Dynamic behaviors on polyacrylic acid (PAA) gels and mass (small molecules) transports in the gels have been studied mainly by dynamic light scattering (DLS). The cross-linking degree (fc), monomer concentration (Cm)...Dynamic behaviors on polyacrylic acid (PAA) gels and mass (small molecules) transports in the gels have been studied mainly by dynamic light scattering (DLS). The cross-linking degree (fc), monomer concentration (Cm) and temperature of the gels have significant influences on its dynamic behavior and mass transport in the gels. The increase of fc leads to decrease of the mesh sizes of the gels, thus the obstacle of the gels for mass transport is increased. As a result, small molecular diffusion Dk in the gels is decreased. So even if for small molecules, the Dk also is influenced.展开更多
Dynamic light scattering(DLS)is a promising technique for early cataract detection and for studying cataractogenesis.A novel probabilistic analysis tool,the sparse Bayesian learning(SBL)algorithm,is described for reco...Dynamic light scattering(DLS)is a promising technique for early cataract detection and for studying cataractogenesis.A novel probabilistic analysis tool,the sparse Bayesian learning(SBL)algorithm,is described for reconstructing the most-probable size distribution ofα-crystallin and their aggregates in an ocular lens from the DLS data.The performance of the algorithm is evaluated by analyzing simulated correlation data from known distributions and DLS data from the ocular lenses of a fetal calf,a Rhesus monkey,and a man,so as to establish the required efficiency of the SBL algorithm for clinical studies.展开更多
The technique of dynamic light scattering has been used to investigate the translation diffusion behavior of 8-arm star polystyrene (SPS)in a good solvent, tetrahydrofuran (THF) or benzene (BZ) and a theta solvent, cy...The technique of dynamic light scattering has been used to investigate the translation diffusion behavior of 8-arm star polystyrene (SPS)in a good solvent, tetrahydrofuran (THF) or benzene (BZ) and a theta solvent, cyclohexane (CH), by homodyne photon correlation spectroscopy .The intensityintensity autocorrelation function was analyzed by the method of cumulant. The translation diffusion coefficients have been obtained as a function of temperature and concentration. Under theta condition ,the non-concentration dependence of diffusion coefficient showed the unperturbed Gaussian state o the SPS molecular chain. The different hydrodynamic radii estimated from Stokes- Einstein equation reflected the stretch extent of the arm chain for regular star polymer. The data of diffusion activation energy of SPS in THF, BZ and CH were also obtained respectively.展开更多
The performance of nanoparticles is often affected by particle size and morphology.Currently,electron microscopy or atomic force microscopy is typically utilized to determine the size and morphology of nanoparticles.H...The performance of nanoparticles is often affected by particle size and morphology.Currently,electron microscopy or atomic force microscopy is typically utilized to determine the size and morphology of nanoparticles.However,there are issues such as difficult sample preparation,long processing times,and challenges in quantitative characterization.Therefore,it is of great significance to develop a fast,accu-rate,and statistical method to measure the size and morphology of nanoparticles.In this study,a new method,called polarized imaging dynamic light scattering(PIDLS),is proposed.The nanoparticles are irradiated with a vertical linearly polarized laser beam,and a polarization camera collected the dynamic light scattering images of particles at four different polarization directions(0°,45°,90°,and 135°)at a scattering angle of 90°.The average particle size and distribution are obtained using the imaging dy-namic light scattering method at 0°polarization direction,and the morphology of the particles is ob-tained based on the depolarization patterns of the scattered light.The optical sphericityΦis defined based on the degree of linear polarization(DoLP).It is also implemented for the quantitative evaluation of the sphericity of the nanoparticles,including spherical,octahedral,nanoplate,nanorod,and linear ones.Together with the Poincarésphere parameterψ,the morphology of the nanoparticles can be roughly identified.In addition,PIDLS enables the measurement of particle size and morphology distributions simultaneously for evaluating the uniformity of particles.The effectiveness of PIDLS is verified by the measurement of five kinds of industrial titanium dioxide as well.展开更多
Understanding the dynamic assembly process of DNA nanostructures is important for developing novel strategy to design and construct functional devices.In this work,temperature-controlled dynamic light scattering(DLS)s...Understanding the dynamic assembly process of DNA nanostructures is important for developing novel strategy to design and construct functional devices.In this work,temperature-controlled dynamic light scattering(DLS)strategy has been applied to study the global assembly process of DNA origami and DNA bricks.Through the temperature dependent size and intensity profiles,the self-assembly process of various DNA nanostructures with different morphologies have been well-studied and the temperature transition ranges could be observed.Taking advantage of the DLS information,rapid preparation of the DNA origami and the brick assembly has been realized through a constant temperature annealing.Our results demonstrate that the DLS-based strategy provides a convenient and robust tool to study the dynamic process of forming hieratical DNA structures,which will benefit understanding the mechanism of self-assembly of DNA nanostructures.展开更多
Dynamic light scattering(DLS)is a nondestructive,well-established technique for the size characterization of proteins,nanoparticles,polymers,and colloidal dispersions.However,current DLS techniques are only applied to...Dynamic light scattering(DLS)is a nondestructive,well-established technique for the size characterization of proteins,nanoparticles,polymers,and colloidal dispersions.However,current DLS techniques are only applied to particle groups of single composition due to the limitation of their inversion algorithm.In this study,we propose a particle size distribution inversion algorithm based on the Tikhnonov regularization method that can be applied to the dual-substance particle mixture.The algorithm retrieves the particle size distributions of two substances,respectively,by taking advantage of their refractive index differences.The simulation results reveal that the algorithm has excellent accuracy and stability when the scattering angle is 30°.Instead of the original identity matrix,the first-order difference matrix and second-order difference matrix are used as the regular matrix when utilizing the Tikhnonov algorithm,which obviously improves the anti-interference,accuracy,and stability of the algorithm.Furthermore,the inversion of particle size distribution is carried out at a 0.01%–1%noise level,which shows that the algorithm has an available antinoise ability.Finally,experimental particle size measurements for a mixture of polystyrene beads and toner particles demonstrate that the proposed algorithm is superior to the traditional Tikhnonov algorithm in applicability and accuracy.展开更多
In this paper, an image dynamic light scattering method for nanoparticle sizing is introduced. The spatial distribution of the scattered lights from nanoparticles undergoing Brownian motion was captured at a high fram...In this paper, an image dynamic light scattering method for nanoparticle sizing is introduced. The spatial distribution of the scattered lights from nanoparticles undergoing Brownian motion was captured at a high frame rate by a digital camera within one second, which is considerably faster than the conven- tional photon correlation spectroscopy method. The captured series of photographs were meshed into thousands of small units for calculating the intensity autocorrelation functions in parallel. Experimental results from the measurements of three reference nanoparticle samples (27, 80, and 352 nm in diameters) demonstrated the feasibility of this method.展开更多
Pterodontic acid(PA)has been isolated from Laggera pterodonta,a Chinese herbal medicine,and shown to possess antibacterial activity in vitro.To facilitate its preclinical development,the interaction between PA and bov...Pterodontic acid(PA)has been isolated from Laggera pterodonta,a Chinese herbal medicine,and shown to possess antibacterial activity in vitro.To facilitate its preclinical development,the interaction between PA and bovine serum albumin(BSA)was studied using a fluorescence quenching technique,ultraviolet–visible spectrophotometry and dynamic light scattering(DLS).At temperatures of 297 K and 310 K and an excitation wavelength of 282 nm,the fluorescence intensity of BSA decreased significantly with increasing concentration of PA attributed to the formation of a PA–BSA complex.The apparent binding constant,number of binding sites and corresponding thermodynamic parameters were calculated and the main intermolecular attraction shown to result from hydrogen bonding and van der Waals forces.Synchronous fluorescence spectrometry revealed that the binding site in the complex approached the microenvironment of Trp and three-dimensional fluorescence spectroscopy showed the binding induced conformational changes in BSA.Using DLS,increasing PA concentration was shown to cause a gradual increase in hydrodynamic diameter and significant aggregation of the complex.展开更多
The effects of temperature,ionic strength,and enzymatic hydrolysis on the average hydrodynamic radius(Rh)of casein micelles in phosphate buffer were studied by using dynamic light scattering.The results showed that th...The effects of temperature,ionic strength,and enzymatic hydrolysis on the average hydrodynamic radius(Rh)of casein micelles in phosphate buffer were studied by using dynamic light scattering.The results showed that the average Rh value of casein micelles decreased irreversibly during the heating,decreased with the increase of ionic strength in lower ionic strength solution(less than 0.05 mol/L),but opposite in higher ionic strength solution(above 0.1 mol/L).The Rh value of casein increased rapidly during the process of enzymatic hydrolysis,and the structural model of casein micelles in the enzymatic hydrolysis process was also proposed,i.e.the casein micelle changed from compact sphere into unfolded and regularly flocky peptides.展开更多
This paper presents the study of the effect of multiple ultrasonic impacts on submicron asphaltene aggregates in a toluene/heptane solution,conducted with dynamic light scattering technique.The objects of the study we...This paper presents the study of the effect of multiple ultrasonic impacts on submicron asphaltene aggregates in a toluene/heptane solution,conducted with dynamic light scattering technique.The objects of the study were four samples of asphaltenes obtained from four different oils.For all samples,the change in the average size of the asphaltene submicron aggregates with time was measured after the addition of a precipitant(heptane)to a solution of asphaltenes in toluene at an amount above the threshold concentration.Asphaltene aggregates formed in solution after the addition of the precipitant and were subjected to ultrasonic treatment,which led to the destruction of the asphaltene aggregates.Aggregation of destroyed asphaltenes was observed.The kinetics of this aggregation were similar to the kinetics of aggregation of asphaltenes after the addition of a precipitant.Multiple iterations of asphaltene aggregate destruction in the sample led to a significant change in the kinetics of aggregation:the growth of aggregates slowed and stabilized at a size of approximately 200 nm and 30 nm for the different studied samples.展开更多
This review covers the progress of light scattering applications in the field of particle characterization in the past decade. The review addresses static light scattering (the measurement of scattering intensities d...This review covers the progress of light scattering applications in the field of particle characterization in the past decade. The review addresses static light scattering (the measurement of scattering intensities due to light-particle interaction at various spatial locations), dynamic light scattering (the measurement of scattering due to light-particle interaction as a function of time), and scattering tracking analysis (the tracking of particle movement through scattering measurement).展开更多
Spontaneous vesicles from the mixed aqueous solution of poly-tailed cationic surfactant PTA and anionic surfactant AOT are firstly obtained. Vesicle formation and characterizations are demonstrated by negative-staini...Spontaneous vesicles from the mixed aqueous solution of poly-tailed cationic surfactant PTA and anionic surfactant AOT are firstly obtained. Vesicle formation and characterizations are demonstrated by negative-staining TEM and dynamic light scattering. A monodisperse vesicle system is obtained with a polydispersity of 0.082. Ultrasonication can promote the vesicle formation. Mechanism of vesicle formation is discussed from the viewpoint of molecular interaction.展开更多
We used a thermally reversible hybrid gel made of billions of physically jam-packed swollen thermally sensitivepoly(N-isopropyl-acrylamide) chemical microgels. Laser light scattering study on a series of such hybrid g...We used a thermally reversible hybrid gel made of billions of physically jam-packed swollen thermally sensitivepoly(N-isopropyl-acrylamide) chemical microgels. Laser light scattering study on a series of such hybrid gels formed atdifferent gelling rates and temperatures revealed that the position-dependence of the scattering speckle pattern(staticnonergodicity) came from large voids formed during the sol-gel transition. With a proper preparation, such a nonergodicitycould be completely removed, indicating that the static nonergodicity generally observed in a gel is not indinsic, but comesfrom the clustering "island" structure formed during the gelation process.展开更多
The effects of heat treatment(heating temperature and pH) on the structures and emulsifying properties of caseins were systematically studied by spectroscopy.Heat treatment from 60to 100℃resulted in an increase in th...The effects of heat treatment(heating temperature and pH) on the structures and emulsifying properties of caseins were systematically studied by spectroscopy.Heat treatment from 60to 100℃resulted in an increase in their fluorescence intensity,hydrodynamic diameter,turbidity and emulsifying activity index,but decreased the size polydispersity of caseins.In the pH range of 5.5to 7.0,the fluorescence intensity,hydrodynamic diameter,turbidity and emulsifying properties decreased with increased heating pH,but the size polydispersity of caseins increased with increased pH.The relationship between the surface fluorescence intensity and emulsifying activity was also investigated,revealing a correlation coefficient of 0.90.These results suggested that heat treatment could be used to modify the structures and emulsifying properties of caseins by appropriately selecting heating conditions.展开更多
The adsorption of protein on nanoparticles was studied by using dynamic light scattering tomeasure the hydrodynamic size of both pure protein and nanoparticles adsorbed with differentamounts of protein. The thickness ...The adsorption of protein on nanoparticles was studied by using dynamic light scattering tomeasure the hydrodynamic size of both pure protein and nanoparticles adsorbed with differentamounts of protein. The thickness of the adsorbed protein layer increases as proteinconcentration, but decreases as the initial size of nanoparticles. After properly scaling thethickness with the initial diameter, we are able to fit all experimental data with a single mastercurve. Our experimental results suggest that the adsorbed proteins form a monolayer on thenanoparticle surface and the adsorbed protein molecules are attached to the particle surface atmany points through a possible hydrogen-bonding. Our results also indicate that as proteinconcentration increases, the overall shape of the adsorbed protein molecule continuously changesfrom a flat layer on the particle surface to a stretched coil extended into water. During thechange, the hydrodynamic volume of the adsorbed protein increases linearly with proteinconcentration.展开更多
The refractive index increment, dynamic and static laser light scattering, intrinsic viscosity [η] and Huggins constant (KH) of nylon 12 have been measured in m-cresol and sulphuric acid/water system at 10-60℃. Th...The refractive index increment, dynamic and static laser light scattering, intrinsic viscosity [η] and Huggins constant (KH) of nylon 12 have been measured in m-cresol and sulphuric acid/water system at 10-60℃. The intrinsic viscosity, Rn, Rg, A2, and (〈 S 〉2)^1/2 (calculated from viscosity data) and "a" values of nylon 12 are found to be higher in m-cresol than in sulphuric acid. All these parameters decrease with the increase in water contents in sulphuric acid. The refractive index increment, KH and activation energy show an opposite trend to that of [η]. The intrinsic viscosity, RH, Rg, A2, and (〈 S 〉2)^1/2 have maximum values around 30-40℃ in sulphuric acid/water system, whereas in m-cresol they fall at about 20℃. It has been concluded that the variation in size, interaction parameter (second virial coefficient), [η] and KH of the polymer solutions with the alteration in solvent composition and temperature are the out come of change in thermodynamic quality of solvents, selective adsorption, hydrogen bonding and conformational transitions. It has also been concluded that the increase in temperature first enhances the quality of the solvent, encourages hydrogen bonding and specific adsorption, and then deteriorates, bringing conformational transitions in the polymer molecules. However, the addition of water to sulphuric acid continuously deteriorates the solvent quality. This characteristic of the solvent system brings conformational changes in the polymer especially at low temperatures.展开更多
The morphologies and the microstructures of the dispersed particles of the cubic phase, which were formed by precursor method, were studied. The freeze-fracture TEM clearly showed that the aqueous dispersed particles ...The morphologies and the microstructures of the dispersed particles of the cubic phase, which were formed by precursor method, were studied. The freeze-fracture TEM clearly showed that the aqueous dispersed particles have irregular cubic shapes. X-ray diffraction technique has been utilized to study the microstructure of the particles and it was found that these particles still retained the cubic character. The sizes of the particles were measured by dynamic light scattering, and the results showed that the sizes of the dispersed particles were between 200 ~ 400 nm under different conditions.展开更多
The lysozyme crystals were made by batch crystallization method and the distribution of aggregate in solution were measured by dynamic light scattering. The results showed that the dimension of aggregate increased wit...The lysozyme crystals were made by batch crystallization method and the distribution of aggregate in solution were measured by dynamic light scattering. The results showed that the dimension of aggregate increased with the increase of the concentration of lysozyme and NaCl, lysozyme molecules aggregated gradually in solution and finally arrived at balance each other. The higher the concentrations of lysozyme and NaCl were, the faster the growth rate of (110) face was. The growth rates of lysozyme crystal were obtained by a Zeiss microscope, and the effective surface energy (a) of growing steps were calculated about 4.01×10^-8s J·cm^-2 according to the model of multiple two-dimensional nucleation mechanism.展开更多
基金Project 29774011 was supported by the National Natural Science Foundation of China.
文摘Dynamic behaviors on polyacrylic acid (PAA) gels and mass (small molecules) transports in the gels have been studied mainly by dynamic light scattering (DLS). The cross-linking degree (fc), monomer concentration (Cm) and temperature of the gels have significant influences on its dynamic behavior and mass transport in the gels. The increase of fc leads to decrease of the mesh sizes of the gels, thus the obstacle of the gels for mass transport is increased. As a result, small molecular diffusion Dk in the gels is decreased. So even if for small molecules, the Dk also is influenced.
基金the National Science Council of the Republic of China under the Contract No.NSC-97-2112-M-006-006.
文摘Dynamic light scattering(DLS)is a promising technique for early cataract detection and for studying cataractogenesis.A novel probabilistic analysis tool,the sparse Bayesian learning(SBL)algorithm,is described for reconstructing the most-probable size distribution ofα-crystallin and their aggregates in an ocular lens from the DLS data.The performance of the algorithm is evaluated by analyzing simulated correlation data from known distributions and DLS data from the ocular lenses of a fetal calf,a Rhesus monkey,and a man,so as to establish the required efficiency of the SBL algorithm for clinical studies.
文摘The technique of dynamic light scattering has been used to investigate the translation diffusion behavior of 8-arm star polystyrene (SPS)in a good solvent, tetrahydrofuran (THF) or benzene (BZ) and a theta solvent, cyclohexane (CH), by homodyne photon correlation spectroscopy .The intensityintensity autocorrelation function was analyzed by the method of cumulant. The translation diffusion coefficients have been obtained as a function of temperature and concentration. Under theta condition ,the non-concentration dependence of diffusion coefficient showed the unperturbed Gaussian state o the SPS molecular chain. The different hydrodynamic radii estimated from Stokes- Einstein equation reflected the stretch extent of the arm chain for regular star polymer. The data of diffusion activation energy of SPS in THF, BZ and CH were also obtained respectively.
基金supported by Shanghai Sailing Program(grant No.22YF1429600).
文摘The performance of nanoparticles is often affected by particle size and morphology.Currently,electron microscopy or atomic force microscopy is typically utilized to determine the size and morphology of nanoparticles.However,there are issues such as difficult sample preparation,long processing times,and challenges in quantitative characterization.Therefore,it is of great significance to develop a fast,accu-rate,and statistical method to measure the size and morphology of nanoparticles.In this study,a new method,called polarized imaging dynamic light scattering(PIDLS),is proposed.The nanoparticles are irradiated with a vertical linearly polarized laser beam,and a polarization camera collected the dynamic light scattering images of particles at four different polarization directions(0°,45°,90°,and 135°)at a scattering angle of 90°.The average particle size and distribution are obtained using the imaging dy-namic light scattering method at 0°polarization direction,and the morphology of the particles is ob-tained based on the depolarization patterns of the scattered light.The optical sphericityΦis defined based on the degree of linear polarization(DoLP).It is also implemented for the quantitative evaluation of the sphericity of the nanoparticles,including spherical,octahedral,nanoplate,nanorod,and linear ones.Together with the Poincarésphere parameterψ,the morphology of the nanoparticles can be roughly identified.In addition,PIDLS enables the measurement of particle size and morphology distributions simultaneously for evaluating the uniformity of particles.The effectiveness of PIDLS is verified by the measurement of five kinds of industrial titanium dioxide as well.
基金supported by the National Natural Science Foundation of China(No.21971248)。
文摘Understanding the dynamic assembly process of DNA nanostructures is important for developing novel strategy to design and construct functional devices.In this work,temperature-controlled dynamic light scattering(DLS)strategy has been applied to study the global assembly process of DNA origami and DNA bricks.Through the temperature dependent size and intensity profiles,the self-assembly process of various DNA nanostructures with different morphologies have been well-studied and the temperature transition ranges could be observed.Taking advantage of the DLS information,rapid preparation of the DNA origami and the brick assembly has been realized through a constant temperature annealing.Our results demonstrate that the DLS-based strategy provides a convenient and robust tool to study the dynamic process of forming hieratical DNA structures,which will benefit understanding the mechanism of self-assembly of DNA nanostructures.
基金supported by the National Natural Science Foundation of China(grant No.61775065)。
文摘Dynamic light scattering(DLS)is a nondestructive,well-established technique for the size characterization of proteins,nanoparticles,polymers,and colloidal dispersions.However,current DLS techniques are only applied to particle groups of single composition due to the limitation of their inversion algorithm.In this study,we propose a particle size distribution inversion algorithm based on the Tikhnonov regularization method that can be applied to the dual-substance particle mixture.The algorithm retrieves the particle size distributions of two substances,respectively,by taking advantage of their refractive index differences.The simulation results reveal that the algorithm has excellent accuracy and stability when the scattering angle is 30°.Instead of the original identity matrix,the first-order difference matrix and second-order difference matrix are used as the regular matrix when utilizing the Tikhnonov algorithm,which obviously improves the anti-interference,accuracy,and stability of the algorithm.Furthermore,the inversion of particle size distribution is carried out at a 0.01%–1%noise level,which shows that the algorithm has an available antinoise ability.Finally,experimental particle size measurements for a mixture of polystyrene beads and toner particles demonstrate that the proposed algorithm is superior to the traditional Tikhnonov algorithm in applicability and accuracy.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (20113120130001)the Nanotech Initiative Project of Shanghai Science and Technology Commission(11 nm0507100)the Innovation Fund Project For Graduate Student of Shanghai (JWCXSL1401)
文摘In this paper, an image dynamic light scattering method for nanoparticle sizing is introduced. The spatial distribution of the scattered lights from nanoparticles undergoing Brownian motion was captured at a high frame rate by a digital camera within one second, which is considerably faster than the conven- tional photon correlation spectroscopy method. The captured series of photographs were meshed into thousands of small units for calculating the intensity autocorrelation functions in parallel. Experimental results from the measurements of three reference nanoparticle samples (27, 80, and 352 nm in diameters) demonstrated the feasibility of this method.
基金supported by the Special Fund for Basic Scientific Research of Central Colleges,South-Central University for Nationalities(No.CZQ11013)by the Wuhan Science and Technology Bureau(No.201051730558).
文摘Pterodontic acid(PA)has been isolated from Laggera pterodonta,a Chinese herbal medicine,and shown to possess antibacterial activity in vitro.To facilitate its preclinical development,the interaction between PA and bovine serum albumin(BSA)was studied using a fluorescence quenching technique,ultraviolet–visible spectrophotometry and dynamic light scattering(DLS).At temperatures of 297 K and 310 K and an excitation wavelength of 282 nm,the fluorescence intensity of BSA decreased significantly with increasing concentration of PA attributed to the formation of a PA–BSA complex.The apparent binding constant,number of binding sites and corresponding thermodynamic parameters were calculated and the main intermolecular attraction shown to result from hydrogen bonding and van der Waals forces.Synchronous fluorescence spectrometry revealed that the binding site in the complex approached the microenvironment of Trp and three-dimensional fluorescence spectroscopy showed the binding induced conformational changes in BSA.Using DLS,increasing PA concentration was shown to cause a gradual increase in hydrodynamic diameter and significant aggregation of the complex.
基金supported by the National Natural Science Foundation of China(Grant No.20306023)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20050056061).
文摘The effects of temperature,ionic strength,and enzymatic hydrolysis on the average hydrodynamic radius(Rh)of casein micelles in phosphate buffer were studied by using dynamic light scattering.The results showed that the average Rh value of casein micelles decreased irreversibly during the heating,decreased with the increase of ionic strength in lower ionic strength solution(less than 0.05 mol/L),but opposite in higher ionic strength solution(above 0.1 mol/L).The Rh value of casein increased rapidly during the process of enzymatic hydrolysis,and the structural model of casein micelles in the enzymatic hydrolysis process was also proposed,i.e.the casein micelle changed from compact sphere into unfolded and regularly flocky peptides.
基金The author of the article would like to thank Alexey D.Yapryntsev(Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences)for studying the samples by scanning electron microscopy.The author thanks the staff of the A.E.Arbuzov Institute of Organic and Physical Chemistry,“Kazan Scientific Center of Russian Academy of Sciences”,laboratory of Chemistry and Geochemistry of Petroleum and organizers of International Conference on Petroleum Phase Behavior&Fouling“PetroPhase2017”for providing samples of asphaltenes and resins.This work was performed within the framework of the state task(by Ministry of Science and Higher Education of the Russian Federation)of the Oil and Gas Research Institute of Russian Academy of Sciences(Project No.122022800364-6).
文摘This paper presents the study of the effect of multiple ultrasonic impacts on submicron asphaltene aggregates in a toluene/heptane solution,conducted with dynamic light scattering technique.The objects of the study were four samples of asphaltenes obtained from four different oils.For all samples,the change in the average size of the asphaltene submicron aggregates with time was measured after the addition of a precipitant(heptane)to a solution of asphaltenes in toluene at an amount above the threshold concentration.Asphaltene aggregates formed in solution after the addition of the precipitant and were subjected to ultrasonic treatment,which led to the destruction of the asphaltene aggregates.Aggregation of destroyed asphaltenes was observed.The kinetics of this aggregation were similar to the kinetics of aggregation of asphaltenes after the addition of a precipitant.Multiple iterations of asphaltene aggregate destruction in the sample led to a significant change in the kinetics of aggregation:the growth of aggregates slowed and stabilized at a size of approximately 200 nm and 30 nm for the different studied samples.
文摘This review covers the progress of light scattering applications in the field of particle characterization in the past decade. The review addresses static light scattering (the measurement of scattering intensities due to light-particle interaction at various spatial locations), dynamic light scattering (the measurement of scattering due to light-particle interaction as a function of time), and scattering tracking analysis (the tracking of particle movement through scattering measurement).
基金The work was supported by the Natural Science Foundation of China (No. 29903006 29973023).
文摘Spontaneous vesicles from the mixed aqueous solution of poly-tailed cationic surfactant PTA and anionic surfactant AOT are firstly obtained. Vesicle formation and characterizations are demonstrated by negative-staining TEM and dynamic light scattering. A monodisperse vesicle system is obtained with a polydispersity of 0.082. Ultrasonication can promote the vesicle formation. Mechanism of vesicle formation is discussed from the viewpoint of molecular interaction.
基金The financial support of the NNSF Fund (No. 29974027), the CAS Bai Ren Project, and the Research Grants Council of the Hong Kong Special Administration Region Earmarked Grant (CUHK 4266/00P, 2160135) is gratefully acknowledged.
文摘We used a thermally reversible hybrid gel made of billions of physically jam-packed swollen thermally sensitivepoly(N-isopropyl-acrylamide) chemical microgels. Laser light scattering study on a series of such hybrid gels formed atdifferent gelling rates and temperatures revealed that the position-dependence of the scattering speckle pattern(staticnonergodicity) came from large voids formed during the sol-gel transition. With a proper preparation, such a nonergodicitycould be completely removed, indicating that the static nonergodicity generally observed in a gel is not indinsic, but comesfrom the clustering "island" structure formed during the gelation process.
基金International Science&Technology Cooperation Program of China(2011DFA32550)Ministry of Science and Technology of China(2012BAD12B08)
文摘The effects of heat treatment(heating temperature and pH) on the structures and emulsifying properties of caseins were systematically studied by spectroscopy.Heat treatment from 60to 100℃resulted in an increase in their fluorescence intensity,hydrodynamic diameter,turbidity and emulsifying activity index,but decreased the size polydispersity of caseins.In the pH range of 5.5to 7.0,the fluorescence intensity,hydrodynamic diameter,turbidity and emulsifying properties decreased with increased heating pH,but the size polydispersity of caseins increased with increased pH.The relationship between the surface fluorescence intensity and emulsifying activity was also investigated,revealing a correlation coefficient of 0.90.These results suggested that heat treatment could be used to modify the structures and emulsifying properties of caseins by appropriately selecting heating conditions.
文摘The adsorption of protein on nanoparticles was studied by using dynamic light scattering tomeasure the hydrodynamic size of both pure protein and nanoparticles adsorbed with differentamounts of protein. The thickness of the adsorbed protein layer increases as proteinconcentration, but decreases as the initial size of nanoparticles. After properly scaling thethickness with the initial diameter, we are able to fit all experimental data with a single mastercurve. Our experimental results suggest that the adsorbed proteins form a monolayer on thenanoparticle surface and the adsorbed protein molecules are attached to the particle surface atmany points through a possible hydrogen-bonding. Our results also indicate that as proteinconcentration increases, the overall shape of the adsorbed protein molecule continuously changesfrom a flat layer on the particle surface to a stretched coil extended into water. During thechange, the hydrodynamic volume of the adsorbed protein increases linearly with proteinconcentration.
文摘The refractive index increment, dynamic and static laser light scattering, intrinsic viscosity [η] and Huggins constant (KH) of nylon 12 have been measured in m-cresol and sulphuric acid/water system at 10-60℃. The intrinsic viscosity, Rn, Rg, A2, and (〈 S 〉2)^1/2 (calculated from viscosity data) and "a" values of nylon 12 are found to be higher in m-cresol than in sulphuric acid. All these parameters decrease with the increase in water contents in sulphuric acid. The refractive index increment, KH and activation energy show an opposite trend to that of [η]. The intrinsic viscosity, RH, Rg, A2, and (〈 S 〉2)^1/2 have maximum values around 30-40℃ in sulphuric acid/water system, whereas in m-cresol they fall at about 20℃. It has been concluded that the variation in size, interaction parameter (second virial coefficient), [η] and KH of the polymer solutions with the alteration in solvent composition and temperature are the out come of change in thermodynamic quality of solvents, selective adsorption, hydrogen bonding and conformational transitions. It has also been concluded that the increase in temperature first enhances the quality of the solvent, encourages hydrogen bonding and specific adsorption, and then deteriorates, bringing conformational transitions in the polymer molecules. However, the addition of water to sulphuric acid continuously deteriorates the solvent quality. This characteristic of the solvent system brings conformational changes in the polymer especially at low temperatures.
文摘The morphologies and the microstructures of the dispersed particles of the cubic phase, which were formed by precursor method, were studied. The freeze-fracture TEM clearly showed that the aqueous dispersed particles have irregular cubic shapes. X-ray diffraction technique has been utilized to study the microstructure of the particles and it was found that these particles still retained the cubic character. The sizes of the particles were measured by dynamic light scattering, and the results showed that the sizes of the dispersed particles were between 200 ~ 400 nm under different conditions.
基金supported by the National Natural Science Foundation of China(No.10472127 and No.10432060)Knowledge Innovation Program of Chinese Academy of Sciences(KSCX2-SW-322,KICX2-SW-L05).
文摘The lysozyme crystals were made by batch crystallization method and the distribution of aggregate in solution were measured by dynamic light scattering. The results showed that the dimension of aggregate increased with the increase of the concentration of lysozyme and NaCl, lysozyme molecules aggregated gradually in solution and finally arrived at balance each other. The higher the concentrations of lysozyme and NaCl were, the faster the growth rate of (110) face was. The growth rates of lysozyme crystal were obtained by a Zeiss microscope, and the effective surface energy (a) of growing steps were calculated about 4.01×10^-8s J·cm^-2 according to the model of multiple two-dimensional nucleation mechanism.
基金This work supported by the National Natural Science Foundation of China(No.30370945)Ministry of Science and Technology(G 2000078104,2003CCA02900)+2 种基金Guizhou Provincial Govemor Foundation(No.6,2001)Guizhou Education Department(No.206,2003)Guizhou Normal University Young Teachers Development Scientific Research Found.