Using φ-mapping method and topological current theory, the topological structure and bifurcation ofdisclination lines in two-dimensional liquid crystals are studied. By introducing the strength density and the topolo...Using φ-mapping method and topological current theory, the topological structure and bifurcation ofdisclination lines in two-dimensional liquid crystals are studied. By introducing the strength density and the topologicalcurrent of many disclination lines, the total disclination strength is topologically quantized by the Hopf indices andBrouwer degrees at the singularities of the director field when the Jacobian determinant of director field does not vanish.When the Jacobian determinant vanishes, the origin, annihilation and bifurcation processes of disclination lines arestudied in the neighborhoods of the limit points and bifurcation points, respectively. The branch solutions at the limitpoint and the different directions of all branch curves at the bifurcation point are calculated with the conservation lawof the topological quantum numbers. It is pointed out that a disclination line with a higher strength is unstable and itwill evolve to the lower strength state through the bifurcation process.展开更多
Heat shock cognate proteins 70 (hsp70s) act as molecular chaperones. Some hsp70s are also expressed in unstressed plants, known as hsc70. To gain further knowledge about the hsc70, the Thellungiella halophila hsc70 (T...Heat shock cognate proteins 70 (hsp70s) act as molecular chaperones. Some hsp70s are also expressed in unstressed plants, known as hsc70. To gain further knowledge about the hsc70, the Thellungiella halophila hsc70 (Thhsc70) gene that encoded the cytosolic hsc70 in salt cress (T.halophila (C.A.Mey.) O.E.Schulz) was identified. In unstressed plants the expression of Thhsc70was shown to be tissue-specific. The Thhsc70 gene was induced by heat and cold stresses, but almost not by salt and drought stresses. Overexpression of Thhsc7Ocould increase thermctolerance and chilling tolerance in transgenic Arabidopsis plants.展开更多
High-chromia grains were synthesized by sintering and fusing methods,It was difficult for their sintering body to densify by sintering proess,but high densification grains with high chromia content could be obtained b...High-chromia grains were synthesized by sintering and fusing methods,It was difficult for their sintering body to densify by sintering proess,but high densification grains with high chromia content could be obtained by fusing process.High performance,Cr2O3-Al2O3-ZrO2 refractories needed a suitable amount of alumina powder and pigment chromia,as well as the additive form of unstabilized zirconia,80% Cr2O3 material was ined in a slagging coal gasifier and had gained the service life of 6003 h.The improved Cr2O3-Al2O3-ZrO2 refractory has been used in most of the coal gasi-fiers in China and much better performance is being proved.展开更多
The efficient chiral Ru 3(CO) 12 systems were prepared in situ from Ru 3(CO) 12 and various chiral diimino-or diamino-diphosphine tetradentate ligands. The systems have been used for the asymmetric transfer hy...The efficient chiral Ru 3(CO) 12 systems were prepared in situ from Ru 3(CO) 12 and various chiral diimino-or diamino-diphosphine tetradentate ligands. The systems have been used for the asymmetric transfer hydrogenation of propiophenone in 2-propanol, leading to 1-phenyl-1-propanol in a 98% yield and 96% e.e. The IR study suggests that the carbonyl hydride anion [HRu 3(CO) 11]- most probably exists as a principal species under the reaction conditions. The high chiral efficiency may be due to the synergetic effect produced by the neighboring ruthenium atoms and a special chiral micro-environment involving the polydentate ligand and the Ru 3 framework.展开更多
The existence ofpositive radialsolutions ofthe equation - div(｜Du｜p- 2Du)= f(u) is studied in annular dom ains in Rn,n≥2. Itisproved thatiff(0)≥0, f is somewhere negativein (0,∞), lim u→0+ f′(u)= 0and lim u→...The existence ofpositive radialsolutions ofthe equation - div(｜Du｜p- 2Du)= f(u) is studied in annular dom ains in Rn,n≥2. Itisproved thatiff(0)≥0, f is somewhere negativein (0,∞), lim u→0+ f′(u)= 0and lim u→∞(f(u)/up- 1)= ∞, then thereisa largepositiveradialsolution on allannuli.Iff(0)< 0 and satisfiescertain condi- tions, then the equation has no radialsolution ifthe annuliare too wide.展开更多
A moving boundary model under considering the volume change of spherical resin beads during ion exchange processes was employed to recognize the mechanisms of recovering uranium from carbonate solutions using strongly...A moving boundary model under considering the volume change of spherical resin beads during ion exchange processes was employed to recognize the mechanisms of recovering uranium from carbonate solutions using strongly basic anion exchanger Two important factors, swelling and ion exchange, which directly affect the volume of ion exchangers were taken into account. An ion exchange mechanism has been found for the forward reaction RCl/[UO2 CO3)3]4- at pH 8.5～10.0, where the rate is controlled by liquid-film diffusion at low concentration of the tetravalent uranyl complex anion [UO2 (CO3)3]4-, and is partical diffusion governing at high concentration of the complex anion. The mechanism of RCl/U(Ⅳ) at pH 5. 5～7. 5 is a chemical reaction taking place at the moving boundary of the unreacted nucleus. For the reverse reaction RnU/NaCl, the uranyl tricarbonate complex anion in the resin phase is replaced by Cl- ions with an ion exchange mechanism always determined by particle diffusion. The other forms of uranium in the solid phase loaded on the resin at pH 5. 5～7. 5 should belong to non-exchangeable uranium. The mechanism of the reverse reaction RnU/HCl is always chemical reaction which is not restricted to the moving boundary of the unreacted core.展开更多
Various branched and cyclic hydrocarbons are isolated from the Fushun oil shale and their carbon isotopes are determined. The analytical results show that the branched and cyclic hydrocarbons are fully separated from ...Various branched and cyclic hydrocarbons are isolated from the Fushun oil shale and their carbon isotopes are determined. The analytical results show that the branched and cyclic hydrocarbons are fully separated from n-alkanes by 5 molecular-sieve adduction using long time and cold solvent. The branched and cyclic hydrocarbon frac-tion obtained by this method is able to satisfy the analytic requests of GC-IRMS. The carbon isotopic compositions of these branched and cyclic hydrocarbons obtained from the sample indicate that they are derived from photoautotrophic algae, chemoautotrophic bacteria (-33.4—-39.0) and methanotrophic bacteria (-38.4—-46.3). However the long-chain 2-methyl-branched alkanes indicate that their carbon isotopic compositions reflect biological origin from higher plants. The carbon isotopic composition of C30 4-methyl sterane (-22.1? is the heaviest in all studied ste- ranes, showing that the carbon source or growth condition for its precursor, dinoflagellate, may be different from that of regular steranes. The variation trend of d 13C values between isomers of hopanes shows that 13C-enriched precursors take precedence in process of their epimerization. Methanotro-phic hopanes presented reveal the processes of strong trans-formation of organic matter and cycling of organic carbon in the water column and early diagenesis of oil shale.展开更多
文摘Using φ-mapping method and topological current theory, the topological structure and bifurcation ofdisclination lines in two-dimensional liquid crystals are studied. By introducing the strength density and the topologicalcurrent of many disclination lines, the total disclination strength is topologically quantized by the Hopf indices andBrouwer degrees at the singularities of the director field when the Jacobian determinant of director field does not vanish.When the Jacobian determinant vanishes, the origin, annihilation and bifurcation processes of disclination lines arestudied in the neighborhoods of the limit points and bifurcation points, respectively. The branch solutions at the limitpoint and the different directions of all branch curves at the bifurcation point are calculated with the conservation lawof the topological quantum numbers. It is pointed out that a disclination line with a higher strength is unstable and itwill evolve to the lower strength state through the bifurcation process.
文摘Heat shock cognate proteins 70 (hsp70s) act as molecular chaperones. Some hsp70s are also expressed in unstressed plants, known as hsc70. To gain further knowledge about the hsc70, the Thellungiella halophila hsc70 (Thhsc70) gene that encoded the cytosolic hsc70 in salt cress (T.halophila (C.A.Mey.) O.E.Schulz) was identified. In unstressed plants the expression of Thhsc70was shown to be tissue-specific. The Thhsc70 gene was induced by heat and cold stresses, but almost not by salt and drought stresses. Overexpression of Thhsc7Ocould increase thermctolerance and chilling tolerance in transgenic Arabidopsis plants.
文摘High-chromia grains were synthesized by sintering and fusing methods,It was difficult for their sintering body to densify by sintering proess,but high densification grains with high chromia content could be obtained by fusing process.High performance,Cr2O3-Al2O3-ZrO2 refractories needed a suitable amount of alumina powder and pigment chromia,as well as the additive form of unstabilized zirconia,80% Cr2O3 material was ined in a slagging coal gasifier and had gained the service life of 6003 h.The improved Cr2O3-Al2O3-ZrO2 refractory has been used in most of the coal gasi-fiers in China and much better performance is being proved.
基金Supported by the National Natural Science Foundation of China(No.2 0 0 730 34,2 0 3730 5 6,2 0 1710 37),Fujian Provinceand Technology Comm ission(No.2 0 0 2 F0 16 ) and Xiamen Science and Technology Com mission(No.35 0 2 Z2 0 0 2 10 4 4 )
文摘The efficient chiral Ru 3(CO) 12 systems were prepared in situ from Ru 3(CO) 12 and various chiral diimino-or diamino-diphosphine tetradentate ligands. The systems have been used for the asymmetric transfer hydrogenation of propiophenone in 2-propanol, leading to 1-phenyl-1-propanol in a 98% yield and 96% e.e. The IR study suggests that the carbonyl hydride anion [HRu 3(CO) 11]- most probably exists as a principal species under the reaction conditions. The high chiral efficiency may be due to the synergetic effect produced by the neighboring ruthenium atoms and a special chiral micro-environment involving the polydentate ligand and the Ru 3 framework.
文摘The existence ofpositive radialsolutions ofthe equation - div(｜Du｜p- 2Du)= f(u) is studied in annular dom ains in Rn,n≥2. Itisproved thatiff(0)≥0, f is somewhere negativein (0,∞), lim u→0+ f′(u)= 0and lim u→∞(f(u)/up- 1)= ∞, then thereisa largepositiveradialsolution on allannuli.Iff(0)< 0 and satisfiescertain condi- tions, then the equation has no radialsolution ifthe annuliare too wide.
文摘A moving boundary model under considering the volume change of spherical resin beads during ion exchange processes was employed to recognize the mechanisms of recovering uranium from carbonate solutions using strongly basic anion exchanger Two important factors, swelling and ion exchange, which directly affect the volume of ion exchangers were taken into account. An ion exchange mechanism has been found for the forward reaction RCl/[UO2 CO3)3]4- at pH 8.5～10.0, where the rate is controlled by liquid-film diffusion at low concentration of the tetravalent uranyl complex anion [UO2 (CO3)3]4-, and is partical diffusion governing at high concentration of the complex anion. The mechanism of RCl/U(Ⅳ) at pH 5. 5～7. 5 is a chemical reaction taking place at the moving boundary of the unreacted nucleus. For the reverse reaction RnU/NaCl, the uranyl tricarbonate complex anion in the resin phase is replaced by Cl- ions with an ion exchange mechanism always determined by particle diffusion. The other forms of uranium in the solid phase loaded on the resin at pH 5. 5～7. 5 should belong to non-exchangeable uranium. The mechanism of the reverse reaction RnU/HCl is always chemical reaction which is not restricted to the moving boundary of the unreacted core.
基金This work wassupported by the Knowledge Innovation Program of Chinese Academyof Sciences (Grant No.KZCx3-sw-128), the “973”Programme ofChina (Grant No.2002CB211701), and the Foundation of the State KeyLaboratory of Gas Geochemistry.
文摘Various branched and cyclic hydrocarbons are isolated from the Fushun oil shale and their carbon isotopes are determined. The analytical results show that the branched and cyclic hydrocarbons are fully separated from n-alkanes by 5 molecular-sieve adduction using long time and cold solvent. The branched and cyclic hydrocarbon frac-tion obtained by this method is able to satisfy the analytic requests of GC-IRMS. The carbon isotopic compositions of these branched and cyclic hydrocarbons obtained from the sample indicate that they are derived from photoautotrophic algae, chemoautotrophic bacteria (-33.4—-39.0) and methanotrophic bacteria (-38.4—-46.3). However the long-chain 2-methyl-branched alkanes indicate that their carbon isotopic compositions reflect biological origin from higher plants. The carbon isotopic composition of C30 4-methyl sterane (-22.1? is the heaviest in all studied ste- ranes, showing that the carbon source or growth condition for its precursor, dinoflagellate, may be different from that of regular steranes. The variation trend of d 13C values between isomers of hopanes shows that 13C-enriched precursors take precedence in process of their epimerization. Methanotro-phic hopanes presented reveal the processes of strong trans-formation of organic matter and cycling of organic carbon in the water column and early diagenesis of oil shale.
