Catálogo de publicaciones - revistas

<jats:title>Earthquakes get a more flexible source</jats:title> <jats:p> Earth's surface deforms in part as a result of ruptures along brittle crustal faults that generate earthquakes. Understanding rock deformation in the ductile lower crust and mantle is challenging. Using the densest seismic arrays in the world, Inbal <jats:italic>et al.</jats:italic> have found an unexpected localization of seismicity at these depths under the Newport-Inglewood fault in southern California. The seismicity points to a type of earthquake that may help us understand how ductile deformation operates in this region of Earth. </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="6308" page="88" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf1370">88</jats:related-article> </jats:p>

<jats:title>Maintaining a stable phase</jats:title> <jats:p> For solar cell applications, all-inorganic perovskite phases could be more stable than those containing organic cations. But the band gaps of the former, which determine the electrical conductivity of these materials, are not well matched to the solar spectrum. The cubic structure of CsPbI <jats:sub>3</jats:sub> is an exception, but it is stable in bulk only at high temperatures. Swarnkar <jats:italic>et al.</jats:italic> show that surfactant-coated α-CsPbI <jats:sub>3</jats:sub> quantum dots are stable at ambient conditions and have tunable band gaps in the visible range. Thin films of these materials can be made by spin coating with an antisolvent technique to minimize surfactant loss. When used in solar cells, these films have efficiencies exceeding 10%, making them promising for light harvesting or for LEDs. </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="6308" page="92" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aag2700">92</jats:related-article> </jats:p>

<jats:title>Sluggish turmoil in the Fermi sea</jats:title> <jats:p> The nonequilibrium dynamics of many-body quantum systems are tricky to study experimentally or theoretically. As an experimental setting, dilute atomic gases offer an advantage over electrons in metals. In this environment, the heavier atoms make collective processes that involve the entire Fermi sea occur at the sluggish time scale of microseconds. Cetina <jats:italic>et al.</jats:italic> studied these dynamics by using a small cloud of <jats:sup>40</jats:sup> K atoms that was positioned at the center of a far larger <jats:sup>6</jats:sup> Li cloud. Controlling the interactions between K and Li atoms enabled a detailed look into the formation of quasiparticles associated with K “impurity” atoms. </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="6308" page="96" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf5134">96</jats:related-article> </jats:p>

<jats:title>A flatter route to shorter channels</jats:title> <jats:p> High-performance silicon transistors can have gate lengths as short as 5 nm before source-drain tunneling and loss of electrostatic control lead to unacceptable leakage current when the device is off. Desai <jats:italic>et al.</jats:italic> explored the use of MoS <jats:sub>2</jats:sub> as a channel material, given that its electronic properties as thin layers should limit such leakage. A transistor with a 1-nm physical gate was constructed with a MoS <jats:sub>2</jats:sub> bilayer channel and a single-walled carbon nanotube gate electrode. Excellent switching characteristics and an on-off state current ratio of ∼10 <jats:sup>6</jats:sup> were observed. </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="6308" page="99" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah4698">99</jats:related-article> </jats:p>

<jats:title>Something like the real thing</jats:title> <jats:p> Artificial metalloenzymes ideally combine the favorable properties of natural enzymes with the high efficiency of synthetic catalysts. Inserting new metal groups into existing native proteins, however, often leads to poorer overall catalytic efficiency. To break through this limitation, Dydio <jats:italic>et al.</jats:italic> replaced the iron in the heme group of cytochrome P450 with iridium and subjected it to directed evolution. The enzyme catalyzed a range of reactions with kinetics similar to those of the native enzyme. It was also able to functionalize fully unactivated C-H bonds, a reaction that previously has only been mediated by synthetic catalysts. Moreover, the artificial enzyme was stable across temperatures and scales that are used industrially. </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="6308" page="102" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah4427">102</jats:related-article> </jats:p>

<jats:title>Making nacre shine in the lab</jats:title> <jats:p> Many of the materials that animals use to make shells and skeletons are built with brittle or soft molecules. They owe their amazing mechanical properties to their layered construction, which is a challenge for synthetic fabrication. Pearly nacre, for example, has proved challenging to make owing to its complex structure of aragonite crystals in an organic matrix. Using an assembly-and-mineralization approach, Mao <jats:italic>et al.</jats:italic> have managed to fabricate nacre in the laboratory (see the Perspective by Barthelat). First, a layered, three-dimensional chitosan matrix is made, within which aragonite nanocrystals are precipitated from a solution containing calcium bicarbonate. </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="6308" page="107" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf8991">107</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6308" page="32" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah6507">32</jats:related-article> </jats:p>

<jats:title>Apes understand false beliefs</jats:title> <jats:p> We humans tend to believe that our cognitive skills are unique, not only in degree, but also in kind. The more closely we look at other species, however, the clearer it becomes that the difference is one of degree. Krupenye <jats:italic>et al.</jats:italic> show that three different species of apes are able to anticipate that others may have mistaken beliefs about a situation (see the Perspective by de Waal). The apes appear to understand that individuals have different perceptions about the world, thus overturning the human-only paradigm of the theory of mind. </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="6308" page="110" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf8110">110</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6308" page="39" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aai8851">39</jats:related-article> </jats:p>

<jats:title>The long and winding road to methane</jats:title> <jats:p> The process by which archaea make methane involves a series of reactions and enzymes. First, CO <jats:sub>2</jats:sub> and methanofuran (MFR) are reduced to formyl-MFR by an as yet unresolved mechanism. Wagner <jats:italic>et al.</jats:italic> solved the x-ray crystal structure of a tungsten-containing formyl-MFR dehydrogenase complex. Two active sites in the complex are separated by a 43-Å tunnel, which is responsible for transferring the formate made after CO <jats:sub>2</jats:sub> reduction. The complex also contains a chain of 46 iron-sulfur clusters. Although the exact function of this chain is unclear, it may electronically couple the four tungsten redox centers. </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="6308" page="114" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf9284">114</jats:related-article> </jats:p>

<jats:p> With some 2 meters of DNA squished into the micron-sized nucleus of every mammalian cell, to call that space "cozy" is an understatement. Yet for cells, the genome poses issues not only of compaction but of functionality: The DNA must be packaged such that it remains accessible to gene regulatory factors. Indeed, chromatin architecture plays a key role in gene regulation, but until recently, researchers had few tools with which to study that relationship. <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/chromatin-untangled-new-methods-map-genomic-structure">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/7%20October%20Genomics%20Features.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/7%20October%20New%20Products.pdf">Read New Products (PDF)</jats:ext-link> </jats:p> </jats:list-item> </jats:list> </jats:p>

<jats:p> Immune cells divide rapidly when mounting an immune response against a pathogen, for example, or when initiating a wound-healing response. To accommodate the increased energy requirements to mount the immune response, these cells may employ metabolic pathways similar to those engaged by cancer cells—pathways such as aerobic glycolysis. This correlation presents the intriguing possibility that understanding immune cell metabolism will provide new and actionable insights into the behavior of tumor cells. In this webinar, our expert speakers will explore how this phenomenon is being studied and describe how it could enable the development of new strategies in the fight against cancer. <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://webinar.sciencemag.org/webinar/archive/key-signaling-pathways-cancer-0">View the Webinar</jats:ext-link> </jats:p> </jats:list-item> </jats:list> </jats:p>