Mesoporous CeO2 particles with high surface area were synthesized using a modified evaporation-induced self assembly(EISA) method which combined citric acid as complexing agent.As-prepared powder and further thermal t...Mesoporous CeO2 particles with high surface area were synthesized using a modified evaporation-induced self assembly(EISA) method which combined citric acid as complexing agent.As-prepared powder and further thermal treatment samples were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),selected area electron diffraction(SAED),Fourier transform infrared spectrometer(FTIR),thermogravimetry and differential thermal analysis(TG-DTA),Brunauer-Emmett-Teller(BET) and Barrett-Joyner-Ha...展开更多
Equal-channel angular pressing （ECAP） process was applied to a 12 mm ×12 mm ×80 mm billet of pure copper （99.98 wt.%） at room temperature. The shear deformation characteristics, microstructure evolution,...Equal-channel angular pressing （ECAP） process was applied to a 12 mm ×12 mm ×80 mm billet of pure copper （99.98 wt.%） at room temperature. The shear deformation characteristics, microstructure evolution, and tensile properties were investigated. A combination of high strength （-420 MPa） and high elongation to failure （-25%） was achieved after eight ECAP passes at room temperature. The mixing of ultrafme grains （-0.2 μm） with nanocrystalline grains （-80 nm） resulted in high tensile strength and ductility.展开更多
An experiment was carried out to investigate the variations in metal uptake and translocation among 19 wetland plant species in small-scale plots of constructed wetland using artificial wastewater containing 2.0 mg L^...An experiment was carried out to investigate the variations in metal uptake and translocation among 19 wetland plant species in small-scale plots of constructed wetland using artificial wastewater containing 2.0 mg L^-1 copper （Cu）, 1.0 mg L^-1 chromium （Cr）, and 2.0 mg L^-1 nickel （Ni）. More than 97% of Cu, Cr, and Ni were removed from the wastewater by the wetland plant species. There were more than ]00-fold differences in the metal accumulation and more than ten-fold differences in the metal concentrations among the 19 plant species. These plants accumulated as high as 8.8% of Cu, 20.5% of Cr, and 14.4% of Ni when they were grown in the wetland soaked with the wastewater. Several plant species were found to be highly capable of accumulating one, two or all the three metals. The results indicated considerable variations in the metal removal abilities through phytoextraction among the 19 wetland plant species. It can be concluded that the selection of appropriate plant species in constructed wetland can be crucial for the improvement of metal removal efficiency of the wetland system.展开更多
The dynamics of transportation,accumulation,disappearance and distribution of 60Co in a simulated aquatic-terrestrial ecosystem was studied by isotope-tracer technique. In the aquatic system,60Co was transported and t...The dynamics of transportation,accumulation,disappearance and distribution of 60Co in a simulated aquatic-terrestrial ecosystem was studied by isotope-tracer technique. In the aquatic system,60Co was transported and transformed via depositing,coupling with ions and adsorption. The absorption resulted in the redistribution and accumulation of 60Co in each compartment of the system. Specific activities of 60Co in water started sharply and gently decreased. The sediment accumulated a large amount of 60Co by adsorption and ion exchange. The hornwort (Ceralophyllum demersum) could also adsorb a large amount of 60Co in a short time,because of its large specific surface area. Fish (Carassius auratus) and snail (Bellamya purificata) had a poor capacity of adsorbing 60Co. The distribution of 60Co in the fish was mainly in the viscera,and the amount of 60Co in the snail flesh was greater than that in the shell. The amount of 60Co in individual compartment in the system was changed with time. The highest specific activity of 60Co in the bean of the terrestrial system remained in the root nodule.展开更多
In order to understand the mechanisms on the variation between rice cultivars in Cd uptake and accumulation, two pot soil experiments were conducted with typical rice cultivars that varied greatly in soil Cd uptake. T...In order to understand the mechanisms on the variation between rice cultivars in Cd uptake and accumulation, two pot soil experiments were conducted with typical rice cultivars that varied greatly in soil Cd uptake. The experiments with six rice cultivars showed that the root oxidation abilities of rice differed with rice cultivars and also with types of the cultivars, the cultivars with indica consanguinity were significantly higher than the cultivars with japonica consanguinity. Root oxidation abilities of the rice cultivars correlated positively and significantly （P〈0.01） with their Cd concentrations and Cd quantity accumulations in rice plants. The experiments with two rice cultivars showed that significant differences also existed between the two cultivars in pot soil redox potentials, which of Shan you 63 （higher soil Cd accumulator） were significantly higher than that of Wu yun jing 7 （lower soil Cd accumulator） under different soil Cd levels, but the degrees of the differences varied with soil Cd levels. The differences were larger under soil Cd treatments than the control. The results indicate that root oxidation ability, especially in Cd contaminated soil, is one of the main mechanisms which dominate Cd uptake and accumulation by rice plant.展开更多
A new method for constructing the Wronskian entries is proposed and applied to the differential-difference Kadomtsev-Petviashvilli （DΔKP） equation. The generalized Wronskian solutions to it are obtained, including ...A new method for constructing the Wronskian entries is proposed and applied to the differential-difference Kadomtsev-Petviashvilli （DΔKP） equation. The generalized Wronskian solutions to it are obtained, including rational solutions and Matveev solutions.展开更多
K4Ce2Nb10O30 ultrafine powders were prepared by stearic acid method (SAM). The obtained products were analyzed by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning ele...K4Ce2Nb10O30 ultrafine powders were prepared by stearic acid method (SAM). The obtained products were analyzed by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning electron microscopy and UV-visible absorption spectra. XRD patterns revealed that K4Ce2Nb10O30 powders treated at 900 oC for 2 h presented tetragonal structure without the presence of deleterious phases. Furthermore, the K4Ce2Nb10O30 prepared by SAM had considerable activity under visible light irradiation.展开更多
Gas-liquid contactors equipped with polytetrafluoroethylene （PTFE） or polypropylene （PP） hydrophobic membranes were applied for removal of sulfur dioxide from refinery gas. Pure water, NaOH solution and MDEA were ...Gas-liquid contactors equipped with polytetrafluoroethylene （PTFE） or polypropylene （PP） hydrophobic membranes were applied for removal of sulfur dioxide from refinery gas. Pure water, NaOH solution and MDEA were adopted as the absorbents. The performance of the two kinds of membranes for separation of SO2 was evaluated in terms of the concentration of absorbent solution, the concentration of SO2, and the feed flow rate. The efficiency for removal of SO2 increased with an increasing absorbent concentration. Upon increasing the concentration of SO2 and the feed flow rate, the desulfurization efficiency was decreased.展开更多
We introduce a new model of one-dimensional （1D） photonic crystal composed of alternately arranged RHM and LHM layers with positive and negative refractive indices respectively, for which the transmission spectra of...We introduce a new model of one-dimensional （1D） photonic crystal composed of alternately arranged RHM and LHM layers with positive and negative refractive indices respectively, for which the transmission spectra of the model are calculated numerically with the transfer matrix method, and the bandgap structure and the polarization properties are analyzed. We found that the introduction of negative refractive index layers （i.e. LHM medium layers） gives rise to some peculiar band-gap structure and polarization properties as follows. Firstly, the forbidden bands are extremely wide and the transmission bands are very sharp without oscillation;and secondly, the change of incident angle has different influences on the forbidden bands of TE and TM modes. For the TM mode, the forbidden band width decreases substantially and finally vanishes, and for the TE mode with central wavelength, the total reflection happens at anv incident anale.展开更多
Treating acid gases contained in natural gas by MDEA is used widely. But the efficiency of regeneration of the MDEA solution limited the development of this technology. An optimal temperature is necessary for regenera...Treating acid gases contained in natural gas by MDEA is used widely. But the efficiency of regeneration of the MDEA solution limited the development of this technology. An optimal temperature is necessary for regeneration of the MDEA solution using membrane distillation. The experiment results showed that the regeneration rate of MDEA rose with an increasing temperature. But the rate increased slowly after the regeneration temperature arrived at a certain value. This study can confirm that regeneration of the MDEA solution using membrane distillation is feasible. This technology provides more advantages as compared to conventional regeneration process.展开更多
By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and ...By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expres- sions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.展开更多
The reaction of Ni（CH3COO）2.6H2O, 4-hydroxycinnamic acid （Hhca） and 4,4＇-bipyridine （bipy） ligand in water-solution afforded a mononuclear complex [Ni（H2O）4（4,4＇-bipy）2]（hca）2 which was characterized by ...The reaction of Ni（CH3COO）2.6H2O, 4-hydroxycinnamic acid （Hhca） and 4,4＇-bipyridine （bipy） ligand in water-solution afforded a mononuclear complex [Ni（H2O）4（4,4＇-bipy）2]（hca）2 which was characterized by IR, elemental analysis, TGA and single-crystal X-ray diffraction. X-ray crystallography analysis reveals that the complex is of triclinic, space group PI with a = 7.0238（14）, b = 7.2934（11）, c = 17.186（4） A, α = 87.073（13）, β = 84.354（10）, γ = 81.961（12）°, V= 866.9（3） A^3, Z = 1, Dc = 1.474 g/cm^3, F（000） = 402,μ = 62.7 mm^-1, R = 0.0411, wR = 0.0862 and GOF = 1.048. In solid state, the cation [Ni（H2O）4（4,4＇-bpy）2]^2＋ connects six nearby hca counter anions via O-H…O hydrogen bonds to form an extended 2D lattice framework and the O-…N hydrogen bonds finally link the 2D layers into an infinite 3D network.展开更多
Two novel fluorine-containing cyclophanes 1 and 2 incorporating a 1,4-bismethylfluorophenylene subunits have been synthesized via the template-directed clipping methodology and their structure was characterized by ~1H...Two novel fluorine-containing cyclophanes 1 and 2 incorporating a 1,4-bismethylfluorophenylene subunits have been synthesized via the template-directed clipping methodology and their structure was characterized by ~1H NMR,^(13)C NMR, MALDI-TOF-MS and elemental analysis.X-ray diffraction analysis of the solid state molecular structure showed that the complex units are linked by non-classical C-H…F hydrogen bonding.展开更多
Structural and thermodynamic parameters of 56 oxygen-containing and 56 sulfur- containing organic compounds were computed at the B3LPY/6-311G＊＊ level using density functional theory （DFT） method. Furthermore,the d...Structural and thermodynamic parameters of 56 oxygen-containing and 56 sulfur- containing organic compounds were computed at the B3LPY/6-311G＊＊ level using density functional theory （DFT） method. Furthermore,the dependent equations between the experimental data of boiling points （Tb） and theoretical parameters were proposed with SPSS12.0 for windows software,whose correlation coefficients R2 are 0.933 and 0.945. These dependent equations were validated by cross-validation method （q2 are 0.923 and 0.929,respectively）. VIF （variance inflation factors） and t-value methods were also used to verify the significance and self-correlationship of each variable. Results indicate that our dependent equation exhibits good prediction ability,and molecular polarizability （α） is the main factor affecting the Tb of oxygen- and sulfur-containing organic compounds. To our interest,obvious dependence could also be found among the oxygen- and sulfur-containing organic compounds＇ experimental data of boiling points （Tb） with R^2 of 0.857.展开更多
A novel molecule tetra-N-alkylation of cyclen （1,4,7,10-tetraazacyclododecane）, 1,4,7,10-tetrakis（2-（（4-hydroxy）phenoxy）ethyl）-1,4,7,10-tetraazacyclododecane 2, was synthesized and structurally characterized b...A novel molecule tetra-N-alkylation of cyclen （1,4,7,10-tetraazacyclododecane）, 1,4,7,10-tetrakis（2-（（4-hydroxy）phenoxy）ethyl）-1,4,7,10-tetraazacyclododecane 2, was synthesized and structurally characterized by single-crystal X-ray diffraction. The molecule turned into chiral helical compound crystals grown from EtOH by slow diffusion at room temperature and three of the four hydroquinone groups of the benzene ring formed a g-electron-rich cavity by C-H…π stacking interaction. The crystal belongs to the monoclinic system, space group P21/C with a = 13.9192（9）, b = 13.2871（6）, c = 22.1894（15）A^°, β = 91.4600（10）°, V = 4102.5（4）A^°3, Z = 4, Dc = 1.219 g/cm^3, C40H52N4O8, Mr = 752.89, F（000） = 1616,μ = 0.088 mm^-1, MoKa radiation （λ = 0.71073）, R = 0.0578 and wR = 0.1389 for 5588 observed reflections with I 〉 2σ（I）. Moreover, compound 2 was characterized with ^1H NMR, ^13C NMR, IR spectra and MS.展开更多
Introduction Although devices based on pseudorotaxanes, cantenanes, and rotaxanes are commercialized yet, several researches have been done on the applications of these donor-acceptor molecules. A promising area is t...Introduction Although devices based on pseudorotaxanes, cantenanes, and rotaxanes are commercialized yet, several researches have been done on the applications of these donor-acceptor molecules. A promising area is the field of nanotechnology. The miniaturization of semi-conductor technology by the ＂top-down＂ approach is limited by the wavelength of the radiation used in the lithography to prepare electronic components. Therefore, the ＂bottom-up＂ may be more suitable to create devices with sizes down to the molecular level. A molecular or supramolecular system, in which the relative position of the component parts can be altered by an external stimulus, a molecular switch, can act as the basic unit for the creation of new molecular devices .展开更多
Nano-sized CeO_2 powders were synthesized by homogeneous precipitation method in alcohol-water solution with HMT as precipitator and the nano-particles were characterized by TEM and BET. The process parameters which i...Nano-sized CeO_2 powders were synthesized by homogeneous precipitation method in alcohol-water solution with HMT as precipitator and the nano-particles were characterized by TEM and BET. The process parameters which influenced the sizes and agglomeration of nanometer CeO_2 powders were studied and the influence mechanism was discussed. The results show that the average size of the particles prepared by the above method with the best process parameters is about 8 nm, and the particles are of smaller size and better dispersion than those obtained from the ordinary powders synthesized by homogeneous precipitation in water solution.展开更多
In this letter,the effects of Bragg-mirror quasi-periodicity on the shifts and quality factor in defect modes of photonic crystals are studied by using the transfer matrix method.Furthermore the influence of the quasi...In this letter,the effects of Bragg-mirror quasi-periodicity on the shifts and quality factor in defect modes of photonic crystals are studied by using the transfer matrix method.Furthermore the influence of the quasi-periodicity on electric field enhancement effect inside the defect layer is studied,which is similar to that on the quality factor.展开更多
The enhancement effect of the phase-conjugate wave produced by a third order nonlinear optical medium in a （AB）^N （D）^2 （BA）^N Bragg microcavity made of one-dimensional photonic crystals is studied. The gain fac...The enhancement effect of the phase-conjugate wave produced by a third order nonlinear optical medium in a （AB）^N （D）^2 （BA）^N Bragg microcavity made of one-dimensional photonic crystals is studied. The gain factor of the phase-conjugate wave is derived when the resonance condition is satisfied by the incident optical wave and the Bragg microcavity mode. Because of stronger resonance enhancement to incident pump beam given by the Bragg microcavity, the enhancement effect of the phase-conjugate wave produced by a third order nonlinear optical medium inside Bragg microcavity is more outstanding than that caused by the naked third order nonlinear optical medium. The theoretical analysis and the numerical calculation show the Bragg microcavity with larger number N of periods is identical with a Fabry-Perot cavity when the resonance condition is satisfied by the incident optical wave and the Bragg microcavity mode.展开更多
Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)havin...Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)having calcium chloride,in the presence of poly(vinyl pyrrolidone)(PVP)having a viscosity average molecular weight lower than 40 000.It was confirmed that the polycondensation could be accelerated,the inherent viscosity of the polymer could be increased,and the polymers could be fibrillated more easily by the addition of the PVP.FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps.The morphology of the resultant pulps,the effect of viscosity average molecular weight,amount and adding mode of PVP on inherent viscosity,specific surface area,and mean length of the resultant pulps were discussed in detail.And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.展开更多
基金supported by the National Natural Science Foundation of China (20771047)the Natural Science Foundation of Jiangsu Province (BK2008541)+1 种基金Jiangsu Graduate Student Innovation Grant (CX82Z-007Z)Jiangsu University Innovation Grant (1293000425)
文摘Mesoporous CeO2 particles with high surface area were synthesized using a modified evaporation-induced self assembly(EISA) method which combined citric acid as complexing agent.As-prepared powder and further thermal treatment samples were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),selected area electron diffraction(SAED),Fourier transform infrared spectrometer(FTIR),thermogravimetry and differential thermal analysis(TG-DTA),Brunauer-Emmett-Teller(BET) and Barrett-Joyner-Ha...
基金This work is financially supported by the Natural Science Foundation of Jiangsu Province, China (No. BK2001053), the International Cooperation Project Foundation of Jiangsu Province, China (No. BZ2006018), and the Science and Technol-ogy Project Foundation of Changzhou, China (No. CZ2006008).
文摘Equal-channel angular pressing （ECAP） process was applied to a 12 mm ×12 mm ×80 mm billet of pure copper （99.98 wt.%） at room temperature. The shear deformation characteristics, microstructure evolution, and tensile properties were investigated. A combination of high strength （-420 MPa） and high elongation to failure （-25%） was achieved after eight ECAP passes at room temperature. The mixing of ultrafme grains （-0.2 μm） with nanocrystalline grains （-80 nm） resulted in high tensile strength and ductility.
基金Project supported by the Postgraduate Research and Innovation Project of the Universities in Jiangsu Province, China(No. CX08S 018Z)the Jiangsu Provincial Natural Science Foundation of China (No. BK2008144)the Key Projectfor Agricultural Science and Technology of Changzhou, Jiangsu Province, China (No. CE2008211)
文摘An experiment was carried out to investigate the variations in metal uptake and translocation among 19 wetland plant species in small-scale plots of constructed wetland using artificial wastewater containing 2.0 mg L^-1 copper （Cu）, 1.0 mg L^-1 chromium （Cr）, and 2.0 mg L^-1 nickel （Ni）. More than 97% of Cu, Cr, and Ni were removed from the wastewater by the wetland plant species. There were more than ]00-fold differences in the metal accumulation and more than ten-fold differences in the metal concentrations among the 19 plant species. These plants accumulated as high as 8.8% of Cu, 20.5% of Cr, and 14.4% of Ni when they were grown in the wetland soaked with the wastewater. Several plant species were found to be highly capable of accumulating one, two or all the three metals. The results indicated considerable variations in the metal removal abilities through phytoextraction among the 19 wetland plant species. It can be concluded that the selection of appropriate plant species in constructed wetland can be crucial for the improvement of metal removal efficiency of the wetland system.
基金National Natural Science Foundation of China (39570149)
文摘The dynamics of transportation,accumulation,disappearance and distribution of 60Co in a simulated aquatic-terrestrial ecosystem was studied by isotope-tracer technique. In the aquatic system,60Co was transported and transformed via depositing,coupling with ions and adsorption. The absorption resulted in the redistribution and accumulation of 60Co in each compartment of the system. Specific activities of 60Co in water started sharply and gently decreased. The sediment accumulated a large amount of 60Co by adsorption and ion exchange. The hornwort (Ceralophyllum demersum) could also adsorb a large amount of 60Co in a short time,because of its large specific surface area. Fish (Carassius auratus) and snail (Bellamya purificata) had a poor capacity of adsorbing 60Co. The distribution of 60Co in the fish was mainly in the viscera,and the amount of 60Co in the snail flesh was greater than that in the shell. The amount of 60Co in individual compartment in the system was changed with time. The highest specific activity of 60Co in the bean of the terrestrial system remained in the root nodule.
文摘In order to understand the mechanisms on the variation between rice cultivars in Cd uptake and accumulation, two pot soil experiments were conducted with typical rice cultivars that varied greatly in soil Cd uptake. The experiments with six rice cultivars showed that the root oxidation abilities of rice differed with rice cultivars and also with types of the cultivars, the cultivars with indica consanguinity were significantly higher than the cultivars with japonica consanguinity. Root oxidation abilities of the rice cultivars correlated positively and significantly （P〈0.01） with their Cd concentrations and Cd quantity accumulations in rice plants. The experiments with two rice cultivars showed that significant differences also existed between the two cultivars in pot soil redox potentials, which of Shan you 63 （higher soil Cd accumulator） were significantly higher than that of Wu yun jing 7 （lower soil Cd accumulator） under different soil Cd levels, but the degrees of the differences varied with soil Cd levels. The differences were larger under soil Cd treatments than the control. The results indicate that root oxidation ability, especially in Cd contaminated soil, is one of the main mechanisms which dominate Cd uptake and accumulation by rice plant.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10371070 and 10671121 .Acknowledgments The authors exPress their thanks to Prof. D.J. Zhang and Dr. J.B. Bi for their good advices.
文摘A new method for constructing the Wronskian entries is proposed and applied to the differential-difference Kadomtsev-Petviashvilli （DΔKP） equation. The generalized Wronskian solutions to it are obtained, including rational solutions and Matveev solutions.
基金Project supported by the National Natural Science Foundation of China (20872051) "Zijin Star" of NJUST
文摘K4Ce2Nb10O30 ultrafine powders were prepared by stearic acid method (SAM). The obtained products were analyzed by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning electron microscopy and UV-visible absorption spectra. XRD patterns revealed that K4Ce2Nb10O30 powders treated at 900 oC for 2 h presented tetragonal structure without the presence of deleterious phases. Furthermore, the K4Ce2Nb10O30 prepared by SAM had considerable activity under visible light irradiation.
基金supported by the Suzhou Science and Technology Program.
文摘Gas-liquid contactors equipped with polytetrafluoroethylene （PTFE） or polypropylene （PP） hydrophobic membranes were applied for removal of sulfur dioxide from refinery gas. Pure water, NaOH solution and MDEA were adopted as the absorbents. The performance of the two kinds of membranes for separation of SO2 was evaluated in terms of the concentration of absorbent solution, the concentration of SO2, and the feed flow rate. The efficiency for removal of SO2 increased with an increasing absorbent concentration. Upon increasing the concentration of SO2 and the feed flow rate, the desulfurization efficiency was decreased.
文摘We introduce a new model of one-dimensional （1D） photonic crystal composed of alternately arranged RHM and LHM layers with positive and negative refractive indices respectively, for which the transmission spectra of the model are calculated numerically with the transfer matrix method, and the bandgap structure and the polarization properties are analyzed. We found that the introduction of negative refractive index layers （i.e. LHM medium layers） gives rise to some peculiar band-gap structure and polarization properties as follows. Firstly, the forbidden bands are extremely wide and the transmission bands are very sharp without oscillation;and secondly, the change of incident angle has different influences on the forbidden bands of TE and TM modes. For the TM mode, the forbidden band width decreases substantially and finally vanishes, and for the TE mode with central wavelength, the total reflection happens at anv incident anale.
文摘Treating acid gases contained in natural gas by MDEA is used widely. But the efficiency of regeneration of the MDEA solution limited the development of this technology. An optimal temperature is necessary for regeneration of the MDEA solution using membrane distillation. The experiment results showed that the regeneration rate of MDEA rose with an increasing temperature. But the rate increased slowly after the regeneration temperature arrived at a certain value. This study can confirm that regeneration of the MDEA solution using membrane distillation is feasible. This technology provides more advantages as compared to conventional regeneration process.
文摘By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expres- sions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.
基金Supported by the National Natural Science Foundation of China (20571054 and 20476066), the NSF of Jiangsu Province (BK2005031) and Project of High Technology of Jiangsu Province (BG2005021)
文摘The reaction of Ni（CH3COO）2.6H2O, 4-hydroxycinnamic acid （Hhca） and 4,4＇-bipyridine （bipy） ligand in water-solution afforded a mononuclear complex [Ni（H2O）4（4,4＇-bipy）2]（hca）2 which was characterized by IR, elemental analysis, TGA and single-crystal X-ray diffraction. X-ray crystallography analysis reveals that the complex is of triclinic, space group PI with a = 7.0238（14）, b = 7.2934（11）, c = 17.186（4） A, α = 87.073（13）, β = 84.354（10）, γ = 81.961（12）°, V= 866.9（3） A^3, Z = 1, Dc = 1.474 g/cm^3, F（000） = 402,μ = 62.7 mm^-1, R = 0.0411, wR = 0.0862 and GOF = 1.048. In solid state, the cation [Ni（H2O）4（4,4＇-bpy）2]^2＋ connects six nearby hca counter anions via O-H…O hydrogen bonds to form an extended 2D lattice framework and the O-…N hydrogen bonds finally link the 2D layers into an infinite 3D network.
基金support from the National Natural Science Foundation of China(No.20872051)
文摘Two novel fluorine-containing cyclophanes 1 and 2 incorporating a 1,4-bismethylfluorophenylene subunits have been synthesized via the template-directed clipping methodology and their structure was characterized by ~1H NMR,^(13)C NMR, MALDI-TOF-MS and elemental analysis.X-ray diffraction analysis of the solid state molecular structure showed that the complex units are linked by non-classical C-H…F hydrogen bonding.
基金Supported by the State Science Foundation of China (No. 20737001)
文摘Structural and thermodynamic parameters of 56 oxygen-containing and 56 sulfur- containing organic compounds were computed at the B3LPY/6-311G＊＊ level using density functional theory （DFT） method. Furthermore,the dependent equations between the experimental data of boiling points （Tb） and theoretical parameters were proposed with SPSS12.0 for windows software,whose correlation coefficients R2 are 0.933 and 0.945. These dependent equations were validated by cross-validation method （q2 are 0.923 and 0.929,respectively）. VIF （variance inflation factors） and t-value methods were also used to verify the significance and self-correlationship of each variable. Results indicate that our dependent equation exhibits good prediction ability,and molecular polarizability （α） is the main factor affecting the Tb of oxygen- and sulfur-containing organic compounds. To our interest,obvious dependence could also be found among the oxygen- and sulfur-containing organic compounds＇ experimental data of boiling points （Tb） with R^2 of 0.857.
基金supported by the National Natural Science Foundation of China (20872051)
文摘A novel molecule tetra-N-alkylation of cyclen （1,4,7,10-tetraazacyclododecane）, 1,4,7,10-tetrakis（2-（（4-hydroxy）phenoxy）ethyl）-1,4,7,10-tetraazacyclododecane 2, was synthesized and structurally characterized by single-crystal X-ray diffraction. The molecule turned into chiral helical compound crystals grown from EtOH by slow diffusion at room temperature and three of the four hydroquinone groups of the benzene ring formed a g-electron-rich cavity by C-H…π stacking interaction. The crystal belongs to the monoclinic system, space group P21/C with a = 13.9192（9）, b = 13.2871（6）, c = 22.1894（15）A^°, β = 91.4600（10）°, V = 4102.5（4）A^°3, Z = 4, Dc = 1.219 g/cm^3, C40H52N4O8, Mr = 752.89, F（000） = 1616,μ = 0.088 mm^-1, MoKa radiation （λ = 0.71073）, R = 0.0578 and wR = 0.1389 for 5588 observed reflections with I 〉 2σ（I）. Moreover, compound 2 was characterized with ^1H NMR, ^13C NMR, IR spectra and MS.
基金Supported by the National Natural Science Foundation of China(No.20272019).
文摘Introduction Although devices based on pseudorotaxanes, cantenanes, and rotaxanes are commercialized yet, several researches have been done on the applications of these donor-acceptor molecules. A promising area is the field of nanotechnology. The miniaturization of semi-conductor technology by the ＂top-down＂ approach is limited by the wavelength of the radiation used in the lithography to prepare electronic components. Therefore, the ＂bottom-up＂ may be more suitable to create devices with sizes down to the molecular level. A molecular or supramolecular system, in which the relative position of the component parts can be altered by an external stimulus, a molecular switch, can act as the basic unit for the creation of new molecular devices .
文摘Nano-sized CeO_2 powders were synthesized by homogeneous precipitation method in alcohol-water solution with HMT as precipitator and the nano-particles were characterized by TEM and BET. The process parameters which influenced the sizes and agglomeration of nanometer CeO_2 powders were studied and the influence mechanism was discussed. The results show that the average size of the particles prepared by the above method with the best process parameters is about 8 nm, and the particles are of smaller size and better dispersion than those obtained from the ordinary powders synthesized by homogeneous precipitation in water solution.
文摘In this letter,the effects of Bragg-mirror quasi-periodicity on the shifts and quality factor in defect modes of photonic crystals are studied by using the transfer matrix method.Furthermore the influence of the quasi-periodicity on electric field enhancement effect inside the defect layer is studied,which is similar to that on the quality factor.
文摘The enhancement effect of the phase-conjugate wave produced by a third order nonlinear optical medium in a （AB）^N （D）^2 （BA）^N Bragg microcavity made of one-dimensional photonic crystals is studied. The gain factor of the phase-conjugate wave is derived when the resonance condition is satisfied by the incident optical wave and the Bragg microcavity mode. Because of stronger resonance enhancement to incident pump beam given by the Bragg microcavity, the enhancement effect of the phase-conjugate wave produced by a third order nonlinear optical medium inside Bragg microcavity is more outstanding than that caused by the naked third order nonlinear optical medium. The theoretical analysis and the numerical calculation show the Bragg microcavity with larger number N of periods is identical with a Fabry-Perot cavity when the resonance condition is satisfied by the incident optical wave and the Bragg microcavity mode.
文摘Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)having calcium chloride,in the presence of poly(vinyl pyrrolidone)(PVP)having a viscosity average molecular weight lower than 40 000.It was confirmed that the polycondensation could be accelerated,the inherent viscosity of the polymer could be increased,and the polymers could be fibrillated more easily by the addition of the PVP.FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps.The morphology of the resultant pulps,the effect of viscosity average molecular weight,amount and adding mode of PVP on inherent viscosity,specific surface area,and mean length of the resultant pulps were discussed in detail.And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.
