Effect of diclofenac on ocular levels of ciprofloxacin and lomefloxacin in rabbits with endophthalmitis

The purpose of this study was to analyze ciprofloxacin and lomefloxacin penetration into the anterior eye tissues after topical instillation in healthy rabbits and with experimental Staphylococcus aureus endophthalmitis. Additionally, effect of diclofenac sodium eye drops on the distribution of both fluoroquinolones in the inflamed eye tissues was investigated. An intense protocol with frequent antibiotic administration was chosen. Samples from aqueous humor were obtained 2 and 6?h after the start of the treatment. Samples from cornea and iris were obtained at the end of the experiment, after euthanasia of the animals. Drug concentrations were measured by HPLC method. The median levels of ciprofloxacin and lomefloxacin in aqueous humor of healthy animals, 2 and 6?h after drug administration were 6.39–9.65 and 5.30–6.81?µg/ml, respectively. Ciprofloxacin levels were neither changed from the inflammation nor after instillation of diclofenac. In contrary, lomefloxacin concentrations in aqueous humour of inflamed eye were significantly increased 12.15–15.08?µg/ml, especially after diclofenac administration (17.12–27.76?µg/ml). Levels of both fluoroquinolones in cornea (13.08?µg/g for ciprofloxacin and 12.25?µg/g for lomefloxacin) and in iris (0.84?µg/g for ciprofloxacin and 1.34?µg/g for lomefloxacin) were higher than MIC and MBC values against S. aureus ATCC 25923. Although higher lomefloxacin concentrations were observed in the aqueous humor after instillation of diclofenac, the levels of both fluoroquinolones in iris and in cornea were not significantly changed. Topical administration of lomefloxacin and diclofenac in combination improved penetration of the antibacterial agent in the aqueous humor which can be of clinical importance.     

Preparation and characterization of hollow α-Fe2O3 irregular microspheres

Hollow α-Fe₂O₃ irregular microspheres were prepared at 160 °C from a hydrolyzing Fe(ClO₄)₃ solution by adding sodium polyanethol sulphonate. The particles were characterized by ⁵⁷Fe Mössbauer, X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. The walls of these hollow particles consisted of elongated subunits composed of elongated and thin α-Fe₂O₃ rods. The precipitation of hollow α-Fe₂O₃ irregular microspheres was governed by the preferential adsorption of sulphonate/sulphate groups. The lateral aggregation of elongated thin rods and subunits also played an important role in the formation of hollow α-Fe₂O₃ irregular microspheres.     

The effect of temperature on the crystallization of α-Fe2O3 particles from dense β-FeOOH suspensions

The effect of temperature on the crystallization of α-Fe₂O₃ particles from dense β-FeOOH suspensions was monitored by ⁵⁷Fe Mössbauer spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy dispersive spectroscopy. Dense suspensions of very long laterally arranged β-FeOOH fibrils were obtained at 90 °C. Crystallization at 120 °C between 18 and 72 h yielded monodisperse α-Fe₂O₃ particles of a shape close to that of double spheres with ring. The double spheres with ring showed two narrow particle size distributions. In these particles a substructure was detected, i.e., the spheres consisted of the linear chains of interconnected α-Fe₂O₃ subparticles. With further rise in the crystallization temperature the increase in α-Fe₂O₃ particles and porosity became pronounced. Obviously, the aggregation mechanism played an important role in the formation of α-Fe₂O₃ particles.     

Growth of uniform lath-like α-(Fe,Al)OOH and disc-like α-(Fe,Al)2O3 nanoparticles in a highly alkaline medium

The effects of aluminium (Al³⁺)-dopant on the precipitation of uniform lath-like α-FeOOH particles, the obtention and growth of α-(Fe,Al)OOH and α-(Fe,Al)₂O₃ solid solutions, particle size and shape were investigated using X-ray powder diffraction, Mössbauer and Fourier transform infrared spectroscopies, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Acicular α-FeOOH particles, precipitated in a highly alkaline medium with the addition of tetramethylammonium hydroxide (TMAH), were used as reference material. The influence of Al-dopant was investigated by adding varying amounts of Al³⁺ ions to the initial FeCl₃ solution. In the presence of lower concentrations of aluminium ions (up to 11.11 mol%) α-(Fe,Al)OOH as a single phase was formed, whereas higher concentrations led to an additional obtention and growth of α-(Fe,Al)₂O₃. Al-for-Fe substitution in the α-FeOOH and α-Fe₂O₃ structures was confirmed by a decrease in the unit-cell dimensions, a decrease in the hyperfine magnetic field and an increase in the wave number of the infrared absorption bands. The presence of lower concentrations of aluminium ions (up to 11.11 mol%) in the precipitation system did not affect the size and shape of the α-(Fe,Al)OOH particles, whereas higher concentrations influenced a decrease in the length and aspect ratio. In the presence of 42.86 mol% Al³⁺ ions fairly uniform disc-shaped α-(Fe,Al)₂O₃ were formed.     

Thermal behavior of the amorphous precursors of the ZrO2-SnO2 system

Thermal behavior of the amorphous precursors of the ZrO₂-SnO₂ system on the ZrO₂-rich side of the concentration range, prepared by co-precipitation from aqueous solutions of the corresponding salts, was monitored using differential thermal analysis, X-ray powder diffraction, Raman spectroscopy, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectrometry (EDS). The crystallization temperature of the amorphous precursors increased with an increase in the SnO₂ content, from 405 °C (0 mol% SnO₂) to 500 °C (40 mol% SnO₂). Maximum solubility of Sn⁴⁺ ions in the ZrO₂ lattice (∼25 mol%) occurred in the metastable products obtained upon crystallization of the amorphous precursors. A precise determination of unit-cell parameters, using both Rietveld and Le Bail refinements of the powder diffraction patterns, shows that the incorporation of Sn⁴⁺ ions causes an asymmetric distortion of the monoclinic ZrO₂ lattice. The results of phase analysis indicate that the incorporation of Sn⁴⁺ ions has no influence on the stabilization of cubic ZrO₂ and negligible influence on the stabilization of tetragonal ZrO₂. Partial stabilization of tetragonal ZrO₂ in products having a tin content above its solid-solubility limit was attributed to the influence of ZrO₂-SnO₂ surface interactions. In addition to phases closely structurally related to cassiterite, monoclinic ZrO₂ and tetragonal ZrO₂, a small amount of metastable ZrSnO₄ phase appeared in the crystallization products of samples with 40 and 50 mol% of SnO₂ calcined at 1000 °C. Further temperature treatments caused a decrease in and disappearance of metastable phases. The results of the micro-structural analysis show that the sinterability of the crystallization products significantly decreases with an increase in the SnO₂ content.     

Molecular Mechanics Study of Nickel(II) Octaethylporphyrin Adsorbed on Graphite(0001)

The effects of adsorption on the graphite(0001) surface on the nonplanar distortions of nickel(II)octaethylporphyrin were studied by molecular mechanics (MM) approach. Using the Consistent Force Field (CFF) program with previously developed parameters for metalloporphyrins and supplemented to treat intermolecular interactions geometry optimizations were carried out for 43 conformations of 28 distinct conformers of nickel(II)octaethylporphyrin. The stable energy-minimized conformers were stereochemically characterized, analyzed by the Normal-coordinate Structural Decomposition (NSD) method and compared with the available theoretical and experimental data for the isolated nickel(II)octaethylporphyrin structures.     

Spectroscopic characterization of alkali borosilicate glasses containing iron ions

Structural properties of alkali borosilicate glasses containing iron ions were investigated using infrared, laser Raman and Mössbauer spectroscopy. Two types of glasses were prepared: SRL-type with the composition 18.5 wt% Na₂O, 10.0 wt% B₂O₃, 52.5 wt% SiO₂, 4.0 wt% Li₂O, 10 wt% TiO₂ and 5.0 wt% CaO, and sodium borosilicate glass with the composition 16.7 wt% Na₂O, 18.7 wt% B₂O₃ and 64.6 wt% SiO₂. Raman spectroscopy showed that orthosilicates are the dominant amorphous phase in the SRL-type of glass. Incorporation of iron in the SRL-type of glass induced polymerization of silicate units and -Si-O-Fe- copolymerization. It was concluded that different amorphous phases are simultaneously present in the SRL-type of glass containing iron ions. Interpretation of the Raman spectra is given. Incorporation of iron ions into the sodium borosilicate glass also affected the corresponding IR spectra. The valence state of iron and its coordination were determined by⁵⁷Fe Mössbauer spectroscopy.     

Microstructural changes in particles detected during the transformation from β-FeOOH to α-Fe2O3 in dense aqueous suspensions

The hydrothermal transformation from β-FeOOH to α-Fe₂O₃ in dense aqueous suspensions, obtained by partial neutralization of concentrated FeCl₃ solution with concentrated NaOH solution, was investigated. Mössbauer spectroscopy was used for the phase analysis of samples, as well as the complementary techniques XRD and FT-IR. The size and morphology of the particles were inspected with FE-SEM. At the beginning of the crystallization process very fine β-FeOOH particles were formed, which transformed to α-Fe₂O₃ (end-product) with a prolonged time of heating. A small amount or traces of α-FeOOH as an intermediate phase were detected by FT-IR and FE-SEM. Gradual formation of α-Fe₂O₃ double spheres with ring was monitored. Double spheres with ring were formed by the aggregation mechanism. The orientation effect of α-Fe₂O₃ subunits in double spheres with ring was observed. α-Fe₂O₃ double spheres with ring also showed two narrow particle size distributions.     

Optimization of the Two- and Three-Dimensional Characterization of Rare Earth-Traced Deoxidation Products

Tracing by means of the light rare earths (REs), particularly La and Ce, is a state-of-the-art method used to track deoxidation products during the steelmaking process. Traced heterogeneous multiphase inclusions are analyzed using scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS) to perform a 2D characterization. The sequential chemical extraction technique is implemented for a 3D investigation to determine traced particles’ actual sizes and shapes. The automated SEM/EDS measurement must be optimized since RE oxides appear brighter in the backscattered electron images due to their high atomic numbers. Therefore, two grayscales are implemented for the detection of RE-containing multiphase inclusions. Within this technique, individual RE-traced heterogeneous nonmetallic inclusions (NMIs) are counted as separate particles. Thus, the measured NMIs must be recombined, which is achieved using a self-developed MATLAB tool. The extracted particles are also analyzed by automated and manual SEM/EDS measurements to determine the 3D morphologies and sizes of traced NMIs.