Chiral nanostructures have attracted much attention due to the valuable applications in biochemistry, medicine industries, and photonic devices. In this study, we propose an ease-of-fabrication planar nanostructure th...Chiral nanostructures have attracted much attention due to the valuable applications in biochemistry, medicine industries, and photonic devices. In this study, we propose an ease-of-fabrication planar nanostructure that consists of rectangular nanohole arrays in which the Z-shaped nanorod is arranged. Theoretically, such chiral nanostructure supports significant absorption circular dichroism (CD) compared with the Z-shaped nanorod because charge distributions are tuned after the introduction of the rectangular frame. Meanwhile, the Z-shaped nanorod directs the flow of current on the rectangular frame, thereby generating the effective quadruple electron oscillation in the Z-shaped nanorod. A novel mode also emerges when an identical Z-shaped nanorod is added into the rectangular hole. The studies will provide a novel approach to enhance the CD effect of planar structures. .展开更多
The distillation residues of middle-temperature coal tar(DRMCT) were separated into saturate, aromatic, resin and asphaltene fractions by using the combination of solvent extraction and column chromatography separatio...The distillation residues of middle-temperature coal tar(DRMCT) were separated into saturate, aromatic, resin and asphaltene fractions by using the combination of solvent extraction and column chromatography separation.The isolated four fractions have been further characterized through the combination of elemental analysis,Fourier transform infrared(FTIR) spectra, proton nuclear magnetic resonance spectrum(~1H NMR) and molecular weight analysis. The analysis results confirm the view that the saturate fraction from DRMCT was mainly composed of long-chain alkanes and almost all of the heteroatoms(S, N and O) were existed in aromatic structures.The asphaltene fraction had the highest molecular weight, the most amount of heteroatom(especially oxygen)and was the most condensed with shortest alkyl side chains among all the fractions. In addition, for the heavier components, the resin and asphaltene fractions from DRMCT contained lower ratio of H/C, lower molecular weight and higher aromaticity degree when compared with crude oils.展开更多
Analytical expressions of electric fields inside and outside an anisotropic dielectric sphere are presented by transforming an anisotropic medium into an isotropic one based on the multi-scale transformation of electr...Analytical expressions of electric fields inside and outside an anisotropic dielectric sphere are presented by transforming an anisotropic medium into an isotropic one based on the multi-scale transformation of electromagnetic theory. The theoretical expressions are consistent with those in the literature. The inside electric field, the outside electric field and the angle between their directions are derived in detail. Numerical simulations show that the direction of the outside field influences the magnitude of the inside field, while the dielectric constant tensor greatly affects its direction.展开更多
According to the equivalent view for the terminal current-voltage constraint relationship between pathological elements and the various second-generation current-controlled convegors （CCCIIs）, four patholo- gical mo...According to the equivalent view for the terminal current-voltage constraint relationship between pathological elements and the various second-generation current-controlled convegors （CCCIIs）, four patholo- gical models for the CCCII are first derived by means of the nodal admittance matrix expansion in this paper. Moreover, 48 new pathological models for the modified CCCII are also synthesized. The derived pathological models for the various CCCIIs are expected to be useful in circuit analysis and synthesis.展开更多
The chemical constituents from Aconitum richardsonianum var.pseudosessiliflorum were investigated.The roots of this plant were extracted three times with 90% EtOH at the room temperature.The ethanol extracts were comb...The chemical constituents from Aconitum richardsonianum var.pseudosessiliflorum were investigated.The roots of this plant were extracted three times with 90% EtOH at the room temperature.The ethanol extracts were combined and concentrated under reduced pressure to yield residue,which was suspended in water and successively partitioned with chloroform.The chloroform extraction was isolated and purified by silica gel and Sephadex LH-20 column chromatography.Six compounds were isolated and elucidated as delelatine（1）,isodelpheline（2）,3-acetylaconitine（3）,isoatisine（4）,nordhagenine A（5）and yunaconitine（6）.Compounds 1-5 were obtained from Aconitum Brunneum for the first time.Compound（1）showed significant cytotoxic activities（IC50=4.36 μM）against the human tumor cell line P388.展开更多
Based on sixteen nullor-mirror models of the voltage differencing transconductance amplifier (VDTA) and port admittance matrices of the tow-Thomas (T-T) filter with orthogonal control between the characteristic freque...Based on sixteen nullor-mirror models of the voltage differencing transconductance amplifier (VDTA) and port admittance matrices of the tow-Thomas (T-T) filter with orthogonal control between the characteristic frequency(f_0) and figure of merit (Q),two different categories of the voltage-mode and transconductance-mode T-T filters are synthesized by the means of the nodal admittance matrix (NAM) expansion method.The category A filter that employs two compressive VDTAs and two grounded capacitors includes four structures,and the category B filter that uses two compressive VDTAs,two grounded capacitors,and one grounded resistor,also includes four structures.These circuits are suitable for integrated circuit manufacture,and their parameters f_0 and Q can be orthogonally adjusted with varying the bias currents of VDTAs.After the paper and pencil test is completed,the computer analyses,including alternating current (AC),parameter sweep,Monte Carlo (MC),and noise analyses,are performed to support the synthesis approach.展开更多
X-ray emission from the collisions of 3 MeV Ar^(11+)ions with V,Fe,Co,Ni,Cu,and Zn is investigated.Both the x-rays of the target atom and projectile are observed simultaneously.The x-ray yield is extracted from the or...X-ray emission from the collisions of 3 MeV Ar^(11+)ions with V,Fe,Co,Ni,Cu,and Zn is investigated.Both the x-rays of the target atom and projectile are observed simultaneously.The x-ray yield is extracted from the original count.The inner-shell ionization cross section is estimated by the binary encounter approximation model and compared with the experimental result.The remarkable result is that the Ar K-shell x-ray yield is diminished with the target atomic number increasing,which is completely opposite to the theoretical calculation.That is interpreted by the competitive consumption of the energy loss for the ionization of inner-shell electrons between the projectile and target atom.展开更多
An electrochemical sensor incorporating a signal enhancement for the determination of lead （II） ions （Pb2＋） was designed on the basis of the thrombin-binding aptamer （TBA） as a molecular recog- nition element a...An electrochemical sensor incorporating a signal enhancement for the determination of lead （II） ions （Pb2＋） was designed on the basis of the thrombin-binding aptamer （TBA） as a molecular recog- nition element and ionic liquid supported cerium oxide （CeO2） nanoparticles-carbon nanotubes compo- site modification. The composite comprises nanoparticles CeO2, multi-waU carbon nanotubes （MWNTs） and hydrophobic room temperature ionic liquid （RTIL） 1-ethyl-3-methylimidazolium tetrafluoroborate （EMIMBF4）. The electrochemical sensors were fabricated by immersing the CeOa-MWNTs-EMIMBF4 modified glassy carbon electrode （GCE） into the solution of TBA probe. In the presence of Pb2＋, the TBA probe could form stable G-quartet structure by the specific binding interactions between Pb2＋ and TBA. The TBA-bound Pb2＋ can be electrochemically reduced, which provides a readout signal for quantitative detection of Pb2＋. The reduction peak current is linearly related to the concentration of Pb2＋ from 1.0 ＊ 10-8 M to 1.0 ＊ 105 M with a detection limit of 5 ＊ 109 M. This work demonstrates that the CeOz-MWNTs-EMIMBF4 nanocomposite modified GCE provides a promising platform for immobi- lizing the TBA probe and enhancing the sensitivity of the DNA-based sensors.展开更多
A new coordination polymer with the formula of [Co（2-mpac）2（py）·4H2O）]n （1, 2-mpac = 5-methyl-2-pyrazinecarboxylic acid, py = pyrazine） has been synthesized through hydrothermal synthesis and structurally ...A new coordination polymer with the formula of [Co（2-mpac）2（py）·4H2O）]n （1, 2-mpac = 5-methyl-2-pyrazinecarboxylic acid, py = pyrazine） has been synthesized through hydrothermal synthesis and structurally characterized by X-ray single-crystal diffraction method. 1 exhibits a 3D supramolecular network. Crystal data： monoclinic, space group C2/m, a = 15.907（9）, b = 7.104（3）, c = 9.793（5）, β = 95.232（8）o, V = 1102.0（10）3, Z = 2, S = 0.995, the final R = 0.0509, wR = 0.1626 for 1002 observed reflections with （I 〉 2σ（I）） and R = 0.0530, wR = 0.1667 for all data. In addition, elemental analysis, IR and thermalgravimetric analysis are presented.展开更多
A novel cuprous azide complex with the formula of [Cu2（dmpz）（N3）2]n（1, dmpz： 2,6-dimethylpyrazine） has been synthesized through hydrothermal synthesis with the reducibility of H3PO3 and structurally characteriz...A novel cuprous azide complex with the formula of [Cu2（dmpz）（N3）2]n（1, dmpz： 2,6-dimethylpyrazine） has been synthesized through hydrothermal synthesis with the reducibility of H3PO3 and structurally characterized by single-crystal X-ray diffraction method. Single-crystal X-ray diffraction analysis reveals the title complex represents a three-dimensional network structure featuring 2D [Cu N3]n plane units bridged by bridging dmpz ligands to form a 3D network. Research results reveal that 1 has lower impact sensitivity and friction sensitivity, which may be expected to become insensitive energetic material and have potential applications. Crystal data： monoclinic, space group C2/c, a = 17.8599（15）, b = 8.2889（5）, c = 14.8076（14） A, β = 113.2580（10）o, V = 2014.0（3） A3, Z = 8, S = 1.025, the final R = 0.0303, w R = 0.0825 for 1460 observed reflections with I 2σ（I） and R = 0.0386, wR = 0.0870 for all reflections. In addition, elemental analysis, IR, and sensitivity characterization are presented.展开更多
Let Mn be an n-dimensional complete connected and oriented hypersurface in a hyperbolic space H（n＋1）（c） with non-zero constant mean curvature H and two distinct principal curvatures. In this paper, we show that ...Let Mn be an n-dimensional complete connected and oriented hypersurface in a hyperbolic space H（n＋1）（c） with non-zero constant mean curvature H and two distinct principal curvatures. In this paper, we show that （1） if the multiplicities of the two distinct principal curvatures are greater than 1,then Mn is isometric to the Riemannian product Sk（r）×H（n-k）（-1/（r2 ＋ ρ2））, where r 〉 0 and 1 〈 k 〈 n - 1;（2）if H2 〉 -c and one of the two distinct principal curvatures is simple, then Mn is isometric to the Riemannian product S（n-1）（r） × H1（-1/（r2 ＋ρ2）） or S1（r） × H（n-1）（-1/（r2 ＋ρ2））,r 〉 0, if one of the following conditions is satisfied （i） S≤（n-1）t22＋c2t（-2）2 on Mn or （ii）S≥ （n-1）t21＋c2t（-2）1 on Mn or（iii）（n-1）t22＋c2t（-2）2≤ S≤（n-1）t21＋c2t（-2）1 on Mn, where t_1 and t_2 are the positive real roots of （1.5）.展开更多
In order to enhance the water-solubility and biological utilization rate of chrysin, sodium 5,7-dihydroxylflavone-8-sulfonate （1, [Na（H2O）1/2]X, X = C15H9OSO3, 5,7-dihydroxylfla- vone-8-sulfonate） was synthesized ...In order to enhance the water-solubility and biological utilization rate of chrysin, sodium 5,7-dihydroxylflavone-8-sulfonate （1, [Na（H2O）1/2]X, X = C15H9OSO3, 5,7-dihydroxylfla- vone-8-sulfonate） was synthesized and its structure was identified on the basis of NMR, FT-IR and elemental analysis. The assembly of 5,7-dihydroxylflavone-8-sulfonate with diethylamide cation afforded diethylamide 5,7-dihydroxylflavone-8-sulfonate （2, NH2（CH2CH3）2X） which was characterized by FT-IR and elemental analysis. The crystal structures of 1 and 2 were determined by X-ray single-crystal diffraction analysis. The crystal of 1 is of triclinic system, space group P1, with a = 8.5628（13）, b = 12.8916（19）, c = 13.562（2） A, α = 82.494（1）, β = 78.601（2）, γ = 84.033（2）°, C30H20Na2O15S2, Z = 2, Mr = 730.59, V = 1450.3（4） A3, Dc = 1.673 g/cm3, F（000） = 748, p = 0.295 mm^-1, the final R = 0.0641 and wR = 0.1458. The crystal of 2 crystallizes in the triclinic system, space group Pi, with a = 7.689（2）, b = 11.184（3）, c = 11.734（3） A, α = 74.268（3）, βl = 81.751（4）, γ= 87.991（3）°, C19H21NO7S, Z = 2, Mr= 407.43, V= 961.2（4） A3, Dc = 1.408 g/cm3, F（000） = 428, p = 0.210 mm^-1, the final R = 0.0484 and wR = 0.1195. In 1, the three-dimensional structure is organized into organic and inorganic regions; the flavone skeletons are stacked into organic regions by π...π staeking interactions; inorganic regions are generated by Na-O coordination bonds among sulfonate groups, coordinated water molecules and NaI. The sulfonate groups play an important role as a bridge of inorganic and organic regions. One-dimensional chain structure of 2 is extended by N-H…O hydrogen bonds and π...π stacking interactions. Furthermore, the antioxidant activity of 1 was evaluated. The scavenging activity of 1 to DPPH free radical is better than that of the parent compound chrysin.展开更多
We produced epitaxial graphene under a moderate pressure of 4 mbar （about 400 Pa） at temperature 1600 ℃. Raman spectroscopy and optical microscopy were used to confirm that epitaxial graphene has taken shape contin...We produced epitaxial graphene under a moderate pressure of 4 mbar （about 400 Pa） at temperature 1600 ℃. Raman spectroscopy and optical microscopy were used to confirm that epitaxial graphene has taken shape continually with slight thickness variations and regularly with a centimeter order of magnitude on 4H-SiC （0001） substrates. Then using X-ray photoelectron spectroscopy and Auger electron spectroscopy, we analyzed the chemical compositions and estimated the layer number of epitaxial graphene. Finally, an atomic force microscope and a scanning force microscope were used to characterize the morphological structure. Our results showed that under 4-mbar pressure, epitaxial graphene could be produced on a SiC substrate with a large area, uniform thickness but a limited morphological property. We hope our work will be of benefit to understanding the formation process of epitaxial graphene on SiC substrate in detail.展开更多
Utilizing mononuclear complex Ni（2-mpac）2（H2O）2 as the molecular building block,a novel coordination polymer [Ni2（2-mpac）4（4,4＇-bpy）·2H2O]n（1,2-mpac = 5-methyl-2-pyrazinecar-boxylic acid,4,4＇-bpy = 4,4...Utilizing mononuclear complex Ni（2-mpac）2（H2O）2 as the molecular building block,a novel coordination polymer [Ni2（2-mpac）4（4,4＇-bpy）·2H2O]n（1,2-mpac = 5-methyl-2-pyrazinecar-boxylic acid,4,4＇-bpy = 4,4＇-bipyridine） was successfully synthesized and structurally characterized by X-ray single-crystal diffraction method.Crystal data：monoclinic,space group C2/c,a = 23.870（1）,b = 9.887（4）,c = 18.929（9） ,β = 126.840（5）°,V = 3575（3） 3,Z = 4,S = 1.046,μ = 1.594 mm-1,F（000） = 1768 and Dc = 1.127 g·cm-3.The final R = 0.0351 and wR = 0.0792 for 2372 observed reflections with Ⅰ 〉 2σ（Ⅰ） and R = 0.0564 and wR = 0.0938 for all reflections.展开更多
Excitable media,such as cells,can be polarized and magnetized in the presence of an external electromagnetic field.In fact,distinct geometric deformation can be induced by the external electromagnetic field,and also t...Excitable media,such as cells,can be polarized and magnetized in the presence of an external electromagnetic field.In fact,distinct geometric deformation can be induced by the external electromagnetic field,and also the capacitance of the membrane of cell can be changed to pump the field energy.Furthermore,the distribution of ion concentration inside and outside the cell can also be greatly adjusted.Based on the theory of bio-electromagnetism,the distribution of field energy and intracellular and extracellular ion concentrations in a single shell cell can be estimated in the case with or without external electric field.Also,the dependence of shape of cell on the applied electronic field is calculated.From the viewpoint of physics,the involvement of external electric field will change the gradient distribution of field energy blocked by the membrane.And the intracellular and extracellular ion concentration show a certain difference in generating timevarying membrane potential in the presence of electric field.When a constant electric field is applied to the cell,distinct geometric deformation is induced,and the cell triggers a transition from prolate to spherical and then to oblate ellipsoid shape.It is found that the critical frequency in the applied electric field for triggering the distinct transition from prolate to oblate ellipsoid shape obtains smaller value when larger dielectric constant of the cell membrane and intracellular medium,and smaller conductivity for the intracellular medium are used.Furthermore,the effect of cell deformation is estimated by analyzing the capacitance per unit area,the density of field energy,and the change of ion concentration on one side of cell membrane.The intensity of external applied electric field is further increased to detect the change of ion concentration.And the biophysical effect in the cell is discussed.So the deformation effect of cells in electric field should be considered when regulating and preventing harm to normal neural activities occurs in a nervous system.展开更多
[Objective] The aim was to study the coupling relationship between economic development and ecological environment. [Method] Firstly, the evaluation index system for the coupling system of economic development and eco...[Objective] The aim was to study the coupling relationship between economic development and ecological environment. [Method] Firstly, the evaluation index system for the coupling system of economic development and ecological environment in Xi’an City was established, then the dynamic variation of coupling relationship between economic development and ecological environment in Xi’an City from 2001 to 2010 was analyzed by using entropy method, finally some corresponding suggestions were put forward according to the problems in the current development model. [Result] The economic development and ecological environment of Xi’an have made a significant upgrading and improvement from 2001 to 2010, namely showing a stable upward trend on the whole, and were in a well-coordinated development state in 2010. However, the development level of ecological environment obviously lagged behind economic development level. In addition, there were obvious differences in the development rate of sub-systems, that is, economic efficiency and economic level developed rapidly, while the carrying capacity of ecological environment and economic vitality grew slowly and unstably. [Conclusion] The research could provide theoretical bases for the establishment of strategies for the coordinated development economy and environment in Xi’an City.展开更多
[Objective] The study aims at evaluating the water environmental quality of the Liaohe River mainstream. [ Method] The water quality of two monitored sections in the mainstream of the Liaohe River from 2004 to 2010 wa...[Objective] The study aims at evaluating the water environmental quality of the Liaohe River mainstream. [ Method] The water quality of two monitored sections in the mainstream of the Liaohe River from 2004 to 2010 was assessed by the fuzzy comprehensive appraisal combined with weighted average, and some practicable measures were put forward according to the assessment results. [ Result] From 2004 to 2010, the water quality of the Liaohe River mainstream varied from Grade II to III at Zhuershan section, and changed from Grade II to IV at Xing＇an section, becom- ing better on the whole. In addition, the major factor influencing the water quality is the small content of dissolved oxygen （DO） in the water body. Meanwhile, the pollution of the water body mainly results from the discharge of organic matter consuming oxygen largely, and ammonia nitrogen should be paid more attention to. [ Conclusion] The research could provide scientific references for the protection of water environment and its pollu- tion control in the mainstream of the Liaohe River.展开更多
The functional network was introduced by E.Catillo, which extended the neural network. Not only can it solve the problems solved, but also it can formulate the ones that cannot be solved by traditional network. This p...The functional network was introduced by E.Catillo, which extended the neural network. Not only can it solve the problems solved, but also it can formulate the ones that cannot be solved by traditional network. This paper applies functional network to approximate the multidimension function under the ridgelet theory. The method performs more stable and faster than the traditional neural network. The numerical examples demonstrate the performance.展开更多
Based on the scales theory of electromagnetic waves, the analytical expression of electrical fields inside an anisotropic medium sphere is studied. Differential scattering cross section and radar cross section （RCS）...Based on the scales theory of electromagnetic waves, the analytical expression of electrical fields inside an anisotropic medium sphere is studied. Differential scattering cross section and radar cross section （RCS） for an anisotropic spherical target are presented. The correctness of the obtained results is tested. The simulation results show that the scattering of an anisotropic sphere has the property of a dipole radiation under the condition of Rayleigh scattering. The larger the dielectric constant is, the stronger the dipole scattering is. Anisotropy in magnetism only has an effect on differential RCS. These results provide a theoretical base for the identification of anisotropic targets.展开更多
Background:Cotton is the world’s largest and most important source of renewable natural fiber.BEL1-like homeodomain(BLH)genes are ubiquitous in plants and have been reported to contribute to plant development.However...Background:Cotton is the world’s largest and most important source of renewable natural fiber.BEL1-like homeodomain(BLH)genes are ubiquitous in plants and have been reported to contribute to plant development.However,there is no comprehensive characterization of this gene family in cotton.In this study,32,16,and 18 BLH genes were identified from the G.hirsutum,G.arboreum,and G.raimondii genome,respectively.In addition,we also studied the phylogenetic relationships,chromosomal location,gene structure,and gene expression patterns of the BLH genes.Results:The results indicated that these BLH proteins were divided into seven distinct groups by phylogenetic analysis.Among them,25 members were assigned to 15 chromosomes.Furthermore,gene structure,chromosomal location,conserved motifs,and expression level of BLH genes were investigated in G.hirsutum.Expression profiles analysis showed that four genes(GhBLH1_3,GhBLH1_4,GhBLH1_5,and GhBLH1_6)from BLH1 subfamily were highly expressed during the fiber cell elongation period.The expression levels of these genes were significantly induced by gibberellic acid and brassinosteroid,but not auxin.Exogenous application of gibberellic acid significantly enhanced GhBLH1_3,GhBLH1_4,and GhBLH1_5 transcripts.Expression levels of GhBLH1_3 and GhBLH1_4 genes were significantly increased under brassinosteroid treatment.Conclusions:The BLH gene family plays a very important role in many biological processes during plant growth and development.This study deepens our understanding of the role of the GhBLH1 gene involved in fiber development and will help us in breeding better cotton varieties in the future.展开更多
文摘Chiral nanostructures have attracted much attention due to the valuable applications in biochemistry, medicine industries, and photonic devices. In this study, we propose an ease-of-fabrication planar nanostructure that consists of rectangular nanohole arrays in which the Z-shaped nanorod is arranged. Theoretically, such chiral nanostructure supports significant absorption circular dichroism (CD) compared with the Z-shaped nanorod because charge distributions are tuned after the introduction of the rectangular frame. Meanwhile, the Z-shaped nanorod directs the flow of current on the rectangular frame, thereby generating the effective quadruple electron oscillation in the Z-shaped nanorod. A novel mode also emerges when an identical Z-shaped nanorod is added into the rectangular hole. The studies will provide a novel approach to enhance the CD effect of planar structures. .
基金Supported by the Natural Science Basic Research Plan in Shaanxi Province of China(2016JM5024)Scientific Research Program of Shaanxi Provincial Education Department(14JK1801)Xianyang Normal University Special Research Fund(15XSYK040)
文摘The distillation residues of middle-temperature coal tar(DRMCT) were separated into saturate, aromatic, resin and asphaltene fractions by using the combination of solvent extraction and column chromatography separation.The isolated four fractions have been further characterized through the combination of elemental analysis,Fourier transform infrared(FTIR) spectra, proton nuclear magnetic resonance spectrum(~1H NMR) and molecular weight analysis. The analysis results confirm the view that the saturate fraction from DRMCT was mainly composed of long-chain alkanes and almost all of the heteroatoms(S, N and O) were existed in aromatic structures.The asphaltene fraction had the highest molecular weight, the most amount of heteroatom(especially oxygen)and was the most condensed with shortest alkyl side chains among all the fractions. In addition, for the heavier components, the resin and asphaltene fractions from DRMCT contained lower ratio of H/C, lower molecular weight and higher aromaticity degree when compared with crude oils.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60741003 and 60871047)
文摘Analytical expressions of electric fields inside and outside an anisotropic dielectric sphere are presented by transforming an anisotropic medium into an isotropic one based on the multi-scale transformation of electromagnetic theory. The theoretical expressions are consistent with those in the literature. The inside electric field, the outside electric field and the angle between their directions are derived in detail. Numerical simulations show that the direction of the outside field influences the magnitude of the inside field, while the dielectric constant tensor greatly affects its direction.
基金supported by the Natural Science Foundation of Shaanxi Province under Grant No.2017JM6087
文摘According to the equivalent view for the terminal current-voltage constraint relationship between pathological elements and the various second-generation current-controlled convegors （CCCIIs）, four patholo- gical models for the CCCII are first derived by means of the nodal admittance matrix expansion in this paper. Moreover, 48 new pathological models for the modified CCCII are also synthesized. The derived pathological models for the various CCCIIs are expected to be useful in circuit analysis and synthesis.
基金financially supported by the Scientific Research Program Funded by Shaanxi Provincial Department(2010JK74909JK672)+1 种基金by the Special Research Fund for the Doctoral Program of Higher Education(20096118110008)the Natural Science Foundation of Shaanxi Province(SJ08B16)
文摘The chemical constituents from Aconitum richardsonianum var.pseudosessiliflorum were investigated.The roots of this plant were extracted three times with 90% EtOH at the room temperature.The ethanol extracts were combined and concentrated under reduced pressure to yield residue,which was suspended in water and successively partitioned with chloroform.The chloroform extraction was isolated and purified by silica gel and Sephadex LH-20 column chromatography.Six compounds were isolated and elucidated as delelatine（1）,isodelpheline（2）,3-acetylaconitine（3）,isoatisine（4）,nordhagenine A（5）and yunaconitine（6）.Compounds 1-5 were obtained from Aconitum Brunneum for the first time.Compound（1）showed significant cytotoxic activities（IC50=4.36 μM）against the human tumor cell line P388.
基金supported by the Natural Science Foundation of Shaanxi Province,China under Grant No. 2017JM6087。
文摘Based on sixteen nullor-mirror models of the voltage differencing transconductance amplifier (VDTA) and port admittance matrices of the tow-Thomas (T-T) filter with orthogonal control between the characteristic frequency(f_0) and figure of merit (Q),two different categories of the voltage-mode and transconductance-mode T-T filters are synthesized by the means of the nodal admittance matrix (NAM) expansion method.The category A filter that employs two compressive VDTAs and two grounded capacitors includes four structures,and the category B filter that uses two compressive VDTAs,two grounded capacitors,and one grounded resistor,also includes four structures.These circuits are suitable for integrated circuit manufacture,and their parameters f_0 and Q can be orthogonally adjusted with varying the bias currents of VDTAs.After the paper and pencil test is completed,the computer analyses,including alternating current (AC),parameter sweep,Monte Carlo (MC),and noise analyses,are performed to support the synthesis approach.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFA0402300)the National Natural Science Foundation of China(Grant Nos.11505248,11775042,11875096,and 11605147)the Scientific Research Program Funded by Shaanxi Provincial Education Department,China(Grant No.20JK0975)+2 种基金the Scientific Research Plan of Science and Technology Department of Shaanxi Province,China(Grant Nos.2021JQ-812 and 2020JM-624)Open Funds of MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions(Grant No.MPCEC201901)Xianyang Normal University Science Foundation(Grant Nos.XSYK20009 and XSYK20024).
文摘X-ray emission from the collisions of 3 MeV Ar^(11+)ions with V,Fe,Co,Ni,Cu,and Zn is investigated.Both the x-rays of the target atom and projectile are observed simultaneously.The x-ray yield is extracted from the original count.The inner-shell ionization cross section is estimated by the binary encounter approximation model and compared with the experimental result.The remarkable result is that the Ar K-shell x-ray yield is diminished with the target atomic number increasing,which is completely opposite to the theoretical calculation.That is interpreted by the competitive consumption of the energy loss for the ionization of inner-shell electrons between the projectile and target atom.
基金supports from the National Science Foundations of China (Nos. 20875076 and 21005061)the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20096101120011)+2 种基金the Natural Science Basic Research Plan in Shaanxi Province of China (No.2010JQ2013)the Education Department of Shaanxi Province,China (No. 09JK759)the NWU Graduate Innovation and Creativity Funds (No. 09YSY04)
文摘An electrochemical sensor incorporating a signal enhancement for the determination of lead （II） ions （Pb2＋） was designed on the basis of the thrombin-binding aptamer （TBA） as a molecular recog- nition element and ionic liquid supported cerium oxide （CeO2） nanoparticles-carbon nanotubes compo- site modification. The composite comprises nanoparticles CeO2, multi-waU carbon nanotubes （MWNTs） and hydrophobic room temperature ionic liquid （RTIL） 1-ethyl-3-methylimidazolium tetrafluoroborate （EMIMBF4）. The electrochemical sensors were fabricated by immersing the CeOa-MWNTs-EMIMBF4 modified glassy carbon electrode （GCE） into the solution of TBA probe. In the presence of Pb2＋, the TBA probe could form stable G-quartet structure by the specific binding interactions between Pb2＋ and TBA. The TBA-bound Pb2＋ can be electrochemically reduced, which provides a readout signal for quantitative detection of Pb2＋. The reduction peak current is linearly related to the concentration of Pb2＋ from 1.0 ＊ 10-8 M to 1.0 ＊ 105 M with a detection limit of 5 ＊ 109 M. This work demonstrates that the CeOz-MWNTs-EMIMBF4 nanocomposite modified GCE provides a promising platform for immobi- lizing the TBA probe and enhancing the sensitivity of the DNA-based sensors.
基金Natural Science Foundation of Shaanxi Province (2009JQ2015,2010JM2009)Special Research Fund of Education Department of Shaanxi Province (09JK798, 2010JK902)
文摘A new coordination polymer with the formula of [Co（2-mpac）2（py）·4H2O）]n （1, 2-mpac = 5-methyl-2-pyrazinecarboxylic acid, py = pyrazine） has been synthesized through hydrothermal synthesis and structurally characterized by X-ray single-crystal diffraction method. 1 exhibits a 3D supramolecular network. Crystal data： monoclinic, space group C2/m, a = 15.907（9）, b = 7.104（3）, c = 9.793（5）, β = 95.232（8）o, V = 1102.0（10）3, Z = 2, S = 0.995, the final R = 0.0509, wR = 0.1626 for 1002 observed reflections with （I 〉 2σ（I）） and R = 0.0530, wR = 0.1667 for all data. In addition, elemental analysis, IR and thermalgravimetric analysis are presented.
基金Supported by the National Natural Science Foundation of China(No.21203160)Education Department Foundation of Shaanxi Province(No.12JK0631)+1 种基金Natural Science Foundation of Shaanxi Province(No.2013JM2013)Special Research Fund of Xianyang Normal University(No.11XSYK204,11XSYK205,12XSYK023)
文摘A novel cuprous azide complex with the formula of [Cu2（dmpz）（N3）2]n（1, dmpz： 2,6-dimethylpyrazine） has been synthesized through hydrothermal synthesis with the reducibility of H3PO3 and structurally characterized by single-crystal X-ray diffraction method. Single-crystal X-ray diffraction analysis reveals the title complex represents a three-dimensional network structure featuring 2D [Cu N3]n plane units bridged by bridging dmpz ligands to form a 3D network. Research results reveal that 1 has lower impact sensitivity and friction sensitivity, which may be expected to become insensitive energetic material and have potential applications. Crystal data： monoclinic, space group C2/c, a = 17.8599（15）, b = 8.2889（5）, c = 14.8076（14） A, β = 113.2580（10）o, V = 2014.0（3） A3, Z = 8, S = 1.025, the final R = 0.0303, w R = 0.0825 for 1460 observed reflections with I 2σ（I） and R = 0.0386, wR = 0.0870 for all reflections. In addition, elemental analysis, IR, and sensitivity characterization are presented.
基金supported by NSF of Shaanxi Province (SJ08A31)NSF of Shaanxi Educational Committee (2008JK484+1 种基金2010JK642)Talent Fund of Xi'an University of Architecture and Technology
文摘Let Mn be an n-dimensional complete connected and oriented hypersurface in a hyperbolic space H（n＋1）（c） with non-zero constant mean curvature H and two distinct principal curvatures. In this paper, we show that （1） if the multiplicities of the two distinct principal curvatures are greater than 1,then Mn is isometric to the Riemannian product Sk（r）×H（n-k）（-1/（r2 ＋ ρ2））, where r 〉 0 and 1 〈 k 〈 n - 1;（2）if H2 〉 -c and one of the two distinct principal curvatures is simple, then Mn is isometric to the Riemannian product S（n-1）（r） × H1（-1/（r2 ＋ρ2）） or S1（r） × H（n-1）（-1/（r2 ＋ρ2））,r 〉 0, if one of the following conditions is satisfied （i） S≤（n-1）t22＋c2t（-2）2 on Mn or （ii）S≥ （n-1）t21＋c2t（-2）1 on Mn or（iii）（n-1）t22＋c2t（-2）2≤ S≤（n-1）t21＋c2t（-2）1 on Mn, where t_1 and t_2 are the positive real roots of （1.5）.
基金Supported by the National Basic Research Program of China (973 Program,2009CB219906)NNSFC(20776117)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education of China(20070698037)Natural Science Foundation of Shaanxi Province (No.2005B01)
文摘In order to enhance the water-solubility and biological utilization rate of chrysin, sodium 5,7-dihydroxylflavone-8-sulfonate （1, [Na（H2O）1/2]X, X = C15H9OSO3, 5,7-dihydroxylfla- vone-8-sulfonate） was synthesized and its structure was identified on the basis of NMR, FT-IR and elemental analysis. The assembly of 5,7-dihydroxylflavone-8-sulfonate with diethylamide cation afforded diethylamide 5,7-dihydroxylflavone-8-sulfonate （2, NH2（CH2CH3）2X） which was characterized by FT-IR and elemental analysis. The crystal structures of 1 and 2 were determined by X-ray single-crystal diffraction analysis. The crystal of 1 is of triclinic system, space group P1, with a = 8.5628（13）, b = 12.8916（19）, c = 13.562（2） A, α = 82.494（1）, β = 78.601（2）, γ = 84.033（2）°, C30H20Na2O15S2, Z = 2, Mr = 730.59, V = 1450.3（4） A3, Dc = 1.673 g/cm3, F（000） = 748, p = 0.295 mm^-1, the final R = 0.0641 and wR = 0.1458. The crystal of 2 crystallizes in the triclinic system, space group Pi, with a = 7.689（2）, b = 11.184（3）, c = 11.734（3） A, α = 74.268（3）, βl = 81.751（4）, γ= 87.991（3）°, C19H21NO7S, Z = 2, Mr= 407.43, V= 961.2（4） A3, Dc = 1.408 g/cm3, F（000） = 428, p = 0.210 mm^-1, the final R = 0.0484 and wR = 0.1195. In 1, the three-dimensional structure is organized into organic and inorganic regions; the flavone skeletons are stacked into organic regions by π...π staeking interactions; inorganic regions are generated by Na-O coordination bonds among sulfonate groups, coordinated water molecules and NaI. The sulfonate groups play an important role as a bridge of inorganic and organic regions. One-dimensional chain structure of 2 is extended by N-H…O hydrogen bonds and π...π stacking interactions. Furthermore, the antioxidant activity of 1 was evaluated. The scavenging activity of 1 to DPPH free radical is better than that of the parent compound chrysin.
基金supported by the Key Specific Projects in the National Science&Technology Program,China(Grant No.2011ZX02707)the Key Research Foundationfrom the Ministry of Education of China(Grant No.JY10000925016)the Specialized Research Fund from Xianyang Normal University,China(GrantNos.13XSYK010 and 201302026)
文摘We produced epitaxial graphene under a moderate pressure of 4 mbar （about 400 Pa） at temperature 1600 ℃. Raman spectroscopy and optical microscopy were used to confirm that epitaxial graphene has taken shape continually with slight thickness variations and regularly with a centimeter order of magnitude on 4H-SiC （0001） substrates. Then using X-ray photoelectron spectroscopy and Auger electron spectroscopy, we analyzed the chemical compositions and estimated the layer number of epitaxial graphene. Finally, an atomic force microscope and a scanning force microscope were used to characterize the morphological structure. Our results showed that under 4-mbar pressure, epitaxial graphene could be produced on a SiC substrate with a large area, uniform thickness but a limited morphological property. We hope our work will be of benefit to understanding the formation process of epitaxial graphene on SiC substrate in detail.
基金Supported by the National Natural Science Foundation of China (20771089)Natural Science Foundation of Shaanxi Province (2009JQ2015,SJ08B09,2007B02)+1 种基金Special Research Fund of Education Department of Shaanxi Province (09JK798)Special Research Fund of Xianyang Normal University (08XSYK305,09XSYK215)
文摘Utilizing mononuclear complex Ni（2-mpac）2（H2O）2 as the molecular building block,a novel coordination polymer [Ni2（2-mpac）4（4,4＇-bpy）·2H2O]n（1,2-mpac = 5-methyl-2-pyrazinecar-boxylic acid,4,4＇-bpy = 4,4＇-bipyridine） was successfully synthesized and structurally characterized by X-ray single-crystal diffraction method.Crystal data：monoclinic,space group C2/c,a = 23.870（1）,b = 9.887（4）,c = 18.929（9） ,β = 126.840（5）°,V = 3575（3） 3,Z = 4,S = 1.046,μ = 1.594 mm-1,F（000） = 1768 and Dc = 1.127 g·cm-3.The final R = 0.0351 and wR = 0.0792 for 2372 observed reflections with Ⅰ 〉 2σ（Ⅰ） and R = 0.0564 and wR = 0.0938 for all reflections.
文摘Excitable media,such as cells,can be polarized and magnetized in the presence of an external electromagnetic field.In fact,distinct geometric deformation can be induced by the external electromagnetic field,and also the capacitance of the membrane of cell can be changed to pump the field energy.Furthermore,the distribution of ion concentration inside and outside the cell can also be greatly adjusted.Based on the theory of bio-electromagnetism,the distribution of field energy and intracellular and extracellular ion concentrations in a single shell cell can be estimated in the case with or without external electric field.Also,the dependence of shape of cell on the applied electronic field is calculated.From the viewpoint of physics,the involvement of external electric field will change the gradient distribution of field energy blocked by the membrane.And the intracellular and extracellular ion concentration show a certain difference in generating timevarying membrane potential in the presence of electric field.When a constant electric field is applied to the cell,distinct geometric deformation is induced,and the cell triggers a transition from prolate to spherical and then to oblate ellipsoid shape.It is found that the critical frequency in the applied electric field for triggering the distinct transition from prolate to oblate ellipsoid shape obtains smaller value when larger dielectric constant of the cell membrane and intracellular medium,and smaller conductivity for the intracellular medium are used.Furthermore,the effect of cell deformation is estimated by analyzing the capacitance per unit area,the density of field energy,and the change of ion concentration on one side of cell membrane.The intensity of external applied electric field is further increased to detect the change of ion concentration.And the biophysical effect in the cell is discussed.So the deformation effect of cells in electric field should be considered when regulating and preventing harm to normal neural activities occurs in a nervous system.
基金Supported by Special Fund Project for Key Subject Construction of Shaanxi Province,China
文摘[Objective] The aim was to study the coupling relationship between economic development and ecological environment. [Method] Firstly, the evaluation index system for the coupling system of economic development and ecological environment in Xi’an City was established, then the dynamic variation of coupling relationship between economic development and ecological environment in Xi’an City from 2001 to 2010 was analyzed by using entropy method, finally some corresponding suggestions were put forward according to the problems in the current development model. [Result] The economic development and ecological environment of Xi’an have made a significant upgrading and improvement from 2001 to 2010, namely showing a stable upward trend on the whole, and were in a well-coordinated development state in 2010. However, the development level of ecological environment obviously lagged behind economic development level. In addition, there were obvious differences in the development rate of sub-systems, that is, economic efficiency and economic level developed rapidly, while the carrying capacity of ecological environment and economic vitality grew slowly and unstably. [Conclusion] The research could provide theoretical bases for the establishment of strategies for the coordinated development economy and environment in Xi’an City.
基金Supported by National Natural Science Foundation of China (11075135)Key Project Supporting Historical and Geographical Subject of Shaanxi Province (10722,60103)Key Subject Project of Xianyang Normal University
文摘[Objective] The study aims at evaluating the water environmental quality of the Liaohe River mainstream. [ Method] The water quality of two monitored sections in the mainstream of the Liaohe River from 2004 to 2010 was assessed by the fuzzy comprehensive appraisal combined with weighted average, and some practicable measures were put forward according to the assessment results. [ Result] From 2004 to 2010, the water quality of the Liaohe River mainstream varied from Grade II to III at Zhuershan section, and changed from Grade II to IV at Xing＇an section, becom- ing better on the whole. In addition, the major factor influencing the water quality is the small content of dissolved oxygen （DO） in the water body. Meanwhile, the pollution of the water body mainly results from the discharge of organic matter consuming oxygen largely, and ammonia nitrogen should be paid more attention to. [ Conclusion] The research could provide scientific references for the protection of water environment and its pollu- tion control in the mainstream of the Liaohe River.
基金Partly supported by the National Natura Science Foundation of China(No.60133010)the Natura Science Foundation of Education Department of Shaanxi Province(No.05JK312)the Natura Science Foundation of Xianyang Normal University(No.04XSYK101)
文摘The functional network was introduced by E.Catillo, which extended the neural network. Not only can it solve the problems solved, but also it can formulate the ones that cannot be solved by traditional network. This paper applies functional network to approximate the multidimension function under the ridgelet theory. The method performs more stable and faster than the traditional neural network. The numerical examples demonstrate the performance.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60971079 and 60801047.
文摘Based on the scales theory of electromagnetic waves, the analytical expression of electrical fields inside an anisotropic medium sphere is studied. Differential scattering cross section and radar cross section （RCS） for an anisotropic spherical target are presented. The correctness of the obtained results is tested. The simulation results show that the scattering of an anisotropic sphere has the property of a dipole radiation under the condition of Rayleigh scattering. The larger the dielectric constant is, the stronger the dipole scattering is. Anisotropy in magnetism only has an effect on differential RCS. These results provide a theoretical base for the identification of anisotropic targets.
基金the State Key Laboratory of Cotton Biology Open Fund(CB2019A03,2019A09 and CB2020A12)the National Natural Science Foundation of China(31872175)+2 种基金the Fundamental Research Funds for the Central Universities(GK202002005 and GK202001004)Natural Science Basic Research Plan in Shaanxi Province of China(2018JZ3006 and 2019JQ-062),Shaanxi Youth Entrusted Talents Program(20190205),Shaanxi Postdoctoral Project(2018BSHYDZZ76)Young Elite Scientists Sponsorship Program by CAST(2019-2021QNRC001).
文摘Background:Cotton is the world’s largest and most important source of renewable natural fiber.BEL1-like homeodomain(BLH)genes are ubiquitous in plants and have been reported to contribute to plant development.However,there is no comprehensive characterization of this gene family in cotton.In this study,32,16,and 18 BLH genes were identified from the G.hirsutum,G.arboreum,and G.raimondii genome,respectively.In addition,we also studied the phylogenetic relationships,chromosomal location,gene structure,and gene expression patterns of the BLH genes.Results:The results indicated that these BLH proteins were divided into seven distinct groups by phylogenetic analysis.Among them,25 members were assigned to 15 chromosomes.Furthermore,gene structure,chromosomal location,conserved motifs,and expression level of BLH genes were investigated in G.hirsutum.Expression profiles analysis showed that four genes(GhBLH1_3,GhBLH1_4,GhBLH1_5,and GhBLH1_6)from BLH1 subfamily were highly expressed during the fiber cell elongation period.The expression levels of these genes were significantly induced by gibberellic acid and brassinosteroid,but not auxin.Exogenous application of gibberellic acid significantly enhanced GhBLH1_3,GhBLH1_4,and GhBLH1_5 transcripts.Expression levels of GhBLH1_3 and GhBLH1_4 genes were significantly increased under brassinosteroid treatment.Conclusions:The BLH gene family plays a very important role in many biological processes during plant growth and development.This study deepens our understanding of the role of the GhBLH1 gene involved in fiber development and will help us in breeding better cotton varieties in the future.
