Search Results (2,253)

We propose a dual-aperture, simultaneous-polarization super-resolution imaging system that combines a total internal reflection optical architecture with a digital micromirror device (DMD) for broadband, high-resolution imaging. The system captures multiple polarization states simultaneously with a single detector and offers a compact, lightweight design. Using reflective Wassermann–Wolf differential equations and Seidel aberration theory, we establish astigmatism-correction boundary conditions and apply iterative optimization to jointly correct spherical aberration, coma, astigmatism, and distortion. Because distortion critically affects super-resolution reconstruction by causing mirror–pixel misregistration, we further introduce a custom merit function to tightly constrain chief-ray positions for each sub-aperture and field point on intermediate and final image planes, effectively suppressing distortion. The final design achieves F/2.5, grid distortion below ±0.5%, and near-diffraction-limited performance in all polarization channels. Tolerance analysis of the four sub-apertures confirms that imaging requirements are satisfied, demonstrating robust high-resolution polarization imaging across multiple polarization states. Full article

Against the backdrop of rapid development in low-carbon building materials, geopolymer mortar has become a high-quality alternative to traditional cement-based materials due to its advantages of environmental friendliness, high strength, and excellent durability. However, its inherent brittleness and tendency to crack severely limit its widespread adoption and use in engineering. To mitigate the inherent brittleness of geopolymer mortar, this study developed a ternary binder system composed of metakaolin, slag, and fly ash. The effects of basalt fiber contents of 0%, 0.25%, 0.50%, 0.75%, 1.00%, and 1.25% by mass on the flowability, flexural strength, compressive strength, and deformation behavior of the geopolymer mortar were systematically investigated. The evolution of the displacement and strain fields during flexural and compressive loading was monitored in real time using two-dimensional digital image correlation (2D-DIC). The fiber-reinforcement mechanism was further examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results show that basalt fiber reduces mortar flowability, and the reduction becomes more pronounced with increasing fiber content. The flexural strength first increased and then decreased with increasing fiber content; at 0.50% fiber content, the 28-day flexural strength reached 12.6 MPa, which was 8.2% higher than that of the fiber-free control. The compressive strength increased only slightly at a low fiber content of 0.25% and then decreased when the fiber content exceeded 0.50%. The 2D-DIC results indicate that a moderate fiber content (0.50–0.75%) markedly increased the ultimate displacement, delayed crack propagation, and enhanced the post-cracking deformation capacity. Microstructural observations revealed that an appropriate fiber content promoted good interfacial bonding with the matrix and enabled fiber bridging and crack resistance. In contrast, excessive fiber addition caused agglomeration-induced micropores and microcracks, thereby degrading mechanical properties. Overall, the recommended basalt fiber content is 0.25–0.50%. These findings provide a theoretical and experimental basis for optimizing high-performance, low-carbon geopolymer mortar for engineering applications. Full article

Wavefront sensing (WFS) is fundamental to adaptive optics, astronomical observation, biological microscopy, and free-space optical communications. However, conventional approaches—including Shack–Hartmann sensors, shearing interferometers, and transport of intensity equation-based methods—are inherently limited by trade-offs among spatial sampling density, angular dynamic range, and device compactness and have rarely been extended to the mid-infrared range. Here, we propose an on-chip mid-infrared wavefront sensing scheme operating based on vectorial photocurrent manipulation and analyze the properties of the proposed device through finite-element simulations. The proposed device comprises a hexagonal array of antenna-integrated graphene pixels, each equipped with three contacts and a microlens. Based on the antenna-induced vectorial photocurrent manipulation, angle-dependent absorption is translated into photocurrent signals, potentially enabling unambiguous recovery of both the elevation and azimuth angles of the incident light over an effective angular dynamic range of ±28°. The hexagonal layout provides a high spatial sampling density of 11,547 mm⁻². Southwell algorithm-based wavefront reconstruction and numerical simulations yield faithful recovery of parabolic, conical, and quadrangular pyramidal wavefronts. In addition, simulation results indicate that this approach can enable high-fidelity reconstruction of both the phase and intensity distributions of an object based on angular-spectrum diffraction theory. Overall, this work theoretically demonstrates a new route toward high-density wavefront measurement and complex light field imaging in the mid-infrared range without a conventional imaging lens. Full article

The transits of Venus occur in couples every 105/122 years: the observed ones were in 1639; 1761–1769; 1874–1882; and 2004–2012. The next couple will occur in the years 2117 and 2125. We need all four contacts to determine the solar diameter accurately. The black-drop phenomenon blurs internal contacts, so we developed a parabolic analysis of the chords drawn by the disk of Venus on the solar limb. The extrapolation of the zeroes gives the contact timings. We tested this method with some high-quality images obtained in 2004 and 2012, and we applied it to the observations of 2012 in a visual band (Huairou Solar Observing Station, hazy weather) and H-alpha (Shen Zen Astronomical Observatory). To exclude a reduction in the measured diameter by the haze, we made two series of measures at the Clementine Gnomon (Rome) and at the PHYSIS telescope (Rome), under various sky transparencies and with diffraction-limited instruments. The haze and the low altitudes above the horizon reduced accuracy at all first contacts examined, without changing the solar diameter. Our measures obtained in China during the transit of 2012 yielded a photospheric radius R_⊙P = 959.33″ ± 0.06″, based on 76 + 75 diffraction-limited images; this is compatible with the chromospheric radius measured at the base of the spiculae, which is R_⊙C = 959.78″ ± 0.11″, relying on 7 + 5 diffraction-limited series of images. Full article

Al-Cu-Fe quasicrystalline coatings were deposited on AISI 321 stainless steel substrates by high-velocity oxy-fuel (HVOF) spraying at oxygen pressures of 3.0, 3.5, and 4.0 bar. The influence of oxygen pressure on the phase composition, microstructure, porosity, corrosion behavior, thermal stability, and microhardness of the coatings was investigated using X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM/EDS), ImageJ porosity analysis, electrochemical corrosion testing in 3.5 wt.% NaCl solution, simultaneous thermal analysis (TGA/DSC), and microhardness measurements. XRD analysis revealed the formation of quasicrystalline-related intermetallic phases together with Al, Fe₃Al₁₃, FeAl, Fe₃O₄, CuFe₂O₄, Cu₂O, and CuO phases. The coating deposited at 3.5 bar exhibited the lowest porosity (5.37%), the most homogeneous microstructure, and the largest residual coating thickness after corrosion testing. SEM and EDS analyses indicated that corrosion preferentially initiated at pores, splat boundaries, and phase interfaces, while the coating produced at 3.5 bar demonstrated the most stable surface condition after exposure to a 3.5 wt.% NaCl solution. Thermal analysis showed that all coatings remained stable up to 900 °C. Sample (a) exhibited the lowest mass loss and the highest thermal stability, whereas sample (b) demonstrated the most favorable combination of structural integrity, phase ordering, coating density, corrosion-related performance, and thermal stability. Microhardness values of the coatings ranged from 754 to 778 HV, significantly exceeding that of the AISI 321 substrate. The results demonstrate that oxygen pressure is a critical parameter controlling the microstructure and functional properties of HVOF-sprayed Al-Cu-Fe coatings, with 3.5 bar providing the most balanced set of properties. Full article

Ptychography implemented with coherent high-harmonic (HHG) sources enables high-resolution, high-fidelity imaging of nanostructures and biosystems. However, when driven by mid-infrared lasers to generate light at higher photon energies, HHG inherently produces a broadband quasi-continuum, which is less suited for coherent imaging compared with a single harmonic order. Consequently, experiments typically select a narrow bandwidth of ≈1%, leaving most of the HHG photons unused, increasing exposure times. In this work, we demonstrate broadband ptychography utilizing an extreme UV (EUV) continuum centered at 92 eV, with a bandwidth of up to 7.9 eV (a relative bandwidth of ~9%). By focusing the HHG beam to a sub-micrometer spot size to relax the temporal coherence constraints, and utilizing a multi-wavelength ptychographic reconstruction algorithm, we achieve a spatial resolution of 42 nm, which is near the diffraction limit of ~30 nm for our setup. To the best of our knowledge, this represents the broadest spectral bandwidth successfully employed to date for EUV ptychography, with the potential to increase the usable photon flux by up to an order of magnitude relative to previous approaches. In the future, broadband soft X-ray ptychography can be used to image hydrated samples around the carbon K-edge and magnetic textures at the L-edges of transition metals. Full article

In characterizing unconventional reservoirs, conventional Digital Rock Physics (DRP) has long been constrained by three fundamental bottlenecks: the trade-off between imaging resolution and field of view, challenges in reconstructing multiscale pore topology, and the prohibitive computational cost of direct numerical simulation (DNS) at the pore scale. The deep integration of artificial intelligence and rock physics has given rise to a new paradigm—Intelligent Digital Rock Physics (IDRP). This paper provides a systematic review of the evolutionary trajectory of IDRP, with a focus on how machine learning is reshaping the end-to-end workflow from imaging and segmentation to reconstruction and simulation. First, we survey image super-resolution and 3D pore structure generation techniques based on convolutional neural networks (CNNs), generative adversarial networks (GANs), and diffusion models, elucidating their mechanisms for surpassing optical diffraction limits and incorporating macroscopic petrophysical constraints. Second, we outline algorithmic strategies for fusing multi-source heterogeneous data (e.g., Micro-CT and SEM) and representing dual-porosity or multi-continuum systems. Third, we critically examine the application of machine learning surrogates in single- and multiphase flow prediction, highlighting how physics-informed machine learning (PIML) and reinforcement learning (RL)—by embedding governing equations such as Navier–Stokes or Muskat–Leverett into loss functions—achieve both computational acceleration and physical consistency. We further identify key limitations of current IDRP approaches, including insufficient validation of generated topological realism, narrow generalization across lithologies, inadequate representation of dynamic wettability, and limited model interpretability. Finally, we propose a forward-looking roadmap centered on multimodal foundation models for rocks, coupled with neural operators and uncertainty quantification frameworks, emphasizing the critical pathways for translating IDRP into engineering digital twins for unconventional hydrocarbon development, coalbed methane production enhancement, Enhanced Geothermal Systems, and geological CO₂ storage. This review offers a comprehensive reference for researchers at the intersection of geophysics, rock mechanics, and artificial intelligence. Full article

Accurate identification of pathogenic yeasts is essential for clinical diagnosis and effective antifungal therapy. However, current approaches predominantly rely on microscopy-based models, which require large-scale annotated datasets and exhibit limited generalization across morphologically similar species. In contrast, light-scattering (LS) imaging captures the diffraction patterns generated by internal cellular structures, providing volumetric biophysical cues that extend beyond surface morphology, yet its indirect representations pose major challenges for feature discrimination. Our objective is to develop fast and accurate methods to detect various species of yeasts. We propose FPA-YeastNet, which is a frequency-enhanced single-modality deep learning architecture that improves yeast classification in LS images by leveraging discriminative frequency-domain features. Building upon this enhanced modality, we further propose FGCA-YeastNet, a frequency-guided cross-attention network designed to integrate LS and microscopy information for complementary representation learning. The proposed multimodal model facilitates synergistic interactions between volumetric scattering structures and fine-grained cellular textures through adaptive fusion and bidirectional attention, leading to improved robustness and interpretability. Comprehensive classification experiments conducted on a multimodal yeast dataset demonstrate that FGCA-YeastNet effectively bridges the performance gap between LS and microscopy modalities, achieving significant improvements over both unimodal and multimodal baselines. The FPA-YeastNet yields an average accuracy improvement of 6.26% compared with LS-only models, and FGCA-YeastNet further provides mean gains of 19.97% and 7.67% over unimodal and multimodal baseline models, respectively. Experimental results demonstrate the diagnostic potential of light scattering and microscopic imaging and underscore the effectiveness of frequency-guided multimodal collaboration for reliable and interpretable yeast classification in clinical microbiology. Full article

The influence of double continuous cold rolling followed by annealing on the texture evolution and mechanical properties of a commercial low-carbon ferritic steel was investigated. Ultrathin sheets (final thickness 0.22 mm) were produced through a two-stage cold rolling process with intermediate and final annealing at 690 °C for 35 s, followed by light temper rolling at 100 °C for 20 s. Texture evolution was characterized using Electron Backscatter Diffraction (EBSD) with Orientation Imaging Microscopy (OIM), producing pole figures and orientation distribution functions (ODFs). Mechanical properties were evaluated through Vickers microhardness and ultimate tensile strength measurements obtained from three independent locations per sample. Quantitative ODF analysis (φ₂ = 45°) revealed that γ-fiber ({111}//ND) intensity increased after each cold reduction stage and decreased after annealing due to recrystallization. The α-fiber (110/RD) and cube components (001//RD) showed a slight increase after annealing. The final ultrathin sheet exhibited moderate γ-fiber intensity (≈3 M.R.D), low Vickers microhardness (100–150 HV), and tensile strength (400–450 MPa). These results demonstrate controlled evolution of texture and microstructure during double cold rolling and annealing, providing a basis for future studies on forming-related behavior without directly assessing formability. Full article

Foraminiferal shell crystals incorporate the chemical signals of their environment during growth. The recorded information is extracted from the crystals via proxies and can be used to reconstruct paleoenvironments, paleoclimates, and the change of the latter. However, the information that is obtained from the biocrystals is often biased, due to structural and chemical modification of the crystals resulting from dissolution, precipitation, recrystallization, and overall, the transformation of the biologically formed crystals into their inorganic analogs. Electron-backscatter diffraction (EBSD) measurements and analysis render a wide range of information regarding crystallographic-structural attributes of the crystals, such as crystal-microstructure, crystal-texture, the misorientation interrelation of adjacent crystals, crystal-twin-generation and many more. We demonstrate in this study that diagenetic overprint of foraminiferal shell Ca-carbonate crystals can be identified by structural-crystallographic characteristics obtained from EBSD measurements. We investigated modern/pristine and fossil Trilobatus sacculifer shells and observed an undisturbed shell surface for both. Despite the latter, we demonstrate here that with an increase in the degree of fossilization and diagenetic overprint, there is an increase in recrystallized calcite in the shells and a decrease in twinned calcite. Twinned calcite is the hallmark of pristine T. sacculifer shells. We show that, with increasing degrees of shell overprint, crystal-microstructure, and crystal-texture, the frequency of the 60°|<001> twin misorientation is modified and propose to use structural-crystallographic attributes determined with EBSD measurements for the identification of recrystallized/overprinted foraminiferal carbonate. We discuss that disclosing low degrees of overprint is of main importance, as minor structure changes of overprinted shells are easily overlooked with SEM imaging. Nonetheless, these are readily identified with EBSD-measurements. Full article

Nanofiber scaffolds play a crucial role in bioengineering by providing structural support for tissue and organoid growth. For composite nanofibers, optimizing their properties for specific applications often requires analyzing the spatial distribution of their chemical structure. This review focuses on the applications of Raman hyperspectral imaging to the mapping of the chemical composition of nanofibers. While the technique is diffraction-limited to the size of the scanning beam, it is possible to decipher the nanoscale features of these fibers by employing oversampling during scanning. Subsequently, these oversampled data can be analyzed by a singular-value decomposition (SVD) analysis and classical least-squares (CLS) decomposition. In many cases, this technique is essential for verifying the spatial distribution of different chemical components within multi-component nanofibers. Full article

In this study, the rapidly setting and hardening high-belite sulfoaluminate cement (HBSAC) is used as the cementitious material, with natural river sand as the fine aggregate, and a high-performance repair mortar is prepared through the synergistic use of different polymers and admixtures. The influences of two polymers (VAE and HPMC) on the working performance, mechanical properties, and hydration characteristics of HBSAC mortars are systematically studied. The results showed that the two polymers had a significant improvement effect on the setting time, mortar flowability, and water retention rate of HBSAC mortar. Among them, VAE had a significant effect on the mortar flowability, and a 5% content could increase the flowability of HBSAC mortar by 29.8%. HPMC has a significant improvement effect on setting time and water retention rate; at 0.1% content, it can delay the initial setting time by 6.5 min and achieve a water retention rate of over 90%. As the polymer to binder ratio increases, both polymers, except for 2.5% VAE, which can slightly improve the flexural strength of mortar, will reduce the flexural and compressive strength of mortar, with VAE causing greater damage to strength. On the contrary, the polymer significantly enhanced the bond strength of the mortar. Compared with the cement control group, the 28 d bond strength of 5% VAE and 0.1% HPMC groups increased by 56.7% and 15.1%, respectively. Moreover, the addition of polymers delayed the occurrence of the exothermic peaks of HBSAC dissolution and ettringite formation, but the total amount of hydration heat released within 48 h was higher than that of pure cement. The diffraction peaks of AFt in the hydration products of VAE-HBSAC paste at 3d and 28d showed significant enhancement, and the peak intensity increased with higher doping levels, while the diffraction peak intensity of C₂S showed a certain decrease. The polymer significantly increased the weight loss peak intensity and mass loss after heating of AFt, AH₃, AFm, and C-S-H gel. The SEM images indicate that VAE can form a mesh on the surface of hydration products and refine the crystal size of AFt; HPMC wraps more flocculent substances around the hydration products, thereby improving the compactness of paste. This study can provide scientific reference for improving the performance and promoting the practical application of high-performance rapid repair mortar for concrete structure damage. Full article

The application of silk sericin as a polymeric biomaterial has recently gained interest, although its film was found to be fragile, exhibiting brittleness when subjected to relatively slight stress, and it also displayed higher water solubility. This study focused on the enhanced physico-mechanical properties of the three films obtained by the crosslinking of sericin protein from three silkworm cocoons with poly (vinyl alcohol) (PVA) to reduce phase separation and solubilization of the films by promoting miscibility between sericin and PVA. The findings demonstrated how crosslinking with glutaraldehyde enhanced thermal stability and tensile strength and controlled the solubility of the three sericin–PVA films. The sericin from G. postica, G. rufobrunnea, and Argema mimosae is composed of serine, aspartic acid, and glutamic acid, which make up 80% of the total polar amino acids. X-ray diffraction (XRD) patterns showed that sericin–PVA films have semicrystalline features, representing amorphous and crystalline regions. The XRD results also indicated that the Saturniidae sericin–PVA film (Sat-SPF), Gonometa postica sericin–PVA film (GP-SPF), and Gonometa rufobrunnea sericin–PVA film (GR-SPF) have crystallinity percentages of 66.4%, 55.9%, and 17.7%, respectively. The moisture vapor transmission rate (MVTR) values observed in this study ranged from 991.2 to 5160 g/m²/24 h, indicating that these films can effectively regulate moisture levels in wounds. The swelling capacity of the three sericin–PVA composite films depends on the crosslinking density of their structures and was also found to be sensitive to the pH of the aqueous media, demonstrating their hydrophilic nature and potential use in drug delivery systems. The water vapor permeability of sericin–PVA films increased with higher environmental relative humidity (RH) and moisture content within the films. The elongation at break for GP-SPF (107.2% ± 3.1) and Sat-SPF (73.0% ± 4.1) was significantly higher than in GR-SPF (29.3% ± 2.3). However, their tensile strength and elastic modulus were lower than those of GR-SPF. These results show that the number of polar groups (amino and hydroxyl groups) from both sericin and PVA influences all the properties of the sericin–PVA composite films. The three sericin–PVA solutions were found to have antibacterial efficacy against three Gram-positive and one Gram-negative bacteria over 24 h. Scanning electron microscopy (SEM) images revealed a rough surface with a granular network pattern, which supports the potential use of sericin–PVA films for cell adhesion and proliferation, which are essential for biomedical wound dressing applications. Full article

Ghost imaging, ghost interference, and ghost diffraction retrieve an object’s spatial distribution and interference–diffraction patterns via intensity correlation. Flexibly synthesizing multi-channel optical information within a single correlation architecture is a key challenge in the evolution of optical correlation from fundamental research to information processing platforms. This study proposes the Extended Operational Ghost Correlation Model (EO-GCM), which introduces the four arithmetic operations (addition, subtraction, multiplication, and division) into optical correlation data processing. Within circular complex Gaussian pseudothermal light fields, the study systematically derives the analytical expressions for the second-order intensity fluctuation correlations with these operations. The theory shows that addition and subtraction obey superposition, whereas for multiplication and division, the average intensity of one object path becomes a weighting factor for the information of the other path. When weakly correlated, multiplication yields a weighted sum, whereas division yields a weighted difference, with the two weights having opposite signs. Experiments on ghost interference or diffraction and ghost imaging verify theoretical predictions and confirm the proportionality between the absolute value of the negative weight in division and the average intensity of the numerator path. The proposed model enables basic operations on multipath object signals, endowing optical correlation systems with reconfigurable, weighted correlation fusion-based information modulation capabilities. Full article

This study aims to compare the structural, mechanical, tribological, and corrosion properties of gradient and bilayer Al₂O₃/Cr₂O₃ coatings obtained by detonation spraying on 316L stainless steel. The coatings were characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, instrumental indentation, scratch testing, ball-on-disk tribological testing, and potentiodynamic polarization in a 3.5% NaCl solution. The results showed that the gradient Al₂O₃/Cr₂O₃ coating had a denser and more homogeneous structure than the bilayer coating. Quantitative SEM image analysis showed that the apparent porosity decreased from 1.285% for the bilayer coating to 0.934% for the gradient coating. Instrumental indentation revealed an increase in hardness from approximately 401 HV to 462 HV and an increase in elastic modulus from about 173 GPa to 183 GPa. The gradient coating also demonstrated higher critical loads during scratch testing, indicating improved resistance to crack initiation and coating failure. Tribological tests showed a lower and more stable coefficient of friction for the gradient coating, decreasing from approximately 0.58–0.60 to 0.52–0.55. Potentiodynamic polarization measurements showed that the corrosion current density decreased from 0.50540 to 0.24155 µA/cm², while the corrosion rate decreased from 0.00894 to 0.00428 mm/year. These results demonstrate that the gradient coating architecture improves the performance of Al₂O₃/Cr₂O₃ coatings by reducing porosity, increasing structural integrity, and promoting an improved structural integrity and reduced defect-related stress concentration through the coating thickness. Therefore, gradient Al₂O₃/Cr₂O₃ coatings obtained by detonation spraying are promising for applications requiring enhanced wear and corrosion resistance. Full article