The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Jinjia Wei - One of the best experts on this subject based on the ideXlab platform.
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Influence of Salts on Morphology of Structures in Surfactant-Polymer Solutions Explored by Coarse Grained Dynamic Simulation
Computational and Experimental Simulations in Engineering, 2020Co-Authors: Dongjie Liu, Wenjing Zhou, Fei Liu, Fei Chen, Jinjia WeiAbstract:In this study, a Coarse-Grained Molecular Dynamic Dynamics simulation Simulation was employed to test the influence of salts in morphology of structures in surfactant-polymer solutions. The surfactant was cetyltrimethyl ammonium chloride (CTAC) and the polymer was polyacrylamide (PAM). Six different salt concentrations were studied in the mixed surfactant-polymer solutions, and pure surfactant solutions with salts were also tested as control groups. By analyzing the shapes of micelles and the CTA^+ aggregation number of micelles, we noted that the proper salt concentration can facilitate the formation of large micelles. In too high or too low salt concentration solutions only spherical or short rodlike micelles exist. The existence of PAM can also facilitate the formation of large micelles because polymers act as “bridges” and increase the probability of touch and coalescence of micelles.
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Molecular Dynamics simulation of self-assembly and viscosity behavior of PAM and CTAC in salt-added solutions
Journal of Molecular Liquids, 2018Co-Authors: Dongjie Liu, Wenjing Zhou, Fei Liu, Fei Chen, Jinjia WeiAbstract:Abstract In this study, the self-assembly of cationic surfactant cetyltrimethyl ammonium chloride (CTAC) and nonionic polymer polyacrylamide (PAM) in aqueous solution with added sodium salicylate (NaSal) as counter-ion salt is studied using a Coarse-Grained Molecular Dynamic simulation (CGMD). The microstructure evolution shows that in the mixed solutions, surfactant micelles are readily to associate with polymer and can form a new complex of CTAC and PAM with interconnected network structures, which can be attributed to the hydrophobic interactions, the attraction between acylamino and the head of CTAC, and the attraction between Sal− and acylamino. The calculation of radial distribution function for different sites also proved the aggregate of the surfactant and polymer. Then a reverse non-equilibrium Molecular Dynamics (RNEMD) simulation is used to investigate the rheological property of the mixed solutions, the CTAC/NaSal solution and the PAM solution. The Molecular Dynamics simulation demonstrates that the viscosity of the CTAC/PAM/NaSal solution is significantly higher than that of the CTAC/NaSal solution, mainly because the surfactant micelles interacted with the polymer and formed rod-like micelles.
Bernd Sachweh - One of the best experts on this subject based on the ideXlab platform.
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Mesoscale modeling of emulsification in rotor-stator devices: Part II: A model framework integrating emulsifier adsorption
Chemical Engineering Science, 2019Co-Authors: Chao Chen, Xiaoping Guan, Ying Ren, Ning Yang, Christian Kunkelmann, Eduard Schreiner, Christian Holtze, Kerstin Mülheims, Bernd SachwehAbstract:Abstract Precise and rational control of droplet size distribution (DSD) is important in emulsification for target-oriented product design. To develop a complete DSD model, crossing the two mesoscales of two different levels is of great significance, viz., the emulsifier adsorption at interfacial level (Mesoscale 1) and the droplet breakage and coalescence in turbulence in rotor-stator device level (Mesoscale 2). While the first mesoscale can be simulated by Coarse-Grained Molecular Dynamic (CGMD), the second has been investigated in computational fluid Dynamics and population balance model (CFD-PBM) simulation through the Energy-Minimization Multi-Scale (EMMS) approach in Part I. We then developed a model framework in Part II, coupling CGMD and CFD-PBM simulation through surfactant transport equations in bulk phase and at interface, with source terms taking account of emulsifier adsorption parameters. The parameters including maximal adsorption amount, diffusion coefficient and adsorption/desorption kinetic constants are acquired from CGMD. The coalescence efficiency is then corrected by the interfacial area fraction not occupied by surfactant and fed into the coalescence kernel functions in PBM. Compared to traditional CFD-PBM simulation, the coupled model can greatly improve the simulation of DSD, Sauter mean diameter, median diameter and span for high dispersed phase amount (DPA), and correctly reflect the influence of DPA, surfactant concentration and rotational speed of rotor-stator (RS) devices. While the simulation cases validate and demonstrate the advantage of this new model framework, it is also promising to incorporate different types of surfactant in future.
Xinyuan Shi - One of the best experts on this subject based on the ideXlab platform.
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Multiscale study on the enhancing effect and mechanism of borneolum on transdermal permeation of drugs with different log P values and Molecular sizes.
International journal of pharmaceutics, 2020Co-Authors: Chang Yang, Shujuan Guo, Xingxing Dai, Pengshuo Yang, Lu Han, Xinyuan ShiAbstract:Abstract D-borneolum is commonly used as a permeation enhancer in Traditional Chinese Medicine (TCM) formulas for transdermal application. Additionally, two other sources of borneolums were recorded in the 2015 edition of the Chinese Pharmacopoeia (ChP), including L-borneolum and borneolum syntheticum. To guide the selection and application of borneolum, the safety and enhancing effect of three sources of borneolums were investigated on transdermal permeation of compounds with different octanol-water partition coefficient (log P) values and Molecular weights (MWs). Both the results of cellular cytotoxicity and in vitro transdermal permeation experiments showed that all three sources of borneolums could be applied in TDDS as permeation enhancers. Moreover, all three sources of borneolums achieved optimal permeation-enhancing performances on transdermal drugs with lower log P values as well as higher MWs. Further study was carried out to elucidate the potential Molecular mechanism of borneolum enhancing transdermal drug delivery via transmission electron microscope (TEM) and Coarse-Grained Molecular Dynamic (CG-MD) simulation. Borneolum significantly promoted transdermal delivery of drugs via changing the dense morphology of the stratum corneum (SC), disturbing the ordered arrangement of ceramide (CER) and free fatty acid (FFA) molecules in lipid layers, and further increasing the diffusion rate of drugs in the lipid layers.
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Influence of Temperature on Transdermal Penetration Enhancing Mechanism of Borneol: A Multi-Scale Study.
International journal of molecular sciences, 2017Co-Authors: Qianqian Yin, Ran Wang, Shufang Yang, Shujuan Guo, Xingxing Dai, Yanjiang Qiao, Xinyuan ShiAbstract:The influence of temperature on the transdermal permeation enhancing mechanism of borneol (BO) was investigated using a multi-scale method, containing a Coarse-Grained Molecular Dynamic (CG-MD) simulation, an in vitro permeation experiment, and a transmission electron microscope (TEM) study. The results showed that BO has the potential to be used as a transdermal penetration enhancer to help osthole (OST) penetrate into the bilayer. With the increasing temperature, the stratum corneum (SC) becomes more flexible, proving to be synergistic with the permeation enhancement of BO, and the lag time (TLag) of BO and OST are shortened. However, when the temperature increased too much, with the effect of BO, the structure of SC was destroyed; for example, a water pore was formed and the micelle reversed. Though there were a number of drugs coming into the SC, the normal bilayer structure was absent. In addition, through comparing the simulation, in vitro experiment, and TEM study, we concluded that the computer simulation provided some visually detailed information, and the method plays an important role in related studies of permeation.
Qing-sheng Yang - One of the best experts on this subject based on the ideXlab platform.
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Coarse-Grained modeling of carbon nanostructures and their composites
2016Co-Authors: Qing-sheng YangAbstract:Carbon nanotube (CNT) and graphene have attracted great attention due to their excellent mechanical and electrical properties. A variety of multi-functional structures based on CNTs and graphene will be applied in plenty of industrial applications. In order to uncover the essential mechanisms of these structures, such as electro-mechanical coupling mechanism, it is necessary to develop overall simulations. Accordingly, multi-scale models for these nanostructures were developed based on a coarse-graining technique. The course-grained model includes Coarse-Grained Molecular Dynamic (CGMD) models and coarse-grid Molecular structural mechanic (CGMSM) model. On one hand, by using the CGMD model, static and cyclic tensile tests of CNT fibers and their composites were reproduced for analyzing their mechanical properties and multi-structural evolution. In addition, the deformation and failure behavior of the CNT fibers induced by an electric field were also studied via the CGMD method. On the other hand, the CGMSM method can apply to simulations of the cross-linked nanostructures under static loads. For example, the CGMSM method was used in simulations of graphite sheets. Consequently, coarse-graining of carbon nanostructures will provide an efficient and effective way for studying a lot more nanostructures in the future.
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Plastic deformation and failure mechanisms of collapsed-carbon nanotube fibers by Coarse-Grained Molecular Dynamic simulations
International Journal of Plasticity, 2015Co-Authors: Xia Liu, Qing-sheng YangAbstract:Abstract Continuous macroscopic carbon nanotube (CNT) fiber is made of meso-scale bundles, where most CNTs are well aligned along the fiber axis direction. This paper presents a multi-scale model of the CNT fiber by using shape-based coarse-graining technique. Simulations of monotonic and cyclic tensile tests were conducted to study plastic deformation and micro-structural evolution of the CNT fiber. It is shown that the plastic deformation of the CNT fiber generates after short elastic-like deformation under tensile loading, and is closely correlated with strain rate of the applied load. In addition, plastic deformation process of the CNT fiber is determined by different factors in two strain rate ranges, i.e. inter-bundle interaction at low strain rates and mechanical properties of CNT bundles at high strain rates.
Dongjie Liu - One of the best experts on this subject based on the ideXlab platform.
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Influence of Salts on Morphology of Structures in Surfactant-Polymer Solutions Explored by Coarse Grained Dynamic Simulation
Computational and Experimental Simulations in Engineering, 2020Co-Authors: Dongjie Liu, Wenjing Zhou, Fei Liu, Fei Chen, Jinjia WeiAbstract:In this study, a Coarse-Grained Molecular Dynamic Dynamics simulation Simulation was employed to test the influence of salts in morphology of structures in surfactant-polymer solutions. The surfactant was cetyltrimethyl ammonium chloride (CTAC) and the polymer was polyacrylamide (PAM). Six different salt concentrations were studied in the mixed surfactant-polymer solutions, and pure surfactant solutions with salts were also tested as control groups. By analyzing the shapes of micelles and the CTA^+ aggregation number of micelles, we noted that the proper salt concentration can facilitate the formation of large micelles. In too high or too low salt concentration solutions only spherical or short rodlike micelles exist. The existence of PAM can also facilitate the formation of large micelles because polymers act as “bridges” and increase the probability of touch and coalescence of micelles.
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Molecular Dynamics simulation of self-assembly and viscosity behavior of PAM and CTAC in salt-added solutions
Journal of Molecular Liquids, 2018Co-Authors: Dongjie Liu, Wenjing Zhou, Fei Liu, Fei Chen, Jinjia WeiAbstract:Abstract In this study, the self-assembly of cationic surfactant cetyltrimethyl ammonium chloride (CTAC) and nonionic polymer polyacrylamide (PAM) in aqueous solution with added sodium salicylate (NaSal) as counter-ion salt is studied using a Coarse-Grained Molecular Dynamic simulation (CGMD). The microstructure evolution shows that in the mixed solutions, surfactant micelles are readily to associate with polymer and can form a new complex of CTAC and PAM with interconnected network structures, which can be attributed to the hydrophobic interactions, the attraction between acylamino and the head of CTAC, and the attraction between Sal− and acylamino. The calculation of radial distribution function for different sites also proved the aggregate of the surfactant and polymer. Then a reverse non-equilibrium Molecular Dynamics (RNEMD) simulation is used to investigate the rheological property of the mixed solutions, the CTAC/NaSal solution and the PAM solution. The Molecular Dynamics simulation demonstrates that the viscosity of the CTAC/PAM/NaSal solution is significantly higher than that of the CTAC/NaSal solution, mainly because the surfactant micelles interacted with the polymer and formed rod-like micelles.