A new cyclometalated platinum complex containing 2, 5-bis(naphthalene-1-yl)-1,3,4-oxadiazole ligand was synthesized and characterized. The UV-Vis absorptions and photoluminescent properties of the ligand and its plati...A new cyclometalated platinum complex containing 2, 5-bis(naphthalene-1-yl)-1,3,4-oxadiazole ligand was synthesized and characterized. The UV-Vis absorptions and photoluminescent properties of the ligand and its platinum complex were investigated. A characteristic metal-ligand charge transfer absorption peak at 439 nm in the UV spectrum and a strong emission peak at 625 nm in the photoluminescence spectrum were observed for this complex in dichloromethane. Cyclic voltammtry (CV) analysis shows that the EHOMO (energy level of the highest occupied molecular orbital) and ELUMO (energy level of the lowest unoccupied molecular orbital) of the platinum complex are about 、5.69 and 、3.25 eV, respectively, indicating that the oxadiazole-based platinum complex has a potential application in electrophosphorescent devices used as a red-emitting material.展开更多
NiTi shape memory alloy(SMA)with nominal composition of Ni 50.8 at%and Ti 49.2 at%was additively manufactured(AM)by selective laser melting(SLM)and laser directed energy deposition(DED)for a comparison study,with emph...NiTi shape memory alloy(SMA)with nominal composition of Ni 50.8 at%and Ti 49.2 at%was additively manufactured(AM)by selective laser melting(SLM)and laser directed energy deposition(DED)for a comparison study,with emphasis on its phase composition,microstructure,mechanical property and deformation mechanism.The results show that the yield strength and ductility obtained by SLM are 100 MPa and 8%,respectively,which are remarkably different from DED result with 700 MPa and 2%.The load path of SLM sample presents shape memory effect,corresponding to martensite phase detected by XRD;while the load path of DED presents pseudo-elasticity with austenite phase.In SLM sample,fine grain and hole provide a uniform deformation during tensile test,resulting in a better elongation.Furthermore,the nonequilibrium solidification was studied by a temperature field simulation to understand the difference of the two 3D printing methods.Both temperature gradient G and growth rate R determine the microstructure and phase in the SLM sample and DED sample,which leads to similar grain morphologies because of similar G/R.While higher G×R of SLM leads to a finer grain size in SLM sample,providing enough driving force for martensite transition and subsequently changing texture compared to DED sample.展开更多
Xenon atoms were produced in their metastable states 5p^56s[3/2]2 and 5p^56s＇[1/2]0 in a pulsed DC discharge in a beam, and subsequently excited to the even-parity autoionizing Rydberg states 5p^5np＇ [3/2] 1,[1/2] 1...Xenon atoms were produced in their metastable states 5p^56s[3/2]2 and 5p^56s＇[1/2]0 in a pulsed DC discharge in a beam, and subsequently excited to the even-parity autoionizing Rydberg states 5p^5np＇ [3/2] 1,[1/2] 1, and 5p^5nf＇ [5/2] 3 using single photon excitation. The excitation spectra of the even-parity autoionizing resonance series from the metastable 129Xe were obtained by recording the autoionized Xe＋ with time-of-flight ion detection in the photon energy range of 28000-42000 cm-1. A wealth of autoionizing resonances were newly observed, from which more precise and systematic spectroscopic data of the level energies and quantum defects were derived.展开更多
Supercontinuum(SC) generation in a dispersion-shifted fiber(DSF) pumped by a 10 GHz regeneratively mode-locked fiber laser(RMLFL) is presented.Optimization of pump wavelength leads to a 20 dB bandwidth of 58.73 nm,whi...Supercontinuum(SC) generation in a dispersion-shifted fiber(DSF) pumped by a 10 GHz regeneratively mode-locked fiber laser(RMLFL) is presented.Optimization of pump wavelength leads to a 20 dB bandwidth of 58.73 nm,which covers the whole C band and part of L band.Using an angle-tuning thin film filter,multi-wavelength and pico-second pulse trains of low chirp could be chosen from the SC spectrum.Amplified spontaneous emission(ASE) induced degeneration of the achieved pulse trains is observed and discussed.展开更多
Dengue vector is responsible for millions of deaths every year and has caused disastrous impacts on health systems. The continuous use of chemical insecticides, such as carbamates, pyrethroids and organophosphates gen...Dengue vector is responsible for millions of deaths every year and has caused disastrous impacts on health systems. The continuous use of chemical insecticides, such as carbamates, pyrethroids and organophosphates generates resistant populations of the mosquito, therefore, new control methods must be investigated. The joint action of the population and guidelines for preventing the reproduction of the mosquito associated with the use of photoactivatable insecticides can be the alternative for the control of epidemiological outbreaks in affected regions. In this study, the photo-larvicidal activity of Photogem^（PG）, a derivative of hematoporphyrin, was investigated against 2nd-early 3rd instar of Aedes aegypti larvae （Diptera： Culicidae） under different lighting conditions （artificial lighting system and sunlight）. The dynamics of PG accumulation was characterized by CLSM （confocal laser scanning microscopy） and total time PG eliminationin solution was investigated by ultraviolet-visible spectrophotometry. The maximum photo-activity of PG was observed in 0.5 h under sunlight exposure which achieved 100% larval mortality. Fluorescence images showed a uniform distribution of PG along the digestive tract. PG remained stable in the sunlight for 48 h and in an artificial lighting system for longer periods, therefore, it can be used for the control ofAedes aegypti larvae as a new alternative to chemical insecticides. The method is considered environmentally friendly due to its rapid degradation in the presence of light. Further studies are required, so that the potential of the technique can be explored in real breeding places.展开更多
It was adopted that the fluorescence microscope, Gas-Flow Heating/Freezing System, Laser-Raman Spect-roscopy, etc. are the multimedia techniques for analysing fluid inclusions of quartz veins in Budate Group, Hailar B...It was adopted that the fluorescence microscope, Gas-Flow Heating/Freezing System, Laser-Raman Spect-roscopy, etc. are the multimedia techniques for analysing fluid inclusions of quartz veins in Budate Group, Hailar Basin. The results show that fluid inclusions in quartz veins are small(1～5 μm)monophase, two-phase(liquid+vapour)aqueous inclusions; the two-phase aqueous inclusions homogeniese to the liquid phase between 120～180℃, two dominant types for oil inclusions were determined in quartz veins:① the primary inclusions, almostly gas, measurement by Laser-Raman Spectroscopy show that both gas phase are enriched in CH4(94.50%～99.25%)and C6H6(0.75%～2.70%), under these conditions, inclusions may have come from juvenile fliud followingly the quartz veins formation. While the quartz veins exhibiting different striking luminescence has been proved by cathodoluminescence, it would be impossible to come from the deep magmas and strata. ② aqueous, liquid and two-phase(liquid+vapour)oil inclusions, belong to secondary hydrocarbon inclusions. The oil inclusions of this stage represent mainly the large scale of oil accumulation, located within the quartz microfracture.展开更多
Laser spark obtained by using a conical optics is much more appropriate to form conducting channels in atmosphere. Only two types of lasers are actively considered to be used in forming high-conductivity channels in a...Laser spark obtained by using a conical optics is much more appropriate to form conducting channels in atmosphere. Only two types of lasers are actively considered to be used in forming high-conductivity channels in atmosphere, controlled by laser spark： pulsed sub-microsecond gas and chemical lasers （CO2, DF （deuterium fluoride））, short pulse solid-state and UV （ultraviolet） lasers. Main advantage of short pulse lasers is their ability in forming of super long ionized channels with a characteristic diameter of- 100 mm in atmosphere along the beam propagation direction. At estimated electron densities below 1,016 cm3 in these filaments and laser wavelengths in the range of 0.5-1.0 mm, the plasma barely absorbs laser radiation. In this case, the length of the track composed of many filaments is determined by the laser intensity and may reach many kilometers at a femtosecond pulse energy of-100 mJ. However, these lasers could not be used to form high-conductivity long channels in atmosphere. The ohmic resistance of this type a conducting channels turned out to be very high, and the gas in the channels could not be strongly heated （〈 1 J）. An electric breakdown controlled by radiation of femtosecond solid-state laser was implemented in only at a length of 3 m with a voltage of 2 MV across the discharge gap （670 kV/m）. Not so long ago scientific group from P.N. Lebedev physical institute has improved that result, the discharge gap （-1m） had been broken under KrF laser irradiation when switching high-voltage （up to 390 kV/m） electric discharge by 100-ns UV pulses. Our previous result -16 m long conducting channel controlled by a laser spark at the voltage -3 MV was obtained more than 20 years ago in Russia and Japan by using pulsed CO2 laser with energy -0.5 kJ. An average electric field strength was 〈 190 kV/m. It is still too much for efficient applications.展开更多
Bi-Te nanoplates （NPs） grown by a low pressure vapor transport method have been studied by Raman spectroscopy, atomic force microscopy （AFM）, energy- dispersive X-ray spectroscopy （EDS）, and Auger electron spect...Bi-Te nanoplates （NPs） grown by a low pressure vapor transport method have been studied by Raman spectroscopy, atomic force microscopy （AFM）, energy- dispersive X-ray spectroscopy （EDS）, and Auger electron spectroscopy （AES）. We find that the surface of relatively thick （more than tens of nanometers） Bi2Te3 NPs is oxidized in the air and forms a bump under heating with moderate laser power, as revealed by the emergence of Raman lines characteristic of Bi2O3 and TeO2 and characterization by AFM and EDS. Further increase of laser power burns holes on the surface of the NPs. Thin （thicknesses less than 20 nm） NPs with stoichiometry different from Bi2Te3 were also studied. Raman lines from non-stoichiometric NPs are different from those of stoichiometric ones and display characteristic changes with the increase of Bi concentration. Thin NPs with the same thickness but different stoichiometries show different color contrast compared to the substrate in the optical image. This indicates that the optical absorption coefficient in thin Bi-Te NPs strongly depends on their stoichiometry.展开更多
Reversible assembly and disassembly of rodlike large complex micelles have been achieved by applying photoswitching of supramolecular inclusion and exclusion of azobenzene-functionalized hyperbranched polyglycerol and...Reversible assembly and disassembly of rodlike large complex micelles have been achieved by applying photoswitching of supramolecular inclusion and exclusion of azobenzene-functionalized hyperbranched polyglycerol and acyclodextrin as driv ing force, promising a versatile system for selfassembly switched by light. Hydrogennuclear magnetic resonance （H NMR） and Fourier transform infrared （FTIR） spectroscopy were applied to characterize the azobenzenefunctionalized hyperbranched polyglycerol. Atomic force microscopy （AFM）, transmission electron microscopy （TEM） and dynamic laser light scattering （DLS） were employed to investigate and track the morphology of the rodlike large complex micelles before and after irradiation of UV light.展开更多
We report in this work a continuous wave(CW) narrowband 589 nm light generation for the purpose of laser guide assisted adaptive optics.A 39 mm long 1 mm thick periodically poled near stoichiometric LiTaO3 crystal wit...We report in this work a continuous wave(CW) narrowband 589 nm light generation for the purpose of laser guide assisted adaptive optics.A 39 mm long 1 mm thick periodically poled near stoichiometric LiTaO3 crystal with duty cycle near 50% was fabricated using electrical poling at room temperature and pumped by a Raman fiber amplifier.We tested two temperature control ovens,and a maximum conversion efficiency of about 14.3%,corresponding to 4 W of yellow light with 28 W of fundamental power,and bandwidth less than 0.18 GHz was achieved.展开更多
基金Project(50473046) supported by the National Natural Science Foundation of ChinaProject(204097) supported by the Science Foundation of the Ministry of Education of China+1 种基金Project(04JJ1002) supported by the Outstanding Youth Foundation of Hunan Province,ChinaProject(06JJ2008) supported by the Natural Science Foundation of Hunan Province,China
文摘A new cyclometalated platinum complex containing 2, 5-bis(naphthalene-1-yl)-1,3,4-oxadiazole ligand was synthesized and characterized. The UV-Vis absorptions and photoluminescent properties of the ligand and its platinum complex were investigated. A characteristic metal-ligand charge transfer absorption peak at 439 nm in the UV spectrum and a strong emission peak at 625 nm in the photoluminescence spectrum were observed for this complex in dichloromethane. Cyclic voltammtry (CV) analysis shows that the EHOMO (energy level of the highest occupied molecular orbital) and ELUMO (energy level of the lowest unoccupied molecular orbital) of the platinum complex are about 、5.69 and 、3.25 eV, respectively, indicating that the oxadiazole-based platinum complex has a potential application in electrophosphorescent devices used as a red-emitting material.
基金Project(2020JJ2046)supported by the Science Fund for Hunan Distinguished Young Scholars,ChinaProject(S2020GXKJGG0416)supported by the Special Project for Hunan Innovative Province Construction,China+1 种基金Project(2018RS3007)supported by the Huxiang Young Talents,ChinaProject(GuikeAB19050002)supported by the Science Project of Guangxi,China。
文摘NiTi shape memory alloy(SMA)with nominal composition of Ni 50.8 at%and Ti 49.2 at%was additively manufactured(AM)by selective laser melting(SLM)and laser directed energy deposition(DED)for a comparison study,with emphasis on its phase composition,microstructure,mechanical property and deformation mechanism.The results show that the yield strength and ductility obtained by SLM are 100 MPa and 8%,respectively,which are remarkably different from DED result with 700 MPa and 2%.The load path of SLM sample presents shape memory effect,corresponding to martensite phase detected by XRD;while the load path of DED presents pseudo-elasticity with austenite phase.In SLM sample,fine grain and hole provide a uniform deformation during tensile test,resulting in a better elongation.Furthermore,the nonequilibrium solidification was studied by a temperature field simulation to understand the difference of the two 3D printing methods.Both temperature gradient G and growth rate R determine the microstructure and phase in the SLM sample and DED sample,which leads to similar grain morphologies because of similar G/R.While higher G×R of SLM leads to a finer grain size in SLM sample,providing enough driving force for martensite transition and subsequently changing texture compared to DED sample.
基金This work was supported by the National Natural Science Foundation of China （No.20673107）, the Chinese National Key Basic Research Special Foundation （No.2007CB815203）, and the Chinese Academy of Science （No.KJCX2-SW-H08）.
文摘Xenon atoms were produced in their metastable states 5p^56s[3/2]2 and 5p^56s＇[1/2]0 in a pulsed DC discharge in a beam, and subsequently excited to the even-parity autoionizing Rydberg states 5p^5np＇ [3/2] 1,[1/2] 1, and 5p^5nf＇ [5/2] 3 using single photon excitation. The excitation spectra of the even-parity autoionizing resonance series from the metastable 129Xe were obtained by recording the autoionized Xe＋ with time-of-flight ion detection in the photon energy range of 28000-42000 cm-1. A wealth of autoionizing resonances were newly observed, from which more precise and systematic spectroscopic data of the level energies and quantum defects were derived.
基金Supperted by National Natural Science Foundation of China(No.60477022)
文摘Supercontinuum(SC) generation in a dispersion-shifted fiber(DSF) pumped by a 10 GHz regeneratively mode-locked fiber laser(RMLFL) is presented.Optimization of pump wavelength leads to a 20 dB bandwidth of 58.73 nm,which covers the whole C band and part of L band.Using an angle-tuning thin film filter,multi-wavelength and pico-second pulse trains of low chirp could be chosen from the SC spectrum.Amplified spontaneous emission(ASE) induced degeneration of the achieved pulse trains is observed and discussed.
文摘Dengue vector is responsible for millions of deaths every year and has caused disastrous impacts on health systems. The continuous use of chemical insecticides, such as carbamates, pyrethroids and organophosphates generates resistant populations of the mosquito, therefore, new control methods must be investigated. The joint action of the population and guidelines for preventing the reproduction of the mosquito associated with the use of photoactivatable insecticides can be the alternative for the control of epidemiological outbreaks in affected regions. In this study, the photo-larvicidal activity of Photogem^（PG）, a derivative of hematoporphyrin, was investigated against 2nd-early 3rd instar of Aedes aegypti larvae （Diptera： Culicidae） under different lighting conditions （artificial lighting system and sunlight）. The dynamics of PG accumulation was characterized by CLSM （confocal laser scanning microscopy） and total time PG eliminationin solution was investigated by ultraviolet-visible spectrophotometry. The maximum photo-activity of PG was observed in 0.5 h under sunlight exposure which achieved 100% larval mortality. Fluorescence images showed a uniform distribution of PG along the digestive tract. PG remained stable in the sunlight for 48 h and in an artificial lighting system for longer periods, therefore, it can be used for the control ofAedes aegypti larvae as a new alternative to chemical insecticides. The method is considered environmentally friendly due to its rapid degradation in the presence of light. Further studies are required, so that the potential of the technique can be explored in real breeding places.
基金Supported by the National Natural Science Foundation of China(Grant No. 40372060)
文摘It was adopted that the fluorescence microscope, Gas-Flow Heating/Freezing System, Laser-Raman Spect-roscopy, etc. are the multimedia techniques for analysing fluid inclusions of quartz veins in Budate Group, Hailar Basin. The results show that fluid inclusions in quartz veins are small(1～5 μm)monophase, two-phase(liquid+vapour)aqueous inclusions; the two-phase aqueous inclusions homogeniese to the liquid phase between 120～180℃, two dominant types for oil inclusions were determined in quartz veins:① the primary inclusions, almostly gas, measurement by Laser-Raman Spectroscopy show that both gas phase are enriched in CH4(94.50%～99.25%)and C6H6(0.75%～2.70%), under these conditions, inclusions may have come from juvenile fliud followingly the quartz veins formation. While the quartz veins exhibiting different striking luminescence has been proved by cathodoluminescence, it would be impossible to come from the deep magmas and strata. ② aqueous, liquid and two-phase(liquid+vapour)oil inclusions, belong to secondary hydrocarbon inclusions. The oil inclusions of this stage represent mainly the large scale of oil accumulation, located within the quartz microfracture.
文摘Laser spark obtained by using a conical optics is much more appropriate to form conducting channels in atmosphere. Only two types of lasers are actively considered to be used in forming high-conductivity channels in atmosphere, controlled by laser spark： pulsed sub-microsecond gas and chemical lasers （CO2, DF （deuterium fluoride））, short pulse solid-state and UV （ultraviolet） lasers. Main advantage of short pulse lasers is their ability in forming of super long ionized channels with a characteristic diameter of- 100 mm in atmosphere along the beam propagation direction. At estimated electron densities below 1,016 cm3 in these filaments and laser wavelengths in the range of 0.5-1.0 mm, the plasma barely absorbs laser radiation. In this case, the length of the track composed of many filaments is determined by the laser intensity and may reach many kilometers at a femtosecond pulse energy of-100 mJ. However, these lasers could not be used to form high-conductivity long channels in atmosphere. The ohmic resistance of this type a conducting channels turned out to be very high, and the gas in the channels could not be strongly heated （〈 1 J）. An electric breakdown controlled by radiation of femtosecond solid-state laser was implemented in only at a length of 3 m with a voltage of 2 MV across the discharge gap （670 kV/m）. Not so long ago scientific group from P.N. Lebedev physical institute has improved that result, the discharge gap （-1m） had been broken under KrF laser irradiation when switching high-voltage （up to 390 kV/m） electric discharge by 100-ns UV pulses. Our previous result -16 m long conducting channel controlled by a laser spark at the voltage -3 MV was obtained more than 20 years ago in Russia and Japan by using pulsed CO2 laser with energy -0.5 kJ. An average electric field strength was 〈 190 kV/m. It is still too much for efficient applications.
文摘Bi-Te nanoplates （NPs） grown by a low pressure vapor transport method have been studied by Raman spectroscopy, atomic force microscopy （AFM）, energy- dispersive X-ray spectroscopy （EDS）, and Auger electron spectroscopy （AES）. We find that the surface of relatively thick （more than tens of nanometers） Bi2Te3 NPs is oxidized in the air and forms a bump under heating with moderate laser power, as revealed by the emergence of Raman lines characteristic of Bi2O3 and TeO2 and characterization by AFM and EDS. Further increase of laser power burns holes on the surface of the NPs. Thin （thicknesses less than 20 nm） NPs with stoichiometry different from Bi2Te3 were also studied. Raman lines from non-stoichiometric NPs are different from those of stoichiometric ones and display characteristic changes with the increase of Bi concentration. Thin NPs with the same thickness but different stoichiometries show different color contrast compared to the substrate in the optical image. This indicates that the optical absorption coefficient in thin Bi-Te NPs strongly depends on their stoichiometry.
基金supported by the National Natural Science Foundation of China (20974093)the National Basic Research Program of China (973 Program, 2007CB936004)+3 种基金Qianjiang Talent Foundation of Zhejiang Province (2010R10021)the Fundamental Research Funds for the Central Universities (2009QNA4040)Zhejiang Provincial Natural Science Foundation of China (R4110175)Research Fund for the Doctoral Program of Higher Education of China ( 20100101110049)
文摘Reversible assembly and disassembly of rodlike large complex micelles have been achieved by applying photoswitching of supramolecular inclusion and exclusion of azobenzene-functionalized hyperbranched polyglycerol and acyclodextrin as driv ing force, promising a versatile system for selfassembly switched by light. Hydrogennuclear magnetic resonance （H NMR） and Fourier transform infrared （FTIR） spectroscopy were applied to characterize the azobenzenefunctionalized hyperbranched polyglycerol. Atomic force microscopy （AFM）, transmission electron microscopy （TEM） and dynamic laser light scattering （DLS） were employed to investigate and track the morphology of the rodlike large complex micelles before and after irradiation of UV light.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11004025,11174046,11104131)
文摘We report in this work a continuous wave(CW) narrowband 589 nm light generation for the purpose of laser guide assisted adaptive optics.A 39 mm long 1 mm thick periodically poled near stoichiometric LiTaO3 crystal with duty cycle near 50% was fabricated using electrical poling at room temperature and pumped by a Raman fiber amplifier.We tested two temperature control ovens,and a maximum conversion efficiency of about 14.3%,corresponding to 4 W of yellow light with 28 W of fundamental power,and bandwidth less than 0.18 GHz was achieved.
