Eye tissue structure and refraction alterations upon nondestructive laser action

A new approach to alterations in eye refraction upon nondestructive laser action on the sclera and cornea is studied. It is demonstrated in in vivo experiments on rabbit eyes that sequential laser irradiation of the sclera and cornea yields a significant alteration in the eye refraction. The collagen structure of the sclera and cornea is studied after the nondestructive laser action with noninvasive polarization-sensitive optical coherence tomography. It is demonstrated that collagen fibers that provide for the cornea tension and applanation partially survive in the zone of the local denaturation of sclera. An irradiation mode that corresponds to an increase in the cornea’s plasticity and does not cause visible structural changes is chosen. The simplest theoretical model for alterations in the eye refraction upon the nonablative laser action on sclera is analyzed. The alteration in the cornea curvature upon stretching resulting from the local sclera coagulation and the corresponding decrease in its volume is calculated. The model makes it possible to approximately estimate the laser irradiation modes that provide the desired alterations in eye refraction.     

Luminescent thermo- and photocurable silicones doped with a europium complex

Two europium ??-diketonates containing tris(trimethylsiloxysilylpropylamide) group in the ligand molecule were obtained by the reaction of the corresponding triethoxysilyl derivatives with trimethylsilanol. The siloxane groups provide solubility of the complexes in liquid silicone compositions, which is sufficient for obtaining luminescent flexible polysiloxane films doped with the europium complex.     

IR laser and heat-induced changes in annulus fibrosus collagen structure

The purpose of this study was to characterize essential changes in the structure of annulus fibrosus (AF) after hydrothermal and infrared (IR) laser treatment and to correlate these results with alterations in tissue state. Polarization-sensitive optical coherence tomography imaging was used to measure collagen birefringence in AF. Differential scanning calorimetry was used as a complementary technique, providing detailed information on thermodynamic processes in the tissue. Birefringence, peak of the denaturation endotherm, and the enthalpy of denaturation (DeltaHm) were determined before and after hydrothermal heat treatment (85 degrees C for 15 min) and non-ablative Er:glass fiber laser exposures on AF in the whole disk (vertebrae-disk-vertebrae complex). Our data have demonstrated quantitative differences between results of laser and hydrothermal heating. Birefringence did not disappear and DeltaHm did not change after treatment in the water bath, but loss of birefringence and a decrease in the enthalpy did occur after laser exposure. These results could be explained by the photomechanical effect of laser irradiation. We suggest that thermo-mechanical stress played a dominant role in the disruption of the collagen network of AF under non-homogeneous laser heating.     

Synthesis and some reactions of silicon phthalocyanine anions

The reactions of PcSi(OH)₂ or Me₃Si(OSiPc)_1–3 OSiMe₃ with Na or K afford anions of silicon mono-, di-, and triphthalocyanines (Pc_1–3) characterized by electronic absorption and EPR spectra. The reactions of the Pc_1–3 anions with proton donors (H₂O and CH₃COOH), Me₃SiCl, and O₂ are carried out. The Pc_1–3 anions in THF are reduced to the Pc ₁ ^3? monophthalocyanine trianion with the partial rearrangement of the phthalocyanine into corrole. In benzene the reactions of Pc_1–3 with Na or K occur only with an additive of crown ether (15C5): Na reduces Pc₁ to the Pc ₁ ^2? dianion, Pc₂ and Pc₃ do not react with Na, and potassium reduces Pc_1–3 to the P trianion.     

New Approaches in Broadband Fiber-Optical Interferometry for Optical Coherent Tomography

We have developed new methods of IR ultrabroadband interferometry for increasing the limiting capabilities of optical coherent tomography (OCT). In particular, this permitted us to create an optical coherent microscope combining the principles of confocal microscopy and OCT. To increase the longitudinal resolution, we synthesized an ultrabroadband optical spectrum based on two superluminescent diodes with separated radiation spectra. The resulting longitudinal resolution was 3.4 m and the transverse resolution was 3.9 m. Images of the inner structure of biological tissues are obtained at the cellular level. Experimental results of a study of biological tissue by the cross-polarization OCT are described.     

The structural transformations of silicon phthalocyanine in reaction with magnesium and trimethylchlorosilane

The reaction of PcSi(OSiMe₃)₂ with Mg in the presence of Me₃SiCl at 20–100°C was shown to cause the phthalocyamine macrocycle contraction and give the silicon α,β,γ-triazatetrabenzocorrole macrocycle. The reaction proceeds in the polar donor solvents (THF, pyridine), but does not occur in aromatic hydrocarbons. The electronic and EPR spectra indicate that the silicon phthalocyanine mono- and dianions are active intermediate reaction products.     

Some donor-acceptor complexes of silicon phthalocyanine dianions

Studying the reaction of PcSiX₂ (X = Cl, OH) with KOH in DMSO we first discovered red D-A complexes [(Pc²⁻)·PcSiX²] and [(Pc²⁻)·O²] in which silicon phthalocyanine dianion Pc²⁻ is a donor, and the parent phthalocyanine silicon or oxygen are acceptors of electron density. The complexes were characterized by electron absorption, NMR, and ESR spectra. In the reactions with Me₃SiCl, H₂O, or CH₃COOH the complexes regenerate phthalocyanine and O₂. In O₂ atmosphere the [(Pc²⁻)·O₂] complex gradually degrades affording a product of unknown nature.     

Preparation and some properties of ionic salts of C 60 − and C 60 2− fullerides with phthalocyanine cations

Ionic fullerides of C ₆₀ ^? and C ₆₀ ^2? with the silicon phthalocyanines cations were obtained in the reaction of PcSi(OH)₂ with fullerene C₆₀ in the presence of KOH in DMSO or in xylene and THF with the addition of 15C5 crown ether. The fullerides were characterized by electron absorption, ¹H NMR and electron spin resonance spectra, and their reaction with O₂ and CF₃COOH were carried out.