The values for the equilibrium constants (K2, K3) were estimated from the relevant Eo values. The simulated voltam-

No abstract

o-Xylylene bis(diisobuty1-and methyloctadecyl-dithiocarbamate) were synthesised and used as neutral carriers in membrane electrodes t o improve the selectivity for Cu2+. The electrodes based o n these ionophores, with o-nitrophenyl octyl ether as a plasticising solvent mediator and potassium tetrakis-(p-chloropheny1)borate as an anion excluder, exhibit a linearity range of 10-1-10-6 M and have a Nernstian slope of 28-29 mV per decade at 25°C. The highly selective electrode based o n o-xylylene bis(diisobuty1dithiocarbamate) rejected the interference of alkali, alkaline earth and transition metal cations by a factor in the range l O 2 -l O 4 and showed a high selectivity for Cu2+ even in chloride and bromide media. The properties of the electrodes are discussed and also compared with those of o-xylylene bis(diethy1dithiocarbamate) under similar measurement conditions.

Adhesion is one of the most interesting subjects in interface phenomena from the viewpoint of wide-range applications as well as basic science. Interfacial water has significant effects on coatings, adhesives, and fiber-reinforced polymer composites, often causing adhesion loss. The way of thinking based on quantum mechanics is essential for a better understanding of physical and chemical properties of adhesive interfaces. In this work, the molecular mechanism of the adhesion interaction between epoxy resin and hydroxylated alumina surface in the presence of interfacial water molecules is investigated by using density-functional tight-binding calculations. Periodic slab model calculations demonstrate that hydrogen bond is an important factor at the adhesion interface. Effects of interfacial water molecules located between epoxy resin and hydroxylated alumina surface are assessed by using a dry model without interfacial water and wet models with water layers of 3, 6, and 9 Å thicknesses. Interesting first- and second-layer structures are observed in the distribution of interfacial water molecules in the tight space between the adhesive and adherend. Energy plots with respect to the displacement of epoxy resin from the alumina surface are nicely approximated by the Morse potential. The adhesion force and stress are theoretically obtained by differentiating the potential curve with respect to the displacement of epoxy resin. Computational results show that the adhesion force and stress are significantly weakened with an increase in the thickness of interfacial water layer. Thus, interfacial water molecules have a clue as to the role of water in the loss of adhesion.

Dual-size nanofibers consisting of a random mixture of nano- and submicron-size nanofibers are promising structures for specific applications such as air filters because of their increased specific surface area and low pressure drop. Synthesis of dual-size nanofibers using one-step electrospinning was reported here for the first time. The formation of well-mixed nano- and submicron-size cellulose-polyvinylpyrrolidone nanofiber composites was accomplished utilizing the physical properties of TEMPO-oxidized cellulose nanofibers (i.e., high thixotropy and high magnitude of zeta potential) and tuning the charge of the polymer jet, which influences the formation and shape of Taylor cone, and Coulombic explosion. The dual-size nanofibers were then spun on the surface of a HEPA filter to obtain a multilayer air filter. Aerosol filtration measurements show that this multilayer air filter has an incredibly high performance, shown by the high quality factor (Qf), 0.117 Pa, which is 10 times the Qf of commercial HEPA filters.