查看更多>>摘要：Clean air actions(CAAs)in China have been linked to considerable benefits in public health.However,whether the beneficial effects of CAAs are equally distributed geographically is unknown.Using high-resolution maps of the distributions of major air pollutants(fine particulate matter[PM2.5]and ozone[O3])and population,we aimed to track spatiotemporal changes in health impacts from,and geographic inequality embedded in,the reduced exposures to PM2.5 and O3 from 2013 to 2020.We used a method established by the Global Burden of Diseases Study.By analyzing the changes in loss of life expectancy(LLE)attributable to PM2.5 and O3,we calculated the gain of life expectancy(GLE)to quantify the health benefits of the air-quality improvement.Finally,we assessed the geographic inequality embedded in the GLE using the Gini index(GI).Based on risk assessments of PM2.5 and O3,during the first stage of CAAs(2013 to 2017),the mean GLE was 1.87 months.Half of the sum of the GLE was disproportionally distributed in about one quarter of the population exposed(GI 0.44).During the second stage of CAAs(2017 to 2020),the mean GLE increased to 3.94 months and geographic inequality decreased(GI 0.18).According to our assessments,CAAs were enhanced,from the first to second stages,in terms of not only preventing premature mortality but also ameliorating health inequalities.The enhancements were related to increased sensitivity to the health effects of air pollution and synergic control of PM2.4 and O3 levels.Our findings will contribute to optimizing future CAAs.
查看更多>>摘要：Core-mantle friction induced by the precession of the Moon's spin axis is a strong heat source in the deep lunar mantle during the early phase of a satellite's evolution,but its influence on the long-term thermal evolution still remains poorly explored.Using a one-dimensional thermal evolution model,we show that core-mantle friction can sustain global-scale partial melting in the upper lunar mantle until～3.1 Ga,thus accounting for the intense volcanic activity on the Moon before～3.0 Ga.Besides,core-mantle friction tends to suppress the secular cooling of the lunar core and is unlikely to be an energy source for the long-lived lunar core dynamo.Our model also favours the transition of the Cassini state before the end of the lunar magma ocean phase(～4.2 Ga),which implies a decreasing lunar obliquity over time after the solidification of the lunar magma ocean.Such a trend of lunar obliquity evolution may allow volcanically released water to be buried in the lunar regolith of the polar regions.As a consequence,local water ice could be more abundant than previously thought when considering only its accumulation caused by solar wind and comet spreading.
查看更多>>摘要：Lactate is present at a high level in the microenvironment of mammalian preimplantation embryos in vivo and in vitro.However,its role in preimplantation development is unclear.Here,we report that lactate is highly enriched in the nuclei of early embryos when major zygotic genome activation(ZGA)occurs in humans and mice.The inhibition of its production and uptake results in developmental arrest at the 2-cell stage,major ZGA failure,and loss of lactate-derived H3K18lac,which could be rescued by the addition of Lac-CoA and recapitulated by overexpression of H3K18R mutation.By profiling the landscape of H3K18lac during mouse preimplantation development,we show that H3K18lac is enriched on the promoter regions of most major ZGA genes and correlates with their expressions.In humans,H3K181ac is also enriched in ZGA markers and temporally concomitant with their expressions.Taken together,we profile the landscapes of H3K18lac in mouse and human preimplantation embryos,and demonstrate the important role for H3K18lac in major ZGA,showing that a conserved metabolic mechanism underlies preimplantation development of mammalian embryos.
查看更多>>摘要：Error-correcting codes(ECCs)employed in the state-of-the-art DNA digital storage(DDS)systems suffer from a trade-offbetween error-correcting capability and the proportion of redundancy.To address this issue,in this study,we introduce soft-decision decoding approach into DDS by proposing a DNA-specific error prediction model and a series of novel strategies.We demonstrate the effectiveness of our approach through a proof-of-concept DDS system based on Reed-Solomon(RS)code,named as Derrick.Derrick shows significant improvement in error-correcting capability without involving additional redundancy in both in vitro and in silico experiments,using various sequencing technologies such as Illumina,PacBio and Oxford Nanopore Technology(ONT).Notably,in vitro experiments using ONT sequencing at a depth of 7 x reveal that Derrick,compared with the traditional hard-decision decoding strategy,doubles the error-correcting capability of RS code,decreases the proportion of matrices with decoding-failure by 229-fold,and amplifies the potential maximum storage volume by impressive 32 388-fold.Also,Derrick surpasses'state-of-the-art'DDS systems by comprehensively considering the information density and the minimum sequencing depth required for complete information recovery.Crucially,the soft-decision decoding strategy and key steps of Derrick are generalizable to other ECCs'decoding algorithms.
查看更多>>摘要：Vaccines have been the primary remedy in the global fight against coronavirus disease 2019(COVID-19).The receptor-binding domain(RBD)of the spike protein,a critical viral immunogen,is affected by the heterogeneity of its glycan structures and relatively low immunogenicity.Here,we describe a scalable synthetic platform that enables the precise synthesis of homogeneously glycosylated RBD,facilitating the elucidation of carbohydrate structure-function relationships.Five homogeneously glycosylated RBDs bearing biantennary glycans were prepared,three of which were conjugated to T-helper epitope(Tpep)from tetanus toxoid to improve their weak immune response.Relative to natural HEK293-derived RBD,synthetic RBDs with biantennary N-glycan elicited a higher level of neutralising antibodies against SARS-CoV-2 in mice.Furthermore,RBDs containing Tpep elicited significant immune responses in transgenic mice expressing human angiotensin-converting enzyme 2.Our collective data suggest that trimming the N-glycans and Tpep conjugation of RBD could potentially serve as an effective strategy for developing subunit vaccines providing efficient protection.
查看更多>>摘要：Iron catalysts are ideal transition metal catalysts because of the Earths abundant,cheap,biocompatible features of iron salts.Iron catalysts often have unique open-shell structures that easily undergo spin crossover in chemical transformations,a feature rarely found in noble metal catalysts.Unfortunately,little is known currently about how the open-shell structure and spin crossover affect the reactivity and selectivity of iron catalysts,which makes the development of iron catalysts a low efficient trial-and-error program.In this paper,a combination of experiments and theoretical calculations revealed that the iron-catalyzed hydrosilylation of alkynes is typical spin-crossover catalysis.Deep insight into the electronic structures of a set of well-defined open-shell active formal Fe(0)catalysts revealed that the spin-delocalization between the iron center and the 1,10-phenanthroline ligand effectively regulates the iron center's spin and oxidation state to meet the opposite electrostatic requirements of oxidative addition and reductive elimination,respectively,and the spin crossover is essential for this electron transfer process.The triplet transition state was essential for achieving high regioselectivity through tuning the nonbonding interactions.These findings provide an important reference for understanding the effect of catalyst spin state on reaction.It is inspiring for the development of iron catalysts and other Earth-abundant metal catalysts,especially from the point of view of ligand development.
查看更多>>摘要：Gas diffusion electrodes(GDEs)mediate the transport of reactants,products and electrons for the electrocatalytic CO2 reduction reaction(CO2RR)in membrane electrode assemblies.The random distribution of ionomer,added by the traditional physical mixing method,in the catalyst layer of GDEs affects the transport of ions and CO2.Such a phenomenon results in elevated cell voltage and decaying selectivity at high current densities.This paper describes a pre-confinement method to construct GDEs with homogeneously distributed ionomer,which enhances mass transfer locally at the active centers.The optimized GDE exhibited comparatively low cell voltages and high CO Faradaic efficiencies(FE＞90％)at a wide range of current densities.It can also operate stably for over 220 h with the cell voltage staying almost unchanged.This good performance can be preserved even with diluted CO2 feeds,which is essential for pursuing a high single-pass conversion rate.This study provides a new approach to building efficient mass transfer pathways for ions and reactants in GDEs to promote the electrocatalytic CO2RR for practical applications.
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