Conducting polymers(CPs),including poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS),are promising coating materials for neural electrodes.However,the weak adhesion of CP coatings to substrates such a...Conducting polymers(CPs),including poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS),are promising coating materials for neural electrodes.However,the weak adhesion of CP coatings to substrates such as platinum-iridium is a significant challenge that limits their practical application.To address this issue,we used femtosecond laser-prepared hierarchical structures on platinum-iridium(Pt-Ir)substrates to enhance the adhesion of PEDOT:PSS coatings.Next,we used cyclic voltammetry(CV)stress and accelerated aging tests to evaluate the stability of both drop cast and electrodeposited PEDOT:PSS coatings on Pt-Ir substrates,both with and without hierarchical structures.Our results showed that after 2000 CV cycles or five weeks of aging at 60℃,the morphology and electrochemical properties of the coatings on the Pt-Ir substrates with hierarchical structures remained relatively stable.In contrast,we found that smooth Pt-Ir substrate surfaces caused delamination of the PEDOT:PSS coating and exhibited both decreased charge storage capacity and increased impedance.Overall,enhancing the stability of PEDOT:PSS coatings used on common platinum-iridium neural electrodes offers great potential for improving their electrochemical performance and developing new functionalities.展开更多
Soil contamination in agroecosystems remains a global environmental problem. Biochar has been suggested as an organic amendment to alleviate soil pollution, sequester carbon(C), and improve soil fertility. However, in...Soil contamination in agroecosystems remains a global environmental problem. Biochar has been suggested as an organic amendment to alleviate soil pollution, sequester carbon(C), and improve soil fertility. However, information on how bacterial and fungal communities in acidic bulk and rhizosphere soils respond to swine manure and its biochar is still lacking. In this study, biochar and swine manure were applied at two rates of 1.5 and 3 t ha-1in a rice-wheat rotation field to assess how soil characteristics, especially p H and chemical element availability, correlate to compositional variations of bacteria and fungi in bulk and rhizosphere soils. Our results showed that high rates of biochar and manure promoted the bacterial richness in bulk and rhizosphere soils by increasing soil pH and reducing soil arsenic(As) and copper(Cu) availability. Compared with soil As and Cu availability, soil p H had opposite effects on beta diversity of both the bacterial and fungal communities. Specifically, biochar and swine manure applications stimulated the bacterial classes Gemmatimonadetes, Deltaproteobacteria, and Gammaproteobacteria by increasing soil pH and decreasing soil available chemical elements. Opposite trends were observed in fungal communities responding to biochar and manure. For example, biochar restrained the fungal class Eurotiomycetes by decreasing soil As and Cu availability, but manure inhibited Leotiomycetes mainly because of an increase in soil pH and a decrease in soil dissolved organic C. These suggest that both bacterial and fungal communities respond significantly to biochar and manure amendments in both bulk and rhizosphere soils, possibly because of their sensitive adaptation to variations in soil environmental factors, such as pH level and chemical element availability.展开更多
The interfacial performance of implanted neural electrodes is crucial for stimulation safety and the recording quality of neuronal activity.This paper proposes a novel surface architecture and optimization strategy fo...The interfacial performance of implanted neural electrodes is crucial for stimulation safety and the recording quality of neuronal activity.This paper proposes a novel surface architecture and optimization strategy for the platinum–iridium(Pt–Ir)electrode to optimize electrochemical performance and wettability.A series of surface micro/nano structures were fabricated on Pt–Ir electrodes with different combinations of four adjustable laser-processing parameters.Subsequently,the electrodes were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,cyclic voltammetry,electrochemical impedance spectroscopy,and wetting behavior.The results show that electrode performance strongly depends on the surface morphology.Increasing scanning overlap along with moderate pulse energy and the right number of pulses leads to enriched surface micro/nano structures and improved electrode performance.It raises the maximum charge storage capacity to 128.2 mC/cm^(2) and the interface capacitance of electrodes to 3.0×10^(4)μF/cm^(2) for the geometric area,compared with 4.6 mC/cm^(2) and 443.1μF/cm2,respectively,for the smooth Pt–Ir electrode.The corresponding optimal results for the optically measured area are 111.8 mC/cm^(2) and 2.6×10^(4)μF/cm^(2),which indicate the contribution of fner structures to the ablation profle.The hierarchical structures formed by the femtosecond laser dramatically enhanced the wettability of the electrode interface,giving it superwicking properties.A wicking speed of approximately 80 mm/s was reached.Our optimization strategy,leading to superior performance of the superwicking Pt–Ir interface,is promising for use in new neural electrodes.展开更多
Low-noise microwave oscillators are cornerstones for wireless communication,radar and clocks.The employment and optimization of optical frequency combs have enabled photonic microwave synthesizers with unrivalled nois...Low-noise microwave oscillators are cornerstones for wireless communication,radar and clocks.The employment and optimization of optical frequency combs have enabled photonic microwave synthesizers with unrivalled noise performance and bandwidth breaking the bottleneck of those electronic counterparts.Emerging interest is to use chip-based Kerr frequency combs,namely microcombs.Today microcombs built on photonic integrated circuits feature small size,weight and power consumption,and can be manufactured to oscillate at any frequency ranging from microwave to millimeter-wave band.A monolithic microcomb-based microwave oscillator requires integration of lasers,photodetectors and nonlinear microresonators on a common substrate,which however has still remained elusive.Here,we demonstrate the first,fully hybrid-integrated,microcomb-based microwave oscillator at 10.7 GHz.The chip device,powered by a customized microelectronic circuit,leverages hybrid integration of a high-power DFB laser,a silicon nitride microresonator of a quality factor exceeding 25× 10^(6),and a high-speed photodetector chip of 110 GHz bandwidth(3 dB)and 0.3 A/W responsivity.Each component represents the state of the art of its own class,yet also allows large-volume manufacturing with low cost using established CMOS and Ⅲ-Ⅴ foundries.The hybrid chip outputs an ultralow-noise laser of 6.9 Hz intrinsic linewidth,a coherent microcomb of 10.7 GHz repetition rate,and a 10.7 GHz microwave carrier of 6.3 mHz linewidth-all the three functions in one entity occupying a footprint of only 76 mm^(2).Furthermore,harnessing the nonlinear laser-microresonator interaction,we observe and maneuver a unique noise-quenching dynamics within discrete microcomb states,which offers immunity to laser current noise,suppression of microwave phase noise by more than 20 dB,and improvement of microwave power by up to 10 dB.The ultimate microwave phase noise reaches-75/-105/-130dBc/Hz at 1/10/100 kHz Fourier offset frequency.Our results can reinvigorate our information society for communication,sensing,imaging,timing and precision measurement.展开更多
Synthetic aperture radar(SAR)records important information about the interaction of electromagnetic waves with the Earth’s surface.However,long-term and high-resolution backscatter coefficient data are still lacking ...Synthetic aperture radar(SAR)records important information about the interaction of electromagnetic waves with the Earth’s surface.However,long-term and high-resolution backscatter coefficient data are still lacking in many urban studies(e.g.,building height estimation).Here,we proposed a framework to reconstruct the 1-km backscatter coefficient in 1990-2022 utilizing the Sentinel-1 Ground Range Detected data and Landsat time series data in the Jing-Jin-Ji(JJJ)region.First,we developed a regression model to convert the optical signals from Landsat into backscatter coefficients as the Sentinel-1 data,using observations from 2015 to 2022.Then,we reconstructed backscatter coefficients from 1990 to 2022 using the long-term Landsat data.Using the reconstructed backscatter coefficients,we analyzed the dynamic patterns of building height over the past decades.The proposed approach performs well on estimating the backscatter coefficient and its spatial pattern,with the annual mean absolute error,root mean square error,and R^(2) of 1.10 dB,1.50 dB,and 0.64,respectively.The temporal trends revealed from the reconstructed backscatter data are reliable compared with satellite observations at a relatively coarse resolution,with Pearson’s coefficients above 0.92 in 6 sample cities.The derived building height from the reconstructed SAR data indicates that the JJJ region experienced a noticeable upward expansion in 1990-2022,e.g.,Beijing has the fastest growth rate of 0.420 km^(3)/decade regarding the total building volumes.The proposed framework of reconstructing SAR data from optical satellite images provides a new insight to complement the long-term and high-resolution backscatter from local to global scales.展开更多
Neural electrode interfaces are essential to the stimulation safety and recording quality of various bioelectronic therapies.The recently proposed hierarchical platinum-iridium(Pt-Ir)electrodes produced by femtosecond...Neural electrode interfaces are essential to the stimulation safety and recording quality of various bioelectronic therapies.The recently proposed hierarchical platinum-iridium(Pt-Ir)electrodes produced by femtosecond lasers have exhibited superior electrochemical performance in vitro,but their in vivo performance is still unclear.In this study,we explored the electrochemical performance,biological response,and tissue adhesion of hierarchical Pt-Ir electrodes by implantation in adult rat brains for 1,8,and 16 weeks.Regular smooth Pt-Ir electrodes were used as a control.The results showed that the electrochemical performance of both electrodes decreased and leveled off during implantation.However,after 16 weeks,the charge storage capacity of hierarchical electrodes stabilized at~16.8 mC/cm^(2),which was 15 times that of the smooth control electrodes(1.1 mC/cm^(2)).Moreover,the highly structured electrodes had lower impedance amplitude and cutoff frequency values.The similar histological response to smooth electrodes indicated good biocompatibility of the hierarchically structured Pt-Ir electrodes.Given their superior in vivo performance,the femtosecond laser-treated Pt-Ir electrode showed great potential for neuromodulation applications.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFC2400201)the National Natural Science Foundation of China(No.81830033)+1 种基金the Natural Science Foundation of Fujian Province,China(No.2023J05097)the Young and Middle-aged Teacher Education Research Project of the Education Department of Fujian Province,China(No.JAT220004)。
文摘Conducting polymers(CPs),including poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS),are promising coating materials for neural electrodes.However,the weak adhesion of CP coatings to substrates such as platinum-iridium is a significant challenge that limits their practical application.To address this issue,we used femtosecond laser-prepared hierarchical structures on platinum-iridium(Pt-Ir)substrates to enhance the adhesion of PEDOT:PSS coatings.Next,we used cyclic voltammetry(CV)stress and accelerated aging tests to evaluate the stability of both drop cast and electrodeposited PEDOT:PSS coatings on Pt-Ir substrates,both with and without hierarchical structures.Our results showed that after 2000 CV cycles or five weeks of aging at 60℃,the morphology and electrochemical properties of the coatings on the Pt-Ir substrates with hierarchical structures remained relatively stable.In contrast,we found that smooth Pt-Ir substrate surfaces caused delamination of the PEDOT:PSS coating and exhibited both decreased charge storage capacity and increased impedance.Overall,enhancing the stability of PEDOT:PSS coatings used on common platinum-iridium neural electrodes offers great potential for improving their electrochemical performance and developing new functionalities.
基金financially funded by the National Natural Science Foundation of China (Nos. 42277282 and41601334)the Public Welfare Technology Application Research Project of Zhejiang Province,China (NoLGF21D010002)+4 种基金the Key Research and Development Program of Zhejiang Province,China (No. 2020C01017)the State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products,Ningbo University,China (No. KF20190106)the Basic and Applied Basic Research Foundation of Guangdong Province,China (No. 2022A1515010861)the Shenzhen Science and Technology Program (No. JCYJ20220530150201003)the Young Teachers Team Project of Fundamental Research Funds for the Central Universities,Sun Yat-sen University,China (No. 22qntd2702)。
文摘Soil contamination in agroecosystems remains a global environmental problem. Biochar has been suggested as an organic amendment to alleviate soil pollution, sequester carbon(C), and improve soil fertility. However, information on how bacterial and fungal communities in acidic bulk and rhizosphere soils respond to swine manure and its biochar is still lacking. In this study, biochar and swine manure were applied at two rates of 1.5 and 3 t ha-1in a rice-wheat rotation field to assess how soil characteristics, especially p H and chemical element availability, correlate to compositional variations of bacteria and fungi in bulk and rhizosphere soils. Our results showed that high rates of biochar and manure promoted the bacterial richness in bulk and rhizosphere soils by increasing soil pH and reducing soil arsenic(As) and copper(Cu) availability. Compared with soil As and Cu availability, soil p H had opposite effects on beta diversity of both the bacterial and fungal communities. Specifically, biochar and swine manure applications stimulated the bacterial classes Gemmatimonadetes, Deltaproteobacteria, and Gammaproteobacteria by increasing soil pH and decreasing soil available chemical elements. Opposite trends were observed in fungal communities responding to biochar and manure. For example, biochar restrained the fungal class Eurotiomycetes by decreasing soil As and Cu availability, but manure inhibited Leotiomycetes mainly because of an increase in soil pH and a decrease in soil dissolved organic C. These suggest that both bacterial and fungal communities respond significantly to biochar and manure amendments in both bulk and rhizosphere soils, possibly because of their sensitive adaptation to variations in soil environmental factors, such as pH level and chemical element availability.
基金the National Natural Science Foundation of China(Nos.51777115 and 81527901)the National Key Research and Development Program of China(Nos.2016YFC0105502 and 2016YFC0105900)Tsinghua University Intiative Scientifc Research Program and Major Achievements Transformation Project of Beijing’s College.
文摘The interfacial performance of implanted neural electrodes is crucial for stimulation safety and the recording quality of neuronal activity.This paper proposes a novel surface architecture and optimization strategy for the platinum–iridium(Pt–Ir)electrode to optimize electrochemical performance and wettability.A series of surface micro/nano structures were fabricated on Pt–Ir electrodes with different combinations of four adjustable laser-processing parameters.Subsequently,the electrodes were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,cyclic voltammetry,electrochemical impedance spectroscopy,and wetting behavior.The results show that electrode performance strongly depends on the surface morphology.Increasing scanning overlap along with moderate pulse energy and the right number of pulses leads to enriched surface micro/nano structures and improved electrode performance.It raises the maximum charge storage capacity to 128.2 mC/cm^(2) and the interface capacitance of electrodes to 3.0×10^(4)μF/cm^(2) for the geometric area,compared with 4.6 mC/cm^(2) and 443.1μF/cm2,respectively,for the smooth Pt–Ir electrode.The corresponding optimal results for the optically measured area are 111.8 mC/cm^(2) and 2.6×10^(4)μF/cm^(2),which indicate the contribution of fner structures to the ablation profle.The hierarchical structures formed by the femtosecond laser dramatically enhanced the wettability of the electrode interface,giving it superwicking properties.A wicking speed of approximately 80 mm/s was reached.Our optimization strategy,leading to superior performance of the superwicking Pt–Ir interface,is promising for use in new neural electrodes.
基金support from the National Natural Science Foundation of China(Grant No.12261131503,No.12404436,No.61975121,and No.12404417)Innovation Program for Quantum Science and Technology(2023ZD0301500)+2 种基金National Key R&D Program of China(Grant No.2024YFA1409300),Shenzhen-Hong Kong Cooperation Zone for Technology and Innovation(HZQB-KCZYB2020050)Shenzhen Science and Technology Program(Grant No.RCJC20231211090042078)Guangdong-Hong Kong Technology Cooperation Funding Scheme(Grant No.2024A0505040008).
文摘Low-noise microwave oscillators are cornerstones for wireless communication,radar and clocks.The employment and optimization of optical frequency combs have enabled photonic microwave synthesizers with unrivalled noise performance and bandwidth breaking the bottleneck of those electronic counterparts.Emerging interest is to use chip-based Kerr frequency combs,namely microcombs.Today microcombs built on photonic integrated circuits feature small size,weight and power consumption,and can be manufactured to oscillate at any frequency ranging from microwave to millimeter-wave band.A monolithic microcomb-based microwave oscillator requires integration of lasers,photodetectors and nonlinear microresonators on a common substrate,which however has still remained elusive.Here,we demonstrate the first,fully hybrid-integrated,microcomb-based microwave oscillator at 10.7 GHz.The chip device,powered by a customized microelectronic circuit,leverages hybrid integration of a high-power DFB laser,a silicon nitride microresonator of a quality factor exceeding 25× 10^(6),and a high-speed photodetector chip of 110 GHz bandwidth(3 dB)and 0.3 A/W responsivity.Each component represents the state of the art of its own class,yet also allows large-volume manufacturing with low cost using established CMOS and Ⅲ-Ⅴ foundries.The hybrid chip outputs an ultralow-noise laser of 6.9 Hz intrinsic linewidth,a coherent microcomb of 10.7 GHz repetition rate,and a 10.7 GHz microwave carrier of 6.3 mHz linewidth-all the three functions in one entity occupying a footprint of only 76 mm^(2).Furthermore,harnessing the nonlinear laser-microresonator interaction,we observe and maneuver a unique noise-quenching dynamics within discrete microcomb states,which offers immunity to laser current noise,suppression of microwave phase noise by more than 20 dB,and improvement of microwave power by up to 10 dB.The ultimate microwave phase noise reaches-75/-105/-130dBc/Hz at 1/10/100 kHz Fourier offset frequency.Our results can reinvigorate our information society for communication,sensing,imaging,timing and precision measurement.
基金supported by the National Natural Science Foundation of China(42101418 and 42371413)the National Natural Science Foundation of China/RGC Joint Research Scheme(42361164614 and N_HKU722/23)+1 种基金the NSFC Excellent Young Scientists Fund(Overseas)the Chinese University Scientific Fund.
文摘Synthetic aperture radar(SAR)records important information about the interaction of electromagnetic waves with the Earth’s surface.However,long-term and high-resolution backscatter coefficient data are still lacking in many urban studies(e.g.,building height estimation).Here,we proposed a framework to reconstruct the 1-km backscatter coefficient in 1990-2022 utilizing the Sentinel-1 Ground Range Detected data and Landsat time series data in the Jing-Jin-Ji(JJJ)region.First,we developed a regression model to convert the optical signals from Landsat into backscatter coefficients as the Sentinel-1 data,using observations from 2015 to 2022.Then,we reconstructed backscatter coefficients from 1990 to 2022 using the long-term Landsat data.Using the reconstructed backscatter coefficients,we analyzed the dynamic patterns of building height over the past decades.The proposed approach performs well on estimating the backscatter coefficient and its spatial pattern,with the annual mean absolute error,root mean square error,and R^(2) of 1.10 dB,1.50 dB,and 0.64,respectively.The temporal trends revealed from the reconstructed backscatter data are reliable compared with satellite observations at a relatively coarse resolution,with Pearson’s coefficients above 0.92 in 6 sample cities.The derived building height from the reconstructed SAR data indicates that the JJJ region experienced a noticeable upward expansion in 1990-2022,e.g.,Beijing has the fastest growth rate of 0.420 km^(3)/decade regarding the total building volumes.The proposed framework of reconstructing SAR data from optical satellite images provides a new insight to complement the long-term and high-resolution backscatter from local to global scales.
基金supported by the National Key Research and Development Program of China(2021YFC2400201)the National Natural Science Foundation of China(nos.51777115 and 81830033)+1 种基金the Tsinghua Precision Medicine Foundation(LC201906)the Shenzhen International Cooperative Research Project(GJHZ20180930110402104).
文摘Neural electrode interfaces are essential to the stimulation safety and recording quality of various bioelectronic therapies.The recently proposed hierarchical platinum-iridium(Pt-Ir)electrodes produced by femtosecond lasers have exhibited superior electrochemical performance in vitro,but their in vivo performance is still unclear.In this study,we explored the electrochemical performance,biological response,and tissue adhesion of hierarchical Pt-Ir electrodes by implantation in adult rat brains for 1,8,and 16 weeks.Regular smooth Pt-Ir electrodes were used as a control.The results showed that the electrochemical performance of both electrodes decreased and leveled off during implantation.However,after 16 weeks,the charge storage capacity of hierarchical electrodes stabilized at~16.8 mC/cm^(2),which was 15 times that of the smooth control electrodes(1.1 mC/cm^(2)).Moreover,the highly structured electrodes had lower impedance amplitude and cutoff frequency values.The similar histological response to smooth electrodes indicated good biocompatibility of the hierarchically structured Pt-Ir electrodes.Given their superior in vivo performance,the femtosecond laser-treated Pt-Ir electrode showed great potential for neuromodulation applications.
