Catálogo de publicaciones - revistas

<jats:title>Hydrothermal processes on Enceladus</jats:title> <jats:p> Saturn's moon Enceladus has a subsurface ocean covered by a layer of ice. Some liquid escapes into space through cracks in the ice, which is the source of one of Saturn's rings. In October 2015, the Cassini spacecraft flew directly through the plume of escaping material and sampled its chemical composition. Waite <jats:italic>et al.</jats:italic> found that the plume contains molecular hydrogen, H <jats:sub>2</jats:sub> , a sign that the water in Enceladus' ocean is reacting with rocks through hydrothermal processes (see the Perspective by Seewald). This drives the ocean out of chemical equilibrium, in a similar way to water around Earth's hydrothermal vents, potentially providing a source of chemical energy. </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="6334" page="155" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aai8703">155</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6334" page="132" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aan0444">132</jats:related-article> </jats:p>

<jats:title>Adding a twist for enhanced performance</jats:title> <jats:p> The efficiency of organic light-emitting diodes (OLEDs) is fundamentally governed by the ratio of emissive singlet to dark triplet excitons that are formed from spin-polarized electron and hole currents within the material. Typically, this has set an upper limit of 25% internal quantum efficiency for OLEDs. Di <jats:italic>et al.</jats:italic> manipulated the ratio of spin states through a modification of process chemistry. They introduced a rotation of the molecular structure, which inverted the spin-state energetics and enhanced OLED performance. </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="6334" page="159" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aah4345">159</jats:related-article> </jats:p>

<jats:title>Crustal rock strength from outer space</jats:title> <jats:p> The response of crustal rock to stresses is challenging to estimate yet vital for determining risks from events such as earthquakes. Moore <jats:italic>et al.</jats:italic> take advantage of the recent <jats:italic>M</jats:italic> <jats:sub>w</jats:sub> 7.1 Kumamoto earthquake in Japan to determine the rheology of crustal rocks in the region. The observed inversion of the crustal strain rates demonstrates that certain areas have stiff rock and others (e.g., under the Aso volcanic complex) have much weaker rock. The results match up with expectations, which means that the method can successfully measure rock properties over a wide range of strength and large spatial and temporal scales. </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="6334" page="163" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aal3422">163</jats:related-article> </jats:p>

<jats:title>Transporter layers for greater stability</jats:title> <jats:p> Although perovskite solar cells (PSCs) can have power conversion efficiencies exceeding 20%, they can have limited stability under ultraviolet irradiation. This is in part because the mesoporous TiO <jats:sub>2</jats:sub> used as an electron-transporting layer can photocatalyze unwanted reactions in the perovskite layer. Shin <jats:italic>et al.</jats:italic> report a low-temperature colloidal method for depositing La-doped BaSnO <jats:sub>3</jats:sub> films as a replacement for TiO <jats:sub>2</jats:sub> to reduce such ultraviolet-induced damage. Solar cells retained over 90% of their initial performance after 1000 hours of full sun illumination. </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="6334" page="167" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aam6620">167</jats:related-article> </jats:p>

<jats:title>Stitching a belt out of carbon rings</jats:title> <jats:p> If you had a molecular scalpel, you could slice a carbon nanotube twice against the long axis to excise a loop of fused phenyl rings. Of course, knives don't come that small. Instead, Povie <jats:italic>et al.</jats:italic> succeeded in stitching together such a nanometer-scale belt in bottom-up fashion from molecular components, using consecutive Wittig reactions (see the Perspective by Siegel). The belt of 12 edge-sharing rings could ultimately be a first step toward more precisely controlled bottom-up syntheses of extended nanotubes. </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="6334" page="172" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aam8158">172</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6334" page="135" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aan0441">135</jats:related-article> </jats:p>

<jats:title>One antibody for all and all antibodies for one</jats:title> <jats:p> Antibodies against related flavi-viruses such as dengue (DENV) and West Nile (WNV) can cross-react with Zika virus (ZIKV) and could thereby increase disease severity. Bardina <jats:italic>et al.</jats:italic> tested whether DENV and WNV antibodies from humans, or even yellow fever vaccination, could enhance ZIKV infection. In a mouse model, low titers of DENV and WNV antibodies enhanced ZIKV viremia, especially in the spinal cord and testes, whereas high titers remained protective. Generally, WNV antibodies were less disease-enhancing than DENV antibodies, and, in macaques, yellow fever vaccination had very little effect. </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="6334" page="175" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aal4365">175</jats:related-article> </jats:p>

<jats:title>Quantifying hunting-induced defaunation</jats:title> <jats:p> As the human population grows and increasingly encroaches on remaining wildlife habitat, hunting threatens many species. Benítez-López <jats:italic>et al.</jats:italic> conducted a large-scale meta-analysis of hunting trends and impacts across the tropics (see the Perspective by Brashares and Gaynor). Bird and mammal populations were considerably lower in areas where hunting occurred. Although commercial hunting and proximity to roads and urban centers were the most damaging factors, all hunting had worrying impacts, even in protected areas. Protection and alternative approaches for sustainable subsistence hunting must be implemented soon if we are to prevent further, rapid defaunation. </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="6334" page="180" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aaj1891">180</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6334" page="136" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aan0499">136</jats:related-article> </jats:p>

<jats:title>Machines learn what people know implicitly</jats:title> <jats:p> AlphaGo has demonstrated that a machine can learn how to do things that people spend many years of concentrated study learning, and it can rapidly learn how to do them better than any human can. Caliskan <jats:italic>et al.</jats:italic> now show that machines can learn word associations from written texts and that these associations mirror those learned by humans, as measured by the Implicit Association Test (IAT) (see the Perspective by Greenwald). Why does this matter? Because the IAT has predictive value in uncovering the association between concepts, such as pleasantness and flowers or unpleasantness and insects. It can also tease out attitudes and beliefs—for example, associations between female names and family or male names and career. Such biases may not be expressed explicitly, yet they can prove influential in behavior. </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="6334" page="183" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aal4230">183</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6334" page="133" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aan0649">133</jats:related-article> </jats:p>