Catálogo de publicaciones - revistas

<jats:title>Methane borylation in a cyclohexane sea</jats:title> <jats:p> Although methane combusts readily at high temperatures, it is generally the hardest hydrocarbon to transform under gentler conditions, owing to its particularly strong C-H bonds. Cook <jats:italic>et al.</jats:italic> now show that soluble rhodium, iridium, and ruthenium catalysts can slice through these C-H bonds to add boron substituents to methane at 150°C. Smith <jats:italic>et al.</jats:italic> report the iridium-catalyzed reaction using phosphine ligands to enhance activity. Both studies were performed in cyclohexane solvent, revealing a remarkable selective preference for the methane reaction over functionalization of the cyclic hydrocarbon. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue pp. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6280" page="1421" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad9289">1421</jats:related-article> and <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6280" page="1424" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad9730">1424</jats:related-article> </jats:p>

<jats:p> The 11-year solar magnetic cycle shows a high degree of coherence in spite of the turbulent nature of the solar convection zone. It has been found in recent high-resolution magnetohydrodynamics simulations that the maintenance of a large-scale coherent magnetic field is difficult with small viscosity and magnetic diffusivity ( <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>≲</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>12</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> </jats:inline-formula> square centimenters per second). We reproduced previous findings that indicate a reduction of the energy in the large-scale magnetic field for lower diffusivities and demonstrate the recovery of the global-scale magnetic field using unprecedentedly high resolution. We found an efficient small-scale dynamo that suppresses small-scale flows, which mimics the properties of large diffusivity. As a result, the global-scale magnetic field is maintained even in the regime of small diffusivities—that is, large Reynolds numbers. </jats:p>

<jats:title>Perovskite solar cells recycle photons</jats:title> <jats:p> Inorganic-organic perovskite solar cells are very efficient in part because the charge carriers exhibit very long path lengths. Pazos-Outón <jats:italic>et al.</jats:italic> show that photon recycling, as seen previously in highly efficient gallium arsenide solar cells, contributes to this effect (see the Perspective by Yablonovitch). In most solar cells, the recombination of photogenerated charge carriers (electrons and holes) wastes all of the energy. In these lead tri-iodide cells, recombination emits a photon that can be reabsorbed and create more charge carriers. </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="6280" page="1430" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf1168">1430</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6280" page="1401" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf4603">1401</jats:related-article> </jats:p>

<jats:title>Another social science looks at itself</jats:title> <jats:p> Experimental economists have joined the reproducibility discussion by replicating selected published experiments from two top-tier journals in economics. Camerer <jats:italic>et al.</jats:italic> found that two-thirds of the 18 studies examined yielded replicable estimates of effect size and direction. This proportion is somewhat lower than unaffiliated experts were willing to bet in an associated prediction market, but roughly in line with expectations from sample sizes and P values. </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="6280" page="1433" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf0918">1433</jats:related-article> </jats:p>

<jats:title>Variability for a day or a season</jats:title><jats:p>Species that experience larger seasonal climatic fluctuations are likely to be more physiologically flexible and thus likely to occur across a wider elevational range. Daily changes in temperature are also common but have rarely been considered. Chan<jats:italic>et al.</jats:italic>used a global data set of vertebrates to look at how these two different sets of variation affect a species' elevational distribution (see the Perspective by Perez<jats:italic>et al.</jats:italic>). Unexpectedly, larger daily fluctuations were associated with smaller elevational distributions. Thus, specialists are favored where daily fluctuations are dominant, whereas generalists are favored where seasonal fluctuations are the main climate influence.</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="6280" page="1437" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aab4119">1437</jats:related-article>; see also p.<jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6280" page="1392" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf3343">1392</jats:related-article></jats:p>

<jats:title>Coding what is known and what is new</jats:title><jats:p>Do neural activity patterns during sleep reflect the replay of a novel experience or an invariant preexisting dynamic? Grosmark and Buzsáki observed that both familiar and novel aspects of learned information are replayed during synchronous bursts of activity in the hippocampus. Familiarity was encoded by fast-firing less-modifiable neurons that showed rate and sequence correlations that persisted into postlearning sleep. The novel features of an experience were represented by a different set of slowly firing and highly plastic cells.</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="6280" page="1440" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad1935">1440</jats:related-article></jats:p>

<jats:title>Tracking neuronal transcriptional programs</jats:title> <jats:p> Early in brain development, cortical neurons are born near the ventricles, then migrate to their functional destinations. Telley <jats:italic>et al.</jats:italic> used a fluorescent labeling technique to see what transcripts characterize these earliest stages of neural development. Waves of transcriptional programs are initiated, then passed by as the neuron progresses from proliferative to migratory and finally to connectivity phases. </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="6280" page="1443" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad8361">1443</jats:related-article> </jats:p>

<jats:title>Organic contributions to cloud theory</jats:title> <jats:p> Current theories about the formation of cloud droplets from aerosol particles containing organic components assume that the organic molecules are distributed throughout the droplet. Ruehl <jats:italic>et al.</jats:italic> show that this assumption is not always correct (see the Perspective by Noziere). During droplet nucleation, droplet diameters were 50% larger than predicted by the standard model. This suggests that the organic particles reside in a surface layer rather than in the bulk of the droplet. Models that neglect organic surface activity will thus underestimate how well organic-rich particles seed clouds. </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="6280" page="1447" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad4889">1447</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6280" page="1396" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf3253">1396</jats:related-article> </jats:p>

<jats:title>Variation and transcription factor binding</jats:title> <jats:p> Little is known about the phenotypic and functional effects of genetic variants that result in amino acid changes within functional proteins. Barrera <jats:italic>et al.</jats:italic> investigated whether amino acid variants changed the DNA binding specificity or affinity of transcription factors. Predictive analyses identified changes in the proteins, and protein-binding microarrays verified changes that affected transcription factor function, including those associated with disease. Thus, within-human protein sequence variation can affect transcriptional regulatory networks, which, depending on the genetic variant, may confer robustness and buffer against amino acid changes and could explain phenotypic variation among individuals. </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="6280" page="1450" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad2257">1450</jats:related-article> </jats:p>

<jats:title>The spread of bad neighborhoods</jats:title> <jats:p> Our genomes have complex three-dimensional (3D) arrangements that partition and regulate gene expression. Cancer cells frequently have their genomes grossly rearranged, disturbing this intricate 3D organization. Hnisz <jats:italic>et al.</jats:italic> show that the disruption of these 3D neighborhoods can bring oncogenes under the control of regulatory elements normally kept separate from them (see the Perspective by Wala and Beroukim). These novel juxtapositions can result in the inappropriate activation of oncogenes. </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="6280" page="1454" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad9024">1454</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6280" page="1398" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf5542">1398</jats:related-article> </jats:p>