Catálogo de publicaciones - revistas

<jats:title>Ironing on hydroxyls</jats:title> <jats:p> Although iron-dependent enzymes efficiently hydroxylate aryl rings, this activity has proven hard to replicate with synthetic catalysts. Cheng <jats:italic>et al</jats:italic> . report that a disulfide ligand activates iron to catalyze carbon–hydrogen hydroxylation of a wide variety of arenes using hydrogen peroxide. The protocol can also cleanly functionalize phenols with an additional hydroxyl group, although unfunctionalized arenes react more rapidly, in contrast to conventional oxidative selectivity patterns. The authors showcase this complementary selectivity through hydroxylation of pharmaceuticals with complex substitution patterns. —JSY </jats:p>

<jats:title>From polarons to a Fermi liquid</jats:title> <jats:p> Superconductivity in the cuprates emerges by doping an antiferromagnetic “parent” state with holes or electrons. With increased doping, antiferromagnetism gives way to unconventional superconductivity, and the system eventually becomes a Fermi liquid. Koepsell <jats:italic>et al</jats:italic> . simulated this progression using cold, strongly interacting lithium-6 atoms trapped in an optical lattice. Although the equivalent ordered phases are not yet reachable at the experimentally available temperatures, the researchers were able to measure multipoint spin and hole correlations over a wide range of hole doping. The evolution of these correlators with doping revealed a crossover from a polaronic regime to a Fermi liquid. —JS </jats:p>

<jats:title>Far away landslide detection</jats:title> <jats:p> A mass wasting and flood event on 7 February 2021 in Uttarakhand, India, killed more than 200 people and damaged two hydropower plants. Cook <jats:italic>et al</jats:italic> . discovered that teleseimic signals from the beginning of this event were recorded at different stations on a regional seismic network in northern India. The signals were observed up to 100 kilometers from the disaster and demonstrate the potential for these far-away monitoring stations to be useful for early warning. This discovery suggests a different way to monitor such remote Himalayan valleys for mass wasting hazards. —BG </jats:p>

<jats:title> Capturing OH(H <jats:sub>3</jats:sub> O <jats:sup>+</jats:sup> ) in ionized water </jats:title> <jats:p> Recent advances in liquid-phase ultrafast electron diffraction techniques make it possible to observe what has only been theoretically presumed to occur at short times upon interaction of ionizing radiation with liquid water. Lin <jats:italic>et al</jats:italic> . provide direct evidence for capturing the short-lived radical-cation pair OH(H <jats:sub>3</jats:sub> O <jats:sup>+</jats:sup> ), which has been hypothesized for years to form after ionization of liquid water but was not structurally resolved previously (see the Perspective by Cao <jats:italic>et al</jats:italic> .). The authors trace dissociation and subsequent nonradiative structural relaxation around the ionization center. —YS </jats:p>

<jats:title>Densification via bridging layers</jats:title> <jats:p> MXenes are a family of layered two-dimensional metal carbides and nitrides with interesting properties that can be lost if voids are formed during synthesis. By using a sequential combination of hydrogen and covalent bonding agents, Wan <jats:italic>et al</jats:italic> . were able to densify the layered structure and remove voids. This procedure leads to improvements in the mechanical strength and toughness, electrical conductivity, and shielding from electromagnetic interference. —MSL </jats:p>

<jats:title>Minimal domains for maximum energy</jats:title> <jats:p> Dielectric capacitors are important electronic components that can store energy, at least for a short period of time. Pan <jats:italic>et al</jats:italic> . used phase-field simulations to help determine the right combination of bismuth iron oxide, barium titanium oxide, and samarium doping that is likely to generate a material with excellent dielectric properties (see the Perspective by Chu). The simulations guide a set of experimental measurements showing this system can produce a very high-energy storage by breaking down polar domains to the nanometer scale. These materials could be useful for high-power applications and to suppress failure. —BG </jats:p>

<jats:title>Persistence of acute viruses</jats:title> <jats:p> How do highly contagious viruses that cause acute infections hang on to cause recurrent problems in a population? It should be expected that such infections would fade out as herd immunity develops, but foot and mouth disease virus (FMDV) can reemerge. Jolles <jats:italic>et al</jats:italic> . explored how FMDV remains endemic in African buffalo and serves as a reservoir for disease in domestic livestock (see the Perspective by Hampson and Haydon). The authors found that the virus persists in the population in carrier animals. Inconspicuous, rare, and sporadic transmission rescues the virus from fade-out, assisted by antigenic shift and the seasonal birth of susceptible calves. —CA </jats:p>

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

<jats:title>Resilience to tipping points in ecosystems</jats:title> <jats:p> Spatial pattern formation has been proposed as an early warning signal for dangerous tipping points and imminent critical transitions in complex systems, including ecosystems. Rietkerk <jats:italic>et al</jats:italic> . review how ecosystems and Earth system components can actually evade catastrophic tipping through various pathways of spatial pattern formation. With mathematical and real-world examples, they argue that evading tipping and enhancing resilience could be relevant for many ecosystems and Earth system components that until now were known as tipping prone. Many of these complex systems may be more resilient than currently thought because of overlooked spatial dynamics and multiple stable states, and may thus not undergo critical or catastrophic transitions with global change. —AMS </jats:p>