Quasi one-dimensional polycrystalline samples of Ba_(3)Hf(Se_(1-x)Te_(x))_(5)(x=0-1)are synthesized under hightemperature and high-pressure conditions.Using the powder x-ray diffraction technique and first-principles ...Quasi one-dimensional polycrystalline samples of Ba_(3)Hf(Se_(1-x)Te_(x))_(5)(x=0-1)are synthesized under hightemperature and high-pressure conditions.Using the powder x-ray diffraction technique and first-principles calculations,Ba_(3)HfSe_(5)is identified as having a hexagonal structure with a space group of P63/mcm(193)and lattice constants of a=9.5756(1)A°,c=6.3802(7)A°.The structure is composed of Hf(Se1)6 chains and Se_(2)linear chains extending along the c-axis.As the doping content of Te increases,the lattice expands and leads to 5.8%and 7.3%increases of the a and c values and a 20.1%increase of the unit cell volume of Ba_(3)HfTe_(5)compared to Ba_(3)HfSe_(5).The detailed structural refinements show that the Hf vacancies decrease gradually as Te doping increases in the Ba_(3)Hf(Se_(1-x)Te_(x))_(5)(x=0-1)materials,which leads to a decrease of electronic localization.In addition,the lower electronegativity of Te and the more extended orbitals with respect to Se contribute to orbital overlap between the inter chains.All these dominate the enhanced electron hopping,leading to a reduction of the bandgap from 1.95 eV to 0.23 eV for Ba_(3)Hf(Se_(1-x)Te_(x))_(5)(x=0-1)materials as the Ba_(3)HfSe_(5)evolves to Ba_(3)HfTe_(5).展开更多
Manganese-catalyzed hydrogenation of unsaturated molecules has made tremendous progresses recently benefiting from non-innocent pincer or bidentate ligands for manganese.Herein,we describe the hydrogenation of quinoli...Manganese-catalyzed hydrogenation of unsaturated molecules has made tremendous progresses recently benefiting from non-innocent pincer or bidentate ligands for manganese.Herein,we describe the hydrogenation of quinolines and imines catalyzed by simple manganese carbonyls,Mn2(CO)10 or MnBr(CO)5,thus eliminating the prerequisite pincer-type or bidentate ligands.展开更多
Daytime HONO photolysis is an important source of atmospheric hydroxyl radicals(OH).Knowledge of HONO formation chemistry under typical haze conditions,however,is still limited.In the Multiphase chemistry experiment i...Daytime HONO photolysis is an important source of atmospheric hydroxyl radicals(OH).Knowledge of HONO formation chemistry under typical haze conditions,however,is still limited.In the Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain in 2018,we investigated the wintertime HONO formation and its atmospheric implications at a rural site Gucheng.Three different episodes based on atmospheric aerosol loading levels were classified:clean periods(CPs),moderately polluted periods(MPPs)and severely polluted periods(SPPs).Correlation analysis revealed that HONO formation via heteroge.neous conversion of NO_(2)was more efficient on aerosol surfaces than on ground,highlighting the important role of aerosols in promoting HONO formation.Daytime HONO budget analysis indicated a large missing source(with an average production rate of 0.66±0.26,0.97±0.47 and 1.45±0.55 ppbV/hr for CPs,MPPs and SPPs,respectively),which strongly correlated with photo-enhanced reactions(NO_(2)heterogeneous reaction and particulate nitrate photolysis).Average OH formation derived from HONO photolysis reached up to(0.92±0.71),(1.75±1.26)and(1.82±1.47)ppbV/hr in CPs,MPPs and SPPs respectively,much higher than that from O3 photolysis(i.e.,(0.004±0.004),(0.006±0.007)and(0.0035±0.0034)ppbV/hr).Such high OH production rates could markedly regulate the atmospheric oxidation capacity and hence promote the formation of secondary aerosols and pollutants.展开更多
The Ensemble Kalman Filter(EnKF),as the most popular sequential data assimilation algorithm for history matching,has the intrinsic problem of high computational cost and the potential inconsistency of state variables ...The Ensemble Kalman Filter(EnKF),as the most popular sequential data assimilation algorithm for history matching,has the intrinsic problem of high computational cost and the potential inconsistency of state variables updated at each loop of data assimilation and its corresponding reservoir simulated result.This problem forbids the reservoir engineers to make the best use of the 4D seismic data,which provides valuable information about the fluid change inside the reservoir.Moreover,only matching the production data in the past is not enough to accurately forecast the future,and the development plan based on the false forecast is very likely to be suboptimal.To solve this problem,we developed a workflow for geophysical and production data history matching by modifying ensemble smoother with multiple data assimilation(ESMDA).In this work,we derived the mathematical expressions of ESMDA and discussed its scope of applications.The geophysical data we used is P-wave impedance,which is typically included in a basic seismic interpretation,and it directly reflects the saturation change in the reservoir.Full resolution of the seismic data is not necessary,we subsampled the P-wave impedance data to further reduce the computational cost.With our case studies on a benchmark synthetic reservoir model,we also showed the supremacy of matching both geophysical and production data,than the traditional reservoir history matching merely on the production data:the overall percentage error of the observed data is halved,and the variances of the updated forecasts are reduced by two orders of the magnitude.展开更多
Globally,fossil fuel dependence has created several environmental challenges and climate change.Hence,creating other alternative renewable and ecologically friendly bio-energy sources is necessary.Lignocellulosic biom...Globally,fossil fuel dependence has created several environmental challenges and climate change.Hence,creating other alternative renewable and ecologically friendly bio-energy sources is necessary.Lignocellulosic biomass has gained significant attention recently as a renewable material for biofuel production.The large amounts of plantain and banana plant parts wasted after harvesting,as well as the peels generated daily by the fruit market and industries,demonstrate the potential of bioenergy resources.This review briefly assesses plantain and banana plant biomass(PBB)generated in the developing,developed,and underdeveloped countries,the consumable parts,and feasible products yield.It emphasized the advantages and disadvantages of the commonly adopted treatment technologies of composting,incineration,and landfilling.Further,the utilization of PBB as catalysts in biodiesel synthesis was briefly highlighted.To optimize recovery of biofuel,different integration routes of pyrolysis,anaerobic digestion,fermentation,hydrothermal carbonization,hydrothermal liquefaction,and hydrothermal gasification for the valorization of the PBB were proposed.The complex compounds present in the PBB(hemicellulose,cellulose,and lignin)can be converted into valuable bio-products such as methane gas and bio-ethanol for bioenergy,and nutrients to promote bioactive ingredients.The investigation of the viability and innovation potential of the integrated routes’technology is necessary to improve the circular bio-economy and the recovery of biofuels from biomass waste,particularly PBB.展开更多
The long sought cubic gauche polymeric nitrogen(cg-N)consisting of N-N single bonds has been synthesized by one pot route using sodium azide as a precursor at ambient conditions.The recrystallization process was desig...The long sought cubic gauche polymeric nitrogen(cg-N)consisting of N-N single bonds has been synthesized by one pot route using sodium azide as a precursor at ambient conditions.The recrystallization process was designed to expose crystal faces with low activation energy that facilitates initiating the polymeric reaction at ambient conditions.The azide was considered as a precursor due to the low energy barrier in transforming double bonded N=N to single bonded cg-N.Raman spectrum measurements detected the emerging vibron peaks at 635 cm^(−1) for the polymerized sodium azide samples,demonstrating the formation of cg-N with N-N single bonds.Different from traditional high-pressure technique and recently developed plasma enhanced chemical vapor deposition method,the route achieves the quantitative synthesis of cg-N at ambient conditions.The one pot synthesis of cg-N offers potential for further scaling up production as well as practical applications of polymeric nitrogen based materials as high energy density materials.展开更多
From April 2020 to June 2022,a Ca+lidar with dual-wavelength and narrow-band emitting lasers utilizing all-solid-state technology was employed to conduct observations in Beijing(40.41°N,116.01°E)for a total ...From April 2020 to June 2022,a Ca+lidar with dual-wavelength and narrow-band emitting lasers utilizing all-solid-state technology was employed to conduct observations in Beijing(40.41°N,116.01°E)for a total duration of 1797.79 hours over 280 nights.A total of 286 sporadic Ca+layers were observed,with heights ranging from 88 to 120 km and densities varying from 5.33 to 2200 cm^(-3).We simultaneously observed the ionosonde,located 28 km from the lidar,and found a correlation of 61.89%between the sporadic Ca+layer and the sporadic E layer.When the sporadic Ca+layer has a downward phase trend,there is a correlation of 76.84%.By excluding the influence of ionosonde sensitivity,we focus only on calcium ions that have a density exceeding 140 cm^(-3),which exhibit a correlation of82.25%.Above 100 km,the correlation significantly increases,reaching approximately 90%.Furthermore,the correlation between the sporadic Ca+layer and the sporadic E layer is particularly noticeable during the summer season,reaching around 90%.This phenomenon can be attributed to the variations in metal ions that occur during different seasons.展开更多
In this study, a numerical method was proposed to evaluate the calligraphy work called calligraphy evaluation system. Four classical chirographies of ＂Kaisho＂, ＂Gyosho＂, ＂Sousho＂ and ＂Hiragana＂, and 47 charact...In this study, a numerical method was proposed to evaluate the calligraphy work called calligraphy evaluation system. Four classical chirographies of ＂Kaisho＂, ＂Gyosho＂, ＂Sousho＂ and ＂Hiragana＂, and 47 characters for each chirography, were selected and analyzed by this system. The ＂Sumi＂ distribution of character was clarified from 12 directions and summarized into four parts of horizontal part, diagonal left part, vertical part and diagonal fight part. The character＇s contour line was converted to a signal data in order to calculate roundness index. The degree of character＇s radian was presented by roundness index. The smooth index was calculated at the same time. Additionally, width index, ＂Sumi＂ ratio, stability index also were calculated to contrast the features of each style. The main character points of four styles of ＂Kaisho＇, ＂Gyosho＂, ＂Sousho＂, ＂Hiragana＂ were extracted to compare each other, and provide a reference for learners. The learners could obtain the quantitative data to understand their work＇s characteristics. It can also be compared with other person＇s work by this system in order to improve learners＇ writing skill.展开更多
Flexoelectric and photo-flexoelectricity are scientifically intriguing and hold considerable potential for various applications such as soft strain sensing,photovoltaics,energy harvesting,etc.Among flexoelectric mater...Flexoelectric and photo-flexoelectricity are scientifically intriguing and hold considerable potential for various applications such as soft strain sensing,photovoltaics,energy harvesting,etc.Among flexoelectric materials,freestanding ferroelectric thin films are believed to have huge flexoelectricity and tunability due to their excellent lattice regulatory freedom and sustainability to larger strain gradients.In this work,we demonstrated a freestanding BiFeO3(BFO)thin film-based soft strain sensor and explored their flexoelectric coefficient and flexoelectric photovoltaic effect under different strain gradients.Under different bending scales,the photocurrent of the thin film exhibits a step-like variation,indicating that the sensor can measure strain gradient with high sensitivity.These results show the potential application of freestanding ferroelectric films in flexible devices.展开更多
Accurate liquid concentration detection is vital for medical,industrial,and environmental applications,yet conventional methods still face limitations.We propose an ultrasound probe with a self-assembled polymer whisp...Accurate liquid concentration detection is vital for medical,industrial,and environmental applications,yet conventional methods still face limitations.We propose an ultrasound probe with a self-assembled polymer whispering-gallery-mode(WGM)microcavity,leveraging the photoacoustic(PA)effect and a distributed feedback(DFB)laser tuning system for ultrasensitive quantification.The probe achieves 13.5 Pa sensitivity and 42 MHz bandwidth(±6 dB),ensuring broad applicability in diverse liquids.Overcoming traditional WGM sensors'instability,our integrated platform demonstrates a recordlow detection limit of 10^(-7)g/mL for crystal violet among substrate-free,real-time methods.Unifying the microcavity,laser,and electronics into a portable architecture,this system enables high-fidelity,nondestructive liquid analysis with strong anti-interference and endoscope-deployable sensing in complex environments.展开更多
Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors.Using a developed one pot method...Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors.Using a developed one pot method,we successfully synthesized the atomic polymeric nitrogen employing lithium azide as a precursor.Raman spectrum measurements detected the emerging vibrational peak at 635 cm-1for the polymerized lithium azide sample,indicating the formation of atomic cubic gauche nitrogen(cg-N)with N–N single bonds.Through systematic investigations,the preparation conditions are optimized to be 180℃with a reaction time of 3 h for obtaining atomic cubic gauche polymeric nitrogen.The one pot method achieves the quantitative synthesis of cg-N at ambient pressure using alkali metal azide as the precursors.It offers a simple way for further scalable synthesis of polymeric atomic nitrogen high energy density materials.展开更多
The polymerized nitrogen material with single bonds is considered one of the candidates for storing huge chemical energy due to the significant energy difference between triply bonded di-nitrogen and singly bonded nit...The polymerized nitrogen material with single bonds is considered one of the candidates for storing huge chemical energy due to the significant energy difference between triply bonded di-nitrogen and singly bonded nitrogen[1].It was anticipated that the greatest utility of fully single-bonded nitrogen would yield a tenfold improvement in detonation pressure over HMX(one of the more powerful high explosives)[2]and therefore polymerized nitrogen is of great interest to physical sciences.It was predicted in 1985 that molecule nitrogen would polymerize to atomic solid at high pressure[3].展开更多
基金supported by the National Key R&D Program of China(Grant Nos.2023YFA1406001 and 2024YFA1408004)the National Natural Science Foundation of China(Grant Nos.12104488 and 12474097).
文摘Quasi one-dimensional polycrystalline samples of Ba_(3)Hf(Se_(1-x)Te_(x))_(5)(x=0-1)are synthesized under hightemperature and high-pressure conditions.Using the powder x-ray diffraction technique and first-principles calculations,Ba_(3)HfSe_(5)is identified as having a hexagonal structure with a space group of P63/mcm(193)and lattice constants of a=9.5756(1)A°,c=6.3802(7)A°.The structure is composed of Hf(Se1)6 chains and Se_(2)linear chains extending along the c-axis.As the doping content of Te increases,the lattice expands and leads to 5.8%and 7.3%increases of the a and c values and a 20.1%increase of the unit cell volume of Ba_(3)HfTe_(5)compared to Ba_(3)HfSe_(5).The detailed structural refinements show that the Hf vacancies decrease gradually as Te doping increases in the Ba_(3)Hf(Se_(1-x)Te_(x))_(5)(x=0-1)materials,which leads to a decrease of electronic localization.In addition,the lower electronegativity of Te and the more extended orbitals with respect to Se contribute to orbital overlap between the inter chains.All these dominate the enhanced electron hopping,leading to a reduction of the bandgap from 1.95 eV to 0.23 eV for Ba_(3)Hf(Se_(1-x)Te_(x))_(5)(x=0-1)materials as the Ba_(3)HfSe_(5)evolves to Ba_(3)HfTe_(5).
基金the National Natural Science Foundation of China(No.21772202,21831008)Beijing Municipal Science&Technology Commission(No.Z191100007219009)Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXXM201901)。
文摘Manganese-catalyzed hydrogenation of unsaturated molecules has made tremendous progresses recently benefiting from non-innocent pincer or bidentate ligands for manganese.Herein,we describe the hydrogenation of quinolines and imines catalyzed by simple manganese carbonyls,Mn2(CO)10 or MnBr(CO)5,thus eliminating the prerequisite pincer-type or bidentate ligands.
基金supported by the National Key Research and Development Program of China (No. 2017YFC210104)the National Natural Science Foundation of China (No. 91644218)+2 种基金the Guangdong Innovative and Entrepreneurial Research Team Program (No. 2016ZT06N263)the Special Fund Project for Science and Technology Innovation Strategy ofGuangdong Province (No. 2019B121205004)the financial support from the China Scholarship Council (CSC)
文摘Daytime HONO photolysis is an important source of atmospheric hydroxyl radicals(OH).Knowledge of HONO formation chemistry under typical haze conditions,however,is still limited.In the Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain in 2018,we investigated the wintertime HONO formation and its atmospheric implications at a rural site Gucheng.Three different episodes based on atmospheric aerosol loading levels were classified:clean periods(CPs),moderately polluted periods(MPPs)and severely polluted periods(SPPs).Correlation analysis revealed that HONO formation via heteroge.neous conversion of NO_(2)was more efficient on aerosol surfaces than on ground,highlighting the important role of aerosols in promoting HONO formation.Daytime HONO budget analysis indicated a large missing source(with an average production rate of 0.66±0.26,0.97±0.47 and 1.45±0.55 ppbV/hr for CPs,MPPs and SPPs,respectively),which strongly correlated with photo-enhanced reactions(NO_(2)heterogeneous reaction and particulate nitrate photolysis).Average OH formation derived from HONO photolysis reached up to(0.92±0.71),(1.75±1.26)and(1.82±1.47)ppbV/hr in CPs,MPPs and SPPs respectively,much higher than that from O3 photolysis(i.e.,(0.004±0.004),(0.006±0.007)and(0.0035±0.0034)ppbV/hr).Such high OH production rates could markedly regulate the atmospheric oxidation capacity and hence promote the formation of secondary aerosols and pollutants.
基金supported by Chinese National Science and Technology Major Project(2016ZX05015-005).
文摘The Ensemble Kalman Filter(EnKF),as the most popular sequential data assimilation algorithm for history matching,has the intrinsic problem of high computational cost and the potential inconsistency of state variables updated at each loop of data assimilation and its corresponding reservoir simulated result.This problem forbids the reservoir engineers to make the best use of the 4D seismic data,which provides valuable information about the fluid change inside the reservoir.Moreover,only matching the production data in the past is not enough to accurately forecast the future,and the development plan based on the false forecast is very likely to be suboptimal.To solve this problem,we developed a workflow for geophysical and production data history matching by modifying ensemble smoother with multiple data assimilation(ESMDA).In this work,we derived the mathematical expressions of ESMDA and discussed its scope of applications.The geophysical data we used is P-wave impedance,which is typically included in a basic seismic interpretation,and it directly reflects the saturation change in the reservoir.Full resolution of the seismic data is not necessary,we subsampled the P-wave impedance data to further reduce the computational cost.With our case studies on a benchmark synthetic reservoir model,we also showed the supremacy of matching both geophysical and production data,than the traditional reservoir history matching merely on the production data:the overall percentage error of the observed data is halved,and the variances of the updated forecasts are reduced by two orders of the magnitude.
基金This work was supported by the Start-Up Funding for Research of Nanchang Institute of Science and Technology(NGRCZX-22-03)School of Environment and Civil Engineering,Nanchang,Jiangxi,China.
文摘Globally,fossil fuel dependence has created several environmental challenges and climate change.Hence,creating other alternative renewable and ecologically friendly bio-energy sources is necessary.Lignocellulosic biomass has gained significant attention recently as a renewable material for biofuel production.The large amounts of plantain and banana plant parts wasted after harvesting,as well as the peels generated daily by the fruit market and industries,demonstrate the potential of bioenergy resources.This review briefly assesses plantain and banana plant biomass(PBB)generated in the developing,developed,and underdeveloped countries,the consumable parts,and feasible products yield.It emphasized the advantages and disadvantages of the commonly adopted treatment technologies of composting,incineration,and landfilling.Further,the utilization of PBB as catalysts in biodiesel synthesis was briefly highlighted.To optimize recovery of biofuel,different integration routes of pyrolysis,anaerobic digestion,fermentation,hydrothermal carbonization,hydrothermal liquefaction,and hydrothermal gasification for the valorization of the PBB were proposed.The complex compounds present in the PBB(hemicellulose,cellulose,and lignin)can be converted into valuable bio-products such as methane gas and bio-ethanol for bioenergy,and nutrients to promote bioactive ingredients.The investigation of the viability and innovation potential of the integrated routes’technology is necessary to improve the circular bio-economy and the recovery of biofuels from biomass waste,particularly PBB.
文摘The long sought cubic gauche polymeric nitrogen(cg-N)consisting of N-N single bonds has been synthesized by one pot route using sodium azide as a precursor at ambient conditions.The recrystallization process was designed to expose crystal faces with low activation energy that facilitates initiating the polymeric reaction at ambient conditions.The azide was considered as a precursor due to the low energy barrier in transforming double bonded N=N to single bonded cg-N.Raman spectrum measurements detected the emerging vibron peaks at 635 cm^(−1) for the polymerized sodium azide samples,demonstrating the formation of cg-N with N-N single bonds.Different from traditional high-pressure technique and recently developed plasma enhanced chemical vapor deposition method,the route achieves the quantitative synthesis of cg-N at ambient conditions.The one pot synthesis of cg-N offers potential for further scaling up production as well as practical applications of polymeric nitrogen based materials as high energy density materials.
基金supported by the National Natural Science Foundation of China(42004134,42374204,41627804)Fundamental Research Program of Shanxi Province(202303021221051)+2 种基金State Key Laboratory of Space Weather,Scientific Projects of Hainan Province(ZDYF2021GXJS040)the Innovational Fund for Scientific and Technological Personnel of Hainan Province(KJRC2023C05)Chinese Academy of Sciences(YSBR-018)。
文摘From April 2020 to June 2022,a Ca+lidar with dual-wavelength and narrow-band emitting lasers utilizing all-solid-state technology was employed to conduct observations in Beijing(40.41°N,116.01°E)for a total duration of 1797.79 hours over 280 nights.A total of 286 sporadic Ca+layers were observed,with heights ranging from 88 to 120 km and densities varying from 5.33 to 2200 cm^(-3).We simultaneously observed the ionosonde,located 28 km from the lidar,and found a correlation of 61.89%between the sporadic Ca+layer and the sporadic E layer.When the sporadic Ca+layer has a downward phase trend,there is a correlation of 76.84%.By excluding the influence of ionosonde sensitivity,we focus only on calcium ions that have a density exceeding 140 cm^(-3),which exhibit a correlation of82.25%.Above 100 km,the correlation significantly increases,reaching approximately 90%.Furthermore,the correlation between the sporadic Ca+layer and the sporadic E layer is particularly noticeable during the summer season,reaching around 90%.This phenomenon can be attributed to the variations in metal ions that occur during different seasons.
文摘In this study, a numerical method was proposed to evaluate the calligraphy work called calligraphy evaluation system. Four classical chirographies of ＂Kaisho＂, ＂Gyosho＂, ＂Sousho＂ and ＂Hiragana＂, and 47 characters for each chirography, were selected and analyzed by this system. The ＂Sumi＂ distribution of character was clarified from 12 directions and summarized into four parts of horizontal part, diagonal left part, vertical part and diagonal fight part. The character＇s contour line was converted to a signal data in order to calculate roundness index. The degree of character＇s radian was presented by roundness index. The smooth index was calculated at the same time. Additionally, width index, ＂Sumi＂ ratio, stability index also were calculated to contrast the features of each style. The main character points of four styles of ＂Kaisho＇, ＂Gyosho＂, ＂Sousho＂, ＂Hiragana＂ were extracted to compare each other, and provide a reference for learners. The learners could obtain the quantitative data to understand their work＇s characteristics. It can also be compared with other person＇s work by this system in order to improve learners＇ writing skill.
基金funded by the Hong Kong Research Grants Council(Grant:PolyU 15301421)the Science and Technology Projects in Guangzhou(No.202201000008)+1 种基金the National Natural Science Foundation of China(Nos.U22A20117,52002134)support from Hong Kong Scholar Program(No.XJ2022004).
文摘Flexoelectric and photo-flexoelectricity are scientifically intriguing and hold considerable potential for various applications such as soft strain sensing,photovoltaics,energy harvesting,etc.Among flexoelectric materials,freestanding ferroelectric thin films are believed to have huge flexoelectricity and tunability due to their excellent lattice regulatory freedom and sustainability to larger strain gradients.In this work,we demonstrated a freestanding BiFeO3(BFO)thin film-based soft strain sensor and explored their flexoelectric coefficient and flexoelectric photovoltaic effect under different strain gradients.Under different bending scales,the photocurrent of the thin film exhibits a step-like variation,indicating that the sensor can measure strain gradient with high sensitivity.These results show the potential application of freestanding ferroelectric films in flexible devices.
基金supported by the National Natural Science Foundation of China(No.62305006)the Natural Science Foundation of Jiangsu Province(Nos.BK20230287 and BK20230286)+1 种基金the Nantong Social Livelihood Science and Technology Planning Project(No.MS12022003)the Nantong Social Livelihood Science and Technology Planning Project(No.MS2023071)。
文摘Accurate liquid concentration detection is vital for medical,industrial,and environmental applications,yet conventional methods still face limitations.We propose an ultrasound probe with a self-assembled polymer whispering-gallery-mode(WGM)microcavity,leveraging the photoacoustic(PA)effect and a distributed feedback(DFB)laser tuning system for ultrasensitive quantification.The probe achieves 13.5 Pa sensitivity and 42 MHz bandwidth(±6 dB),ensuring broad applicability in diverse liquids.Overcoming traditional WGM sensors'instability,our integrated platform demonstrates a recordlow detection limit of 10^(-7)g/mL for crystal violet among substrate-free,real-time methods.Unifying the microcavity,laser,and electronics into a portable architecture,this system enables high-fidelity,nondestructive liquid analysis with strong anti-interference and endoscope-deployable sensing in complex environments.
基金supported by the National Key R&D Program of China(Grant No.2023YFA1406000)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-052).
文摘Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors.Using a developed one pot method,we successfully synthesized the atomic polymeric nitrogen employing lithium azide as a precursor.Raman spectrum measurements detected the emerging vibrational peak at 635 cm-1for the polymerized lithium azide sample,indicating the formation of atomic cubic gauche nitrogen(cg-N)with N–N single bonds.Through systematic investigations,the preparation conditions are optimized to be 180℃with a reaction time of 3 h for obtaining atomic cubic gauche polymeric nitrogen.The one pot method achieves the quantitative synthesis of cg-N at ambient pressure using alkali metal azide as the precursors.It offers a simple way for further scalable synthesis of polymeric atomic nitrogen high energy density materials.
基金supported by the National Natural Science Foun-dation of China(11921004)Ministry of Science&Technology(2023YFA1406000)CAS Project for Young Scientists in Basic Research(YSBR.052)of China.
文摘The polymerized nitrogen material with single bonds is considered one of the candidates for storing huge chemical energy due to the significant energy difference between triply bonded di-nitrogen and singly bonded nitrogen[1].It was anticipated that the greatest utility of fully single-bonded nitrogen would yield a tenfold improvement in detonation pressure over HMX(one of the more powerful high explosives)[2]and therefore polymerized nitrogen is of great interest to physical sciences.It was predicted in 1985 that molecule nitrogen would polymerize to atomic solid at high pressure[3].
