Catálogo de publicaciones - revistas

<jats:title>Small olefins from syngas</jats:title> <jats:p> The conversion of coal or natural gas to liquid fuels or chemicals often proceeds through the production of CO and H <jats:sub>2</jats:sub> . This mixture, known as syngas, is then converted to hydrocarbons with Fischer-Tropsch catalysts. For the light olefins (ethylene to butylenes) needed for chemical and polymer synthesis, conventional catalysts are mechanistically limited to &lt;60% conversion and deactivate through carbon buildup. Jiao <jats:italic>et al.</jats:italic> developed a bifunctional catalyst that achieves higher conversions and avoids deactivation (see the Perspective by de Jong). A zinc-chromium oxide creates ketene intermediates that are then coupled over a zeolite. </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="6277" page="1065" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf1835">1065</jats:related-article> , see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6277" page="1030" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf3250">1030</jats:related-article> </jats:p>

<jats:title>Reducing quantum overhead</jats:title> <jats:p> A quantum computer is expected to outperform its classical counterpart in certain tasks. One such task is the factorization of large integers, the technology that underpins the security of bank cards and online privacy. Using a small-scale quantum computer comprising five trapped calcium ions, Monz <jats:italic>et al.</jats:italic> implement a scalable version of Shor's factorization algorithm. With the function of ions being recycled and the architecture scalable, the process is more efficient than previous implementations. The approach thus provides the potential for designing a powerful quantum computer, but with fewer resources. </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="6277" page="1068" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad9480">1068</jats:related-article> </jats:p>

<jats:title>Make it stretch, make it glow</jats:title> <jats:p> The skins of some cephalopods, such as the octopus, are highly flexible and contain color-changing cells. These cells are loaded with pigments that enable rapid and detailed camouflaging abilities. Larson <jats:italic>et al.</jats:italic> developed a stretchable electroluminescent actuator. The material could be highly stretched, could emit light, and could also sense internal and external pressure. A soft robot demonstrated these combined capabilities by stretching and emitting light as it moved. </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="6277" page="1071" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aac5082">1071</jats:related-article> </jats:p>

<jats:title>Brain activity shows underlying motives</jats:title> <jats:p> In humans, two completely different motives may nevertheless lead to exactly the same behavior. Because we can't directly observe motives, modern economists often completely disregard them. However, Hein <jats:italic>et al.</jats:italic> , using fMRI, show that different human motives can yield observable responses in the brain (see the Perspective by Gluth and Fontanesi). In empathy-based and reciprocity-based altruistic behavior, the direction and the strength of functional connectivity between specific brain regions were different for each motive. Moreover, the connectivity patterns were independent of the behavioral implications of the motives. </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="6277" page="1074" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aac7992">1074</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6277" page="1028" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf4688">1028</jats:related-article> </jats:p>

<jats:title>Profiling the antibody response to Ebola</jats:title> <jats:p> The recent Ebola virus outbreak in West Africa illustrates the need not only for a vaccine but for potential therapies, too. One promising therapy is monoclonal antibodies that target Ebola's membrane-anchored glycoprotein (GP). Bornholdt <jats:italic>et al.</jats:italic> isolated and characterized 349 antibodies from a survivor of the 2014 outbreak. A large fraction showed some neutralizing activity and several were quite potent. Structural analysis revealed an important site of vulnerability on the membrane stalk region of GP. Antibodies targeting this area were therapeutically effective in Ebola virus–infected mice. </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="6277" page="1078" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad5788">1078</jats:related-article> </jats:p>

<jats:title>Regulatory use of endogenous retroviruses</jats:title> <jats:p> Mammalian genomes contain many endogenous retroviruses (ERVs), which have a range of evolutionary ages. The propagation and maintenance of these genetic elements have been attributed to their ability to contribute to gene regulation. Chuong <jats:italic>et al.</jats:italic> demonstrate that some ERV families are enriched in regulatory elements, so that they act as independently evolved enhancers for immune genes in both humans and mice (see the Perspective by Lynch). The analysis revealed a primate-specific element that orchestrates the transcriptional response to interferons. Selection can therefore act on selfish genetic elements to generate novel gene networks. </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="6277" page="1083" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad5497">1083</jats:related-article> see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6277" page="1029" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf2977">1029</jats:related-article> </jats:p>

<jats:title>Doubling DNA but not expression</jats:title> <jats:p> As the genome replicates, and before the cell divides, the copy number of the replicated portions of the genome doubles. In bacteria and archaea, gene expression tracks with gene dosage, both of which increase after DNA replication. Voichek <jats:italic>et al.</jats:italic> , however, show that an increase in DNA dosage after replication does not increase gene expression in budding yeast. This expression buffering is mediated by the acetylation of newly synthesized histone H3 deposited on the replicated DNA. This acetylation helps suppress transcription from the excess DNA. </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="6277" page="1087" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad1162">1087</jats:related-article> </jats:p>

<jats:title>Choosing where to start transcription</jats:title> <jats:p> The RNA polymerase enzyme complex binds to the promoter of a gene and separates the two DNA strands. The subsequently formed “transcription bubble” is required for RNA synthesis to begin. How RNA polymerase chooses the exact DNA base at which it will start transcription has been unclear. Winkelman <jats:italic>et al.</jats:italic> show that a control element upstream of the start site is involved in helping RNA polymerase make this choice in bacteria. Start site selection involves promoter scrunching, where a stationary RNA polymerase unwinds and pulls DNA through the active site, scrunching the DNA of the transcription bubble. </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="6277" page="1090" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad6881">1090</jats:related-article> </jats:p>

<jats:title>To have or have not determines DNA repair</jats:title> <jats:p> Cells presumably try to protect DNA from damage at all costs. But Uphof <jats:italic>et al.</jats:italic> show that they do not, because the cost is too high. Single-molecule and single-cell measurements show that the DNA repair enzyme Ada, which also regulates its own expression, was present in such low amounts in <jats:italic>E. coli</jats:italic> that stochastic variation led to some cells having none of the protein at all. Such cells undergo increased mutagenesis, which could be beneficial in circumstances in which increased genetic heterogeneity is required for adaptation. The expression of large amounts of such a DNA-altering protein was also toxic. </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="6277" page="1094" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aac9786">1094</jats:related-article> </jats:p>

<jats:p> Immunohistochemistry (IHC) dates back decades, but that doesn't mean it's stagnant. Automated sample processors, digital slide scanners, image analysis software, and more have given the aged procedure a decidedly 21st century flair. <jats:list list-type="bullet"> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/custom-publishing/technology-features/immunohistochemistry-21st-century">Read the Feature (Full-Text HTML)</jats:ext-link> </jats:p> </jats:list-item> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/sites/default/files/custom-publishing/documents/4%20March%20Tissue%20Analysis.pdf">Read the Feature (PDF)</jats:ext-link> </jats:p> </jats:list-item> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/sites/default/files/custom-publishing/douments/4%20March%20New%20Products.pdf">Read New Products (PDF)</jats:ext-link> </jats:p> </jats:list-item> </jats:list> </jats:p>