Surface‐initiated ring‐opening polymerization of p‐dioxanone on Wang resin bead

Biodegradable poly(p‐dioxanone) (PPDO) was formed on Wang resin surface by surface‐initiated ring‐opening polymerization (SI‐ROP). The SI‐ROP of p‐dioxanone (PDO) was achieved by heating a mixture of Tin(II) bis(2‐ethylhexanoate) [Sn(Oct)₂], hydroxyl functionalized Wang resin, and PDO in anhydrous toluene at 80 °C. The resultant polymer‐grafted Wang resin (Wang‐g‐PPDO) was characterized by fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), optical microscopy (OM), and field‐emission scanning electron microscopy (FE‐SEM). The FTIR spectra of Wang‐g‐PPDO show peak characteristic of PPDO at 2943 cm^?1 (? C? H stretch), at 1741 cm^?1 (? C?O stretch), and 1136 cm^?1 (C? O? C stretch) indicating the formation of ester linkage between PPDO and hydroxyl terminated Wang resin. The DSC thermogram show melting peak corresponding to PPDO polymer on Wang resin surface. Thermogravimetric investigation shows increase in PPDO content on the Wang resin surface in terms of percentage of weight loss with increase in reaction time. The OM and SEM photographs clearly show the formation of PPDO polymer on the Wang resin surface without altering the spherical nature of Wang resin bead. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1178–1184, 2008     

Optimization of the liquid scintillation counting technique for the European interlaboratory comparison on gross α/β activity concentrations in water

A liquid scintillation counting (LSC) measurement method optimization for the gross α/β activity analysis in drinking waters with different chemical and radionuclide composition was performed. The optimized method was suitable to provide gross radioactivity results in drinking waters with the levels of the accuracy and precision similar to those obtained using other radioactivity screening techniques. Robust LSC results contributed to the calculation of gross α/β activity reference values of EC-JRC interlaboratory comparison water samples in 2012. Some of the most common errors in the determination of the gross radioactivity using the LSC are presented.

     

Two new phenolic amides from the seeds of Pharbitis nil

Two new phenolic amides, pharnilatins A (1) and B (2), were isolated from the seeds of Pharbitis nil. These new compounds possess a p-coumaroyl unit with a structurally unique side chain, (2S,3S)-2,3-dihydroxyputrescine. The chemical structures and absolute stereochemistries of the new compounds were determined on the basis of spectroscopic analyses including 1D- and 2D-NMR experiments and chemical reactions. Compounds 1 and 2 exhibited cytotoxicity against A549, SK-OV-3, SK-MEL-2, and HCT-15 human tumor cells. However, none of the compounds inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-activated microglia cells.     

Theoretical and experimental study of the nanoparticle-driven blue phase stabilisation

We have studied theoretically and experimentally the effects of various types of nanoparticles (NPs) on the temperature stability range [Formula: see text] T (BP) of liquid-crystalline (LC) blue phases. Using a mesoscopic Landau-de Gennes type approach we obtain that the defect core replacement (DCR) mechanism yields in the diluted regime [Formula: see text] T (BP)(x) [Formula: see text] 1/(1 - xb) , where x stands for the concentration of NPs and b is a constant. Our calculations suggest that the DCR mechanism is efficient if a local NP environment resembles the core structure of disclinations, which represent the characteristic property of BP structures. These predictions are in line with high-resolution ac calorimetry and optical polarising microscopy experiments using the CE8 LC and CdSe or aerosil NPs. In mixtures with CdSe NPs of 3.5nm diameter and hydrophobic coating the BPIII stability range has been extended up to 20K. On the contrary, the effect of aerosil silica nanoparticles of 7.0nm diameter and hydrophilic coating is very weak.     

Remarks on Quasilinear Hyperbolic Equations with Dynamic Boundary Conditions

In this paper the non-existence of global solutions of two fourth-order hyperbolic equations with dynamic boundary conditions is considered. Here we prove stronger results than that of M. Kirane, S. Kouachi and N. Tatar by a different method.     

Thermodynamic analysis and experimental study on the reduction of mixed oxides including uranium oxide by lithium

In order to determine the operating conditions of an uranium reduction process with U₃O₈-Li-LiCl system, the operating conditions have been evaluated in thermodynamic aspects and the results were experimentally confirmed in this study. All the reduction experiments were conducted in an argon atmospheric glove box, and the resultant degree of reduction was determined by analyzing the product using XRD and TGA. In the results of this study, a reduction yield greater than 95% is achieved within about 3 hours of reaction. The effects of the added quantity of Li and LiCl to the reduction yield of U₃O₈ and the preferential removal of several metal oxides accompanying U₃O₈ in the course of reduction were discussed. For a greater reduction of U₃O₈, an additional 20% of Li is required when compared to the stoichiometric composition. The proper composition of LiCl is about 75% based on the weight of U₃O₈ charged.