Poly(methacrylic acid co-poloxamer) hydrogel networks were synthesized by free radical solution polymerization and their equilibrium swelling and solute permeation properties were characterized. These gels exhibited p...Poly(methacrylic acid co-poloxamer) hydrogel networks were synthesized by free radical solution polymerization and their equilibrium swelling and solute permeation properties were characterized. These gels exhibited pH dependant swelling and solute diffusivity due to the formation or disruption of hydrogen bonded complexation between methacrylic acid (MAA) and etheric (EO). In neutral and basic conditions (above the swelling transition pH), the copolymer swelling was greatly higher than acid condition. In complexed hydrogels, the diffusion coefficients of vitamin B12 (VB12) were in the range of 10-10 to 10-7 cm2s-1; While in uncomplexed hydrogels, the values were about 210-6 cm2s-1. The comonomer composition and synthesis conditions have great effect on the structure, and thereby, swelling and solute diffusion characteristics of the resultant hydrogels. For the copolymers with composition of less than or more than 1:1 MAA/EO molar ratio, the plot of lnD vs 1/H-1 followed two different linear equations of 慺ree volume theory? respectively.展开更多
We herein report two crystals based on 2-（imidazo[1,2-a]pyridin-2-yl）-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or s...We herein report two crystals based on 2-（imidazo[1,2-a]pyridin-2-yl）-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or supramolecular interactions. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical in two crystals mainly exist as diamagnetic dimer formed via short atomic contacts or supramolecular interactions （hydrogen bonds, anion-Tr or lone- pair-~r interactions）, leading to low magnetic susceptibilities. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical crystal exhibits quasi-one-dimensional columnar stacking chain and weak antiferromagnetism. However, its perchlorate crystal possesses one-dimensional double- stranded chain structure assembled through double hydrogen bonds and anion-To interactions, and reveals weak ferromagnetism.展开更多
The first cyclic molecule formation reactions from ethyne （C2H2）, initiated by ethynyl radical （C2H）, were studied by theoretical quantum mechanic. The study included the competition reaction between structure re-...The first cyclic molecule formation reactions from ethyne （C2H2）, initiated by ethynyl radical （C2H）, were studied by theoretical quantum mechanic. The study included the competition reaction between structure re-arrangement for the favourable ring-closure mechanism and ethyne addition in each step. The analysis was done by evaluating the energy difference of activation （AE）, entalphy （AH）, Gibbs （AG） of the optimized stable and transition molecules. The reaction temperatures were set at normal （T = 298 K） and combustion （T = 1200 K） condition.展开更多
We present a theoretical study of the reaction of the hydroxyl radical with ethene using electronic structure calculations and direct-dynamics simulations. High-accuracy electronic structure calculations at the CCSD（...We present a theoretical study of the reaction of the hydroxyl radical with ethene using electronic structure calculations and direct-dynamics simulations. High-accuracy electronic structure calculations at the CCSD（T）/aug-cc-pVTZ//MP2/aug-ce-pVDZ level have been carried out to characterize the representative regions of the potential energy surface of various reaction pathways, including OH-addition and H-abstraction. These ab initio calculations have been employed to derive an improved set of parameters for the MSINDO semiempirieal Hamiltonian specific to the OH＋C2H4 reaction. The specific-reaction-parameter Hamilto- nian captures the ab initio data accurately, and has been used to perform direct quasiclassica] trajectory simulations of the OH＋C2H4 reaction at collision energies in the range of 2-10 kcal/mol. The calculated cross sections reveal that the OH-addition reaction domi- nates at all energies over H-abstraction. In addition, the excitation function of addition is reminiscent of a barrierless capture process, while that for abstraction corresponds to an activated one, and these trends can be connected to the transition-state energies of both reactions. We note that the development of an accurate semiempirical Hamiltonian for the OH＋C2H4 reaction in this work required the inclusion of empirical dispersion corrections, which will be important in future applications for which long-range intermoleeular attraction becomes significant.展开更多
Silk was grafted using 2-hydroxyethyl methacrylate(HEMA)by atom transfer radical polymerization(ATRP)method.The amino groups and hydroxyl groups on the side chains of the silk fibroin was reacted with 2-bromoisobutyry...Silk was grafted using 2-hydroxyethyl methacrylate(HEMA)by atom transfer radical polymerization(ATRP)method.The amino groups and hydroxyl groups on the side chains of the silk fibroin was reacted with 2-bromoisobutyryl bromide(BriB-Br)to obtain efficient macroinitiator for ATRP.And the macroinitiator was grafted with HEMA in water aqueous using CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine(PMDETA)as catalyst system.The effects of monomer concentration,the proportion of CuBr and PMDETA,grafting temperature and time on the silk grafting were discussed,and the optimal grafting technology was obtained.FT-IR characterization of the grafted silk showed a peak corresponding to HEMA,which indicated that HEMA was grafted onto the surface of silk.ATRP method could be applied on the silk modification and this technique provided a new way for silk grafting.展开更多
This study evaluated the effect of four different solvent, i.e., water, ethanol, water-ethanol mixture and ethyl acetate, on the antioxidant activities of wild and cultivated heather （Calluna vulgaris （L.） Hull） p...This study evaluated the effect of four different solvent, i.e., water, ethanol, water-ethanol mixture and ethyl acetate, on the antioxidant activities of wild and cultivated heather （Calluna vulgaris （L.） Hull） plant. The highest values for total flavonoid content were obtained for samples extracted using ethanol-water mixture and ethyl acetate. Cupric reducing antioxidant capacity （CUPRAC） method, scavenging ability on 1,1-diphenyl-2-pirylhydrazyl radicals （DPPH） radicals and chelating activity on Fe2~ ions have been used for evaluation of antioxidant activity of the extracts. Ethanolic fraction exhibited the lowest reducing capacity, despite a heather sample used. The extracts of cultivated heather exhibited significant scavenging effect on DPPH radicals, and ethanol and ethanol-water fractions were found to be the most effective. The metal-chelating effect of the extracts increased in the order： ethanol 〈 ethyl acetate 〈 ethanol-water 〈 water. The results may be helpful for better utilization of heather flowers extracts as potential pharmaceutical and nutraceutical ingredient.展开更多
In the present work we investigated, for the first time, the anti-inflammatory activity and the antioxidant properties of aqueous and ethanolic extracts, obtained from stem bark of Geoffroea decorticans （Gill. ex Hoo...In the present work we investigated, for the first time, the anti-inflammatory activity and the antioxidant properties of aqueous and ethanolic extracts, obtained from stem bark of Geoffroea decorticans （Gill. ex Hook. et Am.） Burk. （Fabaceae）. G. decorticans, commonly known as ＂chafiar＂ or ＂chafiarcillo＂, is a traditional argentinean plant used as emollient, balsamic, antitussive, expectorant and anti-inflammatory. The stem bark was collected from San Francisco del Monte de Oro, San Luis, Argentina. Anti-inflammatory activity was evaluated by carrageenan-induced paw edema in rats. Antioxidant activity was tested using 1,1-Diphenyl-2-picrylhydrazyl radical-scavenging activity （DPPH）, 2,2＂-Azino-bis（3-ethylbenzthiazoline-6-sulphonic acid） radical scavenging activity （ABTS） and ferric ion-reducing power （RP-Fe） assays. Aqueous extract 10% p/v showed anti-inflammatory activity （3h, 48% inhibition, 5h 37% inhibition and 7h 17% inhibition） and antioxidant activity （DPPH, ICs0 （mg/mL） = 0.098 =1： 0.032; ABTS, ICs0 （mg/mL） = 0.022 ~ 0.343, RP-Fe IC50 （mg/mL） = 1.124 ~ 0.146）. In the other hand, the ethanolic extract 5% p/v, presented anti-inflammatory activity （3h, 34% inhibition, 5h 38% inhibition and 7h 35% inhibition） and antioxidant activity （DPPH, IC50 （mg/mL） = 0.133 q- 0.027; ABTS, IC50 （mg/mL） = 0.086 ＋ 0.262, RP-Fe IC50 （mg/mL） = 7.089 ± 0.104）. These results suggest that, also fruits, the aqueous and ethanolic extracts from the stem bark of G. decorticans present significant anti-inflammatory activity and antioxidant properties.展开更多
文摘Poly(methacrylic acid co-poloxamer) hydrogel networks were synthesized by free radical solution polymerization and their equilibrium swelling and solute permeation properties were characterized. These gels exhibited pH dependant swelling and solute diffusivity due to the formation or disruption of hydrogen bonded complexation between methacrylic acid (MAA) and etheric (EO). In neutral and basic conditions (above the swelling transition pH), the copolymer swelling was greatly higher than acid condition. In complexed hydrogels, the diffusion coefficients of vitamin B12 (VB12) were in the range of 10-10 to 10-7 cm2s-1; While in uncomplexed hydrogels, the values were about 210-6 cm2s-1. The comonomer composition and synthesis conditions have great effect on the structure, and thereby, swelling and solute diffusion characteristics of the resultant hydrogels. For the copolymers with composition of less than or more than 1:1 MAA/EO molar ratio, the plot of lnD vs 1/H-1 followed two different linear equations of 慺ree volume theory? respectively.
基金This work was supported by the National Natural Science Foundation of China （No.21172210）.
文摘We herein report two crystals based on 2-（imidazo[1,2-a]pyridin-2-yl）-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or supramolecular interactions. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical in two crystals mainly exist as diamagnetic dimer formed via short atomic contacts or supramolecular interactions （hydrogen bonds, anion-Tr or lone- pair-~r interactions）, leading to low magnetic susceptibilities. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical crystal exhibits quasi-one-dimensional columnar stacking chain and weak antiferromagnetism. However, its perchlorate crystal possesses one-dimensional double- stranded chain structure assembled through double hydrogen bonds and anion-To interactions, and reveals weak ferromagnetism.
文摘The first cyclic molecule formation reactions from ethyne （C2H2）, initiated by ethynyl radical （C2H）, were studied by theoretical quantum mechanic. The study included the competition reaction between structure re-arrangement for the favourable ring-closure mechanism and ethyne addition in each step. The analysis was done by evaluating the energy difference of activation （AE）, entalphy （AH）, Gibbs （AG） of the optimized stable and transition molecules. The reaction temperatures were set at normal （T = 298 K） and combustion （T = 1200 K） condition.
文摘We present a theoretical study of the reaction of the hydroxyl radical with ethene using electronic structure calculations and direct-dynamics simulations. High-accuracy electronic structure calculations at the CCSD（T）/aug-cc-pVTZ//MP2/aug-ce-pVDZ level have been carried out to characterize the representative regions of the potential energy surface of various reaction pathways, including OH-addition and H-abstraction. These ab initio calculations have been employed to derive an improved set of parameters for the MSINDO semiempirieal Hamiltonian specific to the OH＋C2H4 reaction. The specific-reaction-parameter Hamilto- nian captures the ab initio data accurately, and has been used to perform direct quasiclassica] trajectory simulations of the OH＋C2H4 reaction at collision energies in the range of 2-10 kcal/mol. The calculated cross sections reveal that the OH-addition reaction domi- nates at all energies over H-abstraction. In addition, the excitation function of addition is reminiscent of a barrierless capture process, while that for abstraction corresponds to an activated one, and these trends can be connected to the transition-state energies of both reactions. We note that the development of an accurate semiempirical Hamiltonian for the OH＋C2H4 reaction in this work required the inclusion of empirical dispersion corrections, which will be important in future applications for which long-range intermoleeular attraction becomes significant.
基金National Natural Science Foundation of China(No.50673071,No.50973079)Natural Science Fund for Colleges and Universities in Jiangsu Province,China(No.07KJD540188,No.09KJA540001)
文摘Silk was grafted using 2-hydroxyethyl methacrylate(HEMA)by atom transfer radical polymerization(ATRP)method.The amino groups and hydroxyl groups on the side chains of the silk fibroin was reacted with 2-bromoisobutyryl bromide(BriB-Br)to obtain efficient macroinitiator for ATRP.And the macroinitiator was grafted with HEMA in water aqueous using CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine(PMDETA)as catalyst system.The effects of monomer concentration,the proportion of CuBr and PMDETA,grafting temperature and time on the silk grafting were discussed,and the optimal grafting technology was obtained.FT-IR characterization of the grafted silk showed a peak corresponding to HEMA,which indicated that HEMA was grafted onto the surface of silk.ATRP method could be applied on the silk modification and this technique provided a new way for silk grafting.
文摘This study evaluated the effect of four different solvent, i.e., water, ethanol, water-ethanol mixture and ethyl acetate, on the antioxidant activities of wild and cultivated heather （Calluna vulgaris （L.） Hull） plant. The highest values for total flavonoid content were obtained for samples extracted using ethanol-water mixture and ethyl acetate. Cupric reducing antioxidant capacity （CUPRAC） method, scavenging ability on 1,1-diphenyl-2-pirylhydrazyl radicals （DPPH） radicals and chelating activity on Fe2~ ions have been used for evaluation of antioxidant activity of the extracts. Ethanolic fraction exhibited the lowest reducing capacity, despite a heather sample used. The extracts of cultivated heather exhibited significant scavenging effect on DPPH radicals, and ethanol and ethanol-water fractions were found to be the most effective. The metal-chelating effect of the extracts increased in the order： ethanol 〈 ethyl acetate 〈 ethanol-water 〈 water. The results may be helpful for better utilization of heather flowers extracts as potential pharmaceutical and nutraceutical ingredient.
文摘In the present work we investigated, for the first time, the anti-inflammatory activity and the antioxidant properties of aqueous and ethanolic extracts, obtained from stem bark of Geoffroea decorticans （Gill. ex Hook. et Am.） Burk. （Fabaceae）. G. decorticans, commonly known as ＂chafiar＂ or ＂chafiarcillo＂, is a traditional argentinean plant used as emollient, balsamic, antitussive, expectorant and anti-inflammatory. The stem bark was collected from San Francisco del Monte de Oro, San Luis, Argentina. Anti-inflammatory activity was evaluated by carrageenan-induced paw edema in rats. Antioxidant activity was tested using 1,1-Diphenyl-2-picrylhydrazyl radical-scavenging activity （DPPH）, 2,2＂-Azino-bis（3-ethylbenzthiazoline-6-sulphonic acid） radical scavenging activity （ABTS） and ferric ion-reducing power （RP-Fe） assays. Aqueous extract 10% p/v showed anti-inflammatory activity （3h, 48% inhibition, 5h 37% inhibition and 7h 17% inhibition） and antioxidant activity （DPPH, ICs0 （mg/mL） = 0.098 =1： 0.032; ABTS, ICs0 （mg/mL） = 0.022 ~ 0.343, RP-Fe IC50 （mg/mL） = 1.124 ~ 0.146）. In the other hand, the ethanolic extract 5% p/v, presented anti-inflammatory activity （3h, 34% inhibition, 5h 38% inhibition and 7h 35% inhibition） and antioxidant activity （DPPH, IC50 （mg/mL） = 0.133 q- 0.027; ABTS, IC50 （mg/mL） = 0.086 ＋ 0.262, RP-Fe IC50 （mg/mL） = 7.089 ± 0.104）. These results suggest that, also fruits, the aqueous and ethanolic extracts from the stem bark of G. decorticans present significant anti-inflammatory activity and antioxidant properties.
