Exploring multifunctional interfacial modifiers is an effective approach to addressing interface issues in perovskite solar cells(PSCs)and improving device performance and stability.While most interfacial modifiers fo...Exploring multifunctional interfacial modifiers is an effective approach to addressing interface issues in perovskite solar cells(PSCs)and improving device performance and stability.While most interfacial modifiers focus on passivating defects at the interfaces,there has been limited investigation into the relationship between molecular design and interfacial charge dynamics.This work introduces resonance molecules with a push-pull effect for interfacial modification,allowing for synergistic regulation of passivation effects and charge dynamics.Specifically,FCz-PO,which includes an electron-withdrawing fluorine atom,exhibits superior passivation but poor molecular stacking and charge extraction.In contrast,MCz-PO,featuring an electron-donating methoxy group,provides effective passivation,wellordered molecular packing,and efficient charge extraction and transport.Consequently,PSCs using MCz-PO achieve high power conversion efficiency(PCE)of 24.74%and excellent operational stability.This study suggests that resonance structures can be an effective molecular design strategy for developing interfacial modifiers with both strong passivation capabilities and well-regulated charge dynamics.展开更多
The cavity-mode resonance effect could result in significant degradation of the shielding effectiveness （SE） of a shielding enclosure around its resonance frequencies. In this paper, the influence of coated wall los...The cavity-mode resonance effect could result in significant degradation of the shielding effectiveness （SE） of a shielding enclosure around its resonance frequencies. In this paper, the influence of coated wall loss on the suppression of the resonance effect is investigated. For this purpose, an equivalent circuit model is employed to analyze the SE of an apertured rectangular cavity coated with an inside layer of resistive material. The model is developed by extending Robinson＇s equivalent circuit model through incorporating the effect of the wall loss into both the propagation constant and the characteristic impedance of the waveguide. Calculation results show that the wall loss could lead to great improvement on the SE for frequencies near the resonance but almost no effect on the SE for frequencies far away from the resonance.展开更多
Herein,we report a novel ternary material comprised of Ag nanoparticles and carbon quantum dots(CDs),which are co-loaded using 2D Bi4Ti3O12(BIT)sheets.In this system,Ag can be applied as excited electron-hole pairs in...Herein,we report a novel ternary material comprised of Ag nanoparticles and carbon quantum dots(CDs),which are co-loaded using 2D Bi4Ti3O12(BIT)sheets.In this system,Ag can be applied as excited electron-hole pairs in the Bi4Ti3O12 by transferring the plasmonic energy from the metal to the semiconductor.The surface plasmon resonance of Ag can promote the electron transfer properties of the CDs,thereby improving the separation efficiency of the electron-hole pairs.Meanwhile,the CDs can act as an electron buffer to decrease the recombination rate of the electron hole.Moreover,CDs are prepared using a biomaterial,which can provide a chemical group to enhance the electron transfer and connection.The synergistic effects of CDs,Ag,and BIT enable the design of a photocatalytic application with a remarkably improved efficiency and operational stability.展开更多
This paper adopted a semi-analytical method based on eigenfunction matching to solve the problem of sharp resonance of cylindrical structures with a moonpool that has a restricted entrance. To eliminate the sharp reso...This paper adopted a semi-analytical method based on eigenfunction matching to solve the problem of sharp resonance of cylindrical structures with a moonpool that has a restricted entrance. To eliminate the sharp resonance and to measure the viscous effect, a quadratic dissipation is introduced by assuming an additional dissipative disk at the moonpool entrance. The fluid domain is divided into five cylindrical subdomains, and the velocity potential in each subdomain is obtained by meeting the Laplace equation as well as the boundary conditions. The free-surface elevation at the center of the moonpool, along with the pressure and velocity at the restricted entrance for first-order wave are evaluated. By choosing appropriate dissipation coefficients, the free-surface elevation calculated at the center of the moonpool is in coincidence with the measurements in model tests both at the peak period and amplitude at resonance. It is shown that the sharp resonance in the potential flow theory can be eliminated and the viscous effect can be estimated with a simple method in some provided hydrodynamic models.展开更多
Lanthanide coordination compounds of the formula Na[Ln(L)4](1 Ln),where Ln=La^3+,Eu^3+,Gd^3+,Tb^3+,L=[L]-and HL=dimethyl(4-methylphenylsulfo nyl)amidophosphate,were synthesized.Their structural and spectro scopic prop...Lanthanide coordination compounds of the formula Na[Ln(L)4](1 Ln),where Ln=La^3+,Eu^3+,Gd^3+,Tb^3+,L=[L]-and HL=dimethyl(4-methylphenylsulfo nyl)amidophosphate,were synthesized.Their structural and spectro scopic properties were discussed in detail based on X-ray diffraction measurements,IR spectroscopy,absorption and emission spectroscopy at 293 and 77 K and theoretical calculations of the intramolecular energy transfer(IET)rates.DFT calculations were used to investigate the 1 Ln electronic properties re quired to calculate the transition rates.30 and 22 pathways of intramolecular nonradiative energy transfer were examined in the case of 1 Eu and 1 Tb,respectively.It is shown that the main pathway for sensitization of the lanthanide emission is either the triplet(1 Eu)or singlet(1 Tb)transfer,occurring mainly through the exchange mechanism.The energy rates for energy transfer from S1 and T1 equal WS=1.53×10^5 s^-1(1 Eu),WT=5.14×10^6 s^-1(1 Eu)and WS=4.09×10^7 s^-1(1 Tb),WT=6.88×10^5 s^-1(1 Tb).The crucial role of the 7 F5 level in the energy transfer process of 1 Tb and the participation of the LMCT state in the depopulation of the ligand singlet state of 1 Eu were demonstrated.The influence of the resonance effect on the splitting of the7 F1 level in 1 Eu was analyzed.By comparing the properties of 1 Ln with the properties of 2 Ln coordination compounds,sharing the same ligand and crystallizing in the same crystallographic system(monoclinic),but with a different space group,it is demonstrated how slight structural changes can affect the photophysical properties of Ln compounds.展开更多
Based on the beam wave synchronous interaction in transverse and longitudinal directions at the same time and starting from Maxwell’s equation and linear Vlasov equation, the beam–wave interaction ‘hot’ dispersion...Based on the beam wave synchronous interaction in transverse and longitudinal directions at the same time and starting from Maxwell’s equation and linear Vlasov equation, the beam–wave interaction ‘hot’ dispersion equation considering both cyclotron resonance and Cherenkov resonance in a staggered double metallic grating traveling wave tube is deduced.Through the reasonable selection for geometric and electrical parameters, the numerical calculation and analysis of the ‘hot’ dispersion equation shows that the beam–wave interaction gain and frequency band with the cyclotron resonance enhancement effect are higher than those with only Cherenkov resonance radiation.展开更多
Based on the nonlocal strain gradient theory(NSGT), a model is proposed for an axially moving nanobeam with two kinds of scale effects. The internal resonanceaccompanied fundamental harmonic response of the external e...Based on the nonlocal strain gradient theory(NSGT), a model is proposed for an axially moving nanobeam with two kinds of scale effects. The internal resonanceaccompanied fundamental harmonic response of the external excitation frequency in the vicinities of the first and second natural frequencies is studied by adopting the multivariate Lindstedt-Poincaré(L-P) method. Based on the root discriminant of the frequencyamplitude equation under internal resonance conditions, theoretical analyses are performed to investigate the scale effects of the resonance region and the critical external excitation amplitude. Numerical results show that the region of internal resonance is related to the amplitude of the external excitation. Particularly, the internal resonance disappears after a certain critical value of the external excitation amplitude is reached.It is also shown that the scale parameters, i.e., the nonlocal parameters and the material characteristic length parameters, respectively, reduce and increase the critical amplitude,leading to a promotion or suppression of the occurrence of internal resonance. In addition,the scale parameters affect the size of the enclosed loop of the bifurcated solution curves as well by changing their intersection, divergence, or tangency.展开更多
Carbon dots(CDs)with room-temperature phosphorescence(RTP)have attracted dramatically growing interest in optical functional materials.However,the photoluminescence mechanism of CDs is still a vital and challenging to...Carbon dots(CDs)with room-temperature phosphorescence(RTP)have attracted dramatically growing interest in optical functional materials.However,the photoluminescence mechanism of CDs is still a vital and challenging topic.In this work,we prepared CD-based RTP materials via melting boric acid with various lengths of alkyl amine compounds as precursors.The spatial effect on the structure and the RTP properties of CDs were systematically investigated.With the increase in carbon chain length,the interplanar spacing of the carbon core expands and crosslink-enhanced emission weakens,resulting in a decrease in the phosphorescence intensity and lifetimes.Meanwhile,based on triplet-to-singlet resonance energy transfer,we employed intense and long-lived phosphorescence CDs as the donor and short-lived fluorescent dyes as the acceptor to achieve long-lived multicolor afterglow.By the triplet-to-singlet resonance energy transfer,the afterglow color can change from green to orange.The afterglow lifetimes are more than 0.9 s.Thanks to the outstanding afterglow properties,the composites were used for timeresolved and multiple-color advanced anticounterfeiting.This work will promote the design of multicolor and long-lived afterglow materials and expand their applications.展开更多
The study has shown that the shear component of the vertical integrated kinetic energy(Ks)over the box(40oE-100oE,0-20oN)can be used to measure the intensity of the South Asian summer monsoon(SASM).Based on its value ...The study has shown that the shear component of the vertical integrated kinetic energy(Ks)over the box(40oE-100oE,0-20oN)can be used to measure the intensity of the South Asian summer monsoon(SASM).Based on its value averaged between June and August,the SASM can be divided into strong and weak monsoon episodes.Between1958 and 2018,there existed 16(16)strong(weak)monsoon episodes.Based on the calendar year,the relationship between the SASM and ENSO episodes can be grouped into six patterns:weak monsoon-El Ni?o(WM-EN),normal monsoon-El Ni?o(NM-EN),weak monsoon-non ENSO(WM-NE),strong monsoon-La Ni?a(SM-LN),normal monsoon-La Ni?a(NM-LN)and strong monsoon-non ENSO(SM-NE).Previous studies suggest that the WM-EN and SM-LN patterns reflect the correlated relationship between the SASM and El Ni?o/Southern Oscillation(ENSO)events.Therefore,we name these two strongly coupled categories WM-EN and SM-LN as the resonance effect.Two important circulations,i.e.,Walker circulation(WC)and zonal Asian monsoon circulation(MC),in the vertical plane are found to be not always correlated.The MC is controlled by thermal gradients between the Asian landmass and the tropical Indian Ocean,while the WC associated with ENSO events is primarily the east-west thermal gradient between the tropical South Pacific and the tropical Indian Ocean.Furthermore,the gradient directions caused by different surface thermal conditions are different.The main factor for the resonance effect is the phenomenon that the symbols of SSTA in the tropical Indian Ocean and the equatorial eastern Pacific are the same,but are opposite to that of the SSTA near the maritime continent.展开更多
The structure of the extended gate ion sensitive field effect transistor (EGISFET) is similar to the structure of the ion sensitive field effect transistor (ISFET).Moreover,the non-ideal effect of EGISFET is the mai...The structure of the extended gate ion sensitive field effect transistor (EGISFET) is similar to the structure of the ion sensitive field effect transistor (ISFET).Moreover,the non-ideal effect of EGISFET is the main impediment to development of commercial processes for sensitive devices.It is necessary to promote the stability and reliability of the devices by employing calibration circuits and the better fabrication conditions.The temporal drift exists in the entire measurement experiment. Furthermore,in this study we can reduce the temporal drift effect which influences the stability of the TiN sensitive electrode with the differential front-end offset circuit.The measurement system combines with shifting circuit,differential and instrument amplifiers.We employ the calibration circuit to compare with the variations of the output voltage,and expectably improve the stability and reliability of the TiN sensitive electrode by the novel calibration circuit.展开更多
In this paper, the effective pyroelectric coefficient and polarization offset of the compositionally step-like graded multilayer ferroelectric structures have been studied by use of the first-principles approach. It i...In this paper, the effective pyroelectric coefficient and polarization offset of the compositionally step-like graded multilayer ferroelectric structures have been studied by use of the first-principles approach. It is exhibited that the dielectric gradient has a nontrivial influence on the effective pyroelectric coefficient, but has a little influence on the polarization offset; and the polarization gradient plays an important role in the abnormal hysteresis loop phenomenon of the co.mpositionally step-like graded ferroelectric structures. Moreover, the origin of the polarization offset is explored,which can be attributed to the polarization gradient in the compositionally step-like graded structure.展开更多
We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice....We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice. Starting from an unentangled initial state associated with the regular ＇island＇ of classical phase space, it is demonstrated that the quantum resonance leads to entanglement generation, the chaotic parameter region results in the increase of the generation speed, and the symmetries of the initial probability distribution determine the final degree of entanglement. The entangled initial states are associated with the classical ＇chaotic sea＇, which do not affect the final entanglement degree for the same initial symmetry. The results may be useful in engineering quantum dynamics for quantum information processing.展开更多
Quantum interference plays an important role in tuning the transport property of nano-devices. Using the non- equilibrium Green＇s Function method in combination with density functional theory, we investigate the infl...Quantum interference plays an important role in tuning the transport property of nano-devices. Using the non- equilibrium Green＇s Function method in combination with density functional theory, we investigate the influence to the transport property of a CO molecule adsorbed on one edge of a zigzag graphene nanoribbon device. Our results show that the CO molecule-adsorbed zigzag graphene nanoribbon devices can exhibit the Fano resonance phenomenon. Moreover, the distance between CO molecules and zigzag graphene nanoribbons is closely related to the energy sites of the Fano resonance. Our theoretical analyses indicate that the Fano resonance would be attributed to the interaction between CO molecules and the edge of the zigzag graphene nanoribbon device, which results in the localization of electrons and significantly changes the transmission spectrum.展开更多
Metal-based surface plasmon resonance(SPR)plays an important role in enhancing the photonic spin Hall effect(SHE)and developing sensitive optical sensors.However,the very large negative permittivities of metals limit ...Metal-based surface plasmon resonance(SPR)plays an important role in enhancing the photonic spin Hall effect(SHE)and developing sensitive optical sensors.However,the very large negative permittivities of metals limit their applications beyond the near-infrared regime.In this work,we theoretically present a new mechanism to enhance the photonic SHE by taking advantage of SiC-supported surface phonon resonance(SPhR)in the mid-infrared regime.The transverse displacement of photonic SHE is very sensitive to the wavelength of incident light and the thickness of SiC layer.Under the optimal parameter setup,the calculated largest transverse displacement of SiC-based SPhR structure reaches up to 163.8 ym,which is much larger than the condition of SPR.Moreover,an NO_(2) gas sensor based on the SPhR-enhanced photonic SHE is theoretically proposed with the superior sensing performance.Both the intensity and angle sensitivity of this sensor can be effectively manipulated by varying the damping rate of SiC.The results may provide a promising paradigm to enhance the photonic SHE in the mid-infrared region and open up new opportunity of highly sensitive refractive index sensors.展开更多
The effect of signal modulating noise in bistable stochastic resonance systems was studied theoretically and experimentally. A mathematical analysis was made on the bistable stochastic resonance model with small syste...The effect of signal modulating noise in bistable stochastic resonance systems was studied theoretically and experimentally. A mathematical analysis was made on the bistable stochastic resonance model with small system parameters. An analogue circuit was designed to perform the effect. The effect of signal modulating noise was shown in the analog simulation experiment. The analog experiment was conducted for two sinusoidal signals with different frequencies. The results show that there are a sinusoidal component corresponding to the input sinusoidal signal and a noise component presented as a Wiener process corresponding to the input white noise in the system output. By properly selecting system parameters, the effect of signal modulating noise can be manifested in the system output.展开更多
A monolithic integrated two-section distributed feedback(TS-DFB)semiconductor laser for high-speed direct modulation is proposed and analyzed theoretically.The grating structure of the TS-DFB laser is designed by the ...A monolithic integrated two-section distributed feedback(TS-DFB)semiconductor laser for high-speed direct modulation is proposed and analyzed theoretically.The grating structure of the TS-DFB laser is designed by the reconstructionequivalent-chirp(REC)technique,which can reduce the manufacturing cost and difficulty,and achieve high wavelength controlling accuracy.The detuned loading effect and the photon-photon resonance(PPR)effect are utilized to enhance the modulation bandwidth of the TS-DFB laser,exceeding 37 GHz,while that of the conventional one-section DFB laser is only 16 GHz.When the bit rate of the non-return-to-zero(NRZ)signal reaches 55 Gb/s,a clear eye diagram with large opening can still be obtained.These results show that the proposed method can enhance the modulation bandwidth of DFB laser significantly.展开更多
Two sets of gold nanoparticles (NP) embedded in amorphous BaTiO3 films were prepared by sol-gel method using spin coating. Sample (1) is having BaTiO3 sol with 0.025 gm of Chloroauric acid dissolved in 10 ml of propan...Two sets of gold nanoparticles (NP) embedded in amorphous BaTiO3 films were prepared by sol-gel method using spin coating. Sample (1) is having BaTiO3 sol with 0.025 gm of Chloroauric acid dissolved in 10 ml of propan-2-ol, while sample (2) is having 0.086 gm of Chloroauric acid in the same amount of propan-2-ol. The films have been deposited on various substrates like borosilicate glass and fused silica. TEM images show that the particles are of 5 and 10 nm in size for the two set of samples, and some are having elongated morphology. Optical absorption properties of these films reveal the substrate and size effect on localised surface plasmon resonance (SPR). It shows a marginal red shift in the plasmon resonance peak from 414 nm to 420 nm in the case of sample (1) and 566 nm to 568 nm for sample (2) as the substrate changed from borosilicate glass to fused silica. It also shows red shift in Plasmon peak as the size increases from 5 to 10 nm and coincides with Mie explanation for the shift with size.展开更多
Objective: To investigate the diagnostic effects of CT and magnetic resonance imaging (MRI) in patients with lacunar infarction. Methods: Thirty patients with early lacunar infarction in our hospital were diagnosed by...Objective: To investigate the diagnostic effects of CT and magnetic resonance imaging (MRI) in patients with lacunar infarction. Methods: Thirty patients with early lacunar infarction in our hospital were diagnosed by ct and 30 patients were diagnosed by magnetic resonance imaging according to the examination time, the average diameter of infarct focus and examination cost. Vascular image quality (siphon segment score of internal carotid artery, petrous segment score of artery, posterior communicating artery score and basilar artery score), and the lesion detection rates of the two inspection methods were compared;Results The detection effect of MRI was superior to that of ct (P < 0.05). Conclusion: patients with lacunar infarction by magnetic resonance imaging technology and ct two ways of diagnosis, can get good diagnosis effect, but the magnetic resonance imaging technology to detect the infarct diameter is larger, the diagnosis effect is better, the detection time is shorter, however, the examination cost is more, can according to the needs of patients in clinical reasonable choice of examination methods.展开更多
This study focuses on coupled vibrations of rotating thin-walled composite beams subjected to hygrothermal effects.In the existing literature,many studies have been conducted on coupled bending-torsional vibration and...This study focuses on coupled vibrations of rotating thin-walled composite beams subjected to hygrothermal effects.In the existing literature,many studies have been conducted on coupled bending-torsional vibration and resonance in hygrothermal environments.Few studies considered the coupled flapwise-edgewise and resonances of composite thin-walled beams.Considering this,the flapwise-edgewise coupling effects and resonant characteristics of rotating thin-walled composite beams in a hygrothermal environment are studied.The Rayleigh–Ritz method is used to solve the equations of the beam.Results indicate that flapwise-edgewise coupling factors are essential for the vibration analysis of rectangular thin-walled beams.The ply angle and setting angle strongly affect the internal and external resonances.Large ply angles can significantly reduce the chances of primary internal and external resonances occurring when the permitted rotational speed is lower.展开更多
This study examines the coupling analysis between box roll motion response and free surface oscillation in a narrow gap,utilizing a two-box system comprising a small roll box and a large fixed box.The potential flow m...This study examines the coupling analysis between box roll motion response and free surface oscillation in a narrow gap,utilizing a two-box system comprising a small roll box and a large fixed box.The potential flow model reveals a two-peak variation in both roll motion response and free surface oscillation across incident wave frequencies.Free decay tests indicate that these frequencies correspond to the first and second resonant frequencies of the roll-fixed two-box system.Viscous fluid flow model simulations demonstrate a two-peak behavior in roll motion response,while free surface oscillation exhibits a single peak near the second resonant frequency.Repositioning the small roll box from upstream to downstream results in increased roll motion amplitude around the first resonant frequency.The roll-box with round edge profiles exhibits beating behavior in motion response,resulting in increased roll motion amplitude across a broad frequency range.Notably,wave energy at the first resonant frequency component remains undamped by round edge profiles.展开更多
基金the financial support from the Natural Science Foundation of Xiamen,China(3502Z202373075)the National Natural Science Foundation of China(Grant nos.22175180,52311530673,22103013)+1 种基金the Natural Science Foundation of Fujian Province(No.2023J01527,2021J01184,2024J01189)the Start-up funding from Fujian Normal University(Y0720312K13)。
文摘Exploring multifunctional interfacial modifiers is an effective approach to addressing interface issues in perovskite solar cells(PSCs)and improving device performance and stability.While most interfacial modifiers focus on passivating defects at the interfaces,there has been limited investigation into the relationship between molecular design and interfacial charge dynamics.This work introduces resonance molecules with a push-pull effect for interfacial modification,allowing for synergistic regulation of passivation effects and charge dynamics.Specifically,FCz-PO,which includes an electron-withdrawing fluorine atom,exhibits superior passivation but poor molecular stacking and charge extraction.In contrast,MCz-PO,featuring an electron-donating methoxy group,provides effective passivation,wellordered molecular packing,and efficient charge extraction and transport.Consequently,PSCs using MCz-PO achieve high power conversion efficiency(PCE)of 24.74%and excellent operational stability.This study suggests that resonance structures can be an effective molecular design strategy for developing interfacial modifiers with both strong passivation capabilities and well-regulated charge dynamics.
基金supported by the National Natural Science Foundation of China(Grant No.51037001)
文摘The cavity-mode resonance effect could result in significant degradation of the shielding effectiveness （SE） of a shielding enclosure around its resonance frequencies. In this paper, the influence of coated wall loss on the suppression of the resonance effect is investigated. For this purpose, an equivalent circuit model is employed to analyze the SE of an apertured rectangular cavity coated with an inside layer of resistive material. The model is developed by extending Robinson＇s equivalent circuit model through incorporating the effect of the wall loss into both the propagation constant and the characteristic impedance of the waveguide. Calculation results show that the wall loss could lead to great improvement on the SE for frequencies near the resonance but almost no effect on the SE for frequencies far away from the resonance.
基金financially supported by the National Natural Science Foundation of China(U1510126,21676115)the Natural Science Foundation of Jiangsu Provincial(BK20180884)~~
文摘Herein,we report a novel ternary material comprised of Ag nanoparticles and carbon quantum dots(CDs),which are co-loaded using 2D Bi4Ti3O12(BIT)sheets.In this system,Ag can be applied as excited electron-hole pairs in the Bi4Ti3O12 by transferring the plasmonic energy from the metal to the semiconductor.The surface plasmon resonance of Ag can promote the electron transfer properties of the CDs,thereby improving the separation efficiency of the electron-hole pairs.Meanwhile,the CDs can act as an electron buffer to decrease the recombination rate of the electron hole.Moreover,CDs are prepared using a biomaterial,which can provide a chemical group to enhance the electron transfer and connection.The synergistic effects of CDs,Ag,and BIT enable the design of a photocatalytic application with a remarkably improved efficiency and operational stability.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51509048,51679044 and11572094)
文摘This paper adopted a semi-analytical method based on eigenfunction matching to solve the problem of sharp resonance of cylindrical structures with a moonpool that has a restricted entrance. To eliminate the sharp resonance and to measure the viscous effect, a quadratic dissipation is introduced by assuming an additional dissipative disk at the moonpool entrance. The fluid domain is divided into five cylindrical subdomains, and the velocity potential in each subdomain is obtained by meeting the Laplace equation as well as the boundary conditions. The free-surface elevation at the center of the moonpool, along with the pressure and velocity at the restricted entrance for first-order wave are evaluated. By choosing appropriate dissipation coefficients, the free-surface elevation calculated at the center of the moonpool is in coincidence with the measurements in model tests both at the peak period and amplitude at resonance. It is shown that the sharp resonance in the potential flow theory can be eliminated and the viscous effect can be estimated with a simple method in some provided hydrodynamic models.
基金Project supported by the Minister of Science and Higher Education POIG.01.01.02-02-006/09the grant Minister of Science and Higher Education for young scientists 2432/M/WCH/14+1 种基金partially developed within the scope of the project CICECO-Aveiro Institute of Materials,FCT(Portuguese agency)Ref.UID/CTM/50011/2019financed by national funds through the FCT/MCTES。
文摘Lanthanide coordination compounds of the formula Na[Ln(L)4](1 Ln),where Ln=La^3+,Eu^3+,Gd^3+,Tb^3+,L=[L]-and HL=dimethyl(4-methylphenylsulfo nyl)amidophosphate,were synthesized.Their structural and spectro scopic properties were discussed in detail based on X-ray diffraction measurements,IR spectroscopy,absorption and emission spectroscopy at 293 and 77 K and theoretical calculations of the intramolecular energy transfer(IET)rates.DFT calculations were used to investigate the 1 Ln electronic properties re quired to calculate the transition rates.30 and 22 pathways of intramolecular nonradiative energy transfer were examined in the case of 1 Eu and 1 Tb,respectively.It is shown that the main pathway for sensitization of the lanthanide emission is either the triplet(1 Eu)or singlet(1 Tb)transfer,occurring mainly through the exchange mechanism.The energy rates for energy transfer from S1 and T1 equal WS=1.53×10^5 s^-1(1 Eu),WT=5.14×10^6 s^-1(1 Eu)and WS=4.09×10^7 s^-1(1 Tb),WT=6.88×10^5 s^-1(1 Tb).The crucial role of the 7 F5 level in the energy transfer process of 1 Tb and the participation of the LMCT state in the depopulation of the ligand singlet state of 1 Eu were demonstrated.The influence of the resonance effect on the splitting of the7 F1 level in 1 Eu was analyzed.By comparing the properties of 1 Ln with the properties of 2 Ln coordination compounds,sharing the same ligand and crystallizing in the same crystallographic system(monoclinic),but with a different space group,it is demonstrated how slight structural changes can affect the photophysical properties of Ln compounds.
基金supported by National Natural Science Foundation of China(No.61671431)
文摘Based on the beam wave synchronous interaction in transverse and longitudinal directions at the same time and starting from Maxwell’s equation and linear Vlasov equation, the beam–wave interaction ‘hot’ dispersion equation considering both cyclotron resonance and Cherenkov resonance in a staggered double metallic grating traveling wave tube is deduced.Through the reasonable selection for geometric and electrical parameters, the numerical calculation and analysis of the ‘hot’ dispersion equation shows that the beam–wave interaction gain and frequency band with the cyclotron resonance enhancement effect are higher than those with only Cherenkov resonance radiation.
基金Project supported by the National Natural Science Foundation of China(Nos.11702036,11602204,and 11502218)。
文摘Based on the nonlocal strain gradient theory(NSGT), a model is proposed for an axially moving nanobeam with two kinds of scale effects. The internal resonanceaccompanied fundamental harmonic response of the external excitation frequency in the vicinities of the first and second natural frequencies is studied by adopting the multivariate Lindstedt-Poincaré(L-P) method. Based on the root discriminant of the frequencyamplitude equation under internal resonance conditions, theoretical analyses are performed to investigate the scale effects of the resonance region and the critical external excitation amplitude. Numerical results show that the region of internal resonance is related to the amplitude of the external excitation. Particularly, the internal resonance disappears after a certain critical value of the external excitation amplitude is reached.It is also shown that the scale parameters, i.e., the nonlocal parameters and the material characteristic length parameters, respectively, reduce and increase the critical amplitude,leading to a promotion or suppression of the occurrence of internal resonance. In addition,the scale parameters affect the size of the enclosed loop of the bifurcated solution curves as well by changing their intersection, divergence, or tangency.
基金The authors greatly acknowledge the Natural Science Foundation of Jiangsu Province(No.BK20220351)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.22KJB150027)for financial support.
文摘Carbon dots(CDs)with room-temperature phosphorescence(RTP)have attracted dramatically growing interest in optical functional materials.However,the photoluminescence mechanism of CDs is still a vital and challenging topic.In this work,we prepared CD-based RTP materials via melting boric acid with various lengths of alkyl amine compounds as precursors.The spatial effect on the structure and the RTP properties of CDs were systematically investigated.With the increase in carbon chain length,the interplanar spacing of the carbon core expands and crosslink-enhanced emission weakens,resulting in a decrease in the phosphorescence intensity and lifetimes.Meanwhile,based on triplet-to-singlet resonance energy transfer,we employed intense and long-lived phosphorescence CDs as the donor and short-lived fluorescent dyes as the acceptor to achieve long-lived multicolor afterglow.By the triplet-to-singlet resonance energy transfer,the afterglow color can change from green to orange.The afterglow lifetimes are more than 0.9 s.Thanks to the outstanding afterglow properties,the composites were used for timeresolved and multiple-color advanced anticounterfeiting.This work will promote the design of multicolor and long-lived afterglow materials and expand their applications.
基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20060503)Fund of Southern Marine Science and Engineering Guangdong Laboratory(ZJW-2019-08)+2 种基金National Key R&D Program of China(2017YFC1501802,2018YFA0605604)Project of Enhancing School with Innovation of Guangdong Ocean University(230419053)Projects(Platforms)for Construction of Topranking Disciplines of Guangdong Ocean University(231419022)
文摘The study has shown that the shear component of the vertical integrated kinetic energy(Ks)over the box(40oE-100oE,0-20oN)can be used to measure the intensity of the South Asian summer monsoon(SASM).Based on its value averaged between June and August,the SASM can be divided into strong and weak monsoon episodes.Between1958 and 2018,there existed 16(16)strong(weak)monsoon episodes.Based on the calendar year,the relationship between the SASM and ENSO episodes can be grouped into six patterns:weak monsoon-El Ni?o(WM-EN),normal monsoon-El Ni?o(NM-EN),weak monsoon-non ENSO(WM-NE),strong monsoon-La Ni?a(SM-LN),normal monsoon-La Ni?a(NM-LN)and strong monsoon-non ENSO(SM-NE).Previous studies suggest that the WM-EN and SM-LN patterns reflect the correlated relationship between the SASM and El Ni?o/Southern Oscillation(ENSO)events.Therefore,we name these two strongly coupled categories WM-EN and SM-LN as the resonance effect.Two important circulations,i.e.,Walker circulation(WC)and zonal Asian monsoon circulation(MC),in the vertical plane are found to be not always correlated.The MC is controlled by thermal gradients between the Asian landmass and the tropical Indian Ocean,while the WC associated with ENSO events is primarily the east-west thermal gradient between the tropical South Pacific and the tropical Indian Ocean.Furthermore,the gradient directions caused by different surface thermal conditions are different.The main factor for the resonance effect is the phenomenon that the symbols of SSTA in the tropical Indian Ocean and the equatorial eastern Pacific are the same,but are opposite to that of the SSTA near the maritime continent.
文摘The structure of the extended gate ion sensitive field effect transistor (EGISFET) is similar to the structure of the ion sensitive field effect transistor (ISFET).Moreover,the non-ideal effect of EGISFET is the main impediment to development of commercial processes for sensitive devices.It is necessary to promote the stability and reliability of the devices by employing calibration circuits and the better fabrication conditions.The temporal drift exists in the entire measurement experiment. Furthermore,in this study we can reduce the temporal drift effect which influences the stability of the TiN sensitive electrode with the differential front-end offset circuit.The measurement system combines with shifting circuit,differential and instrument amplifiers.We employ the calibration circuit to compare with the variations of the output voltage,and expectably improve the stability and reliability of the TiN sensitive electrode by the novel calibration circuit.
文摘In this paper, the effective pyroelectric coefficient and polarization offset of the compositionally step-like graded multilayer ferroelectric structures have been studied by use of the first-principles approach. It is exhibited that the dielectric gradient has a nontrivial influence on the effective pyroelectric coefficient, but has a little influence on the polarization offset; and the polarization gradient plays an important role in the abnormal hysteresis loop phenomenon of the co.mpositionally step-like graded ferroelectric structures. Moreover, the origin of the polarization offset is explored,which can be attributed to the polarization gradient in the compositionally step-like graded structure.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11175064 and 11475060the Construct Program of the National Key Discipline of Chinathe Hunan Provincial Innovation Foundation for Postgraduates under Grant No CX2014B195
文摘We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice. Starting from an unentangled initial state associated with the regular ＇island＇ of classical phase space, it is demonstrated that the quantum resonance leads to entanglement generation, the chaotic parameter region results in the increase of the generation speed, and the symmetries of the initial probability distribution determine the final degree of entanglement. The entangled initial states are associated with the classical ＇chaotic sea＇, which do not affect the final entanglement degree for the same initial symmetry. The results may be useful in engineering quantum dynamics for quantum information processing.
基金Supported by the National Natural Science Foundation of China under Grant No 21673296the Science and technology Plan of Hunan Province under Grant No 2015RS4002the Hunan Provincial Natural Science Foundation under Grant No 2017JJ3063
文摘Quantum interference plays an important role in tuning the transport property of nano-devices. Using the non- equilibrium Green＇s Function method in combination with density functional theory, we investigate the influence to the transport property of a CO molecule adsorbed on one edge of a zigzag graphene nanoribbon device. Our results show that the CO molecule-adsorbed zigzag graphene nanoribbon devices can exhibit the Fano resonance phenomenon. Moreover, the distance between CO molecules and zigzag graphene nanoribbons is closely related to the energy sites of the Fano resonance. Our theoretical analyses indicate that the Fano resonance would be attributed to the interaction between CO molecules and the edge of the zigzag graphene nanoribbon device, which results in the localization of electrons and significantly changes the transmission spectrum.
基金Project supported by the National Natural Science Foundation of China (Grant No.12175107)the Natural Science Foundation of Nanjing Vocational University of Industry Technology (Grant No.YK22-02-08)+2 种基金the Qing Lan Project of Jiangsu Provincethe Natural Science Foundation of Jiangsu Province of China (Grant No.BK20230347)the Fund from the Research Center of Industrial Perception and Intelligent Manufacturing Equipment Engineering of Jiangsu Province,China (Grant No.ZK21-05-09)。
文摘Metal-based surface plasmon resonance(SPR)plays an important role in enhancing the photonic spin Hall effect(SHE)and developing sensitive optical sensors.However,the very large negative permittivities of metals limit their applications beyond the near-infrared regime.In this work,we theoretically present a new mechanism to enhance the photonic SHE by taking advantage of SiC-supported surface phonon resonance(SPhR)in the mid-infrared regime.The transverse displacement of photonic SHE is very sensitive to the wavelength of incident light and the thickness of SiC layer.Under the optimal parameter setup,the calculated largest transverse displacement of SiC-based SPhR structure reaches up to 163.8 ym,which is much larger than the condition of SPR.Moreover,an NO_(2) gas sensor based on the SPhR-enhanced photonic SHE is theoretically proposed with the superior sensing performance.Both the intensity and angle sensitivity of this sensor can be effectively manipulated by varying the damping rate of SiC.The results may provide a promising paradigm to enhance the photonic SHE in the mid-infrared region and open up new opportunity of highly sensitive refractive index sensors.
基金Project (10276032) supportedjointly by the National Natural Science Foundation of China and by the Science Foundationof China Academy of Engineering Physics NSAFproject(2005038228) supported by Postdoctoral Science Foundation of China projectsupported by the Postdoctoral Science Foundation of Central South University(2005)
文摘The effect of signal modulating noise in bistable stochastic resonance systems was studied theoretically and experimentally. A mathematical analysis was made on the bistable stochastic resonance model with small system parameters. An analogue circuit was designed to perform the effect. The effect of signal modulating noise was shown in the analog simulation experiment. The analog experiment was conducted for two sinusoidal signals with different frequencies. The results show that there are a sinusoidal component corresponding to the input sinusoidal signal and a noise component presented as a Wiener process corresponding to the input white noise in the system output. By properly selecting system parameters, the effect of signal modulating noise can be manifested in the system output.
基金the National Key Research and Development Program of China(Grant No.2020YFB2205804)the National Natural Science Foundation of China(Grant Nos.61974165 and Grant 61975075)the National Natural Science Foundation of China for the Youth,China(Grant No.62004105)。
文摘A monolithic integrated two-section distributed feedback(TS-DFB)semiconductor laser for high-speed direct modulation is proposed and analyzed theoretically.The grating structure of the TS-DFB laser is designed by the reconstructionequivalent-chirp(REC)technique,which can reduce the manufacturing cost and difficulty,and achieve high wavelength controlling accuracy.The detuned loading effect and the photon-photon resonance(PPR)effect are utilized to enhance the modulation bandwidth of the TS-DFB laser,exceeding 37 GHz,while that of the conventional one-section DFB laser is only 16 GHz.When the bit rate of the non-return-to-zero(NRZ)signal reaches 55 Gb/s,a clear eye diagram with large opening can still be obtained.These results show that the proposed method can enhance the modulation bandwidth of DFB laser significantly.
文摘Two sets of gold nanoparticles (NP) embedded in amorphous BaTiO3 films were prepared by sol-gel method using spin coating. Sample (1) is having BaTiO3 sol with 0.025 gm of Chloroauric acid dissolved in 10 ml of propan-2-ol, while sample (2) is having 0.086 gm of Chloroauric acid in the same amount of propan-2-ol. The films have been deposited on various substrates like borosilicate glass and fused silica. TEM images show that the particles are of 5 and 10 nm in size for the two set of samples, and some are having elongated morphology. Optical absorption properties of these films reveal the substrate and size effect on localised surface plasmon resonance (SPR). It shows a marginal red shift in the plasmon resonance peak from 414 nm to 420 nm in the case of sample (1) and 566 nm to 568 nm for sample (2) as the substrate changed from borosilicate glass to fused silica. It also shows red shift in Plasmon peak as the size increases from 5 to 10 nm and coincides with Mie explanation for the shift with size.
文摘Objective: To investigate the diagnostic effects of CT and magnetic resonance imaging (MRI) in patients with lacunar infarction. Methods: Thirty patients with early lacunar infarction in our hospital were diagnosed by ct and 30 patients were diagnosed by magnetic resonance imaging according to the examination time, the average diameter of infarct focus and examination cost. Vascular image quality (siphon segment score of internal carotid artery, petrous segment score of artery, posterior communicating artery score and basilar artery score), and the lesion detection rates of the two inspection methods were compared;Results The detection effect of MRI was superior to that of ct (P < 0.05). Conclusion: patients with lacunar infarction by magnetic resonance imaging technology and ct two ways of diagnosis, can get good diagnosis effect, but the magnetic resonance imaging technology to detect the infarct diameter is larger, the diagnosis effect is better, the detection time is shorter, however, the examination cost is more, can according to the needs of patients in clinical reasonable choice of examination methods.
基金supported by the National Natural Science Foundation of China(Grant Nos.11902002 and 51705002)the Sichuan Provincial Natural Science Foundation(Grant No.2022NSFSC0275)the University Outstanding Youth Researcher Support Program of the Education Department of Anhui Province,and the Teaching Project of the Education Department of Anhui Province(Grant No.2022xxsfkc023).
文摘This study focuses on coupled vibrations of rotating thin-walled composite beams subjected to hygrothermal effects.In the existing literature,many studies have been conducted on coupled bending-torsional vibration and resonance in hygrothermal environments.Few studies considered the coupled flapwise-edgewise and resonances of composite thin-walled beams.Considering this,the flapwise-edgewise coupling effects and resonant characteristics of rotating thin-walled composite beams in a hygrothermal environment are studied.The Rayleigh–Ritz method is used to solve the equations of the beam.Results indicate that flapwise-edgewise coupling factors are essential for the vibration analysis of rectangular thin-walled beams.The ply angle and setting angle strongly affect the internal and external resonances.Large ply angles can significantly reduce the chances of primary internal and external resonances occurring when the permitted rotational speed is lower.
基金supported by the National Natural Science Foundation of China(Grant Nos.52371267 and 52171250)。
文摘This study examines the coupling analysis between box roll motion response and free surface oscillation in a narrow gap,utilizing a two-box system comprising a small roll box and a large fixed box.The potential flow model reveals a two-peak variation in both roll motion response and free surface oscillation across incident wave frequencies.Free decay tests indicate that these frequencies correspond to the first and second resonant frequencies of the roll-fixed two-box system.Viscous fluid flow model simulations demonstrate a two-peak behavior in roll motion response,while free surface oscillation exhibits a single peak near the second resonant frequency.Repositioning the small roll box from upstream to downstream results in increased roll motion amplitude around the first resonant frequency.The roll-box with round edge profiles exhibits beating behavior in motion response,resulting in increased roll motion amplitude across a broad frequency range.Notably,wave energy at the first resonant frequency component remains undamped by round edge profiles.
