Catálogo de publicaciones - revistas

<jats:title>Iron links a trio</jats:title> <jats:p> Iron holds particular appeal as a catalytic metal—it is safe and abundant, as well as a mainstay of enzymatic reactivity. Nonetheless, in synthetic construction of carbon-carbon bonds, modern chemists have largely had to rely on rarer metals such as palladium. Liu <jats:italic>et al</jats:italic> . now report that coordination of iron by a bulky chelating phosphine ligand enables efficient mutual coupling of three different reactants—an alkyl halide, an aryl Grignard, and an olefin—to form two carbon-carbon bonds (see the Perspective by Lefèvre). A combination of Mössbauer spectroscopy, crystallography, and computational simulations illuminates the mechanism. —JSY </jats:p>

<jats:title>Locking down access to the brain</jats:title> <jats:p> Inflammatory bowel disease is best known for intestinal symptoms but can also cause a variety of extraintestinal manifestations in other organs. It can also be associated with cognitive and psychiatric effects, including anxiety and depression. Using mouse models of intestinal inflammation, Carloni <jats:italic>et al</jats:italic> . uncovered a potential pathogenic link between these aspects of inflammatory bowel disease. The inflammatory process causes the gut vascular barrier to become more permeable, resulting in the spread of inflammation beyond the intestine, while the vascular barrier in the choroid plexus shuts down, helping protect the brain from inflammation but also potentially impairing communication between organs and impairing some brain functions. —YN </jats:p>

<jats:title>Metasurfaces tune polarization</jats:title> <jats:p> In photonic systems, the polarization state of light is typically manipulated with bulky components based on dielectrics and liquid crystals. Active metasurfaces now provide the possibility of shrinking the size of these components to the nanoscale. Biswas <jats:italic>et al</jats:italic> . demonstrate an active nanophotonic structure capable of versatile electro-optic polarization conversion. Using trilayer black phosphorus sandwiched between electrical gates forming a cavity, they show that the polarization state of light across telecommunication wavelengths can be electrically switched. Such control can be useful for a number of applications in communications, imaging, and beam steering where the wavefront of the propagating light can be actively manipulated. —ISO </jats:p>

<jats:title>Designing water uptake</jats:title> <jats:p> Although the locations of water molecules in some porous materials have been determined with diffraction techniques, determining the filling sequence of water sites has been challenging. Hanikel <jats:italic>et al</jats:italic> . used single-crystal x-ray diffraction to locate all of the water molecules in pores of the metal-organic framework MOF-303 at different water loadings (see the Perspective by Öhrström and Amombo Noa). They used this information on the water molecule adsorption sequence to modify the linkers of this MOF and control the water-harvesting properties from humid air for different temperature regimes. —PDS </jats:p>

<jats:title>Sulfur-stabilized intermetallic nanoparticles</jats:title> <jats:p> Nanoparticles of intermetallic alloys of platinum could have enhanced electronic properties that improve their catalytic activity, but the high temperatures needed to ensure complete atomic diffusion often lead to the growth of larger nanoparticles—sintering—with low surface area and hence low overall activity. Yang <jats:italic>et al</jats:italic> . show that sulfur-doped carbon supports create strong platinum-sulfur bonds that stabilize small platinum alloy nanoparticles (&lt;5 nanometers in diameter) to temperatures up to 1000ºC. They screened libraries of platinum alloys and identified ones with high mass activity for the oxygen reduction reaction in hydrogen fuel cells. —PDS </jats:p>

<jats:title>Turning wood into honeycombs</jats:title> <jats:p> Wood is an attractive material for structural applications, but it usually works best as boards or sheets. Xiao <jats:italic>et al</jats:italic> . have developed a process for engineering hardwood that allows these sheets to be manipulated into complex structures (see the Perspective by Tajvidi and Gardner). The key is to manipulate the cell wall structure by shrinking and blasting open the fibers and vessels by drying and “water-shocking” them. This process creates a window wherein the wood can be manipulated without ripping or tearing. Honeycomb, corrugated, or other complex structures are locked in once the wood dries. —BG </jats:p>

<jats:title>Community of antibodies against COVID-19</jats:title> <jats:p> The severe acute respiratory syndrome coronavirus 2 spike protein is the basis of many vaccines and is a primary target of neutralizing antibodies after COVID-19 infection. The Coronavirus Immunotherapeutic Consortium (CoVIC), comprising 56 partners across the world, has analyzed a panel of 269 monoclonal antibodies (mAbs) and, on the basis of competition profiles, sorted 186 mAbs that target the receptor binding domain into seven communities. Hastie <jats:italic>et al</jats:italic> . went on to structurally analyze representative antibody binding and used pseudovirus neutralization assays to study the effect of spike mutations on antibody function, including the combinations of mutations found in certain variants of concern. These results are important to guide both treatment and prevention efforts. —VV </jats:p>

<jats:title>Fine-scale strengthening swirls</jats:title> <jats:p> Creatively combining different alloys using additive manufacturing methods has the potential to produce materials with interesting properties. Zhang <jats:italic>et al</jats:italic> . use laser powder bed fusion to combine small amounts of 316L stainless steel into Ti64 titanium alloy. This process creates an alloy with a distinctive microstructure that retains high strength while substantially improving ductility. The design strategy should be useful for improving mechanical properties in other alloy system as well. —BG </jats:p>

<jats:title>Lose the tusks</jats:title> <jats:p> Harvest and poaching of wildlife have increased as the human population and our technology have grown. These pressures now occur on such a scale that they can be considered selective drivers. Campbell-Staton <jats:italic>et al</jats:italic> . show that this phenomenon has occurred in African elephants, which are poached for their ivory, during the 20-year Mozambican civil war (see the Perspective by Darimont and Pelletier). In response to heavy poaching by armed forces, African elephant populations in Gorongosa National Park declined by 90%. As the population recovered after the war, a relatively large proportion of females were born tuskless. Further exploration revealed this trait to be sex linked and related to specific genes that generated a tuskless phenotype more likely to survive in the face of poaching. —SNV </jats:p>

<jats:title>Wild phage evolution</jats:title> <jats:p> Bacteria possess a diversity of highly specific phage defense mechanisms that evolve rapidly and that account for a large proportion of bacterial genomes. These dynamics must be understood if phage therapy is to be seriously considered for clinical use. Hussain <jats:italic>et al</jats:italic> . studied a set of nearly clonal wild-caught <jats:italic>Vibrio lentus</jats:italic> hosts and their phage and found that the hosts segregated into two groups infected by different viruses (see the Perspective by Meaden and Fineran). Puzzlingly, both host groups have the same surface phage receptors. This apparent paradox was resolved by sequencing of the hosts, which revealed distinct suites of endogenous but mobile phage defense elements (PDEs) in the two host phenotypes. Indeed, the PDEs constitute a large fraction of the flexible noncore genome of the bacteria. This means the PDEs can evolve and transfer from cell to cell without interfering with metabolic processes required to synthesize essential cell surface molecules. —CA </jats:p>