Selecting compound 97-9-G4 as lead compound, a series of bispiperazinittm salts 5a-h were designed, synthesized and evaluated for their analgesic activities. The results show that phenylethyl group of 97-9-G4 is a cru...Selecting compound 97-9-G4 as lead compound, a series of bispiperazinittm salts 5a-h were designed, synthesized and evaluated for their analgesic activities. The results show that phenylethyl group of 97-9-G4 is a crucial pharmacophore; the intro- duction of electron-withdrawing group on benzene ring is favorable to the activity.展开更多
2,5,6-Tribromo-l-methylgramine （TBG）, isolated from bryozoan Zoobotryon pellucidum was shown to be very efficient in preventing recruitment of larval settlement. In order to improve the compatibility of TBG and its ...2,5,6-Tribromo-l-methylgramine （TBG）, isolated from bryozoan Zoobotryon pellucidum was shown to be very efficient in preventing recruitment of larval settlement. In order to improve the compatibility of TBG and its analogues with other ingredients in antifouling paints, structural modification of TBG was focused mainly on halogen substitution and N-substitution. Two halogen-substitute gramines and their derivatives which contain ester functional groups at N-position of gramines were synthesized. Algal inhibition activities of the synthesized compounds against algae Nitzschia cIosterium were evaluated and the Median Effective Concentration （EC50） range was 1.06-6.74 lag ml^-1. Compounds that had a long chain ester group exhibited extremely high antifouling activity. Quantitive Structure Activity Relationship （QSAR） studies with multiple linear regression analysis were applied to fred correlation between different calculated molecular descriptors and biological activity of the synthesized compounds. The results show that the toxicity （log （I/EC50）） is correlated well with the partition coefficient log P. Thus, these products have potential function as antifouling agents.展开更多
Trade and economic relations between China and Africa have a protracted history and have developed incrementally over the course of time. Consequently, increasing numbers of Chinese businesses and entrepreneurs have s...Trade and economic relations between China and Africa have a protracted history and have developed incrementally over the course of time. Consequently, increasing numbers of Chinese businesses and entrepreneurs have sought partnerships with African companies with the aim of establishing strategic partnerships, collaborations, and joint ventures. In recent years, these Sino-African trading relations have been the subject of consistent debate and scrutiny, attracting positive and negative analyses from scholars and practitioners across disciplines. Some studies questioned China＇s motives in Africa＇s markets, and others viewed with suspicion the structure of Sino-Africa＇s bilateral trading engagements. Conducting an extensive literature survey of related sources and employing content analysis of recent and current data （2000-2009）, the paper examined institutional and academic publications pertaining to Sino-African relationship. It determines imbalance in the structure of Sino-African bilateral trade, negative impact on domestic economic development, and competitive disadvantage in African marketplaces. Policy implications of these findings were provided as well as recommendations for mutual trade benefits and global strategic investments展开更多
Synthesis of Ag nanoparticles dispersed in germanium dioxide （GeO2） matrix was performed via sol-gel route. Analysis of the powder X-ray diffraction （XRD） pattern shows fcc cubic unit cell of Ag with lattice param...Synthesis of Ag nanoparticles dispersed in germanium dioxide （GeO2） matrix was performed via sol-gel route. Analysis of the powder X-ray diffraction （XRD） pattern shows fcc cubic unit cell of Ag with lattice parameters： a = 4.0884 A, space group Fm-3m. Energy dispersive analysis of X-rays （EDAX） results show the presence of only GeO2 and Ag in the sample. The average crystallite sizes of Ag particles determined by Scherrer＇s relation are found to be i 8-47 nm. Observed sharp electron paramagnetic resonance （EPR） lineshapes at 8, 70 and 300 K with g-values of 2.004, 2.004, and 2.004, respectively, show that the Ag （5s~） electrons are localized in the Ag nanoparticles. The calculated value of the magnetic susceptibility is 1.014~ 10-5 emu/gG from the observed magnetic moments data at 300 K, which shows fairly strong paramagnetic nature of the material. Refinement of Ag crystal structure in space group Fm-3m with Ag atoms in 4（a） position shows the agreement bond length as 2.8909 ,＆. Calculated density of states below Fermi factors Rp= 67.22%, Rwp= 75.7%, Rexp= 0.06%, Z = 4 and Ag-Ag energy, EF, from -2 to -8 eV are due to valence d orbitals of Ag.展开更多
In the present study, we designed and synthesized a series of 1-substituted-β-carboline derivatives through modification of position-l, 2 and 9 of β-carboline nucleus in order to discover novel leading compounds wit...In the present study, we designed and synthesized a series of 1-substituted-β-carboline derivatives through modification of position-l, 2 and 9 of β-carboline nucleus in order to discover novel leading compounds with better antitumor activities and less toxicity. Their structures were confirmed by 1H NMR, 13C NMR, MS, IR and elemental analyses. All the target compounds were tested for cytotoxic activity against six cancer cell lines, including Bel-7402, HepG2, A549, A375, 786-0 and HT-29 by methyl thiazolyl tetrazolium （MTT） method. Studies of structure-activity relationships indicated that the effects of substituents in position- 1 on cytotoxic activities were in an order as follows： 2-thienyl 〉2-chlorophenyl 〉4-chlorophenyl 〉benzyl group.展开更多
The two-electron Hooke's atom - a quantum mechanical system with two electrons bound in a harmonic potential - is well known for its exact analytical properties at certain oscillator strengths. The Hooke's ato...The two-electron Hooke's atom - a quantum mechanical system with two electrons bound in a harmonic potential - is well known for its exact analytical properties at certain oscillator strengths. The Hooke's atoms with more than two electrons offer more scope for valuable practical applications. In this work, we study the asymptotic structure of these Hooke's atoms in the classically forbidden region. The leading-order term of the long-range expression for the KS exchange-correlation potential v xc (r) is shown to be-1/r. The second and third higher order terms are also exactly obtained. Various components of v xc (r) are also studied. It is shown that the leading term of O(1/r) in vxc (r) is due to the pure Pauli correlation, while the leading contribution of the Coulomb correlation is of O(1/r3 ). Neither of them makes contribution to the term of O(1/r2 ), which is shown to be solely due to the kinetic correlation effect. Results for the two-electron Hooke's atom were obtained before in the literature. Our results reduce to those of the two-electron Hooke's atom as a special case.展开更多
基金National Natural Science Foundation of China (Grant No. 20372006 and 20772009)
文摘Selecting compound 97-9-G4 as lead compound, a series of bispiperazinittm salts 5a-h were designed, synthesized and evaluated for their analgesic activities. The results show that phenylethyl group of 97-9-G4 is a crucial pharmacophore; the intro- duction of electron-withdrawing group on benzene ring is favorable to the activity.
基金Supported by the National Natural Science Foundation of China (No. 50673085, 20060423017, A1420080191)National High-Technology Research Program of China (863 Program, No. 2006AA09Z224)
文摘2,5,6-Tribromo-l-methylgramine （TBG）, isolated from bryozoan Zoobotryon pellucidum was shown to be very efficient in preventing recruitment of larval settlement. In order to improve the compatibility of TBG and its analogues with other ingredients in antifouling paints, structural modification of TBG was focused mainly on halogen substitution and N-substitution. Two halogen-substitute gramines and their derivatives which contain ester functional groups at N-position of gramines were synthesized. Algal inhibition activities of the synthesized compounds against algae Nitzschia cIosterium were evaluated and the Median Effective Concentration （EC50） range was 1.06-6.74 lag ml^-1. Compounds that had a long chain ester group exhibited extremely high antifouling activity. Quantitive Structure Activity Relationship （QSAR） studies with multiple linear regression analysis were applied to fred correlation between different calculated molecular descriptors and biological activity of the synthesized compounds. The results show that the toxicity （log （I/EC50）） is correlated well with the partition coefficient log P. Thus, these products have potential function as antifouling agents.
文摘Trade and economic relations between China and Africa have a protracted history and have developed incrementally over the course of time. Consequently, increasing numbers of Chinese businesses and entrepreneurs have sought partnerships with African companies with the aim of establishing strategic partnerships, collaborations, and joint ventures. In recent years, these Sino-African trading relations have been the subject of consistent debate and scrutiny, attracting positive and negative analyses from scholars and practitioners across disciplines. Some studies questioned China＇s motives in Africa＇s markets, and others viewed with suspicion the structure of Sino-Africa＇s bilateral trading engagements. Conducting an extensive literature survey of related sources and employing content analysis of recent and current data （2000-2009）, the paper examined institutional and academic publications pertaining to Sino-African relationship. It determines imbalance in the structure of Sino-African bilateral trade, negative impact on domestic economic development, and competitive disadvantage in African marketplaces. Policy implications of these findings were provided as well as recommendations for mutual trade benefits and global strategic investments
文摘Synthesis of Ag nanoparticles dispersed in germanium dioxide （GeO2） matrix was performed via sol-gel route. Analysis of the powder X-ray diffraction （XRD） pattern shows fcc cubic unit cell of Ag with lattice parameters： a = 4.0884 A, space group Fm-3m. Energy dispersive analysis of X-rays （EDAX） results show the presence of only GeO2 and Ag in the sample. The average crystallite sizes of Ag particles determined by Scherrer＇s relation are found to be i 8-47 nm. Observed sharp electron paramagnetic resonance （EPR） lineshapes at 8, 70 and 300 K with g-values of 2.004, 2.004, and 2.004, respectively, show that the Ag （5s~） electrons are localized in the Ag nanoparticles. The calculated value of the magnetic susceptibility is 1.014~ 10-5 emu/gG from the observed magnetic moments data at 300 K, which shows fairly strong paramagnetic nature of the material. Refinement of Ag crystal structure in space group Fm-3m with Ag atoms in 4（a） position shows the agreement bond length as 2.8909 ,＆. Calculated density of states below Fermi factors Rp= 67.22%, Rwp= 75.7%, Rexp= 0.06%, Z = 4 and Ag-Ag energy, EF, from -2 to -8 eV are due to valence d orbitals of Ag.
基金National Science and Technology Major Projec of the Ministry of Science and Technology of China(Grant No2011ZX09401-007)National Key Technology Research and Development Program of the Ministry of Science and Technology of China(Grant No.2012BAI30B00)
文摘In the present study, we designed and synthesized a series of 1-substituted-β-carboline derivatives through modification of position-l, 2 and 9 of β-carboline nucleus in order to discover novel leading compounds with better antitumor activities and less toxicity. Their structures were confirmed by 1H NMR, 13C NMR, MS, IR and elemental analyses. All the target compounds were tested for cytotoxic activity against six cancer cell lines, including Bel-7402, HepG2, A549, A375, 786-0 and HT-29 by methyl thiazolyl tetrazolium （MTT） method. Studies of structure-activity relationships indicated that the effects of substituents in position- 1 on cytotoxic activities were in an order as follows： 2-thienyl 〉2-chlorophenyl 〉4-chlorophenyl 〉benzyl group.
文摘The two-electron Hooke's atom - a quantum mechanical system with two electrons bound in a harmonic potential - is well known for its exact analytical properties at certain oscillator strengths. The Hooke's atoms with more than two electrons offer more scope for valuable practical applications. In this work, we study the asymptotic structure of these Hooke's atoms in the classically forbidden region. The leading-order term of the long-range expression for the KS exchange-correlation potential v xc (r) is shown to be-1/r. The second and third higher order terms are also exactly obtained. Various components of v xc (r) are also studied. It is shown that the leading term of O(1/r) in vxc (r) is due to the pure Pauli correlation, while the leading contribution of the Coulomb correlation is of O(1/r3 ). Neither of them makes contribution to the term of O(1/r2 ), which is shown to be solely due to the kinetic correlation effect. Results for the two-electron Hooke's atom were obtained before in the literature. Our results reduce to those of the two-electron Hooke's atom as a special case.
