Search Results (1,900)

This study aims to evaluate the corrosion behavior of and morphological changes in S235JR steel exposed to 0.5 M hydrochloric acid solution over a period of 24 weeks. Corrosion resistance was assessed through weight loss measurements and electrochemical techniques (such as open circuit potential (OCP), polarization resistance (R_p), and corrosion rate (V_corr)), while surface morphology, elemental analysis, roughness, and Vickers hardness were also analyzed. All evaluations were performed at the same immersion intervals: 2, 4, 8, 12, and 24 weeks. The corrosion rate started at 0.9 mm/year after the first hour of immersion, then decreased due to the formation of corrosion products on the steel surface, and fluctuated during prolonged exposure, reaching a maximum of 8.5 mm/year after 24 weeks. Weight loss increased gradually during the first 8 weeks, followed by a more pronounced rise. Polarization resistance and corrosion rate exhibited dynamic variations. SEM analysis revealed severe surface degradation, including cracks and deep pits. Surface roughness increased significantly from an initial value of 0.91 μm to 9.03 μm at 24 weeks. Vickers hardness dropped from 148.7 HV0.5 to 87.3 HV0.5, due to non-uniform corrosion product formation. These findings highlight the progressive deterioration of S235JR steel in acidic environments and provide valuable insight into its long-term corrosion resistance. Full article

Background: Elite athletes are frequently subjected to high-intensity training regimens, which can result in cumulative physical stress, overtraining, and potential health risks. Monitoring autonomic responses to such load is essential for optimizing performance and preventing maladaptation. Objective: The present study aimed to assess changes in autonomic regulation immediately and two hours after training in athletes, using an integrated framework (combining time- and frequency-domain HRV indices with nonlinear and recurrence quantification analysis). It was investigated how repeated assessments over a 4-month period can reveal cumulative effects and identify athletes at risk. Special attention was paid to identifying signs of excessive fatigue, autonomic imbalance, and cardiovascular stress. Methods: Holter ECGs of 12 athletes (mean age 21 ± 2.22 years; males, athletes participating in competitions) over a 4-month period were recorded before, immediately after, and two hours after high-intensity training, with HRV calculated from 5-min segments. Metrics included HRV and recurrent quantitative analysis. Statistical comparisons were made between the pre-, post-, and recovery phases to quantify autonomic changes (repeated-measures ANOVA for comparisons across the three states, paired t-tests for direct two-state contrasts, post hoc analyses with Holm–Bonferroni corrections, and effect size estimates η²). Results: Immediately after training, significant decreases in SDNN (↓ 35%), RMSSD (↓ 40%), and pNN50 (↓ 55%), accompanied by increases in LF/HF (↑ 32%), were observed. DFA α1 and Recurrence Rate increased, indicating reduced complexity and more structured patterns of RR intervals. After two hours of recovery, partial normalization was observed; however, RMSSD (−18% vs. baseline) and HF (−21% vs. baseline) remained suppressed, suggesting incomplete recovery of parasympathetic activity. Indications of overtraining and cardiac risk were found in three athletes. Conclusion: High-intensity training in elite athletes induces pronounced acute autonomic changes and incomplete short-term recovery, potentially increasing fatigue and cardiovascular workload. Longitudinal repeated testing highlights differences between well-adapted, fatigued, and at-risk athletes. These findings highlight the need for individualized recovery strategies and ongoing monitoring to optimize adaptation and minimize the risk of overtraining and health complications. Full article

Assessment of liver fibrosis stage is important in the management of patients with metabolic dysfunction-associated steatotic liver disease (MASLD). However, non-invasive methods to determine the changes in liver fibrosis stage are unknown. We investigated whether Wisteria floribunda agglutinin-positive human Mac-2 binding protein (WFA⁺-M2BP), a serum fibrosis marker, can evaluate the changes in liver fibrosis stage. We observed the course of liver fibrosis stage and five serum fibrosis markers of 196 MASLD patients who had a paired biopsy performed. The changes in fibrosis markers, including WFA⁺-M2BP, were compared according to the changes in fibrosis stage. Factors associated with improvement of fibrosis stage were examined in a multivariate analysis. The changes in WFA⁺-M2BP (ΔWFA⁺-M2BP) were significantly correlated with changes in fibrosis stage (p < 0.01). The median of ΔWFA⁺-M2BP was −0.21, −0.08, −0.04, and 0.19 in 2 fibrosis stage regression group, 1 fibrosis stage regression group, fibrosis stage unchanged group, and fibrosis stage progression group, respectively (p < 0.01). However, other non-invasive markers did not reflect changes in fibrosis. ΔWFA⁺-M2BP was a significant factor for the regression of liver fibrosis stage in multivariate analysis (odds ratio: 3.54, 95% confidence interval: 1.55–8.12, p < 0.01). Time-course changes in WFA⁺-M2BP levels indicate the changes in liver fibrosis. Full article

Urban flood damage is increasing globally, particularly in major cities. Factors contributing to flood risk include urban environmental changes, such as watershed development and precipitation variations caused by climate change. Rapid urbanization and weather anomalies further complicate flood management and damage mitigation. Additionally, detailed analyses at small spatial units (e.g., roads, buildings) remain insufficient. Hence, urban flood analysis considering such spatial variations is required. This study analyzed flood risk in Ulsan, Korea, under a severe flood scenario. Land cover changes from the 1980s to 2010s were examined in 10-year intervals, along with the frequency of heavy rainfall and high river water levels that trigger severe floods. Flood risk was structured as a matrix of likelihood and impact. The results revealed that land cover changes, influenced by development policies or regulations, had a minimal impact on urban flood risk, which is likely because effective drainage systems and stringent urban planning regulations mitigated their effects. However, the frequency and intensity of extreme precipitation events had a substantial effect. These findings were validated using a comparative analysis of an inundation damage trace map and flood range simulated by a physical model. The 10 m grid resolution and time-series likelihood-and-impact framework used in this study can inform budget allocation, resource mobilization, disaster prevention planning, and decision-making during disaster response efforts in major cities. Full article

Background/Objectives: This study aimed to investigate changes and synthesize the existing evidence in macular choroidal thickness in patients with keratoconus (KC) compared to healthy controls, utilizing optical coherence tomography (OCT). Methods: PubMed and Scopus databases were systematically searched for published articles comparing choroidal thickness between patients with KC and healthy controls. The Mean Difference (MD) with 95% confidence interval (CI) was computed to compare continuous variables. Our study was registered with PROSPERO with registration ID: CRD42024605227. Revman 5.4 was used for the analysis. Results 10 studies were included in the analysis. Subfoveal choroidal thickness was increased in patients with KC compared to controls. (MD = 43.94, 95% CI = 17.36–70.51, p = 0.001, I² = 95%). Leave-one-out sensitivity analysis confirmed this finding. Conclusions: Our meta-analysis demonstrated that eyes with keratoconus have significantly increased macular choroidal thickness compared to controls. These findings highlight the need for longitudinal studies stratified by disease severity to clarify the role of choroidal changes in keratoconus progression. Full article

Based on long-term series of observations of water flow of 22 small and medium-sized rivers in the forest-steppe and steppe east of the East European Plain, an analysis of its trend changes in 1961–2022, i.e., in the time interval of the Anthropocene with the most progressive climate change in the study region, was carried out. The main quantitative hydrological parameters studied were annual average water discharge, annual maximum water discharge (Q_max), minimum water discharge (Q_min-CP) during the ice-covered period of the riverbed (cold period, mainly December–March), minimum water discharge (Q_min-WP) during the ice-free period of the riverbed (warm period, mainly April–November), as well as some of their ratios, which provide a clear idea of changes in the intra-annual variability of water flow. The principal methodological toolkit used was a standard set of statistical tests applied to time series analysis. A summary of the study results showed that statistically significant trend changes in the annual water flow of most of the analyzed rivers were not observed for the specified period. At the same time, statistically significant intra-annual changes in the flow were revealed: a significant reduction in Q_max (especially in the forest-steppe zone) and a significant increase in Q_min-CP and Q_min-WP. Thus, the ratio between Q_max and Q_min-CP (Q_min-WP) decreased between the baseline climatic periods 1961–1990 and 1991–2020 by an average of 4.1 (4.0) times in the rivers of the forest-steppe zone, and by 5.2 (5.3) times in the rivers of the steppe zone. Climate change is considered the leading cause of the observed intra-annual changes in river water flow in the study region, with the main factor being an increment in annual air temperature, especially during the cold season. Full article

Marine applications often involve metallic materials, including steel, that must endure harsh conditions such as cavitation erosion (CE). This study investigates the CE behavior of 42CrMo4 steel, both in its original state and after pre-corrosion in a 3.5% NaCl solution for 120 days, simulating a simplified marine environment. Cavitation testing was conducted using an ultrasonic vibratory setup with a stationary sample, at intervals of 10 and 30 min, with a total testing time of 150 min. Mass loss (ML), mass loss rate (MLR), mean depth of erosion (MDE), and level of degradation (LoD) were calculated, while surface roughness (Rz) was measured using a TR200 tester. Surface changes were analyzed through field emission scanning electron microscopy (FESEM) and image analysis techniques. Morphological parameters such as the number of pits, average diameter, and total pit area were used to quantify surface damage. Results showed that pre-corroded samples exhibited a significantly higher erosion rate than non-corroded ones. Pre-corrosion introduced microcracks and surface defects that served as initiation sites for cavitation damage. These imperfections increased surface roughness and created favorable conditions for pit formation, leading to faster and deeper material loss. Image and FESEM analyses confirmed the presence of larger and deeper pits in pre-corroded samples compared to the smaller and shallower pits in non-corroded specimens. This study highlights the impact of pre-corrosion on the cavitation resistance of 42CrMo4 steel and demonstrates the effectiveness of combining mass loss data with morphological and surface analyses for evaluating cavitation damage under marine-like conditions. Full article

Background/Objective: Contact lens discomfort (CLD) is a prevalent issue affecting up to 50% of wearers and contributes to discontinuation in approximately 30% of cases. This study aimed to evaluate the impact of refitting symptomatic monthly replacement contact lens (CL) wearers with a new daily, disposable contact lens (Kalifilcon A DDCL) and to compare its effectiveness against a placebo CL. Methods: Seventy-nine symptomatic wearers (CLDEQ-8 ≥ 12; mean age 27.07 ± 8.38 years; 77% female) were recruited and randomly assigned to wear either Kalifilcon A DDCLs or placebo CLs. Participants were assessed at baseline and after one month of CL wear. Subjective measures included the CLDEQ-8 and the NEI VFQ-25 questionnaire. Objective assessments included tear film stability and ocular surface health. Statistical analysis was performed using paired t-tests and repeated-measures ANOVA. Bonferroni correction was applied for multiple comparisons, and results were reported with effect sizes (Cohen’s d) and 95% confidence intervals. Statistical significance was set at p < 0.05. Results: Kalifilcon A DDCL wearers showed a significant reduction in CLDEQ-8 scores (18.5 ± 4.6 to 10.8 ± 8.5; p < 0.005; Cramer’s V: 0.594; 95% CI: 13.35–15.34), with only 33% remaining symptomatic. Vision-related quality of life improved (75.83 ± 8.0 to 83.5 ± 8.6; p < 0.005; Cramer’s V: 0.977; 95% CI: 78.54–80.81), especially in ocular pain (p < 0.001; Cramer’s V: 0.755; 95% CI: 54.73–58.88), role difficulties (p < 0.001; Cramer’s V: 0.812; 95% CI: 35.12–42.77), and color vision (p < 0.05; Cramer’s V: 0.575; 95% CI: 93.07–95.63). Compared to the placebo CL, Kalifilcon A DDCLs led to greater improvements in comfort (p < 0.0001; Cramer’s V: 0.329; 95% CI: 7.22–7.74), visual acuity (p < 0.0001; Cramer’s V: 0.267; 95% CI: 7.38–7.85), and satisfaction (p = 0.005; Cramer’s V: 0.208; 95% CI: 7.70–8.18). Tear film stability also improved significantly (p < 0.05), with no changes observed in the placebo group. Conclusions: Refitting symptomatic CL wearers with Kalifilcon A DDCLs significantly improves comfort, reduces CLD symptoms, and enhances vision-related quality of life. These results support its use as a beneficial alternative to monthly CLs in symptomatic individuals. Full article

Background/Objectives: This study aimed to investigate the association between dietary patterns and the risk of developing osteoporosis in women, emphasizing the role of nutrition in bone health during menopause-related hormonal changes. Methods: We conducted a prospective study involving 4865 women aged 40–69 years without osteoporosis at baseline. Dietary information was collected using a validated semi-quantitative food frequency questionnaire, and composite-defined osteoporosis (CDO) was defined using self-administered questionnaires and quantitative ultrasound. Multivariate Cox proportional hazards regression analysis was employed to calculate hazard ratios and 95% confidence intervals to assess the association between dietary patterns and the risk of CDO. Results: During a median follow-up of 8.26 years, 895 and 1525 cases of CDO were reported in premenopausal and postmenopausal women, respectively. Three dietary patterns were identified in premenopausal women: the “Vegetables and Seafood,” “Western,” and “White rice, Meat, and Alcohol” patterns. In postmenopausal women, the “Diverse,” “Plant-based,” and “Sweets and Drinks” patterns were identified. Among premenopausal women, the “White rice, Meat, and Alcohol” pattern was associated with a significantly greater risk of CDO in the highest tertile compared with that in the lowest tertile, whereas no significant patterns were observed in postmenopausal women. Conclusions: These findings underscore the importance of dietary factors in maintaining bone health, particularly in premenopausal women. Encouraging the reduction in dietary factors associated with an increased osteoporosis risk may help improve bone health and quality of life in women, especially before significant menopause-induced bone loss occurs. This study highlights the need for early dietary interventions to prevent osteoporosis in women. Full article

Geophysical and remote sensing observations offer powerful means to monitor large-scale hydrological changes, particularly in regions where in situ data are scarce. In this study, we integrate satellite-derived water storage from the Gravity Recovery and Climate Experiment (GRACE) with land surface variables from the Global Land Data Assimilation System (GLDAS) to assess and forecast groundwater storage (GWS) dynamics across eight major regions in Sudan. Missing GRACE observations of terrestrial water storage (TWS) were first reconstructed using a Random Forest machine learning model, after which GWS anomalies were estimated by subtracting GLDAS-based surface and root-zone components from TWS. The resulting GWS time series was decomposed into trend, seasonal, and residual components, and the trend signals were used to train a bootstrapped Bidirectional Long Short-Term Memory (BiLSTM) model. This framework generated probabilistic forecasts accompanied by confidence intervals, which were generally narrow and consistent with the historical range. The forecasted GWS anomalies indicate positive recovery across all regions, with Sen’s slope values ranging from 0.014 to 0.051 per month. The strongest recoveries are evident in the southern and southwestern regions, while northern and eastern areas display more modest gains. This work represents one of the first applications of deep learning with uncertainty quantification for GRACE-based groundwater analysis in Sudan, demonstrating the potential of such an integrated approach to support informed and sustainable groundwater management in data-limited environments. Full article

Heart Rate Variability (HRV) analysis allows for assessing autonomic control from the beat-by-beat dynamics of the time series of cardiac intervals. However, some HRV indices may strongly correlate with the mean heart rate, possibly flawed by the interpretation of HRV changes in terms of autonomic control. Therefore, this study aims to (1) investigate how HRV indices of fluctuation amplitude and multiscale complex dynamics of cardiac time series faithfully describe the autonomic control at different heart rates through a mathematical model of the generation of cardiac action potentials driven by realistically synthesized autonomic modulations; and (2) propose an alternative procedure of HRV analysis less sensitive to the mean heart rate. Results on the synthesized series confirm a strong dependency of amplitude indices of HRV on the mean heart rate due to a nonlinearity in the model, which can be removed by our procedure. Application of our procedure to real cardiac intervals recorded in different postures suggests that the dependency of these indices on the heart rate may importantly affect the physiological interpretation of HRV. By contrast, multiscale complexity indices do not substantially depend on the heart rate provided that multiscale analyses are defined on a time- rather than a beat-basis. Full article

Background: The optimal treatment strategy for locally advanced unresectable pancreatic cancer (LAPC) is still investigated. Therefore, we evaluated the role of radiotherapy (RT) in the management of LAPC in the modern era. Methods: A systematic review was conducted following the Preferred Reporting Items for Systemic Review and Meta-Analyses guidelines. Eligible studies were about for LAPC treated with curative-intent modern RT techniques including intensity-modulated radiotherapy (IMRT), stereotactic body radiotherapy (SBRT), and particle beam therapy (PBT) until September 2024. Results: In total, 53 observational studies, encompassing 2548 patients (993 treated with IMRT, 998 with SBRT, and 557 with PBT), met the inclusion criteria. Concurrent chemoradiotherapy (CCRT) was implemented in 28 studies, including only 3 studies in the SBRT group. Elective nodal irradiation (ENI) was adopted in 22%. The pooled 2-year overall survival (OS) rate was 29% (95% confidence interval [CI], 25–34%) for all patients, with no significant differences among RT techniques: 28% (95% CI, 22–34%) for IMRT, 26% (95% CI, 19–34%) for SBRT, and 43% (95% CI, 28–57%) for PBT (p = 0.1121). The pooled rate of acute hematologic toxicity (HT) ≥ grade 3 was 17% (95% CI, 9–26%), with significant differences among RT techniques: 23% (95% CI, 9–40%) for IMRT, 4% (95% CI, 0–11%) for SBRT, and 20% (95% CI, 6–37%) for PBT (p = 0.0181). In addition, CCRT (p = 0.0084) and ENI (p = 0.0145) significantly increased the risk of acute HT. Gastrointestinal toxicities rarely occurred. Conclusions: This systematic review and meta-analysis showed similar efficacy among modern RT techniques for LAPC management. Since almost all studies have single-arm design, and chemotherapy regimens have changed over time, conclusions must be drawn with caution. The use of modern RT techniques is individually selected according to clinical practice and resource availability. Full article

Background/Objectives: We evaluated the clinical features and natural course of treatment-naïve non-exudative macular neovascularization (NE MNV) associated with age-related macular degeneration in Korean patients. Methods: This retrospective longitudinal study of 21 eyes of 21 patients with NE MNV involved a chart review of best corrected visual acuity (BCVA), optical coherence tomography (OCT), and OCT angiography parameters. Results: This study included 13 men (13/21, 61.9%) and 8 women (8/21, 38.1%), with a mean age of 71.5 ± 9.1 years. The average follow-up period was 15.1 ± 11.8 (range 6.0–49.6) months, and 14 eyes (66.7%) demonstrated exudative changes on OCT scans. The baseline BCVA was 0.15 ± 0.18 logMAR. The initial central macular thickness (CMT), subfoveal choroidal thickness, and the outer retinal layer thickness were 265.3 ± 37.1, 245.2 ± 95.2, and 86.6 ± 5.3 μm, respectively. Cox proportional hazards analysis revealed that older age (hazard ratio [HR]: 1.096, 95% confidence interval [CI]: 1.002–1.200; p = 0.045), larger baseline CMT (HR: 1.025, 95% CI: 1.002–1.049; p = 0.035), and larger baseline MNV (HR: 1.618, 95% CI: 1.035–2.529; p = 0.035) were significant risk factors for exudative changes. Conclusions: We observed the clinical features and natural course of NE MNV in Korean patients and identified that significant risk factors for exudative changes in NE MNV included old age, initially thick CMT, and larger MNV size at baseline. For eyes with NE MNV that have risk factors of exudative conversion, more frequent observation is recommended to ensure the appropriate management. Full article

Background/Objectives: This systematic review aimed to evaluate the effectiveness and predictability of lower incisor intrusion with clear aligners in permanent dentition, addressing one of the most challenging aspects of vertical tooth movement control in the mandibular anterior region. Methods: A comprehensive literature search was conducted across five databases (PubMed, Scopus, Embase, and Cochrane) according to PRISMA guidelines. Eight clinical studies fulfilled the eligibility criteria. Risk of bias was assessed using ROBINS-I, and certainty of evidence was graded with GRADE. Key outcomes included the amount of achieved versus planned intrusion, predictability, treatment protocols, use of auxiliaries, and patient-related factors such as age and compliance. Results: Reported mean intrusion values ranged from 0.4 to 1.5 mm, with predictability between 35% and 65%. The effectiveness of intrusion was influenced by the magnitude of planned movement, auxiliaries (e.g., attachments, elastics), refinement strategies, and patient-specific factors. Substantial heterogeneity was present in measurement methods (CBCT, cephalometry, digital models) and clinical protocols (aligner change intervals, refinement frequency), preventing meta-analysis. Seven of the eight studies were rated as having a serious risk of bias, and the overall certainty of evidence was moderate to low. Long-term outcomes and patient-centered measures were not adequately assessed. Conclusions: Within the limitations of the available evidence, lower incisor intrusion with clear aligners may be considered a feasible orthodontic option when supported by biomechanically informed clinical management. However, conclusions should be interpreted with caution due to heterogeneity, high risk of bias, and lack of long-term data. Further standardized studies with longer follow-up are required to strengthen reliability and clinical applicability. Full article

Background: This prospective observational study was conducted to systematically assess immediate changes occurring (within one hour) in corneal endothelial cell morphology and anterior segment parameters following Nd:YAG laser posterior capsulotomy in pseudophakic patients and to analyze the correlation between these changes and laser energy parameters. Methods: A single-arm, within-subject pre–post design was employed to evaluate corneal endothelial morphology (cell density, count, area, coefficient of variation and hexagonal percentage) and anterior chamber parameters (depth, angle, volume) before and one hour after the procedure using specular microscopy and Pentacam analysis. Patient demographics (age), clinical parameters (best corrected visual acuity and intraocular pressure), postoperative-YAG laser interval, and laser energy parameters (energy per shot, pulse count, and total applied energy) were also documented. Results: Thirty-two pseudophakic patients (mean age 56.3 ± 19.2 years) underwent Nd:YAG laser posterior capsulotomy with mean energy per shot of 3.15 ± 1.07 mJ and pulse count of 34.3 ± 20.4. Specular microscopy revealed significant post-procedural decreases in endothelial cell density (2184.05 to 2057.2 cells/mm²; p = 0.006) and increases in average cell area (529.25 ± 242.72 to 587.75 ± 281.09 µm²; p = 0.004) and minimum cell area (199.3 ± 170.62 to 248.35 ± 202.7 µm²; p = 0.035). Corneal topography also decreased significantly in the anterior chamber angle (40.07 ± 10.34 to 35.42 ± 6.78 degrees; p = 0.048), with positive correlations between energy per shot and endothelial cell density (r = 0.557; p = 0.011) and average cell area (r = 0.544; p = 0.013). Conclusions: This study demonstrates that Nd:YAG laser capsulotomy causes immediate, energy-dependent alterations in corneal endothelial density and anterior chamber parameters within one hour post-procedurally. The identification of energy per shot as a key determinant represents a preliminary observation for optimizing laser parameters and reducing potential complications in pseudophakic patients. Full article