A polymerized lyotropic liquid crystal monomer of sodium 3,4,5-tris(11-acryloxyundecyloxy)- benzoate was synthesized by a convenient route starting from 3,4,5-trihydroxybenzoic acid via esterification followed by et...A polymerized lyotropic liquid crystal monomer of sodium 3,4,5-tris(11-acryloxyundecyloxy)- benzoate was synthesized by a convenient route starting from 3,4,5-trihydroxybenzoic acid via esterification followed by etherification, acylation and finally neutralization. The chemi- cal structure was confirmed by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance spectral analysis. The self-organization behavior of the monomer with deionized water in methanol at room temperature was also demonstrated. The assemblies were char- acterized by polarized optical microscope and X-ray diffraction. The results show that a solution containing 80:20 of the monomer to water was found to be able to self-organize into Lamellar (La) phase and 92:8 with inverted hexagonal (H]I) phase, which was in ac- cordance with the theoretical calculation of critical packing parameter. It suggests that the concentration of the monomer was the key factor to influence assembly structure. Addi- tionally, the acrylate conversion with different photoinitiators and nanostructure retention after polymerization were investigated. The research shows that the acrylate conversion of the monomer with Darocur2959 could reach up to 78% when irradiated by 30 mW/cm2 UV light of 365 nm for 30 min characterized by Real-time FT-IR as well as the sol-gel method. Meanwhile, the La and HII phase nanostructures were both retained after polymerization.展开更多
In this paper the conception of smart materials and structures is firstly combined with research of air bag,and the main theory of self adapting cushioning of intelligent air bag is expatiated.The intelligent venting...In this paper the conception of smart materials and structures is firstly combined with research of air bag,and the main theory of self adapting cushioning of intelligent air bag is expatiated.The intelligent venting structure is the main part affecting the cushioning result.Electrostrictive material was found having big force,high response speed and wide linearity,and it is fit to utilize in intelligent venting structure. The characteristic of the dynamic response and cushioning actuating of an electrostrictive stack actuator is analyzed,and the result of the computer simulation of the fuzzy control to intelligent venting structure is given.It is concluded that intelligent venting structure has good actuating characteristic and can satisfy the need of intelligent air bag.展开更多
In order to compensate for the limitation of conventional XY table used in semiconductor integrated circuits(IC) packaging and improve its speed and accuracy, a voice coil actuator (VCA) direct-drive high-speed and pr...In order to compensate for the limitation of conventional XY table used in semiconductor integrated circuits(IC) packaging and improve its speed and accuracy, a voice coil actuator (VCA) direct-drive high-speed and precision positioning XY table used in wire bonder was proposed. Also, a novel flexible decoupling mechanism was used in the positioning table, and the small moving mass enabled the positioning table to move at high speed and precision. XY table deformation interference caused by assembly error and instant interference generated by dynamic load moving with high speed and acceleration can be eliminated through the flexible decoupling mechanism. Considering the positioning table as lumped mass spring system,the dynamic equations of the mechanical system and the VCA were built according to the Newton mechanics principle and electromagnetic theory. Then the electromechanical coupling control model of the system was created through Laplace transform. Based on displacement PID controller, the loop-locked controlling algorithm of the positioning system was investigated. The dynamic control algorithm effectively improved the system dynamic performance. The precision test of the prototype machine was carried out, and the results validated the correctness of the model and the theory. Compared with traditional XY table, the table has higher speed, acceleration and positioning accuracy.展开更多
The luminous efficiency of organic light-emitting devices depends on the recombination probability of electrons injected at the cathode and holes at the anode. A theoretical model to calculate the distribution of curr...The luminous efficiency of organic light-emitting devices depends on the recombination probability of electrons injected at the cathode and holes at the anode. A theoretical model to calculate the distribution of current densities and the recombination rate in organic single layer devices is presented taking into account the charge injection process at each electrode, charge transport and recombination in organic layer. The calculated results indicate that efficient single-layer devices are possible by adjusting the barrier heights at two electrodes and the carrier mobilities. Lowering the barrier heights can improve the electroluminescent(EL) efficiency pronouncedly in many cases, and efficient devices are still possible using an ohmic contact to inject the low mobility carrier, and a contact limited contact to inject the high mobility carrier. All in all, high EL efficiency needs to consider sufficient recombination, enough injected carriers and well transport.展开更多
In this paper, the organic quantum well devices,which are similar to the type-Ⅱ quantum well of inorganic semiconductor, have been fabricated, in which the NPB (N,N’-Di-[(1-naphthalenyl)-N,N’-diphenyl]-(1,1’-biphe...In this paper, the organic quantum well devices,which are similar to the type-Ⅱ quantum well of inorganic semiconductor, have been fabricated, in which the NPB (N,N’-Di-[(1-naphthalenyl)-N,N’-diphenyl]-(1,1’-biphenyl)-4,4’-diamine) and Alq3 (Tris-(8-quinolinolato)aluminum) act as the potential barrier layer and the potential well layer, respectively. In the electroluminescence, the blue shift of spectrum with the decreasing of well width is observed for the device with different well width, and this is interpreted by combination of quantum size effect and exciton confinement effect. The blue shift of spectrum with increasing applied voltage is observed for the same device, and this is interpreted in terms of polarization effect and quantum size effect.展开更多
As the increasing number of the individuals suffering from AIDs,chemotherapy,and radiotherapy,pathogenic fungi,which may rapidly grow and invade the host tissues in these immune-compromised patients,is becoming great ...As the increasing number of the individuals suffering from AIDs,chemotherapy,and radiotherapy,pathogenic fungi,which may rapidly grow and invade the host tissues in these immune-compromised patients,is becoming great threat to human health.In this study,we constructed a novel fungal pathogen-responsive assembly of cuprous oxide(Cu_(2)O)nanoparticles(NPs)for specific targeting and inhibiting growth and biofilm formation of the representative fungal pathogen,Candida albicans(C.albicans).This assembly was formed by coating the initial Cu_(2)O NPs with both phosphatidylethanolamine(PE)and bovine serum albumin(BSA),followed by hydrophobic/electrostatic interaction-driven formation of the Cu_(2)O-PE-BSA microaggregates.The formed microaggregates could be induced for disassembly by the fungal pathogen C.albicans,leading to close binding of the NPs to the cell wall of the pathogen.Both confocal microscopy and viability assays showed that the assembly strongly inhibited growth and biofilm formation of the pathogen,but had extreme low toxicity to mammalian cells.In vivo mouse wound model further revealed that the assembly had high capacity of healing the fungus-infected wounds and reduced the fungal burden of the wound tissues.This study sheds a novel light on facile development of pathogen-responsive nano-assemblies for efficient and safe antifungal therapy.展开更多
Luminescent carbon nanoparticles (CNPs) are newcomers to the world of nanomaterials and have shown great impact in health and environmental applications as well as being promising building blocks for future nanodevi...Luminescent carbon nanoparticles (CNPs) are newcomers to the world of nanomaterials and have shown great impact in health and environmental applications as well as being promising building blocks for future nanodevices because of their fascinating photoluminescence and potential to serve as nontoxic replacements for traditional heavy-metals-based quantum dots. Herein, fluorescent CNPs have been prepared from candle soot by re fluxing with HNO3 and subsequently separated by a single centrifugation. The CNPs can be represented by the empirical formula C1Ho.677Oo.586No.o15Nao.069, and have a size of 20-100 nm, height of 3.0 nm, lifetime of 7.31 ns + 0.06 ns and quantum yield of -1.7%. Further studies demonstrate that: (1)the as-prepared CNPs exhibit excellent stability in biological media and their luminescence intensity does not change with ionic strength or pH in the physiological and pathological range of pH 4.5-8.8; (2) CNPs can act as electron donors and transporters and porphyrin can assemble onto CNPs through electrostatic and ^-stacking interactions to form porphyrin-CNPs supramolecular composites; (3)CNPs have strong intrinsic peroxidase-like activity. Based on this intrinsic peroxidase activity, a simple, cheap, and highly selective and sensitive colorimetric and quantitative assay has been developed for the detection of glucose levels. This assay has been used to analyze real samples, such as diluted blood and fruit juice.展开更多
Carbon nanotubes(CNTs)were grown into anodic aluminum oxide(AAO)channels by chemical vapor deposition(CVD)using C2H2/N2mixtures as feeding gas,which can be used as field emitters.The bottom surface of AAO template was...Carbon nanotubes(CNTs)were grown into anodic aluminum oxide(AAO)channels by chemical vapor deposition(CVD)using C2H2/N2mixtures as feeding gas,which can be used as field emitters.The bottom surface of AAO template was etched slightly and the tips of CNTs were explored as the field emission arrays which were uniform and vertical.Field emission characterization showed a low turn-on field about 3.25 V/m and high emission current about 30 mA/cm2with the electric field about 4 V/m.These superior field emission characteristics could be attributed to low density of vertical CNTs and higher conductivity of the substrate.展开更多
文摘A polymerized lyotropic liquid crystal monomer of sodium 3,4,5-tris(11-acryloxyundecyloxy)- benzoate was synthesized by a convenient route starting from 3,4,5-trihydroxybenzoic acid via esterification followed by etherification, acylation and finally neutralization. The chemi- cal structure was confirmed by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance spectral analysis. The self-organization behavior of the monomer with deionized water in methanol at room temperature was also demonstrated. The assemblies were char- acterized by polarized optical microscope and X-ray diffraction. The results show that a solution containing 80:20 of the monomer to water was found to be able to self-organize into Lamellar (La) phase and 92:8 with inverted hexagonal (H]I) phase, which was in ac- cordance with the theoretical calculation of critical packing parameter. It suggests that the concentration of the monomer was the key factor to influence assembly structure. Addi- tionally, the acrylate conversion with different photoinitiators and nanostructure retention after polymerization were investigated. The research shows that the acrylate conversion of the monomer with Darocur2959 could reach up to 78% when irradiated by 30 mW/cm2 UV light of 365 nm for 30 min characterized by Real-time FT-IR as well as the sol-gel method. Meanwhile, the La and HII phase nanostructures were both retained after polymerization.
文摘In this paper the conception of smart materials and structures is firstly combined with research of air bag,and the main theory of self adapting cushioning of intelligent air bag is expatiated.The intelligent venting structure is the main part affecting the cushioning result.Electrostrictive material was found having big force,high response speed and wide linearity,and it is fit to utilize in intelligent venting structure. The characteristic of the dynamic response and cushioning actuating of an electrostrictive stack actuator is analyzed,and the result of the computer simulation of the fuzzy control to intelligent venting structure is given.It is concluded that intelligent venting structure has good actuating characteristic and can satisfy the need of intelligent air bag.
基金Supported by National Natural Science Foundation of China (No50505032)
文摘In order to compensate for the limitation of conventional XY table used in semiconductor integrated circuits(IC) packaging and improve its speed and accuracy, a voice coil actuator (VCA) direct-drive high-speed and precision positioning XY table used in wire bonder was proposed. Also, a novel flexible decoupling mechanism was used in the positioning table, and the small moving mass enabled the positioning table to move at high speed and precision. XY table deformation interference caused by assembly error and instant interference generated by dynamic load moving with high speed and acceleration can be eliminated through the flexible decoupling mechanism. Considering the positioning table as lumped mass spring system,the dynamic equations of the mechanical system and the VCA were built according to the Newton mechanics principle and electromagnetic theory. Then the electromechanical coupling control model of the system was created through Laplace transform. Based on displacement PID controller, the loop-locked controlling algorithm of the positioning system was investigated. The dynamic control algorithm effectively improved the system dynamic performance. The precision test of the prototype machine was carried out, and the results validated the correctness of the model and the theory. Compared with traditional XY table, the table has higher speed, acceleration and positioning accuracy.
基金Excellent Youth Foundation of Hunan Province(03JJY1008) Science Foundation for Post-doctorate of China(2004035083) Science Foundation of Central South University( 0601059)
文摘The luminous efficiency of organic light-emitting devices depends on the recombination probability of electrons injected at the cathode and holes at the anode. A theoretical model to calculate the distribution of current densities and the recombination rate in organic single layer devices is presented taking into account the charge injection process at each electrode, charge transport and recombination in organic layer. The calculated results indicate that efficient single-layer devices are possible by adjusting the barrier heights at two electrodes and the carrier mobilities. Lowering the barrier heights can improve the electroluminescent(EL) efficiency pronouncedly in many cases, and efficient devices are still possible using an ohmic contact to inject the low mobility carrier, and a contact limited contact to inject the high mobility carrier. All in all, high EL efficiency needs to consider sufficient recombination, enough injected carriers and well transport.
基金the National Nature Science Foundation ofChina (60576016,10374001), the National Key Basic Research Spe-cial Foundation of China (2003CB314707),The National High Tech-nology Research and Development Program of China(2006AA0380412),the Beijing City Natural Science Foundation(2073030), the Key Item of National Nature Science Foundation ofChina (10434030),and the Excellent Doctor’s Science and Technol-ogy Innovation Foundation of Beijing Jiaotong University(48010).
文摘In this paper, the organic quantum well devices,which are similar to the type-Ⅱ quantum well of inorganic semiconductor, have been fabricated, in which the NPB (N,N’-Di-[(1-naphthalenyl)-N,N’-diphenyl]-(1,1’-biphenyl)-4,4’-diamine) and Alq3 (Tris-(8-quinolinolato)aluminum) act as the potential barrier layer and the potential well layer, respectively. In the electroluminescence, the blue shift of spectrum with the decreasing of well width is observed for the device with different well width, and this is interpreted by combination of quantum size effect and exciton confinement effect. The blue shift of spectrum with increasing applied voltage is observed for the same device, and this is interpreted in terms of polarization effect and quantum size effect.
基金the National Natural Science Foundation of China(31870139 and 81873961)the Natural Science Foundation of Tianjin(19JCZDJC33800)+1 种基金the National Training Program of Innovation and Entrepreneurship for Undergraduates(201810055105)the Fundamental Research for the Central Universities。
文摘As the increasing number of the individuals suffering from AIDs,chemotherapy,and radiotherapy,pathogenic fungi,which may rapidly grow and invade the host tissues in these immune-compromised patients,is becoming great threat to human health.In this study,we constructed a novel fungal pathogen-responsive assembly of cuprous oxide(Cu_(2)O)nanoparticles(NPs)for specific targeting and inhibiting growth and biofilm formation of the representative fungal pathogen,Candida albicans(C.albicans).This assembly was formed by coating the initial Cu_(2)O NPs with both phosphatidylethanolamine(PE)and bovine serum albumin(BSA),followed by hydrophobic/electrostatic interaction-driven formation of the Cu_(2)O-PE-BSA microaggregates.The formed microaggregates could be induced for disassembly by the fungal pathogen C.albicans,leading to close binding of the NPs to the cell wall of the pathogen.Both confocal microscopy and viability assays showed that the assembly strongly inhibited growth and biofilm formation of the pathogen,but had extreme low toxicity to mammalian cells.In vivo mouse wound model further revealed that the assembly had high capacity of healing the fungus-infected wounds and reduced the fungal burden of the wound tissues.This study sheds a novel light on facile development of pathogen-responsive nano-assemblies for efficient and safe antifungal therapy.
基金This project was supported by the 973 Project (No. 2011CB936004), the National Natural Science Foundation of China (NSFC) (Nos. 20831003, 90813001, 20833006, and 90913007) and Funds from the Chinese Academy of Sciences.
文摘Luminescent carbon nanoparticles (CNPs) are newcomers to the world of nanomaterials and have shown great impact in health and environmental applications as well as being promising building blocks for future nanodevices because of their fascinating photoluminescence and potential to serve as nontoxic replacements for traditional heavy-metals-based quantum dots. Herein, fluorescent CNPs have been prepared from candle soot by re fluxing with HNO3 and subsequently separated by a single centrifugation. The CNPs can be represented by the empirical formula C1Ho.677Oo.586No.o15Nao.069, and have a size of 20-100 nm, height of 3.0 nm, lifetime of 7.31 ns + 0.06 ns and quantum yield of -1.7%. Further studies demonstrate that: (1)the as-prepared CNPs exhibit excellent stability in biological media and their luminescence intensity does not change with ionic strength or pH in the physiological and pathological range of pH 4.5-8.8; (2) CNPs can act as electron donors and transporters and porphyrin can assemble onto CNPs through electrostatic and ^-stacking interactions to form porphyrin-CNPs supramolecular composites; (3)CNPs have strong intrinsic peroxidase-like activity. Based on this intrinsic peroxidase activity, a simple, cheap, and highly selective and sensitive colorimetric and quantitative assay has been developed for the detection of glucose levels. This assay has been used to analyze real samples, such as diluted blood and fruit juice.
基金supported by China National Funds for Distinguished Young Scientists(Grant No.61125101)the Science and Technology on Vacuum&Cryogenics Technology and Physics Laboratory
文摘Carbon nanotubes(CNTs)were grown into anodic aluminum oxide(AAO)channels by chemical vapor deposition(CVD)using C2H2/N2mixtures as feeding gas,which can be used as field emitters.The bottom surface of AAO template was etched slightly and the tips of CNTs were explored as the field emission arrays which were uniform and vertical.Field emission characterization showed a low turn-on field about 3.25 V/m and high emission current about 30 mA/cm2with the electric field about 4 V/m.These superior field emission characteristics could be attributed to low density of vertical CNTs and higher conductivity of the substrate.