The dielectrophoretic technology has been one of the most frequently applied microfluidic technologies to manipulate particles.The way of a combination of controlled electroosmotic micro-vortices and dielectrophoresis...The dielectrophoretic technology has been one of the most frequently applied microfluidic technologies to manipulate particles.The way of a combination of controlled electroosmotic micro-vortices and dielectrophoresis to manipulate particles of different sizes was proposed in our previous work.However,the thickness of the modulating electrode is neglected.In practice,when the thickness of the modulating electrode increases,the channel flux increases,while the ability of the vortex to capture the particles reduces.In this study,a new method combining the field-modulating electroosmotic vortex and the insulating post is proposed to improve the manipulating capability of the field-modulated electroosmotic vortex to particles.The results indicate that there are three great advantages as the insulating post is placed on the channel wall on the same side of the modulating electrode.First,the capturing ability of the vortex to particles is greater due to the reduction of channel flux and the squeezing effect.Second,the range of regulating channel flux to achieve the optimal separation is extended.Third,the separation efficiency improves since the perfect separation can be achieved at a higher flow rate.Furthermore,the effects of the location and the size of the insulating post on particle separation are analyzed in detail.The present work could provide the reference for the application of the DEP technology.展开更多
Besides polyamidimide film and aromatic polyamidefiber paper which have been mentioned before, wehave also developed several other kinds of synthetic film and paperas polyester film, polyester fibre felt, polypropene ...Besides polyamidimide film and aromatic polyamidefiber paper which have been mentioned before, wehave also developed several other kinds of synthetic film and paperas polyester film, polyester fibre felt, polypropene film, and theircomposite materials. (a) Polyester film was exploited in China in early 60’s andput into mass production in middle 60’s. It is used mainly for slotinsulation of medium and small size motors as class E展开更多
Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the ...Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the smooth surface and chemical inertness of aramid fibers. Herein, AP are modified via the nacre-mimetic structure composed of aramid nanofibers (ANF) and carbonylated basalt nanosheets (CBSNs). This is achieved by impregnating AP into an ANF-CBSNs (A-C) suspension containing a 3D ANF framework as the matrix and 2D CBSNs as fillers. The resultant biomimetic composite papers (AP/A-C composite papers) exhibit a layered “brick-and-mortar” structure, demonstrating superior mechanical and electrical insulating properties. Notably, the tensile strength and breakdown strength of AP/A-C5 composite papers reach 39.69 MPa and 22.04 kV mm^(−1), respectively, representing a 155 % and 85 % increase compared to those of the control AP. These impressive properties are accompanied with excellent volume resistivity, exceptional dielectric properties, impressive folding endurance, outstanding heat insulation, and remarkable flame retardance. The nacre-inspired strategy offers an effective approach for producing highly promising electrical insulating papers for advanced electrical equipment.展开更多
The present study focuses on the formulation of new composite consisting of plaster and raffia vinifera particle (RVP) with the purpose to reducing energy consumption. The aim of this study is to test this new compoun...The present study focuses on the formulation of new composite consisting of plaster and raffia vinifera particle (RVP) with the purpose to reducing energy consumption. The aim of this study is to test this new compound as an insulating eco-material in building in a tropical climate. The composites samples were developed by mixing plaster with raffia vinifera particles (RVP) using three different sizes (1.6 mm, 2.5 mm and 4 mm). The effects of four different RVP incorporations rates (i.e., 0wt%, 5wt%;10wt%;15wt%) on physical, thermal, mechanicals properties of the composites were investigated. In addition, the use of the raffia vinifera particles and plaster based composite material as building envelopes thermal insulation material is studied by the habitable cell thermal behavior instrumentation. The results indicate that the incorporation of raffia vinifera particle leads to improve the new composite physical, mechanical and thermal properties. And the parametric analysis reveals that the sampling rate and the size of raffia vinifera particles are the most decisive factor to impact these properties, and to decreases in the thermal conductivity which leads to an improvement to the thermal resistance and energy savings. The best improvement of plaster composite was obtained at the raffia vinifera particles size between 2.5 and 4.0 mm loading of 5wt% (C95P5R) with a good ratio of thermo-physical-mechanical properties. Additionally, the habitable cell experimental thermal behavior, with the new raffia vinifera particles and plaster-based composite as thermal insulating material for building walls, gives an average damping of 4°C and 5.8°C in the insulated house interior environment respectively for cold and hot cases compared to the outside environment and the uninsulated house interior environment. The current study highlights that this mixture gives the new composite thermal insulation properties applicable in the eco-construction of habitats in tropical environments.展开更多
The protection effectiveness of traditional Lightning Strike Protection(LSP)for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike,so a new...The protection effectiveness of traditional Lightning Strike Protection(LSP)for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike,so a new protection method based on Air Breakdown and insulating adhesive layer(AB-LSP method)was designed to avoid it.In this study,a numerical method was developed to simulate the electrical breakdown,and verified by experiment results.Based on this method,a Finite Element Model(FEM)was established to investigate the effect of two factors(breakdown strength and initial ablation temperature of adhesive layer)on the LSP effectiveness.The results show that the breakdown strength impacts more to the ablation damage in composite than that of high-temperature resistance.Then,another FEM was established to predict the ablation damage by lightning strike in the AB-LSP method protected composite rotor blade.The mechanisms and potential key parameters(magnitude of lightning current,discharge channel location,adhesive layer thickness,and air gap width)that could affect the protection effectiveness were analyzed.The introduction of air breakdown changes the current conduction path and reduces explosion risk.After rational design,this method can offer effective lightning protection for composite helicopter rotor blade and other composite structures.展开更多
Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate...Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate radar stealth and thermal insulation capabilities.In this study,we have synthesized three-dimensional(3D)porous composites comprising V_(2)O_(3) nanoparticles embedded in Juncus effusus cellulose-derived carbon aerogels(VCA)using a self-templating method followed by high-temperature pyrolysis.The V_(2)O_(3) nanoparticles possess a 3D V-V framework and a relatively narrow bandgap,facilitating the Mott transition for enhanced conductivity.Furthermore,their uniform dispersion on hollow carbon tubes of Juncus effusus promotes efficient electron transfer and creates numerous heterogeneous interfaces.Consequently,VCA-2 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.92 dB at a matching thickness of 2.0mm and a maximum effective absorption bandwidth of 8.24 GHz at a thickness of 2.44mm,covering nearly half of the tested frequency range.Additionally,the radar cross-section reduction reaches a peak value of 29.40 dB m^(2),underscoring the excellent radar stealth capabilities of the material.In summary,VCA exhibits exceptional EMWA,radar stealth,and thermal insulation properties,highlighting its potential for multifunctional applications in EMWA material development.展开更多
Semi insulating (SI) InP wafers of 50 and 75mm in diameter can be obtained by annealing of undoped liquid encapsulated Czochralski (LEC) InP at 930℃ for 80h.The annealing ambient can be pure phosphorus (PP) or iron ...Semi insulating (SI) InP wafers of 50 and 75mm in diameter can be obtained by annealing of undoped liquid encapsulated Czochralski (LEC) InP at 930℃ for 80h.The annealing ambient can be pure phosphorus (PP) or iron phosphide (IP).The IP SI InP wafers have good electrical parameters and uniformity of whole wafer.However,PP SI InP wafers exhibit poor uniformity and electrical parameters.Photoluminescence which is subtle to deep defect appears in IP annealed semi insulating InP.Traps in annealed SI InP are detected by the spectroscopy of photo induced current transient.The results indicate that there are fewer traps in IP annealed undoped SI InP than those in as grown Fe doped and PP undoped SI InP.The formation mechanism of deep defects in annealed undoped InP is discussed.展开更多
Device structure and fabrication process of SOI nMOSFET depleted partially are p roposed for multi-gigahertz RF applications.Many advanced techniques for deep submiron MOSFETs are incorporated into the proposed devic...Device structure and fabrication process of SOI nMOSFET depleted partially are p roposed for multi-gigahertz RF applications.Many advanced techniques for deep submiron MOSFETs are incorporated into the proposed device.Main steps and condit ions in process are given in details,with simulation and optimization by using t he process simulator,Tsuprem4.Experiment results of 0.25μm SOI RF nMOSFET are i n consistence with simulated ones,and excellent or acceptable parameters of devi ce performance are obtained for multi-gigahertz RF applications.展开更多
Oligodendrocytes and their cell-intrinsic gene regulatory network:Oligodendrocytes(OLs)are the myelinating glial cells of the vertebrate central nervous system.They are responsible for insulating neuronal axons with a...Oligodendrocytes and their cell-intrinsic gene regulatory network:Oligodendrocytes(OLs)are the myelinating glial cells of the vertebrate central nervous system.They are responsible for insulating neuronal axons with a lipid-rich myelin sheath,which enables the saltatory conduction of action potentials.During development,oligodendrocyte progenitor cells(OPCs)emerge from neural stem cells in the ventricular zone.They then proliferate,increase their number,and migrate to their final destination where they encounter unmyelinated neuronal axons and differentiate in a stepwise fashion into myelinating oligodendrocytes(mOLs)under the influence of environmental stimuli.展开更多
The hybridization gap in strained-layer InAs/In_(x)Ga_(1−x) Sb quantum spin Hall insulators(QSHIs)is significantly enhanced compared to binary InAs/GaSb QSHI structures,where the typical indium composition,x,ranges be...The hybridization gap in strained-layer InAs/In_(x)Ga_(1−x) Sb quantum spin Hall insulators(QSHIs)is significantly enhanced compared to binary InAs/GaSb QSHI structures,where the typical indium composition,x,ranges between 0.2 and 0.4.This enhancement prompts a critical question:to what extent can quantum wells(QWs)be strained while still preserving the fundamental QSHI phase?In this study,we demonstrate the controlled molecular beam epitaxial growth of highly strained-layer QWs with an indium composition of x=0.5.These structures possess a substantial compressive strain within the In_(0.5)Ga_(0.5)Sb QW.Detailed crystal structure analyses confirm the exceptional quality of the resulting epitaxial films,indicating coherent lattice structures and the absence of visible dislocations.Transport measurements further reveal that the QSHI phase in InAs/In_(0.5)Ga_(0.5)Sb QWs is robust and protected by time-reversal symmetry.Notably,the edge states in these systems exhibit giant magnetoresistance when subjected to a modest perpendicular magnetic field.This behavior is in agreement with the𝑍2 topological property predicted by the Bernevig–Hughes–Zhang model,confirming the preservation of topologically protected edge transport in the presence of enhanced bulk strain.展开更多
Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always...Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always struggle to balance mechanical properties and thermal insulation,resulting in their inability to meet the demands for both washing resistance and personal protection.Herein,inspired by the natural spring-like structures of cucumber tendrils,a superelastic and washable micro/nanofibrous sponge(MNFS)based on biomimetic helical fibers is directly prepared utilizing multiple-jet electrospinning technology for high-performance thermal insulation.By regulating the conductivity of polyvinylidene fluoride solution,multiple-jet ejection and multiple-stage whipping of jets are achieved,and further control of phase separation rates enables the rapid solidification of jets to form spring-like helical fibers,which are directly entangled to assemble MNFS.The resulting MNFS exhibits superelasticity that can withstand large tensile strain(200%),1000 cyclic tensile or compression deformations,and retain good resilience even in liquid nitrogen(-196℃).Furthermore,the MNFS shows efficient thermal insulation with low thermal conductivity(24.85 mW m^(-1)K^(-1)),close to the value of dry air,and remains structural stability even after cyclic washing.This work offers new possibilities for advanced fibrous sponges in transportation,environmental,and energy applications.展开更多
Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectiv...Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectively.While these materials are affordable and display good thermal insulation,their unsustainable traits pertaining to an intensive manufacturing process and poor disposability are major concerns.Alternative insulation materials with enhanced sustainable characteristics are therefore being explored,and one type of material which has gained notable attention owing to its low carbon footprint and low thermal conductivity is natural fibre.Among the few review studies conducted on Natural Fibre Reinforced Composite(NFRC)insulation boards,the multitude of factors and underlying mechanisms affecting their thermal conductivity performance have been sparsely covered.This review study aimed to address this gap by providing a holistic overview of some of the key intrinsic and extrinsic factors affecting the thermal conductivity performance of NFRCs.Key intrinsic factors pertaining to the microstructural features and to the physico-mechanical traits of NFRCs,namely the fibre lumen size,α,and the fibre-matrix thermal conductivity ratio,β,respectively,were found to largely affect the Transverse Thermal Conductivity(TTC)in NFRC boards.Extrinsic factors,which were found to indirectly affect NFRCs’thermal conductivity,such as fibre pre-processing,composite manufacturing and environmental factors,were also covered.Some of the noteworthy NFRC featureswhich were found to affect their thermal conductivity are volume fraction of fibres,bulk density and porosity.The findings of this study highlight the need for additional research investigation to address the foregoing limitations observed in NFRC thermal insulation boards by considering appropriate natural fibres,composition and fabrication techniques.The fabrication of high-grade NFRC boards,which will display an optimum balance between enhanced thermal insulation and long-term durability performance,could further replace conventionally used thermal insulation boards in the modern building and construction industry.展开更多
In conventional higher-order topological insulators(HOTIs),the emergence of topological states can be explained by using the nonzero bulk polarization index.However,corner states emerge in HOTIs with incomplete bounda...In conventional higher-order topological insulators(HOTIs),the emergence of topological states can be explained by using the nonzero bulk polarization index.However,corner states emerge in HOTIs with incomplete boundary unit cells(i.e.,boundary defects)even though the bulk polarization is zero,which challenges the conventional understanding of HOTIs.Here,based on a Kekul´e-distorted honeycomb lattice with incomplete unit cells,we reveal that incomplete unit cells exhibit fractional charges through the analysis of Wannier centers by developing a compensation method and creating the concept of Wannier center domain(WCD)which is the smallest region that one Wannier center occupies.This method compensates for the missing parts of these boundary incomplete unit cells with additional WCDs to make them complete.The compensated WCDs automatically carry the corresponding charge,and this charge together with that of the incomplete unit cell constitutes the total charge of the complete unit cell after compensation.We conclude that the emergence of corner states is attributed to the filling anomaly,which is a fundamental mechanism.Our results refresh the understanding of HOTIs,especially those with structural discontinuities,and provide a novel design for topological states which have application value in producing optical functional devices.展开更多
Transition metal diborides based ultrahigh temperature ceramics(UHTCs) are characterized by high melting point, high strength and hardness, and high electrical and thermal conductivity. The high thermal conductivity a...Transition metal diborides based ultrahigh temperature ceramics(UHTCs) are characterized by high melting point, high strength and hardness, and high electrical and thermal conductivity. The high thermal conductivity arises from both electronic and phonon contributions. Thus electronic and phonon contributions must be controlled simultaneously in reducing the thermal conductivity of transition metal diborides. In high entropy(HE) materials, both electrons and phonons are scattered such that the thermal conductivity can significantly be reduced, which opens a new window to design novel insulating materials. Inspired by the high entropy effect, porous HE(Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)B2 is designed in this work as a new thermal insulting ultrahigh temperature material and is synthesized by an in-situ thermal borocarbon reduction/partial sintering process. The porous HE(Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)B2 possesses high porosity of 75.67%, pore size of 0.3–1.2 μm, homogeneous microstructure with small grain size of 400–800 nm, which results in low room temperature thermal diffusivity and thermal conductivity of 0.74 mm2 s^-1 and 0.51 W m^-1K^-1, respectively. In addition, it exhibits high compressive strength of3.93 MPa. The combination of these properties indicates that exploring porous high entropy ceramics such as porous HE(Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)B2 is a novel strategy in making UHTCs thermal insulating.展开更多
Understanding the role of heat transfer between catalysts and substrates is important for enhancing photothermal CO2 catalysis.Herein,we investigate the effect of different substrates,including silicon wafers,glass sl...Understanding the role of heat transfer between catalysts and substrates is important for enhancing photothermal CO2 catalysis.Herein,we investigate the effect of different substrates,including silicon wafers,glass slides and copper plates,on the photothermal catalytic performance of commercial Ni catalysts.The highest CO2 conversion rate and CO selectivity are observed in the catalyst film on the glass substrate,and this can be traced to a reduced catalyst-to-substrate heat transfer that increases the catalyst temperature under illumination.Our study reveals the important role of thermal management between catalysts and substrates in photothermal catalysis and sheds light on reactor design for efficient solar-to-chemical energy conversions.展开更多
With the mandate of worldwide carbon neutralization,pursuing comfortable living environment while consuming less energy is an enticing and unavoidable choice.Novel composite aerogels with super thermal insulation and ...With the mandate of worldwide carbon neutralization,pursuing comfortable living environment while consuming less energy is an enticing and unavoidable choice.Novel composite aerogels with super thermal insulation and high sunlight reflection are developed for energy-efficient buildings.A solvent-assisted freeze-casting strategy is used to produce boron nitride nanosheet/polyvinyl alcohol(BNNS/PVA)composite aerogels with a tailored alignment channel structure.The effects of acetone and BNNS fillers on microstructures and multifunctional properties of aerogels are investigated.The acetone in the PVA suspension enlarges the cell walls to suppress the shrinkage,giving rise to a lower density and a higher porosity,accompanied with much diminished heat conduction throughout the whole product.The addition of BNNS fillers creates whiskers in place of disconnected transverse ligaments between adjacent cell walls,further ameliorating the thermal insulation transverse to the cell wall direction.The resultant BNNS/PVA aerogel delivers an ultralow thermal conductivity of 23.5 mW m^(−1) K^(−1) in the transverse direction.The superinsulating aerogel presents both an infrared stealthy capability and a high solar reflectance of 93.8%over the whole sunlight wave-length,far outperforming commercial expanded polystyrene foams with reflective coatings.The anisotropic BNNS/PVA composite aerogel presents great potential for application in energy-saving buildings.展开更多
In this paper, we investigate the single event transient （SET） occurring in partially depleted silicon-on-insulator （PDSOI） metal-oxide-semiconductor （MOS） devices irradiated by pulsed laser beams. Transient sig...In this paper, we investigate the single event transient （SET） occurring in partially depleted silicon-on-insulator （PDSOI） metal-oxide-semiconductor （MOS） devices irradiated by pulsed laser beams. Transient signal characteristics of a 0.18-p.m single MOS device, such as SET pulse width, pulse maximum, and collected charge, are measured and an- alyzed at wafer level. We analyze in detail the influences of supply voltage and pulse energy on the SET characteristics of the device under test （DUT）. The dependences of SET characteristics on drain-induced barrier lowering （DIBL） and the parasitic bipolar junction transistor （PBJT） are also discussed. These results provide a guide for radiation-hardened deep sub-micrometer PDSOI technology for space electronics applications.展开更多
Bio-based polyurethane foam has attracted increasing attentions due to eco-friendliness and fossil feedstock issues.However,the inherent flammability limits its application in different fields.Herein,we demonstrate a ...Bio-based polyurethane foam has attracted increasing attentions due to eco-friendliness and fossil feedstock issues.However,the inherent flammability limits its application in different fields.Herein,we demonstrate a green bio-based flame-retardant system to fabricate polyurethane foam composite with durable flame retardancy,smoke suppression,and thermal insulation property.In this system,the green bio-based polyol(VED)with good reactivity and compatibility plays a role of flame retardant and EG acts as a synergistic filler.As a result,the LOI value of foam composite increased to 30.5 vol.%and it achieved a V-0 rating in the UL-94 vertical burning test.Additionally,the peak heat release rate(pHRR)and the total smoke production(TSP)decreased by 66.1%and 63.4%,respectively.Furthermore,the foam composite maintained durable flame retardancy after accelerated thermal aging test,whose thermal-insulating property was maintained even after being treated in high-humidity environment with 85%R.H.for a week.This work provides a facile strategy for durable flame retardancy and long-term thermal insulation performance,and creates opportunities for the practical applications of bio-based foam composites.展开更多
Chemical co-precipitation method was used to synthesize tin-doped indium oxide（ITO）nanoparticles,and the subsequent solution co-blend was employed to fabricate ITO/PVB nanocomposites.UV（Ultra-violet）-Vis（Visible...Chemical co-precipitation method was used to synthesize tin-doped indium oxide（ITO）nanoparticles,and the subsequent solution co-blend was employed to fabricate ITO/PVB nanocomposites.UV（Ultra-violet）-Vis（Visible）-NIR（Near Infrared） spectra show that the addition of ITO nano particles can significantly enhance the thermal insulating efficiency of ITO/PVB nanocomposites.With increasing ITO content,the thermal insulating efficiency is increased.UV is almost fully absorbed by all ITO/PVB nanocomposites.Vis transmittance-haze spectra reveal that ITO/PVB nanocomposites exhibit higher Vis transmittance over 71.3%and lower haze below 2%when ITO content is in the range of 0.1 wt%-0.7 wt%.The UV-Vis-NIR spectroscopy shows that,under the premise of over 70%transmittance to the visible light,the screening effect of the NIR can be enhanced by 80%with 0.7%ITO/PVB nanocomposite membrane compared with the undoped PVB.The thermal insulating tests indicate that,in comparison with the pure PVB film,nanocomposite films with 0.1 wt%-0.9 wt%ITO can reduce temperature by 3-8 ℃.The results show that this novel nanocomposite can be used for energy-saving glass.展开更多
The pechini method was used to synthesize antimony-doped tin oxide （ATO） nanoparticles, and the subsequent solution co-blend was employed to fabricate ATO/PVB nanocomposites. Uv-Vis-NIR spectra show that the additio...The pechini method was used to synthesize antimony-doped tin oxide （ATO） nanoparticles, and the subsequent solution co-blend was employed to fabricate ATO/PVB nanocomposites. Uv-Vis-NIR spectra show that the addition ofATO nano particles can significantly enhance the thermal insulating efficiency of ATO/PVB nanocomposites. With the increase of ATO content, the thermal insulating efficiency is increased. Uv is almost fully absorbed by all ATO/PVB nanocomposites. Vis transmittance-haze spectra reveal that ATO/ PVB nanocomposites exhibit higher Vis transmittance of over 72.7% and lower haze of below 2% when ATO content is in the range of 0.1 wt%-0.5 wt%. The thermal insulating tests indicate that in comparison with the pure PVB film, nanocomposite films with 0.1 wt%-0.5 wt% ATO can reduce temperature of 1-3 ℃, suggesting that this novel nanocomposite can be used for energy-saving glass.展开更多
基金Project supported by the National Natural Science Foundation of China(No.11572139)。
文摘The dielectrophoretic technology has been one of the most frequently applied microfluidic technologies to manipulate particles.The way of a combination of controlled electroosmotic micro-vortices and dielectrophoresis to manipulate particles of different sizes was proposed in our previous work.However,the thickness of the modulating electrode is neglected.In practice,when the thickness of the modulating electrode increases,the channel flux increases,while the ability of the vortex to capture the particles reduces.In this study,a new method combining the field-modulating electroosmotic vortex and the insulating post is proposed to improve the manipulating capability of the field-modulated electroosmotic vortex to particles.The results indicate that there are three great advantages as the insulating post is placed on the channel wall on the same side of the modulating electrode.First,the capturing ability of the vortex to particles is greater due to the reduction of channel flux and the squeezing effect.Second,the range of regulating channel flux to achieve the optimal separation is extended.Third,the separation efficiency improves since the perfect separation can be achieved at a higher flow rate.Furthermore,the effects of the location and the size of the insulating post on particle separation are analyzed in detail.The present work could provide the reference for the application of the DEP technology.
文摘Besides polyamidimide film and aromatic polyamidefiber paper which have been mentioned before, wehave also developed several other kinds of synthetic film and paperas polyester film, polyester fibre felt, polypropene film, and theircomposite materials. (a) Polyester film was exploited in China in early 60’s andput into mass production in middle 60’s. It is used mainly for slotinsulation of medium and small size motors as class E
基金supported by the National Natural Science Foundation of China(No.22278260)the Open Foundation of Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry(No.KFKT2021-14)Shaanxi Collaborative Innovation Center of Industrial Auxiliary Chemistry and Technology(No.KFKT2021-14).
文摘Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the smooth surface and chemical inertness of aramid fibers. Herein, AP are modified via the nacre-mimetic structure composed of aramid nanofibers (ANF) and carbonylated basalt nanosheets (CBSNs). This is achieved by impregnating AP into an ANF-CBSNs (A-C) suspension containing a 3D ANF framework as the matrix and 2D CBSNs as fillers. The resultant biomimetic composite papers (AP/A-C composite papers) exhibit a layered “brick-and-mortar” structure, demonstrating superior mechanical and electrical insulating properties. Notably, the tensile strength and breakdown strength of AP/A-C5 composite papers reach 39.69 MPa and 22.04 kV mm^(−1), respectively, representing a 155 % and 85 % increase compared to those of the control AP. These impressive properties are accompanied with excellent volume resistivity, exceptional dielectric properties, impressive folding endurance, outstanding heat insulation, and remarkable flame retardance. The nacre-inspired strategy offers an effective approach for producing highly promising electrical insulating papers for advanced electrical equipment.
文摘The present study focuses on the formulation of new composite consisting of plaster and raffia vinifera particle (RVP) with the purpose to reducing energy consumption. The aim of this study is to test this new compound as an insulating eco-material in building in a tropical climate. The composites samples were developed by mixing plaster with raffia vinifera particles (RVP) using three different sizes (1.6 mm, 2.5 mm and 4 mm). The effects of four different RVP incorporations rates (i.e., 0wt%, 5wt%;10wt%;15wt%) on physical, thermal, mechanicals properties of the composites were investigated. In addition, the use of the raffia vinifera particles and plaster based composite material as building envelopes thermal insulation material is studied by the habitable cell thermal behavior instrumentation. The results indicate that the incorporation of raffia vinifera particle leads to improve the new composite physical, mechanical and thermal properties. And the parametric analysis reveals that the sampling rate and the size of raffia vinifera particles are the most decisive factor to impact these properties, and to decreases in the thermal conductivity which leads to an improvement to the thermal resistance and energy savings. The best improvement of plaster composite was obtained at the raffia vinifera particles size between 2.5 and 4.0 mm loading of 5wt% (C95P5R) with a good ratio of thermo-physical-mechanical properties. Additionally, the habitable cell experimental thermal behavior, with the new raffia vinifera particles and plaster-based composite as thermal insulating material for building walls, gives an average damping of 4°C and 5.8°C in the insulated house interior environment respectively for cold and hot cases compared to the outside environment and the uninsulated house interior environment. The current study highlights that this mixture gives the new composite thermal insulation properties applicable in the eco-construction of habitats in tropical environments.
文摘The protection effectiveness of traditional Lightning Strike Protection(LSP)for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike,so a new protection method based on Air Breakdown and insulating adhesive layer(AB-LSP method)was designed to avoid it.In this study,a numerical method was developed to simulate the electrical breakdown,and verified by experiment results.Based on this method,a Finite Element Model(FEM)was established to investigate the effect of two factors(breakdown strength and initial ablation temperature of adhesive layer)on the LSP effectiveness.The results show that the breakdown strength impacts more to the ablation damage in composite than that of high-temperature resistance.Then,another FEM was established to predict the ablation damage by lightning strike in the AB-LSP method protected composite rotor blade.The mechanisms and potential key parameters(magnitude of lightning current,discharge channel location,adhesive layer thickness,and air gap width)that could affect the protection effectiveness were analyzed.The introduction of air breakdown changes the current conduction path and reduces explosion risk.After rational design,this method can offer effective lightning protection for composite helicopter rotor blade and other composite structures.
基金supported by the National Natural Science Foundation of China(No.22265021)the Aeronautical Science Foundation of China(No.2020Z056056003)。
文摘Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate radar stealth and thermal insulation capabilities.In this study,we have synthesized three-dimensional(3D)porous composites comprising V_(2)O_(3) nanoparticles embedded in Juncus effusus cellulose-derived carbon aerogels(VCA)using a self-templating method followed by high-temperature pyrolysis.The V_(2)O_(3) nanoparticles possess a 3D V-V framework and a relatively narrow bandgap,facilitating the Mott transition for enhanced conductivity.Furthermore,their uniform dispersion on hollow carbon tubes of Juncus effusus promotes efficient electron transfer and creates numerous heterogeneous interfaces.Consequently,VCA-2 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.92 dB at a matching thickness of 2.0mm and a maximum effective absorption bandwidth of 8.24 GHz at a thickness of 2.44mm,covering nearly half of the tested frequency range.Additionally,the radar cross-section reduction reaches a peak value of 29.40 dB m^(2),underscoring the excellent radar stealth capabilities of the material.In summary,VCA exhibits exceptional EMWA,radar stealth,and thermal insulation properties,highlighting its potential for multifunctional applications in EMWA material development.
文摘Semi insulating (SI) InP wafers of 50 and 75mm in diameter can be obtained by annealing of undoped liquid encapsulated Czochralski (LEC) InP at 930℃ for 80h.The annealing ambient can be pure phosphorus (PP) or iron phosphide (IP).The IP SI InP wafers have good electrical parameters and uniformity of whole wafer.However,PP SI InP wafers exhibit poor uniformity and electrical parameters.Photoluminescence which is subtle to deep defect appears in IP annealed semi insulating InP.Traps in annealed SI InP are detected by the spectroscopy of photo induced current transient.The results indicate that there are fewer traps in IP annealed undoped SI InP than those in as grown Fe doped and PP undoped SI InP.The formation mechanism of deep defects in annealed undoped InP is discussed.
文摘Device structure and fabrication process of SOI nMOSFET depleted partially are p roposed for multi-gigahertz RF applications.Many advanced techniques for deep submiron MOSFETs are incorporated into the proposed device.Main steps and condit ions in process are given in details,with simulation and optimization by using t he process simulator,Tsuprem4.Experiment results of 0.25μm SOI RF nMOSFET are i n consistence with simulated ones,and excellent or acceptable parameters of devi ce performance are obtained for multi-gigahertz RF applications.
基金supported by grants from the Deutsche Forschungsgemeinschaft(DFG)to MW.
文摘Oligodendrocytes and their cell-intrinsic gene regulatory network:Oligodendrocytes(OLs)are the myelinating glial cells of the vertebrate central nervous system.They are responsible for insulating neuronal axons with a lipid-rich myelin sheath,which enables the saltatory conduction of action potentials.During development,oligodendrocyte progenitor cells(OPCs)emerge from neural stem cells in the ventricular zone.They then proliferate,increase their number,and migrate to their final destination where they encounter unmyelinated neuronal axons and differentiate in a stepwise fashion into myelinating oligodendrocytes(mOLs)under the influence of environmental stimuli.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant Nos.XDB28000000 and XDB0460000)the Quantum Science and Technology-National Science and Technology Major Project (Grant No.2021ZD0302600)the National Key Research and Development Program of China(Grant No.2024YFA1409002)。
文摘The hybridization gap in strained-layer InAs/In_(x)Ga_(1−x) Sb quantum spin Hall insulators(QSHIs)is significantly enhanced compared to binary InAs/GaSb QSHI structures,where the typical indium composition,x,ranges between 0.2 and 0.4.This enhancement prompts a critical question:to what extent can quantum wells(QWs)be strained while still preserving the fundamental QSHI phase?In this study,we demonstrate the controlled molecular beam epitaxial growth of highly strained-layer QWs with an indium composition of x=0.5.These structures possess a substantial compressive strain within the In_(0.5)Ga_(0.5)Sb QW.Detailed crystal structure analyses confirm the exceptional quality of the resulting epitaxial films,indicating coherent lattice structures and the absence of visible dislocations.Transport measurements further reveal that the QSHI phase in InAs/In_(0.5)Ga_(0.5)Sb QWs is robust and protected by time-reversal symmetry.Notably,the edge states in these systems exhibit giant magnetoresistance when subjected to a modest perpendicular magnetic field.This behavior is in agreement with the𝑍2 topological property predicted by the Bernevig–Hughes–Zhang model,confirming the preservation of topologically protected edge transport in the presence of enhanced bulk strain.
基金supported by Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.2022QNRC001)the National Natural Science Foundation of China(No.52273053)the Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(No.21CGA41)。
文摘Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always struggle to balance mechanical properties and thermal insulation,resulting in their inability to meet the demands for both washing resistance and personal protection.Herein,inspired by the natural spring-like structures of cucumber tendrils,a superelastic and washable micro/nanofibrous sponge(MNFS)based on biomimetic helical fibers is directly prepared utilizing multiple-jet electrospinning technology for high-performance thermal insulation.By regulating the conductivity of polyvinylidene fluoride solution,multiple-jet ejection and multiple-stage whipping of jets are achieved,and further control of phase separation rates enables the rapid solidification of jets to form spring-like helical fibers,which are directly entangled to assemble MNFS.The resulting MNFS exhibits superelasticity that can withstand large tensile strain(200%),1000 cyclic tensile or compression deformations,and retain good resilience even in liquid nitrogen(-196℃).Furthermore,the MNFS shows efficient thermal insulation with low thermal conductivity(24.85 mW m^(-1)K^(-1)),close to the value of dry air,and remains structural stability even after cyclic washing.This work offers new possibilities for advanced fibrous sponges in transportation,environmental,and energy applications.
文摘Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectively.While these materials are affordable and display good thermal insulation,their unsustainable traits pertaining to an intensive manufacturing process and poor disposability are major concerns.Alternative insulation materials with enhanced sustainable characteristics are therefore being explored,and one type of material which has gained notable attention owing to its low carbon footprint and low thermal conductivity is natural fibre.Among the few review studies conducted on Natural Fibre Reinforced Composite(NFRC)insulation boards,the multitude of factors and underlying mechanisms affecting their thermal conductivity performance have been sparsely covered.This review study aimed to address this gap by providing a holistic overview of some of the key intrinsic and extrinsic factors affecting the thermal conductivity performance of NFRCs.Key intrinsic factors pertaining to the microstructural features and to the physico-mechanical traits of NFRCs,namely the fibre lumen size,α,and the fibre-matrix thermal conductivity ratio,β,respectively,were found to largely affect the Transverse Thermal Conductivity(TTC)in NFRC boards.Extrinsic factors,which were found to indirectly affect NFRCs’thermal conductivity,such as fibre pre-processing,composite manufacturing and environmental factors,were also covered.Some of the noteworthy NFRC featureswhich were found to affect their thermal conductivity are volume fraction of fibres,bulk density and porosity.The findings of this study highlight the need for additional research investigation to address the foregoing limitations observed in NFRC thermal insulation boards by considering appropriate natural fibres,composition and fabrication techniques.The fabrication of high-grade NFRC boards,which will display an optimum balance between enhanced thermal insulation and long-term durability performance,could further replace conventionally used thermal insulation boards in the modern building and construction industry.
基金supported by the Natural Science Basic Research Program of Shaanxi Province (Grant Nos.2024JC-JCQN-06 and2025JC-QYCX-006)the National Natural Science Foundation of China (Grant No.12474337)Chinese Academy of Sciences Project (Grant Nos.E4BA270100,E4Z127010F,E4Z6270100,and E53327020D)。
文摘In conventional higher-order topological insulators(HOTIs),the emergence of topological states can be explained by using the nonzero bulk polarization index.However,corner states emerge in HOTIs with incomplete boundary unit cells(i.e.,boundary defects)even though the bulk polarization is zero,which challenges the conventional understanding of HOTIs.Here,based on a Kekul´e-distorted honeycomb lattice with incomplete unit cells,we reveal that incomplete unit cells exhibit fractional charges through the analysis of Wannier centers by developing a compensation method and creating the concept of Wannier center domain(WCD)which is the smallest region that one Wannier center occupies.This method compensates for the missing parts of these boundary incomplete unit cells with additional WCDs to make them complete.The compensated WCDs automatically carry the corresponding charge,and this charge together with that of the incomplete unit cell constitutes the total charge of the complete unit cell after compensation.We conclude that the emergence of corner states is attributed to the filling anomaly,which is a fundamental mechanism.Our results refresh the understanding of HOTIs,especially those with structural discontinuities,and provide a novel design for topological states which have application value in producing optical functional devices.
基金supported by the National Natural Science Foundation of China (Nos. 51672064 and U1435206)
文摘Transition metal diborides based ultrahigh temperature ceramics(UHTCs) are characterized by high melting point, high strength and hardness, and high electrical and thermal conductivity. The high thermal conductivity arises from both electronic and phonon contributions. Thus electronic and phonon contributions must be controlled simultaneously in reducing the thermal conductivity of transition metal diborides. In high entropy(HE) materials, both electrons and phonons are scattered such that the thermal conductivity can significantly be reduced, which opens a new window to design novel insulating materials. Inspired by the high entropy effect, porous HE(Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)B2 is designed in this work as a new thermal insulting ultrahigh temperature material and is synthesized by an in-situ thermal borocarbon reduction/partial sintering process. The porous HE(Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)B2 possesses high porosity of 75.67%, pore size of 0.3–1.2 μm, homogeneous microstructure with small grain size of 400–800 nm, which results in low room temperature thermal diffusivity and thermal conductivity of 0.74 mm2 s^-1 and 0.51 W m^-1K^-1, respectively. In addition, it exhibits high compressive strength of3.93 MPa. The combination of these properties indicates that exploring porous high entropy ceramics such as porous HE(Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)B2 is a novel strategy in making UHTCs thermal insulating.
基金financially supported by the National Natural Science Foundation of China(51802208,1902113,51920105005)the China Postdoctoral Science Foundation(2017M611893)+2 种基金111 Projectthe Collaborative Innovation Centre of Suzhou Nano Science&Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Understanding the role of heat transfer between catalysts and substrates is important for enhancing photothermal CO2 catalysis.Herein,we investigate the effect of different substrates,including silicon wafers,glass slides and copper plates,on the photothermal catalytic performance of commercial Ni catalysts.The highest CO2 conversion rate and CO selectivity are observed in the catalyst film on the glass substrate,and this can be traced to a reduced catalyst-to-substrate heat transfer that increases the catalyst temperature under illumination.Our study reveals the important role of thermal management between catalysts and substrates in photothermal catalysis and sheds light on reactor design for efficient solar-to-chemical energy conversions.
基金supported by the Research Grants Council(GRF Projects:16205517,16209917,and 16200720)and Innovation and Technology Commission(ITS/012/19)of Hong Kong SAR.Technical assistance from the Materials Characterization and Preparation Facility(MCPF)the Advanced Engineering Material Facility(AEMF)the Environmental Central Facility(ENVF)at HKUST are also appreciated.
文摘With the mandate of worldwide carbon neutralization,pursuing comfortable living environment while consuming less energy is an enticing and unavoidable choice.Novel composite aerogels with super thermal insulation and high sunlight reflection are developed for energy-efficient buildings.A solvent-assisted freeze-casting strategy is used to produce boron nitride nanosheet/polyvinyl alcohol(BNNS/PVA)composite aerogels with a tailored alignment channel structure.The effects of acetone and BNNS fillers on microstructures and multifunctional properties of aerogels are investigated.The acetone in the PVA suspension enlarges the cell walls to suppress the shrinkage,giving rise to a lower density and a higher porosity,accompanied with much diminished heat conduction throughout the whole product.The addition of BNNS fillers creates whiskers in place of disconnected transverse ligaments between adjacent cell walls,further ameliorating the thermal insulation transverse to the cell wall direction.The resultant BNNS/PVA aerogel delivers an ultralow thermal conductivity of 23.5 mW m^(−1) K^(−1) in the transverse direction.The superinsulating aerogel presents both an infrared stealthy capability and a high solar reflectance of 93.8%over the whole sunlight wave-length,far outperforming commercial expanded polystyrene foams with reflective coatings.The anisotropic BNNS/PVA composite aerogel presents great potential for application in energy-saving buildings.
文摘In this paper, we investigate the single event transient （SET） occurring in partially depleted silicon-on-insulator （PDSOI） metal-oxide-semiconductor （MOS） devices irradiated by pulsed laser beams. Transient signal characteristics of a 0.18-p.m single MOS device, such as SET pulse width, pulse maximum, and collected charge, are measured and an- alyzed at wafer level. We analyze in detail the influences of supply voltage and pulse energy on the SET characteristics of the device under test （DUT）. The dependences of SET characteristics on drain-induced barrier lowering （DIBL） and the parasitic bipolar junction transistor （PBJT） are also discussed. These results provide a guide for radiation-hardened deep sub-micrometer PDSOI technology for space electronics applications.
基金supported by the National Natural Science Foundation of China(Nos.22175123,52122302,and 51991351)the 111 Project(No.B20001)Fundamental Research Funds for the Central Universities,and Open and Innovative Fund of Hubei Three Gorges Laboratory(Nos.2022LF2021 and SC213011).
文摘Bio-based polyurethane foam has attracted increasing attentions due to eco-friendliness and fossil feedstock issues.However,the inherent flammability limits its application in different fields.Herein,we demonstrate a green bio-based flame-retardant system to fabricate polyurethane foam composite with durable flame retardancy,smoke suppression,and thermal insulation property.In this system,the green bio-based polyol(VED)with good reactivity and compatibility plays a role of flame retardant and EG acts as a synergistic filler.As a result,the LOI value of foam composite increased to 30.5 vol.%and it achieved a V-0 rating in the UL-94 vertical burning test.Additionally,the peak heat release rate(pHRR)and the total smoke production(TSP)decreased by 66.1%and 63.4%,respectively.Furthermore,the foam composite maintained durable flame retardancy after accelerated thermal aging test,whose thermal-insulating property was maintained even after being treated in high-humidity environment with 85%R.H.for a week.This work provides a facile strategy for durable flame retardancy and long-term thermal insulation performance,and creates opportunities for the practical applications of bio-based foam composites.
基金Funded by State Key Laboratory of Silicate Building Materials(Wuhan University of Technology),China(No.SYSJJ2014-04)Hubei Science and Technology Department,China(No.Q20141006)
文摘Chemical co-precipitation method was used to synthesize tin-doped indium oxide（ITO）nanoparticles,and the subsequent solution co-blend was employed to fabricate ITO/PVB nanocomposites.UV（Ultra-violet）-Vis（Visible）-NIR（Near Infrared） spectra show that the addition of ITO nano particles can significantly enhance the thermal insulating efficiency of ITO/PVB nanocomposites.With increasing ITO content,the thermal insulating efficiency is increased.UV is almost fully absorbed by all ITO/PVB nanocomposites.Vis transmittance-haze spectra reveal that ITO/PVB nanocomposites exhibit higher Vis transmittance over 71.3%and lower haze below 2%when ITO content is in the range of 0.1 wt%-0.7 wt%.The UV-Vis-NIR spectroscopy shows that,under the premise of over 70%transmittance to the visible light,the screening effect of the NIR can be enhanced by 80%with 0.7%ITO/PVB nanocomposite membrane compared with the undoped PVB.The thermal insulating tests indicate that,in comparison with the pure PVB film,nanocomposite films with 0.1 wt%-0.9 wt%ITO can reduce temperature by 3-8 ℃.The results show that this novel nanocomposite can be used for energy-saving glass.
基金Funded by Wuhan Science and Technology Bureau,Hubei,China(No.200911011428)Hubei Science and Technology Department,China(No.2010EGA047)Key Laboratory of Green Preparation and Application for Functional Materials,Ministry of Education,China(No.2010EKLGPAFM018)
文摘The pechini method was used to synthesize antimony-doped tin oxide （ATO） nanoparticles, and the subsequent solution co-blend was employed to fabricate ATO/PVB nanocomposites. Uv-Vis-NIR spectra show that the addition ofATO nano particles can significantly enhance the thermal insulating efficiency of ATO/PVB nanocomposites. With the increase of ATO content, the thermal insulating efficiency is increased. Uv is almost fully absorbed by all ATO/PVB nanocomposites. Vis transmittance-haze spectra reveal that ATO/ PVB nanocomposites exhibit higher Vis transmittance of over 72.7% and lower haze of below 2% when ATO content is in the range of 0.1 wt%-0.5 wt%. The thermal insulating tests indicate that in comparison with the pure PVB film, nanocomposite films with 0.1 wt%-0.5 wt% ATO can reduce temperature of 1-3 ℃, suggesting that this novel nanocomposite can be used for energy-saving glass.
