Search Results (4,682)

The mechanical recycling of thermoplastics (especially of polyolefins) often results in recyclates with inferior properties compared to their virgin counterparts. This phenomenon is mainly due to the modification of the polymer microstructure induced by the degradation processes undergone by the materials during their service life and reprocessing. In this work, a promising route for obtaining high-melt-strength recycled high-density polyethylene (HDPE) is proposed. In particular, the exploited approach involves the utilization of a commercially available additive (i.e., Nexamite^® R305, Nexam Chemical, Lomma, Sweden), which was demonstrated to be capable of driving thermo-mechanical degradation reactions (experienced by HDPE during mechanical recycling) towards the obtainment of a long-chain branched microstructure, thereby enabling the further processing of the recycled material through technologies dominated by elongational flow. The additive-induced alterations of the polymer microstructure were exploited for the formulation of fibers, and the performed tensile characterization showed that the additive-containing material exhibits strikingly improved ductility (namely, elongation at break of 350% for the fibers stretched at a draw ratio of 60) with respect to pristine recycled HDPE. Overall, the obtained results clearly demonstrated the possibility of attaining an effective upcycling of HDPE, which could be exploited for industrially relevant high-added-value applications, hence paving the way for the achievement of full plastic circularity. Full article

This study aimed to assess the effectiveness of various active recovery strategies in youth female soccer players during competitive tournaments with limited recovery periods (i.e., 24–48 h). Twenty-two elite under-17 female football players participated in this randomized controlled trial, which encompassed fourteen 90 min official matches. Participants were randomly allocated to one of three recovery protocols: passive stretching, foam rolling, or lumbopelvic mobility exercises, which were implemented ten minutes after each match. Countermovement jump with free arm (CMJA) height was measured pre-intervention, immediately post-intervention, and 5 h post-intervention. Wellness perception was evaluated 24 h later. Significant enhancements in CMJA height were observed immediately after all recovery protocols and at 5 h post-intervention compared with pre-intervention (p < 0.001). The lumbopelvic mobility protocol yielded the most substantial improvement, significantly surpassing both stretching and foam rolling. Moreover, significant increases in wellness perception were observed following the foam rolling (p < 0.001, ES = 0.95) and mobility (p < 0.05, ES = 0.88) protocols, with the mobility protocol demonstrating a marginally larger effect size than stretching. Active recovery strategies significantly enhanced neuromuscular function and wellness perception in under-17 female soccer players. Lumbopelvic mobility exercises exhibited superior efficacy, suggesting that they should be prioritized in post-match recovery regimens. Full article

This study investigates the mutual interaction between self- and partner-induced actions in determining pressure distribution during a handshake and proposes a tele haptic handshake system based on these findings. To achieve this, experiments were conducted to examine how pressure distribution in face-to-face handshakes is influenced by mutual actions. Based on the experimental results, an interaction force model was developed to calculate stimulus intensities, incorporating region-specific weights for different parts of the hand. Additionally, a tele haptic handshake system was designed, integrating flex sensors to measure finger joint angles and a distributed haptic stimulus presentation device to provide tactile feedback. While this study lays the foundation for understanding the dynamics of handshake interactions and their application in remote environments, further validation of the system’s effectiveness in replicating real-world handshake experiences remains a subject for future work. Full article

Based on the analysis of the IR transmission spectra in the region of stretching vibrations of hydrogen atoms of OH⁻-groups, it was established that the oxygen-octahedral МеО₆ clusters (Ме-Li⁺, Nb⁵⁺, vacant octahedron V, impurity ion) of the structure of the compositionally homogeneous crystal LiNbO₃:Er³⁺(3.1 wt%) and the gradient crystal LiNbO₃:Er³⁺(congruent composition by the main components, Er gradient of 0.55 at%/cm) have a shape close to the regular one. In this case, the value of R = [Li]/[Nb] ≈ 1, and in the structure of both crystals, there are practically no point defects in Nb_Li responsible for the photorefraction effect. By using the IR transmission spectra and Klauer’s method, it was found that the volume concentration of OH⁻-groups in the gradient crystal LiNbO₃:Er³⁺ is almost an order of magnitude lower than in the compositionally homogeneous LiNbO₃:Er³⁺(3.1 wt%) crystal. This fact explains the lower hydrogen conductivity of the gradient crystal LiNbO₃:Er³⁺ and the lower photorefraction effect compared to the compositionally homogeneous LiNbO₃:Er³⁺(3.1 wt%) crystal. The results obtained are important for the development of materials for active nonlinear laser media and for the conversion of laser radiation. Full article

Background/Objectives: “Hermes” is an ankle–foot orthosis (AFO) with negative stiffness designed to mechanically compensate the symptomatic increase in plantarflexion (PF) torque (i.e., ankle joint torque resistance to dorsiflexion, DF) in patients with spastic paresis. Methods: The effectiveness of “Hermes” was evaluated in twelve patients with chronic unilateral spastic paresis after stroke. Using a robotic ankle manipulator, stiffness at the ankle joint was assessed across three conditions: ankle without Hermes ($A$), ankle with Hermes applying no torque compensation ($A+H_{0\mathrm{\%}}$), and ankle with Hermes tuned to compensate 100% of the patients’ ankle joint stiffness ($A+H_{100\mathrm{\%}}$). Results: A significant reduction in PF torque was found with Hermes applying compensation ($A+H_{100\mathrm{\%}}$) compared to the conditions without Hermes ($A$) and with Hermes applying no compensation ($A+H_{0\mathrm{\%}}$). Furthermore, a significant reduction in positive dorsiflexion work was found with Hermes applying compensation ($A+H_{100\mathrm{\%}}$) compared to the condition with Hermes applying no compensation ($A+H_{0\mathrm{\%}}$). Hermes did not significantly contribute to additional PF torque or positive work when applying no compensation ($A+H_{0\mathrm{\%}}$). Conclusions: The reductions in PF torque achieved with Hermes are comparable to those seen with repeated ankle stretching programs and ankle robot training. Thus, Hermes is expected to assist voluntary dorsiflexion and improve walking in patients with spastic paresis. Full article

This study explores the effectiveness of the Movement System Impairment (MSI) model compared to traditional physiotherapy for treating knee pain. Fifty patients with unilateral knee pain participated, with their femur, tibia, and knee alignment assessed in nine functional positions. Evaluations included the Tegner Activity Scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), muscle power, extensibility, and pain levels. Patients were randomly assigned to either the MSI treatment group, which focused on identifying and correcting faulty movements, or a routine physiotherapy group that received general strengthening and stretching exercises. Results indicated that both treatment approaches improved muscle power in hip abductors and lateral rotators, as well as scores on the Tegner Activity Scale and the KOOS. Notably, the MSI group demonstrated greater improvements in the muscle power of the hip lateral rotators and knee extensors and a significant reduction in knee pain during walking compared to the routine group (p = 0.005). In conclusion, both treatments enhanced pain, function, and muscle strength, while the MSI model significantly reduced knee pain in walking and improved hip and knee muscle power compared to routine physiotherapy. Full article

A novel application of microresonators for refractometric sensing in aqueous media is presented. To carry out this approach, microspheres of different materials and sizes were fabricated and doped with Nd³⁺ ions. Under 532 nm excitation, the microspheres presented typical NIR Nd³⁺ emission bands with superimposed sharp peaks, related to the Whispering Gallery Modes (WGMs), due to the geometry of the microspheres. When the microspheres were submerged in water with increasing concentrations of glycerol, spectral shifts for the WGMs were observed as a function of the glycerol concentration. These spectral shifts were studied and calibrated for three different microspheres and validated with the theoretical shifts, obtained by solving the Helmholtz equations for the electromagnetic field, considering the geometry of the system, and also by calculating the extinction cross-section. WGM shifts strongly depend on the diameter of the microspheres and their refractive index (RI) difference compared with the external medium, and are greater for decreasing values of the diameter and lower values of RI difference. Experimental sensitivities ranging from 2.18 to 113.36 nm/RIU (refractive index unit) were obtained for different microspheres. Furthermore, reproducibility measurements were carried out, leading to a repeatability of 2.3 pm and a limit of detection of 5 × 10⁻⁴ RIU. The proposed sensors, taking advantage of confocal microscopy for excitation and detection, offer a robust, reliable, and contactless alternative for environmental water analysis. Full article

The widespread use of plastic bags as improvised food cooking covers in Mozambican communities has raised public health concerns, increasing interest in studying these plastic bags, which contain heavy metals additives used to improve their physical and chemical properties. This study aims to evaluate the levels of heavy metals commonly used in plastic bags used as improvised food cooking covers, focused on Mozambican communities that have this habit. Using spectroscopic techniques, Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Absorption Spectroscopy (AAS), we analyzed plastic bag samples to identify polymer types, chemical composition, and heavy metal concentrations. FTIR analysis confirmed low- and high-density polyethylene (LDPE and HDPE) as the primary materials, with spectra peaks between 2800 and 3000 cm⁻¹, indicating stretching vibrations characteristic of LDPE and HDPE. The density measurements varied between 0.04 and 0.08 g/cm³ with very low uncertainty values (0.27% and 0.098%). The heavy metal analysis revealed concentrations higher than those stipulated in international standards. The results in terms of the percentage of LDPE samples in relation to the HDPE samples are as follows: Cd: 69.71% (LDPE < HDPE); Cu: 220.44% (LDPE > HDPE); Pb: 24% (LDPE < HDPE); and Zn: 51.53% (LDPE < HDPE). These findings highlight the potential public health risks associated with the use of plastic bags in cooking and underscore the need for regulatory intervention. Full article

Celiac disease is attributable to a combination of genetic predisposition and exposure to dietary gluten, with immune system involvement. The incidence is increasing globally, and the societal economic burden of celiac disease stretches beyond the cost of gluten-free food. This enteropathy that affects the small intestine has been related to different disorders and comorbidities. Thus, the implications of suffering from this disease are multidimensional and need further consideration. Celiac disease is a serious condition that remains under-recognized, resulting in an increased need for programs for better management. This review aims to summarize the current evidence regarding celiac diseases, with special emphasis on clinical implications, diagnosis, dietary management, socioeconomical aspects, and future perspectives. Full article

Background/Objectives: Issues related to the chronic venous leg ulcer (VLU) treatment and prevention of recurrences remain the subject of research, but so too do common clinical problems in daily medical practice. Due to its medicinal properties, Manuka honey is increasingly used in the treatment of wounds of various origins. The aim of the study was to investigate the effectiveness of Manuka honey for the topical treatment of non-healing, chronic, venous leg ulcers. Methods: Eighty patients with chronic VLU participated in the study and were randomized into two equinumerous groups. In group 1, patients were treated with topical Manuka honey application and short stretch bandage compression, whereas, in group 2, antimicrobial calcium alginate wound dressing + Ag was used instead of Manuka honey. The efficacy of both treatment methods was compared. Results: The ulcerations in patients from group 1 have healed completely after up to seven weeks of therapy in all cases. In contrast, in all patients from group 2, the healing process was longer but completed successfully after up to 14 weeks of the therapy. The process of wound cleaning from microorganisms was also faster in group 1, as well as the reduction in ulcer area during treatment. Conclusions: It was found that the topical administration of Manuka honey may be a promising alternative to traditional methods of non-healing VLU treatment. Full article

Low-moisture Mozzarella cheese (LMMC) was manufactured in a dairy factory by stretching fresh curd in hot water, with the addition of 0–30% commercial curd (stored curd) purchased as a semi-finished product. Two commercial fermentation-produced camel chymosins, CC-M and CC-S, were employed as coagulants. The chemical, rheological and microstructural properties of LMMC were assessed during storage. The results demonstrated that cheese composition was not significantly influenced by curd addition. The use of CC-S promoted a slight increase of fat matter with respect to the CC-M samples because of the higher proteolytic specificity and clotting activity of the CC-S enzyme. A higher extent of proteolysis was found in LMMC manufactured with CC-M. The textural properties evaluated during storage revealed an increase in meltability, adhesiveness and springiness over time. The amount of added curd had only a minor effect. The melting behaviour was significantly influenced by proteolysis during the 35-day storage period. Overall, the proteolysis during aging was the most impactful factor affecting the properties of LMMC. Full article

Direct wide-bandgap III-Ns and II-Os have recently gained considerable attention due to their unique electrical and chemical properties. These novel semiconductors are being explored to design short-wavelength light-emitting diodes, sensors/biosensors, photodetectors for integration into flexible transparent nanoelectronics/photonics to achieve high-power radio-frequency modules, and heat-resistant optical switches for communication networks. Knowledge of the elastic constants structural and mechanical properties has played crucial roles both in the basic understanding and assessing materials’ use in thermal management applications. In the absence of experimental structural, elastic constants, and mechanical traits, many theoretical simulations have yielded inconsistent results. This work aims to investigate the basic characteristics of tetrahedrally coordinated, partially ionic BeO, MgO, ZnO, and CdO, and partially covalent BN, AlN, GaN, and InN materials. By incorporating a bond-orbital and a valance force field model, we have reported comparative results of our systematic calculations for the bond length $\mathrm{d}$, bond polarity ${\mathsf{\alpha }}_{\mathrm{P}}$, covalency ${\mathsf{\alpha }}_{\mathrm{C}}$, bulk modulus $\mathrm{B}$, elastic stiffness $\mathrm{C}(={\displaystyle \frac{\left[{\mathrm{c}}_{11}-{\mathrm{c}}_{12}\right]}{2}})$, bond-stretching $\mathsf{\alpha }$ and bond-bending $\mathsf{\beta }$ force constants, Kleinmann’s internal displacement ζ, and Born’s transverse effective charge ${\mathrm{e}}_{\mathrm{T}}^{*}$. Correlations between $\mathrm{C}/\mathrm{B}$, $\mathsf{\beta }$/$\mathsf{\alpha }$, ${\displaystyle \frac{{\mathrm{c}}_{12}}{{\mathrm{c}}_{11}}},$ ζ, $\mathrm{a}\mathrm{n}\mathrm{d}$ ${\mathsf{\alpha }}_{\mathrm{C}}$revealed valuable trends of structural, elastic, and bonding characteristics. The study noticed AlN and GaN (MgO and ZnO) showing nearly comparable features, while BN (BeO) is much harder compared to InN (CdO) material, with drastically softer bonding. Calculations of microhardness $\mathrm{H}$, shear modulus $\mathrm{G},$ and Young’s modulus $\mathrm{Y}$ have predicted BN (BeO) satisfying a criterion of super hardness. III-Ns (II-Os) could be vital in electronics, aerospace, defense, nuclear reactors, and automotive industries, providing integrity and performance at high temperature in high-power applications, ranging from heat sinks to electronic substrates to insulators in high-power devices. Full article

Leg stretching devices are one of the main instruments used to improve human function. To solve the limitations of existing leg stretching products, such as single function and low degree of coincidence, a leg stretching device satisfying ergonomics was studied in this paper. Firstly, the Box–Behnken Design (BBD) response surface methodology was applied to establish a regression model for leg force. Secondly, a motion analysis was conducted on the leg lifting mechanism using analytical methods, and the model data were coupled by Creo Parametric and Automatic Dynamic Analysis of Mechanical System (ADAMS) 2019 software to develop the kinematic model. Then, the motion characteristics during the whole process were studied, and the motion parameter curves were obtained. Next, ABAQUS 2022 software was employed to create the finite element simulation model of the leg lifting device, and key component strength was also analyzed. Finally, a prototype of the device was made and experimentally validated with leg lifting. The results show that in the case of different heights and weights, the lifting angle of the human leg has a significant effect on the force state during the leg lifting process. When the leg is lifted 0–30°, the force on the leg is small. As the leg lifting angle increases, the force on the leg also increases. In the process of leg lifting, the angular velocity and angular acceleration of the leg lifting mechanism change more gently, and there is no obvious mutation. The maximum stress of the driving rod is 102.5 MPa, the maximum stress of the lifting rod is 88.12 MPa, and the maximum stress of the leg placing plate is 40.5 MPa, all of which meet the strength requirements and provide a reference for the research of the human leg stretching device. Full article

This study presents the formulation and comprehensive characterization of compatibilized polyamide 6 (PA6)/cyclic olefin copolymer (COC) blends with the aim of developing a self-healing matrix for thermoplastic structural composites. Rheological analysis highlighted the compatibilizing effect of ethylene glycidyl methacrylate (E-GMA), as evidenced by an increase in viscosity, melt strength (MS), and breaking stretching ratio (BSR), thus improving the processability during film extrusion. E-GMA also decreased COC domain size and improved the interfacial interaction with PA6, which was at the basis of a higher tensile strength and strain at break compared to neat PA6/COC blends. E-GMA also significantly boosted the healing efficiency (HE), measured via fracture toughness tests in quasi-static and impact conditions. The optimal healing temperature was identified as 160 °C, associated with an HE of 38% in quasi-static mode and 82% in impact mode for the PA6/COC blends with an E-GMA content of 5 wt% (PA6COC_5E-GMA). The higher healing efficiency under impact conditions was attributed to the planar fracture surface, which facilitated the flow of the healing agent in the crack zone, as proven by fractography analysis. This work demonstrates the potential of E-GMA in fine-tuning the thermomechanical properties of PA6/COC blends. PA6COC_5E-GMA emerged as the formulation with the best balance between processability and self-healing efficiency, paving the way for advanced multifunctional self-healing thermoplastic composites for structural applications. Full article

In this work, a conductive composite film composed of multi-walled carbon nanotubes (MWCNTs) and multi-layer Ti₃C₂Tx MXene nanosheets is used to construct a strain sensor on sandpaper Ecoflex substrate. The composite material forms a sophisticated conductive network with exceptional electrical conductivity, resulting in sensors with broad detection ranges and high sensitivities. The findings indicate that the strain sensing range of the Ecoflex/Ti₃C₂Tx/MWCNT strain sensor, when the mass ratio is set to 5:2, extends to 240%, with a gauge factor (GF) of 933 within the strain interval from 180% to 240%. The strain sensor has demonstrated its robustness by enduring more than 33,000 prolonged stretch-and-release cycles at 20% cyclic tensile strain. Moreover, a fast response time of 200 ms and detection limit of 0.05% are achieved. During application, the sensor effectively enables the detection of diverse physiological signals in the human body. More importantly, its application in a data glove that is coupled with machine learning and uses the Support Vector Machine (SVM) model trained on the collected gesture data results in an impressive recognition accuracy of 93.6%. Full article