Carbon nano additives(CNAs)are critical to achieving the unique properties of functionalized composites,however,controlling the dispersion of CNAs in material matrix is always a challenging task.In this study,a simple...Carbon nano additives(CNAs)are critical to achieving the unique properties of functionalized composites,however,controlling the dispersion of CNAs in material matrix is always a challenging task.In this study,a simple atomization approach was successfully developed to promote the dispersion efficiency of graphene nanoplatelets(GNPs)in cement composites.This atomization approach can be integrated with the direct,indirect and combined ultrasonic stirrings in a homemade automatic stirring-atomization device.Mechanical and microstructure tests were performed on hardened cement pastes blended with GNPs in different stirring and mixing approaches.Results show that the direct ultrasonic stirrings enabled more homogeneous dispersions of GNP particles with a smaller size for a longer duration.The atomized droplets with the mean size of~100μm largely mitigated GNPs’agglomerations.Monolayer GNPs were observed in the cement matrix with the strength gain by up to 54%,and the total porosity decrease by 21%in 0.3 wt%GNPs dosage.The greatly enhanced dispersion efficiency of GNPs in cement also raised the cement hydration.This work provides an effective and manpower saving technique toward dispersing CNAs in engineering materials with great industrialization prospects.展开更多
Zearalenone(ZEN)is a widely distributed mycotoxin that frequently contaminates crops and animal feed.ZEN can cause serious health problems in livestock and humans alike,leading to great economic losses in the food ind...Zearalenone(ZEN)is a widely distributed mycotoxin that frequently contaminates crops and animal feed.ZEN can cause serious health problems in livestock and humans alike,leading to great economic losses in the food industry and livestock farming.Therefore,approaches for efficient ZEN decontamination in food and feed are urgently needed.Traditional physical and chemical methods may decrease the nutritional quality of food and palatability of feed,or leading to residues and safety concerns.By contrast,biological methods for the removal or degradation of ZEN overcome these problems,especially for biological degradation by microorganisms and specific enzymes extracted from strains that can convert ZEN to less toxic or even completely harmless products.In this review,we comprehensively describe methods for ZEN degradation,focusing especially on biological strategies.Finally,emerging strategies and advice on remaining challenges in biodegradation research are also briefly discussed.展开更多
Two-dimensional(2D)semiconductors isoelectronic to phosphorene have been drawing much attention recently due to their promising applications for next-generation(opt)electronics.This family of 2D materials contains mor...Two-dimensional(2D)semiconductors isoelectronic to phosphorene have been drawing much attention recently due to their promising applications for next-generation(opt)electronics.This family of 2D materials contains more than 400members,including(a)elemental group-V materials,(b)binary III–VII and IV–VI compounds,(c)ternary III–VI–VII and IV–V–VII compounds,making materials design with targeted functionality unprecedentedly rich and extremely challenging.To shed light on rational functionality design with this family of materials,we systemically explore their fundamental band gaps and alignments using hybrid density functional theory(DFT)in combination with machine learning.First,calculations are performed using both the Perdew–Burke–Ernzerhof exchange–correlation functional within the generalgradient-density approximation(GGA-PBE)and Heyd–Scuseria–Ernzerhof hybrid functional(HSE)as a reference.We find this family of materials share similar crystalline structures,but possess largely distributed band-gap values ranging approximately from 0 eV to 8 eV.Then,we apply machine learning methods,including linear regression(LR),random forest regression(RFR),and support vector machine regression(SVR),to build models for the prediction of electronic properties.Among these models,SVR is found to have the best performance,yielding the root mean square error(RMSE)less than 0.15 eV for the predicted band gaps,valence-band maximums(VBMs),and conduction-band minimums(CBMs)when both PBE results and elemental information are used as features.Thus,we demonstrate that the machine learning models are universally suitable for screening 2D isoelectronic systems with targeted functionality,and especially valuable for the design of alloys and heterogeneous systems.展开更多
High-purity magnetic CoNi submicrospherical chains, each of length 20 μm - 30 μm and self-assembled from fcc-phase CoNi submicrospheres of average diameter 800 nm, are synthesized via a surfactant-assisted solvother...High-purity magnetic CoNi submicrospherical chains, each of length 20 μm - 30 μm and self-assembled from fcc-phase CoNi submicrospheres of average diameter 800 nm, are synthesized via a surfactant-assisted solvothermal route without the aid of nucleation agent. The effects of surfactant and reducing agent on the morphology and size of the CoNi chains are studied, and a possible growth mechanism for the CoNi chains is proposed. The CoNi chains show ferromagnetic characteristics with a similarly small saturation magnetization of 104.1 emu/g and a larger coercivity of 150 Oe at room temperature compared to the monodispersed CoNi submicrospheres of 105 emu/g and 34 Oe as a result of the increased shape anisotropy.展开更多
For a two-dimensional ultra-cold Fermi superfluid with an effective static magnetic impurity, we theoretically investigated the variation of the Yu–Shiba–Rusinov(YSR) bound state in the Bardeen–Cooper–Schrieffer(B...For a two-dimensional ultra-cold Fermi superfluid with an effective static magnetic impurity, we theoretically investigated the variation of the Yu–Shiba–Rusinov(YSR) bound state in the Bardeen–Cooper–Schrieffer(BCS) to Bose–Einstein condensation(BEC) crossover regime.Within the framework of mean-field theory, analytical results of the YSR bound state energy were obtained as a function of the interaction parameters.First, when the background Fermi superfluid system stays in the weakly interacting BCS regime, we found that the YSR bound state energy is linearly dependent on the gap parameter with its coefficient slightly different from previous results.Second, we discovered re-entrance phenomena for the YSR state and an upper bound of the strength of the interaction between the paired atoms.By carefully analyzing the bound state energy as a function of the interaction parameters, we obtained a phase diagram showing the existence of the YSR state.Finally, we concluded that the re-entrance phenomena and the critical point can be easily experimentally detected through measurement of radio-frequency spectroscopy and density of states using current experimental techniques.展开更多
Structural and magnetic properties of Nd15Fe70T15Nδ(T=V, Mo) alloys, made by mechanical alloying (MA) followed by heat-treatment and nitriding, have been investigated systematically.Effects of annealing temperature o...Structural and magnetic properties of Nd15Fe70T15Nδ(T=V, Mo) alloys, made by mechanical alloying (MA) followed by heat-treatment and nitriding, have been investigated systematically.Effects of annealing temperature on the structure and magnetic properties of the materials were studied by means of X-ray diffraction, AC susceptibility and high field magnetization measurements. Under pure argon atmosphere, the optimum temperatures for the heat treatment are found to be 75 and 850℃ for Nd15Fe7015Nδ and Nd15Fe70Mo15Nδ respectively. Correspondingly, the following magnetic properties are achieved : (1) Nd15Fe70V15Nδ:Br=0.63 T,,HC=8.01kA/cm (10.1 kOe), (BH )max=50.3 kJ/m3 (6 32 MGOe), (2) Nd15Fe70Mo15Nδ :Br=0.42 T. iHc=5.6 kA/cm (7.4 kOe), (BH )max=26.6 kJ/m3 (3.34 MGOe)展开更多
Exchange interaction plays an important role on magnetic properties of nanocomposite magnets consisting of hard- and soft-magnetic phases. Here the exchange interaction in the Sm-Co/Co （and Fe65Co35） magnetic films ...Exchange interaction plays an important role on magnetic properties of nanocomposite magnets consisting of hard- and soft-magnetic phases. Here the exchange interaction in the Sm-Co/Co （and Fe65Co35） magnetic films was characterized by measuring static （mr（H）） and demagnetized （md（H）） remanence curves. According to conventional method： δm（H）=md（H） - [1 - 2mr（H）], the exchange interaction was evaluated. The switching fields H′p and Hp, at which static （mr（H）） and demagnetized （md（H）） remanence show the fastest change, were identified. The relative ratio η=Hp-H′p/Hp of switching fields H′p and Hp has a linear relationship with the maximum value δmmax of δm（H） curves, proposing an alternative way to characterize the exchange interaction.展开更多
Purpose: The aim of the study was to evaluate the feasibility of a new venous-thrombus aspiration and autologous blood(auto-blood) reinfusion system.Materials and methods: We constructed the venous model from polyviny...Purpose: The aim of the study was to evaluate the feasibility of a new venous-thrombus aspiration and autologous blood(auto-blood) reinfusion system.Materials and methods: We constructed the venous model from polyvinyl chloride(PVC) tubes and three-way unions using a fresh clot of chicken blood as the venous thrombus. Eight French and 12 F aspiration catheters were used to aspirate the thrombus in the right–pulmonary-artery model, 8 French and 14 F aspiration catheters were used in the inferior–vena cava model, and 8 French and 10 F aspiration catheters were used in the left-–iliofemoral-vein model. A thrombus filtration and auto-blood reinfusion bottle was used to filter the thrombus and re-infuse auto-blood. We evaluated the thrombus aspiration capability of each catheter by comparing preaspirated with the post-aspirated thrombus volume, and we evaluated the difference in aspiration capability between the two catheters in each model by comparing their thrombus aspiration rates. We used Student’s t-test for statistical analysis.Results: Differences between pre-aspirated and post-aspirated thrombus volumes for each catheter were insignificant, as were those between the thrombus aspiration rates of the two catheters in each venous model. Using the thrombus aspiration and auto-blood reinfusion system, each aspiration catheter could fluently aspirate the thrombus out of the venous model.Conclusion: In this study, we designed a new venous-thrombus aspiration system. This system could be used to aspirate acute venous thrombi and re-infuse autologous blood.展开更多
A brief review on recent advances in the area of the magnetic nanocapsules is given. The most applicable nanoencapsulation procedures are introduced, which include： （1） physical techniques such as arc-discharge, ev...A brief review on recent advances in the area of the magnetic nanocapsules is given. The most applicable nanoencapsulation procedures are introduced, which include： （1） physical techniques such as arc-discharge, evaporating, etc.; （2） chemical techniques such as chemical vapor deposition, solid-state reactions, etc. The structure and magnetic properties of various nanocapsules with different core/shell structures are studied in details, for possibly applications in magnetic recording, magnetic refrigerator, magnetic fluids, superconductors and medicine.展开更多
The fully-leaky guided wave technique has been used to study the reflective 90? MTN liquid crystal cell used for LCOS. The cell is comprised of upper substrate with indium-tin-oxide coating and lower substrate with al...The fully-leaky guided wave technique has been used to study the reflective 90? MTN liquid crystal cell used for LCOS. The cell is comprised of upper substrate with indium-tin-oxide coating and lower substrate with aluminum coating. Reflective angle-dependent signals (Rss, Rpp, Rsp and Rps) were recorded over a range of angles of incidence with the cell under application of 0 - 7 Vrms ac electric fields. From the recorded experimental data, we found the reflective signals are quite strong, especially the polarization conversion signals. Fitting the data in reflection with the results of the modeling-program gives the information about the pre-tilt and twist of the director as well as the parameters of different optical layers. We found that the pre-tilt angle on the upper substrate is different from that on the bottom in the best fits, which suggests that the indium-tin-oxide and the aluminum coatings have different effects on the alignment layers.展开更多
This paper investigated the dynamics of a dipole of ±1/2 parallel wedge disclination lines in a confined geometry, based on Landau-de Gennes theory. The behavior of the pair depends on the competition between two...This paper investigated the dynamics of a dipole of ±1/2 parallel wedge disclination lines in a confined geometry, based on Landau-de Gennes theory. The behavior of the pair depends on the competition between two kinds of forces: the attractive force between the two defects, aggravating the annihilation process, and the anchoring forces coming from the substrates, inhibiting the annihilation process. There are three states when the system is equilibrium, divided by two critical thicknesses dc1 and dc2 (existing when r0≤15ξ, r0 is the initial distance between the two defects), both changing linearly with r0. When the cell gap d>dc1, the two defects coalesce and annihilate. The dynamics follows the function of r∝(t0-t)α during the annihilation step when d is sufficiently large, relative to r0, where r is the relative distance between the pair and t0 is the coalescence time. α decreases with the decrease of d or the increase of r0. The annihilation process has delicate structures: when r0≤15ξ and d>dc2 or r0>15ξand d>dc1, the two defects annihilate and the system is uniaxial at equilibrium state;when r0≤15ξ and dc2>d>dc1, the two defects coalesce and annihilate, and the system is not uniaxial, but biaxial in the region where the defects collide. When d≤dc1, the defects can be stable existence.展开更多
The defect structures of s = ±1/2 twist disclinations in twisted nematic and twisted chiral liquid crystals have been investigated within the Landau-de Gennes theory numerically. Our results show that there exist...The defect structures of s = ±1/2 twist disclinations in twisted nematic and twisted chiral liquid crystals have been investigated within the Landau-de Gennes theory numerically. Our results show that there exists eigenvalue exchange across the defect core of both the two models. The defect core is essentially biaxial and never isotropic. The defect centre is uniaxial and is surrounded by a strong biaxial region.展开更多
This paper presents analytical solutions for full-field radiation in magnetoelectric(ME)antennas,considering a fully magnetoelastic coupled constitutive relation.A nonlinear converse ME coupling model is established,i...This paper presents analytical solutions for full-field radiation in magnetoelectric(ME)antennas,considering a fully magnetoelastic coupled constitutive relation.A nonlinear converse ME coupling model is established,incorporating mechanical,electric,and magnetic variables with generalized Maxwell equations.This model emphasizes the essence of ME antennas,where radiation is achieved through strain/stress-mediated coupling between different phases.The magnetic flux density and electric displacement obtained from the model are used as sources to solve the full-field radiations of ME antennas.The proposed model is validated through existing experiments and simulations,demonstrating that the radiation performance of ME antennas is strongly influenced by nonlinear magneto-elastic coupling.The material parameters and magnetic bias significantly impact the magnetic flux density and far-field radiation due to the nonlinear magnetization process.The study reveals the mechanisms behind enhanced working bandwidth and frequency tuning by examining the frequency response of the radiation impedance with material parameters.By adjusting the initial magnetization rate,saturation magnetostriction,and saturation magnetization,the radiation efficiency/gain can be increased by 340%,108%,and 112%respectively.This model enhances our understanding of the full-field radiation of ME antennas and provides a foundation for designing tunable ME antennas.展开更多
Heat is almost everywhere.Unlike electricity,which can be easily manipulated,the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodyna...Heat is almost everywhere.Unlike electricity,which can be easily manipulated,the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodynamics.Optical illumination and pressure have been used to switch endothermic/exothermic responses of materials via phase transitions;however,these strategies are less cost-effective and unscalable.Here,we spectroscopically demonstrate the glassy crystal state of 2-amino-2-methyl-1,3-propanediol(AMP)to realize an affordable,easily manageable approach for thermal energy recycling.The supercooled state of AMP is so sensitive to pressure that even several megapascals can induce crystallization to the ordered crystal,resulting in a substantial temperature increase of 48 K within 20 s.Furthermore,we demonstrate a proof-of-concept device capable of programable heating with an extremely high work-to-heat conversion effi-ciency of383.Such delicate and efficient tuning of heat may remarkably facilitate rational utilization of waste heat.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.226-2023-00010)National Natural Science Foundation of China(No.52038004)ZJU-ZCCC Institute of Collaborative Innovation(No.ZDJG2021008).
文摘Carbon nano additives(CNAs)are critical to achieving the unique properties of functionalized composites,however,controlling the dispersion of CNAs in material matrix is always a challenging task.In this study,a simple atomization approach was successfully developed to promote the dispersion efficiency of graphene nanoplatelets(GNPs)in cement composites.This atomization approach can be integrated with the direct,indirect and combined ultrasonic stirrings in a homemade automatic stirring-atomization device.Mechanical and microstructure tests were performed on hardened cement pastes blended with GNPs in different stirring and mixing approaches.Results show that the direct ultrasonic stirrings enabled more homogeneous dispersions of GNP particles with a smaller size for a longer duration.The atomized droplets with the mean size of~100μm largely mitigated GNPs’agglomerations.Monolayer GNPs were observed in the cement matrix with the strength gain by up to 54%,and the total porosity decrease by 21%in 0.3 wt%GNPs dosage.The greatly enhanced dispersion efficiency of GNPs in cement also raised the cement hydration.This work provides an effective and manpower saving technique toward dispersing CNAs in engineering materials with great industrialization prospects.
基金We acknowledge the financial support from National Key Research and Development Program of China(No.2018YFC1604100).
文摘Zearalenone(ZEN)is a widely distributed mycotoxin that frequently contaminates crops and animal feed.ZEN can cause serious health problems in livestock and humans alike,leading to great economic losses in the food industry and livestock farming.Therefore,approaches for efficient ZEN decontamination in food and feed are urgently needed.Traditional physical and chemical methods may decrease the nutritional quality of food and palatability of feed,or leading to residues and safety concerns.By contrast,biological methods for the removal or degradation of ZEN overcome these problems,especially for biological degradation by microorganisms and specific enzymes extracted from strains that can convert ZEN to less toxic or even completely harmless products.In this review,we comprehensively describe methods for ZEN degradation,focusing especially on biological strategies.Finally,emerging strategies and advice on remaining challenges in biodegradation research are also briefly discussed.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFA0206301)。
文摘Two-dimensional(2D)semiconductors isoelectronic to phosphorene have been drawing much attention recently due to their promising applications for next-generation(opt)electronics.This family of 2D materials contains more than 400members,including(a)elemental group-V materials,(b)binary III–VII and IV–VI compounds,(c)ternary III–VI–VII and IV–V–VII compounds,making materials design with targeted functionality unprecedentedly rich and extremely challenging.To shed light on rational functionality design with this family of materials,we systemically explore their fundamental band gaps and alignments using hybrid density functional theory(DFT)in combination with machine learning.First,calculations are performed using both the Perdew–Burke–Ernzerhof exchange–correlation functional within the generalgradient-density approximation(GGA-PBE)and Heyd–Scuseria–Ernzerhof hybrid functional(HSE)as a reference.We find this family of materials share similar crystalline structures,but possess largely distributed band-gap values ranging approximately from 0 eV to 8 eV.Then,we apply machine learning methods,including linear regression(LR),random forest regression(RFR),and support vector machine regression(SVR),to build models for the prediction of electronic properties.Among these models,SVR is found to have the best performance,yielding the root mean square error(RMSE)less than 0.15 eV for the predicted band gaps,valence-band maximums(VBMs),and conduction-band minimums(CBMs)when both PBE results and elemental information are used as features.Thus,we demonstrate that the machine learning models are universally suitable for screening 2D isoelectronic systems with targeted functionality,and especially valuable for the design of alloys and heterogeneous systems.
文摘High-purity magnetic CoNi submicrospherical chains, each of length 20 μm - 30 μm and self-assembled from fcc-phase CoNi submicrospheres of average diameter 800 nm, are synthesized via a surfactant-assisted solvothermal route without the aid of nucleation agent. The effects of surfactant and reducing agent on the morphology and size of the CoNi chains are studied, and a possible growth mechanism for the CoNi chains is proposed. The CoNi chains show ferromagnetic characteristics with a similarly small saturation magnetization of 104.1 emu/g and a larger coercivity of 150 Oe at room temperature compared to the monodispersed CoNi submicrospheres of 105 emu/g and 34 Oe as a result of the increased shape anisotropy.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFA0206302)
文摘For a two-dimensional ultra-cold Fermi superfluid with an effective static magnetic impurity, we theoretically investigated the variation of the Yu–Shiba–Rusinov(YSR) bound state in the Bardeen–Cooper–Schrieffer(BCS) to Bose–Einstein condensation(BEC) crossover regime.Within the framework of mean-field theory, analytical results of the YSR bound state energy were obtained as a function of the interaction parameters.First, when the background Fermi superfluid system stays in the weakly interacting BCS regime, we found that the YSR bound state energy is linearly dependent on the gap parameter with its coefficient slightly different from previous results.Second, we discovered re-entrance phenomena for the YSR state and an upper bound of the strength of the interaction between the paired atoms.By carefully analyzing the bound state energy as a function of the interaction parameters, we obtained a phase diagram showing the existence of the YSR state.Finally, we concluded that the re-entrance phenomena and the critical point can be easily experimentally detected through measurement of radio-frequency spectroscopy and density of states using current experimental techniques.
文摘Structural and magnetic properties of Nd15Fe70T15Nδ(T=V, Mo) alloys, made by mechanical alloying (MA) followed by heat-treatment and nitriding, have been investigated systematically.Effects of annealing temperature on the structure and magnetic properties of the materials were studied by means of X-ray diffraction, AC susceptibility and high field magnetization measurements. Under pure argon atmosphere, the optimum temperatures for the heat treatment are found to be 75 and 850℃ for Nd15Fe7015Nδ and Nd15Fe70Mo15Nδ respectively. Correspondingly, the following magnetic properties are achieved : (1) Nd15Fe70V15Nδ:Br=0.63 T,,HC=8.01kA/cm (10.1 kOe), (BH )max=50.3 kJ/m3 (6 32 MGOe), (2) Nd15Fe70Mo15Nδ :Br=0.42 T. iHc=5.6 kA/cm (7.4 kOe), (BH )max=26.6 kJ/m3 (3.34 MGOe)
基金financially supported by the National High-Tech Research and Development Program of China("863"Program)under Grant No.2002AA302603the National Natural Science Foundation of China under Grant Nos.50071062,59725103,and 50331030.
文摘Exchange interaction plays an important role on magnetic properties of nanocomposite magnets consisting of hard- and soft-magnetic phases. Here the exchange interaction in the Sm-Co/Co （and Fe65Co35） magnetic films was characterized by measuring static （mr（H）） and demagnetized （md（H）） remanence curves. According to conventional method： δm（H）=md（H） - [1 - 2mr（H）], the exchange interaction was evaluated. The switching fields H′p and Hp, at which static （mr（H）） and demagnetized （md（H）） remanence show the fastest change, were identified. The relative ratio η=Hp-H′p/Hp of switching fields H′p and Hp has a linear relationship with the maximum value δmmax of δm（H） curves, proposing an alternative way to characterize the exchange interaction.
文摘Purpose: The aim of the study was to evaluate the feasibility of a new venous-thrombus aspiration and autologous blood(auto-blood) reinfusion system.Materials and methods: We constructed the venous model from polyvinyl chloride(PVC) tubes and three-way unions using a fresh clot of chicken blood as the venous thrombus. Eight French and 12 F aspiration catheters were used to aspirate the thrombus in the right–pulmonary-artery model, 8 French and 14 F aspiration catheters were used in the inferior–vena cava model, and 8 French and 10 F aspiration catheters were used in the left-–iliofemoral-vein model. A thrombus filtration and auto-blood reinfusion bottle was used to filter the thrombus and re-infuse auto-blood. We evaluated the thrombus aspiration capability of each catheter by comparing preaspirated with the post-aspirated thrombus volume, and we evaluated the difference in aspiration capability between the two catheters in each model by comparing their thrombus aspiration rates. We used Student’s t-test for statistical analysis.Results: Differences between pre-aspirated and post-aspirated thrombus volumes for each catheter were insignificant, as were those between the thrombus aspiration rates of the two catheters in each venous model. Using the thrombus aspiration and auto-blood reinfusion system, each aspiration catheter could fluently aspirate the thrombus out of the venous model.Conclusion: In this study, we designed a new venous-thrombus aspiration system. This system could be used to aspirate acute venous thrombi and re-infuse autologous blood.
文摘A brief review on recent advances in the area of the magnetic nanocapsules is given. The most applicable nanoencapsulation procedures are introduced, which include： （1） physical techniques such as arc-discharge, evaporating, etc.; （2） chemical techniques such as chemical vapor deposition, solid-state reactions, etc. The structure and magnetic properties of various nanocapsules with different core/shell structures are studied in details, for possibly applications in magnetic recording, magnetic refrigerator, magnetic fluids, superconductors and medicine.
文摘The fully-leaky guided wave technique has been used to study the reflective 90? MTN liquid crystal cell used for LCOS. The cell is comprised of upper substrate with indium-tin-oxide coating and lower substrate with aluminum coating. Reflective angle-dependent signals (Rss, Rpp, Rsp and Rps) were recorded over a range of angles of incidence with the cell under application of 0 - 7 Vrms ac electric fields. From the recorded experimental data, we found the reflective signals are quite strong, especially the polarization conversion signals. Fitting the data in reflection with the results of the modeling-program gives the information about the pre-tilt and twist of the director as well as the parameters of different optical layers. We found that the pre-tilt angle on the upper substrate is different from that on the bottom in the best fits, which suggests that the indium-tin-oxide and the aluminum coatings have different effects on the alignment layers.
文摘This paper investigated the dynamics of a dipole of ±1/2 parallel wedge disclination lines in a confined geometry, based on Landau-de Gennes theory. The behavior of the pair depends on the competition between two kinds of forces: the attractive force between the two defects, aggravating the annihilation process, and the anchoring forces coming from the substrates, inhibiting the annihilation process. There are three states when the system is equilibrium, divided by two critical thicknesses dc1 and dc2 (existing when r0≤15ξ, r0 is the initial distance between the two defects), both changing linearly with r0. When the cell gap d>dc1, the two defects coalesce and annihilate. The dynamics follows the function of r∝(t0-t)α during the annihilation step when d is sufficiently large, relative to r0, where r is the relative distance between the pair and t0 is the coalescence time. α decreases with the decrease of d or the increase of r0. The annihilation process has delicate structures: when r0≤15ξ and d>dc2 or r0>15ξand d>dc1, the two defects annihilate and the system is uniaxial at equilibrium state;when r0≤15ξ and dc2>d>dc1, the two defects coalesce and annihilate, and the system is not uniaxial, but biaxial in the region where the defects collide. When d≤dc1, the defects can be stable existence.
文摘The defect structures of s = ±1/2 twist disclinations in twisted nematic and twisted chiral liquid crystals have been investigated within the Landau-de Gennes theory numerically. Our results show that there exists eigenvalue exchange across the defect core of both the two models. The defect core is essentially biaxial and never isotropic. The defect centre is uniaxial and is surrounded by a strong biaxial region.
基金supported by the Natural Science Foundation of Shaanxi Province(Grant No.2024JC-YBMS-069)the Fundamental Research Funds for the Central Universities and the Innovation Fund of Xidian University(Grant Nos.ZYTS24026 and YJSJ24001).
文摘This paper presents analytical solutions for full-field radiation in magnetoelectric(ME)antennas,considering a fully magnetoelastic coupled constitutive relation.A nonlinear converse ME coupling model is established,incorporating mechanical,electric,and magnetic variables with generalized Maxwell equations.This model emphasizes the essence of ME antennas,where radiation is achieved through strain/stress-mediated coupling between different phases.The magnetic flux density and electric displacement obtained from the model are used as sources to solve the full-field radiations of ME antennas.The proposed model is validated through existing experiments and simulations,demonstrating that the radiation performance of ME antennas is strongly influenced by nonlinear magneto-elastic coupling.The material parameters and magnetic bias significantly impact the magnetic flux density and far-field radiation due to the nonlinear magnetization process.The study reveals the mechanisms behind enhanced working bandwidth and frequency tuning by examining the frequency response of the radiation impedance with material parameters.By adjusting the initial magnetization rate,saturation magnetostriction,and saturation magnetization,the radiation efficiency/gain can be increased by 340%,108%,and 112%respectively.This model enhances our understanding of the full-field radiation of ME antennas and provides a foundation for designing tunable ME antennas.
基金The work conducted in the Institute of Metal Research was supported by the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(grant no.ZDBS-LY-JSC002)the Liaoning Provincial Science Fund for Distinguished Young Scholars(grant no.2023JH6/100500003)+7 种基金the Innovation Fund of Institute of Metal Research,Chinese Academy of Sciences,(grant no.2021-ZD01)the CSNS Consortium on High-performance Materials of the Chinese Academy of Sciences,the Young Innovation Talent Program of Shenyang(grant no.RC210432)the Ministry of Science and Technology of the People’s Republic of China(grant nos.2021YFB3501201,2022YFE0109900,and 2020YFA0406002)the National Natural Science Foundation of China(grant nos.11934007,52001101,and 61974147)the International Partner Program of Chinese Academy of Sciences(grant no.174321KYSB20200008)J.L.and M.W.are grateful for the Research Foundation Flanders(grant no.G0B3218N)J.Luo acknowledges Sichuan Science and Technology Program(grant nos.2022ZYD0016 and 2023JDRC0013)National Natural Science Foundation of China(grant nos.21776120 and 22378270).The authors thank Sucheng Wang and Changji Li for their help with the in situ XRD experiments,Shuai Huang for thermal infrared image measurements,and Bo Huang for sample deuteration.They also thank Prof.Jie Pan and Prof.Si Lan for valuable discussions.
文摘Heat is almost everywhere.Unlike electricity,which can be easily manipulated,the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodynamics.Optical illumination and pressure have been used to switch endothermic/exothermic responses of materials via phase transitions;however,these strategies are less cost-effective and unscalable.Here,we spectroscopically demonstrate the glassy crystal state of 2-amino-2-methyl-1,3-propanediol(AMP)to realize an affordable,easily manageable approach for thermal energy recycling.The supercooled state of AMP is so sensitive to pressure that even several megapascals can induce crystallization to the ordered crystal,resulting in a substantial temperature increase of 48 K within 20 s.Furthermore,we demonstrate a proof-of-concept device capable of programable heating with an extremely high work-to-heat conversion effi-ciency of383.Such delicate and efficient tuning of heat may remarkably facilitate rational utilization of waste heat.
