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<jats:p>Editors’ selections from the current scientific literature</jats:p>

<jats:title>A look at variant-specific boosters</jats:title> <jats:p> The evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) has raised the question of whether current COVID-19 vaccines protect against VOCs and if a variant specific vaccine may be needed. Of the currently identified VOCs, the Delta variant is believed to be the most transmissible, whereas the Beta variant appears to be the most vaccine resistant. Corbett <jats:italic>et al</jats:italic> . looked at the effect of vaccine boosting using either the original WA-1 strain vaccine or a Beta variant–specific booster. Around 6 months after the primary two-dose vaccine series, a third boost vaccination resulted in higher neutralizing antibody levels against VOCs in nonhuman primates. Regardless of whether the boost was from the original vaccine or the Beta-specific version, similar increases in neutralizing antibody levels were observed and resulted in enhanced viral protection. —PNK </jats:p>

<jats:title>Delta’s spike</jats:title> <jats:p> Understanding the molecular mechanisms of the increased transmissibility and immune evasion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants is critical to guiding current and future intervention strategies. Zhang <jats:italic>et al</jats:italic> . determined cryo–electron microscopy structures of the full-length spike protein trimers of the Delta, Kappa, and Gamma variants of SARS-CoV-2 and studied their function and antigenic properties. The Delta spike protein fused membranes more efficiently at low levels of the cellular receptor ACE2, and its pseudotyped viruses infected target cells substantially more rapidly than all other variants tested, possibly at least partly accounting for its heightened transmissibility. Mutations of each variant rearranged the antigenic surface of the N-terminal domain of the spike protein but only caused local changes in the receptor-binding domain, consistent with greater resistance to neutralizing antibodies. These findings elucidate the molecular events that have led these viruses to adapt in human communities and to evade host immunity. —VV </jats:p>

<jats:title>Rational design of stable nanocatalysts</jats:title> <jats:p> Sintering of nanoparticles is one of the main causes of their catalytic deactivation. Rational design of nanocatalysts that are stable against sintering is a grand challenge in heterogenous catalysis. Hu <jats:italic>et al</jats:italic> . present kinetic theories for two competing sintering mechanisms, Ostwald ripening and particle migration, which relate the rates of both processes to fundamental interaction energies in metal nanoparticle-support combinations. Using kinetic simulations for hundreds of such pairs, the authors show a universal volcano dependence of the sintering kinetics on the metal-support binding energy that can serve as a single descriptor to predict nanoparticle growth rates. The revealed scaling relations are a good start in the development of high-throughput screening computational approaches to drive discovery of sintering-resistant nanocatalysts. —YS </jats:p>

<jats:title>Why oil and water do not mix</jats:title> <jats:p> It is well known that oil forms stable droplets that carry a negative electrophoretic mobility (and negative charge) upon dispersing in water. However, the underlying mechanism is a long-debated topic. Using vibrational sum-frequency scattering spectroscopy, Pullanchery <jats:italic>et al</jats:italic> . recorded the interfacial vibrational spectrum in the oxygen–deuterium and carbon–hydrogen stretching regions of a hexadecane–water interface. Their spectral analysis accompanied by molecular dynamics simulations showed that water molecules form “improper” interfacial hydrogen bonds with alkyl hydrogens, resulting in the water-to-oil charge transfer that stabilizes oil droplets. This work demonstrates that sum-frequency scattering spectroscopy is a powerful technique that can improve our understanding of hydrophobicity in water-mediated chemical and biological systems. —YS </jats:p>

<jats:title>Resilient secondary tropical forests?</jats:title> <jats:p> Although deforestation is rampant across the tropics, forest has a strong capacity to regrow on abandoned lands. These “secondary” forests may increasingly play important roles in biodiversity conservation, climate change mitigation, and landscape restoration. Poorter <jats:italic>et al</jats:italic> . analyzed the patterns of recovery in forest attributes (related to soil, plant functioning, structure, and diversity) in 77 secondary forest sites in the Americas and West Africa. They found that different attributes recovered at different rates, with soil recovering in less than a decade and species diversity and biomass recovering in little more than a century. The authors discuss how these findings can be applied in efforts to promote forest restoration. —AMS </jats:p>

<jats:title>Shared systems in leaf development</jats:title> <jats:p> The long, narrow leaves of grasses look rather different from the often shorter, flatter leaves of eudicot plants. Richardson <jats:italic>et al</jats:italic> . combined developmental genetics and computational modeling to reveal that these two types of leaves, which are widely separated by evolution, have more in common than expected. Expression of similar patterning genes in the primordial zone is confined to a wedge for the eudicot leaf but expanded to concentric domains in the grass leaf, driving development of the cylindrical, encircling sheath characteristic of grass leaves. Addition or removal of gene expression in a marginal zone contributes to the development of the broader leaf characteristic of eudicots. Thus, grass and eudicot leaves are diversified elaborations of shared toolkits. —PJH </jats:p>

<jats:title>Imaging a peculiar Fermi surface</jats:title> <jats:p> Running a current through a superconductor can cause the superconducting gap to close on a section of the Fermi surface. However, observing this segmented Fermi surface directly is tricky. To do so, Zhu <jats:italic>et al</jats:italic> . worked with a thin film of the topological insulator bismuth telluride placed on top of superconducting niobium diselenide. A small applied magnetic field caused a screening current, which in turn led to a segmented Fermi surface in the topological insulator layer. Using a scanning tunneling microscope, the researchers were able to map out this Fermi surface. —JS </jats:p>

<jats:title>Improving DFT with deep learning</jats:title> <jats:p> In the past 30 years, density functional theory (DFT) has emerged as the most widely used electronic structure method to predict the properties of various systems in chemistry, biology, and materials science. Despite a long history of successes, state-of-the-art DFT functionals have crucial limitations. In particular, significant systematic errors are observed for charge densities involving mobile charges and spins. Kirkpatrick <jats:italic>et al</jats:italic> . developed a framework to train a deep neural network on accurate chemical data and fractional electron constraints (see the Perspective by Perdew). The resulting functional outperforms traditional functionals on thorough benchmarks for main-group atoms and molecules. The present work offers a solution to a long-standing critical problem in DFT and demonstrates the success of combining DFT with the modern machine-learning methodology. —YS </jats:p>

<jats:title>Single element switch</jats:title> <jats:p> Phase-change materials are attractive for computer memory and switching, in part due to their small size and fast switching speeds. However, competitive materials frequently have many elements, which decreases the switching reliability. Shen <jats:italic>et al</jats:italic> . built a pure tellurium device that is capable of fast switching through a phase transformation (see the Perspective by Calarco and Arciprete). Unlike many other phase-change materials, the change in resistance happens because the tellurium melts during the switching process. The resulting device can be switched 100 million times before failure and is an appealing route for avoiding the issues from multi-element phase-change materials. —BG </jats:p>