Large quadruped mammals,such as ruminants,have outstanding motion ability,including running and bounding.These advanced motion abilities are related to the buffer effect of their complicated musculoskeletal systems.Ho...Large quadruped mammals,such as ruminants,have outstanding motion ability,including running and bounding.These advanced motion abilities are related to the buffer effect of their complicated musculoskeletal systems.However,the buffer effect of most bio-robots is not satisfactory owing to the simple design of their buffer systems.In this paper,a physiological analysis of the ruminant musculoskeletal system is presented to explain the intrinsic buffer mechanism of motion.Based on the physical buffer parts of the ruminant limbs,the corresponding bionic mappings were determined.These mappings were used to guide the mechanism design of the robot multistage buffer system.The multistage buffer system includes two main buffer mechanisms:the first stage and the second stage.The buffer mechanism analysis of the first stage and multiple stages is discussed in theory to compare the effects between the normal single buffer system and the novel multistage buffer system.Then,the detailed mechanical structure of the limbs was designed based on the limb mechanism design.To further verify the superior efficacy of the multistage buffer system,the corresponding walking simulation experiments were conducted after the virtual prototype of a quadruped robot with a novel limb was built completely.Both theoretical analysis and simulation experiments prove that the bionic robot design with the novel multistage buffer system achieves better motion performance than the traditional robot buffer design and can be regarded as the design template of the robot limb.展开更多
Taking the MK7-3 of USA hydraulic buffer arresting device as the research subject,the dynamical model for the shipboard aircraft arresting system is established,and the magneto-rheological(MR) damper is applied to pul...Taking the MK7-3 of USA hydraulic buffer arresting device as the research subject,the dynamical model for the shipboard aircraft arresting system is established,and the magneto-rheological(MR) damper is applied to pulley shock absorbers for shipboard aircraft block system.Due to the effect of the MR damper has not been known completely and so far MR damper model has not been defined,we use a set of characteristic test of the MR damper,through the process of parameters identification,to establish the dynamical model for the MR damper based on the Bingham plastic model.Then,the fuzzy control rules are designed,the buffer control for the pulley buffer of shipboard aircrafts is completed in touchdown moment based on MR technology. Compared with blocking device of hydraulic pulley buffer in the same condition,the simulations results show that the proposed MR pulley buffer can effectively recognize the impact energy for shipboard block system and reduce the pull peak of arresting cable.It improves significantly safety during landing of the air vehicles and lowers the risk of accidents.展开更多
Redox homeostasis is crucial for cellular function,and its disruption is associated with numerous diseases and age-related pathologies.Superoxide(·O_(2)-),a key reactive oxygen species(ROS),functions as a crucial...Redox homeostasis is crucial for cellular function,and its disruption is associated with numerous diseases and age-related pathologies.Superoxide(·O_(2)-),a key reactive oxygen species(ROS),functions as a crucial signaling molecule under normal physiological processes;however,both its excessive accumulation and deficiency can lead to significant detrimental effects on organismal health.Inspired by the natural enzyme superoxide dismutase(SOD),which alleviates oxidative stress by neutralizing excess free radicals and modulates intracellular ROS levels to activate anti-aging pathways,we bioengineered a novel"superoxide buffering formulation"(SOD Buffer)to precisely regulate mitochondrial superoxide levels.Using C.elegans as a model,we show that SOD Buffer reduces superoxide accumulation under oxidative stress(e.g.,UV exposure)and restores superoxide levels under its depletion(e.g.,post-MitoQ treatment),without affecting general ROS level.Mechanistically,SOD Buffer modulates superoxide levels to activate the mitochondrial unfolded protein response(UPR^(mt)),evidenced by the increased HSP-6 expression.This activation is mediated by the transcription regulators ATFS-1 and DVE-1,which govern mitochondrial stress responses.Functionally,SOD Buffer extends average lifespan by 36.98% and improves aging-related behaviors in C.elegans in a UPR^(mt) dependent manner.These findings highlight the therapeutic promise of targeted superoxide modulation to maintain mitochondrial health and promote longevity.展开更多
Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision...Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision process is formulated as a Markov decision process(MDP)model to maximize the modularity.Corresponding key partitioning constraints on parallel restoration are considered.Second,based on the partitioning objective and constraints,the reward function of the partitioning MDP model is set by adopting a relative deviation normalization scheme to reduce mutual interference between the reward and penalty in the reward function.The soft bonus scaling mechanism is introduced to mitigate overestimation caused by abrupt jumps in the reward.Then,the deep Q network method is applied to solve the partitioning MDP model and generate partitioning schemes.Two experience replay buffers are employed to speed up the training process of the method.Finally,case studies on the IEEE 39-bus test system demonstrate that the proposed method can generate a high-modularity partitioning result that meets all key partitioning constraints,thereby improving the parallelism and reliability of the restoration process.Moreover,simulation results demonstrate that an appropriate discount factor is crucial for ensuring both the convergence speed and the stability of the partitioning training.展开更多
We propose an all-optical WDM buffer for optical packet switching system, which consists of NOLM and feedback loop. The proposed structure provides more than 40 turn buffering and nice output of buffered data when sel...We propose an all-optical WDM buffer for optical packet switching system, which consists of NOLM and feedback loop. The proposed structure provides more than 40 turn buffering and nice output of buffered data when selected by control signal.展开更多
Many rock avalanches were triggered by the Wenchuan earthquake on May 12, 2008 in southwest China. Protection galleries covered with a single soil layer are usually used to protect against rockfall. Since one-layer pr...Many rock avalanches were triggered by the Wenchuan earthquake on May 12, 2008 in southwest China. Protection galleries covered with a single soil layer are usually used to protect against rockfall. Since one-layer protection galleries do not have sufficient buffer capacity, a two-layered absorbing system has been designed. This study aims to find whether an expanded poly-styrol （EPS） cushion, which is used in the soil-covered protection galleries for shock absorption, could be positioned under dynamic loadings. The dynamic impacts of the two-layered absorbing system under the conditions of rock avalanches are numerically simulated through a 2D discrete dement method. By selecting reasonable parameters, a series of numerical experiments were conducted to find the best combination for the two- layered absorbing system. The values of the EPS layer area as a percentage of the total area were set as 0% （Sl）, 22~ （S2）, and 70% （$3）. 22~ of the area of the EPS layer was found to be a reasonable value, and experiments were conducted to find the best position of the EPS layer in the two-layered absorbing system. The numerical results yield useful conclusions regarding the interaction between the impacting avalanches and the two-layered absorbing system. The soil layer can absorb the shock energy effectively and S2 （0.4-m thick EPS cushion covered with soil layer） is the most efficient combination, which can reduce the impact force, compared with the other combinations.展开更多
In this study, the authors investigated the performance of different buffer layers through the electrical parameters such as J<sub>sc</sub>, V<sub>oc</sub>, QE and η of the quaternary system C...In this study, the authors investigated the performance of different buffer layers through the electrical parameters such as J<sub>sc</sub>, V<sub>oc</sub>, QE and η of the quaternary system Cu(In,Ga)Se<sub>2</sub> solar cells. The performance of Cu(In,Ga)Se<sub>2</sub>solar cells has been modeled and numerically simulated by using the SCAPS- 1D device simulation tool. The cells with a ZnSe, Zn(O,S) and (Zn,Mg)O buffer layers were compared with the reference CdS buffer layer. The investigation of ZnSe, Zn(O, S) and (Zn,Mg)O-based cells to substitute the traditional CdS in the future shows that the ZnSe-buffer layer is a potential material to replace CdS, which revealed the best efficiency of 20.76%, the other electrical parameters are: J<sub>SC</sub> = 34.6 mA/cm<sup>2</sup>, V<sub>OC</sub> = 0.76 V and FF = 79.6%. The losses as a function of the temperature are estimated at 0.1%/K, among all kinds of buffer layers studied. We have also shown that the use of a high band-gap buffer layer is necessary to obtain a better short-circuit current density J<sub>SC</sub>. From our results, we note that the chalcogenide solar cells with Zn-based alternative buffer layer have almost the same stability thatthe traditional CdS buffer layer solar cells have.展开更多
Different from traditional aggregation method, the unreliable buffers are originally considered and a more general aggregation method is offered, in which not only the unreliable buffers are considered, but also the p...Different from traditional aggregation method, the unreliable buffers are originally considered and a more general aggregation method is offered, in which not only the unreliable buffers are considered, but also the probabilities of system states are obtained by a discrete model rather than the continuous flow model of unreliable manufacturing systems. The solution technique is offered to get the system sate probabilities. The method advances the traditional system aggregation techniques. Numerical results specify the extended aggregation method and also show that the unreliable limited buffers have a strong impact on the efficiency of the production lines.展开更多
The principles of chemical equilibrium were used to derive a new set of formulae representing the oxygen potentials for five buffer gas mixtures at normal pressure.Various sorts of classical formulae for them are on- ...The principles of chemical equilibrium were used to derive a new set of formulae representing the oxygen potentials for five buffer gas mixtures at normal pressure.Various sorts of classical formulae for them are on- ly a particular representation under ignoring the effects of oxygen,thereby being unavailable for accurate cal- culation of oxygen potentials.In this paper,the oxygen potentials set by CO_2-H_2 gas mixtures and the mis- takes and errors of the classical expressions for them were discussed emphatically.The deviation in partial pressures of oxygen in some of previous experiments under the oxygen potentials controlled by CO_2-H_2 gas mixtures was explained quantitatively.The oxygen-potential diagrams predicting the equilibrated gas com- positions from the initial conditions have been also given.展开更多
The collision of ships poses a great threat to the piers in navigable waters.The kinetic energy of the moving ship can be consumed not only with the structural deformation,but also with tensile force from the proposed...The collision of ships poses a great threat to the piers in navigable waters.The kinetic energy of the moving ship can be consumed not only with the structural deformation,but also with tensile force from the proposed Floating Two-stage Buffer Collision-Prevention System(FTBCPS).The actual anti-collision effect of the current designed FTBCPS can be evaluated by the dynamic simulation.The construction method of 3D model is introduced,and the system initial state is defined.The transformation matrix and the basic kinematics vector are given,and the system basic dynamics equation is then created.The mechanical analysis on each component is carried out,and the detailed process of numerical simulation is also given.The simulation results indicate that collision direction and collision position have a great influence on the system kinematic response.Bridge pier faces the greatest threat when a ship hits the floater on the front beam in a nearly vertical direction,or on the side beam in a larger course angle.The study shows that the current designed FTBCPS can make full use of the fracture tensile property of polyester ropes and keep the tensile force acted on pier within its bearable range at the same time.The collision direction has a significant effect on the dynamic response of the colliding bodies,but no failure appeared in the simulations,which indicates that the current designed FTBCPS can protect bridge piers of all cases for the 5000-t ship with a velocity smaller than 5 m/s in navigable waters.展开更多
A new structure of optical buffer for resolving ATM cell contention is presented in this paper. It is composed of fiber delay lines, optical waveguide switching array and nonlinear semiconductor optical amplifier. Als...A new structure of optical buffer for resolving ATM cell contention is presented in this paper. It is composed of fiber delay lines, optical waveguide switching array and nonlinear semiconductor optical amplifier. Also, an experimental system for switching ATM cells formed by data at different transmission rates (up to 622MB/s) from different users is reported. The throughput of this system is 1.2Gb/s.展开更多
One of the major concepts of the geological disposal of high level radioactive waste is to enclose a metallic container with bentonite buffer which is considered to be impermeable and chemically stable. Since the aver...One of the major concepts of the geological disposal of high level radioactive waste is to enclose a metallic container with bentonite buffer which is considered to be impermeable and chemically stable. Since the average density of the container is around 6 to 7 and very heavy compared to bentonite, the scenario of container sinking has been evaluated because excess sinking makes short the pathway of nuclide migration in the bentonite and is detrimental to the safety of the disposal system. Previous considerations on container sinking have been made from the viewpoint of mechanical deformation of the bentonite. In this paper, a chemical deformation process is presented as another mechanism of container sinking, which has not been previously considered for the container sinking in the field of radioactive waste disposal. The chemical deformation mentioned in this paper is the deformation through the process of pressure solution of minerals constituting the buffer, transportation by diffusion and precipitation. That such chemical deformation is a ubiquitous phenomenon occurring in various scales in the crust of the earth will be shown through the review of previous works. Then, some future research topics will be suggested which would be required in order to evaluate the container sinking in the safety case for radioactive waste disposal.展开更多
Mobile edge computing (MEC) has a vital role in various delay-sensitive applications. With the increasing popularity of low-computing-capability Internet of Things (IoT) devices in industry 4.0 technology, MEC also fa...Mobile edge computing (MEC) has a vital role in various delay-sensitive applications. With the increasing popularity of low-computing-capability Internet of Things (IoT) devices in industry 4.0 technology, MEC also facilitates wireless power transfer, enhancing efficiency and sustainability for these devices. The most related studies concerning the computation rate in MEC are based on the coordinate descent method, the alternating direction method of multipliers (ADMMs) and Lyapunov optimization. Nevertheless, these studies do not consider the buffer queue size. This research work concerns the computation rate maximization for wireless-powered and multiple-user MEC systems, specifically focusing on the computation rate of end devices and managing the task buffer queue before computation at the terminal devices. A deep reinforcement learning (RL)-based task offloading algorithm is proposed to maximize the computation rate of end devices and minimizes the buffer queue size at the terminal devices.Precisely, considering the channel gain, the buffer queue size and wireless power transfer, it further formalizes the task offloading problem. The mode selection for task offloading is based on the individual channel gain, the buffer queue size and wireless power transfer maximization in a particular time slot.The central idea of this work is to explore the best optimal mode selection for IoT devices connected to the MEC system. The proposed algorithm optimizes computation delay by maximizing the computation rate of end devices and minimizing the buffer queue size before computation at the terminal devices. Then, the current study presents a deep RL-based task offloading algorithm to solve such a mixed-integer and non-convex optimization problem, aiming to get a better trade-off between the buffer queue size and the computation rate. The extensive simulation results reveal that the presented algorithm is much more efficient than the existing work to maintain a small buffer queue for terminal devices while simultaneously achieving a high-level computation rate.展开更多
An optimal design problem of local buffer allocation in the FMS is discussed in order to maximize a reward earned from processed jobs at all workstations. Structural properties of the optimal design problem are analyz...An optimal design problem of local buffer allocation in the FMS is discussed in order to maximize a reward earned from processed jobs at all workstations. Structural properties of the optimal design problem are analyzed for the model with two job routing policies. Based on these properties, approaches to optimal solutions are given.展开更多
The role of forest litter as an acid-base buffering system was assessed by litter from plantation and natural forests in South China. Samples were either extracted with acid solutions or titrated with acid or base sol...The role of forest litter as an acid-base buffering system was assessed by litter from plantation and natural forests in South China. Samples were either extracted with acid solutions or titrated with acid or base solutions. Litter was found to be a strong acid-base buffering system. Two legume species, Acacia mangium Willd and A. auriculaiformis A. Cunn, had very high litter pH values of around 6, which was 2 pH units higher than that of the soil where they grew. Litter of all other plantation species had litter pH of around 4, similar to that of the soil. Both legume species have high potential to neutralize soil acidity and the litter layer could act to shield soil against acid rain. The current stand of two legume species was estimated to be able to raise rain acidity by 0.1 to 0.4 pH units. Inorganic ions did not fully explain the pH pattern of different litter extracts, but high sodium and low nitrate partly accounted for the high pH of the two legume species. Some natural forest species had extremely low pH. As a whole, the litter of the natural climax forest was the driving force of soil acidification. Although plant residues are strong acid-base buffering system and able to adjust acidity of environment, only a few species can be expected to make soil more acid or alkaline through this mechanism since most species have litter pH values similar to those of soil where they grow.展开更多
Stochastic optical reconstruction microscopy(STORM),as a typical technique of single-molecule localization microscopy(SMLM),has overcome the diffraction limit by randomly switching fluorophores between fluorescent and...Stochastic optical reconstruction microscopy(STORM),as a typical technique of single-molecule localization microscopy(SMLM),has overcome the diffraction limit by randomly switching fluorophores between fluorescent and dark states,allowing for the precise localization of isolated emission patterns and the super-resolution reconstruction from millions of localized positions of single fluorophores.A critical factor influencing localization precision is the photo-switching behavior of fluorophores,which is affected by the imaging buffer.The imaging buffer typically comprises oxygen scavengers,photo-switching reagents,and refractive index regulators.Oxygen scavengers help prevent photobleaching,photo-switching reagents assist in facilitating the conversion of fluorophores,and refractive index regulators are used to adjust the refractive index of the solution.The synergistic interaction of these components promotes stable blinking of fluorophores,reduces irreversible photobleaching,and thereby ensures high-quality super-resolution imaging.This review provides a comprehensive overview of the essential compositions and functionalities of imaging buffers used in STORM,serving as a valuable resource for researchers seeking to select appropriate imaging buffers for their experiments.展开更多
Man-made superheavy elements(SHE)are produced as energetic recoils in complete-fusion reactions and need to be thermalized in a gas-filled chamber for chemical studies.The ever-shorter half-lives and decreasing produc...Man-made superheavy elements(SHE)are produced as energetic recoils in complete-fusion reactions and need to be thermalized in a gas-filled chamber for chemical studies.The ever-shorter half-lives and decreasing production rates of the elements beyond Fl(atomic number Z=114)-the heaviest element chemically studied today-require the development of novel techniques for quantitative thermalization and fast extraction efficiency.The Universal high-density gas stopping Cell(UniCell),currently under construction,was proposed to achieve this.Within this work,we propose an Ion Transfer by Gas Flow(ITGF)device,which serves as a UniCell ejector to interface with a gas chromatography detector array for chemical studies.Detailed parameter optimizations,using gas dynamics and Monte Carlo ion-trajectory simulations,promise fast(within a few ms)and highly efficient(up to 100%)ion extraction across a wide mass range.These ions can then be transmitted quantitatively through the ITGF into the high-pressure environment needed for further chemical studies.展开更多
The Casimir pressure plays an important role in the adhesion stability of nanofilms at submicro scales.In this work,the Casimir pressure of peptide films deposited on a layered substrate is investigated.Three types of...The Casimir pressure plays an important role in the adhesion stability of nanofilms at submicro scales.In this work,the Casimir pressure of peptide films deposited on a layered substrate is investigated.Three types of semi-infinite substrates,i.e.,silica,silicon and gold,are considered.The buffer layer between the peptide film and substrate consists of silicon or silica.The switching sign of the Casimir pressure can be controlled in a region ranging from about 130 nm to 1000 nm,depending on the thickness of the buffer layer and the substrate.The results suggest that the critical thickness of peptide films for Casimir equilibrium increases(or decreases)by increasing the thickness of the silicon(or silica)buffer film.The influences of wetting and electrolyte screening on the Casimir pressure are also investigated.Our finding provides a theoretical guide for the adhesion stability of peptide films in organic electronics.展开更多
The squeezing deformation of surrounding rock is an important factor restricting the safe construction and long-term operation of tunnels when a tunnel passes through soft strata with high ground stress.Under such sof...The squeezing deformation of surrounding rock is an important factor restricting the safe construction and long-term operation of tunnels when a tunnel passes through soft strata with high ground stress.Under such soft rock geological conditions,the large deformation of the surrounding rock can easily lead to the failure of supporting structures,including shotcrete cracks,spalling,and steel arch distortion.To improve the lining support performance during the large deformation of squeezed surrounding rock,this work selects aluminum foam with densities of 0.25 g/cm3,0.42 g/cm3 and 0.61 g/cm3 as the buffer layer material and carries out uniaxial confined compression tests.Through the evaluation and analysis of energy absorption and the comparison of the yield pressure of aluminum foam with those of other cushioning materials and yield pressure support systems,the strength,deformation and energy absorption of aluminum foam with a density of 0.25 g/cm3 meet the yield pressure performance requirements.The numerical model of the buffer layer yielding support system is then established via the finite element analysis software ABAQUS,and the influence of the buffer layer setting on the lining support is analyzed.Compared with the conventional support scheme,the addition of an aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining.The maximum and minimum principal stresses of the primary support are reduced by 13%and 15%,respectively.The maximum and minimum principal stresses of the secondary lining are reduced by 15%and 12%,respectively,and the displacement deformation of the secondary lining position is reduced by 15%.In summary,the application of aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining,improve the stress safety of the support and reduce the deformation of the support.展开更多
Photocatalytic hydrogen peroxide(H_(2)O_(2))production offers a sustainable route to convert water and oxygen into H_(2)O_(2)using solar energy.However,achieving long-term stability in photocatalysts remains a critica...Photocatalytic hydrogen peroxide(H_(2)O_(2))production offers a sustainable route to convert water and oxygen into H_(2)O_(2)using solar energy.However,achieving long-term stability in photocatalysts remains a critical challenge due to mismatched kinetics between oxygen reduction(ORR)and water oxidation(WOR),which leads to hole accumulation and oxidative degradation.Here,we report a redox-mediated strategy to address this bottleneck by designing a hydroquinone-embedded covalent organic framework(Tz-QH-COF)that enables reversible hole buffering and kinetic balance.The hydroquinone(QH)units act as dynamic hole reservoirs,capturing excess holes during ORR and converting to benzoquinone(Q),which is regenerated to QH via WOR,thereby preventing oxidative decomposition.This reversible QH/Q cycle,directly visualized through in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy,ensures unmatched stability,achieving continuous H_(2)O_(2) production for 528 h(22 d)with an accumulated yield of 18.6 mmol L^(–1)—the highest reported duration for organic photocatalysts.Density functional theory calculations reveal that the QH units exhibit a strong oxygen adsorption energy and favorable two-electron ORR/WOR pathways with low energy barriers.The synergy between experimental and theoretical insights elucidates a redox-mediated charge-balance mechanism,advancing the design of robust photocatalysts for solar-driven H_(2)O_(2) synthesis.展开更多
基金Supported by the National Key Research and Development Program of China(Grant No.2019YFB1309600)the National Natural Science Foundation of China(Grant Nos.51775011&91748201).
文摘Large quadruped mammals,such as ruminants,have outstanding motion ability,including running and bounding.These advanced motion abilities are related to the buffer effect of their complicated musculoskeletal systems.However,the buffer effect of most bio-robots is not satisfactory owing to the simple design of their buffer systems.In this paper,a physiological analysis of the ruminant musculoskeletal system is presented to explain the intrinsic buffer mechanism of motion.Based on the physical buffer parts of the ruminant limbs,the corresponding bionic mappings were determined.These mappings were used to guide the mechanism design of the robot multistage buffer system.The multistage buffer system includes two main buffer mechanisms:the first stage and the second stage.The buffer mechanism analysis of the first stage and multiple stages is discussed in theory to compare the effects between the normal single buffer system and the novel multistage buffer system.Then,the detailed mechanical structure of the limbs was designed based on the limb mechanism design.To further verify the superior efficacy of the multistage buffer system,the corresponding walking simulation experiments were conducted after the virtual prototype of a quadruped robot with a novel limb was built completely.Both theoretical analysis and simulation experiments prove that the bionic robot design with the novel multistage buffer system achieves better motion performance than the traditional robot buffer design and can be regarded as the design template of the robot limb.
基金the National Natural Science Foundation of China(No.61074090)the Program for Liaoning Excellent Talents in University(No.LR2011005)the Aviation Industry Corporation of China Innovation Funds(No.cxy2011SH)
文摘Taking the MK7-3 of USA hydraulic buffer arresting device as the research subject,the dynamical model for the shipboard aircraft arresting system is established,and the magneto-rheological(MR) damper is applied to pulley shock absorbers for shipboard aircraft block system.Due to the effect of the MR damper has not been known completely and so far MR damper model has not been defined,we use a set of characteristic test of the MR damper,through the process of parameters identification,to establish the dynamical model for the MR damper based on the Bingham plastic model.Then,the fuzzy control rules are designed,the buffer control for the pulley buffer of shipboard aircrafts is completed in touchdown moment based on MR technology. Compared with blocking device of hydraulic pulley buffer in the same condition,the simulations results show that the proposed MR pulley buffer can effectively recognize the impact energy for shipboard block system and reduce the pull peak of arresting cable.It improves significantly safety during landing of the air vehicles and lowers the risk of accidents.
基金supported by the National Key R&D Program of China(No.2022YFA1205801)the National Natural Science Foundation of China(Nos.T2225026 and 82172087)+1 种基金the Beijing Institute of Technology Research Fund Program for Young Scholars,Innovative Group Cultivation Project for Basic Medicine(No.CX25XT03)Laboratory for Clinical Medicine,Capital Medical University.
文摘Redox homeostasis is crucial for cellular function,and its disruption is associated with numerous diseases and age-related pathologies.Superoxide(·O_(2)-),a key reactive oxygen species(ROS),functions as a crucial signaling molecule under normal physiological processes;however,both its excessive accumulation and deficiency can lead to significant detrimental effects on organismal health.Inspired by the natural enzyme superoxide dismutase(SOD),which alleviates oxidative stress by neutralizing excess free radicals and modulates intracellular ROS levels to activate anti-aging pathways,we bioengineered a novel"superoxide buffering formulation"(SOD Buffer)to precisely regulate mitochondrial superoxide levels.Using C.elegans as a model,we show that SOD Buffer reduces superoxide accumulation under oxidative stress(e.g.,UV exposure)and restores superoxide levels under its depletion(e.g.,post-MitoQ treatment),without affecting general ROS level.Mechanistically,SOD Buffer modulates superoxide levels to activate the mitochondrial unfolded protein response(UPR^(mt)),evidenced by the increased HSP-6 expression.This activation is mediated by the transcription regulators ATFS-1 and DVE-1,which govern mitochondrial stress responses.Functionally,SOD Buffer extends average lifespan by 36.98% and improves aging-related behaviors in C.elegans in a UPR^(mt) dependent manner.These findings highlight the therapeutic promise of targeted superoxide modulation to maintain mitochondrial health and promote longevity.
基金funded by the Beijing Engineering Research Center of Electric Rail Transportation.
文摘Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision process is formulated as a Markov decision process(MDP)model to maximize the modularity.Corresponding key partitioning constraints on parallel restoration are considered.Second,based on the partitioning objective and constraints,the reward function of the partitioning MDP model is set by adopting a relative deviation normalization scheme to reduce mutual interference between the reward and penalty in the reward function.The soft bonus scaling mechanism is introduced to mitigate overestimation caused by abrupt jumps in the reward.Then,the deep Q network method is applied to solve the partitioning MDP model and generate partitioning schemes.Two experience replay buffers are employed to speed up the training process of the method.Finally,case studies on the IEEE 39-bus test system demonstrate that the proposed method can generate a high-modularity partitioning result that meets all key partitioning constraints,thereby improving the parallelism and reliability of the restoration process.Moreover,simulation results demonstrate that an appropriate discount factor is crucial for ensuring both the convergence speed and the stability of the partitioning training.
文摘We propose an all-optical WDM buffer for optical packet switching system, which consists of NOLM and feedback loop. The proposed structure provides more than 40 turn buffering and nice output of buffered data when selected by control signal.
基金financial support from the Project of National Science Foundation of China(Grant No.41272346)the National Outstanding Youth Funds(Grant No.41225011)+2 种基金financial support from the Science & Technology Research Plan of China Railway Eryuan Engineering Group CO.LTD (Grant No.13164196(13-15))the Project of National Science Foundation of China(Grant Nos. 41472293,91430105)"hundred talents" program of CAS
文摘Many rock avalanches were triggered by the Wenchuan earthquake on May 12, 2008 in southwest China. Protection galleries covered with a single soil layer are usually used to protect against rockfall. Since one-layer protection galleries do not have sufficient buffer capacity, a two-layered absorbing system has been designed. This study aims to find whether an expanded poly-styrol （EPS） cushion, which is used in the soil-covered protection galleries for shock absorption, could be positioned under dynamic loadings. The dynamic impacts of the two-layered absorbing system under the conditions of rock avalanches are numerically simulated through a 2D discrete dement method. By selecting reasonable parameters, a series of numerical experiments were conducted to find the best combination for the two- layered absorbing system. The values of the EPS layer area as a percentage of the total area were set as 0% （Sl）, 22~ （S2）, and 70% （$3）. 22~ of the area of the EPS layer was found to be a reasonable value, and experiments were conducted to find the best position of the EPS layer in the two-layered absorbing system. The numerical results yield useful conclusions regarding the interaction between the impacting avalanches and the two-layered absorbing system. The soil layer can absorb the shock energy effectively and S2 （0.4-m thick EPS cushion covered with soil layer） is the most efficient combination, which can reduce the impact force, compared with the other combinations.
文摘In this study, the authors investigated the performance of different buffer layers through the electrical parameters such as J<sub>sc</sub>, V<sub>oc</sub>, QE and η of the quaternary system Cu(In,Ga)Se<sub>2</sub> solar cells. The performance of Cu(In,Ga)Se<sub>2</sub>solar cells has been modeled and numerically simulated by using the SCAPS- 1D device simulation tool. The cells with a ZnSe, Zn(O,S) and (Zn,Mg)O buffer layers were compared with the reference CdS buffer layer. The investigation of ZnSe, Zn(O, S) and (Zn,Mg)O-based cells to substitute the traditional CdS in the future shows that the ZnSe-buffer layer is a potential material to replace CdS, which revealed the best efficiency of 20.76%, the other electrical parameters are: J<sub>SC</sub> = 34.6 mA/cm<sup>2</sup>, V<sub>OC</sub> = 0.76 V and FF = 79.6%. The losses as a function of the temperature are estimated at 0.1%/K, among all kinds of buffer layers studied. We have also shown that the use of a high band-gap buffer layer is necessary to obtain a better short-circuit current density J<sub>SC</sub>. From our results, we note that the chalcogenide solar cells with Zn-based alternative buffer layer have almost the same stability thatthe traditional CdS buffer layer solar cells have.
基金Great Technology Innovation of Gansu Province,China (No.2GS063-A52-005-01)Natural Science Foundation of Gansu Province,China (No.3ZS062-B25-034)Research Item of Education Department of Gansu Province,China (No.0703-06)
文摘Different from traditional aggregation method, the unreliable buffers are originally considered and a more general aggregation method is offered, in which not only the unreliable buffers are considered, but also the probabilities of system states are obtained by a discrete model rather than the continuous flow model of unreliable manufacturing systems. The solution technique is offered to get the system sate probabilities. The method advances the traditional system aggregation techniques. Numerical results specify the extended aggregation method and also show that the unreliable limited buffers have a strong impact on the efficiency of the production lines.
文摘The principles of chemical equilibrium were used to derive a new set of formulae representing the oxygen potentials for five buffer gas mixtures at normal pressure.Various sorts of classical formulae for them are on- ly a particular representation under ignoring the effects of oxygen,thereby being unavailable for accurate cal- culation of oxygen potentials.In this paper,the oxygen potentials set by CO_2-H_2 gas mixtures and the mis- takes and errors of the classical expressions for them were discussed emphatically.The deviation in partial pressures of oxygen in some of previous experiments under the oxygen potentials controlled by CO_2-H_2 gas mixtures was explained quantitatively.The oxygen-potential diagrams predicting the equilibrated gas com- positions from the initial conditions have been also given.
基金financially supported by the National Natural Science Foundation of China(Grant No.51679250)the High-Tech Ship Research Projects Sponsored by Chinese Ministry of Industry and Information Technology(Grant No.[2019-357]).
文摘The collision of ships poses a great threat to the piers in navigable waters.The kinetic energy of the moving ship can be consumed not only with the structural deformation,but also with tensile force from the proposed Floating Two-stage Buffer Collision-Prevention System(FTBCPS).The actual anti-collision effect of the current designed FTBCPS can be evaluated by the dynamic simulation.The construction method of 3D model is introduced,and the system initial state is defined.The transformation matrix and the basic kinematics vector are given,and the system basic dynamics equation is then created.The mechanical analysis on each component is carried out,and the detailed process of numerical simulation is also given.The simulation results indicate that collision direction and collision position have a great influence on the system kinematic response.Bridge pier faces the greatest threat when a ship hits the floater on the front beam in a nearly vertical direction,or on the side beam in a larger course angle.The study shows that the current designed FTBCPS can make full use of the fracture tensile property of polyester ropes and keep the tensile force acted on pier within its bearable range at the same time.The collision direction has a significant effect on the dynamic response of the colliding bodies,but no failure appeared in the simulations,which indicates that the current designed FTBCPS can protect bridge piers of all cases for the 5000-t ship with a velocity smaller than 5 m/s in navigable waters.
基金the High Technology Research and Development Programme of China
文摘A new structure of optical buffer for resolving ATM cell contention is presented in this paper. It is composed of fiber delay lines, optical waveguide switching array and nonlinear semiconductor optical amplifier. Also, an experimental system for switching ATM cells formed by data at different transmission rates (up to 622MB/s) from different users is reported. The throughput of this system is 1.2Gb/s.
文摘One of the major concepts of the geological disposal of high level radioactive waste is to enclose a metallic container with bentonite buffer which is considered to be impermeable and chemically stable. Since the average density of the container is around 6 to 7 and very heavy compared to bentonite, the scenario of container sinking has been evaluated because excess sinking makes short the pathway of nuclide migration in the bentonite and is detrimental to the safety of the disposal system. Previous considerations on container sinking have been made from the viewpoint of mechanical deformation of the bentonite. In this paper, a chemical deformation process is presented as another mechanism of container sinking, which has not been previously considered for the container sinking in the field of radioactive waste disposal. The chemical deformation mentioned in this paper is the deformation through the process of pressure solution of minerals constituting the buffer, transportation by diffusion and precipitation. That such chemical deformation is a ubiquitous phenomenon occurring in various scales in the crust of the earth will be shown through the review of previous works. Then, some future research topics will be suggested which would be required in order to evaluate the container sinking in the safety case for radioactive waste disposal.
基金National Natural Science Foundation of China(No.61902060)Shanghai Sailing Program,China(No.19YF1402100)+1 种基金Fundamental Research Funds for the Central Universities,China(No.2232019D3-51)Open Foundation of State Key Laboratory of Networking and Switching Technology(Beijing University of Posts and Telecommunications,China)(No.SKLNST-2021-1-06)。
文摘Mobile edge computing (MEC) has a vital role in various delay-sensitive applications. With the increasing popularity of low-computing-capability Internet of Things (IoT) devices in industry 4.0 technology, MEC also facilitates wireless power transfer, enhancing efficiency and sustainability for these devices. The most related studies concerning the computation rate in MEC are based on the coordinate descent method, the alternating direction method of multipliers (ADMMs) and Lyapunov optimization. Nevertheless, these studies do not consider the buffer queue size. This research work concerns the computation rate maximization for wireless-powered and multiple-user MEC systems, specifically focusing on the computation rate of end devices and managing the task buffer queue before computation at the terminal devices. A deep reinforcement learning (RL)-based task offloading algorithm is proposed to maximize the computation rate of end devices and minimizes the buffer queue size at the terminal devices.Precisely, considering the channel gain, the buffer queue size and wireless power transfer, it further formalizes the task offloading problem. The mode selection for task offloading is based on the individual channel gain, the buffer queue size and wireless power transfer maximization in a particular time slot.The central idea of this work is to explore the best optimal mode selection for IoT devices connected to the MEC system. The proposed algorithm optimizes computation delay by maximizing the computation rate of end devices and minimizing the buffer queue size before computation at the terminal devices. Then, the current study presents a deep RL-based task offloading algorithm to solve such a mixed-integer and non-convex optimization problem, aiming to get a better trade-off between the buffer queue size and the computation rate. The extensive simulation results reveal that the presented algorithm is much more efficient than the existing work to maintain a small buffer queue for terminal devices while simultaneously achieving a high-level computation rate.
文摘An optimal design problem of local buffer allocation in the FMS is discussed in order to maximize a reward earned from processed jobs at all workstations. Structural properties of the optimal design problem are analyzed for the model with two job routing policies. Based on these properties, approaches to optimal solutions are given.
文摘The role of forest litter as an acid-base buffering system was assessed by litter from plantation and natural forests in South China. Samples were either extracted with acid solutions or titrated with acid or base solutions. Litter was found to be a strong acid-base buffering system. Two legume species, Acacia mangium Willd and A. auriculaiformis A. Cunn, had very high litter pH values of around 6, which was 2 pH units higher than that of the soil where they grew. Litter of all other plantation species had litter pH of around 4, similar to that of the soil. Both legume species have high potential to neutralize soil acidity and the litter layer could act to shield soil against acid rain. The current stand of two legume species was estimated to be able to raise rain acidity by 0.1 to 0.4 pH units. Inorganic ions did not fully explain the pH pattern of different litter extracts, but high sodium and low nitrate partly accounted for the high pH of the two legume species. Some natural forest species had extremely low pH. As a whole, the litter of the natural climax forest was the driving force of soil acidification. Although plant residues are strong acid-base buffering system and able to adjust acidity of environment, only a few species can be expected to make soil more acid or alkaline through this mechanism since most species have litter pH values similar to those of soil where they grow.
基金funded by the National Natural Science Foundation of China(No.62305041)the Natural Science Foundation of Liaoning Province(No.2023-MS-103)。
文摘Stochastic optical reconstruction microscopy(STORM),as a typical technique of single-molecule localization microscopy(SMLM),has overcome the diffraction limit by randomly switching fluorophores between fluorescent and dark states,allowing for the precise localization of isolated emission patterns and the super-resolution reconstruction from millions of localized positions of single fluorophores.A critical factor influencing localization precision is the photo-switching behavior of fluorophores,which is affected by the imaging buffer.The imaging buffer typically comprises oxygen scavengers,photo-switching reagents,and refractive index regulators.Oxygen scavengers help prevent photobleaching,photo-switching reagents assist in facilitating the conversion of fluorophores,and refractive index regulators are used to adjust the refractive index of the solution.The synergistic interaction of these components promotes stable blinking of fluorophores,reduces irreversible photobleaching,and thereby ensures high-quality super-resolution imaging.This review provides a comprehensive overview of the essential compositions and functionalities of imaging buffers used in STORM,serving as a valuable resource for researchers seeking to select appropriate imaging buffers for their experiments.
基金This work was supported by the German BMBF (No.05P21UMFN2)
文摘Man-made superheavy elements(SHE)are produced as energetic recoils in complete-fusion reactions and need to be thermalized in a gas-filled chamber for chemical studies.The ever-shorter half-lives and decreasing production rates of the elements beyond Fl(atomic number Z=114)-the heaviest element chemically studied today-require the development of novel techniques for quantitative thermalization and fast extraction efficiency.The Universal high-density gas stopping Cell(UniCell),currently under construction,was proposed to achieve this.Within this work,we propose an Ion Transfer by Gas Flow(ITGF)device,which serves as a UniCell ejector to interface with a gas chromatography detector array for chemical studies.Detailed parameter optimizations,using gas dynamics and Monte Carlo ion-trajectory simulations,promise fast(within a few ms)and highly efficient(up to 100%)ion extraction across a wide mass range.These ions can then be transmitted quantitatively through the ITGF into the high-pressure environment needed for further chemical studies.
基金supported by the National Natural Science Foundation of China(Grant No.11804288)the Natural Science Foundation of Henan(Grant No.232300420120)。
文摘The Casimir pressure plays an important role in the adhesion stability of nanofilms at submicro scales.In this work,the Casimir pressure of peptide films deposited on a layered substrate is investigated.Three types of semi-infinite substrates,i.e.,silica,silicon and gold,are considered.The buffer layer between the peptide film and substrate consists of silicon or silica.The switching sign of the Casimir pressure can be controlled in a region ranging from about 130 nm to 1000 nm,depending on the thickness of the buffer layer and the substrate.The results suggest that the critical thickness of peptide films for Casimir equilibrium increases(or decreases)by increasing the thickness of the silicon(or silica)buffer film.The influences of wetting and electrolyte screening on the Casimir pressure are also investigated.Our finding provides a theoretical guide for the adhesion stability of peptide films in organic electronics.
基金the support of the National Natural Science Foundation of China(Grant No.42207199)Scientific Research Project of Education of Zhejiang Province(No.Y202351343)+1 种基金Zhejiang Postdoctoral Scientific Research Project(Grant Nos.ZJ2022155,ZJ2022156)Zhejiang Province International Science and Technology Cooperation Base Open Fund Project(IBGDP-2023-01)。
文摘The squeezing deformation of surrounding rock is an important factor restricting the safe construction and long-term operation of tunnels when a tunnel passes through soft strata with high ground stress.Under such soft rock geological conditions,the large deformation of the surrounding rock can easily lead to the failure of supporting structures,including shotcrete cracks,spalling,and steel arch distortion.To improve the lining support performance during the large deformation of squeezed surrounding rock,this work selects aluminum foam with densities of 0.25 g/cm3,0.42 g/cm3 and 0.61 g/cm3 as the buffer layer material and carries out uniaxial confined compression tests.Through the evaluation and analysis of energy absorption and the comparison of the yield pressure of aluminum foam with those of other cushioning materials and yield pressure support systems,the strength,deformation and energy absorption of aluminum foam with a density of 0.25 g/cm3 meet the yield pressure performance requirements.The numerical model of the buffer layer yielding support system is then established via the finite element analysis software ABAQUS,and the influence of the buffer layer setting on the lining support is analyzed.Compared with the conventional support scheme,the addition of an aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining.The maximum and minimum principal stresses of the primary support are reduced by 13%and 15%,respectively.The maximum and minimum principal stresses of the secondary lining are reduced by 15%and 12%,respectively,and the displacement deformation of the secondary lining position is reduced by 15%.In summary,the application of aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining,improve the stress safety of the support and reduce the deformation of the support.
文摘Photocatalytic hydrogen peroxide(H_(2)O_(2))production offers a sustainable route to convert water and oxygen into H_(2)O_(2)using solar energy.However,achieving long-term stability in photocatalysts remains a critical challenge due to mismatched kinetics between oxygen reduction(ORR)and water oxidation(WOR),which leads to hole accumulation and oxidative degradation.Here,we report a redox-mediated strategy to address this bottleneck by designing a hydroquinone-embedded covalent organic framework(Tz-QH-COF)that enables reversible hole buffering and kinetic balance.The hydroquinone(QH)units act as dynamic hole reservoirs,capturing excess holes during ORR and converting to benzoquinone(Q),which is regenerated to QH via WOR,thereby preventing oxidative decomposition.This reversible QH/Q cycle,directly visualized through in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy,ensures unmatched stability,achieving continuous H_(2)O_(2) production for 528 h(22 d)with an accumulated yield of 18.6 mmol L^(–1)—the highest reported duration for organic photocatalysts.Density functional theory calculations reveal that the QH units exhibit a strong oxygen adsorption energy and favorable two-electron ORR/WOR pathways with low energy barriers.The synergy between experimental and theoretical insights elucidates a redox-mediated charge-balance mechanism,advancing the design of robust photocatalysts for solar-driven H_(2)O_(2) synthesis.
