Microscale Electrochemical Corrosion of Uranium Oxide Particles.

Understanding the corrosion of spent nuclear fuel is important for the development of long-term storage solutions. However, the risk of radiation contamination presents challenges for experimental analysis. Adapted from the system for analysis at the liquid-vacuum interface (SALVI), we developed a miniaturized uranium oxide (UO)-attached working electrode (WE) to reduce contamination risk.

A microfluidic electrochemical cell for studying the corrosion of uranium dioxide (UO).

We have developed a specialized microfluidic electrochemical cell that enables investigation of the electrochemical corrosion of microgram quantities of redox active solids. The advantage of downscaling is the reduction of hazards, waste, expense, and greatly expanding data collection for hazardous materials, including radioactive samples. Cyclic voltammetry was used to monitor the oxidation-reduction cycle of minute quantities of micron-size uraninite (UO) particles, from the formation of hexavalent uranium (U(vi)), UO and reduction to UO .

Integrated atomic force microscopy and x-ray irradiation for in situ characterization of radiation-induced processes.

Understanding radiation-induced chemical and physical transformations at material interfaces is important across diverse fields, but experimental approaches are often limited to either ex situ observations or in situ electron microscopy or synchrotron-based methods, in which cases the radiation type and dose are inextricably tied to the imaging basis itself. In this work, we overcome this limitation by demonstrating integration of an x-ray source with an atomic force microscope to directly monitor radiolytically driven interfacial chemistry at the nanoscale. We illustrate the value of in situ observations by examining effects of radiolysis on material adhesion forces in aqueous solution as well as examining the production of alkali nitrates at the interface between an alkali halide crystal surface and air.

Studying Corrosion Using Miniaturized Particle Attached Working Electrodes and the Nafion Membrane.

We developed a new approach to attach particles onto a conductive layer as a working electrode (WE) in a microfluidic electrochemical cell with three electrodes. Nafion, an efficient proton transfer molecule, is used to form a thin protection layer to secure particle electrodes. Spin coating is used to develop a thin and even layer of Nafion membrane.

Direct visualization of radiation-induced transformations at alkali halide-air interfaces.

Radiation driven reactions at mineral/air interfaces are important to the chemistry of the atmosphere, but experimental constraints (e.g. simultaneous irradiation, in situ observation, and environmental control) leave process understanding incomplete.

Stamping Nanoparticles onto the Electrode for Rapid Electrochemical Analysis in Microfluidics.

Electrochemical analysis is an efficient way to study various materials. However, nanoparticles are challenging due to the difficulty in fabricating a uniform electrode containing nanoparticles. We developed novel approaches to incorporate nanoparticles as a working electrode (WE) in a three-electrode microfluidic electrochemical cell.

Self-organizing layers from complex molecular anions.

The formation of traditional ionic materials occurs principally via joint accumulation of both anions and cations. Herein, we describe a previously unreported phenomenon by which macroscopic liquid-like thin layers with tunable self-organization properties form through accumulation of stable complex ions of one polarity on surfaces. Using a series of highly stable molecular anions we demonstrate a strong influence of the internal charge distribution of the molecular ions, which is usually shielded by counterions, on the properties of the layers.

High-Resolution Imaging of Dendrimers Used in Drug Delivery via Scanning Probe Microscopy.

Dendrimers and telodendrimer micelles represent two new classes of vehicles for drug delivery that have attracted much attention recently. Their structural characterization at the molecular and submolecular level remains a challenge due to the difficulties in reaching high resolution when imaging small particles in their native media. This investigation offers a new approach towards this challenge, using scanning tunneling microscopy (STM) and atomic force microscopy (AFM).

High-resolution imaging of the intramolecular structure of indomethacin-carrying dendrimers by scanning tunneling microscopy.

Dendrimers have shown great potential in drug delivery because of their enhancement of drug solubility in aqueous media, leading to an increase in in vivo circulation and efficacy to targets. The structure of drug-dendrimer complexes however, is not well-known owing to the difficulties associated with visualizing individual drug molecules attached to dendrimers. Scanning tunneling microscopy (STM) enables visualization of dendrimer intramolecular structures using our approach of metal ion tagging.