Catálogo de publicaciones - revistas

<jats:title>Pinpointing proteins</jats:title> <jats:p> To develop drugs that target a specific cell surface protein, it's helpful to know which other proteins reside in its vicinity. Geri <jats:italic>et al.</jats:italic> report a light-triggered labeling technique that improves the spatial resolution for this type of mapping. Specifically, they rely on a photocatalyst with a very short energy-transfer range to activate a carbene-based label that can only diffuse a short distance in water before reacting. They showcase the technique by mapping the environment of the programmed-death ligand 1 (PDL1) protein on B cell surfaces, a system of considerable interest in cancer immunotherapy. </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="6482" page="1091" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aay4106">1091</jats:related-article> </jats:p>

<jats:title>Tuning band gaps with three halides</jats:title> <jats:p> Tandem solar cells can boost solar cell efficiency by using two active layers to absorb the solar spectrum more completely, provided that the two cells are current-matched. Inorganic-organic perovskites tuned to the appropriate wide band gap (∼1.7 electron volts) as top cells that contained iodine and bromine or bromine and chlorine have short carrier diffusion lengths and undergo photo-induced phase segregation. Xu <jats:italic>et al.</jats:italic> now report a method for incorporating chloride that allows for fabrication of stable triple-halide perovskites with a band gap of 1.67 electron volts. Two-terminal tandem silicon solar cells made with this material had a power conversion efficiency of 27%. </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="6482" page="1097" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz5074">1097</jats:related-article> </jats:p>

<jats:title>A major psychosocial stress circuit</jats:title> <jats:p> Psychological stress induces various physiological responses by activating the sympathetic nervous system. The brain circuits involved in these functions are still not completely understood. In a rat model, Kataoka <jats:italic>et al.</jats:italic> combined anatomical tracing, immediate early gene expression analysis, pharmacology, optogenetics, electrophysiology, and genetic cell ablation to provide evidence for the prominent role of a ventral part of the medial prefrontal cortex in sympathetic responses to social defeat stress. This brain region sends excitatory projections to the dorsomedial hypothalamus as a central coordinator of the psychosocial stress responses. This pathway is crucial for understanding how psychosocial stress influences a variety of body functions. </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="6482" page="1105" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz4639">1105</jats:related-article> </jats:p>

<jats:title>Diversity from development</jats:title> <jats:p> When given a line to follow, some fruit flies do so carefully and others weave. Linneweber <jats:italic>et al.</jats:italic> now show that these behaviors are stable for an individual but diverse in an isogenic population. Key to generating individual diversity in the population is the inherent chaos of normal development. A set of neurons in the visual system is wired up in a variable manner, resulting in brain circuit asymmetry unique to each fly that guides its line-walking behavior. With more asymmetry in its brain circuit, a fly is better able to orient to the line. </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="6482" page="1112" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaw7182">1112</jats:related-article> </jats:p>

<jats:title>Watching defects flow and grow</jats:title> <jats:p> Orientational topological defects in liquid crystals, known as disclinations, have been visualized in polymeric materials or through mesoscale simulations of the local orientation of the molecules. Duclos <jats:italic>et al.</jats:italic> report the experimental visualization of the structure and dynamics of disclination loops in active, three-dimensional nematics using light-sheet microscopy to watch the motion of nematic molecules driven by the motion of microtubule bundles (see the Perspective by Bartolo). This setup makes it possible to directly watch the nucleation, deformation, recombination, and collapse of spatially extended topological defects in three dimensions. </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="6482" page="1120" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz4547">1120</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6482" page="1075" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba5319">1075</jats:related-article> </jats:p>

<jats:title>Seeing single silicon atom vibrations</jats:title> <jats:p> Vibrational spectroscopy can achieve high energy resolution, but spatial resolution of unperturbed vibrations is more difficult to realize. Hage <jats:italic>et al.</jats:italic> show that a single-atom impurity in a solid (a silicon atom in graphene) can give rise to distinctive localized vibrational signatures. They used high-resolution electron energy-loss spectroscopy in a scanning transmission electron microscope to detect this signal. An experimental geometry was chosen that reduced the relative elastic scattering contribution, and repeated scanning near the silicon impurity enhanced the signal. The experimental vibration frequencies are in agreement with ab initio calculations. </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="6482" page="1124" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba1136">1124</jats:related-article> </jats:p>

<jats:title>Gauge invariance with cold atoms</jats:title> <jats:p> There is considerable interest in developing quantum computational technologies that can simulate a series of physical phenomena inaccessible by classical computers. Mil <jats:italic>et al.</jats:italic> propose a modular scheme for quantum simulation of a U(1) lattice gauge theory based on heteronuclear spin-changing collisions in a mixture of two bosonic quantum gases isolated in single wells of a one-dimensional optical lattice. They engineered the elementary building block for a single well and demonstrate its reliable operation that preserves the gauge invariance. The potential for scalability of the proposed scheme opens up opportunities to address challenges in quantum simulating the continuum limit of the gauge theories. </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="6482" page="1128" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz5312">1128</jats:related-article> </jats:p>

<jats:title>Human brain activity during memory</jats:title> <jats:p> Animal studies suggest that sequence replay of neuronal activity may underlie memory retrieval and consolidation. However, there is no direct evidence that the replay of spiking activity sequences is important for these processes in the human brain. Vaz <jats:italic>et al.</jats:italic> simultaneously recorded single-unit spikes, local field potential, and intracranial electroencephalography signals in the brain while participants performed a memory task. Sharp wave ripple oscillations in the temporal lobe cortex reflected bursts of neural spiking, and these bursts of spikes organized into sequences during memory formation. These sequences were replayed during successful memory retrieval. The extent of sequence replay during correct recall was related to the extent to which cortical spiking activity was coupled with ripples in the medial temporal lobe. </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="6482" page="1131" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba0672">1131</jats:related-article> </jats:p>

<jats:title>Growing perovskite on textured silicon</jats:title> <jats:p> Wide–band gap perovskites could boost the efficiency of silicon solar cells by forming tandem cells, but usually the perovskite must be grown on a smoothed side of the silicon cell because the material grown on the rough light-trapping side often does not fully coat the silicon surface and its rough texture is prone to phase separation. Hou <jats:italic>et al.</jats:italic> grew thick films of a perovskite with a band gap of ∼1.68 electron volts and used a passivant, 1-butanethiol, to limit its phase separation. The tandem cells had a certified power conversion efficiency of 25.7% and had negligible losses after 400 hours of operation. </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="6482" page="1135" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz3691">1135</jats:related-article> </jats:p>