Catálogo de publicaciones - revistas

<jats:title>Single seismometer structure</jats:title> <jats:p> Because of the lack of direct seismic observations, the interior structure of Mars has been a mystery. Khan <jats:italic>et al.</jats:italic> , Knapmeyer-Endrun <jats:italic>et al.</jats:italic> , and Stähler <jats:italic>et al.</jats:italic> used recently detected marsquakes from the seismometer deployed during the InSight mission to map the interior of Mars (see the Perspective by Cottaar and Koelemeijer). Mars likely has a 24- to 72-kilometer-thick crust with a very deep lithosphere close to 500 kilometers. Similar to the Earth, a low-velocity layer probably exists beneath the lithosphere. The crust of Mars is likely highly enriched in radioactive elements that help to heat this layer at the expense of the interior. The core of Mars is liquid and large, ∼1830 kilometers, which means that the mantle has only one rocky layer rather than two like the Earth has. These results provide a preliminary structure of Mars that helps to constrain the different theories explaining the chemistry and internal dynamics of the planet. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abf2966, abf8966, abi7730, this issue p. <jats:related-article issue="6553" page="434" related-article-type="in-this-issue" vol="373">434</jats:related-article> , p. <jats:related-article issue="6553" page="438" related-article-type="in-this-issue" vol="373">438</jats:related-article> , p. <jats:related-article issue="6553" page="443" related-article-type="in-this-issue" vol="373">443</jats:related-article> see also abj8914, p. <jats:related-article issue="6553" page="388" related-article-type="in-this-issue" vol="373">388</jats:related-article> </jats:p>

<jats:title>Straining for high photoluminescence</jats:title> <jats:p> The photoluminescence quantum yield in monolayer transition metal dichalcogenides generally drops at high emission intensities because the excitons undergo nonradiative annihilation. Kim <jats:italic>et al.</jats:italic> show that this process is resonantly amplified in these materials by van Hove singularities in their joint density of states. However, application of small mechanical strains (∼0.5%) shifted the van Hove singularities and suppressed the nonradiative processes. Near-unity photoluminescence quantum yield at high exciton densities was seen in exfoliated monolayers of molybdenum sulfide, tungsten sulfide, and tungsten selenide, as well as centimeter-scale tungsten sulfide monolayers grown by chemical vapor deposition. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abi9193, this issue p. <jats:related-article issue="6553" page="448" related-article-type="in-this-issue" vol="373">448</jats:related-article> </jats:p>

<jats:title>Triplet-state lifetime quenched by oxygen</jats:title> <jats:p> Little is known about the atomistic mechanism that nature uses to mitigate the destructive interaction of triplet-excited pigment chromophores with omnipresent oxygen. Peng <jats:italic>et al.</jats:italic> tackled this challenge by developing a technique based on conducting atomic force microscopy to populate and track triplets in a single pentacene molecule, a model ϖ-conjugated system, placed on a sodium chloride surface (see the Perspective by Li and Jiang). The authors show how the triplet-state lifetime can be quenched in controllable manner by atomic-scale manipulations with oxygen co-adsorbed in close vicinity. The presented single-molecule spectroscopy paves the way for further atomically resolved studies of triplet excited states that play an important role in many other fields, such as organic electronics, photocatalysis, and photodynamic therapy. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abh1155, this issue p. <jats:related-article issue="6553" page="452" related-article-type="in-this-issue" vol="373">452</jats:related-article> ; see also abj5860, p. <jats:related-article issue="6553" page="392" related-article-type="in-this-issue" vol="373">392</jats:related-article> </jats:p>

<jats:title>Birds in the bin</jats:title> <jats:p> It is by now well accepted that humans are not the only animal to have complex culture, and we have also found that ecological novelty can lead to cultural innovation. Klump <jats:italic>et al.</jats:italic> documented the emergence of an evolving set of behaviors in response to human-generated resources, specifically garbage bins, in sulphur-crested cockatoos. This finding both documents the existence and spread of complex foraging culture among parrots, a lineage known for high-level cognitive function, and illuminates how the spread of a cultural innovation can lead to regional distinct variations. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , abe7808, this issue p. <jats:related-article issue="6553" page="456" related-article-type="in-this-issue" vol="373">456</jats:related-article> </jats:p>

<jats:title>More VEGF, more life—and health span</jats:title> <jats:p> Advanced aging is celebrated but its ill effects, deterioration at the cell, tissue, and organ levels, are not. Grunewald <jats:italic>et al</jats:italic> . provide evidence for the vascular theory of aging, which reports that age-related decrease of vascular function is a driver of organismal aging at large (see the Perspective by Augustin and Kipnis). Vascular endothelial growth factor (VEGF) signaling insufficiency underlies this vascular insufficiency in aged mice. A modest compensatory increase in circulatory VEGF was sufficient to preserve a young-like vascular homeostasis, alleviate multiple adverse age-related processes, and ameliorate a host of age-associated pathologies in mice. —BAP </jats:p>

<jats:title>Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women</jats:title> <jats:p> Yoshino <jats:italic>et al</jats:italic> . (Reports, 11 June 2021, p. 1224) have reported that nicotinamide mononucleotide (NMN) increases muscle insulin sensitivity in prediabetic women. However, the 13 women who received NMN had hepatic lipid content of 6.3 ± 1.2%, whereas the 12 in the placebo group had 14.8 ± 2.0% ( <jats:italic>P</jats:italic> = 0.003). Given that a target of NMN is liver fat clearance, this was not an effectively randomized trial. </jats:p>

<jats:title>Back to the future phage</jats:title> <jats:p> The interrelationships that prevail between bacteria and their phage parasites are subtle and evolutionarily dynamic. In Bangladesh, cholera remains endemic, and natural, clinically relevant infections have been monitored for decades. LeGault <jats:italic>et al</jats:italic> . investigated the relationship between antiphage defenses and phage counterresponses in human <jats:italic>Vibrio cholerae</jats:italic> cases. These bacteria have integrative and conjugative elements called SXT ICEs, which are notorious for carrying antibiotic resistance genes but also contain genes that defend bacteria from phage. Phage have their own counterdefense mechanisms. One constitutes a 44–amino acid peptide product in a phage lineage that inhibits the bacterium’s SXT ICE defenses. In a further complication, SXT-ICEs also inhibit the lysogenic phage that transmit <jats:italic>Vibrio</jats:italic> virulence factors, including cholera toxin. Therefore, this process drives bacterial diversity as well as antibiotic resistance. —CA </jats:p>

<jats:title>Sweat out the fat with TSLP!</jats:title> <jats:p> Thymic stromal lymphopoietin (TSLP) is a cytokine that can promote immune responses that characterize allergic diseases. Choa <jats:italic>et al</jats:italic> . found that mice engineered to produce elevated TSLP displayed selective white adipose tissue loss that protected them from obesity, insulin resistance, and steatohepatitis (see the Perspective by Schneider). Protection was not mediated by eosinophils, regulatory T cells, or innate lymphoid cells. Rather, TLSP induced the migration of conventional T cells to sebaceous glands in the skin. Once there, these T cells promoted white adipose tissue loss by the hypersecretion of sebum, a lipid-rich substance that augments the skin’s barrier function. This mechanism, which likely evolved to enhance cutaneous antimicrobial defenses, could be possibly targeted in future treatments for obesity. —STS </jats:p>

<jats:title>Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women</jats:title> <jats:p>In evaluating any randomized clinical trial, it is important to determine whether baseline differences between groups could have affected the primary outcome. In our study, muscle insulin sensitivity, which was identical in both groups at baseline, improved after nicotinamide mononucleotide (NMN), not placebo, therapy. Differences in baseline intrahepatic triglyceride content between groups do not negate the effects of NMN observed in muscle.</jats:p>