In the present paper is reported the method for the isolation and extraction of total flavonoids of Epimedium Koreanum Nakai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts...In the present paper is reported the method for the isolation and extraction of total flavonoids of Epimedium Koreanum Nakai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts of modifier and extraction time, the optimized condition of SFE is confirmed as 30 MPa and 60 ℃, with 70% ethanol as the modifier. The samples were statically extracted for 30 min, followed by dynamic extraction for 120 min at a flow rate of 6 mL/min. The quantitative analysis of total flavonoids was performed by UV-Vis spectrophotometry. Compared with the conventional method, the SFE method is more efficient, more rapid and more friendly environmentally.展开更多
The crystal structure of tetrakis[(pyrrol-1-yl)methyl]methane was determined by X-ray diffraction measurement, and the result shows that it belongs to monoclinic crystal system, space group is P2 1/n, with a=0.9284(3...The crystal structure of tetrakis[(pyrrol-1-yl)methyl]methane was determined by X-ray diffraction measurement, and the result shows that it belongs to monoclinic crystal system, space group is P2 1/n, with a=0.9284(3) nm, b=1.0950(6) nm, c=1.8749(8) nm; α=γ= 90.00(4)°, β=103.63(3)°, V=1.8523(14) nm 3, Z=4, ρ calcd. =1.192 kg/m 3, μ=0.072 nm -1 , F(000)=712, R 1=0.0854, wR 2=0.1884. It has been found that the molecules exist in two enantiomeric states. Enantioselective self-assemblies such as one-dimensional molecular stacks in a single handedness, homochiral monolayers and a chiral superlattice are specified in this racemic crystal. In addition, a simple technique is advocated to distinguish chiral states from tetrahedral molecules in the solid state. The present R/S nomenclature of the tetracooradinated carbon centers is used solely for its convenience to distinguish the two enantiomeric states, but not used to determine the absolute configurations.展开更多
The solidification of primary austenite in hypoeutectic gray cast iron was studied by stepped grinding and quantitative metallography. The dendrite structure of primary austenite can be described by three models: typi...The solidification of primary austenite in hypoeutectic gray cast iron was studied by stepped grinding and quantitative metallography. The dendrite structure of primary austenite can be described by three models: typical dendrite crystal model, metamorphic dendrite crystal model and network dendrite crystal model. The dendrite crystals formed according to 3rd model is much more than those formed according to other models in this experiment. The primary austenites are connected each other, and the primary stems of austenite could be regarded as secondary arms and vice versa.展开更多
基金the Natural Science and Technology Foundation of Jilin Province(No.2 0 0 2 0 6 37- 1)
文摘In the present paper is reported the method for the isolation and extraction of total flavonoids of Epimedium Koreanum Nakai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts of modifier and extraction time, the optimized condition of SFE is confirmed as 30 MPa and 60 ℃, with 70% ethanol as the modifier. The samples were statically extracted for 30 min, followed by dynamic extraction for 120 min at a flow rate of 6 mL/min. The quantitative analysis of total flavonoids was performed by UV-Vis spectrophotometry. Compared with the conventional method, the SFE method is more efficient, more rapid and more friendly environmentally.
基金the National Natural Science Foundation of China(No.6 0 1710 0 8) and Shanghai Science and TechnologyCom mittee(No.0 2 14 nm0 0 5 )
文摘The crystal structure of tetrakis[(pyrrol-1-yl)methyl]methane was determined by X-ray diffraction measurement, and the result shows that it belongs to monoclinic crystal system, space group is P2 1/n, with a=0.9284(3) nm, b=1.0950(6) nm, c=1.8749(8) nm; α=γ= 90.00(4)°, β=103.63(3)°, V=1.8523(14) nm 3, Z=4, ρ calcd. =1.192 kg/m 3, μ=0.072 nm -1 , F(000)=712, R 1=0.0854, wR 2=0.1884. It has been found that the molecules exist in two enantiomeric states. Enantioselective self-assemblies such as one-dimensional molecular stacks in a single handedness, homochiral monolayers and a chiral superlattice are specified in this racemic crystal. In addition, a simple technique is advocated to distinguish chiral states from tetrahedral molecules in the solid state. The present R/S nomenclature of the tetracooradinated carbon centers is used solely for its convenience to distinguish the two enantiomeric states, but not used to determine the absolute configurations.
基金Item Sponsored by National Natural Science Foundation of China(59771002)
文摘The solidification of primary austenite in hypoeutectic gray cast iron was studied by stepped grinding and quantitative metallography. The dendrite structure of primary austenite can be described by three models: typical dendrite crystal model, metamorphic dendrite crystal model and network dendrite crystal model. The dendrite crystals formed according to 3rd model is much more than those formed according to other models in this experiment. The primary austenites are connected each other, and the primary stems of austenite could be regarded as secondary arms and vice versa.
