Catálogo de publicaciones - revistas

<jats:title>Snapshots of bacteriorhodopsin</jats:title> <jats:p> Bacteriorhodopsin is a membrane protein that harvests the energy content from light to transport protons out of the cell against a transmembrane potential. Nango <jats:italic>et al.</jats:italic> used timeresolved serial femtosecond crystallography at an x-ray free electron laser to provide 13 structural snapshots of the conformational changes that occur in the nanoseconds to milliseconds after photoactivation. These changes begin at the active site, propagate toward the extracellular side of the protein, and mediate internal protonation exchanges that achieve proton transport. </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="6319" page="1552" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah3497">1552</jats:related-article> </jats:p>

<jats:title>Watching Majorana bound states form</jats:title> <jats:p> Majorana bound states (MBSs) are peculiar quasiparticles that may one day become the cornerstone of topological quantum computing. To engineer these states, physicists have used semiconductor nanowires in contact with a superconductor. Although many of the observed properties align with theoretical predictions, a closer look into the creation of MBSs is desirable. Deng <jats:italic>et al.</jats:italic> fabricated nanowires with a quantum dot at one end that served as a spectrometer for the states that formed inside the superconducting gap of the nanowire. Using this setup, topologically trivial bound states were seen to coalesce into MBSs as the magnetic field was varied. </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="6319" page="1557" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf3961">1557</jats:related-article> </jats:p>

<jats:title>Rosetta observes sublimating surface ices</jats:title><jats:p>Comets are “dirty snowballs” made of ice and dust, but they are dark because the ice sublimates away, leaving some of the dust behind on the surface. The Rosetta spacecraft has provided a close-up view of the comet 67P/Churyumov-Gerasimenko as it passes through its closest point to the Sun (see the Perspective by Dello Russo). Filacchione<jats:italic>et al.</jats:italic>detected the spectral signature of solid CO<jats:sub>2</jats:sub>(dry ice) in small patches on the surface of the nucleus as they emerged from local winter. By modeling how the CO<jats:sub>2</jats:sub>sublimates, they constrain the composition of comets and how ices generate the gaseous coma and tail. Fornasier<jats:italic>et al.</jats:italic>studied images of the comet and discovered bright patches on the surface where ice was exposed, which disappeared as the ice sublimated. They also saw frost emerging from receding shadows. The surface of the comet was noticeably less red just after local dawn, indicating that icy material is removed by sunlight during the local day.</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="6319" page="1563" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aag3161">1563</jats:related-article>, p.<jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6319" page="1566" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aag2671">1566</jats:related-article>; see also p.<jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6319" page="1536" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aal1964">1536</jats:related-article></jats:p>

<jats:title>Rosetta observes sublimating surface ices</jats:title> <jats:p> Comets are “dirty snowballs” made of ice and dust, but they are dark because the ice sublimates away, leaving some of the dust behind on the surface. The Rosetta spacecraft has provided a close-up view of the comet 67P/Churyumov-Gerasimenko as it passes through its closest point to the Sun (see the Perspective by Dello Russo). Filacchione <jats:italic>et al.</jats:italic> detected the spectral signature of solid CO <jats:sub>2</jats:sub> (dry ice) in small patches on the surface of the nucleus as they emerged from local winter. By modeling how the CO <jats:sub>2</jats:sub> sublimates, they constrain the composition of comets and how ices generate the gaseous coma and tail. Fornasier <jats:italic>et al.</jats:italic> studied images of the comet and discovered bright patches on the surface where ice was exposed, which disappeared as the ice sublimated. They also saw frost emerging from receding shadows. The surface of the comet was noticeably less red just after local dawn, indicating that icy material is removed by sunlight during the local day. </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="6319" page="1563" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aag3161">1563</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6319" page="1566" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aag2671">1566</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6319" page="1536" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aal1964">1536</jats:related-article> </jats:p>

<jats:title>Boron nitride catalysis</jats:title> <jats:p> Propene is one of the highest-volume organic chemicals produced. Propene has mainly been made from naphtha, but changes in the global supply chain are creating shortages. Direct conversion from propane, a component of natural gas, via reaction with oxygen is an attractive alternative, but existing approaches produce a large fraction of unwanted CO and CO <jats:sub>2</jats:sub> . Grant <jats:italic>et al.</jats:italic> report that boron nitride, normally an unreactive material, has high selectivity to catalyze the production of propene (77%) and ethene (13%). </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="6319" page="1570" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf7885">1570</jats:related-article> </jats:p>

<jats:title>Extending qubit lifetime through a shaped environment</jats:title> <jats:p> Qubits are the quantum two-level systems that encode and process information in quantum computing. Kept in isolation, qubits can be stable. In a practical setting, however, qubits must be addressed and interact with each other. Such an environment is typically viewed as a source of decoherence and has a detrimental effect on a qubit's ability to retain encoded information. Gustavsson <jats:italic>et al.</jats:italic> used a sequence of pulses as a source of “environment shaping” that could substantially increase the coherence time of a superconducting qubit. </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="6319" page="1573" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah5844">1573</jats:related-article> </jats:p>