Search Results (1,385)

Reinforcing PLA composites with natural fibres is a prominent strategy for improving PLA’s properties while benefiting from its intrinsic biodegradation. However, these composites may be susceptible to an inefficient stress-transferring process due to the weak intermolecular interactions between PLA and natural fibres. A well-known practice is to incorporate coupling agents to improve polymer–fibre adhesion, such as carboxylic acids (CAs) and grafted copolymers. CAs are a more affordable and biodegradable option for improving PLA/natural fibre interface strength, resulting in a material with superior mechanical and thermal properties. In this context, this research discusses the potential use of mono (C6 and C8) and di (CC6 and CC8) carboxylic acids as coupling agents in PLA/pecan nutshells (PN) composites. PLA/PN composites with four different CAs were processed in a twin-screw extruder and subsequently injection moulded. The results indicated an increase in the flexural strength of the PLA due to the presence of PN in the neat composite. The use of CAs increased the storage modulus of PLA/PN composites, while C6 and CC8 reduced the PLA composite tan δ peak height. The PLA’s T_g in PLA/PN composite shifted to lower temperatures after the incorporation of CAs while increasing the PLA crystallinity degree. These results strongly suggested that besides acting as efficient coupling agents, these acids also exerted roles as nucleating agents and plasticisers. Full article

The administration of isolated mitochondria is a promising strategy for protecting cells from oxidative damage. This study aimed to identify mitochondrial characteristics that contribute to stronger protective effects. We compared two types of mitochondria isolated from C6 cells with similar ATP-producing capacity but differing in outer membrane integrity. To evaluate their stability in extracellular conditions, we examined their behavior in serum. Both types underwent mitochondrial permeability transition to a similar extent; however, under intracellular-like conditions after serum incubation, mitochondria with intact membranes retained more polarized mitochondria. Notably, mitochondria with intact outer membranes were internalized more efficiently than those with damaged membranes. In H9c2 cells, both types of mitochondria similarly increased intracellular ATP levels 1 h after administration under all tested conditions. When co-administered with H₂O₂, both suppressed oxidative damage to a comparable degree, as indicated by similar H₂O₂-scavenging activity in solution, comparable intracellular ROS levels, and equivalent preservation of electron transport chain activity. However, at higher H₂O₂ concentrations, cells treated with mitochondria possessing intact outer membranes exhibited greater survival 24 h after co-administration. Furthermore, when mitochondria were added after H₂O₂-induced damage and their removal, intact mitochondria conferred superior cell survival compared to damaged ones. These findings suggest that while both mitochondrial types exert comparable antioxidant effects, outer membrane integrity prior to administration plays a critical role in enhancing cell survival under conditions of oxidative stress. Full article

This study aimed to develop experimental filler-reinforced resin composites for vat-photopolymerization 3D printing and to evaluate the effects of filler addition on their mechanical, physicochemical, and bonding properties for dental restorative applications. Silanized nano- and/or micro-fillers were incorporated into acrylic resin monomers to formulate photocurable resins suitable for vat-photopolymerization. The rheological behavior of these liquid-state resins was assessed through viscosity measurements. Printed resin composites were fabricated and characterized for mechanical properties—including flexural strength, flexural modulus, and Vickers hardness—both before and after 8 weeks of water immersion. Physicochemical properties, such as water sorption, water solubility, and degree of conversion, were also evaluated. Additionally, shear bond strength to a resin-based luting agent was measured before and after artificial aging via thermocycling. A commercial dental CAD-CAM resin composite served as a reference material. Filler incorporation significantly improved the mechanical properties of the printed composites. The highest performance was observed in the composite containing 60 wt% micro-fillers, with a flexural strength of 168 ± 10 MPa, flexural modulus of 6.3 ± 0.4 GPa, and Vickers hardness of 63 ± 1 VHN, while the commercial CAD-CAM composite showed values of 152 ± 8 MPa, 7.9 ± 0.3 GPa, and 66 ± 2 VHN, respectively. Filler addition did not adversely affect the degree of conversion, although the relatively low conversion led to the elution of unpolymerized monomers and increased water solubility. The shear bond strength of the optimal printed composite remained stable after aging without silanization, demonstrating superior bonding performance compared with the CAD-CAM composite. These findings suggest that the developed 3D-printed resin composite is a promising candidate for dental restorative materials. Full article

Refining the land use structure can boost land utilization efficiency and curtail regional carbon emissions. Nevertheless, prior research has predominantly concentrated on static linear planning analysis. It has failed to account for how future dynamic alterations in driving factors (such as GDP and population) affect simulation outcomes and how the land use spatial configuration impacts the attainment of the carbon-neutrality goal. In this research, 1 km spatial resolution LULC products were employed to meticulously simulate multiple land use scenarios across China at the national level from 2030 to 2060. This was performed by taking into account the dynamic changes in driving factors. Subsequently, an analysis was carried out on the low-carbon land use spatial structure required to reach the carbon-neutrality target. The findings are as follows: (1) When employing the PLUS (Patch—based Land Use Simulation) model to conduct simulations of various land use scenarios in China by taking into account the dynamic alterations in driving factors, a high degree of precision was attained across diverse scenarios. The sustainable development scenario demonstrated the best performance, with kappa, OA, and FoM values of 0.9101, 93.15%, and 0.3895, respectively. This implies that the simulation approach based on dynamic factors is highly suitable for national-scale applications. (2) The simulation accuracy of the PLUS and GeoSOS-FLUS (Systems for Geographical Modeling and Optimization, Simulation of Future Land Utilization) models was validated for six scenarios by extrapolating the trends of influencing factors. Moreover, a set of scenarios was added to each model as a control group without extrapolation. The present research demonstrated that projecting the trends of factors having an impact notably improved the simulation precision of both the PLUS and GeoSOS-FLUS models. When contrasted with the GeoSOS-FLUS model, the PLUS model attained superior simulation accuracy across all six scenarios. The highest precision indicators were observed in the sustainable development scenario, with kappa, OA, and FoM values reaching 0.9101, 93.15%, and 0.3895, respectively. The precise simulation method of the PLUS model, which considers the dynamic changes in influencing factors, is highly applicable at the national scale. (3) Under the sustainable development scenario, it is anticipated that China’s land use carbon emissions will reach their peak in 2030 and achieve the carbon-neutrality target by 2060. Net carbon emissions are expected to decline by 14.36% compared to the 2020 levels. From the perspective of dynamic changes in influencing factors, the PLUS model was used to accurately simulate China’s future land use. Based on these simulations, multi-scenario predictions of future carbon emissions were made, and the results uncover the spatiotemporal evolution characteristics of China’s carbon emissions. This study aims to offer a solid scientific basis for policy-making related to China’s low-carbon economy and high-quality development. It also intends to present Chinese solutions and key paths for achieving carbon peak and carbon neutrality. Full article

As the scale of shipboard power systems expands, their vulnerability becomes increasingly prominent. Identifying vulnerable points in ship power grids is essential for enhancing system stability, optimizing overall performance, and ensuring safe navigation. To address this issue, this paper proposes an algorithm based on fuzzy local dimension and topology (FLDT). The algorithm distinguishes contributions from nodes at different radii and within the same radius to a central node using fuzzy sets, and then derives the final importance value of each node by combining the local dimension and topology. Experimental results on nine datasets demonstrate that the FLDT algorithm outperforms degree centrality (DC), closeness centrality (CC), local dimension (LD), fuzzy local dimension (FLD), local link similarity (LLS), and mixed degree decomposition (MDD) algorithms in three metrics: network efficiency (NE), largest connected component (LCC), and monotonicity. Furthermore, in a ship power grid experiment, when 40% of the most important nodes were removed, FLDT caused a network efficiency drop of 99.78% and reduced the LCC to 2.17%, significantly outperforming traditional methods. Additional experiments under topological perturbations—including edge addition, removal, and rewiring—also show that FLDT maintains superior performance, highlighting its robustness to structural changes. This indicates that the FLDT algorithm is more effective in identifying and evaluating vulnerable points and distinguishing nodes with varying levels of importance. Full article

Knowing the superior biochemical defense mechanisms of sessile organisms, it is not hard to believe the cure for any human sickness might be hidden in nature—we “just” have to identify it and make it safely available in the right dose to our organs and cells that are in need. For decades, green tea catechins (GTCs) have been a case in point. Because of their low redox potential and favorable positioning of hydroxyl groups, these flavonoid representatives (namely, catechin—C, epicatechin—EC, epicatechin gallate—ECG, epigallocatechin—EGC, epigallocatechin gallate—EGCG) are among the most potent plant-derived (and not only) antioxidants. The proven anti-inflammatory, neuroprotective, antimicrobial, and anticarcinogenic properties of these phytochemicals further contribute to their favorable pharmacological profile. Doubtlessly, GTCs hold the potential to “cope” with the majority of today‘s socially significant diseases, yet their mass use in clinical practice is still limited. Several factors related to the compounds’ membrane penetrability, chemical stability, and solubility overall determine their low bioavailability. Moreover, the antioxidant-to-pro-oxidant transitioning behavior of GTCs is highly conditional and, to a certain degree, unpredictable. The nanoparticulate delivery systems represent a logical approach to overcoming one or more of these therapeutic challenges. This review particularly focuses on the lipid-based nanotechnologies known to be a leading choice when it comes to drug permeation enhancement and not drug release modification nor drug stabilization solely. It is our goal to present the privileges of encapsulating green tea catechins in either vesicular or particulate lipid carriers with respect to the increasingly popular trends of advanced phytotherapy and functional nutrition. Full article

This research presents a reinforcement learning framework for stable quadruped locomotion using Proximal Policy Optimization (PPO). We address critical challenges in articulated robot control—including mechanical complexity and trajectory instability by implementing a 12-degree-of-freedom model in PyBullet simulation. Our approach features three key innovations: (1) a hybrid reward function ($R_t=0.72 · e^{-\Delta {\mathrm{CoG}}_t} + 0.25 · v_t - 0.11 · ‖{\tau }_t‖$) explicitly prioritizing center-of-gravity (CoG) stabilization; (2) rigorous benchmarking demonstrating Adam’s superiority over SGD for policy convergence (68% lower reward variance); and (3) a four-metric evaluation protocol quantifying locomotion quality through reward progression, CoG deviation, policy loss, and KL-divergence penalties. Experimental results confirm an 87.5% reduction in vertical CoG oscillation (from 2.0″ to 0.25″) across 1 million training steps. Policy optimization achieved −6.2 × 10⁻⁴ loss with KL penalties converging to 0.13, indicating stable gait generation. The framework’s efficacy is further validated by consistent CoG stabilization during deployment, demonstrating potential for real-world applications requiring robust terrain adaptation. Full article

Experimental tests on confined concrete specimens are essential to characterize the mechanisms activated under varying degrees of confinement. Such characterization is critical for understanding how full, partial, and non-uniform wrapping configurations influence strength and ductility enhancements. This study investigates the compressive behavior of concrete cylinders (160 mm × 320 mm) confined using full, partial, and non-uniform carbon fiber-reinforced polymers (CFRP) configurations. In the first phase, all wrapping schemes were applied with equivalent quantities of CFRP, enabling a direct performance comparison under material parity. The results indicate that non-uniform confinement (NUC) achieved approximately 15% higher axial strength than full confinement (FC2) using the same amount of CFRP. In the second phase, the NUC configuration was tested with 25% less CFRP material, yet the reduction in strength was limited to about 3%, demonstrating its superior efficiency. A new predictive model was developed to estimate peak axial stress and strain in CFRP-confined concrete cylinders. Compared to existing models, the proposed model demonstrated greater predictive accuracy (R² = 0.98 for stress and 0.91 for strain) and reduced error metrics (RMSE and scatter index). ANOVA confirmed the statistical significance of the model’s predictions (p < 0.00001 for stress, p = 0.002 for strain). These findings highlight the performance advantages and material efficiency of non-uniform CFRP confinement and support the utility of the proposed model as a practical design tool for developing advanced confinement strategies in structural engineering. Full article

Malignant mediastinal tumors are a group representing some of the most demanding oncological challenges for early, multi-level, and successful management. The timely identification of any suspicious clinical symptomatology is urgent in achieving an accurate, staged histological diagnosis, in order to follow up with an equally detailed medical therapeutic plan (interventional or not) and determine the principal goals regarding efficient overall treatment in these patients. We report a case of a 24-year-old male patient with an incident-free prior medical history. An initial chest X-ray was performed after the patient reported short-term, consistent moderate chest pain symptomatology, early work fatigue, and shortness of breath. The following imaging procedures (chest CT, PET-CT) indicated the presence of an anterior mediastinal mass (meas. ~11 cm × 10 cm × 13 cm, SUV: 8.7), applying additional pressure upon both right heart chambers. The Alpha-Fetoprotein (aFP) blood levels had exceeded at least 50 times their normal range. Two consecutive diagnostic attempts with non-specific histological results, a negative-for-malignancy fine-needle aspiration biopsy (FNA-biopsy), and an additional tumor biopsy, performed via mini anterior (R) thoracotomy with “suspicious” cellular gatherings, were performed elsewhere. After admission to our department, an (R) Video-Assisted Thoracic Surgery (VATS) was performed, along with multiple tumor biopsies and moderate pleural effusion drainage. The tumor’s measurements had increased to DMax: 16 cm × 9 cm × 13 cm, with a severe degree of atelectasis of the Right Lower Lobe parenchyma (RLL) and a pressure-displacement effect upon the Superior Vena Cava (SVC) and the (R) heart sinus, based on data from the preoperative chest MRA. The histological report indicated elements of a combined, non-seminomatous germ-cell mediastinal tumor, posthuberal-type teratoma, and embryonal carcinoma. The imminent chemotherapeutic plan included a “BEP” (Bleomycin^®/Cisplatin^®/Etoposide^®) scheme, which needed to be modified to a “VIP” (Cisplatin^®/Etoposide^®/Ifosfamide^®) scheme, due to an acute pulmonary embolism incident. While the aFP blood levels declined, even reaching normal measurements, the tumor’s size continued to increase significantly (DMax: 28 cm × 25 cm × 13 cm), with severe localized pressure effects, rapid weight loss, and a progressively worsening clinical status. Thus, an emergency surgical intervention took place via median sternotomy, extended with a complementary “T-Shaped” mini anterior (R) thoracotomy. A large, approx. 4 Kg mediastinal tumor was extracted, with additional RML and RUL “en-bloc” segmentectomy and partial mediastinal pleura decortication. The following histological results, apart from verifying the already-known posthuberal-type teratoma, indicated additional scattered small lesions of combined high-grade rabdomyosarcoma, chondrosarcoma, and osteosarcoma, as well as numerous high-grade glioblastoma cellular gatherings. No visible findings of the previously discovered non-seminomatous germ-cell and embryonal carcinoma elements were found. The patient’s postoperative status progressively improved, allowing therapeutic management to continue with six “TIP” (Cisplatin^®/Paclitaxel^®/Ifosfamide^®) sessions, currently under his regular “follow-up” from the oncological team. This report underlines the importance of early, accurate histological identification, combined with any necessary surgical intervention, diagnostic or therapeutic, as well as the appliance of any subsequent multimodality management plan. The diversity of mediastinal tumors, especially for young patients, leaves no place for complacency. Such rare examples may manifest, with equivalent, unpredictable evolution, obliging clinical physicians to stay constantly alert and not take anything for granted. Full article

Floating offshore wind turbines (FOWTs) unlock superior wind resources and reduce operational barriers. The dynamics of FOWT platforms present added engineering challenges and opportunities. While the motion of the floating platform due to wind and wave disturbances can worsen power quality and increase structural loading, certain movements of the floating platform can be exploited to improve power capture. Consequently, active FOWT platform control methods using conventional and innovative actuation systems are under investigation. This paper develops a novel framework to design nonlinear control laws for six degrees-of-freedom platform motion. The framework uses simplified rigid-body analytical models of the FOWT. Lyapunov’s direct method is used to develop actuator-agnostic unconstrained control laws for platform translational and rotational control. A model based on the NREL-5MW reference turbine on the OC3-Hywind spar-buoy platform is utilized to test the control framework for an ideal actuation scenario. Possible applications using traditional and novel turbine actuators and future research directions are presented. Full article

It is critical to provide life-sustaining treatment to OHCA patients before ambulance care arrives. However, incorrectly performed resuscitation maneuvers reduce the chances of survival and recovery for the victims. Therefore, we must train regularly and learn how to do it correctly. To facilitate regular chest compression training, this study aims to improve the accuracy of a chest compression evaluation system using posture estimation and to develop a web application. To analyze and enhance accuracy, the YOLOv8 posture estimation was used to examine compression depth, recoil, and tempo, and its accuracy was compared to that of the manikin, which has evaluation systems. We conducted comparative experiments with different camera angles and heights to optimize the accuracy of the evaluation. The experimental results showed that an angle of 30 degrees and a height of 50 cm produced superior accuracy. For web application development, a system has been designed to allow users to upload videos for analysis and obtain appropriate compression parameters. The usability evaluation of the application confirmed its ease of use and accessibility, and positive feedback was obtained. In the conclusion, these findings suggest that optimizing recording conditions significantly improves the accuracy of posture-based chest compression evaluation. Future work will focus on enhancing real-time feedback functionality and improving the user interface of the web application. Full article

Poly(ε-caprolactone)-b-polysarcosine (PCL-b-PSar) block copolymers (BCPs) emerge as a promising alternative to conventional poly(ε-caprolactone)-b-poly(ethylene oxide) BCPs for biomedical applications, leveraging superior biocompatibility and biodegradability. In this study, we synthesized two series of PCL-b-PSar BCPs with controlled polymerization degrees (DP of PCL: 45/67; DP of PSar: 28–99) and low polydispersity indexes (Đ ≤ 1.1) and systematically investigated their crystallization-driven self-assembly (CDSA) in alcohol solvents (ethanol, n-butanol, and n-hexanol). It was found that the limited solubility of PSar in alcohols resulted in competition between micellization and crystallization during self-assembly of PCL-b-PSar, and thus coexistence of lamellae and spherical micelles. To overcome this morphological heterogeneity, we developed a modified self-seeding method by employing a two-step crystallization strategy (i.e., T_c1 = 33 °C and T_c2 = 8 °C), achieving conversion of micelles into crystals and yielding uniform self-assembled structures. PCL-b-PSar BCPs with short PSar blocks tended to form well-defined two-dimensional lamellar crystals, while those with long PSar blocks induced formation of hierarchical structures in the PCL₄₅ series and polymer aggregation on crystal surfaces in the PCL₆₇ series. Solvent quality notably influenced the self-assembly pathways of PCL₄₅-b-PSar₂₈. Lamellar crystals were formed in ethanol and n-butanol, but micrometer-scale dendritic aggregates were generated in n-hexanol, primarily due to a significant Hansen solubility parameter mismatch. This study elucidated the CDSA mechanism of PCL-b-PSar in alcohols, enabling precise structural control for biomedical applications. Full article

Due to its superior maneuverability and concealment, the micro flapping-wing aircraft has great application prospects in both military and civilian fields. However, the development and optimization of lightweight materials have always been the key factors limiting performance enhancement. This paper designs the flapping mechanism of a single-degree-of-freedom miniature flapping wing aircraft. In this study, T800 carbon fiber composite material was used as the frame material. Three typical wing membrane materials, namely polyethylene terephthalate (PET), polyimide (PI), and non-woven kite fabric, were selected for comparative analysis. Three flapping wing configurations with different stiffness were proposed. These wings adopted carbon fiber composite material frames. The wing membrane material is bonded to the frame through a coating. Inspired by bionics, a flapping wing that mimics the membrane vein structure of insect wings is designed. By changing the type of membrane material and the distribution of carbon fiber composite materials on the wing, the stiffness of the flapping wing can be controlled, thereby affecting the mechanical properties of the flapping wing aircraft. The modal analysis of the flapping-wing structure was conducted using the finite element analysis method, and the experimental prototype was fabricated by using 3D printing technology. To evaluate the influence of different wing membrane materials on lift performance, a high-precision force measurement experimental platform was built, systematic tests were carried out, and the lift characteristics under different flapping frequencies were analyzed. Through computational modeling and experiments, it has been proven that under the same flapping wing frequency, the T800 carbon fiber composite material frame can significantly improve the stiffness and durability of the flapping wing. In addition, the selection of wing membrane materials has a significant impact on lift performance. Among the test materials, the PET wing film demonstrated excellent stability and lift performance under high-frequency conditions. This research provides crucial experimental evidence for the optimal selection of wing membrane materials for micro flapping-wing aircraft, verifies the application potential of T800 carbon fiber composite materials in micro flapping-wing aircraft, and opens up new avenues for the application of advanced composite materials in high-performance micro flapping-wing aircraft. Full article

Background: Aquatic therapy (AT), immersion in hot water, and supported standing are frequently used to manage spasticity, contractures, and joint retractions in children with cerebral palsy (CP). Recently, the use of exoskeletons has been offering a new treatment option for severe CP. This study aimed to compare the post-immediate effects of four treatments on spasticity, range of motion, and the heart rate of children with severe CP. Methods: Three children with spastic CP (levels IV and V GMFCS) received a single 30-min session in consecutive weeks of robot-assisted gait training (RAGT), AT, supported standing, and immersion in hot water. Post-immediate assessments included knee flexor spasticity (modified Ashworth scale, MAS, and modified Tardieu scale, MTS); knee range of motion (ROM, in degrees (°)); and heart rate (HR). Results: AT and supported standing induced greater reductions in spasticity based on MAS scores. RAGT demonstrated superior spasticity reduction using MTS and yielded the greatest improvement in popliteal angle (mean increase: 27°). AT and RAGT induced a 14 beats-per-minute change in HR, indicating moderate cardiovascular engagement. Conclusions: RAGT appears particularly effective in improving spasticity and ROM in children with severe CP. Nonetheless, conventional treatments still offer an effective option when addressing spasticity. Full article

The challenge of achieving high-precision direction-of-arrival (DOA) estimation with enhanced degrees of freedom (DOFs) under a limited number of physical array elements remains a critical issue in array signal processing. To address this limitation, this paper makes the following three key contributions: (1) a novel moving sparse array synthesis model incorporating time-frequency-spatial joint processing for coprime frequencies signal sources; (2) an optimized coprime frequencies-based unmanned aerial vehicle array (CF-UAVA) configuration with derived closed-form expressions for the distribution of synthesized array; and (3) two DOA estimation methods: a group sparsity-based approach universally applicable to the proposed aperture synthesis model and a joint group sparsity and virtual array interpolation tailored for the proposed CF-UAVA configuration. Comprehensive simulation results demonstrate the superior DOA estimation accuracy and increased DOFs achieved by our proposed aperture synthesis model and DOA estimation algorithms compared to conventional approaches. Full article