Dual‐sites single atom catalysts hold promise for efficiently regulating multiple reaction processes and explicitly explaining the underlying mechanisms. However, delicate atomic engineering for ...dual‐site single atom catalysts remains a huge challenge. Herein, atomically dispersed Fe‐Ni single atoms embedded in a nitrogen‐doped carbon matrix (FeNi SAs/NC) are successfully developed with extraordinary activity for electrocatalytic oxygen reduction and evolution reactions (ORR/OER). The atomic FeNi SAs/NC catalyst displays high onset potential (0.98 V) and half‐wave potential (0.84 V) for the ORR, as well as, low overpotential of (270 mV) at 10 mA cm−2 for the OER. The density functional theory calculations indicate that the Fe site as the active center can facilitate the four‐electron reaction process, while Ni sites regulate the electronic structure of Fe sites and further reduce the energy barrier of the rate‐determining step. In addition, the nitrogen‐doped carbon matrix prevents the metal atoms from aggregation and corrosion, leading to the improvement of catalyst durability. As a proof of concept, flexible quasi‐solid‐state zinc– and aluminum–air batteries assembled with the FeNi SAs/NC catalyst exhibit superior peak power densities and discharging specific capacities outperforming the commercial Pt/C. This work provides rational guidance for the synthesis of bifunctional electrocatalysts in next‐generation energy devices for flexible consumer electronics.
Unique noble metal‐free electrocatalysts with atomically dispersed Fe‐Ni dual‐sites are precisely designed and present superior oxygen reduction and evolution reaction reactivity under alkaline conditions, which provides a perspective and guidance for the design of efficient catalysts for metal–air batteries.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Metal hydroxides and oxides have emerged as fascinating materials and key structures for electrocatalysis however, they have rarely been investigated for the HER. Herein, we introduce unique ...transition-metal hydroxides@MXene (TMHs@MXene) hybrids, including Co(OH)
2
@MXene, Ni(OH)
2
@MXene, and FeOOH@MXene, with well-defined components and hierarchical sheet-like architectures for the alkaline HER. By virtue of their novel structure and the strong interfacial interactions between transition-metal hydroxides (TMHs) and MXene nanosheets, the obtained nanohybrids not only provide sufficient active sites and a robust structure, but also ensure favourable electrochemical kinetics and superior catalytic activity. Significantly, both theoretical calculations and the electrochemical test prove that the interfacial electronic coupling between the two different components could optimize the adsorption energy of water and hydrogen, thereby resulting in Pt-like catalytic activity including a low Tafel slope (31.7 mV dec
−1
), a small overpotential (21.0 mV@10 mA cm
−2
), and excellent stability for Co(OH)
2
@MXene. As expected, an alkaline water electrolyzer was built using Co(OH)
2
@MXene as the cathode for overall water splitting, which achieves a current density of 10 mA cm
−2
at 1.46 V with outstanding stability over 100 h. Our discovery highlights the great potential of interfacial electronic coupling to optimize advanced electrocatalysts for application in energy-related fields.
The well-designed hybrid electrocatalysts have been synthesized by anchoring ultrathin transition metal hydroxides on MXene nanosheets to boost the HER performance. Thanks to the unique architecture and synergistic effects, Co(OH)
2
@MXene manifests unprecedented catalytic activity.
Astrocytes play essential roles in brain function by supporting synaptic connectivity and associated circuits. How these roles are regulated by transcription factors is unknown. Moreover, there is ...emerging evidence that astrocytes exhibit regional heterogeneity, and the mechanisms controlling this diversity remain nascent. Here, we show that conditional deletion of the transcription factor nuclear factor I-A (NFIA) in astrocytes in the adult brain results in region-specific alterations in morphology and physiology that are mediated by selective DNA binding. Disruptions in astrocyte function following loss of NFIA are most pronounced in the hippocampus, manifested by impaired interactions with neurons, coupled with diminution of learning and memory behaviors. These changes in hippocampal astrocytes did not affect basal neuronal properties but specifically inhibited synaptic plasticity, which is regulated by NFIA in astrocytes through calcium-dependent mechanisms. Together, our studies reveal region-specific transcriptional dependencies for astrocytes and identify astrocytic NFIA as a key transcriptional regulator of hippocampal circuits.
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•NFIA is required to maintain astrocyte function in a brain-region-specific manner•Brain-region-specific DNA binding by NFIA is inhibited by its association with NFIB•Astrocyte-neuron communication in the hippocampus is disrupted•Synaptic plasticity and memory are impaired in mice lacking astrocytic NFIA
Astrocytes play essential roles in brain function by supporting synaptic connectivity and associated circuits. We found the transcription factor NFIA is required to maintain astrocyte function in the hippocampus through region-specific DNA binding mechanisms. Alterations in astrocyte-neuron communication disrupt hippocampal circuit function, resulting in impaired learning and memory behaviors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Astrocytes are the most abundant cell type in the brain, where they perform a wide array of functions, yet the nature of their cellular heterogeneity and how it oversees these diverse roles remains ...shrouded in mystery. Using an intersectional fluorescence-activated cell sorting-based strategy, we identified five distinct astrocyte subpopulations present across three brain regions that show extensive molecular diversity. Application of this molecular insight toward function revealed that these populations differentially support synaptogenesis between neurons. We identified correlative populations in mouse and human glioma and found that the emergence of specific subpopulations during tumor progression corresponded with the onset of seizures and tumor invasion. In sum, we have identified subpopulations of astrocytes in the adult brain and their correlates in glioma that are endowed with diverse cellular, molecular and functional properties. These populations selectively contribute to synaptogenesis and tumor pathophysiology, providing a blueprint for understanding diverse astrocyte contributions to neurological disease.
Spintronic elements based on spin transfer torque have emerged with potential for on‐chip memory, but they suffer from large energy dissipation due to the large current densities required. In ...contrast, an electric‐field‐driven magneto‐electric storage element can operate with capacitive displacement charge and potentially reach 1–10 µJ cm−2 switching operation. Here, magneto‐electric switching of a magnetoresistive element is shown, operating at or below 200 mV, with a pathway to get down to 100 mV. A combination of phase detuning is utilized via isovalent La substitution and thickness scaling in multiferroic BiFeO3 to scale the switching energy density to ≈10 µJ cm−2. This work provides a template to achieve attojoule‐class nonvolatile memories.
Spintronic elements based on spin transfer torque have emerged with potential for on‐chip memory, but they suffer from large energy dissipation. Magneto‐electric switching of a magnetoresistive element operating at or below 200 mV with a pathway to reduce a switching energy density to ≈10 µJ cm‐2 is shown. This work provides a template to achieve attojoule‐class nonvolatile memories.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Two compact, printed, ultrawideband (UWB) monopole antennas with tri-band notched characteristics are reported. The notched filters are achieved by introducing printed, electrically small, ...capacitively-loaded loop (CLL) resonators. The directly driven elements consist of printed top-loaded CLL-based monopoles and 50 Ω microstrip feed lines. By adding three CLL elements close to the feed line, band-notch properties in the WiMAX (3.3-3.6GHz), lower WLAN (5.15-5.35GHz) and higher WLAN (5.725-5.825GHz) bands are achieved. Each antenna system is contained on a 27×34mm 2 sheet of Rogers Duroid 5880 substrate. One is designed with three additional CLL elements; the other is achieved with only two. Comparisons between the simulation and measurement results show that these UWB antennas have broadband matched impedance values and stable radiation patterns for all radiating frequencies.
Abstract
Magnetoelectric coupling at room temperature in multiferroic materials, such as BiFeO
3
, is one of the leading candidates to develop low-power spintronics and emerging memory technologies. ...Although extensive research activity has been devoted recently to exploring the physical properties, especially focusing on ferroelectricity and antiferromagnetism in chemically modified BiFeO
3
, a concrete understanding of the magnetoelectric coupling is yet to be fulfilled. We have discovered that La substitutions at the Bi-site lead to a progressive increase in the degeneracy of the potential energy landscape of the BiFeO
3
system exemplified by a rotation of the polar axis away from the 〈111〉
pc
towards the 〈112〉
pc
discretion. This is accompanied by corresponding rotation of the antiferromagnetic axis as well, thus maintaining the right-handed vectorial relationship between ferroelectric polarization, antiferromagnetic vector and the Dzyaloshinskii-Moriya vector. As a consequence, La-BiFeO
3
films exhibit a magnetoelectric coupling that is distinctly different from the undoped BiFeO
3
films.
Air pollution is inevitably the result of human civilization, industrialization, and globalization. It is composed of a mixture of gases and particles at harmful levels. Particulate matter (PM), ...nitrogen oxides (NOx), and carbon dioxides (CO
) are mainly generated from vehicle emissions and fuel consumption and are the main materials causing outdoor air pollution. Exposure to polluted outdoor air has been proven to be harmful to human eyes. On the other hand, indoor air pollution from environmental tobacco smoking, heating, cooking, or poor indoor ventilation is also related to several eye diseases, including conjunctivitis, glaucoma, cataracts, and age-related macular degeneration (AMD). In the past 30 years, no updated review has provided an overview of the impact of air pollution on the eye. We reviewed reports on air pollution and eye diseases in the last three decades in the PubMed database, Medline databases, and Google Scholar and discussed the effect of various outdoor and indoor pollutants on human eyes.
Long-range transport (LRT) of air pollutants from East Asia during the northeast monsoon season impacts several downwind locations. In 2020, the initial COVID-19 lockdowns in China overlapped with ...Week 3 of the Chinese New Year (CNY) holiday, and an Asian outflow event. Thus, movement of the Chinese populace from city to city was already greatly reduced by the time of the LRT episode, although the reductions in industrial output are less clear. We found NO2 column concentrations were reduced by 24% during the CNY Week 3 this year compared to previous years. The attenuated transport event arrived to northern Taiwan with a PM2.5 concentration <45 μg m−3 and most often <35 μg m−3, which is 2–3 times lower than LRT episodes of similar back-trajectory and synoptic patterns. The whole episode persisted for about 60 h, longer than most LRT episodes from China to Taiwan. CMAQ v5.2.1 modeling of the LRT event with 100% emission and reduced emission scenarios, revealed emissions in China were approximately 50% less than normal periods. Due to the length of the episode and the significant reduction in emissions, Taiwan avoided a PM2.5 surplus of 19.2 μg m−3 on average during the episode, equivalent to a 0.5 μg m−3 reduction for the whole 3-month winter season. Employing the 100% emission model scenario and scaling up to the average episode hours each winter, the PM2.5 surplus delivered via plumes on the northeast monsoon is equivalent to a 0.5 μg m−3 surplus for the whole year.
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•COVID-19 lockdown in China reduced long-range transport of air pollution to Taiwan.•OMI NO2 over central-north China reduced by 24% compared to previous years.•PM2.5 concentration in northern Taiwan 2 times lower compared to similar episode•CMAQ simulation with 50% reduced emission in China matches measured PM2.5 in Taiwan.•Avoided PM2.5 pollution equivalent to 0.5 μg m−3 reduction for entire winter season
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Architected materials that actively respond to external stimuli hold tantalizing prospects for applications in energy storage, wearable electronics, and bioengineering. Molybdenum disulfide, ...an excellent two-dimensional building block, is a promising candidate for lithium-ion battery anode. However, the stacked and brittle two-dimensional layered structure limits its rate capability and electrochemical stability. Here we report the dewetting-induced manufacturing of two-dimensional molybdenum disulfide nanosheets into a three-dimensional foam with a structural hierarchy across seven orders of magnitude. Our molybdenum disulfide foam provides an interpenetrating network for efficient charge transport, rapid ion diffusion, and mechanically resilient and chemically stable support for electrochemical reactions. These features induce a pseudocapacitive energy storage mechanism involving molybdenum redox reactions, confirmed by in-situ X-ray absorption near edge structure. The extraordinary electrochemical performance of molybdenum disulfide foam outperforms most reported molybdenum disulfide-based Lithium-ion battery anodes and state-of-the-art materials. This work opens promising inroads for various applications where special properties arise from hierarchical architecture.
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