The formation of homogeneous dielectric barrier discharge(DBD)in air is a key scientific problem and core technical problem to be solved for the application of plasmas.Here,we report the effect of two-dimensional(2D)n...The formation of homogeneous dielectric barrier discharge(DBD)in air is a key scientific problem and core technical problem to be solved for the application of plasmas.Here,we report the effect of two-dimensional(2D)nanomaterial Ti_(3)C_(2)T_(x)(Tx=-F,-O and/or-OH)on regulating the electrical discharge characteristics.The field emission and weak bound state property of Ti_(3)C_(2)T_(x)can effectively increase the seed electrons and contribute to the generation of atmospheric pressure homogeneous air DBD.The electron avalanche development for the uneven electrode structure is calculated,and the discharge mode transition is modeled.The comparative analyses of discharge phenomena validate the regulation of Ti_(3)C_(2)T_(x)on the discharge characteristics of DBD.The light emission capture and the voltage and current waveforms verify that the transition of Townsend discharge to streamer discharge is effectively inhibited.The optical emission spectra are used to characterize the plasma and confirm that it is in a non-equilibrium state and the gas temperature is at room temperature.This is the first exploration of Ti_(3)C_(2)T_(x)on the regulation of electrical discharge characteristics as far as we know.This work proves the feasibility of Ti_(3)C_(2)T_(x)as a source of seed electrons to form homogeneous DBD,establishing a preliminary foundation for promoting the application of atmospheric pressure non-equilibrium plasma.展开更多
The global push for carbon neutrality highlights the need for rigorous assessments of whether national efforts align with stated targets.However,existing evaluations often prioritize commitments over tangible progress...The global push for carbon neutrality highlights the need for rigorous assessments of whether national efforts align with stated targets.However,existing evaluations often prioritize commitments over tangible progress,lacking comprehensive and transparent metrics.To bridge this gap,we develop a multidimensional indicator system that evaluates targets,policies,actions,and effectiveness across key areas,including policy implementation,technology deployment,financial investment,and international cooperation.While 151 countries have pledged carbon neutralityd19 of which are developing nations that made commitments in 2024dimplementation remains uneven.Only 72 countries have established complete policy frameworks,and advanced low-carbon technologies are concentrated in a handful of nations.Current trends indicate that global renewable energy capacity will reach just 2.7 times its 2022 level by 2030,falling short of the tripling target.Moreover,the global median action score in 2024 stands at only 25dfar below the target of 65dhighlighting the urgency for stronger efforts.Our findings reveal a significant gap between ambition and action,with renewable energy deployment lagging behind expectations.To accelerate progress,enhanced global cooperation,increased investment,and fewer barriers to technology diffusion are crucial.This study underscores the need for more implementationfocused tracking to ensure carbon neutrality commitments translate into measurable outcomes.展开更多
Cancer,as one of the most notorious health diseases,represents the main reason attributed to millions of worldwide deaths each year.Timely detection and accurate diagnosis are thus vital to cancer prevention and timel...Cancer,as one of the most notorious health diseases,represents the main reason attributed to millions of worldwide deaths each year.Timely detection and accurate diagnosis are thus vital to cancer prevention and timely therapy.Traditional cancer prescreening is not only cumbersome but also heavily reliant on sufficient expert knowledge,which inevitably increases the complexity of cancer diagnosis and limits early cancer diagnosis.To overcome this problem,recent terahertz(THz)technology,as an unconventional bio-friendly detection approach,has emerged with great potential in human disease diagnosis due to its non-ionic and high-resolution features.By combining the THz detection technique and artificial intelligence technique,here we propose a dense and efficient channel attention network(DECANet)framework-based THz diagnosis system for cancer prescreening.The cancer identification and diagnosis process are transformed into one end-to-end classification process of THz signals reflected from cancer tissue.The biosamples of breast and skin cancer tissue are characterized to validate the effectiveness and applicability of the proposed approach.Our quantified results indicate that our proposed THz diagnosis framework has promising feature extraction capability for abnormal cancerous tissue and provides an effective complement tool to assist the healthcare cancer diagnosis.展开更多
The inadequate stability of organic–inorganic hybrid perovskites remains a signifcant barrier to their widespread commercial application in optoelectronic devices.Aging phenomena profoundly afect the optoelectronic p...The inadequate stability of organic–inorganic hybrid perovskites remains a signifcant barrier to their widespread commercial application in optoelectronic devices.Aging phenomena profoundly afect the optoelectronic performance of perovskite-based devices.In addition to enhancing perovskite stability,the real-time detection of aging status,aimed at monitoring the aging progression,holds paramount importance for both fundamental research and the commercialization of organic–inorganic hybrid perovskites.In this study,the aging status of perovskite was real-time investigated by using terahertz time-domain spectroscopy.Our analysis consistently revealed a gradual decline in the intensity of the absorption peak at 0.968 THz with increasing perovskite aging.Furthermore,a systematic discussion was conducted on the variations in intensity and position of the terahertz absorption peaks as the perovskite aged.These fndings facilitate the real-time assessment of perovskite aging,providing a promising method to expedite the commercialization of perovskite-based optoelectronic devices.展开更多
The realization of high-performance tunable absorbers for terahertz frequencies is crucial for advancing applications such as single-pixel imaging and spectroscopy.Based on the strong position sensitivity of metamater...The realization of high-performance tunable absorbers for terahertz frequencies is crucial for advancing applications such as single-pixel imaging and spectroscopy.Based on the strong position sensitivity of metamaterials’electromagnetic response,we combine meta-atoms that support strongly localized modes with suspended flat membranes that can be driven electrostatically.This design maximizes the tunability range for small mechanical displacements of the membranes.We employ a micro-electromechanical system technology and successfully fabricate the devices.Our prototype devices are among the best-performing tunable THz absorbers demonstrated to date,with an ultrathin device thickness(~1/50 of the working wavelength),absorption varying between 60%and 80%in the initial state when the membranes remain suspended,and fast switching speed(~27μs).The absorption is tuned by an applied voltage,with the most marked results achieved when the structure reaches the snap-down state.In this case,the resonance shifts by >200% of the linewidth(14% of the initial resonance frequency),and the absolute absorption modulation measured at the initial resonance can reach 65%.The demonstrated approach can be further optimized and extended to benefit numerous applications in THz technology.展开更多
We introduce a novel method to accurately extract the optical parameters in terahertz reflection imaging. Our method builds on standard self-referencing methods using the reflected signal from the bottom of the imagin...We introduce a novel method to accurately extract the optical parameters in terahertz reflection imaging. Our method builds on standard self-referencing methods using the reflected signal from the bottom of the imaging window material to further compensate for time-dependent system fluctuations and position-dependent variation in the window thickness. Our proposed method not only improves the accuracy, but also simplifies the imaging procedure and reduces measurement times.展开更多
Terahertz(THz)topological photonic structures are promising for last-centimeter communication in intra/interchip communication systems because they support bit-error-free THz signal transmission with topological robus...Terahertz(THz)topological photonic structures are promising for last-centimeter communication in intra/interchip communication systems because they support bit-error-free THz signal transmission with topological robustness.Active and dynamically tunable THz topological photonic components have not yet been experimentally realized.Here,we experimentally demonstrate a THz topological switch(270-290 GHz)based on a valley Hall photonic crystal structured high-resistivity silicon substrate,in which the THz waves can be dynamically turned on/off by an external 447 nm continuous-wave laser.Our device exhibited an on/off ratio of 19 dB under a pumping light intensity of 240 mW/mm^(2).The 3 dB switching bandwidth was〜60 kHz.展开更多
Carbon-coated Cu nanocomposites (Cu@C NCs) consisting of core-shell nanoparticles and nanorods weresynthesized by arc discharge plasma under an atmosphere of He and H_(2) gas, and the N-doping of themwas achieved by a...Carbon-coated Cu nanocomposites (Cu@C NCs) consisting of core-shell nanoparticles and nanorods weresynthesized by arc discharge plasma under an atmosphere of He and H_(2) gas, and the N-doping of themwas achieved by a post-treatment process using ureal as the precursor. The concentration of N in the Ndoped samples varies in the range of 0.62%-2.31 % (in mole), with a transformation from pyrrolic N tographitic N when increasing the relative content of ureal. Dielectric properties of the NCs without or withN-doping in the microwave and THz bands were investigated. The N-doped samples achieve theenhanced dielectric loss in both microwave and THz bands. In the microwave band, dielectric loss wasdominated by interfacial polarization, dipolar polarization, and conduction loss, while in the THz band,plasma resonance, ionic polarization and conduction loss are responsible for the dielectric loss, with astrong absorption characteristic dominated by conductive effect.展开更多
基金support of the Science and Technology Innovation Commission of Shenzhen(Nos.JCYJ20180507181858539 and JCYJ20190808173815205)Guangdong Basic and Applied Basic Research Foundation(No.2019A1515012111)+2 种基金Shenzhen Science and Technology Program(No.KQTD20180412181422399)the National Key R&D Program of China(No.2019YFB2204500)National Natural Science Foundation of China(No.51804199)。
文摘The formation of homogeneous dielectric barrier discharge(DBD)in air is a key scientific problem and core technical problem to be solved for the application of plasmas.Here,we report the effect of two-dimensional(2D)nanomaterial Ti_(3)C_(2)T_(x)(Tx=-F,-O and/or-OH)on regulating the electrical discharge characteristics.The field emission and weak bound state property of Ti_(3)C_(2)T_(x)can effectively increase the seed electrons and contribute to the generation of atmospheric pressure homogeneous air DBD.The electron avalanche development for the uneven electrode structure is calculated,and the discharge mode transition is modeled.The comparative analyses of discharge phenomena validate the regulation of Ti_(3)C_(2)T_(x)on the discharge characteristics of DBD.The light emission capture and the voltage and current waveforms verify that the transition of Townsend discharge to streamer discharge is effectively inhibited.The optical emission spectra are used to characterize the plasma and confirm that it is in a non-equilibrium state and the gas temperature is at room temperature.This is the first exploration of Ti_(3)C_(2)T_(x)on the regulation of electrical discharge characteristics as far as we know.This work proves the feasibility of Ti_(3)C_(2)T_(x)as a source of seed electrons to form homogeneous DBD,establishing a preliminary foundation for promoting the application of atmospheric pressure non-equilibrium plasma.
基金supported by the National Natural Science Foundation of China(No.72140002,72348001 and 72204137).
文摘The global push for carbon neutrality highlights the need for rigorous assessments of whether national efforts align with stated targets.However,existing evaluations often prioritize commitments over tangible progress,lacking comprehensive and transparent metrics.To bridge this gap,we develop a multidimensional indicator system that evaluates targets,policies,actions,and effectiveness across key areas,including policy implementation,technology deployment,financial investment,and international cooperation.While 151 countries have pledged carbon neutralityd19 of which are developing nations that made commitments in 2024dimplementation remains uneven.Only 72 countries have established complete policy frameworks,and advanced low-carbon technologies are concentrated in a handful of nations.Current trends indicate that global renewable energy capacity will reach just 2.7 times its 2022 level by 2030,falling short of the tripling target.Moreover,the global median action score in 2024 stands at only 25dfar below the target of 65dhighlighting the urgency for stronger efforts.Our findings reveal a significant gap between ambition and action,with renewable energy deployment lagging behind expectations.To accelerate progress,enhanced global cooperation,increased investment,and fewer barriers to technology diffusion are crucial.This study underscores the need for more implementationfocused tracking to ensure carbon neutrality commitments translate into measurable outcomes.
基金supported by the National Natural Science Foundation of China(52175115,52405587)supported by the China Postdoctoral Science Foundation(2023M740922)Postdoctoral Fellowship Program of CPSF(GZB20230953).
文摘Cancer,as one of the most notorious health diseases,represents the main reason attributed to millions of worldwide deaths each year.Timely detection and accurate diagnosis are thus vital to cancer prevention and timely therapy.Traditional cancer prescreening is not only cumbersome but also heavily reliant on sufficient expert knowledge,which inevitably increases the complexity of cancer diagnosis and limits early cancer diagnosis.To overcome this problem,recent terahertz(THz)technology,as an unconventional bio-friendly detection approach,has emerged with great potential in human disease diagnosis due to its non-ionic and high-resolution features.By combining the THz detection technique and artificial intelligence technique,here we propose a dense and efficient channel attention network(DECANet)framework-based THz diagnosis system for cancer prescreening.The cancer identification and diagnosis process are transformed into one end-to-end classification process of THz signals reflected from cancer tissue.The biosamples of breast and skin cancer tissue are characterized to validate the effectiveness and applicability of the proposed approach.Our quantified results indicate that our proposed THz diagnosis framework has promising feature extraction capability for abnormal cancerous tissue and provides an effective complement tool to assist the healthcare cancer diagnosis.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2330114,61975135,and 62105216)Medical-Engineering Interdisciplinary Research Foundation of Shenzhen University and Special projects in key areas of Guangdong Province(No.2022ZDZX2053)+1 种基金Shenzhen University 2035 Plan Project,Shenzhen Key Laboratory of Photonics and Biophotonics(No.ZDSYS20210623092006020)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110477).
文摘The inadequate stability of organic–inorganic hybrid perovskites remains a signifcant barrier to their widespread commercial application in optoelectronic devices.Aging phenomena profoundly afect the optoelectronic performance of perovskite-based devices.In addition to enhancing perovskite stability,the real-time detection of aging status,aimed at monitoring the aging progression,holds paramount importance for both fundamental research and the commercialization of organic–inorganic hybrid perovskites.In this study,the aging status of perovskite was real-time investigated by using terahertz time-domain spectroscopy.Our analysis consistently revealed a gradual decline in the intensity of the absorption peak at 0.968 THz with increasing perovskite aging.Furthermore,a systematic discussion was conducted on the variations in intensity and position of the terahertz absorption peaks as the perovskite aged.These fndings facilitate the real-time assessment of perovskite aging,providing a promising method to expedite the commercialization of perovskite-based optoelectronic devices.
文摘The realization of high-performance tunable absorbers for terahertz frequencies is crucial for advancing applications such as single-pixel imaging and spectroscopy.Based on the strong position sensitivity of metamaterials’electromagnetic response,we combine meta-atoms that support strongly localized modes with suspended flat membranes that can be driven electrostatically.This design maximizes the tunability range for small mechanical displacements of the membranes.We employ a micro-electromechanical system technology and successfully fabricate the devices.Our prototype devices are among the best-performing tunable THz absorbers demonstrated to date,with an ultrathin device thickness(~1/50 of the working wavelength),absorption varying between 60%and 80%in the initial state when the membranes remain suspended,and fast switching speed(~27μs).The absorption is tuned by an applied voltage,with the most marked results achieved when the structure reaches the snap-down state.In this case,the resonance shifts by >200% of the linewidth(14% of the initial resonance frequency),and the absolute absorption modulation measured at the initial resonance can reach 65%.The demonstrated approach can be further optimized and extended to benefit numerous applications in THz technology.
基金Research Grants Council of Hong Kong(415313,14205514)Direct Grant,Chinese University of Hong Kong
文摘We introduce a novel method to accurately extract the optical parameters in terahertz reflection imaging. Our method builds on standard self-referencing methods using the reflected signal from the bottom of the imaging window material to further compensate for time-dependent system fluctuations and position-dependent variation in the window thickness. Our proposed method not only improves the accuracy, but also simplifies the imaging procedure and reduces measurement times.
基金National Natural Science Foundation of China(61805148,61805150,61975135)International Cooperation and Exchanges NSFC(61911530218)+5 种基金Shenzhen International Scientific and Technological Cooperation Project(GJHZ20190822095407131)Natural Science Foundation of Guangdong Province(2019A1515010869,2021A1515012296)Guangdong Medical Science and Technology Research Fund(A2020401)Shenzhen University New Researcher Startup Funding(2019134,RC00058)Shenzhen Science and Technology Program(KQTD20180412181422399)Research Grants Council of Hong Kong(14209519).
文摘Terahertz(THz)topological photonic structures are promising for last-centimeter communication in intra/interchip communication systems because they support bit-error-free THz signal transmission with topological robustness.Active and dynamically tunable THz topological photonic components have not yet been experimentally realized.Here,we experimentally demonstrate a THz topological switch(270-290 GHz)based on a valley Hall photonic crystal structured high-resistivity silicon substrate,in which the THz waves can be dynamically turned on/off by an external 447 nm continuous-wave laser.Our device exhibited an on/off ratio of 19 dB under a pumping light intensity of 240 mW/mm^(2).The 3 dB switching bandwidth was〜60 kHz.
基金financially supported by the National Natural Science Foundation of China(NOs.U1908220 and 51331006).
文摘Carbon-coated Cu nanocomposites (Cu@C NCs) consisting of core-shell nanoparticles and nanorods weresynthesized by arc discharge plasma under an atmosphere of He and H_(2) gas, and the N-doping of themwas achieved by a post-treatment process using ureal as the precursor. The concentration of N in the Ndoped samples varies in the range of 0.62%-2.31 % (in mole), with a transformation from pyrrolic N tographitic N when increasing the relative content of ureal. Dielectric properties of the NCs without or withN-doping in the microwave and THz bands were investigated. The N-doped samples achieve theenhanced dielectric loss in both microwave and THz bands. In the microwave band, dielectric loss wasdominated by interfacial polarization, dipolar polarization, and conduction loss, while in the THz band,plasma resonance, ionic polarization and conduction loss are responsible for the dielectric loss, with astrong absorption characteristic dominated by conductive effect.
