Spotlights pubs.acs.org/JPCL
Spotlights: Volume 8, Issue 15
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EFFECT OF DRYING RATE ON AEROSOL PARTICLE MORPHOLOGY
PROTEINS BREAKING BAD: A FREE ENERGY PERSPECTIVE It is well known that biological aging brings disease, and much work is being done to understand the processes involved in order to better predict disease onset. Proteins are emerging as a crucial piece of the puzzle. Proteins respond to changes in force with an instantaneous elastic recoil followed by a folding contraction, but aging disrupts this elasticity: Aged proteins “break bad,” becoming unstructured polymers. Valle-Orero et al. (10.1021/acs.jpclett.7b01509) studied this phenomenon using a free energy mesoscopic model, and they show that protein folding under force is constituted by two separable componentspolymer properties and hydrophobic collapse with the latter becoming irreversibly blocked when oxidative damage occurs. The findings may have implications for the study of other physiological phenomena, such as oxidation, protein−chaperon interaction, and post-translational modifications, which are crucial for modeling tissue elasticity.
Aerosol particles have complex effects on the Earth’s climate. Unlike greenhouse gases, which have a net warming effect on climate, aerosol particles have a net cooling effect; however, the magnitude of cooling remains uncertain. Determining aerosol particle properties such as composition, morphology, and size is crucial in order to incorporate them into climate models designed to quantify the direct and indirect effects of aerosol on climate. In the submicron size regime, the morphology of particles that undergo liquid−liquid phase separation depends on their size, whereas for some systems small particles are homogeneous and large particles are phase-separated. Using cryogenic transmission electron microscopy, Altaf and Freedman (10.1021/acs.jpclett.7b01327) studied the morphology of model organic aerosol systems and found that the transition region (where both homogeneous and phase-separated morphologies are seen) spanned 121 nm at the fastest drying rates with a midpoint diameter >170 nm. When the drying rate was slowed over several orders of magnitude, the transition region shifted to smaller diameters (midpoint < 40 nm), and the width narrowed to 4 nm. The findings suggest that the sizedependent morphology originates from an underlying finite size effect, rather than solely kinetics, due to the presence of size dependence even at the slowest drying rates. This could have significant consequences for cloud condensation nucleus activity and the growth of new particles in the atmosphere.
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A DIRECT ALCOHOL FUEL CELL DRIVEN BY AN OUTER SPHERE POSITIVE ELECTRODE In the ongoing pursuit of alternative fuels, direct alcohol fuel cells (DAFCs) are showing promise as a safer option than H2/ O2 fuel cells. However, several challenges hinder the widespread use of DAFC technology. For example, the electrocatalysts for either half-cell reactions are the same Pt-based catalysts, so routine approaches of employing heavy precious metal loading with engineered domains for alcohol tolerance have failed because the two half-cell reactions competitively coupled on the same Pt based cathode. Bhat et al. (10.1021/ acs.jpclett.7b01418) successfully decoupled the oxidative dehydrogenation of alcohols from the redox energy transformation of the electron acceptor on the same electrode by altering the interfacial chemistry at the cathode with an outer sphere redox species possessing a positive redox energy, leading to a DAFC equipped with an alcohol passive cathode, with performance metrics many times higher than Pt-based DAFCO2.
UNRAVELING THE SINGLE-NANOMETER THICKNESS OF SHELLS OF VESICLE-TEMPLATED POLYMER NANOCAPSULES
There is a lot of buzz about advances in targeted drug delivery, such as chemotherapy that can attack cancer cells while sparing healthy cells. Hollow polymer nanocapsules are emerging as a viable option for many practical applications and show promise as a platform for targeted drug delivery. In particular, vesicletemplated nanocapsules have received attention in recent years because of their precisely controlled permeability, fast mass transfer, and long-term stability; however, achieving a better understanding of the structural parameters of their shells has been challenging because of their extremely thin polymer structure. Richter et al. (10.1021/acs.jpclett.7b01149) set out to directly measure the thickness of the shells and to resolve the longstanding uncertainty about the bilayer-templated polymerization and the action of porogens responsible for the formation of selective nanopores, which are key issues in the directed assembly of nanocapsules and related materials. The authors used small-angle neutron scattering at the edge of detectability to elucidate structural data with high accuracy. Their findings contribute to our understanding of self-assembly and offer insights into the characterization of nanostructures. © 2017 American Chemical Society
Published: August 3, 2017 3696
DOI: 10.1021/acs.jpclett.7b01930 J. Phys. Chem. Lett. 2017, 8, 3696−3696
