Search Results (129)

Different polyurethanes (PURs) and silicone for potential use in particle accelerators and detectors have been characterized in the uncured state, after curing, and after exposure to ionizing irradiation in ambient air and in liquid helium. The viscosity evolution during processing was measured with a rheometer. Dynamic mechanical analysis (DMA) and Shore A hardness measurements were applied to detect irradiation-induced crosslinking and chain scission effects. Uniaxial tensile and flexural tests under ambient and cryogenic conditions have been performed to assess changes in mechanical strength, elongation at break, and elastic properties. The initial viscosity of 550 cP at 25 °C of the uncured PUR RE700-4 polyol and RE106 isocyanate system for protective encapsulation is sufficiently low for impregnation of small magnet coils, but the pot life of about 30 min is too short for impregnation of large magnet coils. The cured RE700-4 system has outstanding mechanical properties at 77 K (flexural strength, impact strength, and fracture toughness). When RE700-4 is exposed to ionizing radiation, chain scission and cross-linking occur at a similar rate. In the other casting systems, irradiation-induced changes are cross-linking dominated, as manifested by an increase of the rubbery shear modulus (G’_rubbery), the ambient temperature Young’s modulus (E_RT), and the Shore A hardness. Cross-linking rates are strongly reduced when irradiation occurs in liquid helium. The irradiation effect on mechanical properties can be strongly dependent on the testing temperature. The RT mechanical strength and strain at fracture of the cross-linking silicone is drastically decreased after 1.6 MGy, whereas its 77 K strain at fracture has almost doubled. In addition, 77 K elastic moduli are similar for all pure resins and only slightly affected by irradiation. Full article

In this work, we present an innovative, crosslinker-free method for preparing chitosan-based hydrogel precursors, fully aligned with green chemistry principles and composed of only five non-toxic, readily available reagents. The key novelty lies in the use of glycerin, which, during thermal annealing, evaporates and triggers a surface or bulk chemical transformation of chitosan, depending on its concentration. This process significantly enhances the material’s mechanical properties after swelling—with up to a 35% increase in tensile strength and a notable reduction in water uptake compared to systems containing AMPS-based crosslinkers. FTIR analysis indicates a partial re-acetylation of chitosan, shifting its structure toward that of chitin, which correlates with improved hydrophobicity (as shown by increased contact angles up to 92°) and greater structural integrity. These improvements are particularly pronounced at glycerin concentrations of 10–20%, whereas higher concentrations (50%) result in brittle, non-moldable films. Importantly, preliminary biological tests confirm that the resulting hydrogels are effectively colonized by mammalian cells, making them promising candidates for bioimplant or tissue engineering applications. Surface morphology and compatibility were further assessed via SEM, AFM, and contact angle measurements. Full article

The delayed healing and infection risks associated with chronic wounds and burns pose significant clinical challenges. Traditional dressings provide basic coverage but lack the bioactive properties needed for tissue regeneration and antimicrobial protection. In this study, we developed zinc alginate hydrogel-coated traditional wound dressings (WD@AlgZn) and evaluated their physicochemical properties, antimicrobial performance, and in vivo healing efficacy. Scanning electron microscopy (SEM) revealed a uniform coating of the zinc alginate network on dressing fibers, while Fourier-transform infrared spectroscopy (FT-IR) confirmed the successful incorporation of zinc ions. Antimicrobial assays further demonstrated that WD@AlgZn reduced bacterial loads (CFU/mL counts) by several orders of magnitude for both Staphylococcus aureus and Escherichia coli compared to uncoated controls. An in vivo rat burn wound model exhibited accelerated wound closure when using WD@AlgZn dressings compared to conventional wound care approaches, achieving a 90.75% healing rate by day 21, significantly outperforming the silver sulfadiazine (52.32%), uncoated-dressing (46.58%), and spontaneous-healing (37.25%) groups. Histological analysis confirmed enhanced re-epithelialization, neovascularization, and reduced inflammation in WD@AlgZn-treated tissues. The findings suggest that WD@AlgZn offers a promising alternative for advanced wound management, combining structural robustness with bioactive properties to support efficient wound healing and infection control. These results provide valuable insights into the potential clinical applications of metal-ion cross-linked biopolymeric hydrogel dressings for next-generation wound care strategies. Full article

This work focuses on the hydrothermal aging of two-dimensional layered Ti₃C₂T_x (MXene)/epoxy (EP) nanocomposites. MXene/EP composites were successfully prepared by homogeneously dispersing multilayer MXene (m-MXene) and few-layer MXene (f-MXene) into the curing agent, methyl nadic anhydride (MNA). Considering the application, the MXene loading was designed to be 0.1 wt.%. Characterization included the characteristics of MXene, the water absorption behavior of the resin and composite samples, the glass transition temperatures (T_g) in various states, and the tensile strength evolution during aging. The curing behavior of the MXene composites was also discussed to facilitate an understanding of the processability. The results showed that MNA can chemically bond with MXene to obtain a stable suspension. The addition of MXene increased the curing characteristic temperature of the system, but the change in the activation energy of the curing reaction was minimal. The addition of MXene decreased the crosslink density of the epoxy resin, leading to a decrease in the T_g value of the initial samples. After hydrothermal aging, the T_g of pure EP decreased by 46.9 °C, and re-drying the samples did not fully restore the T_g. However, the T_g of the MXene/EP system decreased by only 8.9 °C (m-MXene) and 9.5 °C (f-MXene), respectively, and the T_g values of the samples were fully restored to their pre-aging levels via re-drying. Experiments with immersion at 25 °C and 100 °C showed that the difference in water absorption behavior between the MXene/EP and pure EP systems was minimal. Tensile tests showed that the addition of MXene increased the initial strength of the resin system by 14.7% (m-MXene) and 20.9% (f-MXene). After 400 h of hydrothermal aging, the tensile strength retention of the pure EP samples was 69.1%, while the strength retention of the MXene/EP samples was 85.3% (m-MXene) and 83.0% (f-MXene). The combined results demonstrate that the addition of MXene with a low loading of only 0.1% can effectively improve the hydrothermal resistance of epoxy resins. Full article

Introduction: Hair damage from chemical treatments, mechanical stress, and environmental factors can lead to significant degradation in hair quality, necessitating effective solutions for restoration. The aim of this study was to develop and evaluate novel compounds for repairing hair damage through the chemical regeneration of disulfide bridges. Materials and Methods: Three novel thiol-reactive cross-linking agents (APA, STA, SAA) were synthesized and characterized. Their efficacy in repairing hair damage was evaluated through in vitro tensile strength tests on human hair fibers, comparing treated and untreated samples. Cysteine reactivity tests were also performed to assess the capability of these agents to restore disulfide bridges in hair keratin. Results: The tensile strength tests revealed significant improvements in the mechanical properties of treated hair fibers compared to untreated samples. APA demonstrated the highest efficacy in restoring tensile strength and elasticity, showing higher performance in mechanical strengthening. The cysteine reactivity tests confirmed that APA could effectively re-establish disulfide bonds, particularly at higher temperatures. STA, while less effective than APA, showed substantial efficiency in restoring disulfide bonds. When compared to the reference agent, both APA and STA exhibited higher performance in tensile strength and cysteine reactivity, with APA showing the greatest improvement in mechanical properties. Conclusions: Our study successfully revealed the potential of the synthesized thiol-reactive cross-linking agents in repairing hair damage by chemically regenerating disulfide bridges. These findings offer a promising new direction for the development of advanced hair repair treatments in the cosmetic industry. Full article

Background: The wound healing process presents notable challenges for nursing teams, requiring extensive knowledge of wound care materials. A nanoparticle-free, bioabsorbable pol-yvinyl alcohol (PVA) with citric acid (CA) dressing produced by simple electrospin-ning was evaluated to treat acute wound healing in rats. This PVA-CA combination promotes crosslinking, increases the dressing capacity of absorption and confers heal-ing properties due to the citric acid antioxidant action. Methods: The dressing was tested in a quantitative experiment on 1.9 cm acute dermatological lesions in rats (n = 12), com-paring the PVA-CA-treated group with the untreated control group (CG). Samples were collected at 3, 7 and 14 days after lesion induction to evaluate the inflammatory process and tissue healing. Results: The macroscopic and histological data on the third day showed similar characteristics in both groups; however, after fourteen days, the PVA-CA group exhibited complete healing, accompanied by recomposition of the skin layers, whereas the wounds in the CG did not close completely. Conclusions: The results highlight that electrospun PVA-AC dressings improve healing outcomes and constitute a prom-ising and affordable solution, providing a suitable environment for tissue repair, re-ducing inflammatory cell infiltration, blood vessel formation, and restoration of epi-thelial tissue, reducing the time of the healing process of acute wounds. Full article

Aramid nanofiber (ANF), a nanoscale building block with a prominently complex structure, can be prepared by splitting poly(p-phenylene terephthalamide) (PPTA) fibers into negatively charged ANFs in a deprotonating manner in a DMSO/KOH solvent system, followed by a subsequent re-protonation process using a proton-donor reagent. There are rare reports regarding the utilization of an aprotic donor reagent to convert deprotonated ANF dispersion into film or gel with a controllable structure and high mechanical properties. In this work, dichloromethane, as an anhydrous aprotic donor solvent, has been introduced into the deprotonated ANF dispersion to replace DMSO, containing PPTA molecules and hydroxyl ions, leading to the gelation of deprotonated ANF dispersions, forming a film (ANF_DCM) possessing a surprisingly highly entangled and oriented structure, as proven by SEM results. Due to the attenuation of electrostatic repulsion in the dispersion, partially deprotonated ANFs intertwined and cross-linked through π–π conjugation among a large number of benzene rings in PPTA molecules. After treating ANF_DCM with water for re-protonation, the as-prepared film (ANF_DCM-W) exhibited high tensile strength (307.7 MPa) and toughness (74.7 MJ m⁻³). Full article

Furan/maleimide dynamic covalent chemistry has been extensively used to fabricate re-workable and self-healing thermosets. Understanding the relationship between crosslinker structure, network dynamics, and material final properties, however, remains a challenge. This study introduces self-healing and shape-memory thermosets derived from furan-functionalized polyketones (PKFU) crosslinked with aromatic bis-maleimides, i.e., 1,1′-(methylenedi-4,1-phenylene)bis-maleimide (BISM1) and bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (BISM2), via a thermally reversible Diels-Alder reaction. Polyketones were chemically modified with furfurylamine through the Paal-Knorr reaction, achieving varying furan grafting ratios. The resulting networks, characterized by ATR-FTIR, ¹H-NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and rheology, demonstrated tunable thermomechanical properties. BISM2-based thermosets exhibited enhanced thermal stability and reversibility over a broad temperature range (20–120 °C), with a shape recovery ratio of up to 89% and complete self-healing at 120 °C within 5 min. These findings highlight the potential of polyketone-based thermosets for applications requiring adaptive thermomechanical properties, efficient self-repair, and sustainability. Full article

A physically and chemically cross-linked Al³⁺-CS/PAM-MBA dual-network gel with enhanced fire-suppression performance was prepared using chitosan (CS), acrylamide (AM), and N,N’-methylenebisacrylamide (MBA) as base materials. The first network was formed through the covalent cross-linking of polyacrylamide (PAM) with MBA, while the second network was established by crosslinking CS molecules with Al³⁺ ions. The optimal gel ratio was determined by evaluating its formation time and viscosity. The fire prevention and extinguishing performance of the gel was assessed through thermal stability analysis, temperature-programmed studies, infrared spectroscopy, thermal analysis, and fire-extinguishing experiments. The results indicated that the Al³⁺-CS/PAM-MBA dual-network gel exhibited excellent thermal stability and a strong self-ignition inhibition effect, effectively suppressing coal spontaneous combustion and oxidation. The gel achieved this by chemically inactivating coal molecules, disrupting the functional groups closely associated with coal–oxygen reactions and thereby hindering these reactions. Fire-extinguishing tests demonstrated that the gel restrained coal from spontaneous combustion. Upon application, the gel rapidly reduced the coal temperature, making re-ignition less likely. Full article

Food allergies are a global concern, with β-lactoglobulin (β-LG) in bovine milk being a major allergenic protein. This study investigated the effects of transglutaminase (TGase)-mediated crosslinking on the antibody recognition capacity (ARC) and structural properties of β-LG, with the aim of developing hypoallergenic dairy products. β-LG solutions were treated with TGase at varying concentrations (0, 5, 10, 15, and 20 U/g) and durations (0, 6, 18, 24, and 42 h), followed by analysis using electrophoresis, enzyme-linked immunosorbent assay (ELISA), and spectroscopy. The results demonstrated that treatment with TGase at 20 U/g significantly reduced the ARC and immunoglobulin E (IgE) binding capacity of β-LG to 90.0 ± 0.4% and 58.4 ± 1.0%, respectively, with the optimal ARC reduction observed after 6 h of treatment (86.7 ± 1.2%, p < 0.05). Although electrophoresis did not reveal significant crosslinking of β-LG, ultraviolet absorption, fluorescence intensity, and hydrophobicity all increased with prolonged crosslinking time, while sulfhydryl content fluctuated irregularly. These findings suggest that β-LG underwent varying degrees of structural modification, which led to the masking of antigenic epitopes during the early stages (0–24 h), followed by their re-exposure at the later stage (42 h). Overall, these results highlight the potential of TGase to reduce β-LG potential allergenicity, presenting a promising strategy for the development of hypoallergenic dairy products. Full article

The large-scale production of waste plastics has brought serious environmental pollution problems and its recycling and high value-added utilization technology remains a global challenge. Therefore, this study uses waste polyethylene (PE) to prepare high-performance polyethylene composite modified asphalt (HPEA), solving the problem of poor stability and low temperature performance of traditional plastic modified asphalt, while achieving high value-added utilization of waste plastics. A high-performance polyethylene composite modifier (HPE) was prepared through mechanochemical and thermochemical interactions. Then HPEA with different HPE content and styrene-butadiene-styrene (SBS) modified asphalt (SBSMA) with different SBS content were prepared. Compare and analyze the conventional performance, storage stability, anti-aging performance and microscopic properties of HPEA and SBSMA. The results are as follows: (1) the conventional performance of HPEA is comparable to, or superior to, that of SBSMA. The addition of HPE resulted in a significant decrease in asphalt penetration. The modification effect achieved by adding 3–5% SBS to Kunlun 70# asphalt is equivalent to that achieved by incorporating 4–6% HPE. (2) HEPA exhibits good storage stability and no obvious segregation phenomenon. When the HPE content changes from 4% to 8%, the maximum difference in 48 h softening point of HPEA is 1.1 °C, which is significantly smaller than the 48 h softening point difference of SBSMA when the SBS content changes from 3% to 5%. (3) When HPE attains a specific concentration, HPEA can exhibit an anti-aging performance that is comparable to, or superior to, that of SBSMA. (4) The infrared spectrum of HPEA closely resembles that of SK70# matrix asphalt. The modification of HPEA primarily involves physical blending, with HPE undergoing development and re-crosslinking within the system, leading to interactions between smaller particles and asphalt, resulting in the formation of a relatively stable three-dimensional spatial structure. Full article

This study aims to investigate the chemical recycling of two different fully recyclable bio-based epoxy matrices based on epoxidized precursors derived from waste flour. The key for their recyclability relies on the use of a cleavable hardener. In fact, the latter contains a ketal group in its chemical structure, which is cleavable in mild acetic conditions, so allowing for the breakage of the cured network. The recyclability was successfully assessed for both the two investigated formulations, with a recycling process yield ranging from 80 up to 85%. The recycled polymers presented a T_g up to 69.0 ± 0.4 °C, determined by mean of DMA and DSC analysis. Next, the TGA revealed that the thermal decomposition of the specimens primarily occurred around 320 °C and attributed to the breaking of C–O and C–N bonds in cross-linked networks. In the end, the chemical characterizations were carried out by mean of Py-GC/MS, MALDI-TOF-MS and FT-IR ATR. In fact, these analyses allowed for investigating how the recycled polymer’s structure changed, starting from the initial epoxy systems. These insights on their chemical structure could further allow for identifying re-use strategies in accordance with a circular economy approach. Full article

A recrosslinkable CO₂-resistant branched preformed particle gel (CO₂-BRPPG) was developed for controlling CO₂ injection conformance, particularly in reservoirs with super-permeable channels. Previous work focused on a millimeter-sized CO₂-BRPPG in open fractures, but its performance in high-permeability channels with pore throat networks remained unexplored. This study used a sandpack model to evaluate a micro-sized CO₂-BRPPG under varying conditions of salinity, gel concentration, and pH. At ambient conditions, the equilibrium swelling ratio (ESR) of the gel reached 76 times its original size. This ratio decreased with increasing salinity but remained stable at low pH values, demonstrating the gel’s resilience in acidic environments. Rheological tests revealed shear-thinning behavior, with gel strength improving as salinity increased (the storage modulus rose from 113 Pa in 1% NaCl to 145 Pa in 10% NaCl). Injectivity tests showed that lower gel concentrations reduced the injection pressure, offering flexibility in deep injection treatments. Gels with higher swelling ratios had lower injection pressures due to increased strength and reduced deformability. The gel maintained stable plugging performance during two water-alternating-CO₂ cycles, but a decline was observed in the third cycle. It also demonstrated a high CO₂ breakthrough pressure of 177 psi in high salinity conditions (10% NaCl). The permeability reduction for water and CO₂ was influenced by gel concentration and salinity, with higher salinity increasing the permeability reduction and higher gel concentrations decreasing it. These findings underscore the effectiveness of the CO₂-BRPPG in improving CO₂ sweep efficiency and managing CO₂ sequestration in reservoirs with high permeability. Full article

Objectives: To report a novel application within the USA of excimer ablation for the normalization of central corneal refractive irregularity, combined with higher fluence CXL in the effective management and visual rehabilitation of progressive keratoconus. Methods: 17 consecutive cases with progressive keratoconus were treated with corneal surface excimer laser ablation normalization using topography-guided (Contura) myopic ablation for customized corneal re-shaping with a 6 mm optical zone. The epithelial removal was accounted for by adding a −2.75 diopter correction to this topography-guided normalizing surface ablation followed by a second wavefront-optimized hyperopic excimer treatment of +2.75 diopters also with a 6 mm optical zone. The two sequential excimer ablations applied on the intact epithelium were followed by corneal crosslinking (CXL). Visual acuity, refraction, and keratoconus documentation via keratometry, topography, and pachymetry, as well as endothelial cell density were evaluated over 36 months. Results: Keratoconus stabilized in all cases. The severity and stage of keratoconus determined by the Amsler–Krumeich criteria improved for the OD from an average of 2.2 to 1. The median UDVA showed marked improvement at one-year follow-up (all values in LogMAR), from 0.8 preoperative to 0.3 at 12 months, and was stable through the 3 years at 0.3. The median CDVA increased from 0.5 to 0.1 at 1 year and was stable at 0.1 at 3 years. The average minimal corneal thickness decreased from 466 μm to 396 μm, as recorded the first year postoperatively, and then slightly increased to 405 μm at the 3-year follow-up. Conclusions: We introduce herein the initial clinical data for the use of a novel, off-label therapeutic excimer laser surface ablation application. It was designed to perform both epithelial removal and anterior corneal stroma reshaping and combined with CXL to apply the Athens Protocol CXL with US excimer laser-approved specifications. Full article

Objectives: This study aimed to investigate factors that influence the 12-month outcomes after the treatment of multiple gingival recessions (GRs) with a modified coronally advanced tunnel (MCAT) and a subepithelial connective tissue graft (SCTG), with cross-linked hyaluronic acid (HA, tests) or without (controls). Materials and Methods: Twenty-four patients with 266 GRs were treated. A logistic regression model was set to identify the baseline parameters that could predict the 12-month outcomes. The study protocol was registered at ClinicalTrials.gov (ID No. NCT05045586). Results: The evaluated clinical and esthetic parameters showed marked improvement in both groups without any statistically significant differences between the groups, with the exception of the soft tissue texture (STT). The STT was in favor of the HA group (0.96 versus 0.73, p = 0.0091). The likelihood of an MRC > 85%, of achieving CRC, and of gaining an RES = 10 was the highest for the incisors (reference group) and the lowest for the molars (OR = 0.046, p = 0.005). With each 1 mm increase in the baseline clinical attachment level, the odds of failure (MRC < 85%, not achieving CRC) increased, whereas each 1 mm increase in the baseline keratinized tissue width (KTW) improved the chances of an MRC > 85%, of achieving CRC, and of gaining an RES = 10. The application of HA increased the likelihood of a perfect RES more than twofold (OR = 2.683, p = 0.001). Conclusions: The application of HA improved the 12-month esthetic outcomes after the treatment of GRs with the MCAT technique. The baseline CAL, KTW, and tooth type predicted the 12-month MRC, CRC, and RES. An evaluation of the baseline characteristics of the surgical area might help clinicians develop individualized treatment plans. Full article