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Author: Runfang Mao
Publisher:
ISBN:
Category : Energy dissipation
Languages : en
Pages : 33
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Book Description
Dissipative particle dynamics simulation with novel model is applied to predict aggregation in ionic surfactants. Anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant cetyl trimethyl ammonium bromide (CTAB) are chosen as characteristic examples. Coarse-grained models are constructed from infinite dilution activity coefficient in reference solutions and atomistic simulations. Ionic groups are modeled as beads with charges distributed around the bead centers and placed in implicit dielectric medium. The model of ionic surfactant semi-quantitatively reproduces the dependence of self-assembly in solutions of CTAB and SDS on surfactant concentration, the molarity of added electrolyte. In particular, the decline of the free surfactant concentration with increasing total surfactant loading, as well as the aggregation transition in single-component surfactant cause by salt addition are predicted correctly. Addition of CTAB to a micellar solution of SDS causes a transition to worm-like micelles and then to mini-vesicles. This systematic methodology has been further extended to carbopol system. A stable carbopol film has been observed after equilibrium based on this model. Further investigation to study rheology of surfactant-carbopol system are required in future work, like add surfactant into this system.
Author: Runfang Mao
Publisher:
ISBN:
Category : Energy dissipation
Languages : en
Pages : 33
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Book Description
Dissipative particle dynamics simulation with novel model is applied to predict aggregation in ionic surfactants. Anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant cetyl trimethyl ammonium bromide (CTAB) are chosen as characteristic examples. Coarse-grained models are constructed from infinite dilution activity coefficient in reference solutions and atomistic simulations. Ionic groups are modeled as beads with charges distributed around the bead centers and placed in implicit dielectric medium. The model of ionic surfactant semi-quantitatively reproduces the dependence of self-assembly in solutions of CTAB and SDS on surfactant concentration, the molarity of added electrolyte. In particular, the decline of the free surfactant concentration with increasing total surfactant loading, as well as the aggregation transition in single-component surfactant cause by salt addition are predicted correctly. Addition of CTAB to a micellar solution of SDS causes a transition to worm-like micelles and then to mini-vesicles. This systematic methodology has been further extended to carbopol system. A stable carbopol film has been observed after equilibrium based on this model. Further investigation to study rheology of surfactant-carbopol system are required in future work, like add surfactant into this system.
Author: Neil Denham
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A mesoscale dynamics simulation using a Dissipative Particle Dynamics regime was developed to investigate the ability of small molecules to control phase structures in non-ionic surfactant-water systems. The ability to control phase structure has positive implications for potential templating applications which require ordered and stable phases with high surface curvature. The phases present in such systems were successfully modelled, the results of which compare well with experiment. Additives which decreased the surface curvature of the interfacial region included oils and long-chained alcohols. These molecules destabilised high-surface curvature phases, such as the bicontinuous cubic and mesh phases, in favour of the lamellar phase. However, the addition of anaesthetics and short-chained alcohols, which are small amphiphilic molecules, promote surface curvature, and there is an optimum chain length for maximum stability of the mesh phase. Coulombic interactions, although unsuccessfully modelled with the simulations, were found to be important through Langmuir trough investigations adding ionic and nonionic anaesthetics to non-ionic surfactant and ionic lipid monolayers, as ionic monolayer-anaesthetic combinations showed a larger increase in surface pressure compared to the non-ionic monolayer-anaesthetic combination. It is therefore very difficult to engineer phase structures for templating applications because the extreme chemical environment in the templating solution would serve to destabilise any high surface curvature these additives would stabilise.
Author: Sarah Jane Gray
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: N. S. Martys
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Dennis Y.C. Leung
Publisher: CRC Press
ISBN: 1315815079
Category : Science
Languages : en
Pages : 337
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Book Description
Fuel cells are clean and efficient energy conversion devices expected to be the next generation power source. During more than 17 decades of research and development, various types of fuel cells have been developed with a view to meet the different energy demands and application requirements. Scientists have devoted a great deal of time and effort
Author: Huixiao Hong
Publisher: Springer
ISBN: 3030164438
Category : Science
Languages : en
Pages : 412
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Book Description
This book provides a comprehensive review of both traditional and cutting-edge methodologies that are currently used in computational toxicology and specifically features its application in regulatory decision making. The authors from various government agencies such as FDA, NCATS and NIEHS industry, and academic institutes share their real-world experience and discuss most current practices in computational toxicology and potential applications in regulatory science. Among the topics covered are molecular modeling and molecular dynamics simulations, machine learning methods for toxicity analysis, network-based approaches for the assessment of drug toxicity and toxicogenomic analyses. Offering a valuable reference guide to computational toxicology and potential applications in regulatory science, this book will appeal to chemists, toxicologists, drug discovery and development researchers as well as to regulatory scientists, government reviewers and graduate students interested in this field.
Author: Bastian E. Rapp
Publisher: Elsevier
ISBN: 0128240237
Category : Technology & Engineering
Languages : en
Pages : 850
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Book Description
Microfluidics: Modeling, Mechanics and Mathematics, Second Edition provides a practical, lab-based approach to nano- and microfluidics, including a wealth of practical techniques, protocols and experiments ready to be put into practice in both research and industrial settings. This practical approach is ideally suited to researchers and R&D staff in industry. Additionally, the interdisciplinary approach to the science of nano- and microfluidics enables readers from a range of different academic disciplines to broaden their understanding. Alongside traditional fluid/transport topics, the book contains a wealth of coverage of materials and manufacturing techniques, chemical modification/surface functionalization, biochemical analysis, and the biosensors involved. This fully updated new edition also includes new sections on viscous flows and centrifugal microfluidics, expanding the types of platforms covered to include centrifugal, capillary and electro kinetic platforms. Provides a practical guide to the successful design and implementation of nano- and microfluidic processes (e.g., biosensing) and equipment (e.g., biosensors, such as diabetes blood glucose sensors) Provides techniques, experiments and protocols that are ready to be put to use in the lab, or in an academic or industry setting Presents a collection of 3D-CAD and image files on a companion website
Author: Henri L. Rosano
Publisher: CRC Press
ISBN: 9780824774394
Category : Science
Languages : en
Pages : 464
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Book Description
Author: Mohamed Daoud
Publisher: Springer Science & Business Media
ISBN: 3662038455
Category : Science
Languages : en
Pages : 335
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Book Description
In a liquid crystal watch, the molecules contained within a thin film of the screen are reorientated each second by extremely weak electrical signals. Here is a fine example of soft matter: molecular systems giving a strong response to a very weak command signal. They can be found almost everywhere. Soft magnetic materials used in transformers exhibit a strong magnetic moment under the action of a weak magnetic field. Take a completely different domain: gelatin, formed from col lagen fibres dissolved in hot water. When we cool below 37°C, gelation occurs, the chains joining up at various points to form a loose and highly deformable network. This is a natural example of soft matter. Going further, rather than consider a whole network, we could take a single chain of flexible polymer, such as polyoxyethylene [POE = (CH CH O)N, 2 2 5 where N rv 10 ], for example, in water. Such a chain is fragile and may break under flow. Even though hydrodynamic forces are very weak on the molecular scale, their cumulated effect may be significant. Think of a rope pulled from both ends by two groups of children. Even if each girl and boy cannot pull very hard, the rope can be broken when there are enough children pulling.
Author: Edward J. Maginn
Publisher: Springer Nature
ISBN: 9813366397
Category : Science
Languages : en
Pages : 228
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Book Description
This highly informative and carefully presented book comprises select proceedings of Foundation for Molecular Modelling and Simulation (FOMMS 2018). The contents are written by invited speakers centered on the theme Innovation for Complex Systems. It showcases new developments and applications of computational quantum chemistry, statistical mechanics, molecular simulation and theory, and continuum and engineering process simulation. This volume will serve as a useful reference to researchers, academicians and practitioners alike.
