interventions are more cost-effective than random or traditional interventions.However,we still need to address several challenges to improve the practice of molecular network-guided targeting interventions to finally end the HIV epidemic.The data remain limited or difficult to obtain,and more automatic real-time tools are required.In addition,molecular and social networks must be combined,and technical parameters and ethnic issues warrant further studies.展开更多
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDB0450202)。
文摘Strong Coulombic repulsion in small doubly charged molecular ions usually leads to fragmentation.Some of these ions,such as CO_(2)^(++),could survive and be detected if they are stable or metastable in energetics,but how to produce these observable doubly charged ions is a puzzling issue.Here we investigate CO_(2)^(++)production by electron-impact ionization with a supersonic molecular beam of CO_(2)under different nozzle pressures,using time-of-flight mass spectrometry measurements and ab initio calculations.The mass spectral profile of CO_(2)^(++)varies slightly with the nozzle pressure,implying different mechanisms of the ion production.The calculations indicate that the ground state of CO_(2)^(++)is 3Aʺwith a nonlinear conformation,while the linear conformer is in the first excited state 1Δ_(g).We further suggest that,besides CO_(2)^(++)(1Δ_(g))produced from CO_(2),CO_(2)^(++)(3Aʺ)could be produced by the dissociation of doubly charged dimer(C2O4^(++))in a repulsive triplet state.
基金Project partially supported by the National Key Research and Development Program of China (Grant Nos. 2019YFA0307700)the National Natural Science Foundation of China (Grant Nos. 12004133, 12074143, 12134005, and 11904210)China Postdoctoral Science Foundation (Grant No. 2021M691220)。
文摘Taking an image of their structure and a movie of their dynamics of small quantum systems have always been a dream of physicists and chemists. Laser-induced Coulomb explosion imaging(CEI) provides a great opportunity to make this dream a reality for small molecules or their aggregation — clusters. The method is unique for identifying the atomic locations with angstrom spatial resolution and capturing the structural evolution with a femtosecond time scale, in particular for imaging transient state products. This review summarizes the determination of three-dimensional equilibrium geometry of molecules and molecular cluster system through the reconstruction from the fragments momenta, and also shows that the dissociation dynamics on the complex potential energy surface can be tracked in real-time with the ultrafast CEI(UCEI).Furthermore, the detailed measurement and analysis procedures of the CEI, theoretical methods, exemplary results, and future perspectives of the technique are described.
基金the generous supported by the National Key R&D Program of China(No.2023YFC2413100)the National Natural Science Foundation of China(Nos.22322102,21871042 and 21471028)+1 种基金the Fundamental Research Funds for the Central Universities-Excellent Youth Team Program(No.2412023YQ001)the Natural Science Foundation of Jilin Province(Nos.YDZJ202401550ZYTS,20200201083JC)。
文摘Metal-based antimicrobial materials have been extensively studied and applied over decades.While these materials are notably characterized by their superior antibacterial performance and low propensity to induce drug resistance,critical limitations such as inherent cytotoxicity,poor solubility,and instability in aqueous solution remain significant challenges requiring systematic optimization.In this study,we synthesized water-soluble molecular iron-oxo clusters(MIC)with excellent biosafety and stability of aqueous solution.Our findings demonstrate that MIC exhibits marked therapeutic efficacy in cecal ligation and puncture induced sepsis models,a critical validation given sepsis'etiology as a life-threatening infection mediated systemic inflammatory syndrome.MIC combats bacteria by enhancing humoral immune responsiveness.MIC significantly improved the survival rate,reduced bacterial burden,stabilized body temperature,and modulated cytokine profiles in mice with sepsis.Further investigations revealed that MIC promotes B cells proliferation and oxidative phosphorylation,and mitigates mitochondrial damage and apoptosis in B cells,suggesting its role in modulating cellular metabolism.RNA sequencing analysis demonstrated that MIC exerts its effects by influencing key pathways involved in humoral immunity,inflammatory responses,and metabolic adaptation.These findings establish MIC as a novel therapeutic agent for regulating immune responses in sepsis,providing innovative strategies to improve recovery from this life-threatening condition.
基金supported by the National Natural Science Foundation of China(Grant No.40102005 and No.49725205).
文摘Molecular dynamics simulations are performed to observe the evolutions of 512 and 51262 cage-like water clusters filled with or without a methane molecule immersed in bulk liquid water at 250 K and 230 K. The lifetimes of these clusters are calculated according to their Lindemann index δ (t) using the criteria of δ≥0.07. For both the filled and empty clusters, we find the dynamics of bulk water determines the lifetimes of cage-like water clusters, and that the lifetime of 512 62 cage-like cluster is the same as that of 512 cage-like cluster. Although the methane molecule indeed makes the filled cage-like cluster more stable than the empty one, the empty cage-like cluster still has chance to be long-lived compared with the filled clusters. These observations support the labile cluster hypothesis on the formation mechanisms of gas hydrates.
基金Supported by the National Natural Science Foundation of China under Grant No 10535070.
文摘Protons with very high kinetic energy of about lOkeV and the saturation effect of proton energy for laser intensity have been observed in the interaction of an ultrashort intense laser pulse with large-sized hydrogen dusters. Including the cluster-size distribution as well as the laser-intensity distribution on the focus spot, the theoretical calculations based on a simplified Coulomb explosion model have been compared with our experimental measurements, which are in good agreement with each other.
基金the National Key Research and Development Program of China(No.2018YFB0704200)the Project of State Key Laboratory of NBC Protection for Civilian(No.ZKGSG-ZB-20194334)+1 种基金the National Natural Science Foundation of China(Nos.21961142018 and 51873067)Natural Science Foundation of Guangdong Province(Nos.2021A1515012024 and 2021A1515010271)。
文摘The urgent need for immediate personal protection against chemical warfare agents(CWAs)spurs the requirement on robust and highly efficient catalytic systems that can be conveniently integrated to wearable devices.Herein,as a new concept for CWA decontamination catalyst design,sub-nanoscale,catalytically active zirconium-oxo molecular clusters are covalently integrated in flexible polymer network as crosslinkers for the full exposure of catalytic sites as well as robust framework structures.The obtained membrane catalysts exhibit high swelling ratio with aqueous content as 84 wt%and therefore,demonstrate quasi-homogeneous catalytic activity toward the rapid hydrolysis of both CWA,soman(GD)(t_(1/2)=5.0 min)and CWA simulant,methyl paraoxon(DMNP)(t_(1/2)=8.9 min).Meanwhile,due to the covalent nature of cross-linkages and the high flexibility of polymer strands,the membranes possess promising mechanical strength and toughness that can stand the impact of high gas pressures and show high permeation for both CO_(2)and O_(2),enabling their extended applications in the field of collective/personal protective materials with body comfort.
基金supported by the National Basic Research Program of China (Grant No 2006CB806000)the National Natural Science Foundation of China (Grant No 10535070)
文摘This paper reports that Coulomb explosions taken place in the experiment of heteronuclear deuterated methane clusters （（CD4）n） in a gas jet subjected to intense femtoseeond laser pulses （170 mJ, 70 fs） have led to table-top laser driven DD nuclear fusion. The clusters produced in supersonic expansion had an average size of about 5 nm in radius and the laser intensity used was 3 × 10^17 W/cm^2.The measured maximum and average energies of deuterons produced in the laser-cluster interaction were 60 and 13.5 keV, respectively. Prom DD collisions of energetic deuterons, a yield of 2.5（±0.4） × 10^4 fusion neutrons of 2.45 MeV per shot was realized, giving rise to a neutron production efficiency of about 1.5 × 10^5 per joule of incident laser pulse energy. Theoretical calculations were performed and a fairly good agreement of the calculated neutron yield with that obtained from the present experiment was found.
基金Professor Hong Yu at Intelligent Fishery Innovative Team(No.C202109)in School of Information Engineering of Dalian Ocean University for her support of this workfunded by the National Natural Science Foundation of China(No.31800615 and No.21933010)。
文摘Performing cluster analysis on molecular conformation is an important way to find the representative conformation in the molecular dynamics trajectories.Usually,it is a critical step for interpreting complex conformational changes or interaction mechanisms.As one of the density-based clustering algorithms,find density peaks(FDP)is an accurate and reasonable candidate for the molecular conformation clustering.However,facing the rapidly increasing simulation length due to the increase in computing power,the low computing efficiency of FDP limits its application potential.Here we propose a marginal extension to FDP named K-means find density peaks(KFDP)to solve the mass source consuming problem.In KFDP,the points are initially clustered by a high efficiency clustering algorithm,such as K-means.Cluster centers are defined as typical points with a weight which represents the cluster size.Then,the weighted typical points are clustered again by FDP,and then are refined as core,boundary,and redefined halo points.In this way,KFDP has comparable accuracy as FDP but its computational complexity is reduced from O(n^(2))to O(n).We apply and test our KFDP method to the trajectory data of multiple small proteins in terms of torsion angle,secondary structure or contact map.The comparing results with K-means and density-based spatial clustering of applications with noise show the validation of the proposed KFDP.
文摘Structure-based virtual screening（molecular docking）is now one of the most pragmatic techniques to leverage target structure for ligand discovery.Accurate binding pose prediction is critical to molecular docking.Here,we describe a general strategy to improve the accuracy of docking pose prediction by implementing the structural descriptor-based fltering and KGS-penalty function-based conformational clustering in an unbiased manner.We assessed our method against 150 high-quality protein–ligand complex structures.Surprisingly,such simple components are suffcient to improve the accuracy of docking pose prediction.The success rate of predicting near-native docking pose increased from 53%of the targets to 78%.We expect that our strategy may have general usage in improving currently available molecular docking programs.
文摘The energy-localized CNDO/2 molecular orbitals have been calculated for the cluster anions of [Co_6 (CO)_(14)]￣(4-) and [Ni_2Co_4 (CO)_(14)]￣(2-)in order to get a deeper insight into the nature of their skeletal bonding. The bonding characteristics of these hexanuclear carbonyl cobaltates are described from a localization bonding viewpoint. There are two typical M-CO bondings, one of which is formed by electron donation from the terminal and capping carbonyl ligands into the vacant hybrid orbitals on the metal atoms , leading to formation ofσ(C_t→Co) and σ(C_b→{Co_3})bonds. The other typical M-CO bonding is back donation of the lone d-electron pairs on the metal atoms into the carbonyl ligands, forming π(Co→C_t) bonds, σ(Co→{C_(b2)}) bonds and π(Co→{C_(b4)} ) bonds. It is found that there are no direct metalmetal bondings in the skeletons of these two cluster anions.The delocalization situation of the skeletal bonding electrons is briefly discussed.
基金Work supported by the National Natural Science Foundation of China(NNSFC)
文摘The new cluster[Mo_4(μ_3-O)_2O_4Cl_2(o-CH_3C_6H_4COO)_6]has been prepared by the reaction of molybdenum pentachloride and o-methylbenzoic acid.The crystal and molecular structures were determined by the X-ray diffraction method.It crystallizes in the orthorhombic space group Pnna with cell parameters:Mr=1361.6,a=13.792(4), b=17.957(3),c=20.974(9) ,V=5194(2) ~3,Z=4,Dc=1.74/cm^3,F(OOO)=2704,μ(MoK ) =11.0/cm,R=0.074.
文摘Reaction of dimers of (R) thionophosphine sulfide (R = P - C6H4OMe,SMe ) with Co, (CO), yields the novel hexacobalt cluster [Co'(μ3, -S)2, (CO) 14 (μ4 -μ4- and the trinuclear clusterPSCH,)J 2' In 1, tw0 Co3S(C0)7 units linked by a novel phosphido-thio1ato bifunc-tiona1 bridging p'-SPR ligand as backbone.
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.
文摘A redshift in the wavelength of excitation spectra is experimentally measured as a function of the concentration parameter for tryptophan solutions in water. To understand the microscopic causes of this behavior, theoretical calculations obtained from four model clusters are carried out: (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">1</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">9</span></sub><span style="font-family:Verdana;">, (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">2</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">18</span></sub><span style="font-family:Verdana;">, (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">3</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">27</span></sub><span style="font-family:Verdana;"> and (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">4</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">36</span></sub><span style="font-family:Verdana;">, where there are interactions among 1, 2, 3 and 4 molecules of tryptophan. According to the literature, each interaction occurred with nine molecules of water to stabilize its expected zwitterionic form. In these models, the molecules of tryptophan appear at an adjacent distance among them to generate an analogous behavior when there is an experimental increase in the concentration. It is evident that </span><span style="font-family:Verdana;">the distance between adjacent molecules of tryptophan decreases as their concentration</span><span style="font-family:Verdana;"> increases. The optical properties of these clusters are obtained by studying the corresponding excited states and the molecular orbitals involved, showing charge transfers by using time-dependent density functional theory (TD-DFT) methods. The experimental spectroscopic data are obtained by using the clusters proposed, and good agreement is found by drawing a comparison with the theoretical data</span></span><span style="font-family:Verdana;">.
基金financially supported by the National Natural Science Foundation of China(30800603)the Science and Technology Plan Projects of Taicang City,China(TC214YY3)the Building Program of the Science and Technology Innovation Team of Chien-Shiung Institute of Technology,China(2013CX02)
文摘There are nearly 1 000 rice landrace varieties in the Taihu basin, China. To assess the genetic diversity of the rice, 24 intragenic molecular markers（representing 17 starch synthesis-related genes） were investigated in 115 Taihu basin rice landraces and 87 improved cultivars simultaneously. The results show that the average genetic diversity and polymorphism information content values of the landraces were higher than those of improved cultivars. In total, 41 and 39 allele combinations（of the 17 genes） were derived from the landraces and improved cultivars, respectively; only two identical allele combinations were found bet ween the two rice variety sources. Cluster analysis, based on the molecular markers, revealed that the rice varieties could be subdivided into five groups and, within these, the japonica improved rice and japonica landrace rice varieties were in two separate groups. According to the quality reference criteria to classify the rice into grades, some of the landraces were found to perform we ll, in terms of starch quality. For example, according to NY /T595-2002 criteria from the Ministry of Agriculture of China, 25 and 33 landraces reached grade 1, in terms of their apparent amylose content and gel consistency. Th e varieties that had outstanding quality could be used as breeding materials for rice quality breeding programs in the future. Our study is useful for future applications, such as genetic diversity studies, the protection of rice variety and improvment of rice quality in breeding programs.
文摘The experimental set-up of SMBI system in HL-2A and the detail structure of the molecular beam valve with cooling trap are shown in Fig.l. The valve used for producing hydrogen cluster jet is a solenoid valve S99 with a nozzle orifice of 0.2 mm diameter. The distance between the nozzle of the valve and the edge plasma is about 1.28 m. A liquid nitrogen cryogenic trap is applied for cooling the valve body and decreasing the working gas temperature. The hydrogen cluster jet used for the experiments is in fact a free jet. For real gases, the adiabatic expansion of gas through a nozzle into vacuum results in substantial cooling in the frame of the moving gas. Atoms or molecules that interact weakly at low temperature can form clusters as a result. Attractive forces between atoms can be hydrogen bonding,
基金This work was supported in part by the Mega-Projects of the National Science Research for the 13th Five-Year Plan(No.2017ZX10201101),Innovation Team Development Program of the Ministry of Education(No.IRT_16R70)the National Natural Science Foundation of China(No.81871637)Central Publicinterest Scientific Institution Basal Research Fund(No.2018PT31042).
文摘Precise identification of HIV transmission among populations is a key step in public health responses.However,the HIV transmission network is usually difficult to determine.HIV molecular networks can be determined by phylogenetic approach,genetic distance-based approach,and a combination of both approaches.These approaches are increasingly used to identify transmission networks among populations,reconstruct the history of HIV spread,monitor the dynamics of HIV transmission,guide targeted intervention on key subpopulations,and assess the effects of interventions.Simulation and retrospective studies have demonstrated that these molecular network-based interventions are more cost-effective than random or traditional interventions.However,we still need to address several challenges to improve the practice of molecular network-guided targeting interventions to finally end the HIV epidemic.The data remain limited or difficult to obtain,and more automatic real-time tools are required.In addition,molecular and social networks must be combined,and technical parameters and ethnic issues warrant further studies.
