Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often ...Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often posing diagnostic challenges.Dermoscopy and reflectance confocal microscopy(RCM)can aid in their differentiation,yet their specific features under these tools have not been systematically described.This study aims to summarize and analyze the dermoscopic and RCM features of VEN,SK,VP,VV,and NS.Methods:A total of 121 patients with histopathologically confirmed verrucous proliferative skin diseases were enrolled.Dermoscopy and RCM imaging was used to observe and analyze the microscopic features of these conditions.Results:Under dermoscopy,the 5 diseases displayed distinct characteristics:VEN typically showed gyriform structures;SK was characterized by gyriform structures,comedo-like openings,and milia-like cysts;VP and VV featured dotted vessels and frogspawn-like structures;NS presented as brownish-yellow globules.RCM revealed shared features such as hyperkeratosis and acanthosis across all 5 diseases.Specific features included gyriform structures and elongated rete ridges in VEN;pseudocysts and gyriform structures in SK;evenly distributed ring-like structures in VP;vacuolated cells and papillomatous proliferation in VV;and frogspawn-like structures in NS.Conclusion:These 5 verrucous proliferative skin conditions exhibit distinguishable features under both dermoscopy and RCM.The combination of these 2 noninvasive imaging modalities holds significant clinical value for the differential diagnosis of verrucous proliferative skin diseases.展开更多
Developing in situ spectroelectrochemistry methods,which can provide detailed information about species trans-formation during electrochemical reactions,is very important for studying electrode reaction mechanisms and...Developing in situ spectroelectrochemistry methods,which can provide detailed information about species trans-formation during electrochemical reactions,is very important for studying electrode reaction mechanisms and improving battery performance.Studying real-time changes in the surface of electrode materials during normal operation can be an effective way to assess and optimize the practical performance of electrode materials,thus,in situ and in operando characterization techniques are particularly important.However,batteries are hard to be studied by in situ characterization measurements due to their hermetically sealed shells,and there is still much room for battery characterizations.In this work,a specially designed battery based on the structure of coin cells,whose upper cover was transparent,was constructed.With such a device,acquisition of diffuse reflectance spectra of electrode materials during charging and discharging was realized.This not only provided a simple measurement accessory for diffuse reflectance spectroscopy(DRS),but also complemented in situ characterization techniques for batteries.Taking commonly used cathode materials in lithium-ion batteries(LIBs),including LiFePO_(4)(LFP),NCM811 and LiCoO_(2)(LCO)as examples,we managed tofind out the response relationships of different electrode materials to visible light of different wavelengths under ordinary reflectance illumination conditions.Heterogeneity of different cathode ma-terials on interaction relationships with the lights of different wavelengths was also revealed.This work demonstrated the capability of guiding wavelength selection for different materials and assessing electrochemical performances of in situ diffuse reflectance spectroelectrochemistry.By combining electrochemistry with diffuse reflectance spectroscopy,this work made an effective complementary for spectroelectrochemistry.展开更多
Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due t...Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due to macro-phase separation.In this study,a novel polymer(denoted as PU-PDI)with intrinsic NIR reflective proper⁃ties was synthesized by covalent incorporation of PDI units into polyurethane chains.Its photophysical characteris⁃tics,mechanical property and NIR reflectance property are investigated in detail.The results show that covalent in⁃corporation reduces the severe aggregation of PDI units,thereby endows PU-PDI with excellent mechanical property.The elongation at break of PU-PDI can reach more than 700%,and the breaking strength is 34.11 MPa.Moreover,compared to the blending system,PU-PDI possesses enhanced NIR reflection ability due to the better dispersion of PDI units.展开更多
This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy(PM IRRAS)to provide molecular-level information about the structure,orientation and conformation of...This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy(PM IRRAS)to provide molecular-level information about the structure,orientation and conformation of constituents of thin films at electrode surfaces.PM IRRAS relies on the surface selection rules stating that the p-polarized IR beam is enhanced,while the s-polarized beam is attenuated at the metal surface.The difference between p-and s-polarized beams eliminates the background of the solvent and provides IR spectra at a single electrode potential.In contrast,two other popular in situ IR spectroscopic techniques,namely,subtractively normalized interfacial Fourier transform infrared spectroscopy(SNIFTIRS)and surface-enhanced infrared reflection absorption spectroscopy(SEIRAS),provide potential difference spectra to remove the signal from the bulk solution.In this feature article,we provide a brief tutorial on how to run the PM IRRAS experiment and describe the methods used for background elimination first.The application of the PM IRRAS in the biomimetic research is then illustrated by three examples:construction of a tethered bilayer,reconstitution of colicin into a phospholipid bilayer and determination of the orientation of nucleolipids in a monolayer assembled at a gold electrode surface.Finally,the structural changes of graphene oxide during its electrochemical reduction are described to highlight the promising application of PM IRRAS in materials science.展开更多
The simultaneous transmitting and reflecting reconfigurable intelligent surface(STAR-RIS)can independently adjust surface’s reflection and transmission coefficients so as to enhance space coverage.For a multiple-inpu...The simultaneous transmitting and reflecting reconfigurable intelligent surface(STAR-RIS)can independently adjust surface’s reflection and transmission coefficients so as to enhance space coverage.For a multiple-input multiple-output(MIMO)communication system with a STAR-RIS,a base station(BS),an eavesdropper,and multiple users,the system security rate is studied.A joint design of the power allocation at the transmitter and phase shift matrices for reflection and transmission at the STAR-RIS is conducted,in order to maximize the worst achievable security data rate(ASDR).Since the problem is nonconvex and hence challenging,a particle swarm optimization(PSO)based algorithm is developed to tackle the problem.Both the cases of continuous and discrete phase shift matrices at the STAR-RIS are considered.Simulation results demonstrate the effectiveness of the proposed algorithm and shows the benefits of using STAR-RIS in MIMO mutliuser systems.展开更多
Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under norm...Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under normal temperature and pressure environments are commonly employed;however,in certain configurations,such as at high-altitudes(HAs),the environment may involve low temperature and pressure conditions.The present study develops a theoretical prediction model for the TP path under reduced pressure and temperature conditions,utilizing the image bursts method,reflected polar analysis,and dimensional analysis.The model's accuracy is evaluated through numerical simulations and experimental data.Results indicate that the prediction model effectively evaluates the TP path under diminished temperature and pressure conditions,with most predictions falling within a±15%deviation.It was found that the TP height increases with altitude.As the altitude rises from 0 m to 10,000 m,the average TP height increases by 61.7%,87.9%,109.0%,and 134.3%for the scaled height of burst of 1.5 m,2.0 m,2.5 m,and 3.0 m,respectively.Moreover,the variation in TP height under HA environments closely mirrors that observed under corresponding reduced pressure conditions.In HA environments,only the effect of low-pressure conditions on the TP path needs to be considered,as the environmental lowtemperature has a minimal effect.展开更多
Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials(EMs)due to their obvious catalytic effect on the EMs,especially the uniformly dispersed nanomaterials.H...Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials(EMs)due to their obvious catalytic effect on the EMs,especially the uniformly dispersed nanomaterials.However,few studies have reported the dispersion of nanomaterials.In this study,the dispersity and mixing uniformity of nano-CuCr_(2)O_(4)was evaluated based on the difference of solid UV light absorption between the nano-catalytic materials and EMs.The nano-CuCr_(2)O_(4)/ultrafine AP composites with different dispersity of nano-CuCr_(2)O_(4)were prepared by manual grinding and mechanical grinding with different grinding strength and griding time.And then,the absorbance of different samples at 212 nm was obtained by solid UV testing due to the high repeatability of the absorbance at 210-214 nm for three parallel experiments,and the dispersity of different samples was calculated through the established difference equation.Furthermore,the samples were characterized by XRD,IR,SEM,EDS,DSC and TG-MS,which confirmed that different mixing methods did not change the structure of the samples(XRD and IR),and the mixing uniformity improved with the increase of grinding strength and grinding time(SEM and EDS).The scientificity and feasibility of the difference equation were further verified by DSC.The dispersity of nano-CuCr_(2)O_(4)exhibits a positive intrinsic relationship with its catalytic performance,and the uniformly dispersed nano-CuCr_(2)O_(4)significantly reduces the thermal decomposition temperature of ultrafine AP from 367.7 to 338.8℃.The TG-MS patterns show that the dispersed nano-CuCr_(2)O_(4)advanced the thermal decomposition process of ultrafine AP by about 700 s,especially in the high temperature decomposition stage,and the more concentrated energy release characteristic is beneficial to further enhance the energy performance of AP-based propellants.The above conclusions show that the evaluation method of dispersity based on solid UV curves could provide new ideas for the dispersity characterization of nano-catalytic materials in EMs,which is expected to be widely used in the field of EMs.展开更多
This work introduces a novel method for measuring thin film thickness,employing a multi-wavelength method that significantly reduces the need for broad-spectrum data.Unlike traditional techniques that require sev⁃eral...This work introduces a novel method for measuring thin film thickness,employing a multi-wavelength method that significantly reduces the need for broad-spectrum data.Unlike traditional techniques that require sev⁃eral hundred spectral data points,the multi-wavelength method achieves precise thickness measurements with data from only 10 wavelengths.This innovation not only simplifies the process of spectral measurement analysis but also enables accurate real-time thickness measurement on industrial coating production lines.The method effectively reconstructs and fits the visible spectrum(400-800 nm)using a minimal amount of data,while maintaining measurement error within 7.1%.This advancement lays the foundation for more practical and efficient thin film thickness determination techniques in various industrial applications.展开更多
This paper considers an intelligent reflecting surface(IRS)-assisted multiple-input multiple-output(MIMO)system.To maximize the average achievable rate(AAR)under outdated channel state information(CSI),we propose a tw...This paper considers an intelligent reflecting surface(IRS)-assisted multiple-input multiple-output(MIMO)system.To maximize the average achievable rate(AAR)under outdated channel state information(CSI),we propose a twin-timescale passive beamforming(PBF)and power allocation protocol which can reduce the IRS configuration and training overhead.Specifi-cally,the short-timescale power allocation is designed with the outdated precoder and fixed PBF.A new particle swarm opti-mization(PSO)-based long-timescale PBF optimization is pro-posed,where mini-batch channel samples are utilized to update the fitness function.Finally,simulation results demonstrate the effectiveness of the proposed method.展开更多
遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER(Advanced Space-borne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计)数据,因涵盖波长范围宽[VNIR(Visible and Near In...遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER(Advanced Space-borne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计)数据,因涵盖波长范围宽[VNIR(Visible and Near Infra-red)、SWIR(Short wave-length Infra-red)、TIR(Thermal Infra-red)]、波段多(14个波段)、性价比合理等因素,ASTER数据的研究迅速发展。长久以来,对覆盖区进行蚀变遥感异常信息提取一直是遥感找矿的关注点之一。笔者等利用ASTER数据对浅覆盖区——包古图斑岩铜矿的Ⅱ号、Ⅴ号斑岩体进行蚀变遥感异常提取,提取的蚀变异常与野外地质情况吻合性好。分别提取了光谱特征谱带差异明显的2组蚀变矿物的异常信息:第一组是蒙脱石、埃洛石、伊利石与绢云母;第二组是方解石、黑云母与绿泥石。提出了需要进一步工作的异常靶区。展开更多
The selective catalytic reduction reaction belongs to the gas-solid multiphase reaction, and the adsorption of NH3 and NO on CuO/γ-Al2O3 catalysts plays an important role in the reaction. Performance of the CuO/γ-Al...The selective catalytic reduction reaction belongs to the gas-solid multiphase reaction, and the adsorption of NH3 and NO on CuO/γ-Al2O3 catalysts plays an important role in the reaction. Performance of the CuO/γ-Al2O3 catalysts was explored in a fixed bed adsorption system. The catalysts maintain nearly 100% NO conversion efficiency at 350℃. Comprehensive tests were carried out to study the adsorption behavior of NH3 and NO over the catalysts. The desorption experiments prove that NH3 and NO are adsorbed on CuO/γ-Al2O3 catalysts. The adsorption behaviors of NH3 and NO were also studied with the in-situ diffusion reflectance infrared Fourier transform spectroscopy methods. The results show that NH3 could be strongly adsorbed on the catalysts, resulting in coordinated NH3 and NH4＋. NO adsorption leads to the formation of bridging bidentate nitrate, chelating bidentate nitrate, and chelating nitro. The interaction of NH3 and NO molecules with the Cu2＋ present on the CAl2O3 （100） surface was investigated by using a periodic density functional theory. The results show that the adsorption of all the molecules on the Cu2＋ site is energetically favorable, whereas NO bound is stronger than that of NH3 with the adsorption site, and key information about the structural and energetic properties was also addressed.展开更多
This objective of the study was to develop a model for the determination of N deficiency in cherry trees using a combination of visible near infrared methods and spectro-radiometric measurement.In our experimental des...This objective of the study was to develop a model for the determination of N deficiency in cherry trees using a combination of visible near infrared methods and spectro-radiometric measurement.In our experimental design,cherry seedlings were grown under various N deficiency conditions in nutrient-controlled containers.The reflectance values of plant leaves were measured using a spectro-radiometer.Plant leaves samples were simultaneously collected.Their nutrient contents were determined in the laboratory.Afterwards,we performed a statistical comparison of the reflectance values.Sample analysis results established the significant wavelengths.Moreover,we received accurate regression models for predicting N deficiency in cherry leaves that were grown in nutrient solutions.Next,we verified the model validity by measuring the reflectance of the leaves collected from cherry orchards at various locations using a spectroradiometer.Nutrient deficiencies were calculated using the developed model,and then,the predicted and measured data were compared to evaluate model validity.From these results,we determined the wavelengths that yielded the most accurate results for N prediction,selected from the blue and green regions of the spectrum.We established that for N prediction in cherry trees,the simplest model can be created using 560and 570nm wavelengths.However,the evaluated model can be applicable only under certain conditions.We concluded that in order to develop aprediction method with sufficient application capacity,as well as the ability to assess nutritional and physiological characteristics,the ecology condition of the plant should be properly considered based on the model.展开更多
The 1920’s is an unusual time in American history. Even it is so far away from us , we can still feel it in abundant literary heritage, among which is Great Gatsby, which marks the highest point of Fitzgerald’s ...The 1920’s is an unusual time in American history. Even it is so far away from us , we can still feel it in abundant literary heritage, among which is Great Gatsby, which marks the highest point of Fitzgerald’s artistic achievement. It shows us a vivid picture of the 1920’s with its surface prosperity and underlying sadness. The failure of American dream, the "flapper", the contrast between the rich and the poor and the crisis of value are all reflected in characters and details of this novel.展开更多
With the development of the society, more and more people are realized that it is a fact that the communication between people plays a significant role in their daily work and life. English Public speaking, as one of ...With the development of the society, more and more people are realized that it is a fact that the communication between people plays a significant role in their daily work and life. English Public speaking, as one of the means of communication, also gains the attention of the many universities. The author will reflect some issues which exist in Yunnnan Agricultural University in recent years and raise some measures as well.展开更多
基金supported by the Project of Health Committee of Hunan Province(D202304128868),China.
文摘Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often posing diagnostic challenges.Dermoscopy and reflectance confocal microscopy(RCM)can aid in their differentiation,yet their specific features under these tools have not been systematically described.This study aims to summarize and analyze the dermoscopic and RCM features of VEN,SK,VP,VV,and NS.Methods:A total of 121 patients with histopathologically confirmed verrucous proliferative skin diseases were enrolled.Dermoscopy and RCM imaging was used to observe and analyze the microscopic features of these conditions.Results:Under dermoscopy,the 5 diseases displayed distinct characteristics:VEN typically showed gyriform structures;SK was characterized by gyriform structures,comedo-like openings,and milia-like cysts;VP and VV featured dotted vessels and frogspawn-like structures;NS presented as brownish-yellow globules.RCM revealed shared features such as hyperkeratosis and acanthosis across all 5 diseases.Specific features included gyriform structures and elongated rete ridges in VEN;pseudocysts and gyriform structures in SK;evenly distributed ring-like structures in VP;vacuolated cells and papillomatous proliferation in VV;and frogspawn-like structures in NS.Conclusion:These 5 verrucous proliferative skin conditions exhibit distinguishable features under both dermoscopy and RCM.The combination of these 2 noninvasive imaging modalities holds significant clinical value for the differential diagnosis of verrucous proliferative skin diseases.
基金the financial support from the National Natural Science Foundation of China (No. 21925403)the Excellent Research Program of Nanjing University (Grant No. ZYJH004)。
文摘Developing in situ spectroelectrochemistry methods,which can provide detailed information about species trans-formation during electrochemical reactions,is very important for studying electrode reaction mechanisms and improving battery performance.Studying real-time changes in the surface of electrode materials during normal operation can be an effective way to assess and optimize the practical performance of electrode materials,thus,in situ and in operando characterization techniques are particularly important.However,batteries are hard to be studied by in situ characterization measurements due to their hermetically sealed shells,and there is still much room for battery characterizations.In this work,a specially designed battery based on the structure of coin cells,whose upper cover was transparent,was constructed.With such a device,acquisition of diffuse reflectance spectra of electrode materials during charging and discharging was realized.This not only provided a simple measurement accessory for diffuse reflectance spectroscopy(DRS),but also complemented in situ characterization techniques for batteries.Taking commonly used cathode materials in lithium-ion batteries(LIBs),including LiFePO_(4)(LFP),NCM811 and LiCoO_(2)(LCO)as examples,we managed tofind out the response relationships of different electrode materials to visible light of different wavelengths under ordinary reflectance illumination conditions.Heterogeneity of different cathode ma-terials on interaction relationships with the lights of different wavelengths was also revealed.This work demonstrated the capability of guiding wavelength selection for different materials and assessing electrochemical performances of in situ diffuse reflectance spectroelectrochemistry.By combining electrochemistry with diffuse reflectance spectroscopy,this work made an effective complementary for spectroelectrochemistry.
文摘Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due to macro-phase separation.In this study,a novel polymer(denoted as PU-PDI)with intrinsic NIR reflective proper⁃ties was synthesized by covalent incorporation of PDI units into polyurethane chains.Its photophysical characteris⁃tics,mechanical property and NIR reflectance property are investigated in detail.The results show that covalent in⁃corporation reduces the severe aggregation of PDI units,thereby endows PU-PDI with excellent mechanical property.The elongation at break of PU-PDI can reach more than 700%,and the breaking strength is 34.11 MPa.Moreover,compared to the blending system,PU-PDI possesses enhanced NIR reflection ability due to the better dispersion of PDI units.
基金This research was funded by Discovery Grants from the Natural Sciences and Engineering Research Council of Canada(JL:RGPIN-2022-03958AC:RGPIN-2022-04238).
文摘This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy(PM IRRAS)to provide molecular-level information about the structure,orientation and conformation of constituents of thin films at electrode surfaces.PM IRRAS relies on the surface selection rules stating that the p-polarized IR beam is enhanced,while the s-polarized beam is attenuated at the metal surface.The difference between p-and s-polarized beams eliminates the background of the solvent and provides IR spectra at a single electrode potential.In contrast,two other popular in situ IR spectroscopic techniques,namely,subtractively normalized interfacial Fourier transform infrared spectroscopy(SNIFTIRS)and surface-enhanced infrared reflection absorption spectroscopy(SEIRAS),provide potential difference spectra to remove the signal from the bulk solution.In this feature article,we provide a brief tutorial on how to run the PM IRRAS experiment and describe the methods used for background elimination first.The application of the PM IRRAS in the biomimetic research is then illustrated by three examples:construction of a tethered bilayer,reconstitution of colicin into a phospholipid bilayer and determination of the orientation of nucleolipids in a monolayer assembled at a gold electrode surface.Finally,the structural changes of graphene oxide during its electrochemical reduction are described to highlight the promising application of PM IRRAS in materials science.
文摘The simultaneous transmitting and reflecting reconfigurable intelligent surface(STAR-RIS)can independently adjust surface’s reflection and transmission coefficients so as to enhance space coverage.For a multiple-input multiple-output(MIMO)communication system with a STAR-RIS,a base station(BS),an eavesdropper,and multiple users,the system security rate is studied.A joint design of the power allocation at the transmitter and phase shift matrices for reflection and transmission at the STAR-RIS is conducted,in order to maximize the worst achievable security data rate(ASDR).Since the problem is nonconvex and hence challenging,a particle swarm optimization(PSO)based algorithm is developed to tackle the problem.Both the cases of continuous and discrete phase shift matrices at the STAR-RIS are considered.Simulation results demonstrate the effectiveness of the proposed algorithm and shows the benefits of using STAR-RIS in MIMO mutliuser systems.
基金funding from Anhui Engineering Laboratory of Explosive Materials and Technology Foundation(No.AHBP2022B-04)Natural Science Research Project of Anhui Educational Committee(No.2023AH051221)+1 种基金Anhui Provincial Natural Science Foundation(No.2208085QA26)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology for the project related to this work.
文摘Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under normal temperature and pressure environments are commonly employed;however,in certain configurations,such as at high-altitudes(HAs),the environment may involve low temperature and pressure conditions.The present study develops a theoretical prediction model for the TP path under reduced pressure and temperature conditions,utilizing the image bursts method,reflected polar analysis,and dimensional analysis.The model's accuracy is evaluated through numerical simulations and experimental data.Results indicate that the prediction model effectively evaluates the TP path under diminished temperature and pressure conditions,with most predictions falling within a±15%deviation.It was found that the TP height increases with altitude.As the altitude rises from 0 m to 10,000 m,the average TP height increases by 61.7%,87.9%,109.0%,and 134.3%for the scaled height of burst of 1.5 m,2.0 m,2.5 m,and 3.0 m,respectively.Moreover,the variation in TP height under HA environments closely mirrors that observed under corresponding reduced pressure conditions.In HA environments,only the effect of low-pressure conditions on the TP path needs to be considered,as the environmental lowtemperature has a minimal effect.
基金the National Natural Science Foundation of China(Project Nos.21805139,21905023,12102194,22005144 and 22005145)the Joint Funds of the National Natural Science Foundation of China(Grant No.U2141202)+2 种基金Natural Science Foundation of Jiangsu Province(Grant No.BK20200471)the Fundamental Research Funds for the Central Universities(Grant Nos.30920041106,30921011203)Young Elite Scientists Sponsorship Program by CAST(Program,2021QNRC001).
文摘Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials(EMs)due to their obvious catalytic effect on the EMs,especially the uniformly dispersed nanomaterials.However,few studies have reported the dispersion of nanomaterials.In this study,the dispersity and mixing uniformity of nano-CuCr_(2)O_(4)was evaluated based on the difference of solid UV light absorption between the nano-catalytic materials and EMs.The nano-CuCr_(2)O_(4)/ultrafine AP composites with different dispersity of nano-CuCr_(2)O_(4)were prepared by manual grinding and mechanical grinding with different grinding strength and griding time.And then,the absorbance of different samples at 212 nm was obtained by solid UV testing due to the high repeatability of the absorbance at 210-214 nm for three parallel experiments,and the dispersity of different samples was calculated through the established difference equation.Furthermore,the samples were characterized by XRD,IR,SEM,EDS,DSC and TG-MS,which confirmed that different mixing methods did not change the structure of the samples(XRD and IR),and the mixing uniformity improved with the increase of grinding strength and grinding time(SEM and EDS).The scientificity and feasibility of the difference equation were further verified by DSC.The dispersity of nano-CuCr_(2)O_(4)exhibits a positive intrinsic relationship with its catalytic performance,and the uniformly dispersed nano-CuCr_(2)O_(4)significantly reduces the thermal decomposition temperature of ultrafine AP from 367.7 to 338.8℃.The TG-MS patterns show that the dispersed nano-CuCr_(2)O_(4)advanced the thermal decomposition process of ultrafine AP by about 700 s,especially in the high temperature decomposition stage,and the more concentrated energy release characteristic is beneficial to further enhance the energy performance of AP-based propellants.The above conclusions show that the evaluation method of dispersity based on solid UV curves could provide new ideas for the dispersity characterization of nano-catalytic materials in EMs,which is expected to be widely used in the field of EMs.
基金Supported by National Key R&D Program of China(2021YFA0715500)National Natural Science Foundation of China(NSFC)(12227901)+2 种基金Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB0580000)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Chinese Academy of Sciences President's International Fellowship Initiative(2021PT0007).
文摘This work introduces a novel method for measuring thin film thickness,employing a multi-wavelength method that significantly reduces the need for broad-spectrum data.Unlike traditional techniques that require sev⁃eral hundred spectral data points,the multi-wavelength method achieves precise thickness measurements with data from only 10 wavelengths.This innovation not only simplifies the process of spectral measurement analysis but also enables accurate real-time thickness measurement on industrial coating production lines.The method effectively reconstructs and fits the visible spectrum(400-800 nm)using a minimal amount of data,while maintaining measurement error within 7.1%.This advancement lays the foundation for more practical and efficient thin film thickness determination techniques in various industrial applications.
基金supported by the National Natural Science Foundation of China(62271068)the Beijing Natural Science Foundation(L222046).
文摘This paper considers an intelligent reflecting surface(IRS)-assisted multiple-input multiple-output(MIMO)system.To maximize the average achievable rate(AAR)under outdated channel state information(CSI),we propose a twin-timescale passive beamforming(PBF)and power allocation protocol which can reduce the IRS configuration and training overhead.Specifi-cally,the short-timescale power allocation is designed with the outdated precoder and fixed PBF.A new particle swarm opti-mization(PSO)-based long-timescale PBF optimization is pro-posed,where mini-batch channel samples are utilized to update the fitness function.Finally,simulation results demonstrate the effectiveness of the proposed method.
文摘遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER(Advanced Space-borne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计)数据,因涵盖波长范围宽[VNIR(Visible and Near Infra-red)、SWIR(Short wave-length Infra-red)、TIR(Thermal Infra-red)]、波段多(14个波段)、性价比合理等因素,ASTER数据的研究迅速发展。长久以来,对覆盖区进行蚀变遥感异常信息提取一直是遥感找矿的关注点之一。笔者等利用ASTER数据对浅覆盖区——包古图斑岩铜矿的Ⅱ号、Ⅴ号斑岩体进行蚀变遥感异常提取,提取的蚀变异常与野外地质情况吻合性好。分别提取了光谱特征谱带差异明显的2组蚀变矿物的异常信息:第一组是蒙脱石、埃洛石、伊利石与绢云母;第二组是方解石、黑云母与绿泥石。提出了需要进一步工作的异常靶区。
基金Projects(50806025, 51021065, 50976038) supported by the National Natural Science Foundation of ChinaProject(20100480893) supported by the China Postdoctoral Science FoundationProject(1001022B) supported by the Postdoctoral Research Fund of Jiangsu Province, China
文摘The selective catalytic reduction reaction belongs to the gas-solid multiphase reaction, and the adsorption of NH3 and NO on CuO/γ-Al2O3 catalysts plays an important role in the reaction. Performance of the CuO/γ-Al2O3 catalysts was explored in a fixed bed adsorption system. The catalysts maintain nearly 100% NO conversion efficiency at 350℃. Comprehensive tests were carried out to study the adsorption behavior of NH3 and NO over the catalysts. The desorption experiments prove that NH3 and NO are adsorbed on CuO/γ-Al2O3 catalysts. The adsorption behaviors of NH3 and NO were also studied with the in-situ diffusion reflectance infrared Fourier transform spectroscopy methods. The results show that NH3 could be strongly adsorbed on the catalysts, resulting in coordinated NH3 and NH4＋. NO adsorption leads to the formation of bridging bidentate nitrate, chelating bidentate nitrate, and chelating nitro. The interaction of NH3 and NO molecules with the Cu2＋ present on the CAl2O3 （100） surface was investigated by using a periodic density functional theory. The results show that the adsorption of all the molecules on the Cu2＋ site is energetically favorable, whereas NO bound is stronger than that of NH3 with the adsorption site, and key information about the structural and energetic properties was also addressed.
基金The Scientific and Technical Research Council of Turkey,Agriculture,Forestry&Veterinary Research Grant Committee Project No TOVAG 109O376
文摘This objective of the study was to develop a model for the determination of N deficiency in cherry trees using a combination of visible near infrared methods and spectro-radiometric measurement.In our experimental design,cherry seedlings were grown under various N deficiency conditions in nutrient-controlled containers.The reflectance values of plant leaves were measured using a spectro-radiometer.Plant leaves samples were simultaneously collected.Their nutrient contents were determined in the laboratory.Afterwards,we performed a statistical comparison of the reflectance values.Sample analysis results established the significant wavelengths.Moreover,we received accurate regression models for predicting N deficiency in cherry leaves that were grown in nutrient solutions.Next,we verified the model validity by measuring the reflectance of the leaves collected from cherry orchards at various locations using a spectroradiometer.Nutrient deficiencies were calculated using the developed model,and then,the predicted and measured data were compared to evaluate model validity.From these results,we determined the wavelengths that yielded the most accurate results for N prediction,selected from the blue and green regions of the spectrum.We established that for N prediction in cherry trees,the simplest model can be created using 560and 570nm wavelengths.However,the evaluated model can be applicable only under certain conditions.We concluded that in order to develop aprediction method with sufficient application capacity,as well as the ability to assess nutritional and physiological characteristics,the ecology condition of the plant should be properly considered based on the model.
文摘The 1920’s is an unusual time in American history. Even it is so far away from us , we can still feel it in abundant literary heritage, among which is Great Gatsby, which marks the highest point of Fitzgerald’s artistic achievement. It shows us a vivid picture of the 1920’s with its surface prosperity and underlying sadness. The failure of American dream, the "flapper", the contrast between the rich and the poor and the crisis of value are all reflected in characters and details of this novel.
文摘With the development of the society, more and more people are realized that it is a fact that the communication between people plays a significant role in their daily work and life. English Public speaking, as one of the means of communication, also gains the attention of the many universities. The author will reflect some issues which exist in Yunnnan Agricultural University in recent years and raise some measures as well.
