Search Results (1,487)

This paper proposes a compact UHF microstrip divider with wideband harmonic suppression. A combined resonator, formed by a T-shaped resonator and a pair of coupled compact microstrip resonant cells (CCMRCs), is embedded into each divider branch to replace the conventional quarter-wavelength transmission lines. The divider is designed on an FR4 substrate (ε_r = 4.4, thickness = 60 mil) for a center frequency of 570 MHz. Full-wave electromagnetic simulations indicate equal power division at 570 MHz with return loss better than 39 dB and output-port isolation higher than 47 dB. Moreover, a wide stopband from 1.5 GHz to 3.5 GHz is obtained, yielding strong attenuation for the third-to-sixth harmonics. The proposed layout occupies 19.6 mm × 21.6 mm, which is about 76% smaller than a conventional 570 MHz divider (42.7 mm × 41 mm). The proposed design is suitable for modern wireless communication systems. Full article

Background/Objectives: Diagnosing Rotator Cuff Tears (RCTs) via Magnetic Resonance Imaging (MRI) is clinically challenging due to complex 3D anatomy and significant interobserver variability. Traditional slice-centric Convolutional Neural Networks (CNNs) often fail to capture the necessary volumetric context for accurate grading. This study aims to develop and validate the Patient-Aware Vision Transformer (Pa-ViT), an explainable deep-learning framework designed for the automated, patient-level classification of RCTs (Normal, Partial-Thickness, and Full-Thickness). Methods: A large-scale retrospective dataset comprising 2447 T2-weighted coronal shoulder MRI examinations was utilized. The proposed Pa-ViT framework employs a Vision Transformer (ViT-Base) backbone within a Weakly-Supervised Multiple Instance Learning (MIL) paradigm to aggregate slice-level semantic features into a unified patient diagnosis. The model was trained using a weighted cross-entropy loss to address class imbalance and was benchmarked against widely used CNN architectures and traditional machine-learning classifiers. Results: The Pa-ViT model achieved a high overall accuracy of 91% and a macro-averaged F1-score of 0.91, significantly outperforming the standard VGG-16 baseline (87%). Notably, the model demonstrated superior discriminative power for the challenging Partial-Thickness Tear class (ROC AUC: 0.903). Furthermore, Attention Rollout visualizations confirmed the model’s reliance on genuine anatomical features, such as the supraspinatus footprint, rather than artifacts. Conclusions: By effectively modeling long-range dependencies, the Pa-ViT framework provides a robust alternative to traditional CNNs. It offers a clinically viable, explainable decision support tool that enhances diagnostic sensitivity, particularly for subtle partial-thickness tears. Full article

Background: Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disease and affects male patients more often than women. Prior studies, however, suggested that women are diagnosed later and at advanced stages of the disease, present with more pronounced symptoms, and experience worse outcomes. Objectives: To investigate sex-specific differences in clinical, laboratory, and comprehensive imaging characteristics in a contemporary cohort of HCM patients from a tertiary referral center in Austria. Methods: We retrospectively analyzed 321 HCM patients enrolled in a prospective registry (2018–2024). All patients underwent a comprehensive baseline evaluation, including medical history, laboratory assessment, transthoracic echocardiography, and cardiac magnetic resonance imaging. Results: At diagnosis, women were significantly older (62 vs. 53 years, p < 0.001) and presented with more advanced functional class (NYHA ≥ II: 80% vs. 49%, p < 0.001). Six-minute walking distance was lower and obstructive HCM was more prevalent in women (425 vs. 505 m, p < 0.001, and 55% vs. 32%, p < 0.001, respectively). Echocardiographic assessment revealed higher diastolic filling pressures (E/E′ 18 vs. 10, p < 0.001), larger indexed atrial volumes (29.5 vs. 26.6 mL/m², p < 0.001), a higher left ventricular ejection fraction (70% vs. 62%, p < 0.001), and a larger indexed interventricular septal thickness in women (10.2 vs. 9.3 mm/m², p = 0.004). Moreover, serum levels of NT-proBNP were significantly higher in women (760 vs. 338 pg/L, p < 0.001). Conclusions: Female patients with HCM were diagnosed at an older age, presented with more advanced symptoms, had higher rates of obstructive physiology, and a phenotype characterized by diastolic dysfunction and elevated biomarkers, closely resembling heart failure with preserved ejection fraction. Recognizing these sex-specific disparities is crucial in improving diagnostic awareness and individualized therapeutic management. Full article

The present work explores the viscoelastic properties of a homologous series of organosilicon fluids (polymethylsiloxane fluids) using the acoustic resonant method at a frequency of shear vibrations of approximately 100 kHz. The resonant method is based on investigating the influence of additional binding forces on the resonant characteristics of the oscillatory system. The fluid under study was placed between a piezoelectric quartz crystal that performs tangential oscillations and a solid cover plate. Standing shear waves were established in the fluid. The thickness of the liquid layer was much smaller than the length of the shear wavelength, and low-amplitude deformations allowed for the determination of the complex shear modulus G* in the linear region, where the shear modulus has a constant value. The studies demonstrated the presence of a viscoelastic relaxation process at the experimental frequency, which is several orders of magnitude lower than the known high-frequency relaxation in liquids. In this work, the relaxation frequency of the viscoelastic process in the studied fluids and the effective viscosity were calculated, and the lengths of the shear wave and the attenuation coefficients were determined. Full article

In this study, we investigated the effect of annealing ultrathin silver (Ag) films of varying thicknesses (1–6 nm) on both their optical absorption and the performance of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) organic solar cells (OSCs). The Ag films were deposited on indium tin oxide (ITO) anodes and annealed at 300 °C for 1–2 h to modify the anodic interface. The optical and electrical properties of the resulting devices were systematically characterized and optimized. The results revealed that a 1 nm AgO layer annealed for 2 h significantly enhanced the device performance, yielding a 6% increase in power conversion efficiency compared to the standard configuration. This improvement is attributed to two main factors: (i) a 25% increase in light absorption of the AgO/P3HT:PCBM film due to localized surface plasmon resonance of Ag nanoparticles and (ii) an 11% reduction in series resistance resulting from the favorable alignment of the Ag work function with the ITO anode and the polymer HOMO, which facilitates efficient hole extraction. These findings highlight the potential of ultrathin, annealed Ag/AgO interfacial layers as an effective strategy to enhance light absorption and charge transport in OSCs. Full article

The Wufeng–Longmaxi (WF–LMX) shale gas reservoirs at depths > 3500 m in the Lu203–Yang101 well block, southern Sichuan Basin, possess great exploration potential, but their reservoir characteristics and high-production mechanisms remain unclear. In this study, we employed multi-scale analyses—including core geochemistry, X-ray diffraction (XRD), scanning electron microscopy (SEM), low-pressure N₂ adsorption, and nuclear magnetic resonance (NMR)—to characterize the macro- and micro-scale characteristics of these deep shales. By comparing with shallower shales in adjacent areas, we investigated differences in pore structure between deep and shallow shales and the main controlling factors for high gas-well productivity. The results show that the Long 11 sub-member shales are rich in organic matter, with total organic carbon (TOC) content decreasing upward. The mineral composition is dominated by quartz (averaging ~51%), which slightly decreases upward, while clay content increases upward. Porosity ranges from 1% to 7%; the Long11-1-3 sublayers average 4–6%, locally >6%. Gas content correlates closely with TOC and porosity, highest in the Long11-1 sublayer (6–10 m³/t) and decreasing upward, and the central part of the study area has higher gas content than adjacent areas. The micro-pore structure exhibits pronounced stratigraphic differences: the WF Formation top and Long11-1 and Long11-3 sublayers are dominated by connected round or bubble-like organic pores (50–100 nm), whereas the Long11-2 and Long11-4 sublayers contain mainly smaller isolated organic pores (5–50 nm). Compared to shallow shales nearby, the deep shales have a slightly lower proportion of organic pores, smaller pore sizes with more isolated pores, inorganic pores of mainly intraparticle types, and more developed microfractures, confirming that greater burial depth leads to a more complex pore structure. Type I high-quality reservoirs are primarily distributed from the top of the WF Formation to the Long11-3 sublayer, with a thickness of 15.6–38.5 m and a continuous thickness of 13–23 m. The Lu206–Yang101 area has the thickest high-quality reservoir, with a cumulative thickness of Type I + II exceeding 60 m. Shale gas-well high productivity is jointly controlled by multiple factors: an oxygen-depleted, stagnant deep-shelf environment, with deposited organic-rich, biogenic siliceous shales providing the material basis for high yields; abnormally high pore-fluid pressure with preserved abundant large organic pores and increased free gas content; and effective multi-stage massive fracturing connecting a greater reservoir volume, which is the key to achieving high gas-well production. This study provides a scientific basis for evaluating deep marine shale gas reservoirs in southern Sichuan and understanding the enrichment patterns for high productivity. Full article

Background: Wound healing contributes to restoring skin integrity. However, scars affect soft tissue in all its layers, including the superficial and deep fascia; moreover, it has been demonstrated that the fibroblasts leading the scarring process develop from progenitors located in the superficial fascia. In the past, research into scar etiology has focused primarily on the dermal and epidermal layers, leaving the role of the fasciae largely overlooked. Many patients presenting with surgical or traumatic scars complain of the increased stiffness and thickness of the scar, reduced extensibility of the area surrounding it, and chronic pain persisting even after the healing process has been completed. The purpose of this systematic review is to investigate the non-invasive tools and methods employed for the objective evaluation of scars that involve fascial layers. Methods: A systematic literature search was conducted on PubMed and WOS. Registration DOI: 10.17605/OSF.IO/SDR3Q. Results: A total of 11 articles were selected; the etiologies of scars were surgical, traumatic, and other (keloids). The investigations were conducted using ultrasound, magnetic resonance imaging, strain elastography, and shear wave elastography on the visceral fasciae, superficial fascia, hypodermis, and musculoskeletal fasciae. Sliding of fasciae was assessed by ultrasound; thickness of fasciae was assessed by ultrasound and magnetic resonance imaging; stiffness was assessed by shear wave elastography and strain elastography; and the qualitative assessment was performed via ultrasound. Conclusions: Our literature review showed that ultrasound, magnetic resonance imaging, strain elastography, and shear wave elastography are currently adopted for investigating the sliding, thickness, stiffness, and qualitative features of scars involving fascial layers. Moreover, our research showed the existence of a gap in the scientific literature on this topic. Full article

Structural optimization focusing on the root fillet radius and the crown and band thicknesses was implemented to prevent rotor–stator interaction-induced resonance, with the objective of enhancing the frequency safety margin for the 4-nodal-diameter mode shape. An ultra-high-head pump–turbine runner is analyzed using an acoustic fluid–structure coupling method to investigate modal characteristics and identify effective design improvements. The results show that increasing the root fillet radius from 0 to 50 mm raises the frequency safety margin from 3.7% to 8.5%, thereby significantly reducing the resonance risk. Likewise, increasing the thickness of the crown, the band, or both leads to higher frequency safety margins, with simultaneous thickening of both components delivering the most improvement. Frequency safety margins continue to rise as the degree of thickening increases. When a runner’s natural frequency is only slightly higher than the corresponding excitation frequency, design measures such as enlarging the root fillet radius and jointly thickening the crown and band effectively expand the frequency safety margin. These findings can provide designers with both qualitative and quantitative references when modifying these structural parameters to mitigate resonance risk. Full article

Amyloidosis is a group of disorders caused by extracellular deposition of insoluble fibrillar proteins, leading to progressive organ dysfunction. Cardiac amyloidosis is clinically significant, as myocardial infiltration results in restrictive cardiomyopathy, arrhythmias, and heart failure. The main subtypes are light-chain (AL) and transthyretin (ATTR) amyloidosis, while AA and isolated atrial amyloidosis (IAA) are less common. Accurate subtype identification is crucial for management and prognosis. Diagnosis requires a multimodal approach combining imaging and tissue-based techniques. Echocardiography is usually first-line, showing increased wall thickness, biatrial enlargement, and apical sparing. Cardiac magnetic resonance (CMR) provides superior tissue characterization through late gadolinium enhancement and elevated extracellular volume. Nuclear scintigraphy with 99mTc-labeled tracers enables non-invasive ATTR detection, while amyloid-specific PET tracers show potential for early diagnosis. Histochemical confirmation remains essential. Congo Red staining with apple-green birefringence under polarized light is the diagnostic gold standard, supported by Thioflavin T, PAS, and Alcian Blue stains. Immunohistochemistry and mass spectrometry aid amyloid typing, while electron microscopy provides ultrastructural confirmation. Integrating imaging, histochemical, immunohistochemical, and proteomic techniques enhances early recognition and precise classification, improving therapeutic strategies and patient outcomes. Full article

Background/Objectives: Thyroid eye disease (TED) can lead to structural and microvascular changes in the orbit and retina. This study aimed to investigate the associations between Clinical Activity Score (CAS), orbital magnetic resonance imaging (MRI) measurements, and retinal microvascular changes in TED patients. Methods: This cross-sectional study included 38 patients (76 eyes) with TED. Each patient underwent a comprehensive ophthalmological evaluation, CAS assessment, and a detailed medical history. Optical coherence tomography angiography (OCTA) was performed to quantify vessel density (VD) in the superficial and deep capillary plexus (SCP and DCP). Exophthalmos, extraocular muscle thickness and orbital fat thickness were measured on MRI scans to evaluate structural changes. Laboratory analyses included thyroid hormone levels, thyrotropin receptor antibodies (TRAb), anti-thyroid peroxidase antibodies (anti-TPO), and lipid profile. Results: Active TED patients (CAS ≥ 3) had significantly higher TRAb levels (p < 0.001), while anti-TPO did not differ between groups. Active eyes showed significantly higher DCP VD in the whole image (p = 0.013), parafovea (p = 0.012), and perifovea (p = 0.009) across all quadrants, with no difference in SCP or the foveal avascular zone (FAZ). In linear mixed model regression analyses, after adjusting for previous glucocorticosteroid therapy, higher triglycerides, greater medial rectus thickness, and whole-image DCP VD independently predicted higher CAS values (R² = 42, p < 0.001). After adjusting for age and sex, CAS remained significantly positive predictor of DCP VD in the parafovea (R² = 0.22, p < 0.001). Conclusions: Changes in DCP VD reflect TED activity and structural orbital involvement. Full article

Acoustic metamaterials are artificially engineered materials composed of subwavelength structural units, whose effective acoustic properties are primarily determined by structural design rather than intrinsic material composition. By introducing local resonances, these materials can exhibit unconventional acoustic behavior, enabling enhanced sound insulation beyond the limitations of conventional structures. In this study, a thin plate (thin sheet) refers to a structural element whose thickness is much smaller than its in-plane dimensions and can be accurately described using classical thin-plate vibration theory. When resonant mass blocks are attached to a thin plate, a thin-plate acoustic metamaterial is formed through the coupling between plate bending vibrations and local resonances. Thin-plate acoustic metamaterials exhibit excellent sound insulation performance in the low- and mid-frequency ranges. Multilayer configurations and the combination with porous materials can effectively broaden the insulation bandwidth and improve overall performance. However, the large number of structural parameters in multilayer composite thin-plate acoustic metamaterials significantly increases design complexity, making conventional trial-and-error approaches inefficient. To address this challenge, a neural-network-based inverse design framework is proposed for multilayer composite thin-plate acoustic metamaterials. An analytical model of thin-plate metamaterials with multiple attached cylindrical masses is established using the point matching and modal superposition methods and validated by finite element simulations. A multilayer composite unit cell is then constructed, and a dataset of 30,000 samples is generated through numerical simulations. Based on this dataset, a forward prediction network achieves a test error of 1.06%, while the inverse design network converges to an error of 2.27%. The inverse-designed structure is finally validated through impedance tube experiments. The objective of this study is to establish a systematic theoretical and neural-network-assisted inverse design framework for multilayer thin-plate acoustic metamaterials. The main novelties include the development of an accurate analytical model for thin-plate metamaterials with multiple attached masses, the construction of a large-scale simulation dataset, and the proposal of a neural-network-assisted inverse design strategy to address non-uniqueness in inverse design. The proposed approach provides an efficient and practical solution for low-frequency sound insulation design. Full article

Modern high-bypass turbofan engines often operate near their structural natural frequencies, posing significant challenges for vibration isolation in aircraft engine mount systems. This study presents a comprehensive modal optimization framework to enhance vibration isolation performance by maximizing the separation between excitation and natural frequencies. A dynamic model of a typical single-aisle airliner engine mount system is formulated. Modal analysis is conducted via finite element modeling in Abaqus, extracting 20 modes and identifying dominant modes based on effective mass criteria. To avoid resonance within the excitation range of 72–336 Hz, a genetic algorithm is employed in MATLAB R2023a (9.14) to optimize key geometric parameters, including mount thicknesses and thrust link dimensions. The optimized configuration achieves a 16.84% increase in minimum frequency separation and a 21.51% reduction in vibration transmissibility. The results demonstrate the efficacy of combining modal analysis with evolutionary algorithms in designing advanced engine mounting systems for improved vibration isolation in next-generation aircraft. Full article

In this work, a quasi-D-shaped photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) biosensor is proposed and numerically investigated using the finite element method (FEM) implemented in COMSOL Multiphysics version 6.2 for the detection of cancer cells with different refractive indices. The biosensor has a coating of plasmonic material gold (Au) and a polymer coat of polymethyl methacrylate (PMMA). The effects of plasmonic material thickness and air hole dimensions on key sensing parameters, including confinement loss (CL), wavelength sensitivity (WS), and amplitude sensitivity (AS), are systematically analyzed. The results revealed that increasing plasmonic thickness beyond its optimum value significantly raises CL while reducing sensitivity due to reduced penetration depth of the evanescent field. Similarly, variations in the geometrical dimensions of the air holes (±10%) also affect the sensor response, emphasizing the importance of precise structural optimization. For the optimized design the proposed biosensor exhibits high performance with a maximum WS of 31,000 nm/RIU for MDA-MB-231 cells under x-polarization and 29,500 nm/RIU under y-polarization. The corresponding resolutions achieved are as low as 3.22 × 10⁻⁶ RIU and 3.38 × 10⁻⁶ RIU, respectively, with AS exceeding 9000 RIU⁻¹. The WS, AS, and other sensing parameters obtained from our sensor are relatively higher than some of the PCF–SPR sensors reported recently. These numerical results demonstrate that the optimized quasi-D-shaped PCF–SPR biosensor exhibits enhanced sensitivity to refractive index (RI) variations associated with cancerous cells, suggesting its suitability for early detection. Full article

In recent years, achieving ultra-wideband electromagnetic absorption has emerged as a critical challenge in confronting advanced broadband electromagnetic detection technologies. This capability is essential for effectively countering sophisticated radar systems. In this study, we present a novel multilayer metamaterial absorber that integrates an FR4 transmission layer, a periodic gradient dielectric structure designed for resonant impedance matching, and a magnetic skin layer for enhanced energy dissipation. By employing asymptotic gradients in both structure and composition, this design achieves dual-gradient electromagnetic parameter modulation, enabling efficient absorption across the X, Ku, and K bands (8.6–26.4 GHz) with a total thickness of 3.5 mm (effective thickness: 2 mm) and a density that is one-third that of conventional magnetic metamaterials. The proposed absorber demonstrates polarization insensitivity, stability across wide incident angles (up to 60°), and an absorption efficiency of 94%, as confirmed by full-wave simulations and experimental validation. Moreover, the fiber-reinforced hierarchical structure addresses the traditional trade-off between broadband absorption performance and mechanical load-bearing capacity. Full article

Antarctic ice shelves regulate ice-sheet discharge and global sea-level rise, yet their rapid retreat underscores the need for new, low-cost monitoring tools. We analyze ambient seismic noise recorded by seismometers on the Pine Island Glacier ice shelf to characterize wind-induced signals and detect persistent structural resonances. Power spectral analysis shows that wind sensitivity is strongly damped compared with bedrock sites: noise increases only 5–7 dB from 0 to 25 m s⁻¹ winds, versus a 42 dB increase at an inland bedrock station, reflecting the contrasted coupling environments of floating and grounded substrates. The horizontal-to-vertical spectral ratio (HVSR) spectrograms reveal two temporally stable peaks at ~2.2 Hz and ~4.3 Hz that persist across stations and remain independent of environmental forcing. Forward modeling indicates that these peaks correspond to S-wave resonances within the ice shelf. The inferred ice-water interface depth (~440 m) agrees with the Bedmap2 thickness estimate (466 m). This work demonstrates that HVSR provides an effective passive, single-station method for measuring ice shelf thickness. Full article