No abstract

To understand the structure/property of the ionomer in the CL, adsorbed Nafion thin films were prepared on model substrate, SiO2 terminated silicon wafer, by spontaneous adsorption of Nafion from its 0.1 to 5 wt% solution. Fitting of Variable Angle Spectroscopic Ellipsometry (VASE) data yielded thickness of adsorbed films ranging from 4 nm at low concentrations (0.1 wt% film) to 306 nm at high concentrations (5wt% film). Contact angle measurements indicated that the low (0.1 wt%) and high (3 wt%) films to posses hydrophobic surface but the intermediate concentration (0.5 wt% and 1.0 wt%) film surface to be hydrophilic. Conductivity measurements of adsorbed films over a range of RH showed that all films prepared from 1 wt% and lower concentrations solutions to possess similar conductivities at high RH. However, the 5wt% film showed much higher conductivity indicating a different proton conduction mechanism for low and high concentration films.

It has previously been shown that the easily handled, heat- and air-stable compound Pd(η3-1-PhC3H4)(η5-C5H5) (Vb) reacts rapidly with a wide variety of tertiary phosphines L to produce near-quantitative yields of the corresponding Pd(0) compounds PdL2, which are widely believed to be the active species in many often-used cross-coupling catalyst systems based on Pd(PPh3)4 (I), Pd2(dba)3 (II), PdCl2 (III), and Pd(OAc)2 (IV). However, catalyst precursors I–IV are in fact known to preferentially generate sterically hindered, three-coordinate Pd(0) species rather than two-coordinate PdL2, and thus Vb is hypothetically expected to be a better catalyst precursor for e.g. Suzuki–Miyaura cross-coupling reactions. Utilizing the conventional Suzuki–Miyaura cross-coupling reaction of phenylboronic acid with bromoanisole, comparisons are made of the efficacies of catalyst systems based on Vb with those based on compounds I–IV (L = the representative phosphines PPh3, PCy3, PBu t 3). As anticipated, catalysts generated from Vb are significantly more competent and, as a bonus, Vb makes palladium(0) complexes PdL2 available under rigorously anhydrous conditions.

The shock properties of epoxy-based particulate composites have been extensively studied in the literature. Generally, these materials only have a single particulate phase; typically alumina. This paper presents equation of state experiments conducted on five epoxy-based particulate composites. The shock stress and shock velocity states were measured for five different composites: two epoxy-aluminum two-phase composites, with various amounts of aluminum, and three epoxy-aluminum-(metal) composites, where the metal constituent was either copper, nickel, or tungsten. The impact velocities ranged from 300 to 960 m/s. Numerical simulations of the experiments of epoxy-Al are compared with mesoscale simulations of epoxy-Al2O3 composites to investigate the effect of the soft versus hard particulate; additionally, an epoxy-Al–W simulation was conducted to investigate the material properties of the second phase on shock response of these materials. In these epoxy-based particulate composites, the slope of the shock velocity-particle velocity curve appears to depend on the epoxy binder. It is shown that the addition of only 10 vol % of a second, denser metallic phase significantly affects the shock response in these composites.

A bronchosubcutaneous fistula is a communication between the subcutaneous tissues, the pleural cavity, and the bronchial system. It is a rare manifestation of primary pulmonary disease. The authors present a very unusual case of bronchosubcutaneous fistula that presented as subcutaneous emphysema after palliative radiation therapy for primary carcinoma of the lung.