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The magnetic field induced birefringence in isotropic aqueous suspensions of tobacco mosaic virus (TMV) was measured as a function of temperature and concentration in high magnetic fields (100 kG). The temperature range was between 15 and 50 °C and the concentration range was between 4 and 20 mg/cm3. We find that the Cotton–Mouton constant (C) increases with decreasing temperature by 15%–20% over the entire range and extrapolates to infinity at a finite temperature of 110 to 150 K. At constant temperature, the measured ρ/C(ρ=number of TMV particles per cm3 of suspension) can be expanded in a power series of ρ, where the coefficients are expressed by the irreducible cluster integrals. At 20 °C the experimental values can be fitted to the linear form: ρ/λC=(2.09×1030–1.35×1015ρ)G2/cm3. For rigid cylindrical particles with l=3000 Å and d=180 Å, and using the rigid hard particle interaction model, we find for the first order coefficient 0.62×1015, i.e., a significant deviation for the rigid hard-rod model. This deviation is also indicated by the variation of C with temperature. We discuss the results on TMV and of similar measurements on phage fd in terms of the interparticle interaction and rigidity of the particles. [ABSTRACT FROM AUTHOR]

In interface instabilities, deformations first grow exponentially, then enter a nonlinear regime affecting amplitude and symmetry. Most extant studies have focused on amplitude alone. Here, we study a 2D Rayleigh-Taylor instability for an initial sinusoidal deformation, analyzing its amplitude and asymmetry over time. For the latter, we define a metric based on the zero crossings of the interface. We develop a weakly nonlinear model and compare it to experimental data. It shows that our asymmetry metric complements the amplitude for an improved description of the instabilities' nonlinear phases. [ABSTRACT FROM AUTHOR]

Recently the nontrivial spatial and temperature dependence of the surface-induced weak planar orientational order parameter Q( z, T) was determined just above the isotropic-nematic (IN) phase transition point (Ji-H. Lee et al., Phys. Rev. Lett. 102, 167801 (2009)). In this paper we present a theoretical explanation of the observed behaviour. We obtain expressions for the short-range and long-range contributions to the interface potential of the induced nematic film and specify the repulsive character of the interaction between the soft IN interface and the external bounding substrate. It is shown that the small value of the IN interfacial tension results in the renormalization of the repulsive interaction potential due to the thermal fluctuations of the soft IN interface. This leads to an increase of the equilibrium thickness of the induced nematic film and the appearance of a step-like orientational order parameter profile. We find that only renormalized short-range and thermal pseudo-Casimir interactions are essential for the appearance of the induced nematic film, which provide the observed thickness, h ∼ 30 nm, of this film. The long-range van der Waals interaction is shown to be negligibly small and the dominant role is played by the renormalized short-range repulsion. Fitting of the experimental order parameter profiles (Ji-H. Lee et al. (2009)) with the expressions based on these interactions makes it possible to determine the material parameters of the system, including the amplitudes of the surface interaction, the IN interfacial tension and the interfacial coherence length. The agreement between theory and experiment confirms the importance of the interface fluctuation renormalization of the interface potentials for soft interfaces. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study was to find HPV DNA incidence in women with CIN and normal women and in their respective partners, as well as the relation between the virus groups found in women with CIN or normal women and in their respective partners.Methods: Partners of 30 women with CIN at several grades and of 60 normal women were prospectively assessed. In men, HPV search was performed by collecting samples through penile scraping for Hybrid Capture, followed by peniscopic evaluation and biopsy of acetowhite lesions.Results: The presence of HPV DNA in male partners does not necessarily implicate the presence of HPV or even CIN in their female partners.Conclusions: If these results are confirmed by other authors, obtaining a peniscopy, a penile biopsy, and a HPV DNA search in partners that present with no clinical lesions, but in couples with women having CIN, would not be warranted. [ABSTRACT FROM AUTHOR]

It has been widely recognized that the combination of carbon nanotube (CNT) and liquid crystals (LCs) not only provides a useful way to align CNTs, but also dramatically enhances the order in the LC phases, which is especially useful in liquid crystal display (LCD) technology. As the measure of this phase behavior, the complex specific heat is presented over a wide temperature range for a negative dielectric anisotropy alkoxyphenylbenzoate liquid crystal (9OO4) and CNT composites as a function of CNT concentration. The calorimetric scans were performed under near-equilibrium conditions between 25 and 95°C, first cooling and then followed by heating for CNT weight percent ranging from ɸw = 0 to 0.2. All 9OO4/CNT mesophases have transition temperatures ~1 K higher and a crystallization temperature 4 K higher than that of the pure 9OO4. The crystal phase superheats until a strongly first-order specific heat feature is observed, 0.5 K higher than in the pure 9OO4. The transition enthalpy for the nanocomposite mesophases is 10% lower than that observed in the pure 9OO4. The strongly first-order crystallization and melting transition enthalpies are essentially constant over this range of ɸw. Complementary electroclinic measurement on a 0.05 wt. % sample, cooling towards the smectic-C phase from the smectic-A, indicates that the SmA-SmC transition remains mean-field-like in the presence of the CNTs. Given the homogeneous and random distribution of CNTs in these nanocomposites, we interpret these results as arising from the LC-CNT surface interaction pinning the orientational order uniformly along the CNT, without pinning the position of the 9OO4 molecule, leading to a net ordering effect for all phases. These effects of incorporating CNTs into LCs are likely due to "anisotropic orientational" coupling between CNT and LC, the change in the elastic properties of composites and thermal anisotropic properties of the CNTs. [ABSTRACT FROM AUTHOR]

The so-called chiral smectic C-beta (SmC*beta) phase has been reported as distinct from the SmC* phase in several materials that exhibit antiferroelectric liquid crystal mesophases and subphases. The SmC*beta phase is known to be chiral, tilted and to exhibit ferrielectric switching, but no structure had been suggested which explains these effects. This paper presents a possible structure for the SmC*beta phase which can explain the ferrielectric properties. The model is proposed on the basis of complementary optical, electric and X-ray diffraction studies of a chiral liquid crystal. The layer spacing, optical and steric tilt and spontaneous polarization over the temperature range of the SmC*beta phase are described. The complementary experimental techniques used reveal the occurrence of inversion phenomena, on which this model is based. [ABSTRACT FROM AUTHOR]