Water management within the membrane electrode assemblies(MEAs)of electrochemical hydrogen compressors(EHCs)plays a crucial role in optimizing overall performance,particularly under low relative humidity(RH),where the...Water management within the membrane electrode assemblies(MEAs)of electrochemical hydrogen compressors(EHCs)plays a crucial role in optimizing overall performance,particularly under low relative humidity(RH),where the anode side tends to dry out.Hollow mesoporous silica nanoparticles functionalized with amino groups(HMSNs-NH_(2))were integrated into the anode catalyst layers of EHCs to establish humidity-independent proton pathways through acid-base interactions with Nafion ionomers.These acid-base pairs between grafted–NH_(2)and sulfonic acid groups create continuous“proton highways”,enabling efficient conduction via the Grotthuss mechanism even at 50%RH.With only 2.5 wt%HMSNs-NH_(2)in the anode catalyst layer,hydrogen was compressed to 0.9 MPa in 60±3 s at 50%RH,representing a 55%reduction in compression time compared to MEAs with conventional Pt/C catalyst layers under the same conditions.This work overcomes the critical water-management bottleneck in EHCs,advancing the deployment of hydrogen energy technologies in arid environments.展开更多
We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-ly...We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.展开更多
We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by contro...We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the intercavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons.展开更多
Lithium metal batteries,with their light mass anode and high theoretical specific capacity of 3860 m Ah/g,have great potential for development in achieving high energy density.However,the generation of lithium dendrit...Lithium metal batteries,with their light mass anode and high theoretical specific capacity of 3860 m Ah/g,have great potential for development in achieving high energy density.However,the generation of lithium dendrites and the loss of dead lithium pose a serious threat to the safety and long-cycle stability of batteries.Herein,we utilize the Lewis acid-base interaction principle for lithium-ion migration regulation.Through loading solid-acids onto molecular sieves to immobilize Lewis base(PF_(6^(-))),we achieve accelerated dissociation of lithium salts and successfully increase the lithium ion transference number to 0.44.Lewis acid-base interaction helps lithium metal batteries achieve more uniform lithium deposition,with an average CE improved to 92.8%.The symmetrical cells can be plated/stripped stably for more than 800 h of cycling.Full cell with high surface-loaded LFP cathode(14 mg/cm^(2))exhibits impressively high capacity retention of 90.7%after 120 cycles at 0.5 C.展开更多
This paper is committed to exploring the importance of learner learner interaction for language learning. It starts with a discussion of the roles that learner learner interaction plays in language learning from two p...This paper is committed to exploring the importance of learner learner interaction for language learning. It starts with a discussion of the roles that learner learner interaction plays in language learning from two points of view pedagogic and psycholinguistic, which is followed by a brief guideline for organizing group work in class.展开更多
A numerical simulation was performed to investigate the interaction of two bubbles rising side by side in shear-thinning fluid using volume of fluid （VOF） method coupled with continuous surface force （CSF） method....A numerical simulation was performed to investigate the interaction of two bubbles rising side by side in shear-thinning fluid using volume of fluid （VOF） method coupled with continuous surface force （CSF） method. By considering rheological characteristics of fluid, this approach was able to accurately capture the deformation of bubble interface, and validated by comparing with the experimental results. The rising of bubble pairs with different configurations, including horizontal alignment and oblique alignment, was simulated by the method. The influences of the bubble initial distance and the bubble alignment were studied by analyzing the bubble deformation, rising paths and flow fields surrounding bubbles. The results indicate that within certam mltlal bubble spacing of S = 3.3 （S＊ = SI/D, SI initial distance between bubbles, and D bubble diameter）, the dynamic interaction between two bub- bles aligned horizontally shows repulsive effect that decreases with the increase of initial bubble spacing, but weakens to certain degree by the shear-thinning properties of fluid. However, the interaction between two bubbles aligned obliquely presents a repulsive effect for the small angle involved but an attractive impact for the large one, which is vet strengthened by the rheological characteristics of fluid.展开更多
In this article,a comprehensive study of the fission process of Th,U,Pu,and Cm isotopes using a Yukawa-folded meanfield plus standard pairing model is presented.The study focused on analyzing the effects of the pairin...In this article,a comprehensive study of the fission process of Th,U,Pu,and Cm isotopes using a Yukawa-folded meanfield plus standard pairing model is presented.The study focused on analyzing the effects of the pairing interaction on the fragment mass distribution and its dependence on nuclear elongation.The significant role of pairing interactions in the fragment mass distributions of^(230)Th,^(234)U,^(240)Pu,and^(246)Cm was demonstrated.Numerical analysis revealed that increasing the pairing interaction strength decreased the asymmetric fragment mass distribution and increased the symmetric distribution.Furthermore,the odd-even mass differences at symmetric and asymmetric fission points were examined,highlighting their sensitivity to changes in the pairing interaction strength.Systematic analysis of the Th,U,Pu,and Cm isotope fragment mass distributions demonstrated the effectiveness of the model in reproducing the experimental data.In addition,the effects of the zero-point energy and half-width parameter on the fragment mass distribution for^(240)Pu were explored.Thus,this study provides valuable insights into the fission process by emphasizing the importance of pairing interactions and their relationship with nuclear elongation.展开更多
The single photon scattering properties in a pair of waveguides coupled by a whispering-gallery resonator in- teracting with a semiconductor quantum dot are investigated theoretically. The two waveguides support four ...The single photon scattering properties in a pair of waveguides coupled by a whispering-gallery resonator in- teracting with a semiconductor quantum dot are investigated theoretically. The two waveguides support four possible ports for an incident single photon. The quantum dot is considered a V-type system. The incident direction-dependent single photon scattering properties are studied and equal-output probability from the four ports for a single photon incident is discussed. The influences of backscattering between the two modes of the whispering-gallery resonator for incident direction-dependent single photon scattering properties are also pre- sented.展开更多
Two novel acid-base adducts,[H2L1^2＋]（Hpbda）2（1,L1 = 1,4-di（lH-imidazol-4-yl）benzene,H2pbda = 1,4-benzenedicarboxylic acid） and[H2L2^2＋]（NO3）2（2,L2 = l,4-di（l-carboxymethyl-imidazol-4-yl）benzene）,have be...Two novel acid-base adducts,[H2L1^2＋]（Hpbda）2（1,L1 = 1,4-di（lH-imidazol-4-yl）benzene,H2pbda = 1,4-benzenedicarboxylic acid） and[H2L2^2＋]（NO3）2（2,L2 = l,4-di（l-carboxymethyl-imidazol-4-yl）benzene）,have been prepared and characterized by single-crystal X-ray diffraction,IR spectroscopy and elemental analysis.Compound 1 crystallizes in monoclinic,space group P21/n with a = 5.3525（11）,b = 9.1471（19）,c = 19.314（4） ？,β = 92.342（3）°,V= 944.8（3） A°3,Z = 2,C16H16N6O（10）,Mr = 452.35,Dc = 1.590 g/cm^3,μ = 0.135 mm^-1,S = 1.058,F（000） = 468,the final R = 0.0661 and wR = 0.1887 for 2298 observed reflections（I〉 2σ（I））.Compound 2 crystallizes in monoclinic,space group P21/c with a = 9.6923（10）,b = 17.2950（17）,c = 7.1880（7） ？,β =94.801（2）°,V= 1200.7（2）A°3,Z = 2,C（28）H（22）N4O8,Mr = 542.50,Dc = 1.501 g/cm^3,μ = 0.112 mm^-1,S= 1.060,F（000） = 564,the final R = 0.0394 and wR = 0.1017 for 2768 observed reflections（I 〉2σ（I））.In the title compounds,both of L1 and L2 ligands act as weak base to accept protons to exhibit diprotonated H2L1^2＋ and H2L2^2＋ form,which can effectively employ as hydrogen bonding donors to combine anion moieties to form binary adducts respectively.In the crystal packing diagram of two polymers,there exist extensive noncovalent interactions including charge-transfer interactions,C（N）-H…π and N-H…O,C-H…O,O-H…O hydrogen bonding interactions between co-crystal moieties which consolidate the structures of supramolecular polymers,thus generating three-dimensional（3D） frameworks.展开更多
Solid-aqueous interfaces and phenomena occurring at those interfaces are ubiquitously found in a plethora of chemical systems.When it comes to heterogeneous catalysis,however,our understanding of chemical transformati...Solid-aqueous interfaces and phenomena occurring at those interfaces are ubiquitously found in a plethora of chemical systems.When it comes to heterogeneous catalysis,however,our understanding of chemical transformations at solid-aqueous interfaces is relatively limited and primitive.This review phenomenologically describes a selection of water-engendered effects on the catalytic behavior for several prototypical acid-base-catalyzed reactions over solid catalysts,and critically assesses the general and special roles of water molecules,structural moieties derived from water,and ionic species that are dissolved in it,with an aim to extract novel concepts and principles that underpin heterogeneous acid-base catalysis in the aqueous phase.For alcohol dehydration catalyzed by solid Bronsted acids,rate inhibition by water is most typically related to the decrease in the acid strength and/or the preferential solvation of adsorbed species over the transition state as water molecules progressively solvate the acid site and form extended networks wherein protons are mobilized.Water also inhibits dehydration kinetics over most Lewis acid-base catalysts by competitive adsorption,but a few scattered reports reveal substantial rate enhancements due to the conversion of Lewis acid sites to Brønsted acid sites with higher catalytic activities upon the introduction of water.For aldol condensation on catalysts exposing Lewis acid-base pairs,the addition of water is generally observed to enhance the rate when C–C coupling is rate-limiting,but may result in rate inhibition by site-blocking when the initial unimolecular deprotonation is rate-limiting.Water can also promote aldol condensation on Brønsted acidic catalysts by facilitating inter-site communication between acid sites through hydrogen-bonding interactions.For metallozeolite-catalyzed sugar isomerization in aqueous media,the nucleation and networking of intrapore waters regulated by hydrophilic entities causes characteristic enthalpy-entropy tradeoffs as these water moieties interact with kinetically relevant hydride transfer transition states.The discussed examples collectively highlight the utmost importance of hydrogen-bonding interactions and ionization of covalently bonded surface moieties as the main factors underlying the uniqueness of water-mediated interfacial acid-base chemistries and the associated solvation effects in the aqueous phase or in the presence of water.A perspective is also provided for future research in this vibrant field.展开更多
Ab initio calculations were performed using the Gaussian 03 software package to obtain the optimized structure,interaction energy and infrared spectrum of ionic liquids(ILs)containing a tetraalkylphosphonium cation an...Ab initio calculations were performed using the Gaussian 03 software package to obtain the optimized structure,interaction energy and infrared spectrum of ionic liquids(ILs)containing a tetraalkylphosphonium cation and an amino acid anion.In order to investigate the effect of the presence of nitrogen in the cation,the tetraalkylphosphonium cation was replaced by a tetraalkylammonium cation,while amino acids were retained as anions in the ionic liquid.The amino acids studied here included glycine,alanine,serine,lysine,and glutamine.Optimized structures of several ILs in the gas phase were determined at the levels of Hartree-Fock(HF/6-3+G(d))and 1density functional theory(B3LYP/6-31++G(d,p)).At high-level estimations,MP2/6-31+G(d)and MP2/6-31++G(d,p),the interaction energies between the cations and anions of the ILs were determined.In order to investigate the effect of alkyl-chain length on interaction energy,the alkyl groups were varied from methyl to ethyl and propyl in the tetraalkylphosphonium functional groups.This procedure revealed that there is a considerably stronger interaction between the alkylphosphonium cations and amino acids than between alkylammonium cations and amino acids.Vibrational spectroscopy of ILs shows that a significant-OH vibration peak occurs at 4124 cmt in serine-containing ILs,and a prominent C=O vending peak occurs at 1626 cm^-1 in amino acids.展开更多
It is shown that the approximation of a strong Coulomb interaction between electrons results in a new model of the atom with a spatial quantization of electrons accompanied by their quantization in energy. This model ...It is shown that the approximation of a strong Coulomb interaction between electrons results in a new model of the atom with a spatial quantization of electrons accompanied by their quantization in energy. This model implies that electrons rotate in circular orbits centered outside the atomic nucleus and only orbit axes pass through it. The Coulomb interaction between electrons leads to a spherically symmetric distribution of their orbits on the surfaces of equipotential spheres of a spherically symmetric electrostatic field of the nucleus. The distribution is similar to “inscribing” electron orbits into faces of regular nucleus-centered polyhedra so each polyhedron corresponds to a certain electron state (s, p, d, f), and a certain set of polyhedra corresponds to a certain period of the Mendeleev Table. It is shown that a spherically symmetric distribution of electron orbits gives rise to the formation of electron pairs in which electron orbits with a common axis are located symmetrically with respect to the nucleus and the orbital magnetic moments of the electrons are oppositely directed. The physical meaning of the electron spin concept becomes clear. The spin turns out to be related to the orbital magnetic moment of an electron and reflects the fact that two electrons of a pair rotate in opposite directions relative to their common axis. So the spin is one of characteristics of the electron state in the atom associated with electron rotation in the orbit centered outside the nucleus. The atomic model gives an insight into the periodicity of changes in the atomic properties with increasing nuclear charge and the reasons for an electron double energy quantization associated with different states and periods. The model shows that the atomic structure and properties can be explained by using concepts of classical mechanics and classical electrodynamics which regard the electron as a particle.展开更多
With the rapid expansion of social media,analyzing emotions and their causes in texts has gained significant importance.Emotion-cause pair extraction enables the identification of causal relationships between emotions...With the rapid expansion of social media,analyzing emotions and their causes in texts has gained significant importance.Emotion-cause pair extraction enables the identification of causal relationships between emotions and their triggers within a text,facilitating a deeper understanding of expressed sentiments and their underlying reasons.This comprehension is crucial for making informed strategic decisions in various business and societal contexts.However,recent research approaches employing multi-task learning frameworks for modeling often face challenges such as the inability to simultaneouslymodel extracted features and their interactions,or inconsistencies in label prediction between emotion-cause pair extraction and independent assistant tasks like emotion and cause extraction.To address these issues,this study proposes an emotion-cause pair extraction methodology that incorporates joint feature encoding and task alignment mechanisms.The model consists of two primary components:First,joint feature encoding simultaneously generates features for emotion-cause pairs and clauses,enhancing feature interactions between emotion clauses,cause clauses,and emotion-cause pairs.Second,the task alignment technique is applied to reduce the labeling distance between emotion-cause pair extraction and the two assistant tasks,capturing deep semantic information interactions among tasks.The proposed method is evaluated on a Chinese benchmark corpus using 10-fold cross-validation,assessing key performance metrics such as precision,recall,and F1 score.Experimental results demonstrate that the model achieves an F1 score of 76.05%,surpassing the state-of-the-art by 1.03%.The proposed model exhibits significant improvements in emotion-cause pair extraction(ECPE)and cause extraction(CE)compared to existing methods,validating its effectiveness.This research introduces a novel approach based on joint feature encoding and task alignment mechanisms,contributing to advancements in emotion-cause pair extraction.However,the study’s limitation lies in the data sources,potentially restricting the generalizability of the findings.展开更多
The alkaline hydrogen evolution reaction(HER)is a crucial process for sustainable hydrogen production,yet it requires efficient and stable electrocatalysts to overcome the high activation energy barrier.The article di...The alkaline hydrogen evolution reaction(HER)is a crucial process for sustainable hydrogen production,yet it requires efficient and stable electrocatalysts to overcome the high activation energy barrier.The article discusses a novel strategy for enhancing the performance of Ni-Fe layered double hydroxide(Ni-Fe LDH)in the alkaline HER by modifying it with a frustrated Lewis acid-base pair(FLP)constructed through vacancy engineering.The study found that the modified Ni-Fe LDH exhibited improved alkaline HER performance.Density functional theory(DFT)calculations demonstrate that the introduction of FLP can activate water and protons more efficiently than monometallic sites,thus reducing the alkaline HER energy barrier and overpotential.In HER under alkaline conditions,the Volmer step involves an additional hydrolysis dissociation compared to acidic conditions,which is one of the factors contributing to the slow reaction kinetics.This paper demonstrates that FLPs can alter the rate-determining step in alkaline HER from the Volmer step to a step with a lower energy barrier,more suitable for hydrogen desorption.The work provides new insights into the role of FLPs in regulating the mechanism and kinetics of HER and opens a new direction for the design and optimization of LDH-based and other electrocatalysts.展开更多
Development of high-performance ion-selective membranes is crucial for achieving efficient ion separation in water treatment and energy storage applications.In this study,we demonstrate the strategic incorporation of ...Development of high-performance ion-selective membranes is crucial for achieving efficient ion separation in water treatment and energy storage applications.In this study,we demonstrate the strategic incorporation of acid-base pairs within a polybenzimidazole matrix through controlled sulfonation.By leveraging these intermolecular interactions,we enhance the Li^(+)/Mg^(2+)selectivity of the membrane.At an optimal sulfonation degree,the SP45 membrane forms a cross-linked structure,featuring contracted ionic clusters and discrete hydrophilic domains with limited interconnectivity.This unique microstructure imposes significantly higher energy barriers for the transmembrane transport of Mg^(2+),thereby endowing the SP45 membrane with exceptional perm-selectivity of 48.1 at a current density of 2 mA cm^(-2).Cycling stability tests reveal that the Li^(+)/Mg^(2+)selectivity degradation remains below 10%across multiple cycles in diverse mixed-salt systems.In practical brine ion distillation tests,we achieved a separation factor of exceeding 60,000 between Li^(+)and Mg^(2+)utilizing a 4-stage ion-distillation device equipped with the prepared SP45 membranes.This work provides fundamental insights into ion transport regulation through molecular-level acid-base pairs engineering,opening new avenues for advanced ion-selective separation membranes.展开更多
Loop pairing is one of the major concerns when designing decentralized control systems for multivariable processes.Most existing pairing tools,such as the relative gain array(RGA) method,have shortcomings both in meas...Loop pairing is one of the major concerns when designing decentralized control systems for multivariable processes.Most existing pairing tools,such as the relative gain array(RGA) method,have shortcomings both in measuring interaction and in integrity issues.To evaluate the overall interaction among loops,we propose a statistics-based criterion via enumerating all possible combinations of loop statuses.Furthermore,we quantify the traditional concept of integrity to represent the extent of integrity of a decentralized control system.Thus,we propose that a pairing decision should be made by taking both factors into consideration.Two examples are provided to illustrate the effectiveness of the proposed criterion.展开更多
We calculate the two-proton decay width of the6 Be nucleus employing the schematic densitydependent contact potential for the proton-proton pairing interaction. The decay width is calculated with a time-dependent meth...We calculate the two-proton decay width of the6 Be nucleus employing the schematic densitydependent contact potential for the proton-proton pairing interaction. The decay width is calculated with a time-dependent method, in which the two-proton emission is described as a time-evolution of a threebody meta-stable state. Model-dependence of the two-proton decay width has been shown by comparing the results obtained with the two different pairing models, schematic density-dependent contact and Minnesota interactions, which have zero and finite ranges, respectively.展开更多
The paper discusses the researches that formed the basis of the study of the transition of “ordering-phase separation” and the reasons for such transition occurrence. Experimental results have presented what diffusi...The paper discusses the researches that formed the basis of the study of the transition of “ordering-phase separation” and the reasons for such transition occurrence. Experimental results have presented what diffusion pairs are and how they occur in binary and multicomponent alloys. The paper illustrates that the chemical bonds between atoms are realized on the principle of pair interaction in both solid and liquid states of the alloy. The process of separating a multi-component ABC alloy into diffusion pairs A/B, A/C, and B/C occurs in a liquid solution, where the diffusion mobility of atoms is very high, and the resistance of the environment is relatively low. The driving force of such a process is the chemical attraction between like and unlike atoms, that is, the tendency to phase separation and the tendency to ordering. Quenching the liquid alloy into the water fixes a microstructure consisting of microscopic areas corresponding in composition to one or another diffusion pairs. The paper shows what exactly should be done so that such a branch of science as Materials Science could get rid of the empirical approach when creating new alloys.展开更多
A modified selectively infective phage (SIP) is developed to facilitate the selection of interacting antibody antigen pairs from a large single chain antibody (scFv) library in vivo. The system is constructed with a m...A modified selectively infective phage (SIP) is developed to facilitate the selection of interacting antibody antigen pairs from a large single chain antibody (scFv) library in vivo. The system is constructed with a modified helper phage M13KO7 and phagemid pCANTAB 5 E. The antigen fused to the C terminal of N1 N2 domain and the scFv to the N terminal of CT domain of the gIIIp of filamentous phage are encoded on the phage and phagemid vectors respectively. The phages produced by co transformants restore infectivity via interaction between antigen and antibody fusions in the cell periplasm. In a model system, the scFv fragment of the anti hemagglutinin 17/9 antibody and its corresponding antigen are detected in the presence of a 10 5 fold excess of a non interacting control pairs, which demonstrates this system to be very sensitive and facile to screen a large single chain antibody library.展开更多
The electron gas examined in a very thin potential tube exhibits some special kind of the excited pairs making them similar to the Cooper pairs. The coupling energy of the pair can be calculated as an amount of energy...The electron gas examined in a very thin potential tube exhibits some special kind of the excited pairs making them similar to the Cooper pairs. The coupling energy of the pair can be calculated as an amount of energy required to transform the excitation energy of a coupled pair into the one-electron excitation energy. For an extremely thin potential tube the coupling energy of the pair tends to infinity. The gas energy is unstable with respect to the pair excitation which provides a kind of gap near the Fermi level. A decisive part of the gap energy is due to the electron-electron interaction. The gap is attained on condition the length of a thin potential box exceeds some critical value. In the next step, a coherence length in the gas is obtained. This length, combined with a critical magnetic field representing a transition from a superconducting to a normal state, allows us to calculate the penetration depth of the magnetic field for the singlet and triplet excitations. The penetration depth together with the critical magnetic field and energy gap can provide us with a critical current, as well as critical temperature for the superconducting state.展开更多
基金supported by the National Natural Science Foundation of China(No.22208376,No.UA22A20429)the Fundamental Research Funds for the Central Universities(buctrc202118,No.25CX07002A)+1 种基金the Qingdao New Energy Shandong Laboratory Open Project(QNESL OP 202303)the Shandong Provincial Natural Science Foundation(ZR2024QB175 and ZR2023LFG005)。
文摘Water management within the membrane electrode assemblies(MEAs)of electrochemical hydrogen compressors(EHCs)plays a crucial role in optimizing overall performance,particularly under low relative humidity(RH),where the anode side tends to dry out.Hollow mesoporous silica nanoparticles functionalized with amino groups(HMSNs-NH_(2))were integrated into the anode catalyst layers of EHCs to establish humidity-independent proton pathways through acid-base interactions with Nafion ionomers.These acid-base pairs between grafted–NH_(2)and sulfonic acid groups create continuous“proton highways”,enabling efficient conduction via the Grotthuss mechanism even at 50%RH.With only 2.5 wt%HMSNs-NH_(2)in the anode catalyst layer,hydrogen was compressed to 0.9 MPa in 60±3 s at 50%RH,representing a 55%reduction in compression time compared to MEAs with conventional Pt/C catalyst layers under the same conditions.This work overcomes the critical water-management bottleneck in EHCs,advancing the deployment of hydrogen energy technologies in arid environments.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602501)the National Natural Science Foundation of China(Grant No.12011530060)+1 种基金supported solely by the Russian Science Foundation(Grant No.22-12-00043)supported by the Chinese Academy of Sciences(CAS)Presidents International Fellowship Initiative(PIFI)(Grant Nos.2018VMB0016 and 2022VMC0002),respectively。
文摘We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60372061)the Scientific Forefront and Interdisciplinary Innovation Project of Jilin University, China (Grant No. 200903296)
文摘We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the intercavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons.
基金supported by the National Natural Science Foundation of China(No.22179007)。
文摘Lithium metal batteries,with their light mass anode and high theoretical specific capacity of 3860 m Ah/g,have great potential for development in achieving high energy density.However,the generation of lithium dendrites and the loss of dead lithium pose a serious threat to the safety and long-cycle stability of batteries.Herein,we utilize the Lewis acid-base interaction principle for lithium-ion migration regulation.Through loading solid-acids onto molecular sieves to immobilize Lewis base(PF_(6^(-))),we achieve accelerated dissociation of lithium salts and successfully increase the lithium ion transference number to 0.44.Lewis acid-base interaction helps lithium metal batteries achieve more uniform lithium deposition,with an average CE improved to 92.8%.The symmetrical cells can be plated/stripped stably for more than 800 h of cycling.Full cell with high surface-loaded LFP cathode(14 mg/cm^(2))exhibits impressively high capacity retention of 90.7%after 120 cycles at 0.5 C.
文摘This paper is committed to exploring the importance of learner learner interaction for language learning. It starts with a discussion of the roles that learner learner interaction plays in language learning from two points of view pedagogic and psycholinguistic, which is followed by a brief guideline for organizing group work in class.
基金Supported by the National Natural Science Foundation of China （21076139, 21106106）, Tianjin Natural Science Foundation of China （12JcQNJC3700）, and Foundation of Tianjin Educational Committee of China （20100508）.
文摘A numerical simulation was performed to investigate the interaction of two bubbles rising side by side in shear-thinning fluid using volume of fluid （VOF） method coupled with continuous surface force （CSF） method. By considering rheological characteristics of fluid, this approach was able to accurately capture the deformation of bubble interface, and validated by comparing with the experimental results. The rising of bubble pairs with different configurations, including horizontal alignment and oblique alignment, was simulated by the method. The influences of the bubble initial distance and the bubble alignment were studied by analyzing the bubble deformation, rising paths and flow fields surrounding bubbles. The results indicate that within certam mltlal bubble spacing of S = 3.3 （S＊ = SI/D, SI initial distance between bubbles, and D bubble diameter）, the dynamic interaction between two bub- bles aligned horizontally shows repulsive effect that decreases with the increase of initial bubble spacing, but weakens to certain degree by the shear-thinning properties of fluid. However, the interaction between two bubbles aligned obliquely presents a repulsive effect for the small angle involved but an attractive impact for the large one, which is vet strengthened by the rheological characteristics of fluid.
基金This work was supported by the National Natural Science Foundation of China(Nos.12275115 and 12175097)the Educational Department of Liaoning Province(No.LJKMZ20221410).
文摘In this article,a comprehensive study of the fission process of Th,U,Pu,and Cm isotopes using a Yukawa-folded meanfield plus standard pairing model is presented.The study focused on analyzing the effects of the pairing interaction on the fragment mass distribution and its dependence on nuclear elongation.The significant role of pairing interactions in the fragment mass distributions of^(230)Th,^(234)U,^(240)Pu,and^(246)Cm was demonstrated.Numerical analysis revealed that increasing the pairing interaction strength decreased the asymmetric fragment mass distribution and increased the symmetric distribution.Furthermore,the odd-even mass differences at symmetric and asymmetric fission points were examined,highlighting their sensitivity to changes in the pairing interaction strength.Systematic analysis of the Th,U,Pu,and Cm isotope fragment mass distributions demonstrated the effectiveness of the model in reproducing the experimental data.In addition,the effects of the zero-point energy and half-width parameter on the fragment mass distribution for^(240)Pu were explored.Thus,this study provides valuable insights into the fission process by emphasizing the importance of pairing interactions and their relationship with nuclear elongation.
基金Supported by the National Natural Science Foundation of China under Grant No 11105001the Anhui Provincial Natural Science Foundation under Grant Nos 1408085QA22 and 1608085MA09
文摘The single photon scattering properties in a pair of waveguides coupled by a whispering-gallery resonator in- teracting with a semiconductor quantum dot are investigated theoretically. The two waveguides support four possible ports for an incident single photon. The quantum dot is considered a V-type system. The incident direction-dependent single photon scattering properties are studied and equal-output probability from the four ports for a single photon incident is discussed. The influences of backscattering between the two modes of the whispering-gallery resonator for incident direction-dependent single photon scattering properties are also pre- sented.
基金supported by the National Natural Science Foundation of China(No.21171040 and 21302019)the disguished organic project(2013JCJS01)
文摘Two novel acid-base adducts,[H2L1^2＋]（Hpbda）2（1,L1 = 1,4-di（lH-imidazol-4-yl）benzene,H2pbda = 1,4-benzenedicarboxylic acid） and[H2L2^2＋]（NO3）2（2,L2 = l,4-di（l-carboxymethyl-imidazol-4-yl）benzene）,have been prepared and characterized by single-crystal X-ray diffraction,IR spectroscopy and elemental analysis.Compound 1 crystallizes in monoclinic,space group P21/n with a = 5.3525（11）,b = 9.1471（19）,c = 19.314（4） ？,β = 92.342（3）°,V= 944.8（3） A°3,Z = 2,C16H16N6O（10）,Mr = 452.35,Dc = 1.590 g/cm^3,μ = 0.135 mm^-1,S = 1.058,F（000） = 468,the final R = 0.0661 and wR = 0.1887 for 2298 observed reflections（I〉 2σ（I））.Compound 2 crystallizes in monoclinic,space group P21/c with a = 9.6923（10）,b = 17.2950（17）,c = 7.1880（7） ？,β =94.801（2）°,V= 1200.7（2）A°3,Z = 2,C（28）H（22）N4O8,Mr = 542.50,Dc = 1.501 g/cm^3,μ = 0.112 mm^-1,S= 1.060,F（000） = 564,the final R = 0.0394 and wR = 0.1017 for 2768 observed reflections（I 〉2σ（I））.In the title compounds,both of L1 and L2 ligands act as weak base to accept protons to exhibit diprotonated H2L1^2＋ and H2L2^2＋ form,which can effectively employ as hydrogen bonding donors to combine anion moieties to form binary adducts respectively.In the crystal packing diagram of two polymers,there exist extensive noncovalent interactions including charge-transfer interactions,C（N）-H…π and N-H…O,C-H…O,O-H…O hydrogen bonding interactions between co-crystal moieties which consolidate the structures of supramolecular polymers,thus generating three-dimensional（3D） frameworks.
文摘Solid-aqueous interfaces and phenomena occurring at those interfaces are ubiquitously found in a plethora of chemical systems.When it comes to heterogeneous catalysis,however,our understanding of chemical transformations at solid-aqueous interfaces is relatively limited and primitive.This review phenomenologically describes a selection of water-engendered effects on the catalytic behavior for several prototypical acid-base-catalyzed reactions over solid catalysts,and critically assesses the general and special roles of water molecules,structural moieties derived from water,and ionic species that are dissolved in it,with an aim to extract novel concepts and principles that underpin heterogeneous acid-base catalysis in the aqueous phase.For alcohol dehydration catalyzed by solid Bronsted acids,rate inhibition by water is most typically related to the decrease in the acid strength and/or the preferential solvation of adsorbed species over the transition state as water molecules progressively solvate the acid site and form extended networks wherein protons are mobilized.Water also inhibits dehydration kinetics over most Lewis acid-base catalysts by competitive adsorption,but a few scattered reports reveal substantial rate enhancements due to the conversion of Lewis acid sites to Brønsted acid sites with higher catalytic activities upon the introduction of water.For aldol condensation on catalysts exposing Lewis acid-base pairs,the addition of water is generally observed to enhance the rate when C–C coupling is rate-limiting,but may result in rate inhibition by site-blocking when the initial unimolecular deprotonation is rate-limiting.Water can also promote aldol condensation on Brønsted acidic catalysts by facilitating inter-site communication between acid sites through hydrogen-bonding interactions.For metallozeolite-catalyzed sugar isomerization in aqueous media,the nucleation and networking of intrapore waters regulated by hydrophilic entities causes characteristic enthalpy-entropy tradeoffs as these water moieties interact with kinetically relevant hydride transfer transition states.The discussed examples collectively highlight the utmost importance of hydrogen-bonding interactions and ionization of covalently bonded surface moieties as the main factors underlying the uniqueness of water-mediated interfacial acid-base chemistries and the associated solvation effects in the aqueous phase or in the presence of water.A perspective is also provided for future research in this vibrant field.
文摘Ab initio calculations were performed using the Gaussian 03 software package to obtain the optimized structure,interaction energy and infrared spectrum of ionic liquids(ILs)containing a tetraalkylphosphonium cation and an amino acid anion.In order to investigate the effect of the presence of nitrogen in the cation,the tetraalkylphosphonium cation was replaced by a tetraalkylammonium cation,while amino acids were retained as anions in the ionic liquid.The amino acids studied here included glycine,alanine,serine,lysine,and glutamine.Optimized structures of several ILs in the gas phase were determined at the levels of Hartree-Fock(HF/6-3+G(d))and 1density functional theory(B3LYP/6-31++G(d,p)).At high-level estimations,MP2/6-31+G(d)and MP2/6-31++G(d,p),the interaction energies between the cations and anions of the ILs were determined.In order to investigate the effect of alkyl-chain length on interaction energy,the alkyl groups were varied from methyl to ethyl and propyl in the tetraalkylphosphonium functional groups.This procedure revealed that there is a considerably stronger interaction between the alkylphosphonium cations and amino acids than between alkylammonium cations and amino acids.Vibrational spectroscopy of ILs shows that a significant-OH vibration peak occurs at 4124 cmt in serine-containing ILs,and a prominent C=O vending peak occurs at 1626 cm^-1 in amino acids.
文摘It is shown that the approximation of a strong Coulomb interaction between electrons results in a new model of the atom with a spatial quantization of electrons accompanied by their quantization in energy. This model implies that electrons rotate in circular orbits centered outside the atomic nucleus and only orbit axes pass through it. The Coulomb interaction between electrons leads to a spherically symmetric distribution of their orbits on the surfaces of equipotential spheres of a spherically symmetric electrostatic field of the nucleus. The distribution is similar to “inscribing” electron orbits into faces of regular nucleus-centered polyhedra so each polyhedron corresponds to a certain electron state (s, p, d, f), and a certain set of polyhedra corresponds to a certain period of the Mendeleev Table. It is shown that a spherically symmetric distribution of electron orbits gives rise to the formation of electron pairs in which electron orbits with a common axis are located symmetrically with respect to the nucleus and the orbital magnetic moments of the electrons are oppositely directed. The physical meaning of the electron spin concept becomes clear. The spin turns out to be related to the orbital magnetic moment of an electron and reflects the fact that two electrons of a pair rotate in opposite directions relative to their common axis. So the spin is one of characteristics of the electron state in the atom associated with electron rotation in the orbit centered outside the nucleus. The atomic model gives an insight into the periodicity of changes in the atomic properties with increasing nuclear charge and the reasons for an electron double energy quantization associated with different states and periods. The model shows that the atomic structure and properties can be explained by using concepts of classical mechanics and classical electrodynamics which regard the electron as a particle.
文摘With the rapid expansion of social media,analyzing emotions and their causes in texts has gained significant importance.Emotion-cause pair extraction enables the identification of causal relationships between emotions and their triggers within a text,facilitating a deeper understanding of expressed sentiments and their underlying reasons.This comprehension is crucial for making informed strategic decisions in various business and societal contexts.However,recent research approaches employing multi-task learning frameworks for modeling often face challenges such as the inability to simultaneouslymodel extracted features and their interactions,or inconsistencies in label prediction between emotion-cause pair extraction and independent assistant tasks like emotion and cause extraction.To address these issues,this study proposes an emotion-cause pair extraction methodology that incorporates joint feature encoding and task alignment mechanisms.The model consists of two primary components:First,joint feature encoding simultaneously generates features for emotion-cause pairs and clauses,enhancing feature interactions between emotion clauses,cause clauses,and emotion-cause pairs.Second,the task alignment technique is applied to reduce the labeling distance between emotion-cause pair extraction and the two assistant tasks,capturing deep semantic information interactions among tasks.The proposed method is evaluated on a Chinese benchmark corpus using 10-fold cross-validation,assessing key performance metrics such as precision,recall,and F1 score.Experimental results demonstrate that the model achieves an F1 score of 76.05%,surpassing the state-of-the-art by 1.03%.The proposed model exhibits significant improvements in emotion-cause pair extraction(ECPE)and cause extraction(CE)compared to existing methods,validating its effectiveness.This research introduces a novel approach based on joint feature encoding and task alignment mechanisms,contributing to advancements in emotion-cause pair extraction.However,the study’s limitation lies in the data sources,potentially restricting the generalizability of the findings.
基金financially supported by National Natural Science Foundation of China(Nos.52301011,52231008,52142304,52177220,U23A200767,52302236,and 22369005)Hainan Provincial Natural Science Foundation of China(Nos.524QN226 and 524QN222)+2 种基金the Key Research and Development Program of Hainan Province(No.ZDYF2022GXJS006)Starting Research Fund from the Hainan University(No.KYQD(ZR)23026)International Science&Technology Cooperation Program of Hainan Province(No.GHYF2023007).
文摘The alkaline hydrogen evolution reaction(HER)is a crucial process for sustainable hydrogen production,yet it requires efficient and stable electrocatalysts to overcome the high activation energy barrier.The article discusses a novel strategy for enhancing the performance of Ni-Fe layered double hydroxide(Ni-Fe LDH)in the alkaline HER by modifying it with a frustrated Lewis acid-base pair(FLP)constructed through vacancy engineering.The study found that the modified Ni-Fe LDH exhibited improved alkaline HER performance.Density functional theory(DFT)calculations demonstrate that the introduction of FLP can activate water and protons more efficiently than monometallic sites,thus reducing the alkaline HER energy barrier and overpotential.In HER under alkaline conditions,the Volmer step involves an additional hydrolysis dissociation compared to acidic conditions,which is one of the factors contributing to the slow reaction kinetics.This paper demonstrates that FLPs can alter the rate-determining step in alkaline HER from the Volmer step to a step with a lower energy barrier,more suitable for hydrogen desorption.The work provides new insights into the role of FLPs in regulating the mechanism and kinetics of HER and opens a new direction for the design and optimization of LDH-based and other electrocatalysts.
基金supported by the National Key Research and Development Program of China(2022YFB3805100)National Natural Science Foundation of China(22222812 and 22178330).
文摘Development of high-performance ion-selective membranes is crucial for achieving efficient ion separation in water treatment and energy storage applications.In this study,we demonstrate the strategic incorporation of acid-base pairs within a polybenzimidazole matrix through controlled sulfonation.By leveraging these intermolecular interactions,we enhance the Li^(+)/Mg^(2+)selectivity of the membrane.At an optimal sulfonation degree,the SP45 membrane forms a cross-linked structure,featuring contracted ionic clusters and discrete hydrophilic domains with limited interconnectivity.This unique microstructure imposes significantly higher energy barriers for the transmembrane transport of Mg^(2+),thereby endowing the SP45 membrane with exceptional perm-selectivity of 48.1 at a current density of 2 mA cm^(-2).Cycling stability tests reveal that the Li^(+)/Mg^(2+)selectivity degradation remains below 10%across multiple cycles in diverse mixed-salt systems.In practical brine ion distillation tests,we achieved a separation factor of exceeding 60,000 between Li^(+)and Mg^(2+)utilizing a 4-stage ion-distillation device equipped with the prepared SP45 membranes.This work provides fundamental insights into ion transport regulation through molecular-level acid-base pairs engineering,opening new avenues for advanced ion-selective separation membranes.
基金supported by the National High-Tech Research and Development Program (863) of China (No.2009AA04Z154)the National Natural Science Foundation of China (No.60736021)
文摘Loop pairing is one of the major concerns when designing decentralized control systems for multivariable processes.Most existing pairing tools,such as the relative gain array(RGA) method,have shortcomings both in measuring interaction and in integrity issues.To evaluate the overall interaction among loops,we propose a statistics-based criterion via enumerating all possible combinations of loop statuses.Furthermore,we quantify the traditional concept of integrity to represent the extent of integrity of a decentralized control system.Thus,we propose that a pairing decision should be made by taking both factors into consideration.Two examples are provided to illustrate the effectiveness of the proposed criterion.
文摘We calculate the two-proton decay width of the6 Be nucleus employing the schematic densitydependent contact potential for the proton-proton pairing interaction. The decay width is calculated with a time-dependent method, in which the two-proton emission is described as a time-evolution of a threebody meta-stable state. Model-dependence of the two-proton decay width has been shown by comparing the results obtained with the two different pairing models, schematic density-dependent contact and Minnesota interactions, which have zero and finite ranges, respectively.
文摘The paper discusses the researches that formed the basis of the study of the transition of “ordering-phase separation” and the reasons for such transition occurrence. Experimental results have presented what diffusion pairs are and how they occur in binary and multicomponent alloys. The paper illustrates that the chemical bonds between atoms are realized on the principle of pair interaction in both solid and liquid states of the alloy. The process of separating a multi-component ABC alloy into diffusion pairs A/B, A/C, and B/C occurs in a liquid solution, where the diffusion mobility of atoms is very high, and the resistance of the environment is relatively low. The driving force of such a process is the chemical attraction between like and unlike atoms, that is, the tendency to phase separation and the tendency to ordering. Quenching the liquid alloy into the water fixes a microstructure consisting of microscopic areas corresponding in composition to one or another diffusion pairs. The paper shows what exactly should be done so that such a branch of science as Materials Science could get rid of the empirical approach when creating new alloys.
文摘A modified selectively infective phage (SIP) is developed to facilitate the selection of interacting antibody antigen pairs from a large single chain antibody (scFv) library in vivo. The system is constructed with a modified helper phage M13KO7 and phagemid pCANTAB 5 E. The antigen fused to the C terminal of N1 N2 domain and the scFv to the N terminal of CT domain of the gIIIp of filamentous phage are encoded on the phage and phagemid vectors respectively. The phages produced by co transformants restore infectivity via interaction between antigen and antibody fusions in the cell periplasm. In a model system, the scFv fragment of the anti hemagglutinin 17/9 antibody and its corresponding antigen are detected in the presence of a 10 5 fold excess of a non interacting control pairs, which demonstrates this system to be very sensitive and facile to screen a large single chain antibody library.
文摘The electron gas examined in a very thin potential tube exhibits some special kind of the excited pairs making them similar to the Cooper pairs. The coupling energy of the pair can be calculated as an amount of energy required to transform the excitation energy of a coupled pair into the one-electron excitation energy. For an extremely thin potential tube the coupling energy of the pair tends to infinity. The gas energy is unstable with respect to the pair excitation which provides a kind of gap near the Fermi level. A decisive part of the gap energy is due to the electron-electron interaction. The gap is attained on condition the length of a thin potential box exceeds some critical value. In the next step, a coherence length in the gas is obtained. This length, combined with a critical magnetic field representing a transition from a superconducting to a normal state, allows us to calculate the penetration depth of the magnetic field for the singlet and triplet excitations. The penetration depth together with the critical magnetic field and energy gap can provide us with a critical current, as well as critical temperature for the superconducting state.
