Catalytic kinetics of single gold nanoparticles observed via optical microwell arrays.

Catalytic activities and kinetics are measured at the single-particle level for gold nanoparticles catalyzing a fluorogenic oxidation reaction. This measurement is accomplished by confining the reactions in optically addressable microwell arrays. Citrate-capped gold nanoparticles are isolated in sealed ∼70 fL microwells along with a substrate, and the accumulation of a fluorescent product over time is observed.

Effect of high velocity, large amplitude stimuli on the spread of depolarization in S1 "barrel" cortex.

We examined the effect of large, controlled whisker movements, delivered at a high speed, on the amplitude and spread of depolarization in the anesthetized mouse barrel cortex. The stimulus speed was varied between 1500 and 6000°/s and the extent of movement was varied between 4° and 16°. The rate of rise of the response was linearly related to the rate of rise of the stimulus.

Introducing medical students to radiology as paid emergency department triage assistants.

Purpose: The aim of this report is to provide a detailed description of a program employing medical students to assist with triaging off-hour diagnostic imaging studies at a major academic medical center.

Methods: Current and former participants of the Medical student Emergency Department (ED) Radiology Triage Program were interviewed regarding the inception, development, and impact of this program. Student participation and triage activities were compiled and tabulated from scheduling records and triage assistant call logs.

Force-induced redistribution of a chemical equilibrium.

Spiropyran (SP) mechanophores (mechanochemically reactive units) can impart the unique functionality of visual stress detection to polymers and have potential for use in smart materials with self-sensing capabilities. These color-generating mechanophores were incorporated into polyurethane via step growth polymerization. Polyurethane, which is inherently a versatile engineering polymer, possesses an optimized balance of mechanical toughness and elasticity to allow for investigation of the kinetics of the mechanochemical response of the SP mechanophore in the bulk polymer via fluorescence and absorbance measurements.

Dynamic regulation of fluorescent proteins from a single species of coral.

To gain a better understanding of the natural function of fluorescent proteins, we have undertaken quantitative analyses of these proteins in a single species of coral, Montastraea cavernosa, residing around Turneffe atoll, on the Belizean Barrier Reef. We identified at least 10 members of a fluorescent protein family in this species, which consist of 4 distinct spectral classes. As much as a 10-fold change in the overall expression of fluorescent proteins was observed from specimen to specimen, suggesting that fluorescent proteins are dynamically regulated in response to environmental or physiological conditions.

In vivo simultaneous tracing and Ca(2+) imaging of local neuronal circuits.

A central question about the brain is how information is processed by large populations of neurons embedded in intricate local networks. Answering this question requires not only monitoring functional dynamics of many neurons simultaneously, but also interpreting such activity patterns in the context of neuronal circuitry. Here, we introduce a versatile approach for loading Ca(2+) indicators in vivo by local electroporation.

Profiling an electrospray plume using surface-enhanced Raman spectroscopy.

We report the use of silver nanoparticles to obtain surface-enhanced Raman spectra of Crystal Violet in an electrospray plume. Surface enhancement allowed detection at low concentrations with the high specificity afforded by vibrational spectroscopy. SERS spectra were used to obtain an axial concentration profile closely matching that obtained in previous fluorescence experiments.