Catálogo de publicaciones - revistas

<jats:title>Extra-large and intersecting pores</jats:title> <jats:p> Thermally stable zeolites with large pores, such as zeolite Y with 12-membered rings, are used for converting large molecules from petroleum into smaller, more useful hydrocarbons. Lin <jats:italic>et al</jats:italic> . report the synthesis of ZEO-1, a thermally stable zeolite with extra-large, 16-membered rings. The use of tricyclohexylmethylphosphonium as an organic structure–directing agent created a zeolite with a fully interconnected multidimensional framework and a very high specific surface area. —PDS </jats:p>

<jats:title>Coupling up of spins and lattice</jats:title> <jats:p> The development of spintronics and magnetic data storage relies on understanding and controlling the dynamics of magnetic excitations within a material. Of crucial importance for practical applications is how fast the magnetization can be switched. Mashkovich <jats:italic>et al</jats:italic> . report the use of ultrafast terahertz radiation to create magnon excitations in the antiferromagnet cobalt difluoride that can then be coupled with phonon excitations (see the Perspective by Juraschek and Narang). Using light to control coupling between the spins and the lattice provides a route to manipulate magnetization in antiferromagnetic materials on ultrafast time scales. —ISO </jats:p>

<jats:title>Radical cyclization made easy</jats:title> <jats:p> Metalloenzymes contain metal cofactors that can sometimes be exploited to catalyze reactions distinct from their natural function. Drawing on inspiration from heme-based radical polymerizations, Zhou <jats:italic>et al</jats:italic> . screened a panel of metalloproteins for candidates that could catalyze an atom-transfer radical cyclization, producing a lactam from an amide substrate bearing bromoalkyl and alkene functional groups (see the Perspective by Zhang and Dydio). Cytochrome P-450 derivatives were effective catalysts, and a series of enzyme variants were generated by directed evolution to access the full range of enantiomer and diastereomer products for model substrates. Such biocatalysts are valuable additions to the synthetic chemistry toolkit and reiterate the potential of metalloenzymes in catalyzing useful unnatural reactions. —MAF </jats:p>

<jats:title>Straining to make a transistor</jats:title> <jats:p> The use of carbon nanotubes (CNTs) as short-channel-length transistors will require control of their chirality, which determines whether they are semiconducting or metallic and if they form strong, low-resistance contacts. Tang <jats:italic>et al</jats:italic> . fabricated CNT intramolecular transistors by progressive heating and straining of individual CNTs within a transmission electron microscope. Changes to chirality along sections of the nanotube created metallic-to-semiconducting transitions. A semiconducting nanotube channel was covalently bonded to the metallic nanotube source and drain regions. The resulting CNT intramolecular transistors had channel lengths as short as 2.8 nanometers. —PDS </jats:p>

<jats:title>How the Delta variant evades defenses</jats:title> <jats:p> In the course of the COVID-19 epidemic, variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to emerge, some of which evade immunity or increase transmission. In late 2020, the Delta and Kappa variants were detected, and the Delta variant became globally dominant by June 2021. McCallum <jats:italic>et al</jats:italic> . show that vaccine-elicited serum-neutralizing activity is reduced against these variants. Based on biochemistry and structural studies, the authors show that mutations in the domain that binds the ACE2 receptor abrogate binding to some monoclonal antibodies but do not improve ACE2 binding, suggesting that they emerged to escape immune recognition. Remodeling of the N-terminal domain allows the variants to escape recognition by most neutralizing antibodies that target it. The work could guide the development of next-generation vaccines and antibody therapies. —VV </jats:p>

<jats:title>A tool to probe SARS-CoV-2 biology</jats:title> <jats:p> To develop therapies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and emerging variants, it is important to understand the viral biology and the effect of mutations. However, this is challenging because live virus can only be studied in a few laboratories that meet stringent safety standards. Syed <jats:italic>et al</jats:italic> . describe a virus-like particle (VLP) that comprises the four SARS-CoV-2 structural proteins, but instead of packaging viral RNA, it packages messenger RNA (mRNA) that expresses a reporter protein (see the Perspective by Johnson and Menachery). The amount of reporter expressed in receiver cells depends on the efficiency of packaging and assembly in the producer cells and the efficiency of entry into receiver cells. Mutations in the nucleocapsid protein that are found in more transmissible variants increase mRNA packaging and expression. The VLPs provide a platform for studying the effect of mutations in the structural proteins and for screening therapeutics. —VV </jats:p>

<jats:title>Another benefit of dietary fiber</jats:title> <jats:p> The gut microbiome can modulate the immune system and influence the therapeutic response of cancer patients, yet the mechanisms underlying the effects of microbiota are presently unclear. Spencer <jats:italic>et al</jats:italic> . add to our understanding of how dietary habits affect microbiota and clinical outcomes to immunotherapy. In an observational study, the researchers found that melanoma patients reporting high fiber (prebiotic) consumption had a better response to checkpoint inhibitor immunotherapy compared with those patients reporting a low-fiber diet. The most marked benefit was observed for those patients reporting a combination of high fiber consumption and no use of over-the-counter probiotic supplements. These findings provide early insights as to how diet-related factors may influence the immune response. —PNK </jats:p>

<jats:title>The amygdala and goal-directed actions</jats:title> <jats:p> Almost everything we do in our daily lives is goal directed. The brain can maintain a motivational state to direct actions to achieve desired outcomes. Using deep-brain calcium imaging, electrophysiology, and optogenetics in mice, Courtin <jats:italic>et al</jats:italic> . observed that at the time of goal-directed action, basolateral amygdala principal neurons integrate and encode pursued outcome identity, pursued outcome value, and action-outcome contingency information. At the time of consumption, basolateral amygdala neuronal firing represents current outcome identity and value. Together, action- and consumption-associated activity integrate behaviorally relevant information at distinct time points along goal-directed action-consumption sequences. —PRS </jats:p>

<jats:title>Cell type diversity in the neocortex</jats:title> <jats:p> The ability to link molecularly identified neurons with their function during behavior requires monitoring the activity of these cell types in vivo. Condylis <jats:italic>et al</jats:italic> . developed a platform for population functional imaging with spatial transcriptomics. Using newly acquired transcriptomic cell census data from the Allen Institute for Brain Science, the authors studied the function of cell types in primary somatosensory cortex in mice performing a tactile working memory task. Task-related properties of both excitatory and inhibitory neurons continued to differentiate as they were segregated into increasingly discrete molecular types. A new excitatory cell type, Baz1a, formed a sensory-driven circuit hub that orchestrates local sensory processing in superficial layers of the neocortex. This approach opens new venues for exploring information processing in the brain. —PRS </jats:p>