Catálogo de publicaciones - revistas

<jats:title>Lightly dispersed palladium</jats:title> <jats:p> Catalysts made from atomically dispersed metal atoms on oxide supports can exhibit very high per atom activity. However, the low loadings needed to prevent metal particle formation can limit overall performance. Liu <jats:italic>et al.</jats:italic> stably decorated titanium oxide nanosheets with relatively high loadings of single palladium atoms by reducing the ions with ultraviolet light and ethylene glycol. These catalysts cleaved H <jats:sub>2</jats:sub> into atoms and were highly effective for hydrogenating alkenes and aldehydes. </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="6287" page="797" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf5251">797</jats:related-article> </jats:p>

<jats:title>Carbon links without helpful neighbors</jats:title> <jats:p> It's an irony of modern organic chemistry that the simplest-looking carbon-carbon bonds are often the hardest to make. Most reactions owe their efficiency to neighboring double bonds or oxygen and nitrogen atoms that linger in the products. Qin <jats:italic>et al.</jats:italic> now present a broadly applicable protocol for making C-C bonds in the absence of such surrounding help. The nickel-catalyzed process couples a zinc-activated carbon center to an ester that's poised to lose CO <jats:sub>2</jats:sub> . The ready availability of numerous carboxylic acids (which are easily converted to esters) contributes to the reaction's versatility. </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="6287" page="801" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf6123">801</jats:related-article> </jats:p>

<jats:title>A twist on optical multiplexing</jats:title> <jats:p> Information can be encoded using various properties of light. Optical multiplexing frequency, brightness, and polarization have played crucial roles in information technologies, high-capacity data storage, high-speed communications, and biological sensing. Angular momentum is another degree of freedom that could increase capacity further. Typically, however, the bulk optical elements used to determine the angular momentum of light limit possible on-chip processing. Ren <jats:italic>et al.</jats:italic> take a nanophotonics approach to measure and sort light co-propagating with different states of angular momentum (see the Perspective by Molina-Terriza). The approach is promising for on-chip multiplex processing of optical signals. </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="6287" page="805" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf1112">805</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="774" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf6388">774</jats:related-article> </jats:p>

<jats:title>Isotopes isolated after impact</jats:title> <jats:p> Details about how Earth formed are gleaned from the daughter products of certain short-lived radioactive isotopes found in rocks. Rizo <jats:italic>et al.</jats:italic> describe subtle tungsten isotope variations in rocks from the very deep mantle in Baffin Island and the Ontong Java Plateau (see the Perspective by Dahl). The results suggest that portions of Earth have remained unmixed since it formed. The unmixed deep mantle rocks also imply that Earth's core formed from several large impact events. </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="6287" page="809" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aad8563">809</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="768" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf2482">768</jats:related-article> </jats:p>

<jats:title>Let sleeping mice remember</jats:title> <jats:p> The role of REM (rapid eye movement) sleep for memory consolidation has been discussed for a long time. Boyce <jats:italic>et al.</jats:italic> used optogenetics to inhibit theta oscillations in the mouse hippocampus during REM sleep (see the Perspective by Kocsis). Both object recognition memory and contextual fear memory were impaired. This consolidation mechanism occurred in a critical time window immediately after training. Disrupting the same system for similar durations during non-REM sleep or wakefulness had no effect on memory. </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="6287" page="812" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aad5252">812</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="770" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf9117">770</jats:related-article> </jats:p>

<jats:title>Zika virus tested in human brain organoids</jats:title> <jats:p> The pernicious and resilient <jats:italic>Aedes</jats:italic> mosquito is rapidly spreading Zika virus (ZIKV) through the Americas. ZIKV infection mostly causes mild disease, but in some patients, nervous system involvement is indicated. A particular worry is an observed correlation between infection of mothers in the first trimester of pregnancy and microcephaly in newborns. Garcez <jats:italic>et al.</jats:italic> tested the effects of ZIKV compared with dengue virus infection on human neural stem cells grown as organoids. ZIKV targeted the human brain cells, reduced their size and viability in vitro, and caused programmed cell death responses. </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="6287" page="816" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf6116">816</jats:related-article> </jats:p>

<jats:title>Consequences conferred at a distance</jats:title> <jats:p> Migratory animals have adapted to life in multiple, sometimes very different environments. Thus, they may show particularly complex responses as climates rapidly change. Van Gils <jats:italic>et al.</jats:italic> show that body size in red knot birds has been decreasing as their Arctic breeding ground warms (see the Perspective by Wikelski and Tertitski). However, the real toll of this change appears not in the rapidly changing northern part of their range but in the apparently more stable tropical wintering range. The resulting smaller, short-billed birds have difficulty reaching their major food source, deeply buried mollusks, which decreases the survival of birds born during particularly warm years. </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="6287" page="819" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aad6351">819</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6287" page="775" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf6544">775</jats:related-article> </jats:p>

<jats:title>Catching a radical in action</jats:title> <jats:p> Many enzymes catalyze reactions through the production of radical intermediates. Radical SAM enzymes, the largest superfamily of enzymes in nature, do this by using an iron-sulfur cluster to cleave S-adenosylmethionine and produce a radical intermediate. Using freeze quenching, Horitani <jats:italic>et al.</jats:italic> were able to trap a previously unseen radical intermediate from bacterial pyruvate formate-lyase activating enzyme. Spectroscopy revealed that the intermediate consists of a short-lived covalent bond between the terminal carbon of 5′-deoxyadenosyl and the single iron atom of the iron-sulfur cluster. Not only does the observation of this radical expand our mechanistic understanding of radical SAM enzymes, but it expands the range of enzyme active sites or cofactors that function through an organometallic center. </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="6287" page="822" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaf5327">822</jats:related-article> </jats:p>

<jats:title>The effects of rainfall on rainfall</jats:title> <jats:p>Soil moisture, which is controlled in part by past rainfall, can affect the probability of future rainfall over large areas. This is because the water contained in soils helps determine how sunlight is converted into latent heat (evaporation) and sensible heat (which increases overlying air temperatures). Tuttle and Salvucci used data collected for the contiguous United States over 10 years to study this relationship. The feedback between soil moisture and rainfall is generally positive in the western United States but negative in the east. This regional dependence could be a function of large-scale differences in aridity.</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="6287" page="825" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aaa7185">825</jats:related-article> </jats:p>

<jats:title>An antibody to block viral fusion</jats:title> <jats:p> A small fraction of HIV-1–infected individuals develop broad and potent antibodies that bind the HIV-1 envelope protein (Env). These antibodies recognize a limited set of conserved epitopes on Env, such as Env's host receptor-binding site. Kong <jats:italic>et al.</jats:italic> now report a neutralizing antibody isolated from an HIV-1–infected individual that binds to the fusion peptide of Env. This is unexpected because viruses often try to mask such key components of their cell entry machinery from antibody attack. Crystal structures of the antibody bound to the fusion peptide and to Env itself define the epitope, provide insight into the specific mechanism of antibody binding, and may inform HIV-1 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="6287" page="828" related-article-type="in-this-issue" vol="352" xlink:href="10.1126/science.aae0474">828</jats:related-article> </jats:p>