The extended Brinkman Darcy model for momentum equations and an energy equation is used to calculate the unsteady natural convection Couette flow of a viscous incompressible heat generating/absorbing fluid in a vertic...The extended Brinkman Darcy model for momentum equations and an energy equation is used to calculate the unsteady natural convection Couette flow of a viscous incompressible heat generating/absorbing fluid in a vertical channel （formed by two infinite vertical and parallel plates） filled with the fluid-saturated porous medium. The flow is triggered by the asymmetric heating and the accelerated motion of one of the bounding plates. The governing equations are simplified by the reasonable dimensionless parameters and solved analytically by the Laplace transform techniques to obtain the closed form solutions of the velocity and temperature profiles. Then, the skin friction and the rate of heat transfer are consequently derived. It is noticed that, at different sections within the vertical channel, the fluid flow and the temperature profiles increase with time, which are both higher near the moving plate. In particular, increasing the gap between the plates increases the velocity and the temperature of the fluid, however, reduces the skin friction and the rate of heat transfer.展开更多
This study considers a theoretical analysis of natural convection flow of heat generating/absorbing fluid near an infinite vertical plate with ramped temperature. It is assumed that the bounding plate has a ramped tem...This study considers a theoretical analysis of natural convection flow of heat generating/absorbing fluid near an infinite vertical plate with ramped temperature. It is assumed that the bounding plate has a ramped temperature profile. Exact solutions of energy and momentum equations are obtained using the Laplacetransform techniques. Solutions are obtained for different values of the Prandtl number (Pr) and the heat sink parameter (S). Results of the ramped and isothermal temperature and velocity as well as Nusselt number and skin friction have been compared and presented with the help of graphs.展开更多
In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not ...In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.展开更多
Neuroinflammation is associated with Parkinson’s disease:Reactive gliosis and neuroinflammation are hallmarks of Parkinson’s disease(PD),a multisystem neurodegenerative disorder characterized by a progressive loss o...Neuroinflammation is associated with Parkinson’s disease:Reactive gliosis and neuroinflammation are hallmarks of Parkinson’s disease(PD),a multisystem neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons.Neuroinflammation has long been considered a mere consequence of neuronal loss,but whether it promotes PD or is a key player in disease progression remains to be determined.Human leukocyte antigen.展开更多
This study presents a comparative analysis of a complex SQL benchmark, TPC-DS, with two existing text-to-SQL benchmarks, BIRD and Spider. Our findings reveal that TPC-DS queries exhibit a significantly higher level of...This study presents a comparative analysis of a complex SQL benchmark, TPC-DS, with two existing text-to-SQL benchmarks, BIRD and Spider. Our findings reveal that TPC-DS queries exhibit a significantly higher level of structural complexity compared to the other two benchmarks. This underscores the need for more intricate benchmarks to simulate realistic scenarios effectively. To facilitate this comparison, we devised several measures of structural complexity and applied them across all three benchmarks. The results of this study can guide future research in the development of more sophisticated text-to-SQL benchmarks. We utilized 11 distinct Language Models (LLMs) to generate SQL queries based on the query descriptions provided by the TPC-DS benchmark. The prompt engineering process incorporated both the query description as outlined in the TPC-DS specification and the database schema of TPC-DS. Our findings indicate that the current state-of-the-art generative AI models fall short in generating accurate decision-making queries. We conducted a comparison of the generated queries with the TPC-DS gold standard queries using a series of fuzzy structure matching techniques based on query features. The results demonstrated that the accuracy of the generated queries is insufficient for practical real-world application.展开更多
In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As...In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As has been used in solidstate and fiber lasers as a mode-locker.However,the pulse widths that have been reported in the searchable published literature are all long and the shortest is tens of picoseconds.Femtosecond pulse widths,desired for a variety of applications,have not yet been reported in Ga As-based pulsed lasers.In this work,we further explore the nonlinear characteristics of Ga As that has been magnetron sputtered onto the surface of a tapered fiber and its application in the generation of femtosecond lasing via effective dispersion optimization and nonlinearity management.With the enhanced interaction between evanescent waves and Ga As nanosheets,mode-locked soliton pulses as short as 830 fs are generated at repetition rates of 4.64 MHz.As far as we know,this is the first time that femtosecond-level pulses have been generated with a Ga As-based saturable absorber.In addition,soliton molecules,including in the dual-pulse state,are also realized under stronger pumping.This work demonstrates that Ga As-based photonic devices have good application prospects in effective polymorphous ultrashort pulsed laser generation.展开更多
The dielectric loss of carbon materials is closely related to the microstructure and the degree of crystallization,and the microstructure modulation of electromagnetic wave absorbing carbon materials is the key to enh...The dielectric loss of carbon materials is closely related to the microstructure and the degree of crystallization,and the microstructure modulation of electromagnetic wave absorbing carbon materials is the key to enhancing absorption properties.In this work,a porous elastic Co@CNF-PDMS composite was prepared by freeze-drying and confined catalysis.The graphitization degree and conductivity loss of carbon nanofibers(CNFs)were regulated by heat treatment temperature and Co catalyst content.The construction of a heterointerface between Co and C enhances the interfacial polarization loss.The Co@CNF-PDMS composite with 4.5 mm achieves the minimum reflection loss(RLmin)of-81.0 dB at 9.9 GHz and RL no higher than-12.1 dB in the whole of the X-band.After applying a load of up to 40% strain and 100 cycles to Co@CNF-PDMS,the dielectric properties of the composite remain stable.With the increase of compression strain,the distribution density of the absorbent increases,and the CNF sheet layer extrusion contact forms a conductive path,which leads to the conductive loss increase,finally,the absorption band moves to a high frequency.The absorption band can be bi-directionally regulated by loading and strain with good stability,which provides a new strategy for the development of intelligent electromagnetic wave absorbing materials.展开更多
In geotechnical engineering,rock bolts are commonly used for reinforcement,while the surrounding rock mass bears varying degrees of shear loads.The shear rate affects the stability of bolted rock joints,especially in ...In geotechnical engineering,rock bolts are commonly used for reinforcement,while the surrounding rock mass bears varying degrees of shear loads.The shear rate affects the stability of bolted rock joints,especially in projects susceptible to dynamic shear loads.In laboratory experiments,fully-grouted bolts and energy-absorbing bolts were used as research objects,and artificial rock specimens with rough joints were fabricated to analyze the shear characteristics and damage mechanisms of bolted rock joints under cyclic shear conditions and different shear velocities.The results showed that as the shear rate increased,the shear strength of bolted rock joint specimens decreased.Degradation of asperities resulted in no obvious peak shear stress in the specimens.Energy-absorbing bolts exhibited greater deformation capacity,with significant necking phenomena and the ability to withstand larger shear displacements.In contrast,fully-grouted bolts,which have threaded surfaces that provide higher bonding performance,exhibited a reduced capacity for plastic deformation and were prone to breaking under smaller shear displacements.Although the shear stiffness of specimens reinforced by energy-absorbing bolts was slightly lower than that of fully-grouted bolt specimens,they demonstrated greater stability under various shear rates.The absorbed shear energy showed that energy-absorbing bolts had superior coordinated deformation capabilities,thus exhibiting greater absorbed shear energy than fully-grouted bolts.Overall,fully-grouted bolts are more suitable for projects requiring higher rock shear strength and overall stiffness.In contrast,energy-absorbing bolts are more suitable for coping with dynamic or fluctuating load conditions to maintain the relative stability of jointed rock masses.展开更多
Two dimensional(2D) materials based on boron and carbon have attracted wide attention due to their unique properties. BC compounds have rich active sites and diverse chemical coordination, showing great potential in o...Two dimensional(2D) materials based on boron and carbon have attracted wide attention due to their unique properties. BC compounds have rich active sites and diverse chemical coordination, showing great potential in optoelectronic applications. However, due to the limitation of calculation and experimental conditions, it is still a challenging task to predict new 2D BC monolayer materials. Specifically, we utilized Crystal Diffusion Variational Autoencoder(CDVAE) and pre-trained Materials Graph Neural Network with 3-Body Interactions(M3GNet) model to generate novel and stable BCP materials. Each crystal structure was treated as a high-dimensional vector, where the encoder extracted lattice information and element coordinates, mapping the high-dimensional data into a low-dimensional latent space. The decoder then reconstructed the latent representation back into the original data space. Additionally, our designed attribute predictor network combined the advantages of dilated convolutions and residual connections,effectively increasing the model's receptive field and learning capacity while maintaining relatively low parameter count and computational complexity. By progressively increasing the dilation rate, the model can capture features at different scales. We used the DFT data set of about 1600 BCP monolayer materials to train the diffusion model, and combined with the pre-trained M3GNet model to screen the best candidate structure. Finally, we used DFT calculations to confirm the stability of the candidate structure.The results show that the combination of generative deep learning model and attribute prediction model can help accelerate the discovery and research of new 2D materials, and provide effective methods for exploring the inverse design of new two-dimensional materials.展开更多
In this work,a novel microwave absorbing material(MAM)made of a pseudo-binary of Sr_(2)TiMoO_(6)-Al_(2)O_(3)(STM)is proposed first.The MAMs labeled as STM X(X=60,70,80 and 100,respectively),in which X is the initial w...In this work,a novel microwave absorbing material(MAM)made of a pseudo-binary of Sr_(2)TiMoO_(6)-Al_(2)O_(3)(STM)is proposed first.The MAMs labeled as STM X(X=60,70,80 and 100,respectively),in which X is the initial weight percent of Sr_(2)TiMoO_(6),were synthesized using the solid-state reaction method.Compared with STM100,some equilibrium phases,including SrTiO_(3),Mo,Sr_(8)(Al1_(2)O_(24))(MoO_(4))_(2)and a few undefined ones,are presented in the composites as evidenced by X-ray diffraction results and scanning electron microscopy due to the chemical reaction between Sr_(2)TiMoO_(6)and Al_(2)O_(3)component.Besides conductance loss,heterogeneous interfaces between various equilibrium phases introduce interfacial polarization,which causes an enhancement of dissipation for the incident electromagnetic wave.Among the synthesized samples,STM80 presents the best microwave absorbing properties.It has a minimum reflection loss(RLmin)of-26 dB and an effective absorbing bandwidth up to 2.7 GHz when the thickness is only 1 mm.This indicates that STM80 is a new type of microwave absorbing material with strong absorption and ultrathin thickness.展开更多
Concentrated solar thermal power generation has been experimentally tested in advanced countries for a period of time.This paper demonstrates how this technology can be improved by using water molecules as a medium to...Concentrated solar thermal power generation has been experimentally tested in advanced countries for a period of time.This paper demonstrates how this technology can be improved by using water molecules as a medium to drive traditional generator sets for energy conversion,thereby simultaneously improving the energy conversion rate.Additionally,a novel contribution is made by incorporating a magic number 4 to enhance the focusing efficiency of Fresnel lenses,which drives improvements in power generation output and QE(Quantum Efficiency).展开更多
Predicting molecular properties is essential for advancing for advancing drug discovery and design. Recently, Graph Neural Networks (GNNs) have gained prominence due to their ability to capture the complex structural ...Predicting molecular properties is essential for advancing for advancing drug discovery and design. Recently, Graph Neural Networks (GNNs) have gained prominence due to their ability to capture the complex structural and relational information inherent in molecular graphs. Despite their effectiveness, the “black-box” nature of GNNs remains a significant obstacle to their widespread adoption in chemistry, as it hinders interpretability and trust. In this context, several explanation methods based on factual reasoning have emerged. These methods aim to interpret the predictions made by GNNs by analyzing the key features contributing to the prediction. However, these approaches fail to answer critical questions: “How to ensure that the structure-property mapping learned by GNNs is consistent with established domain knowledge”. In this paper, we propose MMGCF, a novel counterfactual explanation framework designed specifically for the prediction of GNN-based molecular properties. MMGCF constructs a hierarchical tree structure on molecular motifs, enabling the systematic generation of counterfactuals through motif perturbations. This framework identifies causally significant motifs and elucidates their impact on model predictions, offering insights into the relationship between structural modifications and predicted properties. Our method demonstrates its effectiveness through comprehensive quantitative and qualitative evaluations of four real-world molecular datasets.展开更多
Photothermal therapy(PTT)and photodynamic therapy(PDT)have received tremendous attention owing to their great potential for tumor treatment.However,two main issues hamper the antitumor performance of PDT:overexpressio...Photothermal therapy(PTT)and photodynamic therapy(PDT)have received tremendous attention owing to their great potential for tumor treatment.However,two main issues hamper the antitumor performance of PDT:overexpression of glutathione(GSH)in tumors,which consumes PDT-induced reactive oxygen species(ROS),and hypoxia within the tumor microenvironment.The drawbacks of PTT include uneven temperature distribution and the upregulation of the heat-shock proteins in tumors,both of which result in ineffective treatment.To address these issues,a MnO_(2)doped nano-delivery system(HTIM-PMs)was synthesized by one-step self-assembly of disulfide bond bridged copolymers for indocyanine green(ICG)and MnO_(2)loading.The surface of polymeric micelles was layered with hyaluronan(HA)and transactivator(TAT)peptides to improve active targeting and increase cell penetration.After internalization,HTIM-PMs showed responsiveness to the tumor microenvironment(acid pH,high glutathione,high H_(2)O_(2)).Breaking the disulfide bond reduced the intratumoral GSH level and simultaneously released the MnO_(2)and ICG.The released MnO_(2)further reduced the GSH level and promoted O_(2)generation,thus enhancing the PDT effect.The PTT-mediated hyperthermia accelerated blood flow,which is beneficial for O_(2)distribution,and promotes ROS diffusion.These PTT-mediated adjuvant effects further overcame the limitations of PDT and the robust PDT effect in turn compensated for the deficiency of PTT.This promising platform exhibited a significant improvement in the PTT-PDT cancer treatment strategy compared to previously reported nanostructures.展开更多
The complex refractive index dispersion(CRID)of absorbing materials is very important in many fields,especially in printing industry and medical research.However,due to their strong absorbing,CRID determination is sti...The complex refractive index dispersion(CRID)of absorbing materials is very important in many fields,especially in printing industry and medical research.However,due to their strong absorbing,CRID determination is still a challenge.In this study,without diluting treatment or the thickness information,a method is proposed to calculate the CRID of absorbing materials,based merely on the reflectance and transmittance spectra measurements.The method separates the CRID into absorbing part and transparent part based on Kramers-Kronig relations,and it also uses the common Cauchy dispersion formula and Fresnel reflection formula.The CRID of methyl-red-doped poly(methyl methacrylate)(MR-PMMA)(3%mass fraction)and hemoglobin(Hb)solutions(320 g/L)are determined over the spectral range from 400 nm to 750 nm,and the result shows good stability and consistency of the method.展开更多
The Cyclonic-Static Microbubble Flotation Column (FCSMC) is currently a widely used, novel type of flotation device. The self-absorbing microbubble generator is the core component of this device. The structure of the ...The Cyclonic-Static Microbubble Flotation Column (FCSMC) is currently a widely used, novel type of flotation device. The self-absorbing microbubble generator is the core component of this device. The structure of the microbubble generator directly influences flotation column performance by affecting bubble size and distribution as well as gas holdup in the column. However, the complicated flow inside the generator results in high R&D costs and difficulty in testing. Thus, the CFD software, FLUENT, was used to simulate the gas-liquid two-phase flow inside a self-absorbing microbubble generator. The effect of area ratio, a key structural parameter, was studied in detail. Critical flow-field parameters including velocity, turbulent kinetic energy, minimum static pressure and gas holdup were obtained. The simulation results demonstrate that the optimum area ratio is 3.展开更多
A WTi-Al_(2)O_(3)cermet-based solar selective absorber was prepared to investigate the atomic diffusion induced spectral selectivity degeneration.The as-deposited coating exhibits superior absorptance(0.934)and low th...A WTi-Al_(2)O_(3)cermet-based solar selective absorber was prepared to investigate the atomic diffusion induced spectral selectivity degeneration.The as-deposited coating exhibits superior absorptance(0.934)and low thermal emittance(0.098),as well as excellent thermal stability with a selectivity of 0.900/0.07 even after annealing at 923 K for 400 h in Ar ambient.However,the multilayer coating failed after being subjected to annealing at 923 K for 400 h in an air environment,as indicated by a decrease in solar absorptance to 0.912 and an increase in thermal emittance to 0.634.The microstructure characterizations reveal that the annealed coating exhibits a columnar morphology along the vertical direction of the substrate.The presence of abundant grain boundaries in the multilayer coating promotes the outward diffusion of Cr and Mn atoms in the stainless-steel substrate.The Mn atoms,in particular,possess the capability to migrate towards the surface of the coating and undergo an oxidation reaction with oxygen,facilitating the formation of a thick Mn_(2)O_(3)layer.The roughness of the coating surface was significantly increased in this case,adversely affecting solar absorptance due to amplified sunlight reflection.In addition,the rocketing of thermal emittance is attributed to the destabilization of W infrared reflective layer during the annealing.These findings highlight the importance of considering the outward diffusion of Mn and Cr elements in the stainless-steel substrate when optimizing solar selective absorbers.展开更多
The Finite-Difference Time-Domain (FDTD) method is a well-known technique for the analysis of quantum devices. It solves a discretized Schrodinger equation in an iterative process. However, the method provides only a ...The Finite-Difference Time-Domain (FDTD) method is a well-known technique for the analysis of quantum devices. It solves a discretized Schrodinger equation in an iterative process. However, the method provides only a second-order accurate numerical solution and requires that the spatial grid size and time step should satisfy a very restricted condition in order to prevent the numerical solution from diverging. In this article, we present a generalized FDTD method with absorbing boundary condition for solving the one-dimensional (1D) time-dependent Schr?dinger equation and obtain a more relaxed condition for stability. The generalized FDTD scheme is tested by simulating a particle moving in free space and then hitting an energy potential. Numerical results coincide with those obtained based on the theoretical analysis.展开更多
Fabrics,a class of carriers,have been pioneered in electromagnetic protection,but their microwave absorbing potential has not been fully explored for a considerable period.Herein,aramid nanofibers(ANFs)enhanced reduce...Fabrics,a class of carriers,have been pioneered in electromagnetic protection,but their microwave absorbing potential has not been fully explored for a considerable period.Herein,aramid nanofibers(ANFs)enhanced reduced graphene oxide fabrics(ANF/rGO fabrics)were synthesized by wet spinning-chemical reduction.The ANF/rGO fabrics can achieve the minimum reflection loss(RLmin)of−15.8 dB with a thickness of 2.7 mm.On this basis,ANF/rGO fabrics grown with polyaniline(ANF/rGO-PANi fabrics)through in-situ doping polymerization were obtained.Polyaniline compensates for the lack of conductivity of the dielectric fabrics,bringing higher impedance matching and attenuation capability.The corresponding RLmin can reach−52.3 dB under 2.9 mm and the effective absorption bandwidth(EAB)increases to 6 GHz covering the whole Ku band under 2.5 mm.The fabrics woven by high-strength graphene-based hybrid fibers proposed in this study provide a new angle to achieve high-efficiency microwave absorption.展开更多
The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifical...The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifically the capillary gravity waves generated by its motion at the surface. The study analyses the flow of an inviscid, barotropic, and compressible fluid around the stationary solid body. The dynamic behaviour of the fluid is analysed using a two-dimensional coupled Neumann-Kelvin model extended with capillarity and inertia terms. For computational purposes, it is necessary to truncate the unbounded spatial domain with artificial boundaries and then introduce appropriate absorbing boundary conditions. The propagation of short wavelength waves in a convective fluid medium with significant differences in properties between the interior and the surface of the fluid presents a number of difficulties in the design of these conditions. The results are illustrated numerically and commented upon.展开更多
B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear fuel.In order to improve the high-temperature mechanical properties of B_(4)C/Al composites,i...B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear fuel.In order to improve the high-temperature mechanical properties of B_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder surface.In this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(B_(4)C+Al_(2)O_(3))/Al composites.It was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high temperature.As the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased significantly.The finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional B_(4)C/Al composites.展开更多
文摘The extended Brinkman Darcy model for momentum equations and an energy equation is used to calculate the unsteady natural convection Couette flow of a viscous incompressible heat generating/absorbing fluid in a vertical channel （formed by two infinite vertical and parallel plates） filled with the fluid-saturated porous medium. The flow is triggered by the asymmetric heating and the accelerated motion of one of the bounding plates. The governing equations are simplified by the reasonable dimensionless parameters and solved analytically by the Laplace transform techniques to obtain the closed form solutions of the velocity and temperature profiles. Then, the skin friction and the rate of heat transfer are consequently derived. It is noticed that, at different sections within the vertical channel, the fluid flow and the temperature profiles increase with time, which are both higher near the moving plate. In particular, increasing the gap between the plates increases the velocity and the temperature of the fluid, however, reduces the skin friction and the rate of heat transfer.
文摘This study considers a theoretical analysis of natural convection flow of heat generating/absorbing fluid near an infinite vertical plate with ramped temperature. It is assumed that the bounding plate has a ramped temperature profile. Exact solutions of energy and momentum equations are obtained using the Laplacetransform techniques. Solutions are obtained for different values of the Prandtl number (Pr) and the heat sink parameter (S). Results of the ramped and isothermal temperature and velocity as well as Nusselt number and skin friction have been compared and presented with the help of graphs.
基金supported by the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515010093)the Shenzhen Fundamental Research Program (Stable Support Plan Program)(Nos.JCYJ20220809170611004, 20231121110828001 and 20231121113641002)the National Taipei University of Technology-Shenzhen University Joint Research Program (No.2024001)。
文摘In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.
基金supported by the Spanish Government(ISCIII-FEDER)PI20/01063by Navarra Government(PC 060-061 and PC 192-193)Fundación Gangoiti(to MSA).LA was funded by FPU19/03255.
文摘Neuroinflammation is associated with Parkinson’s disease:Reactive gliosis and neuroinflammation are hallmarks of Parkinson’s disease(PD),a multisystem neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons.Neuroinflammation has long been considered a mere consequence of neuronal loss,but whether it promotes PD or is a key player in disease progression remains to be determined.Human leukocyte antigen.
文摘This study presents a comparative analysis of a complex SQL benchmark, TPC-DS, with two existing text-to-SQL benchmarks, BIRD and Spider. Our findings reveal that TPC-DS queries exhibit a significantly higher level of structural complexity compared to the other two benchmarks. This underscores the need for more intricate benchmarks to simulate realistic scenarios effectively. To facilitate this comparison, we devised several measures of structural complexity and applied them across all three benchmarks. The results of this study can guide future research in the development of more sophisticated text-to-SQL benchmarks. We utilized 11 distinct Language Models (LLMs) to generate SQL queries based on the query descriptions provided by the TPC-DS benchmark. The prompt engineering process incorporated both the query description as outlined in the TPC-DS specification and the database schema of TPC-DS. Our findings indicate that the current state-of-the-art generative AI models fall short in generating accurate decision-making queries. We conducted a comparison of the generated queries with the TPC-DS gold standard queries using a series of fuzzy structure matching techniques based on query features. The results demonstrated that the accuracy of the generated queries is insufficient for practical real-world application.
基金Project supported by the National Natural Science Foundation of China(Grant No.12164030)Young Science and Technology Talents of Inner Mongolia,China(Grant No.NJYT22101)+1 种基金the Central Government Guides Local Science,the Technology Development Fund Projects(Grant No.2023ZY0005)the Science and Technology Plan Projects of Inner Mongolia Autonomous Region of China(Grant No.2023KYPT0012)。
文摘In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As has been used in solidstate and fiber lasers as a mode-locker.However,the pulse widths that have been reported in the searchable published literature are all long and the shortest is tens of picoseconds.Femtosecond pulse widths,desired for a variety of applications,have not yet been reported in Ga As-based pulsed lasers.In this work,we further explore the nonlinear characteristics of Ga As that has been magnetron sputtered onto the surface of a tapered fiber and its application in the generation of femtosecond lasing via effective dispersion optimization and nonlinearity management.With the enhanced interaction between evanescent waves and Ga As nanosheets,mode-locked soliton pulses as short as 830 fs are generated at repetition rates of 4.64 MHz.As far as we know,this is the first time that femtosecond-level pulses have been generated with a Ga As-based saturable absorber.In addition,soliton molecules,including in the dual-pulse state,are also realized under stronger pumping.This work demonstrates that Ga As-based photonic devices have good application prospects in effective polymorphous ultrashort pulsed laser generation.
基金financially supported by the National Natural Science Foundation of China(No.52231007)the Natural Science Foundation of Shaanxi Province(No.2022JM-248)+1 种基金the Creative Research Foundation of the Science and Technology on Thermostructural Composite Materials Laboratorythe Doctoral Scientific Research Foundation of Shaanxi University of Science&Technology(No.BJ16-06).
文摘The dielectric loss of carbon materials is closely related to the microstructure and the degree of crystallization,and the microstructure modulation of electromagnetic wave absorbing carbon materials is the key to enhancing absorption properties.In this work,a porous elastic Co@CNF-PDMS composite was prepared by freeze-drying and confined catalysis.The graphitization degree and conductivity loss of carbon nanofibers(CNFs)were regulated by heat treatment temperature and Co catalyst content.The construction of a heterointerface between Co and C enhances the interfacial polarization loss.The Co@CNF-PDMS composite with 4.5 mm achieves the minimum reflection loss(RLmin)of-81.0 dB at 9.9 GHz and RL no higher than-12.1 dB in the whole of the X-band.After applying a load of up to 40% strain and 100 cycles to Co@CNF-PDMS,the dielectric properties of the composite remain stable.With the increase of compression strain,the distribution density of the absorbent increases,and the CNF sheet layer extrusion contact forms a conductive path,which leads to the conductive loss increase,finally,the absorption band moves to a high frequency.The absorption band can be bi-directionally regulated by loading and strain with good stability,which provides a new strategy for the development of intelligent electromagnetic wave absorbing materials.
基金partially funded by the National Natural Science Foundation of China(Grant Nos.52179098 and 41907251)the State Scholarship Fund of China(Grant No.202306650001).
文摘In geotechnical engineering,rock bolts are commonly used for reinforcement,while the surrounding rock mass bears varying degrees of shear loads.The shear rate affects the stability of bolted rock joints,especially in projects susceptible to dynamic shear loads.In laboratory experiments,fully-grouted bolts and energy-absorbing bolts were used as research objects,and artificial rock specimens with rough joints were fabricated to analyze the shear characteristics and damage mechanisms of bolted rock joints under cyclic shear conditions and different shear velocities.The results showed that as the shear rate increased,the shear strength of bolted rock joint specimens decreased.Degradation of asperities resulted in no obvious peak shear stress in the specimens.Energy-absorbing bolts exhibited greater deformation capacity,with significant necking phenomena and the ability to withstand larger shear displacements.In contrast,fully-grouted bolts,which have threaded surfaces that provide higher bonding performance,exhibited a reduced capacity for plastic deformation and were prone to breaking under smaller shear displacements.Although the shear stiffness of specimens reinforced by energy-absorbing bolts was slightly lower than that of fully-grouted bolt specimens,they demonstrated greater stability under various shear rates.The absorbed shear energy showed that energy-absorbing bolts had superior coordinated deformation capabilities,thus exhibiting greater absorbed shear energy than fully-grouted bolts.Overall,fully-grouted bolts are more suitable for projects requiring higher rock shear strength and overall stiffness.In contrast,energy-absorbing bolts are more suitable for coping with dynamic or fluctuating load conditions to maintain the relative stability of jointed rock masses.
基金supported by the National Nature Science Foundation of China (Nos. 61671362 and 62071366)。
文摘Two dimensional(2D) materials based on boron and carbon have attracted wide attention due to their unique properties. BC compounds have rich active sites and diverse chemical coordination, showing great potential in optoelectronic applications. However, due to the limitation of calculation and experimental conditions, it is still a challenging task to predict new 2D BC monolayer materials. Specifically, we utilized Crystal Diffusion Variational Autoencoder(CDVAE) and pre-trained Materials Graph Neural Network with 3-Body Interactions(M3GNet) model to generate novel and stable BCP materials. Each crystal structure was treated as a high-dimensional vector, where the encoder extracted lattice information and element coordinates, mapping the high-dimensional data into a low-dimensional latent space. The decoder then reconstructed the latent representation back into the original data space. Additionally, our designed attribute predictor network combined the advantages of dilated convolutions and residual connections,effectively increasing the model's receptive field and learning capacity while maintaining relatively low parameter count and computational complexity. By progressively increasing the dilation rate, the model can capture features at different scales. We used the DFT data set of about 1600 BCP monolayer materials to train the diffusion model, and combined with the pre-trained M3GNet model to screen the best candidate structure. Finally, we used DFT calculations to confirm the stability of the candidate structure.The results show that the combination of generative deep learning model and attribute prediction model can help accelerate the discovery and research of new 2D materials, and provide effective methods for exploring the inverse design of new two-dimensional materials.
基金supported by the National Natural Science Foundation of China(No.52402078)Yunnan Major Scientific and Technological Projects(No.202302AG050010)+1 种基金Yunnan Fundamental Research Projects(No.202201BE070001-008)the National Key Research and Development Program of China(No.2022YFB3708600)。
文摘In this work,a novel microwave absorbing material(MAM)made of a pseudo-binary of Sr_(2)TiMoO_(6)-Al_(2)O_(3)(STM)is proposed first.The MAMs labeled as STM X(X=60,70,80 and 100,respectively),in which X is the initial weight percent of Sr_(2)TiMoO_(6),were synthesized using the solid-state reaction method.Compared with STM100,some equilibrium phases,including SrTiO_(3),Mo,Sr_(8)(Al1_(2)O_(24))(MoO_(4))_(2)and a few undefined ones,are presented in the composites as evidenced by X-ray diffraction results and scanning electron microscopy due to the chemical reaction between Sr_(2)TiMoO_(6)and Al_(2)O_(3)component.Besides conductance loss,heterogeneous interfaces between various equilibrium phases introduce interfacial polarization,which causes an enhancement of dissipation for the incident electromagnetic wave.Among the synthesized samples,STM80 presents the best microwave absorbing properties.It has a minimum reflection loss(RLmin)of-26 dB and an effective absorbing bandwidth up to 2.7 GHz when the thickness is only 1 mm.This indicates that STM80 is a new type of microwave absorbing material with strong absorption and ultrathin thickness.
文摘Concentrated solar thermal power generation has been experimentally tested in advanced countries for a period of time.This paper demonstrates how this technology can be improved by using water molecules as a medium to drive traditional generator sets for energy conversion,thereby simultaneously improving the energy conversion rate.Additionally,a novel contribution is made by incorporating a magic number 4 to enhance the focusing efficiency of Fresnel lenses,which drives improvements in power generation output and QE(Quantum Efficiency).
文摘Predicting molecular properties is essential for advancing for advancing drug discovery and design. Recently, Graph Neural Networks (GNNs) have gained prominence due to their ability to capture the complex structural and relational information inherent in molecular graphs. Despite their effectiveness, the “black-box” nature of GNNs remains a significant obstacle to their widespread adoption in chemistry, as it hinders interpretability and trust. In this context, several explanation methods based on factual reasoning have emerged. These methods aim to interpret the predictions made by GNNs by analyzing the key features contributing to the prediction. However, these approaches fail to answer critical questions: “How to ensure that the structure-property mapping learned by GNNs is consistent with established domain knowledge”. In this paper, we propose MMGCF, a novel counterfactual explanation framework designed specifically for the prediction of GNN-based molecular properties. MMGCF constructs a hierarchical tree structure on molecular motifs, enabling the systematic generation of counterfactuals through motif perturbations. This framework identifies causally significant motifs and elucidates their impact on model predictions, offering insights into the relationship between structural modifications and predicted properties. Our method demonstrates its effectiveness through comprehensive quantitative and qualitative evaluations of four real-world molecular datasets.
基金financial support from the National Natural Science Foundation of China(Nos.82172090 and 82072059)CAMS Innovation Fund for Medical Sciences(CIFMS,Nos.2021-I2M-1-058 and 2022-I2M-1-023)+1 种基金Fundamental Research Funds for the Central Universities(No.2019PT320028)Tianjin Municipal Natural Science Foundation(No.20JCYBJC00030)。
文摘Photothermal therapy(PTT)and photodynamic therapy(PDT)have received tremendous attention owing to their great potential for tumor treatment.However,two main issues hamper the antitumor performance of PDT:overexpression of glutathione(GSH)in tumors,which consumes PDT-induced reactive oxygen species(ROS),and hypoxia within the tumor microenvironment.The drawbacks of PTT include uneven temperature distribution and the upregulation of the heat-shock proteins in tumors,both of which result in ineffective treatment.To address these issues,a MnO_(2)doped nano-delivery system(HTIM-PMs)was synthesized by one-step self-assembly of disulfide bond bridged copolymers for indocyanine green(ICG)and MnO_(2)loading.The surface of polymeric micelles was layered with hyaluronan(HA)and transactivator(TAT)peptides to improve active targeting and increase cell penetration.After internalization,HTIM-PMs showed responsiveness to the tumor microenvironment(acid pH,high glutathione,high H_(2)O_(2)).Breaking the disulfide bond reduced the intratumoral GSH level and simultaneously released the MnO_(2)and ICG.The released MnO_(2)further reduced the GSH level and promoted O_(2)generation,thus enhancing the PDT effect.The PTT-mediated hyperthermia accelerated blood flow,which is beneficial for O_(2)distribution,and promotes ROS diffusion.These PTT-mediated adjuvant effects further overcame the limitations of PDT and the robust PDT effect in turn compensated for the deficiency of PTT.This promising platform exhibited a significant improvement in the PTT-PDT cancer treatment strategy compared to previously reported nanostructures.
基金supported by the National Key R&D Program of China(No.2021YFC2401401)。
文摘The complex refractive index dispersion(CRID)of absorbing materials is very important in many fields,especially in printing industry and medical research.However,due to their strong absorbing,CRID determination is still a challenge.In this study,without diluting treatment or the thickness information,a method is proposed to calculate the CRID of absorbing materials,based merely on the reflectance and transmittance spectra measurements.The method separates the CRID into absorbing part and transparent part based on Kramers-Kronig relations,and it also uses the common Cauchy dispersion formula and Fresnel reflection formula.The CRID of methyl-red-doped poly(methyl methacrylate)(MR-PMMA)(3%mass fraction)and hemoglobin(Hb)solutions(320 g/L)are determined over the spectral range from 400 nm to 750 nm,and the result shows good stability and consistency of the method.
基金Financial supports for this work provided by the National High Technology Research and Development Program of China (No.2008BAB31B02) is gratefully acknowledged
文摘The Cyclonic-Static Microbubble Flotation Column (FCSMC) is currently a widely used, novel type of flotation device. The self-absorbing microbubble generator is the core component of this device. The structure of the microbubble generator directly influences flotation column performance by affecting bubble size and distribution as well as gas holdup in the column. However, the complicated flow inside the generator results in high R&D costs and difficulty in testing. Thus, the CFD software, FLUENT, was used to simulate the gas-liquid two-phase flow inside a self-absorbing microbubble generator. The effect of area ratio, a key structural parameter, was studied in detail. Critical flow-field parameters including velocity, turbulent kinetic energy, minimum static pressure and gas holdup were obtained. The simulation results demonstrate that the optimum area ratio is 3.
基金Funded by the Natural Science Foundation of Shanxi Province of China(Nos.202303021221177 and 202103021224063)the National Natural Science Foundation of China(No.52002159)。
文摘A WTi-Al_(2)O_(3)cermet-based solar selective absorber was prepared to investigate the atomic diffusion induced spectral selectivity degeneration.The as-deposited coating exhibits superior absorptance(0.934)and low thermal emittance(0.098),as well as excellent thermal stability with a selectivity of 0.900/0.07 even after annealing at 923 K for 400 h in Ar ambient.However,the multilayer coating failed after being subjected to annealing at 923 K for 400 h in an air environment,as indicated by a decrease in solar absorptance to 0.912 and an increase in thermal emittance to 0.634.The microstructure characterizations reveal that the annealed coating exhibits a columnar morphology along the vertical direction of the substrate.The presence of abundant grain boundaries in the multilayer coating promotes the outward diffusion of Cr and Mn atoms in the stainless-steel substrate.The Mn atoms,in particular,possess the capability to migrate towards the surface of the coating and undergo an oxidation reaction with oxygen,facilitating the formation of a thick Mn_(2)O_(3)layer.The roughness of the coating surface was significantly increased in this case,adversely affecting solar absorptance due to amplified sunlight reflection.In addition,the rocketing of thermal emittance is attributed to the destabilization of W infrared reflective layer during the annealing.These findings highlight the importance of considering the outward diffusion of Mn and Cr elements in the stainless-steel substrate when optimizing solar selective absorbers.
文摘The Finite-Difference Time-Domain (FDTD) method is a well-known technique for the analysis of quantum devices. It solves a discretized Schrodinger equation in an iterative process. However, the method provides only a second-order accurate numerical solution and requires that the spatial grid size and time step should satisfy a very restricted condition in order to prevent the numerical solution from diverging. In this article, we present a generalized FDTD method with absorbing boundary condition for solving the one-dimensional (1D) time-dependent Schr?dinger equation and obtain a more relaxed condition for stability. The generalized FDTD scheme is tested by simulating a particle moving in free space and then hitting an energy potential. Numerical results coincide with those obtained based on the theoretical analysis.
基金supported by the National Nat-ural Science Foundation of China(NSFC,Nos.51903213 and 5217130190)the Science and Technology Planning Project of Sichuan Province(Nos.2023NSFSC1952 and 2022ZYD0028)+1 种基金the Central Government Guides the Local Science and Technology Development Special Funds(No.2021Szvup124)the Fundamental Research Funds for the Central Universities(Nos.2682021GF004 and 2682022CG005)to freely explore basic research projects.
文摘Fabrics,a class of carriers,have been pioneered in electromagnetic protection,but their microwave absorbing potential has not been fully explored for a considerable period.Herein,aramid nanofibers(ANFs)enhanced reduced graphene oxide fabrics(ANF/rGO fabrics)were synthesized by wet spinning-chemical reduction.The ANF/rGO fabrics can achieve the minimum reflection loss(RLmin)of−15.8 dB with a thickness of 2.7 mm.On this basis,ANF/rGO fabrics grown with polyaniline(ANF/rGO-PANi fabrics)through in-situ doping polymerization were obtained.Polyaniline compensates for the lack of conductivity of the dielectric fabrics,bringing higher impedance matching and attenuation capability.The corresponding RLmin can reach−52.3 dB under 2.9 mm and the effective absorption bandwidth(EAB)increases to 6 GHz covering the whole Ku band under 2.5 mm.The fabrics woven by high-strength graphene-based hybrid fibers proposed in this study provide a new angle to achieve high-efficiency microwave absorption.
文摘The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifically the capillary gravity waves generated by its motion at the surface. The study analyses the flow of an inviscid, barotropic, and compressible fluid around the stationary solid body. The dynamic behaviour of the fluid is analysed using a two-dimensional coupled Neumann-Kelvin model extended with capillarity and inertia terms. For computational purposes, it is necessary to truncate the unbounded spatial domain with artificial boundaries and then introduce appropriate absorbing boundary conditions. The propagation of short wavelength waves in a convective fluid medium with significant differences in properties between the interior and the surface of the fluid presents a number of difficulties in the design of these conditions. The results are illustrated numerically and commented upon.
基金supported by the National Key R&D Program of China(Grant No.2023YFB3710601)the National Natural Science Foundation of China(Grant Nos.52203385 and 52171056)+2 种基金the CNNC Science Fund for Talented Young Scholars,the Institute of Metal Research(IMR)Innovation Fund(Grant No.2021-ZD02)the Natural Science Foundation of Liaoning Province(Grant No.2022-BS-009)Young Elite Scientists Sponsorship Program by CAST(Grant No.YESS20220225).
文摘B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear fuel.In order to improve the high-temperature mechanical properties of B_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder surface.In this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(B_(4)C+Al_(2)O_(3))/Al composites.It was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high temperature.As the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased significantly.The finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional B_(4)C/Al composites.
