Allen Guelzo, Henry R. Luce Professor of the Civil War Era and Director of Civil War Era Studies

In this first Next Page column of the 2014-15 academic year, Allen Guelzo, the Henry R. Luce Professor of the Civil War Era and Director of Civil War Era Studies, shares with us what he would ask Dickens, St. Paul, Tolstoy, and Lincoln if he had the chance; which texts inspired him to study history; and which title he would recommend if you want to fall in love with the Civil War

Allison Singley, Director of Parent Relations

In our new Next Page column, Allison Singley, Director of Parent Relations, shares with us the three books she is currently reading and why it might take her a while to finish them, her two desert island books (one of which inspired her doctoral dissertation), how she maintains a habit of reading poetry daily, and why she doesn’t write in books anymore — or feel the need to finish one

Erin O\u27Connor, Class of 2015

In this current issue of Next Page, Erin O\u27Connor, Class of 2015 and winner of this year\u27s Silent Leader Award, tells us which influential courses and works inspired her to develop her own major, Diversity and Development in Education, what conversation she would like to have with Paulo Freire if given the chance, and which books are on her To Read list for after graduation

A Biochemical Nickel(I) State Supports Nucleophilic Alkyl Addition: A Roadmap for Methyl Reactivity in Acetyl Coenzyme A Synthase

Nickel-containing enzymes such as methyl coenzyme M reductase (MCR) and carbon monoxide dehydrogenase/acetyl coenzyme A synthase (CODH/ACS) play a critical role in global energy conversion reactions, with significant contributions to carbon-centered processes. These enzymes are implied to cycle through a series of nickel-based organometallic intermediates during catalysis, though identification of these intermediates remains challenging. In this work, we have developed and characterized a nickel-containing metalloprotein that models the methyl-bound organometallic intermediates proposed in the native enzymes. Using a nickel(I)-substituted azurin mutant, we demonstrate that alkyl binding occurs via nucleophilic addition of methyl iodide as a methyl donor. The paramagnetic NiIII-CH3 species initially generated can be rapidly reduced to a high-spin NiII-CH3 species in the presence of exogenous reducing agent, following a reaction sequence analogous to that proposed for ACS. These two distinct bioorganometallic species have been characterized by optical, EPR, XAS, and MCD spectroscopy, and the overall mechanism describing methyl reactivity with nickel azurin has been quantitatively modeled using global kinetic simulations. A comparison between the nickel azurin protein system and existing ACS model compounds is presented. NiIII-CH3 Az is only the second example of two-electron addition of methyl iodide to a NiI center to give an isolable species and the first to be formed in a biologically relevant system. These results highlight the divergent reactivity of nickel across the two intermediates, with implications for likely reaction mechanisms and catalytically relevant states in the native ACS enzyme

In Solidarity

This edition of Next Page is a departure from our usual question and answer format with a featured campus reader. Instead, we asked speakers who participated in the College’s recent Student Solidarity Rally (March 1, 2017) to recommend readings that might further our understanding of the topics on which they spoke

Resonant energy transfer of triplet excitons from pentacene to PbSe nanocrystals.

The efficient transfer of energy between organic and inorganic semiconductors is a widely sought after property, but has so far been limited to the transfer of spin-singlet excitons. Here we report efficient resonant-energy transfer of molecular spin-triplet excitons from organic semiconductors to inorganic semiconductors. We use ultrafast optical absorption spectroscopy to track the dynamics of triplets, generated in pentacene through singlet exciton fission, at the interface with lead selenide (PbSe) nanocrystals. We show that triplets transfer to PbSe rapidly (<1 ps) and efficiently, with 1.9 triplets transferred for every photon absorbed in pentacene, but only when the bandgap of the nanocrystals is close to resonance (±0.2 eV) with the triplet energy. Following triplet transfer, the excitation can undergo either charge separation, allowing photovoltaic operation, or radiative recombination in the nanocrystal, enabling luminescent harvesting of triplet exciton energy in light-emitting structures.This is the author's accepted manuscript and will be under embargo until the 5th of April 2015. The final version is published by NPG in Nature Materials here: http://www.nature.com/nmat/journal/v13/n11/full/nmat4093.html

Single-walled carbon nanotube interactions with HeLa cells

This work concerns exposing cultured human epithelial-like HeLa cells to single-walled carbon nanotubes (SWNTs) dispersed in cell culture media supplemented with serum. First, the as-received CoMoCAT SWNT-containing powder was characterized using scanning electron microscopy and thermal gravimetric analyses. Characterizations of the purified dispersions, termed DM-SWNTs, involved atomic force microscopy, inductively coupled plasma – mass spectrometry, and absorption and Raman spectroscopies. Confocal microRaman spectroscopy was used to demonstrate that DM-SWNTs were taken up by HeLa cells in a time- and temperature-dependent fashion. Transmission electron microscopy revealed SWNT-like material in intracellular vacuoles. The morphologies and growth rates of HeLa cells exposed to DM-SWNTs were statistically similar to control cells over the course of 4 d. Finally, flow cytometry was used to show that the fluorescence from MitoSOX™ Red, a selective indicator of superoxide in mitochondria, was statistically similar in both control cells and cells incubated in DM-SWNTs. The combined results indicate that under our sample preparation protocols and assay conditions, CoMoCAT DM-SWNT dispersions are not inherently cytotoxic to HeLa cells. We conclude with recommendations for improving the accuracy and comparability of carbon nanotube (CNT) cytotoxicity reports

Sexual Selection, Physical Attractiveness, and Facial Neoteny: Cross-cultural Evidence and Implications [and Comments and Reply]

Physical attractiveness and its relation to the theory of sexual selection deserve renewed attention from cultural and biological anthropologists. This paper focuses on an anomaly associated with physical attractiveness-in our species, in contrast to many others, males seem to be more concerned than females with the attractiveness of potential sexual partners, perhaps because humans show far more age-related variance in female than in male fecundity. The resulting selection for male attraction to markers of female youth may lead incidentally to attraction to females displaying age-related cues in an exaggerated form. This paper reports cross-cultural evidence that males in five populations (Brazilians, U.S. Americans, Russians, Ache, and Hiwi) show an attraction to females with neotenous facial proportions (a combination of large eyes, small noses, and full lips) even after female age is controlled for. Two further studies show that female models have neotenous cephalofacial proportions relative to U.S. undergraduates and that drawings of faces artificially transformed to make them more or less neotenous are perceived as correspondingly more or less attractive. These results suggest several further lines of investigation, including the relationship between facial and bodily cues and the consequences of attraction to neoteny for morphological evolutio