Catálogo de publicaciones - revistas

<jats:title>Plasmons can map temperature on the nanoscale</jats:title> <jats:p> Determining temperature on small length scales can be challenging: Direct probes can alter sample temperature, and radiation probes are limited by the wavelength of the light used. Mecklenberg <jats:italic>et al.</jats:italic> show how the bulk plasmon resonance of aluminum can be used to map the temperature on the nanoscale with transmission electron microscopy (see the Perspective by Colliex). Many other metals and semiconductors also have plasmon resonances that could also be used for temperature imaging. </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="6222" page="629" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa2433">629</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6222" page="611" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa5311">611</jats:related-article> </jats:p>

<jats:title>Can't keep hot sides hot and cold sides cold?</jats:title> <jats:p> On Earth, we're accustomed to cycles of day and night, which drive a complex thermal relationship between the ground and atmosphere. Some exoplanets very close to their stars aren't so lucky and are generally assumed to be locked by tides into hemispheres of unchanging day and night. The thick atmosphere of Venus is thought to keep it from the same fate, but Leconte <jats:italic>et al.</jats:italic> present models showing that even a much sparser atmosphere may suffice for lower-mass stars. The non-instantaneous thermal response of the planet (when the hottest time of day is after noon) may speed up or slow down the planet. Such thermal tides may be important in assessing potential extraterrestrial habitable zones. </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="6222" page="632" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1258686">632</jats:related-article> </jats:p>

<jats:title>Screw dislocations: A hard case to crack</jats:title> <jats:p> The motion of dislocations or defects in a metal influences its strength and toughness. If these defects can be “pinned” by adding alloying elements, it should be possible to create a stronger alloy. It was thought that there shouldn't be much of an interaction between screw dislocations and any alloying elements. However, Yu <jats:italic>et al.</jats:italic> show that for α-Ti, the profound hardening effect of oxygen is due to the strong interactions with the core of the dislocations. First-principles calculations reveal that distortion of the interstitial sites at the dislocation core creates a very strong but short-range repulsion for oxygen 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="6222" page="635" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1260485">635</jats:related-article> </jats:p>

<jats:title>DNA control of bonding interactions</jats:title> <jats:p>Colloidal particles have been used as atom mimics and are often connected together using complementary DNA strands. Rogers and Manoharan controlled the strength of the colloidal “bond” by using a set of competing strand displacement reactions. They capitalized on the reversible chemical equilibrium between the DNA strands connecting different particles to control the temperature dependence of the equilibrium 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="6222" page="639" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1259762">639</jats:related-article> </jats:p>

<jats:title>Catching a glimpse of the elusive QOOH</jats:title> <jats:p> It's straightforward to write down the net combustion reaction: Oxygen reacts with hydrocarbons to form water and carbon dioxide. The details of how all the bonds break and form in succession are a great deal more complicated. Savee <jats:italic>et al.</jats:italic> now report direct detection of a long-postulated piece of the puzzle, a so-called QOOH intermediate. This structure results from bound oxygen stripping a hydrogen atom from carbon, leaving a carbon-centered radical behind. The study explores the influence of the hydrocarbon's unsaturation on the stability of QOOH, which has implications for both combustion and tropospheric oxidation chemistry. </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="6222" page="643" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa1495">643</jats:related-article> </jats:p>

<jats:title>Popping open one by one into polymers</jats:title> <jats:p> We rarely board airplanes by joining the back of a single well-ordered line. More often, we jostle around in one of several bulging crowds that merge haphazardly near the gate. Roughly speaking, these processes are analogous to the chain growth and step growth mechanisms of polymer assembly at the molecular level. Kang <jats:italic>et al.</jats:italic> present a strategy to link molecular building blocks through hydrogen bonding in accord with the well-controlled chain growth model. The molecules start out curled inward, as they engage in internal hydrogen bonding, until an initiator pulls one open; that molecule is then in the right conformation to pull a partner into the growing chain, poising it to pull in yet another, and so forth down the line. </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="6222" page="646" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa4249">646</jats:related-article> </jats:p>

<jats:title>Termites can stabilize tropical grasslands</jats:title> <jats:p> Spotty vegetation patterns in tropical savannas and grasslands can be a warning sign of imminent desertification. However, Bonachela <jats:italic>et al.</jats:italic> find that termites can also produce spotty patterns. Their theoretical study, confirmed by field data from Kenya, shows that patterns produced by termite mounds are not harbingers of desertification. Indeed, the presence of termites buffers these ecosystems against climate 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="6222" page="651" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1261487">651</jats:related-article> </jats:p>

<jats:title>Genetic control of stem cell fate in plant roots</jats:title> <jats:p> Without roots, most plants cannot thrive. Crawford <jats:italic>et al.</jats:italic> have now unearthed the robust control systems that build roots. Signaling by the plant hormone auxin triggers three genes that control the development of stem cells forming the root. With this trio of genes, any one of which can do the job, root development is backed up with fail-safe controls. The team could use the same system of controls to sprout roots in the wrong places, making roots instead of shoots. </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="6222" page="655" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa0196">655</jats:related-article> </jats:p>