Reconstruction of the constricted orbital cavity in patients with artificial anophthalmy

In cases, in which not only the globe of the eye, but the whole conjunctival sack is missing and the eyelids are due to scarring attached either to the orbital tissues and/or to each other, it is not possible to insert a prosthesis. This is a major aesthetic defect. The cavity that allows artificial eye insertion can be formed by surgery. One of the best methods is the orbital cavity reconstruction developed and suggested by the Hungarian István Csapody. He constructed two instruments to perform the operation: a butterfly shaped marker to prepare skin graft with proper size and shape, and an adjustable cone formed spacer to keep the reconstructed socket open during the healing process. We use free autologous split skin graft to line the cavity. If the shapes of the eyelids are intact, and the color of the prosthesis matches the fellow eye and it fits perfectly, then the postoperative cosmetic result can be excellent.     

Silicon compounds as additives improving coating performance: fixation of silicon compounds with cellulose

In this study the reactivity of cellulose with new solvent born preparations containing organosilanes, alkyd resin and natural oil was analysed. Structural analysis of cellulose after reaction with organosilanes and after extraction was performed using Fourier-transform infrared spectroscopy (FTIR). In IR spectra the analyzed bands included 1250 cm^?1 responsible for vibrations of the SiC group and 800 cm^?1 responsible for vibrations of SiC and/or SiO groups. These bands are characteristic of silicon bonds with atoms of carbon and oxygen originating from the methoxy groups found in organosilanes. The presence of these bands in the spectra proves the occurrence of a reaction between cellulose and organosilanes. The concentration of silicon was determined by AAS in cellulose after reaction with preparations and after extraction.     

Modeling of optical constants of diamond-like carbon

A new model of optical constants of diamond-like carbon parameterizing joint density of states (PJDOS) is introduced and compared with a previously published model based on the parameterization of density of states (PDOS). Both the models employ only six parameters: three parameters for π → π^⁎ and three parameters for the σ → σ^⁎ transitions. These parameters have a clear physical meaning. One describes the minimum energy needed for the band transition, i.e. band gap, the second is the maximum energy of transitions and the third is proportional to the total density of the corresponding electronic states. An inherent disadvantage of the PDOS model is in the necessity of a numerical calculation. On the other hand the PJDOS model is analytical and, therefore, it can be implemented in a simple manner. The efficiency of both the models for the study of DLC structure is demonstrated in several examples.     

Conducting polyaniline–montmorillonite composites

Polyaniline (PANI)–montmorillonite (MMT) composites were prepared in two ways: (a) by the polymerization of aniline hydrochloride with ammonium peroxydisulfate (APS) in aqueous suspensions of MMT, (b) by the intercalation of aniline hydrochloride into MMT in aqueous suspension followed by the oxidation with APS, i.e. by the surface and intercalative polymerizations of aniline. The products were analyzed by SEM, XRD, TGA, FTIR and Raman spectroscopies. The formation of red coloration after interaction of MMT with aniline is discussed. The conductivity of PANI–MMT composites increased to units S cm^?1 as the content of PANI reached 50–60 wt.%. The intercalation of aniline into MMT before the polymerization had no marked effect on the conductivity of resulting composites, which was determined mainly by the PANI present at the MMT particles surfaces.     

Polyaniline–silver composites prepared by the oxidation of aniline with silver nitrate in acetic acid solutions

The reaction between two non‐conducting chemicals, aniline and silver nitrate, yields a composite of two conducting components, polyaniline and metallic silver. Such conducting polymer composites combine the electrical properties of metals and the materials properties of polymers. In the present study, aniline was oxidized with silver nitrate in solutions of acetic acid; in this context, aniline oligomers are often a major component of the oxidation products. An insoluble precipitate of silver acetate is also present in the samples. The optimization of reaction conditions with respect to aniline and acetic acid concentrations leads to a conductivity of the composite as high as 8000 S cm^?1 at ca 70 wt% (ca 21 vol%) of silver. A sufficient concentration of acetic acid, as well as a time extending to several weeks, has to be provided for the successful polymerization of aniline. Polyaniline is present as nanotubes or nanobrushes composed of thin nanowires. The average size of the silver nanoparticles is 30–50 nm; silver nanowires are also observed. Copyright © 2009 Society of Chemical Industry     

Band structure of diamond-like carbon films assessed from optical measurements in wide spectral range

The optical measurements of thin films on substrates, such as ellipsometry and spectrophotometry, can be efficiently used for obtaining information about film material structure if their dielectric function is parametrized by a proper dispersion model. The sample of hydrogenated diamond-like carbon (DLC) film, prepared by plasma enhanced chemical vapor deposition on silicon single crystal substrate, was investigated by ellipsometry in the NIR–UV range (0.6–6.5 eV), synchrotron ellipsometry in the UV–XUV range (4–20 eV) and reflectometry in NIR–UV range (1.24–6.5 eV). Various dispersion models based on the parametrization of density of states (PDOS) were investigated concerning their application in the wide spectral range. The previously used simple PDOS model was found to be insufficient. It resulted in poor separation of π and σ bands in the short spectral range while in the wide range it could not reflect the film optical properties because transitions to higher excited states were neglected. The inclusion of these transitions led to a considerable improvement of the fit above 16 eV. However, the realistic value of the band gap of σ electrons was obtained only after refinement of the previously expected parabolic shape of the DOS of π and σ electrons. The further developed PDOS model can be used for any other disordered material and it will, together with the optical measurements extended to XUV, supply important information about its band structure.     

Study of the pO2-sensitivity of the dendrimeric and free forms of Pd-meso-tetra(4-carboxyphenyl)porphyrin, incorporated or not in chitosan-based nanoparticles

The concentration of oxygen and its rate of consumption are important factors in certain medical treatments, such as radiotherapy and photodynamic therapy (PDT). Measuring the tissue concentration of oxygen or its partial pressure (pO2) can be achieved by taking advantage of the oxygen-dependent luminescence lifetime of certain molecules, including metallo-porphyrin derivatives, due to the oxygen-dependent quenching of their triplet state. Unfortunately, most of these porphyrin derivatives are phototoxic due to the O(2)1delta produced in the pO2 measurement procedure. The aim of this work was to characterize new nanoparticle oxygen sensors, where the palladium-porhyrin molecule (Pd-meso-tetra(4-carboxyphenyl)porphyrin) or its dendrimer form, is incorporated into an oxygen permeable matrix of chitosan-based colloidal particles. It was hypothesized that the reactive O(2)1delta produced during the pO2 measurement would react inside the particle thus reducing its toxicity for the surrounding tissue, whereas the 3sigma ground state of O2, that is to be measured, would diffuse freely in the peptide. We observed that the incorporation of the porphyrin in the nanoparticles resulted in a reduction of the phosphorescence lifetime sensitivity to pO2 by about one order of magnitude. Our studies of these new sensors indicate that the oxygen concentration can be measured in aqueous solutions with a precision of +/- 20% for oxygen concentrations ranging between 0% and 25%.