The Brownian dynamics （BD） simulation of a dilute surfactant solution is conducted in a steady shear flow. The rodlike micelle is assumed as a rigid rod composed of lined-up beads. A novel intercluster potential mod...The Brownian dynamics （BD） simulation of a dilute surfactant solution is conducted in a steady shear flow. The rodlike micelle is assumed as a rigid rod composed of lined-up beads. A novel intercluster potential model is introduced for describing the interactions between, micelles. In the model, the Lennard-Jones and the soft-sphere potentials are used as inter-bead potentials for end-end and interior-interior beads, respectively. The micelles are combined at their ends to form a network structure at lower shear rates and are disconnected to become more and more parallel to the shear flow direction with increasing shear rate. The change of micellar microstructures with the variation of the shear rate results in shear thinning characteristics of the computed shear viscosities and first normal stress difference coefficients. The effects of surfactant solution concentration on the micellar structures and rheological properties are also investigated. Results show that the shear viscosities and the first normal stress difference coefficients increase with increasing the viscosity of the surfactant solution.展开更多
The presence of salt has a profound effect on the size,shape and structure of sodium dodecyl sulfate(SDS)micelles.There have been a great number of experiments on SDS micelles in the presence and absence of salt to st...The presence of salt has a profound effect on the size,shape and structure of sodium dodecyl sulfate(SDS)micelles.There have been a great number of experiments on SDS micelles in the presence and absence of salt to study this complex problem.Unfortunately,it is not clear yet how electrolyte ions influence the structure of micelles.By describing the compromise between dominant mechanisms,a simplified atomic model of SDS in presence of salt has been developed and the molecular dynamics(MD)simulations of two series of systems with different concentrations of salt and charges of ion have been performed.Polydispersity of micelle size is founded at relatively high concentration of SDS and low charge of cation.Although the counter-ion pairs with head groups are formed,the transition of micelle shape is not observed because the charge of cation is not enough to neutralize the polar of micelle surface.展开更多
The photosensitive micellar system with prospect in drag reduction and heat transfer enhancement has been the research focus of science and industry.In this paper,a new type of photosensitive micellar system formed by...The photosensitive micellar system with prospect in drag reduction and heat transfer enhancement has been the research focus of science and industry.In this paper,a new type of photosensitive micellar system formed by cetyl trimethylammonium bromide(CTAB) and trans-chlorocinnamic acid(trans-CICA) was investigated.The effects of counter-ion concentration,surfactant concentration,UV irradiation time,and the position of substituent groups of counter-ion on photorheological properties were discussed.The results indicate that after UV irradiation the relative viscosity and thixotropy of micellar systems reduce obviously.At the same time,the relative viscosity of micelle systems and concentration of trans-CICA decline during UV irradiation time.The flow curves of micellar solutions before and after UV irradiation could be described by non-linear co-rotational Jeffreys model correctly.The rheokinetic equation was firstly established to describe the relationship between relative viscosity of micelle systems and conversion of trans-CICA.展开更多
We developed an HPLC method to study the pharmacokinetics ofpuerarin in Beagle dogs after oral administration of puerarin or puerarin mixed micelles （PMMS）. Beagle dogs were divided into two groups randomly, and the...We developed an HPLC method to study the pharmacokinetics ofpuerarin in Beagle dogs after oral administration of puerarin or puerarin mixed micelles （PMMS）. Beagle dogs were divided into two groups randomly, and the blood samples were collected at fixed time intervals after single oral administration ofpuerarin or PMMS at a dosage of 120 mg/kg. Following sample preparation, analytes were separated on a C18 column （DIKMA, 150 mm×4.6 mm, 5 μm） with a guard column （DIKMA, 8 mm×4 mm） and eluted with methanol-water （25：75, v/v）. Theophylline was used as the internal standard. WinNonlin 6.1 （Pharsight, USA） was used to calculate the pharrnacokinetic parameters. The pharmacokinetic parameters for puerarin and PMMS in Beagle dogs were as follows： AUC, 515.96 and 2796.43 min μg/mL; Tmax, 61.48 and 202.91 min; CL/F, 232.58 and 42.91 mL/min/kg, respectively. The relative bioavailability of PMMS to puerarin was 542.0%. Our results showed that the mixed micelle preparation significantly improved the bioavailability of puerarin by delaying absorption and reducing clearance.展开更多
A theoretical model to explain the mechanism of the electromagnetic wave propagation in the quasi two-dimensional layer of counterions adjacent to the surface of a charged cylindrical membrane is presented. By using M...A theoretical model to explain the mechanism of the electromagnetic wave propagation in the quasi two-dimensional layer of counterions adjacent to the surface of a charged cylindrical membrane is presented. By using Maxwell and hydrodynamic equations with appropriate boundary conditions, general expression of dispersion relation is obtained for the electromagnetic wave with mixed TE and TM modes.展开更多
文摘The Brownian dynamics （BD） simulation of a dilute surfactant solution is conducted in a steady shear flow. The rodlike micelle is assumed as a rigid rod composed of lined-up beads. A novel intercluster potential model is introduced for describing the interactions between, micelles. In the model, the Lennard-Jones and the soft-sphere potentials are used as inter-bead potentials for end-end and interior-interior beads, respectively. The micelles are combined at their ends to form a network structure at lower shear rates and are disconnected to become more and more parallel to the shear flow direction with increasing shear rate. The change of micellar microstructures with the variation of the shear rate results in shear thinning characteristics of the computed shear viscosities and first normal stress difference coefficients. The effects of surfactant solution concentration on the micellar structures and rheological properties are also investigated. Results show that the shear viscosities and the first normal stress difference coefficients increase with increasing the viscosity of the surfactant solution.
基金Supported by the Outstanding Overseas Research Team Project of the Chinese Academy of Sciences, the National Natural Science Foundation of China （20221603）, and the Research Fund of Key Lab for Nanomaterials, Ministry of Education, China （2006-1）.
文摘The presence of salt has a profound effect on the size,shape and structure of sodium dodecyl sulfate(SDS)micelles.There have been a great number of experiments on SDS micelles in the presence and absence of salt to study this complex problem.Unfortunately,it is not clear yet how electrolyte ions influence the structure of micelles.By describing the compromise between dominant mechanisms,a simplified atomic model of SDS in presence of salt has been developed and the molecular dynamics(MD)simulations of two series of systems with different concentrations of salt and charges of ion have been performed.Polydispersity of micelle size is founded at relatively high concentration of SDS and low charge of cation.Although the counter-ion pairs with head groups are formed,the transition of micelle shape is not observed because the charge of cation is not enough to neutralize the polar of micelle surface.
基金Supported by the National Natural Science Foundation of China(21273072)
文摘The photosensitive micellar system with prospect in drag reduction and heat transfer enhancement has been the research focus of science and industry.In this paper,a new type of photosensitive micellar system formed by cetyl trimethylammonium bromide(CTAB) and trans-chlorocinnamic acid(trans-CICA) was investigated.The effects of counter-ion concentration,surfactant concentration,UV irradiation time,and the position of substituent groups of counter-ion on photorheological properties were discussed.The results indicate that after UV irradiation the relative viscosity and thixotropy of micellar systems reduce obviously.At the same time,the relative viscosity of micelle systems and concentration of trans-CICA decline during UV irradiation time.The flow curves of micellar solutions before and after UV irradiation could be described by non-linear co-rotational Jeffreys model correctly.The rheokinetic equation was firstly established to describe the relationship between relative viscosity of micelle systems and conversion of trans-CICA.
基金Foundation of Independent Subject of Beijing University of Chinese Medicine (Grant No. JYB22-JS025)Compound Chinese Medicine Preparation Research Innovation Team (Team No. 2011-CXTD-13)
文摘We developed an HPLC method to study the pharmacokinetics ofpuerarin in Beagle dogs after oral administration of puerarin or puerarin mixed micelles （PMMS）. Beagle dogs were divided into two groups randomly, and the blood samples were collected at fixed time intervals after single oral administration ofpuerarin or PMMS at a dosage of 120 mg/kg. Following sample preparation, analytes were separated on a C18 column （DIKMA, 150 mm×4.6 mm, 5 μm） with a guard column （DIKMA, 8 mm×4 mm） and eluted with methanol-water （25：75, v/v）. Theophylline was used as the internal standard. WinNonlin 6.1 （Pharsight, USA） was used to calculate the pharrnacokinetic parameters. The pharmacokinetic parameters for puerarin and PMMS in Beagle dogs were as follows： AUC, 515.96 and 2796.43 min μg/mL; Tmax, 61.48 and 202.91 min; CL/F, 232.58 and 42.91 mL/min/kg, respectively. The relative bioavailability of PMMS to puerarin was 542.0%. Our results showed that the mixed micelle preparation significantly improved the bioavailability of puerarin by delaying absorption and reducing clearance.
文摘A theoretical model to explain the mechanism of the electromagnetic wave propagation in the quasi two-dimensional layer of counterions adjacent to the surface of a charged cylindrical membrane is presented. By using Maxwell and hydrodynamic equations with appropriate boundary conditions, general expression of dispersion relation is obtained for the electromagnetic wave with mixed TE and TM modes.
