Catálogo de publicaciones - revistas

<jats:title>Bend it, shape it, remember it</jats:title> <jats:p> Shape-memory alloys have the useful property of returning to their original shape after being greatly deformed. This process depends on the collective behavior of many small mineral grains in the metal. Using three-dimensional x-ray diffraction, Sedmák <jats:italic>et al.</jats:italic> tracked over 15,000 grains in a nickel-titanium shape-memory alloy as it moved through this transformation, thus linking microscopic changes to the bulk deformation. </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="6299" page="559" related-article-type="in-this-issue" vol="353" xlink:href="10.1126/science.aad6700">559</jats:related-article> </jats:p>

<jats:title>Membranes to make benzene from methane</jats:title> <jats:p> Methane gas is expensive to ship. It is usually converted into carbon monoxide and hydrogen and then liquefied. This is economically feasible only on very large scales. Hence, methane produced in small amounts at remote locations is either burned or not extracted. A promising alternative is conversion to benzene and hydrogen with molybdenumzeolite catalysts. Unfortunately, these catalysts deactivate because of carbon buildup; plus, hydrogen has to be removed to drive the reaction forward. Morejudo <jats:italic>et al.</jats:italic> address both of these problems with a solid-state BaZrO <jats:sub>3</jats:sub> membrane reactor that electrochemically removes hydrogen and supplies oxygen to suppress carbon buildup. </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="6299" page="563" related-article-type="in-this-issue" vol="353" xlink:href="10.1126/science.aag0274">563</jats:related-article> </jats:p>

<jats:title>Watching batteries fail</jats:title> <jats:p> Rechargeable batteries lose capacity in part because of physical changes in the electrodes caused by electrochemical cycling. Lim <jats:italic>et al.</jats:italic> track the reaction dynamics of an electrode material, LiFePO <jats:sub>4</jats:sub> , by measuring the relative concentrations of Fe(II) and Fe(III) in it by means of high-resolution x-ray absorption spectrometry (see the Perspective by Schougaard). The exchange current density is then mapped for Li <jats:sup>+</jats:sup> insertion and removal. At fast cycling rates, solid solutions form as Li <jats:sup>+</jats:sup> is removed and inserted. However, at slow cycling rates, nanoscale phase separation occurs within battery particles, which eventually shortens battery life. </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="6299" page="566" related-article-type="in-this-issue" vol="353" xlink:href="10.1126/science.aaf4914">566</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6299" page="543" related-article-type="in-this-issue" vol="353" xlink:href="10.1126/science.aah4124">543</jats:related-article> </jats:p>

<jats:title>Long-life excimer-like structures</jats:title> <jats:p> Metal quantum clusters have ideal properties for medical applications such as imaging. The challenge is to prolong their transient properties for the fabrication of useful devices. Santiago-Gonzalez <jats:italic>et al.</jats:italic> arranged gold clusters in a supramolecular lattice held together by hydrogen bonding and showed that this material can be used for imaging of fibroblast cells. In the superstructure, the gold molecules can come together in the excited state as excimers and then dissociate to emit radiation. Because they are within a lattice, this behavior shows long-term stability. Furthermore, the lattice superstructure scavenges reactive oxygen species and reduces cell damage. </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="6299" page="571" related-article-type="in-this-issue" vol="353" xlink:href="10.1126/science.aaf4924">571</jats:related-article> </jats:p>