As a versatile and environmentally benign oxidant,hydrogen peroxide(H_(2)O_(2))is highly desired in sanitation,disinfection,environmental remediation,and the chemical industry.Compared with the conventional anthraquin...As a versatile and environmentally benign oxidant,hydrogen peroxide(H_(2)O_(2))is highly desired in sanitation,disinfection,environmental remediation,and the chemical industry.Compared with the conventional anthraquinone process,the electrosynthesis of H_(2)O_(2)through the two-electron oxygen reduction reaction(2e^(−)ORR)is an efficient,competitive,and promising avenue.Electrocatalysts and devices are two core factors in 2e^(−)ORR,but the design principles of catalysts for different pH conditions and the development trends of relevant synthesis devices remain unclear.To this end,this review adopts a multiscale perspective to summarize recent advancements in the design principles,catalytic mechanisms,and application prospects of 2e^(−)ORR catalysts,with a particular focus on the influence of pH conditions,aiming at providing guidance for the selective design of advanced 2e^(−)ORR catalysts for highly-efficient H_(2)O_(2)production.Moreover,in response to diverse on-site application demands,we elaborate on the evolution of H_(2)O_(2)electrosynthesis devices,from rotating ring-disk electrodes and H-type cells to diverse flow-type cells.We elaborate on their characteristics and shortcomings,which can be beneficial for their further upgrades and customized applications.These insights may inspire the rational design of innovative catalysts and devices with high performance and wide serviceability for large-scale implementations.展开更多
Mine water pollution caused by improper discharge of industrial wastewater,waste liquid and waste residue into minedout areas is a new form of pollution occurred in China in recent years.This kind of pollution is buri...Mine water pollution caused by improper discharge of industrial wastewater,waste liquid and waste residue into minedout areas is a new form of pollution occurred in China in recent years.This kind of pollution is buried deeply,and it is difficult to control,dispose and repair.Deep contaminated mine water from abandoned mining areas may even enter the ocean,posing a great threat to marine ecosystems.In this study,using a water pollution incident occurred in a coal field at a depth of 80 m in Shandong Province,China,in 2015,as an example,the methods of engineering block disposal and groundwater remediation are reported,and the remediation effects are tested and evaluated by in-situ chemical detection and geophysical surveys.The test results showed that engineering blocking measures such as cut-off walls can obviously block the DNAPL diffusion process in mine water,but the blocking effect on organic pollutants dissolved in water was limited.It can slow down the diffusion process of organic gas.The presence of mining tunnels and mined-out areas in the contaminated zone enhances the diffusion speed of various pollutants,especially during the remediation process when pollutants rapidly spread throughout the entire contaminated area.Groundwater circulation extraction and oxidation methods have a significant degradation effect on pollutants like dichloromethane,but they may generate a large amount of secondary gaseous pollutants.These gaseous pollutants may migrate to the shallow subsurface through structures such as faults,leading to secondary subsurface contamination.When designing remediation plans,it is crucial to strike a balance between blocking and guiding in the context of both blocking and restoration projects for achieving effective remediation.展开更多
Ischemic stroke is a secondary cause of mortality worldwide,imposing considerable medical and economic burdens on society.Extracellular vesicles,serving as natural nanocarriers for drug delivery,exhibit excellent bioc...Ischemic stroke is a secondary cause of mortality worldwide,imposing considerable medical and economic burdens on society.Extracellular vesicles,serving as natural nanocarriers for drug delivery,exhibit excellent biocompatibility in vivo and have significant advantages in the management of ischemic stroke.However,the uncertain distribution and rapid clearance of extracellular vesicles impede their delivery efficiency.By utilizing membrane decoration or by encapsulating therapeutic cargo within extracellular vesicles,their delivery efficacy may be greatly improved.Furthermore,previous studies have indicated that microvesicles,a subset of large-sized extracellular vesicles,can transport mitochondria to neighboring cells,thereby aiding in the restoration of mitochondrial function post-ischemic stroke.Small extracellular vesicles have also demonstrated the capability to transfer mitochondrial components,such as proteins or deoxyribonucleic acid,or their sub-components,for extracellular vesicle-based ischemic stroke therapy.In this review,we undertake a comparative analysis of the isolation techniques employed for extracellular vesicles and present an overview of the current dominant extracellular vesicle modification methodologies.Given the complex facets of treating ischemic stroke,we also delineate various extracellular vesicle modification approaches which are suited to different facets of the treatment process.Moreover,given the burgeoning interest in mitochondrial delivery,we delved into the feasibility and existing research findings on the transportation of mitochondrial fractions or intact mitochondria through small extracellular vesicles and microvesicles to offer a fresh perspective on ischemic stroke therapy.展开更多
We propose a quantum Otto engine operating through a cycle of two isochoric processes,where the working substance interacts with a single-mode radiation field,and two unitary strokes,during which the working substance...We propose a quantum Otto engine operating through a cycle of two isochoric processes,where the working substance interacts with a single-mode radiation field,and two unitary strokes,during which the working substance is decoupled from the field.We investigate the influence of quantum superposition and quantum internal friction on the engine's power output and efficiency,demonstrating that these quantum effects enhance both performance metrics.While these enhancements are accompanied by increased power fluctuations,we show that such fluctuations can be effectively mitigated through careful selection of control parameters.Our results reveal that the proposed quantum Otto engine can achieve performance regimes that are thermally inconceivable in classical systems,including surpassing the Otto efficiency limit and attaining 100%efficiency with nonzero power output.展开更多
The inelastic deformations of shape memory alloys(SMAs)always show poor controllability due to the avalanche-like martensite transformation,and the effective control for the deformation of precision de-vices has been ...The inelastic deformations of shape memory alloys(SMAs)always show poor controllability due to the avalanche-like martensite transformation,and the effective control for the deformation of precision de-vices has been not yet mature.In this work,the phase field method was used to investigate the shape memory effects(SMEs)of NiTi SMAs undergoing grain size(GS)engineering,to obtain tunable one-way and stress-assisted two-way SMEs(OWSME and SATWSME).The OWSME and SATWSME of the systems with various gradient-nanograin structures and bimodal grain structure,as well as that with geometric gradients were simulated.The simulated results indicate that due to the GS dependences of martensite transformation and reorientation,the occurrence and expansion of martensite reorientation,martensite transformation and its reverse can be efficaciously controlled via the GS engineering.When combining the GS engineering and geometric gradient design,since the effects of GS and stress gradient can be su-perimposed or competing,and the responses of martensite reorientation,martensite transformation and its reverse to this are different,the OWSME and SATWSME of the geometrically graded systems with various nanograin structures can exhibit different improvements in controllability.In short,the reorienta-tion hardening modulus during OWSME is increased and the transformation temperature window during SATWSME is widened by GS engineering,indicating the improved controllability of SMEs.The optimal GS engineering schemes revealed in this work provide the basic reference and guidance for designing tun-able SMEs and producing NiTi-based driving devices catering to desired functional performance in various engineering fields.展开更多
The development of low-cost,abundant,and efficient non-metal catalysts has always been a research focus on photocatalytic hydrogen evolution reactions.Boron nitride nanosheet(BNNS),which is a promising non-metallic tw...The development of low-cost,abundant,and efficient non-metal catalysts has always been a research focus on photocatalytic hydrogen evolution reactions.Boron nitride nanosheet(BNNS),which is a promising non-metallic two-dimensional material,possesses remarkable properties.However,its inherently wide bandgap significantly limits their potential for visible-light-responsive catalysis,and conventional chemical methods struggle to overcome this limitation.In this study,we employed high-energy ionizing radiation to precisely regulate defect formation in BNNS at ambient temperature and pressure.The results showed that gamma-ray radiation markedly enhanced the efficiency of photocatalytic hydrogen production of the irradiated BNNS with increasing absorbed dose.The maximum hydrogen production rate of the samples reached 1033.7μmol/(g·h),which represents an increase of almost two orders of magnitude compared to commercial BNNS.The structural characterization also confirmed that the introduction of three-boron-center defects results in forming intermediate energy levels and improving the charge carrier separation efficiency of BNNS.This transformation converts BNNS from a wide bandgap semiconductor to a visible-light-responsive catalyst.This work not only provides a novel approach for the application of BNNS in visible-light photocatalysis,but also demonstrates the unique role of radiation technology in quantitatively regulating defects and improving catalytic activity.展开更多
Current transient analysis predominantly relies on zero-dimensional/one-dimensional tools,proficient at capturing aerothermodynamic variations across critical engine stations but insufficient for analyzing the interna...Current transient analysis predominantly relies on zero-dimensional/one-dimensional tools,proficient at capturing aerothermodynamic variations across critical engine stations but insufficient for analyzing the internal flow field evolution during transients.Addressing this gap,the study presents an enhanced quasi-three dimensional(quasi-3D)transient simulation technique that integrates component volume effects,offering a significant leap from the preceding quasi-3D transient simulation method based on quasi-steady assumption.By embedding the component volume effects on density,momentum,and energy within the physical temporal dimension of the Navier-Stokes equations,the refined quasi-3D transient model achieves a closer representation of physical phenomena.Validation against a single-shaft turbofan engine’s experimental data confirms the model’s accuracy.Average errors for key performance indicators,including shaft speed,thrust,mass flow rate,and critical component exit temperature and pressure,remain below 0.41%,5.69%,2.55%,3.18%and 0.67%,respectively.Crucially,the model exposes a discernible temporal lag in the compressor outlet pressure and temperature response due to volume effects—previously unquantified in quasi-3D transient simulations.And further exploration of the meridional flow field emphasizes the consequential role of volumes in transient flow field evolution.Incorporating volume effects within quasi-3D transient simulations enhances engine modeling and is pivotal for precise transient analysis in engine design and optimization.展开更多
The high-energy-density and low-cost features endow lithium-sulfur batteries with broad application prospects.However,many drawbacks,especially the detrimental shuttle effect,have hindered the further development of L...The high-energy-density and low-cost features endow lithium-sulfur batteries with broad application prospects.However,many drawbacks,especially the detrimental shuttle effect,have hindered the further development of LSBs.In response,a lot of new structures have been applied to suppress the shuttle effect and promote the development of LSBs.Recently,vacancy engineering has gained the attention of researchers due to its unique electronic structure.This review aims to analyze the application of vacancy engineering in LSBs.Firstly,the electrochemistry of LSBs has been systematically discussed and the existing challenges as well as improvement tactics of LSBs have also been presented.Subsequently,the preparation methods and characterization technologies of various vacancies are summarized,including oxygen vacancies,sulfur vacancies,selenium vacancies,other anion vacancies,cation vacancies,etc.The latest applications of vacancy engineering in LSBs are also summarized in this review.Finally,some prospects and insights for further investigation and practical application of vacancy engineering in LSBs are put forward.展开更多
In this work,we open an avenue toward rational design of potential efficient catalysts for sustainable ammonia synthesis through composition engineering strategy by exploiting the synergistic effects among the active ...In this work,we open an avenue toward rational design of potential efficient catalysts for sustainable ammonia synthesis through composition engineering strategy by exploiting the synergistic effects among the active sites as exemplified by diatomic metals anchored graphdiyne via the combination of hierarchical high-throughput screening,first-principles calculations,and molecular dynamics simulations.Totally 43 highly efficient catalysts feature ultralow onset potentials(|U_(onset)|≤0.40 V)with Rh-Hf and Rh-Ta showing negligible onset potentials of 0 and-0.04 V,respectively.Extremely high catalytic activities of Rh-Hf and Rh-Ta can be ascribed to the synergistic effects.When forming heteronuclears,the combinations of relatively weak(such as Rh)and relatively strong(such as Hf or Ta)components usually lead to the optimal strengths of adsorption Gibbs free energies of reaction intermediates.The origin can be ascribed to the mediate d-band centers of Rh-Hf and Rh-Ta,which lead to the optimal adsorption strengths of intermediates,thereby bringing the high catalytic activities.Our work provides a new and general strategy toward the architecture of highly efficient catalysts not only for electrocatalytic nitrogen reduction reaction(eNRR)but also for other important reactions.We expect that our work will boost both experimental and theoretical efforts in this direction.展开更多
The rotating propagation of a continuous detonation engine (CDE) with different types of nozzles is investigated in three-dimensional numerical simulation using a one-step chemical reaction model. Flux terms are solve...The rotating propagation of a continuous detonation engine (CDE) with different types of nozzles is investigated in three-dimensional numerical simulation using a one-step chemical reaction model. Flux terms are solved by the so-called monotonicity-preserving weighted essentially non-oscillatory (MPWENO) scheme. The simulated flow field agrees well with the previous experimental results. Once the initial transient effects die down, the detonation wave maintains continuous oscillatory propagation in the annular chamber as long as fuel is continuously injected. Using a numerical flow field, the propulsion per- formance of a CDE is computed for four types of nozzles, namely the constant-area nozzle, Laval nozzle, diverging nozzle and converging nozzle. The gross specific impulse of the CDE ranges 1 540-1 750 s and the mass flux per square meter ranges 313-330 kg/(m2·s) for different nozzles. Among these four types of nozzles, Laval nozzle performs the best, and these parameters are 1 800 N, 1 750 s and 313 kg/(m2.s). A nozzle can greatly improve the propulsion performance.展开更多
During the second period of China ＂Tanyue＂ Project, the explorer will softland on the moon. The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground. It is necessary to study...During the second period of China ＂Tanyue＂ Project, the explorer will softland on the moon. The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground. It is necessary to study its plume effects on the explorer component. The self-developed PWS （Plume WorkStation） software based on direct simulation Monte Carlo （DSMC） method is used to simulate the plume effects of two 150 N engines. Due to the complex structure of the explorer, PWS uses a decoupling method to treat the boundary mesh, which mainly interacts with simulation particles, and has no relation with the computational grids. After the analytical expressions of plane surfaces and curved surfaces of each boundary block are given, the particle position within or without the boundary blocks can be easily determined. Finally the 3D plume field of two 150 N engines is simulated. The pressure, temperature and velocity distributions of plume field are clearly presented by three characteristic slices. The aerodynamic effects on the explorer bottom, the landfall legs and antenna are separately shown. The compression influence on the plume flow of four landfall legs can be observed.展开更多
Power augmented ram （PAR）engine is a popular equipment to reduce the requirement of power for takeoff and improve aerodynamic performance. To provide detailed insight into the aerodynamic characteristics of wing-in-...Power augmented ram （PAR）engine is a popular equipment to reduce the requirement of power for takeoff and improve aerodynamic performance. To provide detailed insight into the aerodynamic characteristics of wing-in-ground effect （WIG）craft with PAR engine, numerical simulations are carried out on WIG craft models in cruise. Simplified engine models are applied to the simulations. Two cruise modes for PAR engine are considered. The aerodynamic characteristics of the WIG craft and other features are studied. Comparisons with WIG craft model without PAR show that shutoff of PAR engine results in an increase in drag and less change in lift. Accordingly for the work of PAR engine, the air flow blown from the engine accelerates the flow around the upper surface and a high-speed attached flow near the trailing edge is recorded. With the schemed PAR flow, more suction force is realized and the flow features over the wing vary noticeably. It is also shown that the Coanda effect,provided with an attached flow, introduces an appropriate and practical flow mode for WIG craft with PAR engine in cruise. The results refresh our understanding on aerodynamic characteristics of WIG craft.展开更多
As versatile and robust genome editing tools,clustered regularly interspaced short palindromic repeats(CRISPR)technologies have been broadly used in basic research,biotechnology,and therapeutic development.Off-target ...As versatile and robust genome editing tools,clustered regularly interspaced short palindromic repeats(CRISPR)technologies have been broadly used in basic research,biotechnology,and therapeutic development.Off-target mutagenesis by CRISPR systems has been demonstrated,and various methods have been developed to markedly increase their specificity.In this review,we highlight the efforts of producing and modifying guide RNA(gRNA)to minimize off-target activities,including sequence and structure design,tuning expression and chemical modification.The modalities of gRNA engineering can be applied across CRISPR systems.In conjunction with CRISPR protein effectors,the engineered gRNA enables efficient and precise genome editing.展开更多
Nozzle effects on thrust and inlet pressure of a multi-cycle air-breathing pulse detonation engine （APDE） are investigated experimentally. An APDE with 68 mm in diameter and 2 050 mm in length is operated using gaso...Nozzle effects on thrust and inlet pressure of a multi-cycle air-breathing pulse detonation engine （APDE） are investigated experimentally. An APDE with 68 mm in diameter and 2 050 mm in length is operated using gasoline/air mixture. Straight nozzle, converging nozzle, converging-diverging nozzle and diverging nozzle are tested. The results show that thrust augmentation of converging-diverging nozzle, diverging nozzle or straight nozzle is better than that of converging nozzle on the whole. Thrust augmentation of straight nozzle is worse than those of converging-diverging nozzle and diverging nozzle. Thrust augmentations of diverging nozzle with larger expansion ratio and converging-diverging nozzle with larger throat area range from 20% to 40% on tested frequencies and are better than those of congeneric other nozzles respectively. Nozzle effects on inlet pressure are also researched. At each frequency it is indicated that filling pressures and average peak pressures of inlet with diverging nozzle and converging-diverging nozzle with large throat cross section area are higher than those with straight nozzle and converging nozzle Pressures near thrust wall increase in an increase order from without nozzle, with diverging nozzle, straight nozzle and converging-diverging nozzle to converging nozzle.展开更多
Measuring bullwhip effect is useful for making better controls on production planning and enhancing the supply chain operating efficiency.First,this article establishes the comparative analysis model of bullwhip effec...Measuring bullwhip effect is useful for making better controls on production planning and enhancing the supply chain operating efficiency.First,this article establishes the comparative analysis model of bullwhip effect between(s,S)and Periodic Review(PR)inventory policy based on the quantitative bullwhip effect model under different inventories.Then,the impacts of lead time,inventory review time,autocorrelation coefficient,and the number of samples on the gap of bullwhip effect under(s,S)and PR IP are analyzed.The results show that bullwhip effect in PR is more intense than(s,S)inventory policy.Contractors should pay more attention to control bullwhip effect when adopting PR inventory policy to enhance the total operating efficiency of the engineering project supply chains.展开更多
The principle of sonic wave measurement was introduced, and cumulative damage effects of underground engineering rock mass under blasting load were studied by in situ test, using RSM-SY5 intelligent sonic wave apparat...The principle of sonic wave measurement was introduced, and cumulative damage effects of underground engineering rock mass under blasting load were studied by in situ test, using RSM-SY5 intelligent sonic wave apparatus. The blasting test was carried out for ten times at some tunnels of Changba Lead-Zinc Mine. The damage depth of surrounding rock caused by old blasting excavation （0.8-1.2 m） was confirmed. The relation between the cumulative damage degree and blast times was obtained. The results show that the sonic velocity decreases gradually with increasing blast times, hut the damage degree （D） increases. The damage cumulative law is non-linear. The damage degree caused by blast decreases with increasing distance, and damage effects become indistinct. The blasting damage of rock mass is anisotropic. The damage degree of rock mass within charging range is maximal. And the more the charge is, the more severe the damage degree of rock mass is. The test results provide references for researches of mechanical parameters of rock mass and dynamic stability analysis of underground chambers.展开更多
Non-noble metal electrocatalysis has witnessed rapid and profound performance improvements owing to the emergence of advanced nanosynthetic techniques.Integration of these nanotechniques can lead to synergistic perfor...Non-noble metal electrocatalysis has witnessed rapid and profound performance improvements owing to the emergence of advanced nanosynthetic techniques.Integration of these nanotechniques can lead to synergistic performance enhancement,but such system-engineering strategies are difficult to achieve because of the lack of effective synthesis method.We hereby demonstrate an integrated approach that combines most of the existing nanotechniques in a facile one-pot synthesis.Material characterization reveals that the product shows key features intended by techniques including morphological,structural,doping,heterointerface,and surface wetting engineering.The as-obtained nitrogen-doped hierarchical heterostructured MoS_(x)/Ni_(3)S_(2)nanowires show an overpotential that is only50 mV higher than commercial Pt/C for hydrogen evolution reaction over current densities from 10 to 150 mA cm^(-2).Correlations between the adopted nanotechniques and the electrochemical reaction rates are established by evaluating the impacts of individual techniques on the activation energy,pre-exponential factor,and transfer coefficient.This indepth analysis provides a full account of the synergistic effects and the overall improvement in electrocatalytic performance of hydrogen evolution reaction.This work manifests a generic strategy for multipurpose material design in non-noble metal electrocatalysis.展开更多
This article attempts to investigate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau. As a case study, Chaidaer-Muli Railway is used to evaluate the measure effect of ru...This article attempts to investigate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau. As a case study, Chaidaer-Muli Railway is used to evaluate the measure effect of rubble roadbed engineering in permafrost regions. The AHP(Analytic Hierarchy Process) method is thus employed to establish the evaluation indicator system. The evaluation factor is selected by analyzing the mutual relation between the permafrost environment and roadbed engineering. Thus, a hierarchical structure model is established based on the selected evaluation indices. Each factor is weighted to determine the status in the evaluation system, and grading standards are built for providing a basis for the evaluation. Then, the fuzzy mathematical method is introduced to evaluate the measure effect of rubble roadbed engineering in permafrost regions along the Chadaer-Muli Railway. Results show that most of the permafrost roadbed is in a preferable condition(b) along the Chaidaer-Muli Railway due to rubble engineering measures. This proportion reaches to 86.1%. The proportion in good(a), general(c) and poor states(d) are 0.0%, 7.5% and 6.4%, respectively, in all the evaluation sections along the Chaidaer-Muli Railway. Ground-temperature monitoring results are generally consistent with AHP-FUZZY evaluation results. This means that the AHP-FUZZY method can be applied to evaluate the effect of rubble roadbed engineering measures in permafrost regions. The effect evaluation of engineering measures will provide timely and effective feedback information for further engineering design. The series of engineering measures will more effectively protect permafrost stability.展开更多
The concentrically layered thermal cloaks with isotropic materials could realize the equivalent thermal cloaking effect with Pendry＇s cloak, while the effectiveness is scarcely investigated quantitatively. Here we ex...The concentrically layered thermal cloaks with isotropic materials could realize the equivalent thermal cloaking effect with Pendry＇s cloak, while the effectiveness is scarcely investigated quantitatively. Here we examine the cloaking effectiveness quantitatively by evaluating the standard deviation of the temperature difference between the simulated plane with the layered thermal cloak and Pendry＇s thermal cloak. The design rules for the isotropic materials in terms of thermal conductivity and layer thickness are presented. The present method could quan- titatively evaluate the cloaking effectiveness, and could open avenues for analyzing the cloaking effect, detecting the （anti-） cloaks, etc.展开更多
Developing efficient,stable,and low-cost electrocatalysts toward alkaline hydrogen evolution reactions(HER)in water electrolysis driven by renewable energy sources has always been discussed over the past decade.To red...Developing efficient,stable,and low-cost electrocatalysts toward alkaline hydrogen evolution reactions(HER)in water electrolysis driven by renewable energy sources has always been discussed over the past decade.To reduce energy consumption and improve energy utilization efficiency,highly active electrocatalytic electrodes are essential for lowering the energy barrier of the HER.Catalysts featuring multiple interfaces have attracted significant research interest recently due to their enhanced physicochemical properties.Reasonable interface modulation can optimize intermediate active species’adsorption energy,improve catalytic active sites’selectivity,and enhance intrinsic catalytic activity.Here,we provided an overview of the latest advancement in interface engineering for efficient HER catalysts.We begin with a brief introduction to the fundamental concepts and mechanisms of alkaline HER.Then,we analyze and discuss current regulating principles in interface engineering for HER catalysts,focusing particularly on optimizing electron structures and modulating microenvironment reactions.Finally,the challenges and further prospects of interface catalysts for future applications are discussed.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22102073,22075147).
文摘As a versatile and environmentally benign oxidant,hydrogen peroxide(H_(2)O_(2))is highly desired in sanitation,disinfection,environmental remediation,and the chemical industry.Compared with the conventional anthraquinone process,the electrosynthesis of H_(2)O_(2)through the two-electron oxygen reduction reaction(2e^(−)ORR)is an efficient,competitive,and promising avenue.Electrocatalysts and devices are two core factors in 2e^(−)ORR,but the design principles of catalysts for different pH conditions and the development trends of relevant synthesis devices remain unclear.To this end,this review adopts a multiscale perspective to summarize recent advancements in the design principles,catalytic mechanisms,and application prospects of 2e^(−)ORR catalysts,with a particular focus on the influence of pH conditions,aiming at providing guidance for the selective design of advanced 2e^(−)ORR catalysts for highly-efficient H_(2)O_(2)production.Moreover,in response to diverse on-site application demands,we elaborate on the evolution of H_(2)O_(2)electrosynthesis devices,from rotating ring-disk electrodes and H-type cells to diverse flow-type cells.We elaborate on their characteristics and shortcomings,which can be beneficial for their further upgrades and customized applications.These insights may inspire the rational design of innovative catalysts and devices with high performance and wide serviceability for large-scale implementations.
基金supported by the Polluted Site Remediation Project of Gao Village,Puji Street,Zhangqiu District,Jinan City,Shandong Provincefinancially supported by the National Natural Science Foundation of China(Nos.42072331,U1906209)the Taishan Scholar Foundation(No.tstp20230626)。
文摘Mine water pollution caused by improper discharge of industrial wastewater,waste liquid and waste residue into minedout areas is a new form of pollution occurred in China in recent years.This kind of pollution is buried deeply,and it is difficult to control,dispose and repair.Deep contaminated mine water from abandoned mining areas may even enter the ocean,posing a great threat to marine ecosystems.In this study,using a water pollution incident occurred in a coal field at a depth of 80 m in Shandong Province,China,in 2015,as an example,the methods of engineering block disposal and groundwater remediation are reported,and the remediation effects are tested and evaluated by in-situ chemical detection and geophysical surveys.The test results showed that engineering blocking measures such as cut-off walls can obviously block the DNAPL diffusion process in mine water,but the blocking effect on organic pollutants dissolved in water was limited.It can slow down the diffusion process of organic gas.The presence of mining tunnels and mined-out areas in the contaminated zone enhances the diffusion speed of various pollutants,especially during the remediation process when pollutants rapidly spread throughout the entire contaminated area.Groundwater circulation extraction and oxidation methods have a significant degradation effect on pollutants like dichloromethane,but they may generate a large amount of secondary gaseous pollutants.These gaseous pollutants may migrate to the shallow subsurface through structures such as faults,leading to secondary subsurface contamination.When designing remediation plans,it is crucial to strike a balance between blocking and guiding in the context of both blocking and restoration projects for achieving effective remediation.
基金supported by the grants from University of Macao,China,Nos.MYRG2022-00221-ICMS(to YZ)and MYRG-CRG2022-00011-ICMS(to RW)the Natural Science Foundation of Guangdong Province,No.2023A1515010034(to YZ)。
文摘Ischemic stroke is a secondary cause of mortality worldwide,imposing considerable medical and economic burdens on society.Extracellular vesicles,serving as natural nanocarriers for drug delivery,exhibit excellent biocompatibility in vivo and have significant advantages in the management of ischemic stroke.However,the uncertain distribution and rapid clearance of extracellular vesicles impede their delivery efficiency.By utilizing membrane decoration or by encapsulating therapeutic cargo within extracellular vesicles,their delivery efficacy may be greatly improved.Furthermore,previous studies have indicated that microvesicles,a subset of large-sized extracellular vesicles,can transport mitochondria to neighboring cells,thereby aiding in the restoration of mitochondrial function post-ischemic stroke.Small extracellular vesicles have also demonstrated the capability to transfer mitochondrial components,such as proteins or deoxyribonucleic acid,or their sub-components,for extracellular vesicle-based ischemic stroke therapy.In this review,we undertake a comparative analysis of the isolation techniques employed for extracellular vesicles and present an overview of the current dominant extracellular vesicle modification methodologies.Given the complex facets of treating ischemic stroke,we also delineate various extracellular vesicle modification approaches which are suited to different facets of the treatment process.Moreover,given the burgeoning interest in mitochondrial delivery,we delved into the feasibility and existing research findings on the transportation of mitochondrial fractions or intact mitochondria through small extracellular vesicles and microvesicles to offer a fresh perspective on ischemic stroke therapy.
基金supported by the National Natural Science Foundation of China(Grant No.12465009)support from the Major Program of Jiangxi Provincial Natural Science Foundation,China(Grant No.20224ACB201007)。
文摘We propose a quantum Otto engine operating through a cycle of two isochoric processes,where the working substance interacts with a single-mode radiation field,and two unitary strokes,during which the working substance is decoupled from the field.We investigate the influence of quantum superposition and quantum internal friction on the engine's power output and efficiency,demonstrating that these quantum effects enhance both performance metrics.While these enhancements are accompanied by increased power fluctuations,we show that such fluctuations can be effectively mitigated through careful selection of control parameters.Our results reveal that the proposed quantum Otto engine can achieve performance regimes that are thermally inconceivable in classical systems,including surpassing the Otto efficiency limit and attaining 100%efficiency with nonzero power output.
基金The National Natural Science Foundation of China(12022208)the Project funded by China Postdoctoral Science Foundation(2022M712243)the Fundamental Research Funds for the Cen-tral Universities are acknowledged.
文摘The inelastic deformations of shape memory alloys(SMAs)always show poor controllability due to the avalanche-like martensite transformation,and the effective control for the deformation of precision de-vices has been not yet mature.In this work,the phase field method was used to investigate the shape memory effects(SMEs)of NiTi SMAs undergoing grain size(GS)engineering,to obtain tunable one-way and stress-assisted two-way SMEs(OWSME and SATWSME).The OWSME and SATWSME of the systems with various gradient-nanograin structures and bimodal grain structure,as well as that with geometric gradients were simulated.The simulated results indicate that due to the GS dependences of martensite transformation and reorientation,the occurrence and expansion of martensite reorientation,martensite transformation and its reverse can be efficaciously controlled via the GS engineering.When combining the GS engineering and geometric gradient design,since the effects of GS and stress gradient can be su-perimposed or competing,and the responses of martensite reorientation,martensite transformation and its reverse to this are different,the OWSME and SATWSME of the geometrically graded systems with various nanograin structures can exhibit different improvements in controllability.In short,the reorienta-tion hardening modulus during OWSME is increased and the transformation temperature window during SATWSME is widened by GS engineering,indicating the improved controllability of SMEs.The optimal GS engineering schemes revealed in this work provide the basic reference and guidance for designing tun-able SMEs and producing NiTi-based driving devices catering to desired functional performance in various engineering fields.
文摘The development of low-cost,abundant,and efficient non-metal catalysts has always been a research focus on photocatalytic hydrogen evolution reactions.Boron nitride nanosheet(BNNS),which is a promising non-metallic two-dimensional material,possesses remarkable properties.However,its inherently wide bandgap significantly limits their potential for visible-light-responsive catalysis,and conventional chemical methods struggle to overcome this limitation.In this study,we employed high-energy ionizing radiation to precisely regulate defect formation in BNNS at ambient temperature and pressure.The results showed that gamma-ray radiation markedly enhanced the efficiency of photocatalytic hydrogen production of the irradiated BNNS with increasing absorbed dose.The maximum hydrogen production rate of the samples reached 1033.7μmol/(g·h),which represents an increase of almost two orders of magnitude compared to commercial BNNS.The structural characterization also confirmed that the introduction of three-boron-center defects results in forming intermediate energy levels and improving the charge carrier separation efficiency of BNNS.This transformation converts BNNS from a wide bandgap semiconductor to a visible-light-responsive catalyst.This work not only provides a novel approach for the application of BNNS in visible-light photocatalysis,but also demonstrates the unique role of radiation technology in quantitatively regulating defects and improving catalytic activity.
基金supported by the National Natural Science Foundation of China(No.52376021).
文摘Current transient analysis predominantly relies on zero-dimensional/one-dimensional tools,proficient at capturing aerothermodynamic variations across critical engine stations but insufficient for analyzing the internal flow field evolution during transients.Addressing this gap,the study presents an enhanced quasi-three dimensional(quasi-3D)transient simulation technique that integrates component volume effects,offering a significant leap from the preceding quasi-3D transient simulation method based on quasi-steady assumption.By embedding the component volume effects on density,momentum,and energy within the physical temporal dimension of the Navier-Stokes equations,the refined quasi-3D transient model achieves a closer representation of physical phenomena.Validation against a single-shaft turbofan engine’s experimental data confirms the model’s accuracy.Average errors for key performance indicators,including shaft speed,thrust,mass flow rate,and critical component exit temperature and pressure,remain below 0.41%,5.69%,2.55%,3.18%and 0.67%,respectively.Crucially,the model exposes a discernible temporal lag in the compressor outlet pressure and temperature response due to volume effects—previously unquantified in quasi-3D transient simulations.And further exploration of the meridional flow field emphasizes the consequential role of volumes in transient flow field evolution.Incorporating volume effects within quasi-3D transient simulations enhances engine modeling and is pivotal for precise transient analysis in engine design and optimization.
基金financially supported by Qing dao Post-doctoral Applied Research Project(No.QDBS H20220202040)the Natural Science Foundation of Shand ong Province,China(No ZR2021QE192)the Postdoctoral Science Foundation of China(No2018M63074)。
文摘The high-energy-density and low-cost features endow lithium-sulfur batteries with broad application prospects.However,many drawbacks,especially the detrimental shuttle effect,have hindered the further development of LSBs.In response,a lot of new structures have been applied to suppress the shuttle effect and promote the development of LSBs.Recently,vacancy engineering has gained the attention of researchers due to its unique electronic structure.This review aims to analyze the application of vacancy engineering in LSBs.Firstly,the electrochemistry of LSBs has been systematically discussed and the existing challenges as well as improvement tactics of LSBs have also been presented.Subsequently,the preparation methods and characterization technologies of various vacancies are summarized,including oxygen vacancies,sulfur vacancies,selenium vacancies,other anion vacancies,cation vacancies,etc.The latest applications of vacancy engineering in LSBs are also summarized in this review.Finally,some prospects and insights for further investigation and practical application of vacancy engineering in LSBs are put forward.
基金support from the National Natural Science Foundation of China(22073033,21873032,21673087,21903032)startup fund(2006013118 and 3004013105)from Huazhong University of Science and Technology+1 种基金the Fundamental Research Funds for the Central Universities(2019kfyRCPY116)the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003)
文摘In this work,we open an avenue toward rational design of potential efficient catalysts for sustainable ammonia synthesis through composition engineering strategy by exploiting the synergistic effects among the active sites as exemplified by diatomic metals anchored graphdiyne via the combination of hierarchical high-throughput screening,first-principles calculations,and molecular dynamics simulations.Totally 43 highly efficient catalysts feature ultralow onset potentials(|U_(onset)|≤0.40 V)with Rh-Hf and Rh-Ta showing negligible onset potentials of 0 and-0.04 V,respectively.Extremely high catalytic activities of Rh-Hf and Rh-Ta can be ascribed to the synergistic effects.When forming heteronuclears,the combinations of relatively weak(such as Rh)and relatively strong(such as Hf or Ta)components usually lead to the optimal strengths of adsorption Gibbs free energies of reaction intermediates.The origin can be ascribed to the mediate d-band centers of Rh-Hf and Rh-Ta,which lead to the optimal adsorption strengths of intermediates,thereby bringing the high catalytic activities.Our work provides a new and general strategy toward the architecture of highly efficient catalysts not only for electrocatalytic nitrogen reduction reaction(eNRR)but also for other important reactions.We expect that our work will boost both experimental and theoretical efforts in this direction.
基金Aeronautical Science Foundation of China (2008ZH71006)
文摘The rotating propagation of a continuous detonation engine (CDE) with different types of nozzles is investigated in three-dimensional numerical simulation using a one-step chemical reaction model. Flux terms are solved by the so-called monotonicity-preserving weighted essentially non-oscillatory (MPWENO) scheme. The simulated flow field agrees well with the previous experimental results. Once the initial transient effects die down, the detonation wave maintains continuous oscillatory propagation in the annular chamber as long as fuel is continuously injected. Using a numerical flow field, the propulsion per- formance of a CDE is computed for four types of nozzles, namely the constant-area nozzle, Laval nozzle, diverging nozzle and converging nozzle. The gross specific impulse of the CDE ranges 1 540-1 750 s and the mass flux per square meter ranges 313-330 kg/(m2·s) for different nozzles. Among these four types of nozzles, Laval nozzle performs the best, and these parameters are 1 800 N, 1 750 s and 313 kg/(m2.s). A nozzle can greatly improve the propulsion performance.
基金supported by the "Tanyue" Period Two Research Projects
文摘During the second period of China ＂Tanyue＂ Project, the explorer will softland on the moon. The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground. It is necessary to study its plume effects on the explorer component. The self-developed PWS （Plume WorkStation） software based on direct simulation Monte Carlo （DSMC） method is used to simulate the plume effects of two 150 N engines. Due to the complex structure of the explorer, PWS uses a decoupling method to treat the boundary mesh, which mainly interacts with simulation particles, and has no relation with the computational grids. After the analytical expressions of plane surfaces and curved surfaces of each boundary block are given, the particle position within or without the boundary blocks can be easily determined. Finally the 3D plume field of two 150 N engines is simulated. The pressure, temperature and velocity distributions of plume field are clearly presented by three characteristic slices. The aerodynamic effects on the explorer bottom, the landfall legs and antenna are separately shown. The compression influence on the plume flow of four landfall legs can be observed.
基金Program for Changjiang Scholars and Innovative Research Team in UniversityDoctoral Program Foundation of Institutions of Higher Education of China (20060247028)
文摘Power augmented ram （PAR）engine is a popular equipment to reduce the requirement of power for takeoff and improve aerodynamic performance. To provide detailed insight into the aerodynamic characteristics of wing-in-ground effect （WIG）craft with PAR engine, numerical simulations are carried out on WIG craft models in cruise. Simplified engine models are applied to the simulations. Two cruise modes for PAR engine are considered. The aerodynamic characteristics of the WIG craft and other features are studied. Comparisons with WIG craft model without PAR show that shutoff of PAR engine results in an increase in drag and less change in lift. Accordingly for the work of PAR engine, the air flow blown from the engine accelerates the flow around the upper surface and a high-speed attached flow near the trailing edge is recorded. With the schemed PAR flow, more suction force is realized and the flow features over the wing vary noticeably. It is also shown that the Coanda effect,provided with an attached flow, introduces an appropriate and practical flow mode for WIG craft with PAR engine in cruise. The results refresh our understanding on aerodynamic characteristics of WIG craft.
基金supported by the National Key Research and Development Program of China(2018YFA0801401 and 2019YFA0802801)the National Natural Science Foundation of China 31871345+1 种基金the Young Thousand Talented Program from Wuhan Universitythe startup funding from Wuhan University to H.Y.
文摘As versatile and robust genome editing tools,clustered regularly interspaced short palindromic repeats(CRISPR)technologies have been broadly used in basic research,biotechnology,and therapeutic development.Off-target mutagenesis by CRISPR systems has been demonstrated,and various methods have been developed to markedly increase their specificity.In this review,we highlight the efforts of producing and modifying guide RNA(gRNA)to minimize off-target activities,including sequence and structure design,tuning expression and chemical modification.The modalities of gRNA engineering can be applied across CRISPR systems.In conjunction with CRISPR protein effectors,the engineered gRNA enables efficient and precise genome editing.
基金National Natural Science Foundation of China(50976094, 51176158)Reseach Fund for the Doctoral Program of Higher Education of China(20096102110022)Doctorate Foundation of Northwestern Polytechnical University (CX200909)
文摘Nozzle effects on thrust and inlet pressure of a multi-cycle air-breathing pulse detonation engine （APDE） are investigated experimentally. An APDE with 68 mm in diameter and 2 050 mm in length is operated using gasoline/air mixture. Straight nozzle, converging nozzle, converging-diverging nozzle and diverging nozzle are tested. The results show that thrust augmentation of converging-diverging nozzle, diverging nozzle or straight nozzle is better than that of converging nozzle on the whole. Thrust augmentation of straight nozzle is worse than those of converging-diverging nozzle and diverging nozzle. Thrust augmentations of diverging nozzle with larger expansion ratio and converging-diverging nozzle with larger throat area range from 20% to 40% on tested frequencies and are better than those of congeneric other nozzles respectively. Nozzle effects on inlet pressure are also researched. At each frequency it is indicated that filling pressures and average peak pressures of inlet with diverging nozzle and converging-diverging nozzle with large throat cross section area are higher than those with straight nozzle and converging nozzle Pressures near thrust wall increase in an increase order from without nozzle, with diverging nozzle, straight nozzle and converging-diverging nozzle to converging nozzle.
文摘Measuring bullwhip effect is useful for making better controls on production planning and enhancing the supply chain operating efficiency.First,this article establishes the comparative analysis model of bullwhip effect between(s,S)and Periodic Review(PR)inventory policy based on the quantitative bullwhip effect model under different inventories.Then,the impacts of lead time,inventory review time,autocorrelation coefficient,and the number of samples on the gap of bullwhip effect under(s,S)and PR IP are analyzed.The results show that bullwhip effect in PR is more intense than(s,S)inventory policy.Contractors should pay more attention to control bullwhip effect when adopting PR inventory policy to enhance the total operating efficiency of the engineering project supply chains.
基金Project (50490272) supported by the National Natural Science Foundation of ChinaProject(040109) supported by the Doctor Degree Paper Innovation Engineering of Central South University
文摘The principle of sonic wave measurement was introduced, and cumulative damage effects of underground engineering rock mass under blasting load were studied by in situ test, using RSM-SY5 intelligent sonic wave apparatus. The blasting test was carried out for ten times at some tunnels of Changba Lead-Zinc Mine. The damage depth of surrounding rock caused by old blasting excavation （0.8-1.2 m） was confirmed. The relation between the cumulative damage degree and blast times was obtained. The results show that the sonic velocity decreases gradually with increasing blast times, hut the damage degree （D） increases. The damage cumulative law is non-linear. The damage degree caused by blast decreases with increasing distance, and damage effects become indistinct. The blasting damage of rock mass is anisotropic. The damage degree of rock mass within charging range is maximal. And the more the charge is, the more severe the damage degree of rock mass is. The test results provide references for researches of mechanical parameters of rock mass and dynamic stability analysis of underground chambers.
基金financial support from the NSFC(Grant No.21403119)the Science and Technology Bureau of Shenzhen(Grant No.JCYJ20170306171540744)
文摘Non-noble metal electrocatalysis has witnessed rapid and profound performance improvements owing to the emergence of advanced nanosynthetic techniques.Integration of these nanotechniques can lead to synergistic performance enhancement,but such system-engineering strategies are difficult to achieve because of the lack of effective synthesis method.We hereby demonstrate an integrated approach that combines most of the existing nanotechniques in a facile one-pot synthesis.Material characterization reveals that the product shows key features intended by techniques including morphological,structural,doping,heterointerface,and surface wetting engineering.The as-obtained nitrogen-doped hierarchical heterostructured MoS_(x)/Ni_(3)S_(2)nanowires show an overpotential that is only50 mV higher than commercial Pt/C for hydrogen evolution reaction over current densities from 10 to 150 mA cm^(-2).Correlations between the adopted nanotechniques and the electrochemical reaction rates are established by evaluating the impacts of individual techniques on the activation energy,pre-exponential factor,and transfer coefficient.This indepth analysis provides a full account of the synergistic effects and the overall improvement in electrocatalytic performance of hydrogen evolution reaction.This work manifests a generic strategy for multipurpose material design in non-noble metal electrocatalysis.
基金supported by the National Natural Science Foundation of China (Nos. 41501079 and 91647103)the self-determined Project Funded by State Key Laboratory of Frozen Soil Engineering (No. SKLFSE-ZQ-43)the Foundation for Excellent Youth Scholars of NIEER, CAS
文摘This article attempts to investigate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau. As a case study, Chaidaer-Muli Railway is used to evaluate the measure effect of rubble roadbed engineering in permafrost regions. The AHP(Analytic Hierarchy Process) method is thus employed to establish the evaluation indicator system. The evaluation factor is selected by analyzing the mutual relation between the permafrost environment and roadbed engineering. Thus, a hierarchical structure model is established based on the selected evaluation indices. Each factor is weighted to determine the status in the evaluation system, and grading standards are built for providing a basis for the evaluation. Then, the fuzzy mathematical method is introduced to evaluate the measure effect of rubble roadbed engineering in permafrost regions along the Chadaer-Muli Railway. Results show that most of the permafrost roadbed is in a preferable condition(b) along the Chaidaer-Muli Railway due to rubble engineering measures. This proportion reaches to 86.1%. The proportion in good(a), general(c) and poor states(d) are 0.0%, 7.5% and 6.4%, respectively, in all the evaluation sections along the Chaidaer-Muli Railway. Ground-temperature monitoring results are generally consistent with AHP-FUZZY evaluation results. This means that the AHP-FUZZY method can be applied to evaluate the effect of rubble roadbed engineering measures in permafrost regions. The effect evaluation of engineering measures will provide timely and effective feedback information for further engineering design. The series of engineering measures will more effectively protect permafrost stability.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51576078 and 51376070
文摘The concentrically layered thermal cloaks with isotropic materials could realize the equivalent thermal cloaking effect with Pendry＇s cloak, while the effectiveness is scarcely investigated quantitatively. Here we examine the cloaking effectiveness quantitatively by evaluating the standard deviation of the temperature difference between the simulated plane with the layered thermal cloak and Pendry＇s thermal cloak. The design rules for the isotropic materials in terms of thermal conductivity and layer thickness are presented. The present method could quan- titatively evaluate the cloaking effectiveness, and could open avenues for analyzing the cloaking effect, detecting the （anti-） cloaks, etc.
文摘Developing efficient,stable,and low-cost electrocatalysts toward alkaline hydrogen evolution reactions(HER)in water electrolysis driven by renewable energy sources has always been discussed over the past decade.To reduce energy consumption and improve energy utilization efficiency,highly active electrocatalytic electrodes are essential for lowering the energy barrier of the HER.Catalysts featuring multiple interfaces have attracted significant research interest recently due to their enhanced physicochemical properties.Reasonable interface modulation can optimize intermediate active species’adsorption energy,improve catalytic active sites’selectivity,and enhance intrinsic catalytic activity.Here,we provided an overview of the latest advancement in interface engineering for efficient HER catalysts.We begin with a brief introduction to the fundamental concepts and mechanisms of alkaline HER.Then,we analyze and discuss current regulating principles in interface engineering for HER catalysts,focusing particularly on optimizing electron structures and modulating microenvironment reactions.Finally,the challenges and further prospects of interface catalysts for future applications are discussed.
