Catálogo de publicaciones - revistas

<jats:title>Phase transition of scattered light</jats:title> <jats:p> Disordered structures can give rise to intriguing scattering phenomena owing to the unpredictable nature of their interaction with light. Using subwavelength-scale disordered metasurfaces, Maguid <jats:italic>et al.</jats:italic> observed a phase transition in how the light is scattered as a function of disorder. Weak disorder induced a photonic spin Hall effect, whereas strong disorder led to spin-split modes in momentum space, a random optical-Rashba effect. Thus, designed photonic structure could offer a versatile platform to study similar phenomena in complex solid-state systems. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1411" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aap8640">1411</jats:related-article> </jats:p>

<jats:title>Breaking the symmetry in a supersolid</jats:title><jats:p>The concept of broken symmetry has relevance across all branches of physics, including particle and condensed matter physics. In many cases, the shape of the potential energy resembles a Mexican hat, and the symmetry of the system is broken when it chooses a particular spot along the “trough” of the hat. Out of this minimum-energy state, the system can undergo collective excitations either along the trough or perpendicular to it. Léonard<jats:italic>et al.</jats:italic>detected these so-called Goldstone and Higgs modes in a supersolid Bose-condensed atomic gas held in two crossed optical cavities. By monitoring the dynamics of the light field in each cavity, the oscillations of the order parameter associated with both modes were observed in real time.</jats:p><jats:p><jats:italic>Science</jats:italic>, this issue p.<jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1415" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aan2608">1415</jats:related-article></jats:p>

<jats:title>Stable catalysts through steaming</jats:title> <jats:p> The lifetime of catalysts that convert automotive exhaust pollutants can be increased by lowering their operating temperature, which helps to prevent deactivation caused by the active metal atoms agglomerating into larger, less active particles. Nie <jats:italic>et al.</jats:italic> show that a thermally stable catalyst, atomically dispersed Pt <jats:sup>2+</jats:sup> on CeO <jats:sub>2</jats:sub> , can become active for CO oxidation at 150°C after steam treatment at 750°C. In studies with simulated vehicle exhaust, this catalyst treatment also improves its oxidation activity for other exhaust components such as hydrocarbons. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1419" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aao2109">1419</jats:related-article> </jats:p>

<jats:title>Fast phase change with no preconditions</jats:title> <jats:p> Random access memory (RAM) devices that rely on phase changes are primarily limited by the speed of crystallization. Rao <jats:italic>et al.</jats:italic> combined theory with a simple set of selection criteria to isolate a scandium-doped antimony telluride (SST) with a subnanosecond crystallization speed (see the Perspective by Akola and Jones). They synthesized SST and constructed a RAM device with a 700-picosecond writing speed. This is an order of magnitude faster than previous phase-change memory devices and competitive with consumer dynamic access, static random access, and flash memory. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1423" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aao3212">1423</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1386" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aaq0476">1386</jats:related-article> </jats:p>

<jats:title>Dispersing small, bimetallic nanoparticles</jats:title> <jats:p> For applications of nanoparticles in sensing and catalysis, smaller nanoparticles are often more effective because they expose more active surface sites. The properties of metallic nanoparticles can also be improved by creating bimetallic alloys, but typical synthetic methods yield larger nanoparticles where the metals are poorly mixed. Wong <jats:italic>et al.</jats:italic> show that well-mixed bimetallic ∼1-nm-diameter nanoparticles can be made on silica supports. To do this, they exploited strong electrostatic adsorption, in which the metal precursors are strongly adsorbed onto the surface by controlling pH relative to the surface point of zero charge. Their method was successful for a wide range of metal alloys. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1427" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aao6538">1427</jats:related-article> </jats:p>

<jats:title>An extra sugar protects</jats:title> <jats:p> Many microbial pathogens produce proteins that are toxic to the cells that they are targeting. Broad-leaved plants are susceptible to NLP (necrosis and ethylene-inducing peptide 1–like protein) toxins. Lenarčič <jats:italic>et al.</jats:italic> identified the receptors for NLP toxins to be GIPC (glycosylinositol phosphorylceramide) sphingolipids (see the Perspective by Van den Ackerveken). Their findings reveal why these toxins only attack broad-leaved plants (so-called eudicots): If the sphingolipid carries just two hexoses, as is the case for eudicots, the toxin binds and causes cell lysis. But in monocots with sphingolipids that have three hexoses, the toxin is ineffective. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1431" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aan6874">1431</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1383" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aar4188">1383</jats:related-article> </jats:p>

<jats:title>A little zinc makes the rings all link</jats:title> <jats:p> Although polymer strands are often informally called chains, molecular topologies that actually resemble extended macroscopic chain links have proven surprisingly challenging to make. Most approaches have settled for tethering pairs of interlocked rings amid spacer segments. Wu <jats:italic>et al.</jats:italic> now report successful synthesis of polycatenanes in which tens of rings are consecutively interlinked. The key was using zinc ions to template the threading of one macrocycle precursor through flanking preformed macrocycles, after which metathesis catalysis closed up the first ring, and the metal could be flushed out. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1434" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aap7675">1434</jats:related-article> </jats:p>

<jats:title>A structural look at α-synuclein oligomers</jats:title> <jats:p> Fibrillar aggregates of the protein α-synuclein (αS) are the major constituents of Lewy bodies in Parkinson's disease. However, small oligomers that accumulate during the process of fibril formation are thought to cause the neuronal toxicity associated with the onset and progression of Parkinson's disease. Little is known about the detailed structural properties of αS oligomers and the molecular mechanisms that lead to their toxicity. Fusco <jats:italic>et al.</jats:italic> report the structural characterization of two forms of αS oligomers, which elucidates the fundamental structural elements giving rise to neuronal toxicity. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1440" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aan6160">1440</jats:related-article> </jats:p>

<jats:title>Bacteria go the distance in cancer</jats:title> <jats:p> The bacterial species <jats:italic>Fusobacterium nucleatum</jats:italic> is associated with a subset of human colorectal cancers, but its role in tumorigenesis is unclear. Studying patient samples, Bullman <jats:italic>et al.</jats:italic> found that <jats:italic>F. nucleatum</jats:italic> and certain co-occurring bacteria were present not only in primary tumors but also in distant metastases. Preliminary evidence suggests that the bacterium is localized primarily within the metastatic cancer cells rather than in the stroma. Antibiotic treatment of mice carrying xenografts of <jats:italic>F. nucleatum</jats:italic> –positive human colorectal cancer slowed tumor growth, consistent with a causal role for the bacterium in tumorigenesis. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1443" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aal5240">1443</jats:related-article> </jats:p>

<jats:title>Tubulin carboxypeptidase identity revealed</jats:title> <jats:p> Enzymes of the α-tubulin detyrosination/tyrosination cycle create landmarks on microtubules that are essential for their multiple cellular functions and are altered in disease. Tubulin carboxypeptidases (TCPs) responsible for detyrosination have remained elusive for 40 years (see the Perspective by Akhmanova and Maiato). Aillaud <jats:italic>et al.</jats:italic> identified vasohibins as enzymes that perform the TCP function and found that their small interacting partner SBVP was essential for their activity. Vasohibin/SVBP complexes were involved in neuron polarization and brain cortex development. The authors also developed an inhibitor targeting this family of enzymes. Using a completely different strategy, Nieuwenhuis <jats:italic>et al.</jats:italic> also showed that vasohibins can remove the C-terminal tyrosine of α-tubulin. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1448" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aao4165">1448</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1453" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aao5676">1453</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6369" page="1381" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aar3895">1381</jats:related-article> </jats:p>