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Ferroelectric tunnel junctions (FTJs) based on epitaxial complex oxide heterostructures are promising building blocks for developing low power nanoelectronics and neuromorphic computing. FTJs consisting of correlated oxide electrodes have distinct advantages in size scaling but only yield moderate electroresistance (ER) at room temperature due to the challenge in imposing asymmetric interfacial screening and large modulation of the tunneling potential profile. Here, we achieve large ER in all-oxide FTJs by paring a correlated metal with a narrow bandgap Mott insulator as electrodes. We fabricate epitaxial FTJs composed of 2.8 and 4 nm PbZr0.2Ti0.8O3 tunnel barriers sandwiched between correlated oxides LaNiO3 and Sr3Ir2O7 electrodes. An ER of 6500% has been observed at room temperature, which increases to over 105% at 100 K. The high ER can be attributed to ferroelectric polarization induced metal–insulator transition in interfacial Sr3Ir2O7, which enhances the potential asymmetry for the tunnel barrier. The temperature dependence of tunneling current shows that direct tunneling dominates in the on state, while the off-state conduction transitions from thermally activated behavior at high temperatures to Glazman–Matveev defect-mediated inelastic tunneling at low temperatures. Our study provides a viable material strategy for designing all-oxide FTJs with high ER, facilitating their implementation in nonvolatile memories and energy-efficient computing devices. 

Neurotransmitters play a crucial role in regulating communication between neurons within the brain and central nervous system. Thus, imaging neurotransmitters has become a high priority in neuroscience. This minireview focuses on recent advancements in the development of fluorescent small‐molecule fluorescent probes for neurotransmitter imaging and applications of these probes in neuroscience. Innovative approaches for probe design are highlighted as well as attributes which are necessary for practical utility, with a view to inspiring new probe development capable of visualizing neurotransmitters. 

Abstract Visualizing spatial assay data in anatomical images is vital for understanding biological processes in cell, tissue, and organ organizations. Technologies requiring this functionality include traditional one-at-a-time assays, and bulk and single-cell omics experiments, including RNA-seq and proteomics. The spatialHeatmap software provides a series of powerful new methods for these needs, and allows users to work with adequately formatted anatomical images from public collections or custom images. It colors the spatial features (e.g. tissues) annotated in the images according to the measured or predicted abundance levels of biomolecules (e.g. mRNAs) using a color key. This core functionality of the package is called a spatial heatmap plot. Single-cell data can be co-visualized in composite plots that combine spatial heatmaps with embedding plots of high-dimensional data. The resulting spatial context information is essential for gaining insights into the tissue-level organization of single-cell data, or vice versa. Additional core functionalities include the automated identification of biomolecules with spatially selective abundance patterns and clusters of biomolecules sharing similar abundance profiles. To appeal to both non-expert and computational users, spatialHeatmap provides a graphical and a command-line interface, respectively. It is distributed as a free, open-source Bioconductor package (https://bioconductor.org/packages/spatialHeatmap) that users can install on personal computers, shared servers, or cloud systems. 

Abstract PremiseDioecy (separate sexes) has independently evolved numerous times across the angiosperm phylogeny and is recently derived in many lineages. However, our understanding is limited regarding the evolutionary mechanisms that drive the origins of dioecy in plants. The recent and repeated evolution of dioecy across angiosperms offers an opportunity to make strong inferences about the ecological, developmental, and molecular factors influencing the evolution of dioecy, and thus sex chromosomes. The genusAsparagus(Asparagaceae) is an emerging model taxon for studying dioecy and sex chromosome evolution, yet estimates for the age and origin of dioecy in the genus are lacking. MethodsWe use plastome sequences and fossil time calibrations in phylogenetic analyses to investigate the age and origin of dioecy in the genusAsparagus. We also review the diversity of sexual systems present across the genus to address contradicting reports in the literature. ResultsWe estimate that dioecy evolved once or twice approximately 2.78−3.78 million years ago inAsparagus, of which roughly 27% of the species are dioecious and the remaining are hermaphroditic with monoclinous flowers. ConclusionsOur findings support previous work implicating a young age and the possibility of two origins of dioecy inAsparagus, which appear to be associated with rapid radiations and range expansion out of Africa. Lastly, we speculate that paleoclimatic oscillations throughout northern Africa may have helped set the stage for the origin(s) of dioecy inAsparagusapproximately 2.78−3.78 million years ago. 

Abstract The superior size and power scaling potential of ferroelectric-gated Mott transistors makes them promising building blocks for developing energy-efficient memory and logic applications in the post-Moore’s Law era. The close to metallic carrier density in the Mott channel, however, imposes the bottleneck for achieving substantial field effect modulation via a solid-state gate. Previous studies have focused on optimizing the thickness, charge mobility, and carrier density of single-layer correlated channels, which have only led to moderate resistance switching at room temperature. Here, we report a record high nonvolatile resistance switching ratio of 38,440% at 300 K in a prototype Mott transistor consisting of a ferroelectric PbZr_0.2Ti_0.8O₃gate and anRNiO₃(R: rare earth)/La_0.67Sr_0.33MnO₃composite channel. The ultrathin La_0.67Sr_0.33MnO₃buffer layer not only tailors the carrier density profile inRNiO₃through interfacial charge transfer, as corroborated by first-principles calculations, but also provides an extended screening layer that reduces the depolarization effect in the ferroelectric gate. Our study points to an effective material strategy for the functional design of complex oxide heterointerfaces that harnesses the competing roles of charge in field effect screening and ferroelectric depolarization effects. 

Abstract Due to commonalities in pathophysiology, age-related macular degeneration (AMD) represents a uniquely accessible model to investigate therapies for neurodegenerative diseases, leading us to examine whether pathways of disease progression are shared across neurodegenerative conditions. Here we use single-nucleus RNA sequencing to profile lesions from 11 postmortem human retinas with age-related macular degeneration and 6 control retinas with no history of retinal disease. We create a machine-learning pipeline based on recent advances in data geometry and topology and identify activated glial populations enriched in the early phase of disease. Examining single-cell data from Alzheimer’s disease and progressive multiple sclerosis with our pipeline, we find a similar glial activation profile enriched in the early phase of these neurodegenerative diseases. In late-stage age-related macular degeneration, we identify a microglia-to-astrocyte signaling axis mediated by interleukin-1 β which drives angiogenesis characteristic of disease pathogenesis. We validated this mechanism using in vitro and in vivo assays in mouse, identifying a possible new therapeutic target for AMD and possibly other neurodegenerative conditions. Thus, due to shared glial states, the retina provides a potential system for investigating therapeutic approaches in neurodegenerative diseases. 

Abstract. Coupled physical–biogeochemical models can fill thespatial and temporal gap in ocean carbon observations. Challenges ofapplying a coupled physical–biogeochemical model in the regional oceaninclude the reasonable prescription of carbon model boundary conditions,lack of in situ observations, and the oversimplification of certainbiogeochemical processes. In this study, we applied a coupledphysical–biogeochemical model (Regional Ocean Modelling System, ROMS) to theGulf of Mexico (GoM) and achieved an unprecedented 20-year high-resolution(5 km, 1/22∘) hindcast covering the period of 2000 to 2019. Thebiogeochemical model incorporated the dynamics of dissolved organic carbon(DOC) pools and the formation and dissolution of carbonate minerals. Thebiogeochemical boundaries were interpolated from NCAR's CESM2-WACCM-FV2solution after evaluating the performance of 17 GCMs in the GoM waters. Modeloutputs included carbon system variables of wide interest, such aspCO2, pH, aragonite saturation state (ΩArag), calcitesaturation state (ΩCalc), CO2 air–sea flux, and carbon burialrate. The model's robustness is evaluated via extensive model–datacomparison against buoys, remote-sensing-based machine learning (ML)products, and ship-based measurements. A reassessment of air–sea CO2flux with previous modeling and observational studies gives us confidencethat our model provides a robust and updated CO2 flux estimation, andNGoM is a stronger carbon sink than previously reported. Model resultsreveal that the GoM water has been experiencing a ∼ 0.0016 yr−1 decrease in surface pH over the past 2 decades, accompanied by a∼ 1.66 µatm yr−1 increase in sea surfacepCO2. The air–sea CO2 exchange estimation confirms in accordance with severalprevious models and ocean surface pCO2 observations that theriver-dominated northern GoM (NGoM) is a substantial carbon sink, and theopen GoM is a carbon source during summer and a carbon sink for the rest ofthe year. Sensitivity experiments are conducted to evaluate the impacts ofriver inputs and the global ocean via model boundaries. The NGoM carbonsystem is directly modified by the enormous carbon inputs (∼ 15.5 Tg C yr−1 DIC and ∼ 2.3 Tg C yr−1 DOC) from theMississippi–Atchafalaya River System (MARS). Additionally,nutrient-stimulated biological activities create a ∼ 105 timeshigher particulate organic matter burial rate in NGoM sediment than in thecase without river-delivered nutrients. The carbon system condition of theopen ocean is driven by inputs from the Caribbean Sea via the Yucatan Channeland is affected more by thermal effects than biological factors.