Search Results (12,725)

Duckweed/algal bloom-type black–odorous waters (DAWs) exhibit composite optical properties of vegetation and pollution, posing intractable remote sensing identification challenges in complex environments. Current methods suffer from three critical limitations: a misclassification rate exceeding 25% due to spectral confusion with artificial green covers, an 18.7% false-negative rate for small patches (stemming from the imbalance between CNNs and Transformers), and insufficient feature dimensionality to characterize the dual properties of DAWs. To address these gaps, this study proposes a novel method that integrates the ASGICTVS feature set with a customized SwinTf-Unet model. The ASGICTVS feature set combines vegetation-sensitive metrics, optical water quality indicators, and visual features. The SwinTf-Unet model utilizes an optimized 4 × 4 window, an embedded feature fusion module, and an adaptive shifted window stride to balance global context capture and local detail reconstruction. Experiments on 21,104 GF-2 satellite samples demonstrate that the method achieves 87.50% precision, 88.41% recall, an 85.32% F1-score, and an 83.46% Intersection over Union (IoU), outperforming DeepLabV3+ by 14.56 percentage points in the IoU. With an inference time of 0.87 s per 512 × 512-pixel image and a stable performance across cross-regional datasets (IoU: 82.1–85.3%), it exhibits strong efficiency and generalization. This study resolves DAW spectral confusion, enables high-precision segmentation, and establishes a standardized feature threshold system, providing reliable technical support for large-scale automated DAW monitoring and regional water environment management. Full article

Near-field scanning microwave microscopy (NSMM) offers the ability to probe local electromagnetic properties beyond the classical Abbe diffraction limit, but achieving high resolution over practical scan areas remains challenging. In this work, we introduce a novel three-dimensional (3D) NSMM probe consisting of a split-ring resonator (SRR) coupled to a microstrip line and loaded with vertically extended metallic bars. The 3D loading enhances electric-field localization in the sensing region by introducing field singularities. Full-wave numerical simulations are used to extract the field-spread function ($FSF$) of the probe and to quantify how probe geometry, stand-off distance, and bar dimensions control the $FSF$ and its spatial-frequency (k-space) content. An imaging model is then developed in which the NSMM image is represented as a convolution between the object and $FSF$ in one and two dimensions. This framework demonstrates that progressively localized $FSFs$, obtained through 3D loading and resonator miniaturization, systematically improve image fidelity and preserve higher spatial frequencies. The probe is fabricated using printed circuit board technology (PCB) with vertically attached metallic bars, and its performance is validated by imaging a dielectric slab containing a cylindrical air-filled void. The measured line profiles and two-dimensional images are in good agreement in general characteristics with the convolution-based model, confirming that the proposed 3D SRR-based probe operates as a spatial filter whose engineered near-field distribution governs the achievable resolution in NSMM imaging. Full article

Laser-induced autofluorescence (LIAF) spectroscopy is a label-free optical technique sensitive to biochemical and structural tissue properties. Its application in upper aerodigestive tract malignancies is in its early stages. This study evaluates the feasibility of a matrix scan-based LIAF approach for examining differences between normal and malignant tissues. An exploratory case series involving three patients with oropharyngeal malignancies was conducted. Tissue sections from normal and tumor regions were analyzed using LIAF spectroscopy, including intensity and lifetime measurements, implemented through a matrix scanning protocol with fixed excitation, detection sensitivity, and sample thickness. Complementary Fourier-transform infrared (FTIR) spectroscopy was used to qualitatively assess biochemical variations, and spectroscopic findings were correlated with histopathological evaluation. Within individual cases, consistent differences in autofluorescence spectral and lifetime characteristics were observed between benign and malignant tissue regions. FTIR analysis revealed concurrent biochemical variations that qualitatively supported the autofluorescence observations. This exploratory study demonstrates the potential of combining LIAF matrix scan with FTIR spectroscopy to investigate tissue-specific spectral variations in upper aerodigestive tract lesions. The findings are preliminary and motivate further investigation using larger patient groups and clinically relevant acquisition conditions. Full article

Arc welding techniques for applying austenitic stainless steel cladding to low-carbon steels are common. Cladding enhances surface properties, increases corrosion resistance, improves product performance, extends service life, and reduces maintenance costs associated with surface corrosion. The hot-wire gas tungsten arc welding (HW-GTAW) method offers several benefits, making it appealing for cladding applications. This research investigates the use of HW-GTAW to clad low-carbon steels with super-austenitic stainless steel, examining macro and microstructures, mechanical strength, corrosion resistance, and wear performance. Two conditions were tested: one without a hot-wire, called CW-GTAW (cold-wire), and one with a hot-wire, called HW-GTAW. The HW-GTAW process reduced the dilution rate, thereby benefiting cladding. Microstructural analysis showed that both conditions exhibited elongated columnar dendrites in the heat-affected zone and a shallow region of equiaxed dendrites near the surface. The HW-CL condition displayed slight improvements in corrosion and wear resistance, but both samples outperformed the uncoated base material. These findings support the expanded application of super austenitic stainless steels and HW-GTAW in cladding processes. Full article

This study investigates the molecular and mechanical effects of sodium accumulation in myocardial tissue using a combination of physiological measurements and Raman spectroscopy. Male Wistar rats were maintained on normal- and high-salt diets to induce differential sodium loading in cardiac tissue. Hemodynamic and mechanical analyses revealed increased myocardial stiffness and altered contractile parameters in the high-salt group. Raman microspectroscopy of myocardial sections demonstrated distinct spectral changes, particularly in regions corresponding to glycosaminoglycan (GAG), collagen, and its component, proline. Enhanced Raman signals near 1640 cm⁻¹ in the Amide I range, 1246 cm⁻¹ in the Amide III range, and in the 1030–1070 cm⁻¹ range indicated structural modifications of the GAG–collagen complex and an increased contribution of proline-rich collagen, consistent with elevated tissue rigidity. These findings support the concept that sodium deposition in the myocardium alters its molecular architecture and mechanical properties through GAG-mediated binding and collagen remodeling. This study provides new insights into the biophysical mechanisms linking sodium homeostasis to myocardial stiffness and diastolic dysfunction. Full article

The tumor microenvironment, characterized by higher acidity, hypoxia, and dense cellular structures, plays a pivotal role in cancer progression, therapeutic resistance, and treatment response. Nanoparticle-based contrast agents enable the precise delineation of solid regions within heterogeneous tumors through advanced molecular imaging techniques. Since 1956, ultrasound (US) medical imaging has provided essential anatomical and functional insights about internal organs. More recently, magnetomotive ultrasound (MMUS) has emerged as a promising imaging modality, using a modulated magnetic field to exert force on superparamagnetic iron oxide nanoparticles (SPIONs), inducing motion in the surrounding tissues through mechanical coupling. In parallel, magnetic hyperthermia (MH), which employs localized heating by alternating magnetic fields, has demonstrated significant potential in selectively destroying cancer cells while sparing healthy tissues. This review summarizes the current state of IONP-based contrast agents, with particular emphasis on their use in MH for cancer treatment, as well as their potential in multimodal imaging, including MMUS, and photoacoustic (PA) imaging. The advantages and limitations of IONPs in tumor detection and characterization are discussed, examining the development of surface-functionalized MNPs, and analyzing how material properties and environmental factors affect their diagnostic and therapeutical performance. Finally, strategies for combining MMUS and PA modalities for pre-clinical cancer imaging are proposed. Full article

Pulque is a traditional Mexican fermented beverage produced by the spontaneous fermentation of the sap (aguamiel) produced by several Agave (maguey) species. Pulque fermentation starts with the addition of freshly collected aguamiel (harvested twice daily) into a traditional container known as the tinacal, which contains previously fermented pulque serving as a microbial inoculum; the native microbiota associated with both the aguamiel and the inoculum ferments the available sugars, driving the development of the beverage’s characteristic sensorial properties. However, the preservation of its complex microbiota for research, fermentation standardization, and long-term conservation has not been systematically evaluated. In this study, we assessed the impact of freeze-drying on the viability, taxonomic composition, and diversity of the bacterial and yeast communities of pulque across five independent batches. Viable counts revealed no systematic loss of cultivable populations across major guilds. High-throughput sequencing of the V3-V4 16S rDNA and ITS1 regions demonstrated that the global taxonomic structure of pulque is preserved mainly after freeze-drying, with dominant genera, including Lactobacillus, Acetobacter, Zymomonas, Lactococcus, Saccharomyces, and Kazachstania, remaining stable. A modest decrease in richness, without major shifts in community architecture, was observed among minor yeasts, indicating that freeze-drying effectively preserves the core microbiota of pulque. Moreover, preserving pulque biomass safeguards the microbial dimension of this ancestral biocultural resource while enabling future efforts to standardize fermentation and establish microbial biobanks. Full article

Pteridium aquilinum (L.) Kuhn, known as bracken fern, is considered a poisonous plant due to its toxic substances. This species contains toxic substances and enzymes: thiaminase and an anti-thiamine substance, which cause thiamine deficiency syndrome. Prunasin induces acute cyanide poisoning. Ptaquiloside causes haematuria, retinal atrophy, immunodeficiency, and lymphoproliferative disorders. It also induces carcinogenesis in livestock, and in animals and human cell lines. Ptaquiloside has been found in the milk of cattle, goats, and sheep that grazed on P. aquilinum in pastures. Ptaquiloside is water-soluble and washes away from the plants into the soil with rainwater. It has been found in streams and groundwater wells. The International Agency for Research on Cancer has classified bracken fern as a Group 2B carcinogen. However, P. aquilinum has long been used as a folk remedy in various regions. Several studies have identified its medicinal value and bioactive compounds with potential pharmacological activity. Pterosin B and its analogues exhibit anti-osteoarthritis, anti-Alzheimer’s disease, neuroprotective, anti-cardiomyocyte hypertrophy, anti-diabetic, and smooth muscle relaxant properties. Ptaquiloside also induces apoptosis in certain human cancer cell lines and acts as an anticancer agent. Therefore, pterosins and ptaquiloside have therapeutic properties. Other compounds, including some flavonoids and polysaccharides, act as antimicrobial, antifungal, and immunomodulatory agents. Based on their structures, it is possible to develop medicines with these therapeutic properties, particularly those containing pterosins and ptaquiloside. However, more research is needed on their use in medicinal treatments. Full article

This review synthetizes experimental evidence on collagen-related bioactivity and the biomaterial potential of plant species native to the Chihuahuan Desert, aiming to identify natural compounds that could enhance next-generation dermal bioinks for 3D bioprinting. A structured search across major databases included studies characterizing plant extracts or metabolites, with reported effects on collagen synthesis, fibroblast activity, inflammation, oxidative balance, or interactions with polymers commonly used in skin-engineering materials being developed. Evidence was organized thematically to reveal mechanistic patterns despite methodological heterogeneity. Several species, among them Larrea tridentata, Opuntia spp., Aloe spp., Matricaria chamomilla, Simmondsia chinensis, Prosopis glandulosa, and Artemisia ludoviciana, repeatedly demonstrated the presence of bioactive metabolites such as lignans, flavonoids, phenolic acids, terpenoids, and polysaccharides. These compounds support pathways central to extracellular matrix repair, including stimulation of fibroblast migration and collagen I/III expression, modulation of inflammatory cascades, antioxidant protection, and stabilization of ECM structures. Notably, several metabolites also influence viscoelastic and crosslinking behaviors, suggesting that they may enhance the printability, mechanical stability, and cell-supportive properties of collagen-, GelMA-, and hyaluronic acid-based bioinks. The review also reflects on the bioethical and sustainability considerations regarding endemic floral resources, highlighting the importance of responsible sourcing, conservation extraction practices, and alignment with international biodiversity and access to benefit/sharing frameworks. Taken together, these findings point to a promising, yet largely unexplored, opportunity: integrating regionally derived phytochemicals into bioinks to create biologically active, environmentally conscious, and clinically relevant materials capable of improving collagen remodeling and regenerative outcomes in 3D-printed skin. Full article

In this study, we present the synthesis of TiO₂ nanomaterials doped with different mol% cobalt, prepared by the sol–gel method for CO₂ reduction using UV light. The nanomaterials were calcined at 400 °C for 4 h. Characterization of the nanomaterials was performed using XRD-Rietveld refinement, XPS, Raman spectroscopy, diffuse reflectance spectroscopy (DRS), SEM-EDS, TEM-HRTEM, BET area, photoluminescence, and electrochemical techniques. The results show that the incorporation of cobalt into TiO₂ modifies the structural properties, binding energies, and oxygen vacancy generation, it undergoes a shift towards the visible region, the recombination of charge carriers decreases, and the BET area is slightly modified. The photoreduction of CO₂ with the highest production of methane and ethane is with 1% mol% of cobalt in TiO₂, exhibiting values 3 and 14 times higher with respect to TiO₂, which is attributed to the efficiency in the separation of photogenerated species (e⁻/h⁺) as a consequence of the generation of energetic states that function as an electron trap and thus improve the photocatalytic activity for the photoreduction of CO₂. Full article

In the face of accelerating climate change and increasingly complex disturbance regimes, enhancing forest ecosystem resilience has become a core priority in forest ecology and management. This paper argues that long-term resilience in hemiboreal forests depends fundamentally on the management of ecosystem legacies—structural, compositional, and functional remnants that persist following past disturbances and land use. Organized under the resilience framework, this perspective emphasizes that resilience is not solely a matter of response or effect, but an emergent property shaped by abiotic and biotic legacies, including life history traits, landscape heterogeneity, and both anthropogenic and natural disturbance. In this paper, drawing from disturbance ecology, resilience theory, and regional empirical studies, a conceptual model is presented that integrates legacy attributes, environmental filters, and management objectives to support adaptive restoration strategies. It helps design restoration pathways that are ecologically meaningful, operationally realistic, and robust to novel disturbance regimes. By operationalizing legacy–action linkages, the model offers practitioners concrete entry points for retention, disturbance use, and landscape design to enhance resilience. Full article

In this work, we extend the classical framework of quantization for Borel probability measures defined on normed spaces ${\mathbb{R}}^k$ by introducing and analyzing the notions of the nth constrained quantization error, constrained quantization dimension, and constrained quantization coefficient. These concepts generalize the well-established nth quantization error, quantization dimension, and quantization coefficient, which are traditionally considered in the unconstrained setting and thereby broaden the scope of quantization theory. A key distinction between the unconstrained and constrained frameworks lies in the structural properties of optimal quantizers. In the unconstrained setting, if the support of P contains at least n elements, then the elements of an optimal set of n-points coincide with the conditional expectations over their respective Voronoi regions; this characterization does not, in general, persist under constraints. Moreover, it is known that if the support of P contains at least n elements, then any optimal set of n-points in the unconstrained case consists of exactly n distinct elements. This property, however, may fail to hold in the constrained context. Further differences emerge in asymptotic behaviors. For absolutely continuous probability measures, the unconstrained quantization dimension is known to exist and equals the Euclidean dimension of the underlying space. In contrast, we show that this equivalence does not necessarily extend to the constrained setting. Additionally, while the unconstrained quantization coefficient exists and assumes a unique, finite, and positive value for absolutely continuous measures, we establish that the constrained quantization coefficient can exhibit significant variability and may attain any nonnegative value, depending critically on the specific nature of the constraint applied to the quantization process. Full article

Background/Objectives: Cephalosporins represent one of the most important classes of β-lactam antibiotics, widely used in clinical practice due to their broad-spectrum activity and favorable safety profile. As generations evolved, structural modifications were introduced to expand antimicrobial coverage and overcome β-lactamase resistance. This study aimed to analyze the drug-like properties of cephalosporins across different generations using molecular descriptors to identify structural and pharmacokinetic patterns influencing bioavailability and oral administration profiles. Methods: Thirty-eight cephalosporins representative of different generations were selected. Molecular data were obtained from PubChem, and SMILES were extracted and validated. Molecular descriptors (including MW, logP, TPSA, HBA, HBD, rotatable bonds, and global complexity indices) were calculated using the SwissADME and ChemDes platforms. Statistical analysis included ANOVA followed by post hoc tests, and principal component analysis (PCA). Results: A progressive increase in molecular weight, polarity, and TPSA was observed across generations, with fourth-generation cephalosporins showing significantly higher values compared to first-generation compounds (p < 0.0001). LogP decreased significantly in fourth-generation agents (p < 0.0001), reflecting increased polarity. PCA revealed that most compounds from generations 1–2 cluster in regions consistent with Lipinski’s and Veber’s rules, whereas fourth- and fifth generation - cephalosporins deviated substantially, prioritizing antimicrobial efficacy over oral bioavailability. Recurrent structural modifications such as oximes, tetrazoles, and aminothiazoles were identified, with increasing frequency in modern generations. Conclusions: The evolution of cephalosporins reflects a strategic shift toward enhanced antimicrobial potency and β-lactamase stability at the expense of oral bioavailability. Understanding these structural transitions provides valuable insights for rational drug design, aiming to balance antimicrobial effectiveness with favorable pharmacokinetic profiles essential for therapeutic success. Full article

CO₂ flooding is an effective technique for enhancing oil recovery in low-permeability reservoirs. However, it is often hindered by severe CO₂ channeling. This challenge is particularly pronounced in near-wellbore regions with large pressure differentials and in fractured reservoirs, where high CO₂ injection rates and rapid breakthrough require channel blocking systems with high mechanical strength and excellent CO₂-resistant performance. In this work, a smart responsive polymer was synthesized and subsequently crosslinked with a highly active phenolic resin crosslinking agent to develop a smart responsive polymer gel channel blocking system. The resulting gel exhibits CO₂-responsive strength enhancement and excellent CO₂-resistant performance. The static and dynamic gelation behaviors, nonlinear rheological properties, CO₂-resistant performance, channel blocking, and enhanced oil recovery performance of the smart responsive polymer gel were systematically investigated. The results demonstrate that the polymer gel maintains good structural stability during dynamic transport in the reservoir and does not undergo significant strength degradation under shear conditions. Moreover, the smart responsive polymer gel exhibits excellent CO₂-resistant performance within a temperature range of 80–110 °C, salinity up to 10 × 10⁴ mg/L, and pressure up to 20 MPa. Moreover, the system shows a significant enhancement in channel blocking and enhanced oil recovery performance, highlighting its promising potential for effective CO₂ flooding channel blocking in low-permeability reservoirs. Full article

This paper presents PLAM (Plovdiv Air Monitoring)—a regional multi-agent platform for air quality monitoring, semantic reasoning, and forecasting. The platform uses a hybrid architecture that combines two types of intelligent agents: classic BDI (Belief-Desire-Intention) agents for complex, goal-oriented behavior and planning, and ReAct agents based on large language models (LLM) for quick response, analysis, and interaction with users. The system integrates data from heterogeneous sources, including local IoT sensor networks and public external services, enriching it with a specialized OWL ontology of environmental norms. Based on this data, the platform performs comparative analysis, detection of anomalies and inconsistencies between measurements, as well as predictions using machine learning models. The results are visualized and presented to users via a web interface and mobile application, including personalized alerts and recommendations. The architecture demonstrates essential properties of an intelligent agent such as autonomy, proactivity, reactivity, and social capabilities. The implementation and testing in the city of Plovdiv demonstrate the system’s ability to provide a more objective and comprehensive assessment of air quality, revealing significant differences between measurements from different institutions. The platform offers a modular and adaptive design, making it applicable to other regions, and outlines future development directions, such as creating a specialized small language model and expanding sensor capabilities. Full article