MoS2,acting as a promising gas sensing material,has shown huge potential in monitoring of toxic and harmful gases at room temperature.However,MoS2-based gas sensors still suffer from poor gas sensing performance such ...MoS2,acting as a promising gas sensing material,has shown huge potential in monitoring of toxic and harmful gases at room temperature.However,MoS2-based gas sensors still suffer from poor gas sensing performance such as poor sensitivity,long response time.Constructing the hete ro structure is an effective approach to improve gas-sensing performance of MoS2.Herein,PbS@MoS2 composites synthesized by mechanical exfoliation combining with wet-chemical precipitation are used to investigate its performance in detecting NO2 at room temperature.The response value of PbS@MoS2 gas sensor against NO2 is significantly improved compared with the pure MoS2 gas sensor.At the same time,the modification with PbS also accelerates the response speed of MoS2,and the response time is almost reduced by two orders of magnitude,from hundreds of seconds to less than ten seconds.The enhanced response value and fast response time are mainly benefited from the modulation effect of NO2 to PbS@MoS2 heterostructure and the mechanically exfoliated MoS2 surface with few defects.This work can be expected to provide useful guidance for designing composite materials with excellent gas sensing properties.展开更多
Two novel decyloxyphenylquinoxaline-based donor-acceptor （D-A） electroactive monomers bearing dialkoxythiophene as the donor unit are synthesized using Stille coupling reaction. The corresponding polymers, poly[2,3-...Two novel decyloxyphenylquinoxaline-based donor-acceptor （D-A） electroactive monomers bearing dialkoxythiophene as the donor unit are synthesized using Stille coupling reaction. The corresponding polymers, poly[2,3- bis（4-decyloxyphenyl）-5,8-bis（3,4-dimethoxylthiophen-2-yl）quinoxaline] （P1） and poly[2,3-bis（4-decyloxyphenyl）-5,8- bis（2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl）quinoxaline] （P2）, are directly deposited onto the working electrode surface by electropolymerization. All materials were characterized by nuclear magnetic resonance （NMR）, mass spectrometry （MS）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, ultraviolet-visible absorption spectrometry （UV-Vis） and spectro-electrochemical measurements. Electrochemical studies demonstrate that both polymers are capable of showing both reasonable n- and p-doping processes, and advanced long-term switching stabilities. 3,4-Ethylenedioxythiophene substituted for 3,4-dimethoxythiophene as a donor unit, which enhances the conjugated double-bond character of the conducting polymer, thus leading to a lower electronic band-gap. Likewise, the neutral state color of the synthesized polymer tuned from blue to blue-green corresponding to the red shift of the maximum absorption wavelengths in the visible region. In addition, kinetics study of P1 revealed 42% （595 nm）, 30% （839 nm） and 69% （1500 nm） transmittance changes （A7%）, while P2 exhibited 32% （740 nm）, 71% （2000 nm） at the dominant wavelengths. It was also observed that both films could switch quickly between the neutral state and oxidation state, with the response time less than 1 s both in visible and near infrared regions.展开更多
Flexible piezoresistive pressure sensors have attracted much attention for applications in health monitoring and human-machine interfaces due to their simple device structures and easy-to-read signals.For practical ap...Flexible piezoresistive pressure sensors have attracted much attention for applications in health monitoring and human-machine interfaces due to their simple device structures and easy-to-read signals.For practical applications,the deployment of flexible pressure sensors characterized by high sensitivity and fast response time is imperative for the rapid and accurate detection and monitoring of tiny signals.Such capabilities are essential for facilitating immediate feedback and informed decision-making across a spectrum of contexts.Drawing lessons from the hypersensitive and fast-responding pressure sensing structures in the dragonfly’s neck(for stable imaging during its highly maneuverable flight),a Biomimetic Piezoresistive Pressure Sensor(BPPS)with exquisite mechanically interlocking sensing microstructures is developed.Each interlocking perceptual structure pair consists of an ox-horn-shaped and a mushroom-shaped structural unit.Through the characteristic configuration of the perceptual structure pair,the BPPS realizes a fast gradient accumulation of the contact area,thus synergistically enhancing the sensitivity and fast response capability.Remarkably,the sensitivity of the BPPS reaches 0.35 kPa^(−1),which increased by 75%compared to the 0.2 kPa^(−1) of the pressure sensors without biomimetic structures.Moreover,the BPPS also achieves rapid response/recovery times(<90/15 ms).Our BPPS finds utility in tasks such as identifying objects of different weights,monitoring human respiratory status,and tracking motion,demonstrating its potential in wearable healthcare devices,assistive technology,and intelligent soft robotics.Moreover,it possesses the advantages of high sensitivity and fast response time in practical applications.展开更多
Respiratory rate monitoring is of great significance in pig healthy breeding for the early detection and timely prevention of respiratory diseases.Humidity sensing is an important noncontact method to monitor pig resp...Respiratory rate monitoring is of great significance in pig healthy breeding for the early detection and timely prevention of respiratory diseases.Humidity sensing is an important noncontact method to monitor pig respiration,which does not cause direct harm to pigs and meets the requirements of animal welfare.This paper proposes a humidity sensor based on graphene oxide wrapped-silica microspheres(GO@SiO_(2)).First,the sensor shows fast response/recovery performances of 0.24/0.73 s.Experiments demonstrate that the wrapped microsphere structure can inhibit water aggregation.It is speculated that the wrapped microsphere structure can inhibit the stacking of GO,and its curved surface can promote the evaporation of water molecules.Second,the sensor shows a high sensitivity of 1.2%/%RH-4.2%/%RH in 11%-95%RH range.This can be attributed to different sensing mechanisms,from hopping transport to increasing ion transport,leading to a significant change in the sensor’s resistance.Third,the sensor shows selectivity to water molecules due to the hydrophilic characteristic of GO and the significant increase in conductivity by ion transport.Finally,the sensor is applied to realize the respiratory rate monitoring of adult pigs and piglets.展开更多
Limited by the poor transient response performance of turbochargers,the dynamic performance of aviation piston engines tends to deteriorate.In a bid to enhance the turbocharger’s acceleration capabilities,this study ...Limited by the poor transient response performance of turbochargers,the dynamic performance of aviation piston engines tends to deteriorate.In a bid to enhance the turbocharger’s acceleration capabilities,this study scrutinizes various factors impacting its performance.Based on the operational principles and transient response process of the turbocharger,three types of in-ertiadnamely,aerodynamic inertia(ADI),thermal inertia(TI),and mechanical inertia(MI)d are identified and addressed for design.To begin,this paper pioneers the innovative definition of a method for evaluating the transient response performance of the turbocharger.This method incor-porates the introduction of an ADI parameter,inspired by the definition of MI.Subsequently,a thin-walled volute design with a low Biot number and a lightweight turbine impeller is introduced to reduce the turbocharger’s TI and MI.The simulation results of theflowfield distribution within the volute and diffuser demonstrate the comprehensive design method’s effectiveness in improving gas pressure and temperature distributions in these components.Notably,the pressure distributionfluctuation in the constant moment-of-momentum volute(CMV)is 62.8%lower than that in the constant velocity moment volute(CVMV).The low-TI thin-walled volute not only en-hances the turbocharger’s response speed but also reduces its weight by approximately 40%.The impact of three types of inertia on the engine’s response speed is quantified as follows:ADI(94%)>MI(5%)>TI(1%).This conclusion has been verified through test results of both the turbocharger and the engine.This design method not only significantly improves the turbo-charger’s response performance but also offers valuable insights for the optimal design of other blade mechanical systems.展开更多
Semiconductive metal–organic frameworks(MOFs)have attracted great interest for the electronic applications.However,dark currents of present hybrid organic–inorganic materials are 1000–10,000 times higher than those...Semiconductive metal–organic frameworks(MOFs)have attracted great interest for the electronic applications.However,dark currents of present hybrid organic–inorganic materials are 1000–10,000 times higher than those of commercial inorganic detectors,leading to poor charge transportation.Here,we demonstrate a ZIF-8(Zn(mim)_(2),mim=2-methylimidazolate)wafer with ultra-low dark current of 1.27 pA·mm^(-2) under high electric fields of 322 V·mm^(-1).The isostatic pressing preparation process provides ZIF-8 wafers with good transmittance.Besides,the presence of redox-active metals and small spatial separation between components promotes the charge hopping.The ZIF-8-based semiconductor detector shows promising X-ray detection sensitivity of 70.82μC·Gy^(-1)·cm^(-2) with low doses exposures,contributing to superior X-ray imaging capability with a relatively high spatial resolution of 1.2 lp·mm^(-1).Simultaneously,good peak discrimination with the energy resolution of~43.78%is disclosed when the detector is illuminated by uncollimated 241Am@5.48 MeVα-particles.These results provide a broad prospect of MOFs for future radiation detection applications.展开更多
Charge manipulation is crucial in optoelectronic devices.The unoptimized interfacial charge injection/extraction in solution-processed bulkheterojunction(BHJ)organic photodetectors(OPDs)presents significant challenges...Charge manipulation is crucial in optoelectronic devices.The unoptimized interfacial charge injection/extraction in solution-processed bulkheterojunction(BHJ)organic photodetectors(OPDs)presents significant challenges in achieving high detectivity and fast response speed.Here,we first develop an approach for intrinsic charge manipulation induced by molecularly engineered donors to block electron injection and facilitate hole extraction between the indium tin oxide(ITO)transparent anode and the photoactive layer.By utilizing a polymer donor with 3,4-ethylenedioxythiophene(EDOT)as the conjugated side chain,a polymer-rich layer forms spontaneously on the ITO substrate due to the increased oxygen interactions between ITO and EDOT.This results in electron-blocking-layer(EBL)-free devices with lower dark current and noise without a reduction in responsivity compared to control devices.As a result,the EBL-free devices exhibit a peak specific detectivity of 2.36×10^(13) Jones at 950 nm and achieve a-3 dB bandwidth of 30 MHz under-1 V.Enhanced stability is also observed compared to the devices with poly(3,4-ethylenedioxythiophene)polystyrene sulfonate(PEDOT:PSS).This work demonstrates a new method to intrinsically manipulate charge injection in BHJ photoactive layers,enabling the fabrication of solution-processed EBL-free OPDs with high sensitivity,rapid response,and good stability.展开更多
In the last decade,optoelectronic devices based on organic-inorganic hybrid perovskite(OIHP)materials,which have unique advantages of direct bandgap,large absorption coefficient,low density of defects,long charge carr...In the last decade,optoelectronic devices based on organic-inorganic hybrid perovskite(OIHP)materials,which have unique advantages of direct bandgap,large absorption coefficient,low density of defects,long charge carrier lifetime,diffusion length,and solution processability,have traveled with traditional inorganic semiconductor devices.The state-of-the-art OIHP photodetectors have contributed a comparable performance with Si and III-V compound semiconductor based photodetectors.Large amount of efforts have been focused on improving sensitivity,broadening detection spectra,enlarging linear dynamic range.However,few reports emphasized the important parameter of response speed.In this review,we summarize the progress and applications of OIHP photodetectors with fast response.Based on photovoltaic and photoconductive-type OIHP photodetectors,the working principle and key factors on determining response speed are systematically mentioned.Then,the research progress of response speed,which is composed of resistance-capacitance(RC)time constant and charge carrier transit time is discussed in detail.Subsequently,considering the intrinsic flexibility of perovskite materials,we briefly discuss the flexible photodetectors.Finally,an outlook and potential rules for designing fast-response OIHP photodetectors are further proposed.展开更多
This paper describes the measurements and the post-processing procedure adopted for the determination of the turbulence intensity in a low pressure turbine (LPT) by means of a single sensor fast response aerodynamic p...This paper describes the measurements and the post-processing procedure adopted for the determination of the turbulence intensity in a low pressure turbine (LPT) by means of a single sensor fast response aerodynamic pressure probe. The rig was designed in cooperation with MTU Aero Engines and considerable efforts were put into the adjustment of all relevant model parameters. Blade count ratio, airfoil aspect ratio, reduced massflow, reduced speed, inlet turbulence intensity and Reynolds numbers were chosen to reproduce the full scale LP turbine. Measurements were performed adopting a phase-locked acquisition technique in order to provide the time resolved flow field downstream of the turbine rotor. The total pressure random fluctuations are obtained by selectively filtering, in the frequency domain, the deterministic unsteadiness due to the rotor blades and coherent structures. The turbulence intensity is derived from the inverse Fourier transform and the correlations between total pressure and velocity fluctuations. The determination of the turbulence intensity allows the discussion of the interaction processes between the stator and rotor for engine-representative operating conditions of the turbine.展开更多
A polymer/silica hybrid 2×2 multimode-interference switch is designed and fabricated. Instead of polymer Mach-Zehnder interferometer thermo-optic （TO） silica is used as under-cladding to accelerate heat release...A polymer/silica hybrid 2×2 multimode-interference switch is designed and fabricated. Instead of polymer Mach-Zehnder interferometer thermo-optic （TO） silica is used as under-cladding to accelerate heat release because of its large thermal conductivity. The developed switch exhibits low power consumption of 6.2 mW, low crosstalk of about 28 dB, and short response time. The rise and fall times of 103 and 91 its for this hybrid switch are shortened by 40.8% and 52.4%, respectively, compared with those of the fabricated TO switch （174 and 191 μs） using polymer as both upper- and under-claddings.展开更多
This paper provides practical data for thermal product values of different scratched temperature sensors that can be used for accurate transient heat transfer measurements under hypersonic flow conditions.The effect o...This paper provides practical data for thermal product values of different scratched temperature sensors that can be used for accurate transient heat transfer measurements under hypersonic flow conditions.The effect of using different scratch techniques(abrasive papers and scalpel blades)to form the sensor's junction is investigated.It was observed that the thermal product of a particular sensor depends on the Mach number,junction scratch technique, junction location and enthalpy conditions.It was demonstrated that using different scratched technique would produce different thermal product values.展开更多
By utilizing Schottky contact in device fabrication,we have constructed fast response ultraviolet photodetectors based on the solution-processed Zn O nanocrystals.At 5 V,the detector exhibits fast photoresponse with a...By utilizing Schottky contact in device fabrication,we have constructed fast response ultraviolet photodetectors based on the solution-processed Zn O nanocrystals.At 5 V,the detector exhibits fast photoresponse with a rise time of 20 ns and fall time of 350 ns,which is one of the fastest response time among the reported Zn O-based photodetectors.The results reported in this paper may show great promise for fast response optoelectronic devices based on the solution-processed nanocrystals.展开更多
Quasi-one-dimensional semiconductor nanostructure-based photodetectors show high sensitivity but suffer from slow response speed due to surface reaction. Here, we report a fast-response CdS-CdSxTei-x-CdTe core-shell n...Quasi-one-dimensional semiconductor nanostructure-based photodetectors show high sensitivity but suffer from slow response speed due to surface reaction. Here, we report a fast-response CdS-CdSxTei-x-CdTe core-shell nanobelt photodetector with a rise time of 11 /.is, which is the fastest among CdS based photodetectors reported previously. The improved response speed is ascribed to the sup-pressed possibilities of surface reaction resulting from the core-shell structure and heterojunction among the CdS, CdSxTel-x and CdTe. The measured response spectrum of CdS-CdSxTe1-x-CdTe core-shell nano-belt photodetector covers a wide range from 355 to 785 nm. Moreover, high responsivity （1,520 A/W） and large 3 dB bandwidth （~22.9 kHz） are obtained along with the fast response, The high performance in responsivity, sensitivity, spectral response and photoresponse speed makes this device a promising candidate for practical application in optical sensing, communication and imaging.展开更多
Six coupled general circulation models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) are em-ployed for examining the full evolution of the North Pacific mode water and Subtropical Countercurrent (STCC...Six coupled general circulation models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) are em-ployed for examining the full evolution of the North Pacific mode water and Subtropical Countercurrent (STCC) under global warming over 400 years following the Representative Concentration Pathways (RCP) 4.5. The mode water and STCC first show a sharp weakening trend when the radiative forcing increases, but then reverse to a slow strengthening trend of smaller magnitude after the radiative forcing is stablized. As the radiative forcing increases during the 21st century, the ocean warming is surface-intensified and decreases with depth, strengthening the upper ocean's stratification and becoming unfavorable for the mode water formation. Moving southward in the subtropical gyre, the shrinking mode water decelerates the STCC to the south. After the radiative forcing is stabilized in the 2070s, the subsequent warming is greater at the subsurface than at the sea surface, destabilizing the upper ocean and becoming favorable for the mode water formation. As a result, the mode water and STCC recover gradually after the radiative forc-ing is stabilized.展开更多
The inertia response and primary frequency regulation capability of synchronous grids are declining owing to the increasing penetration of inverter-based resources. The fast frequency response(FFR) of inverter-based r...The inertia response and primary frequency regulation capability of synchronous grids are declining owing to the increasing penetration of inverter-based resources. The fast frequency response(FFR) of inverter-based resources is an important mitigation option for maintaining grid security under the conditions of low inertia and insufficient primary frequency response capability. However, the understanding and technical characteristics of the FFR of inverter-based resources are still unclear. Aiming at solving the aforementioned problems, this paper proposes a definition for FFR based on the impact mechanism of FFR on system frequency. The performance requirements of FFR are clarified. Then, the effects of FFR on system frequency characteristics are further analyzed based on steady-state frequency deviation, the initial rate of change of frequency, and the maximum transient frequency deviation. Finally, the system requirements for FFR and its application effects are verified by simulating an actual bulk power grid, providing technical support for subsequent engineering application.展开更多
In 26 patients with confirmed primary verified gonarthrosis(PGA),a clinical and instrumental examination was conducted to evaluate the response energy osteopathy followed by statistical processing of the data.Three ty...In 26 patients with confirmed primary verified gonarthrosis(PGA),a clinical and instrumental examination was conducted to evaluate the response energy osteopathy followed by statistical processing of the data.Three types of the body’s response to treatment were identified:immediate,fast,and delayed,which,despite the different informative value of the data of the polyparametric study,allowed judging the effectiveness of the method used.展开更多
In this study,the decomposed fast and slow responses of clouds to an abruptly quadrupled CO_(2)concentration(approximately 1139 ppmv)in East Asia(EA)are obtained quantitatively by using a general circulation model,BCC...In this study,the decomposed fast and slow responses of clouds to an abruptly quadrupled CO_(2)concentration(approximately 1139 ppmv)in East Asia(EA)are obtained quantitatively by using a general circulation model,BCC–AGCM2.0.Our results show that in the total response,the total cloud cover(TCC),low cloud cover(LCC),and high cloud cover(HCC)all increased north of 40°N and decreased south of 40°N except in the Tibetan Plateau(TP).The mean changes of the TCC,LCC,and HCC in EA were–0.74%,0.38%,and–0.38%in the total response,respectively;1.05%,–0.03%,and 1.63%in the fast response,respectively;and–1.79%,0.41%,and–2.01%in the slow response,respectively.By comparison,we found that changes in cloud cover were dominated by the slow response in most areas in EA due to the changes in atmospheric temperature,circulation,and water vapor supply together.Overall,the changes in the cloud forcing over EA related to the fast and slow responses were opposite to each other,and the final cloud forcing was dominated by the slow response.The mean net cloud forcing(NCF)in the total response over EA was–1.80 W m^(–2),indicating a cooling effect which partially offset the warming effect caused by the quadrupled CO_(2).The total responses of NCF in the TP,south China(SC),and northeast China(NE)were–6.74 W m^(–2),6.11 W m^(–2),and–7.49 W m^(–2),respectively.Thus,the local effects of offsetting or amplifying warming were particularly obvious.展开更多
The unique arrangement of panels and folds in origami structures provides distinct mechanical properties,such as the ability to achieve multiple stable states,reconfigure shapes,and adjust performance.However,combinin...The unique arrangement of panels and folds in origami structures provides distinct mechanical properties,such as the ability to achieve multiple stable states,reconfigure shapes,and adjust performance.However,combining movement and control functions into a simple yet efficient origami-based system remains a challenge.This study introduces a practical and efficient bistable origami mechanism,realized through lightweight and tailored designs in two bio-inspired applications.The mechanism is constructed from two thin materials:a PET sheet with precisely cut flexible hinges and a pre-tensioned elastic band.Its mechanical behavior is studied using nonlinear spring models.These components can be rearranged to create new bistable structures,enabling the integration of movement and partial control features.Inspired by natural systems,the mechanism is applied to two examples:a passive origami gripper that can quickly and precisely grasp moving objects in less than 100 ms,and an active magnetic-driven fish tail capable of high-speed swimming in multiple modes,reaching a maximum straight-line speed of 3.35 body lengths per second and a turning speed of 2.3 radians per second.This bistable origami mechanism highlights its potential for flexible design and high performance,offering useful insights for developing origami-based robotic systems.展开更多
Aging-related diseases are gradually becoming a major problem with the rapid development of aged population in human society.Although many fluorescent probes have been employed to diagnosis senescence via imaging sene...Aging-related diseases are gradually becoming a major problem with the rapid development of aged population in human society.Although many fluorescent probes have been employed to diagnosis senescence via imaging senescence-associatedβ-galactosidase(SA-β-Gal),which is proved to be closely associated with senescent cells,the similar catalytic effectiveness of enzymatic reaction of ovarian cancer-associatedβ-Gal(OA-β-Gal)will interfere with imaging accuracy.Herein,a near-infrared(NIR)hemicyanine based fluorescent probe HCyXA-βGal was designed for light-up imaging of live cells containingβ-Gal.With the organelle-targeting morpholinyl and positive charge moieties,HCyxA-βGal was successfully applicated to image the difference of enzymatic location in senescent cells and ovarian cancer cells.Furthermore,inspired by the fast response performance,fast and precise imaging of the two cell lines was realized via covering another dimension of fluorescence signal:time-dependent intensity.展开更多
Controllable synthesis of luminescent metal-organic frameworks (MOFs) having the merits of ease preparation, outstanding sensitivity and stability is of great significance for exploring their efficient sensing applica...Controllable synthesis of luminescent metal-organic frameworks (MOFs) having the merits of ease preparation, outstanding sensitivity and stability is of great significance for exploring their efficient sensing applications. Herein, we report a hierarchical terbium-doped yttrium-benzene-1,3,5-tricarboxylate MOF nanosheet via solvent-free synthetic strategy with a topological structure of MIL-78. The fluorescence property of the hierarchical Tb^(3+)-doped Y-based MOF nanosheets can be tuned by adjusting the molar ratio of Tb^(3+) to Y^(3+) ions, and the Tb_(0.5)Y_(0.5)-MOF nanosheet-like morphology with the optimum characteristic Tb^(3+) ion green emission exhibited great potential acting as fluorescence probe for highly sensitive Fe^(3+) and Cr_(2)O_(7)^(2−) detection. The Tb^(3+)-doped Y-MOF nanosheets show a fast response time of less than 1 s for Fe^(3+) ions. They also have low detection limits of 0.40 and 0.26 µM toward Fe^(3+) and Cr_(2)O_(7)^(2−) ions, respectively, as well as excellent stability. This work paves the way to explore intriguing hierarchical MOF-based luminescent materials for efficient fluorescence sensing applications.展开更多
基金supported by Hunan Provincial Natural Science Foundation of China(No.2018JJ2404)Scientific Research Foundation of Hunan Provincial Education Department(Nos.19A475,19C1739)Hunan Science and Technology Plan Program(No.2019RS1056)。
文摘MoS2,acting as a promising gas sensing material,has shown huge potential in monitoring of toxic and harmful gases at room temperature.However,MoS2-based gas sensors still suffer from poor gas sensing performance such as poor sensitivity,long response time.Constructing the hete ro structure is an effective approach to improve gas-sensing performance of MoS2.Herein,PbS@MoS2 composites synthesized by mechanical exfoliation combining with wet-chemical precipitation are used to investigate its performance in detecting NO2 at room temperature.The response value of PbS@MoS2 gas sensor against NO2 is significantly improved compared with the pure MoS2 gas sensor.At the same time,the modification with PbS also accelerates the response speed of MoS2,and the response time is almost reduced by two orders of magnitude,from hundreds of seconds to less than ten seconds.The enhanced response value and fast response time are mainly benefited from the modulation effect of NO2 to PbS@MoS2 heterostructure and the mechanically exfoliated MoS2 surface with few defects.This work can be expected to provide useful guidance for designing composite materials with excellent gas sensing properties.
基金financially supported by the National Natural Science Foundation of China(Nos.51473074 and 31400044)the General and Special Program of the Postdoctoral Science Foundation China(Nos.2013M530397 and 2014T70861)+1 种基金the Postgraduate Innovation Project of China University of Petroleum(East China)(No.YCX2015022)the Fundamental Research Funds for the Central Universities(No.15CX06049A)
文摘Two novel decyloxyphenylquinoxaline-based donor-acceptor （D-A） electroactive monomers bearing dialkoxythiophene as the donor unit are synthesized using Stille coupling reaction. The corresponding polymers, poly[2,3- bis（4-decyloxyphenyl）-5,8-bis（3,4-dimethoxylthiophen-2-yl）quinoxaline] （P1） and poly[2,3-bis（4-decyloxyphenyl）-5,8- bis（2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl）quinoxaline] （P2）, are directly deposited onto the working electrode surface by electropolymerization. All materials were characterized by nuclear magnetic resonance （NMR）, mass spectrometry （MS）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, ultraviolet-visible absorption spectrometry （UV-Vis） and spectro-electrochemical measurements. Electrochemical studies demonstrate that both polymers are capable of showing both reasonable n- and p-doping processes, and advanced long-term switching stabilities. 3,4-Ethylenedioxythiophene substituted for 3,4-dimethoxythiophene as a donor unit, which enhances the conjugated double-bond character of the conducting polymer, thus leading to a lower electronic band-gap. Likewise, the neutral state color of the synthesized polymer tuned from blue to blue-green corresponding to the red shift of the maximum absorption wavelengths in the visible region. In addition, kinetics study of P1 revealed 42% （595 nm）, 30% （839 nm） and 69% （1500 nm） transmittance changes （A7%）, while P2 exhibited 32% （740 nm）, 71% （2000 nm） at the dominant wavelengths. It was also observed that both films could switch quickly between the neutral state and oxidation state, with the response time less than 1 s both in visible and near infrared regions.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52021003)National Natural Science Foundation of China(Nos.52222509,52105301)+1 种基金the Natural Science Foundation of Jilin Province(Grant No.20220101220JC)supported by“Fundamental Research Funds for the Central Universities”.
文摘Flexible piezoresistive pressure sensors have attracted much attention for applications in health monitoring and human-machine interfaces due to their simple device structures and easy-to-read signals.For practical applications,the deployment of flexible pressure sensors characterized by high sensitivity and fast response time is imperative for the rapid and accurate detection and monitoring of tiny signals.Such capabilities are essential for facilitating immediate feedback and informed decision-making across a spectrum of contexts.Drawing lessons from the hypersensitive and fast-responding pressure sensing structures in the dragonfly’s neck(for stable imaging during its highly maneuverable flight),a Biomimetic Piezoresistive Pressure Sensor(BPPS)with exquisite mechanically interlocking sensing microstructures is developed.Each interlocking perceptual structure pair consists of an ox-horn-shaped and a mushroom-shaped structural unit.Through the characteristic configuration of the perceptual structure pair,the BPPS realizes a fast gradient accumulation of the contact area,thus synergistically enhancing the sensitivity and fast response capability.Remarkably,the sensitivity of the BPPS reaches 0.35 kPa^(−1),which increased by 75%compared to the 0.2 kPa^(−1) of the pressure sensors without biomimetic structures.Moreover,the BPPS also achieves rapid response/recovery times(<90/15 ms).Our BPPS finds utility in tasks such as identifying objects of different weights,monitoring human respiratory status,and tracking motion,demonstrating its potential in wearable healthcare devices,assistive technology,and intelligent soft robotics.Moreover,it possesses the advantages of high sensitivity and fast response time in practical applications.
基金supported by the National Natural Science Foundation of China(Grant No.12302127)the Talents Introduction Project of Xihua University(Grant No.Z241008)the Key Project of Sichuan Province Modern Agricultural Equipment Engineering Technology Research Center(Grant No.XDNY2024-002).
文摘Respiratory rate monitoring is of great significance in pig healthy breeding for the early detection and timely prevention of respiratory diseases.Humidity sensing is an important noncontact method to monitor pig respiration,which does not cause direct harm to pigs and meets the requirements of animal welfare.This paper proposes a humidity sensor based on graphene oxide wrapped-silica microspheres(GO@SiO_(2)).First,the sensor shows fast response/recovery performances of 0.24/0.73 s.Experiments demonstrate that the wrapped microsphere structure can inhibit water aggregation.It is speculated that the wrapped microsphere structure can inhibit the stacking of GO,and its curved surface can promote the evaporation of water molecules.Second,the sensor shows a high sensitivity of 1.2%/%RH-4.2%/%RH in 11%-95%RH range.This can be attributed to different sensing mechanisms,from hopping transport to increasing ion transport,leading to a significant change in the sensor’s resistance.Third,the sensor shows selectivity to water molecules due to the hydrophilic characteristic of GO and the significant increase in conductivity by ion transport.Finally,the sensor is applied to realize the respiratory rate monitoring of adult pigs and piglets.
基金funded by the Basic Research Program of the National Nature Science Foundation of China (Grant number[52206131],[U2233213],[51775025]and[U2333217])National Key R&D Program of China,grant number[2022YFB2602002]and[2018YFB0104100]+1 种基金Zhejiang Provincial Natural Science Foundation of China,grant number[LQ22E060004]Science Center of Gas Turbine Project[P2022-A-I-001-001].
文摘Limited by the poor transient response performance of turbochargers,the dynamic performance of aviation piston engines tends to deteriorate.In a bid to enhance the turbocharger’s acceleration capabilities,this study scrutinizes various factors impacting its performance.Based on the operational principles and transient response process of the turbocharger,three types of in-ertiadnamely,aerodynamic inertia(ADI),thermal inertia(TI),and mechanical inertia(MI)d are identified and addressed for design.To begin,this paper pioneers the innovative definition of a method for evaluating the transient response performance of the turbocharger.This method incor-porates the introduction of an ADI parameter,inspired by the definition of MI.Subsequently,a thin-walled volute design with a low Biot number and a lightweight turbine impeller is introduced to reduce the turbocharger’s TI and MI.The simulation results of theflowfield distribution within the volute and diffuser demonstrate the comprehensive design method’s effectiveness in improving gas pressure and temperature distributions in these components.Notably,the pressure distributionfluctuation in the constant moment-of-momentum volute(CMV)is 62.8%lower than that in the constant velocity moment volute(CVMV).The low-TI thin-walled volute not only en-hances the turbocharger’s response speed but also reduces its weight by approximately 40%.The impact of three types of inertia on the engine’s response speed is quantified as follows:ADI(94%)>MI(5%)>TI(1%).This conclusion has been verified through test results of both the turbocharger and the engine.This design method not only significantly improves the turbo-charger’s response performance but also offers valuable insights for the optimal design of other blade mechanical systems.
基金supported by the National Natural Science Foundations of China(Nos.U2032170 and 62104194)The project was also supported by the Natural Science Basic Research Plan in Shaanxi Province of China(No.2021GXLH-01-03)+2 种基金the ND Basic Research Funds(No.G2022WD)the Research Fund of the State Key Laboratory of Solidification Processing(NPU)China(No.2022-TS-07).
文摘Semiconductive metal–organic frameworks(MOFs)have attracted great interest for the electronic applications.However,dark currents of present hybrid organic–inorganic materials are 1000–10,000 times higher than those of commercial inorganic detectors,leading to poor charge transportation.Here,we demonstrate a ZIF-8(Zn(mim)_(2),mim=2-methylimidazolate)wafer with ultra-low dark current of 1.27 pA·mm^(-2) under high electric fields of 322 V·mm^(-1).The isostatic pressing preparation process provides ZIF-8 wafers with good transmittance.Besides,the presence of redox-active metals and small spatial separation between components promotes the charge hopping.The ZIF-8-based semiconductor detector shows promising X-ray detection sensitivity of 70.82μC·Gy^(-1)·cm^(-2) with low doses exposures,contributing to superior X-ray imaging capability with a relatively high spatial resolution of 1.2 lp·mm^(-1).Simultaneously,good peak discrimination with the energy resolution of~43.78%is disclosed when the detector is illuminated by uncollimated 241Am@5.48 MeVα-particles.These results provide a broad prospect of MOFs for future radiation detection applications.
基金the Shenzhen Fundamental Research Funding(Key Program,No.JCYJ20200109141405950)Shenzhen Key Lab Funding(No.ZDSYS2015052915525382)+6 种基金the National Natural Science Foundation of China(No.51703092)the European Research Council for support under the European Union's Horizon 2020 Research and Innovation Program(Nos.742708 and 648901)support under Guangdong Provincial Natural Science Foundation General Project(No.2024A1515012318)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515111140)Shenzhen government for support under the special appointed position-“Pengcheng Peacock Plan-C”The Chinese University of Hong Kong(Shenzhen)for support under The University Development Fund(No.UDF01003117)Special Funds for High-Level Universities-Talent Projects-“Presidential Young Fellow”(No.UF02003117).
文摘Charge manipulation is crucial in optoelectronic devices.The unoptimized interfacial charge injection/extraction in solution-processed bulkheterojunction(BHJ)organic photodetectors(OPDs)presents significant challenges in achieving high detectivity and fast response speed.Here,we first develop an approach for intrinsic charge manipulation induced by molecularly engineered donors to block electron injection and facilitate hole extraction between the indium tin oxide(ITO)transparent anode and the photoactive layer.By utilizing a polymer donor with 3,4-ethylenedioxythiophene(EDOT)as the conjugated side chain,a polymer-rich layer forms spontaneously on the ITO substrate due to the increased oxygen interactions between ITO and EDOT.This results in electron-blocking-layer(EBL)-free devices with lower dark current and noise without a reduction in responsivity compared to control devices.As a result,the EBL-free devices exhibit a peak specific detectivity of 2.36×10^(13) Jones at 950 nm and achieve a-3 dB bandwidth of 30 MHz under-1 V.Enhanced stability is also observed compared to the devices with poly(3,4-ethylenedioxythiophene)polystyrene sulfonate(PEDOT:PSS).This work demonstrates a new method to intrinsically manipulate charge injection in BHJ photoactive layers,enabling the fabrication of solution-processed EBL-free OPDs with high sensitivity,rapid response,and good stability.
基金The authors are grateful to National Natural Science Foundation of China(61875072)International Cooperation and Exchange Project of People's Government of Jilin Province(20170414002GH,20180414001GH)for their supports to this work.
文摘In the last decade,optoelectronic devices based on organic-inorganic hybrid perovskite(OIHP)materials,which have unique advantages of direct bandgap,large absorption coefficient,low density of defects,long charge carrier lifetime,diffusion length,and solution processability,have traveled with traditional inorganic semiconductor devices.The state-of-the-art OIHP photodetectors have contributed a comparable performance with Si and III-V compound semiconductor based photodetectors.Large amount of efforts have been focused on improving sensitivity,broadening detection spectra,enlarging linear dynamic range.However,few reports emphasized the important parameter of response speed.In this review,we summarize the progress and applications of OIHP photodetectors with fast response.Based on photovoltaic and photoconductive-type OIHP photodetectors,the working principle and key factors on determining response speed are systematically mentioned.Then,the research progress of response speed,which is composed of resistance-capacitance(RC)time constant and charge carrier transit time is discussed in detail.Subsequently,considering the intrinsic flexibility of perovskite materials,we briefly discuss the flexible photodetectors.Finally,an outlook and potential rules for designing fast-response OIHP photodetectors are further proposed.
基金the EU project VITAL,contract no.AIP4-CT-2004-012271,is acknowledged in which the stage was designed,manufactured and operated
文摘This paper describes the measurements and the post-processing procedure adopted for the determination of the turbulence intensity in a low pressure turbine (LPT) by means of a single sensor fast response aerodynamic pressure probe. The rig was designed in cooperation with MTU Aero Engines and considerable efforts were put into the adjustment of all relevant model parameters. Blade count ratio, airfoil aspect ratio, reduced massflow, reduced speed, inlet turbulence intensity and Reynolds numbers were chosen to reproduce the full scale LP turbine. Measurements were performed adopting a phase-locked acquisition technique in order to provide the time resolved flow field downstream of the turbine rotor. The total pressure random fluctuations are obtained by selectively filtering, in the frequency domain, the deterministic unsteadiness due to the rotor blades and coherent structures. The turbulence intensity is derived from the inverse Fourier transform and the correlations between total pressure and velocity fluctuations. The determination of the turbulence intensity allows the discussion of the interaction processes between the stator and rotor for engine-representative operating conditions of the turbine.
基金supported by the National Natural Science Foundation of China (Nos. 61077041, 61107021,and 61177027)the Ministry of Education of China (Nos.20110061120052 and 20090061110041)+1 种基金the China Post-doctoral Science Foundation (No. 20110491299)the Special Funds of Basic Science and Technology of Jilin University (Nos. 200905005, 201100253, and 201103076)
文摘A polymer/silica hybrid 2×2 multimode-interference switch is designed and fabricated. Instead of polymer Mach-Zehnder interferometer thermo-optic （TO） silica is used as under-cladding to accelerate heat release because of its large thermal conductivity. The developed switch exhibits low power consumption of 6.2 mW, low crosstalk of about 28 dB, and short response time. The rise and fall times of 103 and 91 its for this hybrid switch are shortened by 40.8% and 52.4%, respectively, compared with those of the fabricated TO switch （174 and 191 μs） using polymer as both upper- and under-claddings.
文摘This paper provides practical data for thermal product values of different scratched temperature sensors that can be used for accurate transient heat transfer measurements under hypersonic flow conditions.The effect of using different scratch techniques(abrasive papers and scalpel blades)to form the sensor's junction is investigated.It was observed that the thermal product of a particular sensor depends on the Mach number,junction scratch technique, junction location and enthalpy conditions.It was demonstrated that using different scratched technique would produce different thermal product values.
基金supported by the Natural Science Foundation of Liaoning Province of China(Grant No.2013020010)
文摘By utilizing Schottky contact in device fabrication,we have constructed fast response ultraviolet photodetectors based on the solution-processed Zn O nanocrystals.At 5 V,the detector exhibits fast photoresponse with a rise time of 20 ns and fall time of 350 ns,which is one of the fastest response time among the reported Zn O-based photodetectors.The results reported in this paper may show great promise for fast response optoelectronic devices based on the solution-processed nanocrystals.
基金supported by the National Natural Science Foundation of China(51672245 and 61735017)the National Key Basic Research Program of China(2015CB352003)+2 种基金Zhejiang Provincial Natural Science Foundation of China(R17F050003)the Fundamental Research Funds for the Central Universitiesthe Program for Zhejiang Leading Team of S&T Innovation
文摘Quasi-one-dimensional semiconductor nanostructure-based photodetectors show high sensitivity but suffer from slow response speed due to surface reaction. Here, we report a fast-response CdS-CdSxTei-x-CdTe core-shell nanobelt photodetector with a rise time of 11 /.is, which is the fastest among CdS based photodetectors reported previously. The improved response speed is ascribed to the sup-pressed possibilities of surface reaction resulting from the core-shell structure and heterojunction among the CdS, CdSxTel-x and CdTe. The measured response spectrum of CdS-CdSxTe1-x-CdTe core-shell nano-belt photodetector covers a wide range from 355 to 785 nm. Moreover, high responsivity （1,520 A/W） and large 3 dB bandwidth （~22.9 kHz） are obtained along with the fast response, The high performance in responsivity, sensitivity, spectral response and photoresponse speed makes this device a promising candidate for practical application in optical sensing, communication and imaging.
基金supported by the National Basic Research Program of China(2012CB955602)National Key Program for Developing Basic Science(2010CB428904)Natural Science Foundation of China(41176006 and 40921004)
文摘Six coupled general circulation models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) are em-ployed for examining the full evolution of the North Pacific mode water and Subtropical Countercurrent (STCC) under global warming over 400 years following the Representative Concentration Pathways (RCP) 4.5. The mode water and STCC first show a sharp weakening trend when the radiative forcing increases, but then reverse to a slow strengthening trend of smaller magnitude after the radiative forcing is stablized. As the radiative forcing increases during the 21st century, the ocean warming is surface-intensified and decreases with depth, strengthening the upper ocean's stratification and becoming unfavorable for the mode water formation. Moving southward in the subtropical gyre, the shrinking mode water decelerates the STCC to the south. After the radiative forcing is stabilized in the 2070s, the subsequent warming is greater at the subsurface than at the sea surface, destabilizing the upper ocean and becoming favorable for the mode water formation. As a result, the mode water and STCC recover gradually after the radiative forc-ing is stabilized.
基金supported by National Science Foundation of China(51477091)。
文摘The inertia response and primary frequency regulation capability of synchronous grids are declining owing to the increasing penetration of inverter-based resources. The fast frequency response(FFR) of inverter-based resources is an important mitigation option for maintaining grid security under the conditions of low inertia and insufficient primary frequency response capability. However, the understanding and technical characteristics of the FFR of inverter-based resources are still unclear. Aiming at solving the aforementioned problems, this paper proposes a definition for FFR based on the impact mechanism of FFR on system frequency. The performance requirements of FFR are clarified. Then, the effects of FFR on system frequency characteristics are further analyzed based on steady-state frequency deviation, the initial rate of change of frequency, and the maximum transient frequency deviation. Finally, the system requirements for FFR and its application effects are verified by simulating an actual bulk power grid, providing technical support for subsequent engineering application.
文摘In 26 patients with confirmed primary verified gonarthrosis(PGA),a clinical and instrumental examination was conducted to evaluate the response energy osteopathy followed by statistical processing of the data.Three types of the body’s response to treatment were identified:immediate,fast,and delayed,which,despite the different informative value of the data of the polyparametric study,allowed judging the effectiveness of the method used.
基金supported by the National Key R&D Program of China(2017YFA0603502)the National Natural Science Foundation of China(Grant No.41905081)S&T Development Fund of CAMS(2021KJ004&2022KJ019).
文摘In this study,the decomposed fast and slow responses of clouds to an abruptly quadrupled CO_(2)concentration(approximately 1139 ppmv)in East Asia(EA)are obtained quantitatively by using a general circulation model,BCC–AGCM2.0.Our results show that in the total response,the total cloud cover(TCC),low cloud cover(LCC),and high cloud cover(HCC)all increased north of 40°N and decreased south of 40°N except in the Tibetan Plateau(TP).The mean changes of the TCC,LCC,and HCC in EA were–0.74%,0.38%,and–0.38%in the total response,respectively;1.05%,–0.03%,and 1.63%in the fast response,respectively;and–1.79%,0.41%,and–2.01%in the slow response,respectively.By comparison,we found that changes in cloud cover were dominated by the slow response in most areas in EA due to the changes in atmospheric temperature,circulation,and water vapor supply together.Overall,the changes in the cloud forcing over EA related to the fast and slow responses were opposite to each other,and the final cloud forcing was dominated by the slow response.The mean net cloud forcing(NCF)in the total response over EA was–1.80 W m^(–2),indicating a cooling effect which partially offset the warming effect caused by the quadrupled CO_(2).The total responses of NCF in the TP,south China(SC),and northeast China(NE)were–6.74 W m^(–2),6.11 W m^(–2),and–7.49 W m^(–2),respectively.Thus,the local effects of offsetting or amplifying warming were particularly obvious.
基金supported in part by the Fundamental Research Funds for the Central Universities under Grant CSA-TS202404in part by the National Natural Science Foundation of China under Grant 12172226.
文摘The unique arrangement of panels and folds in origami structures provides distinct mechanical properties,such as the ability to achieve multiple stable states,reconfigure shapes,and adjust performance.However,combining movement and control functions into a simple yet efficient origami-based system remains a challenge.This study introduces a practical and efficient bistable origami mechanism,realized through lightweight and tailored designs in two bio-inspired applications.The mechanism is constructed from two thin materials:a PET sheet with precisely cut flexible hinges and a pre-tensioned elastic band.Its mechanical behavior is studied using nonlinear spring models.These components can be rearranged to create new bistable structures,enabling the integration of movement and partial control features.Inspired by natural systems,the mechanism is applied to two examples:a passive origami gripper that can quickly and precisely grasp moving objects in less than 100 ms,and an active magnetic-driven fish tail capable of high-speed swimming in multiple modes,reaching a maximum straight-line speed of 3.35 body lengths per second and a turning speed of 2.3 radians per second.This bistable origami mechanism highlights its potential for flexible design and high performance,offering useful insights for developing origami-based robotic systems.
基金supported by National Natural Science Foundation of China(Nos.22122803 and 21788102)the National Natural Science Foundation of Jiangsu Province(No.BK20220644).
文摘Aging-related diseases are gradually becoming a major problem with the rapid development of aged population in human society.Although many fluorescent probes have been employed to diagnosis senescence via imaging senescence-associatedβ-galactosidase(SA-β-Gal),which is proved to be closely associated with senescent cells,the similar catalytic effectiveness of enzymatic reaction of ovarian cancer-associatedβ-Gal(OA-β-Gal)will interfere with imaging accuracy.Herein,a near-infrared(NIR)hemicyanine based fluorescent probe HCyXA-βGal was designed for light-up imaging of live cells containingβ-Gal.With the organelle-targeting morpholinyl and positive charge moieties,HCyxA-βGal was successfully applicated to image the difference of enzymatic location in senescent cells and ovarian cancer cells.Furthermore,inspired by the fast response performance,fast and precise imaging of the two cell lines was realized via covering another dimension of fluorescence signal:time-dependent intensity.
基金supported by National Natural Science Foundation of China(Grants Nos.22171040 and 22005203)the Guiding Project of the Science and Technology Researching Program of Liaoning Provin-cial Education Department(No.2019-ZD-0074).
文摘Controllable synthesis of luminescent metal-organic frameworks (MOFs) having the merits of ease preparation, outstanding sensitivity and stability is of great significance for exploring their efficient sensing applications. Herein, we report a hierarchical terbium-doped yttrium-benzene-1,3,5-tricarboxylate MOF nanosheet via solvent-free synthetic strategy with a topological structure of MIL-78. The fluorescence property of the hierarchical Tb^(3+)-doped Y-based MOF nanosheets can be tuned by adjusting the molar ratio of Tb^(3+) to Y^(3+) ions, and the Tb_(0.5)Y_(0.5)-MOF nanosheet-like morphology with the optimum characteristic Tb^(3+) ion green emission exhibited great potential acting as fluorescence probe for highly sensitive Fe^(3+) and Cr_(2)O_(7)^(2−) detection. The Tb^(3+)-doped Y-MOF nanosheets show a fast response time of less than 1 s for Fe^(3+) ions. They also have low detection limits of 0.40 and 0.26 µM toward Fe^(3+) and Cr_(2)O_(7)^(2−) ions, respectively, as well as excellent stability. This work paves the way to explore intriguing hierarchical MOF-based luminescent materials for efficient fluorescence sensing applications.
