Gambogic acid （GA, 1）, the most prominent representative of Garcinia natural products, has been reported to be a promising anti-tumor agent. In order to further explore the structure-activity relationship of GA and ...Gambogic acid （GA, 1）, the most prominent representative of Garcinia natural products, has been reported to be a promising anti-tumor agent. In order to further explore the structure-activity relationship of GA and discover novel GA derivatives as anti-tumor agents, 17 novel C-37 modified derivatives of GA were synthesized and evaluated for their in vitro anti-tumor activities against A549, HCT-116, BGC-823, HepG2 and MCF-7 cancer cell lines. Among them, 11 compounds were found to be more potent than GA against some cancer cell lines. Notably, com- pound 8 was almost 5--10 folds more active than GA against A549 and BGC-823 cell lines with the IC50 values of 0.12 μmol·L^-1 and 0.57 μmol·L^-1, respectively. Chemical modification at C-37 position of GA by introducing of hydrophilic amines could lead to increased activity and improved drug-like properties. These findings will enhance our understanding of the structure-activity relationship （SAR） of GA and lead to the discovery of novel GA derivatives as potential anti-tumor agents.展开更多
It has been found that some nonlinear wave equations have one-loop soliton solutions. What is the dynamical behavior of the so-called one-loop soliton solution? To answer this question, the travelling wave solutions f...It has been found that some nonlinear wave equations have one-loop soliton solutions. What is the dynamical behavior of the so-called one-loop soliton solution? To answer this question, the travelling wave solutions for four nonlinear wave equations are discussed. Exact explicit parametric representations of some special travelling wave solutions are given. The results of this paper show that a loop solution consists of three different breaking travelling wave solutions. It is not one real loop soliton travelling wave solution.展开更多
The H6P2W18O62/TiO2composite catalyst was prepared by the combination of nonionic surfactant C18H37(OCH2CH2)10OH(Brij-76)as the template and the sol-gel method.As-synthesized composite was characterized by FT-TR,SEM,N...The H6P2W18O62/TiO2composite catalyst was prepared by the combination of nonionic surfactant C18H37(OCH2CH2)10OH(Brij-76)as the template and the sol-gel method.As-synthesized composite was characterized by FT-TR,SEM,N2 absorption-desorption and NH3-TPD.The results showed that the composite H6P2W18O62/TiO2 was mesoporous material(ca.3.3 nm),and large surface area(99.78 m2/g).Additionally,the aggregation of TiO2 particles was effectively inhibited,and the surface acidity was increased substantially.The photocatalytic elimination of monochlorobenzene was used as model reaction to evaluate the photocatalytic activity of the composite catalyst under visible light separately.Photocatalytic experimental results showed that the composite H6P2W18O62/TiO2 can effectively degradate monochlorobenzene.展开更多
Using the methods of dynamical systems for two generalized Boussinesq systems, the existence of all possible solitary wave solutions and many uncountably infinite periodic wave solutions is obtained. Exact explicit pa...Using the methods of dynamical systems for two generalized Boussinesq systems, the existence of all possible solitary wave solutions and many uncountably infinite periodic wave solutions is obtained. Exact explicit parametric representations of the travelling solutions are given. To guarantee the existence of the above solutions, all parameter conditions are determined.展开更多
Dynamic operation and control of power system is being increasingly done with the help of phasor measurement unit(PMU) based wide area monitoring and control system. The data communication requirements for the PMU bas...Dynamic operation and control of power system is being increasingly done with the help of phasor measurement unit(PMU) based wide area monitoring and control system. The data communication requirements for the PMU based applications are well addressed by IEEE C37.118.2 standard. However, IEC 61850 is now becoming a leading standard for power utility automation needs. A new part of IEC 61850, IEC 61850-90-5, specifying the IEEE C37.118.1 based synchrophasors data transfer according to IEC 61850, will lead to IEC 61850-90-5 based PMU communication networks. A novel IEC 61850-90-5 compliant communication model of PMU is proposed in this paper. We also present a comparative performance analysis of the PMU communication networks supporting the new synchrophasor standard for data transfer, i.e. IEC61850-90-5, and the existing standard, i.e. IEEE C37.118.2, for end to end(ETE) delay requirements for a modified IEEE 30 bus test system.展开更多
In this paper, the heteroclinic bifurcation problem with real eigenvalues and two incli- nation-flips is investigated in a four-dimensional reversible system. We perform a detailed study of this case by using the meth...In this paper, the heteroclinic bifurcation problem with real eigenvalues and two incli- nation-flips is investigated in a four-dimensional reversible system. We perform a detailed study of this case by using the method originally established in the papers "Problems in Homoclinic Bifurcation with Higher Dimensions" and "Bifurcation of Heteroclinic Loops," and obtain fruitful results, such as the existence and coexistence of R-symmetric homoclinic orbit and R-symmetric heteroclinic loops, R-symmetric homoclinic orbit and R-symmetric periodic orbit. The double R-symmetric homoclinic bifurcation (i.e., two-fold R-symmetric homoclinic bifurcation) for reversible heteroclinic loops is found, and the existence of infinitely many R-symmetric periodic orbits accumulating onto a homoclinic orbit is demonstrated. The relevant bifurcation surfaces and the existence regions are also located.展开更多
2C型丝氨酸/苏氨酸蛋白磷酸酶(PP2C-type protein phosphatases, PP2C)是ABA信号转导途径中的关键组分,在植物生长发育、细胞周期调节及应对逆境胁迫的过程中发挥重要的作用。本研究利用本实验室构建的‘云烟87’转录组数据库,从‘云烟8...2C型丝氨酸/苏氨酸蛋白磷酸酶(PP2C-type protein phosphatases, PP2C)是ABA信号转导途径中的关键组分,在植物生长发育、细胞周期调节及应对逆境胁迫的过程中发挥重要的作用。本研究利用本实验室构建的‘云烟87’转录组数据库,从‘云烟87’烟草中克隆到一个NtPP2C37-like基因,该基因开放阅读框为1 275 bp,编码425个氨基酸残基。通过对NtPP2C37-like蛋白质进行相关分析,该蛋白不存在信号肽,可能属于非分泌蛋白;不具有跨膜结构,不属于跨膜蛋白。同源性分析结果显示,说明NtPP2C37-like蛋白与茄科植物有高度同源性。本研究获得了烟草NtPP2C37-like基因完整ORF,这为将来深入研究烟草NtPP2C37-like基因功能提供了科学依据。展开更多
This paper concerns the number and distributions of limit cycles in a Z 2-equivariant quintic planar vector field. 25 limit cycles are found in this special planar polynomial system and four different configurations o...This paper concerns the number and distributions of limit cycles in a Z 2-equivariant quintic planar vector field. 25 limit cycles are found in this special planar polynomial system and four different configurations of these limit cycles are also given by using the methods of the bifurcation theory and the qualitative analysis of the differential equation. It can be concluded that H(5) ? 25 = 52, where H(5) is the Hilbert number for quintic polynomial systems. The results obtained are useful to study the weakened 16th Hilbert problem.展开更多
基金Acknowledgement This work was supported by the National Natural Science Foundation of China （Nos. 90713038, 21072231, 30873157） and National Major Science and Technology Project of China （Innovation and Development of New Drugs. Nos. 2008ZX09401-001, 2009ZX09501-003）.
文摘Gambogic acid （GA, 1）, the most prominent representative of Garcinia natural products, has been reported to be a promising anti-tumor agent. In order to further explore the structure-activity relationship of GA and discover novel GA derivatives as anti-tumor agents, 17 novel C-37 modified derivatives of GA were synthesized and evaluated for their in vitro anti-tumor activities against A549, HCT-116, BGC-823, HepG2 and MCF-7 cancer cell lines. Among them, 11 compounds were found to be more potent than GA against some cancer cell lines. Notably, com- pound 8 was almost 5--10 folds more active than GA against A549 and BGC-823 cell lines with the IC50 values of 0.12 μmol·L^-1 and 0.57 μmol·L^-1, respectively. Chemical modification at C-37 position of GA by introducing of hydrophilic amines could lead to increased activity and improved drug-like properties. These findings will enhance our understanding of the structure-activity relationship （SAR） of GA and lead to the discovery of novel GA derivatives as potential anti-tumor agents.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 10671179)the Natural Science Foundation of Yunnan Province (Grant No. 2005A0013M)
文摘It has been found that some nonlinear wave equations have one-loop soliton solutions. What is the dynamical behavior of the so-called one-loop soliton solution? To answer this question, the travelling wave solutions for four nonlinear wave equations are discussed. Exact explicit parametric representations of some special travelling wave solutions are given. The results of this paper show that a loop solution consists of three different breaking travelling wave solutions. It is not one real loop soliton travelling wave solution.
文摘The H6P2W18O62/TiO2composite catalyst was prepared by the combination of nonionic surfactant C18H37(OCH2CH2)10OH(Brij-76)as the template and the sol-gel method.As-synthesized composite was characterized by FT-TR,SEM,N2 absorption-desorption and NH3-TPD.The results showed that the composite H6P2W18O62/TiO2 was mesoporous material(ca.3.3 nm),and large surface area(99.78 m2/g).Additionally,the aggregation of TiO2 particles was effectively inhibited,and the surface acidity was increased substantially.The photocatalytic elimination of monochlorobenzene was used as model reaction to evaluate the photocatalytic activity of the composite catalyst under visible light separately.Photocatalytic experimental results showed that the composite H6P2W18O62/TiO2 can effectively degradate monochlorobenzene.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10671179, 10772158)
文摘Using the methods of dynamical systems for two generalized Boussinesq systems, the existence of all possible solitary wave solutions and many uncountably infinite periodic wave solutions is obtained. Exact explicit parametric representations of the travelling solutions are given. To guarantee the existence of the above solutions, all parameter conditions are determined.
文摘Dynamic operation and control of power system is being increasingly done with the help of phasor measurement unit(PMU) based wide area monitoring and control system. The data communication requirements for the PMU based applications are well addressed by IEEE C37.118.2 standard. However, IEC 61850 is now becoming a leading standard for power utility automation needs. A new part of IEC 61850, IEC 61850-90-5, specifying the IEEE C37.118.1 based synchrophasors data transfer according to IEC 61850, will lead to IEC 61850-90-5 based PMU communication networks. A novel IEC 61850-90-5 compliant communication model of PMU is proposed in this paper. We also present a comparative performance analysis of the PMU communication networks supporting the new synchrophasor standard for data transfer, i.e. IEC61850-90-5, and the existing standard, i.e. IEEE C37.118.2, for end to end(ETE) delay requirements for a modified IEEE 30 bus test system.
基金supported by National Natural Science Foundation of China (Grant No. 10671069)
文摘In this paper, the heteroclinic bifurcation problem with real eigenvalues and two incli- nation-flips is investigated in a four-dimensional reversible system. We perform a detailed study of this case by using the method originally established in the papers "Problems in Homoclinic Bifurcation with Higher Dimensions" and "Bifurcation of Heteroclinic Loops," and obtain fruitful results, such as the existence and coexistence of R-symmetric homoclinic orbit and R-symmetric heteroclinic loops, R-symmetric homoclinic orbit and R-symmetric periodic orbit. The double R-symmetric homoclinic bifurcation (i.e., two-fold R-symmetric homoclinic bifurcation) for reversible heteroclinic loops is found, and the existence of infinitely many R-symmetric periodic orbits accumulating onto a homoclinic orbit is demonstrated. The relevant bifurcation surfaces and the existence regions are also located.
基金Supported by the Fund of Youth of Jiangsu University(Grant No.05JDG011)the National Natural Science Foundation of China(Nos.90610031,10671127)+1 种基金the Outstanding Personnel Program in Six Fields of Jiangsu Province(Grant No.6-A-029)Shanghai Shuguang Genzong Project(Grant No.04SGG05)
文摘This paper concerns the number and distributions of limit cycles in a Z 2-equivariant quintic planar vector field. 25 limit cycles are found in this special planar polynomial system and four different configurations of these limit cycles are also given by using the methods of the bifurcation theory and the qualitative analysis of the differential equation. It can be concluded that H(5) ? 25 = 52, where H(5) is the Hilbert number for quintic polynomial systems. The results obtained are useful to study the weakened 16th Hilbert problem.
