Search Results (176)

Removing orthodontic brackets often presents clinical challenges, as it may cause patient discomfort, bracket fracture, or enamel damage resulting from strong adhesive bonds. Various techniques have been proposed to facilitate safer and more efficient debonding. Among them, laser-assisted methods have gained attention for their potential to minimize mechanical stress and improve patient comfort. The main objective of this study was to evaluate the effect of an erbium-doped yttrium–aluminum–garnet (Er:YAG) laser as an alternative to traditional mechanical methods for removing metal and ceramic orthodontic brackets. Materials and Methods: Thirty-six extracted premolars were prepared for bonding metal or ceramic brackets using a light-cure adhesive system. The control group consisted of six ceramic and six metal brackets removed with conventional orthodontic pliers. In the experimental groups, brackets were debonded using the Er:YAG laser (2940 nm, 0.6 mm spot size, 150 mJ; 15 Hz; (2.25 W) with an H14 handpiece. Irradiation time was recorded for each method, and teeth were rescanned to measure the surface area and volume of the crowns before and after bracket removal. Data were analyzed using one-way ANOVA and Tukey’s HSD test (p < 0.05). Scanning electron microscopy (SEM) was used for surface analysis. Results: A significant difference in debonding time (p = 0.001) was observed between the laser and traditional methods. The laser group took 52.5 s for metal and 56.25 s for ceramic brackets, compared to 1.05 s (metal) and 0.64 s (ceramic) in the traditional group. A significant difference in remaining cement volume was noted (p = 0.0002), but no differences were found between metal and ceramic brackets with laser removal. Conclusions: Er:YAG laser-assisted debonding is safe and minimally invasive but more time-consuming and costly than conventional methods, showing no improvement in clinical efficiency under current parameters. Full article

Tunnel construction in karst formations faces significant geological uncertainties, which pose challenges for quantifying construction risks using traditional deterministic methods. This paper proposes a probabilistic reliability analysis framework that integrates the Stochastic Finite Element Method (SFEM), a Radial Basis Function Neural Network (RBFNN) surrogate model, and Monte Carlo Simulation (MCS) method. The probability distributions of rock mass mechanical parameters and karst geometric parameters were established based on field investigation and geophysical prospecting data. The accuracy of the finite element model was verified through existing physical model tests, with the lateral karst condition identified as the most unfavorable scenario. Limit state functions with control indices, including tunnel crown settlement, invert uplift, ground surface settlement and convergence, were defined. A high-precision surrogate model was constructed using RBFNN (average R² > 0.98), and the failure probabilities of displacement indices were quantitatively evaluated via MCS (10,000 samples). Results demonstrate that the overall failure probability of tunnel construction is 3.31%, with the highest failure probability observed for crown settlement (3.26%). Sensitivity analysis indicates that the elastic modulus of the disturbed rock mass and the clear distance between the karst cavity and the tunnel are the key parameters influencing deformation. This study provides a probabilistic risk assessment tool and a quantitative decision-making basis for tunnel construction in karst areas. Full article

Objective: This in vitro study quantitatively compared the time-dependent remineralization potential of three professional agents on artificially induced enamel lesions using Scanning Electron Microscopy (SEM) and energy-dispersive X-ray analysis (EDX). Methods: Sixty extracted sound molars were randomly assigned to three groups (number = 20): G_CPP-ACP, treated with casein phosphopeptide–amorphous calcium phosphate; G_Zn-HA, treated with zinc-hydroxyapatite; and G_F-ACP, treated with fluoridated amorphous calcium phosphate. The crown of each tooth was divided into three areas: one represented the control (CTRL, sound enamel), one underwent demineralization (DEMIN, demineralized enamel), and the third one was at first demineralized and then treated with a remineralizing agent, allowing intra-sample comparison. Artificial lesions were produced by immersion in 0.1 M lactic acid (72 h). Groups were subdivided according to remineralization time (7, 14, 21, and 28 days). Samples underwent daily treatment under a pH-cycling regimen. Surface morphology and Ca/P ratios were evaluated by SEM-EDX, and data were statistically analyzed (p < 0.05). Results: All agents promoted a progressive increase in Ca/P ratio over time, confirming a time-dependent remineralization effect. At day 7, G_Zn-HA showed higher Ca/P values, but from day 14 onward, G_F-ACP produced significantly greater mineral gain than the other groups (p < 0.05). By day 21, G_F-ACP reached Ca/P values approaching CTRL, while G_CPP-ACP and G_Zn-HA remained at lower levels, reaching a plateau respectively at 21 and 14 days. SEM observations supported these findings: G_CPP-ACP and G_Zn-HA showed partial surface recovery, whereas G_F-ACP exhibited a compact, homogeneous enamel-like structure at 28 days. Conclusions: All tested agents demonstrated time-dependent remineralization, enhanced with prolonged exposure, suggesting that the time of application represents a key factor for clinical success. Full article

Understory vegetation, particularly dwarf bamboo, plays a crucial role in regulating forest nutrient cycles by intercepting litter and altering decomposition processes, yet its overall impacts remain understudied and insufficiently quantified. This study employs a combination of field surveys and decomposition bag experiments to investigate how understory dwarf bamboo (Fargesia decurvata) alters the spatial–temporal patterns of leaf litter production and decomposition. We found that the dwarf bamboo intercepted more than 25% of canopy litterfall, altering its spatial distribution and reducing decomposition efficiency in the bamboo crown (BC). Leaf trait-decomposition relationships differed strongly across habitats, being positive for saturated fresh weight (SFW), leaf thickness (LFT), and leaf area (LA) and dry weight (DW) in bamboo habitats but weaker in the bamboo-free habitat (NB). Potassium release was significantly higher in the BC treatment, whereas carbon release showed the opposite trend. In contrast, nitrogen and phosphorus exhibited net enrichment across all treatments, with phosphorus enrichment being slower in BC than in bamboo-covered ground surface (BG) and NB. Our results demonstrate that the understory dwarf bamboo reshapes the spatial distribution of litter and nutrient release dynamics during decomposition, resulting in element-specific nutrient release patterns. These findings provide mechanistic insights into how understory dwarf bamboo mediates nutrient cycling dynamics in forest communities. Full article

Background: Dental implants are widely used to replace missing teeth, particularly in aesthetically sensitive areas. The implant’s macrogeometry is crucial for ensuring primary stability and successful osseointegration. Internal conical connections and reactive surfaces on implants have shown positive outcomes in tissue and bone stability. In response, a hybrid conical dental implant was designed to address a variety of clinical scenarios. Materials and Methods: This pilot study evaluated the performance of the hybrid conical implant using histological and micro-CT analysis in a preclinical model with immediate loading. Five implants were placed in a mongrel dog, and histomorphometric and micro-CT assessments were performed after 60 days of healing. Results: Analysis showed a high degree of osseointegration, with BIC at 61.56% and BT/TV at 77%. Micro-CT confirmed these findings, with nBIC at 82.20%. Vertical measurements indicated stable crestal bone. Peri-implant tissue displayed organized supracrestal connective tissue, without signs of inflammation or bone saucerization. Polarized light microscopy revealed collagen fibers in perpendicular and oblique orientations around the abutment, suggesting mechanical integration and biological sealing despite the absence of a prosthetic crown. Conclusions: Within the limitations of this exploratory study with one animal study, the hybrid conical implant showed favorable biological and structural responses under immediate loading. These preliminary findings provide useful insights for the refinement of implant design, although further investigations in larger preclinical and clinical studies are required before clinical applicability can be confirmed. Full article

Accurate measurement of tree height and diameter at breast height (DBH) is essential for forest inventory, biomass estimation, and habitat assessment but remains challenging in structurally complex, multi-layered forests. This study evaluates the accuracy and operational feasibility of Unmanned Aerial Vehicle (UAV) LiDAR and Mobile Laser Scanning (MLS) for estimating tree height and DBH in such stands with a diverse structure in the Romanian Carpathians. Field measurements from six plots encompassing mixed-species (Fagus sylvatica L., Abies alba Mill., Picea abies (L.) H.Karst.) and single-species (Picea abies) stands were compared against UAV- and MLS-derived metrics. MLS delivered near-inventory-grade DBH accuracy across all species (R² up to 0.98) and reliable height estimates for intermediate and suppressed trees, while UAV LiDAR consistently underestimated tree height, especially in dense, multi-layered stands (R² < 0.2 in mixed plots). Voxel-based occlusion analysis revealed that over 93% of area under canopy and interior crown volume was captured only by MLS, confirming its dominance below the canopy, whereas UAV LiDAR primarily delineated the outer canopy surface. Species traits influenced DBH accuracy locally, but structural complexity and canopy layering were the main drivers of height underestimation. We recommend hybrid UAV–MLS workflows combining UAV efficiency for canopy-scale mapping with MLS precision for stem and sub-canopy structure. Future research should explore multi-season acquisitions, improved SLAM robustness, and automated data fusion to enable scalable, multi-layer forest monitoring for carbon accounting, biodiversity assessment, and sustainable forest management decision making. Full article

The ecological impact of crown-of-thorns starfish (CoTS; Acanthaster spp.) on coral reefs is intrinsically linked to their feeding behaviour. Management thresholds designed to mitigate coral loss driven by elevated densities of crown-of-thorns starfish rely on accurate estimates of individual feeding rates. In this study, structure-from-motion photogrammetry and intensive tracking of adult Pacific CoTS over an extended survey period were used to generate three-dimensional, high-resolution estimates of daily feeding rates. Our findings revealed substantial variation in the areal extent of coral consumed, both across consecutive days and among individuals. Notably, CoTS did not feed consistently; feeding occurred on 65% of observation days, with 2–3 days periods of inactivity common. Despite this variability, mean daily feeding rates aligned with previous studies (1.35 coral colonies d⁻¹; 198.4 cm² day⁻¹ planar area, and 998.83 cm² day⁻¹ three-dimensional surface area). Across all tracked individuals (n = 8), feeding was recorded on 17 coral genera; however, Acropora alone accounted for 51% of colonies consumed and contributed 82% of the total three-dimensional surface area ingested during the survey period. This highlights the disproportionately large feeding yield derived from Acropora-dominated diets and raises important questions about how future declines in Acropora cover may impact CoTS feeding success and energetic intake. Full article

To address the problems of traditional methods that rely on destructive sampling, the poor adaptability of fixed equipment, and the susceptibility of single-view angle measurements to occlusions, a non-destructive and portable device for three-dimensional phenotyping and biomass detection in lettuce was developed. Based on the Structure-from-Motion Multi-View Stereo (SFM-MVS) algorithms, a high-precision three-dimensional point cloud model was reconstructed from multi-view RGB image sequences, and 12 phenotypic parameters, such as plant height, crown width, were accurately extracted. Through regression analyses of plant height, crown width, and crown height, and the R² values were 0.98, 0.99, and 0.99, respectively, the RMSE values were 2.26 mm, 1.74 mm, and 1.69 mm, respectively. On this basis, four biomass prediction models were developed using Adaptive Boosting (AdaBoost), Support Vector Regression (SVR), Gradient Boosting Decision Tree (GBDT), and Random Forest Regression (RFR). The results indicated that the RFR model based on the projected convex hull area, point cloud convex hull surface area, and projected convex hull perimeter performed the best, with an R² of 0.90, an RMSE of 2.63 g, and an RMSEn of 9.53%, indicating that the RFR was able to accurately simulate lettuce biomass. This research achieves three-dimensional reconstruction and accurate biomass prediction of facility lettuce, and provides a portable and lightweight solution for facility crop growth detection. Full article

Background: Monolithic zirconia has attracted considerable interest in dentistry due to its favorable physical and mechanical properties, making it a promising alternative for crown fabrication. Nonetheless, a standardized finishing protocol for this material has yet to be established. Objective: This study aimed to evaluate the surface characteristics and in vitro biofilm formation of zirconia finished by either polishing or glazing. Methods: A total of 72 zirconia specimens were fabricated and divided into control, glazing, and polishing groups. Surface analysis included roughness, wettability, and surface free energy. Microbiological analysis included CFU (colony-forming units per mL) counts, microbial adhesion at 2, 4, 6, and 8 h, biofilm biovolume, and qualitative biofilm assessment via scanning electron microscopy (sEm). Results: The glazing group showed significantly greater roughness than the polishing (p = 0.006) and control (p = 0.016) groups, along with a lower contact angle (polishing—p = 0.002; control—p < 0.001) and higher surface energy (polishing—p = 0.005; control—p < 0.001). No significant differences were observed in CFU counts for the tested microorganisms (C. albicans, p = 0.158; L. casei, p = 0.610; S. mutans, p = 0.904). Regarding microbial adhesion, the polishing group showed a smaller biofilm-covered area compared to the control group for both total biofilm (p = 0.008) and viable biofilm (p = 0.005). no statistically significant difference was observed in biofilm biovolume (p = 0.082). Conclusions: These findings suggest that, despite the surface differences among the groups, biofilm formation was not significantly affected. Full article

With the rapid advancement of urban underground space development, shield tunnel construction has seen a significant increase. However, at the initial launching stage of shield tunnels in shallow-buried weak strata, engineering risks such as face instability and sudden surface settlement frequently occur. At present, there are relatively few studies on the reinforcement technology of the initial section of shield tunnel in shallow soft ground and the evolution law of ground disturbance. This study takes the launching section of the Guanggang New City depot access tunnel on Guangzhou Metro Line 10 as the engineering background. By applying MIDAS/GTS numerical simulation, settlement monitoring, and theoretical analysis, the reinforcement technology at the tunnel face, the spatiotemporal evolution of ground settlement, and the mechanism of soil disturbance transmission during the launching process in muddy soil layer are revealed. The results show that: (1) the reinforcement scheme combining replacement filling, high-pressure jet grouting piles, and soil overburden counterpressure significantly improves surface settlement control. The primary influence zone is concentrated directly above the shield machine and in the forward excavation area. (2) When the shield machine reaches the junction between the reinforced and unreinforced zones, a large settlement area forms, with the maximum ground settlement reaching −26.94 mm. During excavation in the unreinforced zone, ground deformation mainly occurs beneath the rear reinforced section, with subsidence at the crown and uplift at the invert. (3) The transverse settlement trough exhibits a typical Gaussian distribution and the discrepancy between the measured maximum settlement and the numerical and theoretical values is only 3.33% and 1.76%, respectively. (4) The longitudinal settlement follows a trend of initial increase, subsequent decrease, and gradual stabilization, reaching a maximum when the excavation passes directly beneath the monitoring point. The findings can provide theoretical reference and engineering guidance for similar projects. Full article

Phalaenopsis is a widely cultivated ornamental plant of considerable economic value worldwide. However, traditional growing medium, sphagnum moss, is limited and non-renewable. It also decomposes slowly and is prone to environmental issues. Therefore, there is an urgent need to identify more environmentally friendly and efficient alternatives. Biochar, a sustainable material with excellent physical and chemical properties, has been recognized as an effective promoter of plant growth. In this study, we investigated the influence of biochar derived from three raw materials (corn straw, bamboo, and walnut) mixed1 with coconut shell at ratios of 1:2, 1:10, and 4:1, on the growth of Phalaenopsis ‘Big Chili’. Over a 150-day controlled experiment, we evaluated multiple growth parameters, including plant height, crown width, total root length, total projected area, total surface area, and root volume. Compared to the traditional growing medium, the optimal biochar-coconut shell mixture (maize straw biochar: coconut shell = 1:2) increased plant height and crown width by 7.55% and 6.68%, respectively. Root metrics improved substantially, with total root length increasing by 10.96%, total projected area by 22.82%, total surface area by 22.14%, and root volume by 38.49%. Root biomass in the optimal treatment group increased by 42.47%, while aboveground and belowground dry weights increased by 6.16% and 77.11%, respectively. These improvements were closely associated with favorable substrate characteristics, including low bulk density, high total and water-holding porosity, moderate aeration, and adequate nutrient availability. These findings demonstrate that substrate characteristics critically influence plant performance and that biochar–coconut shell mixtures, particularly at a 1:2 ratio, represent a viable and sustainable alternative to sphagnum moss for commercial cultivation of Phalaenopsis. Full article

Wildfires impact forest ecosystems, affecting tree survival and physiological responses. This study explored the effects of surface fires on Pinus densiflora and Quercus variabilis, assessing mortality, internal injuries, and canopy health. By 2024, P. densiflora had an 18.0% mortality rate, whereas Q. variabilis exhibited no crown dieback. Morphological traits, including tree height, the bark scorch index (BSI), and bark thickness, influenced fire resistance. Despite superior stand characteristics, P. densiflora showed higher mortality due to thin bark, whereas Q. variabilis maintained xylem integrity. While sonic tomography (SoT) showed no significant differences, electrical resistance tomography (ERT) detected physiological stress, with higher ERT_R and ERT_Y area ratios correlating with mortality risk. Notably, F-W-W classified trees showed elevated resistance a year before mortality, suggesting ERT as a predictive tool. ERT_R values exceeding 15.0% were associated with a 37.5% mortality rate, whereas ERT_B values below 55.0% corresponded to 42.9% mortality. Despite fire exposure, canopy responses, including chlorophyll fluorescence and photosynthetic efficiency, remained stable, indicating that the surviving trees maintained functional integrity. This study underscores ERT’s efficacy in diagnosing fire-induced stress and predicting mortality risk. The findings highlight species-specific diagnostic criteria and inform post-fire management, supporting forest resilience through the early detection of high-risk trees and improved restoration strategies. Full article

With increased electrification of new aircraft designs, cooling becomes more challenging. The most straightforward solution is to activate yet unused heat sinks available in the aircraft. The crown and cabin sidewall are such an unused area suitable for heat transfer. Here, only a thin plate separates the warm cabin from the cold exterior environment in cruise. Air used for the cooling of devices could be guided along the fuselage skin to benefit from the large heat exchanging surface. Scaling test results indicate that up to 24 kW of additional heat could be dissipated in the short term through this system in flight. Full article

This article offers the architectural definition and interpretative keys to a unique project. It is a space shared by the three main Abrahamic faiths: the Jewish, Christian and Muslim religions. Although conceptually other religions could be accommodated. Its configuration is very elementary: a cubic volume, massive and almost blind, with a cylindrical space crowned by a simple skylight. Each of the religions is based on a scratching of the interior surfaces of the space, forming the ritual areas of each of them. And towards the center of the space there are other areas of prayer and celebration that could be shared among the believers of the different religions, from the conviction that they are addressed to the same God. In this configuration there is a will of invitation, of offering to all men of good will. The article, written by the architect of this space, mentions some plastic and conceptual references that have served as inspiration for the project and its presentation is intended to fuel the debate on the possibility of this space. Full article

Forest fine fuels are a crucial component of surface fuels and play a key role in igniting forest fires. However, despite nearly 20 years of long-term prescribed burning management on Zhaobi Mountain in Xinping County, Yunnan Province, China, there remains a lack of specific quantification regarding the effectiveness of fine fuel management in Pinus yunnanensis forests. In this study, 10 m × 10 m sample plots were established on Zhaobi Mountain following one year of growth after prescribed burning. The plots were placed in a prescribed burning (PB) area and an unburned control (UB) area. We utilized indicators such as forest stand characteristics, fine fuel physicochemical properties, and potential fire behavior parameters for evaluation. The results indicate that prescribed burning at one-year intervals significantly affects stand characteristics, particularly in metrics such as crown base height, diameter breast height, and fuel load (p < 0.05). However, the physical and chemical properties of fine fuels did not show significant differences. Notably, the mean range of spread (RS) of PB fuels downhill was 43.3% lower than that of UB fuels, and the mean flaming height (FH) was 35.2% lower. The fire line intensity was <750 kW/m, categorizing it as a low-intensity fire. These findings provide data on the composition of fine fuels and the variables of fire behavior affected by prescribed burning, demonstrating that low-intensity prescribed burns can regulate fine fuels in the understory and maintain a stable regional fire risk level. Full article