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The ability of cobalt, copper, and nickel salts to quench SDBS surfacted single-walled carbon nanotubes (SWNTs) with a concentration between 0.5 and 5 mM per 15 mg·L−1 of SWNT has been investigated. The following metal salts show a decrease in fluorescence of the SWNTs: CuSO4, Cu(OAc)2, CuCl2, CoSO4, Co(OAc)2, CoCl2, NiSO4, Ni(OAc)2, and NiCl2. The Stern−Volmer quenching constants are found to depend on the identity of the metal ion and the anion but not on the chirality (similar to other ions of the same size) of the SWNT. As with Group 2 and 12 metal ions, the SWNT exciton formed from light absorption is sensitive to its local environment, and the field around the metal ions has a significant effect on the exciton facilitating nonradiative decay paths. Increased quenching is observed with transition-metal ions as compared to their Group 2 and 12 analogs, and this differs from the established charge versus ionic-volume trend observed with the latter. Some of this apparent increase is due to absorption by...

Ordered carbonaceous growth typically requires high-energy methods such as arc discharge [1] or decomposition of hydrocarbon-based precursors using laser [2–4], plasma [3], or thermolytic techniques [4]. For the latter technique, temperature regimes on the order of 600–1000° C are most common, with a few recent reports citing lower temperatures using halogenated precursors [5–7], or through alkali-metal catalyzed transformation of bulk carbon allotropes [8,9]. Sailor etal. have reported the first growth of non-amorphous carbon deposits at room temperature [10]. However, their electrochemical synthesis did not produce nanostructural carbon; due to the absence of nanosized catalytic seeds, the diameters of their fibers were > 5μm, and contained copious amounts of Cl, H, N, and O impurities.

While drilling through pressure-depleted formations, drilling-induced fracturing often occurs. Fracturing results when the drilling fluid overburden pressure exceeds the fracture pressure of the rock, initiating fractures that may further propagate as overburden pressure is increased. The growth in the aperture of these fractures results in lost circulation incidents. The consequences pose a major economic and safety risk when drilling. Numerous papers have been published on the concept of maximizing the fracture width to preserve the resulting hoop stress around the wellbore and effectively decrease drilling fluid losses. Using these techniques to control lost circulation with bridging materials can be extremely difficult when drilling with non-aqueous, oil-based fluid. The reduced permeability of an oil-wet filter cake prevents carrier fluid leak-off and necessary solids concentration. The resulting lower-strength plug in the fracture prevents effective support. The fracture then closes, preventing maximum hoop compression of the wellbore. Altering the oil-wet solids in the fracture to water-wet conditions increases the ability for pressure to leak-off in fractures when placing bridging agents. This capability is paramount to improving bridging agent placement and increasing the effective strength of the wellbore. A lost circulation pill system has been developed that alters the wettability of the fracture from oil-wet to water-wet. This pill system penetrates and water-wets oil-containing fractures and enables fast pressure leak-off and fracture support, effectively increasing pressure required for fracture growth. Laboratory and chemical methods are presented that show the system is effective over a broad range of temperatures and differential pressures.

We describe the growth of amorphous carbon nanofibers (CNFs) from iron-encapsulated dendrimer catalysts at ambient temperature and pressure conditions. Both fourth-generation poly (propyleneimine) (PPI) and poly(amidoamine) (PAMAM) dendrimers were suitable macromolecular hosts for the catalytic species. Average nanofiber diameters range from 10 - 15 nm, with lengths in excess of 20 microns.