Catálogo de publicaciones - revistas

<jats:title>Taking advantage of four for a nickel</jats:title> <jats:p>Metal atoms change their oxidation state—i.e., lose or gain electrons—relatively easily. This is a major reason why metal compounds accelerate so many chemical reactions. Camasso and Sanford now report a straightforward way to prepare complexes of nickel in the +4 oxidation state, based on careful tuning of the coordination environment around the metal center (see the Perspective by Riordan). These complexes could prove useful in coupling carbon to oxygen, nitrogen, or sulfur, and complement more traditional nickel catalysts that operate in lower oxidation states.</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="6227" page="1218" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa4526">1218</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6227" page="1203" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa7553">1203</jats:related-article> </jats:p>

<jats:title>A block-by-block way to manufacture molecules</jats:title> <jats:p> Carbon-based small molecules involved in biochemistry and drug design exhibit extraordinary structural diversity. But can we come up with a general set of building blocks from which a machine could put most of them together, in assembly-line fashion? Li <jats:italic>et al.</jats:italic> present progress toward this goal by showcasing the range of structures available via coupling reactions of fragments bearing a specific type of boronate group. They successfully made complex polycyclic structures by stringing together a linear precursor and then coaxing it to fold back on itself. They also developed a purification method that facilitates automation of the reaction and product isolation. </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="6227" page="1221" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa5414">1221</jats:related-article> </jats:p>

<jats:title>Onsite radar shows what lies beneath</jats:title> <jats:p> In more active periods of the Moon's history, volcanic eruptions created lava plains that formed layers of dark basalt. Without subsurface probing, we can only examine the most recent flows. After the soft landing of the Chang'E-3 spacecraft, Xiao <jats:italic>et al.</jats:italic> made penetrating radar measurements of the lunar crust with the Yutu rover. Several subsurface layers suggest multiple geologic processes at play throughout the crustal history, including multiple lava flows and the weathering-induced creation of dust and rocky debris. </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="6227" page="1226" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1259866">1226</jats:related-article> </jats:p>

<jats:title>Quantum walkers under a microscope</jats:title> <jats:p> Generations of physics students have been taught to think of one-dimensional random walks in terms of a drunken sailor taking random steps to the right or to the left. But that doesn't compare with the complexity of a quantum walker, who can propagate down multiple paths at the same time. Preiss <jats:italic>et al.</jats:italic> detected particles in single sites of an optical lattice to study the dynamics of two interacting atoms of 87Rb performing a quantum walk (see the Perspective by Widera). Depending on the initial conditions and the interaction strength between the atoms, the atoms either ignored each other, stuck to each other, or tried to get as far away from each other as possible. </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="6227" page="1229" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1260364">1229</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6227" page="1200" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa6885">1200</jats:related-article> </jats:p>

<jats:title>Highly charged ions in cold confines</jats:title> <jats:p> High-energy irradiation can strip many electrons away from individual atoms, producing ions with charges of +10 or more. However, many of the interesting properties of such highly charged ions are hard to study or exploit under the extreme conditions needed to prepare them. Schmöger <jats:italic>et al.</jats:italic> cooled down argon ions with +13 charges from the megakelvin temperatures needed for their generation to millikelvin temperatures appropriate for high-precision spectroscopy. The method relies on sympathetic cooling by a cold sample of singly charged beryllium ions and is likely to be applicable to a broad range of other elements. </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="6227" page="1233" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa2960">1233</jats:related-article> </jats:p>

<jats:title>Connecting orbit to the ocean floor</jats:title> <jats:p> The amount of magma erupted at mid-ocean ridges can be modified by periodic ice ages that alter sea level. Crowley <jats:italic>et al.</jats:italic> analyzed high-resolution ocean depth data across the Australian-Antarctic ocean ridge (see the Perspective by Conrad). The results revealed 23-, 41-, and 100-thousand-year periodicity. These periods are similar to the well-known Milankovitch cycles associated with ice ages that are triggered by changes in Earth's orbit. Decreasing sea levels decrease the overlying pressure, thereby increasing the amount of erupted magma. The cyclic nature of glaciations and sea level creates a series of spaced topographic highs along the sea floor. Thus, Earth's atmosphere and mantle are coupled on a glacial time scale. </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="6227" page="1237" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1261508">1237</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6227" page="1204" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa6813">1204</jats:related-article> </jats:p>

<jats:title>Vaccinate children despite Ebola</jats:title> <jats:p> During the medical emergency caused by the Ebola virus outbreak in West Africa, routine childhood vaccination programs have been suspended. If vaccination is not resumed soon, there could be even more deaths. Measles is highly infectious, and outbreaks are a sign of health care systems in trouble. Using mathematical modelling, Takahashi <jats:italic>et al.</jats:italic> estimate that about a million children across Liberia, Sierra Leone, and Guinea are vulnerable to measles. Aggressive public health programs are vital for this region to minimize harm, not only from measles but also from polio, malaria, tuberculosis, and other childhood infections. </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="6227" page="1240" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa3438">1240</jats:related-article> </jats:p>