This thesis is mainly concerned with some important properties of complex fluids, and how these properties are influenced by structures in the nano/mesoscopic scale. Short-range assembly of the constituent molecules results in an amazing variety of phase behavior in these systems. Liquid-liquid phase transitions, or transitions from a homogeneous(mixed) phase to an immiscible phase (two-phase coexistence), are the outcome of a competition between entropy and short-ranged attractive forces, and form an important part of this thesis. A rich phase behavior is uncovered by a detailed study of liquid-liquid phase transitions in a mixture of ethanol(E) and water(W), induced by the addition of ammonium sulfate(AS) ions (E and W are otherwise completely soluble in each other). This is the main motivation for choosing this system. Furthermore, experimental evidence of the presence of supramolecular association in alcohol-water mixtures [J.-H. Guo et al., Phys. Rev Lett, 91, 15401(2003)] enhances our interest to study the phase behavior in more detail. The presence of a critical point, at which there is a second order phase transition, is quite common in complex fluids. An issue which has been the subject of extensive scientific research in recent years is the influence of nano/mesoscopic structure on the critical behavior of these fluids corresponds to the Ising universality class. However, the approach to the asymptotic regime is governed by a competition between the correlation length of critical concentration fluctuations and the additional length scale arising due to structuring., which results in a crossover from the universal Ising behavior to the mean-field behavior, sometimes within the critical domain. This phenomenon of crossover criticality is presently explored in the E + W + AS system. A significant portion of the thesis presents explorations on the critical behavior in the vicinity of special critical points (SCP), which are formed by the coalescence of two or.

The fourth Nishinomiya-Yukawa Memorial Symposium, devoted to the topic of dynamics and patterns in complex fluids, was held on October 26 and 27, 1989, in Nishinomiya City, Japan, where ten invited speakers gave their lectures. A one-day meeting, comprising short talks and poster sessions, was then held on the same topic on October 28 at the Research Institute for Fundamental Physics, Kyoto University. The present volume contains the 10 invited papers and 38 contributed papers presented at these two meetings. The symposium was sponsored by Nishinomiya City, where Prof. Hideki Yukawa once lived and where he wrote the celebrated paper describing the work that was later honored by a Nobel prize. The topic of the fourth symposium was chosen from one of the most vigorously evolving and highly interdisciplinary fields in condensed matter physics. The field of complex fluids is very diverse and still in its infancy and, as a result, the definition of a complex fluid varies greatly from one researcher to the next. One of the objectives of the symposium was to clarify its definition by explicitly posing a number of potentially rich problems waiting to be explored. Indeed, experimentalists are disclosing a variety of intriguing dynamical phenomena in complex systems such as polymers, liquid crystals, gels, colloids, and surfactant systems. We, the organizers, hope that the symposium will contribute to the increasing importance of the field in the coming years.

This book provides a self-contained presentation of optical methods used to measure the structure and dynamics of complex fluids subject to the influence of external fields. Such fields--hydrodynamic, electric, and magnetic--are commonly encountered in both academic and industrial research, and can produce profound changes in the microscale properties of liquids comprised of polymers, colloids, liquid crystals, or surfactants. Starting with the basic Maxwell field equations, this book discusses the polarization properties of light, including Jones and Mueller calculus, and then covers the transmission, reflection, and scattering of light in anisotropic materials. Spectroscopic interactions with oriented systems such as absorptive dichroism, small wide angle light scattering, and Raman scattering are discussed. Applications of these methods to a wide range of problems in complex fluid dynamics and structure are presented, along with selected case studies chosen to elucidate the range of techniques and materials that can be studied. As the only book of its kind to present a self-contained description of optical methods used for the full range of complex fluids, this work will be special interest to a wide range of readers, including chemical engineers, physical chemists, physicists, polymer and colloid scientists, along with graduate and post-graduate researchers.

This book is dedicated to the tube flow of viscoelastic fluids and Newtonian single and multi-phase particle-laden fluids. This succinct volume collects the most recent analytical developments and experimental findings, in particular in predicting the secondary field, highlighting the historical developments which led to the progress made. This book brings a fresh and unique perspective and covers and interprets efforts to model laminar flow of viscoelastic fluids in tubes and laminar and turbulent flow of single and multi-phase particle-laden flow of linear fluids in the light of the latest findings.

Complex liquids constitute a basic element in modern materials science; their significant features include self-assembly, mesoscale structures, complex dynamics, unusual phases and enormous sensitivity to perturbations. Understanding their nature and properties are a great challenge to modern materials science that demands novel approaches. This book focuses on nonlinear dielectric phenomena, particularly on nonlinear dielectric spectroscopy (NDS), which may be considered a possible successor to broadband dielectric spectroscopy (BDS). NDS phenomena directly coupled to mesoscale heterogeneity fluctuations, so information obtained in this way is basically complementary to BDS tests. The book also discusses the application of NDS in a set of complex liquid systems: glassy liquids, liquid crystals, liquids with critical point phenomena, and bio-relevant liquids. The complementary application of NDS and BDS may allow the discovery of universal patterns for the whole category of complex liquids. Written by specialists in the field of nonlinear dielectric studies, theoreticians and experimentalists, ranging from solid state physics to biophysics, the book is organized so that it can serve as a basic textbook for a non-experienced reader.

The aim of this book is to present the current state of the art of extracting natural products with near-critical solvents and to view the possibilities of further extensions of the technique. Relevant background theory is given but does not dominate the book. Carbon dioxide is the near-critical solvent used in most recent applications and inevitably receives prominence. In addition to general descriptions and reviews, the book contains three chapters by indus trial practitioners who describe in detail the operation of their processes and discuss the market for their products. Sections on the design of the pressure vessels and pumps required in these processes and on the acquisition of the data required for design are included. The costing of the processes is also discussed. There is good scope for combining a near-critical extraction step with other process steps in which the properties of near-critical solvents are utilised, for example as a reaction or crystallisation medium and a chapter is devoted to these important aspects. It is hoped that the work will be found to contain a great deal of specific information of use to those already familiar with this field. However the style of presentation and content is such that it will also be useful as an introduction. In particular it will be helpful to those wondering if this form of separation method has anything to offer for them, whether they are engineers, chemists or managers in industry, or in academic or research institutions.