Enhanced oil recovery(EOR)by means of polymer flooding is an important technology for the strategic development of offshore oilfields in China.Hydrophobically associating polyacrylamide(HAPAM)has been recently propose...Enhanced oil recovery(EOR)by means of polymer flooding is an important technology for the strategic development of offshore oilfields in China.Hydrophobically associating polyacrylamide(HAPAM)has been recently proposed as a new flooding agent.The solubility of HAPAM is low,which is the bottleneck for further improving the oil recovery through polymer flooding in offshore oilfield.Stirred tanks have been used on offshore platforms to enhance HAPAM dissolving.But there is little literature on the study of HAPAM dissolving characteristics in stirred tanks.In this paper,effects of temperature,salinity,stirring speed,impeller type and stirring method on the dissolution of HAPAM are reported.The experimental results manifest that the dissolving rate of HAPAM increases with temperature and stirring speed,but the viscosity of the polymer solution decreases.There is an optimal range of salinity for polymer dissolving.Combining the operation mode of up-pumping with varying stirring speed,hydrofoil impeller can accelerate the dissolution of HAPAM and maintain a high solution viscosity.展开更多
In order to improve the surface hydrophobicity, silicone rubber （SIR） samples were exposed to CF4 radio frequency （RF） capacitively coupled plasma （CCP）. Attenuated total reflection Fourier transform infrared （...In order to improve the surface hydrophobicity, silicone rubber （SIR） samples were exposed to CF4 radio frequency （RF） capacitively coupled plasma （CCP）. Attenuated total reflection Fourier transform infrared （ATR-FTIR） spectrum and X-ray photoelectron spectroscopy （XPS） were used to observe the variation of the functional groups of the modified SIR. Static contact angle （SCA） was employed to estimate the change of hydrophobicity of the modified SIR. The surface energy of SIR is reduced largely from 27.37 mJ/m^2 of original SIR sample to 2.94 mJ/m^2 of SIR sample treated by CF4 CCP modification at RF power of 200 W for a treatment time of 5 rnin. According to the XPS, ATR-FTIR and surface energy analysis, it is suggested that the improvement of hydrophobicity on the modified SIR surface is mainly ascribed to the decrease of surface energy, which is caused by the cooperation of the fluosilicic structure of Si--F or Si--F2 and the fluoric groups of C--CFn induced by the methyl replacement reaction and residual methyl groups of SIR surface.展开更多
Gene therapy targeted to vascular cells repre- sents a promising approach for prevention and treatment of pathological conditions such as intimal hyperplasia, in-stent and post-angioplasty restenosis. In this context,...Gene therapy targeted to vascular cells repre- sents a promising approach for prevention and treatment of pathological conditions such as intimal hyperplasia, in-stent and post-angioplasty restenosis. In this context, polymeric non-viral gene delivery systems are a safe alternative to viral vectors but a further improvement in efficiency and cytocom- patibility is needed to improve their clinical success. Herein, a library of 24 branched polyethylenimine （bPEI） derivatives modified with hydrophobic moieties was synthesised, char- acterised and tested in vitro on primary vascular cells, aim- ing to identify delivery agents with superior transfection effi- ciency and low cytotoxicity. Low molecular weight PEIs （0.6, 1.2 and 2 kDa） were grafted with long （C18） and short （C3） aliphatic chains, featuring different unsaturation degrees and degrees of substitution. 0.6 kDa bPEI-based derivatives were generally ineffective in transfection on vascular smooth mus- cle cells （VSMCs）, while among the other derivatives some promising vectors were identified. Forcing polyplexes on the cell surface by means of centrifugation invariably boosted transfection levels but increased cytotoxicity as well. Of note, a propionyl-snbstituted derivative （PEI2-PrA1, C3：0） was the most effective on both VSMCs and endothelial cells （ECs）, with higher and more sustained gene expression in combi- nation with markedly lower cytotoxicity with respect to the gold standard 25 kDa bPEI. In addition, a linoleoyl-substi- tuted derivative （PEI1.2-LA6, C18：2） owing to its high effi- ciency in VSMCs and relative inefficacy in ECs, combined with tolerable cytotoxicity was proposed as a vector for spe- cific VSMCs targeting.展开更多
文摘Enhanced oil recovery(EOR)by means of polymer flooding is an important technology for the strategic development of offshore oilfields in China.Hydrophobically associating polyacrylamide(HAPAM)has been recently proposed as a new flooding agent.The solubility of HAPAM is low,which is the bottleneck for further improving the oil recovery through polymer flooding in offshore oilfield.Stirred tanks have been used on offshore platforms to enhance HAPAM dissolving.But there is little literature on the study of HAPAM dissolving characteristics in stirred tanks.In this paper,effects of temperature,salinity,stirring speed,impeller type and stirring method on the dissolution of HAPAM are reported.The experimental results manifest that the dissolving rate of HAPAM increases with temperature and stirring speed,but the viscosity of the polymer solution decreases.There is an optimal range of salinity for polymer dissolving.Combining the operation mode of up-pumping with varying stirring speed,hydrofoil impeller can accelerate the dissolution of HAPAM and maintain a high solution viscosity.
基金Project(05JT1034) supported by the Plan of Science and Technology Bureau of Hunan Province,China
文摘In order to improve the surface hydrophobicity, silicone rubber （SIR） samples were exposed to CF4 radio frequency （RF） capacitively coupled plasma （CCP）. Attenuated total reflection Fourier transform infrared （ATR-FTIR） spectrum and X-ray photoelectron spectroscopy （XPS） were used to observe the variation of the functional groups of the modified SIR. Static contact angle （SCA） was employed to estimate the change of hydrophobicity of the modified SIR. The surface energy of SIR is reduced largely from 27.37 mJ/m^2 of original SIR sample to 2.94 mJ/m^2 of SIR sample treated by CF4 CCP modification at RF power of 200 W for a treatment time of 5 rnin. According to the XPS, ATR-FTIR and surface energy analysis, it is suggested that the improvement of hydrophobicity on the modified SIR surface is mainly ascribed to the decrease of surface energy, which is caused by the cooperation of the fluosilicic structure of Si--F or Si--F2 and the fluoric groups of C--CFn induced by the methyl replacement reaction and residual methyl groups of SIR surface.
基金financially supported by the Natural Science and Engineering Research Council of Canada, (Discovery Grant to UludagH and Mantovani D)the Canadian Institute for Health Research (Operating grant to Uludag H)the Fonds de Recherche du Quebec sur les Natures et Technologies (Bilateral Grant to Mantovani D)
文摘Gene therapy targeted to vascular cells repre- sents a promising approach for prevention and treatment of pathological conditions such as intimal hyperplasia, in-stent and post-angioplasty restenosis. In this context, polymeric non-viral gene delivery systems are a safe alternative to viral vectors but a further improvement in efficiency and cytocom- patibility is needed to improve their clinical success. Herein, a library of 24 branched polyethylenimine （bPEI） derivatives modified with hydrophobic moieties was synthesised, char- acterised and tested in vitro on primary vascular cells, aim- ing to identify delivery agents with superior transfection effi- ciency and low cytotoxicity. Low molecular weight PEIs （0.6, 1.2 and 2 kDa） were grafted with long （C18） and short （C3） aliphatic chains, featuring different unsaturation degrees and degrees of substitution. 0.6 kDa bPEI-based derivatives were generally ineffective in transfection on vascular smooth mus- cle cells （VSMCs）, while among the other derivatives some promising vectors were identified. Forcing polyplexes on the cell surface by means of centrifugation invariably boosted transfection levels but increased cytotoxicity as well. Of note, a propionyl-snbstituted derivative （PEI2-PrA1, C3：0） was the most effective on both VSMCs and endothelial cells （ECs）, with higher and more sustained gene expression in combi- nation with markedly lower cytotoxicity with respect to the gold standard 25 kDa bPEI. In addition, a linoleoyl-substi- tuted derivative （PEI1.2-LA6, C18：2） owing to its high effi- ciency in VSMCs and relative inefficacy in ECs, combined with tolerable cytotoxicity was proposed as a vector for spe- cific VSMCs targeting.
