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Fabrication of multifunctional nanofiber mats by emulsion electrospinning of TPU/fish skin gelatin incorporating plant extract-based therapeutic oil for wound dressing applications
No full textIn this study, for the first time thermoplastic polyurethane (TPU), fish skin gelatin (FSG), and H. perforatum oil (HPO) combine to form a new nanofiber material by using the emulsion electrospinning technique. Scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) are used for the characterization studies. Moreover, antibacterial activities, in vitro wound healing and cytotoxicity of the TPU mats are also investigated. The SEM investigations reveal that the average diameters of defect-free TPU nanofiber mats with diverse HPO concentrations are ≈400–500 nm and suitable to mimic the native extracellular matrix (ECM) with these values. Moreover, although there is no antibacterial activity in the control TPU mat, the addition of the tannic acid crosslinker and 12% of HPO to the nanofiber mat acquires a 31.3% inhibition against Staphylococcus aureus and a 21.0% against Escherichia coli. Furthermore, the TPU nanofiber mat with the highest HPO concentration (12%) is non-toxic to the cells and tends to promote healing in vitro assay. Overall results indicate that the wound healing properties of the obtained HPO-encapsulated TPU nanofiber mats can be a promising candidate for wound dressing applications
4D printing of reusable mechanical metamaterial energy absorber, experimental and numerical investigation
No full textThis study investigates the compression behavior, energy absorption, shape memory properties, and reusability of 4D-printed smart mechanical metamaterials. Four structural configurations, i.e. honeycomb, re-entrant, and two modified re-entrant designs were developed to assess microstructure effects. Samples were fabricated using Polylactic Acid (PLA), a widely used shape memory polymer (SMP) in 4D printing, and polyethylene terephthalate glycol (PETG), an emerging SMP with demonstrated shape memory performance in recent studies. Cold-programming-induced shape recovery was evaluated at room temperature, simulating real-world conditions. Finite element simulations of compression and shape memory cycles matched experimental results well. Auxetic samples with negative Poisson’s ratios showed superior energy absorption. However, only PETG demonstrated sufficient reusability, while PLA proved unsuitable for reusable designs. The PETG-3 modified re-entrant structure exhibited the best performance, with high energy absorption, delayed densification onset, and shape recovery and reusability factors of 0.95 and 0.96, respectively. Findings highlight the importance of considering both shape recovery and reusability when designing smart structures to address industrial challenges
Current state and potential of polymersomes as ocular drug delivery systems
No full textAmphiphilic copolymers can spontaneously form different structures such as micelles, worm-like micelles, and spherical and tubular polymersomes, determined by the ratio of hydrophilic and hydrophobic blocks. Among them, polymersomes are composed of an aqueous core and a hydrophobic membrane that can encapsulate hydrophilic and hydrophobic drugs. Significant effort has been dedicated to developing polymersomes for targeted delivery of drugs, particularly in cancer therapy. Nonetheless, polymersomes hold great potential for drug delivery to the ocular tissues as well. Polymersomes provide various advantages as ocular drug delivery systems due to their chemical and physical adaptability, ability to encapsulate multiple drugs, and precise control over parameters including size, shape, membrane characteristics, drug release, ability to traverse biological barriers, and responsiveness to stimuli. Despite the limited research to date, polymersomes, with their superior mobility within ocular compartments and their tunable properties, should be considered a promising option for ocular drug delivery, surpassing other vesicular systems such as liposomes and niosomes. In this review, we assessed the possibility of polymersomes as carriers for delivering drugs to ocular tissues
Polaron catastrophe within quantum acoustics
No full textThe quantum acoustic framework has recently emerged as a nonperturbative, coherent approach to electron–lattice interactions, uncovering rich physics often obscured by perturbative methods with incoherent scattering events. Here, we model the strongly coupled dynamics of electrons and acoustic lattice vibrations within this framework, representing lattice vibrations as coherent states and electrons as quantum wave packets, in a manner distinctively different from tight-binding or discrete hopping-based approaches. We derive and numerically implement electron backaction on the lattice, providing both visual and quantitative insights into electron wave packet evolution and the formation of acoustic polarons. We investigate polaron binding energies across varying material parameters and compute key observables—including mean square displacement, kinetic energy, potential energy, and vibrational energy—over time. Our findings reveal the conditions that favor polaron formation, which is enhanced by low temperatures, high deformation potential constants, slow sound velocities, and high effective masses. Additionally, we explore the impact of external electric and magnetic fields, showing that while polaron formation remains robust under moderate fields, it is weakly suppressed at higher field strengths. These results deepen our understanding of polaron dynamics and pave the way for future studies into nontrivial transport behavior in quantum materials
Effect of heat treatment and hot isostatic pressing on the microstructure and mechanical properties of the directed energy deposition IN738LC and IN718: a comparative study
No full textAdditive manufacturing of nickel-based superalloys is challenging due to the presence of several alloying elements and their wide range of solidification temperatures, which causes residual stress, intermetallics formation, and in-process cracking. Moreover, upon achieving successful production, the as-built components generally possess poor ductility. In this paper, proper post-treatment strategies for IN738LC and IN718 are employed to investigate their effects on the microstructural and mechanical properties of the previously developed mixed IN738LC + IN718 (80/20) alloy. It is shown that the HIP can significantly increase the mass density of IN718 and the mixed IN738LC + IN718. The microstructure of mixed IN738LC + IN718 resembles the IN738LC γ/γ’ microstructure with a few Laves and eutectics, which are common in IN718. Applying heat treatment or HIP cause the evolution of the γ’ phase, which directly affects the mechanical properties of this alloy. After the optimum post-treatment, the ultimate strength of the mixed IN738LC + IN718 is recovered to over 1300 MPa along with 17 % elongation at break. The hardness of this alloy can be improved to almost the same value for as-built IN738LC as well. Therefore, the addition of IN718 is not only harmless to the mechanical properties of IN738LC, it is an effective way to produce large components from this alloy without requiring special production conditions
Lower bounds for weighted Chebyshev and orthogonal polynomials
No full textWe derive optimal asymptotic and non-asymptotic lower bounds on the Widom factors for weighted Chebyshev and orthogonal polynomials on compact subsets of the real line. In the Chebyshev case we extend the optimal non-asymptotic lower bound previously known only in a handful of examples to regular compact sets and a large class weights. Using the non-asymptotic lower bound, we extend Widom’s asymptotic lower bound for weights bounded away from zero to a large class of weights with zeros including weights with strong zeros and infinitely many zeros. As an application of the asymptotic lower bound we extend Bernstein’s 1931 asymptotics result for weighted Chebyshev polynomials on an interval to arbitrary Riemann integrable weights with finitely many zeros and to some continuous weights with infinitely many zeros. In the case of orthogonal polynomials, we derive optimal asymptotic and non-asymptotic lower bound on arbitrary regular compact sets for a large class of weights in the non-asymptotic case and for arbitrary Szegő class weights in the asymptotic case, extending previously known bounds on finite gap and Parreau–Widom sets
Fine-tuning equilibrium water content and mechanical properties of acrylic-based copolymers for intraocular lens applications
No full textWe report on the development of copolymers of 2-hydroxy ethyl acrylate (HEA) with 2-(2-ethoxy ethoxy) ethyl acrylate (EEEA) grafted with ethylene glycol di-methacrylate, designed for use as an intraocular lens (IOL) material. Various HEA/EEEA monomer ratios were synthesized via thermal copolymerization, with the HEA concentration progressively increasing from 3.5% to 28%, while the EEEA concentration decreased proportionately. The physical-chemical, optical, and mechanical properties of the newly developed materials, fabricated as discs (∼3.2 mm thick, 11 mm in diameter) and strips (∼3.2 mm thick, 80 × 15 mm2), were comprehensively analyzed. Fourier-Transform Infrared Spectroscopy confirmed the successful copolymerization, as characteristic peaks corresponding to the monomers were observed. Since the development of IOL materials hinges on understanding their physical-chemical, optical, and mechanical characteristics—particularly the equilibrium water content (EWC)—our initial focus was on identifying EWC as a key factor in the development of IOLs. The results showed that the EWC value increased with higher HEA concentrations. Contact angle measurements indicated that the polymers exhibited hydrophilic behavior, with values ranging from 68 to 76°. X-ray diffraction analysis demonstrated that the HEA concentration influenced the crystalline structure, which, in turn, affected the mechanical properties. The results indicated that higher HEA concentrations, corresponding to increased EWC values (i.e. ∼8%), led to enhanced flexibility, as evidenced by a decrease in tensile strength from 1.71 to 1.13 MPa, and reduced hardness, which declined from 57.5 to 47.5 Shore A. Additionally, refractive index analyses revealed a gradual decrease with increasing HEA concentrations, ranging from 1.565 to 1.543 when measured at 480 nm and from 1.547 to 1.528 when measured at 660 nm. The evaluation of the coefficient of variation and Pearson’s correlation coefficient demonstrated strong material consistency and clear trends across formulations, reinforcing the reliability of the observed properties. These findings emphasize the significance of EWC and the ratio of hydrophilic monomers in acrylic-based copolymers, suggesting that future research could benefit from designing copolymers with tailored physical-chemical, optical, and mechanical properties for IOL applications
A genome-wide analysis of structure and evolution in Irish and British populations of bombus terrestris (L. 1758): implications for genetic resource conservation
Get PDFInsect pollinators play vital regulatory roles within ecosystems and provide humanity with essential services that support our health, wellbeing, and economies. Despite their importance, reported declines at regional and national levels have raised concerns over the continuation of such benefits. Island pollinator populations are of particular conservation interest as they may harbor lower genetic diversity due to restricted gene flow caused by geographical barriers, which may in turn influence local selective processes. In this study, we investigated the population structure and potential targets of selection within the genomes of a bumblebee subspecies, Bombus terrestris audax, native to the islands of Ireland and Great Britain. In particular, we compared the genomes of wild-caught populations from each island alongside representatives of other European subspecies and commercial imports to ascertain patterns of historical admixture. Our analysis identified a largely genetically distinct population of B. t. audax on the island of Ireland, with weak evidence of admixture. In addition, we find differential signatures of positive selection between the two island populations in genes associated with neurology and development, indicating potential local adaptation. Furthermore, we identified an extremely polymorphic region on chromosome 10 with evidence of shared haplotypes in both wild and commercial bees, which may represent long-standing genetic variation at the continental level or potential localized admixture between wild and commercial bees. Collectively, our findings inform on the genetic distinctiveness of these island bumblebees, emphasizing the applied need to genetically characterize natural populations to ensure the conservation of genetic resources—in the context of this study, by informing risk-assessment and management of commercial bumblebees. In addition, our study reinforces the utility of genomic approaches in the biomonitoring of isolated or regionally adapted insect pollinator populations, which will contribute towards the effective conservation of these ecologically vital organisms
Reinforcement learning in condition-based maintenance: a survey
No full textThis literature review examines the convergence of Reinforcement Learning (RL) and Condition-Based Maintenance (CBM), emphasizing the trans- formative impact of RL methodologies on maintenance decision-making in com- plex industrial settings. By integrating insights from a diverse array of studies, the review critically assesses the use of various RL techniques such as Q-learning, deep reinforcement learning, and policy gradient approaches in forecasting equipment failures, optimizing maintenance schedules, and reducing operational downtime. It outlines the shift from conventional, rule-based maintenance practices to adaptive, data-driven strategies that exploit real-time sensor data and probabilistic modeling. Key challenges highlighted include computational complexity, the extensive training data requirements, and the integration of RL models into existing industrial frameworks. Furthermore, the review explores literature on CBM within multi-component systems, where prevalent approaches include numerical analyses, Markov Decision Processes (MDPs), and case studies, all of which demonstrate notable cost reductions and decreased downtime. Relevant studies were identified through searches on databases such as Google Scholar, Scopus, and Web of Science. Overall, this review provides a comprehensive analysis of the current state and prospects of employing reinforcement learning in condition-based maintenance, offering valuable insights for both academic researchers and industry practitioners
A route optimization approach for incentivizing self-pickups in last-mile deliveries
No full textCOVID-19 has further accelerated the growth of e-commerce, stimulating the demand for last-mile deliveries. Parcel lockers (PLs) allowing self-pickups offer a remedy to mitigate the adverse effects associated with traditional door-to-door deliveries. However, consumer preference for free or cheap home delivery remains a substantial obstacle to the widespread adoption of PLs. Thus, e-commerce companies and logistics service providers (LSPs) may need to devise effective incentive strategies so that customers opt for receiving their orders from PLs. In this study, we first investigate potential savings for LSPs by employing PLs instead of customer addresses as delivery points and adopting a route-optimization approach. Our computational experiments reveal a substantial reduction in delivery fleet travel distance and size, indicating potential cost savings up to 78.9%. Then, we examine various incentive mechanisms through which LSPs may share the savings with the customers, finding that distance-based incentives offer the highest gain. Nevertheless, our sensitivity analyses underscore that the savings may significantly diminish if PLs have highly limited capacities or customers prefer collecting their orders only from the nearest PL