The reductive desorption of n-alkanethiolate (RS-) self-assembled monolayers (SAMs) on gold, platinum, and palladium substrates was investigated. The kinetics of this process were too slow to measure directly in the case of RS-Pt and RS-Pd SAMs. Thus, the faradaic response of potassium ferricyanide after partial or complete desorption was determined and used to quantify the relative electrochemically accessible surface area. Both the type of underlying metal substrate and the chain length of the n-alkanethiol were varied. The relative alkanethiol binding affinity and effective kinetics of binding for each of the substrates were discussed in light of these observations.

Biogeochemical cycling in high-latitude regions has a disproportionate impact on global nutrient budgets. Here, we introduce a holistic, multidisciplinary framework for elucidating the influence of glacial meltwaters, shelf currents, and biological production on biogeochemical cycling in high-latitude continental margins, with a focus on the silica cycle. Our findings highlight the impact of significant glacial discharge on nutrient supply to shelf and slope waters, as well as surface and benthic production in these regions, over a range of timescales from days to thousands of years. Whilst biological uptake in fjords and strong diatom activity in coastal waters maintains low dissolved silicon concentrations in surface waters, we find important but spatially heterogeneous additions of particulates into the system, which are transported rapidly away from the shore. We expect the glacially-derived particles-together with biogenic silica tests-to be cycled rapidly through shallow sediments, resulting in a strong benthic flux of dissolved silicon. Entrainment of this benthic silicon into boundary currents may supply an important source of this key nutrient into the Labrador Sea, and is also likely to recirculate back into the deep fjords inshore. This study illustrates how geochemical and oceanographic analyses can be used together to probe further into modern nutrient cycling in this region, as well as the palaeoclimatological 3 approaches to investigating changes in glacial meltwater discharge through time, especially during periods of rapid climatic change in the Late Quaternary.

Transparent, conductive indium-tin oxide (ITO) and tin oxide thin films were deposited on soda-lime-silicate (SLS) float glass and silica glass substrates by an RF aerosol plasma technique in an atmospheric environment. The ITO films were deposited from solutions with various In: Sn ratios. The dependence of the film properties on the substrate temperature, deposition time, and tin concentration has been studied. The films were characterized by several techniques including XRD, EDS, electrical resistivity, SEM, optical (IR-UV-Vis transmission), Mössbauer, and infrared spectroscopy. The results showed that film phase, morphology, thickness, crystallite size, and conductivity depend on the solution composition and deposition parameters. XRD revealed that In2O3 was present in the film when a In: Sn ratio of 5: 5 or higher was used; otherwise only SnO2 shown. SEM analysis showed that dense and uniform films were formed with particle sizes ranging from approximately 50 nm to 150 nm. The resistivity of the ITO films ranged from 0.12 to 5.0 ohm-cm at room temperature. Optical transmission of the ITO-coated glasses was not different from the uncoated samples. Infrared results indicated that the structure of the near surface of the glasses was significantly modified with a higher indium concentration. The advantages of the atmospheric, RF aerosol plasma deposition process over other techniques are discussed.

Resonant tunneling transport was studied in GaAs-AlGaAs single well, double barrier structures. Negative differential resistance at 77 and 300 K was observed in devices grown by metalorganic chemical vapor deposition. The observed peak to valley ratios were 6 to 1 and 1.48 to 1, respectively. The presence of GaAs spacer layers was found to have a distinct effect on the 300 K current versus voltage characteristics. Microwave oscillation at frequencies up to 3.0 GHz was observed at 300 K. A short discussion of the oscillation frequency limits of our structure is presented.

Self-assembled monolayers of dodecanethiol on gold, palladium, and platinum can be locally replaced with a different thiol under the action of a scanning tunneling microscopy tip at elevated bias. This process is characterized and the bias dependence of the degree of replacement for each metal substrate is illustrated. Replacement on gold substrates occurs at lower applied potentials than on platinum substrates, provided care has been taken to remove surface oxides.