Search Results (20,181)

Surface glint significantly reduces the measurement accuracy of remote sensing reflectance of water, R_rs, making it difficult to effectively use field measurements for studying water optical properties, accurately retrieving water quality parameters, and validating satellite remote sensing products. To accurately assess the effectiveness of various glint removal methods and enhance the accuracy of water reflectance measurements, a portable multiprobe high-resolution System (PMHRS) is designed. The system is composed of a spectrometer, fiber bundles, an irradiance probe, and three radiance probes. The reliability and measurement accuracy of the PMHRS are ensured through rigorous laboratory radiometric calibration and temperature correction. The comprehensive uncertainty of laboratory calibration ranges from 1.29% to 1.43% for irradiance calibration and from 1.47% to 1.59% for radiance calibration. Field measurement results show a strong correlation with both synchronous ASD data, and Sen2Cor-atmospherically corrected Sentinel-2B data (R² = 0.949, RMSE = 0.013; R² = 0.926, RMSE = 0.0105). The water-leaving radiance measurements obtained under different solar elevation angles using three methods (M99 method, polarization method, and SBA) demonstrate that the improved narrow field-of-view polarization probe effectively removes surface glint across various solar elevation angles (with overall better performance than the traditional M99 method). At a solar elevation angle of 69.7°, the MAPD and MAD between the measurements of this method and those of the SBA are 5.8% and 1.4 × 10⁻⁴, respectively. The results demonstrate that the PMHRS system outperforms traditional methods in sun glint removal, significantly enhancing the accuracy of water remote sensing reflectance measurements and improving the validation quality of satellite data. This work provides a crucial technical foundation for the development of high-resolution continuous observation platforms in complex aquatic environments. It holds significant implications for improving the accuracy of field-based water remote sensing reflectance measurements and for enhancing the quality of water ecological monitoring data and satellite validation data. Full article

In the attempt to induce spin-polarized states in graphene (Gr), rare-earth deposition on Gr/Co(0001) has been demonstrated to be a successful strategy: the coupling of graphene with the cobalt substrate provides spin-polarized conical-shaped states (minicone) and the rare-earth deposition brings these states at the Fermi level. In this manuscript, we theoretically explore the feasibility of an analogue approach applied on Gr/Ni(111) doped with rare-earth ions by means of density functional theory calculations. Even if not well mentioned in the literature, this system owns a minicone, similar to the cobalt case. By testing different rare-earth ions, not only do we suggest which one can provide the required doping but we also explain the effect behind this proper charge transfer. Full article

The ²⁰³Pb and ²¹²Pb lead radioisotopes are attracting growing interest as they can aid in the development of personalized, targeted radionuclide treatment for advanced and currently untreatable cancers. In the present study, the bonding interactions of Pb²⁺ with twelve macrocyclic ligands, having an octa and nona coordination, were assessed using Density Functional Theory (DFT) calculations. The molecular structures in an aqueous solution were computed utilizing the polarized continuum model. The preference for the twisted square antiprismatic (TSAP) structure was confirmed for ten out of the eleven cyclen-based complexes. The characteristics of the bonding were assessed using a Natural Energy Decomposition Analysis (NEDA). The analysis revealed a strong electrostatic character of the bonding in the complexes, with minor variations in electrical terms. The charge transfer (CT) had a comparable energetic contribution only in the case of neutral ligands, while in general, it showed notable variations regarding the various donor groups. Our data confirmed the general superiority of the carboxylate O and aromatic N donors. The combination of the selected efficient pendant arms pointed out the superiority of the acetate pendant arms and the lack of significant cooperation between the different pendant arms in the probed ligands. Altogether, the combination led only to a marginal enhancement in the total CTs in the complexes. Full article

Polar stratospheric clouds (PSCs) play a crucial role in ozone depletion in the polar stratosphere. In this study, the space-based PSCs record from CALISPO and an offline three-dimensional chemical transport model (SLIMCAT) are used to analyze the PSCs in the Arctic and the Antarctic for the period 2006−2021. Observations indicate that the seasonal evolution of the Antarctic PSC area is similar from year to year. In contrast, the Arctic PSCs show large differences in seasonal variations of coverage and duration in different years. The SLIMCAT simulations effectively capture the seasonal and interannual variations of PSCs. However, the simulated PSC areas are larger than CALIPSO observations, which can be attributed to the relatively high instrumental detection threshold of CALIPSO. SLIMCAT can capture the zonal asymmetry of PSCs in both the Antarctic and Arctic, and it can reproduce a more accurate spatial distribution of PSCs when the PSC coverage area is larger. In addition, accurate simulation of HNO₃ is important for PSC simulation. Because the simulation of denitrification processes is poor in SLIMCAT, which uses the thermodynamic equilibrium PSC scheme, the PSCs modeled by SLIMCAT are located at higher altitudes compared to the observation in the Antarctic, where the denitrification processes are strong. In contrast, for ice PSCs of which HNO₃ is not required in calculations and the Arctic where denitrification is weak, the simulated PSC at different altitudes closely matches the observations. Full article

The Internet’s development has prompted social media to become an essential channel for disseminating disaster-related information. Increasing the accuracy of emotional polarity recognition in tweets is conducive to the government or rescue organizations understanding the public’s demands and responding appropriately. Existing sentiment analysis models have some limitations of applicability. Therefore, this research proposes an IDBO-CNN-BiLSTM model combining the swarm intelligence optimization algorithm and deep learning methods. First, the Dung Beetle Optimization (DBO) algorithm is improved by adopting the Latin hypercube sampling, integrating the Osprey Optimization Algorithm (OOA), and introducing an adaptive Gaussian–Cauchy mixture mutation disturbance. The improved DBO (IDBO) algorithm is then utilized to optimize the Convolutional Neural Network—Bidirectional Long Short-Term Memory (CNN-BiLSTM) model’s hyperparameters. Finally, the IDBO-CNN-BiLSTM model is constructed to classify the emotional tendencies of tweets associated with the Hurricane Harvey event. The empirical analysis indicates that the proposed model achieves an accuracy of 0.8033, outperforming other single and hybrid models. In contrast with the GWO, WOA, and DBO algorithms, the accuracy is enhanced by 2.89%, 2.82%, and 2.72%, respectively. This study proves that the IDBO-CNN-BiLSTM model can be applied to assist emergency decision-making in natural disasters. Full article

Background/Objectives: The relationship between sarcoidosis and the occurrence of neoplasia deserves to be investigated, but this relation has been observed in different and heterogeneous populations, leading to conflicting data. To clarify the causal relationship between these two diseases, different risk factors (e.g., smoking), concurrent comorbidities, corticosteroid therapy, and metastasis development—as an expression of cancer aggressiveness—were investigated. Methods: In a retrospective study on 287 sarcoidosis outpatients at the Pneumological Department of the Gemelli Foundation (Rome, Italy) between 2000 and 2024, the diagnosis of cancer was recorded in 36 subjects (12.5%). Results: The reciprocal timeline of the diseases showed three different scenarios: (1) cancer preceding sarcoidosis or sarcoid-like reactions (63.8%); (2) cancer arising after sarcoidosis diagnosis (8.3%); and (3) sarcoidosis accompanying the onset of malignancy (27.8%). Only two subjects with sarcoidosis and cancer showed metastasis, and one of them was affected by lymphoma. Conclusions: These data suggest that granulomatous inflammation due to sarcoidosis may assume an ambivalent role as a “double-edged sword”, according to the M1/M2 macrophage polarization model: it represents a protective shield, preventing the formation of metastasis through the induction of immune surveillance against cancer while, on the other hand, it can be a risk factor for carcinogenesis due to the persistence of a chronic active inflammatory status. Low-dose steroid treatment was administered in only 31.6% of the cancer–sarcoidosis subjects for less than six months to control inflammation activity, with no promotive effect on carcinogenesis observed. Full article

In this work, heat treatment of three different temperatures (600 °C, 800 °C, and 1000 °C) was applied to as-cast Al_0.75CoCr_1.25FeNi high-entropy alloys (HEAs) to investigate the influence of heat treatment on their corrosion properties. Open circuit potential (OCP) and cyclic polarization tests reveal that the 1000 °C heat-treated HEA possesses excellent corrosion resistance, as indicated by the low corrosion tendency and corrosion current density. Electrochemical impedance spectroscopy (EIS) and potentiostatic polarization analyses imply the presence of a superior passive film on the 1000 °C heat-treated HEA. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the passive film formed on the 1000 °C heat-treated HEA during potentiostatic polarization tests is most corrosion-resistant since it possesses the highest ratio of Al₂O₃/Al(OH)₃ and Cr₂O₃/Cr(OH)₃. Full article

This paper presents an extensive performance analysis of open-ended waveguide elements for direct radiating arrays with a high scan angle (±50° /60°). The evaluated designs are based on square and hexagonal apertures loaded with ridges. Both square and triangular lattices are considered in the framework of Ka-band downlink design requirements for future LEO mega-constellations. The parameter space defined by the monomodal condition has been explored to find an optimum value for each structure. The analyses carried out with both infinite and finite full-wave models in terms of active reflection coefficient, scan loss and cross-polar discrimination are in good agreement. Full article

The lateral root (LR) is an essential component of the plant root system, performing important functions for nutrient and water uptake in plants and playing a pivotal role in cereal crop productivity. Nitrate (NO₃⁻) is an essential nutrient for plants. In this study, wheat plants were grown in 1/2 strength Hoagland’s solution containing 5 mM NO₃⁻ (check; CK), 0.1 mM NO₃⁻ (low NO₃⁻; LN), or 0.1 mM NO₃⁻ plus 60 mg/L 2,3,5-triiodobenzoic acid (TIBA) (LNT). The results showed that LN increased the LR number significantly at 48 h after treatment compared with CK, while not increasing the root biomass, and LNT significantly decreased the LR number and root biomass. The transcriptomic analysis showed that LN induced the expression of genes related to root IAA synthesis and transport and cell wall remodeling, and it was suppressed in the LNT conditions. A physiological assay revealed that the LN conditions increased the activity of IAA biosynthesis-related enzymes, the concentrations of tryptophan and IAA, and the activity of cell wall remodeling enzymes in the roots, whereas the content of polysaccharides in the LRP cell wall was significantly decreased compared with the control. Fourier-transform infrared spectroscopy and atomic microscopy revealed that the content of cell wall polysaccharides decreased and the cell wall elasticity of LR primordia (LRP) increased under the LN conditions. The effects of LN on IAA synthesis and polar transport, cell wall remodeling, and LR development were abolished when TIBA was applied. Our findings indicate that NO₃⁻ starvation may improve auxin homeostasis and the biological properties of the LRP cell wall and thus promote LR initiation, while TIBA addition dampens the effects of LN on auxin signaling, gene expression, physiological processes, and the root architecture. Full article

Divalent metal cations are of vital importance in biochemistry and materials science, and their structural and thermodynamic properties in aqueous solution have often been used as targets for the development of ion models. This study presented a strategy for designing nonbonded point charge models of divalent metal cations (Mg²⁺ and Ca²⁺) and Cl⁻ by targeting quantum mechanics (QM)-based ion–water dimer interactions. The designed models offered an accurate representation of ion–water interactions in the gas phase and showed reasonable performance for non-targeted properties in aqueous solutions, such as the ion–water oxygen distance (IOD), coordination number (CN), and density and viscosity of MgCl₂ and CaCl₂ solutions at low concentrations. Our metal cation models yielded considerable overestimates of the hydration free energies (HFEs) of the ions, whereas the Cl⁻ model displayed good performance. Together with the overestimated density and viscosity of the salt solutions, these results indicated the necessity of re-optimizing ion–ion interactions and/or including polarization effects in the design of ion models. The designed Mg²⁺ model was capable of maintaining the crystal metal-binding networks during MD simulation of a metalloprotein, indicating great potential for biomolecular simulations. This work highlighted the potential of QM-based ion models to advance the study of metal ion interactions in biological and material systems. Full article

The increased exploitation of ores leads to the generation of mining waste, which has a negative impact on the environment and human health. For this reason, it is necessary to take care of it in an adequate way by applying some of the possible treatments. In addition to protecting the environment by applying appropriate treatment, there is also the possibility of making a profit by valorizing useful elements from mining waste. In order to choose the most adequate treatment, it is necessary to perform the characterization of mining waste. This paper contains a detailed characterization of the flotation tailings deposited at the Old Flotation Tailings in eastern Serbia, originating from copper ore processing. Characterization includes physico-chemical analysis, polarizing microscope analysis, X-ray Diffraction analysis (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) analysis analysis. The obtained results indicate that the investigated flotation tailings can be used as a secondary raw material for metal recovery, in this case primarily copper (whose content is about 0.24%), gold (with a content of about 0.43 ppm) and silver (with a content of about 1.7 ppm). Considering that the content of valuable elements is quite low, it is suggested to apply hydrometallurgical treatment for their recovery. Full article

In this study, a novel algorithm to retrieve the current speed along the range direction under extreme sea states is developed from C-band synthetic aperture radar imagery. To this aim, a Sentinel-1 (S-1) dual-polarized synthetic aperture radar (SAR) dataset consisting of 2300 images is collected during 200 tropical cyclones (TCs). The dataset is complemented with collocated wave simulations from the Wavewatch-III (WW3) model and reanalysis currents from the HYbrid Coordinate Ocean Model (HYCOM). The corresponding TC winds are officially released by IFRMER, while the Stokes drift following the wave propagation direction is estimated from the waves simulated by WW3. In this study, first the dependence of wind, Stokes drift, and range current on the Doppler centroid anomaly is investigated, and then the extreme gradient boosting (XGBoost) machine learning model is trained on 87% of the S-1 dataset for range current retrieval purposes. The rest of the dataset is used for testing the retrieval algorithm, showing a root mean square error (RMSE) and a correlation coefficient (r) of 0.11 m/s and 0.97, respectively, with the HYCOM outputs. A validation against measurements collected from two high-frequency (HF) phased-array radars is also performed, resulting in an RMSE and r of 0.12 m/s and 0.75, respectively. Those validation results are better than the 0.22 m/s RMSE and 0.28 r achieved by the empirical CDOP model. Hence, the experimental results confirm the soundness of the XGBoost, exhibiting a certain improvement over the empirical model. Full article

The COVID-19 pandemic has exposed individuals to various risks, including job loss, income reduction, deteriorating well-being, and severe health complications and death. In Brazil and the U.S., as well as in other countries, the initial response to the pandemic was marked by governmental underestimation, leading to inadequate public health measures to curb the spread of the virus. Although progressively mitigated, this approach played a crucial role in the impacts on local populations. Therefore, the principal aim of this paper is to evaluate the impact of COVID-19 and, indirectly, of the policies adopted by the U.S. and the Brazilian governments to prevent pandemic diffusion on income distribution. Utilizing available microdata and employing novel econometric methods (RIF-regression for inequality measures) this study shows that growth in COVID-19 prevalence significantly exacerbates economic disparities. Furthermore, the impact of COVID-19 on inequality has increased over time, suggesting that this negative impact has been intensifying. In the U.S., results indicate that working from home, the inability to work, and barriers to job-seeking significantly increase inequalities. Although further data are necessary to validate the hypothesis, this preliminary evidence suggests that the pandemic has significantly contributed to increased inequality in these two countries already characterized by increasing polarization and significant social disparities. Full article

Aimed at the problems of optical frequency combs, such as their large number of comb lines, their high flatness, and their lack of ease in generating, as well as the fact that the channelization efficiency of the scheme based on optical frequency combs is low, we proposed a microwave photonic channelization receiver based on signal polarization multiplexing. Using two-line local optical frequency combs with different frequencies to demodulate the RF signal in the orthogonal polarization state, 16 sub-channels with a bandwidth of 1 GHz can be received simultaneously. The experimental results show that the image rejection ratio can reach 28 dB, and the third-order spurious-free dynamic range of the system can reach 96.8 dB·Hz^2∕3. This scheme has the advantages of a large number of sub-channels and a high channelization efficiency; it has great application potential in broadband wireless communication, radar, and electronic warfare systems. Full article

Complementary polarized spin-transfer torque magnetic random-access memory (CPSTT-MRAM) has been proposed to address the sensing reliability issues caused by the single-ended sensing of STT-MRAM. However, it results in a three-fold increase in the free layer (FL) area compared to STT-MRAM, leading to a higher write current. Moreover, the read and write current paths in this memory are the same, thus preventing the optimization of each operation. To address these, in this study, we proposed a complementary polarized spin-orbit torque MRAM (CPSOT-MRAM), which tackles these issues through the SOT mechanism. This CPSOT-MRAM retains the advantages of CPSTT-MRAM while significantly alleviating the high write current requirement issue. Furthermore, the separation of the read and write current paths enables the optimization of each operation. Compared to CPSTT-MRAM, the proposed CPSOT-MRAM achieves a 4.0× and 2.8× improvement in write and read power, respectively, and a 20% reduction in layout area. Full article