Development of poly(2-hydroxyethyl methacrylate)/clay composites as drug delivery systems of paracetamol

In this work the synthesis of hydrogel/clay nanocomposites based on poly(2-hydroxyethyl methacrylate) (HEMA) has been performed through in situ free radical polymerization in order to examine their potential use in biomedical applications as drug carriers. 2-hydroxyethyl methacrylate monomer has been intercalated into the interlayer spaces of a clay mineral using sodium montmorillonite (MMT) nanoparticles and then polymerized. The influence of different amounts of MMT on the structural properties of the resulting novel materials HEMA/MMT was investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). X ray diffraction analysis has been used to evaluate the state of dispersion of the clay particles in the hydrogel matrix. TGA, DSC and swelling results have revealed that the clay sheets acted as effective multifunctional cross-linkers. Paracetamol incorporation efficiency in the HEMA/MMT hydrogels was determined by UV–vis spectroscopy. The DSC study revealed an amorphization of paracetamol in the drug loaded hydrogel. The effect of varying the concentration of MMT within the hydrogel was investigated to obtain optimum conditions to control the drug release. The burst effect was significantly reduced and the releasing equilibrium time was extended in the nanocomposites HEMA/MMT in comparison to the HEMA hydrogel

Converse Smith-Martin cell cycle kinetics by transformed B lymphocytes

Recent studies using direct live cell imaging have reported that individual B lymphocytes have correlated transit times between their G1 and S/G2/M phases. This finding is in contradiction with the influential model of Smith and Martin that assumed the bulk of the total cell cycle time variation arises in the G1 phase of the cell cycle with little contributed by the S/G2/M phase. Here we extend these studies to examine the relation between cell cycle phase lengths in two B lymphoma cell lines. We report that transformed B lymphoma cells undergo a short G1 period that displays little correlation with the time taken for the subsequent S/G2/M phase. Consequently, the bulk of the variation noted for total division times within a population is found in the S/G2/M phases and not the G1 phase. Models that reverse the expected source of variation and assume a single deterministic time in G1 followed by a lag + exponential distribution for S/G2/M fit the data well. These models can be improved further by adopting two sequential distributions or by using the stretched lognormal model developed for primary lymphocytes. We propose that shortening of G1 transit times and uncoupling from other cell cycle phases may be a hallmark of lymphocyte transformation that could serve as an observable phenotypic marker of cancer evolution.K. Pham, A. Kan, L. Whitehead, R. J. Hennessy, K. Rogers, P. D. Hodgki

Low loss coatings for the VIRGO large mirrors

présentée par L. PinardThe goal of the VIRGO program is to build a giant Michelson type interferometer (3 kilometer long arms) to detect gravitational waves. Large optical components (350 mm in diameter), having extremely low loss at 1064 nm, are needed. Today, the Ion beam Sputtering is the only deposition technique able to produce optical components with such performances. Consequently, a large ion beam sputtering deposition system was built to coat large optics up to 700 mm in diameter. The performances of this coater are described in term of layer uniformity on large scale and optical losses (absorption and scattering characterization). The VIRGO interferometer needs six main mirrors. The first set was ready in June 2002 and its installation is in progress on the VIRGO site (Italy). The optical performances of this first set are discussed. The requirements at 1064 nm are all satisfied. Indeed, the absorption level is close to 1 ppm (part per million), the scattering is lower than 5 ppm and the R.M.S. wavefront of these optics is lower than 8 nm on 150 mm in diameter. Finally, some solutions are proposed to further improve these performances, especially the absorption level (lower than 0.1 ppm) and the mechanical quality factor Q of the mirrors (thermal noise reduction)

Informações básicas sobre o município de Moju, Pará: uma contribuição para o seu planejamento.

bitstream/item/223661/1/Informacoes-basicas-sobre-o-municipio.pdfTrabalho financiado pelo Projeto GESPAN - Gestão Participativa de Recursos Naturais

Nonlinearity measurements of thin films by third-harmonic-generation microscopy

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Nonlinear microscopy

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Nonlinear microscopy

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Nonlinearity measurements of thin films by third-harmonic-generation microscopy

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Noninstantaneous femtosecond phase shift in second order cascading process

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Nonlinear microscopy

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