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Rapid CO2 mineralization by zeolite via cation exchange
Giant electrostriction in textured La2Ce2O7 ceramics: A promising lead-free alternative for electromechanical conversion
The search for high-performance, lead-free materials with tailored electromechanical properties is crucial for the advancement of energy harvesting and actuator technologies. While piezoelectric materials offer promising solutions, balancing high piezoelectric response with low dielectric permittivity remains a significant challenge. Recent research has highlighted the potential of “giant” electrostriction as an alternative approach, offering substantial electromechanical responses with more favorable electrical properties. This work investigates the electrostrictive and dielectric properties of non-textured and textured La2Ce2O7 ceramics. Our findings reveal a substantial electrostrictive coefficient [M33 ≈ 10−18 (m/V)2, exceeding conventional electrostrictive materials], coupled with a high effective piezoelectric response (d33eff = 40 pm/V at E = 100 kV/cm) and a high effective piezoelectric voltage coefficient (g33eff = 146–205 × 10−3 Vm/N). Notably, [111]-texturing of La2Ce2O7 significantly reduces dielectric losses, further enhancing its suitability for energy harvesting and actuator applications. The combination of electromechanical and dielectric properties creates conditions for high energy-harvesting performance, comparable to lead-containing ceramics and far superior to lead-free alternatives. Combined with temperature stability and compatibility with Si-based microfabrication, La2Ce2O7 emerges as a promising lead-free alternative for high-performance electromechanical energy conversion applications.
Fast barrier-free switching in synthetic antiferromagnets
AbstractWe analytically solve the Landau-Lifshitz equations for the collective magnetization dynamics in a synthetic antiferromagnet (SAF) nanoparticle and uncover a regime of barrier-free switching under a short small-amplitude magnetic field pulse applied perpendicular to the SAF plane. We give examples of specific implementations for forming such low-power and ultra-fast switching pulses. For fully optical, resonant, barrier-free SAF switching we estimate the power per write operation to be $$ \sim 100 $$ ∼ 100 pJ, 10–100 times smaller than for conventional quasi-static rotation, which should be attractive for memory applications.
<i>In situ</i> determination of the optical axis orientation in a single grain using time-domain Brillouin microscopy
In this paper, we develop a method that combines optical birefringence properties and time-domain Brillouin scattering microscopy to determine in situ the optical axis orientation of each single micrometer size grain in a polycrystalline sample. We illustrate the method by investigating the room temperature multiferroic material BiFeO3 where the optical axis coincides with the ferroelectric polarization direction. We are able to find the grain orientation and also provide the sound velocity (longitudinal and transverse) since the method is based on the Brillouin scattering process. These advances open interesting perspectives for probing the anisotropy of a micrometer size grain with an extension to the evaluation of the ferroelastic domain orientation in a non-contact and non-destructive manner.
An intelligent incentive-based demand response program for exhaustive environment constrained techno-economic analysis of microgrid system
AbstractThe cost-effective scheduling of distributed energy resources through sophisticated optimization algorithms is the main focus of recent work on microgrid energy management. In order to improve load factor and efficiency, load-shifting techniques are frequently used in conjunction with additional complex constraints such as PHEV scheduling and battery life assessment. Pollutant reduction, however, is rarely highlighted as a primary goal. An incentive-based demand response (IBDR) is introduced in the proposed work to close this gap and promote load curtailment during peak hours. IBDR policy rewards participant customers with incentives for load curtailment which in turn lowers emissions and generation costs. Furthermore, a trade-off approach ensures both environmental and economic sustainability by striking a balance between cost reduction and emission reduction. Considering the fact in view that the 30–40% of the microgrid customers are willing to participate in the IBDR program, six different scenarios that have been analysed, each of which involves various levels of grid participation and different approaches to pricing in the electricity market. These scenarios also include the implementation of demand response programmes. Differential evolution algorithm was used as the optimization tool for the study. The results achieved for all the scenarios demonstrate the suitability and effectiveness of implementing the suggested IBDR strategy in terms of cost savings. According to numerical results reported, the generating cost decreased by 10–13% with the inclusion of IBDR. Additionally, a 6–8% reduction in peak and 4–5% improvement in load factor was also realised as a positive impact of the IBDR policy. The weighted economic emission dispatch algorithm offered a balanced solution that considered both the minimum generation cost and emissions for various load models in the microgrid system.
450 nm light-induced upconversion ultraviolet-C photons for optical information encryption and sterilization
Ultraviolet-C (UVC) photons play a key role in many fields such as covert communication, bacterial inactivation, information storage, and encryption. Because the UVC component of solar spectrum is almost absorbed by the ozone layer around our earth, there is little natural UVC light on the earth. Therefore, developing artificial UVC light source is of great significance. The visible-to-UVC upconversion mechanism has been demonstrated to be a useful strategy. Here, we introduce a visible-to-UVC upconversion system, that is, CaSrSiO4:Pr3+. Under excitation of both commonly used laser and light-emitting diode at 450 nm, CaSrSiO4:Pr3+ emits UVC photons. The presence of UVC light of CaSrSiO4:Pr3+ has also been confirmed by a solar blind camera, in addition to an optical spectrometer. Moreover, experimental results show that the UVC emission of CaSrSiO4:Pr3+ is assigned to a two-photon assisted upconversion mechanism. In the end, we demonstrate the potential applications of CaSrSiO4:Pr3+ for information encryption and sterilization.
Differential physiological and yield responses of selected mung bean (Vigna radiata (L.) R. Wilczek) genotypes to various high-temperature stress regimes
Synaptic transistor based on reversible hydrogenation of graphene channel
Graphene transistors with a gate-controlled transition of neuromorphic functions between artificial neurons and synapses have attracted increasing attention because the atomic thickness could be easily modulated by different stimuli, which is very beneficial for synaptic applications. As a modulation method, a graphene electrolyte-gated transistor (EGT) has been proposed, in which the electrical conductance of the graphene channel is modulated by reversible electrochemical hydrogenation of graphene. However, only a sparse physically realized graphene-based synaptic H+-EGTs have been reported due to the difficulty of achieving a high concentration of protons at the electrolyte–graphene interface. Here, we have reported the H+-EGTs with a highly defective graphene channel and a gel electrolyte [H3PO4/poly(vinyl alcohol)], which is based on hydrogenation and dehydrogenation of highly defected-graphene, performing the similar functions as the common artificial synaptic transistors, with good retention (&lt;1% attenuation per minute), analog tunability (&gt;200 nonvolatile states), and precisely controllable resistance (∼0.4% step flipped per synaptic event). In addition, the cyclic voltammetry test was applied to confirm the hydrogenation and dehydrogenation of the graphene channel. It is expected that this principle can provide ideas for designing graphene-based artificial synapses enabling integrated functions of in-memory computing and in-memory sensing for the neuromorphic system.
The effects of war-related experiences on mental health symptoms of individuals living in conflict zones: a longitudinal study
Unipolar fields produced by ultrafast optical gating of terahertz pulses
Unipolar (sub-cycle) electromagnetic fields are a subject of current interest as a possible useful tool for light–matter interaction studies and applications. We propose, numerically simulate, and experimentally prove a method to produce unipolar terahertz fields by optical gating of conventional bipolar terahertz pulses in a GaAs wafer. In particular, picosecond long unipolar pulses with the electric field strength of ∼1 kV/cm were detected by electro-optic sampling at the output of the wafer.
A risk prediction model for endometrial hyperplasia/endometrial carcinoma in premenopausal women
Low-pressure CVD grown Si-doped β-Ga2O3 films with promising electron mobilities and high growth rates
In this work, we systematically investigated the growth of Si-doped β-Ga2O3 films using low-pressure chemical vapor deposition (LPCVD) system, achieving high room-temperature Hall mobilities of 162 and 149 cm2/V·s at carrier concentrations of 1.51 × 1017 and 1.15 × 1017 cm−3, respectively, for homoepitaxial (010) β-Ga2O3 film grown on β-Ga2O3 substrates and heteroepitaxial (2¯01) β-Ga2O3 film grown on off-axis c-sapphire substrate with 6° miscut-representing the highest mobilities reported for LPCVD-grown β-Ga2O3 materials. Carrier concentrations were precisely tuned by varying SiCl4 flow rates at a growth temperature of 1000 °C, resulting in concentrations ranging from 1.15 × 1017 to 1.19 × 1019 cm−3 as confirmed by both Hall and capacitance–voltage (C–V) measurements. The films exhibited high crystalline quality, confirmed by high resolution x-ray diffraction and Raman spectroscopy, indicating phase purity and structural integrity. Surface morphologies characterized by field-emission scanning electron microscope and atomic force microscopy showed a strong correlation between carrier concentrations and surface smoothness, with lower concentration resulting in reduced RMS roughness. Secondary Ion Mass Spectrometry analysis revealed uniform Si incorporation, with low carbon, hydrogen, and chlorine impurities below detection limits, indicating high purity of the films. A high low-temperature peak mobility exceeding &gt;843 cm2/V·s was achieved at a carrier concentration of 1.74 × 1016 cm−3 for a (2¯01) β-Ga2O3 heteroepitaxial film at 80 K, highlighting the high purity and low compensation of these films. These findings emphasize the potential of LPCVD growth system for producing high-purity β-Ga2O3 films with thickness ranging between ∼2.3 and 11.7 μm and faster growth rates (∼4.7–17 μm/h), promising transport properties, controllable doping, and scalability for developing high-power vertical devices.
Unifying spatiotemporal and frequential attention for traffic prediction
Abstract Intelligent transportation systems heavily rely on forecasting urban traffic flow, and a variety of approaches have been developed for this purpose. However, most current methods focus on exploring spatial and temporal dependencies in historical traffic data, while often overlooking the inherent spectral characteristics hidden in traffic time series. In this paper, we introduce an approach to analyzing traffic flow in the frequency domain. By integrating attention mechanisms, we comprehensively capture the hidden correlations among space, time, and frequency dimensions. By leveraging deep learning to capture spatial correlations in traffic flow and applying spectral analysis to fuse time series data with underlying periodic correlations in both the time and frequency domains, we develop an innovative traffic prediction model called the Space-Time-Frequency Attention Network (STFAN). The core of this network lies in the application of attention mechanisms, which project the hidden states of current traffic features across the space, time, and frequency domains onto future hidden states. This approach enables a comprehensive learning of the relationships between each dimension and the future states, ultimately allowing for accurate predictions of future traffic flow. We carry out experiments on two publicly available datasets from the California Department of Transportation, PeMS04 and PeMS08, to assess the performance of the proposed model. The results demonstrate that the proposed model outperforms existing baseline models in terms of predictive accuracy, particularly for mid- and long-term traffic flow forecasting. Finally, the ablation study confirmed that the frequency domain characteristics of traffic flow significantly influence future traffic conditions, demonstrating the practical effectiveness of the model.
A 15-Item modification of the PSP rating scale to improve clinical meaningfulness and statistical performance
Torsion-induced rapid switching and tunability of multistable state ferroelectric polarization
The pulse-based rapid domain structure switching method in ferroelectric memristors has stability and other issues, limiting its applications. In this study, we perform atomic simulations to investigate the polarization domain switching behavior of ferroelectric materials under non-pulse torsional loading. During torsion, uniformly distributed spontaneous polarization transitions to predominantly in-plane polarization and finally evolves to predominantly out-of-plane polarization. The out-of-plane polarization remains stable during torsion and can be adjusted through mechanical and electric fields to achieve multistability. This evolution behavior is attributed to the rapid increase in initial normal stress and continuous cyclic variation of shear stress during torsion. The non-pulse control method developed in this study lays the foundation for further research and utilization of polarization regulation in ferroelectric materials, potentially advancing the application of ferroelectric memristors.
Bathymetry estimation for coastal regions using self-attention
Parasitic structure defect blights sustainability of cobalt-free single crystalline cathodes
AbstractRecent efforts to reduce battery costs and enhance sustainability have focused on eliminating Cobalt (Co) from cathode materials. While Co-free designs have shown notable success in polycrystalline cathodes, their impact on single crystalline (SC) cathodes remains less understood due to the significantly extended lithium diffusion pathways and the higher-temperature synthesis involved. Here, we reveal that removing Co from SC cathodes is structurally and electrochemically unfavorable, exhibiting unusual voltage fade behavior. Using multiscale diffraction and imaging techniques, we identify lithium-rich nanodomains (LRNDs) as a heterogeneous phase within the layered structure of Co-free SC cathodes. These LRNDs act as critical tipping points, inducing significant chemo-mechanical lattice strain and irreversible structural degradation, which exacerbates the voltage and capacity loss in electrochemical performance. Our findings highlight the considerable challenges of developing Co-free SC cathodes compared to polycrystalline ones and emphasize the need for new strategies to balance the interplay between cost, sustainability, and performance.
Two-color strong-field terahertz amplification in the non-identical focusing condition
High optical-to-terahertz (THz) conversion efficiency is crucial for generating THz waves. Strong-field ionization using a bi-focal bi-chromatic geometry produces cascading plasmas, leading to amplified THz generation and extended THz bandwidth. We investigate the effect of focal length in this bi-focal geometry on THz intensity. The results show that the THz intensity produced with non-identical focal lengths of the bi-chromatic fields is 25% higher than that of identical focal lengths, and 15 times higher than traditional bi-chromatic THz generation. The electro-optic sampling measurements reveal that the THz-electric-field intensity generated by the bi-focal bi-chromatic field exhibits periodic oscillations, which results from the modulation of the photoelectron's asymptotic velocity by the relative phase of the bi-chromatic pulses, and are consistent with the photocurrent model. The photocurrent simulations indicate that the self-compression of the second harmonic pulse significantly enhances THz amplification and extends the THz bandwidth. These findings deepen understanding of the THz generation mechanism and suggest potential avenues for optimizing THz sources.