Catálogo de publicaciones - revistas

<jats:title>Toward Titanium Carbide Batteries</jats:title> <jats:p> Many batteries and capacitors make use of lithium intercalation as a means of storing and transporting charge. Lithium is commonly used because it offers the best energy density, but also because there are difficulties in storing larger cations without disrupting the crystal structure of the host. <jats:bold> Lukatskaya <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6153" page="1502" related-article-type="in-this-issue" vol="341" xlink:href="10.1126/science.1241488">1500</jats:related-article> ) developed a series of MX compounds, where M represents a transition metal and X is carbon or nitrogen.The compound Ti <jats:sub>3</jats:sub> C <jats:sub>2</jats:sub> forms a two dimensional layered structure, which is capable of accommodating a wide range of cations, including multivalent ones, either spontaneously or electrochemically </jats:p>

<jats:title>Shape Memory Ceramics</jats:title> <jats:p> Shape memory materials convert heat into strain and vice versa. These materials are often made from metal alloys, which can generate large stresses with small shape changes. Ceramics have certain characteristics that underlie shape memory transformation, but generally crack under strain. <jats:bold> Lai <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6153" page="1505" related-article-type="in-this-issue" vol="341" xlink:href="10.1126/science.1239745">1505</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="6153" page="1464" related-article-type="in-this-issue" vol="341" xlink:href="10.1126/science.1245097">Faber</jats:related-article> </jats:bold> ) introduce a modified ceramic structure with limited crystal grains that can withstand comparable cyclic strains to shape memory metals. </jats:p>

<jats:title>Futile Forest Fragments</jats:title> <jats:p> Most of the planet's terrestrial biodiversity is found in tropical forests, but much of this critical habitat now persists as fragmented patches surrounded by agriculture. Smaller forest patches sustain fewer species than larger patches or contiguous forest. However, the numbers of species that will disappear from a forest fragment—and the rate of species loss—remain poorly understood. <jats:bold> Gibson <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6153" page="1508" related-article-type="in-this-issue" vol="341" xlink:href="10.1126/science.1240495">1508</jats:related-article> ) surveyed islands in a reservoir in Thailand to measure the rate of loss of small mammals from small forest fragments. Collapse of the entire native community (up to 12 species) from 16 forest fragments was observed after 25 years of isolation. Thus, small forest fragments hold little value for mammalian biodiversity, and conservation efforts should instead focus on the preservation of large forest expanses. </jats:p>

<jats:title>Keeping Cells Cooperating</jats:title> <jats:p> Multicellular organisms have certain advantages over those that are single-celled. To evolve, however, they must surmount a persistent challenge: ensuring that their constituent cells cooperate with one another rather than “cheat” or compete with each other for resources. <jats:bold> Dejosez <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6153" page="1511" related-article-type="in-this-issue" vol="341" xlink:href="10.1126/science.1241628">1511</jats:related-article> , published online 12 September) performed a genome-wide screen in induced pluripotent stem cells to search for genes that promote cell cooperation. A number of genes were identified of which knockdown allowed competitive behavior to dominate. These genes formed a network centered on p53, topoisomerase 1, and olfactory receptors. Thus, a genetic mechanism may promote cooperation in the developing embryo. </jats:p>

<jats:title>Sourcing Antibiotic Resistance</jats:title> <jats:p> It is widely assumed that antibiotic resistance in farm animals contributes in a major way to antibiotic resistance in humans. <jats:bold> Mather <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6153" page="1514" related-article-type="in-this-issue" vol="341" xlink:href="10.1126/science.1240578">1514</jats:related-article> , published online 12 September; see the Perspective by <jats:related-article issue="6153" page="" related-article-type="in-this-issue" vol="341"> <jats:bold>Woolhouse and Ward</jats:bold> ) </jats:related-article> analyzed hundreds of genome sequences from <jats:italic>Salmonella</jats:italic> isolates collected from both livestock and patients in Scotland between 1990 and 2004. The relative contributions of animal-derived and human-derived sources of infection were quantified and the phylogenetic diversity of resistance profiles was matched with bacterial phylogenies. The results suggest that most human infections are caught from other humans rather than from livestock and that humans harbor a greater diversity of antibiotic resistance. </jats:p>

<jats:title>The Overeating Connection</jats:title> <jats:p> Obesity has become a major global health problem. Working in mice, <jats:bold> Jennings <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6153" page="1517" related-article-type="in-this-issue" vol="341" xlink:href="10.1126/science.1241812">1517</jats:related-article> ) identified an important brain circuit within the lateral hypothalamus that modulates food intake. The findings reveal the neuronal connections that drive the consumption of highly palatable food even when energy needs are satisfied. Inhibition of this circuit suppressed feeding. </jats:p>

<jats:title>Drugs, Dopamine, and Disinhibition</jats:title> <jats:p> Drugs often change the neuronal circuitry in the brain and thereby cause a long-lasting change in behavior. Using a wide range of in vivo and in vitro techniques in mice, <jats:bold> Bocklisch <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6153" page="1521" related-article-type="in-this-issue" vol="341" xlink:href="10.1126/science.1237059">1521</jats:related-article> ) observed that cocaine profoundly altered dopamine neuron function and that drug-evoked synaptic plasticity in a specific set of neurons represents a crucial step in circuit remodeling. </jats:p>

<jats:p> The 2014 Gordon Research Conference schedule was published on pages 1526 to 1536 of this issue of the print version of <jats:italic>Science</jats:italic> . The current schedule can also be found online at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.grc.org/">www.grc.org/</jats:ext-link> . </jats:p>

<jats:p>Listen to stories on taming mercury in the environment, news from the Curiosity rover, codon bias in bacterial genes, and more.</jats:p>

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>