Browse Articles

An Overview of Flame‐Retardant Materials for Triboelectric Nanogenerators and Future Applications

Abstract Triboelectric nanogenerators (TENGs) have gained significant attention for ability to convert mechanical energy into electrical energy. As the applications of TENG devices expand, their safety and reliability becomes priority, particularly where there is risk of fire or spontaneous combustion. Flame‐retardant materials can be employed to address these safety concerns without compromising the performance and efficiency of TENGs. The primary focus of this review is on flame‐retardant materials, including polymers, biomaterials, liquid polymers, aerogels, and carbon‐based materials. The fundamental properties of these materials for TENG applications are elucidated. The characteristics of each material type are described, along with their potential to boost the safety and performance of TENGs. The importance of flame retardancy in advancing TENG technology can be projected from its usage in wearable electronics, self‐powered sensors, and smart textiles. Current challenges such as material compatibility, fabrication complexity, and environmental concerns are addressed, along with proposed strategies for overcoming them. This review underscores the significance of flame‐retardant materials in strengthening the functionality and safety of TENG devices, paving the way for their widespread adoption across various industries.  

A significant enhancement in thermal conductivity of plastic crystals under compressive strain by deep potential molecular dynamics

The unique properties of plastic crystals highlight their potential for use in solid-state refrigeration. However, their practical applications are limited by thermal hysteresis due to low thermal conductivity. In this study, the effect of compressive strain on the thermal transport properties of [(CH3)4N][FeCl4] was investigated using molecular dynamic simulation with a deep potential. It is found that the thermal conductivities along the [100], [010], [001], [101], and [011] directions are enhanced under 9% strain by 110%, 580%, 114%, 408%, and 268%, respectively. The underlying mechanisms are analyzed through vibrational density of states and spectral energy densities. The enhancement in thermal conductivity is primarily due to reduced phonon scattering. These findings offer theoretical insights for the practical application of plastic crystals in thermal management systems.

Detection and segmentation of pulmonary embolism in 3D CT pulmonary angiography using a threshold adjustment segmentation network

High endurance and low coercive voltage ferroelectric tunnel junction by electrode engineering

In this paper, we report a high endurance and low coercive voltage (Vc) ferroelectric tunnel junction (FTJ) device by replacing the TiN top electrode with W electrode after annealing. This method implants a TiNOx thin layer, which reduces leakage current and increases breakdown voltage (Vbd), leading to better device endurance. It can also effectively promote the formation of orthogonal phase and inhibit tetragonal phase during the wake-up process, which contributes to reducing Vc. Therefore, the proposed 5 nm H0.5Z0.5O2 (HZO) FTJ exhibits excellent performances, such as low Vc (0.49 V), small Vc/Vbd ratio (19.1%), high endurance (>1011), and high double remanent polarization (2Pr = 41 μC/cm2), which are the frontier of the reported HfO2-based FTJ. The results strongly indicate that the FTJ has high potential in addressing the frequent weight changes generated by brain-like computational training and learning.

Integrated geophysical prospecting for deep ore detection in the Yongxin gold mining area, Heilongjiang, China

Abstract Geophysical exploration techniques play a pivotal role in enhancing the accuracy of mineral prospecting predictions. However, relying solely on individual methods often introduces uncertainties. This study presents a case study from the Yongxin gold deposit, where we integrated audio-frequency magnetotelluric (AMT) methods with gravimetric surveying and high-resolution magnetic profiling to overcome this challenge. Advanced three-dimensional modeling techniques were utilized to precisely delineate lithological variations and deep-seated mineralization features inherent to the area. The inversion and interpretation of cross-sectional AMT data provided insights into the subsurface structure down to a depth of 1.5 km. This enhanced data reliability was achieved through an integrated interpretation constrained by multiple datasets, enabling a more accurate inference of the deeper geological framework. Furthermore, by amalgamating various datasets, we uncovered characteristics of deep mineralization, the three-dimensional configuration of mineralization-related rock masses, and the spatial orientation of known ore deposits. This holistic approach facilitated a comprehensive understanding of the deeper geological formations. A detailed analysis of ore-controlling structures and exploration markers led to the development of a tailored geological-geophysical model for mineral exploration within the study area, serving as a valuable reference for future deep exploration efforts.

Giant correlation, many body and exciton effects in Janus ferrovalley material H-FeClBr

The family of transition metal dichlorides are recently found to be ferrovalley materials, exhibiting desirable spontaneous valley polarization that is a key to practical applications. In this work, Janus monolayer H-FeClBr is investigated as a case study by performing first-principles calculations. We focus on the giant correlation and many-body and exciton effects that will essentially modulate the electronic, valleytronic, and optical properties. The H-FeClBr presents strong ferromagnetism and spin–orbit coupling, giving rise to large spontaneous valley polarization. Due to the enormous electron correlation of the localized d electrons of the Fe atoms, the energy gap calculated using Hubbard U and hybrid functional HSE06 is extraordinarily widened by about seven times with respect to the Perdew–Burke–Ernzerhof (PBE) counterpart. As a result, the orbitals in valley bands are exchanged, the sign of the valley Berry curvatures is switched, and the valley polarization is reversed. The GW calculations further enhance the gap significantly to about 4 eV, which is close to ten times that of the PBE gap and indicative of very strong many-body effects. The exciton spectrum obtained by solving the Bethe–Salpeter equations reveals colossal electron–hole interaction, giving rise to a giant exciton binding energies of ∼1.54 eV. Corresponding to the optical excitation in the two inequivalent valleys with unequal gaps, there are two split exciton peaks, as opposed to the A and B exciton peaks in MoS2 spectrum, which correspond to the optical transitions in the same valley.

Large inversion effects for common objects and objects that require little if any holistic processing

Synergistic Integration of Halide Perovskite and Rare‐Earth Ions toward Photonics

Abstract Halide perovskites (HPs), emerging as a noteworthy class of semiconductors, hold great promise for an array of optoelectronic applications, including anti‐counterfeiting, light‐emitting diodes (LEDs), solar cells (SCs), and photodetectors, primarily due to their large absorption cross section, high fluorescence efficiency, tunable emission spectrum within the visible region, and high tolerance for lattice defects, as well as their adaptability for solution‐based fabrication processes. Unlike luminescent HPs with band‐edge emission, trivalent rare‐earth (RE) ions typically emit low‐energy light through intra‐4f optical transitions, characterized by narrow emission spectra and long emission lifetimes. When fused, the cooperative interactions between HPs and REs endow the resulting binary composites not only with optoelectronic properties inherited from their parent materials but also introduce new attributes unattainable by either component alone. This review begins with the fundamental optoelectronic characteristics of HPs and REs, followed by a particular focus on the impact of REs on the electronic structures of HPs and the associated energy transfer processes. The advanced synthesis methods utilized to prepare HPs, RE‐doped compounds, and their binary composites are overviewed. Furthermore, potential applications are summarized across diverse domains, including high‐fidelity anticounterfeiting, bioimaging, LEDs, photovoltaics, photodetection, and photocatalysis, and conclude with remaining challenges and future research prospects.

Sole‐Solvent High‐Entropy Electrolyte Realizes Wide‐Temperature and High‐Voltage Practical Anode‐Free Sodium Pouch Cells

Abstract Anode‐free sodium batteries (AFSBs) hold great promise for high‐density energy storage. However, high‐voltage AFSBs, especially those can stably cycle at a wide temperature range are challenging due to the poor electrolyte compatibility toward both the cathode and anode. Herein, high‐voltage AFSBs with cycling ability in a wide temperature range (−20–60 °C) are realized for the first time via a sole‐solvent high‐entropy electrolyte based on the diethylene glycol dibutyl ether solvent (D2) and NaPF 6 salt. The sole‐solvent high‐entropy electrolyte with unique solvent‐ions effect of strong anion interaction and weak cation solvation enables entropy‐driven electrolyte salt disassociation and high‐concentration contact ion pairs, thus simultaneously forming stable anion‐derived electrode–electrolyte interphases on cathode and anode. Moreover, the wide liquid range of D2 further extends the temperature extremes of the battery. Consequently, ampere‐hour (Ah)‐level anode‐free sodium pouch cells with cyclability in a wide temperature range of −20–60 °C are realized. Impressively, the pouch cell achieves a leadingly high cell‐level energy density of 209 Wh kg −1 and a high capacity retention of 83.1% after 100 cycles at 25 °C. This work provides inspirations for designing advanced electrolytes for practical AFSBs.

Probing thickness-dependent tip-induced band bending in MoS2

Scanning tunneling spectroscopy (STS) has played an important role in determining the electronic band structures of semiconductors. However, the tip-induced band bending (TIBB) could strongly affect the measured valence and conduction band edges, which are of vital importance for a semiconductor. In the literature, the presence or absence of the TIBB effect in a given STS measurement is often not discussed thoroughly. In this work, we quantitatively investigate the TIBB effect in MoS2 with varying thicknesses using light-modulated contact-mode STS. Our results demonstrate that the TIBB effect is strongly dependent on the thickness of MoS2. With thin MoS2 of a few atomic layers (several nanometers), the TIBB approaches zero, and the measured STS can accurately reflect the band edges. While for thicker MoS2 of ∼100 nm, the TIBB can be as large as ∼1 eV. This work clarifies the ambiguity about the TIBB effect and provides a foundation for the interpretation of STS data on atomically thin semiconductors.

Sensory processing sensitivity in adult dental patients and its relation to perceived stress, cortisol, and serotonin secretion

Untethered Soft Robots Based on 1D and 2D Nanomaterials

Abstract Biological structures exhibit autonomous and intelligent behaviors, such as movement, perception, and responses to environmental changes, through dynamic interactions with their surroundings. Inspired by natural organisms, future soft robots are also advancing toward autonomy, sustainability, and interactivity. This review summarizes the latest achievements in untethered soft robots based on 1D and 2D nanomaterials. First, the performance of soft actuators designed with different structures is compared. Then, the development of basic locomotion forms, including crawling, jumping, swimming, rolling, gripping, and multimodal, mimicking biological motion mechanisms under dynamic stimuli, is discussed. Subsequently, various self‐sustained movements based on imbalance mechanisms under static stimuli are introduced, including light tracking, self‐oscillating, self‐crawling, self‐rolling, and flying. Following that, the progress in soft actuators integrated with additional functionalities such as sensing, energy harvesting, and storage is summarized. Finally, the challenges faced in this field and the prospects for future development are discussed.

Temperature-dependent defect dipoles polarization of (La, Nb) co-doped TiO2/PEI microwave absorption materials

Point defect engineering has emerged as a key strategy to pursue efficient microwave absorption (MA) by effectively balancing impedance matching and polarization loss. Nevertheless, the detailed interplay between the temperature-driven dielectric relaxation characteristics and the absorption dissipation mechanisms remains an area that requires deeper exploration. Here, (La0.5Nb0.5)xTi1-xO2/polyetherimide (x = 0, 0.25%, 0.5%, and 1%) composites were prepared by co-doping TiO2 with donor (Nb5+) and acceptor (La3+) ions. As the concentration of point dipoles increases, the enhanced polarization loss significantly amplifies MA dissipation, demonstrating substantial potential for high-temperature applications at x = 0.5%. Notably, the point dipole polarization model provides a more comprehensive explanation of the relaxation time (τ), activation energy (Wη), and T. This behavior is attributed to strong polarization loss resulting from short-range electronic motion suppressed by those defect clusters, which provides a theoretical foundation for further understanding the mechanisms of microwave dissipation and high-temperature absorption potential.

Statistical and machine learning analysis of diesel engines fueled with Moringa oleifera biodiesel doped with 1-hexanol and Zr2O3 nanoparticles

Engineering EVs‐Mediated mRNA Delivery Regulates Microglia Function and Alleviates Depressive‐Like Behaviors

Abstract The development of new non‐neurotransmitter drugs is an important supplement to the clinical treatment of major depressive disorder. The latest development of mRNA therapy provides the possibility for the treatment of some major diseases. The endoplasmic reticulum (ER) and mitochondria constitute a highly interconnected set of fundamental organelles within cells. The interconnection between them forms specific microdomains that play pivotal roles in calcium signaling, mitochondrial dynamics, inflammation, and autophagy. Perturbations in ER‐mitochondrial connections may contribute to the progression of neurological disorders and other diseases. Herein, an extracellular vesicles‐based delivery system, grounded in mRNA gene therapy and integrated with nanomedicine technology is devised. This system is engineered to traverse the blood–brain barrier and specifically target the central nervous system (CNS), facilitating the simultaneous delivery of mRNA drugs and metallic nanozymes into the brain. This dual‐pronged approach, targeting ER and mitochondrial crosstalk, inhibits microglial overactivation, promotes M2 polarization of microglia, and suppresses the NF‐κB signaling pathway. Consequently, it significantly alleviates Lipopolysaccharides‐induced neuroinflammatory responses and ameliorates anxiety‐ and depression‐like behaviors. This study demonstrates a novel antidepressant therapeutic strategy and establishes a new paradigm for mRNA gene therapy in CNS diseases.

Visible light-driven synaptic transistors based on bilayer InGaZnO homojunction for neuromorphic computing

The development of photoelectric synaptic transistors (PSTs) using visible light-driven mimicking synaptic behaviors represents a key advancement toward biomimetic visual systems. This study proposes a PST based on bilayer indium-gallium-zinc-oxide (IGZO) homojunctions with tunable gallium ratios. By optimizing the gallium content, oxygen vacancy concentrations in the channel were precisely controlled, suppressing deionization processes and enhancing device performance. The IGZO homojunction PST demonstrated outstanding electrical characteristics (Ion/Ioff = 1.2 × 107, μ = 3.88 cm2/Vs, Vth = 0 V) and exhibited high photocurrent and robust persistent photoconductivity under visible light. The device mimicked various synaptic behaviors, including excitatory postsynaptic current, paired-pulse facilitation, the transition from short-term plasticity to long-term plasticity, spiking-rate-dependent plasticity, and spike-timing-dependent plasticity. Furthermore, leveraging the potentiation and depression behaviors of the IGZO homojunction PST, a triple-layer neural network achieved 96.8% accuracy in pattern recognition tasks. These results underscore the IGZO homojunction PST's immense potential for advancing artificial vision systems.

White supremacist beliefs predict discrimination but not implicit bias towards perceived Arab Middle Eastern Muslim men

Growth of CdTe films on patterned graphene/Ge (100) by molecular beam epitaxy

Growth on patterned graphene/Ge provides a route to improve the film quality of large mismatch heteroepitaxy and simultaneously facilitate the transfer of epitaxial films; however, the growth process and its associated technical challenges remain unclear. In this work, the molecular beam epitaxy (MBE) growth of CdTe films on micro-scale patterned strip-like graphene/Ge (100), containing selective area epitaxy (SAE) of CdTe seeds on exposed Ge and the merging process of CdTe seeds, were systematically investigated. The effects of growth temperature on the SAE of CdTe seeds were studied in detail, and a growth model of the CdTe seeds was proposed. Additionally, we examined the morphology and crystal quality of CdTe films at different growth stages, identifying the suppression of CdTe nucleation on graphene during the CdTe seed growth and merging as a key challenge to obtain high-quality films on patterned graphene/Ge.

Bistability and bifurcations in HIV-1 infection model with non-monotone responses

Abstract This study proposes a mathematical model for HIV-1 infection and investigates their qualitative dynamics such as stability, bistability, and bifurcation properties. The model builds on existing HIV-1 models by incorporating the effects of antiretroviral therapy (ART) and modeling immune-cell dynamics through non-monotone functional responses, capturing may help to gain insights into immune activation behaviors. Further, this study discusses the presence of bistability and bifurcation phenomena, indicating that HIV-1 infection dynamics can switch between multiple equilibriums depending on model parameters and initial conditions. To ensure the disease spread in the community, this study determines the formula to calculate the basic reproduction number for the model. Theoretically, this study performs the disease-free, immune-free, and infection steady-state analysis to determine the threshold conditions focusing on saddle-node, trans-critical and Hopf-type bifurcation relies on significant parameters. The study also works on a data-driven modeling approach to determine the appropriate population parameters of the model with the help of clinical trials performed on human patients for 15 weeks.

Minimization of temperature reached by adiabatic demagnetization refrigeration in Ce-based intermetallic Ce2(Cu1<b>−</b> <i>x</i>Ni<i>x</i>)2In

Magnetic entropy remaining near absolute zero temperature in the antiferromagnetic (AFM) critical state is expected to be usable for the cryogenic magnetic refrigeration. In this paper, we report quasi-adiabatic demagnetization refrigeration for Ce2(Cu1−xNix)2In (0≤x≤0.38) whose parent compound Ce2Cu2In orders antiferromagnetically below 6 K, by using a laboratory-made cell attachable to a commercial 4He refrigerator with a base temperature of 1.8 K. The final temperature by the quasi-adiabatic demagnetization as a function of x indicates a local minimum of 1 K at the AFM critical composition of x∼0.3. The validity of this result is confirmed by our specific-heat measurements. Our work motivates the future developments of Ce-based cryogenic magnetic refrigerants with the lower characteristic temperature in view of the low cost and easiness in synthesizing compared with Yb-based counterparts.