Effective utilization of abundant solar energy for desalination of seawater and purification of wastewater is one of sustainable techniques for production of clean water,helping relieve global water resource shortage....Effective utilization of abundant solar energy for desalination of seawater and purification of wastewater is one of sustainable techniques for production of clean water,helping relieve global water resource shortage.Herein,we fabricate a vertically aligned reduced graphene oxide/Ti_(3)C_(2)T_(x)MXene(A-RGO/MX)hybrid hydrogel with aligned channels as an independent solar steam generation device for highly efficient solar steam generation.The vertically aligned channels,generated by a liquid nitrogen-assisted directional-freezing process,not only rapidly transport water upward to the evaporation surface for efficient solar steam generation,but also facilitate multiple reflections of solar light inside the channels for efficient solar light absorption.The deliberate slight reduction endows the RGO with plenty of polar groups,decreasing the water vaporization enthalpy effectively and hence accelerating water evaporation efficiently.The MXene sheets,infiltrated inside the A-RGO hydrogel on the basis of Marangoni effect,enhance light absorption capacity and photothermal conversion performance.As a result,the A-RGO/MX hybrid hydrogel achieves a water evaporation rate of 2.09 kg·m^(−2)·h^(−1)with a high conversion efficiency of 93.5%under 1-sun irradiation.Additionally,this photothermal conversion hydrogel rapidly desalinates seawater and purifies wastewater to generate clean water with outstanding ion rejection rates of above 99%for most ions.展开更多
Encoding information in light polarization is of great importance in facilitating optical data storage(ODS)for information security and data storage capacity escalation.However,despite recent advances in nanophotonic ...Encoding information in light polarization is of great importance in facilitating optical data storage(ODS)for information security and data storage capacity escalation.However,despite recent advances in nanophotonic techniques vastly en-hancing the feasibility of applying polarization channels,the data fidelity in reconstructed bits has been constrained by severe crosstalks occurring between varied polarization angles during data recording and reading process,which gravely hindered the utilization of this technique in practice.In this paper,we demonstrate an ultra-low crosstalk polarization-en-coding multilayer ODS technique for high-fidelity data recording and retrieving by utilizing a nanofibre-based nanocom-posite film involving highly aligned gold nanorods(GNRs).With parallelizing the gold nanorods in the recording medium,the information carrier configuration minimizes miswriting and misreading possibilities for information input and output,respectively,compared with its randomly self-assembled counterparts.The enhanced data accuracy has significantly im-proved the bit recall fidelity that is quantified by a correlation coefficient higher than 0.99.It is anticipated that the demon-strated technique can facilitate the development of multiplexing ODS for a greener future.展开更多
Aligned graphene nanoribbon (GNR) arrays have been made by unzipping of aligned single-walled and few-walled carbon nanotube (CNT) arrays. Nanotube unzipping was achieved by a polymer-protected Ar plasma etching metho...Aligned graphene nanoribbon (GNR) arrays have been made by unzipping of aligned single-walled and few-walled carbon nanotube (CNT) arrays. Nanotube unzipping was achieved by a polymer-protected Ar plasma etching method, and the resulting nanoribbon array can be transferred onto any chosen substrate. Atomic force microscope (AFM) imaging and Raman mapping on the same CNTs before and after unzipping confirmed that ~80% of CNTs were opened up to form single layer sub-10 nm GNRs. Electrical devices made from the GNRs (after annealing in H2 at high temperature) showed on/off current (Ion/Ioff) ratios up to 103 at room temperature, suggesting the semiconducting nature of the narrow GNRs. Novel GNR-GNR and GNR-CNT crossbars were fabricated by transferring GNR arrays across GNR and CNT arrays, respectively. The production of such ordered graphene nanoribbon architectures may allow for large scale integration of GNRs into nanoelectronics or optoelectronics.展开更多
Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing methodology.The aligned pattern and outstanding intrinsic ...Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing methodology.The aligned pattern and outstanding intrinsic properties render“metal-like”thermal conductivity of the SWCNT films,as well as excellent mechanical strength,flexibility,and hydrophobicity.Further,the aligned cellular microstructure promotes the electromagnetic interference(EMI)shielding ability of the SWCNTs,leading to excellent shielding effectiveness(SE)of~39 to 90 dB despite a density of only~0.6 g cm^(−3) at thicknesses of merely 1.5-24μm,respectively.An ultrahigh thickness-specific SE of 25693 dB mm^(−1) and an unprecedented normalized specific SE of 428222 dB cm^(2)g^(−1) are accomplished by the freestanding SWCNT films,significantly surpassing previously reported shielding materials.In addition to an EMI SE greater than 54 dB in an ultra-broadband frequency range of around 400 GHz,the films demonstrate excellent EMI shielding stability and reliability when subjected to mechanical deformation,chemical(acid/alkali/organic solvent)corrosion,and high-/low-temperature environments.The novel printed SWCNT films offer significant potential for practical applications in the aerospace,defense,precision components,and smart wearable electronics industries.展开更多
The soluble nature of polysulfide species created on the sulfur electrode has severely hampered the electrochemical performance of lithium-sulfur （Li-S） batteries. Trapping and anchoring polysulfides are promising a...The soluble nature of polysulfide species created on the sulfur electrode has severely hampered the electrochemical performance of lithium-sulfur （Li-S） batteries. Trapping and anchoring polysulfides are promising approaches for overcoming this issue. In this work, a mechanically robust, electrically conductive hybrid carbon aerogel （HCA） with aligned and interconnected pores was created and investigated as an interlayer for Li-S batteries. The hierarchical cross-linked networks constructed by graphene sheets and carbon nanotubes can act as an ＂internet＂ to capture the polysulfide, while the micro- and nano-pores inside the aerogel can facilitate quick penetration of the electrolyte and rapid transport of lithium ions. As advantages of the unique structure and excellent accommodation of the volume change of the active materials, a high specific capacity of 1,309 mAh.g-1 at 0.2 C was achieved for the assembled Li-S battery, coupled with good rate performance and long-term cycling stability （78% capacity retention after 600 cycles at 4 C）.展开更多
Extensive experimental studies on the heat transfer characteristics of two rows of aligned jet holes impinging on a concave surface in a wing leading edge were conducted, where50000 Rej 90000, 1.74 H/d 27.5, 66° ...Extensive experimental studies on the heat transfer characteristics of two rows of aligned jet holes impinging on a concave surface in a wing leading edge were conducted, where50000 Rej 90000, 1.74 H/d 27.5, 66° a 90°, and 13.2 r/d 42.03. The finding was that the heat transfer performance at the jet-impingement stagnation point with two rows of aligned jet holes was the same as that with a single row of jet holes or the middle row of three-row configurations when the circumferential angle of the two jet holes was larger than 30°. The attenuation coefficient distribution of the jet impingement heat transfer in the chordwise direction was so complicated that two zones were divided for a better analysis. It indicated that： the attenuation coefficient curve in the jet impingement zone exhibited an approximate upside-down bell shape with double peaks and a single valley; the attenuation coefficient curve in the non-jet impingement zone was like a half-bell shape, which was similar to that with three rows of aligned jet holes; the factors,including Rej, H/d and r/d, affected the attenuation coefficient value at the valley significantly.When r/d was increased from 30.75 to 42.03, the attenuation rates of attenuation coefficient increased only by 1.8%. Consequently, experimental data-based correlation equations of the Nusselt number for the heat transfer at the jet-impingement stagnation point and the distributionof the attenuation coefficient in the chordwise direction were acquired, which play an important role in designing the wing leading edge anti-icing system with two rows of aligned jet holes.展开更多
High-efficiency electromagnetic interference(EMI)shielding materials are of great importance for electronic equipment reliability,information security and human health.In this work,bidirectional aligned Ti_(3)C_(2)T_(...High-efficiency electromagnetic interference(EMI)shielding materials are of great importance for electronic equipment reliability,information security and human health.In this work,bidirectional aligned Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/CNF aerogels(BTFCA)were firstly assembled by bidirectional freezing and freeze-drying technique,and the BTFCA/epoxy nanocomposites with long-range aligned lamellar structures were then prepared by vacuum-assisted impregnation of epoxy resins.Benefitting from the successful construction of bidirectional aligned three-dimensional conductive networks and electromagnetic synergistic effect,when the mass fraction of Ti_(3)C_(2)T_(x) and Fe_(3)O_(4) are 2.96 and 1.48 wt%,BTFCA/epoxy nanocomposites show outstanding EMI shield-ing effectiveness of 79 dB,about 10 times of that of blended Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/epoxy(8 dB)nanocomposites with the same loadings of Ti_(3)C_(2)T_(x) and Fe_(3)O_(4).Meantime,the corresponding BTFCA/epoxy nanocomposites also present excellent thermal stability(T_(heat-resistance index) of 198.7℃)and mechanical properties(storage modulus of 9902.1 MPa,Young’s modulus of 4.51 GPa and hardness of 0.34 GPa).Our fabricated BTFCA/epoxy nanocomposites would greatly expand the applications of MXene and epoxy resins in the fields of information security,aerospace and weapon manufacturing,etc.展开更多
A detailed theoretical analysis of determining the sum of flexoelectric coefficients in nematic liquid crystals using the capacitance method is given. In the strong anchoring parallel aligned nematic （PAN） and hybri...A detailed theoretical analysis of determining the sum of flexoelectric coefficients in nematic liquid crystals using the capacitance method is given. In the strong anchoring parallel aligned nematic （PAN） and hybrid aligned nematic （HAN） cells, the dependences of the capacitance on the sum of flexoelectric coefficients and the applied voltage are obtained by numerical simulations, and the distributions of the director and the electric potential for different applied voltages and flexoelectric coefficients are also given. Based on this theoretical analysis, we propose an experimental design for measuring the capacitance of a liquid crystal cell using the improved precision LCR meter E4980A （Agilent）. Through comparing the experimental data with the simulated results, the sum of flexoeletric coefficients can be determined.展开更多
MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based o...MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene nanosheets.It is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the electrode.In this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying method.The bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport freely.The A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.展开更多
Porous copper(Cu)current collectors are regarded as a promising host for stabilizing lithium(Li)metal anodes but suffer from uncontrollable Li metal deposition due to the intrinsic lithiophobic nature of Cu.This study...Porous copper(Cu)current collectors are regarded as a promising host for stabilizing lithium(Li)metal anodes but suffer from uncontrollable Li metal deposition due to the intrinsic lithiophobic nature of Cu.This study proposes a vertically aligned Cu host with hyperbranched CuxO nanostructure to provide lithiophilic nucleation sites for homogeneous Li metal deposition.Specifically,the vertically aligned Cu nanostructure dramatically reduces the local current density and brings homogeneous Li‐ion flux.The lithiophilic hyperbranched CuxO nanostructure with a low nucleation barrier could induce homogeneous Li nucleation and growth.As a result,the Cu@CuxO nanostructured host exhibits a low nucleation overpotential of 44.3 mV and achieves highly electrochemical reversibility with high Coulombic efficiency of 98.33%in a half‐cell.The Cu@CuxO nanostructured electrode is capable of working under different current densities varying from 0.5 to 5 mA/cm2 in a symmetric cell.The assembled full cell coupling of the Li/Cu@CuxO composite anode with the LiFePO4 cathode manifests stable long‐term cycling life at 1 C.This study elaborates on the synergistic effect of electrode structure design and interfacial chemistry modification to regulate the Li deposition/dissolution behavior,thus exhibiting remarkable electrochemical performances for next‐generation Li‐metal batteries.展开更多
A new substrate,aligned Ag nanowires decorated with silver nanoparticle composite structure(AgNWs@AgNPs),was fabricated to investigate metalenhanced fluorescence(MEF) and its mechanism.The new composite structure was ...A new substrate,aligned Ag nanowires decorated with silver nanoparticle composite structure(AgNWs@AgNPs),was fabricated to investigate metalenhanced fluorescence(MEF) and its mechanism.The new composite structure was fabricated via a three-phase interface assembly method followed by SnCl2 sensitization and AgNO3 reduction process.The size and distribution of the nanoparticles on silver nanowires increased with the sensitization and reduction cycles.The formation of AgNPs on the surfaces of AgNWs was confirmed by multiple characterization methods including scanning electron microscopy(SEM),transmission electron microscope(TEM),atomic force microscopy(AFM) and X-ray diffraction(XRD).The results show that the fluorescence intensity of the poly(3-hexylthiophene)(P3HT) on the composite structure was greatly enhanced compared with that on bare glass substrate,and the intensity increased with the increase in particle sizes and density.The mechanism was basedo n the increase in excitation rate and the radiation decay rate.The new type of substrate could serve as a good and efficient MEF substrate for high-performance fluorescence-based devices.展开更多
With the rapid development of high-power-density electronic devices,interface thermal resistance has become a critical barrier for effective heat management in high-performance electronic products.Therefore,there is a...With the rapid development of high-power-density electronic devices,interface thermal resistance has become a critical barrier for effective heat management in high-performance electronic products.Therefore,there is an urgent demand for advanced thermal interface materials(TIMs)with high cross-plane thermal conductivity and excellent compressibility to withstand increasingly complex operating conditions.To achieve this aim,a promising strategy involves vertically arranging highly thermoconductive graphene on polymers.However,with the currently available methods,achieving a balance between low interfacial thermal resistance,bidirectional high thermal conductivity,and large-scale production is challenging.Herein,we prepared a graphene framework with continuous filler structures in in-plane and cross-plane directions by bonding corrugated graphene to planar graphene paper.The interface interaction between the graphene paper framework and polymer matrix was enhanced via surface functionalization to reduce the interface thermal resistance.The resulting three-dimensional thermal framework endows the polymer composite material with a cross-plane thermal conductivity of 14.4 W·m^(-1)·K^(-1)and in-plane thermal conductivity of 130W·m^(-1)·K^(-1)when the thermal filler loading is 10.1 wt%,with a thermal conductivity enhancement per 1 wt%filler loading of 831%,outperforming various graphene structures as fillers.Given its high thermal conductivity,low contact thermal resistance,and low compressive modulus,the developed highly thermoconductive composite material demonstrates superior performance in TIM testing compared with TFLEX-700,an advanced commercial TIM,effectively solving the interfacial heat transfer issues in electronic systems.This novel filler structure framework also provides a solution for achieving a balance between efficient thermal management and ease of processing.展开更多
Autografting is the gold standard for surgical repair of nerve defects>5 mm in length;however,autografting is associated with potential complications at the nerve donor site.As an alternative,nerve guidance conduit...Autografting is the gold standard for surgical repair of nerve defects>5 mm in length;however,autografting is associated with potential complications at the nerve donor site.As an alternative,nerve guidance conduits may be used.The ideal conduit should be flexible,resistant to kinks and lumen collapse,and provide physical cues to guide nerve regeneration.We designed a novel flexible conduit using electrospinning technology to create fibers on the innermost surface of the nerve guidance conduit and employed melt spinning to align them.Subsequently,we prepared disordered electrospun fibers outside the aligned fibers and helical melt-spun fibers on the outer wall of the electrospun fiber lumen.The presence of aligned fibers on the inner surface can promote the extension of nerve cells along the fibers.The helical melt-spun fibers on the outer surface can enhance resistance to kinking and compression and provide stability.Our novel conduit promoted nerve regeneration and functional recovery in a rat sciatic nerve defect model,suggesting that it has potential for clinical use in human nerve injuries.展开更多
Multi-phase vertically aligned nanocomposite(MP-VAN)thin films represent a promising avenue for achieving complex multifunctionality,exploring novel interfacial phenomena,and enabling complex metamaterial designs and ...Multi-phase vertically aligned nanocomposite(MP-VAN)thin films represent a promising avenue for achieving complex multifunctionality,exploring novel interfacial phenomena,and enabling complex metamaterial designs and exploration.In this study,a novel self-assembled all-oxides three-phase VAN system was conceptualized and fabricated utilizing pulsed laser deposition(PLD)with a single composite target.Detailed microstructural analysis reveals the presence of three distinct phases:LiNbO_(3),CeO_(2-x),and LiNbCe_(1-x)O_(y)within the MP-VAN films.Subsequently,ferroelectric,dielectric,optical anisotropy,and magnetic properties were systematically investigated to showcase the multifunctionality inherent in these films.This work presents a pioneering approach to designing and realizing MP-VAN systems,and opens up opportunities for tailoring the complex three-dimensional(3D)physical properties and property coupling of VAN films towards diverse device applications.展开更多
基金support from the National Natural Science Foundation of China(Nos.51773008,51533001,and U1905217)the Fundamental Research Funds for the Central Universities(No.XK1802).
文摘Effective utilization of abundant solar energy for desalination of seawater and purification of wastewater is one of sustainable techniques for production of clean water,helping relieve global water resource shortage.Herein,we fabricate a vertically aligned reduced graphene oxide/Ti_(3)C_(2)T_(x)MXene(A-RGO/MX)hybrid hydrogel with aligned channels as an independent solar steam generation device for highly efficient solar steam generation.The vertically aligned channels,generated by a liquid nitrogen-assisted directional-freezing process,not only rapidly transport water upward to the evaporation surface for efficient solar steam generation,but also facilitate multiple reflections of solar light inside the channels for efficient solar light absorption.The deliberate slight reduction endows the RGO with plenty of polar groups,decreasing the water vaporization enthalpy effectively and hence accelerating water evaporation efficiently.The MXene sheets,infiltrated inside the A-RGO hydrogel on the basis of Marangoni effect,enhance light absorption capacity and photothermal conversion performance.As a result,the A-RGO/MX hybrid hydrogel achieves a water evaporation rate of 2.09 kg·m^(−2)·h^(−1)with a high conversion efficiency of 93.5%under 1-sun irradiation.Additionally,this photothermal conversion hydrogel rapidly desalinates seawater and purifies wastewater to generate clean water with outstanding ion rejection rates of above 99%for most ions.
基金financial supports from the National Natural Science Foundation of China(Grant Nos.62174073,61875073,11674130,91750110 and 61522504)the National Key R&D Program of China(Grant No.2018YFB1107200)+3 种基金the Guangdong Provincial Innovation and Entrepren-eurship Project(Grant No.2016ZT06D081)the Natural Science Founda-tion of Guangdong Province,China(Grant Nos.2016A030306016 and 2016TQ03X981)the Pearl River Nova Program of Guangzhou(Grant No.201806010040)the Technology Innovation and Development Plan of Yantai(Grant No.2020XDRH095).
文摘Encoding information in light polarization is of great importance in facilitating optical data storage(ODS)for information security and data storage capacity escalation.However,despite recent advances in nanophotonic techniques vastly en-hancing the feasibility of applying polarization channels,the data fidelity in reconstructed bits has been constrained by severe crosstalks occurring between varied polarization angles during data recording and reading process,which gravely hindered the utilization of this technique in practice.In this paper,we demonstrate an ultra-low crosstalk polarization-en-coding multilayer ODS technique for high-fidelity data recording and retrieving by utilizing a nanofibre-based nanocom-posite film involving highly aligned gold nanorods(GNRs).With parallelizing the gold nanorods in the recording medium,the information carrier configuration minimizes miswriting and misreading possibilities for information input and output,respectively,compared with its randomly self-assembled counterparts.The enhanced data accuracy has significantly im-proved the bit recall fidelity that is quantified by a correlation coefficient higher than 0.99.It is anticipated that the demon-strated technique can facilitate the development of multiplexing ODS for a greener future.
基金This work was supported by MARCO-MSD,Intel,ONR and graphene-MURI.
文摘Aligned graphene nanoribbon (GNR) arrays have been made by unzipping of aligned single-walled and few-walled carbon nanotube (CNT) arrays. Nanotube unzipping was achieved by a polymer-protected Ar plasma etching method, and the resulting nanoribbon array can be transferred onto any chosen substrate. Atomic force microscope (AFM) imaging and Raman mapping on the same CNTs before and after unzipping confirmed that ~80% of CNTs were opened up to form single layer sub-10 nm GNRs. Electrical devices made from the GNRs (after annealing in H2 at high temperature) showed on/off current (Ion/Ioff) ratios up to 103 at room temperature, suggesting the semiconducting nature of the narrow GNRs. Novel GNR-GNR and GNR-CNT crossbars were fabricated by transferring GNR arrays across GNR and CNT arrays, respectively. The production of such ordered graphene nanoribbon architectures may allow for large scale integration of GNRs into nanoelectronics or optoelectronics.
基金support of National Key R&D Program of China (2021YFB3502500)Provincial Key Research and Development Program of Shandong (2019JZZY010312, 2021ZLGX01)+4 种基金Natural Science Foundation of Shandong Province (2022HYYQ-014)New 20 Funded Programs for Universities of Jinan (2021GXRC036)Qilu Young Scholar Program of Shandong University (31370082163127)the assistance of Shandong University Testing and Manufacturing Center for Advanced Materialssupport from the National Science Foundation Engineering Research Center for Power Optimization of Electro Thermal Systems (POETS) under Grant No. EEC 1449548.
文摘Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing methodology.The aligned pattern and outstanding intrinsic properties render“metal-like”thermal conductivity of the SWCNT films,as well as excellent mechanical strength,flexibility,and hydrophobicity.Further,the aligned cellular microstructure promotes the electromagnetic interference(EMI)shielding ability of the SWCNTs,leading to excellent shielding effectiveness(SE)of~39 to 90 dB despite a density of only~0.6 g cm^(−3) at thicknesses of merely 1.5-24μm,respectively.An ultrahigh thickness-specific SE of 25693 dB mm^(−1) and an unprecedented normalized specific SE of 428222 dB cm^(2)g^(−1) are accomplished by the freestanding SWCNT films,significantly surpassing previously reported shielding materials.In addition to an EMI SE greater than 54 dB in an ultra-broadband frequency range of around 400 GHz,the films demonstrate excellent EMI shielding stability and reliability when subjected to mechanical deformation,chemical(acid/alkali/organic solvent)corrosion,and high-/low-temperature environments.The novel printed SWCNT films offer significant potential for practical applications in the aerospace,defense,precision components,and smart wearable electronics industries.
基金This work was financially supported by the National Natural Science Foundation of China （Nos. 21376113, 51125011, and 51433001）, Natural Science Foundation of Jiangsu Province （No. BK20150238）, and the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘The soluble nature of polysulfide species created on the sulfur electrode has severely hampered the electrochemical performance of lithium-sulfur （Li-S） batteries. Trapping and anchoring polysulfides are promising approaches for overcoming this issue. In this work, a mechanically robust, electrically conductive hybrid carbon aerogel （HCA） with aligned and interconnected pores was created and investigated as an interlayer for Li-S batteries. The hierarchical cross-linked networks constructed by graphene sheets and carbon nanotubes can act as an ＂internet＂ to capture the polysulfide, while the micro- and nano-pores inside the aerogel can facilitate quick penetration of the electrolyte and rapid transport of lithium ions. As advantages of the unique structure and excellent accommodation of the volume change of the active materials, a high specific capacity of 1,309 mAh.g-1 at 0.2 C was achieved for the assembled Li-S battery, coupled with good rate performance and long-term cycling stability （78% capacity retention after 600 cycles at 4 C）.
基金supported by the National Natural Science Foundation of China (No. 51206008)
文摘Extensive experimental studies on the heat transfer characteristics of two rows of aligned jet holes impinging on a concave surface in a wing leading edge were conducted, where50000 Rej 90000, 1.74 H/d 27.5, 66° a 90°, and 13.2 r/d 42.03. The finding was that the heat transfer performance at the jet-impingement stagnation point with two rows of aligned jet holes was the same as that with a single row of jet holes or the middle row of three-row configurations when the circumferential angle of the two jet holes was larger than 30°. The attenuation coefficient distribution of the jet impingement heat transfer in the chordwise direction was so complicated that two zones were divided for a better analysis. It indicated that： the attenuation coefficient curve in the jet impingement zone exhibited an approximate upside-down bell shape with double peaks and a single valley; the attenuation coefficient curve in the non-jet impingement zone was like a half-bell shape, which was similar to that with three rows of aligned jet holes; the factors,including Rej, H/d and r/d, affected the attenuation coefficient value at the valley significantly.When r/d was increased from 30.75 to 42.03, the attenuation rates of attenuation coefficient increased only by 1.8%. Consequently, experimental data-based correlation equations of the Nusselt number for the heat transfer at the jet-impingement stagnation point and the distributionof the attenuation coefficient in the chordwise direction were acquired, which play an important role in designing the wing leading edge anti-icing system with two rows of aligned jet holes.
基金The authors are grateful for the supports from the National Natural Science Foundation of China(U21A2093 and 52203100)Y.L.Zhang would like to thank the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2021107)。
文摘High-efficiency electromagnetic interference(EMI)shielding materials are of great importance for electronic equipment reliability,information security and human health.In this work,bidirectional aligned Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/CNF aerogels(BTFCA)were firstly assembled by bidirectional freezing and freeze-drying technique,and the BTFCA/epoxy nanocomposites with long-range aligned lamellar structures were then prepared by vacuum-assisted impregnation of epoxy resins.Benefitting from the successful construction of bidirectional aligned three-dimensional conductive networks and electromagnetic synergistic effect,when the mass fraction of Ti_(3)C_(2)T_(x) and Fe_(3)O_(4) are 2.96 and 1.48 wt%,BTFCA/epoxy nanocomposites show outstanding EMI shield-ing effectiveness of 79 dB,about 10 times of that of blended Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/epoxy(8 dB)nanocomposites with the same loadings of Ti_(3)C_(2)T_(x) and Fe_(3)O_(4).Meantime,the corresponding BTFCA/epoxy nanocomposites also present excellent thermal stability(T_(heat-resistance index) of 198.7℃)and mechanical properties(storage modulus of 9902.1 MPa,Young’s modulus of 4.51 GPa and hardness of 0.34 GPa).Our fabricated BTFCA/epoxy nanocomposites would greatly expand the applications of MXene and epoxy resins in the fields of information security,aerospace and weapon manufacturing,etc.
基金supported by the National Natural Science Foundation of China(Grant Nos.11274088,11374087,and 11304074)the Natural Science Foundation of Hebei Province,China(Grant No.A2014202123)+2 种基金the Research Project of Hebei Education Department,China(Grant Nos.Z2012061 and QN2014130)the Science and Technology Plan Project of Hebei Province,China(Grant No.134576260)the Key Subject Construction Project of Hebei Province University,China
文摘A detailed theoretical analysis of determining the sum of flexoelectric coefficients in nematic liquid crystals using the capacitance method is given. In the strong anchoring parallel aligned nematic （PAN） and hybrid aligned nematic （HAN） cells, the dependences of the capacitance on the sum of flexoelectric coefficients and the applied voltage are obtained by numerical simulations, and the distributions of the director and the electric potential for different applied voltages and flexoelectric coefficients are also given. Based on this theoretical analysis, we propose an experimental design for measuring the capacitance of a liquid crystal cell using the improved precision LCR meter E4980A （Agilent）. Through comparing the experimental data with the simulated results, the sum of flexoeletric coefficients can be determined.
基金financially supported by the National Natural Science Foundation of China(No.52002354)China Postdoctoral Science Foundation(No.2020M672256)。
文摘MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene nanosheets.It is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the electrode.In this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying method.The bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport freely.The A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.
基金Research Startup Fund from NJUPT,Grant/Award Numbers:NY220085,NY220069,NY221128National Natural Science Foundation of China,Grant/Award Numbers:22201135,22203046,52102265,91963119+3 种基金China Postdoctoral Science Foundation,Grant/Award Number:2020M681681Project of State Key Laboratory of Organic Electronics and Information Displays,Nanjing University of Posts and Telecommunications,Grant/Award Numbers:GDX2022010010,GZR2022010017Priority Academic Program Development of Jiangsu Higher Education Institutions,Grant/Award Number:PAPD,YX030003Natural Science Foundation of Jiangsu Province,Grant/Award Numbers:BK20210604,BK20220385。
文摘Porous copper(Cu)current collectors are regarded as a promising host for stabilizing lithium(Li)metal anodes but suffer from uncontrollable Li metal deposition due to the intrinsic lithiophobic nature of Cu.This study proposes a vertically aligned Cu host with hyperbranched CuxO nanostructure to provide lithiophilic nucleation sites for homogeneous Li metal deposition.Specifically,the vertically aligned Cu nanostructure dramatically reduces the local current density and brings homogeneous Li‐ion flux.The lithiophilic hyperbranched CuxO nanostructure with a low nucleation barrier could induce homogeneous Li nucleation and growth.As a result,the Cu@CuxO nanostructured host exhibits a low nucleation overpotential of 44.3 mV and achieves highly electrochemical reversibility with high Coulombic efficiency of 98.33%in a half‐cell.The Cu@CuxO nanostructured electrode is capable of working under different current densities varying from 0.5 to 5 mA/cm2 in a symmetric cell.The assembled full cell coupling of the Li/Cu@CuxO composite anode with the LiFePO4 cathode manifests stable long‐term cycling life at 1 C.This study elaborates on the synergistic effect of electrode structure design and interfacial chemistry modification to regulate the Li deposition/dissolution behavior,thus exhibiting remarkable electrochemical performances for next‐generation Li‐metal batteries.
基金financially supported by the National Natural Science Foundation of China (No.51273048)Science and Technology Planning Project of Guangdong Province (No.2017B090915004)the Open Operation of Guangdong Provincial Key Laboratory of Advanced Coatings Research and Development (No.2017B030314105)
文摘A new substrate,aligned Ag nanowires decorated with silver nanoparticle composite structure(AgNWs@AgNPs),was fabricated to investigate metalenhanced fluorescence(MEF) and its mechanism.The new composite structure was fabricated via a three-phase interface assembly method followed by SnCl2 sensitization and AgNO3 reduction process.The size and distribution of the nanoparticles on silver nanowires increased with the sensitization and reduction cycles.The formation of AgNPs on the surfaces of AgNWs was confirmed by multiple characterization methods including scanning electron microscopy(SEM),transmission electron microscope(TEM),atomic force microscopy(AFM) and X-ray diffraction(XRD).The results show that the fluorescence intensity of the poly(3-hexylthiophene)(P3HT) on the composite structure was greatly enhanced compared with that on bare glass substrate,and the intensity increased with the increase in particle sizes and density.The mechanism was basedo n the increase in excitation rate and the radiation decay rate.The new type of substrate could serve as a good and efficient MEF substrate for high-performance fluorescence-based devices.
基金financially supported by the National Natural Science Foundation of China(Nos.52130303,52327802 and 52173078)National Key R&D Program of China(No.2022YFB3805702)。
文摘With the rapid development of high-power-density electronic devices,interface thermal resistance has become a critical barrier for effective heat management in high-performance electronic products.Therefore,there is an urgent demand for advanced thermal interface materials(TIMs)with high cross-plane thermal conductivity and excellent compressibility to withstand increasingly complex operating conditions.To achieve this aim,a promising strategy involves vertically arranging highly thermoconductive graphene on polymers.However,with the currently available methods,achieving a balance between low interfacial thermal resistance,bidirectional high thermal conductivity,and large-scale production is challenging.Herein,we prepared a graphene framework with continuous filler structures in in-plane and cross-plane directions by bonding corrugated graphene to planar graphene paper.The interface interaction between the graphene paper framework and polymer matrix was enhanced via surface functionalization to reduce the interface thermal resistance.The resulting three-dimensional thermal framework endows the polymer composite material with a cross-plane thermal conductivity of 14.4 W·m^(-1)·K^(-1)and in-plane thermal conductivity of 130W·m^(-1)·K^(-1)when the thermal filler loading is 10.1 wt%,with a thermal conductivity enhancement per 1 wt%filler loading of 831%,outperforming various graphene structures as fillers.Given its high thermal conductivity,low contact thermal resistance,and low compressive modulus,the developed highly thermoconductive composite material demonstrates superior performance in TIM testing compared with TFLEX-700,an advanced commercial TIM,effectively solving the interfacial heat transfer issues in electronic systems.This novel filler structure framework also provides a solution for achieving a balance between efficient thermal management and ease of processing.
基金supported by the National Natural Science Foundation of China,No.82202718the Natural Science Foundation of Beijing,No.L212050the China Postdoctoral Science Foundation,Nos.2019M664007,2021T140793(all to ZL)。
文摘Autografting is the gold standard for surgical repair of nerve defects>5 mm in length;however,autografting is associated with potential complications at the nerve donor site.As an alternative,nerve guidance conduits may be used.The ideal conduit should be flexible,resistant to kinks and lumen collapse,and provide physical cues to guide nerve regeneration.We designed a novel flexible conduit using electrospinning technology to create fibers on the innermost surface of the nerve guidance conduit and employed melt spinning to align them.Subsequently,we prepared disordered electrospun fibers outside the aligned fibers and helical melt-spun fibers on the outer wall of the electrospun fiber lumen.The presence of aligned fibers on the inner surface can promote the extension of nerve cells along the fibers.The helical melt-spun fibers on the outer surface can enhance resistance to kinking and compression and provide stability.Our novel conduit promoted nerve regeneration and functional recovery in a rat sciatic nerve defect model,suggesting that it has potential for clinical use in human nerve injuries.
基金supported by Shenzhen Science and Technology Program(No.JCYJ20210324133610028)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515012594).
文摘Multi-phase vertically aligned nanocomposite(MP-VAN)thin films represent a promising avenue for achieving complex multifunctionality,exploring novel interfacial phenomena,and enabling complex metamaterial designs and exploration.In this study,a novel self-assembled all-oxides three-phase VAN system was conceptualized and fabricated utilizing pulsed laser deposition(PLD)with a single composite target.Detailed microstructural analysis reveals the presence of three distinct phases:LiNbO_(3),CeO_(2-x),and LiNbCe_(1-x)O_(y)within the MP-VAN films.Subsequently,ferroelectric,dielectric,optical anisotropy,and magnetic properties were systematically investigated to showcase the multifunctionality inherent in these films.This work presents a pioneering approach to designing and realizing MP-VAN systems,and opens up opportunities for tailoring the complex three-dimensional(3D)physical properties and property coupling of VAN films towards diverse device applications.
