Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) are used to monitor changes in the ionization of monolayers of 11-mercaptoundecanoic acid. When using an anionic redox probe, Fe(CN)6(-4), the charge-transfer resistance of the 11-mercaptoundecanoic acid monolayer-modified interface increases in a sigmoidal fashion as the solution is made basic. The opposite effect is observed when using a cationic redox probe. The inflection points of these two titration curves, however, differ when using the different redox probes. This result is taken as being characteristic of the influence that applied potential has on the ionization of the monolayer. The role of substrate potential on the ionization of the monolayer is further investigated by SECM. The SECM measurement monitors the concentration of Ru(NH3)6(+3) as the potential of the substrate is varied about the potential of zero charge. For monolayers of 11-mercaptoundecanoic acid in solutions buffered near the pKa of the terminal carboxylic acid, potential excursions positive of the PZC cause an increase in the concentration of Ru(NH3)6(+3) local to the interface, and potential excursions negative of the PZC cause a decrease in the local concentration of Ru(NH3)6(+3). Similar experiments conducted with an interface modified with 11-undecanethiol had no impact on the local concentration of Ru(NH3)6(+3). These results are interpreted in terms of the influence that applied potential has on the pH of the solution local to the interface and the impact that this has on the ionization of the monolayer.

A new experiment for use in introductory nanotechnology courses is described. This experiment allows students to fabricate metallic wires with microscale lateral dimensions and nanoscale vertical dimensions. Fabrication occurs in the capillaries of polydimethylsiloxane (PDMS) stamps modified with hydrophilic polymers. This experiment provides students with an opportunity to conduct templateassisted electrodeposition of micro-and nanomaterials, utilizing a reusable template instead of the commonly used porous, anodic alumina oxide (AAO) membranes that require dissolution to examine the wires. Fabrication of the metal wires is accomplished via the reduction of metal cations in the channels of modified PDMS stamps. In addition, this experiment introduces students to characterization using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and atomic-force microscopy (AFM). The microscale dimensions of the silver wires accommodate imaging with optical microscopy for institutions possessing limited characterization capabilities.

This paper describes a laboratory exercise that provides students enrolled in introductory nanotechnology courses with an opportunity to synthesize polymer structures with micro-and nanoscale dimensions. Polyvinylpyrrolidone (PVP) films deposited on corrugated PDMS stamps using student-built spin coaters were transferred to clean, dry substrates via microcontact printing. The microscale dimensions of the resulting patterns were characterized in class using optical microscopy. Characterization with atomic force microscopy (AFM) was used for visualization of nanoscale vertical dimensions of the structures. This laboratory investigation highlights the following concepts often associated with polymer nanostructure fabrication: polymer synthesis, surface chemistry, soft lithography, and contact angle. It is noteworthy to mention that this laboratory exercise demonstrates the feasibility of utilizing nontoxic, cost-effective, bench-top materials to teach and investigate fundamentals associated with fabrication of polymer nanomaterials.

a b s t r a c tShewanella-containing microbial fuel cells (MFCs) typically use the fresh water wild-type strain Shewanella oneidensis MR-1 due to its metabolic diversity and facultative oxidant tolerance. However, S. oneidensis MR-1 is not capable of metabolizing polysaccharides for extracellular electron transfer. The applicability of Shewanella japonica (an agar-lytic Shewanella strain) for power applications was analyzed using a diverse array of carbon sources for current generation from MFCs, cellular physiological responses at an electrode surface, biofilm formation, and the presence of soluble extracellular mediators for electron transfer to carbon electrodes. Critically, air-exposed S. japonica utilizes biosynthesized extracellular mediators for electron transfer to carbon electrodes with sucrose as the sole carbon source.Published by Elsevier Ltd.

This paper describes an experiment developed to provide students enrolled in introductory nanotechnology and introductory chemistry courses with an opportunity to synthesize silver nanowires using a bottom-up nanofabrication technique. The reaction between copper metal sputter coated on silicon dioxide and a dilute silver nitrate solution is used to create the nanowires. Included in this experiment is a characterization component allowing students to analyze the nanowires using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Microscale silver wires are also produced in the reaction, making it possible for students to utilize optical microscopy, in addition to AFM and SEM, for silver wire characterization. The silver nanowire synthesis reported in this paper does not require the use of nanoporous templates or hazardous purification steps to liberate wires from template confinement.