Tributes to Professor Cyril A. Fox, Jr.

Cy Fox often forgets that he was supposed to be “only” an academic. For three decades, as he helped thousands of law students through the intricacies of the Rule in Shelley’s Case, or watched them calculate a “life in being plus twenty one years” for the Rule Against Perpetuities, he failed to appreciate that law school was supposed to be an amalgam of theory and confusion, not the place for his teaching law students about helping real people solve real life problems

Improvement in the Light Extraction of Blue InGaN/GaN-Based LEDs Using Patterned Metal Contacts

We demonstrate a method to improve the light extraction from an LED using photonic crystal (PhC)-like structures in metal contacts. A patterned metal contact with an array of Silicon Oxide (SiO x ) pillars (440 nm in size) on an InGaN/GaN-based MQW LED has shown to increase output illumination uniformity through experimental characterization. Structural methods of improving light extraction using transparent contacts or dielectric photonic crystals typically require a tradeoff between improving light extraction and optimal electrical characteristics. The method presented here provides an alternate solution to provide a 15% directional improvement (surface normal) in the radiation profile and ~ 30% increase in the respective intensity profile without affecting the electrical characteristics of the device. Electron beam patterning of hydrogen silesquioxane (HSQ), a novel electron beam resist is used in patterning these metal contacts. After patterning, thermal curing of the patterned resist is done to form SiO x pillars. These SiO x pillars aid as a mask for transferring the pattern to the p-metal contact. Electrical and optical characterization results of LEDs fabricated with and without patterned contacts are presented. We present the radiation and intensity profiles of the planar and patterned devices extracted using Matlab-based image analysis technique from 200 μm (diameter) circular unpackaged LEDs

Size-Dependent Energy Transfer between CdSe/ZnS Quantum Dots and Gold Nanoparticles

This Letter deals with the effect of the particle size on the energy transfer from CdSe/ZnS quantum dots to the proximal gold nanoparticles with different sizes. The 3 nm sized gold nanoparticles have negligible localized surface plasmon resonance (LSPR) absorption and quench the fluorescence emission of the quantum dots with a 1/<i>d</i>⁴ distance-dependence, indicating the nanometal surface energy transfer (NSET) mechanism. The 15 and 80 nm sized gold nanoparticles have strong LSPR absorption bands that overlap with the emission band of the quantum dots. The energy transfer efficiency depends on the 1/<i>d</i>⁶ separation distance, which is dominated by the dipole–dipole interaction according to Förster resonance energy transfer (FRET). The 80 nm sized gold nanoparticle displays higher quenching efficiency due to the increased spectral overlap of the LSPR band with the emission band of quantum dots

Easily Accessible Polycyclic Amines that Inhibit the Wild-Type and Amantadine-Resistant Mutants of the M2 Channel of Influenza A Virus

[Image: see text] Amantadine inhibits the M2 proton channel of influenza A virus, yet most of the currently circulating strains of the virus carry mutations in the M2 protein that render the virus amantadine-resistant. While most of the research on novel amantadine analogues has revolved around the synthesis of novel adamantane derivatives, we have recently found that other polycyclic scaffolds effectively block the M2 proton channel, including amantadine-resistant mutant channels. In this work, we have synthesized and characterized a series of pyrrolidine derivatives designed as analogues of amantadine. Inhibition of the wild-type M2 channel and the A/M2-S31N, A/M2-V27A, and A/M2-L26F mutant forms of the channel were measured in Xenopus oocytes using two-electrode voltage clamp assays. Most of the novel compounds inhibited the wild-type ion channel in the low micromolar range. Of note, two of the compounds inhibited the amantadine-resistant A/M2-V27A and A/M2-L26F mutant ion channels with submicromolar and low micromolar IC(50), respectively. None of the compounds was found to inhibit the S31N mutant ion channel

Protein Dielectric Constants Determined from NMR Chemical Shift Perturbations

Understanding the connection between protein structure and function requires a quantitative under-standing of electrostatic effects. Structure-based electrostatics calculations are essential for this purpose, but their use has been limited by a long-standing discussion on which value to use for the dielectric constants (εeff and εp) required in Coulombic models and Poisson-Boltzmann models. The currently used values for εeff and εp are essentially empirical parameters calibrated against thermodynamic properties that are indirect measurements of protein electric fields. We determine optimal values for εeff and εp by measuring protein electric fields in solution using direct detection of NMR chemical shift perturbations (CSPs). We measured CSPs in fourteen proteins to get a broad and general characterization of electric fields. Coulomb’s law reproduces the measured CSPs optimally with a protein dielectric constant (εeff) from 3 to 13, with an optimal value across all proteins of 6.5. However, when the water-protein interface is treated with finite difference Poisson-Boltzmann calculations, the optimal protein dielectric constant (εp) rangedsfrom 2-5 with an optimum of 3. It is striking how similar this value is to the dielectric constant of 2-4 measured for protein powders, and how different it is from the εp of 6-20 used in models based on the Poisson-Boltzmann equation when calculating thermodynamic parameters. Because the value of εp = 3 is obtained by analysis of NMR chemical shift perturbations instead of thermodynamic parameters such as pKa values, it is likely to describe only the electric field and thus represent a more general, intrinsic, and transferable εp common to most folded proteins.Science Foundation Irelan