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This study investigates polymer nanocomposite films fabricated via the casting method, blending polyvinyl alcohol (PVA) with varying percentages of Er2O3 nanoparticles. X-ray diffraction analysis (XRD) confirms the semi-crystalline structure and high crystallinity of 40 nm Er2O3 nanoparticles, compatible with PVA. Fourier-transform infrared spectroscopy (FTIR) confirms the absence of new chemical bonds, while Raman spectroscopy hints at potential interactions between Er3+ ions and PVA hydroxyl groups. UV-visible spectra reveal Er2O3's influence on optical properties, and photoluminescence spectroscopy demonstrates significant alterations in emission profiles upon nanoparticle inclusion. Differential scanning calorimetry (DSC) unveils distinct thermal transitions in PVA. The presence of well-defined endothermic peaks in nanocomposite films with 10 wt % and 20 wt % doping of Er2O3 nanoparticles confirms the crystalline nature of polymer nanocomposite films. The melting point temperature of Er2O3/PVA nanocomposites was increased compared to PVA. Electrical analysis reveals that the 10% Er2O3 composite exhibits both lower activation energies and the highest conductivity (1,188 10− 7 S/cm), suggesting efficient charge transport. Interestingly, the presence of Maxwell-Wagner-Sillars (MWS) polarization is only observed in the 10% Er2O3 case (0.182 kJ/mol), reducing the overall electrical resistance and dielectric losses. Dielectric spectroscopy reveals diverse relaxation processes. These findings, highlighting compatibility, distinct thermal and electrical behaviors, and potential chemical interactions, suggest exciting possibilities for PVA/ Er2O3 nanocomposites in various technological applications. [ABSTRACT FROM AUTHOR]

Polyolefins are the most widely produced type of plastics owing to their low production cost and favorable properties. Their polymer backbone consists solely of inert C-C bonds, making them resistant and durable materials. Although this is an extremely useful attribute during their use phase, it complicates chemical recycling. In this work, different types of polyethylenes (PEs) are converted into ketone-functionalized PEs with up to 3.4% functionalized carbon atoms, in mild conditions (≤100 °C), using a titanosilicate catalyst and tert-butyl hydroperoxide as the oxidant. Subsequently, the introduced ketones are exploited as sites for heteroatom insertion. Through Baeyer-Villiger oxidation, in-chain esters are produced with yields up to 73%. Alternatively, the ketones can be converted into the corresponding oxime, which can undergo a Beckmann rearrangement to obtain in-chain amides, with yields up to 75%. These transformations allow access to polymers that are amenable to solvolysis, thereby enhancing their potential for chemical recycling. Chemical recycling of polyolefins continues to pose challenges. This research introduces ketones into polyethylene using a titanosilicate catalyst and transforms them into in-chain esters or amides, resulting in polymers suitable for closed-loop recycling. [ABSTRACT FROM AUTHOR]

Nuclear power plants are aging around the world, and a precise assessment of irradiation damage in their components is needed. One key component, concrete, and specifically the silicates in its aggregates, can undergo significant expansion upon neutron radiation, which can lead to cracking and, ultimately, structural failure. However, assessing and predicting the extent of damage via neutron radiation is challenging due to reasons such as residual radioactivity and, most importantly, the high time involved. Here, we evaluate whether ion radiation can be a viable surrogate. Specifically, by employing Si2+ ion radiations and a comprehensive multi-modal imaging protocol, we report mineral-specific responses for key silicates such as quartz, albite, anorthite, and microcline. We find that 10 MeV Si2+ ions result in mineral expansions that are remarkably comparable to neutron radiation equivalent expansions (R2 = 0.86, RMSE = 1.29%), opening up pathways towards rapid assessment of silicates subject to irradiation. [ABSTRACT FROM AUTHOR]

Today, SF is a natural polymer with unique features, such as excellent mechanical properties, biocompatibility, biodegradability, and low toxicity, which characterize this material with diverse forms for different purposes. Silk nanoparticles, scaffolds, films, and mats are used in various therapeutic and diagnostic strategies including drug/gene delivery, tissue engineering, biomolecule detection, and wound healing. Therefore, a study that examines all SF applications and evaluates its toxicity helps researchers in future projects. In this study, we comprehensively searched all sources of databases in different years about the medical application of various types of SF. Also, we reviewed the toxicity of SF. Several newer papers were selected for reporting and conclusions. In conclusion, the evaluation of the literature revealed that SF is a promising candidate for a wide range of biomedical applications. [ABSTRACT FROM AUTHOR]

The tensile deformation behaviour of blended polyethylene (PE) was studied using molecular dynamic methods. The blended PE was modeled by blending linear chains with different molecular weights based on a united atom model. The mechanical response and microscopic conformational behaviours of blended PE were investigated at different strain rates and temperatures. The interatomic energy evolution displayed a similar trend to the stress–strain curve showing the stiffness of blended PE increase with a higher fraction of chain with high molecular weight. The microstructure metrics associated with free volume, orientation, entanglement and crystallisation were recorded as a function of strain in detail to obtain insight into the role of PE chains with different molecular weights for blended PE during deformation. The conformation evolution indicates that orientation and disentanglement are more noticeable in the short chain with low molecular weight in a blended PE system, while the long chain promotes the crystallisation of the initial chain structure. The chain entanglement evolution clearly shows some new flexion nodes created to entangle short chains again, implying that re-entanglement might exist during the tensile deformation. [ABSTRACT FROM AUTHOR]

According to World Health Organization (WHO), on average, 0.5 Kg of hazardous waste is generated per bed every day in high-income countries. The adverse effects imposed by synthetic materials and chemicals on the environment and humankind have urged researchers to explore greener technologies and materials. Amidst of all the natural fibers, silk fibroin (SF), by virtue of its superior toughness (6 × 104∼16 × 104 J/kg), tensile strength (47.2–67.7 MPa), tunable biodegradability, excellent Young's modulus (1.9–3.9 GPa), presence of functional groups, ease of processing, and biocompatibility has garnered an enormous amount of scientific interests. The use of silk fibroin conjoint with purely natural materials can be an excellent solution for the adverse effects of chemical-based treatment techniques. Considering this noteworthiness, vigorous research is going on in silk-based biomaterials, and it is opening up new vistas of opportunities. This review enswathes the structural aspects of silk fibroin along with its potency to form composites with other natural materials, such as curcumin, keratin, alginate, hydroxyapatite, hyaluronic acid, and cellulose, that can replace the conventionally used synthetic materials, providing a sustainable pathway to biomedical engineering. It was observed that a large amount of polar functional moieties present on the silk fibroin surface enables them to compatibilize easily with the natural additives. The conjunction of silk with natural additives initiates synergistic interactions that mitigate the limitations offered by individual units as well as enhance the applicability of materials. Further the current status and challenges in the commercialization of silk-based biomedical devices are discussed. Use of natural additive loaded silk fibroin: A sustainable approach towards health care. [ABSTRACT FROM AUTHOR]

The structural characteristics of silk secretion of the freshwater mite Limnesia maculata (O.F. Müller) (Acariformes, Limnesiidae) are described and analyzed for the first time based on light, atomic force and electron-microscopical approaches. The common dermal glands (14 pairs scattered over the body) produce silk mostly during the warm summer season. The process of silk secretion lasts from several hours to several days. The silk may appear like barely recognized clouds of a fine whitish substance. An individual silk thread is an indefinitely long uniform unbranched and non-stretchable tube, hollow or with a vesicular electron-dense residual content. In the silk bundle, threads may be freely interlaced, bent, curved or occasionally broken. The diameter of the tubes is in the range of 0.9–1.5 µm. The width of the tube walls varies greatly from 60 to 300 nm. Chaotically interlaced fine fibrils build the tube walls. On the external surface of the tube wall, these fibrils are loosely organized and frequently rising vertically, whereas on the internal side they are packed more tightly sometimes showing a mesh. The walls may reveal a layered structure or, contrary, are quite thin with through foramens. The revealed organization of silk in the freshwater mites is found to be the simplest among that of other arthropods. We propose a role of the silk in the capture of potential prey in the summer season. Silk in water mites significantly widens the wholesome area for the mites' life and gives them better chances in competition for potential resources. [ABSTRACT FROM AUTHOR]

A second study of ferriallanite-(Ce) from Nya Bastnäs, Sweden, extends current data by using electron probe micro-analysis (EPMA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis and brings new insights about its crystal chemistry obtained by Raman spectroscopy. The study presents the first Raman spectra for ferriallanite-(Ce) member of the allanite group (not considering the rather low-quality spectra published in preceding papers). The material does not show significant radiation damage, which is rare as allanite-group minerals often have undergone metamictisation due to significant amounts of incorporated radionuclides (U, Th). Some interior regions show pronounced zoning that correlates with variations in Raman-band positions. In spite of its significant REE content, the material is virtually non-luminescent. New additional data for allanite-(Ce) from Oßling, Germany and Domanínek, Czech Republic are also presented, which were used for comparison. [ABSTRACT FROM AUTHOR]

The new mineral nishanbaevite, ideally KAl2O(AsO4)(SO4), was found in sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with euchlorine, alumoklyuchevskite, langbeinite, urusovite, lammerite, lammerite-β, ericlaxmanite, kozyrevskite, and hematite. Nishanbaevite occurs as long-prismatic or lamellar crystals up to 0.03 mm typically combined in brush-like aggregates and crusts up to 1.5 mm across. It is transparent, colourless, with vitreous lustre. Dcalc = 3.012 g cm− 3. Nishanbaevite is optically biaxial (–), α = 1.552, β ≈ γ = 1.567. The chemical composition (average of seven analyses) is: Na2O 3.79, K2O 8.01, CaO 0.10, CuO 0.21, Al2O3 30.08, Fe2O3 0.50, SiO2 1.62, P2O5 0.66, As2O5 32.23, SO3 22.59, total 99.79 wt%. The empirical formula calculated based on 9 O apfu is: (K0.57Na0.41Ca0.01)Σ0.99(Al1.99Fe3+0.02Cu0.01)Σ2.02(As0.95S0.95Si0.09P0.03)Σ2.02O9. Nishanbaevite is orthorhombic, Pbcm, a = 15.487(3), b = 7.2582(16), c = 6.6014(17) Å, V = 742.1(3) Å3 and Z = 4. The strongest reflections of the powder XRD pattern [d,Å(I)(hkl)] are: 15.49(100)(100), 6.56(30)(110), 4.653(29)(111), 3.881(54)(400), 3.298(52)(002), 3.113(29)(121), and 3.038(51)(202, 411). The crystal structure, solved from single-crystal XRD data (R = 7.58%), is unique. It is based on the complex heteropolyhedral sheets formed by zig-zag chains of Al-centred polyhedra (alternating trigonal bipyramids AlO5 and octahedra AlO6 sharing edges) and isolated tetrahedra AsO4 and SO4. Adjacent chains of Al polyhedra are connected via AsO4 tetrahedra to form a heteropolyhedral double-layer. Its topological peculiarity is considered and compared with those in structurally related compounds. The (K,Na) site is located in the interlayer space between SO4 tetrahedra. The position of nishanbaevite among the arsenate-sulfates and their specific structural features are discussed. The mineral is named in honour of the Russian mineralogist Tursun Prnazorovich Nishanbaev (1955–2017). [ABSTRACT FROM AUTHOR]

Spider silk fibres have unique mechanical properties due to their hierarchical structure and the nanoscale organization of their proteins. Novel imaging techniques reveal new insights into the macro- and nanoscopic structure of Major (MAS) and Minor (MiS) Ampullate silk fibres from pristine samples of the orb-web spider Nephila Madagascariensis. Untreated threads were imaged using Coherent Anti-Stokes Raman Scattering and Confocal Microscopy, which revealed an outer lipid layer surrounding an autofluorescent protein core, that is divided into two layers in both fibre types. Helium ion imaging shows the inner fibrils without chemical or mechanical modifications. The fibrils are arranged parallel to the long axis of the fibres with typical spacing between fibrils of 230 nm ± 22 nm in the MAS fibres and 99 nm ± 24 nm in the MiS fibres. Confocal Reflection Fluorescence Depletion (CRFD) microscopy imaged these nano-fibrils through the whole fibre and showed diameters of 145 nm ± 18 nm and 116 nm ± 12 nm for MAS and MiS, respectively. The combined data from HIM and CRFD suggests that the silk fibres consist of multiple nanoscale parallel protein fibrils with crystalline cores oriented along the fibre axes, surrounded by areas with less scattering and more amorphous protein structures. [ABSTRACT FROM AUTHOR]

Plastic take-out food containers may release microplastics (MPs) into food and pose a potential risk to food safety and human health. Here, after being subjected to hot water treatment, MPs released from three types of plastic food containers (polypropylene, PP; polyethylene, PE; expanded polystyrene, EPS) were identified by micro-Raman spectroscopy. The results showed that the size of released MPs ranged from 0.8–38 μm and over 96% MPs were smaller than 10 μm. Various MPs concentrations were found from the three types of containers, that is, 1.90 × 104, 1.01 × 105, and 2.82 × 106 particles/L on average from PP, PE, and EPS, respectively. Moreover, based on thermal and morphology analysis, we discovered that both relaxations of the polymer chains in the rubbery state and defects caused by processing techniques might contribute to the release of MPs. Thus, such release can be reduced by increasing the thermal stability of the materials and mitigating the defects generated during production. [ABSTRACT FROM AUTHOR]

Development of more sustainable and environmentally friendly polymers as alternatives to petroleum‐based polymers is a priority. We report the synthesis of six linear, aliphatic, renewable polymers by acyclic diene metathesis (ADMET) and thiol‐ene polymerization of α,ω‐polyenes resulting from thermal esterification of adipic, azelaic, and itaconic acids with 9‐decen‐1‐ol. ADMET homopolymerization was performed with 1.0 mol% Hoveyda–Grubbs second generation metathesis catalyst. Thiol‐ene copolymerization was conducted photochemically with 1 wt% 2,2‐dimethoxy‐2‐phenyl‐acetophenone and stoichiometric 1,2‐ethanedithiol (EDT). Although the thiol‐ene copolymers exhibited carbon and atom economies of 100%, the ADMET‐derived polyesters possessed superior renewable carbon content (100%) and environmental factors (<4). These results were attributed to incorporation of non‐renewable EDT into poly(thioether‐ester)s and loss of ethene during production of ADMET polyesters. The Mn (>26 kDa), Mw (>92 kDa), and dispersities (>3.4) of the poly(thioether‐ester)s were higher than the corresponding polyesters, which in part explained why the poly(thioether‐ester)s gave higher melting (>61°C), crystallization (>49°C) and glass transition (>−31°C) temperatures. The cross‐linked itaconate polymers did not melt or crystallize, thereby suggesting amorphous morphology. Lastly, the ADMET polyesters were more thermally stable (T50 > 408°C) than the poly(thioether‐ester)s (T50 < 377°C). In summary, the aliphatic biopolymers displayed a wide range of properties that were impacted by polymerization method as well as the nature of the monomer. [ABSTRACT FROM AUTHOR]

Enthesis, the interfacial tissue between a tendon/ligament and bone, exhibits a complex histological transition from soft to hard tissue, which significantly complicates its repair and regeneration after injury. Because traditional surgical treatments for enthesis injury are not satisfactory, tissue engineering has emerged as a strategy for improving treatment success. Rapid advances in enthesis tissue engineering have led to the development of several strategies for promoting enthesis tissue regeneration, including biological scaffolds, cells, growth factors, and biophysical modulation. In this review, we discuss recent advances in enthesis tissue engineering, particularly the use of biological scaffolds, as well as perspectives on the future directions in enthesis tissue engineering. [ABSTRACT FROM AUTHOR]

Spider silk has garnered attention as a structural material and a medical resource for next generation because it is tough, lightweight, and biodegradable. Nonwoven silk fabrics are emerging in research and industries owing to advanced electrospinning techniques. Several studies have reported nonwoven fabrics made of spider silk‐like proteins, which are originated from recombinant expression systems, with lower molecular weights than the natural counterpart. The lower molecular weight causes a lack of mechanical strength and durability, preventing the evaluation of industrial potential of the spider silk‐based nonwoven fabric to use as a structural and medical material. In this study, an electrospun nonwoven fabric is produced using native spider silk fibers forcibly reeled from live spiders. The spider silk‐based nonwoven fabrics demonstrate cell compatibility, and the mechanical properties are superior to the silkworm silk‐based nonwoven fabrics. The availability of spider silk‐based nonwoven fabrics introduces an unexplored set of potential uses, along with the context of sustainable development goals. [ABSTRACT FROM AUTHOR]

Transmission electron microscopy analyses of the polymineralic regolith particle RC-MD01-0025 show microstructural and microchemical characteristics indicative of space weathering on the surface of asteroid Itokawa. The depletion of sulfur and nickel was identified in space weathered rims on troilite and pentlandite minerals. This corresponds to the first report of nickel depletion in samples returned from asteroid Itokawa by the Hayabusa mission. Microstructurally, the sulfide minerals present crystalline rims and the olivine presents both crystalline and amorphous zones in the rim. These results suggest that sulfides might be more resistant to amorphization caused by solar wind irradiation. The space weathering features identified in the regolith particle analyzed here are likely formed via solar wind irradiation. Additionally, the differences in the space weathering features in olivine, pentlandite, and troilite suggest that silicates and sulfides respond differently to the same space weathering conditions in interplanetary space. [ABSTRACT FROM AUTHOR]

Nanofibrils play a pivotal role in spider silk and are responsible for many of the impressive properties of this unique natural material. However, little is known about the internal structure of these protein fibrils. We carry out polarized Raman and polarized Fourier-transform infrared spectroscopies on native spider silk nanofibrils and determine the concentrations of six distinct protein secondary structures, including β-sheets, and two types of helical structures, for which we also determine orientation distributions. Our advancements in peak assignments are in full agreement with the published silk vibrational spectroscopy literature. We further corroborate our findings with X-ray diffraction and magic-angle spinning nuclear magnetic resonance experiments. Based on the latter and on polypeptide Raman spectra, we assess the role of key amino acids in different secondary structures. For the recluse spider we develop a highly detailed structural model, featuring seven levels of structural hierarchy. The approaches we develop are directly applicable to other proteinaceous materials. Secondary fibril structure is a key component of the mechanical properties of protein materials like silk, yet, limited information is known about the internal structure of these protein fibrils. Here, the authors report on the use of polarised Raman and FTIR spectroscopy to study silk materials and identify six distinct secondary structures. [ABSTRACT FROM AUTHOR]

A reciprocating tribometer has been modified with a high-impedance electronic measurement circuit for the purpose of addressing the question of how tribology influences triboelectric charging. This measurement circuit allows for the accurate measurement of potential difference, induced current, and total triboelectric charge generated within the tribometer contact. These electronic properties can now be effectively compared with tribological parameters such as contact force, relative sample velocity, and friction coefficient (μ ) for varying contacts. In this study we present our apparatus, alongside our findings regarding the influence of material wear mechanisms and friction on the accumulation and dissipation of triboelectric contact charges. [ABSTRACT FROM AUTHOR]

High-performance polymer fibres offer promising tensile and physical properties but are rarely used in structural composite applications due to their poor compressive performance. To better understand their performance inside a composite, unidirectional thermoset composites made with three types of polymer fibres were tested in shear-loaded compression. The results confirmed the poor compressive performance of the composites despite good fibre alignment, low porosity, and decent interfacial adhesion. Showing that the fibres collapse rather than microbuckle proves that intrinsic fibre behaviour in compression is the key culprit. The developed finite element model predicted that the short gauge lengths required to avoid buckling lead to significant strain concentrations due to the grips. This causes the test to underestimate the compressive modulus and potentially the rest of the compressive stress in the stress–strain diagram. [ABSTRACT FROM AUTHOR]

Polytetrafluoroethylene (PTFE) is a ubiquitous material used for implants and medical devices in general because of its high biocompatibility and inertness: blood vessel, heart, table jawbone, nose, eyes, or abdominal wall can benefit from its properties in case of disease or injury. Its expanded version, ePTFE is an improved version of PTFE with better mechanical properties, which extends its medical applications. A material as frequently used as ePTFE with these exceptional properties deserves a review of its main uses, developments, and possibility of improvements. In this systematic review, we examined clinical trials related to ePTFE‐based medical devices from the literature. Then, we excluded all trials using ePTFE as a control to test other devices. ePTFE‐coated stents, hemodialysis and bypass grafts, guided bone and tissue regeneration membranes, hernia and heart repair and other devices are reviewed. The rates of success using these devices and their efficiency compared to other materials used for the same purposes are reported. ePTFE appears to be more or just as efficient compared to them. Some success rates remain low, suggesting the need of improvement ePTFE for medical applications. [ABSTRACT FROM AUTHOR]

Enthesis, the interfacial tissue between a tendon/ligament and bone, exhibits a complex histological transition from soft to hard tissue, which significantly complicates its repair and regeneration after injury. Because traditional surgical treatments for enthesis injury are not satisfactory, tissue engineering has emerged as a strategy for improving treatment success. Rapid advances in enthesis tissue engineering have led to the development of several strategies for promoting enthesis tissue regeneration, including biological scaffolds, cells, growth factors, and biophysical modulation. In this review, we discuss recent advances in enthesis tissue engineering, particularly the use of biological scaffolds, as well as perspectives on the future directions in enthesis tissue engineering. [ABSTRACT FROM AUTHOR]