Aqueous Zn-iodine batteries(ZIBs)face the formidable challenges towards practical implementation,including metal corrosion and rampant dendrite growth on the Zn anode side,and shuttle effect of polyiodide species from...Aqueous Zn-iodine batteries(ZIBs)face the formidable challenges towards practical implementation,including metal corrosion and rampant dendrite growth on the Zn anode side,and shuttle effect of polyiodide species from the cathode side.These challenges lead to poor cycle stability and severe self-discharge.From the fabrication and cost point of view,it is technologically more viable to deploy electrolyte engineering than electrode protection strategies.More importantly,a synchronous method for modulation of both cathode and anode is pivotal,which has been often neglected in prior studies.In this work,cationic poly(allylamine hydrochloride)(Pah^(+))is adopted as a low-cost dual-function electrolyte additive for ZIBs.We elaborate the synchronous effect by Pah^(+)in stabilizing Zn anode and immobilizing polyiodide anions.The fabricated Zn-iodine coin cell with Pah^(+)(ZnI_(2) loading:25 mg cm^(−2))stably cycles 1000 times at 1 C,and a single-layered 3.4 cm^(2) pouch cell(N/P ratio~1.5)with the same mass loading cycles over 300 times with insignificant capacity decay.展开更多
Single-molecule electroluminescence(SMEL)confines light emission to a well-defined molecular junction,creating a unique platform for probing light-matter interactions at the ultimate spatial limit.This perspective arg...Single-molecule electroluminescence(SMEL)confines light emission to a well-defined molecular junction,creating a unique platform for probing light-matter interactions at the ultimate spatial limit.This perspective argues that four controllable levers—nanocavity plasmons,interface engineering,electric-field modulation,and molecular design—collectively govern the quantum efficiency,spectral characteristics,and excited-state dynamics of SMEL[1].This multifaceted control scheme opens up pathways to transformative technologies,including quantum light sources,single-molecule light-emitting diodes(LEDs),andprogrammable optoelectronic chips.展开更多
We propose a scheme for dual-species deceleration and trapping of a cold atom–molecule mixture by a frequency chirping stimulated force.We study the stimulated force exerted on Mg F and Rb using optical Bloch equatio...We propose a scheme for dual-species deceleration and trapping of a cold atom–molecule mixture by a frequency chirping stimulated force.We study the stimulated force exerted on Mg F and Rb using optical Bloch equations based on a direct numerical solution for the time-dependent density matrix.We analyze the relationship between the frequency chirping rate and the number of Mg F molecules and Rb atoms.In addition,we study the dynamical process of molecular deceleration and the effect of transverse diffusion.Monte–Carlo simulations show that buffer-gas-cooled Mg F and Rb beams,with initial velocities of 200 m/s and 130 m/s respectively,can be decelerated to less than 10 m/s.This is achieved with laser powers of as low as 357 m W for Mg F and 10 m W for Rb per traveling wave.The rapid deceleration minimizes molecular loss due to transverse diffusion during the deceleration process.The estimated number of molecules that can be trapped in a magneto-optical trap(MOT)is about 9.0×10^(6),which is an order of magnitude larger than the number of Mg F molecules decelerated by the spontaneous radiation force.The results offer a promising starting point for further studies of sympathetic cooling.展开更多
Using cumulative quantum mechanics(CQM)and the method of generalized mathematical transfer(MGMT),we analytically study quantum nanometer cumulative-dissipative structures(CDS)and the forces arising within them,which f...Using cumulative quantum mechanics(CQM)and the method of generalized mathematical transfer(MGMT),we analytically study quantum nanometer cumulative-dissipative structures(CDS)and the forces arising within them,which focus nanostructures into regular,fractalized systems—cumulative-dissipative standing hydrogen-like excitons(atoms,molecules,lines,surfaces)and flickering crystals we discovered for the first time.(1)We demonstrate the formation of Vysikaylo standing excitons on permittivity[ε(r)]inhomogeneities in diamond in the nanoscale regions of foreign atoms.(2)For the first time,we solve the problem of measuringε(r)profiles in inhomogeneous nanoscale structures using Raman spectra(RS)[with an accuracy of up to 99.9%forε(r)and a step of up to 0.3 nm depending on the distance from the impurity atom(boron)].(3)Using our theory of Vysikaylo standing excitons,we explain the experimental observation of the degeneracy of electron spectra in standing excitons with respect to the principal quantum number n and n−1/2.By comparing the theory and experimental observations of RS in diamonds doped with boron,we solve the problem(that we formulated previously)between the de Broglie hypothesis and the classical new quantum mechanics of Dirac(which limits the-functions,or prohibits symmetric de Broglie half-waves in spherically and cylindrically symmetric quantum resonators)in favor of the de Broglie hypothesis.Based on the works of Wannier and Mott,we refine the definition of the permittivity of nanocrystals as a coefficient in electric potentials[U(r)→ε(r)U(r)]rather than electric fields[D(r)=ε(r)E(r)].We construct the most complete theory of the chemical doping of crystals(using the example of group IV crystals doped with group III and V atoms).For the first time,we raise the question of the quantum cleaning of crystals or the accumulation of dopant atoms.展开更多
DNA and histone protein are important in the formation of nucleosomal arrays, which are the first packaging level of DNA into a more compact chromatin structure. To characterize the interactions of DNA and histone pro...DNA and histone protein are important in the formation of nucleosomal arrays, which are the first packaging level of DNA into a more compact chromatin structure. To characterize the interactions of DNA and histone proteins, we reconstitute nucleosomes using lambda DNA and whole histone proteins by dialysis and perform direct atomic force microscopy （AFM） imaging. Compared with non-specific DNA and histone binding, nucleosomes are formed within the assembled “beads-on-a-string” nucleosomal array by dialysis. These observations facilitate the establishment of the molecular mechanisms of nucleosome and demonstrate the capability of AFM for protein-DNA interaction analysis.展开更多
Collisions between hot H atoms and CO2 molecules were studied experimentally by time resolved Fourier transform infrared emission spectroscopy. H atoms with three translational energies, 174.7, 241.0 and 306.2 k J/mol...Collisions between hot H atoms and CO2 molecules were studied experimentally by time resolved Fourier transform infrared emission spectroscopy. H atoms with three translational energies, 174.7, 241.0 and 306.2 k J/mol respectively, were generated by UV laser photolysis to initiate a chemical reaction of H＋CO2→OH＋CO. Vibrationally excited CO （v≤2） was observed in the spectrum, where CO was the product of the reaction. The highly efficient T-V energy transfer fro,n the hot H atoms to the CO2 was verified too. The highest vibrational level of v=4 in CO2 （va） was found. Rate ratio of the chemical reaction to the energy transfer was estimated as 10.展开更多
The state selection and beam focus of linear triatomic molecules （OCS, HCN, ClCN, BrCN and ICN） with doubling states in a hexapole electric field have been numerically realized. The method is based on a quantum mech...The state selection and beam focus of linear triatomic molecules （OCS, HCN, ClCN, BrCN and ICN） with doubling states in a hexapole electric field have been numerically realized. The method is based on a quantum mechanical treatment of the molecular Stark energy and a classical mechanical treatment for the molecular trajectory in the field. In linear molecules with doubling states, the second-order Stark effect can be neglected and the doubling states have the same value of J and M. The influences of the molecular properties, state energies, and the apparatus parameters such as molecular beam temperature and length of the hexapole, on the role of state selection and focus have been discussed. The method established here can be taken as a guide for hexapole experiment of orientation of polar molecules.展开更多
Direct liquid fuel cells(DLFCs) have received increasing attention because of their high energy densities,instant recharging abilities, simple cell structure, and facile storage and transport. The main challenge for t...Direct liquid fuel cells(DLFCs) have received increasing attention because of their high energy densities,instant recharging abilities, simple cell structure, and facile storage and transport. The main challenge for the commercialization of DLFCs is the high loading requirement of platinum group metals(PGMs) as catalysts. Atomically dispersed catalysts(ADCs) have been brought into recent focus for DLFCs due to their well-defined active sites, high selectivity, maximal atom-utilization, and anti-poisoning property. In this review, we summarized the structure–property relationship for unveiling the underlying mechanisms of ADCs for DLFCs. More specifically, different types of fuels used in DLFCs such as methanol, formic acid,and ethanol were discussed. At last, we highlighted current challenges, research directions, and future outlooks towards the practical application of DLFCs.展开更多
The results of predicting thermodynamic properties in the full composition range of Ti-Al binary melts in a temperature range from 1973 to 2273 K were obtained by coupling with the developed thermodynamic model for ca...The results of predicting thermodynamic properties in the full composition range of Ti-Al binary melts in a temperature range from 1973 to 2273 K were obtained by coupling with the developed thermodynamic model for calculating mass action concentration N_(i)of structural units in Ti-Al system based on the atom and molecule coexistence theory(AMCT).Temperature dependence of the activity coefficients of Ti and Al in natural logarithmic form in the infinitely dilute solution(0x_(Ti)0.01)of Ti-Al binary melts was also determined from the calculated activity coefficients of Ti and Al at temperatures of 1973,2073,2173,and 2273 K.The standard molar Gibbs free energy change of dissolving pure liquid element i(l)for forming 1%(mass fraction)element i in Ti-Al binary melts further was deduced.With the aid of this model,meanwhile,the determined excess thermodynamic properties,such as the excess molar mixing Gibbs free energy/entropy/enthalpy were also calculated.展开更多
The explicit expressions of energy eigenvalues and eigenfunctions of bound states for a three-dimensional diatomic molecule oscillator with a hyperbolic potential function are obtained approximately by means of the hy...The explicit expressions of energy eigenvalues and eigenfunctions of bound states for a three-dimensional diatomic molecule oscillator with a hyperbolic potential function are obtained approximately by means of the hypergeometric series method. Then for a one-dimensional system, the rigorous solutions of bound states are solved with a similar method. The eigenfunctions of a one-dimensional diatomic molecule oscillator, expressed in terms of the Jacobi polynomial, are employed as an orthonormal basis set, and the analytic expressions of matrix elements for position and momentum operators are given in a closed form.展开更多
Stroke is the second leading cause of disability and mortality worldwide,imposing a substantial socioeconomic burden on individuals and healthcare systems.Annually,approximately 14 million people experience stroke,wit...Stroke is the second leading cause of disability and mortality worldwide,imposing a substantial socioeconomic burden on individuals and healthcare systems.Annually,approximately 14 million people experience stroke,with ischemic stroke comprising nearly 85%of cases,of which 10%to 20%involve large vessel occlusions.Currently,recombinant tissue plasminogen activator(tPA)remains the only approved pharmacological intervention.However,its utility is limited due to a narrow therapeutic window and low recanalization rates,making it applicable to only a minority of patients.Therefore,there is an urgent need for novel therapeutic strategies,including pharmacological advancements and combinatory treatments.Small-molecule natural medicines,particularly those derived from traditional Chinese herbs,have demonstrated significant therapeutic potential in ischemic stroke management.These compounds exert multiple neuroprotective effects,such as antioxidation,anti-inflammatory action,and inhibition of apoptosis,all of which are critical in mitigating stroke-induced cerebral damage.This review comprehensively examines the pathophysiology of acute ischemic stroke(AIS)and highlights the recent progress in the development of small-molecule natural medicines as promising therapeutic agents for cerebral ischemic stroke.展开更多
Nonsequential double ionization （NSDI） processes of nonaligned diatomic molecules N2 and O2 are studied using the S-matrix theory. Our results show that the NSDI process significantly depends on the molecular symmet...Nonsequential double ionization （NSDI） processes of nonaligned diatomic molecules N2 and O2 are studied using the S-matrix theory. Our results show that the NSDI process significantly depends on the molecular symmetry and structure. The ratio of NSDI rate to single ionization rate as a function of the field intensity is obtained. It is found that N2 behaves closely with its companion atom Ar in the ratios over the entire intensity range, while O2 exhibits an obvious suppression effect, which is qualitatively consistent with the experiment.展开更多
Ionization is the fundamental process in interaction of atoms/molecules with femtosecond strong laser fields. Comparing to atoms, molecules exhibit peculiar behaviors in strong-field ionization because of their divers...Ionization is the fundamental process in interaction of atoms/molecules with femtosecond strong laser fields. Comparing to atoms, molecules exhibit peculiar behaviors in strong-field ionization because of their diverse geometric structures, molecular electronic orbitals as well as extra nuclear degrees of freedom. In this study, we investigate strong field single and double ionization of carbon monoxide （CO） and carbon dioxide （CO2） in linearly polarized 50-fs, 800-nm laser fields with peak intensity in the range of 2×10 13 W/cm2 to 2×10 14 W/cm2 using time-of-flight mass spectrometer. By comparing the ionization yields with that of the companion atom krypton （Kr）, which has similar ionization potential to the molecules, we investigate the effect of molecular electronic orbitals on the strong-field ionization. The results show that comparing to Kr, no significant suppression is observed in single ionization of both molecules and in non-sequential double ionization （NSDI） of CO, while the NSDI probability of CO2 is strongly suppressed. Based on our results and previous studies on homonuclear diatomic molecules （N2 and O2）, the mechanism of different suppression effect is discussed. It is indicated that the different structure of the highest occupied molecular orbitals of CO and CO2 leads to distinct behaviors in two-center interference by the electronic wave-packet and angular distributions of the ionized electrons, resulting in different suppression effect in strong-field ionization.展开更多
In the course of time, numerous rules were proposed to predict how atoms connect through covalent bonds. Based on the classification of elements in the periodic table, the rule of eight was first proposed to draw form...In the course of time, numerous rules were proposed to predict how atoms connect through covalent bonds. Based on the classification of elements in the periodic table, the rule of eight was first proposed to draw formulas of organic compounds. The later named octet rule exhibited shortcomings when applied to inorganic compounds. Another rule, the rule of two, using covalent bonds between atoms, was proposed as an attempt to unify description of organic and inorganic molecules. This rule unfortunately never managed to expand the field of application of the octet rule to inorganic compounds. In order to conciliate organic and inorganic compounds, the recently put forward even-odd and the isoelectronicity rules suggest the creation of one group of compounds with pairs of electrons. These rules compass the rule of two for covalent bonds as well as the octet rule for organic compounds and suggest transforming bonds of multi-bonded compounds in order to unify representations of both groups of compounds. The aim of the present paper is fourfold: to extend the rule of two to every atom shells;to replace the well-known octet rule by the even-odd rule;to apply the isoelectronicity rule to each atom and to reduce the influence range of the charge of an atom in a compound. According to both rules, the drawing of one atom with its single-covalent bonds is described with electron pairs and charge positions. To illustrate the rules, they are applied to 3D configurations of clusters.展开更多
Two calculation methods on the partition functions for diatomic molecules in plas- mas out of thermal equilibrium are reported. A Boltzmann distribution for the electronic, vi- brational and rotational quantum levels ...Two calculation methods on the partition functions for diatomic molecules in plas- mas out of thermal equilibrium are reported. A Boltzmann distribution for the electronic, vi- brational and rotational quantum levels is assumed in the two calculation methods. The results obtained by two methods are displayed for four sorts of diatomic molecules, 02, N2, OH and NO, that are present in humid air plasmas. The calculation method of density for the electronically excited states is developed. Finally, a method to calculate the partition functions for simulating the non-normalized diatomic spectra is discussed.展开更多
A new method on constructing analytical potential energy functions is presented, and then a relatively universal analytical potential energy function for precisely calculating the spectra of ＇iatomic molecules and io...A new method on constructing analytical potential energy functions is presented, and then a relatively universal analytical potential energy function for precisely calculating the spectra of ＇iatomic molecules and ions is derived. Furthermore, six kinds of common potential energy curves containing three main potential curves i,e. steady state, metastable state and repulsive state are obtained from this potential energy function. Finally, spectroscopic parameters of thirteen diatomic molecules and ions including BeD-X^2∑＋, BeT-X^2∑^＋ and Na2-X^1∑g^＋ etc are calculated by using the potential function, as a consequence, all calculation results are in good agreement with experimental data.展开更多
The tensile strain in inorganic perovskite films induced by thermal annealing is one of the primary factors contributing to the inefficiency and instability of inorganic perovskite solar cells(IPSCs),which reduces the...The tensile strain in inorganic perovskite films induced by thermal annealing is one of the primary factors contributing to the inefficiency and instability of inorganic perovskite solar cells(IPSCs),which reduces the defect formation energy.Here,a flexible molecule 5-maleimidovaleric acid(5-MVA)was introduced as a strain buffer to release the residual strain of CsPbI_(2.85)Br_(0.15)perovskite.Maleic anhydride and carboxyl groups in 5-MVA interact strongly with the uncoordinated Pb^(2+)through Lewis acid-base reaction,thus tightly“pull”the perovskite lattice.The in-between soft carbon chain increased the structural flexibility of CsPbI_(2.85)Br_(0.15)perovskite materials,which effectively relieved the intrinsic internal strain of CsPbI_(2.85)Br_(0.15),resisted the corrosion of external strain,and also reduced the formation of defects such as VIand Pb0.In addition,the introduction of 5-MVA improved crystal quality,passivated residual defects,and narrowed energy level barriers.Eventually,power conversion efficiency(PCE)of NiOxbased inverted IPSCs increased from 19.25%to 20.82%with the open-circuit voltage enhanced from 1.164 V to 1.230 V.The release of strain also improved the stability of CsPbI_(2.85)Br_(0.15)perovskite films and devices.展开更多
Building on the recent success of the even-odd rule, the present paper explores its implications by studying the very specific case of OXO compounds. These compounds are usually represented with double bonds linking t...Building on the recent success of the even-odd rule, the present paper explores its implications by studying the very specific case of OXO compounds. These compounds are usually represented with double bonds linking two oxygen atoms to a central atom—as in carbon dioxyde—yet can sometimes be drawn in a triangular structure, such as in calcium dioxyde. Measurement data moreover indicate that most OXO compounds have an angle around 120° between oxygen atoms, although that seems incompatible with triangular representations. The aim here is to unify these commonly admitted representations by linking oxygen atoms through a single bond that is longer than usual covalent bonds: an “elongated bond”. This elongated bond has the interesting effect of suppressing the need for double bonds between oxygen and the central atom. The elongated bond concept is applied to about a hundred of molecules and ions and methodically compared to classical representations. It is shown that this new representation, associated to the even-odd rule, is compatible with all studied compounds and can be used in place of their classical drawings. Its usage greatly simplifies complex concepts like resonance and separated charges in gases. Elongated bonds are also shown to be practicable with the isoelectronic rule as well as isomers, and throughout chemical reactions. This study of an especially long and wide angle bond confirms the versatility of the even-odd rule: it is not limited to compounds with short covalent bonds and can include OO covalent bond lengths of more than 200 pm and with OXO angles above 90°.展开更多
Dissociations in the gas phase of small molecules have been intensively studied and dissociation energies of various gases are available in reference works. Configurations of compounds before and after the dissociatio...Dissociations in the gas phase of small molecules have been intensively studied and dissociation energies of various gases are available in reference works. Configurations of compounds before and after the dissociation are usually known</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">but local charges are not defined. Building on the even-odd rule, the topic of a series of previous articles by the same author, the objective of this paper is to show how it can be used to give electronic rules for dissociations in gases. To this end, a specific periodic table is created and used. The rules are applied to a selection of more than 30 common molecules, showing that the even-odd rule and its consequences are useful in explaining the phenomenon of dissociation in gases.展开更多
In this paper, a new method on constructing analytical potential energy functions is pre-sented, and from this a analytical potential en-ergy function applied to both neutral diatomic molecules and charged diatomic mo...In this paper, a new method on constructing analytical potential energy functions is pre-sented, and from this a analytical potential en-ergy function applied to both neutral diatomic molecules and charged diatomic molecular ions is obtained. This potential energy function in-cludes three dimensionless undetermined pa-rameters which can be determined uniquely by solving linear equations with the experimental spectroscopic parameters of molecules. The solutions of the dimensionless undetermined parameters are real numbers rather than com-plex numbers, this ensures that the analytical potential energy function has extensive uni-versality. Finally, the potential energy function is examined with four kinds of diatomic molecules or ions—homonuclear neutral diatomic mole-cule , and , homonuclear charged diatomic molecular ion , and , heter-nuclear neutral diatomic Molecule , and , heternuclear ch- arged diatomic Molecular ion , and ,as a conseque- nce, good results are obtained.展开更多
基金supported by the financial support from the National Research Foundation,Singapore,under its Singapore-China Joint Flagship Project(Clean Energy).
文摘Aqueous Zn-iodine batteries(ZIBs)face the formidable challenges towards practical implementation,including metal corrosion and rampant dendrite growth on the Zn anode side,and shuttle effect of polyiodide species from the cathode side.These challenges lead to poor cycle stability and severe self-discharge.From the fabrication and cost point of view,it is technologically more viable to deploy electrolyte engineering than electrode protection strategies.More importantly,a synchronous method for modulation of both cathode and anode is pivotal,which has been often neglected in prior studies.In this work,cationic poly(allylamine hydrochloride)(Pah^(+))is adopted as a low-cost dual-function electrolyte additive for ZIBs.We elaborate the synchronous effect by Pah^(+)in stabilizing Zn anode and immobilizing polyiodide anions.The fabricated Zn-iodine coin cell with Pah^(+)(ZnI_(2) loading:25 mg cm^(−2))stably cycles 1000 times at 1 C,and a single-layered 3.4 cm^(2) pouch cell(N/P ratio~1.5)with the same mass loading cycles over 300 times with insignificant capacity decay.
基金supported by the National Key R&D Program of China(2024YFA1208100,2021YFA1200102,2021YFA1200101,2023YFF1205803,and 2022YFE0128700)the National Natural Science Foundation of China(22173050 and 22595390)Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202407).
文摘Single-molecule electroluminescence(SMEL)confines light emission to a well-defined molecular junction,creating a unique platform for probing light-matter interactions at the ultimate spatial limit.This perspective argues that four controllable levers—nanocavity plasmons,interface engineering,electric-field modulation,and molecular design—collectively govern the quantum efficiency,spectral characteristics,and excited-state dynamics of SMEL[1].This multifaceted control scheme opens up pathways to transformative technologies,including quantum light sources,single-molecule light-emitting diodes(LEDs),andprogrammable optoelectronic chips.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12174115 and 91836103)。
文摘We propose a scheme for dual-species deceleration and trapping of a cold atom–molecule mixture by a frequency chirping stimulated force.We study the stimulated force exerted on Mg F and Rb using optical Bloch equations based on a direct numerical solution for the time-dependent density matrix.We analyze the relationship between the frequency chirping rate and the number of Mg F molecules and Rb atoms.In addition,we study the dynamical process of molecular deceleration and the effect of transverse diffusion.Monte–Carlo simulations show that buffer-gas-cooled Mg F and Rb beams,with initial velocities of 200 m/s and 130 m/s respectively,can be decelerated to less than 10 m/s.This is achieved with laser powers of as low as 357 m W for Mg F and 10 m W for Rb per traveling wave.The rapid deceleration minimizes molecular loss due to transverse diffusion during the deceleration process.The estimated number of molecules that can be trapped in a magneto-optical trap(MOT)is about 9.0×10^(6),which is an order of magnitude larger than the number of Mg F molecules decelerated by the spontaneous radiation force.The results offer a promising starting point for further studies of sympathetic cooling.
文摘Using cumulative quantum mechanics(CQM)and the method of generalized mathematical transfer(MGMT),we analytically study quantum nanometer cumulative-dissipative structures(CDS)and the forces arising within them,which focus nanostructures into regular,fractalized systems—cumulative-dissipative standing hydrogen-like excitons(atoms,molecules,lines,surfaces)and flickering crystals we discovered for the first time.(1)We demonstrate the formation of Vysikaylo standing excitons on permittivity[ε(r)]inhomogeneities in diamond in the nanoscale regions of foreign atoms.(2)For the first time,we solve the problem of measuringε(r)profiles in inhomogeneous nanoscale structures using Raman spectra(RS)[with an accuracy of up to 99.9%forε(r)and a step of up to 0.3 nm depending on the distance from the impurity atom(boron)].(3)Using our theory of Vysikaylo standing excitons,we explain the experimental observation of the degeneracy of electron spectra in standing excitons with respect to the principal quantum number n and n−1/2.By comparing the theory and experimental observations of RS in diamonds doped with boron,we solve the problem(that we formulated previously)between the de Broglie hypothesis and the classical new quantum mechanics of Dirac(which limits the-functions,or prohibits symmetric de Broglie half-waves in spherically and cylindrically symmetric quantum resonators)in favor of the de Broglie hypothesis.Based on the works of Wannier and Mott,we refine the definition of the permittivity of nanocrystals as a coefficient in electric potentials[U(r)→ε(r)U(r)]rather than electric fields[D(r)=ε(r)E(r)].We construct the most complete theory of the chemical doping of crystals(using the example of group IV crystals doped with group III and V atoms).For the first time,we raise the question of the quantum cleaning of crystals or the accumulation of dopant atoms.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.11274374）, the National Basic Research Program of China （No.2009CB930704）, and the Basic Scientific Research Foundation of China Agricultural University （No.2012QJ026）.
文摘DNA and histone protein are important in the formation of nucleosomal arrays, which are the first packaging level of DNA into a more compact chromatin structure. To characterize the interactions of DNA and histone proteins, we reconstitute nucleosomes using lambda DNA and whole histone proteins by dialysis and perform direct atomic force microscopy （AFM） imaging. Compared with non-specific DNA and histone binding, nucleosomes are formed within the assembled “beads-on-a-string” nucleosomal array by dialysis. These observations facilitate the establishment of the molecular mechanisms of nucleosome and demonstrate the capability of AFM for protein-DNA interaction analysis.
基金supported by the National Natural Science Foundation of China and the National Basic Research Program of China(973 Program).
文摘Collisions between hot H atoms and CO2 molecules were studied experimentally by time resolved Fourier transform infrared emission spectroscopy. H atoms with three translational energies, 174.7, 241.0 and 306.2 k J/mol respectively, were generated by UV laser photolysis to initiate a chemical reaction of H＋CO2→OH＋CO. Vibrationally excited CO （v≤2） was observed in the spectrum, where CO was the product of the reaction. The highly efficient T-V energy transfer fro,n the hot H atoms to the CO2 was verified too. The highest vibrational level of v=4 in CO2 （va） was found. Rate ratio of the chemical reaction to the energy transfer was estimated as 10.
基金Supported by the National Natural Science Foundation of China and the Specialized Research Fund for the Doctoral Programme of Higher Education of China.
文摘The state selection and beam focus of linear triatomic molecules （OCS, HCN, ClCN, BrCN and ICN） with doubling states in a hexapole electric field have been numerically realized. The method is based on a quantum mechanical treatment of the molecular Stark energy and a classical mechanical treatment for the molecular trajectory in the field. In linear molecules with doubling states, the second-order Stark effect can be neglected and the doubling states have the same value of J and M. The influences of the molecular properties, state energies, and the apparatus parameters such as molecular beam temperature and length of the hexapole, on the role of state selection and focus have been discussed. The method established here can be taken as a guide for hexapole experiment of orientation of polar molecules.
基金financial supports from the National Science Foundation under Grant Nos. CBET-1949840 and CMMI-1851674financial support from the Preeminent Postdoctoral Program (P3) of the University of Central Florida。
文摘Direct liquid fuel cells(DLFCs) have received increasing attention because of their high energy densities,instant recharging abilities, simple cell structure, and facile storage and transport. The main challenge for the commercialization of DLFCs is the high loading requirement of platinum group metals(PGMs) as catalysts. Atomically dispersed catalysts(ADCs) have been brought into recent focus for DLFCs due to their well-defined active sites, high selectivity, maximal atom-utilization, and anti-poisoning property. In this review, we summarized the structure–property relationship for unveiling the underlying mechanisms of ADCs for DLFCs. More specifically, different types of fuels used in DLFCs such as methanol, formic acid,and ethanol were discussed. At last, we highlighted current challenges, research directions, and future outlooks towards the practical application of DLFCs.
基金Project(U1560203)supported by the Joint Funds of the National Natural Science Foundation of ChinaProject(51274031)supported by the National Natural Science Foundation of China
文摘The results of predicting thermodynamic properties in the full composition range of Ti-Al binary melts in a temperature range from 1973 to 2273 K were obtained by coupling with the developed thermodynamic model for calculating mass action concentration N_(i)of structural units in Ti-Al system based on the atom and molecule coexistence theory(AMCT).Temperature dependence of the activity coefficients of Ti and Al in natural logarithmic form in the infinitely dilute solution(0x_(Ti)0.01)of Ti-Al binary melts was also determined from the calculated activity coefficients of Ti and Al at temperatures of 1973,2073,2173,and 2273 K.The standard molar Gibbs free energy change of dissolving pure liquid element i(l)for forming 1%(mass fraction)element i in Ti-Al binary melts further was deduced.With the aid of this model,meanwhile,the determined excess thermodynamic properties,such as the excess molar mixing Gibbs free energy/entropy/enthalpy were also calculated.
基金Project supported by the National Natural Science Foundation of China （Grant No 90403028）.
文摘The explicit expressions of energy eigenvalues and eigenfunctions of bound states for a three-dimensional diatomic molecule oscillator with a hyperbolic potential function are obtained approximately by means of the hypergeometric series method. Then for a one-dimensional system, the rigorous solutions of bound states are solved with a similar method. The eigenfunctions of a one-dimensional diatomic molecule oscillator, expressed in terms of the Jacobi polynomial, are employed as an orthonormal basis set, and the analytic expressions of matrix elements for position and momentum operators are given in a closed form.
基金supported by the National Natural Science Foundation of China(Nos.82174010 and 81973512)。
文摘Stroke is the second leading cause of disability and mortality worldwide,imposing a substantial socioeconomic burden on individuals and healthcare systems.Annually,approximately 14 million people experience stroke,with ischemic stroke comprising nearly 85%of cases,of which 10%to 20%involve large vessel occlusions.Currently,recombinant tissue plasminogen activator(tPA)remains the only approved pharmacological intervention.However,its utility is limited due to a narrow therapeutic window and low recanalization rates,making it applicable to only a minority of patients.Therefore,there is an urgent need for novel therapeutic strategies,including pharmacological advancements and combinatory treatments.Small-molecule natural medicines,particularly those derived from traditional Chinese herbs,have demonstrated significant therapeutic potential in ischemic stroke management.These compounds exert multiple neuroprotective effects,such as antioxidation,anti-inflammatory action,and inhibition of apoptosis,all of which are critical in mitigating stroke-induced cerebral damage.This review comprehensively examines the pathophysiology of acute ischemic stroke(AIS)and highlights the recent progress in the development of small-molecule natural medicines as promising therapeutic agents for cerebral ischemic stroke.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11074026, 11074155, and 11104225)the Program for New Century Excellent Talents in University of the Ministry of Education of China (Grant No. NCET-08-0883)the National Basic Research Program of China (Grant No. 2011CB808100)
文摘Nonsequential double ionization （NSDI） processes of nonaligned diatomic molecules N2 and O2 are studied using the S-matrix theory. Our results show that the NSDI process significantly depends on the molecular symmetry and structure. The ratio of NSDI rate to single ionization rate as a function of the field intensity is obtained. It is found that N2 behaves closely with its companion atom Ar in the ratios over the entire intensity range, while O2 exhibits an obvious suppression effect, which is qualitatively consistent with the experiment.
文摘Ionization is the fundamental process in interaction of atoms/molecules with femtosecond strong laser fields. Comparing to atoms, molecules exhibit peculiar behaviors in strong-field ionization because of their diverse geometric structures, molecular electronic orbitals as well as extra nuclear degrees of freedom. In this study, we investigate strong field single and double ionization of carbon monoxide （CO） and carbon dioxide （CO2） in linearly polarized 50-fs, 800-nm laser fields with peak intensity in the range of 2×10 13 W/cm2 to 2×10 14 W/cm2 using time-of-flight mass spectrometer. By comparing the ionization yields with that of the companion atom krypton （Kr）, which has similar ionization potential to the molecules, we investigate the effect of molecular electronic orbitals on the strong-field ionization. The results show that comparing to Kr, no significant suppression is observed in single ionization of both molecules and in non-sequential double ionization （NSDI） of CO, while the NSDI probability of CO2 is strongly suppressed. Based on our results and previous studies on homonuclear diatomic molecules （N2 and O2）, the mechanism of different suppression effect is discussed. It is indicated that the different structure of the highest occupied molecular orbitals of CO and CO2 leads to distinct behaviors in two-center interference by the electronic wave-packet and angular distributions of the ionized electrons, resulting in different suppression effect in strong-field ionization.
文摘In the course of time, numerous rules were proposed to predict how atoms connect through covalent bonds. Based on the classification of elements in the periodic table, the rule of eight was first proposed to draw formulas of organic compounds. The later named octet rule exhibited shortcomings when applied to inorganic compounds. Another rule, the rule of two, using covalent bonds between atoms, was proposed as an attempt to unify description of organic and inorganic molecules. This rule unfortunately never managed to expand the field of application of the octet rule to inorganic compounds. In order to conciliate organic and inorganic compounds, the recently put forward even-odd and the isoelectronicity rules suggest the creation of one group of compounds with pairs of electrons. These rules compass the rule of two for covalent bonds as well as the octet rule for organic compounds and suggest transforming bonds of multi-bonded compounds in order to unify representations of both groups of compounds. The aim of the present paper is fourfold: to extend the rule of two to every atom shells;to replace the well-known octet rule by the even-odd rule;to apply the isoelectronicity rule to each atom and to reduce the influence range of the charge of an atom in a compound. According to both rules, the drawing of one atom with its single-covalent bonds is described with electron pairs and charge positions. To illustrate the rules, they are applied to 3D configurations of clusters.
文摘Two calculation methods on the partition functions for diatomic molecules in plas- mas out of thermal equilibrium are reported. A Boltzmann distribution for the electronic, vi- brational and rotational quantum levels is assumed in the two calculation methods. The results obtained by two methods are displayed for four sorts of diatomic molecules, 02, N2, OH and NO, that are present in humid air plasmas. The calculation method of density for the electronically excited states is developed. Finally, a method to calculate the partition functions for simulating the non-normalized diatomic spectra is discussed.
基金the National Natural Science Foundation of China (40274044)
文摘A new method on constructing analytical potential energy functions is presented, and then a relatively universal analytical potential energy function for precisely calculating the spectra of ＇iatomic molecules and ions is derived. Furthermore, six kinds of common potential energy curves containing three main potential curves i,e. steady state, metastable state and repulsive state are obtained from this potential energy function. Finally, spectroscopic parameters of thirteen diatomic molecules and ions including BeD-X^2∑＋, BeT-X^2∑^＋ and Na2-X^1∑g^＋ etc are calculated by using the potential function, as a consequence, all calculation results are in good agreement with experimental data.
基金financial support of National Key Research and Development Program of China(Grant No.2022YFB04200302)joint funds of National Natural Science Foundation of China(Grant No.62104115)+5 种基金National Natural Science Foundation of China(Grant No.U21A2072)Overseas Expertise Introduction Project for Discipline Innovation of Higher Education of China(Grant No.B16027)Key R&D Program of Hebei Province(No.19214301D)Yunnan Provincial Science and Technology Project at Southwest United Graduate School(No.202302A0370009)Haihe Laboratory of Sustainable Chemical TransformationsFundamental Research Funds for the Central Universities,Nankai University。
文摘The tensile strain in inorganic perovskite films induced by thermal annealing is one of the primary factors contributing to the inefficiency and instability of inorganic perovskite solar cells(IPSCs),which reduces the defect formation energy.Here,a flexible molecule 5-maleimidovaleric acid(5-MVA)was introduced as a strain buffer to release the residual strain of CsPbI_(2.85)Br_(0.15)perovskite.Maleic anhydride and carboxyl groups in 5-MVA interact strongly with the uncoordinated Pb^(2+)through Lewis acid-base reaction,thus tightly“pull”the perovskite lattice.The in-between soft carbon chain increased the structural flexibility of CsPbI_(2.85)Br_(0.15)perovskite materials,which effectively relieved the intrinsic internal strain of CsPbI_(2.85)Br_(0.15),resisted the corrosion of external strain,and also reduced the formation of defects such as VIand Pb0.In addition,the introduction of 5-MVA improved crystal quality,passivated residual defects,and narrowed energy level barriers.Eventually,power conversion efficiency(PCE)of NiOxbased inverted IPSCs increased from 19.25%to 20.82%with the open-circuit voltage enhanced from 1.164 V to 1.230 V.The release of strain also improved the stability of CsPbI_(2.85)Br_(0.15)perovskite films and devices.
文摘Building on the recent success of the even-odd rule, the present paper explores its implications by studying the very specific case of OXO compounds. These compounds are usually represented with double bonds linking two oxygen atoms to a central atom—as in carbon dioxyde—yet can sometimes be drawn in a triangular structure, such as in calcium dioxyde. Measurement data moreover indicate that most OXO compounds have an angle around 120° between oxygen atoms, although that seems incompatible with triangular representations. The aim here is to unify these commonly admitted representations by linking oxygen atoms through a single bond that is longer than usual covalent bonds: an “elongated bond”. This elongated bond has the interesting effect of suppressing the need for double bonds between oxygen and the central atom. The elongated bond concept is applied to about a hundred of molecules and ions and methodically compared to classical representations. It is shown that this new representation, associated to the even-odd rule, is compatible with all studied compounds and can be used in place of their classical drawings. Its usage greatly simplifies complex concepts like resonance and separated charges in gases. Elongated bonds are also shown to be practicable with the isoelectronic rule as well as isomers, and throughout chemical reactions. This study of an especially long and wide angle bond confirms the versatility of the even-odd rule: it is not limited to compounds with short covalent bonds and can include OO covalent bond lengths of more than 200 pm and with OXO angles above 90°.
文摘Dissociations in the gas phase of small molecules have been intensively studied and dissociation energies of various gases are available in reference works. Configurations of compounds before and after the dissociation are usually known</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">but local charges are not defined. Building on the even-odd rule, the topic of a series of previous articles by the same author, the objective of this paper is to show how it can be used to give electronic rules for dissociations in gases. To this end, a specific periodic table is created and used. The rules are applied to a selection of more than 30 common molecules, showing that the even-odd rule and its consequences are useful in explaining the phenomenon of dissociation in gases.
文摘In this paper, a new method on constructing analytical potential energy functions is pre-sented, and from this a analytical potential en-ergy function applied to both neutral diatomic molecules and charged diatomic molecular ions is obtained. This potential energy function in-cludes three dimensionless undetermined pa-rameters which can be determined uniquely by solving linear equations with the experimental spectroscopic parameters of molecules. The solutions of the dimensionless undetermined parameters are real numbers rather than com-plex numbers, this ensures that the analytical potential energy function has extensive uni-versality. Finally, the potential energy function is examined with four kinds of diatomic molecules or ions—homonuclear neutral diatomic mole-cule , and , homonuclear charged diatomic molecular ion , and , heter-nuclear neutral diatomic Molecule , and , heternuclear ch- arged diatomic Molecular ion , and ,as a conseque- nce, good results are obtained.
