ABSTRACT
Nanoscale surface modification of Ti6Al4V prosthetic material was investigated at 37 degrees C into a physiological liquid named Ringer's solution. The root-mean-square surface roughness evolution of the material as a function of immersion time was evaluated by atomic force microscopy (AFM) and 3D reconstruction of scanning electron microscope images (SEM). The results obtained from both techniques clearly showed a decrease of the root-mean-square surface roughness during the first 6 hours of immersion in the physiological liquid that is followed by a stability of the roughness value at longer durations. Moreover, the study of the roughness parameters extracted from AFM measurements is used to explain the smoothing process occurring at the interface between the prosthetic material and the physiological liquid.
Subject(s)
Biocompatible Materials/chemistry , Isotonic Solutions/chemistry , Nanostructures/chemistry , Nanostructures/ultrastructure , Prostheses and Implants , Titanium/chemistry , Alloys , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Particle Size , Ringer's Solution , Surface PropertiesABSTRACT
Theoretical simulations of UV-vis spectra for organic chromophores: 3-(4-fluorophenyl)-1,4-diphenyl-, 1-(4-fluorophenyl)-3,4-diphenyl- and 4-(4-fluorophenyl)-1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline. Density Functional Theory 6-31G calculations were performed. The molecular geometry and UV-vis spectra were simulated with the time-dependent DFT calculations. Influence of number of occupied and excited states on the behavior of the spectra is explored. To further improve the calculations a Polarizable Continuum Model (PCM) was employed to simulate the influence of solvent polarity. It was used in both geometry optimization and spectra simulation. An attempt to find a correlation between the values of dipole moments and the spectral shifts was performed. The results were compared with experiment.
Subject(s)
Pyrazoles/chemistry , Quinolines/chemistry , Solvents/chemistry , Computer Simulation , Models, Chemical , Spectrometry, Fluorescence , Spectrophotometry, UltravioletABSTRACT
We present here results of experimental studies and quantum-chemical simulations of optical absorption and optical poling effects performed on a new synthesized cyan, ethylcarboxyl and tert-buthyl derivatives of 1H-pyrazolo[3,4-b]quinoline incorporated into polymer matrix or dissolved in organic solutions. The efficiency of second-order optical susceptibility d vs photoinduced power density I(p) clearly saturates to certain magnitude d(eff) at sufficient power densities (I(p) > or = 1.3 GW cm(-2)). Comparing experimental data and results of semiempirical quantum-chemical simulations one can conclude that there exists generally a good correlation between the magnitude of saturated susceptibilities d(eff) and macroscopic hyperpolarizabilities for all compounds except the chromophore 1,3-dimethyl-6-cyano-[PQ] only. The discrepancy for this compound may reflect a specific contribution of surrounding polymer matrix. According to the quantum chemical analysis the methyl-containing cyan and ethylocarcoxyl derivatives reveal four/five strong absorption bands in the spectral range 200-500 nm. A substitution of the methyl groups by the phenyl group causes the substantial changes of the absorption spectra mainly in the spectral range 240-370 nm. Measured and calculated absorption spectra manifest rather good agreement mainly in the part regarding the spectral positions of the first oscillator (absorption threshold). The quantum-chemical PM3 method shows the best agreement with experiment. At the same time a considerable broadening almost of all absorption bands appears as a characteristic feature of all measured spectra. The discrepancies between the calculated and the measured spectra are attributed to electron-vibronic coupling as well as to a specific rotational dynamics of phenyl rings.
