Catálogo de publicaciones - revistas

<jats:title>Sequentially snipping off fluorines</jats:title> <jats:p> It is often useful in pharmaceutical or agrochemical research to modify the properties of carbon compounds by appending one or more fluorine atoms. However, the methods used to prepare mono-, di-, or trifluorocarbon centers tend to differ from each other in inconvenient ways. Yu <jats:italic>et al.</jats:italic> developed a radical reaction that can successively remove one or two fluorine atoms from trifluoromethyl groups adjacent to amides or esters. The mechanism relies on a spin-center shift after attack at the carbonyl oxygen by a boryl radical. </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="6535" page="1232" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abg0781">1232</jats:related-article> </jats:p>

<jats:title>Topology in the open</jats:title> <jats:p> Controlling the topology of a system provides a route to develop devices that are robust against defects. Whereas earlier developments of topological band theory focused on Hermitian (closed) systems, recent efforts have been toward non-Hermitian (open) systems. K. Wang <jats:italic>et al.</jats:italic> report on the measurement and control of topologically nontrivial windings of a non-Hermitian energy band. By implementing non-Hermitian lattice Hamiltonians along a frequency synthetic dimension formed by optical frequency modes in a modulated ring-resonator, they directly visualized the nontrivial topological band winding and showed that the winding can be controlled. Such control provides a route for the experimental synthesis, characterization, and control of topologically nontrivial phases in open physical 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="6535" page="1240" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abf6568">1240</jats:related-article> </jats:p>

<jats:title>Genomic sleuthing spots early divergence</jats:title> <jats:p> After fertilization, the human zygote divides into two cells. Fasching <jats:italic>et al.</jats:italic> used genomic analysis from cellular samples taken much later in development to back-calculate the cell division trees that went before. Although the first cell division in human development looks symmetrical from the outside, the fates followed by daughter cells from each of those first two blastomeres are anything but the same. As much as 90% of blood cells are derived from just one of the first two blastomeres. </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="6535" page="1245" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abe0981">1245</jats:related-article> </jats:p>

<jats:title>Mutations provide an enduring record</jats:title> <jats:p> Somatic mutations pepper our cells with change, but because they are not in the germline, they do not propagate to the next generation. Bizzotto <jats:italic>et al.</jats:italic> leveraged data on the distribution of somatic mutations in adults to take a backward look at the earliest moments of human development. Calculation of cellular lineages on the basis of shared somatic mutations shows the number of cells from which the body will develop when the human embryo gastrulates. The lineage for forebrain cells is identifiable, as are the asymmetrical fates spun out of many of the gastrula 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="6535" page="1249" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abe1544">1249</jats:related-article> </jats:p>

<jats:title>A soaring shark</jats:title> <jats:p> Modern sharks occupy marine ecosystems across the world but display little morphological diversity, being mostly streamlined predators. Vullo <jats:italic>et al.</jats:italic> describe a new species of shark from the late Cretaceous that shows that the lack of current variation is not due to limited morphological “exploration” in the past. Specifically, <jats:italic>Aquilolamna milarcae</jats:italic> displays many features similar to modern manta rays, notably long, slender fins and a mouth seemingly adapted to filter feeding, suggesting that it was planktivorous. This finding indicates both that elasmobranchs evolutionarily experimented with other forms and that the planktivorous “soarers” emerged in this group at least 30 million years earlier than previously recognized. </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="6535" page="1253" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abc1490">1253</jats:related-article> </jats:p>

<jats:title>Tuning the interactions</jats:title> <jats:p> Elucidating the nature of the superconducting state in magic-angle twisted bilayer graphene (MATBG) has proven tricky. To study the role of electron-electron correlations in this state, Liu <jats:italic>et al.</jats:italic> placed another graphene bilayer, this one having a conventional arrangement of the graphene sheets, in the immediate vicinity of a sample of MATBG. By varying the carrier density in the conventional bilayer, the researchers controlled the strength of interactions in MATBG. Weakening the interactions strengthened superconductivity, consistent with scenarios in which the electron-phonon coupling competes against Coulomb interactions to stabilize the superconducting phase. </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="6535" page="1261" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abb8754">1261</jats:related-article> </jats:p>

<jats:title>Identifying PAHs in space</jats:title> <jats:p> Midinfrared spectroscopy has shown that polycyclic aromatic hydrocarbons (PAHs) are abundant in many astronomical objects, but this technique cannot determine which specific PAH molecules are present. Radio astronomy could provide individual identifications if the molecule is sufficiently abundant and has a large dipole moment, but PAHs are expected to produce large numbers of very weak lines. McGuire <jats:italic>et al.</jats:italic> performed a stacking and matched filter analysis to search for PAHs in radio observations of TMC-1, located within the interstellar Taurus Molecular Cloud. They identified emission from two isomers of the small PAH cyanonapthalene, two fused benzene rings with a CN group attached. </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="6535" page="1265" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abb7535">1265</jats:related-article> </jats:p>

<jats:title>Smoke alarm</jats:title> <jats:p>Intense, widespread bushfires in Australia injected huge amounts of smoke into the stratosphere in 2020. Hirsch and Koren found that this smoke caused record-breaking levels of aerosols over the Southern Hemisphere, as much as that from a moderate volcanic eruption. The severity was caused by a combination of the vigor of the fires and their location at a latitude with a shallow tropopause and within the midlatitude cyclones belt. This aerosol increase caused considerable cooling over oceanic cloud-free areas.</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="6535" page="1269" related-article-type="in-this-issue" vol="371" xlink:href="10.1126/science.abe1415">1269</jats:related-article> </jats:p>