Catálogo de publicaciones - revistas

<jats:title>Helping copper glow</jats:title> <jats:p> Copper's abundance makes the metal an appealing candidate for luminescence applications. However, many copper complexes tend to decay nonradiatively after photoexcitation. A recently described exception involves a two-coordinate complex that sandwiches the metal between an amide ligand and a carbene ligand. Hamze <jats:italic>et al.</jats:italic> thoroughly explored this motif and measured a nearly perfect luminescence efficiency. They used this property to produce a prototype blue organic light-emitting diode. The photodynamics appeared largely ligand-centered, with the excited state attributed to copper-facilitated charge transfer from amide to carbene. </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="6427" page="601" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aav2865">601</jats:related-article> </jats:p>

<jats:title>Zika dynamics in South America</jats:title> <jats:p> The infection dynamics of Zika virus (ZIKV) are difficult to characterize. Many ZIKV infections are asymptomatic, and the clinical presentation of ZIKV is nonspecific. Rodriguez-Barraquer <jats:italic>et al.</jats:italic> took advantage of a long-term health study under way in Salvador, Brazil, the epicenter of the recent outbreak in the Americas. They used multiple serological assays, from before and after the emergence of ZIKV in October 2015, to distinguish ZIKV immune responses from those against Dengue virus (DENV). About 73% of the population was attacked by ZIKV. The presence of preexisting antibodies to DENV was associated with less risk of ZIKV infection and fewer symptoms. </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="6427" page="607" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aav6618">607</jats:related-article> </jats:p>

<jats:title>Delivering fragile drugs to the gut</jats:title> <jats:p> Oral delivery is the simplest and least invasive way to deliver many pharmaceuticals, but many drugs and medications, including insulin, cannot survive passage through the stomach or the gastrointestinal tract. Abramson <jats:italic>et al.</jats:italic> developed an ingestible delivery vehicle that could self-reorient from any starting position so as to attach to the gastric wall. Encapsulation of a spring in a sugar casing allowed for triggered actuation for the delivery of biomolecules. The approach successfully provided active insulin delivery in pigs. </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="6427" page="611" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aau2277">611</jats:related-article> </jats:p>

<jats:title>Shaking up reaction-site selectivity</jats:title> <jats:p> It seems intuitive that putting vibrational energy into a chemical bond ought to promote selective cleavage of that bond. In fact, the relation of vibrational excitation to reactivity has generally proven subtler and more complex. Thomas <jats:italic>et al.</jats:italic> studied how strong coupling of specific vibrational modes to an optical cavity might influence a molecule with two competing reactive sites. The molecule had two silicon centers that could react with fluoride by respective cleavage of a Si–C or Si–O bond. Exciting the vibrations at either center slowed down the overall reaction while favoring otherwise disfavored Si–O cleavage. </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="6427" page="615" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aau7742">615</jats:related-article> </jats:p>

<jats:title>A cloth that adapts to the heat</jats:title> <jats:p> Textiles trap infrared radiation, which helps keep us warm in cold weather. Of course, in hot weather, this is less desirable. Zhang <jats:italic>et al.</jats:italic> constructed an infrared-adaptive textile composed of polymer fibers coated with carbon nanotubes. The yarn itself expanded and collapsed based on heat and humidity, which changed the spacing of the fibers. Wider fiber spacing allowed the textile to breathe but also altered the infrared emissivity of the textile. This allowed for better heat exchange under hot and wet conditions. The self-adjusting emissivity of the textile could help toward wearable thermal-management attire. </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="6427" page="619" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aau1217">619</jats:related-article> </jats:p>

<jats:title>Stability through symmetry</jats:title> <jats:p> A common route to get more light out of a laser system is to couple multiple lasers to form an array. However, instabilities owing to cross-talk and interference between different modes of individual cavities is generally detrimental to performance and could ultimately be damaging to the laser cavities. Hokmabadi <jats:italic>et al.</jats:italic> applied notions derived from supersymmetry, a theory developed in high-energy physics to describe the make-up and properties of particles, to design a stable array of semiconductor lasers (see the Perspective by Kottos). Based on symmetry arguments, the method is scalable and could provide a practical platform to design and develop complex photonic 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="6427" page="623" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aav5103">623</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6427" page="586" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aaw1203">586</jats:related-article> </jats:p>

<jats:title>Advantages of adding just enough alkalis</jats:title> <jats:p> For organic-inorganic hybrid solar cells, addition of cesium or rubidium cations can improve power conversion efficiency. Correa-Baena <jats:italic>et al.</jats:italic> used nanoscale x-ray fluorescence imaging to show that the addition of metal cations at low concentrations homogenized the distribution of bromide and iodide anions and also increased charge-carrier lifetimes. However, at high concentrations, aggregation and cluster formation led to increased charge recombination. </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="6427" page="627" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aah5065">627</jats:related-article> </jats:p>

<jats:title>Timing matters</jats:title> <jats:p> How a species responds to rapid climate change is complicated. Paniw <jats:italic>et al.</jats:italic> used long-term data on the Kalahari meerkat, an arid specialist, to explore how predicted changes might affect population persistence over time. Warming and rainfall changes in one part of the year had a negative impact on survival and persistence, whereas similar changes during another part of the year had the opposite effect. Understanding such variability will be essential as we attempt to understand the broader influence of climate change. </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="6427" page="631" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aau5905">631</jats:related-article> </jats:p>

<jats:title>Abstract concepts in the primate brain</jats:title> <jats:p> Do primates have neurons that encode the conceptual similarity between spaces that differ by their appearance but correspond to the same mental schema? Baraduc <jats:italic>et al.</jats:italic> recorded from monkey hippocampal neurons while the animals explored both a familiar environment and a novel virtual environment that shared the same general structure as the familiar environment but displayed never-before-seen landmarks. About one-third of hippocampal cells showed significantly correlated firing for both familiar and novel landscapes. These correlations hinged on space or task elements, rather than on immediate visual information. The functional features of these cells are analogous to human concept cells, which represent the meaning of a specific stimulus rather than its apparent visual properties. </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="6427" page="635" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aav5404">635</jats:related-article> </jats:p>