Catálogo de publicaciones - revistas

<jats:title>Easing water apart</jats:title> <jats:p> Traditional setups for splitting water into hydrogen and oxygen operate either in acid or in base. A bipolar membrane can potentially enhance efficiency by bridging acidic hydrogen evolution to basic oxygen evolution. Oener <jats:italic>et al.</jats:italic> undertook a systematic study of how catalysts paired with such a membrane might accelerate the preliminary step of water dissociation into protons and hydroxide ions. Using insights from this study for optimal catalyst integration, they were able to substantially lower the overpotential of a bipolar membrane electrolyzer. </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="6507" page="1099" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.aaz1487">1099</jats:related-article> </jats:p>

<jats:title>Finding the source of their durability</jats:title> <jats:p> Many high-strength materials can fail after repeated exposure to subcritical loading; therefore, understanding the causes of fatigue is key to extending the longevity of the material in use. Bai <jats:italic>et al.</jats:italic> used chemical vapor deposition to produce centimeter-long carbon nanotubes. They then decorated these nanotubes with titanium dioxide nanoparticles for optical visualization and studied them using noncontact acoustic resonance tests. The authors determined that fatigue lifetime is dependent on the formation of the first defects on straining and is higher at lower temperatures. </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="6507" page="1104" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.aay5220">1104</jats:related-article> </jats:p>

<jats:title>From cough to splutter</jats:title> <jats:p> In epidemiology, serial intervals are measured from when one infected person starts to show symptoms to when the next person infected becomes symptomatic. For any specific infection, the serial interval is assumed to be a fixed characteristic. Using valuable transmission pair data for coronavirus disease (COVID-19) in mainland China, Ali <jats:italic>et al.</jats:italic> noticed that the average serial interval changed as nonpharmaceutical interventions were introduced. In mid-January 2020, serial intervals were on average 7.8 days, whereas in early February 2020, they decreased to an average of 2.2 days. The more quickly infected persons were identified and isolated, the shorter the serial interval became and the fewer the opportunities for virus transmission. The change in serial interval may not only measure the effectiveness of infection control interventions but may also indicate rising population immunity. </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="6507" page="1106" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abc9004">1106</jats:related-article> </jats:p>

<jats:title>An unexpected source of Earth's water</jats:title> <jats:p> The abundances of Earth's chemical elements and their isotopic ratios can indicate which materials formed Earth. Enstatite chondrite (EC) meteorites provide a good isotopic match for many elements but are expected to contain no water because they formed in the hot inner Solar System. This would require Earth's water to be from a different source, such as comets. Piani <jats:italic>et al.</jats:italic> measured hydrogen contents and deuterium/hydrogen ratios (D/H) in 13 EC meteorites (see the Perspective by Peslier). They found far more hydrogen than is commonly assumed, with D/H close to that of Earth's mantle. Combining these data with cosmochemical models, they show that most of Earth's water could have formed from hydrogen delivered by EC meteorites. </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="6507" page="1110" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.aba1948">1110</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6507" page="1058" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abc1338">1058</jats:related-article> </jats:p>

<jats:title>Expanding the kinetic resolution purview</jats:title> <jats:p> Dynamic kinetic resolution (DKR) is a powerful method to transform a pair of mirror-image reactants into just one of the two possible mirror-image products. The key is to find a means of rapidly interconverting the reactants while one of them is being more efficiently funneled to product. DeHovitz <jats:italic>et al.</jats:italic> report cooperative application of organocatalysis, photoredox catalysis, and enzymatic catalysis to achieve DKR of β-substituted ketones into chiral alcohols. This β position has typically been considered too configurationally stable for a DKR approach. </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="6507" page="1113" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abc9909">1113</jats:related-article> </jats:p>

<jats:title>A common theme in antibody responses</jats:title> <jats:p> In the fight against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), antibodies are a key tool, both as potential therapeutics and to guide vaccine development. Yuan <jats:italic>et al.</jats:italic> focused on finding shared antibody responses, in which multiple individuals develop antibodies against the same antigen using the same genetic elements and modes of recognition. The authors identified the immunoglobulin heavy-chain variable region 3-53 gene as the most frequently used among 294 antibodies that target the receptor-binding domain (RBD) of the viral spike protein. These antibodies have few somatic mutations, and crystal structures of two neutralizing antibodies bound to the RBD show that mostly germline-encoded residues are involved in binding. The minimal affinity maturation and high potency of these antibodies is promising for vaccine design. </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="6507" page="1119" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abd2321">1119</jats:related-article> </jats:p>

<jats:title>Double whammy</jats:title> <jats:p> Dengue and Zika virus epidemics have been lapping each other around the globe. These are closely related mosquito-borne viruses with about 40% homology within the envelope protein. We know that subsequent dengue infections bring a risk of antibody-dependent disease enhancement. Whereas emphasis has been placed on how prior dengue immunity affects Zika infection, little is known about how prior Zika immunity may affect dengue disease. Katzelnick <jats:italic>et al.</jats:italic> have been following a well-characterized and established pediatric cohort in Nicaragua who were serially exposed to both flaviviruses in recent years (see the Perspective by Clapham). This study shows not only that a previous history of just one round of dengue is a problem but also that prior Zika immunity creates an increased risk for severe dengue virus sereotype 2 infection. By contrast, multiple infections raise antibodies to protective levels. </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="6507" page="1123" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abb6143">1123</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6507" page="1055" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abd5922">1055</jats:related-article> </jats:p>

<jats:title>Teasing apart the mosquito immune system</jats:title> <jats:p> Hemocytes are key immune cells of insects, playing a major role in how vector species transmit disease. Raddi <jats:italic>et al.</jats:italic> collected and sequenced the RNA of more than 8000 individual hemocytes from the disease-carrying mosquitoes <jats:italic>Anopheles gambiae</jats:italic> and <jats:italic>Aedes aegypti</jats:italic> . These data were then analyzed to determine hemocyte differentiation lineages and population changes in response to noninfected and <jats:italic>Plasmodium</jats:italic> -infected blood meals. From these data, the researchers identified a new hemocyte type, the megacyte, defined by the transcription of specific marker genes. Gene-silencing experiments implied that the megacyte functions in hemocyte differentiation during immune priming and thus may be involved in the immune response in mosquitoes. </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="6507" page="1128" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abc0322">1128</jats:related-article> </jats:p>

<jats:title>Exploring the design landscape</jats:title> <jats:p> Protein design typically selects a protein topology and then identifies the geometries (secondary-structure lengths and orientations) that give the most stable structures. A challenge for this approach is that functional sites in natural proteins often adopt nonideal geometries. Pan <jats:italic>et al.</jats:italic> addressed this issue by exploring the diversity of geometries that can be sampled by a given topology. They developed a computational method called LUCS that systematically samples geometric variation in loop-helix-loop elements and applied it to two different topologies. This method generated families of well-folded proteins that include structures with non-native geometries. The ability to tune protein geometry may enable the custom design of new functions. </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="6507" page="1132" related-article-type="in-this-issue" vol="369" xlink:href="10.1126/science.abc0881">1132</jats:related-article> </jats:p>