Catálogo de publicaciones - revistas

<jats:title>Explosive origin of a binary neutron star</jats:title> <jats:p> Some types of core-collapse supernovae are known to produce a neutron star (NS). A binary NS merger was recently detected from its gravitational wave emission, but it is unclear how such a tight binary system can be formed. De <jats:italic>et al.</jats:italic> discovered a core-collapse supernova with unusual properties, including the removal of the outer layers of the star before the explosion. They interpret this as the second supernova in an interacting binary system that already contains one NS. Because the explosion probably produced a second NS (rather than a black hole) in a tight orbit, it could be an example of how binary NS systems form. </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="6411" page="201" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aas8693">201</jats:related-article> </jats:p>

<jats:title> Pathologizing <jats:italic>Staphylococcus</jats:italic> , fast </jats:title> <jats:p> Bacteriophages are the main vehicle for gene swapping in bacteria, notoriously of pathogenicity islands and antibiotic resistance genes. Chen <jats:italic>et al.</jats:italic> noticed that the <jats:italic>Staphylococcus aureus</jats:italic> prophages do not excise from their host's genome until very late in their life cycles (see the Perspective by Davidson). Thus, the phage DNA is amplified while embedded in the bacterial chromosome. The resulting concatemers are processively packed into virus capsules while still integrated in the host chromosome. Each virion is only set loose when the capsule has reached physical capacity—a process called “headful” packaging. In situ amplification maximizes viral replication, and the headful mechanism means adjacent bacterial-host DNA also gets grabbed to fill the capsule. This process ensures that host genes are transmitted along with the phage. </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="6411" page="207" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aat5867">207</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6411" page="152" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aav1723">152</jats:related-article> </jats:p>

<jats:title>The twisted carbon nanotube story</jats:title> <jats:p> Despite progress in growing single-walled carbon nanotubes of specific size and chirality, the factors that control their growth are still not fully known. Magnin <jats:italic>et al.</jats:italic> developed a thermodynamic model for the growth of single-walled carbon nanotubes. The model explains the origin of nanotube chirality in terms of the configurational entropy of the nanotube edge. The model should be useful in helping to guide nanotube growth parameters to enhance selectivity. </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="6411" page="212" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aat6228">212</jats:related-article> </jats:p>

<jats:title>An acid inaccessible to aldol products</jats:title> <jats:p> The aldol reaction is a venerable and widely applicable method for making carbon-carbon bonds. Ironically, it is most challenged by the simplest substrates. The trouble is that the product looks a lot like one of the reactants, and so it can latch onto the coupling partner instead. Schreyer <jats:italic>et al.</jats:italic> report that a bulky phosphorus-based acid catalyst alleviates this problem. The acidic site is buried in a pocket that is too small to activate the product for further reaction. The chiral geometry of the catalyst also induces high enantioselectivity. </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="6411" page="216" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aau0817">216</jats:related-article> </jats:p>

<jats:title>Simple routes to self-healing</jats:title> <jats:p> Biology provides many routes for self-healing or repair, but this trait is hard to endow into engineering materials. Although self-repair has been demonstrated for some polymers, it usually required specialized monomers. Urban <jats:italic>et al.</jats:italic> demonstrate that for a very narrow range of compositions, simple vinyl polymers based on methyl methacrylate and <jats:italic>n</jats:italic> -butyl acrylate show repeatable self-healing properties (see the Perspective by Sumerlin). A key characteristic of this system is that it relies on van der Waals interactions rather than the reformation of hydrogen or covalent bonds for repair. </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="6411" page="220" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aat2975">220</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6411" page="150" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aau6453">150</jats:related-article> </jats:p>

<jats:title>Iodine smooths the way to ketyl radicals</jats:title> <jats:p> Chemists typically transform carbonyl compounds through polar two-electron reactions. It is also possible to pursue radical coupling strategies by adding just one electron to form a ketyl group. However, the strong reductant supplying that electron often limits the reaction's versatility. Wang <jats:italic>et al.</jats:italic> report a mild means of forming ketyls by first adding acetyl iodides across the C=O bond (see the Perspective by Blackburn and Roizen). A photoactivated manganese catalyst then temporarily pulls the iodine away, leaving a ketyl to couple with alkynes. The iodine then returns to one of the alkyne's carbons, stabilizing the product but remaining poised for further transformations. </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="6411" page="225" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aau1777">225</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6411" page="157" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aav0574">157</jats:related-article> </jats:p>