Catálogo de publicaciones - revistas

<jats:title>Only the water may pass</jats:title> <jats:p> Removing objects by size to keep only the smallest ones is simple in theory, but it requires a sieve, membrane, or filter with holes small enough to allow only the smallest objects to pass. Gopinadhan <jats:italic>et al.</jats:italic> engineered two-dimensional water channels by removing an atomic plane of atoms from a sandwich made from bulk crystal with a graphene spacer. Water flowed through the channels without resistance, but the channels excluded all ions except for protons because the ion hydration shells could not squeeze through the channels. </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="6423" page="145" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aau6771">145</jats:related-article> </jats:p>

<jats:title>A photonic Weyl system by design</jats:title> <jats:p> Theoretically proposed exotic physics is now being explored and realized in condensed matter and photonic systems. Weyl physics arises when the valence band and conduction bands meet at discrete points in the band structure. Jia <jats:italic>et al.</jats:italic> designed and fabricated a photonic metamaterial in which the position of the Weyl points in momentum space could be tuned using a huge artificial magnetic field. Because these points are stable, the ability to design and control such a Weyl system with a robust chiral optical mode could be exploited in future optical information processing applications. </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="6423" page="148" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aau7707">148</jats:related-article> </jats:p>

<jats:title>Toward nanotubes with periodic gaps</jats:title> <jats:p> Carbon nanotubes consist of a continuous array of benzene rings fused along their edges. It is not straightforward to excise regular fragments in a top-down fashion to produce periodic gaps. Sun <jats:italic>et al.</jats:italic> showcase the beginnings of a bottom-up strategy toward this end. They used borylations and catalytic cross-coupling chemistry to prepare a discrete cylindrical carbon compound composed of 40 benzene rings bonded to one another at the 1, 3, and 5 positions to leave regular void spaces in the walls. Catenation of multiple similar segments could ultimately lead to an extended nanotube with periodic wall defects. </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="6423" page="151" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aau5441">151</jats:related-article> </jats:p>

<jats:title>Broken on impact</jats:title> <jats:p> Two competing models have been proposed for the adsorption of molecular hydrogen on platinum surfaces. Both invoke dissociation at surface defects but differ on whether hydrogen molecules diffuse along the surface before encountering a defect or adsorb only if they initially impact a defect site. Van Lent <jats:italic>et al.</jats:italic> studied the sticking of hydrogen molecules from a molecular beam scanned across a curved platinum single-crystal surface that varied in the density and type of defects exposed. Modeling of the results was consistent only with the second model invoking direct impact. </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="6423" page="155" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aau6716">155</jats:related-article> </jats:p>

<jats:title>Climbing vibrational levels</jats:title> <jats:p> Vibrational excitation of molecules adsorbed on a surface is usually limited because the vibrational energy is rapidly transferred into phonons, the vibrational modes of the substrate. Chen <jats:italic>et al.</jats:italic> found that this is not the case for CO molecules adsorbed on a surface of NaCl. The CO molecules efficiently transferred vibrational energy within groups of molecules from one high excitation state to another until they reached the dissociation limit. This process was possible because of the close proximity of the molecules and the limited transfer of energy to just one phonon mode in the salt surface. </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="6423" page="158" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aav4278">158</jats:related-article> </jats:p>

<jats:title>Mating disks and rods into an ordered phase</jats:title> <jats:p> Disk-shaped molecules tend to stack in columns, whereas rod-shaped ones tend to align parallel to each other. When the two types of molecules are mixed, they tend to phase separate. Yano <jats:italic>et al.</jats:italic> found the right recipe that allowed enough affinity between the disks and rods so that they formed a blended twisted columnar phase. The phase could be stabilized by polymerizing the disks. The orientation of the twisted columns could be altered using electric fields, whereas optical stimuli could lead to a second ordering transition. </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="6423" page="161" related-article-type="in-this-issue" vol="363" xlink:href="10.1126/science.aan1019">161</jats:related-article> </jats:p>