To gain insight into the attachment of =Si^＋ （SC） ion （regarded as guest） to the lowest generation, NH2-terminated poly（amidoamine） （PAMAM） dendrimers （regarded as host） in the liquid phase, density functio...To gain insight into the attachment of =Si^＋ （SC） ion （regarded as guest） to the lowest generation, NH2-terminated poly（amidoamine） （PAMAM） dendrimers （regarded as host） in the liquid phase, density functional theory is used to investigate the structures and energetics of the host-guest complex. The effect of solvent on the structures and energetics is also investigated. Various initial configurations of the ion bound to PAMAM are tested, and two stable conformers are found, i.e, types A （=Si^＋ is bound to the amine site） and C （=Si^＋ is bound to the amide site）. Types A and C are the most stable due to the chemical bond formations of Si-N° （amine nitrogen atoms） and Si-O, respectively. The IR spectra for the lowest energy conformers are thoroughly analyzed and compared with the available experimental data.展开更多
In this study, the feasibility of using chitosan, a multifunctional environmentally friendly biopolymer, at different molecular weights to simultaneously adsorb various metal ions from aqueous solutions was evaluated....In this study, the feasibility of using chitosan, a multifunctional environmentally friendly biopolymer, at different molecular weights to simultaneously adsorb various metal ions from aqueous solutions was evaluated. The experiments were carried out to estimate adsorptivity and selectivity of three molecular weights chitosan, 3.60 × 105 （Chl）, 5.97 × 105 （Ch2） and 9.47 × 105 （Ch3） g/mol, towards Cu（II）, Ni（II）, and Pb（II） ions in aqueous solutions. Experimental results indicated that chitosan of high molecular weight （Ch3） was the best at adsorption capacity than the others. On chitosan solutions followed by Ni（II） and then Cu（II）. the other hand, Pb（lI） had the highest adsorption ability in the three展开更多
P（LLA-CL）（75/25） （poly（L-lactide-co-caprolactone）（75/25）） was synthesized from high purity L-lactide and e-caprolactone using tin octoate as initiator by ring-opening polymerization, and characterized by inf...P（LLA-CL）（75/25） （poly（L-lactide-co-caprolactone）（75/25）） was synthesized from high purity L-lactide and e-caprolactone using tin octoate as initiator by ring-opening polymerization, and characterized by infrared spectrum and ^1-NMR （^1H proton spectrum of nuclear magnetic resonance） spectrum. The synthesized P（LLA-CL）（75/25） is a random copolymer. The influences of polymerization temperature, polymerization time and dosage of initiator on the weight average molecular weight and the polydispersity index of P（LLA-CL）（75/25） were investigated. The optimum preparation condition of P（LLA-CL）（75/25） was： the polymerization pressure is less than 0.5 Pa, the polymerization temperature is 125℃, the n（M）/n（I） ratio is 8,000/1, the polymerization time is 36 h. Under the condition, the weight-average molecular weight of prepared P（LLA-CL）（75/25） is 45.3×10^4, and molecular weight distribution coefficient is 1.24.展开更多
Nitrogen molecules Nx have been the subject of much recent research because of their potential as high-energy materials. Many nitrogen molecules dissociate with very low barriers, including molecules such as acyclic N...Nitrogen molecules Nx have been the subject of much recent research because of their potential as high-energy materials. Many nitrogen molecules dissociate with very low barriers, including molecules such as acyclic N4 that are essentially unbound. A number of studies have reported the ability of heteroatoms to stabilize complex nitrogen molecules. In the present study, the energetic and electronic properties of scandium（Ⅰ） and titanium（Ⅱ） complexes with N2 and N4 are calculated and discussed. Dissociation energies and singlet-triplet energies are determined by theoretical calculations using second-order perturbation theory （MP2） in conjunction with the Dunning basis sets.展开更多
We evaluated the effects of high molecular-weight phlorotannins from Sargassum thunbergii(STP) on ADP-induced platelet aggregation and arachidonic acid(AA) metabolism in New Zealand white rabbits and Wistar rats.The i...We evaluated the effects of high molecular-weight phlorotannins from Sargassum thunbergii(STP) on ADP-induced platelet aggregation and arachidonic acid(AA) metabolism in New Zealand white rabbits and Wistar rats.The inhibition of STP on platelet aggregation was investigated using a turbidimetric method,and the levels of the terminal products of AA metabolism were measured using the corresponding kits for maleic dialdehyde(MDA),thromboxane B2(TXB2) and 6-keto-prostaglandin F1α(6-keto-PGF1α) by colorimetry and radioimmunoassay,as appropriate.We found that STP could inhibit ADP-induced platelet aggregation,and the inhibitory ratio was 91.50% at the STP concentration of 4.0 mg/mL.Furthermore,STP markedly affected AA metabolism by decreasing the synthesis of MDA(P<0.01) and increasing the synthesis of 6-keto-PGF1α,thus changing the plasma TXB2/6-keto-PGF1α balance when the platelets were activated(P<0.01).Therefore,STP altered AA metabolism and these findings partly revealed the molecular mechanism by which STP inhibits ADP-induced platelet aggregation.展开更多
The rapid developments of genomics and proteomics have driven the demand for multiplex and high throughput analysis of large numbers of biomolecules in the fields of medical diagnostics, drug discovery, and environmen...The rapid developments of genomics and proteomics have driven the demand for multiplex and high throughput analysis of large numbers of biomolecules in the fields of medical diagnostics, drug discovery, and environmental monitoring. Encoding the biomolecular binding events is the key technique to fulfill this demand, in which microparticles play the most important roles. This review outlines the development of multiplex and high throughput biodetections, and highlights the most recent advances in the field of encoding microparticles, together with problems that need to be resolved.展开更多
文摘To gain insight into the attachment of =Si^＋ （SC） ion （regarded as guest） to the lowest generation, NH2-terminated poly（amidoamine） （PAMAM） dendrimers （regarded as host） in the liquid phase, density functional theory is used to investigate the structures and energetics of the host-guest complex. The effect of solvent on the structures and energetics is also investigated. Various initial configurations of the ion bound to PAMAM are tested, and two stable conformers are found, i.e, types A （=Si^＋ is bound to the amine site） and C （=Si^＋ is bound to the amide site）. Types A and C are the most stable due to the chemical bond formations of Si-N° （amine nitrogen atoms） and Si-O, respectively. The IR spectra for the lowest energy conformers are thoroughly analyzed and compared with the available experimental data.
文摘In this study, the feasibility of using chitosan, a multifunctional environmentally friendly biopolymer, at different molecular weights to simultaneously adsorb various metal ions from aqueous solutions was evaluated. The experiments were carried out to estimate adsorptivity and selectivity of three molecular weights chitosan, 3.60 × 105 （Chl）, 5.97 × 105 （Ch2） and 9.47 × 105 （Ch3） g/mol, towards Cu（II）, Ni（II）, and Pb（II） ions in aqueous solutions. Experimental results indicated that chitosan of high molecular weight （Ch3） was the best at adsorption capacity than the others. On chitosan solutions followed by Ni（II） and then Cu（II）. the other hand, Pb（lI） had the highest adsorption ability in the three
文摘P（LLA-CL）（75/25） （poly（L-lactide-co-caprolactone）（75/25）） was synthesized from high purity L-lactide and e-caprolactone using tin octoate as initiator by ring-opening polymerization, and characterized by infrared spectrum and ^1-NMR （^1H proton spectrum of nuclear magnetic resonance） spectrum. The synthesized P（LLA-CL）（75/25） is a random copolymer. The influences of polymerization temperature, polymerization time and dosage of initiator on the weight average molecular weight and the polydispersity index of P（LLA-CL）（75/25） were investigated. The optimum preparation condition of P（LLA-CL）（75/25） was： the polymerization pressure is less than 0.5 Pa, the polymerization temperature is 125℃, the n（M）/n（I） ratio is 8,000/1, the polymerization time is 36 h. Under the condition, the weight-average molecular weight of prepared P（LLA-CL）（75/25） is 45.3×10^4, and molecular weight distribution coefficient is 1.24.
基金The Alabama Supercomputer Authority is gratefully acknowledged for a grant of computer time on the SGI Altix in Huntsville, AL. This work was supported by the National Science Foundation （NSF/HBCU-UP grant 0505872）. SJ is supported by NSF/HBCU-UP as an undergraduate scholar. This work was also supported by the National Institutes of Health （NIHINCMHD 1P20MD000547-01） and the Petroleum Research Fund, administered by the American Chemical Society （PRF 43798-B6）. AH is supported by the NIH as an undergraduate scholar in the Minority Access to Research Careers program （NIH/NIGMS 2T34GM008167-22A 1）. The taxpayers of the state of Alabama in particular and the United States in general are gratefully acknowledged.
文摘Nitrogen molecules Nx have been the subject of much recent research because of their potential as high-energy materials. Many nitrogen molecules dissociate with very low barriers, including molecules such as acyclic N4 that are essentially unbound. A number of studies have reported the ability of heteroatoms to stabilize complex nitrogen molecules. In the present study, the energetic and electronic properties of scandium（Ⅰ） and titanium（Ⅱ） complexes with N2 and N4 are calculated and discussed. Dissociation energies and singlet-triplet energies are determined by theoretical calculations using second-order perturbation theory （MP2） in conjunction with the Dunning basis sets.
基金Supported by the National Natural Science Foundation of China (No 30572314)the Basic Research Program of Science and Technology,Ministry of Science and Technology of China (2007FY210500)+1 种基金the Program of Chinese Offshore Investigation and Assessment,State Oceanic Administration of China (Nos 908-01-ST12 and 908-02-05-04)the Science and Technology Planning Project of Qingdao (No 06-2212-JCH)
文摘We evaluated the effects of high molecular-weight phlorotannins from Sargassum thunbergii(STP) on ADP-induced platelet aggregation and arachidonic acid(AA) metabolism in New Zealand white rabbits and Wistar rats.The inhibition of STP on platelet aggregation was investigated using a turbidimetric method,and the levels of the terminal products of AA metabolism were measured using the corresponding kits for maleic dialdehyde(MDA),thromboxane B2(TXB2) and 6-keto-prostaglandin F1α(6-keto-PGF1α) by colorimetry and radioimmunoassay,as appropriate.We found that STP could inhibit ADP-induced platelet aggregation,and the inhibitory ratio was 91.50% at the STP concentration of 4.0 mg/mL.Furthermore,STP markedly affected AA metabolism by decreasing the synthesis of MDA(P<0.01) and increasing the synthesis of 6-keto-PGF1α,thus changing the plasma TXB2/6-keto-PGF1α balance when the platelets were activated(P<0.01).Therefore,STP altered AA metabolism and these findings partly revealed the molecular mechanism by which STP inhibits ADP-induced platelet aggregation.
基金support of Grant for Teaching and Research of Excellent Young Teachers in Southeast University333 Talent Project Foundation and the Qing Lan Project of Jiangsu Province+2 种基金Jiangsu Science and Technology Department (BE2009148 & Bk2008318)the National Natural Science Foundation of China (50925309, 20703010 & 21073033)the Scientific Research Foundation of the Graduate School of Southeast University
文摘The rapid developments of genomics and proteomics have driven the demand for multiplex and high throughput analysis of large numbers of biomolecules in the fields of medical diagnostics, drug discovery, and environmental monitoring. Encoding the biomolecular binding events is the key technique to fulfill this demand, in which microparticles play the most important roles. This review outlines the development of multiplex and high throughput biodetections, and highlights the most recent advances in the field of encoding microparticles, together with problems that need to be resolved.
