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Reconstruction of porous media pore structure and simulation effect analysis of multi-index based on SNESIM algorithm
Abstract The pore structure of porous media directly affects its permeability characteristics and fluid flow properties, making the accurate reconstruction of these structures of great significance. In recent years, multi-point statistics (MPS) methods have been widely used in pore structure modeling. Among them, the SNESIM algorithm, as an advanced MPS technique, has been extensively applied in the study of porous media pore structures. This paper aims to investigate the use of the SNESIM algorithm for reconstructing pore structures on 2D core slices with varying porosities, all taken from the same core. It also analyzes the effectiveness, limitations, and applicable conditions of the algorithm. This study utilizes CT scan images to construct digital core technology and applies the SNESIM algorithm to reconstruct pore structures of core slices with different porosities. By analyzing performance parameters such as porosity, pore throat ratio, average grain radius, coordination number, and permeability, the study shows that the reconstructed images(RI) from most samples maintain a trend similar to that of the training images(TI), demonstrating the good applicability and reliability of the SNESIM algorithm in pore structure reconstruction. However, the core slices used in this study were all taken from the same core. Effectively transferring the pore structures from the 2D plane to the 3D pore space and restoring the pore structures to the greatest extent still requires further research. In particular, when dealing with complex pore structures, the accuracy and performance of the SNESIM algorithm need further improvement. Future research will focus on optimizing the algorithm to handle more diverse pore structures and exploring 3D reconstruction methods to more comprehensively describe and analyze the pore characteristics in actual porous media.
Heterostructure and interfacial engineering for low-resistance contacts to ultra-wide bandgap AlGaN
We report on the heterostructure and interfacial engineering of metalorganic chemical vapor deposition (MOCVD) grown reverse graded contacts to ultra-wide bandgap AlGaN. A record low contact resistivity of 1.4 × 10−6 Ω cm2 was reported on an Al0.82Ga0.18N metal-semiconductor field effect transistor by compositionally grading the contact layer from Al0.85Ga0.15N → Al0.14Ga0.86N with degenerate doping and proper interfacial engineering considering bandgap-narrowing-induced band offset between the channel and the contact layer. This represents orders-of-magnitude of lower contact resistivity than that obtained in similar MOCVD-grown structures. A detailed, layer-by-layer analysis of the reverse graded contact and TCAD simulation of the bandgap narrowing effect highlighted that the reverse graded contact layer itself is extremely conductive, and interfacial resistance due to bandgap-narrowing-induced barrier between contact and channel dominates the contact resistance.
Metabolomic profile of severe COVID-19 and a signature predictive of progression towards severe disease status: a prospective cohort study (METCOVID)
Al2O3/<i>in situ</i> GaON gate dielectrics incorporated GaN MIS-HEMTs with stable VTH and significantly reduced interface state density
This work reports a metal–insulator–semiconductor High-Electron-Mobility-Transistor (HEMT) with Al2O3/in situ GaON bi-layer gate dielectric for improved threshold voltage (VTH) stability and reduced interface state density. With a combination of in situ GaON and large bandgap Al2O3 on top of the recessed gate region, normally-off HEMT was achieved with high On/Off current (ION/IOFF) ratio of 109, low VTH hysteresis less than 60 mV, and low-interface trap density (Dit) in the range of 4 × 1011–2 × 1012 cm−2·eV−1. Thanks to the sharp GaN/oxide interface with narrow distribution of lattice constant, uniform strain distribution and significantly reduced trap density were obtained. More importantly, our proposed bi-layer gate dielectric is perfectly compatible with the conventionally utilized gate recessing technique compared to the conventionally utilized in situ SiNx, demonstrating itself as a promising candidate in GaN power devices.
Impact of the eastern Tibetan Plateau on the ecological sensitivity of the West Qinling Mountains
High-power femtosecond mid-IR source with tunable center frequency and chirp
We present an experimental implementation of a chirped mid-infrared (mid-IR) high-power laser source with variable center frequency between 4 and 30 THz and continuously tunable frequency sweep of up to 20% within one pulse, with a pulse duration of 2 ps. The peak electric field obtained at 4 THz is 1.5 MV/cm. We generate the mid-IR light using a difference-frequency generation process with two phase-locked, chirped IR pulses. The obtained mid-IR electric field waveform is characterized using electro-optic sampling. We compare our experimental results with the predictions of numerical simulations. The results indicate the potential for efficient driving of vibrational modes into a strongly anharmonic regime, in cases where using Fourier-transform-limited pulses to achieve similar vibrational amplitudes would lead to dielectric breakdown.
Anion gap predicting 90-Day mortality and guiding furosemide use in ARDS
Exploring the potential of 2D PtTe2-based memristors for neuromorphic computing
Neuromimetic devices have emerged as transformative technologies with the potential to redefine traditional computing paradigms and enable advanced artificial neural systems. Among various innovative materials, two-dimensional (2D) materials have garnered attention as frontrunners for next-generation device fabrication. In this work, we report the fabrication and comprehensive characterization of a memristor based on 2D PtTe2. The device demonstrates exceptional performance metrics, including a high OFF/ON ratio, low switching voltage, and long data retention time. Leveraging density functional theory calculations, we unravel the underlying conduction mechanism, revealing the pivotal role of Ag conductive filaments in resistive switching behavior. Furthermore, the neuromorphic capabilities of the PtTe2 memristor were evaluated through its emulation of key brain-inspired synaptic functionalities, such as long-term depression/enhancement, paired-pulse facilitation, and spike-timing-dependent plasticity. By modulating its electrical conductance, we implemented a convolutional neural network for MNIST handwritten digit recognition, achieving a remarkable accuracy of 97.49%. To further illustrate its adaptive learning capabilities, we demonstrated a Pavlov's dog experiment using the device. This study establishes 2D PtTe2 as a promising material for neuromorphic applications and represents a critical step forward in bridging the gap between advanced materials and next-generation computing architectures. These findings lay a robust foundation for future exploration of PtTe2 in the field of neuromorphic engineering.
Lightweight mechanical equipment fault diagnosis framework based on GCGAN-MDSCNN-ICA model
Inductive effect of charge transfer in ferroelectrics and plasmonic Ag heterojunctions for enhanced CO2 photoreduction
Converting carbon dioxide into fuel and chemicals by utilizing solar energy represents a cutting-edge approach to carbon recovery and energy renewal. The transfer behavior of photogenerated electrons and built-in electric field of photocatalysts greatly affect the efficiency of the photoreduction reaction. Herein, the heterostructures composed of bismuth sodium titanate (BNT) ferroelectrics and silver nanoparticles (Ag NPs) are constructed to promote the photocatalytic CO2 performance. The large spontaneous polarization of BNT optimizes the transfer dynamics of photoinduced electrons and holes and causes energy band bending with strong intrinsic electric field. With the aid of Ag NPs, the BNT@xAg heterojunctions exhibit intensified light absorption due to the phenomenon of localized surface plasmon resonance (LSPR), which extends the visible light absorption spectrum and strengthens charge transfer. The modified catalysts demonstrate improved charge separation capacity and notably prolonged electron lifetime up to 40.95 ns. The synergistic effect of LSPR and intrinsic polarization significantly boosts the photocatalytic efficiency together with ultrahigh CO product selectivity, which is outstanding among the ferroelectric and other representative photocatalysts. This study elucidates the photocatalytic enhancement mechanism of plasmonic Ag decorated BNT and offers an alternative route for the design of efficient catalysts.
Standalone ultrasound-based highly visualized volumetric spine imaging for surgical navigation
Peculiar spin Hall magnetoresistance in polycrystalline WTe2/Ni80Fe20 heterostructures
Charge–spin interconversion is a key issue in spintronics. It gives rise to a series of new phenomena, such as spin Hall magnetoresistance (SMR). In the present work, we report the peculiar SMR behaviors in heterostructures composed of polycrystalline WTe2 nanoplate and Ni80Fe20(Py) film. We observe a negative SMR, which is contrary to the positive SMR usually measured in heavy metal/ferromagnet bilayers. We further observe a transition from negative to positive SMR with increasing thickness of the WTe2 layer, as well as SMR sign reversal with increasing temperature in heterostructures with thicker WTe2. The peculiar SMR behaviors in polycrystalline WTe2/Py heterostructures are attributed to the interface-induced spin current and its competition with the spin Hall-induced spin current. The findings in this work offer a fundamental input for the future exploitation of heterostructures based on two-dimensional transition metal dichalcogenides.
Adult ADHD predicts intimate partner violence perpetration and victimization irrespective of gender and age
Abstract Understanding the determinants of intimate partner violence (IPV) from perpetrator and victim perspectives has become a major objective of behavioral science. Empirical evidence suggests that adults at risk for Attention-Deficit/Hyperactivity Disorder (ADHD), compared to the general population, tend to have more conflictual partnerships, and the presence of ADHD increases the risk of aggressive behavior. Possible influences of gender have not been sufficiently investigated yet. Using data from an anonymous online survey, this study examined the relationship between ADHD and IPV in 316 male and female individuals with (n = 131) and without (n = 185) ADHD. Multiple linear regression analyses showed that adults at risk for ADHD had more frequently become both victims and perpetrators of IPV compared to the healthy control group. ADHD achieved significant incremental variance over gender and age. Thus, the presence of ADHD seems to be an important risk factor for IPV irrespective of gender and age. Accordingly, research and treatment approaches focusing on ADHD must not neglect the risk of IPV among patients but should offer specific psychological support.
Evolution of point defects in Bi2Te3-based materials and performance of thermoelectric modules subjected to <i> <b>γ</b> </i>-irradiation
Bismuth telluride (Bi2Te3), renowned for its exceptional thermoelectric (TE) properties near room temperature, is used in extreme environments such as deep space exploration, leading to extensive attention on the radiation-induced defects to Bi2Te3. However, the evolution of point defects during gamma (γ)-irradiation is still poorly understood. In this paper, we report the evolution of point defects in Bi2Te3 materials subjected to varying doses of γ-irradiation and their impact on TE performance. Precisely, Bi0.5Sb1.5Te3 and Bi2Te2.7Se0.3 materials, along with TE modules, were fabricated and subsequently subjected to γ-irradiation. The segregation of Te elements in Bi2Te3 was observed under low irradiation dose, attributing to the formation of interstitial atom–vacancy pair of Te induced by γ-irradiation. In addition, the formation of point defects has a positive relation with the irradiation dose. The positron annihilation (PA) measurements revealed that the number of vacancies in Bi2Te3 diminished with increasing irradiation dose. The accompanying changes in carrier concentration (nH) and mobility (μH) suggest that γ-ray drives Bi atoms to occupy Te vacancies, forming antisite defects. The TE performance of Bi2Te3 was subsequently evaluated, and the findings revealed a strong correlation with the evolution of point defects. This study provides insights into the damage mechanisms and property alterations of Bi2Te3 materials under γ-irradiation.
Identifying modifiable factors that influence walking in patients undergoing surgery for neurogenic claudication: a prospective longitudinal study
The effect of transcranial random noise stimulation (tRNS) over bilateral parietal cortex in visual cross-modal conflicts
Gene network analysis identifies dysregulated pathways in an autism spectrum disorder caused by mutations in Transcription Factor 4
Niacinamide and its impact on stratum corneum hydration and structure
Abstract Niacinamide (NIA) is widely used in skincare for its favorable safety profile, anti-aging effects, and proven clinical efficacy in treating various skin conditions. However, its direct impact on the hydration and molecular organization of the stratum corneum (SC), the primary skin barrier, remains unclear. This study examines how NIA influences the SC’s lipid matrix organization, soft keratin structure, and water sorption behavior across varying relative humidity (RH) levels. Using small- and wide-angle X-ray diffraction and dynamic vapor sorption measurements, we compared NIA-treated SC samples to untreated controls under different RHs. The main findings show that while NIA is non-hygroscopic, it enhances water uptake of the SC at high humidity (95% RH). At low humidity (60% RH), NIA swells the keratin monomer spacing, although the SC water content remains low, suggesting a plasticizing effect that could increase SC flexibility in dry conditions. NIA also modifies the diffraction intensities from the lipid matrix differently at 60% and 95% RH, implying that it interacts with the SC lipid matrix and influences the water distribution within the SC lipid and protein domains. These effects appear independent of the investigated dose regime, indicating a specific concentration threshold. Overall, NIA shows distinct interaction with keratin, swelling the spacing between keratin monomers in dry conditions, without acting as a traditional keratolytic agent.