Dispersion of silica nano-particles in sol-gel hybrid resins for fabrication of multi-scale hybrid nanocomposite

Multi-scale hybrid nanocomposites containing both ∼15 nm silica colloids and ∼2 nm oligosiloxanes in a methacryl polymer matrix were newly designed and fabricated. Colloidal silica sols were dispersed in methacryl oligosiloxanes nano-hybrid resins synthesized by sol-gel reaction of methacryloxypropylmethoxysilane and diphenylsilanediol. On the basis of TEM and SANS analyses, it was confirmed that the silica colloids were compatibly dispersed and different sizes of colloidal silica and oligosiloxanes co-exist in the solutions. Multi-scale hybrid nanocomposites fabricated by UV and thermal curing with incorporation of silica colloids in the nano-hybrid materials show enhanced mechanical and thermal characteristics.     

Design of molecular two-photon probes for in vivo imaging. 2H-Benzo[h]chromene-2-one derivatives

2H-Benzo[h]chromene-2-one derivatives showing appreciable water solubility, significant two-photon cross sections, high photostability, cell permeability, low toxicity, and ability to be converted to a protein TP probe have been developed by incorporating all of the needed functions within a small molecule.     

A new approach to the design of surface treatments for reinforcing agents

A new approach for design of improved interfacial bonding between carbon fibers and polymeric matrices is described. In this method the affinity of surface-treated carbon fibers to various polymer matrices is simulated by analyzing the adsorption characteristics of model compounds, typical of the polymer units, onto very high surface area carbon fibers. The affinity can be evaluated by the use of Thermogravimetric Analysis (TGA) to measure adsorption–desorption characteristics. Since high surface area, activated carbon fibers (ACF) can be chemically treated to obtain acidic, basic, nonpolar or highly polar surfaces, it should be possible to assess the interactions of chemically modified surfaces with model compounds such as methanol (MeOH), acetone, dimethylformamide (DMF), dimethylether, tetrahydrofuran (THF) and water. Some preliminary results are presented, indicating that surface treatments for carbon fibers other than oxidation may lead to enhanced bonding with polymeric matrices.     

The characteristics of integrins expression in decidualized human endometrial stromal cell induced by 8-Br-cAMP in in vitro

Integrins are heterodimeric glycoproteins that have been found to undergo dynamic temporal and spatial changes in the endometrium during the menstrual cycle and in early pregnancy. Specificity of integrins is known to be different in human endometrial stromal cells and decidual cells. These shifts of integrins suggested to play an important role in embryo implantation and can be modulated by progesterone, cAMP derivatives, and cytokines. The mechanisms of decidualization and its precise physiological role are still not clearly understood and in vitro systems could provide an alternative that overcomes limitations of studying such complex biological phenomena in vivo at the time of implantation. This study was undertaken to establish an in vitro model system for human decidualization using 8-bromo-cAMP and to investigate the characteristics of stromal integrin expression in vitro by 8-Br-cAMP. Endometrial stromal cells were isolated and cultured, and then were induced to decidualize by 0.5 mM 8-Br-cAMP for 15 days. Immunofluorescence staining and flow cytometric analyses of the integrin subunits (alpha1, alpha4, alpha5, alpha6, beta1 and alphavbeta3) were performed at day 9. In the presence of 8-Br-cAMP, the staining intensity of alphavbeta3 was significantly higher than control and measurements for alpha1, alpha4, alpha5, alpha6, and beta1 were similar. Immunofluorescent localization of the integrins reflected the differences obtained from the flow cytometric analyses described above. In summary, the expression of alphavbeta3 integrin increased in stromal cells in vitro decidualized by 8-Br-cAMP and this up-regulation of alphavbeta3 integrin expression during decidualization might influence on human implantation.     

Spectrophotometric determination of dissociation constants for propionic acid and 2,5-dinitrophenol at elevated temperatures

Using the temperature dependence of pK_a for acetic acid, the pK_a for 2,5-dinitrophenol have been spectrophotometrically determined in acetate buffer at elevated temperatures under the saturation vapor pressures. For 2,5-dinitrophenol $$pK_a = - 33.206 + 2106.7/T + 5.495\ln T$$ where T is in Kelvin. Similarly, pK_a values of propionic acid were obtained at temperatures from 25°C to 175°C producing $$pK_a = - 43.703 + 2128.6/T + 7.2686\ln T$$ From this result, several thermodynamic functions of propionic acid were calculated and compared with those obtained from emf measurement.     

A remark on nilpotent Lie Algebras

Letf(n) denoted the number of essential parameters which are needed to classifyn-dimensional nilpotent Lie Algebras over the complex number field. Then $f(2n) \geqslant \tfrac{{n(n2 - 7)}}{6} - 2$ .