Search Results (181)

Baseflow is the part of the groundwater aquifer that replenishes surface streamflow and is one of the main components of studying the interaction between groundwater and surface water. It is a key factor in maintaining the healthy development of basin ecosystems and is of great significance for promoting the sustainable utilization and scientific management of water resources. However, the understanding of runoff and baseflow in the MYRB is still unclear, and the relationship between streamflow and baseflow has not been fully grasped. At the same time, there is currently no water balance function applicable to the MYRB. In order to solve the above problems, this article uses digital filtering methods to segment the baseflow and the MRC method to construct the main recession curve. The baseflow rate of MYRB was calculated, and the water balance function applicable to MYRB was found. The results obtained are as follows: the average annual baseflow index values for different basins were 0.81, 0.76, 0.81, 0.82, 0.79, and 0.79, respectively. The fitting of the Boussinesq function, the Maillet function, and the Brutsaert and Nieber function was significantly better than the other two functions. Full article

Background: Periodontitis is linked to a range of systemic non-communicable diseases, including hepatic diseases. The aim of this study was to investigate whether periodontal health status is associated with liver cirrhosis (LC). Methods: Patients were recruited from the Department of Internal Medicine at the University Clinical Hospital “Sestre Milosrdnice” and categorized into two groups. The case group comprised patients with LC, while age-matched individuals without LC served as controls. Systemic health status was evaluated through laboratory tests, medical history, and clinical parameters, and the Model for End-Stage Liver Disease (MELD) score was calculated for each participant. A comprehensive clinical periodontal assessment was conducted, measuring bleeding on probing (BoP), probing pocket depth (PPD), gingival recession (GR), clinical attachment level (CAL), and the Periodontal Inflamed Surface Area (PISA) score. Stepwise logistic regression was employed to assess possible predictors of LC, including periodontal status. Results: A total of 100 patients were included in the analysis, consisting of 50 cases with LC and 50 controls. The mean age was 56.79 years (SD = 11.16) of participants, and 58% were male. The majority of LC cases were attributed to alcohol abuse (41/50, 82%), and the median MELD score was 16 (IQR 6–33). Comparison of the two groups revealed significantly worse clinical periodontal parameters in the LC group and a higher prevalence of periodontitis (p = 0.012). Among the 50 LC patients, 46 (92%) exhibited severe forms of periodontitis (stages III and IV). Logistic regression analysis identified alcohol consumption and the PISA score as independent predictors of LC (OR = 23.81, 95% CI 4.48–126.47, p < 0.001; OR = 1.006, 95% CI 1.003–1.01, p < 0.001, respectively). Conclusions: Within the limits of the present study, the higher prevalence of periodontal disease in the LC group suggests an association between LC and periodontitis. Full article

The research investigated the potential of five novel additively manufactured (AM) fiber-reinforced thermoplastic composite (FRTPC) configurations as alternatives for ablative thermal protection system (TPS) applications. The thermal stability and ablative behavior of ten samples developed via fused deposition modeling (FDM) three-dimensional (3D) printing out of fire-retardant thermoplastics were investigated using an in-house oxyacetylene torch bench. All samples featured an innovative internal thermal management architecture with three air chambers. Furthermore, the enhancement of thermal benefits was achieved through several approaches: ceramic coating, mechanical hybridization, or continuous fiber reinforcement. For each configuration, two samples were exposed to flame at 1450 ± 50 °C for 30 s and 60 s, respectively, with the front surface subjected to direct exposure at a distance of 100 mm during the ablation tests. Internal temperatures recorded at two back-side contact points remained below 50 °C, well under the 180 °C maximum allowable back-face temperature for TPS during testing. Continuous reinforced configurations 4 and 5 displayed higher thermal stability the lowest values in terms of thickness, mass loss, and recession rates. Both configurations showed half of the weight losses measured for the other tested configurations, ranging from approximately 5% (30 s) to 10–12% (60 s), confirming the trend observed in the thickness loss measurements. However, continuous glass-reinforced configuration 5 exhibited the lowest weight loss values for both exposure durations, benefiting from its non-combustible nature, low thermal conductivity, and high abrasion resistance intrinsic characteristics. In particular, the Al₂O₃ surface coated configuration 1 showed a mass loss comparable to reinforced configurations, indicating that an enhanced surface coat adhesion could provide a potential benefit. A key outcome of the study was the synergistic effect of the novel air chamber architecture, which reduces thermal conductivity by forming small internal air pockets, combined with the continuous front-wall fiber reinforcement functioning as a thermal and abrasion barrier. This remains a central focus for future research and optimization. Full article

The ablation process of a silica fiber-reinforced polymer (SiFRP) composite under aerodynamic heating and a shear environment was investigated by experiments and numerical study. The flat plate samples were tested in an arc jet wind tunnel under heat flux and pressure ranging from 107 W/cm² at 2.3 kPa to 1100 W/cm² at 84 kPa. The heating surface experiences shear as high as 1900 Pa. The in-depth thermal response and ablating surface temperature of the specimens are measured during ablation. According to the ablation experimental results, a multi-layer ablation model was established that accounts for the effects of carbon deposition, investigating the thermophysical properties of the ablation deposition layer. The accuracy of the proposed ablation model was evaluated by comparing the calculated and experimental surface ablation recession and internal temperature of a silica–phenolic composite under steady-state ablation. Carbon–silica reaction heat is the important endothermic mechanism for silica-reinforced composites. The research provides valuable reference for understanding the ablative thermal protection mechanism of silicon–phenolic composites in a high shear environment. Full article

This study investigates self-pulsation phenomena in a liquid-centered swirl coaxial injector with a recess length of 4 mm, under varying liquid flow conditions, using numerical simulations. The simulations focused on analyzing spray patterns, pressure oscillations, and dominant frequency characteristics, and the results were compared with previous experimental data. Self-pulsation, observed at liquid flow rates of 60%, 90%, and 100% of nominal values, generated distinctive periodic oscillations in the spray pattern, forming “neck” and “shoulder” breakup structures that resemble a Christmas tree. Surface waves induced by Kelvin-Helmholtz and Rayleigh-Taylor instabilities were identified at the gas-liquid interface, contributing to enhanced atomization and reduced spray breakup length. FFT analysis of the pressure oscillations highlighted a match in trends between simulation and experimental data, although variations in dominant frequency magnitudes arose due to the absence of manifold space in simulations, confining oscillations and slightly elevating dominant frequencies. Regional analysis revealed that interactions between the high-speed gas and liquid film in the recess region drive self-pulsation, leading to amplified pressure oscillations throughout the injector’s internal regions, including the gas annular passage, tangential hole, and gas core. These findings provide insights into the internal flow dynamics of swirl coaxial injectors and inform design optimizations to control instabilities in liquid rocket engines. Full article

Background/Objectives: Gingival recession poses significant challenges in periodontal therapy, particularly in procedures aimed at achieving predictable root coverage and long-term stability of grafts. Conditioning of the root surface plays a crucial role in improving biomaterial adhesion and facilitating periodontal regeneration. This in vitro study aimed to evaluate the morphological and microroughness alterations of root cementum following different mechanical and chemical conditioning protocols commonly used in mucogingival surgery. Methods: Forty extracted human single-rooted teeth were randomly allocated into eight groups: untreated control, mechanical scaling alone, and scaling combined with ethylenediaminetetraacetic acid (EDTA), citric acid, phosphoric acid, tetracycline, doxycycline, or saline. Surface roughness was measured using contact profilometry, while structural modifications were analyzed via scanning electron microscopy. Results: Statistically significant intergroup differences (p < 0.05) were observed. Baneocin treatment produced the most conservative changes, with limited surface roughness and minimal structural alteration, whereas phosphoric acid, tetracycline, and EDTA caused pronounced demineralization and surface porosity. Citric acid and doxycycline induced moderate alterations, with partial preservation of cementum integrity. The null hypothesis assuming no surface or morphological changes was rejected. Conclusions: These findings indicate that low-aggressiveness agents may achieve an optimal balance between surface decontamination and cementum preservation, which is critical for enhancing graft integration and improving clinical outcomes in root coverage surgery. Full article

Background: Treatment of gingival recessions starts from an accurate diagnosis considering both periodontal tissue status and adjacent exposed dental tissues. Based on current scientific evidence and the authors’ clinical experience, a decisional scheme has been proposed for the management of gingival recession defects, with or without non-carious cervical lesions, taking into account gingival thickness and interproximal attachment levels. To illustrate its practical application, a series of representative clinical cases is presented, documenting the rationale and outcomes of the therapeutic decisions. Methods: According to the 2017 World Workshop Classification of Periodontal and Peri-Implant Diseases and Conditions, the gingival recession defect classifications have been used to build up a decision-making therapeutic process. Combined periodontal and restorative treatments in presence or absence of dental lesions have been performed. Results: In case of an identifiable cemento-enamel junction (CEJ) with or without non-carious cervical lesions (class A+ and class A−, respectively) and absence of interproximal attachment loss (RT1), flap approaches alone or in combination with connective tissue graft (CTG) were suggested. In case of an unidentifiable CEJ without cervical lesion (class B−), flap approaches alone were proposed in presence of adequate residual keratinized tissue (KT) and absence of interproximal attachment loss (RT1); if KT is extremely reduced, flap approaches + CTG may be performed. If the unidentifiable CEJ is associated with cervical lesions involving both root and crown surfaces (class B+), the combined restorative–periodontal treatment results as the most indicated approach. The adjunctive use of CTG should be also considered in presence of interproximal attachment loss (RT2 and RT3) and reduced gingival thickness (<1 mm). Conclusions: The proposed decisional scheme could be useful to address the clinicians during the decision-making process in the treatment of gingival recessions. Full article

Background: Gingival recession is a common condition involving apical displacement of the gingival margin, leading to root surface exposure and associated complications such as dentin hypersensitivity and root caries. Among the most effective treatment options are the tunneling technique (TUN) and the coronally advanced flap (CAF), both combined with connective tissue grafts (CTGs). This study aimed to evaluate and compare the clinical outcomes of TUN + CTG and CAF + CTG in terms of root coverage and keratinized tissue width (KTW) over a 6–12-month follow-up. Methods: A randomized, double-blind clinical trial was conducted following CONSORT guidelines (ClinicalTrials.gov ID: NCT06228534). Participants were randomly assigned to receive either TUN + CTG or CAF + CTG. Clinical parameters, including gingival recession depth (REC) and KTW, were assessed at baseline as well as 6 months and 12 months postoperatively using a calibrated periodontal probe. Statistical analysis was performed using descriptive statistics and linear mixed models to compare outcomes over time, with a significance level set at 5%. Results: Both techniques demonstrated significant clinical improvements. At 6 months, mean root coverage was 100% in CAF + CTG cases and 97% in TUN + CTG cases, while complete root coverage (REC = 0) was observed in 100% and 89% of cases, respectively. At 12 months, root coverage remained stable, at 99% in the CAF + CTG group and 97% in the TUN + CTG group. KTW increased in both groups, with higher values observed in the CAF + CTG group (3.53 mm vs. 3.11 mm in TUN + CTG at 12 months). No significant postoperative complications were reported. Conclusions: Both TUN + CTG and CAF + CTG are safe and effective techniques for treating RT1 and RT2 gingival recession, offering high percentages of root coverage and increased KTW. While CAF + CTG achieved slightly superior coverage and tissue gain, the TUN was associated with better aesthetic outcomes and faster recovery, making it a valuable alternative in clinical practice. Full article

This study presents a predictive model for the surface deterioration of construction materials exposed to climatic conditions. The model is applied to Santa Pudia calcarenite, the primary construction material used in the heritage buildings of Granada, Spain. Input data on material recession was obtained by using photogrammetric observations. Deterioration was measured in three heritage buildings located in different climatic zones. The methodology proposed enables the deterioration rate of building materials under specific climate conditions to be estimated by exclusively using photogrammetric data. The method was also validated in laboratory tests. The results can be applied to structural analysis and the long-term assessment of cultural heritage vulnerability in the context of future climate change. Notably, the findings indicate that in the case of Santa Pudia calcarenite, global warming slows down the deterioration process. Full article

During the operation of a solid rocket motor, the nozzle, which is a key component, is subjected to extreme conditions, including high temperatures, high-speed gas flow, and discrete-phase particles. For composite nozzles incorporating a carbon/carbon (C/C) throat liner and a carbon/phenolic expansion section, thermochemical ablation and the formation of ablation steps during the ablation process significantly hinder nozzle performance and engine operational stability. In this study, the fluid and solid domains and the physicochemical interactions between them during nozzle operation were analyzed. An innovative thermochemical ablation model for composite nozzles was developed to account for wall recession. The coupled model covered multi-component gas flow, heterogeneous chemical reactions on the nozzle surface, structural heat transfer, variations in material parameters induced by carbon/phenolic pyrolysis, and the dynamic recession process of the nozzle profile due to ablation. The model achieved coupling between gas flow, heterogeneous reactions, and structural heat transfer through interfacial mass and energy balance relationships. Based on this model, the distribution of the nozzle’s thermochemical ablation rate was analyzed to investigate the mechanisms underlying ablation step formation. Furthermore, detailed calculations and analyses were performed to determine the effects of the gas pressure, temperature, H₂O concentration, and aluminum concentration in the propellant on the ablation rate of the throat liner and the thickness of the ablation steps. This study provides a theoretical foundation for the thermal protection design and performance optimization of composite nozzles, improving the reliability and service life of solid rocket motor nozzles and advancing technological development. Full article

Mountain regions are particularly sensitive and vulnerable to the impacts of climate change. Over the past three decades, mountain temperatures have risen significantly faster than those in lowland areas. The Hindu Kush–Karakoram–Himalaya region, often referred to as the “water tower of Asia”, is the largest freshwater source outside the polar regions. However, it is currently undergoing cryospheric degradation as a result of climatic change. In this study, the Normalized Difference Glacier Index (NDGI) was calculated using Landsat and Sentinel satellite images. The results revealed that glaciers in Chitral, located in the Eastern Hindu Kush Mountains of Pakistan, lost 816 km² (31%) of their total area between 1992 and 2022. On average, 27 km² of glacier area was lost annually, with recession accelerating between 1997 and 2002 and again after 2007. Satellite analyses also indicated a significant increase in both maximum (+7.3 °C) and minimum (+3.6 °C) land surface temperatures between 1992 and 2022. Climate data analyses using the Mann–Kendall test, Theil–Sen Slope method, and the Autoregressive Integrated Moving Average (ARIMA) model showed a clear increase in air temperatures from 1967 to 2022, particularly during the summer months (June, July, and August). This warming trend is expected to continue until at least 2042. Over the same period, annual precipitation decreased, primarily due to reduced snowfall in winter. However, rainfall may have slightly increased during the summer months, further accelerating glacial melting. Additionally, the snowmelt season began consistently earlier. While initial glacier melting may temporarily boost water resources, it also poses risks to communities and economies, particularly through more frequent and larger floods. Over time, the remaining smaller glaciers will contribute only a fraction of the former runoff, leading to potential water stress. As such, monitoring glaciers, climate change, and runoff patterns is critical for sustainable water management and strengthening resilience in the region. Full article

The deterioration of stone materials due to atmospheric factors is a growing global concern, affecting the integrity and preservation of numerous UNESCO World Heritage Sites around the world. This study provides an estimate of the long-term impact of the climate on the degradation of carbonate stone materials in the UNESCO site of Matera, in southern Italy. Focusing on Gravina calcarenite, a lithotype susceptible to weathering, the research integrates satellite-derived precipitation data from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) with a dose-response model. The method involves the calibration of CHIRPS precipitation records against ground-based meteorological data, and the use of year-specific recession coefficients K_y dynamically computed as a function of atmospheric CO₂ concentration and temperature. These coefficients were applied within a Lipfert-based equation to estimate annual surface recession from 1981 to 2040 (near future). The results reveal a continuous increase in surface degradation over time, with the cumulative material loss reaching approximately 0.75 mm by 2040. These findings underscore the relevance of climate-responsive models in estimating stone decay and provide a critical basis for adaptive conservation planning. Incorporating future climate projections into risk assessments is essential for the sustainable preservation of carbonate-based cultural heritage exposed to atmospheric and hydrological stressors. Full article

Guangdong, Fujian, and Zhejiang (GFZ), located on China’s southeast coast, have long been economically active and rapidly growing provinces in China. However, the rising energy consumption in these provinces poses a major challenge to their carbon emissions reduction. Due to the spatial variation in the natural environment and socio-economic activities, energy carbon emissions (ECEs) and their reduction may vary among counties. The matter of scientifically formulating localized carbon reduction paths has therefore become a critical issue. This study proposed a novel path analysis framework based on exploring spatiotemporal heterogeneity using a spatiotemporal statistic model (i.e., spatiotemporal weighted regression). The path’s learning procedure was based on linking the changes in the amount of ECEs to the shifts in dominant factors, which were detected through local significance tests on the coefficients of STWR. To verify its effectiveness, we conducted a county-level empirical study considering four drivers (i.e., population (P), impervious surfaces (I), the proportion of secondary industry (manufacturing, M), and the proportion of tertiary industry (services, S)) in GFZ from 2014 to 2021. The ECEs show two different trends that may be affected by the COVID-19 pandemic and economic recession; hence, we divided them into two periods: an active period (2014–2018) and a stable period (2018–2021). Many interpretable paths and their occurrences were derived from our results, including the following: (1) P and S showed higher sensitivity to the changes in ECEs compared with I and M. Most counties (more than 50%) were dominated by P, but the dominator P may shift to I, M, and S during the active period. Many S-dominated counties reverted to being P-dominated ones during the stable period. (2) For the active period, the two most significant paths, M⁺ → S⁻ and M⁺ → P⁺ (+/− denotes positive or negative impacts of dominated driver), reduced ECEs by about 7.747 × 10⁵ tons and 3.145 × 10⁵ tons, respectively. Meanwhile, the worst path, S⁺ → P⁺, increased ECEs by nearly 1.186 × 10⁶ tons. (3) For the stable period, the best path (S⁺ → I⁺) significantly reduced ECEs by 1.122 × 10⁶ tons, while the worst two paths, M⁻ → P⁺ and I⁺ → P⁺, increased ECEs by 1.978 × 10⁶ tons and 4.107 ×10⁵ tons, respectively. These findings verify the effectiveness of our framework and further highlight the need for tailored, region-specific policies to achieve carbon reduction goals. Full article

This study proposes a non-contact framework for evaluating the skid resistance of shared roadside pavements to improve cyclist and pedestrian safety. By integrating a friction tester and a laser scanner, we synchronize high-resolution three-dimensional (3D) surface texture characterization with friction coefficient measurements under dry and wet conditions. Key metrics—including fractal dimension (FD), macro/micro-texture depth density (HL_TX and WL_TX), mean texture depth (MTD), and joint dimensions—were derived from 3D laser scans. A hierarchical regression analysis was employed to prioritize the influence of texture and joint parameters on skid resistance across environmental conditions. Combined with material types (brick, tile, and stone) and drainage performance, these metrics are systematically analyzed to quantify their correlations with skid resistance. Results indicate that raised macro-textures and high FD (>2.5) significantly enhance dry-condition skid resistance, whereas recessed textures degrade performance. The hierarchical model further reveals that FD and MTD dominate dry friction (β = 0.61 and −0.53, respectively), while micro-texture density (WL_TX) and seam depth are critical predictors of wet skid resistance (β = −0.76 and 0.31). In wet environments, skid resistance is dominated by micro-texture density (WL_TX < 3500) and macro-texture-driven water displacement, with higher WL_TX values indicating denser micro-textures that impede drainage. The study validates that non-contact laser scanning enables efficient mapping of critical texture data (e.g., pore connectivity, joint depth ≥0.25 mm) and friction properties, supporting rapid large-scale pavement assessments. These findings establish a data-driven linkage between measurable surface indicators (texture, morphometry, drainage) and skid resistance, offering a practical foundation for proactive sidewalk safety management, especially in high-risk areas. Future work should focus on refining predictive models through multi-sensor fusion and standardized design guidelines. Full article

The oxidation and recession of carbon-fiber-reinforced ultrahigh-temperature ceramic matrix composites (C/UHTCMCs) fabricated via reactive melt infiltration (RMI) using Zr-Ti alloys with three different compositions are evaluated via an arc-jet tunnel test at temperatures above 2000 °C for 60 s. Thermodynamic evaluations show that the recession of the UHTCMCs is prevented by the formation of a solid solution of ZrTiO₄ on their exposed surface. Because an increase in the Zr content increases the melting temperature of ZrTiO₄, the recession of the composites increases as the Zr content in the infiltrated alloys decreases. UHTCMCs fabricated with Zr-20at%Ti showed the least recession (<5%). Full article