Catálogo de publicaciones - revistas

<jats:title>Nuclear organization in the brain</jats:title> <jats:p> The brain consists of different cell types, neurons and glial cells, that have different nuclear architecture. Takei <jats:italic>et al</jats:italic> . used multiplexed imaging tools to examine the spatial arrangement of more than 3000 DNA loci, along with epigenetic marks and gene expression patterns, simultaneously in the same single cells in mouse brain cortex. They observed features that are conserved across cell types, as well as cell-type-dependent spatial arrangements at the megabase level. At the level of tens of kilobases, they observed similar single-cell chromosome domain conformations in both active and inactive X chromosomes that are averaged out in population-based measurements. —DJ </jats:p>

<jats:title>Circulating in the sunlit ocean</jats:title> <jats:p> Marine plankton, which lie at the base of oceanic food chains, drive global biogeochemical fluxes, and knowledge of their distribution is key to understanding the response of oceans to environmental changes. Sommeria-Klein <jats:italic>et al</jats:italic> . explored the patterns and drivers of biogeography in eukaryotic plankton using a probabilistic model of taxon co-occurrence to compare the biogeography of 70 major groups, including a variety of size fractions and ecologies. The analysis is based on metabarcoding data from 129 stations in several oceanic provinces worldwide. Samples are from sunlit surface waters and, in about half of the stations, from the deep chlorophyll maximum. An essential message is that small phototrophs distribute mostly by latitude and bigger consumers are partitioned by ocean basin. —CA </jats:p>

<jats:title>Muddied waters</jats:title> <jats:p> The climate of High Mountain Asia is becoming warmer and wetter. Li <jats:italic>et al</jats:italic> . present data showing that rivers originating in this region have experienced large increases in runoff and sediment fluxes over the past six decades, most dramatically since the mid-1990s. The authors project that sediment flux from those rivers could more than double by 2050 in the case of extreme climate change, with potentially serious impacts on the region’s hydropower capacity, food security, and environment. —HJS </jats:p>

<jats:title>Polyethylene with a nickel’s worth of CO</jats:title> <jats:p> The biggest problem with polyethylene, the most abundantly manufactured plastic, is that it doesn’t break down easily once it is discarded. Chemists have long sought to introduce small quantities of carbon monoxide (CO) into polyethylene chains to promote photodegradation, but too much CO tends to jump in and spoil the plastic’s other properties. Baur <jats:italic>et al</jats:italic> . report that nickel catalysts coordinated by bulky phosphinophenolate ligands can catalyze ethylene polymerization with approximately 1% CO incorporation, preserving tensile strength while promoting degradation under ultraviolet exposure (see the Perspective by Sobkowicz). —JSY </jats:p>

<jats:title>Measuring the effective charge</jats:title> <jats:p> At low enough temperatures, superconductors are capable of conducting electricity without any resistance because of the formation of so-called Cooper pairs of electrons. Cooper pairs typically form at the same critical temperature at which superconductivity sets in. In certain materials, they are thought to form above that temperature, but showing this property directly in an experiment is tricky. Bastiaans <jats:italic>et al</jats:italic> . used tunneling noise spectroscopy to measure the effective charge of current carriers in the disordered superconductor titanium nitride. As expected, below the critical temperature, the effective charge was equal to two electron charges. However, this behavior persisted above the critical temperature, indicating that electron pairs exist in that regime. —JS </jats:p>

<jats:title>Switching a polymer</jats:title> <jats:p> Electrically switchable metasurfaces and plasmonic materials will enable the development of active nanophotonic technology. Karst <jats:italic>et al</jats:italic> . show that a metallic polymer can be used for electrical switching of plasmonic nanoantenna resonances. The plasmonic resonance can be completely switched ON and OFF with switching speeds up to 30 hertz (video rate), low switching voltages of ±1 volt (complementary metal-oxide semiconductor compatible), and a switching contrast of 100%. The results could have applications in nanophotonic devices such as those used in augmented and virtual reality imaging applications. —ISO </jats:p>

<jats:title>Taking the measure of a magnet</jats:title> <jats:p> The recent discovery of magnetism in two-dimensional (2D) materials has inspired efforts to understand its nature. Whereas the magnetism of monolayers of chromium iodide (CrI <jats:sub>3</jats:sub> ) can be understood in terms of out-of-plane magnetic anisotropy, the related material chromium chloride (CrCl <jats:sub>3</jats:sub> ) has spins that lie in the plane. Bedoya-Pinto <jats:italic>et al</jats:italic> . used molecular beam epitaxy to grow monolayers of CrCl <jats:sub>3</jats:sub> on graphene and studied its magnetic properties. Using x-ray magnetic circular dichroism measurements, the authors found that monolayer CrCl <jats:sub>3</jats:sub> is a ferromagnet, unlike bulk CrCl <jats:sub>3</jats:sub> , which is antiferromagnetic. The scaling of the signal in the critical region indicated that the material belongs to the 2D-XY universality class, distinct from Ising magnetism, which some other 2D magnets exhibit. —JS </jats:p>

<jats:title>Stable emission in glass</jats:title> <jats:p> Lead halide perovskites can exhibit bright, narrow band photoluminescence but have stability issues related to formation of inactive phases and the loss of lead ions. Hou <jats:italic>et al</jats:italic> . show that the black, photoactive phase of cesium lead iodide can be stabilized by forming a composite with a glassy phase of a metal-organic framework through liquid-phase sintering. The photoluminescence is at least two orders of magnitude greater than that of the pure perovskite. The glass stabilizes the perovskite under high laser excitation, and about 80% of the photoluminescence was maintained after 10,000 hours of water immersion. —PDS </jats:p>

<jats:title>Nodulation regulation</jats:title> <jats:p> Legumes convert atmospheric nitrogen into biologically useful ammonium with the help of symbiotic bacteria housed in root nodules. Much of nodule development is controlled by the transcription factor NODULE INCEPTION (NIN). Feng <jats:italic>et al</jats:italic> . show that NIN is proteolytically processed to release a fragment that regulates the later stages of nodulation when the nodules acquire nitrogen-fixing capability. In related work, Jiang <jats:italic>et al</jats:italic> . identified members of the NIN-like protein (NLP) transcription factor family as being regulators of leghemoglobin expression acting through an unusual promotor motif shared across legumes. —PJH </jats:p>

<jats:title>Nodulation regulation</jats:title> <jats:p> Legumes convert atmospheric nitrogen into biologically useful ammonium with the help of symbiotic bacteria housed in root nodules. Much of nodule development is controlled by the transcription factor NODULE INCEPTION (NIN). Feng <jats:italic>et al</jats:italic> . show that NIN is proteolytically processed to release a fragment that regulates the later stages of nodulation when the nodules acquire nitrogen-fixing capability. In related work, Jiang <jats:italic>et al</jats:italic> . identified members of the NIN-like protein (NLP) transcription factor family as being regulators of leghemoglobin expression acting through an unusual promotor motif shared across legumes. —PJH </jats:p>