Search Results (396)

Freeze–thaw cycles lead to undesirable gelation in egg yolk, which negatively affects its functional properties, restricting its application in the food industry. This study aimed to investigate whether enzymatic treatment can prevent the freeze-induced gelation of egg yolk, thereby maintaining its desirable quality attributes. Egg yolk samples were treated with an enzyme preparation (Biocatalysts Flavorpro™ 750MDP) at concentrations of 0.05, 0.3, and 0.5 w/w%, homogenized, and incubated at 40 °C for 120 min, followed by rapid cooling and freezing at −24 ± 1 °C for 60 d. Control samples without enzyme treatment were subjected to the same processing steps as the other samples. After thawing, all samples were analyzed for pH, color, rheological and thermophysical properties, turbidity and visual appearance. The results demonstrated that although enzymatic treatment and its combination with freezing significantly altered color, turbidity, rheological and thermophysical properties of egg yolk, it effectively inhibited freezing-induced gel formation, particularly at 0.3 w/w%. The parameters characterizing rheological behavior—yield stress, consistency coefficient, and flow behavior index—were preserved close to those of fresh yolk after the freeze–thaw process. These findings suggest that exopeptidase treatment is a promising approach for controlling freeze–thaw-induced gelation in egg yolk, supporting its wider use in frozen and processed egg products. Full article

Effective teaching and learning in classrooms are achievable only through sound classroom management. While positive attitudes and behaviors exhibited by faculty members enhance instructional quality, undesirable behaviors may impede and negatively influence the teaching–learning process. The purpose of this study is to examine the undesirable behaviors displayed by faculty members in classroom settings based on the perspectives of pre-service teachers. The study adopted a phenomenological design and was conducted with 95 pre-service teachers enrolled in the Classroom Management course at the Faculty of Education, Çanakkale Onsekiz Mart University. Data were collected through a semi-structured interview form and analyzed using content analysis. The findings revealed that undesirable faculty members’ behaviors were characterized as actions stemming from instructors’ inadequacies that negatively affect students and the overall educational process. These behaviors were categorized under four themes: instructional management, time management, communication management, and behavior management. The results indicated that undesirable behaviors predominantly originate from instructor-related factors. Pre-service teachers reported experiencing such behaviors most frequently within the theme of behavior management. These behaviors primarily diminish their motivation and negatively influence their participation and academic performance. Pre-service teachers emphasized the need for both institutional and individual measures to prevent undesirable faculty members’ behaviors. Full article

Background/Objectives: The uprighting of mesially tipped mandibular second molars following first molar loss is a complex surgical and orthodontic challenge. Conventional methods often result in reciprocal anchorage loss. Mini-implants (MIs) have emerged as essential temporary anchorage devices (TADs) that provide absolute anchorage and enable more predictable tooth movements. Methods: Numerical simulations were performed to evaluate the forces required for mandibular second molar uprighting under two conditions: first, only with the second molar present, and second, with both the second and the third molars present. Although the periodontal ligament exhibits nonlinear and viscoelastic behavior in vivo, a linear elastic approximation was adopted to allow for a reliable evaluation of comparative stress distribution and initial displacement patterns within the scope of this exploratory biomechanical study. Stress distribution in the roots, periodontal ligament, and alveolar bone was assessed for each scenario. Two three-dimensional (3D) models of the left mandibular segment were created from scans of a human mandible and its teeth. The first model included the canine, the first and second premolars, and the second molar. A second model additionally incorporated the third molar. A retromolar MI was placed in both models. Molar uprighting was simulated using a spring connecting the implant to a button bonded on the mesial surface of the second molar. A force of 200 g was applied because in clinical orthodontic practice, forces that exceed approximately 2 N may cause pain or undesirable tooth mobility. Displacements along the X, Y, and Z axes, as well as regions of peak stress, were analyzed. Results: Model 1 showed maximum displacements at the furcation/mid-root, distal root apex, and distal crown, with von Mises stresses of 0.470 to 0.371 MPa. In Model 2, peak displacements occurred at the mesial root and crown, with stresses of 0.185 and 0.149 MPa, respectively. The magnitude of displacements was in the order of 10⁻⁵ mm. Such values represent initial mechanical responses rather than clinically observable tooth movements. However, the differences between models (e.g., the stress reduction) are expected to be clinically meaningful. Conclusions: Since clinical measurements regarding the stress distribution on teeth and surrounding tissues during orthodontic molar uprighting movements are impossible to perform, the finite element method (FEM) can offer insight into these aspects. The presence of the third molar significantly modulates the biomechanics of second molar uprighting via retromolar MIs. When the third molar is present, the second molar exhibits a reduced tendency for deformation during distalization, although this leads to a slower displacement. This FEM provides biomechanical insights but does not support direct clinical decision-making. The present findings should be viewed as theoretical biomechanical tendencies that require confirmation through clinical, experimental, and longitudinal studies before translation into clinical practice. Full article

Introduction: Pediatric asthma is the inflammatory condition with the highest burden of chronic disease in children. Awareness of the undesirable effects of modern lifestyles, including sedentary behavior and eating habits associated with Western diets, has led to novel approaches in clinical practice. Current concerns focus on the possibility of non-pharmacological intervention to achieve better disease control and normal lung function in these children. Method: In this narrative review, we analyzed current information on the influence of dietary patterns on lung function. The aim was to clarify the extent to which current knowledge provides arguments for applying certain dietary measures to asthma patients in order to optimize lung function. We conducted research in the literature to evaluate the impact of Western diet, Mediterranean diet, and micronutrients status on lung function. We also focused on how maternal diet during pregnancy can influence lung function in offspring. Results: We found a positive impact on lung function in children who adhere to the Mediterranean diet, in contrast to the Western diet which is related to low asthma control. Deficits of micronutrients like selenium, zinc, iron, and vitamin D are linked to impaired lung function. Maternal intake of fiber, vitamin A, vitamin E, zinc, and selenium during pregnancy is correlated with better FEV1 and FVC. However, current information on this topic is controversial, and there is no clear data on intervention measures in clinical practice. Conclusions: Evaluation and clear recommendations of diet could contribute to a better management of children with asthma. Full article

Photothermal superhydrophobic surfaces represent a promising solution for passive anti-icing; however, the persistent high solar absorption of static black coatings often leads to undesirable overheating under non-icing conditions. To address this limitation, we developed a smart superhydrophobic polydimethylsiloxane (PDMS) surface embedded with thermochromic capsules (TC) (S-PDMS/TC) featuring reversible thermochromic capability via a facile combination of spin-coating and femtosecond laser ablation. The resulting hierarchical micro-grid structure acts as a sacrificial layer, shielding fragile nanostructures against mechanical abrasion, while endowing the surface with robust superhydrophobicity (contact angle > 155°). Uniquely, S-PDMS/TC exhibits an adaptive color transition from pale yellow to deep black when the temperature drops below 5 °C. This response enables on-demand photothermal enhancement, significantly boosting solar absorption in freezing environments while minimizing heat absorption at room temperature. Consequently, S-PDMS/TC demonstrates superior anti-icing performance, extending the freezing time to 310 s and reducing ice adhesion strength to 40.4 kPa. Notably, during photothermal de-icing, the meltwater exhibits spontaneous dewetting behavior driven by the replenishment of the air cushion, effectively preventing secondary icing. This work presents a mechanically durable and intelligent strategy for ice protection, successfully balancing efficient de-icing with thermal management. Full article

The clinker grinding stage in Portland cement production is highly energy-intensive, primarily due to particle agglomeration and intensified interparticle attractive forces that hinder efficient comminution. Grinding aids (GAs) are routinely employed to mitigate these issues, enhancing grinding efficiency and improving cement performance. However, the undesirable side effects associated with conventional GAs on cementitious systems have spurred interest in modification strategies that can concurrently optimize grinding efficiency and final product quality. In this study, widely used commercial GAs, triisopropanolamine (TIPA), diisopropanolamine (DEIPA), and diethylene glycol (DEG), were chemically modified via esterification with organic acids of different carbon chain lengths. Cement specimens incorporating these modified GAs were produced at two dosages (0.05% and 0.1% by mass of clinker + gypsum), resulting in 24 distinct Portland cement formulations alongside a control mix. The influence of modification on grinding efficiency, particle size distribution (PSD), and powder flowability was investigated. Furthermore, scanning electron microscopy (SEM) was utilized to analyze particle morphology and concrete microstructural characteristics with powder flow behavior. The results indicate that organic acid modification not only facilitates achieving target fineness with lower energy consumption but also markedly improves both the PSD profile and the powder’s flow properties. Specifically, hexanoic acid-modified TIPA and DEIPA, along with propanoic acid-modified DEG, delivered the most favorable outcomes across the evaluated parameters. These findings underscore the potential of developing next-generation, modified GAs that simultaneously enhance energy efficiency and powder handling in cement grinding operations. Full article

In Hungary, a fast-growing Empress tree hybrid (×Paulownia Clone in vitro 112) also known as Smaragdfa^® has been developed as a low-density plantation species seeking industrial utilization. Many potential industrial applications presuppose its bonding. The presence of adhesives in bonded layered assemblies, with differing climatic conditions on the internal and outer side, may induce undesired internal strains due to restricted water vapor diffusion, especially in the case of Smaragdfa as a low-density wood species. For decades, lasures have been specifically formulated with a molecular structure that allows partial vapor transmission while hindering water diffusion. Lasure-coated samples were used as control samples to identify, among the different custom-made MW adhesives, the one with diffusion properties closest to those of the lasure. Uncoated Smaragdfa wood samples were used as the baseline reference to evaluate the effect of different adhesive and coating systems on water vapor diffusion. Smaragdfa samples were prepared both uncoated and coated with different adhesive and lasure layers. Experiments were conducted following ISO 12572 and ASTM E96 standards using the cup method, with all specimens pre-conditioned to 12% moisture content. Results showed that the uncoated Smaragdfa exhibited the highest diffusion coefficient (δ = 7.02 × 10⁻¹³ kg/(m·s·Pa)) and flow rate (G = 0.055763 g/h), while the commercial adhesive-coated sample displayed an 84% reduction in diffusion capacity (δ = 1.15 × 10⁻¹³ kg/(m·s·Pa)), indicating a strong vapor-blocking effect. The lasure coating allowed partial vapor transmission, confirming its semi-permeable nature. Adhesives formulated with varying polyol molecular weights (Series 1–5) revealed a clear molecular-weight-dependent diffusion behavior: low-MW systems (S1) acted as strong diffusion barriers comparable to lasure-coated samples (SMW_L), in the same time high-MW systems (S4, S5) permitted excessive diffusion but induced microcracking, while intermediate formulations (S2, S3) achieved the most balanced performance, combining moderate diffusion with structural stability. Overall, the findings confirm that adhesive layers significantly influence water vapor transmission through Smaragdfa wood, with the degree of hindrance closely related to the molecular weight of the polyol matrix. The optimized formulations (S2, S3) demonstrate promising potential for use in bonded assemblies and engineered wood products where controlled vapor diffusion and mechanical reliability are critical in order to support reduced strains caused by water vapor. Full article

In fundamental physics, sensors operating below liquid helium temperatures are highly vulnerable to vibrations, which can affect the sensitivity, for example, of high-performance particle detectors. Pulse-tube refrigerators, while generating vibrations lower than those of conventional systems, may still introduce several disturbances. Hence, flexible thermal connections are a commonly used mechanical solution to mitigate these undesirable effects. Among the materials that can be used, ultra-high-purity aluminum (UHP-Al) has attracted the attention for low-amplitude-vibration cryogenic applications, including gravitational wave interferometry, quantum information systems, precision space instrumentation, and cryogenic resonators. Thus, the aim of the paper is the characterization of the mechanical and microstructure properties of three UHP-Als (i.e., 5N—99.999 wt%, 5N5—99.9995 wt% and 6N—99.9999 wt%) intended for the production of thermal flexible connections with low stiffness, specifically designed to reduce vibration transmission in cryogenic environments. Mechanical properties were evaluated through standard tensile tests from room (+25 °C) to low temperature (i.e., −150 °C), providing insights into yield strength, ultimate tensile strength, elongation and elastic modulus. In addition, the dynamic elastic modulus of material loads, at cryogenic conditions (i.e., about −180 °C), was determined by measuring the natural resonance frequency, thereby assessing the material’s response to vibrational. Moreover, an extensive microstructural analysis was conducted using electron backscatter diffraction and x-ray diffraction. The correlation between the observed microstructure and the elastic properties was systematically examined. The results underscore the pivotal role of microstructural characteristics in dictating the elastic behavior of UHP Als. Eventually, the analysis provides valuable guidelines for the materials employment inside cryogenic systems, where severe vibration control is critical to maintain high operational performance. Full article

This article presents a mathematical analysis of the geometric continuity of industrial robot trajectories, highlighting the influence of continuity conditions on velocity, acceleration, and vibration profiles. This study proposes an original approach: isolating geometric continuity as an independent parameter and the comparative evaluation of the continuity levels C¹, C², and C³ using a series of pre-computed kinematic metrics: vibration energy, acceleration variability, and trajectory curvature stability. The methodology is validated by numerical simulations performed with RoboDK for trajectory generation and by post-processing in Python for metric evaluation. The results indicate that C¹ trajectories exhibit discontinuities in the higher-order derivatives, which lead to undesirable kinematic behaviors, while C² continuity represents the minimum requirement for an acceptable, stable motion in industrial applications. Higher-order continuity, C³, brings greater regularity to the trajectories, but the practical advantages are limited and relatively insignificant for standard industrial applications. Full article

Oxidation of oils is a free-radical cascade of reactions leading to the formation of undesirable odors and tastes, nutrient degradation, and potentially harmful compounds. To better understand the oxidation process, the kinetic parameters were examined depending on the degree of conversion (0 ≤ α ≤ 1) in this study. This approach provides insight into the complexity of the oxidative mechanism and allows a more reliable evaluation of the oxidative stability of nettle seed oil and its behavior during thermal treatment. A non-isothermal DSC method was applied, and kinetic parameters including the activation energy (Ea), the pre-exponential factor (A), and the reaction rate constant (k) were evaluated by applying the isoconversional Ozawa–Flynn–Wall method. Based on kinetic parameters, a simulation of oil oxidation at constant temperature (22 °C) was performed and the oil induction time was estimated. This value was compared to the ones obtained by OXITEST method. The observed conversion-dependent kinetic parameters demonstrate the complex oxidation behavior of nettle seed oil and justify the application of conversion-sensitive kinetic models to accurately describe its thermal stability. The induction period obtained under accelerated oxidation conditions suggests satisfactory oxidative stability of oil and highlights its potential suitability for nutritional and functional applications. Full article

The oxidative stability of meat products is a crucial factor determining quality, shelf life, and consumer acceptance, as lipid and protein oxidation promote undesirable changes in sensory attributes and nutritional content. Antioxidant capacity (AOC) assays such as total phenolic content (TPC), ferric reducing antioxidant power (FRAP), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^•+), and 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) are commonly applied in meat systems to assess the AOC associated with both intrinsic muscle components (endogenous) and the protective effects of natural ingredients (exogenous added compounds), i.e., antioxidants. Although differences in analytical methodologies limit direct comparisons among studies, it has been demonstrated that meat products inherently contain compounds that modulate oxidative reactions, with their effectiveness influenced by meat type, processing, and storage conditions. Within this framework, natural ingredients, including plant- and fungal-derived ingredients and their by-products, have gained attention as sources of natural antioxidants, whose capacity depends on the extraction method, the solvent used, and their behavior during gastrointestinal digestion, as evaluated using simulated gastrointestinal digestion (sGD) models. Numerous studies have shown that incorporating natural extracts or powders into meat products enhances AOC during refrigerated storage, with the effect generally depending on the concentration used. Moreover, several natural antioxidant treatments maintain or even enhance their AOC when assessed under sGD conditions. Full article

The LLC resonant converter constitutes a high-order switching system characterized by multiple operational modes and region-dependent switching sequences. This complexity poses significant challenges to system modeling and dynamic analysis. Furthermore, its inherent high-order nonlinearity tends to induce detrimental nonlinear phenomena, including bifurcation and chaos, which are particularly undesirable in power electronic systems that demand the utmost priority for stability and reliability. To address these concerns, this work focuses on investigating the dynamic behaviors and stability of LLC resonant converter control systems. This study aims to elucidate the origins and evolution of these nonlinear characteristics, thereby facilitating the design of higher-performance power electronic systems. First, a continuous-time model of the closed-loop controlled LLC resonant converter system was established using the sigmoid function modeling method. This model allows direct application of continuous system theory to analyze dynamic behavior, significantly reducing analytical complexity. Second, the system’s bifurcation characteristics and stability were comprehensively investigated through Floquet theory, bifurcation diagrams, and Lyapunov exponent spectra. Results reveal that PFM-controlled LLC resonant converters exhibit rich nonlinear dynamics under variations in key parameters. Experiments successfully captured the observed nonlinear phenomena, validating the evolution of system dynamics and stability. This work provides a novel perspective for stability analysis and parameter design in multi-resonant converter systems. Full article

The aging population and increasing prevalence of oxidative stress-related diseases underscore the need for functional food and pharmaceutical formulations enriched with bioactive compounds. This study aimed to design sustainable emulsion systems incorporating enzymatically modified fats with enhanced functional and bioactive properties. Enzymatic interesterification was employed as an environmentally friendly alternative to chemical catalysis, enabling the transformation of natural lipids without generating undesirable trans isomers. The lipid phase was formulated from blends of hemp oil, a plant-derived source rich in polyunsaturated fatty acids with documented antioxidant potential, and mutton tallow, in an effort to valorize meat industry by-products. Systematic evaluation of emulsion stability, viscosity, and textural properties was conducted using Turbiscan analysis and texture profile analysis. The results demonstrated that xanthan gum concentration was the primary determinant of structural stability, physicochemical stability, and structural integrity of the emulsion systems. Formulation no. 38 (0.8% w/w xanthan gum) was identified as the statistically most stable system based on Turbiscan Stability Index values (TSI = 1.4). Although emulsions containing 1.0% w/w xanthan gum exhibited similarly low TSI values and slightly smaller final droplet diameters, formulation E38 showed the smallest increase in droplet size during storage (<1 µm), indicating superior resistance to structural changes over time. Fat composition showed minimal influence on emulsion behavior, suggesting that lipid selection should prioritize nutritional and bioactive value. These findings indicate that emulsions based on enzymatically modified fats and stabilized with natural polysaccharides can serve as physically stable systems with potential applicability in food, cosmeceutical, and pharmaceutical formulations intended for bioactive compound delivery. Full article

Modern power transmission systems are required to meet increasingly stringent demands, including a wide range of transmission ratios, compact dimensions, high precision, energy efficiency, reliability, and thermal stability under dynamic operating conditions. Among the solutions that satisfy these requirements, cycloidal reducers are particularly prominent, with their application continuously expanding in industrial robotics, computer numerical control (CNC) machines, and military and transportation systems, as well as in the satellite industry. However, as with all mechanical power transmissions, friction in the contact zones of load-carrying elements in cycloidal reducers leads to power losses and an increase in operating temperature, which in turn results in a range of adverse effects. These undesirable phenomena strongly depend on lubrication conditions, namely on the type and properties of the applied lubricant. Although manufacturers’ catalogs provide general recommendations for lubricant selection, they do not address the fundamental tribological mechanisms in the most heavily loaded contact pairs. At the same time, the available scientific literature reveals a significant lack of systematic and experimentally validated studies examining the influence of lubricant type on the energetic and thermal performance of cycloidal reducers. To address this identified research gap, this study presents an analytical and experimental investigation of the effects of different lubricant types—primarily greases and mineral oils—on the thermal stability and efficiency of cycloidal reducers. The results demonstrate that grease lubrication provides lower total power losses and a more stable thermal operating regime compared to oil lubrication, while oil film thickness analyses indicate that the most unfavorable lubrication conditions occur in the contact between the eccentric bearing rollers and the outer raceway. These findings provide valuable guidelines for engineers involved in cycloidal reducer design and lubricant selection under specific operating conditions, as well as deeper insight into the lubricant behavior mechanisms within critical contact zones. Full article

With the widespread diffusion of personal Internet of Things (IoT) devices, Electromagnetic Side-Channel Attacks (EM-SCAs), which exploit electromagnetic emissions to uncover critical data such as cryptographic keys, are becoming extremely common. Existing shielding approaches typically rely on bulky or opaque materials, which limit integration in modern IoT environments; this motivates the need for a transparent, lightweight, and easily integrable solution. Thus, to address this threat, we propose the use of electromagnetic metasurfaces with shielding capabilities, fabricated with an optically transparent conductive film. This film can be easily integrated into glass substrates, offering a novel and discrete shielding solution to traditional methods, which are typically based on opaque dielectric media. The paper presents two proof-of-concept case studies for shielding against EM-SCAs. The first one investigates the design and fabrication of a passive metasurface aimed at shielding emissions from chip processors in IoT devices. The metasurface is conceived to attenuate a specific frequency range, characteristic of the considered IoT processor, with a target attenuation of 30 dB. At the same time, the metasurface ensures that signals from 4G and 5G services are not affected, thus preserving normal wireless communication functioning. Conversely, the second case study introduces an active metasurface for dynamic shielding/transmission behavior, which can be modulated through diodes according to user requirements. This active metasurface is designed to block undesired electromagnetic emissions within the 150–465 MHz frequency range, which is a common band for screen gleaning security threats. The experimental results demonstrate an attenuation of approximately 10 dB across the frequency band when the shielding mode is activated, indicating a substantial reduction in signal transmission. Both the case studies highlight the potential of transparent metasurfaces for secure and dynamic electromagnetic shielding, suggesting their discrete integration in building windows or other environmental structural elements. Full article