Search Results (2,466)

Arundo donax L. is a significant energy crop and perennial grass, with its efficient conversion holding substantial implications for the utilization of agricultural biomass resources. However, the distinct effects of acid and alkali pretreatments on its lignocellulose degradation patterns and structural modifications remain inadequately characterized. This study utilized Arundo donax L. as raw material to compare the effects of dilute sulfuric acid and sodium hydroxide pretreatments on its component degradation and structural modifications. Single-factor experiments were conducted, and the mechanisms were investigated using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses. The results indicated that dilute sulfuric acid pretreatment primarily degraded hemicellulose (up to 85.8%) with limited lignin removal (<13%), whereas sodium hydroxide pretreatment effectively removed lignin (66.8%). XRD analysis revealed that crystallinity after dilute acid treatment was significantly higher than that of untreated samples (p < 0.05). Sodium hydroxide treatment induced a concentration-dependent non-monotonic change in crystallinity: the crystallinity index (CrI) peaked at a 1% concentration, was significantly lower at 3% and 4%, and showed intermediate values at 2% and 5%. The apparent crystallite size remained at 3.0–3.3 nm, suggesting that both pretreatments primarily targeted amorphous regions. FTIR analysis confirmed that alkali treatment more thoroughly disrupted ester bonds and lignin. SEM images revealed that alkali-treated fiber bundles were more loosely packed with relatively smoother surfaces. In acid treatment, 100 °C was identified as the critical temperature for a significant increase in crystallinity, whereas in alkali treatment, temperature had no significant effect on crystallinity. Full article

Background: Children and teenagers use electronic devices daily, especially smartphones. The use of these devices exposes children and adolescents to excess blue light, which can alter the structures of the eye, especially the retina. As a protective mechanism, the macular region contains pigments represented by lutein, zeaxanthin, and meso-zeaxanthin. In this study, we aimed to analyze the relationship between the Macular Pigment Optical Density (MPOD) levels in the macula and the time spent on smartphones in children and adolescents. Methods: Fifty-seven children and teenagers aged between 8 and 18 were evaluated, with a total of 114 eyes. The patients included in the study were divided into two groups: those who spent less than two hours a day on the device and those who exceeded this period. To determine the amount of macular pigment, the Heterochromatic Flicker Photometry technique was used. Results: We found a statistically significant difference in screen time between weekdays and weekends in favor of the latter. We compared the different refractive categories with respect to pigment levels and screen time and found no significant differences between groups. When comparing the patients with respect to environment, we found a slight difference in macular pigmentation in the favor of rural areas and also in the screen time which was shorter in rural areas. We found a strong association at all levels between longer screen time (both weekdays and weekend) and lower macular pigment quantities for both eyes. When comparing the groups with more/less than 2 h of screen time, the MPOD was lower for both eyes in the group with over 2 h screen time. Conclusions: In this study we demonstrated that smartphone use is a risk factor leading to a decrease in MPOD in children and adolescents. The amount of lutein in the retina, brain and serum are correlated, therefore MPOD can be considered a natural biomarker of lutein and zeaxanthin levels in the body. Full article

Heart failure (HF) is a clinical syndrome characterized by structural or functional cardiac abnormalities that impair ventricular filling or ejection, leading to inadequate systemic perfusion and elevated intracardiac pressures. Current epidemiological estimations declare approximately 26 million patients affected worldwide are living with HF. While ischemic heart disease remains the primary etiology, there is a wide range of behavioural factors that significantly influence disease onset and progression. This review focuses on the evidence for established risk factors, including smoking, excessive alcohol consumption, obesity, physical inactivity, poor diet, sleep disorders, and psychological stress. Furthermore, we discuss other novel determinants such as electronic nicotine delivery systems (ENDS), cannabis, high-dose caffeine, and psychostimulants. The basic mechanistic pathways, including endothelial dysfunction, oxidative stress, neurohormonal activation, and direct myocardial toxicity, are also pointed out and reviewed in this paper. The aim of this study is to integrate epidemiological data with pathophysiological insights to identify priority targets for primary prevention and highlight areas for future research. Full article

Oxygen vacancies play a crucial role in modulating the chemical and catalytic properties of metal oxide catalysts. Herein, quercetin was used as a green reducing agent to prepare Cu-doped MnO₂ (Cu-MnO₂) composite catalysts with varying Cu doping levels via an ultrasonically assisted strategy. The structure-activity relationships were systematically investigated using XRD, Raman, XPS, H₂-TPR, and O₂-TPD. Benefiting from optimized surface lattice defects induced by an appropriate Cu doping level, the Cu-MnO₂-2 sample, which exhibited the highest oxygen vacancy concentration, achieved a HCHO removal efficiency of 99.2% for 1 ppm HCHO at room temperature (25 °C) and 50% relative humidity within 30 min. The enrichment of Mn³⁺, Cu⁺, and surface-adsorbed oxygen species (O_ads) further corroborated the increased oxygen vacancy density, indicating that moderate Cu doping effectively promotes electron transfer and oxygen activation. After five consecutive cycles, the HCHO conversion remained above 96%. Post-cycling characterizations (XRD, FTIR, EDS, and XPS) confirmed the excellent structural and chemical stability of the catalyst, with the Mn³⁺ proportion and Cu⁺/Cu²⁺ ratio well preserved. In situ DRIFTS analysis revealed that surface-adsorbed oxygen and oxygen-vacancy-activated reactive oxygen species (ROS) are key factors in the efficient HCHO oxidation over the green Cu-MnO₂-2 catalyst, promoting rapid conversion of intermediates and ultimately generating CO₂ and H₂O. This study provides a facile, low-cost, and green synthesis strategy for Cu-MnO₂ composite catalysts for indoor, room-temperature HCHO abatement, offering new insights into the design of other composite catalyst materials. Full article

Background: Healthcare chatbots have emerged as a promising application of artificial intelligence in healthcare, offering potential benefits in accessibility, efficiency, and patient engagement. However, despite their growing adoption, limited research has examined the factors that determine their success from the user’s perspective. Objective: This study aimed to evaluate the success of a health chatbot service by applying the updated DeLone and McLean Information Systems Success Model augmented with a trust construct, examining the effects of information quality, system quality, service quality, and trust on intention to use, user satisfaction, and net benefits. Methods: An online survey design was employed, utilizing a structured questionnaire with 28 items measuring seven constructs on a seven-point Likert scale. Data were collected electronically from residents of Saudi Arabia between July and September 2024 using convenience sampling. Eligible participants were adults aged 18 years or older who had previously used the health chatbot service. A total of 321 valid responses were obtained. Partial Least Squares Structural Equation (PLS-SEM) was conducted using SmartPLS 3.3 software for measurement and structural model analysis. Results: The measurement model demonstrated acceptable reliability and validity, with composite reliability values exceeding 0.90 and average variance extracted values above 0.70 for all constructs. Structural model analysis supported eight of ten hypotheses. Trust exhibited the strongest effect on intention to use (β = 0.359, p < 0.001), followed by system quality (β = 0.234, p < 0.001) and information quality (β = 0.147, p < 0.01). Intention to use significantly predicted user satisfaction (β = 0.620, p < 0.001) and net benefits (β = 0.278, p < 0.001). User satisfaction demonstrated a strong positive effect on net benefits (β = 0.610, p < 0.001). The model explained 67.6% of the variance in intention to use, 72.7% in user satisfaction, and 71.4% in net benefits. Conclusions: Trust emerged as the most influential factor affecting intention to use the healthcare chatbot service, underscoring its critical role in user acceptance of health chatbot services. Information quality, system quality, and service quality exerted small to moderate effects on behavioral outcomes. These findings suggest that healthcare organizations deploying chatbot services should prioritize building user trust alongside ensuring high system and information quality to maximize user satisfaction and realized net benefits. Full article

The nucleon spin–orbit interaction is a cornerstone of nuclear structure theory, yet its isospin dependence remains insufficiently constrained within modern nuclear energy density functional (EDF) theory. It was recently shown that, within the framework of extended Skyrme EDFs, the charge-weak form factor difference $\Delta F_{\mathrm{CW}}$ in ${}^{48}$Ca exhibits remarkable sensitivity to the effective isovector spin–orbit (IVSO) interaction, whereas $\Delta F_{\mathrm{CW}}$ in ${}^{208}$Pb is much less sensitive to this channel. Extending this analysis to other nuclei, we find that ${}^{90}$Zr, with its ten spin–orbit unpaired $1{\mathrm{g}}_{9/2}$ neutrons, displays a $\Delta F_{\mathrm{CW}}$ sensitivity to the IVSO strength similar to that of ${}^{48}$Ca, arising from modifications to the central mean-field potential rather than the one-body spin–orbit potential. In contrast, ${}^{62}$Ni, like ${}^{208}$Pb, remains largely insensitive to the IVSO interaction. This structure-driven distinction suggests an experimental strategy: future parity-violating electron scattering measurements, e.g., the MREX experiment at the MESA facility, on ${}^{48}$Ca and ${}^{90}$Zr would help constrain the effective IVSO strength, while measurements on ${}^{208}$Pb and ${}^{62}$Ni can provide a cleaner probe of the density dependence of the symmetry energy with reduced IVSO sensitivity. Full article

Lead-free perovskite solar cells have become promising materials in the solar energy field; however, there are some constraints limiting their efficiency, like unfavorable band alignment, high defect densities, and inefficient charge extraction. Cs₃Sb₂I₉ is a lead-free material that has excellent stability, but its experimentally reported efficiencies remain low (<4%). Therefore, Cs₃Sb₂I₉ device performance was investigated using the one-dimensional Solar Cell Capacitance Simulator (SCAPS-1D), where the planar n–i–p structure was analyzed, focusing on its band alignment, transport layers, and key device parameters. The optimized device achieved a power conversion efficiency (PCE) of 13.62%, an open circuit voltage (Voc) of 1.37 V, a short circuit current density (Jsc) of 11.77 mA/cm², and a fill factor (FF) of 84.15% with a 180 nm PCBM electron transport layer, a 150 nm Cu₂O hole transport layer, and a 500 nm absorber thickness. This study advances the development of efficient lead-free perovskite solar cells, promoting sustainable and clean energy. Full article

Hemoglobin A1c is a central biomarker for long-term glycemic control and a key predictor of diabetes-related complications. The COVID-19 pandemic disrupted routine healthcare delivery and introduced potential metabolic effects of SARS-CoV-2 infection, yet the long-term impact of COVID-19 on glycemic trajectories in individuals with diabetes remains unclear. In this retrospective study, we leveraged harmonized electronic health record data from the National Clinical Cohort Collaborative to evaluate changes in HbA1c before and after documented SARS-CoV-2 infection in adults with diabetes (n = 93,320). Patients were required to have repeated HbA1c measurements pre- and post-infection and stable exposure to key antihyperglycemic medications. A paired statistical analysis was used to identify individuals with statistically significant post-infection changes in HbA1c. We then developed and evaluated multiple supervised machine learning classifiers using an 80/20 train–test split and cross-validation to assess demographic, clinical, and structural factors associated with significant glycemic change. Most patients (71%) did not experience a statistically significant change in average HbA1c following COVID-19 infection, and among those who did, decreases were more common than increases. A random forest classifier achieved the best overall performance, and feature importance and SHAP analyses highlighted body mass index, insulin use, age, and socioeconomic proxies as key contributors. These findings suggest that while COVID-19 infection does not substantially alter long-term glycemic control for most patients with diabetes, individual-level clinical and structural factors influence post-infection glycemic variability. Full article

Nano-SiO₂-reinforced epoxy resin gel mortar (NERM) serves as an essential material for repairing and strengthening defective structures in civil engineering. This study developed a hybrid fiber-reinforced NERM (HF-NERM) by incorporating PVA–steel fiber, aiming to achieve superior mechanical properties, toughness, and bonding performance. This study systematically investigates the workability, mechanical properties, toughness, and bonding characteristics of HF-NERM, as well as their enhancement mechanisms characterized using scanning electron microscopy (SEM). Experimental results indicate that the slump of HF-NERM decreased significantly with increasing hybrid fiber content, and the regression coefficient of PVA fiber on slump was −86.7, while that of steel fiber was −4.5. The addition of hybrid fibers generally enhanced the mechanical properties. The optimal combination was 0.9% PVA fiber and 1.2% steel fiber, at which the flexural strength reached 11.56 MPa with an increase of 32.57%, splitting tensile strength reached 4.42 MPa with an increase of 20.1%, and interfacial bonding strength was improved by 9.8%. With the exception of splitting tensile strength, most mechanical properties initially increased and then decreased with increasing hybrid fiber content, indicating an optimal dosage. The hybrid fibers also enhanced the flexural toughness of HF-NERM; the toughness indices I₅, I₁₀ and I₂₀ were increased by 20.99%, 24.12% and 65.83%, respectively, and the residual strength factors R_5,10 and R_10,20 were increased by 26.8% and 160.8%. The hybrid fibers also enhanced the flexural toughness of HF-NERM. Mechanistically, PVA fibers primarily contributed to preventing the development of micro-cracks, while steel fibers were the main contributors to resisting macro-cracks. SEM observations demonstrated that the failure modes of PVA fibers involved synergistic mechanisms, while those of steel fibers were relatively singular. Related enhancement mechanisms were discussed based on the experimental results. Finally, the results demonstrate that NERM could be effectively strengthened by adding an appropriate content of hybrid fibers. This study’s novelty lies in quantifying the individual and synergistic effects of PVA–steel fibers in the NERM system, establishing optimal dosage parameters, and revealing matrix–fiber interaction mechanisms specific to epoxy-based composites. The findings provide a reliable material design basis for high-performance repair mortars and offer practical guidance for extending the service life of aging civil engineering structures. Full article

Thiocarbohydrazone derivatives represent a highly significant class in medicinal chemistry, characterized by a versatile scaffold defined with a thiocarbonyl (C=S) core and one or two imine (–C=N–) functionalities, allowing for precise modulation of their physicochemical and biological properties. The biological potential of a series of novel bis-substituted thiocarbohydrazone derivatives was predicted and evaluated through comprehensive in silico analysis. All investigated compounds complied with Lipinski’s Rule of 5, with most also satisfying the Rule of 3 while simultaneously exhibiting favorable pharmacokinetic properties and low predicted ecotoxicity. To substantiate these findings and elucidate the influence of para-substituents, chromatographic behavior of the studied derivatives was evaluated using reversed-phase thin-layer chromatography (RP-TLC). Initial linear regression analysis revealed statistically significant correlations between chromatographic parameters and in silico-derived descriptors of lipophilicity, pharmacokinetics, and ecotoxicity. Furthermore, cluster analysis and principal component analysis provided a robust and unambiguous interpretation of the structure–property relationships, highlighting substituent polarity as the leading factor controlling the bioactivity of bis-substituted thiocarbohydrazones, although the contribution of electronic effects cannot be neglected. Moreover, R_M⁰ correlates with lipophilicity and pharmacokinetics, whereas m reflects ecotoxicity. Collectively, these findings emphasize the critical role of subtle structural variations in shaping the overall properties of these novel derivatives. Full article

This article examines the interaction of clay minerals with iron ore concentrate in the context of the efficient use of composite mineral resources. The role of the adsorption properties of mineral additives in the formation of interparticle bonds in green pellets is analyzed. Using X-ray diffraction (XRD) and infrared spectroscopy, the dehydration processes of Na- and Ca-montmorillonite were investigated, and the influence of the cation type on the minerals’ ability to retain water was established. The high thermal stability of the structural OH groups of montmorillonite from the IV-layer clay of the Cherkasy deposit was confirmed, which is an important factor during high-temperature processing of mineral raw materials. Electron microscopy results showed that the fourth-layer clay forms an optimal porous composite microstructure, which contributes to increased water-holding capacity and gas permeability of the pellets. A direct correlation between the adsorption capacity of mineral additives and the strength of raw and dried pellets was experimentally confirmed. Montmorillonite with palygorskite from Layer IV, characterized by high adsorption capacity and prolonged dehydration processes, was identified as the most effective composite binding additive. The results obtained deepen scientific understanding of the mechanisms underlying pellet strength formation and have practical significance for the rational and resource-efficient use of mineral resources in the production of iron ore pellets. The results also demonstrate the potential for improving resource efficiency in pellet production through reduced consumption of traditional binder materials. Full article

To optimize the dry mixing preparation process for permeable asphalt mixtures and elucidate the microscopic mechanism of high-viscosity modifiers, this study employed Response Surface Methodology (RSM). Independent variables, including mixing temperature, dry mixing time, and wet mixing time, were selected, with Marshall stability, −10 °C splitting tensile strength, and residual stability as response indicators. The significance and fitting accuracy of the model were evaluated through Analysis of Variance and residual diagnosis. Additionally, the morphological evolution, spatial distribution, and chemical interactions of the modifier were characterized using scanning electron microscopy (SEM), fluorescence microscopy (FM), and Fourier Transform Infrared Spectroscopy (FTIR). The results revealed distinct differences in factor effects: mixing temperature most strongly influenced high-temperature performance, while wet-mixing time primarily governed low-temperature performance and water stability. Furthermore, significant interactions were observed among the variables. Multi-objective optimization determined the optimal process parameters to be a mixing temperature of 182 °C, dry mixing time of 180 s, and wet mixing time of 102 s. Experimental validation confirmed that the relative error between predicted and actual values was within 5%. Microscopic characterization revealed that under the dry mixing process, the modifier undergoes four stages: rapid melting, viscous flow, permeation diffusion, and swelling development. An appropriate mixing temperature combined with sufficient dry and wet mixing times promotes the formation of a uniform, dense spatial network structure of the modifier within the asphalt. This study validated the reliability of RSM in process optimization, providing theoretical foundations and key technical parameters for the green and efficient production of high-performance permeable asphalt mixtures. Full article

To simulate the erosion damage behavior of thermal barrier coatings (TBCs) under actual service conditions in an aircraft engine environment, this study developed a multi-factor coupled test setup capable of simulating combined loading under high-temperature (1150 °C), high-speed (0.4 Mach), and solid-particle erosion conditions. Yttria-stabilized zirconia (YSZ) TBCs were prepared using electron beam physical vapor deposition (EB-PVD). For different erosion durations (2 h, 5 h, 8 h, 12 h), the evolution of macroscopic and microscopic morphologies as well as the development of residual stresses in the thermally grown oxide (TGO) layer were systematically investigated. The results indicate that the erosion process of the YSZ coating can be divided into three stages. During the initial high-erosion-rate stage (8.17 g/kg), erosion damage was confined to the grain tips of the columnar crystals, primarily caused by brittle fracture at the grain tips, and the TGO stress was relatively low (−0.6 GPa). During the intermediate stage, the erosion rate was lower (2.74 g/kg). Impact stresses induced microcracks within the columnar grains, which gradually connected to form intergranular fractures. This led to the expansion of localized spalling pits. The interface began to wrinkle, and the stress rose to −2.2 GPa. In the final accelerated failure stage (5.88 g/kg), horizontal cracks fully propagated, leading to large-scale peeling of the coating. The stress was released to −0.9 GPa. The coating failure mechanism evolves from surface damage to interfacial peeling, which is closely related to the coating structure, stress evolution, and interfacial state. Full article

Rotational isomers (rotamers) of substituted aromatic molecules exhibit distinct physicochemical properties that are fundamental to understanding their reactivity and biological functions. However, resolving individual rotamers spectroscopically remains challenging due to their similar transition energies and overlapping spectral features. Herein, we report the conformer-specific identification and characterization of three stable rotamers of m-ethoxyphenol using a combination of resonance-enhanced multiphoton ionization (REMPI), hole-burning (HB) spectroscopy, and mass-analyzed threshold ionization (MATI) techniques, complemented by high-level quantum chemical calculations at the B3PW91/aug-cc-pVTZ and G4 levels of theory. The S₁ ← S₀ electronic origins of rotamers I, IV, and III were determined to be 35,966 ± 2, 36,031 ± 2, and 36,198 ± 2 cm⁻¹, respectively, while their corresponding adiabatic ionization energies (IEs) were precisely measured as 64,574 ± 5, 64,122 ± 5, and 64,994 ± 5 cm⁻¹. The vibrational spectra of both the S₁ excited state and the D₀ cationic ground state were assigned, with most active modes corresponding to in-plane benzene ring vibrations. Structural analysis reveals that the benzene ring undergoes slight expansion upon S₁ ← S₀ excitation and contraction upon D₀ ← S₁ ionization, while the overall molecular geometry remains remarkably similar across all three electronic states, a key factor underlying the excellent agreement between experimental and simulated Franck–Condon spectra. Comparison with m-methoxyphenol demonstrates that the stronger electron-donating ability of the ethoxy group leads to systematically lower excitation and ionization energies. The distinct spectroscopic fingerprints established herein provide a definitive reference for identifying specific m-ethoxyphenol rotamers in future studies of this molecule and its complexes. Full article

Background: Vancomycin (VAN)-induced nephrotoxicity limits its clinical application. Licorice (Glycyrrhiza uralensis Fisch.) and its bioactive constituents have been reported to protect against nephrotoxicity induced by various nephrotoxic agents. This study aimed to evaluate the protective effects of licorice against VAN-induced nephrotoxicity and to explore the underlying mechanisms both in vivo and in vitro. Methods: Seven groups of male C57BL/6 mice received different treatments for 7 consecutive days. Blood, fecal and renal tissue samples were collected for the assessment of serum creatinine, renal histopathology, mitochondrial ultrastructure, oxidative stress markers, kidney injury molecule-1 (Kim-1), short-chain fatty acids (SCFAs), and uremic toxins. In human proximal tubular epithelial cells (HK-2 cells), the effects of licorice on cell viability, oxidative stress, inflammatory markers, and mitochondrial membrane potential (MMP) were further investigated. Results: Licorice significantly attenuated VAN-induced nephrotoxicity and restored glutathione peroxidase (GSH-Px) activity while reducing malondialdehyde (MDA) levels. In addition, licorice markedly ameliorated VAN-induced renal histopathological injury, as demonstrated by hematoxylin and eosin staining and transmission electron microscopy. Licorice also reversed VAN-induced intestinal microbiota dysbiosis and increased the relative abundance of SCFA-producing bacteria, including Bacteroides. Moreover, licorice treatment increased fecal SCFA contents and modulated multiple uremic toxins in both serum and renal tissue. Consistently, licorice protected HK-2 cells against VAN-induced cytotoxicity by regulating GSH, interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and MMP. Conclusions: These findings demonstrate that licorice exerts protective effects against VAN-induced nephrotoxicity in vivo and in vitro, suggesting the potential involvement of oxidative stress, mitochondrial structure and function, inflammation, intestinal microbiota-SCFAs and uremic toxins. Full article