Orientation dependence of optical activity in light scattering by nanoparticle clusters

The optical properties of nanoparticle clusters vary with the spatial arrangement of the constituent particles, but also the overall orientation of the cluster with respect to the incident light. This...

Forensic determination of determination of damage to human internal organs by the method of reconstruction of the optical activity of histological sections

The article presents the results of experimental testing of the technique of tomographic reconstruction of circular birefringence maps of molecular complexes in a digital histological study of the age of damage to tissues of internal organs (brain, liver and kidney) of temporary monitoring of the mean value, dispersion, asymmetry and kurtosis, characterizing the distribution of the magnitude of the optical activity of histological sections of the brain, liver and kidney identification of the temporal extent of linear changes in statistical parameters and the accuracy of determining the duration of damage to human internal organs by digital histological methods of polarization reconstruction (tomography) of circular birefringence of molecular complexes. Aim of the work. Development of a technique for determining the duration of damage to human internal organs by digital histological methods of polarization reconstruction of circular birefringence of molecular complexes. Materials and methods. The object of the study was the histology of samples of human internal organs (brain, kidney and liver) with different duration of damage from 1 hour to 120 hours. For control, we used BT samples of those who died from coronary artery disease with different duration of damage from 1 hour to 120 hours. The studies were carried out using the technique of polarization reconstruction of circular birefringence of molecular complexes. Results. A set of treatment-relevant relationships between temporal changes in the statistical structure of topographic maps of circular birefringence of optically active molecular complexes of histological sections of human internal organs with different duration of damage and variations in the mean value, dispersion, asymmetry and kurtosis, characterizing the distribution of the value of this parameter of anisotropy, has been determined. Conclusions. A new original method has been developed for tomography of the optical activity of molecular complexes of tissues of human internal organs in a digital histological study of the age of damage to the tissues of the brain, liver and kidney, as well as the myocardium and lung tissue at a time interval of 1 hour. up to 120 hours

Statistical Theory of Helical Twisting in Nematic Liquid Crystals Doped with Chiral Nanoparticles

A molecular field theory of the cholesteric ordering in nematic nanocomposites doped with chiral nanoparticles was developed taking into consideration chiral dispersion interaction between rod-like nanoparticles. It was shown that the inverse pitch of the cholesteric helical structure is proportional to the anisotropy of the effective polarizability and the anisotropy of the effective gyration tensor of a nanoparticle in the nematic host. The theory enables one to predict the helical sense inversion induced by a change of the low-frequency dielectric susceptibility of the nematic host phase. The components of the high-frequency effective polarizability and the effective optical activity of a gold rod-like nanoparticle in a particular nematic solvent were calculated numerically.

Enhanced gyrotropic birefringence and natural optical activity on electromagnon resonance in a helimagnet

Spontaneous symmetry breaking in crystalline solid often produces exotic nonreciprocal phenomena. As one such example, the unconventional optical rotation with nonreciprocity, which is termed gyrotropic birefringence, is expected to emerge from the magnetoelectric coupling. However, the fundamental nature of gyrotropic birefringence remains to be examined. Here w`e demonstrate the gyrotropic birefringence enhanced by the dynamical magnetoelectric coupling on the electrically active magnon resonance, i.e. electromagnon, in a multiferroic helimagnet. The helical spin order having both polarity and chirality is found to cause the giant gyrotropic birefringence in addition to the conventional gyrotropy, i.e. natural optical activity. It is demonstrated that the optical rotation of gyrotropic birefringence can be viewed as the nonreciprocal rotation of the optical principal axes, while the crystallographic and magnetic anisotropies are intact. The independent control of the nonreciprocal linear (gyrotropic birefringence) and circular (natural optical activity) birefringence/dichroism paves a way for the optically active devices.