Catálogo de publicaciones - revistas

<jats:title>Ultrafast studies using liquid cells</jats:title> <jats:p> Advances in microscopy techniques aim to make it possible to study materials under more realistic conditions, such as in liquid cells, or to use fast probes to capture dynamics. Fu <jats:italic>et al.</jats:italic> combined liquid cell transmission electron microscopy with ultrafast pump-probe spectroscopy to perform time-resolved studies of nanoscale objects (see the Perspective by Baum). They successfully captured the change in rotational dynamics of coupled gold nanoparticles and also observed the dynamics as two particles fused together in a liquid environment. </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="6324" page="494" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aah3582">494</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6324" page="458" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aam6381">458</jats:related-article> </jats:p>

<jats:title>Expressed preferences among methyl groups</jats:title> <jats:p> Targeting just one of the two equivalent branch ends in Y-shaped molecules is a particular challenge for catalysis. Enzymes manage to do it by grasping the whole molecule, octopus-like, but often enzymes cannot tolerate minor structural variations. Wu <jats:italic>et al.</jats:italic> produced an amide-directed palladium catalyst that, armed with oxazoline-derived chiral ligands, could reliably attack just one methyl member of isopropyl groups. The reaction successfully replaced C–H bonds with C–C bonds in a wide variety of aryl and vinyl coupling partners. </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="6324" page="499" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aal5175">499</jats:related-article> </jats:p>

<jats:title>Getting a sense of atomically thin materials</jats:title> <jats:p> Two-dimensional materials such as graphene and transition metal dichalcogenides provide a powerful platform for optoelectronic applications. As the materials get thinner, however, characterizing the electronic properties can present an experimental challenge. Lovchinsky <jats:italic>et al.</jats:italic> demonstrate that atomic-like impurities in diamond can be used to probe the properties of 2D materials by nanometer-scale nuclear quadrupole resonance spectroscopy. Coherent manipulation of shallow nitrogen-vacancy color centers enabled probing of nanoscale ensembles down to several tens of nuclear spins in atomically thin hexagonal boron nitride. </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="6324" page="503" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aal2538">503</jats:related-article> </jats:p>

<jats:title>Synapse remodeling during sleep</jats:title> <jats:p> General activity and information processing while an animal is awake drive synapse strengthening. This is counterbalanced by weakening of synapses during sleep (see the Perspective by Acsády). De Vivo <jats:italic>et al.</jats:italic> used serial scanning electron microscopy to reconstruct axon-spine interface and spine head volume in the mouse brain. They observed a substantial decrease in interface size after sleep. The largest relative changes occurred among weak synapses, whereas strong ones remained stable. Diering <jats:italic>et al.</jats:italic> found that synapses undergo changes in synaptic glutamate receptors during the sleep-wake cycle, driven by the immediate early gene <jats:italic>Homer1a.</jats:italic> In awake animals, <jats:italic>Homer1a</jats:italic> accumulates in neurons but is excluded from synapses by high levels of noradrenaline. At the onset of sleep, noradrenaline levels decline, allowing <jats:italic>Homer1a</jats:italic> to move to excitatory synapses and drive synapse weakening. </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="6324" page="457" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aam7917">457</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6324" page="507" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aah5982">507</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6324" page="511" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aai8355">511</jats:related-article> </jats:p>

<jats:title>Synapse remodeling during sleep</jats:title> <jats:p> General activity and information processing while an animal is awake drive synapse strengthening. This is counterbalanced by weakening of synapses during sleep (see the Perspective by Acsády). De Vivo <jats:italic>et al.</jats:italic> used serial scanning electron microscopy to reconstruct axon-spine interface and spine head volume in the mouse brain. They observed a substantial decrease in interface size after sleep. The largest relative changes occurred among weak synapses, whereas strong ones remained stable. Diering <jats:italic>et al.</jats:italic> found that synapses undergo changes in synaptic glutamate receptors during the sleep-wake cycle, driven by the immediate early gene <jats:italic>Homer1a.</jats:italic> In awake animals, <jats:italic>Homer1a</jats:italic> accumulates in neurons but is excluded from synapses by high levels of noradrenaline. At the onset of sleep, noradrenaline levels decline, allowing <jats:italic>Homer1a</jats:italic> to move to excitatory synapses and drive synapse weakening. </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="6324" page="457" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aam7917">457</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6324" page="507" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aah5982">507</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6324" page="511" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aai8355">511</jats:related-article> </jats:p>

<jats:title>Using global data for election predictions</jats:title> <jats:p> Assumptions underlying election result predictions have been questioned recently. Kennedy <jats:italic>et al.</jats:italic> assessed more than 650 executive office elections in over 85 countries and performed two live forecasting experiments. They analyzed a variety of potential predictors theorized to be of importance, ranging from economic performance to polling data. Elections were about 80 to 90% predictable, despite uncertainties with available data. Polling data were very important to successful prediction, although it was necessary to correct for systematic biases. Unexpectedly, economic indicators were only weakly predictive. As data sources improve and grow, predictive power is expected to increase. </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="6324" page="515" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aal2887">515</jats:related-article> </jats:p>

<jats:title>Activating DNA repair</jats:title> <jats:p> DNA double-strand breaks must be repaired efficiently to avoid cell death or cancer. The break ends can either be directly ligated by nonhomologous end joining (NHEJ) or more accurately repaired by homologous recombination that uses information from the sister chromatid. Sibanda <jats:italic>et al.</jats:italic> present a high-resolution x-ray structure of a key component of the DNA repair machinery, the DNA-dependent kinase catalytic subunit (DNA-PKcs), bound to a C-terminal peptide of Ku80. The structure suggests that Ku80 presents the DNA ends for repair to a DNA-PKcs dimer and that activity is modulated by interactions between the monomers. Binding of either Ku80 or BRCA1, which may compete for the same binding site on DNA-PKcs, could provide a switch between NHEJ and homologous 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="6324" page="520" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aak9654">520</jats:related-article> </jats:p>