Search Results (148)

Objectives: The aim of this study was to compare the effects of eight-week hamstring stretching programs, implemented at different times during physical education classes (i.e., warm-up, cool-down, and both periods), on primary schoolchildren’s back-saver sit-and-reach scores. Methods: A total of 275 schoolchildren (141 females and 134 males; age 8.82 ± 1.63 years) were divided into four groups: the WUG performed stretching during warm-up, the CDG during cool-down, and the MXG during both. The NSG followed the standard classes of physical education without any stretching. During physical education classes WUG, CDG, and MXG performed a 4 min stretching program twice a week. Hamstring extensibility was assessed before and after the program using the back-saver sit-and-reach test. Results: The CDG is the one that achieved statistically significant improvements compared with the WUG, MXG, and NSG (p ≤ 0.01; d = 0.50–0.71). Moreover, the CDG statistically increased the percentage of schoolchildren achieving healthy hamstring extensibility from pre-intervention (49%) to post-intervention (66%). Conclusions: This knowledge could guide teachers to design programs that guarantee feasible and effective development of hamstring extensibility in the physical education setting. Full article

Due to the increase in global energy demand, as well as environmental concerns, hydrogen presents itself as a promising energy source. Liquid hydrogen is more suited for long-distance transportation, but hydrogen liquefaction is an energy-intensive process, and many studies have been published proposing more efficient liquefaction cycles. In this study, simple hydrogen liquefaction cycles like Claude, pre-cooled Linde–Hampson (PLH), single mixed refrigerant (SMR), and dual mixed refrigerant (DMR) were assessed regarding the influence of the cycle’s high pressure on energy efficiency, exergy destruction, and its distribution along the equipment. Among the main results, Claude presented the best specific energy consumption (SEC) of 16.47 kWh/kg_LH, followed by DMR with an SEC of 17.30 kWh/kg_LH, SMR with 17.58 kWh/kg_LH, and finally PLH, with an SEC of 45.07 kWh/kg_LH. The exergy efficiency followed the same pattern as the SEC, with Claude having the lowest exergy destruction, followed by DMR and SMR with close exergy destruction, and finally PLH. Nonetheless, although cycles were not optimized in evaluating the effect of increasing the high pressure, which constrains the direct applicability of the result found, especially in the pre-cooled cycles, the analysis provides valuable insights into the sensitivity of cycle performance. The method and its findings provide the basis for further studies, including optimization steps. Full article

As an important component of the Stirling-type pulse tube cryocooler (SPTC), an efficient phase shifter can significantly improve the cooling capacity. This paper combines the advantages of the cold inertance tube and reservoir (ITR) and the active warm displacer (AWD) in an 8 K Stirling-type pulse tube cryocooler. Through numerical simulation methods, the influence of structural parameters of the cold ITR and operating parameters of AWD on acoustic power and impedance was studied. The results indicate that the length and diameter of the inertance tube, as well as the displacement and phase of the AWD, will affect the distribution of PV power inside the middle heat exchanger. The impedance distribution inside the pulse tubes of the higher-temperature section and the lower-temperature section changes in opposite directions. Through experiment, the effectiveness of the cold ITR and the adjustment function of the AWD were verified. A cooling capacity of 74 mW at 8 K can be obtained with the electric power of 177.5 W and a precooling capacity of 9.1 W/70 K. The AWD has a significant adjustment effect on T1 and T2, reaching the lowest no-load temperature at 2.13 mm and 48°, respectively, with a minimum no-load temperature of 5.13 K. Full article

Background/Objectives: Emulsion-based semisolid formulations are important delivery systems for many applications, including pharmaceuticals, cosmetics and food. The manufacturing process for such formulations typically involves a series of heating, cooling, mixing and emulsification steps. Stabilizing agents are usually included in such formulations, as emulsions are intrinsically unstable and are prone to various destabilization mechanisms. Precise control of each processing parameter and the selection of an appropriate stabilizing agent are essential for delivering products with long-term stability and the desired properties. In this study, the effects of emulsification temperature and the selection of the stabilizing agent on key product attributes were investigated to enable improved design and optimization of both the formulation and manufacturing process. Methods: Model emulsion systems containing propylene glycol (PG) as the dispersed phase and mineral oil as the continuous phase were prepared at different emulsification temperatures to cover both pre-crystallization and post-crystallization regimes. Three stabilizing agents, namely mono-and-diglyceride (MDG), neat monoglyceride (MG) and neat diglyceride (DG), were studied. Their crystallization behavior was first examined to determine crystallization temperatures and crystal morphologies. The resulting emulsion samples were then characterized in terms of their microstructure, physical stability and rheological properties. Results: The emulsions prepared under post-crystallization conditions exhibited better physical stability, higher rheological parameters (crossover stress and viscosity) and a more rigid microstructure compared to those formed under pre-crystallization conditions, regardless of the stabilizer used. Rheological properties were found to corelate well with physical stability. In the pre-crystallization regime, poor stability could partially be mitigated by lowering the emulsification temperature. MG was generally more effective than DG in stabilizing the emulsions and led to higher rheological properties, despite both crystallizing into the same polymorph within the system. This difference in performance was attributed to variations in the crystal morphology and spatial distribution within the emulsion. Notably, the MG-stabilized emulsions also displayed a self-hardening effect during storage. Conclusions: The selection of the appropriate stabilizing agents and processing conditions tailored to the specific system is critical for the successful manufacture of emulsion-based semisolid products with an optimized performance. Full article

The urban thermal environment poses a significant challenge to public health and sustainable urban development. Conventional pre-defined classification schemes, such as the Local Climate Zone (LCZ) system, often fail to capture the highly heterogeneous structure of complex urban areas, thus limiting their applicability. This study introduces a novel framework for urban thermal environment analysis, leveraging multi-source data and eXplainable Artificial Intelligence to investigate the driving mechanisms of Land Surface Temperature (LST) across various urban form types. Focusing on the area within Beijing’s 5th Ring Road, this study employs a K-Means clustering algorithm to classify urban blocks into nine distinct types based on their building morphology. Subsequently, an eXtreme Gradient Boosting (XGBoost) model, coupled with the SHapley Additive exPlanations (SHAP) method, is utilized to analyze the non-linear impacts of ten selected driving factors on LST. The findings reveal that: (1) The Compact Mid-rise type exhibits the highest annual average LST at 296.59 K, with a substantial difference of 11.29 K observed between the hottest and coldest block types. (2) SHAP analysis identifies the Normalized Difference Built-up Index (NDBI) as the most significant warming factor across all types, while the Sky View Factor (SVF) plays a crucial cooling role in high-rise areas. Conversely, road density (RD) shows a negative correlation with LST in Open Low-rise areas. (3) The influence of urban form is twofold: increased building height (BH) can induce warming by trapping heat while simultaneously providing a cooling effect through shading. (4) The impact of land use functional zones on LST is significantly modulated by urban form, with temperature differences of up to 2 K observed between different functional zones within compact block types. The analytical framework proposed herein holds significant theoretical and practical implications for achieving fine-grained thermal environment governance and fostering sustainable development in the context of global urbanization. Full article

Actinidia arguta (kiwiberry) is a fruit with significant health benefits, and research continues to identify factors that enhance its storability while maintaining quality. Special attention is given to antioxidant metabolism and total antioxidant activity. In this study, four cold-storage conditions were tested: normal air, normal air with ozone, modified atmosphere, and controlled atmosphere. In each case, the fruit was either pre-cooled before storage or not. The aim was to identify conditions most favorable to preserving internal and external fruit quality over time. Taking into account most of the basic fruit physicochemical traits tested, it can be assumed that for up to 30 days of storage, each storage method can be useful to store A. arguta fruit. After this period, the fruit stored in a controlled and then modified atmosphere retained the highest and acceptable firmness. Changes in antioxidant content are more complex and depend on the type of compound, storage time, and fruit post-harvest treatment. During the 50-day storage period, marked fluctuations in ascorbate, glutathione, and L-cysteine levels were observed at 10-day intervals. Phenolic content increased initially (after 10 days) and then stabilized. Among the methods used, ozonation led to a relative stabilization or increase in antioxidant content. This method, like the cooling procedure, requires further detailed research to determine its suitability for the species/variety being tested. Changes in antiradical activity were reaction-mechanism-dependent. The activity based on single electron transfer consistently decreased, while that based on hydrogen atom transfer was more stable overall. Contrary to this, the pro-oxidative Fe(II) chelating agent appeared during storage. The health-promoting properties of stored fruit may fluctuate due to antioxidant involvement in adaptation to storage conditions and uneven ripening, which remains a challenge both at harvest and during storage. Any of the three alternatives to cold storage in CA (NA, NA+O, MA) proved beneficial in short-term storage. However, MA has proven to be a similarly effective long-term storage method to CA in terms of the physicochemical quality of A. arguta fruit. Full article

Conventional strengthening measures for existing structures are usually not effective for the self-weight, which accounts for around 70% of the total load in reinforced concrete structures. Therefore, their effect on the overall load-bearing capacity is low. A self-weight-effective alternative for flexural strengthening is the thermal prestressing of additional reinforcement installed on the structure. In this method, reinforcing bars are slotted into the tensile zone, embedded in filler material, and tempered from the outside. They are thermally stretched, and once cooling starts, the bond with the hardened filler prevents re-deformation. The induced prestressing force counteracts dead loads and relieves the tensile zone, making the additional bars effective for the self-weight. In this paper, the effectiveness of the strengthening method is experimentally investigated in the serviceability and the ultimate limit states. Experiments involve strengthening a reinforced concrete beam under load by a thermally prestressed additional bar. Moreover, two reference tests are made to evaluate the method. An unstrengthened beam characterizes the lower capacity limit. Another beam with the same reinforcement amount as the strengthened one, but completely installed at casting, serves as the upper benchmark. All beams are loaded until bending failure. The strengthening method is assessed by means of the load-bearing behavior, deflection, crack development, and the strains in the initial as well as the added reinforcement. The results demonstrate the effectiveness of the strengthening method. The thermally prestressed bar achieves an effective pre-strain of approximately. 0.4‰ by heating at about 70 °C. The induced prestressing force and associated compression reduce tensile cracks by approx. 45% and increase stiffness. The strengthened beam reaches the maximum load of the upper benchmark, but with about 33% less deflection. The filler, which also expands thermally, generates an additional prestressing force that is effective up to about 20% of the load capacity. Beyond this, the filler begins to crack and its effect decreases, but the pre-strain in the reinforcing bar remains until maximum load. Full article

Objectives: There is a critical need for effective focal therapies for patients with inoperable or anatomically complex tumors where conventional ablation techniques pose high risk or are ineffective. Integrated Nanosecond Pulsed Irreversible Electroporation (INSPIRE) is a novel non-thermal ablation modality which uses real time temperature feedback during pulse delivery to safely treat tumors near critical structures. This study evaluated the impact of exposed electrode length on ablation zone size, reproducibility, and cardiac safety in a large animal model. Methods: INSPIRE treatments were performed in an in vivo healthy porcine liver model. All treatments administered 6000 V 1000 ns pulses with a 45 °C temperature set point. Treatments were administered percutaneously via an electrode and grounding pad approach using an internally cooled electrode applicator. The exposed electrode region at the distal end of the applicator was set to either 0.5, 1.0, 1.5, or 2.0 cm. Ablation zones were assessed via ultrasound, contrast-enhanced CT, and gross pathology one week post-treatment. Cardiac safety was evaluated by measuring pre- and post-treatment serum Troponin levels. Results: All treatments were completed without adverse events. Troponin levels remained stable (pre: 0.249 ng/mL; post: 0.224 ng/mL), indicating no measurable cardiac injury. The 1.5 cm exposure length produced the largest and most consistent ablation volumes, with a mean volume of 12.8 ± 2.6 cm³ and average dimensions of 3.7 × 2.7 cm in under 6 min. Increasing exposure length beyond 1.5 cm introduced greater variability and reduced treatment volumes. Conclusions: INSPIRE enables safe, large-volume, single-applicator ablation without a need for electrical pulse synchronization with R wave in cardiac rhythm. The 1.5 cm exposure length offers optimal balance between energy delivery and treatment consistency. These findings support further clinical investigation of INSPIRE for non-thermal ablation of inoperable tumors. Full article

Strain monitoring during the service life of a nuclear containment structure is an effective means to evaluate whether the structure is operating safely. Due to the failure of embedded strain sensors, surface-mounted strain sensors should be installed on the outer wall of the structure. However, whether the data from these substitute sensors can reasonably reflect the internal deformation behavior requires further investigation. To ensure the feasibility of the added strain sensors, a refined 3D model of a Chinese Pressurized Reactor (CPR1000) nuclear containment structure was developed in ANSYS 19.1 to study the internal and external deformation laws during a containment test (CTT). Solid reinforcement and cooling methods were employed to simulate prestressed cables and pre-tension application. The influence of ordinary steel bars in concrete was modeled using the smeared model, while interactions between the steel liner and concrete were simulated through coupled nodes. The model’s validity was verified against embedded strain sensor data recorded during a CTT. Furthermore, concrete and prestressed material parameters were refined through a sensitivity analysis. Finally, the variation law between the internal and external deformation of the containment structure was investigated under typical CTT loading conditions. Strain values in the wall thickness direction exhibited an essentially linear relationship. Near the equipment hatch, however, the strain distribution pattern was significantly influenced by the spatial arrangement of prestressed cables. Refined FEM and sensor systems are vital containment monitoring tools. Critically, surface-mounted strain sensors offer a feasible approach for inferring internal stress states and deformation behavior. This study provides theoretical support and a technical foundation for the safe assessment and maintenance of nuclear containment structures during operational service. Full article

Hydrogen energy is valued for its diverse sources and clean, low-carbon nature and is a promising secondary energy source with wide-ranging applications and a significant role in the global energy transition. Nonetheless, hydrogen’s low energy density makes its large-scale storage and transport challenging. Liquid hydrogen, with its high energy density and easier transport, offers a practical solution. This study examines the global hydrogen liquefaction methods, with a particular emphasis on the liquid nitrogen pre-cooling Claude cycle process. It also examines the factors in the helium refrigeration cycle—such as the helium compressor inlet temperature, outlet pressure, and mass—that affect energy consumption in this process. Using HYSYS software, the hydrogen liquefaction process is simulated, and a complete process system is developed. Based on theoretical principles, this study explores the pre-cooling, refrigeration, and normal-to-secondary hydrogen conversion processes. By calculating and analyzing the process’s energy consumption, an optimized flow scheme for hydrogen liquefaction is proposed to reduce the total power used by energy equipment. The study shows that the hydrogen mass flow rate and key helium cycle parameters—like the compressor inlet temperature, outlet pressure, and flow rate—mainly affect energy consumption. By optimizing these parameters, notable decreases in both the total and specific energy consumption were attained. The total energy consumption dropped by 7.266% from the initial 714.3 kW, and the specific energy consumption was reduced by 11.94% from 11.338 kWh/kg. Full article

Solid–liquid phase change materials (PCMs) have attracted significant attention due to their high enthalpy, which enables superior energy storage density. However, it is difficult to maintain their original shapes in a molten state. Therefore, confining PCMs within porous materials is an important method, either through mixing molten polymers and PCMs or confining PCMs in pre-prepared porous materials (e.g., aerogels). The former method is straightforward and easy to execute but its stability is severely limited, and the latter is exactly the opposite. Herein, aerogel-confined functional liquid made via in situ solid–liquid host–guest composite strategy is reported. As a proof of concept, Nylon 66 and 1,6-hexanediol are selected as the solid and liquid phases, respectively. 1,6-hexanediol not only serves as a solvent to dissolve Nylon 66 but also induces sol–gel transition during the cooling process and acts as a PCM to store energy. Unlike aerogel-supported systems requiring multi-step processing, this approach integrates porous host formation and PCM encapsulation in one step. The resulting shape-stabilized PCMs (ss-PCMs) exhibit obscure leakage, high latent heat (160 J/g), mechanical robustness (compressive modulus of 3.6 MPa), and low thermal conductivity (0.081 W/(m·K)) above 75 wt% loading of 1,6-hexanediol. These ss-PCMs enable infrared stealth by delaying thermal detection and passive thermal buffering that suppress temperature fluctuations. The in situ solid–liquid host–guest composite strategy is straightforward, being achievable through a one-pot method involving heating and cooling cycles, with high raw material utilization and minimal waste generation, thus maximizing the conversion rate of raw materials into the final product. By combining the excellent liquid retention capability of aerogels with process simplicity, this methodology opens new avenues for the development of ss-PCMs. Full article

Introduction: Extrinsic skin damage is often a result of oxidative stress caused by exposure to environmental factors such as ultraviolet (UV) radiation, ozone (O₃), and various pollutants. As a result, topical antioxidants have been evaluated for their effectiveness in mitigating or reversing skin damage caused by environmental factors. Topical antioxidants containing a combination of l-ascorbic acid, tocopherol, and ferulic acid have significantly improved markers of skin health after exposure to environment-induced skin damage. However, research suggests that l-ascorbic acid and tocopherol tend to be relatively unstable, possibly affecting their efficacy against outdoor stressor damage. It has been shown that ferulic acid significantly improves the stability of both l-ascorbic acid and tocopherol, but its long-term stabilization effects on these antioxidants are relatively unknown. Material and Methods: This study evaluated the time-dependent effectiveness of a topical antioxidant mix containing 15% l-ascorbic acid, 1% tocopherol, and 0.5% ferulic acid (AOX) on UV-induced skin damage. Skin biopsies (12 mm, n = 60) were placed in a 6-well plate with medium and incubated at 37 °C and 5% CO₂ overnight. The day after, skin samples were pretreated with 10 µL of differently aged AOX (0-, 6-, 12-, and 36-month-old) and then exposed to different doses of UV light (100, 200, 400 mJ/cm²) daily over four days. AOX formulations were stored in a cool, dry, and dark place at approximately 20–22 °C during the whole study. This study evaluated 4-hydroxynonenal (4-HNE) and 8-hydroxy-2′-deoxyguanosine (8-OHdG) as oxidative damage and skin DNA damage markers, Collagen1 and Filaggrin as skin structure, and IL-8 and Nrf2 as inflammatory and defensive response. Results: UV exposure significantly increased oxidative and inflammatory markers in human skin explants affecting also filaggrin and collagen levels. However, pre-treatment with the antioxidant formulation, particularly in its younger formulations (0-, 6-, and 12-month-old), significantly reduced the damaging effect of UV. Additionally, all antioxidant formulations effectively mitigated UV-induced damage across all doses. Conclusions: Our results indicate that pre-treatment with this formulation consistently reduces UV-induced oxidative damage and DNA damage in human skin explants, regardless of the formulation age and the discoloration state. Although effective, the protective capacity of aged formulations may be reduced only when extreme UV exposure is tested, a condition that is unlikely to occur under typical environmental conditions. These results support ferulic acid as a stabilization agent for topical antioxidant mixtures. Full article

Background/Objectives: Cancer represents a significant health challenge, with high mortality and morbidity rates. Its diagnosis often triggers chronic stress, adversely affecting patient outcomes. Exercise has emerged as complementary therapy, enhancing treatment adherence and mitigating the side effects of chemotherapy. This study examines the effects of mild exercise during chemotherapy on patient anxiety. Methods: This prospective paired cohort study was conducted in the General Oncology Hospital of Kifisia “Agioi Anargyroi” in Athens, Greece. Adult cancer patients undergoing chemotherapy participated, excluding those with cognitive, hearing, or motor impairments, those who experienced side effects, or those who declined consent. Anxiety was measured before and after a 20-minute exercise routine performed during chemotherapy, using the Greek-translated State–Trait Anxiety Inventory (STAI). The exercise regimen included warm-up, full-body stretching, and cool-down exercises. Pre- and post-exercise scores were analyzed using the Wilcoxon signed-rank test. Results: Forty-five patients (20 women, 25 men; mean age 69.02 ± 10.62 years) with various cancer backgrounds participated. Pre-intervention anxiety levels were in the borderline “moderate” range, dropping post-exercise to the “low” range. Mean STAI scores decreased from 37.73 ± 13.33 to 32.00 ± 14.22 (p < 0.0001), with a medium-large effect size (Cohen’s d for paired samples = −0.646). No significant correlation was found between age and anxiety scores. Discussion: This study found a significant short-term reduction in anxiety, suggesting that incorporating mild exercise during chemotherapy may help in alleviating patient stress. The medium-to-large effect size supports the potential for meaningful short-term benefits. Conclusions: Incorporating mild exercise during chemotherapy may help reduce anxiety and psychological burden. These findings underscore the need for more comprehensive research in larger, more diverse populations to better understand the benefits of incorporating mild exercise during chemotherapy. Full article

This study investigates long-term land surface temperature (LST) trends along the shoreline of Lake Drūkšiai, a transboundary lake in eastern Lithuania that formerly served as a cooling reservoir for the Ignalina Nuclear Power Plant (INPP). Although the INPP was decommissioned in 2009, its legacy continues to influence the lake’s thermal regime. Using Landsat 8 thermal infrared imagery and NDVI-based methods, we analysed spatial and temporal LST variations from 2013 to 2024. The results indicate persistent temperature anomalies and elevated LST values, particularly in zones previously affected by thermal discharges. The years 2020 and 2024 exhibited the highest average LST values; some years (e.g., 2018) showed lower readings due to localised environmental factors such as river inflow and seasonal variability. Despite a slight stabilisation observed in 2024, temperatures remain higher than those recorded in 2013, suggesting that pre-industrial thermal conditions have not yet been restored. These findings underscore the long-term environmental impacts of industrial activity and highlight the importance of satellite-based monitoring for the sustainable management of land, water resources, and coastal zones. Full article

Users of technical blades expect new generations of tools to feature reduced power requirements for process and maximized tool life. The second aspect is reflected in the reduction in costs associated with the purchase of tools and in the reduction in process line downtime due to tool replacement. Meeting these demands is particularly challenging in cutting operations involving heterogeneous materials, especially when the processed raw material contains inclusions and impurities significantly harder than the material itself. This situation occurs, among others, during flatfish skinning operations analyzed in this paper, a common process in the fish processing industry. These fish, due to their natural living environment and behavior, contain a significant proportion of hard inclusions and impurities (shell fragments, sand grains) embedded in their skin. Contact between the tool and hard inclusions causes deformation, wrapping, crushing, and even chipping of the cutting edge of planar knives, resulting in non-uniform blade wear, which manifests as areas of uncut skin on the fish fillet. This necessitates frequent tool changes, resulting in higher tooling costs and longer operating times. This study provides a unique opportunity to review the results of in-service pre-implementation tests of planar knives in the skinning operation conducted under industrial conditions. The main objective was to verify positive laboratory research results regarding the extension of technical blade tool life through optimization of sharpening conditions during grinding. Durability test results are presented for the skinning process of fillets from plaice (Pleuronectes platessa) and flounder (Platichthys flesus). The study also examined the effect of varying cooling and lubrication conditions in the grinding zone on the tool life of technical planar blades. Sharpening knives under flood cooling conditions and using the hybrid method (combining minimum quantity lubrication and cold compressed air) increased their service life in the plaice skinning process (Pleuronectes platessa) by 12.39% and 8.85%, respectively. The increase in effective working time of knives during flounder (Platichthys flesus) skinning was even greater, reaching 17.7% and 16.3% for the flood cooling and hybrid methods, respectively. Full article