Catálogo de publicaciones - revistas

<jats:title>Identifying live radio scattering events</jats:title> <jats:p> Radio emissions from distant quasars are occasionally modified for a few weeks by foreground interstellar plasma, in an extreme scattering event (ESE). Understanding this process has been difficult, because existing techniques do not allow events to be identified fast enough for follow-up before they finish. Bannister <jats:italic>et al.</jats:italic> developed a radio survey technique that allows ESEs to be identified in real time. After finding their first live ESE, they followed it up with additional radio and optical telescopes. The results constrain the size and density of the plasma and rule out one popular model of ESEs. </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="6271" page="354" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aac7673">354</jats:related-article> </jats:p>

<jats:title>Timing on a chip</jats:title> <jats:p> Laser-induced optical frequency combs allow precision measurements and affect a broad range of technologies. Brasch <jats:italic>et al.</jats:italic> generated optical frequency combs on an optical chip (see the Perspective by Akhmediev and Devine). They induced an optical soliton, or optical bullet, and propagated it in an engineered microcavity waveguide. The emitted output light formed a coherent comb of frequencies spanning two-thirds of an octave. Such an on-chip demonstration bodes well for miniaturization of metrological technology and its adaption for widespread application. </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="6271" page="357" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad4811">357</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6271" page="340" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad8694">340</jats:related-article> </jats:p>

<jats:title>The right kind of dopant</jats:title> <jats:p> The oxygen reduction reaction is an important step in fuel cells and other electrochemical processes but is still largely dependent on precious metal-containing catalysts. Recently explored alternatives include carbon materials that are doped with different, preferably non-precious metal, atoms. Guo <jats:italic>et al.</jats:italic> studied model graphite catalysts to try to understand the role of nitrogen doping and to elucidate the active catalytic sites. A nitrogen atom bound to two carbons formed an active catalyst site with an activity rivaling that of N-doped graphene catalysts. </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="6271" page="361" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad0832">361</jats:related-article> </jats:p>

<jats:title>Weaving organic threads</jats:title> <jats:p> Woven fabrics are inherently flexible. Liu <jats:italic>et al.</jats:italic> created a molecular fabric analog using metal-organic frameworks (see the Perspective by Gutierrez-Puebla). Phenanthroline ligands on a copper metal complex directed the addition of organic linkers via imine bonds to create helical organic threads with woven texture. Removing the copper allowed the strands to slide against each other and increased the elasticity of the material 10-fold. </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="6271" page="365" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad4011">365</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6271" page="336" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad9671">336</jats:related-article> </jats:p>

<jats:title>A different way to put triplets in play</jats:title> <jats:p> Most molecules adopt a singlet spin configuration: All their electrons are arranged in pairs. Unpaired triplet states engage in a variety of useful reactions but are hard to produce. Quantum mechanics dictates that photo-excitation from singlet to triplet states is inefficient. Instead, chemists rely on sensitizers, which populate the triplet states of their neighbors through energy transfer after absorbing light themselves. Mongin <jats:italic>et al.</jats:italic> now show that certain nanoparticles can act as triplet sensitizers. </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="6271" page="369" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad6378">369</jats:related-article> </jats:p>