Search Results (3,011)

Complex operating conditions, such as low temperature, can affect the degradation and safety stability of lithium-ion batteries (LIBs). This paper conducts research on the aging evolution and safety characteristics of LIBs under low-temperature conditions (−20 °C), to reveal the change laws of battery degradation and the trends of thermal parameters of aging LIBs. Cycling and charging/discharging experiments under low temperatures were conducted to collect realistic battery data. Various factors such as temperature, cycle number, charging/discharging rate, and depth of discharge/charge (DOD/DOC) are taken into consideration to test the battery cycling and thermal performance. With collected experimental results, basic electrical states of LIBs such as open-circuit voltage (OCV), internal resistance, and capacity are presented. Then, the capacity loss and internal resistance growth are also described and analyzed under various charge/discharge rates and DODs/DOCs. The experimental results show that low temperatures cause an almost 30% increase in polarization resistance, with nonlinear changes in total internal resistance. Moreover, the battery capacity and internal resistance also have extreme points with different charge/discharge rates under −20 °C, which may demonstrate that the charge/discharge rates of LIBs can be optimized under low temperature. Thermal runaway (TR) experiments were also conducted, and the self-heating rate and other indices are presented to show that an aging battery under low temperature still holds large energy to develop TR. The aging trends of LIBs under low temperatures are summarized, and battery safety is clarified to provide a reference for battery lifetime and safety management under low-temperature conditions. Full article

Global navigation satellite system (GNSS) differential code bias (DCB) and topside ionosphere vertical electron content (VEC) can be estimated using onboard data from low-earth-orbit (LEO) satellites. These satellites provide the potential to make up for the lack of ground-based stations in the oceanic and polar regions and establish a high-precision global ionosphere model. In order to study the influences of different LEO-topside VEC processing methods on estimates, we creatively analyzed and compared the results and accuracy of the DCBs and LEO-topside VEC estimates using two topside VEC solutions—the SH-topside VEC (spherical harmonic-topside vertical electron content) and EP-topside VEC (epoch parameter-topside vertical electron content) methods. Some conclusions are drawn as follows. (1) Using GRACE-A data (400 km in 2016), the monthly stabilities (STDs) of GPS satellite DCBs and LEO receiver DCBs using the EP-topside VEC method are better than those using the SH-topside VEC method. For JASON-2 data (1350 km), the STD results of GPS DCBs using the SH-topside VEC method are slightly superior to those using the EP-topside VEC method, and LEO DCBs using the two methods have similar STD results. However, the root mean square (RMS) results for GPS DCBs using the SH-topside VEC model relative to the Center for Orbit Determination in Europe (CODE) products are slightly superior to those using the EP-topside VEC method. (2) The peak ranges of the actual GRACE-A-topside VEC results using the SH-topside VEC and EP-topside VEC methods are within 42 and 35 TECU, respectively, while the peak ranges of the JASON-2-topside VEC results are both within 6 TECU. Additionally, only the SH-topside VEC model results are displayed due to the EP-topside VEC method not modeling VEC. Due to the difference in orbital altitude, the results and distributions of the GRACE-topside VECs differ from those of the JASON-topside VECs, with the former being more consistent with the ground-based results, indicating that there may be different height structures in the LEO-topside VECs. In addition, we applied the IRI-GIM (International Reference Ionosphere model–Global Ionosphere Map) method to compare the LEO-based topside VEC results, which indicate that the accuracy of GRACE-A-topside VEC using the EP-topside VEC method is better than that using the SH-topside VEC method, whereas for JASON-2, the two methods have similar accuracy. Meanwhile, we note that the temporal and spatial resolutions of the SH-topside VEC method are higher than those of the EP-topside VEC method, and the former has a wide range of usability and predictive characteristics. The latter seems to correspond to the single-epoch VEC mean of the former to some extent. Full article

The development of tunable optical filters in the mid-infrared (MIR) region is crucial for a variety of applications, including environmental monitoring, medical diagnostics, and communication systems. This paper presents the design, fabrication, and characterization of a novel Twisted Liquid Crystal (TLC) electro-tunable optical cavity filter for the MIR region 3–5 μm. The filter is based on a Fabry–Perot interferometer configuration, which includes a polarization-independent TLC to achieve electrical control over the filter’s transmission characteristics. Two distinct filters were fabricated, differing in their substrate materials: silicon and glass. The silicon-based filter demonstrated an impressive 80% transmission with a tuning range of ∼13.6 nm and ∼14.64 nm in two separate bands, achieved by varying the applied voltage from 0 to 20 V. In contrast, the glass substrate filter exhibited a slightly higher transmission of 82% with tuning ranges of ∼10.5 nm and ∼7.2 nm across the spectral band when the voltage was adjusted from 0 to 27 V. Experimental validation showed a strong alignment between the simulations and results, demonstrating the feasibility of integrating tunable liquid crystals into mid-infrared optical cavities. This advancement highlights their potential for applications that require precise and dynamic control of the mid-infrared spectrum. Full article

To address the limitation that single-index evaluation fails to fully reflect the development performance of reservoirs of different types and at various development stages, a multi-index comprehensive evaluation system featuring the workflow of “index screening–weight determination–model evaluation–strategy guidance” was established. Firstly, the grey correlation analysis method (with a correlation degree threshold set at 0.65) was employed to screen 12 key evaluation indicators, including reservoir physical properties (porosity, permeability) and development dynamics (recovery factor, water cut, well activation rate). Subsequently, the fuzzy analytic hierarchy process (FAHP, for subjective weighting, with the consistency ratio (CR) of expert judgments < 0.1) was coupled with the attribute measurement method (for objective weighting, with information entropy redundancy < 5%) to determine the indicator weights, thereby balancing the influences of subjective experience and objective data. Finally, two evaluation models, namely the fuzzy comprehensive decision-making method and the unascertained measurement method, were constructed to conduct evaluations on 308 reservoirs in the Liaohe Oilfield (covering five major categories: integral medium–high-permeability reservoirs, complex fault-block reservoirs, low-permeability reservoirs, special lithology reservoirs, and thermal recovery heavy oil reservoirs). The results indicate that there are 147 high-efficiency reservoirs categorized as Class I and Class II in total. Although these reservoirs account for 47.7% of the total number, they control 71% of the geological reserves (154,548 × 10⁴ t) and 78% of the annual oil production (738.2 × 10⁴ t) in the oilfield, with an average well activation rate of 65.4% and an average recovery factor of 28.9. Significant quantitative differences are observed in the development characteristics of different reservoir types: Integral medium–high-permeability reservoirs achieve an average recovery factor of 37.6% and an average well activation rate of 74.1% by virtue of their excellent physical properties (permeability mostly > 100 mD), with Block Jin 16 (recovery factor: 56.9%, well activation rate: 86.1%) serving as a typical example. Complex fault-block reservoirs exhibit optimal performance at the stage of “recovery degree > 70%, water cut ≥ 90%”, where 65.6% of the blocks are classified as Class I, and the recovery factor of blocks with a “good” rating (42.3%) is 1.8 times that of blocks with a “poor” rating (23.5%). For low-permeability reservoirs, blocks with a rating below medium grade account for 68% of the geological reserves (8403.2 × 10⁴ t), with an average well activation rate of 64.9%. Specifically, Block Le 208 (permeability < 10 mD) has an annual oil production of only 0.83 × 10⁴ t. Special lithology reservoirs show polarized development performance, as Block Shugu 1 (recovery factor: 32.0%) and Biantai Buried Hill (recovery factor: 20.4%) exhibit significantly different development effects due to variations in fracture–vug development. Among thermal recovery heavy oil reservoirs, ultra-heavy oil reservoirs (e.g., Block Du 84 Guantao, with a recovery factor of 63.1% and a well activation rate of 92%) are developed efficiently via steam flooding, while extra-heavy oil reservoirs (e.g., Block Leng 42, with a recovery factor of 19.6% and a well activation rate of 30%) are constrained by reservoir heterogeneity. This system refines the quantitative classification boundaries for four development levels of water-flooded reservoirs (e.g., for Class I reservoirs in the high water cut stage, the recovery factor is ≥35% and the water cut is ≥90%), as well as the evaluation criteria for different stages (steam huff and puff, steam flooding) of thermal recovery heavy oil reservoirs. It realizes the transition from traditional single-index qualitative evaluation to multi-index quantitative evaluation, and the consistency between the evaluation results and the on-site development adjustment plans reaches 88%, which provides a scientific basis for formulating development strategies for the Liaohe Oilfield and other similar oilfields. Full article

To suppress non-stationary main-lobe interference, we utilized the waveform information of the transmitted signal and proposed an interference suppression method based on a multi-polarized array without the need for calculating the target parameters. This method calculates the steering vector of the target through matched filtering. Additionally, for non-stationary interference whose statistical characteristics change over time, we extract high-energy frequency points from the time–frequency joint domain to obtain the time–frequency covariance matrix for subsequent beamforming. Simulation experiments demonstrate that this method leverages the signal polarization information sensed by the multi-polarized array, effectively suppressing non-stationary main-lobe interference in the polarization domain. This method does not require estimation of the target’s polarization parameters and is more suitable for real-world detection scenarios where the waveform is known. Full article

Bow-tie microwave diodes have proven to be effective sensors of electromagnetic radiation across a wide wavelength range, from centimeter-scale radio waves to micrometer-scale mid-infrared radiation. Their operation is based on electron heating by strong electric fields. However, the experimental data obtained so far remain inconclusive, and the exact nature of the voltage detected by bow-tie diodes is not yet fully understood. In this work, we extend the investigation of the electrical properties of bow-tie diodes based on modulation-doped semiconductor structures with a wide spacer. The analysis focuses on the influence of diode metal contact geometry, illumination conditions, and orientation relative to the crystallographic axes. To elucidate the origin of the voltage detected by bow-tie diodes, we compare theoretical predictions of their electrical parameters—including voltage sensitivity, electrical resistance, asymmetry of the I–V characteristic in weak electric fields, and the nonlinearity coefficient of the I–V characteristic in strong electric fields—with corresponding experimental results. The results of our investigations indicate that, for most diodes, the detected voltage originates from electron heating by the microwave electric field, as evidenced by the polarity of the detected voltage matching the thermoelectric emf of hot carriers. Full article

Effective carbon emission control at the provincial level is essential for advancing the high-quality development of the national economy under the “dual carbon” targets. Although Hubei Province is endowed with abundant natural resources and significant potential for sustainable growth, it still faces considerable challenges in industrial and energy restructuring. Therefore, improving carbon emission efficiency (CEE) is imperative. This study thoroughly analyzes the spatial and temporal characteristics of CEE in Hubei Province. Furthermore, the spatial Durbin model (SDM) and geographically and temporally weighted regression (GTWR) were applied to analyze the determinants of changes in CEE. The results indicate that significant disparities in CEE exist across Hubei Province, with the eastern region exhibiting the highest efficiency and the central region the lowest. The year 2016 represented a turning point, as Moran’s I increased from −0.0006 in 2016 to 0.5134 in 2017, indicating a shift in the spatial pattern of CEE from a weak and insignificant spatial autocorrelation to a strong positive spatial autocorrelation. In addition, the CEE in Hubei Province demonstrated a “siphon effect” and exhibited pronounced polarization. Based on these findings, region-specific policies are proposed. The eastern region should optimize its industrial structure and strengthen urban governance. The western region should leverage its clean energy advantage and enhance carbon sink capacity. The central region should advance low-carbon industrial transformation and coordinated governance to prevent core cities from transferring resources and pollution to surrounding areas. Full article

We present a comprehensive first-principles study of nanoribbons made from the α-borophene sheet. This study looks at how edge shape, ribbon width, and magnetic ordering affect their structural, electronic, and transport properties. Ribbons cut along armchair (ac) and zigzag (zz) directions with various edge designs—armchair (a), single (s), and double (d) chains—are all stable. The double chain “dd” edges have the highest binding energies and the lowest edge energies, which aligns with near-bulk coordination. Our analysis of electronic structure and ballistic transport shows strong metallic characteristics in almost all configurations. Only the narrowest “3-ad” ribbon shows a small energy gap that disappears as the width increases. Zigzag ribbons (“zz”) display edge magnetism that depends on width, changing from non-magnetic to antiferromagnetic and finally to ferromagnetic states. Their spin-resolved transmission demonstrates clear spin filtering with polarization exceeding about 40%. Edge passivation affects these properties: hydrogen and fluorine reduce the “zz” edge magnetic moments and spin transport, while oxygen maintains finite magnetism. Near the Fermi level, many ribbons allow for multiple conducting channels. This feature supports low-resistance charge flow even for widths below 10 nm, while higher-energy transmission shows greater dependence on width. These findings position α-borophene nanoribbons as promising one-dimensional components for nanoelectronic connections and spintronic devices, combining high stability, adjustable edge magnetism, and strong metallic conduction. Full article

The pollen morphological characteristics of 16 pummelos and 4 other citrus germplasms from Vietnam, Thailand, and China were observed using scanning electron microscopy (SEM). Observations included equatorial view, polar view, and exine ornamentation. The results showed that the pollen of all tested materials was monads, prolate, or subprolate. The average polar axis length of the pollen ranged from 29.121 to 37.043 µm, and that of the equatorial axis ranged from 19.861 to 25.911 µm. A t-test revealed that the polar axis of pollen from Chinese pummelo germplasms was significantly longer than that of varieties from Southeast Asia, indicating certain geographical differentiation. The apertures were all colporate type, predominantly with four to five colpi (75% of grains); only four colpi were observed in the remainder (25%). The pollen exine ornamentation of pummelo germplasms was perforated, whereas that of other citrus types was reticulate. Pummelos exhibited a smaller pori diameter (0.264–0.673 µm) and wider distance between pori (0.581–1.118 µm), while other citrus species had larger lumina (1.253–1.684 µm) and narrower muri (0.443–0.664 µm). Principal component analysis (PCA) and cluster analysis were performed based on pollen traits, and two principal component factors were extracted. The pummelo germplasms were divided into two subgroups: sweet pummelo and red pummelo, which demonstrated a correlation among their pollen morphology, flesh color, and flesh flavor. The phenotypic diversity of pollen among different pummelo germplasms may provide a valuable auxiliary reference for the identification and systematic classification of pummelos. Full article

Background/Objectives: Naegleria fowleri is a free-living protozoan that causes primary amoebic meningoencephalitis, a rapidly progressing central nervous system infection with high mortality rates and limited treatment options. Targeting virulence-associated proteins is essential for effective drug development. Fowlerpain-1 (FWP1), a papain-like cysteine protease (CP) implicated in extracellular matrix degradation and host–cell cytotoxicity, has been investigated as a therapeutic target. This study aimed to evaluate the FWP1 pocket geometry and stefin binding using an integrated in silico structural biology approach. Methods: A computational pipeline was used, including AlphaFold2-Multimer modeling of FWP1–stefin complexes, 20-ns molecular dynamics simulations under NPT conditions for conformational sampling, and molecular mechanics Poisson–Boltzmann surface area free energy calculations. Three natural CP inhibitors (stefins) were investigated. Structural stability was assessed using root mean square deviations, and binding profiles were characterized using protein–protein interaction analysis. Results: Stable FWP1–stefin interaction interfaces were predicted, with human stefin A showing favorable binding free energy. Two conserved motifs (PG and QVVAG) were identified as critical mediators of active-site recognition. Druggability analysis revealed a concave pocket with both hydrophobic and polar characteristics, consistent with a high-affinity ligand-binding site. Conclusions: This computational study supports a structural hypothesis for selective FWP1 inhibition and identifies stefins as promising scaffolds for developing structure-guided protease-targeted therapeutics against N. fowleri. Full article

The Yellow River Delta (YRD) is a vital agricultural and ecologically fragile zone in China. Understanding the spatial pattern and evolutionary characteristics of Rural Settlements Area (RSA) in this region is crucial for both ecological protection and sustainable development. This study focuses on Dongying, a key YRD city, and compares four advanced deep learning models—U-Net, DeepLabv3+, TransUNet, and TransDeepLab—using fused Sentinel-1 radar and Landsat optical imagery to identify the optimal method for RSA mapping. Results show that TransUNet, integrating polarization and optical features, achieves the highest accuracy, with Precision, Recall, F1 score, and mIoU of 89.27%, 80.70%, 84.77%, and 85.39%, respectively. Accordingly, TransUNet was applied for the spatiotemporal extraction of RSA in 2002, 2008, 2015, 2019, and 2023. The results indicate that medium-sized settlements dominate, showing a “dense in the west/south, sparse in the east/north” pattern with clustered distribution. Settlement patches are generally regular but grow more complex over time while maintaining strong connectivity. In summary, the proposed method offers technical support for RSA identification in the YRD, and the extracted multi-temporal settlement data can serve as a valuable reference for optimizing settlement layout in the region. Full article

Hepatitis B Virus (HBV) continues to pose a significant global health challenge, with over 254 million chronic infections and current therapies being non-curative, necessitating lifelong treatment. The HBV ribonuclease H (RNase H) is essential during HBV reverse transcription by cleaving the viral pregenomic RNA after it has been copied into the (−) polarity DNA strand, enabling the viral polymerase to synthesize the (+) DNA strand. Although RNase H inhibition terminates viral replication and thus viral infectiveness, its targeting as an HBV treatment is unexploited. Its catalytic site contains four carboxylates that bind to two Mg²⁺ ions essential for RNA hydrolysis. As part of our ongoing research on RNase H inhibitors, we developed 23 novel N-hydroxypyridinedione (HPD) analogues. Specifically, 17 HPD imines, 4 HPD oximes, 1 2,6-diamino-4-((substituted)oxy)pyrimidine 1-oxide derivative, and 1 barbituric acid analogue were designed, synthesized, and tested for their anti-HBV activity. The HPD derivatives could be docked in the RNase H active site to coordinate the two Mg²⁺ ions and effectively inhibited viral replication in cellular assays. The 50% effective concentration (EC₅₀) values of these HPD compounds ranged from 0.5 to 73 μM, while the 50% cytotoxic concentration (CC₅₀) values ranged from 15 to 100 μM, resulting in selectivity indexes (SIs) up to 112. Furthermore, the novel HPD derivatives exhibited favourable pharmacokinetic-relevant characteristics, including high cellular permeability, good aqueous solubility, and overall drug-like properties. These findings indicate that HPD imines and oximes possess substantial antiviral potency and selectivity against HBV, underscoring the potential of the HPD scaffold as a promising framework for the development of next-generation anti-HBV agents. Full article

Polarization volume gratings (PVGs) have been recognized as a groundbreaking technology with the potential to revolutionize holographic waveguides and facilitate immersive experiences in augmented and virtual reality (AR/VR) applications. This study investigated the design, fabrication, and utilization of PVGs within the framework of holographic waveguides for immersive encounters. The essay begins by presenting a comprehensive overview of waveguide technologies. The display devices and optical combiners combine the actual and virtual worlds that the naked eye can see. This review categorizes current visual solutions for micro-optical combiners in augmented reality head-mounted displays (AR-HMDs). Subsequently, an investigation was carried out into the manufacturing process, physical principles, optical structures, performance characteristics, and other aspects. Furthermore, a review and assessment of their merits and drawbacks were conducted. Full article

This study examined the characteristics of essential oils and ethanolic extracts from nine pepper species’ fruits to determine their chemical compositions and assess their biological activity. Ethanolic extracts and essential oils were analyzed using HPLC, GC-MS, FTIR, and ¹H NMR spectroscopy. The total phenolic content, total flavonoid content, antioxidant activity (DPPH assay), and antibacterial efficacy against five bacterial strains were assessed. Additionally, multielement analysis was performed using the TXRF method. The results demonstrated that the yields and chemical compositions differed markedly according to the pepper origin and extraction method. Ethanolic extracts consistently demonstrated greater total phenolic content and total flavonoid content and enhanced antioxidant and antibacterial properties relative to their respective essential oils. The increased bioactivity is due to the presence of non-volatile, polar compounds, which are not effectively transferred via hydrodistillation. Piperine was solely detected in extracts from black, green, white, Bengali, and Voatsiperifery peppers. This study emphasizes the necessity of optimizing extraction techniques to enhance the bioactivity of pepper extracts, highlighting their potential as sources of natural antioxidants and antibacterial agents. Full article

A high-gain microstrip antenna array is proposed. The dual-frequency and dual-polarization characteristics of the array allow a satellite communication system to transmit and receive signals with a single antenna. To avoid high losses in microstrip feed lines for large apertures, the array is divided into subarrays, each fed by a low-loss separate feed network. The dual-frequency dual-polarization function is realized by utilizing two orthogonal modes of a corner-fed rectangular patch in a single-layer substrate. Moreover, to minimize losses in the separate feed network, semi-ridged coaxial lines and five four-way radial power dividers are employed. The power divider, composed of a cylindrical cavity and five SMA connectors, features very low insertion loss. Finally, to validate the design concept, a prototype of the proposed 32 × 32-element array operating at 12.5 GHz and 14.25 GHz is fabricated and measured. The measured results are in good agreement with the simulated ones. The −10 dB return loss frequency bands for the two operating frequencies are 12.04 GHz–12.69 GHz and 13.82 GHz–14.66 GHz, respectively. The measured gains at the two operating bands are 34.5 dBi and 35.2 dBi, respectively. Full article