Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal s...Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal sources and N,N-dimethylformamide was employed as a solvent as well as a reductant to produce Cu(Ⅰ) complexes.(ⅱ) An iodide-containing compound was utilized as a ligand and iodide source to prepare complexes.An in situ metalligand reaction occurred and an iodide-bridged copper complex was generated.(ⅲ) A series of aldehydes were added to the reaction systems to induce in situ metal-ligand reactions between the aldehydes and the imidazo[1,5-a]pyridine derivatives,producing polydentate ligand scaffolds.Eight complexes were prepared and characterized.The catalytic activities of these complexes toward the ketalization of ketones by ethylene glycol were investigated.With the exception of complex4,the remaining seven complexes all showed high catalytic activity.The lower activity of 4 may be due to the larger radius of bridging iodide ions and the shorter Cu(Ⅰ)…Cu(Ⅰ) distance.CCDC:2357696,1·2CH_(2)Cl_(2);2357697,2;2018292,3;2092192,4;2092190,5;2155557,6;2406155,7;2406156,8·EtOH.展开更多
Alloying transition metals with Pt is an effective strategy for optimizing Pt-based catalysts toward the oxygen reduction reaction(ORR).Atomic ordered intermetallic compounds(IMC)provide unique electronic and geometri...Alloying transition metals with Pt is an effective strategy for optimizing Pt-based catalysts toward the oxygen reduction reaction(ORR).Atomic ordered intermetallic compounds(IMC)provide unique electronic and geometrical effects as well as stronger intermetallic interactions due to the ordered arrangement of metal atoms,thus exhibiting superior electrocata-lytic activity and durability.However,quantitatively analyzing the ordering degree of IMC and exploring the correlation between the ordering degree and ORR activity remains extremely challenging.Herein,a series of ternary Pt_(2)NiCo interme-tallic catalysts(o-Pt_(2)NiCo)with different ordering degree were synthesized by annealing temperature modulation.Among them,the o-Pt_(2)NiCo which annealed at 800℃for two hours exhibits the highest ordering degree and the optimal ORR ac-tivity,which the mass activity of o-Pt_(2)NiCo is 1.8 times and 2.8 times higher than that of disordered Pt_(2)NiCo alloy and Pt/C.Furthermore,the o-Pt_(2)NiCo still maintains 70.8%mass activity after 30,000 potential cycles.Additionally,the ORR activity test results for Pt_(2)NiCo IMC with different ordering degree also provide a positive correlation between the ordering degree and ORR activity.This work provides a prospective design direction for ternary Pt-based electrocatalysts.展开更多
Sulfur-doped iron-cobalt tannate nanorods(S-FeCoTA)derived from metal-organic frameworks(MOFs)as electrocatalysts were synthesized via a one-step hydrothermal method.The optimized S-FeCoTA was interlaced by loose nano...Sulfur-doped iron-cobalt tannate nanorods(S-FeCoTA)derived from metal-organic frameworks(MOFs)as electrocatalysts were synthesized via a one-step hydrothermal method.The optimized S-FeCoTA was interlaced by loose nanorods,which had many voids.The S-FeCoTA catalysts exhibited excellent electrochemical oxygen evolution reaction(OER)performance with a low overpotential of 273 mV at 10 mA·cm^(-2)and a small Tafel slope of 36 mV·dec^(-1)in 1 mol·L^(-1)KOH.The potential remained at 1.48 V(vs RHE)at 10 mA·cm^(-2)under continuous testing for 15 h,implying that S-FeCoTA had good stability.The Faraday efficiency of S-FeCoTA was 94%.The outstanding OER activity of S-FeCoTA is attributed to the synergistic effects among S,Fe,and Co,thus promoting electron transfer,reducing the reaction kinetic barrier,and enhancing the OER performance.展开更多
The poor electronic conductivity of metal-organic framework(MOF)materials hinders their direct application in the field of electrocatalysis in fuel cells.Herein,we proposed a strategy of embedding carbon nanotubes(CNT...The poor electronic conductivity of metal-organic framework(MOF)materials hinders their direct application in the field of electrocatalysis in fuel cells.Herein,we proposed a strategy of embedding carbon nanotubes(CNTs)during the growth process of MOF crystals,synthesizing a metalloporphyrin-based MOF catalyst TCPPCo-MOF-CNT with a unique CNT-intercalated MOF structure.Physical characterization revealed that the CNTs enhance the overall conductivity while retaining the original characteristics of the MOF and metalloporphyrin.Simultaneously,the insertion of CNTs generated adequate mesopores and created a hierarchical porous structure that enhances mass transfer efficiency.X-ray photoelectron spectroscopic analysis confirmed that the C atom in CNT changed the electron cloud density on the catalytic active center Co,optimizing the electronic structure.Consequently,the E_(1/2) of the TCPPCo-MOF-CNT catalyst under neutral conditions reached 0.77 V(vs.RHE),outperforming the catalyst without CNTs.When the TCPPCo-MOF-CNT was employed as the cathode catalyst in assembling microbial fuel cells(MFCs)with Nafion-117 as the proton exchange membrane,the maxi-mum power density of MFCs reached approximately 500 mW·m^(-2).展开更多
We have examined the theoretical implications of combining two main and three auxiliary ligands to form several Ir(Ⅲ)complexes featuring a transition metal as their core atom to identify some appropriate organic ligh...We have examined the theoretical implications of combining two main and three auxiliary ligands to form several Ir(Ⅲ)complexes featuring a transition metal as their core atom to identify some appropriate organic lightemitting diode(OLED)materials.By utilizing electronic structure,frontier molecular orbitals,minimum single-line absorption,triplet excited states,and emission spectral data derived from the density functional theory,the usefulness of these Ir(Ⅲ)complexes,including(piq)_(2)Ir(acac),(piq)_(2)Ir(tmd),(piq)_(2)Ir(tpip),(fpiq)_(2)Ir(acac),(fpiq)_(2)Ir(tmd),and(fpiq)_(2)Ir(tpip),in OLEDs was examined,where piq=1-phenylisoquinoline,fpiq=1-(4-fluorophenyl)isoquinoline,acac=(3Z)-4-hydroxypent-3-en-2-one,tmd=(4Z)-5-hydroxy-2,2,6,6-tetramethylhept-4-en-3-one,and tpip=tetraphenylimido-diphosphonate.These complexes all have low-efficiency roll-off properties,especially(fpiq)_(2)Ir(tpip).Some researchers have successfully synthesized complexes extremely similar to(piq)_(2)Ir(acac)through the Suzuki-Miyaura coupling reaction.展开更多
The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these c...The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.展开更多
The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled elec...The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled electron transfer(PCET)hinders the overall OER efficiency.Herein,we report an ionic liquid(IL)modified CoSn(OH)_(6)nanocubes(denoted as CoS-n(OH)_(6)-IL),which could be prepared through a facile strategy.The modified IL would not change the structural character-istics of CoSn(OH)_(6),but could effectively regulate the local proton activity near the active sites.The CoSn(OH)_(6)-IL exhibited higher intrinsic OER performances than the pristine CoSn(OH)_(6)in neutral media.For example,the current density of CoS-n(OH)_(6)-IL at 1.8 V versus reversible hydrogen electrode(RHE)was about 4 times higher than that of CoSn(OH)_(6).According to the pH-dependent kinetic investigations,operando electrochemical impedance spectroscopic,chemical probe tests,and deuterium kinetic isotope effects,the interfacial layer of IL could be utilized as a proton transfer mediator to promote the proton transfer,which enhances the surface coverage of OER intermediates and reduces the activation barrier.Consequent-ly,the sluggish OER kinetics would be efficiently accelerated.This study provides a facile and effective strategy to facilitate the PCET processes and is beneficial to guide the rational design of OER electrocatalysts.展开更多
Single-atom catalysts(SACs)are promising for oxygen reduction reaction(ORR)on account of their excellent catalytic activity and maximum utilization of atoms.However,due to the complicated preparation processes and exp...Single-atom catalysts(SACs)are promising for oxygen reduction reaction(ORR)on account of their excellent catalytic activity and maximum utilization of atoms.However,due to the complicated preparation processes and expensive reagents used,the cost of SACs is usually too high to put into practical application.The development of cost-effective and sustainable SACs remains a great challenge.Herein,a low-cost method employing biomass is designed to prepare efficient single-atom Fe-N-C catalysts(SA-Fe-N-C).Benefiting from the confinement effect of porous carbon support and the coordination effect of glucose,SA-Fe-N-C is derived from cheap flour by the two-step pyrolysis.Atomically dispersed Fe atoms exist in the form of Fe-N_(x),which acts as active sites for ORR.The catalyst shows outstanding activity with a half-wave potential(E_(1/2))of 0.86 V,which is better than that of Pt/C(0.84 V).Additionally,the catalyst also exhibits superior stability.The ORR catalyzed by SA-Fe-N-C proceeds via an efficient 4e transfer pathway.The high performance of SA-Fe-N-C also benefits from its porous structure,extremely high specific surface area(1450.1 m^(2)/g),and abundant micropores,which are conducive to increasing the density of active sites and fully exposing them.This work provides a cost-effective strategy to synthesize SACs from cheap biomass,achieving a balance between performance and cost.展开更多
The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying t...The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying traditional maximum equivalent span beam(MESB)theory to determine deformation range,peak point,and angle influence poses a challenge.Considering the overall structure of the intersection roof,the maximum equivalent triangular plate(METP)theory is proposed,and its geometric parameter calculation formula and deflection calculation formula are obtained.The application of the two theories in 18 models with different intersection angles,roadway types,and surrounding rock lithology is verified by numerical analysis.The results show that:1)The METP structure of the intersection roof established by the simulation results of each model successfully determined the location of the roof’s high displacement zone;2)The area comparison method of the METP theory can be reasonably explained:①The roof subsidence of the intersection decreases with the increase of the intersection angle;②The roof subsidence at the intersection of different roadway types has a rectangular type>arch type>circular type;③The roof subsidence of the intersection with weak surrounding rock is significantly larger than that of the intersection with hard surrounding rock.According to the application results of the two theories,the four advantages of the METP theory are compared and clarified in the basic assumptions,mechanical models,main viewpoints,and mechanism analysis.The large deformation inducement of the intersection roof is then explored.The J 2 peak area of the roof drives the large deformation of the area,the peak point of which is consistent with the center of gravity position of the METP.Furthermore,the change in the range of this peak is consistent with the change law of the METP’s area.Hence,this theory clarifies the large deformation area of the intersection roof,which provides a clear guiding basis for its initial support design,mid-term monitoring,and late local reinforcement.展开更多
The new CL-20(hexanitrohexaazaisowurtzitane)type aluminized explosives in the overdrive detonation(ODD)conditions of the core problem is how to accurately represent the state of the overdrive detonation products.To th...The new CL-20(hexanitrohexaazaisowurtzitane)type aluminized explosives in the overdrive detonation(ODD)conditions of the core problem is how to accurately represent the state of the overdrive detonation products.To this end,this paper is based on the impedance matching method to test the ODD conditions of CL-20 type aluminium explosive particle velocity.Calculated the interfacial pressure of the shock wave in different media.Determined the characteristic parameters of the reaction zone of the detonation of CL-20 aluminized explosives.Calibrated the parameters of the JoneseWilkinseLee(JWL)+γ equation for the detonation products(DPs).Revealed the effect of different DPs equation of state(EOS)on the Hugoniot pressure of ODD.The results indicate that when the content of aluminum powder ranges from 0%to 30%,the duration of the ODD reaction zone and the width of the detonation reaction zone of the CL-20-based aluminized explosive are directly proportional to the content of aluminum powder.The width of the detonation reaction zone is increased by 1.97 times to 2.7 times compared to that of the reaction zone without the addition of aluminum powder.However,the energy release efficiency of the detonation reaction zone is inversely proportional to the content of aluminum powder.When the aluminum powder content was held constant,the incorporation of AP caused a 25%reduction in the energy release efficiency of the detonation reaction zone.Compared with existing ODD state equations,the JWL +γ equation is superior in calibrating overpressure Hugoniot data and the isentropic expansion in the C-J state.The deviation between calculated pressure results and experimental measurements is within 6%.展开更多
Rock fracture warning is one of the significant challenges in rock mechanics.Many true triaxial and synchronous acoustic emission(AE)tests were conducted on granite samples.The investigation focused on the characteris...Rock fracture warning is one of the significant challenges in rock mechanics.Many true triaxial and synchronous acoustic emission(AE)tests were conducted on granite samples.The investigation focused on the characteristics of AE signals preceding granite fracture,based on the critical slowing down(CSD)theory.The granite undergoes a transition from the stable phase to the fracture phase and exhibits a clear CSD phenomenon,characterized by a pronounced increase in variance and autocorrelation coefficient.The variance mutation points were found to be more identifiable and suitable as the primary criterion for predicting precursor information related to granite fracture,compared to the autocorrelation coefficient.It is noteworthy to emphasize that the CSD factor holds greater potential in elucidating the underlying mechanisms responsible for the critical transition of granite fracture,in comparison to the AE timing parameters.Furthermore,a novel multi-parameter collaborative prediction method for rock fracture was developed by comprehensively analyzing predictive information,including abnormal variation modes and the CSD factor of AE characteristic parameters.This method enhances the understanding and prediction of rock fracture-related geohazards.展开更多
Investigating natural-inspired applications is a perennially appealing subject for scientists. The current increase in the speed of natural-origin structure growth may be linked to their superior mechanical properties...Investigating natural-inspired applications is a perennially appealing subject for scientists. The current increase in the speed of natural-origin structure growth may be linked to their superior mechanical properties and environmental resilience. Biological composite structures with helicoidal schemes and designs have remarkable capacities to absorb impact energy and withstand damage. However, there is a dearth of extensive study on the influence of fiber redirection and reorientation inside the matrix of a helicoid structure on its mechanical performance and reactivity. The present study aimed to explore the static and transient responses of a bio-inspired helicoid laminated composite(B-iHLC) shell under the influence of an explosive load using an isomorphic method. The structural integrity of the shell is maintained by a viscoelastic basis known as the Pasternak foundation, which encompasses two coefficients of stiffness and one coefficient of damping. The equilibrium equations governing shell dynamics are obtained by using Hamilton's principle and including the modified first-order shear theory,therefore obviating the need to employ a shear correction factor. The paper's model and approach are validated by doing numerical comparisons with respected publications. The findings of this study may be used in the construction of military and civilian infrastructure in situations when the structure is subjected to severe stresses that might potentially result in catastrophic collapse. The findings of this paper serve as the foundation for several other issues, including geometric optimization and the dynamic response of similar mechanical structures.展开更多
Designing highly efficient Pt-free electrocatalysts with low overpotential for an alkaline hydrogen evolution reaction(HER)remains a significant challenge.Here,a novel and efficient cobalt(Co),ruthenium(Ru)bimetallic ...Designing highly efficient Pt-free electrocatalysts with low overpotential for an alkaline hydrogen evolution reaction(HER)remains a significant challenge.Here,a novel and efficient cobalt(Co),ruthenium(Ru)bimetallic electrocatalyst composed of CoRu nanoalloy decorated on the N-doped carbon nanotubes(CoRu@N-CNTs),was prepared by reacting fullerenol with melamine via hydrothermal treatment and followed by pyrolysis.Benefiting from the electronic communication between Co and Ru sites,the as-obtained CoRu@N-CNTs catalyst exhibited superior electrocatalytic HER activity.To deliver a current density of 10 mA·cm^(-2),it required an overpotential of merely 19 mV along with a Tafel slope of 26.19 mV·dec^(-1)in 1 mol·L^(-1)potassium hydroxide(KOH)solution,outperforming the benchmark Pt/C catalyst.The present work would pave a new way towards the design and construction of an efficient electrocatalyst for energy storage and conversion.展开更多
Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For inst...Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For instance,Al-O reaction is the most common pathway to release limited energy while Al-F reaction has received much attentions to enhance Al combustion efficiency.However,microscopic understanding of the Al-O/Al-F reaction dynamics remains unsolved,which is fundamentally necessary to further improve Al combustion efficiency.In this work,for the first time,Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles(n-Al)in oxygen/fluorine containing environments have been revealed via reactive molecular dynamics(RMD)simulations meshing together combustion experiments.Three RMD simulation systems of Al core/O_(2)/HF,n-Al/O_(2)/HF,and n-Al/O_(2)/CF4 with oxygen percentage ranging from 0%to 100%have been performed.The n-Al combustion in mixed O_(2)/CF_4 environments have been conducted by constant volume combustion experiments.RMD results show that Al-O reaction exhibits kinetic benefits while Al-F reaction owns thermodynamic benefits for n-Al combustion.In n-Al/O_(2)/HF,Al-O reaction gives faster energy release rate than Al-F reaction(1.1 times).The optimal energy release efficiency can be achieved with suitable oxygen percentage of 10%and 50%for n-Al/O_(2)/HF and n-Al/O_(2)/CF_4,respectively.In combustion experiments,90%of oxygen percentage can optimally enhance the peak pressure,pressurization rate and combustion heat.Importantly,Al-O reaction prefers to occur on the surface regions while Al-F reaction prefers to proceed in the interior regions of n-Al,confirming the kinetic/thermodynamic benefits of Al-O/Al-F reactions.The synergistic effect of Al-O/Al-F reaction for greatly enhancing n-Al combustion efficiency is demonstrated at atomicscale,which is beneficial for optimizing the combustion performance of metallic fuel.展开更多
A ternary system of PTFE/Al/Bi_(2)O_(3)is constructed by incorporating PTFE-based reactive material and thermite for enhancing the energy release of the PTFE-based reactive material.The effects of Bi_(2)O_(3)in the PT...A ternary system of PTFE/Al/Bi_(2)O_(3)is constructed by incorporating PTFE-based reactive material and thermite for enhancing the energy release of the PTFE-based reactive material.The effects of Bi_(2)O_(3)in the PTFE/Al/Bi_(2)O_(3)on both mechanical properties and the energy release were investigated through various tests such as thermogravimetry-differential scanning calorimetry,adiabatic oxygen bomb test and split Hopkinson pressure bar test.The microstructure observed through scanning electron microscope and Xray diffraction results are used to analyze the ignition and reaction mechanism of PTFE/Al/Bi_(2)O_(3).The results indicate that the PTFE/Al/Bi_(2)O_(3)are capable of triggering the exothermic reaction of molten PTFE/Bi_(2)O_(3)and Al/Bi_(2)O_(3)over the PTFE/Al reactive materials,thereby promoting reactions.The excessive aluminum in the ternary system is beneficial for increasing energy release.The ignition of shock-induced chemical reactions in PTFE/Al/Bi_(2)O_(3)is closely related to the material fracture.The dominant mechanism for hot-spot generation under Split Hopkinson Pressure Bar test is the frictional temperature rise at the microcrack after failure.展开更多
Dominant technology formation is the key for the hightech industry to“cross the chasm”and gain an established foothold in the market(and hence disrupt the regime).Therefore,a stimulus-response model is proposed to i...Dominant technology formation is the key for the hightech industry to“cross the chasm”and gain an established foothold in the market(and hence disrupt the regime).Therefore,a stimulus-response model is proposed to investigate the dominant technology by exploring its formation process and mechanism.Specifically,based on complex adaptive system theory and the basic stimulus-response model,we use a combination of agent-based modeling and system dynamics modeling to capture the interactions between dominant technology and the socio-technical landscape.The results indicate the following:(i)The dynamic interaction is“stimulus-reaction-selection”,which promotes the dominant technology’s formation.(ii)The dominant technology’s formation can be described as a dynamic process in which the adaptation intensity of technology standards increases continuously until it becomes the leading technology under the dual action of internal and external mechanisms.(iii)The dominant technology’s formation in the high-tech industry is influenced by learning ability,the number of adopting users and adaptability.Therein,a“critical scale”of learning ability exists to promote the formation of leading technology:a large number of adopting users can promote the dominant technology’s formation by influencing the adaptive response of technology standards to the socio-technical landscape and the choice of technology standards by the socio-technical landscape.There is a minimum threshold and a maximum threshold for the role of adaptability in the dominant technology’s formation.(iv)The socio-technical landscape can promote the leading technology’s shaping in the high-tech industry,and different elements have different effects.This study promotes research on the formation mechanism of dominant technology in the high-tech industry,presents new perspectives and methods for researchers,and provides essential enlightenment for managers to formulate technology strategies.展开更多
Dempster-Shafer evidence theory is broadly employed in the research of multi-source information fusion.Nevertheless,when fusing highly conflicting evidence it may pro-duce counterintuitive outcomes.To address this iss...Dempster-Shafer evidence theory is broadly employed in the research of multi-source information fusion.Nevertheless,when fusing highly conflicting evidence it may pro-duce counterintuitive outcomes.To address this issue,a fusion approach based on a newly defined belief exponential diver-gence and Deng entropy is proposed.First,a belief exponential divergence is proposed as the conflict measurement between evidences.Then,the credibility of each evidence is calculated.Afterwards,the Deng entropy is used to calculate information volume to determine the uncertainty of evidence.Then,the weight of evidence is calculated by integrating the credibility and uncertainty of each evidence.Ultimately,initial evidences are amended and fused using Dempster’s rule of combination.The effectiveness of this approach in addressing the fusion of three typical conflict paradoxes is demonstrated by arithmetic exam-ples.Additionally,the proposed approach is applied to aerial tar-get recognition and iris dataset-based classification to validate its efficacy.Results indicate that the proposed approach can enhance the accuracy of target recognition and effectively address the issue of fusing conflicting evidences.展开更多
The shock-induced reaction mechanism and characteristics of Ni/Al system,considering an Al nanoparticle-embedded Ni single crystal,are investigated through molecular dynamics simulation.For the shock melting of Al nan...The shock-induced reaction mechanism and characteristics of Ni/Al system,considering an Al nanoparticle-embedded Ni single crystal,are investigated through molecular dynamics simulation.For the shock melting of Al nanoparticle,interfacial crystallization and dissolution are the main characteristics.The reaction degree of Al particle first increases linearly and then logarithmically with time driven by rapid mechanical mixing and following dissolution.The reaction rate increases with the decrease of particle diameter,however,the reaction is seriously hindered by interfacial crystallization when the diameter is lower than 9 nm in our simulations.Meanwhile,we found a negative exponential growth in the fraction of crystallized Al atoms,and the crystallinity of B2-NiAl(up to 20%)is positively correlated with the specific surface area of Al particle.This can be attributed to the formation mechanism of B2-NiAl by structural evolution of finite mixing layer near the collapsed interface.For shock melting of both Al particle and Ni matrix,the liquid-liquid phase inter-diffusion is the main reaction mechanism that can be enhanced by the formation of internal jet.In addition,the enhanced diffusion is manifested in the logarithmic growth law of mean square displacement,which results in an almost constant reaction rate similar to the mechanical mixing process.展开更多
The heat transfer between two corresponding plates,disks,and concentric pipes has many applications,including water cleansing and lubrication.Furthermore,TiO_(2)-water-based nanofluids are used widely because it is us...The heat transfer between two corresponding plates,disks,and concentric pipes has many applications,including water cleansing and lubrication.Furthermore,TiO_(2)-water-based nanofluids are used widely because it is useful for operating and controlling the temperature,especially in photovoltaic technology and solar panels.Motivated by these applications,the current study is based on the nanoparticle aggregation effect on magnetohydrodynamics(MHD)flow via rotating parallel plates with the chemical reaction.To achieve maximum heat transportation,the Bruggeman model is used to adapt the Maxwell model.Also,melting and thermal radiation effects are considered in the modeling to discuss heat transport.The Runge-Kutta-Fehlberg 4th−5th order method is used to attain numerical solutions.The main focus of this study is to see the thermodynamic behavior considering several aspects of nanoparticle aggregation.The heat transfer rate between the parallel plates is enhanced by improving the thermophoresis,radiation,and Brownian motion parameters.The rise in Schmidt number and chemical reaction rate parameter decreases the concentration distribution.This study will be helpful in enhancing the thermal efficiency of photovoltaic technology in solar plates,water purifying,thermal management of electronic devices,designing effective cooling systems,and other sustainable technologies.展开更多
Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of con...Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of controversy.This study delves into the formation of polarons in different crystalline forms of TiO_(2) and their connection with the materials'structure.By employing density functional theory calculations with on-site Coulomb interaction correction(DFT+U),we provide a detailed analysis of the electronic polarization behavior in the anatase and rutile forms of TiO_(2).We focus on the polarization properties of defect-induced and photoexcited excess electrons on various TiO_(2) surfaces.The results reveal that the defect electrons can form small polarons on the anatase TiO_(2)(101)surface,while on the rutile TiO_(2)(110)surface,both small and large polarons(hybrid-state polarons)are formed.Photoexcited electrons are capable of forming both small and large polarons on the surfaces of both crystal types.The analysis indicates that the differences in polaron distribution are primarily determined by the intrinsic properties of the crystals;the structural and symmetry differences between anatase and rutile TiO_(2) lead to the distinct polaron behaviors.Further investigation suggests that the polarization behavior of defect electrons is also related to the arrangement of electron orbitals around the Ti atoms,while the polarization of photoexcited electrons is mainly facilitated by the lattice distortions.These findings elucidate the formation mechanisms of different types of polarons and may contribute to understanding the performance of TiO_(2)in different fields.展开更多
文摘Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal sources and N,N-dimethylformamide was employed as a solvent as well as a reductant to produce Cu(Ⅰ) complexes.(ⅱ) An iodide-containing compound was utilized as a ligand and iodide source to prepare complexes.An in situ metalligand reaction occurred and an iodide-bridged copper complex was generated.(ⅲ) A series of aldehydes were added to the reaction systems to induce in situ metal-ligand reactions between the aldehydes and the imidazo[1,5-a]pyridine derivatives,producing polydentate ligand scaffolds.Eight complexes were prepared and characterized.The catalytic activities of these complexes toward the ketalization of ketones by ethylene glycol were investigated.With the exception of complex4,the remaining seven complexes all showed high catalytic activity.The lower activity of 4 may be due to the larger radius of bridging iodide ions and the shorter Cu(Ⅰ)…Cu(Ⅰ) distance.CCDC:2357696,1·2CH_(2)Cl_(2);2357697,2;2018292,3;2092192,4;2092190,5;2155557,6;2406155,7;2406156,8·EtOH.
基金supported by the National Natural Science Foundation(22279036)the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003).
文摘Alloying transition metals with Pt is an effective strategy for optimizing Pt-based catalysts toward the oxygen reduction reaction(ORR).Atomic ordered intermetallic compounds(IMC)provide unique electronic and geometrical effects as well as stronger intermetallic interactions due to the ordered arrangement of metal atoms,thus exhibiting superior electrocata-lytic activity and durability.However,quantitatively analyzing the ordering degree of IMC and exploring the correlation between the ordering degree and ORR activity remains extremely challenging.Herein,a series of ternary Pt_(2)NiCo interme-tallic catalysts(o-Pt_(2)NiCo)with different ordering degree were synthesized by annealing temperature modulation.Among them,the o-Pt_(2)NiCo which annealed at 800℃for two hours exhibits the highest ordering degree and the optimal ORR ac-tivity,which the mass activity of o-Pt_(2)NiCo is 1.8 times and 2.8 times higher than that of disordered Pt_(2)NiCo alloy and Pt/C.Furthermore,the o-Pt_(2)NiCo still maintains 70.8%mass activity after 30,000 potential cycles.Additionally,the ORR activity test results for Pt_(2)NiCo IMC with different ordering degree also provide a positive correlation between the ordering degree and ORR activity.This work provides a prospective design direction for ternary Pt-based electrocatalysts.
文摘Sulfur-doped iron-cobalt tannate nanorods(S-FeCoTA)derived from metal-organic frameworks(MOFs)as electrocatalysts were synthesized via a one-step hydrothermal method.The optimized S-FeCoTA was interlaced by loose nanorods,which had many voids.The S-FeCoTA catalysts exhibited excellent electrochemical oxygen evolution reaction(OER)performance with a low overpotential of 273 mV at 10 mA·cm^(-2)and a small Tafel slope of 36 mV·dec^(-1)in 1 mol·L^(-1)KOH.The potential remained at 1.48 V(vs RHE)at 10 mA·cm^(-2)under continuous testing for 15 h,implying that S-FeCoTA had good stability.The Faraday efficiency of S-FeCoTA was 94%.The outstanding OER activity of S-FeCoTA is attributed to the synergistic effects among S,Fe,and Co,thus promoting electron transfer,reducing the reaction kinetic barrier,and enhancing the OER performance.
基金the financial support from the National Natural Science Foundation of China(No.22178307)China Southern Power Grid(Grant Nos.0470002022030103HX00002-01).
文摘The poor electronic conductivity of metal-organic framework(MOF)materials hinders their direct application in the field of electrocatalysis in fuel cells.Herein,we proposed a strategy of embedding carbon nanotubes(CNTs)during the growth process of MOF crystals,synthesizing a metalloporphyrin-based MOF catalyst TCPPCo-MOF-CNT with a unique CNT-intercalated MOF structure.Physical characterization revealed that the CNTs enhance the overall conductivity while retaining the original characteristics of the MOF and metalloporphyrin.Simultaneously,the insertion of CNTs generated adequate mesopores and created a hierarchical porous structure that enhances mass transfer efficiency.X-ray photoelectron spectroscopic analysis confirmed that the C atom in CNT changed the electron cloud density on the catalytic active center Co,optimizing the electronic structure.Consequently,the E_(1/2) of the TCPPCo-MOF-CNT catalyst under neutral conditions reached 0.77 V(vs.RHE),outperforming the catalyst without CNTs.When the TCPPCo-MOF-CNT was employed as the cathode catalyst in assembling microbial fuel cells(MFCs)with Nafion-117 as the proton exchange membrane,the maxi-mum power density of MFCs reached approximately 500 mW·m^(-2).
文摘We have examined the theoretical implications of combining two main and three auxiliary ligands to form several Ir(Ⅲ)complexes featuring a transition metal as their core atom to identify some appropriate organic lightemitting diode(OLED)materials.By utilizing electronic structure,frontier molecular orbitals,minimum single-line absorption,triplet excited states,and emission spectral data derived from the density functional theory,the usefulness of these Ir(Ⅲ)complexes,including(piq)_(2)Ir(acac),(piq)_(2)Ir(tmd),(piq)_(2)Ir(tpip),(fpiq)_(2)Ir(acac),(fpiq)_(2)Ir(tmd),and(fpiq)_(2)Ir(tpip),in OLEDs was examined,where piq=1-phenylisoquinoline,fpiq=1-(4-fluorophenyl)isoquinoline,acac=(3Z)-4-hydroxypent-3-en-2-one,tmd=(4Z)-5-hydroxy-2,2,6,6-tetramethylhept-4-en-3-one,and tpip=tetraphenylimido-diphosphonate.These complexes all have low-efficiency roll-off properties,especially(fpiq)_(2)Ir(tpip).Some researchers have successfully synthesized complexes extremely similar to(piq)_(2)Ir(acac)through the Suzuki-Miyaura coupling reaction.
基金supported by Shanxi Province Science Foundation for Youths(202203021212300)Taiyuan University of Science and Technology Scientific Research Initial Funding(20212064)Outstanding Doctoral Award Fund in Shanxi Province(20222060).
文摘The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.
基金supported by the National Natural Science Foundation of China(22209040,22202063).
文摘The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled electron transfer(PCET)hinders the overall OER efficiency.Herein,we report an ionic liquid(IL)modified CoSn(OH)_(6)nanocubes(denoted as CoS-n(OH)_(6)-IL),which could be prepared through a facile strategy.The modified IL would not change the structural character-istics of CoSn(OH)_(6),but could effectively regulate the local proton activity near the active sites.The CoSn(OH)_(6)-IL exhibited higher intrinsic OER performances than the pristine CoSn(OH)_(6)in neutral media.For example,the current density of CoS-n(OH)_(6)-IL at 1.8 V versus reversible hydrogen electrode(RHE)was about 4 times higher than that of CoSn(OH)_(6).According to the pH-dependent kinetic investigations,operando electrochemical impedance spectroscopic,chemical probe tests,and deuterium kinetic isotope effects,the interfacial layer of IL could be utilized as a proton transfer mediator to promote the proton transfer,which enhances the surface coverage of OER intermediates and reduces the activation barrier.Consequent-ly,the sluggish OER kinetics would be efficiently accelerated.This study provides a facile and effective strategy to facilitate the PCET processes and is beneficial to guide the rational design of OER electrocatalysts.
基金Project(52174338)supported by the National Natural Science Foundation of ChinaProjects(2022JJ20086,2021JJ30796)supported by the Natural Science Foundation of Hunan Province,China+1 种基金Project(2023CXQD005)supported by the Central South University Innovation-Driven Research Programme,ChinaProject(23B0841)supported by the Education Department of Hunan Provincial Government,China。
文摘Single-atom catalysts(SACs)are promising for oxygen reduction reaction(ORR)on account of their excellent catalytic activity and maximum utilization of atoms.However,due to the complicated preparation processes and expensive reagents used,the cost of SACs is usually too high to put into practical application.The development of cost-effective and sustainable SACs remains a great challenge.Herein,a low-cost method employing biomass is designed to prepare efficient single-atom Fe-N-C catalysts(SA-Fe-N-C).Benefiting from the confinement effect of porous carbon support and the coordination effect of glucose,SA-Fe-N-C is derived from cheap flour by the two-step pyrolysis.Atomically dispersed Fe atoms exist in the form of Fe-N_(x),which acts as active sites for ORR.The catalyst shows outstanding activity with a half-wave potential(E_(1/2))of 0.86 V,which is better than that of Pt/C(0.84 V).Additionally,the catalyst also exhibits superior stability.The ORR catalyzed by SA-Fe-N-C proceeds via an efficient 4e transfer pathway.The high performance of SA-Fe-N-C also benefits from its porous structure,extremely high specific surface area(1450.1 m^(2)/g),and abundant micropores,which are conducive to increasing the density of active sites and fully exposing them.This work provides a cost-effective strategy to synthesize SACs from cheap biomass,achieving a balance between performance and cost.
基金Project(52204164)supported by the National Natural Science Foundation of ChinaProject(2021QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST,China。
文摘The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying traditional maximum equivalent span beam(MESB)theory to determine deformation range,peak point,and angle influence poses a challenge.Considering the overall structure of the intersection roof,the maximum equivalent triangular plate(METP)theory is proposed,and its geometric parameter calculation formula and deflection calculation formula are obtained.The application of the two theories in 18 models with different intersection angles,roadway types,and surrounding rock lithology is verified by numerical analysis.The results show that:1)The METP structure of the intersection roof established by the simulation results of each model successfully determined the location of the roof’s high displacement zone;2)The area comparison method of the METP theory can be reasonably explained:①The roof subsidence of the intersection decreases with the increase of the intersection angle;②The roof subsidence at the intersection of different roadway types has a rectangular type>arch type>circular type;③The roof subsidence of the intersection with weak surrounding rock is significantly larger than that of the intersection with hard surrounding rock.According to the application results of the two theories,the four advantages of the METP theory are compared and clarified in the basic assumptions,mechanical models,main viewpoints,and mechanism analysis.The large deformation inducement of the intersection roof is then explored.The J 2 peak area of the roof drives the large deformation of the area,the peak point of which is consistent with the center of gravity position of the METP.Furthermore,the change in the range of this peak is consistent with the change law of the METP’s area.Hence,this theory clarifies the large deformation area of the intersection roof,which provides a clear guiding basis for its initial support design,mid-term monitoring,and late local reinforcement.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.11872120,12102050)Key Laboratory of Explosion Science and Technology(Grant No.QNKT22-01).
文摘The new CL-20(hexanitrohexaazaisowurtzitane)type aluminized explosives in the overdrive detonation(ODD)conditions of the core problem is how to accurately represent the state of the overdrive detonation products.To this end,this paper is based on the impedance matching method to test the ODD conditions of CL-20 type aluminium explosive particle velocity.Calculated the interfacial pressure of the shock wave in different media.Determined the characteristic parameters of the reaction zone of the detonation of CL-20 aluminized explosives.Calibrated the parameters of the JoneseWilkinseLee(JWL)+γ equation for the detonation products(DPs).Revealed the effect of different DPs equation of state(EOS)on the Hugoniot pressure of ODD.The results indicate that when the content of aluminum powder ranges from 0%to 30%,the duration of the ODD reaction zone and the width of the detonation reaction zone of the CL-20-based aluminized explosive are directly proportional to the content of aluminum powder.The width of the detonation reaction zone is increased by 1.97 times to 2.7 times compared to that of the reaction zone without the addition of aluminum powder.However,the energy release efficiency of the detonation reaction zone is inversely proportional to the content of aluminum powder.When the aluminum powder content was held constant,the incorporation of AP caused a 25%reduction in the energy release efficiency of the detonation reaction zone.Compared with existing ODD state equations,the JWL +γ equation is superior in calibrating overpressure Hugoniot data and the isentropic expansion in the C-J state.The deviation between calculated pressure results and experimental measurements is within 6%.
基金Project(52074294)supported by the National Natural Science Foundation of ChinaProject(2022YJSNY16)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Rock fracture warning is one of the significant challenges in rock mechanics.Many true triaxial and synchronous acoustic emission(AE)tests were conducted on granite samples.The investigation focused on the characteristics of AE signals preceding granite fracture,based on the critical slowing down(CSD)theory.The granite undergoes a transition from the stable phase to the fracture phase and exhibits a clear CSD phenomenon,characterized by a pronounced increase in variance and autocorrelation coefficient.The variance mutation points were found to be more identifiable and suitable as the primary criterion for predicting precursor information related to granite fracture,compared to the autocorrelation coefficient.It is noteworthy to emphasize that the CSD factor holds greater potential in elucidating the underlying mechanisms responsible for the critical transition of granite fracture,in comparison to the AE timing parameters.Furthermore,a novel multi-parameter collaborative prediction method for rock fracture was developed by comprehensively analyzing predictive information,including abnormal variation modes and the CSD factor of AE characteristic parameters.This method enhances the understanding and prediction of rock fracture-related geohazards.
文摘Investigating natural-inspired applications is a perennially appealing subject for scientists. The current increase in the speed of natural-origin structure growth may be linked to their superior mechanical properties and environmental resilience. Biological composite structures with helicoidal schemes and designs have remarkable capacities to absorb impact energy and withstand damage. However, there is a dearth of extensive study on the influence of fiber redirection and reorientation inside the matrix of a helicoid structure on its mechanical performance and reactivity. The present study aimed to explore the static and transient responses of a bio-inspired helicoid laminated composite(B-iHLC) shell under the influence of an explosive load using an isomorphic method. The structural integrity of the shell is maintained by a viscoelastic basis known as the Pasternak foundation, which encompasses two coefficients of stiffness and one coefficient of damping. The equilibrium equations governing shell dynamics are obtained by using Hamilton's principle and including the modified first-order shear theory,therefore obviating the need to employ a shear correction factor. The paper's model and approach are validated by doing numerical comparisons with respected publications. The findings of this study may be used in the construction of military and civilian infrastructure in situations when the structure is subjected to severe stresses that might potentially result in catastrophic collapse. The findings of this paper serve as the foundation for several other issues, including geometric optimization and the dynamic response of similar mechanical structures.
基金supported by the National Natural Science Foundation of China(No.52072226,U22A20144)Key Research and Development Program of Shaanxi(2024GX-YBXM-466)+1 种基金Science and Technology Program of Xi'an,China(22GXFW0013)Science and Technology Program of Weiyang District of Xi'an,China(202315)。
文摘Designing highly efficient Pt-free electrocatalysts with low overpotential for an alkaline hydrogen evolution reaction(HER)remains a significant challenge.Here,a novel and efficient cobalt(Co),ruthenium(Ru)bimetallic electrocatalyst composed of CoRu nanoalloy decorated on the N-doped carbon nanotubes(CoRu@N-CNTs),was prepared by reacting fullerenol with melamine via hydrothermal treatment and followed by pyrolysis.Benefiting from the electronic communication between Co and Ru sites,the as-obtained CoRu@N-CNTs catalyst exhibited superior electrocatalytic HER activity.To deliver a current density of 10 mA·cm^(-2),it required an overpotential of merely 19 mV along with a Tafel slope of 26.19 mV·dec^(-1)in 1 mol·L^(-1)potassium hydroxide(KOH)solution,outperforming the benchmark Pt/C catalyst.The present work would pave a new way towards the design and construction of an efficient electrocatalyst for energy storage and conversion.
基金support by the National Natural Science Foundation of China(NSFC,Grant Nos.12002324,12372341,12172342)。
文摘Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For instance,Al-O reaction is the most common pathway to release limited energy while Al-F reaction has received much attentions to enhance Al combustion efficiency.However,microscopic understanding of the Al-O/Al-F reaction dynamics remains unsolved,which is fundamentally necessary to further improve Al combustion efficiency.In this work,for the first time,Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles(n-Al)in oxygen/fluorine containing environments have been revealed via reactive molecular dynamics(RMD)simulations meshing together combustion experiments.Three RMD simulation systems of Al core/O_(2)/HF,n-Al/O_(2)/HF,and n-Al/O_(2)/CF4 with oxygen percentage ranging from 0%to 100%have been performed.The n-Al combustion in mixed O_(2)/CF_4 environments have been conducted by constant volume combustion experiments.RMD results show that Al-O reaction exhibits kinetic benefits while Al-F reaction owns thermodynamic benefits for n-Al combustion.In n-Al/O_(2)/HF,Al-O reaction gives faster energy release rate than Al-F reaction(1.1 times).The optimal energy release efficiency can be achieved with suitable oxygen percentage of 10%and 50%for n-Al/O_(2)/HF and n-Al/O_(2)/CF_4,respectively.In combustion experiments,90%of oxygen percentage can optimally enhance the peak pressure,pressurization rate and combustion heat.Importantly,Al-O reaction prefers to occur on the surface regions while Al-F reaction prefers to proceed in the interior regions of n-Al,confirming the kinetic/thermodynamic benefits of Al-O/Al-F reactions.The synergistic effect of Al-O/Al-F reaction for greatly enhancing n-Al combustion efficiency is demonstrated at atomicscale,which is beneficial for optimizing the combustion performance of metallic fuel.
基金the National Natural Science Foundation of China (Grant No.12002045)State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology (Grant No.QNKT22-09)。
文摘A ternary system of PTFE/Al/Bi_(2)O_(3)is constructed by incorporating PTFE-based reactive material and thermite for enhancing the energy release of the PTFE-based reactive material.The effects of Bi_(2)O_(3)in the PTFE/Al/Bi_(2)O_(3)on both mechanical properties and the energy release were investigated through various tests such as thermogravimetry-differential scanning calorimetry,adiabatic oxygen bomb test and split Hopkinson pressure bar test.The microstructure observed through scanning electron microscope and Xray diffraction results are used to analyze the ignition and reaction mechanism of PTFE/Al/Bi_(2)O_(3).The results indicate that the PTFE/Al/Bi_(2)O_(3)are capable of triggering the exothermic reaction of molten PTFE/Bi_(2)O_(3)and Al/Bi_(2)O_(3)over the PTFE/Al reactive materials,thereby promoting reactions.The excessive aluminum in the ternary system is beneficial for increasing energy release.The ignition of shock-induced chemical reactions in PTFE/Al/Bi_(2)O_(3)is closely related to the material fracture.The dominant mechanism for hot-spot generation under Split Hopkinson Pressure Bar test is the frictional temperature rise at the microcrack after failure.
基金supported by the Shanghai Philosophy and Social Science Foundation(2022ECK004)Shanghai Soft Science Research Project(23692123400)。
文摘Dominant technology formation is the key for the hightech industry to“cross the chasm”and gain an established foothold in the market(and hence disrupt the regime).Therefore,a stimulus-response model is proposed to investigate the dominant technology by exploring its formation process and mechanism.Specifically,based on complex adaptive system theory and the basic stimulus-response model,we use a combination of agent-based modeling and system dynamics modeling to capture the interactions between dominant technology and the socio-technical landscape.The results indicate the following:(i)The dynamic interaction is“stimulus-reaction-selection”,which promotes the dominant technology’s formation.(ii)The dominant technology’s formation can be described as a dynamic process in which the adaptation intensity of technology standards increases continuously until it becomes the leading technology under the dual action of internal and external mechanisms.(iii)The dominant technology’s formation in the high-tech industry is influenced by learning ability,the number of adopting users and adaptability.Therein,a“critical scale”of learning ability exists to promote the formation of leading technology:a large number of adopting users can promote the dominant technology’s formation by influencing the adaptive response of technology standards to the socio-technical landscape and the choice of technology standards by the socio-technical landscape.There is a minimum threshold and a maximum threshold for the role of adaptability in the dominant technology’s formation.(iv)The socio-technical landscape can promote the leading technology’s shaping in the high-tech industry,and different elements have different effects.This study promotes research on the formation mechanism of dominant technology in the high-tech industry,presents new perspectives and methods for researchers,and provides essential enlightenment for managers to formulate technology strategies.
基金supported by the National Natural Science Foundation of China(61903305,62073267)the Fundamental Research Funds for the Central Universities(HXGJXM202214).
文摘Dempster-Shafer evidence theory is broadly employed in the research of multi-source information fusion.Nevertheless,when fusing highly conflicting evidence it may pro-duce counterintuitive outcomes.To address this issue,a fusion approach based on a newly defined belief exponential diver-gence and Deng entropy is proposed.First,a belief exponential divergence is proposed as the conflict measurement between evidences.Then,the credibility of each evidence is calculated.Afterwards,the Deng entropy is used to calculate information volume to determine the uncertainty of evidence.Then,the weight of evidence is calculated by integrating the credibility and uncertainty of each evidence.Ultimately,initial evidences are amended and fused using Dempster’s rule of combination.The effectiveness of this approach in addressing the fusion of three typical conflict paradoxes is demonstrated by arithmetic exam-ples.Additionally,the proposed approach is applied to aerial tar-get recognition and iris dataset-based classification to validate its efficacy.Results indicate that the proposed approach can enhance the accuracy of target recognition and effectively address the issue of fusing conflicting evidences.
基金supported by the State Key Program of National Natural Science Foundation of China(Grant No.12132003)State Key Laboratory of Explosion Science and Technology(Grant No.QNKT20-07)。
文摘The shock-induced reaction mechanism and characteristics of Ni/Al system,considering an Al nanoparticle-embedded Ni single crystal,are investigated through molecular dynamics simulation.For the shock melting of Al nanoparticle,interfacial crystallization and dissolution are the main characteristics.The reaction degree of Al particle first increases linearly and then logarithmically with time driven by rapid mechanical mixing and following dissolution.The reaction rate increases with the decrease of particle diameter,however,the reaction is seriously hindered by interfacial crystallization when the diameter is lower than 9 nm in our simulations.Meanwhile,we found a negative exponential growth in the fraction of crystallized Al atoms,and the crystallinity of B2-NiAl(up to 20%)is positively correlated with the specific surface area of Al particle.This can be attributed to the formation mechanism of B2-NiAl by structural evolution of finite mixing layer near the collapsed interface.For shock melting of both Al particle and Ni matrix,the liquid-liquid phase inter-diffusion is the main reaction mechanism that can be enhanced by the formation of internal jet.In addition,the enhanced diffusion is manifested in the logarithmic growth law of mean square displacement,which results in an almost constant reaction rate similar to the mechanical mixing process.
基金Large research project(RGP2/159/45)supported by the Deanship of Research and Graduate Studies at King Khalid University,Saudi Arabia。
文摘The heat transfer between two corresponding plates,disks,and concentric pipes has many applications,including water cleansing and lubrication.Furthermore,TiO_(2)-water-based nanofluids are used widely because it is useful for operating and controlling the temperature,especially in photovoltaic technology and solar panels.Motivated by these applications,the current study is based on the nanoparticle aggregation effect on magnetohydrodynamics(MHD)flow via rotating parallel plates with the chemical reaction.To achieve maximum heat transportation,the Bruggeman model is used to adapt the Maxwell model.Also,melting and thermal radiation effects are considered in the modeling to discuss heat transport.The Runge-Kutta-Fehlberg 4th−5th order method is used to attain numerical solutions.The main focus of this study is to see the thermodynamic behavior considering several aspects of nanoparticle aggregation.The heat transfer rate between the parallel plates is enhanced by improving the thermophoresis,radiation,and Brownian motion parameters.The rise in Schmidt number and chemical reaction rate parameter decreases the concentration distribution.This study will be helpful in enhancing the thermal efficiency of photovoltaic technology in solar plates,water purifying,thermal management of electronic devices,designing effective cooling systems,and other sustainable technologies.
文摘Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of controversy.This study delves into the formation of polarons in different crystalline forms of TiO_(2) and their connection with the materials'structure.By employing density functional theory calculations with on-site Coulomb interaction correction(DFT+U),we provide a detailed analysis of the electronic polarization behavior in the anatase and rutile forms of TiO_(2).We focus on the polarization properties of defect-induced and photoexcited excess electrons on various TiO_(2) surfaces.The results reveal that the defect electrons can form small polarons on the anatase TiO_(2)(101)surface,while on the rutile TiO_(2)(110)surface,both small and large polarons(hybrid-state polarons)are formed.Photoexcited electrons are capable of forming both small and large polarons on the surfaces of both crystal types.The analysis indicates that the differences in polaron distribution are primarily determined by the intrinsic properties of the crystals;the structural and symmetry differences between anatase and rutile TiO_(2) lead to the distinct polaron behaviors.Further investigation suggests that the polarization behavior of defect electrons is also related to the arrangement of electron orbitals around the Ti atoms,while the polarization of photoexcited electrons is mainly facilitated by the lattice distortions.These findings elucidate the formation mechanisms of different types of polarons and may contribute to understanding the performance of TiO_(2)in different fields.
