A procedure has been developed which utilizes aminopropyltriethoxysilane (APS) as the catalyst and a comonomer in the production of hybrid organo-silica nanoparticles. Particles ranging from ca. 100 to 500 nm can be prepared using organo-silanes of the type RSi(OR) 3 , where R ‫؍‬ Me, vinyl, allyl, or other hydrophobic groups and R ‫؍‬ Me or Et, in a water/surfactant solution. Based on elemental analysis, up to 10 mol% of APS was incorporated into the siloxane particle network. It is thought that the amino groups are located mainly on the surface due to their hydrophilicity and APS relatively slow rate of hydrolysis and condensation.

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The bond between fresh and hardened concrete can be subjected to various stress states depending on the application and service conditions. Four test methods, reflecting different stress states at the bond between the fresh and hardened concrete, are evaluated. The four methods are a slant shear test, an indirect tension test and two different flexure tests.The slant shear test is shown to b~ consistent and the most sensitive test in showing the strength of the bond, and was used to evaluate the effect of the following parameters on that strength:We conclude that copolymer PVA is a poor bonding agent over a wide range of curing conditions and that the thickness of a portland cement mortar layer has a strong influence on bond strength. The other factors did not affect strength significantly.

The developing field of electroactive polymers, when the polymers are manipulated into thin film forms, offers potentially ideal materials for EM substrates. Mechanically, they are strong, flat, thin, and stable in the electron beam. For biological specimens, they are hydrophilic and their chemistry can be adapted to the particular specimen so the attachment can be gentle with no denaturation. They have the excellent electron optical properties of low Z, little grain, good electrical conductivity, and no observable radiation damage in the electron beam. Such films can be made fresh just prior to use to avoid contamination.Up to now, thin C films have been the best EM substrates for direct deposition of biological materials. With high vacuum evaporation of C, 20A thick films with >90% coverage of 4u windows in a holey film can be obtained. However, these films rapidly become hydrophobic by absorbing contaminants from the air and so need something like the wet-film technique or glow discharge to keep them hydrophilic. Even so, there are often hot spots of irreversible attachment of biological molecules causing distortion and even denaturation. Also, C films show a significant phase grain, presumably from C60 microcrystals.

The importance of controlling spray droplet size in the minimization of spray drift in the application of agricultural chemicals is widely acknowledged. Self-emulsifying tank-mix additives are an important tool for achieving this control. Understanding how these additives work is key in developing products that are both more efficient and more effective. Certain aspects of the performance of emulsion-based additives are well understood. In particular, oil droplets have been shown to induce perforations in the sheet emerging from a spray nozzle. The growth of these perforations results in the formation of a web that then shatters, creating spray droplets. Fragmentation closer to the nozzle outlet is believed to cause the generation of larger spray droplets. It has been suggested that the properties of deformable oil-phase droplets are important, while in general solid particles are ineffective in reducing drift. Beyond these details the mechanism of spray formation from tank mixes containing emulsions is not well understood. In this study we evaluated the relations between oil-droplet rheology and spray quality for tank-mix and model systems. In particular, we used an optical tensiometer equipped with a pulsating drop module to measure the effects of individual tank-mix components on the dilatational rheology of paraffinic and seed-oil droplets. Spray patterns of these systems were evaluated in a vertically oriented low-speed wind tunnel using industry-established laser-diffraction and imaging techniques. The correlation between these properties are presented.