This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double...This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.展开更多
Water-lubricated bearings have great advantages in the application of ship tail bearings due to the characteristics of green,pollution-free,and sustainable.However,the poor wettability of water-lubricated materials,as...Water-lubricated bearings have great advantages in the application of ship tail bearings due to the characteristics of green,pollution-free,and sustainable.However,the poor wettability of water-lubricated materials,as well as the low viscosity and poor load-carrying capacity of water,resulting in poor lubricating film integrity and short material service life under low-speed,heavy-load,start-stop conditions,which limits its application.To study the relationship between wettability and lubrication state and improve the lubrication performance of Si_(3)N_(4) under water lubrication conditions,the characteristic parameters that determine the hydrophilicity of Sphagnum were detected and extracted,and the bionic Si_(3)N_(4) model was established using Material Studio.Then,the molecular dynamic behavior and tribological properties of different Si_(3)N_(4) models were simulated and analyzed.Pore structure affects the spreading and storage of water on the material surface and changes the wettability of the material.Under the condition of water lubrication,better wettability and water storage promote the formation of water film,effectively improve the lubrication state of the material,and improve its bearing performance.展开更多
Water-lubricated bearing has become the development trend in the future because of its economy and environmental friendliness.The poor friction performance under low speed and heavy load seriously limits the populariz...Water-lubricated bearing has become the development trend in the future because of its economy and environmental friendliness.The poor friction performance under low speed and heavy load seriously limits the popularization and application of water-lubricated bearings.Learning from nature,the phenomenon of low friction and wear in nature has aroused great interest of scientists,and a lot of research has been carried out from mechanism analysis to bionic application.In this review,our purpose is to provide guiding methods and analysis basis for the bionic design and theoretical research of anti-friction and anti-wear of water-lubricated bearings.The development of water-lubricated bearing materials are described.Some typical examples of natural friction reduction and drag reduction are introduced in detail,and several representative preparation methods are listed.Finally,the application status of bionic tribology in water-lubricated bearings is summarized,and the future development direction of water-lubricated bearings is prospected.展开更多
As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promot...As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.展开更多
Chronic exposed to high arsenic via drinking water is worldwide public health problem. A large number of epidemiological studies showed that exposed to arsenic cause the human body skin lesions and also induce cancer,...Chronic exposed to high arsenic via drinking water is worldwide public health problem. A large number of epidemiological studies showed that exposed to arsenic cause the human body skin lesions and also induce cancer, cardiovascular and other kind of diseases. So arsenism not only affect the person’s work capability and life quality but also result in economic losses and mental suffering. How to prevent and control the effects of high arsenic? What intervention is more important and necessary for arsenism? How to scientifically assess the interventions effect of short-term and long-term? Through a systematic follow-up investigation in different high arsenic regions in Inner Mongolia, the environmental arsenic and human body internal arsenic exposure were analyzed, the clinical characteristics and signs of arsenism patients were examined. We established the evaluation system of intervention and control measures for population exposed to high arsenic. This evaluation system and control measures included government and exposed population. For government, change water supply and keep it work well and health education is very important. For exposed population, improving the diet and treating the symptoms or signs related to arsenic is more necessary. Arsenic in human body such as nail or urine sample arsenic must be reduced to normal value and this index show that the subject if still or not expose to high arsenic.展开更多
The magnetically responsive anti-fouling nanofiber membrane(MRANM)was fabricated for efficient oilwater emulsion separation,which could be cleaned using oscillating magnetic field.MRANM was prepared by grafting superp...The magnetically responsive anti-fouling nanofiber membrane(MRANM)was fabricated for efficient oilwater emulsion separation,which could be cleaned using oscillating magnetic field.MRANM was prepared by grafting superparamagnetic Fe_(3)O_(4) nanoparticles onto the surface of electrospun polyacrylonitrile nanofiber membrane(PANM).Compared with PANM,the water contact angle of MRANM decreased from 104°to 0°,indicating that the hydrophilicity of the membrane was significantly improved.For the emulsions of hexadecane,octane and rapeseed oil,the separation efficiency was 98.04%,96.59%and 92.67%,respectively.After the treatments in oscillating magnetic field,the separation efficiency kept above 95%after 8 times recycling,which indicated that the MRANM had good regenerability and reusability.The as-fabricated membrane with magnetic responsiveness facilitated an effective method for solving the membrane fouling problem during practical applications of separation high viscosity oil-water emulsion.展开更多
Water-lubrication bearings are critical components in ship operation.However,studies on their maintenance and failure detection are highly limited.The use of sensors to continually monitor the working operation of bea...Water-lubrication bearings are critical components in ship operation.However,studies on their maintenance and failure detection are highly limited.The use of sensors to continually monitor the working operation of bearings is a potential approach to solve this problem,which is collectively called intelligent bearings.In this literature review,the recent progress of electrical resistance strain gauges,Fiber Bragg grating,triboelectric nanogenerators,piezoelectric nanogenerators,and thermoelectric sensors for in-situ monitoring is summarized.Future research and design concepts on intelligent water-lubrication bearings are also comprehensively discussed.The findings show that the accident risks,lubrication condition,and remaining life of water-lubricated bearings can be evaluated with the surface temperature,coefficient of friction,and wear volume monitoring.The research work on intelligent water-lubricated bearings is committed to promoting the development of green,electrified,and intelligent technologies for ship propulsion systems,which have important theoretical significance and application value.展开更多
Folic acid is a fully oxidized synthetic folate with high bioavailability and stability which has been extensively prescribed to prevent congenital disabilities.Here we revealed the immunosuppressive effect of folic a...Folic acid is a fully oxidized synthetic folate with high bioavailability and stability which has been extensively prescribed to prevent congenital disabilities.Here we revealed the immunosuppressive effect of folic acid by targeting splenic marginal zone B(MZB)cells.Folic acid demonstrates avid binding with the Fc domain of immunoglobulin M(IgM),targeting IgM positive MZB cells in vivo to destabilize IgM-B cell receptor(BCR)complex and block immune responses.The induced anergy of MZB cells by folic acid provides an immunological escaping window for antigens.Covalent conjugation of folic acid with therapeutic proteins and antibodies induces immunological evasion to mitigate the production of anti-drug antibodies,which is a major obstacle to the long-term treatment of biologics by reducing curative effects and/or causing adverse reactions.Folic acid acts as a safe and effective immunosuppressant via IgM-mediated MZB cells targeting to boost the clinical outcomes of biologics by inhibiting the production of anti-drug antibodies,and also holds the potential to treat other indications that adverse immune responses need to be transiently shut off.展开更多
With the development of green tribology in the shipping industry,the application of water lubrication gradually replaces oil lubrication in stern bearings and thrust bearings.In terms of large-scale and high-speed shi...With the development of green tribology in the shipping industry,the application of water lubrication gradually replaces oil lubrication in stern bearings and thrust bearings.In terms of large-scale and high-speed ships,water-lubricated bearings with high performance are more strictly required.However,due to the lubricating medium,water-lubricated bearings have many problems such as friction,wear,vibration,noise,etc.This review focuses on the performance of marine water-lubricated bearings and their failure prevention mechanism.Furthermore,the research of marine water-lubricated bearings is reviewed by discussing its lubrication principle,test technology,friction and wear mechanism,and friction noise generation mechanism.The performance enhancement methods have been overviewed from structure optimization and material modification.Finally,the potential problems and the perspective of water-lubricated bearings are given in detail.展开更多
Greenhouse gases(GHGs)emitted or absorbed by lakes are an important component of the global carbon cycle.However,few studies have focused on the GHG dynamics of eutrophic saline lakes,thus preventing a comprehensive u...Greenhouse gases(GHGs)emitted or absorbed by lakes are an important component of the global carbon cycle.However,few studies have focused on the GHG dynamics of eutrophic saline lakes,thus preventing a comprehensive understanding of the carbon cycle.Here,we conducted four sampling analyses using a floating chamber in Daihai Lake,a eutrophication saline lake in Inner Mongolia Autonomous Region,China,to explore its carbon dioxide(CO_(2))and methane(CH_(4))emissions.The mean CO_(2)emission flux(FCO_(2))and CH_(4)emission flux(FCH_(4))were 17.54±14.54 mmol/m^(2)/day and 0.50±0.50 mmol/m^(2)/day,respectively.The results indicated that Daihai Lake was a source of CO_(2)and CH_(4),and GHG emissions exhibited temporal variability.The mean CO_(2)partial pressure(p CO_(2))and CH_(4)partial pressure(p CH_(4))were 561.35±109.59μatm and 17.02±13.45μatm,which were supersaturated relative to the atmosphere.The regression and correlation analysis showed that the main influencing factors of p CO_(2)were wind speed,dissolved oxygen(DO),total nitrogen(TN)and Chlorophyll a(Chl.a),whereas the main influencing factors of p CH_(4)were water temperature(WT),Chl.a,nitrate nitrogen(NO_(3)^(-)-N),TN,dissolved organic carbon(DOC)and water depth.Salinity regulated carbon mineralization and organic matter decomposition,and it was an important influencing factor of p CO_(2)and p CH_(4).Additionally,the trophic level index(TLI)significantly increased p CH_(4).Our study elucidated that salinity and eutrophication play an important role in the dynamic changes of GHG emissions.However,research on eutrophic saline lakes needs to be strengthened.展开更多
Metasurfaces with spin-selective transmission play an increasingly critical role in realizing optical chiral responses,especially for strong intrinsic chirality,which is limited to complex three-dimensional geometry.I...Metasurfaces with spin-selective transmission play an increasingly critical role in realizing optical chiral responses,especially for strong intrinsic chirality,which is limited to complex three-dimensional geometry.In this paper,we propose a planar metasurface capable of generating maximal intrinsic chirality and achieving dual-band spinselective transmission utilizing dual quasi-bound states in the continuum(quasi-BICs)caused by the structural symmetry breaking.Interestingly,the value of circular dichroism(CD)and the transmittance of two kinds of circular polarization states can be arbitrarily controlled by tuning the asymmetry parameter.Remarkable CD approaching unity with the maximum transmittance up to 0.95 is experimentally achieved in the dual band.Furthermore,assisted by chiral BICs,the application in polarization multiplexed near-field image display is also exhibited.Our work provides a new avenue to flexibly control intrinsic chirality in planar structure and offers an alternative strategy to develop chiral sensing,multiband spin-selective transmission,and high-performance circularly polarized wave detection.The basic principle and design method of our experiments in the microwave regime can be extended to other bands,such as the terahertz and infrared wavelengths.展开更多
The interaction between cavity field and atoms plays an important role in exploring the abundant non-Hermitian physics and constructing powerful wave function devices.In this work,we propose theoretically and realize ...The interaction between cavity field and atoms plays an important role in exploring the abundant non-Hermitian physics and constructing powerful wave function devices.In this work,we propose theoretically and realize experimentally unidirectional perfect absorption in a non-Hermitian acoustic system with the help of the topological bound state in the continuum(BIC),which is established by the hybrid interaction between one trivial BIC and another conventional resonant state.In the 2D parameter space spanned by frequency and distance between the two resonators,the topological scattering singularities appear in pairs and are associated with topological distinguished charges.Meanwhile,we reveal the origin of topological charges and their continuous evolution with the loss factor.At a specific loss factor,two topological charges just annihilate together,and acoustic perfect absorption induced by topological BIC is realized at the left incidence,while there is no phase singularity and near-total reflection is observed at the right incidence,hence the system presents extreme asymmetry.Our work bridges the gap between scattering characteristics of non-Hermitian acoustic systems and topological scattering singularities,which may contribute to the research of novel non-Hermitian physics and the practical applications of advanced absorbers and sensors.展开更多
Optical resonators with high quality(Q)factors are paramount for the enhancement of light–matter interactions in engineered photonic structures,but their performance always suffers from the scattering loss caused by ...Optical resonators with high quality(Q)factors are paramount for the enhancement of light–matter interactions in engineered photonic structures,but their performance always suffers from the scattering loss caused by fabrication imperfections.Merging bound states in the continuum(BICs)provide us with a nontrivial physical mechanism to overcome this challenge,as they can significantly improve the Q factors of quasi-BICs.However,most of the reported merging BICs are found atΓpoint(the center of the Brillouin zone),which intensively limits many potential applications based on angular selectivity.To date,studies on manipulating merging BICs at off-Γpoint are always accompanied by the breaking of structural symmetry that inevitably increases process difficulty and structural defects to a certain extent.Here,we propose a scheme to construct merging BICs at almost an arbitrary point in momentum space without breaking symmetry.Enabled by the topological features of BICs,we merge four accidental BICs with one symmetry-protected BIC at theΓpoint and merge two accidental BICs with opposite topological charges at the off-Γpoint only by changing the periodic constant of a photonic crystal slab.Furthermore,the position of off-Γmerging BICs can be flexibly tuned by the periodic constant and height of the structure simultaneously.Interestingly,it is observed that the movement of BICs occurs in a quasi-flatband with ultra-narrow bandwidth.Therefore,merging BICs in a tiny band provide a mechanism to realize more robust ultrahigh-Q resonances that further improve the optical performance,which is limited by wide-angle illuminations.Finally,as an example of application,effective angle-insensitive second-harmonic generation assisted by different quasi-BICs is numerically demonstrated.Our findings demonstrate momentum-steerable merging BICs in a quasi-flatband,which may expand the application of BICs to the enhancement of frequency-sensitive light–matter interaction with angular selectivity.展开更多
Recently,the concepts of parity–time(PT)symmetry and band topology have inspired many novel ideas for light manipulation in their respective directions.Here we propose and demonstrate a perfect light absorber with a ...Recently,the concepts of parity–time(PT)symmetry and band topology have inspired many novel ideas for light manipulation in their respective directions.Here we propose and demonstrate a perfect light absorber with a PT phase transition via coupled topological interface states(TISs),which combines the two concepts in a onedimensional photonic crystal heterostructure.By fine tuning the coupling between TISs,the PT phase transition is revealed by the evolution of absorption spectra in both ideal and non-ideal PT symmetry cases.Especially,in the ideal case,a perfect light absorber at an exceptional point with unidirectional invisibility is numerically obtained.In the non-ideal case,a perfect light absorber in a broken phase is experimentally realized,which verifies the possibility of tailoring non-Hermiticity by engineering the coupling.Our work paves the way for novel effects and functional devices from the exceptional point of coupled TISs,such as a unidirectional light absorber and exceptional-point sensor.展开更多
The covalently closed circular DNA(cccDNA)of HBV plays a crucial role in viral persistence and is also a risk factor for developing HBV-induced diseases,including liver fibrosis.Stimulator of interferon genes(STING),a...The covalently closed circular DNA(cccDNA)of HBV plays a crucial role in viral persistence and is also a risk factor for developing HBV-induced diseases,including liver fibrosis.Stimulator of interferon genes(STING),a master regulator of DNA-mediated innate immune activation,is a potential therapeutic target for viral infection and virus-related diseases.In this study,agonist-induced STING signaling activation in macrophages was revealed to inhibit cccDNA-mediated transcription and HBV replication via epigenetic modification in hepatocytes.Notably,STING activation could efficiently attenuate the severity of liver injury and fibrosis in a chronic recombinant cccDNA(rcccDNA)mouse model,which is a proven suitable research platform for HBV-induced fibrosis.Mechanistically,STING-activated autophagic flux could suppress macrophage inflammasome activation,leading to the amelioration of liver injury and HBV-induced fibrosis.Overall,the activation of STING signaling could inhibit HBV replication through epigenetic suppression of cccDNA and alleviate HBV-induced liver fibrosis through the suppression of macrophage inflammasome activation by activating autophagic flux in a chronic HBV mouse model.This study suggests that targeting the STING signaling pathway may be an important therapeutic strategy to protect against persistent HBV replication and HBV-induced fibrosis.展开更多
Several soft tissues residing in the living body have excellent hydration lubrication properties and can provide effective protection during relative motion.In order to apply this advantage of soft matters in practica...Several soft tissues residing in the living body have excellent hydration lubrication properties and can provide effective protection during relative motion.In order to apply this advantage of soft matters in practical applications and try to avoid its disadvantage,such as swelling and weakening in water,a design strategy of a soft/hard double network(DN)hydrogel microsphere modified ultrahigh molecular weight polyethylene(UHMWPE)composite is proposed in this study.A series of microspheres of urea-formaldehyde(UF),polyacrylamide(PAAm)hydrogel,UF/PAAm double network,and their composites were prepared.The mechanical properties,swelling,wettability,friction properties,and the lubrication mechanisms of the composites were investigated.The results show that DN microspheres can have an excellent stability and provide hydration lubrication.The performance of 75 DN-1 composite was superior to others.This finding will provide a novel strategy for the development of water-lubricated materials and have wide application in engineering fields.展开更多
Photonic topological edge states in one-dimensional dimer chains have long been thought to be robust to structural perturbations by mapping the topological Su–Schrieffer–Heeger model of a solid-state system.However,...Photonic topological edge states in one-dimensional dimer chains have long been thought to be robust to structural perturbations by mapping the topological Su–Schrieffer–Heeger model of a solid-state system.However,the edge states at the two ends of a finite topological dimer chain will interact as a result of near-field coupling.This leads to deviation from topological protection by the chiral symmetry from the exact zero energy,weakening the robustness of the topological edge state.With the aid of non-Hermitian physics,the splitting frequencies of edge states can be degenerated again,with topological protection recovered by altering the gain or loss strength of the structure.This point of coalescence is known as the exceptional point(EP).The intriguing physical properties of EPs in topological structures give rise to many fascinating and counterintuitive phenomena.In this work,based on a finite non-Hermitian dimer chain composed of ultra-subwavelength resonators,we propose theoretically and verify experimentally that the sensitivity of topological edge states is greatly affected when the system passes through the EP.Using the EP of a non-Hermitian dimer chain,we realize a new sensor that is sensitive to perturbation of on-site frequency at the end of the structure and yet topologically protected from internal perturbation of site-to-site couplings.Our demonstration of a non-Hermitian topological structure with an EP paves the way for the development of novel sensors that are not sensitive to internal manufacturing errors but are highly sensitive to changes in the external environment.展开更多
The unidirectional excitation of near-field optical modes is a fundamental prerequisite for many photonic applications,such as wireless power transfer and information communications.We experimentally construct all-ele...The unidirectional excitation of near-field optical modes is a fundamental prerequisite for many photonic applications,such as wireless power transfer and information communications.We experimentally construct all-electric Huygens and spin metasources and demonstrate anomalous unidirectional excitation of high-k hyperbolic modes in two types of hyperbolic metasurfaces.We use a Huygens metasource to study the unidirectional excitation of hyperbolic bulk modes in a planar hyperbolic metamaterial(HMM).Specifically,unidirectional excitation is the same as that in free space in the vertical direction,but opposite to that in free space in the horizontal direction.This anomalous unidirectional excitation is determined by the anisotropic HMM dispersion.In addition,we use a spin metasource to observe the anomalous photonic spin Hall effect in a planar hyperbolic waveguide.For a near-field source with a specific spin,the guide mode with a fixed directional wave vector is excited due to spin-momentum locking.Because the directions of momentum and energy flows in the HMM waveguide are opposite,the unidirectional excitation of hyperbolic guided modes is reversed.Our results not only uncover the sophisticated electromagnetic functionalities of metasources in the near-field but may also provide novel opportunities for the development of integrated optical devices.展开更多
The running-in of cylinder liner-piston rings(CLPRs)is the most important process that must be performed before a marine diesel engine can be operated.The quality of running-in directly affects the reliability of a CL...The running-in of cylinder liner-piston rings(CLPRs)is the most important process that must be performed before a marine diesel engine can be operated.The quality of running-in directly affects the reliability of a CLPR.The surface texture of a CLPR has been proven to significantly affect its lubrication performance.In this study,the tribological behavior of a CLPR during running-in is investigated.Three types of surface textures are generated on the CLPR via laser processing:dimple texture on piston rings,groove texture on cylinder liners,and co-texture on both sides.Subsequently,a series of tests are performed on a slice tester.A load of 300 N(1.64 MPa) is applied,and two speeds(50 and 100 rpm)are adopted.The CLPR running-in quality is characterized based on three parameters,i.e.,the friction coefficient,contact resistance,and wear topography.Experimental results show that,compared with a non-textured surface,the three types of surface textures mentioned above improved the friction performance during running-in.The lubricant supply capacity of the dimple texture on the piston ring,as a mobile oil reservoir,is stronger than that of the groove texture on the cylinder liner serving as a static oil reservoir.By contrast,the wear resistance of the dimple texture,as a movable debris trap on the piston ring,is weaker than that of the groove texture on the cylinder liner,which serves as a static debris trap.It is demonstrated that the co-texture combines the advantages of dimples and groove textures.Compared with non-textured surfaces,the friction coefficient decreased the most at 100 rpm(44.5%),and the contact resistance improved the most at 50 rpm(352.9%).The coupling effect provides the surface with improved running-in quality by optimizing the tribological performance,particularly at the dead center.This study provides guidance for the tribological design and manufacturing of CLPR in marine diesel engines.展开更多
基金funded by the China Postdoctoral Science Foundation(Grant No.2022M721614)the opening project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology(Grant No.KFJJ23-07M)。
文摘This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.
基金The authors would like to express their sincere gratitude to the National Natural Science Foundation of China(Grant no.52171319).
文摘Water-lubricated bearings have great advantages in the application of ship tail bearings due to the characteristics of green,pollution-free,and sustainable.However,the poor wettability of water-lubricated materials,as well as the low viscosity and poor load-carrying capacity of water,resulting in poor lubricating film integrity and short material service life under low-speed,heavy-load,start-stop conditions,which limits its application.To study the relationship between wettability and lubrication state and improve the lubrication performance of Si_(3)N_(4) under water lubrication conditions,the characteristic parameters that determine the hydrophilicity of Sphagnum were detected and extracted,and the bionic Si_(3)N_(4) model was established using Material Studio.Then,the molecular dynamic behavior and tribological properties of different Si_(3)N_(4) models were simulated and analyzed.Pore structure affects the spreading and storage of water on the material surface and changes the wettability of the material.Under the condition of water lubrication,better wettability and water storage promote the formation of water film,effectively improve the lubrication state of the material,and improve its bearing performance.
基金the National Natural Science Foundation of China(Grant no.52171319).
文摘Water-lubricated bearing has become the development trend in the future because of its economy and environmental friendliness.The poor friction performance under low speed and heavy load seriously limits the popularization and application of water-lubricated bearings.Learning from nature,the phenomenon of low friction and wear in nature has aroused great interest of scientists,and a lot of research has been carried out from mechanism analysis to bionic application.In this review,our purpose is to provide guiding methods and analysis basis for the bionic design and theoretical research of anti-friction and anti-wear of water-lubricated bearings.The development of water-lubricated bearing materials are described.Some typical examples of natural friction reduction and drag reduction are introduced in detail,and several representative preparation methods are listed.Finally,the application status of bionic tribology in water-lubricated bearings is summarized,and the future development direction of water-lubricated bearings is prospected.
基金supported by the National Key Research and Development Program of China (Grant No. 2016YFA0301101)the National Natural Science Foundation of China (Grant Nos. 91850206, 61621001, 2004284, 11674247, and 11974261)+3 种基金Shanghai Science and Technology Committee, China (Grant Nos. 18JC1410900 and 18ZR1442900)the China Postdoctoral Science Foundation (Grant Nos. 2019TQ0232 and 2019M661605)the Shanghai Super Postdoctoral Incentive ProgramFundamental Research Funds for the Central Universities, China
文摘As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.
文摘Chronic exposed to high arsenic via drinking water is worldwide public health problem. A large number of epidemiological studies showed that exposed to arsenic cause the human body skin lesions and also induce cancer, cardiovascular and other kind of diseases. So arsenism not only affect the person’s work capability and life quality but also result in economic losses and mental suffering. How to prevent and control the effects of high arsenic? What intervention is more important and necessary for arsenism? How to scientifically assess the interventions effect of short-term and long-term? Through a systematic follow-up investigation in different high arsenic regions in Inner Mongolia, the environmental arsenic and human body internal arsenic exposure were analyzed, the clinical characteristics and signs of arsenism patients were examined. We established the evaluation system of intervention and control measures for population exposed to high arsenic. This evaluation system and control measures included government and exposed population. For government, change water supply and keep it work well and health education is very important. For exposed population, improving the diet and treating the symptoms or signs related to arsenic is more necessary. Arsenic in human body such as nail or urine sample arsenic must be reduced to normal value and this index show that the subject if still or not expose to high arsenic.
基金supported by the National Natural Science Founda-tion of China(22078347)National Natural Science Foundation of China(21961160745)+2 种基金Key Research and Development Program of Hebei Province,China(20374001D,21373303D)Science and Technology Program of Guanshanhu([2020]13)Program of Inno-vation Academy for Green Manufacture,CAS(IAGM2020C04).
文摘The magnetically responsive anti-fouling nanofiber membrane(MRANM)was fabricated for efficient oilwater emulsion separation,which could be cleaned using oscillating magnetic field.MRANM was prepared by grafting superparamagnetic Fe_(3)O_(4) nanoparticles onto the surface of electrospun polyacrylonitrile nanofiber membrane(PANM).Compared with PANM,the water contact angle of MRANM decreased from 104°to 0°,indicating that the hydrophilicity of the membrane was significantly improved.For the emulsions of hexadecane,octane and rapeseed oil,the separation efficiency was 98.04%,96.59%and 92.67%,respectively.After the treatments in oscillating magnetic field,the separation efficiency kept above 95%after 8 times recycling,which indicated that the MRANM had good regenerability and reusability.The as-fabricated membrane with magnetic responsiveness facilitated an effective method for solving the membrane fouling problem during practical applications of separation high viscosity oil-water emulsion.
基金Supported by the National Natural Science Foundation of China(Grant No.52171319).
文摘Water-lubrication bearings are critical components in ship operation.However,studies on their maintenance and failure detection are highly limited.The use of sensors to continually monitor the working operation of bearings is a potential approach to solve this problem,which is collectively called intelligent bearings.In this literature review,the recent progress of electrical resistance strain gauges,Fiber Bragg grating,triboelectric nanogenerators,piezoelectric nanogenerators,and thermoelectric sensors for in-situ monitoring is summarized.Future research and design concepts on intelligent water-lubrication bearings are also comprehensively discussed.The findings show that the accident risks,lubrication condition,and remaining life of water-lubricated bearings can be evaluated with the surface temperature,coefficient of friction,and wear volume monitoring.The research work on intelligent water-lubricated bearings is committed to promoting the development of green,electrified,and intelligent technologies for ship propulsion systems,which have important theoretical significance and application value.
基金supported by the National Natural Science Foundation of China(82125035,81973245 and 82373817,China)Shanghai Education Commission Major Project(2021-01-07-00-07-E00081,China)。
文摘Folic acid is a fully oxidized synthetic folate with high bioavailability and stability which has been extensively prescribed to prevent congenital disabilities.Here we revealed the immunosuppressive effect of folic acid by targeting splenic marginal zone B(MZB)cells.Folic acid demonstrates avid binding with the Fc domain of immunoglobulin M(IgM),targeting IgM positive MZB cells in vivo to destabilize IgM-B cell receptor(BCR)complex and block immune responses.The induced anergy of MZB cells by folic acid provides an immunological escaping window for antigens.Covalent conjugation of folic acid with therapeutic proteins and antibodies induces immunological evasion to mitigate the production of anti-drug antibodies,which is a major obstacle to the long-term treatment of biologics by reducing curative effects and/or causing adverse reactions.Folic acid acts as a safe and effective immunosuppressant via IgM-mediated MZB cells targeting to boost the clinical outcomes of biologics by inhibiting the production of anti-drug antibodies,and also holds the potential to treat other indications that adverse immune responses need to be transiently shut off.
基金financially supported by the National Key R&D Program of China(No.2018YFE0197600)National Natural Science Foundation of China(No.52071244).
文摘With the development of green tribology in the shipping industry,the application of water lubrication gradually replaces oil lubrication in stern bearings and thrust bearings.In terms of large-scale and high-speed ships,water-lubricated bearings with high performance are more strictly required.However,due to the lubricating medium,water-lubricated bearings have many problems such as friction,wear,vibration,noise,etc.This review focuses on the performance of marine water-lubricated bearings and their failure prevention mechanism.Furthermore,the research of marine water-lubricated bearings is reviewed by discussing its lubrication principle,test technology,friction and wear mechanism,and friction noise generation mechanism.The performance enhancement methods have been overviewed from structure optimization and material modification.Finally,the potential problems and the perspective of water-lubricated bearings are given in detail.
基金supported by the National Key Research and Development Program of China (No.2021YFC3201203)the National Natural Science Foundation of China (Nos.51869014 and 52279067)+2 种基金the Major Science and Technology Projects of Inner Mongolia Autonomous Region (Nos.2020ZD0009 and ZDZX2018054)the Key Scientific and Technological Project of Inner Mongolia (No.2019GG019)the Open Project Program of the Ministry of Education Key Laboratory of Ecology and Resources Use of the Mongolian Plateau (No.KF2020006)。
文摘Greenhouse gases(GHGs)emitted or absorbed by lakes are an important component of the global carbon cycle.However,few studies have focused on the GHG dynamics of eutrophic saline lakes,thus preventing a comprehensive understanding of the carbon cycle.Here,we conducted four sampling analyses using a floating chamber in Daihai Lake,a eutrophication saline lake in Inner Mongolia Autonomous Region,China,to explore its carbon dioxide(CO_(2))and methane(CH_(4))emissions.The mean CO_(2)emission flux(FCO_(2))and CH_(4)emission flux(FCH_(4))were 17.54±14.54 mmol/m^(2)/day and 0.50±0.50 mmol/m^(2)/day,respectively.The results indicated that Daihai Lake was a source of CO_(2)and CH_(4),and GHG emissions exhibited temporal variability.The mean CO_(2)partial pressure(p CO_(2))and CH_(4)partial pressure(p CH_(4))were 561.35±109.59μatm and 17.02±13.45μatm,which were supersaturated relative to the atmosphere.The regression and correlation analysis showed that the main influencing factors of p CO_(2)were wind speed,dissolved oxygen(DO),total nitrogen(TN)and Chlorophyll a(Chl.a),whereas the main influencing factors of p CH_(4)were water temperature(WT),Chl.a,nitrate nitrogen(NO_(3)^(-)-N),TN,dissolved organic carbon(DOC)and water depth.Salinity regulated carbon mineralization and organic matter decomposition,and it was an important influencing factor of p CO_(2)and p CH_(4).Additionally,the trophic level index(TLI)significantly increased p CH_(4).Our study elucidated that salinity and eutrophication play an important role in the dynamic changes of GHG emissions.However,research on eutrophic saline lakes needs to be strengthened.
基金National Key Research and Development Program of China(2021YFA1400602)National Natural Science Foundation of China(11974261,62075213,12104105,12274325,11874286,61621001,91850206)。
文摘Metasurfaces with spin-selective transmission play an increasingly critical role in realizing optical chiral responses,especially for strong intrinsic chirality,which is limited to complex three-dimensional geometry.In this paper,we propose a planar metasurface capable of generating maximal intrinsic chirality and achieving dual-band spinselective transmission utilizing dual quasi-bound states in the continuum(quasi-BICs)caused by the structural symmetry breaking.Interestingly,the value of circular dichroism(CD)and the transmittance of two kinds of circular polarization states can be arbitrarily controlled by tuning the asymmetry parameter.Remarkable CD approaching unity with the maximum transmittance up to 0.95 is experimentally achieved in the dual band.Furthermore,assisted by chiral BICs,the application in polarization multiplexed near-field image display is also exhibited.Our work provides a new avenue to flexibly control intrinsic chirality in planar structure and offers an alternative strategy to develop chiral sensing,multiband spin-selective transmission,and high-performance circularly polarized wave detection.The basic principle and design method of our experiments in the microwave regime can be extended to other bands,such as the terahertz and infrared wavelengths.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA1400602)the National Natural Science Foundation of China(Grant Nos.12074286,and 12004284)+3 种基金the Shanghai Science and Technology Committee(Grant No.21JC1405600)the Fundamental Research Funds for the Central Universities(Grant No.22120210579)the Chenguang Program of Shanghai Education Development Foundationthe Shanghai Municipal Education Commission(Grant No.21CGA22)。
文摘The interaction between cavity field and atoms plays an important role in exploring the abundant non-Hermitian physics and constructing powerful wave function devices.In this work,we propose theoretically and realize experimentally unidirectional perfect absorption in a non-Hermitian acoustic system with the help of the topological bound state in the continuum(BIC),which is established by the hybrid interaction between one trivial BIC and another conventional resonant state.In the 2D parameter space spanned by frequency and distance between the two resonators,the topological scattering singularities appear in pairs and are associated with topological distinguished charges.Meanwhile,we reveal the origin of topological charges and their continuous evolution with the loss factor.At a specific loss factor,two topological charges just annihilate together,and acoustic perfect absorption induced by topological BIC is realized at the left incidence,while there is no phase singularity and near-total reflection is observed at the right incidence,hence the system presents extreme asymmetry.Our work bridges the gap between scattering characteristics of non-Hermitian acoustic systems and topological scattering singularities,which may contribute to the research of novel non-Hermitian physics and the practical applications of advanced absorbers and sensors.
基金National Key Research and Development Program of China (2021YFA1400602)National Natural Science Foundation of China (11974261,12104105,12274325,61621001,62075213,91850206)Fundamental Research Funds for the Central Universities (22120190222)。
文摘Optical resonators with high quality(Q)factors are paramount for the enhancement of light–matter interactions in engineered photonic structures,but their performance always suffers from the scattering loss caused by fabrication imperfections.Merging bound states in the continuum(BICs)provide us with a nontrivial physical mechanism to overcome this challenge,as they can significantly improve the Q factors of quasi-BICs.However,most of the reported merging BICs are found atΓpoint(the center of the Brillouin zone),which intensively limits many potential applications based on angular selectivity.To date,studies on manipulating merging BICs at off-Γpoint are always accompanied by the breaking of structural symmetry that inevitably increases process difficulty and structural defects to a certain extent.Here,we propose a scheme to construct merging BICs at almost an arbitrary point in momentum space without breaking symmetry.Enabled by the topological features of BICs,we merge four accidental BICs with one symmetry-protected BIC at theΓpoint and merge two accidental BICs with opposite topological charges at the off-Γpoint only by changing the periodic constant of a photonic crystal slab.Furthermore,the position of off-Γmerging BICs can be flexibly tuned by the periodic constant and height of the structure simultaneously.Interestingly,it is observed that the movement of BICs occurs in a quasi-flatband with ultra-narrow bandwidth.Therefore,merging BICs in a tiny band provide a mechanism to realize more robust ultrahigh-Q resonances that further improve the optical performance,which is limited by wide-angle illuminations.Finally,as an example of application,effective angle-insensitive second-harmonic generation assisted by different quasi-BICs is numerically demonstrated.Our findings demonstrate momentum-steerable merging BICs in a quasi-flatband,which may expand the application of BICs to the enhancement of frequency-sensitive light–matter interaction with angular selectivity.
基金National Key Research and Development Program of China(2021YFA1400602)National Natural Science Foundation of China(11974261,12275161,61621001,62075213,91850206)Fundamental Research Funds for the Central Universities(22120190222)。
文摘Recently,the concepts of parity–time(PT)symmetry and band topology have inspired many novel ideas for light manipulation in their respective directions.Here we propose and demonstrate a perfect light absorber with a PT phase transition via coupled topological interface states(TISs),which combines the two concepts in a onedimensional photonic crystal heterostructure.By fine tuning the coupling between TISs,the PT phase transition is revealed by the evolution of absorption spectra in both ideal and non-ideal PT symmetry cases.Especially,in the ideal case,a perfect light absorber at an exceptional point with unidirectional invisibility is numerically obtained.In the non-ideal case,a perfect light absorber in a broken phase is experimentally realized,which verifies the possibility of tailoring non-Hermiticity by engineering the coupling.Our work paves the way for novel effects and functional devices from the exceptional point of coupled TISs,such as a unidirectional light absorber and exceptional-point sensor.
基金This work was supported by grants from the National Natural Science Foundation of China(C31872731,C32070910,C31470839)Zhengyi Scholar Foundation of School of Basic Medical Sciences,Fudan University(S25-01).
文摘The covalently closed circular DNA(cccDNA)of HBV plays a crucial role in viral persistence and is also a risk factor for developing HBV-induced diseases,including liver fibrosis.Stimulator of interferon genes(STING),a master regulator of DNA-mediated innate immune activation,is a potential therapeutic target for viral infection and virus-related diseases.In this study,agonist-induced STING signaling activation in macrophages was revealed to inhibit cccDNA-mediated transcription and HBV replication via epigenetic modification in hepatocytes.Notably,STING activation could efficiently attenuate the severity of liver injury and fibrosis in a chronic recombinant cccDNA(rcccDNA)mouse model,which is a proven suitable research platform for HBV-induced fibrosis.Mechanistically,STING-activated autophagic flux could suppress macrophage inflammasome activation,leading to the amelioration of liver injury and HBV-induced fibrosis.Overall,the activation of STING signaling could inhibit HBV replication through epigenetic suppression of cccDNA and alleviate HBV-induced liver fibrosis through the suppression of macrophage inflammasome activation by activating autophagic flux in a chronic HBV mouse model.This study suggests that targeting the STING signaling pathway may be an important therapeutic strategy to protect against persistent HBV replication and HBV-induced fibrosis.
基金supported by the National Natural Science Foundation of China(51605248 and 51509195).
文摘Several soft tissues residing in the living body have excellent hydration lubrication properties and can provide effective protection during relative motion.In order to apply this advantage of soft matters in practical applications and try to avoid its disadvantage,such as swelling and weakening in water,a design strategy of a soft/hard double network(DN)hydrogel microsphere modified ultrahigh molecular weight polyethylene(UHMWPE)composite is proposed in this study.A series of microspheres of urea-formaldehyde(UF),polyacrylamide(PAAm)hydrogel,UF/PAAm double network,and their composites were prepared.The mechanical properties,swelling,wettability,friction properties,and the lubrication mechanisms of the composites were investigated.The results show that DN microspheres can have an excellent stability and provide hydration lubrication.The performance of 75 DN-1 composite was superior to others.This finding will provide a novel strategy for the development of water-lubricated materials and have wide application in engineering fields.
基金National Key R&D Program of China(2016YFA0301101)National Natural Science Foundation of China(11774261,12004284,61621001)+2 种基金Natural Science Foundation of Shanghai(18JC1410900)China Postdoctoral Science Foundation(2019M661605,2019TQ0232)Shanghai Super Postdoctoral Incentive Program.
文摘Photonic topological edge states in one-dimensional dimer chains have long been thought to be robust to structural perturbations by mapping the topological Su–Schrieffer–Heeger model of a solid-state system.However,the edge states at the two ends of a finite topological dimer chain will interact as a result of near-field coupling.This leads to deviation from topological protection by the chiral symmetry from the exact zero energy,weakening the robustness of the topological edge state.With the aid of non-Hermitian physics,the splitting frequencies of edge states can be degenerated again,with topological protection recovered by altering the gain or loss strength of the structure.This point of coalescence is known as the exceptional point(EP).The intriguing physical properties of EPs in topological structures give rise to many fascinating and counterintuitive phenomena.In this work,based on a finite non-Hermitian dimer chain composed of ultra-subwavelength resonators,we propose theoretically and verify experimentally that the sensitivity of topological edge states is greatly affected when the system passes through the EP.Using the EP of a non-Hermitian dimer chain,we realize a new sensor that is sensitive to perturbation of on-site frequency at the end of the structure and yet topologically protected from internal perturbation of site-to-site couplings.Our demonstration of a non-Hermitian topological structure with an EP paves the way for the development of novel sensors that are not sensitive to internal manufacturing errors but are highly sensitive to changes in the external environment.
基金This work was supported by the National Key R&D Program of China(Grant No.2016YFA0301101)the National Natural Science Foundation of China(NSFC)(Grant Nos.12004284,11775159,61621001,and 11935010)+3 种基金the Natural Science Foundation of Shanghai(Grant Nos.18ZR1442800 and 18JC1410900)China Postdoctoral Science Foundation(Grant Nos.2019TQ0232 and 2019M661605)the Shanghai Super Postdoctoral Incentive Programand the Opening Project of Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology.The authors declare no conflicts of interest.
文摘The unidirectional excitation of near-field optical modes is a fundamental prerequisite for many photonic applications,such as wireless power transfer and information communications.We experimentally construct all-electric Huygens and spin metasources and demonstrate anomalous unidirectional excitation of high-k hyperbolic modes in two types of hyperbolic metasurfaces.We use a Huygens metasource to study the unidirectional excitation of hyperbolic bulk modes in a planar hyperbolic metamaterial(HMM).Specifically,unidirectional excitation is the same as that in free space in the vertical direction,but opposite to that in free space in the horizontal direction.This anomalous unidirectional excitation is determined by the anisotropic HMM dispersion.In addition,we use a spin metasource to observe the anomalous photonic spin Hall effect in a planar hyperbolic waveguide.For a near-field source with a specific spin,the guide mode with a fixed directional wave vector is excited due to spin-momentum locking.Because the directions of momentum and energy flows in the HMM waveguide are opposite,the unidirectional excitation of hyperbolic guided modes is reversed.Our results not only uncover the sophisticated electromagnetic functionalities of metasources in the near-field but may also provide novel opportunities for the development of integrated optical devices.
文摘The running-in of cylinder liner-piston rings(CLPRs)is the most important process that must be performed before a marine diesel engine can be operated.The quality of running-in directly affects the reliability of a CLPR.The surface texture of a CLPR has been proven to significantly affect its lubrication performance.In this study,the tribological behavior of a CLPR during running-in is investigated.Three types of surface textures are generated on the CLPR via laser processing:dimple texture on piston rings,groove texture on cylinder liners,and co-texture on both sides.Subsequently,a series of tests are performed on a slice tester.A load of 300 N(1.64 MPa) is applied,and two speeds(50 and 100 rpm)are adopted.The CLPR running-in quality is characterized based on three parameters,i.e.,the friction coefficient,contact resistance,and wear topography.Experimental results show that,compared with a non-textured surface,the three types of surface textures mentioned above improved the friction performance during running-in.The lubricant supply capacity of the dimple texture on the piston ring,as a mobile oil reservoir,is stronger than that of the groove texture on the cylinder liner serving as a static oil reservoir.By contrast,the wear resistance of the dimple texture,as a movable debris trap on the piston ring,is weaker than that of the groove texture on the cylinder liner,which serves as a static debris trap.It is demonstrated that the co-texture combines the advantages of dimples and groove textures.Compared with non-textured surfaces,the friction coefficient decreased the most at 100 rpm(44.5%),and the contact resistance improved the most at 50 rpm(352.9%).The coupling effect provides the surface with improved running-in quality by optimizing the tribological performance,particularly at the dead center.This study provides guidance for the tribological design and manufacturing of CLPR in marine diesel engines.
