A new polyacetylene glycoside,（1,3Z,11E）-tridecatriene-7,9-diyne-5-hydroxyl-6-O-β-D-glucopyranoside,was isolated from the rhizomes of Atractylodes lancea（Thunb.） DC.Its structure was elucidated on the basis of sp...A new polyacetylene glycoside,（1,3Z,11E）-tridecatriene-7,9-diyne-5-hydroxyl-6-O-β-D-glucopyranoside,was isolated from the rhizomes of Atractylodes lancea（Thunb.） DC.Its structure was elucidated on the basis of spectral analysis.展开更多
It is demonstrated that (3Z)-nonenal (NON) and (3Z)-hexenal (HEX) are oxidized in a cascade by lipoxygenase (LOX) and hydroperoxide peroxygenase (HP peroxygenase) into (2E)-4-hydroxy-2- nonenal (HNE) and (2E)-4-hydrox...It is demonstrated that (3Z)-nonenal (NON) and (3Z)-hexenal (HEX) are oxidized in a cascade by lipoxygenase (LOX) and hydroperoxide peroxygenase (HP peroxygenase) into (2E)-4-hydroxy-2- nonenal (HNE) and (2E)-4-hydroxy-2-hexenal (HHE), respectively. In turn, HNE inactivates LOX terminating the cascade. The hydroxy-alkenals produced serve to inhibit plant pathogens, which initiated the cascade. In addition to LOX, other unknown oxygenases may be involved in the cascade.展开更多
The stereoselective syntheses of (Z)-methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-3-butenoates 5a-c were investigated. The reaction of (3-carboethoxy-2-fu-ranyl)-methyltriphenylphosphonium bromide 1 with methyl...The stereoselective syntheses of (Z)-methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-3-butenoates 5a-c were investigated. The reaction of (3-carboethoxy-2-fu-ranyl)-methyltriphenylphosphonium bromide 1 with methyl 2-perfluoroalkynoates 2a-c in the presence of K2CO3 at room temperature gives two adducts, (E)-methyl 3-per-fluoroalkyl-4-( 3-carboethoxy-2-furanyl )-2-triphenylphosphoranylidene-3-butenoates 3a-c and (E)-methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-4-triphenylphos-phoranylidene-2-butenoates 4a-c. (Z)-Methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-3-butenoates 5a-c can be synthesized stereoselectively with high yields when an aqueous DMF solution of 3c, 4c or a mixture of 3a-b and 4a-b was heated at 140℃ for 8 h.展开更多
Synthesis of the title compound was carried out by base-catalyzed cyclization of 1-pivaloyl-3-(2-chloro-4-nitrophenyl) thiourea with α-bromoacetone produced in situ. The structure was confirmed by the spectroscopic a...Synthesis of the title compound was carried out by base-catalyzed cyclization of 1-pivaloyl-3-(2-chloro-4-nitrophenyl) thiourea with α-bromoacetone produced in situ. The structure was confirmed by the spectroscopic and elemental analysis and single crystal X-ray diffraction data. It crystallizes in the triclinic space group P-1 with unit cell dime sions a = 8.7137(10), b = 10.2010(14), c = 10.6593(13), α = 62.671(9), β = 82.701(10), γ = 79.762(10), V = 827.21(8) ?3, Z = 2.展开更多
The major advantages of homogeneous charge compression ignition （HCCI） are high efficiency in combination with low NOx-emissions. However, one of the major challenges with HCCI is the control of higher peak pressure...The major advantages of homogeneous charge compression ignition （HCCI） are high efficiency in combination with low NOx-emissions. However, one of the major challenges with HCCI is the control of higher peak pressures which may damage the engine, limiting the HCCI engine life period. In this paper, an attempt is made to analyze computationally the effect of induction swirl in controlling the peak pressures of an HCCI engine under various operating parameters. A single cylinder 1.6 L reentrant piston bowl diesel engine is chosen. For computational analysis, the ECFM-3Z model of STAR - CD is considered because it is suitable for analyzing the combustion processes in SI and CI engines. As an HCCI engine is a hybrid version of SI and CI engines, the ECFM- 3Z model with necessary modifications is used to analyze the peak pressures inside the combustion chamber. The ECFM-3Z model for HCCI mode of combustion is validated with the existing literature to make sure that the results obtained are accurate. Numerical experiments are performed to study the effect of varying properties like speed of the engine, piston bowl geometry, exhaust gas recirculation （EGR） and equivalence ratio under different swirl ratios in controlling the peak pressures inside the combustion chamber. The results show that the swirl ratio has a considerable impact on controlling the peak pressures of HCCI engine. A reduction in peak pressures are observed with a swirl ratio of 4 because of reduced in cylinder temperatures. The combined effect of four operating parameters, i.e., the speed of the engine, piston bowl geometry, EGR, and equivalence ratio with swirl ratios suggest that lower intake temperatures, reentrant piston bowl, higher engine speeds and higher swirl ratios are favorable in controlling the peak pressures.展开更多
文摘A new polyacetylene glycoside,（1,3Z,11E）-tridecatriene-7,9-diyne-5-hydroxyl-6-O-β-D-glucopyranoside,was isolated from the rhizomes of Atractylodes lancea（Thunb.） DC.Its structure was elucidated on the basis of spectral analysis.
文摘It is demonstrated that (3Z)-nonenal (NON) and (3Z)-hexenal (HEX) are oxidized in a cascade by lipoxygenase (LOX) and hydroperoxide peroxygenase (HP peroxygenase) into (2E)-4-hydroxy-2- nonenal (HNE) and (2E)-4-hydroxy-2-hexenal (HHE), respectively. In turn, HNE inactivates LOX terminating the cascade. The hydroxy-alkenals produced serve to inhibit plant pathogens, which initiated the cascade. In addition to LOX, other unknown oxygenases may be involved in the cascade.
基金Supported by the National Natural Science Foundation of ChinaFor part XVII of the series, see Chinese J. of Chem. (to be published)
文摘The stereoselective syntheses of (Z)-methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-3-butenoates 5a-c were investigated. The reaction of (3-carboethoxy-2-fu-ranyl)-methyltriphenylphosphonium bromide 1 with methyl 2-perfluoroalkynoates 2a-c in the presence of K2CO3 at room temperature gives two adducts, (E)-methyl 3-per-fluoroalkyl-4-( 3-carboethoxy-2-furanyl )-2-triphenylphosphoranylidene-3-butenoates 3a-c and (E)-methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-4-triphenylphos-phoranylidene-2-butenoates 4a-c. (Z)-Methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-3-butenoates 5a-c can be synthesized stereoselectively with high yields when an aqueous DMF solution of 3c, 4c or a mixture of 3a-b and 4a-b was heated at 140℃ for 8 h.
文摘Synthesis of the title compound was carried out by base-catalyzed cyclization of 1-pivaloyl-3-(2-chloro-4-nitrophenyl) thiourea with α-bromoacetone produced in situ. The structure was confirmed by the spectroscopic and elemental analysis and single crystal X-ray diffraction data. It crystallizes in the triclinic space group P-1 with unit cell dime sions a = 8.7137(10), b = 10.2010(14), c = 10.6593(13), α = 62.671(9), β = 82.701(10), γ = 79.762(10), V = 827.21(8) ?3, Z = 2.
文摘The major advantages of homogeneous charge compression ignition （HCCI） are high efficiency in combination with low NOx-emissions. However, one of the major challenges with HCCI is the control of higher peak pressures which may damage the engine, limiting the HCCI engine life period. In this paper, an attempt is made to analyze computationally the effect of induction swirl in controlling the peak pressures of an HCCI engine under various operating parameters. A single cylinder 1.6 L reentrant piston bowl diesel engine is chosen. For computational analysis, the ECFM-3Z model of STAR - CD is considered because it is suitable for analyzing the combustion processes in SI and CI engines. As an HCCI engine is a hybrid version of SI and CI engines, the ECFM- 3Z model with necessary modifications is used to analyze the peak pressures inside the combustion chamber. The ECFM-3Z model for HCCI mode of combustion is validated with the existing literature to make sure that the results obtained are accurate. Numerical experiments are performed to study the effect of varying properties like speed of the engine, piston bowl geometry, exhaust gas recirculation （EGR） and equivalence ratio under different swirl ratios in controlling the peak pressures inside the combustion chamber. The results show that the swirl ratio has a considerable impact on controlling the peak pressures of HCCI engine. A reduction in peak pressures are observed with a swirl ratio of 4 because of reduced in cylinder temperatures. The combined effect of four operating parameters, i.e., the speed of the engine, piston bowl geometry, EGR, and equivalence ratio with swirl ratios suggest that lower intake temperatures, reentrant piston bowl, higher engine speeds and higher swirl ratios are favorable in controlling the peak pressures.
