The concept of TNT(Trinitrotoluene,C_7H_5N_3O_6)equivalence is often invoked to evaluate the performance and predict the explosion parameters of different types of explosives.However,due to its low prediction accuracy...The concept of TNT(Trinitrotoluene,C_7H_5N_3O_6)equivalence is often invoked to evaluate the performance and predict the explosion parameters of different types of explosives.However,due to its low prediction accuracy and limited application range,the use of TNT equivalence for predicting explosion parameters in a confined space is rare.Compared with explosions in free fields,the process of explosive energy release in a confined space is closely related to various factors such as oxygen balance,combustible components content,and surrounding oxygen content.Studies have shown that in a confined space,negative oxygen balance explosives react with surrounding oxygen during afterburning,resulting in additional energy release and enhanced blast effects.The mechanism of energy release during afterburning is highly complex,making it challenging to determine the TNT equivalence for blast effects in a confined space.Therefore,this remains an active area of research.In this study,internal blast experiments were conducted using TNT and three other explosives under both air and N_2(Nitrogen)conditions to obtain explosion parameters including blast wave overpressure,quasi-static pressure,and temperature.The influences of oxygen balance and external oxygen content on energy release are analyzed.The author proposes principles for determining TNT equivalence for internal explosions while verifying the accuracy of obtained blast parameters through calculations based on TNT equivalence.These findings can serve as references for predicting blast performance.展开更多
The detonation of fuel-rich explosives yields combustible products that persistently burn upon mixing with ambient oxygen,releasing additional energy through a phenomenon known as the afterburning effect.This process ...The detonation of fuel-rich explosives yields combustible products that persistently burn upon mixing with ambient oxygen,releasing additional energy through a phenomenon known as the afterburning effect.This process greatly influences the evolution of confined blast loading and the subsequent structural response,which is crucial in confined blast scenarios.Given the complex nature of the reaction process,accurate analysis of the afterburning effect remains challenging.Previous studies have either overlooked the mechanisms of detonation product combustion or failed to provide experimental validation.This study introduces a three-dimensional model to effectively characterize the combustion of detonation products.The model integrates chemical reaction source terms into the governing equations to consider the combustion processes.Numerical simulations and experimental tests were conducted to analyze the combustion and energy release from the detonation products of fuel-rich explosives in confined spaces.Approximately 50%of the energy was released during the combustion of detonation products in a confined TNT explosion.Although the combustion of these products was much slower than the detonation process,it aligned with the dynamic response of the structure,which enhanced the explosive yield.Excluding afterburning from the analysis reduced the center-point deformation of the structure by 30%.Following the inclusion of afterburning,the simulated quasistatic pressure increased by approximately 45%.Subsequent comparisons highlighted the merits of the proposed approach over conventional methods.This approach eliminates the reliance on empirical parameters,such as the amount and rate of energy release during afterburning,thereby laying the foundation for understanding load evolution in more complex environments,such as ships,buildings,and underground tunnels.展开更多
Flows and transport phenomena in confined spaces have emerged as a key direction in modern fluid dynamics research[1].Scaling down the hydrodynamic length of a system does not simply lead to a laminar flow in low Reyn...Flows and transport phenomena in confined spaces have emerged as a key direction in modern fluid dynamics research[1].Scaling down the hydrodynamic length of a system does not simply lead to a laminar flow in low Reynolds number,but reveals plenty of new phenomena with novel technological implications.Unlike in macroscale systems,fluid behavior at micro-and nanoscales is governed by forces that act at or near the interfaces,including surface tension,wettability,van der Waals interactions,and electrostatic effects,etc.These interfacial forces produce new hydrodynamics and mass transport phenomena that have not been observed on large scales,which are widely used in multidisciplinary areas.展开更多
Flexible surface micro-discharge plasma is a non-thermal plasma technique used for treating wounds in a painless way, with significant efficacy for chronic or hard-to-heal wounds. In this study, a confined space was d...Flexible surface micro-discharge plasma is a non-thermal plasma technique used for treating wounds in a painless way, with significant efficacy for chronic or hard-to-heal wounds. In this study, a confined space was designed to simulate wound conditions, with gelatin used to simulate wound tissue. The distinction between open and confined spaces was explored, and the effects of temperature, humidity, discharge power and the gap size within the confined space on the plasma characteristics were analyzed. It was found that temperature, humidity and discharge power are important factors that affect the concentration distribution of active components and the mode transition between ozone and nitrogen oxides. Compared to open space, the concentration of ozone in confined space was relatively lower, which facilitated the formation of nitrogen oxides. In open space, the discharge was dominated by ozone initially. As the temperature,humidity and discharge power increased, nitrogen oxides in the gas-phase products were gradually detected. In confined space, nitrogen oxides can be detected at an early stage and at much higher concentrations than ozone concentration. Furthermore, as the gap of the confined space decreased, the concentration of ozone was observed to decrease while that of nitrate increased, and the rate of this concentration change was further accelerated at higher temperature and higher power. It was shown that ozone concentration decreased from 0.11 to 0.03 μmol and the nitrate concentration increased from 20.5 to 24.5 μmol when the spacing in the confined space was reduced from 5 to 1 mm, the temperature of the external discharge was controlled at 40 ℃, and the discharge power was 12 W. In summary, this study reveals the formation and transformation mechanisms of active substances in air surface micro-discharge plasma within confined space, providing foundational data for its medical applications.展开更多
A highly porous nitrogen-doped carbon sphere(NPC)electrocatalyst was prepared through the carbonization of biomass carbon spheres mixed with urea and zinc chloride in N_(2) atmosphere.The sample carbonized at.1000℃ d...A highly porous nitrogen-doped carbon sphere(NPC)electrocatalyst was prepared through the carbonization of biomass carbon spheres mixed with urea and zinc chloride in N_(2) atmosphere.The sample carbonized at.1000℃ demonstrates a superior oxygen reduction reaction(ORR)performance over the Pt/C electrocatalyst,while its contents of pyridinic nitrogen and graphitic nitrogen are the lowest among samples synthesized at the same or lower carbonization temperatures.This unusual result is explained by a space confinement effect from the microporous and mesoporous structures in the microflakes,which induces the further reduction of peroxide ions or other oxygen species produced in the first step reduction to water to have the preferred overall four electron reduction ORR process.This work demonstrates that in addition to the amount or species of its aptive sites,the space confinement can be a new approach to enhance the ORR performance of precious-metal-free,nitrogen-doped carbon electrocatalysts.展开更多
Assembling two-dimensional(2D)MXene nanosheets into stable three-dimensional(3D)architectures is crucial for unlocking their potential in energy storage and adsorption applications.However,the inability of directional...Assembling two-dimensional(2D)MXene nanosheets into stable three-dimensional(3D)architectures is crucial for unlocking their potential in energy storage and adsorption applications.However,the inability of directional forces to overcome strong interlayer interactions under ambient conditions fundamentally limits the formation of stable 3D MXene structures.Herein,we unveil a universal confined-ion strategy that drives the 2D-to-3D transition inside natural wood microreactors.Potassium ions neutralize the surface charge of MXene nanosheets,triggering the formation of petal-like units,and spatial confinement guides their non-planar assembly into rose-like assemblies with tunable dimensions from 1.0 to 10.2μm.Compared with 2D MXene,the resulting 3D MXene assemblies exhibit a 16.1-fold larger specific surface area and outstanding electrochemical performance,delivering gravimetric and areal capacitances of 895.9 F·g^(−1) and 4.3 F·cm^(−2) with a retention of 100%after 10,000 cycles,respectively.The MXene assemblies also exhibit excellent multifunctionality,achieving a solar evaporation rate of 1.9 kg·m−2·h−1 and a dye removal efficiency of 99.1%.Importantly,this strategy is universal across a range of MXenes,offering a scalable and versatile platform for constructing robust 3D architectures from MXene.展开更多
Ultrasmall palladium nanoclusters have garnered significant attention due to their exceptional catalytic performance.However,their high surface energy always leads to aggregation,reducing the number of active sites an...Ultrasmall palladium nanoclusters have garnered significant attention due to their exceptional catalytic performance.However,their high surface energy always leads to aggregation,reducing the number of active sites and thereby decreasing catalytic efficiency.Herein,a molecular cage(RCC3)was utilized as a confined environment to stabilize ultrasmall PdNCs.The excellent solubility and open framework of cages not only enhance the solubility of palladium nanoclusters but also significantly improve their catalytic activity and stability.The prepared palladium nanoclusters were found to exhibit both peroxidase-like and oxidase-like activities.Under acidic conditions,the protonation of the molecular cage framework facilitates the assembly of ionic Pd nanoclusters with negatively charged enzymes through electrostatic interactions,forming a cascade system.The system is capable of detecting substrates,such as glucose and ascorbic acid,providing a highly catalytic platform for biosensing applications.展开更多
Chemical functionalization of graphene is a topic of paramount importance to broaden its applications in chemistry,physics,and biological science but remains a great challenge due to its low chemical activity and poor...Chemical functionalization of graphene is a topic of paramount importance to broaden its applications in chemistry,physics,and biological science but remains a great challenge due to its low chemical activity and poor dispersion.Here,we report a strategy for the photosynergetic electrochemical functionalization of graphene(EFG).By using chloride ion(Cl^(-))as the intercalation anions and co-reactants,the electrogenerated radicals confined in the expanded graphite layers enable efficient radical addition reaction,thus grasping crystallineperfect EFG.We found that the ultraviolet irradiation and applied voltage have increased the surface/interface concentration of Cl,thus boosting the functionalization of graphene.Theoretical calculation and experimental results verified the oxygen evolution reaction(OER)on EFG has been improved by regulating the doping of chlorine atoms.In addition,the reduced interlayer distance and enhanced electrostatic repulsion near the basal plane endow the fabricated EFG-based membrane with high salt retention.This work highlights a method for the in situ functionalization of graphene and the subsequent applications in OER and water desalination.展开更多
Nanosized NaY crystals have been prepared from metakaolin and sodium silicate by confined space synthesis with starch additive. It is found that the product has a narrow crystal size distribution (50-100 nm), high Si...Nanosized NaY crystals have been prepared from metakaolin and sodium silicate by confined space synthesis with starch additive. It is found that the product has a narrow crystal size distribution (50-100 nm), high Si/Al ratio (Si/Al=4.6-6.1), high surface area (1090 m2/g) and the average diameter of nanosized NaY (75 nm) synthesized is 30 nm, it is smaller than that of without starch additive.展开更多
In response to the demand for short-range detection of anti-smoke environment interference by laser fuzes,this study proposes a smoke environment simulation of non-uniform continuous point source diffusion and investi...In response to the demand for short-range detection of anti-smoke environment interference by laser fuzes,this study proposes a smoke environment simulation of non-uniform continuous point source diffusion and investigates an experimental laboratory smoke environment using an ammonium chloride smoke agent.The particle size distribution,composition,and mass flow distribution of the smoke were studied.Based on a discrete phase model and a kεturbulence model,a numerical simulation was developed to model the smoke generation and diffusion processes of the smoke agent in a confined space.The temporal and spatial distribution characteristics of the smoke mass concentration,velocity,and temperature in the space after smoke generation were analyzed,and the motion law governing the smoke diffusion throughout the entire space was summarized.Combined with the experimental verification of the smoke environment laboratory,the results showed that the smoke plume changed from fan-shaped to umbrella-shaped during smoke generation,and then continued to spread around.Meanwhile,the mass concentration of smoke in the space decreased from the middle outward;the changes in temperature and velocity were small and stable.In the diffusion stage(after 900 s),the mass concentration of smoke above 0.8 m was relatively uniform across an area of smoke that was 12 m thick.The concentration decreased over time,following a consistent decreasing trend,and the attenuation was negligible in a very short time.Therefore,this system was suitable for conducting experimental research on laser fuzes in a smoke environment.Owing to the stability of the equipment and facilities,the setup could reproduce the same experimental smoke environment by artificially controlling the smoke emission of the smoke agent.Overall,this work provides a theoretical reference for subsequent research efforts regarding the construction of uniform smoke environments and evaluating laser transmission characteristics in smoky environments.展开更多
A miniature process for separating the oil phase from dilute oil/water emulsion is developed.This process applies a confined space apparatus,which is a thin flow channel made of two parallel plastic plates.The space b...A miniature process for separating the oil phase from dilute oil/water emulsion is developed.This process applies a confined space apparatus,which is a thin flow channel made of two parallel plastic plates.The space between the two plates is rather narrow to improve the collisions between oil droplets and the plate surface.Oil droplets have an affinity for the plate surface and thus are captured,and then coalesce onto the surface.The droplet size distribution of the residual emulsion resulted from the separation process is remarkably changed.The oil layer on the plate weakens the further separation of oil droplets from the emulsion.Three types of plate materials,polypropylene(PP),polytetrafluoroethylene(PTFE) and nylon 66,were used.It is found that PP is the best in terms of the oil separation efficiency and nylon 66 is the poorest.The interaction between droplets in the emulsion and plate surface is indicated by the spreading coefficient of oil droplet on the plate in aqueous environment,and the influences of formed oil layer and plate material on the separation efficiency are discussed.展开更多
One of the major hazards when working onboard Tankers is working in confined spaces, improving the procedures in working in such spaces is obvious, but developing the equipments used in rescue operation is rare to hap...One of the major hazards when working onboard Tankers is working in confined spaces, improving the procedures in working in such spaces is obvious, but developing the equipments used in rescue operation is rare to happen, that＇s why this paper is focusing on differentiating between the manual ＆ more developed equipments used specially in rescuing the crew in such an adequate time, to save the workers＇ life. The manual way is called ＂MUCKY CRANE＂ which is used for rescue purposes onboard tankers, in any of the confined spaces, should be replaced by excel crane which is air or hydraulic driven machine, to achieve better results. As safety precautions measures taken in such tasks are not enough for the required objective achievement. Such safety procedures have been discussed and critical situations have been pointed out.展开更多
Molecular ferroelectrics,characterized by outstanding photoelectric and unique ferroelectric properties,invigorate the field of ferroelectric photovoltaics.Nonetheless,the performance of molecular ferroelectric device...Molecular ferroelectrics,characterized by outstanding photoelectric and unique ferroelectric properties,invigorate the field of ferroelectric photovoltaics.Nonetheless,the performance of molecular ferroelectric devices is hindered by fine grains resulting from poor high-temperature stability.In this work,we successfully achieved micron-grained molecular ferroelectric films by using the space-confined vapor deposited method.The optimized film exhibited a significant increase in grain size from the nanometer level(0.08μm)to the micrometer level(~2μm),leading to improved optoelectronic and ferroelectricity.Furthermore,it optimizes the energy level and enhances the photovoltaic performance of vertical devices.Research on the mechanism shows that high annealing temperature and inhibiting component loss play an important role in obtaining large grain films.This work provides new research ideas for improving the quality of molecular ferroelectric films and provides valuable reference for the fabrication of high performance molecular ferroelectric photovoltaic devices.展开更多
This study investigates the dynamical behaviors of nearest neighbor asymmetric coupled systems in a confined space.First, the study derivative analytical stability and synchronization conditions for the asymmetrically...This study investigates the dynamical behaviors of nearest neighbor asymmetric coupled systems in a confined space.First, the study derivative analytical stability and synchronization conditions for the asymmetrically coupled system in an unconfined space, which are then validated through numerical simulations. Simulation results show that asymmetric coupling has a significant impact on synchronization conditions. Moreover, it is observed that irrespective of whether the system is confined, an increase in coupling asymmetry leads to a hastened synchronization pace. Additionally, the study examines the effects of boundaries on the system's collective behaviors via numerical experiments. The presence of boundaries ensures the system's stability and synchronization, and reducing these boundaries can expedite the synchronization process and amplify its effects. Finally, the study reveals that the system's output amplitude exhibits stochastic resonance as the confined boundary size increases.展开更多
Researchers have been inspired by the movementand sensory abilities of animals in recent years due to theidea of soft robotics. This has resulted in the creation of biomimetic soft robots, which incorporate traits lik...Researchers have been inspired by the movementand sensory abilities of animals in recent years due to theidea of soft robotics. This has resulted in the creation of biomimetic soft robots, which incorporate traits like biologicalvision and tactile sensation for use in manipulation, obstacleavoidance, and path planning. The miniaturization of softrobots has become a key area of research. However, their smallsize has limited their single locomotion capabilities, preventing true functional integration akin to that of biological systems.Inspired by the movement and electro-sensory abilitiesof insects in nature, this research developed a compact andlightweight (900 mg) electrothermal-driven (ETA) soft robotequipped with capacitive non-contact sensing. The electrothermalPE/CNT/PI composite film actuator exhibits excellentmechanical properties and flexibility, achieving a maximumbending angle of 320° and demonstrating a load capacity of atleast 5 times its own weight. The sensor component consists of0.2 mm diameter silver wire, which detects the proximity ofobjects through changes in the edge electric field. The signalresponse is highly sensitive and can effectively identify obstacles of various diameters. Compared to other reportedworks, this soft robot focuses on detecting the external environment,possessing the ability to sense obstacles in narrowspaces and dimly lit conditions. It also utilizes the generationof sensor signal changes during motion to obtain informationabout its own posture. This provides a new approach and basisfor future applications in complex environments.展开更多
Understandingmass transport within confined spaces is a key challenge with broad implications across numerous scientific and engineering disciplines.While studies on channel size effects and channel wall dynamics have...Understandingmass transport within confined spaces is a key challenge with broad implications across numerous scientific and engineering disciplines.While studies on channel size effects and channel wall dynamics have deepened our knowledge of material transport,the combined analysis of both factors remains underexplored.This study reports on a fatty acid,heptanoic acid,that spontaneously intercalates into graphene/SiO_(2)in its gaseous state but is controllably intercalated in its liquid state through laser irradiation.Leveraging the diverse local properties of the system—such as the confined spaces between flexible graphene and atomically rough SiO_(2)—we employed time-course Raman spectroscopy to record and analyze multiple dynamic molecular intercalation processes.Through systematic analysis,we propose a model based on the dynamic changes of three key parameters:graphene doping,strain,and 2D-band intensity(I2D)during the liquid molecular intercalation process,derived from time-course Raman spectroscopy data.This model allows for the assessment of the impact of molecular intercalation in confined spaces and the quantification of intercalation efficiency.Additionally,we explore the mechanisms by which laser irradiation regulates molecular intercalation behavior.This study provides a foundation for understanding and optimizing molecular transport within graphene-based systems featuring confined spaces.展开更多
Molybdenum disulfide (MoS_(2)) has received enormous attentions in the electrochemical energy storage due to its unique two-dimensional layered structure and relatively high reversible capacity. However, the applicati...Molybdenum disulfide (MoS_(2)) has received enormous attentions in the electrochemical energy storage due to its unique two-dimensional layered structure and relatively high reversible capacity. However, the application of MoS_(2) in potassium-ion batteries (PIBs) is restricted by poor rate capability and cyclability, which are associated with the sluggish reaction kinetics and the huge volume expansion during K+ intercalation. Herein, we propose a two-dimensional (2D) space confined strategy to construct van der Waals heterostructure for superior PIB anode, in which the MoS_(2) nanosheets can be well dispersed on reduced graphene oxide nanosheets by leveraging the confinement effect within the graphene layers and amorphous carbon. The strong synergistic effects in 2D van der Waals heterostructure can extremely promote the electron transportation and ions diffusion during K+ insertion/extraction. More significantly, the 2D space-confinement effect and van der Waals force inhibit polysulfide conversion product dissolution into the electrolyte, which significantly strengthens the structural durability during the long-term cycling process. As anticipated, the as-synthesized the “face-to-face” C/MoS_(2)/G anode delivers remarkable K-storage performance, especially for high reversible capacity (362.5 mAh·g^(-1) at 0.1 A·g^(-1)), excellent rate capability (195.4 mAh·g^(-1) at 10 Ag^(-1)) and superior ultrahigh-rate long-cycling stability (126.4 mAh·g^(-1) after 4000 cycles at high rate of 5 A·g^(-1)). This work presents a promise strategy of structure designing and composition optimization for 2D layered materials in advanced energy storage application.展开更多
Abstract The microlayer or nanolayer coextrusion of hundreds or thousands of alternating low density polyethylene （LDPE）/polystyrene （PS） microlayers or nanolayers were used to study the orientation of LDPE crysta...Abstract The microlayer or nanolayer coextrusion of hundreds or thousands of alternating low density polyethylene （LDPE）/polystyrene （PS） microlayers or nanolayers were used to study the orientation of LDPE crystals in the confined quasi-two-dimensional or two-dimensional space. The clear and continuous layer structures from microscale to nanoscale can be found in SEM images. The morphology evolution of LDPE crystals in the confined microlayer or nanolayer can he varied from 3D spherulites, 2D spherulites, stacked edge-on lamellar, to single edge-on lamellar. Due to the orientation of the LDPE crystals, the tensile strength of the films increases obviously when the layer thickness reduces to nanoscale. The 2D small angle X-ray scattering （SAXS） patterns can reflect the average degree of orientation of LDPE in the confined layers. The stacking of LDPE lamellae is suppressed in interlamination and oppositely in parallel to the extrusion direction. The specific orientation function f can be calculated from the patterns. The infrared dichroism further confirms the mutation of the orientation of LDPE crystals from microscale to nanoscale in the confined space.展开更多
Aiming at the four issues of underground storage state,exploitation mechanism,crude oil flow and efficient recovery,the key theoretical and technical issues and countermeasures for effective development of Gulong shal...Aiming at the four issues of underground storage state,exploitation mechanism,crude oil flow and efficient recovery,the key theoretical and technical issues and countermeasures for effective development of Gulong shale oil are put forward.Through key exploration and research on fluid occurrence,fluid phase change,exploitation mechanism,oil start-up mechanism,flow regime/pattern,exploitation mode and enhanced oil recovery(EOR)of shale reservoirs with different storage spaces,multi-scale occurrence states of shale oil and phase behavior of fluid in nano confined space were provided,the multi-phase,multi-scale flow mode and production mechanism with hydraulic fracture-shale bedding fracture-matrix infiltration as the core was clarified,and a multi-scale flow mathematical model and recoverable reserves evaluation method were preliminarily established.The feasibility of development mode with early energy replenishment and recovery factor of 3o%was discussed.Based on these,the researches of key theories and technologies for effective development of Gulong shale oil are proposed to focus on:(1)in-situ sampling and non-destructive testing of core and fluid;(2)high-temperature,high-pressure,nano-scale laboratory simulation experiment;(3)fusion of multi-scale multi-flow regime numerical simulation technology and large-scale application software;(4)waterless(CO_(2))fracturing technique and the fracturing technique for increasing the vertical fracture height;(5)early energy replenishment to enhance oil recovery;(6)lifecycle technical and economic evaluation.Moreover,a series of exploitation tests should be performed on site as soon as possible to verify the theoretical understanding,optimize the exploitation mode,form supporting technologies,and provide a generalizable development model,thereby supporting and guiding the effective development and production of Gulong shale oil.展开更多
Herein,we successfully prepare highly dispersed and uniform small nano-size nickel nanoparticles embedded on core-shell carbon spheres by confined-deposition method.The mesoporous silica layer containing surfactant co...Herein,we successfully prepare highly dispersed and uniform small nano-size nickel nanoparticles embedded on core-shell carbon spheres by confined-deposition method.The mesoporous silica layer containing surfactant coated on the surface of the polymer sphere provides confined space and effectively controls the growth of nickel nanoparticles during pyrolysis.At the same time,the introduction of nickel species has an impact on structure of the obtained carbon spheres,and it can promote the deposition of carbon to realize the adjustment from hollow to core-shell and then to solid spheres.Owing to the uniform distribution of Ni nanoparticles with small size,mesoporous structure,N-doping groups,high specified surface areas,and core-shell structure,the obtained catalyst shows exciting ability for the production of CO by reduction of CO_(2)with a maximum CO Faradaic efficiency of 98%,indicating its promising prospect in electro-reduction of CO_(2).展开更多
文摘The concept of TNT(Trinitrotoluene,C_7H_5N_3O_6)equivalence is often invoked to evaluate the performance and predict the explosion parameters of different types of explosives.However,due to its low prediction accuracy and limited application range,the use of TNT equivalence for predicting explosion parameters in a confined space is rare.Compared with explosions in free fields,the process of explosive energy release in a confined space is closely related to various factors such as oxygen balance,combustible components content,and surrounding oxygen content.Studies have shown that in a confined space,negative oxygen balance explosives react with surrounding oxygen during afterburning,resulting in additional energy release and enhanced blast effects.The mechanism of energy release during afterburning is highly complex,making it challenging to determine the TNT equivalence for blast effects in a confined space.Therefore,this remains an active area of research.In this study,internal blast experiments were conducted using TNT and three other explosives under both air and N_2(Nitrogen)conditions to obtain explosion parameters including blast wave overpressure,quasi-static pressure,and temperature.The influences of oxygen balance and external oxygen content on energy release are analyzed.The author proposes principles for determining TNT equivalence for internal explosions while verifying the accuracy of obtained blast parameters through calculations based on TNT equivalence.These findings can serve as references for predicting blast performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.52171318 and 12202329)Joint Foundation of the Ministry of Education(Grant No.8091B022105)。
文摘The detonation of fuel-rich explosives yields combustible products that persistently burn upon mixing with ambient oxygen,releasing additional energy through a phenomenon known as the afterburning effect.This process greatly influences the evolution of confined blast loading and the subsequent structural response,which is crucial in confined blast scenarios.Given the complex nature of the reaction process,accurate analysis of the afterburning effect remains challenging.Previous studies have either overlooked the mechanisms of detonation product combustion or failed to provide experimental validation.This study introduces a three-dimensional model to effectively characterize the combustion of detonation products.The model integrates chemical reaction source terms into the governing equations to consider the combustion processes.Numerical simulations and experimental tests were conducted to analyze the combustion and energy release from the detonation products of fuel-rich explosives in confined spaces.Approximately 50%of the energy was released during the combustion of detonation products in a confined TNT explosion.Although the combustion of these products was much slower than the detonation process,it aligned with the dynamic response of the structure,which enhanced the explosive yield.Excluding afterburning from the analysis reduced the center-point deformation of the structure by 30%.Following the inclusion of afterburning,the simulated quasistatic pressure increased by approximately 45%.Subsequent comparisons highlighted the merits of the proposed approach over conventional methods.This approach eliminates the reliance on empirical parameters,such as the amount and rate of energy release during afterburning,thereby laying the foundation for understanding load evolution in more complex environments,such as ships,buildings,and underground tunnels.
文摘Flows and transport phenomena in confined spaces have emerged as a key direction in modern fluid dynamics research[1].Scaling down the hydrodynamic length of a system does not simply lead to a laminar flow in low Reynolds number,but reveals plenty of new phenomena with novel technological implications.Unlike in macroscale systems,fluid behavior at micro-and nanoscales is governed by forces that act at or near the interfaces,including surface tension,wettability,van der Waals interactions,and electrostatic effects,etc.These interfacial forces produce new hydrodynamics and mass transport phenomena that have not been observed on large scales,which are widely used in multidisciplinary areas.
基金supported by Postgraduate Research&Practice Innovation Program of Jiangsu Province (No. 1003016001)。
文摘Flexible surface micro-discharge plasma is a non-thermal plasma technique used for treating wounds in a painless way, with significant efficacy for chronic or hard-to-heal wounds. In this study, a confined space was designed to simulate wound conditions, with gelatin used to simulate wound tissue. The distinction between open and confined spaces was explored, and the effects of temperature, humidity, discharge power and the gap size within the confined space on the plasma characteristics were analyzed. It was found that temperature, humidity and discharge power are important factors that affect the concentration distribution of active components and the mode transition between ozone and nitrogen oxides. Compared to open space, the concentration of ozone in confined space was relatively lower, which facilitated the formation of nitrogen oxides. In open space, the discharge was dominated by ozone initially. As the temperature,humidity and discharge power increased, nitrogen oxides in the gas-phase products were gradually detected. In confined space, nitrogen oxides can be detected at an early stage and at much higher concentrations than ozone concentration. Furthermore, as the gap of the confined space decreased, the concentration of ozone was observed to decrease while that of nitrate increased, and the rate of this concentration change was further accelerated at higher temperature and higher power. It was shown that ozone concentration decreased from 0.11 to 0.03 μmol and the nitrate concentration increased from 20.5 to 24.5 μmol when the spacing in the confined space was reduced from 5 to 1 mm, the temperature of the external discharge was controlled at 40 ℃, and the discharge power was 12 W. In summary, this study reveals the formation and transformation mechanisms of active substances in air surface micro-discharge plasma within confined space, providing foundational data for its medical applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.51672283 and 51902271)the Fundamental Research Funds for the Central Universities(Grant Nos.A1920502051907-15,2682020CX07,and 2682020CX08)+3 种基金Sichuan Science and Technology Program(Grant Nos.2020YJ0259 and 2020YJ0072)Shandong Provincial Natural Science Foundation(Grant No.ZR2019MEM045)Joint Fund between Shenyang National Laboratory for Materials Science and State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals(Grant No.18LHPY009)Liaoning Baiqianwan Talents Program.
文摘A highly porous nitrogen-doped carbon sphere(NPC)electrocatalyst was prepared through the carbonization of biomass carbon spheres mixed with urea and zinc chloride in N_(2) atmosphere.The sample carbonized at.1000℃ demonstrates a superior oxygen reduction reaction(ORR)performance over the Pt/C electrocatalyst,while its contents of pyridinic nitrogen and graphitic nitrogen are the lowest among samples synthesized at the same or lower carbonization temperatures.This unusual result is explained by a space confinement effect from the microporous and mesoporous structures in the microflakes,which induces the further reduction of peroxide ions or other oxygen species produced in the first step reduction to water to have the preferred overall four electron reduction ORR process.This work demonstrates that in addition to the amount or species of its aptive sites,the space confinement can be a new approach to enhance the ORR performance of precious-metal-free,nitrogen-doped carbon electrocatalysts.
基金the financial support from the China Scholarship Council.This work was supported by the National Key Research and Development Program of China(No.2023YFD2201403)the National Natural Science Foundation of China(Nos.32171693 and 52303361).
文摘Assembling two-dimensional(2D)MXene nanosheets into stable three-dimensional(3D)architectures is crucial for unlocking their potential in energy storage and adsorption applications.However,the inability of directional forces to overcome strong interlayer interactions under ambient conditions fundamentally limits the formation of stable 3D MXene structures.Herein,we unveil a universal confined-ion strategy that drives the 2D-to-3D transition inside natural wood microreactors.Potassium ions neutralize the surface charge of MXene nanosheets,triggering the formation of petal-like units,and spatial confinement guides their non-planar assembly into rose-like assemblies with tunable dimensions from 1.0 to 10.2μm.Compared with 2D MXene,the resulting 3D MXene assemblies exhibit a 16.1-fold larger specific surface area and outstanding electrochemical performance,delivering gravimetric and areal capacitances of 895.9 F·g^(−1) and 4.3 F·cm^(−2) with a retention of 100%after 10,000 cycles,respectively.The MXene assemblies also exhibit excellent multifunctionality,achieving a solar evaporation rate of 1.9 kg·m−2·h−1 and a dye removal efficiency of 99.1%.Importantly,this strategy is universal across a range of MXenes,offering a scalable and versatile platform for constructing robust 3D architectures from MXene.
基金supported by the Ministry of Science and Technology of China(2022YFA1505900 and 2024YFB3814900)NSFC(22202073)Natural Science Foundation of Chongqing(CSTB2023NSCQ-MSXO159).
文摘Ultrasmall palladium nanoclusters have garnered significant attention due to their exceptional catalytic performance.However,their high surface energy always leads to aggregation,reducing the number of active sites and thereby decreasing catalytic efficiency.Herein,a molecular cage(RCC3)was utilized as a confined environment to stabilize ultrasmall PdNCs.The excellent solubility and open framework of cages not only enhance the solubility of palladium nanoclusters but also significantly improve their catalytic activity and stability.The prepared palladium nanoclusters were found to exhibit both peroxidase-like and oxidase-like activities.Under acidic conditions,the protonation of the molecular cage framework facilitates the assembly of ionic Pd nanoclusters with negatively charged enzymes through electrostatic interactions,forming a cascade system.The system is capable of detecting substrates,such as glucose and ascorbic acid,providing a highly catalytic platform for biosensing applications.
基金supported by the Natural Science Foundation of Guangxi Province(2021GXNSFBA220077,GUIKE AD23026050)National Natural Science Foundation of China(22102035 and 22162006)Innovation Project of Guangxi Graduate Education(XYCBZ2024021).
文摘Chemical functionalization of graphene is a topic of paramount importance to broaden its applications in chemistry,physics,and biological science but remains a great challenge due to its low chemical activity and poor dispersion.Here,we report a strategy for the photosynergetic electrochemical functionalization of graphene(EFG).By using chloride ion(Cl^(-))as the intercalation anions and co-reactants,the electrogenerated radicals confined in the expanded graphite layers enable efficient radical addition reaction,thus grasping crystallineperfect EFG.We found that the ultraviolet irradiation and applied voltage have increased the surface/interface concentration of Cl,thus boosting the functionalization of graphene.Theoretical calculation and experimental results verified the oxygen evolution reaction(OER)on EFG has been improved by regulating the doping of chlorine atoms.In addition,the reduced interlayer distance and enhanced electrostatic repulsion near the basal plane endow the fabricated EFG-based membrane with high salt retention.This work highlights a method for the in situ functionalization of graphene and the subsequent applications in OER and water desalination.
文摘Nanosized NaY crystals have been prepared from metakaolin and sodium silicate by confined space synthesis with starch additive. It is found that the product has a narrow crystal size distribution (50-100 nm), high Si/Al ratio (Si/Al=4.6-6.1), high surface area (1090 m2/g) and the average diameter of nanosized NaY (75 nm) synthesized is 30 nm, it is smaller than that of without starch additive.
基金the Central University Special Funding for Basic Scientific Research(Grant No.30918012201)the Foundation of JWKJW Field(Grant 2020-JCJQ-JJ-392)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX20_0315).
文摘In response to the demand for short-range detection of anti-smoke environment interference by laser fuzes,this study proposes a smoke environment simulation of non-uniform continuous point source diffusion and investigates an experimental laboratory smoke environment using an ammonium chloride smoke agent.The particle size distribution,composition,and mass flow distribution of the smoke were studied.Based on a discrete phase model and a kεturbulence model,a numerical simulation was developed to model the smoke generation and diffusion processes of the smoke agent in a confined space.The temporal and spatial distribution characteristics of the smoke mass concentration,velocity,and temperature in the space after smoke generation were analyzed,and the motion law governing the smoke diffusion throughout the entire space was summarized.Combined with the experimental verification of the smoke environment laboratory,the results showed that the smoke plume changed from fan-shaped to umbrella-shaped during smoke generation,and then continued to spread around.Meanwhile,the mass concentration of smoke in the space decreased from the middle outward;the changes in temperature and velocity were small and stable.In the diffusion stage(after 900 s),the mass concentration of smoke above 0.8 m was relatively uniform across an area of smoke that was 12 m thick.The concentration decreased over time,following a consistent decreasing trend,and the attenuation was negligible in a very short time.Therefore,this system was suitable for conducting experimental research on laser fuzes in a smoke environment.Owing to the stability of the equipment and facilities,the setup could reproduce the same experimental smoke environment by artificially controlling the smoke emission of the smoke agent.Overall,this work provides a theoretical reference for subsequent research efforts regarding the construction of uniform smoke environments and evaluating laser transmission characteristics in smoky environments.
基金Supported by the Eleventh Five-Year Plan of national support (2007BAI26B03-04)
文摘A miniature process for separating the oil phase from dilute oil/water emulsion is developed.This process applies a confined space apparatus,which is a thin flow channel made of two parallel plastic plates.The space between the two plates is rather narrow to improve the collisions between oil droplets and the plate surface.Oil droplets have an affinity for the plate surface and thus are captured,and then coalesce onto the surface.The droplet size distribution of the residual emulsion resulted from the separation process is remarkably changed.The oil layer on the plate weakens the further separation of oil droplets from the emulsion.Three types of plate materials,polypropylene(PP),polytetrafluoroethylene(PTFE) and nylon 66,were used.It is found that PP is the best in terms of the oil separation efficiency and nylon 66 is the poorest.The interaction between droplets in the emulsion and plate surface is indicated by the spreading coefficient of oil droplet on the plate in aqueous environment,and the influences of formed oil layer and plate material on the separation efficiency are discussed.
文摘One of the major hazards when working onboard Tankers is working in confined spaces, improving the procedures in working in such spaces is obvious, but developing the equipments used in rescue operation is rare to happen, that＇s why this paper is focusing on differentiating between the manual ＆ more developed equipments used specially in rescuing the crew in such an adequate time, to save the workers＇ life. The manual way is called ＂MUCKY CRANE＂ which is used for rescue purposes onboard tankers, in any of the confined spaces, should be replaced by excel crane which is air or hydraulic driven machine, to achieve better results. As safety precautions measures taken in such tasks are not enough for the required objective achievement. Such safety procedures have been discussed and critical situations have been pointed out.
基金support from the National Natural Science Foundation of China(Nos.52325309,22488101,22405040,and 62005027)the National Key R&D Program of China(No.2024YFA1509300)+1 种基金GBRCE for Functional Molecular Engineering and Institute of Green Chemistry and Molecular Engineering,the Gusu Innovation and Entrepreneurship Leading Talent Program(No.ZXL2024383)the Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province&Key Lab of Modern Optical Technologies of Ministry of Education,and the Natural Science Foundation of Jiangsu Province(No.BK20241267)。
文摘Molecular ferroelectrics,characterized by outstanding photoelectric and unique ferroelectric properties,invigorate the field of ferroelectric photovoltaics.Nonetheless,the performance of molecular ferroelectric devices is hindered by fine grains resulting from poor high-temperature stability.In this work,we successfully achieved micron-grained molecular ferroelectric films by using the space-confined vapor deposited method.The optimized film exhibited a significant increase in grain size from the nanometer level(0.08μm)to the micrometer level(~2μm),leading to improved optoelectronic and ferroelectricity.Furthermore,it optimizes the energy level and enhances the photovoltaic performance of vertical devices.Research on the mechanism shows that high annealing temperature and inhibiting component loss play an important role in obtaining large grain films.This work provides new research ideas for improving the quality of molecular ferroelectric films and provides valuable reference for the fabrication of high performance molecular ferroelectric photovoltaic devices.
基金Project supported by the Natural Science Foundation of Shandong Province of China for the Youth (Grant No. ZR2023QA102)。
文摘This study investigates the dynamical behaviors of nearest neighbor asymmetric coupled systems in a confined space.First, the study derivative analytical stability and synchronization conditions for the asymmetrically coupled system in an unconfined space, which are then validated through numerical simulations. Simulation results show that asymmetric coupling has a significant impact on synchronization conditions. Moreover, it is observed that irrespective of whether the system is confined, an increase in coupling asymmetry leads to a hastened synchronization pace. Additionally, the study examines the effects of boundaries on the system's collective behaviors via numerical experiments. The presence of boundaries ensures the system's stability and synchronization, and reducing these boundaries can expedite the synchronization process and amplify its effects. Finally, the study reveals that the system's output amplitude exhibits stochastic resonance as the confined boundary size increases.
基金supported by the National Natural Science Foundation of China (92471102, 52103305 and 52275206)the Sichuan Science and Technology Program (2023NSFSC0438)the Opening Project of Robotic Satellite Laboratory and the Sichuan University Interdisciplinary Innovation Fund。
文摘Researchers have been inspired by the movementand sensory abilities of animals in recent years due to theidea of soft robotics. This has resulted in the creation of biomimetic soft robots, which incorporate traits like biologicalvision and tactile sensation for use in manipulation, obstacleavoidance, and path planning. The miniaturization of softrobots has become a key area of research. However, their smallsize has limited their single locomotion capabilities, preventing true functional integration akin to that of biological systems.Inspired by the movement and electro-sensory abilitiesof insects in nature, this research developed a compact andlightweight (900 mg) electrothermal-driven (ETA) soft robotequipped with capacitive non-contact sensing. The electrothermalPE/CNT/PI composite film actuator exhibits excellentmechanical properties and flexibility, achieving a maximumbending angle of 320° and demonstrating a load capacity of atleast 5 times its own weight. The sensor component consists of0.2 mm diameter silver wire, which detects the proximity ofobjects through changes in the edge electric field. The signalresponse is highly sensitive and can effectively identify obstacles of various diameters. Compared to other reportedworks, this soft robot focuses on detecting the external environment,possessing the ability to sense obstacles in narrowspaces and dimly lit conditions. It also utilizes the generationof sensor signal changes during motion to obtain informationabout its own posture. This provides a new approach and basisfor future applications in complex environments.
基金Financial support from the Research Foundation-Flanders(FWO)(G0A3220N)KU Leuven-Internal Funds(grant no.C14/23/090)is acknowledged+1 种基金supported by FWO(grant nos.G0H2122N and GF9118N)and Fund for Scientific Research(F.R.S.-FNRS)under the Excellence of Science(EOS)program(projects 30489208 and 40007495)the China Scholarship Council(grant no.202006150018).
文摘Understandingmass transport within confined spaces is a key challenge with broad implications across numerous scientific and engineering disciplines.While studies on channel size effects and channel wall dynamics have deepened our knowledge of material transport,the combined analysis of both factors remains underexplored.This study reports on a fatty acid,heptanoic acid,that spontaneously intercalates into graphene/SiO_(2)in its gaseous state but is controllably intercalated in its liquid state through laser irradiation.Leveraging the diverse local properties of the system—such as the confined spaces between flexible graphene and atomically rough SiO_(2)—we employed time-course Raman spectroscopy to record and analyze multiple dynamic molecular intercalation processes.Through systematic analysis,we propose a model based on the dynamic changes of three key parameters:graphene doping,strain,and 2D-band intensity(I2D)during the liquid molecular intercalation process,derived from time-course Raman spectroscopy data.This model allows for the assessment of the impact of molecular intercalation in confined spaces and the quantification of intercalation efficiency.Additionally,we explore the mechanisms by which laser irradiation regulates molecular intercalation behavior.This study provides a foundation for understanding and optimizing molecular transport within graphene-based systems featuring confined spaces.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51902347,51822812,51772334,and 51778627)Natural Science Foundation of Hunan Province(No.2020JJ5741).
文摘Molybdenum disulfide (MoS_(2)) has received enormous attentions in the electrochemical energy storage due to its unique two-dimensional layered structure and relatively high reversible capacity. However, the application of MoS_(2) in potassium-ion batteries (PIBs) is restricted by poor rate capability and cyclability, which are associated with the sluggish reaction kinetics and the huge volume expansion during K+ intercalation. Herein, we propose a two-dimensional (2D) space confined strategy to construct van der Waals heterostructure for superior PIB anode, in which the MoS_(2) nanosheets can be well dispersed on reduced graphene oxide nanosheets by leveraging the confinement effect within the graphene layers and amorphous carbon. The strong synergistic effects in 2D van der Waals heterostructure can extremely promote the electron transportation and ions diffusion during K+ insertion/extraction. More significantly, the 2D space-confinement effect and van der Waals force inhibit polysulfide conversion product dissolution into the electrolyte, which significantly strengthens the structural durability during the long-term cycling process. As anticipated, the as-synthesized the “face-to-face” C/MoS_(2)/G anode delivers remarkable K-storage performance, especially for high reversible capacity (362.5 mAh·g^(-1) at 0.1 A·g^(-1)), excellent rate capability (195.4 mAh·g^(-1) at 10 Ag^(-1)) and superior ultrahigh-rate long-cycling stability (126.4 mAh·g^(-1) after 4000 cycles at high rate of 5 A·g^(-1)). This work presents a promise strategy of structure designing and composition optimization for 2D layered materials in advanced energy storage application.
基金financially supported by Major Program for Fundamental Research of Shanghai Science & Technology Commission(No.14JC1492700)the Fundamental Research Funds for the Central Universities(No.0500219216)
文摘Abstract The microlayer or nanolayer coextrusion of hundreds or thousands of alternating low density polyethylene （LDPE）/polystyrene （PS） microlayers or nanolayers were used to study the orientation of LDPE crystals in the confined quasi-two-dimensional or two-dimensional space. The clear and continuous layer structures from microscale to nanoscale can be found in SEM images. The morphology evolution of LDPE crystals in the confined microlayer or nanolayer can he varied from 3D spherulites, 2D spherulites, stacked edge-on lamellar, to single edge-on lamellar. Due to the orientation of the LDPE crystals, the tensile strength of the films increases obviously when the layer thickness reduces to nanoscale. The 2D small angle X-ray scattering （SAXS） patterns can reflect the average degree of orientation of LDPE in the confined layers. The stacking of LDPE lamellae is suppressed in interlamination and oppositely in parallel to the extrusion direction. The specific orientation function f can be calculated from the patterns. The infrared dichroism further confirms the mutation of the orientation of LDPE crystals from microscale to nanoscale in the confined space.
基金Supported by the National Natural Science Foundation of China(U22B2075).
文摘Aiming at the four issues of underground storage state,exploitation mechanism,crude oil flow and efficient recovery,the key theoretical and technical issues and countermeasures for effective development of Gulong shale oil are put forward.Through key exploration and research on fluid occurrence,fluid phase change,exploitation mechanism,oil start-up mechanism,flow regime/pattern,exploitation mode and enhanced oil recovery(EOR)of shale reservoirs with different storage spaces,multi-scale occurrence states of shale oil and phase behavior of fluid in nano confined space were provided,the multi-phase,multi-scale flow mode and production mechanism with hydraulic fracture-shale bedding fracture-matrix infiltration as the core was clarified,and a multi-scale flow mathematical model and recoverable reserves evaluation method were preliminarily established.The feasibility of development mode with early energy replenishment and recovery factor of 3o%was discussed.Based on these,the researches of key theories and technologies for effective development of Gulong shale oil are proposed to focus on:(1)in-situ sampling and non-destructive testing of core and fluid;(2)high-temperature,high-pressure,nano-scale laboratory simulation experiment;(3)fusion of multi-scale multi-flow regime numerical simulation technology and large-scale application software;(4)waterless(CO_(2))fracturing technique and the fracturing technique for increasing the vertical fracture height;(5)early energy replenishment to enhance oil recovery;(6)lifecycle technical and economic evaluation.Moreover,a series of exploitation tests should be performed on site as soon as possible to verify the theoretical understanding,optimize the exploitation mode,form supporting technologies,and provide a generalizable development model,thereby supporting and guiding the effective development and production of Gulong shale oil.
基金financially supported by the Natural Science Foundation of Hebei(Nos.B02020208088,H2020206514 and B2021208074)S&T Program of Hebei(Nos.20544401D,20314401D,206Z4406G,21314402D,22344402D,22373709D,22284601Z and 21344601D)Tianjin Science and Technology Project(No.19YFSLQY00070)。
文摘Herein,we successfully prepare highly dispersed and uniform small nano-size nickel nanoparticles embedded on core-shell carbon spheres by confined-deposition method.The mesoporous silica layer containing surfactant coated on the surface of the polymer sphere provides confined space and effectively controls the growth of nickel nanoparticles during pyrolysis.At the same time,the introduction of nickel species has an impact on structure of the obtained carbon spheres,and it can promote the deposition of carbon to realize the adjustment from hollow to core-shell and then to solid spheres.Owing to the uniform distribution of Ni nanoparticles with small size,mesoporous structure,N-doping groups,high specified surface areas,and core-shell structure,the obtained catalyst shows exciting ability for the production of CO by reduction of CO_(2)with a maximum CO Faradaic efficiency of 98%,indicating its promising prospect in electro-reduction of CO_(2).
