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Strain-engineering the lattice thermal conductivity of 2D kagome silica
Two-dimensional (2D) materials exhibit a significant potential for thermal management and thermoelectric energy generation due to their unique electrical and thermal transport properties that enhance performance. Their notable stretchability indicates the feasibility of employing strain engineering to optimize both electronic and thermal properties. In this study, we apply first-principles computational methods and the Boltzmann transport equation to explore the impact of strain and higher-order anharmonicity from four-phonon (4ph) scattering on the thermal conductivity (κL) of 2D silica. Our results indicate that under a small strain of 3%, κL increases due to the decrease in the phonon scattering rate and phonon phase space. However, under larger strains (8%), κL decreases significantly due to an increased phonon–phonon scattering rates. These findings provide deeper insights into the thermal transport behavior of 2D silica, paving the way for future research in strain and phonon engineering in 2D materials.
Intelligent evaluation of coal mine solid filling effect using fuzzy logic and improved D-S evidence theory
High-pressure high-temperature synthesis of cubic B-C-N compounds with high thermal stability
Exploring superhard materials is of great significance in materials research. Ternary B-C-N superhard compounds exhibit a superior thermal stability to diamond, with hardness surpassing cubic boron nitride. However, synthesizing cubic B-C-N compounds is challenging, and few studies have been reported on their high-temperature oxidation resistance, impeding their potential applications. In this study, cubic B-C-N compounds (c-BCN) were synthesized using the high-pressure high-temperature synthesis method at 10 GPa and 1530 °C, half the reported pressure and one-quarter lower than the reported temperature. The thermal stability of the obtained c-BCN compound was examined. The results indicated that the air oxidation temperature of c-BCN was as high as 1200 °C, suitable for high-speed cutting of hardened steels. This study provided a production method of cubic B-C-N superhard compounds and extended their potential applications to milling/machining.
Underlying mechanism behind the dynamic mechanical behavior of sandstone with varying moisture content under medium speed impact
Experimental demonstration of synchronization between two quantum dot passively mode-locked laser frequency combs utilizing bidirectional optical coupling
Two monolithic edge-emitting passively mode-locked InAs/InGaAs semiconductor quantum dot lasers generating ps optical pulses at repetition rates of 10 GHz and optical frequency combs centered at 1260 nm are mutually coupled in an all-optical passive synchronization experiment. The two lasers, with different free-running repetition rates, are coupled through a long delay fiber path, they synchronize, and generate optical pulse trains with identical repetition rates in a wide range of experimental conditions (optical frequency, optical delay, and coupling strength). The common repetition rate can be easily fine-tuned with the control of the external coupling path length. In synchronized state, both lasers operate with significantly reduced timing jitter with respect to their free-running values. Finally, under specific conditions, the repetition rate locking is accompanied by partial mutual coherence between the lasers, as indicated by the formation of interferometric fringes.
The evolution, variation and expression patterns of the annexin gene family in the maize pan-genome
A perspective on mechanism of heat transfer and performance optimization in advanced thermal interface materials
In recent years, thermal interface materials (TIMs) have garnered increasing attention in the field of thermal management for electronic devices. By effectively bridging the gap between electronic components and heat sinks, these materials significantly enhance heat transfer efficiency. This paper systematically reviews and analyzes the mechanisms, and the influencing factors associated with TIMs composed of graphene, carbon nanotubes, MXene, boron nitride compounds, and metal nanowires over recent years. Additionally, it delves into the challenges faced by these materials and explores its future research directions in thermal management. Future research endeavors are anticipated to focus on innovative designs for thermal conductivity networks in order to achieve further enhancements in the TIMs performance, ultimately paving the way for their practical application and commercialization.
Temporal action localisation in video data containing rabbit behavioural patterns
Non-ergodic-induced negative differential piezoresponse in relaxor ferroelectrics
Relaxor ferroelectrics exhibit a unique competition between long-range and short-range interactions that can be tuned electrically, which prioritizes these materials in a broad range of electro-mechanical energy-conversion technologies, including biomedical imaging and electric-charge generators. Here, we demonstrate differential negative piezoresponse by utilizing the short-range interactions in relaxor ferroelectrics. The effect was observed over a broad temperature range with local piezoresponse spectroscopy in unpoled samples, while no negative piezoresponse was observed when the material was pre-poled. These measurements suggest that the effect, which is promising for power-generation applications, originates from non-ergodic behavior. Complementary macroscale impedance and dielectric constant measurements as a function of temperature and frequency supported the mesoscopic findings. Bearing in mind the direct relationship between piezoresponse and capacitance, relaxor ferroelectrics appear as an excellent platform for the emerging technology of low-power negative-capacitance transistors.
Rendering the European neutron research landscape
Prediction of toroidal dipole resonance in dielectric metasurface by deep learning
Toroidal dipole (TD) resonance is a promising method for enhancing light–matter interactions, offering significant potential in photonic device design. While numerical simulations are commonly used to study TD resonances, they are computationally expensive and time consuming. In this study, we propose deep learning strategies to predict TD resonances induced by Brillouin zone folding. A fully connected neural network is developed to predict transmission mapping, transmission spectra, multipole scattering, and TD components. Comparison with numerical simulations shows that the neural network predicts TD resonance efficiently and accurately. Experimental validation through fabricated samples further confirms the strong TD response. Our work presents an effective tool for quickly and precisely exploring nanophotonic properties and offers a promising approach for predicting high-quality factor TD resonators.
Analysis of social media language reveals the psychological interaction of three successive upheavals
Dual-metal hybrid metasurface for liquid-tunable infrared polarization-selective perfect absorption
Nanostructure-based metasurfaces provide a promising route for arbitrarily manipulating light waves, especially versatile absorption. Although various meta-absorbers have been studied for perfect absorption, it remains a challenge to achieve high-contrast polarization-dependent absorption with dynamic tunability. Here, a dual-metal hybrid metasurface is demonstrated for polarization-selective perfect absorption and reflection with liquid tuning capabilities in the infrared band. Based on the metal–insulator–metal architecture, the metasurface composed of Al/Ti nanostrips enables an intense absorption resonance at x-polarization and reflects light as a mirror at y-polarization, thus acting as a high-performance linear polarizer. The absorption peak wavelength can be continuously tailored from 1200 to 1850 nm with an average absorption > 99% by scaling the unit-cell period of metasurfaces. Furthermore, the perfect absorption wavelength of the metasurface exhibits a large range switch (>750 nm) through immersion tuning, and its absorption remains above 99.5%. The proposed dual-metal hybrid metasurface for liquid-tunable absorption can promote practical technologies of dynamic polarizers, photodetectors, and optical imaging.
A lightweight coal mine pedestrian detector for video surveillance systems with multi-level feature fusion and channel pruning
Enhancement to the conductivity of surface transfer-doped (111) diamond through thermochemical surface etching
The use of a transition metal catalyzed thermochemical etching method for improving the carrier transport properties of the near-surface two-dimensional (2D) hole gas in surface transfer-doped hydrogen-terminated (111) diamond is demonstrated. Using Ni0.8Cr0.2 films deposited and annealed to a temperature of 900 °C, with up to three etch cycles, preferential (111) surface etching produces large terraces exceeding 10 μm in size with a surface microroughness, σRMS2λ, that is two orders of magnitude lower than for the pre-etched (111) surface. Magnetotransport measurements on hydrogen-terminated Hall bars engineered on the pre- and post-etched surfaces and rendered conductive by the adsorbed water layer formed on exposure to ambient conditions demonstrate that this etching causes an improvement in the hole mobility by an order of magnitude, resulting in a measured sheet resistivity of 1.04 kΩ/sq at a temperature of 4.2 K without gating.
A method for the identification of lactate metabolism-related prognostic biomarkers and its validations in non-small cell lung cancer
Investigating the interplay between spin polarization and magnetic damping in CoxFe80−xB20 for magnonics applications
For magnonics and spintronics applications, the spin polarization (P) of a transport current and the magnetic damping (α) play a crucial role, e.g., for magnetization dynamics and magnetization switching applications. In particular, P in a glassy (amorphous) 3d transition ferromagnet such as CoFeB and α are both strongly affected by s−d scattering mechanisms. Hence, a correlation can be expected, which is a priori difficult to predict. In this work, P and α are measured using current-induced Doppler shifts using propagating spin wave spectroscopy and broadband ferromagnetic resonance techniques in blanket films and current-carrying CoxFe80−xB20 alloy microstrips. The measured P ranges from 0.18 ± 0.05 to 0.39 ± 0.05, and α ranges from (4.0 ± 0.2)·10−3 to (9.7 ± 0.6)·10−3. We find that for increasing P, a systematic drop in α is observed, indicating an interplay between magnetic damping and the spin polarization of the transport current, which suggests that interband scattering dominates in CoxFe80−xB20. Our results may guide future experiments, theory, and applications in advancing spintronics and metal magnonics.
Design and implementation of PLA/GO/metal oxide composites for CO2 sensing application
Abstract This study investigates the modification of polylactic acid (PLA) by the incorporation of graphene oxide (GO) and metal oxides (ZnO and CuO), with the aim of developing efficient CO₂ sensors. Key properties, including total dipole moment (TDM), energy gap (ΔE), molecular electrostatic potential (MESP), and density of states (DOS), were calculated using density functional theory (DFT) to gain insight into the interactions between the composites and CO₂ gas. Experimental techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and optical confocal microscopy were used to validate the material composition and bonding mechanisms. The analysis revealed the presence of SiO₂ impurities in the PLA matrix, which could potentially affect the sensing behavior of the composite. The composites demonstrated effective CO₂ sensing capabilities in experimental tests. This combined theoretical and experimental approach demonstrates that PLA/GO/metal oxide composites offer significant potential for sustainable CO₂ sensing, contributing to air quality monitoring and greenhouse gas regulation.
Control of impurity incorporation into CVD diamond synthesized with <i>tert</i>-butylphosphine for quantum applications
Nitrogen-vacancy (NV) centers in phosphorus-doped diamond have potential applications in quantum technologies because their electron spin has the longest spin coherence time among those in solid systems at room temperature (RT) and because their negative charge state is more stable than that in undoped diamond. However, the conventional phosphorus source, phosphine, is toxic and explosive; a safer precursor is therefore preferred. We consequently attempted to synthesize phosphorus-doped diamonds using tert-butylphosphine (TBP), which has lower toxicity and explosivity than phosphine. However, controlling phosphorus incorporation during doping with TBP is difficult because it condenses easily and remains in the synthesis reactor due to its low boiling point. Here, we report controlling the incorporation of impurities by optimizing the synthesis conditions, such as the synthesis pressure. Comparing diamonds synthesized at 15 and 50 kPa reveals that the phosphorus concentration was reduced by 93% and the nitrogen concentration by 72% in the diamond synthesized at 50 kPa. For diamonds prepared under optimized conditions in our synthesis reactor, a long spin coherence time (T2 = 2.23 ms) for NV centers with almost perfect selective alignment of the NV axes was achieved. The T2 was comparable to the longest reported length for NV centers in a sample synthesized with phosphine, indicating that TBP is a promising phosphorus source for obtaining NV centers with excellent properties. We also achieved high electron mobility [580 cm2/(V s) at RT] in diamonds synthesized with TBP; this value is comparable to that for diamonds synthesized with phosphine.