The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods fo...The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.展开更多
This article presents a micro-structure tensor enhanced elasto-plastic finite element(FE)method to address strength anisotropy in three-dimensional(3D)soil slope stability analysis.The gravity increase method(GIM)is e...This article presents a micro-structure tensor enhanced elasto-plastic finite element(FE)method to address strength anisotropy in three-dimensional(3D)soil slope stability analysis.The gravity increase method(GIM)is employed to analyze the stability of 3D anisotropic soil slopes.The accuracy of the proposed method is first verified against the data in the literature.We then simulate the 3D soil slope with a straight slope surface and the convex and concave slope surfaces with a 90turning corner to study the 3D effect on slope stability and the failure mechanism under anisotropy conditions.Based on our numerical results,the end effect significantly impacts the failure mechanism and safety factor.Anisotropy degree notably affects the safety factor,with higher degrees leading to deeper landslides.For concave slopes,they can be approximated by straight slopes with suitable boundary conditions to assess their stability.Furthermore,a case study of the Saint-Alban test embankment A in Quebec,Canada,is provided to demonstrate the applicability of the proposed FE model.展开更多
Deep learning(DL)has become a crucial technique for predicting the El Niño-Southern Oscillation(ENSO)and evaluating its predictability.While various DL-based models have been developed for ENSO predictions,many f...Deep learning(DL)has become a crucial technique for predicting the El Niño-Southern Oscillation(ENSO)and evaluating its predictability.While various DL-based models have been developed for ENSO predictions,many fail to capture the coherent multivariate evolution within the coupled ocean-atmosphere system of the tropical Pacific.To address this three-dimensional(3D)limitation and represent ENSO-related ocean-atmosphere interactions more accurately,a novel this 3D multivariate prediction model was proposed based on a Transformer architecture,which incorporates a spatiotemporal self-attention mechanism.This model,named 3D-Geoformer,offers several advantages,enabling accurate ENSO predictions up to one and a half years in advance.Furthermore,an integrated gradient method was introduced into the model to identify the sources of predictability for sea surface temperature(SST)variability in the eastern equatorial Pacific.Results reveal that the 3D-Geoformer effectively captures ENSO-related precursors during the evolution of ENSO events,particularly the thermocline feedback processes and ocean temperature anomaly pathways on and off the equator.By extending DL-based ENSO predictions from one-dimensional Niño time series to 3D multivariate fields,the 3D-Geoformer represents a significant advancement in ENSO prediction.This study provides details in the model formulation,analysis procedures,sensitivity experiments,and illustrative examples,offering practical guidance for the application of the model in ENSO research.展开更多
In this paper,a linear optimization method(LOM)for the design of terahertz circuits is presented,aimed at enhancing the simulation efficacy and reducing the time of the circuit design workflow.This method enables the ...In this paper,a linear optimization method(LOM)for the design of terahertz circuits is presented,aimed at enhancing the simulation efficacy and reducing the time of the circuit design workflow.This method enables the rapid determination of optimal embedding impedance for diodes across a specific bandwidth to achieve maximum efficiency through harmonic balance simulations.By optimizing the linear matching circuit with the optimal embedding impedance,the method effectively segregates the simulation of the linear segments from the nonlinear segments in the frequency multiplier circuit,substantially improving the speed of simulations.The design of on-chip linear matching circuits adopts a modular circuit design strategy,incorporating fixed load resistors to simplify the matching challenge.Utilizing this approach,a 340 GHz frequency doubler was developed and measured.The results demonstrate that,across a bandwidth of 330 GHz to 342 GHz,the efficiency of the doubler remains above 10%,with an input power ranging from 98 mW to 141mW and an output power exceeding 13 mW.Notably,at an input power of 141 mW,a peak output power of 21.8 mW was achieved at 334 GHz,corresponding to an efficiency of 15.8%.展开更多
In order to improve the quality of 3D printed raspberry preserves after post-processing,microwave ovens combining infrared and microwave methods were utilized.The effects of infrared heating temperature,infrared heati...In order to improve the quality of 3D printed raspberry preserves after post-processing,microwave ovens combining infrared and microwave methods were utilized.The effects of infrared heating temperature,infrared heating time,microwave power,microwave heating time on the center temperature,moisture content,the chroma(C*),the total color difference(ΔE*),shape fidelity,hardness,and the total anthocyanin content of 3D printed raspberry preserves were analyzed by response surface method(RSM).The results showed that under combining with the two methods,infrared heating improved the fidelity and quality degradation of printed products,while microwave heating enhanced the efficiency of infrared heating.Infrared-microwave combination cooking could maintain relatively stable color appearance and shape of 3D printed raspberry preserves.The AHP–CRITIC hybrid weighting method combined with the response surface test to determine the comprehensive weights of the evaluation indicators optimized the process parameters,and the optimal process parameters were obtained:infrared heating temperature of 190℃,infrared heating time of 10 min and 30 s,microwave power of 300 W,and microwave heating time of 2 min and 6 s.The 3D printed raspberry cooking methods obtained under the optimal conditions seldom had color variation,porous structure,uniform texture,and high shape fidelity,which retained the characteristics of personalized manufacturing by 3D printing.This study could provide a reference for the postprocessing and quality control of 3D cooking methods.展开更多
The modeling of crack growth in three-dimensional(3D)space poses significant challenges in rock mechanics due to the complex numerical computation involved in simulating crack propagation and interaction in rock mater...The modeling of crack growth in three-dimensional(3D)space poses significant challenges in rock mechanics due to the complex numerical computation involved in simulating crack propagation and interaction in rock materials.In this study,we present a novel approach that introduces a 3D numerical manifold method(3D-NMM)with a geometric kernel to enhance computational efficiency.Specifically,the maximum tensile stress criterion is adopted as a crack growth criterion to achieve strong discontinuous crack growth,and a local crack tracking algorithm and an angle correction technique are incorporated to address minor limitations of the algorithm in a 3D model.The implementation of the program is carried out in Python,using object-oriented programming in two independent modules:a calculation module and a crack module.Furthermore,we propose feasible improvements to enhance the performance of the algorithm.Finally,we demonstrate the feasibility and effectiveness of the enhanced algorithm in the 3D-NMM using four numerical examples.This study establishes the potential of the 3DNMM,combined with the local tracking algorithm,for accurately modeling 3D crack propagation in brittle rock materials.展开更多
This paper adopted the hydrothermal method to prepare tungsten oxide(WO_(3))nanorod films and studied the effects of precursor solution concentration(0.02,0.03,0.06 mol/L peroxytungstic acid)and annealing temperature(...This paper adopted the hydrothermal method to prepare tungsten oxide(WO_(3))nanorod films and studied the effects of precursor solution concentration(0.02,0.03,0.06 mol/L peroxytungstic acid)and annealing temperature(200,300,400℃)on their electrochromic properties.The microstructure characterization of WO_(3) films were performed using scanning electron microscope(SEM),X-ray diffraction(XRD),and transmission electron microscope(TEM),and their electrochromic properties were tested by combining an electrochemical workstation with an ultraviolet-visible spectrophotometer.The results showed that the precursor solution concentration directly affected the thickness(290,560,990 nm)and microstructure of WO_(3) films,significantly impacting their electrochromic properties.However,the annealing temperature had a negligible effect.As the precursor solution concentration increased,the optical modulation of WO_(3) films gradually decreased,reaching 51.1%,43.8%,and 35.1%,respectively.The switching time first increased and then stabilized,with coloring times of 7.3,7.7,and 7.7 s,respectively,and bleaching times of 3.8,6.5,and 6.5 s,respectively.The coloration efficiency gradually increased but the increase was relatively small,reaching 41.8,44.4,and 44.8 cm^(2)/C,respectively.Moreover,the cycling stability of WO_(3) films was poor,with the ratios of the final value of optical modulation to the initial value 0.33,0.26,and 0.34,respectively.Additionally,there were bigger differences in the bleached state transmittance,while the colored state transmittance showed smaller variations.However,the former has better cycling stability than the latter.In summary,to obtain better electrochromic properties,the thickness of WO_(3) films should not exceed 290 nm.展开更多
Norfloxacin is widely used owing to its strong bactericidal effect on Gram-negative bacteria.However,the residual norfloxacin in the environment can be biomagnified via food chain andmay damage the human liver and del...Norfloxacin is widely used owing to its strong bactericidal effect on Gram-negative bacteria.However,the residual norfloxacin in the environment can be biomagnified via food chain andmay damage the human liver and delay the bone development ofminors.Present work described a reliable and sensitive smartphone colorimetric sensing system based on cobaltdoped Fe_(3)O_(4) magnetic nanoparticles(Co-Fe_(3)O_(4) MNPs)for the visual detection of norfloxacin.Compared with Fe_(3)O_(4),Co-Fe_(3)O_(4) MNPs earned more remarkably peroxidase-like activity and TMB(colorless)was rapidly oxidized to oxTMB(blue)with the presence of H_(2)O_(2).Interestingly,the addition of low concentration of norfloxacin can accelerate the color reaction process of TMB,and blue deepening of the solution can be observed with the naked eye.However,after adding high concentration of norfloxacin,the activity of nanozymewas inhibited,resulting in the gradual fading of the solution.Based on this principle,a colorimetric sensor integrated with smartphone RGB mode was established.The visual sensor exhibited good linearity for norfloxacin monitoring in the range of 0.13-2.51μmol/L and 17.5-100μmol/L.The limit of visual detectionwas 0.08μmol/L.In the actualwater sample analysis,the spiked recoveries of norfloxacin were over the range of 95.7%-104.7%.These results demonstrated that the visual sensor was a convenient and fast method for the efficient and accurate detection of norfloxacin in water,which may have broad application prospect.展开更多
This study systematically conducted preparation optimization and performance investigations on Co-modified Ce/TiO_(2) catalysts,with a focus on examining how preparation methods and Co loading regulate the catalyst’s...This study systematically conducted preparation optimization and performance investigations on Co-modified Ce/TiO_(2) catalysts,with a focus on examining how preparation methods and Co loading regulate the catalyst’s low-temperature denitrification activity.After identifying optimal preparation parameters via condition screening,multiple characterization techniques-including BET,XRD,XPS,H_(2)-TPR and in situ DRIFTS-were employed to deeply analyze the catalyst’s physicochemical properties and reaction mechanism.Results demonstrated that compared to the impregnation and co-precipitation methods,the Ce-Co_(0.025)/TiO_(2)-SG catalyst(prepared by the sol-gel method with a Co/Ti mass ratio of 0.025)exhibited significantly superior denitrification activity:NO conversion remained stably above 95%in the 225−350℃ temperature range,and it displayed high N_(2) selectivity.Characterization analysis revealed that abundant surface oxygen vacancies,a high proportion of Ce^(3+) species,and prominent acidic sites collectively contributed to enhancing its low-temperature denitrification performance.This work provides reference value for the development of highly efficient low-temperature denitrification catalysts.展开更多
This study presents and verifies a hybrid methodology for reliable determination of parameters in structural rheological models(Zener,Burgers,and Maxwell)describing the viscoelastic behavior of polyurethane specimens ...This study presents and verifies a hybrid methodology for reliable determination of parameters in structural rheological models(Zener,Burgers,and Maxwell)describing the viscoelastic behavior of polyurethane specimens manufactured using extrusion-based 3D printing.Through comprehensive testing,including cyclic compression at strain rates ranging from 0.12 to 120 mm/min(0%-15%strain)and creep/relaxation experiments(10%-30%strain),the lumped parameters were independently determined using both analytical and numerical solutions of the models’differential equations,followed by cross-verification in additional experiments.Numerical solutions for creep and relaxation problems were obtained using finite element analysis,with the three-parameter Mooney-Rivlin model and Prony series employed to simulate elastic and viscous stress components,respectively.Energy dissipation per cycle was quantified during cyclic compression tests.The results demonstrate that all three models adequately describe material behavior within the 0%-15%strain range across various strain rates.Comparative analysis revealed the Burgers model’s superior performance in characterizing creep and stress relaxation at low strain levels.While Zener and Burgers model parameters from uniaxial compression showed limited applicability for energy dissipation calculations,the generalized Maxwell model effectively captured viscoelastic properties across different strain rates.Notably,parameters derived from creep tests provided a more universal assessment of dissipative properties due to optimization based on characteristic curve regions.Both parameter sets described polyurethane’s elastic-hysteretic behavior with approximately 20%error,proving significantly more accurate than the linear strain-time dependence hypothesis.Finite element analysis(FEA)complemented numerical modeling by demonstrating that while the generalized Maxwell model effectively describes initial rapid stress-strain changes,FEA provides superior characterization of steady-state processes.This computational approach yields more physically representative results compared to simplified analytical solutions,despite certain limitations in transient analysis.展开更多
A facile one-step hydrothermal method has been reported to synthesize theα-Fe_(2)O_(3)nanosheet arrays with the preferred orientation along the[104]direction on the ITO substrate.Theα-Fe_(2)O_(3)nanosheet arrays-bas...A facile one-step hydrothermal method has been reported to synthesize theα-Fe_(2)O_(3)nanosheet arrays with the preferred orientation along the[104]direction on the ITO substrate.Theα-Fe_(2)O_(3)nanosheet arrays-based W/α-Fe_(2)O_(3)/ITO memristor has been achieved by depositing the circular W top electrodes on theα-Fe_(2)O_(3)nanosheet arrays.The as-prepared W/α-Fe_(2)O_(3)/ITO memristor shows a reliable nonvolatile bipolar resistive switching behavior with the high resistance ratio of about 103at the reading voltage of 0.1 V,good resistance retention over 10~3s,ultralow set voltage of-0.6 V and reset voltage of 0.7 V,and good durability.In addition,the tunneling conduction mechanism modified by the oxygen vacancies has been proposed and suggested to be responsible for the nonvolatile resistive switching behavior of the as-prepared W/α-Fe_(2)O_(3)/ITO memristor.This work demonstrates that the as-preparedα-Fe_(2)O_(3)nanosheet arrays-based W/α-Fe_(2)O_(3)/ITO memristor would be a promising candidate for further ultralow power nonvolatile memory applications.展开更多
基金supported by National Natural Science Foundation of China(No.52176122).
文摘The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.51890912,51979025 and 52011530189).
文摘This article presents a micro-structure tensor enhanced elasto-plastic finite element(FE)method to address strength anisotropy in three-dimensional(3D)soil slope stability analysis.The gravity increase method(GIM)is employed to analyze the stability of 3D anisotropic soil slopes.The accuracy of the proposed method is first verified against the data in the literature.We then simulate the 3D soil slope with a straight slope surface and the convex and concave slope surfaces with a 90turning corner to study the 3D effect on slope stability and the failure mechanism under anisotropy conditions.Based on our numerical results,the end effect significantly impacts the failure mechanism and safety factor.Anisotropy degree notably affects the safety factor,with higher degrees leading to deeper landslides.For concave slopes,they can be approximated by straight slopes with suitable boundary conditions to assess their stability.Furthermore,a case study of the Saint-Alban test embankment A in Quebec,Canada,is provided to demonstrate the applicability of the proposed FE model.
基金Supported by the Laoshan Laboratory(No.LSKJ202202402)the National Natural Science Foundation of China(No.42030410)+2 种基金the Startup Foundation for Introducing Talent of Nanjing University of Information Science&Technology,and Jiangsu Innovation Research Group(No.JSSCTD 202346)supported by the China National Postdoctoral Program for Innovative Talents(No.BX20240169)the China Postdoctoral Science Foundation(No.2141062400101)。
文摘Deep learning(DL)has become a crucial technique for predicting the El Niño-Southern Oscillation(ENSO)and evaluating its predictability.While various DL-based models have been developed for ENSO predictions,many fail to capture the coherent multivariate evolution within the coupled ocean-atmosphere system of the tropical Pacific.To address this three-dimensional(3D)limitation and represent ENSO-related ocean-atmosphere interactions more accurately,a novel this 3D multivariate prediction model was proposed based on a Transformer architecture,which incorporates a spatiotemporal self-attention mechanism.This model,named 3D-Geoformer,offers several advantages,enabling accurate ENSO predictions up to one and a half years in advance.Furthermore,an integrated gradient method was introduced into the model to identify the sources of predictability for sea surface temperature(SST)variability in the eastern equatorial Pacific.Results reveal that the 3D-Geoformer effectively captures ENSO-related precursors during the evolution of ENSO events,particularly the thermocline feedback processes and ocean temperature anomaly pathways on and off the equator.By extending DL-based ENSO predictions from one-dimensional Niño time series to 3D multivariate fields,the 3D-Geoformer represents a significant advancement in ENSO prediction.This study provides details in the model formulation,analysis procedures,sensitivity experiments,and illustrative examples,offering practical guidance for the application of the model in ENSO research.
基金Supported by the Beijing Municipal Science&Technology Commission(Z211100004421012),the Key Reaserch and Development Pro⁃gram of China(2022YFF0605902)。
文摘In this paper,a linear optimization method(LOM)for the design of terahertz circuits is presented,aimed at enhancing the simulation efficacy and reducing the time of the circuit design workflow.This method enables the rapid determination of optimal embedding impedance for diodes across a specific bandwidth to achieve maximum efficiency through harmonic balance simulations.By optimizing the linear matching circuit with the optimal embedding impedance,the method effectively segregates the simulation of the linear segments from the nonlinear segments in the frequency multiplier circuit,substantially improving the speed of simulations.The design of on-chip linear matching circuits adopts a modular circuit design strategy,incorporating fixed load resistors to simplify the matching challenge.Utilizing this approach,a 340 GHz frequency doubler was developed and measured.The results demonstrate that,across a bandwidth of 330 GHz to 342 GHz,the efficiency of the doubler remains above 10%,with an input power ranging from 98 mW to 141mW and an output power exceeding 13 mW.Notably,at an input power of 141 mW,a peak output power of 21.8 mW was achieved at 334 GHz,corresponding to an efficiency of 15.8%.
基金Supported by the National Natural Science Foundation of China(32072352)。
文摘In order to improve the quality of 3D printed raspberry preserves after post-processing,microwave ovens combining infrared and microwave methods were utilized.The effects of infrared heating temperature,infrared heating time,microwave power,microwave heating time on the center temperature,moisture content,the chroma(C*),the total color difference(ΔE*),shape fidelity,hardness,and the total anthocyanin content of 3D printed raspberry preserves were analyzed by response surface method(RSM).The results showed that under combining with the two methods,infrared heating improved the fidelity and quality degradation of printed products,while microwave heating enhanced the efficiency of infrared heating.Infrared-microwave combination cooking could maintain relatively stable color appearance and shape of 3D printed raspberry preserves.The AHP–CRITIC hybrid weighting method combined with the response surface test to determine the comprehensive weights of the evaluation indicators optimized the process parameters,and the optimal process parameters were obtained:infrared heating temperature of 190℃,infrared heating time of 10 min and 30 s,microwave power of 300 W,and microwave heating time of 2 min and 6 s.The 3D printed raspberry cooking methods obtained under the optimal conditions seldom had color variation,porous structure,uniform texture,and high shape fidelity,which retained the characteristics of personalized manufacturing by 3D printing.This study could provide a reference for the postprocessing and quality control of 3D cooking methods.
基金supported by the National Natural Science Foundation of China(Grant Nos.42172312 and 52211540395)support from the Institut Universitaire de France(IUF).
文摘The modeling of crack growth in three-dimensional(3D)space poses significant challenges in rock mechanics due to the complex numerical computation involved in simulating crack propagation and interaction in rock materials.In this study,we present a novel approach that introduces a 3D numerical manifold method(3D-NMM)with a geometric kernel to enhance computational efficiency.Specifically,the maximum tensile stress criterion is adopted as a crack growth criterion to achieve strong discontinuous crack growth,and a local crack tracking algorithm and an angle correction technique are incorporated to address minor limitations of the algorithm in a 3D model.The implementation of the program is carried out in Python,using object-oriented programming in two independent modules:a calculation module and a crack module.Furthermore,we propose feasible improvements to enhance the performance of the algorithm.Finally,we demonstrate the feasibility and effectiveness of the enhanced algorithm in the 3D-NMM using four numerical examples.This study establishes the potential of the 3DNMM,combined with the local tracking algorithm,for accurately modeling 3D crack propagation in brittle rock materials.
基金the National Natural Science Foundation of China(No.52272009)the Henan Provincial Science and Technology Research Project(No.242102230151)+1 种基金the Henan Provincial University Science and Technology Innovation Team(No.25IRTSTHN009)the Key Scientific Research Projects of Colleges and Universities in Henan Province(Nos.24B560021,25B560020,25B560023)。
文摘This paper adopted the hydrothermal method to prepare tungsten oxide(WO_(3))nanorod films and studied the effects of precursor solution concentration(0.02,0.03,0.06 mol/L peroxytungstic acid)and annealing temperature(200,300,400℃)on their electrochromic properties.The microstructure characterization of WO_(3) films were performed using scanning electron microscope(SEM),X-ray diffraction(XRD),and transmission electron microscope(TEM),and their electrochromic properties were tested by combining an electrochemical workstation with an ultraviolet-visible spectrophotometer.The results showed that the precursor solution concentration directly affected the thickness(290,560,990 nm)and microstructure of WO_(3) films,significantly impacting their electrochromic properties.However,the annealing temperature had a negligible effect.As the precursor solution concentration increased,the optical modulation of WO_(3) films gradually decreased,reaching 51.1%,43.8%,and 35.1%,respectively.The switching time first increased and then stabilized,with coloring times of 7.3,7.7,and 7.7 s,respectively,and bleaching times of 3.8,6.5,and 6.5 s,respectively.The coloration efficiency gradually increased but the increase was relatively small,reaching 41.8,44.4,and 44.8 cm^(2)/C,respectively.Moreover,the cycling stability of WO_(3) films was poor,with the ratios of the final value of optical modulation to the initial value 0.33,0.26,and 0.34,respectively.Additionally,there were bigger differences in the bleached state transmittance,while the colored state transmittance showed smaller variations.However,the former has better cycling stability than the latter.In summary,to obtain better electrochromic properties,the thickness of WO_(3) films should not exceed 290 nm.
基金supported by the National Natural Science Foundation of China (No.21976211).
文摘Norfloxacin is widely used owing to its strong bactericidal effect on Gram-negative bacteria.However,the residual norfloxacin in the environment can be biomagnified via food chain andmay damage the human liver and delay the bone development ofminors.Present work described a reliable and sensitive smartphone colorimetric sensing system based on cobaltdoped Fe_(3)O_(4) magnetic nanoparticles(Co-Fe_(3)O_(4) MNPs)for the visual detection of norfloxacin.Compared with Fe_(3)O_(4),Co-Fe_(3)O_(4) MNPs earned more remarkably peroxidase-like activity and TMB(colorless)was rapidly oxidized to oxTMB(blue)with the presence of H_(2)O_(2).Interestingly,the addition of low concentration of norfloxacin can accelerate the color reaction process of TMB,and blue deepening of the solution can be observed with the naked eye.However,after adding high concentration of norfloxacin,the activity of nanozymewas inhibited,resulting in the gradual fading of the solution.Based on this principle,a colorimetric sensor integrated with smartphone RGB mode was established.The visual sensor exhibited good linearity for norfloxacin monitoring in the range of 0.13-2.51μmol/L and 17.5-100μmol/L.The limit of visual detectionwas 0.08μmol/L.In the actualwater sample analysis,the spiked recoveries of norfloxacin were over the range of 95.7%-104.7%.These results demonstrated that the visual sensor was a convenient and fast method for the efficient and accurate detection of norfloxacin in water,which may have broad application prospect.
基金Supported by the National Key Research and Development Program of China (2023YFB4102903)。
文摘This study systematically conducted preparation optimization and performance investigations on Co-modified Ce/TiO_(2) catalysts,with a focus on examining how preparation methods and Co loading regulate the catalyst’s low-temperature denitrification activity.After identifying optimal preparation parameters via condition screening,multiple characterization techniques-including BET,XRD,XPS,H_(2)-TPR and in situ DRIFTS-were employed to deeply analyze the catalyst’s physicochemical properties and reaction mechanism.Results demonstrated that compared to the impregnation and co-precipitation methods,the Ce-Co_(0.025)/TiO_(2)-SG catalyst(prepared by the sol-gel method with a Co/Ti mass ratio of 0.025)exhibited significantly superior denitrification activity:NO conversion remained stably above 95%in the 225−350℃ temperature range,and it displayed high N_(2) selectivity.Characterization analysis revealed that abundant surface oxygen vacancies,a high proportion of Ce^(3+) species,and prominent acidic sites collectively contributed to enhancing its low-temperature denitrification performance.This work provides reference value for the development of highly efficient low-temperature denitrification catalysts.
文摘This study presents and verifies a hybrid methodology for reliable determination of parameters in structural rheological models(Zener,Burgers,and Maxwell)describing the viscoelastic behavior of polyurethane specimens manufactured using extrusion-based 3D printing.Through comprehensive testing,including cyclic compression at strain rates ranging from 0.12 to 120 mm/min(0%-15%strain)and creep/relaxation experiments(10%-30%strain),the lumped parameters were independently determined using both analytical and numerical solutions of the models’differential equations,followed by cross-verification in additional experiments.Numerical solutions for creep and relaxation problems were obtained using finite element analysis,with the three-parameter Mooney-Rivlin model and Prony series employed to simulate elastic and viscous stress components,respectively.Energy dissipation per cycle was quantified during cyclic compression tests.The results demonstrate that all three models adequately describe material behavior within the 0%-15%strain range across various strain rates.Comparative analysis revealed the Burgers model’s superior performance in characterizing creep and stress relaxation at low strain levels.While Zener and Burgers model parameters from uniaxial compression showed limited applicability for energy dissipation calculations,the generalized Maxwell model effectively captured viscoelastic properties across different strain rates.Notably,parameters derived from creep tests provided a more universal assessment of dissipative properties due to optimization based on characteristic curve regions.Both parameter sets described polyurethane’s elastic-hysteretic behavior with approximately 20%error,proving significantly more accurate than the linear strain-time dependence hypothesis.Finite element analysis(FEA)complemented numerical modeling by demonstrating that while the generalized Maxwell model effectively describes initial rapid stress-strain changes,FEA provides superior characterization of steady-state processes.This computational approach yields more physically representative results compared to simplified analytical solutions,despite certain limitations in transient analysis.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62341305 and 22269002)the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant No.2024GXNSFFA010007)+2 种基金the Science and Technology Project of Guangxi Zhuang Autonomous Region,China(Grant No.AD19110038)the Key Laboratory of AI and Information Processing,Education Department of Guangxi Zhuang Autonomous Region(Grant No.2024GXZDSY015)the Innovation Project of Guangxi University of Science and Technology Graduate Education(Grant No.GKYC202408)。
文摘A facile one-step hydrothermal method has been reported to synthesize theα-Fe_(2)O_(3)nanosheet arrays with the preferred orientation along the[104]direction on the ITO substrate.Theα-Fe_(2)O_(3)nanosheet arrays-based W/α-Fe_(2)O_(3)/ITO memristor has been achieved by depositing the circular W top electrodes on theα-Fe_(2)O_(3)nanosheet arrays.The as-prepared W/α-Fe_(2)O_(3)/ITO memristor shows a reliable nonvolatile bipolar resistive switching behavior with the high resistance ratio of about 103at the reading voltage of 0.1 V,good resistance retention over 10~3s,ultralow set voltage of-0.6 V and reset voltage of 0.7 V,and good durability.In addition,the tunneling conduction mechanism modified by the oxygen vacancies has been proposed and suggested to be responsible for the nonvolatile resistive switching behavior of the as-prepared W/α-Fe_(2)O_(3)/ITO memristor.This work demonstrates that the as-preparedα-Fe_(2)O_(3)nanosheet arrays-based W/α-Fe_(2)O_(3)/ITO memristor would be a promising candidate for further ultralow power nonvolatile memory applications.
