Surface potential decay of polymers for electrical insulation can help to determine the dark conductivity for spacecraft charging analysis. Due to the existence of radiation-induced conductivity, it decays fast in the...Surface potential decay of polymers for electrical insulation can help to determine the dark conductivity for spacecraft charging analysis. Due to the existence of radiation-induced conductivity, it decays fast in the first few hours after irradiation and exponentially slowly for the remaining time. The measurement of dark conductivity with this method usually takes the slow part and needs a couple of days. Integrating the Fowler formula into the deep dielectric charging equations, we obtain a new expression for the fast decay part. The experimental data of different materials, dose rates and temperatures are fitted by the new expression. Both the dark conductivity and the radiation-induced conductivity are derived and compared with other methods. The result shows a good estimation of dark conductivity and radiation-induced conductivity in high-resistivity polymers, which enables a fast measurement of dielectric conductivity within about 600 rain after irradiation.展开更多
Method of VSC (Voltage Shorted Compaction)can be used to determine the intrinsic temperature dependence ofconductivity ofpolycrystalline compaction. The experimental conditions and technical key for preparation of VSC...Method of VSC (Voltage Shorted Compaction)can be used to determine the intrinsic temperature dependence ofconductivity ofpolycrystalline compaction. The experimental conditions and technical key for preparation of VSC device and its physical model as well as its applications in conducting polymers are discussed in detail.展开更多
Some new complexes RE2(EDODA)3·3H2O, where RE = La, Nd, Eu, Gd, Tb, Er, Yb, Lu and Y, EDODA = ethylene-1,2-dioxydiacetate, have been synthesized and characterized by elemental analysis, molar conductance, IR...Some new complexes RE2(EDODA)3·3H2O, where RE = La, Nd, Eu, Gd, Tb, Er, Yb, Lu and Y, EDODA = ethylene-1,2-dioxydiacetate, have been synthesized and characterized by elemental analysis, molar conductance, IR spectra, UV spectra, TG-DTA, 1H NMR and 13C NMR spectra. Various analyses indicate that the complexes are of nine-coordinated binuclear structure. The carboxylates are bidentate ligands and the ether oxygen atoms also coordinate to rare earth ions. Three water molecules are crystalline water. In addition, the influence of concentration on the chemical shift has been studied through the 1H NMR spectra of the complex Lu2(EDODA)3·3H2O in different concentrations.展开更多
The optical, electrical and chemical properties of the gold nanospheres synthesized by different gold concentrations in deionized water through a simple chemical reduction method (Turkevich method) were studied. They ...The optical, electrical and chemical properties of the gold nanospheres synthesized by different gold concentrations in deionized water through a simple chemical reduction method (Turkevich method) were studied. They were dependent on the variation of the gold salt concentration. The peaks of the surface Plasmon resonance (SPR) absorption band and their wavelengths were detected by a UV-visible spectrophotometer. The diameters of the spherical gold nanoparticles were measured theoretically using UV-visible absorption spectrum analysis of the synthesized gold nanoparticles in colloidal form by calculating the ratio of the absorbance at the surface Plasmon resonance (SPR) peak to the absorbance at the lowest peak closed to SPR peak. The values of the gold nanoparticles diameters were (23 nm) and decreased to (13 nm) as the function of molarity changed in the range (0.1 - 0.3 mM). They were compared with the results of the transmission electron microscopy (TEM), which was about (15 - 20 nm) measured by the reference images of Sigma-Aldrich values. The conductivity measurements showed increasing the conductivity with molarity increased. The total dissolved solids (TDS) exhibited increase by linear relation with molarity increasing. The pH-value of the gold nanoparticles solutions varied with the molarity and recorded a bowing value of pH-value at (0.2 mM).展开更多
Spiropyran derivatives are prototype mechanophores with a promising application as molecular sensors because of their changeable structure under external force stimuli.However,the chemical structure evolution under ex...Spiropyran derivatives are prototype mechanophores with a promising application as molecular sensors because of their changeable structure under external force stimuli.However,the chemical structure evolution under external stimuli remains unclear due to the uncertainty and difficulty in distinguishing the structures of different ring-opened merocyanine isomers generated in the force-induced reaction.Here we identify the structure of isomers produced by the force-induced reaction of spiropyran derivatives using a single-molecule conductance measurement and an unsupervised clustering algorithm.We found that the original data from the single-molecule conductance measurement can be divided into four clusters through unsupervised clustering.By introducing a photoinduced reaction and theoretical calculation,we identified and attributed the four clusters of data to the multiple states of the molecular junctions.Our work demonstrates that a single-molecule break junction measurement can distinguish the isomers in the force-induced reaction,suggesting the great potential of single-molecule conductance measurement and unsupervised clustering approaches for structural analysis.展开更多
The audiometric zero level of air conduction for 100 healthy youths was determinedover a froequency range from 20 Hz to 10 KHz in 1971--1973 under the laboratory conditions.The results obtained have been further verif...The audiometric zero level of air conduction for 100 healthy youths was determinedover a froequency range from 20 Hz to 10 KHz in 1971--1973 under the laboratory conditions.The results obtained have been further verified recently on a selected group of 12 persons.This paper also presents the transfer experiments from the original earphone TDH-39(MX-41/AR) to six other types of earphones. The deviation of our data thus obtained from therecommendation by ISO is discussed.展开更多
Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have b...Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have been considered promising,the experimental strategies remain a challenge due to the Brownian motions and weak optical gradient forces with significantly reduced molecular polarizability.Herein,we address direct trapping and in situ sensing of single molecules with unprecedented size,down to∼5Åin solution,by employing an adjustable plasmonic optical nanogap and single-molecule conductance measurement.The theoretical simulations demonstrate that local fields with a high enhancement factor,over 103,were generated at such small nanogaps,resulting in optical forces as large as several piconewtons to suppress the Brownian motion and trap a molecule of length sub-1 nm.This work demonstrates a strategy for directly manipulating the small molecule units,promising a vast multitude of applications in chemical,biological,and materials sciences at the single-molecule level.展开更多
This paper reviews the geometric resistivity correction factor of the 4-point probe DC electrical conduc- tivity measurement method using several geometrical samples. During the review of the literature, only the arti...This paper reviews the geometric resistivity correction factor of the 4-point probe DC electrical conduc- tivity measurement method using several geometrical samples. During the review of the literature, only the articles that include the effect of geometry on resistivity calculation were considered. Combinations of equations used for various geometries were also given. Mathematical equations were given in the text without details. Expressions for the most commonly used geometries were presented in a table for easy reference.展开更多
基金Supported by the Fundamental Research Funds for the Central Universities in Nanjing University of Aeronautics and Astronautics under Grant No NS2014089
文摘Surface potential decay of polymers for electrical insulation can help to determine the dark conductivity for spacecraft charging analysis. Due to the existence of radiation-induced conductivity, it decays fast in the first few hours after irradiation and exponentially slowly for the remaining time. The measurement of dark conductivity with this method usually takes the slow part and needs a couple of days. Integrating the Fowler formula into the deep dielectric charging equations, we obtain a new expression for the fast decay part. The experimental data of different materials, dose rates and temperatures are fitted by the new expression. Both the dark conductivity and the radiation-induced conductivity are derived and compared with other methods. The result shows a good estimation of dark conductivity and radiation-induced conductivity in high-resistivity polymers, which enables a fast measurement of dielectric conductivity within about 600 rain after irradiation.
文摘Method of VSC (Voltage Shorted Compaction)can be used to determine the intrinsic temperature dependence ofconductivity ofpolycrystalline compaction. The experimental conditions and technical key for preparation of VSC device and its physical model as well as its applications in conducting polymers are discussed in detail.
文摘Some new complexes RE2(EDODA)3·3H2O, where RE = La, Nd, Eu, Gd, Tb, Er, Yb, Lu and Y, EDODA = ethylene-1,2-dioxydiacetate, have been synthesized and characterized by elemental analysis, molar conductance, IR spectra, UV spectra, TG-DTA, 1H NMR and 13C NMR spectra. Various analyses indicate that the complexes are of nine-coordinated binuclear structure. The carboxylates are bidentate ligands and the ether oxygen atoms also coordinate to rare earth ions. Three water molecules are crystalline water. In addition, the influence of concentration on the chemical shift has been studied through the 1H NMR spectra of the complex Lu2(EDODA)3·3H2O in different concentrations.
文摘The optical, electrical and chemical properties of the gold nanospheres synthesized by different gold concentrations in deionized water through a simple chemical reduction method (Turkevich method) were studied. They were dependent on the variation of the gold salt concentration. The peaks of the surface Plasmon resonance (SPR) absorption band and their wavelengths were detected by a UV-visible spectrophotometer. The diameters of the spherical gold nanoparticles were measured theoretically using UV-visible absorption spectrum analysis of the synthesized gold nanoparticles in colloidal form by calculating the ratio of the absorbance at the surface Plasmon resonance (SPR) peak to the absorbance at the lowest peak closed to SPR peak. The values of the gold nanoparticles diameters were (23 nm) and decreased to (13 nm) as the function of molarity changed in the range (0.1 - 0.3 mM). They were compared with the results of the transmission electron microscopy (TEM), which was about (15 - 20 nm) measured by the reference images of Sigma-Aldrich values. The conductivity measurements showed increasing the conductivity with molarity increased. The total dissolved solids (TDS) exhibited increase by linear relation with molarity increasing. The pH-value of the gold nanoparticles solutions varied with the molarity and recorded a bowing value of pH-value at (0.2 mM).
基金supported by the National Natural Science Foundation of China(grant nos.22173075,21933012,61901402,31871877,and 21774106)the National Key R&D Program of China(grant no.2017YFA0204902)+1 种基金the Fundamental Research Funds for the Central Universities(grant nos.20720200068 and 20720190002)the Natural Science Foundation of Fujian Province(grant no.2018J06004).
文摘Spiropyran derivatives are prototype mechanophores with a promising application as molecular sensors because of their changeable structure under external force stimuli.However,the chemical structure evolution under external stimuli remains unclear due to the uncertainty and difficulty in distinguishing the structures of different ring-opened merocyanine isomers generated in the force-induced reaction.Here we identify the structure of isomers produced by the force-induced reaction of spiropyran derivatives using a single-molecule conductance measurement and an unsupervised clustering algorithm.We found that the original data from the single-molecule conductance measurement can be divided into four clusters through unsupervised clustering.By introducing a photoinduced reaction and theoretical calculation,we identified and attributed the four clusters of data to the multiple states of the molecular junctions.Our work demonstrates that a single-molecule break junction measurement can distinguish the isomers in the force-induced reaction,suggesting the great potential of single-molecule conductance measurement and unsupervised clustering approaches for structural analysis.
文摘The audiometric zero level of air conduction for 100 healthy youths was determinedover a froequency range from 20 Hz to 10 KHz in 1971--1973 under the laboratory conditions.The results obtained have been further verified recently on a selected group of 12 persons.This paper also presents the transfer experiments from the original earphone TDH-39(MX-41/AR) to six other types of earphones. The deviation of our data thus obtained from therecommendation by ISO is discussed.
基金supported by the National Natural Science Foundation of China(grant nos.T2222002,21973079,22032004,92161118,12174324,21991130,and 21905238)the Ministry of Science and Technology of the People’s Republic of China(grant no.2021YFA1201502)the Natural Science Foundation of Fujian Province(grant no.2021J06008).
文摘Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have been considered promising,the experimental strategies remain a challenge due to the Brownian motions and weak optical gradient forces with significantly reduced molecular polarizability.Herein,we address direct trapping and in situ sensing of single molecules with unprecedented size,down to∼5Åin solution,by employing an adjustable plasmonic optical nanogap and single-molecule conductance measurement.The theoretical simulations demonstrate that local fields with a high enhancement factor,over 103,were generated at such small nanogaps,resulting in optical forces as large as several piconewtons to suppress the Brownian motion and trap a molecule of length sub-1 nm.This work demonstrates a strategy for directly manipulating the small molecule units,promising a vast multitude of applications in chemical,biological,and materials sciences at the single-molecule level.
文摘This paper reviews the geometric resistivity correction factor of the 4-point probe DC electrical conduc- tivity measurement method using several geometrical samples. During the review of the literature, only the articles that include the effect of geometry on resistivity calculation were considered. Combinations of equations used for various geometries were also given. Mathematical equations were given in the text without details. Expressions for the most commonly used geometries were presented in a table for easy reference.