Search Results (3,299)

Climate change has accelerated the retreat of Andean glaciers, with significant recent losses in the tropical Andes. This study evaluates the extinction of the Carihuairazo volcano glacier (Ecuador), quantifying its area from 1312.5 m² in September 2023 to 101.2 m² in January 2024, its thickness (from 2.5 m to 0.71 m), and its volume (from 2638.85 m³ to 457.18 m³), before its complete deglaciation in February 2024; this rapid melting and its small size classify it as a glacierette. Multivariate analyses (PCA and biclustering) were performed to correlate climatic variables (temperature, solar radiation, precipitation, relative humidity, vapor pressure, and wind) with glacier surface and thickness. The PCA explained 70.26% of the total variance, with Axis 1 (28.01%) associated with extreme thermal conditions (temperatures up to 8.18 °C and radiation up to 16.14 kJ m⁻² day⁻¹), which probably drove its disappearance. Likewise, Axis 2 (21.56%) was related to favorable hydric conditions (precipitation between 39 and 94 mm) during the initial phase of glacier monitoring. Biclustering identified three groups of variables: Group 1 (temperature, solar radiation, and vapor pressure) contributed most to deglaciation; Group 2 (precipitation, humidity) apparently benefited initial stability; and Group 3 (wind) played a secondary role. These results, validated through in situ measurements, provide scientific evidence of the disappearance of the Carihuairazo volcano glacier by February 2024. They also corroborate earlier projections that anticipated its extinction by the middle of this decade. The early disappearance of this glacier highlights the vulnerability of small tropical Andean glaciers and underscores the urgent need for water security strategies focused on management, adaptation, and resilience. Full article

The prevention of biofilm formation and algal biodeterioration on building materials, particularly on cultural heritage sites, is a growing concern. Due to regulatory restrictions on conventional algicidal biocides in Europe, natural alternatives such as essential oils are gaining interest for their potential use in heritage conservation. This study evaluates the anti-algal activity of Salvia officinalis and Equisetum arvense (essential oils, hydrolates, and extracts) against a mixed culture of five green algae species (Bracteacoccus minor, Stichococcus bacillaris, Klebsormidium nitens, Chloroidium saccharophilum, and Diplosphaera chodatii). The plant materials were processed using hydrodistillation and solvent extraction, followed by chemical characterization through gas chromatography–mass spectrometry (GC-MS). Biological efficacy was assessed by measuring algal growth inhibition, changes in biomass colour, chlorophyll a concentration, and fluorescence. S. officinalis yielded higher extract quantities (extraction yield: 23%) than E. arvense and contained bioactive compounds such as thujone, camphor, and cineole, which correlated with its strong anti-algal effects. The essential oil of S. officinalis demonstrated the highest efficacy, significantly inhibiting biofilm formation (zones of inhibition: 15–94 mm) and photosynthetic activity at 0.5% concentration (reduction in chlorophyll a concentration 90–100%), without causing visible discolouration of treated surfaces (∆E < 2). These findings highlight the potential of S. officinalis essential oil as a natural, effective, and material-safe algicidal biocide for the sustainable protection of cultural heritage sites. Full article

Background: Dental enamel demineralization is a critical early event in the development of dental caries. To address this, bioactive compounds have been explored for their potential to mitigate enamel demineralization and promote remineralization. Previous studies have demonstrated that varnishes containing natural compounds such as trans,trans-farnesol (tt-farnesol), quercetin, and theobromine exhibit antimicrobial activity, suggesting potential in caries prevention. Thus, this laboratory study assessed the ability of these varnishes to prevent enamel caries lesion formation by using a chemical model to determine whether these natural compounds interfered with de- and remineralization processes in the absence of a cariogenic biofilm. Methods: Sixty bovine enamel specimens, each measuring 5 × 5 × 2 mm, were selected according to their initial surface hardness (SHI), measured by Knoop hardness in three indentations spaced 100 µm apart. The specimens were allocated to the following groups in a random manner (n = 15): an experimental varnish without compounds (NC/negative control); experimental varnishes containing the combination of tt-farnesol, quercetin, and theobromine at concentrations of 1.5% (E1) and 4.5% (E2); and Duraphat™ (NaF 5%/gold standard—D). After applying the varnishes, they remained in artificial saliva for 6 h. The specimens were then subjected to 8 pH cycles, including 4 h of demineralization and 20 h of remineralization. Surface hardness was measured again to calculate the percentage of surface hardness loss (%SHL), and three specimens from each group were examined using scanning electron microscopy. Comparisons were made using ANOVA (p < 0.05). Results: The D group (5% NaF) demonstrated a significantly lower %SHL (75.5% ± 7.88) than the other groups (p < 0.05). E1 (86.3% ± 5.33) was statistically similar to NC (81.8% ± 4) but lower than E2. E2 showed the highest %SHL (91.6% ± 3.64) compared to the other groups. Surface demineralization was evident in all specimens post pH cycling. Conclusion: The bioactive varnishes containing tt-farnesol, quercetin, and theobromine at concentrations of 1.5% and 4.5% did not exhibit a protective effect against mineral loss in dental enamel in the absence of a cariogenic biofilm. Full article

This study investigates the capillary performance and wetting behavior of SLA (Stereolithography) 3D-printed porous structures, focusing on TPMS (triply periodic minimal surfaces)-Gyroid, Octet, Diamond, and Isotruss lattice designs. High-speed imaging was used to analyze droplet interactions, including penetration, spreading, and contact angles, with 16 μL water droplets dropping from 30 mm at 0.77 m/s. Results showed variable contact angles, with Isotruss and Octet having higher angles, while Diamond faced measurement challenges due to surface roughness. Numerical simulations of TPMS-Gyroid of 2 mm³ unit cells validated the experimental results, and Diamond, Octet, and Isotruss structures were simulated. Capillary performance was assessed through deionized (DI) water weight–time (w-t) measurements, identifying that the TPMS-Gyroid structure performed adequately. Structures with 4 mm³ unit cells had low capillary performance, excluding them from permeability testing, whereas smaller 2 mm³ structures demonstrated capillary effects but had printability and cleaning issues. Permeability results indicated that Octet performed best, followed by Isotruss, Diamond, and TPMS-Gyroid. Findings emphasize unit cell size, beam thickness, and droplet positioning as key factors in optimizing fluid dynamics for cooling, filtration, and fluid management. Full article

Objectives: Torus mandibularis (TM) is a benign bony exostosis on the lingual surface of the mandible, typically developing from the third decade of life with slow progression; its etiology remains unclear. As TM excision causes no functional or aesthetic disadvantages, its use as autologous bone graft material (e.g., for pre-implant or sinus lift augmentation) has been suggested. In this study, we investigate the prevalence and expression of TM in a southern German population with regard to age and gender. Additionally, we examine whether TM undergoes dynamic changes over time, with the hypothesis that TM may show temporal growth. Material and Methods: A retrospective analysis of CBCT scans from 210 randomly selected patients (105 males, 105 females) was performed. Patients were divided into three age groups (≤40, 41–60, ≥61 years; 70 per group), and TM was measured using OsiriX MD. For the longitudinal study, 146 CBCTs from 73 patients were compared over intervals of 2–9 years. Surface changes were assessed via 3D overlay using GOM Inspect. Results: TM was found in 30.5% of patients, and its prevalence was significantly higher in males (38%) than females (23%), with no age-related differences identified. Most TMs measured <2 mm (n = 51); only five exceeded this size. No dynamic growth was observed over time. Conclusion and Clinical Implications: TM is a common anatomical variant, more frequently detected through 3D imaging than clinical examination. In most cases, size remains minimal (<2 mm), limiting its clinical use as augmentation material in rare individual cases. Full article

The ecological environment is crucial for human survival and development. As ecological issues become more pressing, studying the spatiotemporal evolution of ecological quality (EQ) and its driving mechanisms is vital for sustainable development. This study, based on MODIS data from 2000 to 2022 and the Google Earth Engine platform, constructs a remote sensing ecological index for the Beibu Gulf Urban Agglomeration and analyzes its spatiotemporal evolution using Theil–Sen trend analysis, Hurst index (HI), and geographic detector. The results show the following: (1) From 2000 to 2010, EQ improved, particularly from 2005 to 2010, with a significant increase in areas of excellent and good quality due to national policies and climate improvements. From 2010 to 2015, EQ degraded, with a sharp reduction in areas of excellent quality, likely due to urban expansion and industrial pressures. After 2015, EQ rebounded with successful governance measures. (2) The HI analysis indicates that future changes will continue the past trend, especially in areas like southeastern Chongzuo and northwestern Fangchenggang, where governance efforts were effective. (3) EQ shows a positive spatial correlation, with high-quality areas in central Nanning and Fangchenggang, and low-quality areas in Nanning and Beihai. After 2015, both high–high and low–low clusters showed changes, likely due to ecological governance measures. (4) NDBSI (dryness) is the main driver of EQ changes (q = 0.806), with significant impacts from NDVI (vegetation coverage), LST (heat), and WET (humidity). Urban expansion’s increase in impervious surfaces (NDBSI rise) and vegetation loss (NDVI decline) have a synergistic effect (q = 0.856), significantly affecting EQ. Based on these findings, it is recommended to control construction land expansion, optimize land use structure, protect ecologically sensitive areas, and enhance climate adaptation strategies to ensure continuous improvement in EQ. Full article

Investigating land cover patterns, changes in carbon stocks, and forecasting future conditions are essential for formulating regional sustainable development strategies and enhancing ecological and environmental quality. This study centers on Guiyang, a mountainous urban area in southwestern China, to analyze the dynamic changes in land cover and their effects on carbon stocks from 2000 to 2035. A carbon stocks assessment framework was developed using a cellular automaton-based artificial neural network model (CA-ANN), the InVEST model, and the geographical detector model to predict future land cover changes and identify the primary drivers of variations in carbon stocks. The results indicate that (1) from 2000 to 2020, impervious surfaces expanded significantly, increasing by 199.73 km². Compared to 2020, impervious surfaces are projected to increase by 1.06 km², 13.54 km², and 34.97 km² in 2025, 2030, and 2035, respectively, leading to further reductions in grassland and forest areas. (2) Over time, carbon stocks in Guiyang exhibited a general decreasing trend; spatially, carbon stocks were higher in the western and northern regions and lower in the central and southern regions. (3) The level of greenness, measured by the normalized vegetation index (NDVI), significantly influenced the spatial variation of carbon stocks in Guiyang. Changes in carbon stocks resulted from the combined effects of multiple factors, with the annual average temperature and NDVI being the most influential. These findings provide a scientific basis for advancing low-carbon development and constructing an ecological civilization in Guiyang. Full article

The present study aims to investigate the multi-year effects (5 years) of individualized whole-body vibration (WBV) on locomotion, postural control, and handgrip strength in a 68-year-old man with relapse remitting multiple sclerosis (PwRRMS). The dose–response relationship induced by a single session was quantified by determining the surface electromyographic activity (sEMG) of the participant. The participant wore an orthosis to limit the lack of foot dorsiflexion in the weakest limb during walking in daily life. The gait alteration during walking was assessed at 1, 2 and 3 km/h (without the orthosis) through angle–angle diagrams by quantifying the area, perimeter and shape of the loops, and the sEMG of leg muscles was recorded in both limbs. The evaluation of postural control was conducted during upright standing by quantifying the displacement of the center of pressure (CoP). The handgrip strength was assessed by measuring the force–time profile synchronized with the sEMG activity of upper arm muscles. The participant improved his ability to walk at higher speeds (2–3 km/h) without the orthosis. There were greater improvements in the area and perimeter of angle–angle diagrams for the weakest limb (Δ = 36–51%). The sEMG activity of the shank muscles increased at all speeds, particularly in the tibialis anterior of weakest limbs (Δ = 10–68%). The CoP displacement during upright standing decreased (Δ = 40–60%), whereas the handgrip strength increased (Δ = 32% average). Over the 5-year period of intervention, the individualized WBV improved locomotion, postural control and handgrip strength without side effects. Future studies should consider the possibility of implementing an individualized WBV in PwRRMS. Full article

Nowadays, a single detection method is insufficient for comprehensively and clearly identifying both surface defects and inner defects in titanium alloys. To address this limitation, this paper proposes a titanium alloy defect detection method based on optical–acoustic image fusion. A detection system was developed to achieve comprehensive and precise inspection of titanium alloys by integrating advanced deep learning-based optical testing technology, reliable C-scan ultrasonic detection technology, and information fusion techniques. Furthermore, the PC software can output interactive fusion results and generate decision-level detection reports. The experimental results demonstrate that the surface defect detection algorithm achieves an accuracy of 99.0%, with a surface defect size measurement resolution of 0.01 mm, an internal defect size measurement resolution of 1 mm, and a positional error within 2 mm. It was found that the proposed method provides a potential solution for the practical application of inspecting surface defects and inner defects in the materials. Full article

This study investigates the thermal response and surface modification of low-carbon manganese-alloyed 20GL steel during electrolytic plasma hardening. The objective was to evaluate the feasibility of surface hardening 20GL steel—traditionally considered difficult to quench—by combining high-rate surface heating with rapid cooling in an electrolyte medium. To achieve this, a transient two-dimensional heat conduction model was developed to simulate temperature evolution in the steel sample under three voltage regimes. The model accounted for dynamic thermal properties and non-linear boundary conditions, focusing on temperature gradients across the thickness. Experimental temperature measurements were obtained using a K-type thermocouple embedded at a depth of 2 mm, with corrections for sensor inertia based on exponential response behavior. A comparison between simulation and experiment was conducted, focusing on peak temperatures, heating and cooling rates, and the effective thermal penetration depth. Microhardness profiling and metallographic examination confirmed surface strengthening and structural refinement, which intensified with increasing voltage. Importantly, the study identified a critical cooling rate threshold of approximately 50 °C/s required to initiate martensitic transformation in 20GL steel. These findings provide a foundation for future optimization of quenching strategies for low-carbon steels by offering insight into the interplay between thermal fluxes, surface kinetics, and process parameters. Full article

A comparison of two synthesis methods for depositing Au nanoparticles onto TiO₂ was performed: (1) impregnation with HAuCl₄ followed by thermal treatment in argon, and (2) magnetron sputtering from a Au disc. The obtained materials were used for acetaldehyde decomposition in a high temperature reaction chamber and ch aracterised by UV-Vis/DR, XPS, XRD, SEM, and photoluminescence measurements. The process was carried out using an air/acetaldehyde gas flow under UV or UV-Vis LED irradiation. The mechanism of acetaldehyde decomposition and conversion was elaborated by in situ FTIR measurements of the photocatalyst surface during the reaction. Simultaneously, concentration of acetaldehyde in the outlet gas was monitored using gas chromatography. All the Au/TiO₂ samples showed absorption in the visible region, with a maximum around 550 nm. The plasmonic effect of Au nanoparticles was observed under UV-Vis light irradiation, especially at elevated temperatures such as 100 °C, for Au/TiO₂ prepared by the magnetron sputtering method. This resulted in a significant increase in the conversion of acetaldehyde at the beginning, followed by gradual decrease over time. The collected FTIR spectra indicated that, under UV-Vis light, acetaldehyde was strongly adsorbed onto Au/TiO₂ surface and formed crotonaldehyde or aldol. Under UV, acetaldehyde was mainly adsorbed in the form of acetate species. The plasmonic effect of Au nanoparticles increased the adsorption of acetaldehyde molecules onto TiO₂ surface, while reducing their decomposition rate. The increased temperature of the process enhanced the decomposition of the acetaldehyde. Full article

Background: Post-traumatic corneal wounds that require suturing are quite common; they reduce corneal transparency and cause corneal distortion, leading to corneal astigmatism and higher-order aberrations. Excimer laser treatment can be a potentially beneficial intervention for such wounds. The observation aimed to evaluate the effectiveness of topography-guided custom ablation treatment (TCAT) in patients with corneal injuries. Methods: This observation included three patients with corneal penetrating trauma (full-thickness corneal scar) and one patient with corneal blunt trauma, i.e., a non-penetrating injury with corneal laceration (partial-thickness corneal scar). This cohort study was conducted from July 2021 to August 2023. After first-stage treatment (stabilization of the post-traumatic visual defect confirmed by refraction and topography examination, corneal healing, and improvement of the corneal scar), the patients underwent the second-stage treatment, i.e., TCAT with a 20 to 45 s application of mitomycin C solution to avoid haze induction. After TCAT, the uncorrected distance visual acuity (UDVA) and best-corrected distance visual acuity (BCVA) were measured. Refractive astigmatism was assessed using autorefractometry. Topographic astigmatism was analyzed using corneal topography and pachymetry. The root mean square (RMS) of the higher-order aberration was calculated using Zernike coefficients. The patients’ corneal healing and refractive changes were monitored. Results: All patients were monitored for corneal healing and refractive changes and underwent the same second-stage treatment, which utilized TCAT to regularize the corneal surface and reduce higher-order aberrations (HOAs). The UDVA of patients 1, 2, 3 and 4 improved by 3, 7.5, 4 and 6 rows (Snellen chart), respectively. The resultant UDVA was 1.0, 0.9, 0.7 and 1.2, while BCVA was 1.0, 1.2, 1.0, and 1.5, respectively. Conclusions: TCAT regularized the patients’ corneal surfaces and reduced HOAs. We, therefore, conclude that TCAT may be a beneficial second-stage treatment for corneal trauma-induced astigmatism. Full article

The structural analysis of shelterbelts forms the foundation of their planning and management, yet the scientific and effective quantification of shelterbelt structures requires further investigation. This study developed an innovative heterogeneous analytical framework, integrating three key methodologies: the LeWoS algorithm for wood–leaf separation, TreeQSM for structural reconstruction, and 3D alpha-shape spatial quantification, using terrestrial laser scanning (TLS) technology. This framework was applied to three typical farmland shelterbelts in the Ulan Buh Desert oasis, enabling the first precise quantitative characterization of structural components during the leaf-on stage. The results showed the following to be true: (1) The combined three-algorithm method achieved ≥90.774% relative accuracy in extracting structural parameters for all measured traits except leaf surface area. (2) Branch length, diameter, surface area, and volume decreased progressively from first- to fourth-order branches, while branch angles increased with ascending branch order. (3) The trunk, branch, and leaf components exhibited distinct vertical stratification. Trunk volume and surface area decreased linearly with height, while branch and leaf volumes and surface areas followed an inverted U-shaped distribution. (4) Horizontally, both surface area density (Scd) and volume density (Vcd) in each cube unit exhibited pronounced edge effects. Specifically, the Scd and Vcd were greatest between 0.33 and 0.60 times the shelterbelt’s height (H, i.e., mid-canopy). In contrast, the optical porosity (Op) was at a minimum of 0.43 H to 0.67 H, while the volumetric porosity (Vp) was at a minimum at 0.25 H to 0.50 H. (5) The proposed volumetric stratified porosity (Vsp) metric provides a scientific basis for regional farmland shelterbelt management strategies. This three-dimensional structural analytical framework enables precision silviculture, with particular relevance to strengthening ecological barrier efficacy in arid regions. Full article

This study examined the eco-friendly synthesis of zinc oxide (ZnO) nanoparticles using Cladophora glomerata extracts as reducing and stabilizing agents, comparing zinc acetate and zinc chloride precursors for biomedical and environmental applications. Zinc acetate-synthesized ZnO nanoparticles showed a significant absorption peak around 320–330 nm, indicating stable, quasi-spherical ZnO nanoparticles with a narrow size distribution, primarily around 100 nm. Zeta potential measurements revealed a value of −25 mV for these particles, suggesting moderate colloidal stability. XRD analysis confirmed a highly crystalline hexagonal wurtzite structure for zinc acetate-derived ZnO, and SEM images supported a proper microstructure with approximately 2 µm particle size. FTIR analysis indicated higher-quality ZnO from zinc acetate due to the absence of moisture and hydroxyl groups. Conversely, zinc chloride-derived ZnO particles displayed a broader absorption spectrum around 370 nm, indicative of significant aggregation. Their narrower zeta potential distribution around +10 mV suggested diminished colloidal stability and a heightened aggregation tendency. While a peak around 100 nm was observed, many particles exceeded 1000 nm, reaching up to 10,000 nm. XRD results showed that zinc chloride adversely affected crystallinity, and SEM analysis indicated smaller particles (approx. 1 µm). FTIR analysis demonstrated that zinc chloride samples retained hydroxyl groups. Both zinc acetate- and zinc chloride-derived ZnO nanoparticles produced notable inhibitory zones against Gram-positive (L. monocytogenes, S. aureus) and specific Gram-negative bacteria (E. coli, K. pneumoniae). Zinc acetate-derived ZnO showed a 21 mm inhibitory zone against P. vulgaris, while zinc chloride-derived ZnO showed a 10.1 mm inhibitory zone against C. albicans. Notably, zinc chloride-derived ZnO exhibited broad-spectrum antimicrobial activity. MIC readings indicated that zinc acetate-derived ZnO had better antibacterial properties at lower concentrations, such as 3.125 µg/mL against L. monocytogenes. These findings emphasize that the precursor material selection critically influences particle characteristics, including optical properties, surface charge, and colloidal stability. Full article

Titanium (Ti) alloys, renowned for their exceptional physicochemical properties and high biocompatibility, are widely utilized in orthopedic and dental implants; however, their lack of intrinsic antimicrobial activity significantly increases the risk of implant-associated infections, often leading to severe complications and implant failure. Developing antimicrobial coatings on Ti implants is therefore a promising strategy. In this study, tannic acid (TA) coatings were deposited by immersing Ti alloy surfaces—beforehand activated by low-temperature oxygen plasma—in TA solutions at 2, 5, and 8 wt%. Coatings were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), water contact angle (WCA) measurements, and Folin–Ciocalteu release assays, and their cytocompatibility and antimicrobial performance were assessed in vitro. Surface characterization confirmed the formation of uniform TA layers, and WCA measurements indicated enhanced hydrophilicity relative to unmodified Ti (82.0° ± 3.6°), with values decreasing as TA concentration increased (from 35.2° ± 3.2° for 2% TA to 26.6° ± 2.8° for 8% TA). TA release profiles exhibited an initial burst followed by sustained diffusion, with 5% and 8% coatings releasing significantly more TA than 2% coatings. Coatings containing ≥ 5% TA demonstrated bactericidal activity—achieving > 2-log₁₀ reductions—against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, and also showed inhibitory effects against Candida albicans. Importantly, all coatings remained cytocompatible with NIH/3T3 fibroblasts, and the released tannic acid hydrolysis products (particularly gallic acid) enhanced their proliferation. These findings indicate that plasma-activated titanium surfaces coated with ≥5 wt% tannic acid impart broad-spectrum antimicrobial efficacy and hold potential to reduce implant-associated infections and improve long-term outcomes in orthopedic and dental applications. Full article