Spotlights Cite This: J. Phys. Chem. Lett. 2019, 10, 693−693
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Spotlights: Volume 10, Issue 3
J. Phys. Chem. Lett. 2019.10:693-693. Downloaded from pubs.acs.org by 193.56.75.24 on 02/12/19. For personal use only.
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TRACKING THE CONNECTION BETWEEN DISORDER AND ENERGY LANDSCAPE IN GLASSES USING GEOLOGICALLY HYPERAGED AMBER In 1995, the Nobel laureate P. W. Anderson immortalized the glass transition as “perhaps the deepest and most interesting unsolved problem in condensed matter physics.” Anderson’s estimate that a conclusive statement about glass formation has yet to be formulated could not be more timely today due to a mix of fundamental and practical obstacles. First, glass formation is a history-dependent fallout of equilibrium: Different glasses with diverse properties can originate from a single liquid. Second, glass is a nonergodic system: Any practical experimental observation can sample only a very small portion of the phase space available to the system, which continuously ages to reach energetically favorable and stable conditions. The characterization of how the physical properties are modified by natural aging is of great significance in order to understand the nature of the metastability of the glassy state. Pogna et al. (10.1021/acs.jpclett.9b00003) took advantage of the extreme natural stabilization experienced by millions-ofyears-old fossil amber to determine the evolution of the vibrational properties of a glass as it hikes down its energy landscape. To obtain and compare glasses sharing the same chemical composition but having very different stability levels, the authors “rejuvenated” the hyperaged sample by annealing into the supercooled liquid phase, erasing its geological thermal history and getting a standard glass. By applying a combination of high-resolution inelastic X-ray scattering techniques to such geologically hyperaged and rejuvenated materials, the authors were able to characterize the vibrational modes: the so-called Boson peak in the vibrational density of state, which is the fingerprint of the glassy state, as well as the sound velocity and attenuation of hypersonic acoustic waves in the same frequency region. Once rationalized within the fluctuating elasticity theory, the results allowed them to establish a quantitative link between the position on the energy landscape reached upon aging and the disorder distribution of the elastic matrix.
specific binding of fluorescence-labeled oligonucleotide probes. Atomic force microscopy of dried ssDNA complexes on silica revealed that the contour and persistence lengths were similar to those of double-stranded DNA in the B-form. An advantage of linearizing ssDNA is that, in principle, any site can be targeted by a specific oligonucleotide probe, thus eliminating the need for labeling with the help of endonucleases. The customizability of the sequence and density of probes bound on DNA may improve the detection of genomic variation on a larger scale. The proposed technology could be promising in a range of applications, including the possibility of imaging a single-stranded genome including RNAs.
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TOWARD FUNDAMENTALS OF CONFINED ELECTROCATALYSIS IN NANOSCALE REACTORS Electrochemical reactions have been shown to be faster and more efficient in confined nanoscale reactorsbut why? What is the charge transfer efficiency in confined spaces? Could the confinement actually change the electrochemical potential of reactants? Are the kinetics improved in electrocatalysis in nanoscale reactors? Li et al. (10.1021/acs.jpclett.8b03448) set out to answer these questions using first-principle density functional calculations and a newly developed electrochemical model. The authors found that the electrochemical potential of reactants in a confined nanoscale reactor can be enhanced significantly, thus increasing the efficiency of the electrochemical reactions. The findings answer several fundamental questions and increase our understanding of “confinement energy”, i.e., the nature of electrochemical reactions in nanoscale reactors, which may aid in the design of new catalytic systems.
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LINEARIZATION AND LABELING OF SINGLE-STRANDED DNA FOR OPTICAL SEQUENCE ANALYSIS Genetic profiling is a hot topic in the 21st century among genealogists, criminologists, medical specialists, and the generally curious. The field would benefit from linearization of single-stranded DNA (ssDNA) through the exposure of the unpaired bases to gene-targeting probes, but this is compromised by the flexibility of ssDNA and its tendency to form self-annealed structures. In their Letter, Basak et al. (10.1021/acs.jpclett.8b03465) demonstrate the linearization of ssDNA molecules via a diblock polypeptide copolymer coating. The copolymer coat prevents self-annealing of the unpaired bases and concomitant effects such as intramolecular folding and intermolecular aggregation but does not preclude site© 2019 American Chemical Society
Published: February 7, 2019 693
DOI: 10.1021/acs.jpclett.9b00266 J. Phys. Chem. Lett. 2019, 10, 693−693
