Catálogo de publicaciones - revistas

<jats:title>Routes to independent vessel networks</jats:title> <jats:p> In air-breathing vertebrates, the circulatory and pulmonary systems contain separate networks of channels that intertwine but do not intersect with each other. Recreating such structures within cell-compatible materials has been a major challenge; even a single vasculature system can be a burden to create. Grigoryan <jats:italic>et al.</jats:italic> show that natural and synthetic food dyes can be used as photoabsorbers that enable stereolithographic production of hydrogels containing intricate and functional vascular architectures. Using this approach, they demonstrate functional vascular topologies for studies of fluid mixers, valves, intervascular transport, nutrient delivery, and host engraftment. </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="6439" page="458" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aav9750">458</jats:related-article> </jats:p>

<jats:title>Slip outraces the fluids</jats:title> <jats:p>Earthquakes generated from fluid injections sometimes appear to occur much faster than would be expected from the speed of fluid migration. Bhattacharya and Viesca used observations from a controlled fluid injection to develop a model to understand the behavior of fluids and aseismic slip. They found that the aseismic slip outpaced the fluid migration, allowing for earthquake triggering to happen much faster and farther away from the initial fluid injection.</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="6439" page="464" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw7354">464</jats:related-article> </jats:p>

<jats:title>Electrostatic doping boosts emission</jats:title> <jats:p> Although monolayers of transition-metal dichalcogenides such as molybdenum disulfide (MoS <jats:sub>2</jats:sub> ) and tungsten disulfide (WS <jats:sub>2</jats:sub> ) should exhibit strong photoluminescence, in practice, defects in these materials can lead to very low quantum yields (less than 1%). Lien <jats:italic>et al.</jats:italic> show that as-formed MoS <jats:sub>2</jats:sub> and WS <jats:sub>2</jats:sub> monolayers encapsulated in poly(methyl methacrylate) can be electrostatically doped to achieve quantum yields near unity. Under these conditions, instead of charged trion species that recombine nonradiatively, only neutral excitons that recombine emissively form. These results help explain why coating these materials with certain Lewis acids also boosts the quantum yield. </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="6439" page="468" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw8053">468</jats:related-article> </jats:p>

<jats:title>Protons venture into the inverted region</jats:title> <jats:p> One of the most counterintuitive features of electron transfer kinetics is the inverted region. As Marcus theory predicts and experiments have borne out, electron transfer slows down once the driving force for it becomes especially favorable. Parada <jats:italic>et al.</jats:italic> now offer evidence for such inverted behavior in proton-coupled electron transfer (see the Perspective by Dempsey). Specifically, they examined a series of compounds with phenol bridging anthracene (electron acceptor) and pyridine (proton acceptor) derivatives. Time-resolved spectroscopy and accompanying theory revealed slower rates at higher driving forces in the back reaction that follows light-induced intramolecular proton and electron transfer. </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="6439" page="471" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw4675">471</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6439" page="436" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw9900">436</jats:related-article> </jats:p>

<jats:title>Efficient all-perovskite tandem cells</jats:title> <jats:p> Organic-inorganic perovskite films can boost the output of conventional silicon solar cells in tandem geometries by utilizing more of the light at the blue end of the solar spectrum. Tandem cells that use only perovskite films have been less successful because of the lack of a suitable material with a low bandgap that can replace silicon. Tong <jats:italic>et al.</jats:italic> report that a mixed tin-lead organic-inorganic material containing a small fraction of guanidinium thiocyanate has a low bandgap, long charge-carrier lifetime, and efficiencies around 25%. </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="6439" page="475" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aav7911">475</jats:related-article> </jats:p>

<jats:title>Structure-based immunogen design</jats:title> <jats:p> Vaccine design for highly mutable pathogens is hindered by a paucity of conserved immunogenic epitopes. Gaiha <jats:italic>et al.</jats:italic> employed a structure-based technique using network theory to assign scores to protein structure in order to infer mutational constraints (see the Perspective by McMichael and Carrington). The authors validated the method on proteins with published functional outcomes and then assessed mutational constraints within the HIV proteome. Highly networked residues strongly associated with immune control of HIV infection and may lead to protective immunogens for pathogens for which there is currently no efficient vaccine. </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="6439" page="480" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aav5095">480</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6439" page="438" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aax4989">438</jats:related-article> </jats:p>

<jats:title>High mutational load gets a response</jats:title> <jats:p> Cancers harbor many genetic mutations. Defects in DNA mismatch repair prevent tumors from repairing certain types of DNA damage and lead to a hypermutable genomic state known as microsatellite instability (MSI). Some tumors with a high degree of MSI may be treatable with PD-1 (programmed cell death–1) immunotherapy, but patient response is highly variable. Mandal <jats:italic>et al.</jats:italic> studied drivers of differential response to immunotherapy in these patients and found that MSI intensity and insertion-deletion mutations strongly affected therapeutic outcome. </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="6439" page="485" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aau0447">485</jats:related-article> </jats:p>

<jats:title>Integrated stress response on the brain</jats:title> <jats:p> During translation, regulation of protein synthesis by phosphorylation of eukaryotic translation initiation factor 2 (eIF2) is a common consequence of diverse stress stimuli, which leads to reprogramming of gene expression. This process, known as the integrated stress response, is one of the most fundamental mechanisms of translational control conserved throughout eukaryotes. It is also a promising therapeutic target in neurodegenerative diseases and traumatic brain injury. Kashiwagi <jats:italic>et al.</jats:italic> report the cryo–electron microscopy and crystal structures and Kenner <jats:italic>et al.</jats:italic> report the cryo–electron microscopy structure of the guanine nucleotide exchange factor eIF2B in complex with eIF2 or phosphorylated eIF2. The structures of the eIF2•eIF2B complex reveal that the single phosphorylation modification on eIF2 changes how eIF2 binds to eIF2B and locks this enzyme into an inhibited complex. </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="6439" page="495" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw4104">495</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6439" page="491" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw2922">491</jats:related-article> </jats:p>

<jats:title>Integrated stress response on the brain</jats:title> <jats:p> During translation, regulation of protein synthesis by phosphorylation of eukaryotic translation initiation factor 2 (eIF2) is a common consequence of diverse stress stimuli, which leads to reprogramming of gene expression. This process, known as the integrated stress response, is one of the most fundamental mechanisms of translational control conserved throughout eukaryotes. It is also a promising therapeutic target in neurodegenerative diseases and traumatic brain injury. Kashiwagi <jats:italic>et al.</jats:italic> report the cryo–electron microscopy and crystal structures and Kenner <jats:italic>et al.</jats:italic> report the cryo–electron microscopy structure of the guanine nucleotide exchange factor eIF2B in complex with eIF2 or phosphorylated eIF2. The structures of the eIF2•eIF2B complex reveal that the single phosphorylation modification on eIF2 changes how eIF2 binds to eIF2B and locks this enzyme into an inhibited complex. </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="6439" page="495" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw4104">495</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6439" page="491" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aaw2922">491</jats:related-article> </jats:p>

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