Catálogo de publicaciones - revistas

<jats:title>Stellar metals shine toward our eyes only</jats:title> <jats:p> Taking a different look at a familiar star may still yield surprises. Boggs <jats:italic>et al.</jats:italic> trained the x-ray vision of the NuSTAR observatory on the well-studied supernova 1987A. Core-collapse explosions such as SN 1987A produce a titanium isotope, <jats:sup>44</jats:sup> Ti, whose radioactive decay yields hard x-ray emission lines. All the emission associated with 44Ti appears to be from material moving toward us, with none moving away. This implies that the explosion was not symmetric. These findings help to explain the mechanics of SN 1987A and of core-collapse supernovae in general. </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="6235" page="670" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa2259">670</jats:related-article> </jats:p>

<jats:title>A circular route to confine electrons</jats:title> <jats:p> Physical barriers are used to confine waves. Whether it is harbor walls for sea waves, a glass disk for light, or the “whispering gallery” circular chamber walls in St. Paul's Cathedral for sound, the principle of confinement—reflection—is the same. Zhao <jats:italic>et al.</jats:italic> used that same principle to confine electrons in a nanoscale circular cavity in graphene. Periodic patterns within the cavity were associated with an electronic wave version of whispering gallery modes. The tunability of the cavity size may provide a route for the manipulation of electrons in graphene and similar materials. </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="6235" page="672" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa7469">672</jats:related-article> </jats:p>

<jats:title>Silent slip events get shallow</jats:title> <jats:p> Clues to help better predict the likelihood of devastating earthquakes and tsunamis may be embedded in a more gentle type of rumbling. Using oceanbottom seismometers, Yamashita <jats:italic>et al.</jats:italic> report rare observations of migrating tremors in the shallow part of a subduction zone off southern Kyushu, Japan. The tremors appear to be linked to a very low-frequency earthquake and seem to migrate to the region where big earthquakes are generated. The tremors may be tracing how and where stress gets concentrated onto the earthquake-producing portion of the fault. </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="6235" page="676" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa4242">676</jats:related-article> </jats:p>

<jats:title>Using friction to guide fabrication</jats:title> <jats:p> Ultralow friction found in certain layered materials such as graphite is important in the construction of nanomechanical devices. Koren <jats:italic>et al.</jats:italic> combined measurements and modeling to characterize the interaction of sliding graphite planes (see the Perspective by Liechti). This helped them to make small graphite devices that featured rotational pivots and multiple locking positions. </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="6235" page="679" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa4157">679</jats:related-article> </jats:p>

<jats:title>Going toward the grains</jats:title> <jats:p> Great strides have been made in improving the efficiency of organic-inorganic perovskite solar cells. Further improvements are likely to depend on understanding the role of film morphology on charge-carrier dynamics. de Quilettes <jats:italic>et al.</jats:italic> correlated confocal fluorescence microscopy images with those from scanning electron microscopy to spatially resolve the photoluminescence and carrier decay dynamics from films of organic-inorganic perovskites. Carrier lifetimes varied widely even between grains, and chemical treatments could improve lifetimes </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="6235" page="683" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa5333">683</jats:related-article> </jats:p>

<jats:title>Waste not, want not</jats:title> <jats:p> Natural gas often escapes or is deliberately burned at remote exploration sites because there is no economical way to transport it to markets. One route proposed for converting its main component, methane, into a more readily transported liquid is conversion to benzene over zeolites containing molybdenum (Mo). However, this method suffers from low conversion efficiency. Gao <jats:italic>et al.</jats:italic> identified the active Mo nanostructures as well as deactivated carbide species that form during this reaction. They were also able to recover and even enhance the zeolite catalytic activity after oxygen treatments. </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="6235" page="686" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa7048">686</jats:related-article> </jats:p>

<jats:title>Mimicking the oxygen evolution center</jats:title> <jats:p> Making a synthetic analog of plant photosynthesis is a key goal for exploiting solar energy and replacing fossil fuels. Zhang <jats:italic>et al.</jats:italic> synthesized a manganese-calcium cluster that looks and acts like the oxygen evolution center in photosystem II (see the Perspective by Sun). The mimic structurally resembles the biological complex, with the notable exception of bridging protein ligands and water-binding sites on a dangling Mn atom. Functionally, however, the cluster's metal center readily undergoes four redox transitions, which contribute to splitting water into oxygen. This and other synthetic mimics will pave the way for developing more efficient catalysts for artificial photosynthesis. </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="6235" page="690" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa6550">690</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6235" page="635" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa9094">635</jats:related-article> </jats:p>

<jats:title>Extra dividends from measles vaccine</jats:title> <jats:p> Vaccination against measles has many benefits, not only lifelong protection against this potentially serious virus. Mina <jats:italic>et al.</jats:italic> analyzed data collected since mass vaccination began in high-income countries when measles was common. Measles vaccination is associated with less mortality from other childhood infections. Measles is known to cause transient immunosuppression, but close inspection of the mortality data suggests that it disables immune memory for 2 to 3 years. Vaccination thus does more than safeguard children against measles; it also stops other infections taking advantage of measles-induced immune damage. </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="6235" page="694" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa3662">694</jats:related-article> </jats:p>

<jats:title>Building stable centromeres</jats:title> <jats:p> Each of our chromosomes has a single centromere, seen as a constriction during cell division, which is required for accurate chromosome segregation to daughter cells. Falk <jats:italic>et al.</jats:italic> show that the special histone protein known as CENP-A, which forms part of the nucleosomes at centromeres, makes the chromatin at these constrictions very stable and long-lived. This stability is conferred by a protein-binding partner, CENP-C, recruited to the centromere by the CENP-A histone. Binding of CENP-C to CENP-A–containing nucleosomes alters the behavior of the macromolecular centromere complex to help it maintain its identity </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="6235" page="699" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.1259308">699</jats:related-article> </jats:p>

<jats:title>Measles virus capsid at high resolution</jats:title> <jats:p> Viruses rely on their capsid proteins to package and protect their genome. For measles virus and other Mononegavirales family members, multiple capsid proteins together form a helical shell around the viral RNA (collectively called the nucleocapsid). Gutsche <jats:italic>et al.</jats:italic> now report a high-resolution cryoelectron microscopy structure of the measles virus nucleocapsid. The structure reveals how the nucleocapsid assembles and how the nucleo-protein and viral RNA interact, both of which may inform drug design </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="6235" page="704" related-article-type="in-this-issue" vol="348" xlink:href="10.1126/science.aaa5137">704</jats:related-article> </jats:p>