BINOCULAR INTERACTION IN AMBLYOPIA.

The review presents new ideas about developmental mechanisms of amblyopia, which are currently discussed in literature. Objective evidence has accumulated that amblyopia affects both monocular and binocular functions in visual processing. Given the increasing evidence of fundamental and clinical research, it is most likely that binocular dysfunction is primary, and monocular reduction is visual acuity is secondary to this disease.

LASER INDUCED FLUORESCENCE OF SKIN: SUPERPOSITION OF SPECTRAL INTENSITIES.

The aim of the work was to determine the possibility of assessing the state of human health by the method of optical spectroscopy of skin and nail. To achieve this goal, Laser-Induced Fluorescence (LIF) spectroscopy was used. A special probe was designed, which makes it possible to record differential spectra and, as a result, to compare the shapes of spectral fluorescence lines.

Cholesteric liquid crystal mirror-based imaging Stokes polarimeter.

We have developed a cholesteric liquid crystal (CLC) mirror-based innovative model for detection and visualization of images in turbid media. Due to its unique optical-polarization properties, the CLC mirror is suggested as the basic element of the imaging Stokes polarimeter. The particular design of the proposed polarimeter, coupled with its distinguished operational simplicity, reliability, and real-time operational facilities, promises to fabricate a new generation of the imaging Stokes polarimeter, which can find applications in areas such as diagnostics, biology, astronomy, and remote sensing.

Direct measurements of structural forces and twist transitions in cholesteric liquid crystal films with a surface force apparatus.

Using a surface force apparatus, a cholesteric liquid crystal was confined between two crossed cylindrical surfaces that induced strong planar anchoring and normal alignment of the chiral helix. The film thickness and total twist angle of the chiral molecular structure were simultaneously measured using multiple-beam optical interference. As the film thickness was increased and the chiral structure deformed, the twist angle remained almost unchanged until discontinuous changes occurred at critical distances that were equally spaced by one cholesteric half-pitch length.

Liquid crystal blue phases interconversions based real-time thermal imaging device.

The real-time thermal imaging systems, which allow the rapid conversion, acquisition, and manipulation of obtained optical information, are the emerging technologies that offer a variety of imaging applications. Here, we present a novel type of thermal imaging device, based on the thermo-optical properties of liquid crystal blue phases. Herewith, the novelty lies in the use of a weak first-order phase transition between the blue phases controlled by external thermal fields.

Temperature-tunable lasing from dye-doped chiral microdroplets encapsulated in a thin polymeric film.

In the last decade, much interest has grown around the possibility to use liquid-crystal droplets as optical microcavities and lasers. In particular, 3D laser emission from dye-doped cholesteric liquid crystals confined inside microdroplets paves the way for many applications in the field of sensors or tunable photonics. Several techniques can be used to obtain small microresonators as, for example, dispersing a liquid crystal inside an immiscible isotropic fluid to create an emulsion.

Mixed emulsion of liquid crystal microresonators: towards white laser systems.

Microdroplet systems have attracted great interest because of their wide range of applications, easiness in processing and handling, feasibility in developing miniaturized devices with high performances and large flexibility. In this study, a stable emulsion based on different dye-doped chiral liquid crystal droplets has been engineered in order to achieve simultaneous omnidirectional lasing at different wavelengths. To obtain the mixed emulsion of dye doped Bragg onion-type microresonators the twofold action, as a surfactant and a droplet stabilizer, of the polyvinyl alcohol dissolved in water has been exploited.

Light controlled drug delivery containers based on spiropyran doped liquid crystal micro spheres.

We have developed a novel, light activated drug delivery containers, based on spiropyran doped liquid crystal micro spheres. Upon exposure to UV/violet light, the spiropyran molecules entrapped inside the nematic liquid crystal micro spheres, interconvert from the hydrophobic, oil soluble form, to the hydrophilic, water soluble merocyanine one, which stimulates the translocation of the merocyanine molecules across the nematic liquid crystal-water barrier and results their homogeneous distribution throughout in an aqueous environment. Light controllable switching property and extremely high solubility of spiropyran in the nematic liquid crystal, promise to elaborate a novel and reliable vehicles for the drug delivery systems.

Detection of Gold Nanoparticles Aggregation Growth Induced by Nucleic Acid through Laser Scanning Confocal Microscopy.

The gold nanoparticle (GNP) aggregation growth induced by deoxyribonucleic acid (DNA) is studied by laser scanning confocal and environmental scanning electron microscopies. As in the investigated case the direct light scattering analysis is not suitable, we observe the behavior of the fluorescence produced by a dye and we detect the aggregation by the shift and the broadening of the fluorescence peak. Results of laser scanning confocal microscopy images and the fluorescence emission spectra from lambda scan mode suggest, in fact, that the intruding of the hydrophobic moiety of the probe within the cationic surfactants bilayer film coating GNPs results in a Förster resonance energy transfer.

Rewritable Optical Storage with a Spiropyran Doped Liquid Crystal Polymer Film.

Rewritable optical storage has been obtained in a spiropyran doped liquid crystal polymer films. Pictures can be recorded on films upon irradiation with UV light passing through a grayscale mask and they can be rapidly erased using visible light. Films present improved photosensitivity and optical contrast, good resistance to photofatigue, and high spatial resolution.

Endothelial-like nitric oxide synthase immunolocalization by using gold nanoparticles and dyes.

Immunofluorescence is a biological technique that allows displaying the localization of the target molecule through a fluorescent microscope. We used a combination of gold nanoparticles and the fluorescein isothiocianate, FITC, as optical contrast agents for laser scanning confocal microscopy imaging to localize the endothelial-like nitric oxide synthase in skeletal muscle cells in a three-dimensional tissue phantom at the depth of 4µm. The FITC detected fluorescence intensity from gold-nanoparticles-labelled cells was brighter than the emission intensity from unlabelled cells.

Light-controllable linear dichroism in nematics.

We report a method to obtain a light-controllable dichroism. The main effect is achieved using spiropyran-doped (SP-doped) nematic liquid crystal mixtures. SP molecules exhibit a high solubility in the liquid crystal host, which can vary between 1% and 4% in weight, without destroying the liquid crystalline phase.

Electrically controllable multicolor cholesteric laser.

A new strategy to obtain multicolor lasing from cholesteric liquid crystals is presented. A four layer cell is prepared with three different cholesteric layers and a layer containing a photoluminescent dye. The three cholesteric mixtures are prepared so that their photonic band gaps are partially overlapped.

Visual micro-thermometers for nanoparticles photo-thermal conversion.

We present a method to calibrate the light to heat conversion in an aqueous fluid containing nanoparticles. Accurate control of light and heat is of dramatic importance in many fields of science and metal nanoparticles have acquired an increased importance as means to address heat in very small areas when irradiated with an intense light. The proposed method enables to measure the temperature in the environment surrounding nanoparticles, as a function of the exposure time to laser radiation, exploiting the properties of thermochromic cholesteric liquid crystals.

Cholesteric liquid crystal holographic laser.

A new type of lasing was obtained on the basis of a dye-doped cholesteric liquid crystal laser with transversally distributed excitation. Two coherent beams of the pumping laser formed an interference pattern in the planar dye-doped cholesteric layer and provided laser generation in the separate narrow strips of the pumped area. Each of the strips demonstrated lasing along the cholesteric axis.

Paper like cholesteric interferential mirror.

A new type of flexible cholesteric liquid crystal mirror is presented. The simple and effective method for the deposition of a cholesteric mixture on a paper substrate and the particular design of the device give a homogeneous alignment of the cholesteric texture providing mirrors with an intense and uniform light reflectance. A desired polarization state for the reflected light, linear or circular, can be easily obtained varying the thickness and optical anisotropy of the polymer cover film.

Possibility of using near infrared irradiation for early cancer diagnosis.

Penetration of near infrared radiation (NIR) through biological tissues (human wrist, muscle and skin of hen, muscle of mollusk) was studied. The possibilities of visualizing various objects within biological tissues were examined. It is found that: (a) it is possible to see small objects with millimeter and sub-millimeter dimensions; and (b) by using NIR rays it is possible to distinguish different parts of small homogeneous biological tissues.

Wide band gap materials as a new tuning strategy for dye doped cholesteric liquid crystals laser.

A new tuning strategy for mirror-less liquid crystals laser is presented. A three layer cell is prepared with two cholesteric layers sandwiching a layer containing an isotropic mixture of a photoluminescent dye. One of the chiral layers contains a wide band gap material while the second layer consists of a series of small band gap materials.

Enhancing cholesteric liquid crystal laser stability by cell rotation.

Stability of dye doped cholesteric liquid crystal laser emission from several minutes up to two hours and more was achieved by rotating the liquid crystal cell. Significant dependence of stability on surface treatment was observed.

Trans-cis isomerization and the blue phases.

A new class of photoactive chiral liquid crystals based on a photoactive nematic host material and a photoinactive chiral dopant was utilized to investigate the behavior of the blues phases when trans-cis isomerization is induced. While the general behavior follows what has been observed in the cholesteric phase, the sensitivity of the blue phases to external parameters causes different behavior when these systems are exposed to UV radiation. The results for four different mixtures are reported and include (1) modulation of the blue phase selective reflection wavelength with low levels of UV and visible light, (2) conversion of one blue phase to another upon exposure to UV light, and (3) induction of blue phases due to UV irradiation when no blue phases are stable beforehand.

[Transplantation of neural stem cells in experimental retinopathy].

A stable and easily reproducible model of experimental retinopathy was constructed in rabbits. The influence of transplanted neural stem cells (NSC) on the functional activity of the retina was studied. Retinopathy was provoked by 0.

[Clinical aspects of injury to the eye inflicted with gas pistols for self-defense].

The clinical picture of an injury inflicted with gas pistols represents polymorphous changes and severe injury to the organ of vision, involving not only the anterior segment, but the deep structures as well. Analysis of the status of the damaged eyes and the mechanism of injury permitted us to distinguish 3 clinical groups in terms of the intensity of exposure to this or that factor: 1) chemical burn of the cornea and conjunctiva (65 patients); 2) chemical burn with elements of thermal involvement and impregnation of tissues with particles of gunpowder that failed to burn and slight or medium-severe contusion of the eyeball (31 patients): and 3) severe thermochemical burn with grave contusion of the eyeball, sometimes with rupture of membranes (6 patients). Hence, we may conclude that the consequences of using gas weapons differ from those described in the Status of Gas Weapons Application and in advertising materials by a much greater severity, and in 11.

[Specific features of war injuries of the eyes in peace time].

The authors analyze clinical features of injuries to the organ of vision under extreme conditions of a local war conflict and present their recommendations on rehabilitation of the victims. The status of 203 patients with eyeball wounds inflicted under such conditions is analyzed. To optimize the outcomes of war traumas to the eye inflicted in peace time the authors give the following recommendations based on the specific features of such injuries and the objective conditions in foci of regional conflicts: (1) Rapid evacuation of wounded subjects to the nearest ophthalmological institutions; (2) Maximally early primary ophthalmological care with obligatory primary surgical debridement of the wound; (3) No attempts at removal of a foreign body during primary surgical debridement at local medical institutions; (4) the earliest possible evacuation of the victims after wound debridement to specialized ophthalmo-traumatological institutions for further rehabilitation.