Catálogo de publicaciones - revistas

<jats:title>Disentangling intertwined orders</jats:title> <jats:p> In copper oxide superconductors, several types of order compete for supremacy. In addition to superconductivity, researchers have found periodic patterns in charge density (CDW order), as well as an asymmetry in the electronic density within the unit cell of some cuprates (nematicity). CDW order has been detected in the underdoped regime of all major cuprate families, but the ubiquity of nematicity is less clear. Achkar <jats:italic>et al.</jats:italic> used resonant x-ray scattering to find that, in the copper oxide planes of three lanthanum-based cuprates, nematicity has a temperature dependence distinct from that of a related structural distortion. This implies that there are additional, electronic mechanisms for nematicity </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="6273" page="576" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad1824">576</jats:related-article> </jats:p>

<jats:title>Controlled colloid bonding using DNA</jats:title> <jats:p> Colloidal particles can act as analogs of atoms for studying crystallization and packing behavior, but they don't naturally bond together the way atoms do. Short strands of DNA are one versatile way to link together colloidal particles (see the Perspective by Tao). Kim <jats:italic>et al.</jats:italic> designed a series of gold colloids with DNA ligands that reversibly bound to or released neighboring particles via DNA strands that opened or closed hairpin loops. Liu <jats:italic>et al.</jats:italic> devised a set of DNA strands that pack into origami structures. Inside each structure were strands that cage a gold nanoparticle. These were further linked to other uncaged nanoparticles to assemble a diamond-like structure. Changing the strand design yielded a wide range of sparsely packed colloidal crystals. </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="6273" page="561" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aae0455">561</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6273" page="579" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad2212">579</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6273" page="582" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad2080">582</jats:related-article> </jats:p>

<jats:title>Controlled colloid bonding using DNA</jats:title> <jats:p> Colloidal particles can act as analogs of atoms for studying crystallization and packing behavior, but they don't naturally bond together the way atoms do. Short strands of DNA are one versatile way to link together colloidal particles (see the Perspective by Tao). Kim <jats:italic>et al.</jats:italic> designed a series of gold colloids with DNA ligands that reversibly bound to or released neighboring particles via DNA strands that opened or closed hairpin loops. Liu <jats:italic>et al.</jats:italic> devised a set of DNA strands that pack into origami structures. Inside each structure were strands that cage a gold nanoparticle. These were further linked to other uncaged nanoparticles to assemble a diamond-like structure. Changing the strand design yielded a wide range of sparsely packed colloidal crystals. </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="6273" page="561" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aae0455">561</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6273" page="579" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad2212">579</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6273" page="582" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad2080">582</jats:related-article> </jats:p>

<jats:title>Manipulating a stubborn magnet</jats:title> <jats:p> Spintronics is an alternative to conventional electronics, based on using the electron's spin rather than its charge. Spintronic devices, such as magnetic memory, have traditionally used ferromagnetic materials to encode the 1's and 0's of the binary code. A weakness of this approach—that strong magnetic fields can erase the encoded information—could be avoided by using antiferromagnets instead of ferromagnets. But manipulating the magnetic ordering of antiferromagnets is tricky. Now, Wadley <jats:italic>et al.</jats:italic> have found a way (see the Perspective by Marrows). Running currents along specific directions in the thin films of the antiferromagnetic compound CuMnAs reoriented the magnetic domains in the material. </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="6273" page="587" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aab1031">587</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6273" page="558" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad8211">558</jats:related-article> </jats:p>

<jats:title>Keeping a stiff upper layer</jats:title> <jats:p> The interior of the Greenland Ice Sheet is growing thicker, in contrast to the thinning that is occurring at its edges. Why? MacGregor <jats:italic>et al.</jats:italic> conclude that more snow is accumulating and that the ice in the interior is flowing more slowly than it did thousands of years ago (see the Perspective by Hvidberg). During the last glacial period, higher rates of atmospheric dust deposition produced softer ice, which flowed more readily than cleaner ice. During most of the Holocene, though, atmospheric dust concentrations were lower, and the less-dusty ice that formed was stiffer, meaning it did not flow or thin so rapidly. Thus, the thickening seen today in the central regions of Greenland is partly a response to changes in ice rheology that occurred thousands of years ago. </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="6273" page="590" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aab1702">590</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6273" page="562" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad9997">562</jats:related-article> </jats:p>

<jats:title> <jats:italic>Varroa</jats:italic> -vectored virus pandemic </jats:title> <jats:p> Bees are facing several threats that are causing population collapses. Wilfert <jats:italic>et al.</jats:italic> found that European honey bees are the primary source of deformed wing virus (DWV) (see the Perspective by Villalobos). However, paradoxically, transmission between bees is inefficient. It seems that parasitic mites can facilitate virus transmission. European honeybees acquired the rapidly spreading <jats:italic>Varroa</jats:italic> mite from Asian honey bees, possibly via the commercial exchange of queens. Not only do bees suffer direct damage from the mites, but the bees are also efficiently inoculated with DWV. </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="6273" page="594" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aac9976">594</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6273" page="554" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aaf0938">554</jats:related-article> </jats:p>

<jats:title>Europe's managed forests contribute to warming</jats:title> <jats:p> For most of the past 250 years, surprisingly it seems that Europe's managed forests have been a net source of carbon, contributing to climate warming rather than mitigating it. Naudts <jats:italic>et al.</jats:italic> reconstructed the history of forest management in Europe in the context of a land-atmosphere model. The release of carbon otherwise stored in litter, dead wood, and soil carbon pools in managed forests was one key factor contributing to climate warming. Second, the conversion of broadleaved forests to coniferous forests has changed the albedo and evapotranspiration of those forests, also leading to warming. Thus, climate change mitigation policies in Europe and elsewhere may need to consider changes in forest management. </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="6273" page="597" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad7270">597</jats:related-article> </jats:p>

<jats:title>It's not only the carbon in the trees</jats:title> <jats:p> Forest loss affects climate not just because of the impacts it has on the carbon cycle, but also because of how it affects the fluxes of energy and water between the land and the atmosphere. Evaluating global impact is complicated because deforestation can produce different results in different climate zones, making it hard to determine large-scale trends rather than more local ones. Alkama and Cescatti conducted a global assessment of the biophysical effects of forest cover change. Forest loss amplifies diurnal temperature variations, increases mean and maximum air temperatures, and causes a significant amount of warming when compared to CO <jats:sub>2</jats:sub> emission from land-use change. </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="6273" page="600" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aac8083">600</jats:related-article> </jats:p>

<jats:title>Cancer therapy by entrapment</jats:title> <jats:p> Mutations in the <jats:italic>KRAS</jats:italic> oncogene occur at high frequency in several of the most lethal human cancers, including lung and pancreatic cancer. Substantial effort has thus been directed toward developing KRAS inhibitors. <jats:italic>KRAS</jats:italic> encodes an enzyme that binds the nucleotide GTP and hydrolyzes it to GDP. It had been thought that oncogenic mutations disable this hydrolytic activity, locking KRAS in the GTP-bound, active state. Surprisingly, Lito <jats:italic>et al.</jats:italic> found that a certain KRAS mutant (G12C) retains hydrolytic activity and continues to cycle between its active and inactive states. They describe a compound that inhibits KRAS(G12C) signaling and tumor cell growth by binding to the GDPbound form of KRAS, trapping it in its inactive state. </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="6273" page="604" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad6204">604</jats:related-article> </jats:p>

<jats:title>A bacterial defense mechanism</jats:title> <jats:p> Polymyxins are antibiotics that disrupt the bacterial cell membrane and are used to treat multidrug-resistant infections. A bacterial enzyme called ArnT can mediate resistance to polymyxins by transferring a sugar group from a lipid carrier to lipid A, a component of the bacterial outer membrane. Petrou <jats:italic>et al.</jats:italic> described structures of ArnT alone and in complex with a lipid carrier and identified a cavity where lipid A probably binds. Insights into the enzyme mechanism could be exploited to design drugs that combat polymyxin resistance. </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="6273" page="608" related-article-type="in-this-issue" vol="351" xlink:href="10.1126/science.aad1172">608</jats:related-article> </jats:p>