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<jats:p>Recent advances in mechanics and materials provide routes to integrated circuits that can offer the electrical properties of conventional, rigid wafer-based technologies but with the ability to be stretched, compressed, twisted, bent, and deformed into arbitrary shapes. Inorganic and organic electronic materials in microstructured and nanostructured forms, intimately integrated with elastomeric substrates, offer particularly attractive characteristics, with realistic pathways to sophisticated embodiments. Here, we review these strategies and describe applications of them in systems ranging from electronic eyeball cameras to deformable light-emitting displays. We conclude with some perspectives on routes to commercialization, new device opportunities, and remaining challenges for research.</jats:p>

<jats:p>Extraordinary electron systems can be generated at well-defined interfaces between complex oxides. In recent years, progress has been achieved in exploring and making use of the fundamental properties of such interfaces, and it has become clear that these electron systems offer the potential for possible future devices. We trace the state of the art of this emerging field of electronics and discuss some of the challenges and pitfalls that may lie ahead.</jats:p>

<jats:p>Fossil evidence indicates that tyrannosaurs also inhabited the southern continents in the late Early Cretaceous period.</jats:p>

<jats:title>“Spontaneous” Release Trigger</jats:title> <jats:p> Synaptic vesicle release occurs in different phases that can be tightly coupled to action potentials (synchronous), immediately following action potentials (asynchronous), or as stochastic events not triggered by action potentials (spontaneous). The vesicle protein synaptotagmin is thought to act as the Ca <jats:sup>2+</jats:sup> sensor in the synchronous phase, but for the other two phases, Ca <jats:sup>2+</jats:sup> sensors have not been identified. <jats:bold> Groffen <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1614" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1183765">1614</jats:related-article> , published online 11 February) now show that cytoplasmic proteins known as Doc2 (double C2 domain) proteins are required for spontaneous release. Doc2 proteins promote membrane fusion in response to exceptionally low increases in Ca <jats:sup>2+</jats:sup> , and are several orders of magnitude more sensitive to Ca <jats:sup>2+</jats:sup> than synaptotagmin. Doc2 and synaptotagmin compete for SNARE-complex binding during membrane fusion. A mutation that abolishes the Ca <jats:sup>2+</jats:sup> dependence of Doc2b also abolishes the Ca <jats:sup>2+</jats:sup> dependence of spontaneous release. Thus, Doc2 is a high-affinity Ca <jats:sup>2+</jats:sup> sensor for spontaneous release that competes with synaptotagmin for SNARE complex binding. </jats:p>

<jats:title>News from the Dark Side?</jats:title> <jats:p> Dark matter is thought to represent 85% of all matter in the universe and to have been responsible for the formation of structure in the early universe, but its nature is still a mystery. <jats:bold> Ahmed <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1619" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1186112">1619</jats:related-article> , published online 11 February; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5973" page="1582" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1187972">Lang</jats:related-article> </jats:bold> ) describe the results from the completed Cryogenic Dark Matter Search (CDMS II) experiment, which searched for dark matter in the form of weakly interacting massive particles (WIMP). Two candidate signals were observed, whereas only one background event was expected. The probability of having two or more events from the background would have been 23%. The results of this analysis cannot be interpreted with confidence as evidence for WIMP interactions, but, at the same time, neither event can be ruled out as representing signal. </jats:p>

<jats:title>Fermion Behavior in an Optical Lattice</jats:title> <jats:p> Due to their extreme tunability, optical lattices loaded with fermions and bosons are expected to act as quantum simulators, answering complicated many-body physics questions beyond the reach of theory and computation. Some of these many-body states, such as the Mott insulator and the superfluid, have been achieved in bosonic optical lattices by simply changing the characteristic depth of the lattice potential wells. Now, <jats:bold> Hackermüller <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1621" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1184565">1621</jats:related-article> ) describe an unusual effect in an optical lattice loaded with fermions: When the strength of the attraction between the fermions is increased adiabatically, instead of contracting, the gas expands in order to preserve entropy. </jats:p>

<jats:title>Platinum-Free Diesel</jats:title> <jats:p> The efficiency advantages inherent in diesel-based combustion engines are counterbalanced by the production of pollutants such as nitrogen oxides (NO <jats:sub> <jats:italic>x</jats:italic> </jats:sub> ). Currently, expensive precious metals, such as platinum, are required to remove these pollutants. <jats:bold> Kim <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1624" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1184087">1624</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5973" page="1584" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1187154">Parks</jats:related-article> </jats:bold> ) show that a strontium-doped perovskite catalyst, prepared from more abundant (and cheaper) elements, may help to lower the cost of NO <jats:sub> <jats:italic>x</jats:italic> </jats:sub> treatments and thus ultimately make diesel a more cost-effective automotive fuel. Under conditions realistically simulating exhaust streams, the catalyst rivaled platinum in accelerating NO <jats:sub> <jats:italic>x</jats:italic> </jats:sub> decomposition. </jats:p>

<jats:title>Iron Exposure</jats:title> <jats:p> The macrocyclic heme motif coordinates iron ions in proteins and plays a widespread role in biochemical oxidative catalysis. <jats:bold> Bezzu <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1627" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1184228">1627</jats:related-article> ) prepared crystals in which analogous iron-centered macrocycles were aligned in pairs. The outer faces of the pairs exposed the iron ions to vacant cavities, where ligand exchange could take place; the inner faces were bound together by rigid bridging ligands lending the crystals structural integrity. The stability and high porosity of these crystals lend themselves to potential catalytic applications. </jats:p>

<jats:title>Preventing Radiation Damage</jats:title> <jats:p> Inside a nuclear reactor, long-term exposure to radiation causes structural damage and limits the lifetimes of the reactor components. <jats:bold> Bai <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1631" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1183723">1631</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5973" page="1587" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1188088">Ackland</jats:related-article> </jats:bold> ) now show, using three simulation methods able to cover a wide range of time and length scales, that grain boundaries in copper can act as sinks for radiation-induced defects. The boundaries are able to store up defects, in the form of interstitials, which subsequently annihilate with vacancies in the bulk. This recombination mechanism has a lower energy barrier than the bulk equivalent, and so provides a lower-cost route for the copper to self-heal. </jats:p>

<jats:title>Perfect Mismatch</jats:title> <jats:p> Heteroepitaxy, or the overgrowth of one crystalline material onto a second crystalline material, is a key fabrication method for making thin films and nanoparticles. But if the lattice mismatch between the two materials is too large or messy, fractured interfaces result. <jats:bold> Zhang <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1634" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1184769">1634</jats:related-article> ) describe a synthesis strategy to obtain spherical nanoparticles with a core-shell architecture that does not depend on heteroepitaxy. Silver was deposited and converted to various semiconductors through a series of chemical transformations to yield structurally perfect single-crystal semiconductor shells on a gold core, despite mismatches approaching 50%. </jats:p>