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Higher-order topological fermion phase and Weyl phonon phase in Li-intercalated graphene layers
Two-dimensional (2D) higher-order topological fermionic phases coexisting with intriguing topological phonon states have recently become a focal point of condensed matter research. However, the coexistence of the second-order topological phase and valley Weyl phonon features in 2D materials remains unexplored. In this Letter, we present a two-dimensional Li-intercalated graphene material family that serves as an ideal platform for demonstrating the coexistence of topological electron and phonon features. Our study, which utilizes first-principles calculations, investigates the structural, electronic, and topological properties of several Li-intercalated graphene materials. The higher-order topological phases are protected by C6 rotation and inversion symmetries in Li-C6 and Li-C6-Li layers, respectively, as confirmed by their calculated topological invariants (χ6, Z4). Topologically protected corner modes are noticed within the gapped bulk and edge states (in the armchair edge) in the nanoflake geometry of the Li-C6 compound. Notably, the phonon spectra of the Li-C6 and Li-C6-Li materials exhibit Weyl phonon nodes in the Brillouin zone where the phonon bands touch at the valley-high symmetry point. The presence of localized Berry curvature and robust topological phonon edge states further confirms the existence of Weyl phonon nodes in these materials. Our first-principles study predicts potential candidates for hosting the coexisting electronic and phononic features and highlights the technological aspects of Li-intercalated graphene materials.
A dual role of Cohesin in DNA DSB repair
Abstract Cells undergo tens of thousands of DNA-damaging events each day. Defects in repairing double-stranded breaks (DSBs) can lead to genomic instability, contributing to cancer, genetic disorders, immunological diseases, and developmental defects. Cohesin, a multi-subunit protein complex, plays a crucial role in both chromosome organization and DNA repair by creating architectural loops through chromatin extrusion. However, the mechanisms by which cohesin regulates these distinct processes are not fully understood. In this study, we identify two separate roles for cohesin in DNA repair within mammalian cells. First, cohesin serves as an intrinsic architectural factor that normally prevents interactions between damaged chromatin. Second, cohesin has an architecture-independent role triggered by ATM phosphorylation of SMC1, which enhances the efficiency of repair. Our findings suggest that these two functions work together to reduce the occurrence of translocations and deletions associated with non-homologous end joining, thereby maintaining genomic stability.
Theoretical studies of transient hydrodynamic phonon transport in two-dimensional disk geometry
Many phonon hydrodynamics phenomena, including heat vortices, wave and parabolic distributions of heat flux, which appear due to sufficient normal process, can also appear when there is insufficient normal process. In other words, a smoking gun of phonon hydrodynamics phenomena at the macroscopic level is still lacking. To find it, transient cooling phenomenon in two-dimensional materials is studied based on the phonon Boltzmann transport equation. A heating pulsed Gaussian laser beam is added at the center of two-dimensional disk and it continues to heat the system for a while under the environment temperature. After the heating laser is removed, results show that the transient temperature could be lower than the environment temperature and this phenomenon could only appear with sufficient normal process and insufficient resistive process, which is exactly a smoking gun of phonon hydrodynamics. In addition, the possibility of this phenomenon measured by transient Raman experiments is theoretically discussed. Numerical results show that given a single-layer suspended graphene disk sample with diameter 7 μm, this transient cooling phenomenon can appear in the temperature range of 50–150 K.
Hominin presence in Eurasia by at least 1.95 million years ago
Alkylamine-tuned MoOx with synergistic manipulation of interlayer spacing and oxygen vacancies toward advanced Li–S batteries
Lithium–sulfur (Li–S) batteries have been considered a promising next-generation energy storage device. However, the serious polysulfide shuttle effect and slow reaction kinetics hampered their development. Herein, alkylamine-tuned MoOx with synergistic manipulation of interlayer spacing and oxygen vacancies as a bifunctional mediator for separator modification (refer to as MOC/PP) in Li–S batteries is proposed. The increased interlayer spacing provides a rapid and stable pathway for Li+ diffusion, facilitating uniform Li+ deposition on lithium anode. Rich oxygen vacancies serve as active sites for efficient chemisorption and catalysis with polysulfide. As demonstrated by theoretical calculations and experimental results successively, MOC/PP efficiently captures and accelerates the redox reaction of polysulfide. Therefore, LiǁLi symmetric cells with MOC/PP exhibit stable cycling over 1000 h at a current density of 1 mA cm−2. The full cells deliver a notable discharge-specific capacity of 602 mAh g−1 at 5 C (1 C = 1675 mA g−1) and maintain stable cycling for 800 cycles at 1 C, with 0.07% capacity decay per cycle. Even under conditions of lean electrolyte (E/S = 7 μL mgs−1) and high sulfur mass loading (4.3 mg cm−2), the initial capacity exceeds 1200 mAh g−1.
A single residue switch mediates the broad neutralization of Rotaviruses
Cryogenic cyclical etching of Si using CF4 plasma passivation steps: The role of CF radicals
Ultraviolet (UV) absorption spectroscopy is used to monitor the CF radical density in CF4 inductively coupled plasma (ICP) plasmas as a function of the substrate temperature. The CF density decreases dramatically when the wafer temperature is reduced from 20 to −130 °C by applying identical plasma conditions, demonstrating that the CF surface sticking coefficient increases as the surface temperature is reduced. This suggests that CF4 plasma could be used to form sidewall passivation layers and perform anisotropic etching at cryogenic temperature, which is impossible at room temperature. Subsequently, a cyclical Bosch type etching process of silicon was evaluated at −100 °C using CF4 plasma to passivate the trench sidewalls. Anisotropic etch profiles were obtained with an etch rate of 4.4 μm/min. Compared to a typical Bosch process using highly polymerizing c-C4F8 plasma, chamber wall contamination could be significantly reduced, alleviating a major issue of this cyclic process. Furthermore, CF4 has a 28% lower global warming potential than c-C4F8.
Metabolic activities are selective modulators for individual segmentation clock processes
Abstract Numerous cellular and molecular processes during embryonic development prompt the fundamental question of how their tempos are coordinated and whether a common global modulator exists. While the segmentation clock tempo scales with the kinetics of gene expression and degradation processes of the core clock gene Hes7 across mammals, the coordination of these processes remains unclear. This study examines whether metabolic activities serve as a global modulator for the segmentation clock, finding them to be selective instead. Several metabolic inhibitions extend the clock period but affect key processes differently: glycolysis inhibition slows Hes7 protein degradation and production delay without altering intron delay, while electron transport chain inhibition extends intron delay without influencing the other processes. Combinations of distinct metabolic inhibitions exhibit synergistic effects. We propose that the scaled kinetics of segmentation clock processes across species may result from combined selective modulators shaped by evolutionary constraints, rather than a single global modulator.
Narrow-linewidth microcavity Brillouin laser based on pump-locked high-Q silica microsphere resonator
Microcavity-based Brillouin lasers are promising high-performance light sources for integrating photonics and optoelectronics. One method to lock the pump light frequency is to utilize a complex system with optoelectronic feedback, which requires a high-cost narrow-linewidth pump laser and limits the application of microlasers in integrated optoelectronic systems. Another method reported recently is all-optical feedback to achieve the locking of microcavity laser. We propose to utilize Rayleigh scattering of microcavities to lock the frequency of the pump laser to the resonant frequency of the Brillouin laser microcavity with the all-optical method. While compressing the linewidth of the pump laser, it can greatly improve the long-term stability of the optically pumped microcavity Brillouin laser. In the experiment, the linewidth of the semiconductor pump laser is compressed from the MHz level to the kHz level. The microcavity Brillouin laser achieves an ultra-narrow intrinsic linewidth of 100 Hz, with an ultra-low frequency noise of 35 Hz2/Hz. The constructed microlaser obtains a locking time up to 1 h, which does not require any temperature control or vibration isolation of the laser system. This work demonstrated an optically pump-locked microcavity Brillouin laser, which provides a stable and reliable low-cost experimental platform for ultra-narrow-linewidth lasers, precision laser sensors, microwave-photonic signal synthesizer, and optomechanical systems.
Asymmetric projection of introspection reveals a behavioural and neural mechanism for interindividual social coordination
Tunable qubit quantum battery with delta-pulse driving
A quantum battery consisting of two coupled qubits driven by a delta-pulse is investigated. By using the framework of open quantum system, we obtain analytically several quantities describing the performance of the quantum battery. In particular, we are interested in the stored energy and the extractable energy known as ergotropy. We discover that by tuning the driving strength and the coupling strength, we can isolate the origin of the ergotropy: quantum coherences, population inversion, or combination of them. Furthermore, increasing the coupling strength not only enhances the stored energy, the ergotropy and charging power, but also reducing the charging time, which boosts the performance of the quantum battery.
Zincophilic CuO as electron sponge to facilitate dendrite-free zinc-based flow battery
The common structure of multiple instability patterns on free liquid surfaces induced by charge injection
A previously disregarded electrohydrodynamic (EHD) instability pattern at the gas–liquid interface caused by charge injection is elaborately described and identified as the classical EHD instability. The characteristics and evolutionary processes of three classic EHD instability patterns were meticulously described experimentally. A Taylor cone-like conical structure is proposed as the common basis for the formation of all these patterns. A direct numerical model based on coupled hydrodynamic and electrodynamic equations is developed, and the evolution of the free liquid surface from static to classical EHD instability patterns is obtained from numerical simulations. The simulation results match the experiments, providing details that cannot be observed experimentally and proving the similarity between the conical structure and the Taylor cone. The comprehensive experimental observations and efficient numerical models can serve as a valuable inspiration and foundation for various applications related to EHD surface instability.
Engineering triple O-Ti-O vacancy associates for efficient water-activation catalysis
Ultrasensitive probing of nematic order parameter via weak measurement
Nematic order parameter S is one of the most crucial material parameters of the nematic phase, which governs all of the material's anisotropic properties. The enhancement of its measurement precision has always been a great concern. In this Letter, a weak measurement scheme with a modified shift pointer is presented to achieve an ultrasensitive probe of S or the director's orientational angle θ. Using this scheme, we have demonstrated a real-time monitoring of the orientational process of cellulose nano-crystal molecules in solutions and measured the orientational direction of polymer nanowires. A typical precision on the order of 10−3 is achieved in the measurement of S and θ. Compared with the current existing techniques, the present scheme not only offers higher measurement precision but also maintains extreme cost-efficiency, thereby holding significance for the research of orientational materials and devices.
Unveiling pelagic-benthic coupling associated with the biological carbon pump in the Fram Strait (Arctic Ocean)
Abstract Settling aggregates transport organic matter from the ocean surface to the deep sea and seafloor. Though plankton communities impact carbon export, how specific organisms and their interactions affect export efficiency is unknown. Looking at 15 years of eDNA sequences (18S-V4) from settling and sedimented organic matter in the Fram Strait, here we observe that most phylogenetic groups were transferred from pelagic to benthic ecosystems. Chaetoceros socialis, sea-ice diatoms, Radiolaria, and Chaetognatha are critical components of vertical carbon flux to 200 m depth. In contrast, the diatom C. socialis alone is essential for the amount of organic carbon reaching the seafloor. Spatiotemporal changes in community composition show decreasing diatom abundance during warm anomalies, which would reduce the efficiency of a diatom-driven biological carbon pump. Interestingly, several parasites are also tightly associated with carbon flux and show a strong vertical connectivity, suggesting a potential role in sedimentation processes involving their hosts, especially through interactions with resting spores, which could have implications for pelagic-benthic coupling and overall ecosystem functioning.
Sub-terahertz PAM4 modulator based on transmission characteristic reconstruction
In this paper, we propose a sub-terahertz PAM4 modulator based on transmission characteristic reconstruction by combining meta-unit, GaAs Schottky diode, and fan branch lines. This method combined the significant electromagnetic resonant characteristics of meta-unit, the high-speed controllability of GaAs Schottky diode, and the high integration of on-chip transmission line together to realize high-speed modulation. Then, we achieve transmission characteristic reconstruction by adjusting the resonance strength under different applied voltages through fan branch lines, enabling high-order amplitude modulation of sub-terahertz waves. The experimental results show that the PAM4 modulation of sub-terahertz waves is achieved with a nearly linear variation of the transmission coefficient in the whole voltage range and a maximum modulation rate of 21 Gbps, providing a promising prospect for the development and application of integrated sub-terahertz direct high-order modulation technology.
Sleeve gastrectomy reveals the plasticity of the human gastric epithelium
Stable magnetocaloric effect over an ultrawide temperature range of 146–320 K via hydrostatic pressure in kagome magnets
Solid-state refrigeration leveraging the magnetocaloric effect (MCE) presents a sustainable and energy-efficient alternative to traditional gas compression refrigeration technologies. However, the practical utility of most magnetocaloric materials is restricted by their narrow operational temperature window. In this work, a stable magnetocaloric effect across an ultrawide temperature range of 146–320 K was achieved in Hf0.85Ta0.15Fe2 magnet via the hydrostatic pressure manipulation. Furthermore, the underlying mechanism for the extended and stable MCEs under hydrostatic pressure has been revealed by magnetization measurements and first-principles calculations. The material systems characterized by strong spin–lattice coupling exhibit considerable potential for externally manipulated hybrid-field-tuned magnetic properties and magnetocaloric performance, providing a convenient and practical approach for advancing applications in magnetic refrigeration technologies.