K-shell ionization for Li-like uranium ions in collisions with a N2 target was performed at the ESR storage ring. We found surprisingly that in such close encounters the 2 s electron remain almost unaffected by the co...K-shell ionization for Li-like uranium ions in collisions with a N2 target was performed at the ESR storage ring. We found surprisingly that in such close encounters the 2 s electron remain almost unaffected by the collisions. A dedicated experimental study was conducted by using Li-like uranium ions at an initial energy of 378 MeV/u in order to manifest the situation. In Fig.1 a typical spectrum is shown registered by a Ge(i)展开更多
An exhaustive structural analysis was carried out on three Indian coals （ranging from sub-bituminous to high volatile bituminous coal） using a range of advanced characterization tools. Detailed investigations were c...An exhaustive structural analysis was carried out on three Indian coals （ranging from sub-bituminous to high volatile bituminous coal） using a range of advanced characterization tools. Detailed investigations were carded out using UV-Visible spectroscopy, X-ray diffraction, scanning electron microscopy coupled energy dispersive spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy. The X-ray and Raman peaks were deconvoluted and analyzed in details. Coal crystallites possess turbostratic structure, whose crystallite diameter and height increase with rank. The tJdC ratio plotted against aromaticity exhibited a decreasing trend, confirming the graphitization of coal upon leaching. It is also found that, with the increase of coal rank, the dependency of I20/I26 on La is saturated, due to the increase in average size of sp2 nanoclusters. In Raman spectra, the observed G peak （1585 cm^-1） and the D2 band arises from graphitic lattices. In IR spectrum, two distinct peaks at 2850 and 2920 cm i are attributed to the symmetric and asymmetric -CH2 stretching vibrations. The intense peak at - 1620 cm^-1, is either attributed to the aromatic ring stretching of C=C nucleus.展开更多
Dragline,framework and cocoon silk fibers of Araneus Ventricosus were used for this study.To investigate the microstructure mechanisms of stress-strain behavior of spider silk,firstly,amino acid compositions were anal...Dragline,framework and cocoon silk fibers of Araneus Ventricosus were used for this study.To investigate the microstructure mechanisms of stress-strain behavior of spider silk,firstly,amino acid compositions were analyzed and molecular conformations and crystallinity were measured with Raman spectra and X-ray diffraction respectively.The results showed that there were more amino acids with large side groups and polar ones in spider silk than those of Bombyx silk,and the amino acid distribution varied with different spider silk.The molecular structures were mainly α-helix and β-sheet,and random coil and β-turn existed as well.The proportions and arrangement of these conformations of dragline silk were different from framework and cocoon silk fibers.Microstructure was one of important factors of excellent mechanical properties of spider silk.Crystallinity of spider silk was very low,which implied that the roles of crystal on spider silk were not as great as other protein fibers.展开更多
Defects in Sb implanted Zn O single crystals have been studied by using photoluminescence(PL) spectroscopy,X-ray diffraction(XRD) and Raman scattering.Electrical properties of the samples were analyzed by Hall effect ...Defects in Sb implanted Zn O single crystals have been studied by using photoluminescence(PL) spectroscopy,X-ray diffraction(XRD) and Raman scattering.Electrical properties of the samples were analyzed by Hall effect measurement.The results indicate that the annealed Sb-implanted sample is n-type with a free electron concentration of the same amplitude as the calculated implantation concentration.The well-known oxygen vacancy related deep level green PL band is suppressed in the as-implanted sample and recovers to the level close to the as-grown Zn O single crystal after annealing.These phenomena suggest that a large portion of as-implanted Sb atoms occupy oxygen lattice site in an unstable state and move to the interstitial site,forming the complex donor defect upon high temperature annealing,resulting in n-type conduction even if the implantation dose is quite high.展开更多
One polythiophene derivative PT3T and two low band gap copolymers,PBTT-T3T and PBTT,with different ratios of 5,6-dini-trobenzothiadiazole as the acceptor unit in the polymer backbone have been synthesized by Pd-cataly...One polythiophene derivative PT3T and two low band gap copolymers,PBTT-T3T and PBTT,with different ratios of 5,6-dini-trobenzothiadiazole as the acceptor unit in the polymer backbone have been synthesized by Pd-catalyzed Stille-coupling polymerizations.Thermal stability,X-ray diffraction analyses,UV-vis absorption spectra,photoluminescence spectra and electrochemical properties of the copolymers were investigated.The band gap estimated from UV-vis-NIR spectra of the copolymers films varied from 1.39 to 1.94 eV.Among these copolymers,the films of PBTT-T3T and PBTT,which contain the 5,6-dinitrobenzothiadiazole unit,cover a broad wavelength range in the visible and near-infrared region from 400 to 1000 nm with the maximal peak absorption around 700 nm,which is exactly matched with the maximum in the photon flux of the sun.展开更多
Nano CuO/ZSM-5 zeolite was prepared and used as a catalyst for dehydration of 1,4-butanediol(BDO) to tetrahydrofuran(THF) in liquid-phase. It was found that the 4.6 wt% CuO/ZSM-5 displayed good catalytic performance, ...Nano CuO/ZSM-5 zeolite was prepared and used as a catalyst for dehydration of 1,4-butanediol(BDO) to tetrahydrofuran(THF) in liquid-phase. It was found that the 4.6 wt% CuO/ZSM-5 displayed good catalytic performance, and nearly 100%of BDO conversion and more than 99% of THF selectivity could be achieved by a rotary evaporator reactor at 170 °C under the atmospheric pressure. With such mild reaction conditions, 2400 g BDO could be converted to THF over 1 g catalyst under semi-continuous operation. Characterizations with X-ray diffraction(XRD), temperature-programmed reduction(TPR),NH3-temperature programmed desorption(TPD), X-ray photoelectron spectroscopy(XPS), transmission electron microscope(TEM) and Brunauer-Emmett-Teller(BET) over fresh and used 4.6 wt% CuO/ZSM-5 were conducted. Based on the results of the characterization and catalytic performance of 4.6 wt% CuO/ZSM-5, it can be conjectured that the formed 1–3 nm CuO nanoparticles, suitable acidity of the catalyst due to the synergic interaction of CuO and ZSM-5 support promoted the dehydration of BDO to THF.展开更多
文摘K-shell ionization for Li-like uranium ions in collisions with a N2 target was performed at the ESR storage ring. We found surprisingly that in such close encounters the 2 s electron remain almost unaffected by the collisions. A dedicated experimental study was conducted by using Li-like uranium ions at an initial energy of 378 MeV/u in order to manifest the situation. In Fig.1 a typical spectrum is shown registered by a Ge(i)
文摘An exhaustive structural analysis was carried out on three Indian coals （ranging from sub-bituminous to high volatile bituminous coal） using a range of advanced characterization tools. Detailed investigations were carded out using UV-Visible spectroscopy, X-ray diffraction, scanning electron microscopy coupled energy dispersive spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy. The X-ray and Raman peaks were deconvoluted and analyzed in details. Coal crystallites possess turbostratic structure, whose crystallite diameter and height increase with rank. The tJdC ratio plotted against aromaticity exhibited a decreasing trend, confirming the graphitization of coal upon leaching. It is also found that, with the increase of coal rank, the dependency of I20/I26 on La is saturated, due to the increase in average size of sp2 nanoclusters. In Raman spectra, the observed G peak （1585 cm^-1） and the D2 band arises from graphitic lattices. In IR spectrum, two distinct peaks at 2850 and 2920 cm i are attributed to the symmetric and asymmetric -CH2 stretching vibrations. The intense peak at - 1620 cm^-1, is either attributed to the aromatic ring stretching of C=C nucleus.
文摘Dragline,framework and cocoon silk fibers of Araneus Ventricosus were used for this study.To investigate the microstructure mechanisms of stress-strain behavior of spider silk,firstly,amino acid compositions were analyzed and molecular conformations and crystallinity were measured with Raman spectra and X-ray diffraction respectively.The results showed that there were more amino acids with large side groups and polar ones in spider silk than those of Bombyx silk,and the amino acid distribution varied with different spider silk.The molecular structures were mainly α-helix and β-sheet,and random coil and β-turn existed as well.The proportions and arrangement of these conformations of dragline silk were different from framework and cocoon silk fibers.Microstructure was one of important factors of excellent mechanical properties of spider silk.Crystallinity of spider silk was very low,which implied that the roles of crystal on spider silk were not as great as other protein fibers.
基金supported by the National Natural Science Foundation of China(Grant No.61474104)
文摘Defects in Sb implanted Zn O single crystals have been studied by using photoluminescence(PL) spectroscopy,X-ray diffraction(XRD) and Raman scattering.Electrical properties of the samples were analyzed by Hall effect measurement.The results indicate that the annealed Sb-implanted sample is n-type with a free electron concentration of the same amplitude as the calculated implantation concentration.The well-known oxygen vacancy related deep level green PL band is suppressed in the as-implanted sample and recovers to the level close to the as-grown Zn O single crystal after annealing.These phenomena suggest that a large portion of as-implanted Sb atoms occupy oxygen lattice site in an unstable state and move to the interstitial site,forming the complex donor defect upon high temperature annealing,resulting in n-type conduction even if the implantation dose is quite high.
基金support from the National Natural Science Foundation of China (50933003 & 50903044)MOST of China (2009AA032304)
文摘One polythiophene derivative PT3T and two low band gap copolymers,PBTT-T3T and PBTT,with different ratios of 5,6-dini-trobenzothiadiazole as the acceptor unit in the polymer backbone have been synthesized by Pd-catalyzed Stille-coupling polymerizations.Thermal stability,X-ray diffraction analyses,UV-vis absorption spectra,photoluminescence spectra and electrochemical properties of the copolymers were investigated.The band gap estimated from UV-vis-NIR spectra of the copolymers films varied from 1.39 to 1.94 eV.Among these copolymers,the films of PBTT-T3T and PBTT,which contain the 5,6-dinitrobenzothiadiazole unit,cover a broad wavelength range in the visible and near-infrared region from 400 to 1000 nm with the maximal peak absorption around 700 nm,which is exactly matched with the maximum in the photon flux of the sun.
基金supported by the National Natural Science Foundation of China(21173240)
文摘Nano CuO/ZSM-5 zeolite was prepared and used as a catalyst for dehydration of 1,4-butanediol(BDO) to tetrahydrofuran(THF) in liquid-phase. It was found that the 4.6 wt% CuO/ZSM-5 displayed good catalytic performance, and nearly 100%of BDO conversion and more than 99% of THF selectivity could be achieved by a rotary evaporator reactor at 170 °C under the atmospheric pressure. With such mild reaction conditions, 2400 g BDO could be converted to THF over 1 g catalyst under semi-continuous operation. Characterizations with X-ray diffraction(XRD), temperature-programmed reduction(TPR),NH3-temperature programmed desorption(TPD), X-ray photoelectron spectroscopy(XPS), transmission electron microscope(TEM) and Brunauer-Emmett-Teller(BET) over fresh and used 4.6 wt% CuO/ZSM-5 were conducted. Based on the results of the characterization and catalytic performance of 4.6 wt% CuO/ZSM-5, it can be conjectured that the formed 1–3 nm CuO nanoparticles, suitable acidity of the catalyst due to the synergic interaction of CuO and ZSM-5 support promoted the dehydration of BDO to THF.
