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Interplay between magnetization compensation temperature and thickness in ferrimagnetic CoGd alloy films
In this study, we explore the interplay between magnetization compensation temperature (Tcom) and thickness in ferrimagnetic CoGd alloys. Temperature-dependent anomalous Hall effect shows that the thickness of CoGd alloys can cause a 160 K shift in Tcom. Element-mapping image measurements display that the concentration of CoGd alloys remains constant regardless of the thickness, while magnetic property measurements indicate that the saturation magnetization (Ms) decreases as the thickness increases. A microstructure constructed by non-coplanar spin is used to account for the modulation of Tcom and Ms with the thickness. Density functional theory offers a microscopic mechanism where the difference in exchange coupling strength between Gd-Co moments should be responsible for thickness-controlled Tcom. Our findings reveal potential opportunities for the use of RE-TM ferrimagnetic films in the development of energy efficient nonvolatile spintronic devices.
Seagrass-rafted large benthic foraminifera transported into the deep Red Sea
Abstract Large shallow-marine foraminifera tests occur in deep-sea carbonate sediments of the northern Red Sea as a minor but recurring component among the remains of otherwise pelagic and deep-marine benthic biogenic assemblages. In this study of sediments recovered along the northern shore of Saudi Arabia, the symbiont-bearing taxa Sorites variabilis, S. orbiculus, Amphisorus hemprichii, Amphistegina lobifera, A. lessonii and A. radiata were identified in samples from between 430 to 1,000 m depth. These foraminifera are dwelling in shallow-water environments, associated with coral reefs and seagrass habitats. The seemingly erratic occurrence of photosymbiotic benthic organisms in deep-sea sediments was explained by the finding of such foraminifera tests along with seagrass (e.g., Halophila leaves) and macroalgae remains in pristine preservational states in the sediment of the Umluj brine pool below ~ 638 m depth. This indicates a passive transport process by rafting attached to floating macrophytes to these off-platform settings. The abundant seagrass and oceanographic conditions along the Arabian Peninsula may facilitate the transport of epiphytes and associated taxa offshore. Such long-distance transport mechanisms could further contribute to the rapid (co-)dispersal of some of these organisms into new habitats. Passive rafting should thus be considered in interpretation of sedimentary records and biogeographic patterns.
An automatic energy storage and release high-performance micro-harvester with steady-state output for low-frequency random energy harvesting
Harvesting wideband and random vibration energy in the vehicle environment is a promising route to power mobile electronic devices. Conventional energy harvesters cannot realize steady-state output, making the energy management circuit design difficult. This work presents an electromagnetic harvester with a counterweight unit, a gearbox, and a generator, which can be adapted to wideband automatic energy storage and quantized output release. The counterweight unit with the low-frequency response can effectively sense the weak vibration. The coil spring in the energy storage gear train is in particular used to store low-frequency random vibration energy in the environment and release the energy stored by the coil spring by switching the gear train. Finally, the coil spring drives the generating gear train to realize the steady-state output of mechanical energy to electrical energy. At a frequency of 2.5 Hz and an acceleration of 0.4 g, the average output power of the automatic energy storage and steady-state output release energy harvester (ASSR) by using a coil spring to first store energy and then quantize the output is 114.5 times higher than that of the method of continuous generating without using a coil spring. The ASSR's energy output can charge the lithium battery (3.7 V, 40 mAh) from 2.6 to 3.716 V during a 60 km ride at an average speed of 12.7 km/h while powering the mobile phones and Bluetooth devices continuously through the energy management circuit. The strategy shows the great potential of micro-energy harvester in various wideband random vibration environments for powering electronics.
Medicinal plants used by local communities in southern Fars Province, Iran
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.