Catálogo de publicaciones - revistas

<jats:title>Heterocycles meet and marry on phosphorus</jats:title> <jats:p> Metals such as palladium are routinely used to link together carbon rings in pharmaceutical synthesis. However, the presence of nitrogen in both rings can trip up this process. Hilton <jats:italic>et al.</jats:italic> report a versatile alternative process in which phosphorus takes the place of the metal. The phosphorus binds successively to both rings at the sites opposite the nitrogen, and treatment with acidic ethanol then pushes them off, bound to each other. Theory implicates a five-coordinate phosphorus intermediate that kinetically favors coupling of the two nitrogen-bearing rings over reactions of the other all-carbon substituents. </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="6416" page="799" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aas8961">799</jats:related-article> </jats:p>

<jats:title>Patterned fiber formation</jats:title> <jats:p> The ability of liquid crystalline materials to order spontaneously has driven many innovations, from display technologies to extremely tough polymer fibers. Cheng <jats:italic>et al.</jats:italic> exploited this preponderance toward long-range ordering to direct the growth of nonliquid crystalline polymers into sheets of highly ordered fibers. Small changes to the processing conditions could be used to tweak the arrangement of the liquid crystals to generate a wide range of polymer mats or sheets for potential use in sensing or filtration applications. </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="6416" page="804" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aar8449">804</jats:related-article> </jats:p>

<jats:title>Chemically reversible hydrogels</jats:title> <jats:p> The dynamic reorganization of some cellular biopolymers in response to signals has inspired efforts to create artificial materials with similar properties. Freeman <jats:italic>et al.</jats:italic> created hydrogels based on peptide amphiphiles that can bear DNA strands that assemble into superstructures and that disassemble in response to chemical triggers. The addition of DNA conjugates induced transitions from micelles to fibers and bundles of fibers. The resulting hydrogels were used as an extracellular matrix mimic for cultured cells. Switching the hydrogel between states also switched astrocytes between their reactive and naïve phenotypes. </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="6416" page="808" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aat6141">808</jats:related-article> </jats:p>

<jats:title>Light-powered cell factories</jats:title> <jats:p> Bacteria and fungi are used industrially to produce commodity fine chemicals at vast scale. Sugars are an economical feedstock, but many of the desired products require enzymatic reduction, meaning that some of the sugar must be diverted to regenerate the cellular reductant NADPH (reduced form of nicotinamide adenine dinucleotide phosphate). Guo <jats:italic>et al.</jats:italic> show that electrons from light-sensitive nanoparticles can drive reduction of cellular NADPH in yeast, which can then be used for reductive biosynthetic reactions. This system can reduce diversion of carbon to NADPH regeneration and should be compatible with many existing engineered strains of yeast. </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="6416" page="813" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aat9777">813</jats:related-article> </jats:p>

<jats:title>Wafer-scale hBN crystalline films</jats:title> <jats:p> Although wafer-scale polycrystalline films of insulating hexagonal boron nitride (hBN) can be grown, the grain boundaries can cause both scattering or pinning of charge carriers in adjacent conducting layers that impair device performance. Lee <jats:italic>et al.</jats:italic> grew wafer-scale single-crystal films of hBN by feeding the precursors into molten gold films on tungsten substrates. The low solubility of boron and nitrogen in gold caused micrometer-scale grains of hBN to form that coalesced into single crystals. These films in turn supported the growth of epitaxial wafer-scale films of graphene and tungsten disulfide. </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="6416" page="817" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aau2132">817</jats:related-article> </jats:p>

<jats:title>Physics and chemistry in concert</jats:title> <jats:p> Shining a short, intense light pulse on a material can cause a transition in both its atomic and electronic structures. The dynamics of the electronic structure in such transitions can be monitored using, for example, time-resolved photoemission spectroscopy. Nicholson <jats:italic>et al.</jats:italic> observed a photoinduced metal-insulator transition in indium nanowires on a silicon surface. They monitored both the physics and the chemistry of the system after the initial photoexcitation and correlated the closing of the electronic bandgap with the rearrangement of chemical bonds. The results showcase the wealth of information that time-resolved tools can reveal about the dynamics of complex 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="6416" page="821" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aar4183">821</jats:related-article> </jats:p>

<jats:title>The science of art advancement</jats:title> <jats:p> Art appreciation is highly subjective. Fraiberger <jats:italic>et al.</jats:italic> used an extensive record of exhibition and auction data to study and model the career trajectory of individual artists relative to a network of galleries and museums. They observed a lock-in effect among highly reputed artists who started their career in high-prestige institutions and a long struggle for access to elite institutions among those who started their career at the network periphery. </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="6416" page="825" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aau7224">825</jats:related-article> </jats:p>

<jats:title>Innovating to be nondisruptive</jats:title> <jats:p> Insights into the architecture and stoichiometry of membrane complexes have grown with advances in cryo–electron microscopy and native mass spectroscopy. However, most of these studies are not in the context of native membrane. Chorev <jats:italic>et al.</jats:italic> released intact membrane complexes directly from native lipid membrane vesicles into a mass spectrometer. They analyzed components of the <jats:italic>Escherichia coli</jats:italic> inner and outer membranes and the bovine mitochondrial inner membrane. For several identified complexes, they found a stoichiometry that differs from published results and, in some cases, confirmed interactions that could not be characterized structurally. </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="6416" page="829" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aau0976">829</jats:related-article> </jats:p>

<jats:title>DNA binding as an anti-inflammatory</jats:title> <jats:p> Mice that lack the gene encoding 8-oxoguanine DNA glycosylase 1 (OGG1) show resistance to inflammation. This enzyme binds to sites of oxidative DNA damage and initiates DNA base excision repair. Visnes <jats:italic>et al.</jats:italic> developed a small-molecule drug that acts as a potent and selective active-site inhibitor that stops OGG1 from recognizing its DNA substrate (see the Perspective by Samson). The drug inhibited DNA repair and modified OGG1 chromatin dynamics, which resulted in the inhibition of proinflammatory pathway genes. The drug was well tolerated by mice and suppressed lipopolysaccharide- and tumor necrosis factor–α–mediated neutrophilic inflammation in the lungs. </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="6416" page="834" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aar8048">834</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6416" page="748" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aav4744">748</jats:related-article> </jats:p>

<jats:title>A programmable type of CRISPR system</jats:title> <jats:p> CRISPR-Cas9 systems have been causing a revolution in biology. Harrington <jats:italic>et al.</jats:italic> describe the discovery and technological implementation of an additional type of CRISPR system based on an extracompact effector protein, Cas14. Metagenomics data, particularly from uncultivated samples, uncovered the CRISPR-Cas14 systems containing all the components necessary for adaptive immunity in prokaryotes. At half the size of class 2 CRISPR effectors, Cas14 appears to target single-stranded DNA without class 2 sequence restrictions. By leveraging this activity, a fast and high-fidelity nucleic acid detection system enabled detection of single-nucleotide polymorphisms. </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="6416" page="839" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aav4294">839</jats:related-article> </jats:p>