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Stability analysis of doped carbon nanotubes (CNTs)
It is well established that (3, 0), (3, 3), and (5, 0) carbon nanotubes (CNTs) are experimentally confirmed and are superconducting at low temperatures. In this study, the dynamical stability of (5, 0), (5, 5), and (7, 0) CNTs will be examined through phonon dispersion and ab initio molecular dynamics calculations as implemented in the QUANTUM ESPRESSO suite. Doping of the pristine CNTs with atoms of the groups IA, IIIA, IVA, and VA in the periodic table gives several stable structures but we show that the position of the doped atom in the primitive cell is crucial for the stability of the resulting structure. The bonding and vibration modes around the doped atoms are analyzed to elucidate the underlying cause of instability. The electron–phonon interaction and superconducting transition temperature (Tc) using McMillan–Allen–Dynes formula are also calculated for stable pristine and doped CNTs. We show that the Si doped (5,0) CNT exhibits superconductivity at Tc∼5.99 K.
Highly ionic-dispersed oxygen electrode for reversible proton ceramic electrochemical cells
Abstract The key challenges for commercializing reversible proton ceramic electrochemical cells (R-PCECs) are the insufficient proton conductivity and inferior thermomechanical stability of oxygen electrodes in air with water vapor. We report a multielement micro-doped BaCoO 3-δ -based perovskite material, in which disorder is induced in the ionic substructure to maximize the oxygen-water reaction activity. Atom probe tomography and density functional theory calculations reveal that reduced proton adsorption/diffusion energy barriers are triggered by homogeneous ion distributions in the perovskite oxide. Moreover, the thermally driven mild oxygen release can be further offset by beneficial proton uptake, thereby increasing the thermomechanical durability of the oxygen electrode. The resulting R-PCECs obtain a peak power density of 1.56 W cm -2 and an electrolysis current density of 2.0 A cm -2 @1.3 V at 600 °C while demonstrating long-term stability exceeding 780 hours, with degradation rates of 19.3 and 16.9 μV h -1 in fuel cell and electrolysis modes, respectively.
Current shunting and plasma instabilities during electrical explosions of copper and aluminum wires in water and air
We present the first x-ray images of electrically exploding wires in air and water, captured at the European X-ray Free-Electron Laser (EuXFEL). These images reveal current shunting in a copper wire during its explosion in air, and the development of electrothermal (and possibly magnetohydrodynamic) instabilities in copper and aluminum wires exploding in water. The experiments were conducted at the Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography instrument (SPB/SFX) at EuXFEL, where fine metallic wires were driven by a pulsed-power generator with a current rise time of ∼1.1 μs and a peak amplitude of ∼28 kA. EuXFEL enabled MHz x-ray radiography of the wires using 20 keV photons and a narrow bandwidth of ∼40 eV. Using the specific current action integral for a copper wire explosion, we provide the first quantitative estimate of the fraction of current that is shunted through the surrounding medium of an exploding wire. Fourier analysis of the electrothermal instability spectrum shows that its wavelength remains mostly independent of the wire diameter once it has exploded, and that the temperature perturbation is similar in magnitude to the average temperature in the wire.
Complex marine ecological response during the Eocene-Oligocene revealed by global foraminiferal record
Abstract The Eocene–Oligocene transition was the crucial turning point when Earth’s climate shifted to its current icehouse state. Understanding how the marine biosphere responded during this transition is not well-constrained, appearing as a simple extinction pulse in low temporal resolution global compendia. Here we design an artificial-intelligence-inspired metaheuristics algorithm to construct a high-resolution global species richness history across the Eocene–Oligocene transition for the rich foraminifera fossil record with an imputed ~29,000-year resolution. The revealed diversity dynamics are complex and differ for each foraminiferal group with distinct ecology. Planktonic and shallow-water larger benthic foraminifera show steady diversity levels in the early phases of the transition in the latest Eocene after a long-term reduction, while the deeper-water small benthic foraminifera radiate notably and then decline over the same interval. In the earliest Oligocene, the planktonic and larger foraminifera suffer major species losses coincident with the first continental-scale ice sheet formed on Antarctica, while small benthic foraminifera diversity holds steady, followed by an accelerating lowering as the early Oligocene proceeds. These findings reveal complicated and ecologically differentiated environment-life processes, indicating the importance of high-resolution temporal data for dissecting out ecological responses to major environmental changes.
Impact of lithium nitrate-induced defects on electrical conduction and 1/f noise in hydrothermally grown ZnO film/nanorod homojunctions
We investigate the electrical transport and low-frequency noise (LFN) characteristics of hydrothermally grown n-type ZnO nanorod/nanotextured film homojunctions synthesized via chemical bath deposition with varying Lithium nitrate concentrations. Homojunctions fabricated without Lithium nitrate or with moderate concentrations exhibit stable rectifying behavior, whereas very low or high lithium nitrate levels induce contact-dominated noise or defect-induced instability. Current–voltage analysis reveals asymmetric space-charge-limited current (SCLC) transport: reverse-bias conduction is governed by trap-free SCLC in nanorods, enabling electron mobility extraction, while forward-bias transport is dominated by trap-controlled SCLC in the nanotextured film, consistent with an exponential trap-state distribution. LFN studies show that forward-bias 1/f noise originates from trapping–detrapping in the nanotextured film, whereas reverse-bias noise follows Hooge's mobility fluctuation model. Noise variations with lithium nitrate concentration correlate with changes in trap-state distributions. Overall, this work demonstrates that electrical characterization combined with LFN analysis offers a sensitive and reliable approach for probing defect-mediated electronic disorder in chemically grown oxide semiconductors.
Biological traits predict species’ time-varying responses to multiple global change drivers
Superlattice reflection signatures of the insulator–metal transition in V3O5 thin films
Nanoelectronic systems that are inspired by the brain are increasingly looking to insulator–metal transition (IMT) materials as they can mimic the response characteristics of neurons to temperature changes so that these can be used in robotic and computational applications. V3O5 has an insulator–metal transition at ∼430 or ∼80 K higher than VO2 and provides a unique high-temperature opportunity for these types of applications. In this work, we track the structural evolution of V3O5 thin films across the IMT through conventional selected-area electron diffraction (SAED) and four-dimensional scanning TEM (4D-STEM), correlated with temperature-dependent resistance measurements. SAED patterns show reversible evidence of superlattice reflections associated with the IMT—present below TIMT and absent above it—consistent with the accompanying drop in resistance. At room temperature, nanobeam electron diffraction patterns further reveal three local configurations: (i) type I regions with clean patterns lacking superlattice reflections and spot splitting; (ii) type II regions exhibiting rows of superlattice reflections and split spots indicative of crystallographic variants; and (iii) type III regions with negligible superlattice reflections but larger spot splitting suggestive of overlapping domains of insulating and conducting phases likely driven by local lattice distortions. Upon heating, the superlattice reflections disappear between 413 and 453 K, concurrent with the resistance drop at TIMT, consistent with the emergence of a conducting phase. The overall diffraction geometry remains essentially unchanged up to 573 K, implying that relative domain orientations persist through the transition. These observations reveal nanoscale structural heterogeneity in V3O5 thin films across the IMT and inform operation in regimes where mixed-phase textures are expected. A plausible indexing framework rationalizing the observed geometries is presented in the Discussion section, alongside its limitations and alternative interpretations.
Prefusion-stabilized Hantaan virus glycoprotein nucleic acid vaccine elicits potent neutralizing antibody responses via germinal center activation
Abstract Old World orthohantaviruses , including Hantaan virus (HTNV), cause hemorrhagic fever with renal syndrome (HFRS) in Eurasia. Available inactivated vaccines often induce low neutralizing antibodies and short-term protection. We evaluated nucleic acid vaccines expressing a prefusion-stabilized HTNV glycoprotein in female BALB/c mice. Both DNA and mRNA-LNP versions elicited robust neutralizing antibodies by strongly activating germinal centers, which protected mice against high-dose HTNV challenge. We further tested heterologous prime-boost regimens, where mice primed with inactivated vaccine received different boosters. All boosters increased neutralizing titers, but only the prefusion-stabilized glycoprotein mRNA-LNP vaccine raised titers to the level achieved by its own full primary vaccination course. This demonstrates the immunogen’s superiority in developing next-generation vaccines and its unique ability to potently recall memory B cells induced by suboptimal inactivated vaccines. Thus, prefusion-stabilized glycoprotein-based nucleic acid vaccines are promising candidates for advanced orthohantavirus vaccine development.
Imitating neuro-plasticity in SrTiO3 based synaptic optoelectronic memristor for in-memory computing applications
Recently, perovskite oxide-based synaptic optoelectronic memristors (SOMs) present a favorable path toward the advancement of neuromorphic (or in-memory) computing. In this study, we propose a SrTiO3 (STO) functional layer-based simple and transparent two-terminal memristor device stacked with ITO/STO/ITO/glass, which shows improved resistive switching behavior after post-oxide nitrogen annealing treatment at 300 °C. The annealed device shows more stable resistive switching characteristics compared to the unannealed device, with a low set voltage (+0.9 V) and an enhanced memory window (∼35). The presence of nitrogen in the STO layer assists in confining the conductive filament path, which helps to enhance the device's uniformity and stability. The device successfully imitates key biological synaptic behaviors, such as long-term potentiation/depression, paired pulse facilitaion (PPF), and spike timing-dependent plasticity. In addition, artificial neural network models with convolutional layers and vision transformer architectures are simulated for image classification tasks on the extended- and fashion-modified National Institute of Standards and Technology datasets with ∼88% and ∼83% accuracy, respectively. The same device was illuminated with violet light (wavelength: 405 nm) at 40 mW/cm2 and produced the excitatory postsynaptic current response that gradually decayed under a dark environment. The exposure conditions are adjusted to simulate short- to long-term memory transition, optical PPF, and image sharpening functions. Along with the learning phase, the impact of illumination is also analyzed on the forgetting (or memory) phase of the current response, which is further utilized for simulating the image memory function. These findings emphasize the remarkable potential of the STO-based SOM for use in in-memory computing applications.
Electrostatically tunable moiré-mediated Wigner states via interfacial potential engineering in 2D van der Waals heterostructures
Cadonilimab plus chemotherapy with or without bevacizumab as first-line treatment for advanced cervical cancer: subgroup analyses from the COMPASSION-16 phase 3 trial
Jagged-mediated lateral induction patterns Notch3 signaling within adult neural stem cell populations
Abstract In the adult brain, Notch3 signaling promotes neural stem cell (NSC) quiescence and stemness. It remains unknown how Notch3 signaling levels are controlled and relate to these NSC decisions. Here we directly measure the nuclear translocation of the Notch3 intracellular fragment (N3ICD) and quantify Notch3 signaling in NSCs of the zebrafish adult telencephalon in situ. We report that Notch3 signaling levels match NSC quiescence and stemness levels. In physical space, Notch3 signaling is patterned and high signaling levels surround N3ICD low cells, which also express the deltaA (dla ) ligand. Another ligand, jagged1b ( jag1b ), expressed in all NSCs, activates Notch3 signaling and sustains expression of the stemness factor Sox2. Finally, lowering jag1b preserves the structured distribution of Notch3 signaling levels in space but attenuates their variance. We propose that Notch3 signaling integrates Dla-mediated lateral inhibition and Jag1b-mediated lateral induction to control quiescence and stemness and their spatiotemporal dynamics in adult NSCs.
High-Fidelity quantum teleportation mediated by hole transfer in an acceptor–donor–radical molecular triad
Cell type-specific enhancers regulate IL-22 expression in innate and adaptive type 3 lymphoid cells
Noradrenaline causes a spread of association in the hippocampal cognitive map
Abstract The mammalian brain organises knowledge about entities in the world and relationships between them using cognitive maps. When forming a cognitive map, there is a necessary trade-off between extending the map to make novel inferences, and storing a veridical copy of past experience. However, the neural mechanisms that control this trade-off remain unknown. Using a cross-scale approach that combines a pharmacological intervention in humans with neural network modelling, we show that the neuromodulator noradrenaline elicits a significant ‘spread of association’ across hippocampal cognitive maps. This neural spread of association can be explained by changes in synaptic plasticity that predict overgeneralisation in behaviour. Thus, elevated noradrenaline during learning increases the ‘smoothing kernel’ for plasticity across the cognitive map, allowing disparate memories to become linked and distorted.
Predator-driven microbial feedback loops promote plant health
Coenzyme-functionalized photo-redox catalysis for low-energy click labeling
Solvation sheath reorganization enables fast ion transfer kinetics in lithium-ion battery
Dopaminergic processes predict temporal distortions in event memory
Abstract Our memories do not simply keep time — they distort it, stretching and compressing the past to reflect the structure of experience. Here, we combined functional magnetic resonance imaging (fMRI; n = 32) with eye-tracking ( n = 28) to test whether activation of the dopaminergic system, known to influence encoding and time perception, expands mnemonic representations of time between contextually distinct events. Participants encoded item sequences while listening to tones that typically repeated over time, but occasionally changed, creating salient event boundaries. We found that tone switches significantly activated the ventral tegmental area (VTA), and the magnitude of these responses predicted greater time dilation between item pairs spanning those switches. At a longer timescale, increased blinking also predicted greater time dilation in memory, but only for boundary-spanning item pairs. Together, these findings suggest that dopaminergic processes are sensitive to event structure and contribute to distortions of remembered time that may help segment continuous experience into distinct episodic memories.