Catálogo de publicaciones - revistas

<jats:title>Silicon smooths the way to vinyl cations</jats:title> <jats:p> Saturated carbon centers often undergo substitution reactions by initial cleavage of a carbon-halogen or carbon-oxygen bond, which leaves the carbon positively charged. Analogous cations have proven much harder to access from vinylic carbons that are engaged in double bonds. Popov <jats:italic>et al.</jats:italic> now show that silicon cations paired with noncoordinating anions can pull triflate groups off such vinylic carbons under ambient conditions (see the Perspective by Kennedy and Klumpp). The resultant vinyl cations react with simple alkanes through C–H insertion. Theoretical and mechanistic studies suggest that these reactions proceed through nonclassical pathways that bifurcate after the transition 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="6400" page="381" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aat5440">381</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6400" page="331" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aau0809">331</jats:related-article> </jats:p>

<jats:title>Cooler electrons for transistors</jats:title> <jats:p> The operating power of field-effect transistors is constrained in part by the minimum change in voltage needed to change the current output. This subthreshold swing (SS) limit is caused by hotter electrons from a thermal electron source leaking over the potential of the gate electrode. Qiu <jats:italic>et al.</jats:italic> show that graphene can act as a Dirac source that creates a narrower distribution of electron energies. When coupled to a carbon nanotube channel, the decrease in SS would allow the supply voltage to be decreased from 0.7 to 0.5 volts. </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="6400" page="387" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aap9195">387</jats:related-article> </jats:p>