Magnetic fluids may be classified as ferrofluids (FF), which are colloidal suspensions of very fine (~ 10 nm) magnetic particles, and magnetorheological fluids, which are suspensions of larger, usually non-stable, magnetic particles. We review the general classification and the main properties of FF, some theoretical models and a few applications. We consider the stability of a FF in terms of various forces and torques on the magnetic particles. We discuss thermodiffusion, which is an important phenomenon in FF, and which gives rise to the Soret effect. We also consider the rotational dynamics of the magnetic moments of the particles. A large portion of this review is dedicated to applications of FF, including a few of the many technological applications. Among the uses of a FF in the study of materials, we have selected the doping of liquid crystals. Among the very promising uses in Medicine, we discuss drug targeting, hyperthermia, cell separation, and contrast in magnetic resonance imaging. We also make some comments on directions for future research on the properties of ferrofluids.

We carried out Z-scan measurements on lyotropic liquid crystals and on lyotropic liquid crystals doped with ferrofluid. In these experiments, the sample is translated through the focal region of a focused Gaussian laser beam. The dependence of the far-field intensity on sample position due to intensity-dependent optical nonlinearities has been analyzed on the basis of the thermal-lens model of Gordon et al. and the Gaussian decomposition analysis of Sheik-Bahae et al. The thermal-lens model is nonlocal in space and time, whereas the Gaussian decomposition is predicated on a strictly local response. We compare the goodness of fit of the predictions of these models to experimental data, and we discuss limitations of these models in describing Z-scan experiments on systems with nonlocal response.

Mixtures of surfactant or amphiphilic molecules and solvents are known to display a large number of lyotropic mesophases. Although the physics of thermotropic liquid crystals has been vastly discussed in the literature, lyotropic mesophases have been much less explored. This book gives a unifying presentation of the structural and physical properties of lyotropic liquid crystalline systems, including a set of experimental results and a discussion of the characterization of different structures and the corresponding phase transitions. The initial chapters contain a description of the main experimental results and techniques associated with the characterization of lyotropic mixtures, and an overview of some theoretical approaches to account for the phase transitions and phase diagrams of these mesophases. This book includes discussions on periodically organized lyotropic systems, micellar and bicontinuous structures, modulated and cholesteric structures, and a number of related developments (magnetic colloids, microemulsions, films, and lyo-banana mesophases).

High‐resolution x‐ray measurements have been performed at the synchrotron of LURE (Orsay) to study both uniaxial (discotic and calamitic) and biaxial nematic lyomesophases of the mixture K‐laurate, 1‐decanol, and D₂O. The variations of the densitometric profiles of the diffracted bands are analyzed vs temperature. They are shown to be consistent with the model of similar micellar aggregates in the three nematic phases, undergoing different orientational fluctuations. It is moreover discussed that the micelles have, on the average, the shape of biaxial platelets with a (1/2/3) anisotropy, and that they build the same pseudolamellar structure in each nematic phase.

We introduce and shortly summarize a variety of more recent aspects of lyotropic liquid crystals (LLCs), which have drawn the attention of the liquid crystal and soft matter community and have recently led to an increasing number of groups studying this fascinating class of materials, alongside their normal activities in thermotopic LCs. The diversity of topics ranges from amphiphilic to inorganic liquid crystals, clays and biological liquid crystals, such as viruses, cellulose or DNA, to strongly anisotropic materials such as nanotubes, nanowires or graphene oxide dispersed in isotropic solvents. We conclude our admittedly somewhat subjective overview with materials exhibiting some fascinating properties, such as chromonics, ferroelectric lyotropics and active liquid crystals and living lyotropics, before we point out some possible and emerging applications of a class of materials that has long been standing in the shadow of the well-known applications of thermotropic liquid crystals, namely displays and electro-optic devices.

Background: Recently, there has been an increasing in the impact of oral health on atherosclerosis and subsequent cardiovascular disease. The aim of this study is to investigate the association between chronic periodontitis and cardiovascular risk markers.Methods: Forty patients with periodontitis and 40 healthy gender‐, body mass index–, and age‐matched individuals were compared by measuring total cholesterol, high‐density lipoprotein, low‐density lipoprotein, triglycerides, levels of cytokines, antibodies against oxidized low‐density lipoprotein, thiobarbituric acid reactive substances, total and differential white blood cell counts, and the non‐linear index of refraction.Results: The levels of triglycerides and high‐density lipoprotein in periodontitis patients were significantly higher and lower, respectively (P = 0.002 and P = 0.0126), compared to controls. Total cholesterol, low‐density lipoprotein, and lipid peroxide levels were the same in both groups (P = 0.2943, P = 0.1284, and P = 0.067, respectively). Interleukin (IL)‐6 and −8, antibodies against oxidized low‐density lipoprotein, and leukocyte and neutrophil counts were significantly higher in periodontitis patients (P <0.05). The value of the non‐linear index of refraction of low‐density lipoprotein solutions was higher in the controls (P = 0.015) compared to individuals with periodontitis.Conclusion: Our results confirmed and further strengthened the suggested association between coronary artery disease and periodontitis.