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<jats:p>Modulations in the charge density provide a clue while adding complexity to the story of high-temperature superconductivity.</jats:p>

<jats:p>The repeat units of a crystalline material can be made up of disordered clusters.</jats:p>

<jats:p>The discovery in archaea of an alternative proteasome based on Cdc48 provides insights into the evolution of protein degradation machines.</jats:p>

<jats:p>Time-lapse video records a bacterial protein transportation machine in action.</jats:p>

<jats:title>Ditching Invading DNA</jats:title> <jats:p> Bacteria and archaea protect themselves from invasive foreign nucleic acids through an RNA-mediated adaptive immune system called CRISPR (clustered regularly interspaced short palindromic repeats)/CRISPR-associated (Cas). <jats:bold> Jinek <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="816" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1225829">816</jats:related-article> , published online 28 June; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6096" page="808" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1227253">Brouns</jats:related-article> </jats:bold> ) found that for the type II CRISPR/Cas system, the CRISPR RNA (crRNA) as well as the trans-activating crRNA—which is known to be involved in the pre-crRNA processing—were both required to direct the Cas9 endonuclease to cleave the invading target DNA. Furthermore, engineered RNA molecules were able to program the Cas9 endonuclease to cleave specific DNA sequences to generate double-stranded DNA breaks. </jats:p>

<jats:title> A State of High <jats:italic> T <jats:sub>c</jats:sub> </jats:italic> Superconductivity </jats:title> <jats:p> There are strong indications that high-temperature superconductivity in the cuprates is formed amid competing orders, but only two have been observed unambiguously. The so-called stripe order has been observed in a Lanthanum-based cuprate family and consists of coexisting charge-and-spin modulations and occurs at a characteristic dopant concentration in which the critical temperature <jats:italic> T <jats:sub>c</jats:sub> </jats:italic> has a dip. Now, <jats:bold> Ghiringhelli <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="821" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1223532">821</jats:related-article> , published online 12 July; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6096" page="811" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1227082">Tranquada</jats:related-article> </jats:bold> ) have used resonant inelastic x-ray scattering to uncover a related but apparently two-dimensional charge order in the much cleaner YBCO cuprate family. The charge fluctuations were not commensurate with the lattice and did not originate in the characteristic oxygen chains of YBCO. The order appeared only in a narrow interval of dopant concentrations and competed with superconductivity, which provides a natural explanation for a plateau in <jats:italic> T <jats:sub>c</jats:sub> </jats:italic> observed in the same range. </jats:p>

<jats:title>Amorphous Crystals</jats:title> <jats:p> One usually thinks of a crystal as containing atoms, molecules, or other ordered units arranged in a periodic fashion to make a larger structure. <jats:bold> L. Wang <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="825" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1220522">825</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="6096" page="812" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1226048"> <jats:bold>D. Wang and Fernandez-Martinez</jats:bold> </jats:related-article> </jats:bold> ) compressed a solvate of xylene in C <jats:sub>60</jats:sub> (fullerene) to very high pressures at room temperature, which caused the fullerene molecules to collapse and form amorphous clusters but with each cluster retaining its position in the original crystal lattice because of the interaction with the intercalated xylene molecules. Thus, a crystal was formed from amorphous constituents. On heating at atmospheric pressure, the xylene disappeared and the sample became completely amorphous. </jats:p>

<jats:title>Mechanical Chameleon</jats:title> <jats:p> A wide range of animals can adapt their color patterns as a means of camouflage or otherwise changing their appearance. This is accomplished through changes in coloration, contrast, patterning, or shape. <jats:bold> Morin <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="828" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1222149">828</jats:related-article> ) show at a basic level that some of these features can be added as microfluidic layers attached to mobile, flexible, soft machines. By pumping different fluids through the channels, the robots were able to change their coloration or overall contrast and could thus blend into the background of the surface they were lying upon. Conversely, by pumping through fluids of different temperature, the infrared profile of the robot could be changed without changing its visible coloration. </jats:p>

<jats:title>Cleaning Diesel Exhaust</jats:title> <jats:p> One strategy for removing pollutants from diesel engine exhaust is to trap the unburned carbon soot and then to combust the soot with the NO <jats:sub>2</jats:sub> that is generated from NO; the two pollutants are then converted to N <jats:sub>2</jats:sub> and CO <jats:sub>2</jats:sub> . Diesel exhaust is relatively cold, compared to gasoline engine exhaust, and conversion of NO to NO <jats:sub>2</jats:sub> has required the use of platinum catalysts. <jats:bold> W. Wang <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="832" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1225091">832</jats:related-article> ) now report that a more earth-abundant catalyst, based on Mn-mullite (Sm, Gd)Mn <jats:sub>2</jats:sub> O <jats:sub>5</jats:sub> metal oxides was able to oxidize NO in simulated diesel exhaust at temperatures as low as 75°C. Spectroscopic studies and quantum chemical modeling suggested that Mn-nitrates formed on Mn-Mn dimer sites were the key intermediates responsible for NO <jats:sub>2</jats:sub> formation. </jats:p>

<jats:title>Water In, Ozone Out</jats:title> <jats:p> The danger of stratospheric ozone loss burst into public awareness in the 1980s, when the Antarctic ozone hole was discovered and described. Since then, the specter of ozone depletion in other locations, notably the Arctic, has been identified. Ozone loss is not confined to high latitudes, however, nor is it only the result of the addition of anthropogenic compounds containing chlorine and bromine in the stratosphere, as <jats:bold> Anderson <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="835" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1222978">835</jats:related-article> , published online 26 July; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6096" page="809" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1227004">Ravishankara</jats:related-article> </jats:bold> ) now demonstrate. Data from the atmosphere above the continental United States revealed that convective injection of water vapor into the stratosphere affects the free radical chemistry involving the (mostly anthropogenic) chlorine and bromine, thus accelerating ozone loss. This process could become important in the stratospheric ozone budget if the frequency and intensity of these water-injection events, which are most common in the summer, increase as a result of global warming. </jats:p>