Search Results (50)

Medical textiles have gained significant attention for their ability to prevent the transmission of infectious diseases while ensuring the safety and comfort of healthcare professionals. This study focuses on modifying the surfaces of polyethylene terephthalate (PET) fabrics with titanium dioxide (TiO₂) nanoparticles (NPs) to enhance their antibacterial properties, thermophysiological comfort, and thermal insulation. The effects of varying volumes of the tetraisopropyl orthotitanate precursor on the functional properties of the coated PET fabrics were systematically investigated. The surface morphology was characterized using scanning electron microscopy (SEM). At the same time, the elemental and chemical properties were analyzed through Energy-dispersive spectroscopy (EDS), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). The TiO₂ NPs-coated PET fabrics demonstrated exceptional antibacterial activity against Gram-negative and Gram-positive bacteria and significantly improved thermophysiological comfort. Specifically, thermal resistance increased with a higher density of TiO₂ nanoparticles, leading to a decrease in thermal conductivity. Notably, only minimal reductions were observed in relative water vapor permeability (RWVP) and air permeability (AP), indicating that the fabric’s porosity was maintained. Furthermore, the presence of the TiO₂ nanolayer on the PET fabric significantly enhanced its thermal stability, providing excellent thermal insulation properties. These findings underscore the potential of TiO₂ NPs-coated PET fabrics as promising candidates for advanced medical textile applications, where a balance of protection, comfort, and thermal insulation is essential. Full article

This study addresses the critical issue of environmental pollution from plastic waste by investigating an effective chemical recycling method for polyethylene terephthalate (PET) via neutral catalytic hydrolysis. We utilized a recoverable and regenerable composite catalyst based on cracking zeolite and γ-Al₂O₃, which possesses both Brønsted and Lewis acidic sites that facilitate the depolymerization of PET into its constituent monomers, terephthalic acid (TPA) and ethylene glycol (EG). This investigation reveals that the catalytic performance is strongly dependent on the total acid site concentration and the specific nature of these sites. A key finding is that a balanced acidic profile with a high proportion of Brønsted acid sites is crucial for enhancing PET hydrolysis attributed to a significant decrease in the activation energy of the reaction. The experiments were conducted in a stirred stainless-steel autoclave reactor, where key parameters such as temperature (210–230 °C), the PET-to-water ratio (1:2 to 1:5), and reaction time were systematically varied. Under optimal conditions of 210 °C and a 6 h reaction time, the process achieved near-complete PET depolymerization (99.5%) and a high TPA yield (90.24%). The catalyst demonstrated remarkable recyclability, maintained its activity over multiple cycles and was easily regenerated. Furthermore, the recovered TPA was of high quality, with a purity of 98.74% as confirmed by HPLC, and exhibited a melt crystallization temperature 14 °C lower than that of the commercial standard. These results not only demonstrate the efficiency and sustainability of neutral catalytic hydrolysis using zeolite/alumina composites but also provide valuable insights for designing advanced catalysts with tunable acidic properties. By demonstrating the importance of tuning acidic properties, specifically the balance between Brønsted and Lewis sites, this work lays a foundation for developing more effective catalysts that can advance circular economy goals for PET recycling. Full article

Wood flour, a landscaping byproduct, poses disposal challenges due to its poor degradability, despite its potential as a sustainable material. This study modified wood powder by synergistically incorporating fly ash and TiO₂, followed by curing it with polyamide and epoxy resin to produce high-performance wood powder-based composites suitable for outdoor furniture applications, it can solve the environmental problems caused by fly ash. The research findings indicated that as the TiO₂ content increased, the material’s pore size diminished, structural strength improved, and it demonstrated enhanced hydrophobic properties and UV absorption capabilities. The optimal UV absorption performance was observed at a TiO₂ content of 1.5%. The combination of TiO₂ and fly ash led to the formation of more stable Si-O-Ti and Si-O-Si bonds, which further strengthened the material. Water contact angle and water repellency tests indicated that the 1.5% TiO₂ composite showed a 12% increase in compressive strength and a water contact angle of 100.6°, indicating improved hydrophobicity. The addition of TiO₂ reduced the number of free-OH groups within the matrix, thereby improving the composite’s hydrophobicity. Outdoor chairs fabricated by mixing 1.5% TiO₂-modified wood powder with PET for demolding exhibited excellent structural stability while also being safe and environmentally friendly. This study proposes a feasible preparation strategy for wood powder, enhancing durability through improved mechanical strength, water repellency, and UV shielding. Furthermore, it offers valuable insights into the material modification of wood powder-based materials for the production of outdoor garden furniture. Full article

The presence of PET (polyethylene terephthalate) in the environment is a global problem due to soil and water microplastic contamination. There is a constant demand for new technologies that expand the possibilities of PET disposal or recycling while reducing energy consumption and anthropogenic carbon footprint. In this study, we developed a comprehensive zero-waste management system for PET recycling (rPET) to cyclic ketals and terephthalic acid. The developed method is based on the hydrolysis of rPET flakes in an inert environment with the separation and purification of terephthalic acid and the dehydration of ethylene glycol. For the first time, we present the use of cheap and readily available Cr/SiO₂ and Fe/SiO₂ nanocatalysts for direct acetalization of ethylene glycol without organic co-solvents. The catalysts were characterized by EDXRF, XPS and TEM techniques. The 2,2-dimethyl-1,3-dioxolane (DMD), a product of ethylene glycol’s direct acetalization with acetone, was tested as a solvent for polymers with satisfactory results in the solubility of epoxy resins. The addition of unpurified terephthalic acid and residues constituting post-production waste to concrete allows for a reduction in the mass of concrete in the range of 11.3–23.4% and the material modified in this way allows for a reduction in concrete consumption. This rPET waste management methodology is consistent with the assumptions of the circular economy and allows for a significant reduction of anthropogenic CO₂ emissions. Full article

To develop membranes capable of efficient and switchable emulsion separation under variable pH conditions, pH-responsive surfaces were engineered on poly(ethylene terephthalate) track-etched membranes (PET TeMs) via a two-step UV-initiated RAFT graft polymerization process. Initially, polystyrene (PS) was grafted to render the surface hydrophobic, followed by the grafting of poly(methacrylic acid) (PMAA) to introduce pH-responsive carboxyl groups. Optimized conditions (117 mM MAA, RAFT:initiator 1:10, 60 min UV exposure at 10 cm) resulted in PET TeMs-g-PS-g-PMAA surfaces exhibiting tunable wettability, with contact angles shifting from 90° at pH 2 to 65° at pH 9. Successful grafting was confirmed by FTIR, AFM, SEM, TGA, and TB dye sorption. The membranes showed high degree of rejection (up to 98%) for both direct and reverse emulsions. In direct emulsions, stable flux values (70 ± 2.8 to 60 ± 2.9 L m⁻² h⁻¹ for cetane-in-water and 195 ± 8.2 to 120 ± 6.9 L m⁻² h⁻¹ for o-xylene-in-water) were maintained over five cycles at 900 mbar, indicating excellent antifouling performance. Reverse emulsions initially exhibited higher flux, but stronger fouling; however, flux recovery reached 91% after cleaning. These findings demonstrate the potential of PET TeMs-g-PS-g-PMAA as switchable, pH-responsive membranes for robust emulsion separation. Full article

This study investigates the modification and application of natural, micro-scale magnetite (Fe₃O₄)—an iron oxide mineral and one of the most abundant iron ores in the world—as a magnetic carrier for removing six common types of microplastics (MPs) from water: polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). Hexadecyltrimethoxysilane (HDTMS) was employed as a surfactant to modify the naturally hydrophilic magnetite, transforming it into a hydrophobic material. The characterization of magnetite treated with HDTMS for 0, 6, 12, 24, and 48 h was performed using a scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy (FT-IR). The results showed HDTMS sorption on the surface of natural magnetite, confirming successful surface modification. Carrier magnetic separation was then performed to remove PP, PE, ABS, PS, PET, and PVC using surface-modified, natural magnetite in two size fractions: +38–75 µm (fine-sized) and +75–150 µm (coarse-sized). Improved performance was observed with longer HDTMS treatment of magnetite, while greater than 90% MP removal was achieved using fine-sized, surface-modified, natural magnetite. These results suggest that surface modification enhanced the heterogenous interactions between magnetite and MPs via hydrophobic-hydrophobic interactions, leading to efficient MP removal via carrier magnetic separation. Full article

Chlorella sp. was cultivated in a closed system using PET bottles (5 L) and with the continuous injection of air and commercial gas (98% CO₂) and in simulated conditions (15% CO₂, 73% N₂, and 12% O₂). The culture medium was prepared using well water and mining wastewater, the cultivation period occurred in a 10-day cycle, and the cell growth curves were evaluated through cell counting using a Neubauer chamber. The cultivation was carried out under the following conditions: temperature at 22 °C to 25 °C; aeration rate with commercial and simulated CO₂ gas at 0.01 vvm; and synthetic air containing 0.042% CO₂. The dry biomass productivity was 0.81 g·L⁻¹·day⁻¹ and the maximum CO₂ fixation rate was 0.90 g·L⁻¹·day⁻¹ when the microalgae were cultivated with a continuous flow of simulated waste gas and a culture medium composed of wastewater. The percentages of macromolecules obtained in the biomass cultivated in wastewater reached 20.95%, 26.48%, and 9.3% for lipids, proteins, and carbohydrates, respectively. Full article

Flexible polymer-based piezoelectric nanogenerators (PENGs) have gained significant interest due to their ability to deliver clean and sustainable energy for self-powered electronics and wearable devices. Recently, the incorporation of fillers into the ferroelectric polymer matrix has been used to improve the relatively low piezoelectric properties of polymer-based PENGs. In this study, we investigated the effect of various nanofillers such as titania (TiO₂), zinc oxide (ZnO), reduced graphene oxide (rGO), and lead zirconate titanate (PZT) on the PENG performance of the nanocomposite thin films containing the nanofillers in poly(vinylidene fluoride-co-trifluoro ethylene) (P(VDF-TrFE)) matrix. The nanocomposite films were prepared by depositing molecularly thin films of P(VDF-TrFE) and nanofiller nanoparticles (NPs) spread at the air/water interface onto the indium tin oxide-coated polyethylene terephthalate (ITO-PET) substrate, and they were characterized by measuring their microstructures, crystallinity, β-phase contents, and piezoelectric coefficients (d₃₃) using SEM, FT-IR, XRD, and quasi-static meter, respectively. Multiple PENGs incorporating various nanofillers within the polymer matrix were developed by assembling thin film-coated substrates into a sandwich-like structure. Their piezoelectric properties, such as open-circuit output voltage (V_OC) and short-circuit current (I_SC), were analyzed. As a result, the PENG containing 4 wt% PZT, which was named P-PZT-4, showed the best performance of V_OC of 68.5 V with the d₃₃ value of 78.2 pC/N and β-phase content of 97%. The order of the maximum V_OC values for the PENGs of nanocomposite thin films containing various nanofillers was PZT (68.5 V) > rGO (64.0 V) > ZnO (50.9 V) > TiO₂ (48.1 V). When the best optimum PENG was integrated into a simple circuit comprising rectifiers and a capacitor, it demonstrated an excellent two-dimensional power density of 20.6 μW/cm² and an energy storage capacity of 531.4 μJ within 3 min. This piezoelectric performance of PENG with the optimized nanofiller type and content was found to be superior when it was compared with those in the literature. This PENG comprising nanocomposite thin film with optimized nanofiller type and content shows a potential application for a power source for low-powered electronics such as wearable devices. Full article

Purpose: Water freely diffuses across cell membranes, making it suitable for measuring absolute tissue perfusion. In this study, we introduce an imaging method for conducting coronary artery angiography and quantifying myocardial perfusion across the entire heart using hyperpolarized water. Methods: ¹H was hyperpolarized using dissolution dynamic nuclear polarization (dDNP) with UV-generated radicals. Submillimeter resolution coronary artery images were acquired as 2D projections using a spoiled GRE (SPGRE) sequence gated on diastole. Dynamic perfusion images were obtained with a multi-slice SPGRE with diastole gating, covering the entire heart. Perfusion values were analyzed through histograms, and the most frequent estimated perfusion value (the mode of the distribution), was compared with the average values for ¹⁵O water PET from the literature. Results: A liquid state polarization of 10% at the time of the injection and a 30 s T₁ in D₂O TRIS buffer were measured. Both coronary artery and dynamic perfusion images exhibited good quality. The main and small coronary artery branches were well resolved. The most frequent estimated perfusion value is around 0.6 mL/g/min, which is lower than the average values obtained from the literature for ¹⁵O-water PET (around 1.1 and 1.5 mL/g/min). Conclusions: The study successfully demonstrated the feasibility of achieving high-resolution, motion-free coronary artery angiography and 3D whole-heart quantitative myocardial perfusion using hyperpolarized water. Full article

Before revascularization, moyamoya patients require hemodynamic evaluation. In this study, we evaluated the scoring system Prior Infarcts, Reactivity and Angiography in Moyamoya Disease (PIRAMID). We also devised a new scoring system, MRI-Based Assessment of Risk for Stroke in Moyamoya Angiopathy (MARS-MMA), and compared the scoring systems with respect to the capability to predict impaired [¹⁵O]water PET cerebral perfusion reserve capacity (CPR). We evaluated 69 MRI, 69 DSA and 38 [¹⁵O]water PET data sets. The PIRAMID system was validated by ROC curve analysis with neurological symptomatology as a dependent variable. The components of the MARS-MMA system and their weightings were determined by binary logistic regression analysis. The comparison of PIRAMID and MARS-MMA was performed by ROC curve analysis. The PIRAMID score correlated well with the symptomatology (AUC = 0.784). The MARS-MMA system, including impaired breath-hold-fMRI, the presence of the Ivy sign and arterial wall contrast enhancement, correlated slightly better with CPR impairment than the PIRAMID system (AUC = 0.859 vs. 0.827, Akaike information criterion 140 vs. 146). For simplified clinical use, we determined three MARS-MMA grades without loss of diagnostic performance (AUC = 0.855). The entirely MRI-based MARS-MMA scoring system might be a promising tool to predict the risk of stroke. Full article

Based on the electron-deficient property of picric acid (PA), two neutral Ir(III) complexes 1 and 2 modified with the electron-rich carbazolyl groups were synthesized and characterized. Both 1 and 2 exhibit aggregation-induced phosphorescence emission (AIPE) properties in THF/H₂O. Among them, 2 is extremely sensitive for detecting PA with a limit of detection of 0.15 μM in THF/H₂O. Furthermore, the selectivity for PA is significantly higher compared to other analytes, enabling the efficient detection of PA in four common water samples. The density functional theory calculations and the spectroscopic results confirm that the sensing mechanism is photo-induced electron transfer (PET). Full article

In this study, we investigated the preparation of char and activated carbon (ACs) materials derived from water bottle waste collected from waste collection point in Tunis. The materials were synthesized using a rotary horizontal furnace on a lab/pilot scale and through chemical activation. Characterization of the carbon materials was performed using nitrogen adsorption isotherms at 77K and SEM-EDX analysis. Furthermore, we examined the effectiveness of the ACs in removing the antibiotics 4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzenesulfonamide (sulfamethoxazole-C₁₀H₁₁N₃O₃S) and 5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diamine (trimethoprim) from aqueous solutions. The results revealed a maximum adsorption capacity of 108.17 mg g⁻¹ (85.34%) for sulfamethoxazole and 98.11 mg g⁻¹ (89.73%) for trimethoprim on the PET-KOH-1:1-800 °C sample. Additionally, we analyzed the adsorption kinetics, fitting the data to pseudo-first and -second-order models, and studied the equilibrium isotherms using the Langmuir and Freundlich equation models. These findings suggest significant potential for the application of ACs derived from plastic bottle waste in the treatment of wastewater containing antibiotics. Overall, our study highlights the feasibility of utilizing waste materials for the synthesis of valuable carbon-based adsorbents with promising adsorption capabilities. This research contributes to the ongoing efforts towards sustainable waste management and environmental remediation. Full article

The skeletal muscles account for approximately 40% of the body weight and are crucial in movement, nutrient absorption, and energy metabolism. Muscle loss and decline in function cause a decrease in the quality of life of patients and the elderly, leading to complications that require early diagnosis. Positron emission tomography/computed tomography (PET/CT) offers non-invasive, high-resolution visualization of tissues. It has emerged as a promising alternative to invasive diagnostic methods and is attracting attention as a tool for assessing muscle function and imaging muscle diseases. Effective imaging of muscle function and pathology relies on appropriate radiopharmaceuticals that target key aspects of muscle metabolism, such as glucose uptake, adenosine triphosphate (ATP) production, and the oxidation of fat and carbohydrates. In this review, we describe how [¹⁸F]fluoro-2-deoxy-D-glucose ([¹⁸F]FDG), [¹⁸F]fluorocholine ([¹⁸F]FCH), [¹¹C]acetate, and [¹⁵O]water ([¹⁵O]H₂O) are suitable radiopharmaceuticals for diagnostic imaging of skeletal muscles. Full article

Superhydrophobic coatings have attracted substantial attention owing to their potential application in various industries. Conventional textiles used in daily life are prone to staining with water and household liquids, necessitating the development of water-repellent and stain-resistant coatings. In this study, we fabricated a highly water-repellent superhydrophobic PET fabric by using an eco-friendly water-based coating process. Fluorine-free octadecyltrichlorosilane (OTS) solutions with various wt.% of hollow silica (HS) nanoparticles were used to produce a superhydrophobic surface via a facile dip coating method. Our findings revealed that the incorporation of HS nanoparticles substantially increased the water contact angle, with higher concentrations resulting in enhanced water repellency and increased surface roughness. The treated fabrics had a remarkable water contact angle of 152.4° ± 0.8°, demonstrating their superhydrophobic fiber surface. In addition, the durability of these superhydrophobic properties was investigated via a laundry procedure, which showed that the fabrics maintained their water repellency even after 20 laundering cycles. EDX and XRD analyses confirmed that the morphological evaluations did not reveal any substantial structural alterations. Significantly, the fibers maintained their strength and durability throughout the testing, enduring only minor hollow SiO₂ nanoparticle loss. This eco-friendly and cost-effective method holds great potential for application in apparel and other industries, offering an effective solution to resist water stains and improve performance in various contexts. Full article

Polyethylene terephthalate (PET) water bottles are widely used in the United Arab Emirates (UAE); however, their production and disposal adversely affect the environment. In collaboration with the private sector, the UAE government has taken serious steps to reduce these impacts, including (i) encouraging people to stop using PET water bottles and to separate their waste, (ii) establishing material recovery facilities, (iii) constructing facilities for incineration with energy recovery, and (iv) creating business opportunities to downcycle and recycle PET water bottles. This paper models the PET supply chain (PSC) using system dynamics (SD) to simulate the current PSC in the UAE and to project its possible evolution from 2023 to 2050, taking greenhouse gas (GHG) emissions into consideration. For decision-makers, the SD model shows that PET reductions must equal population growth to maintain GHG emissions associated with the PSC for the coming years. In addition, the separation efficiency must exceed 33% of PET consumption to meet the current demand for used PET. Moreover, if PET consumption decreases by more than 1.5%, then businesses relying on used PET will face a supply shortage in the year 2050. As for environmental impacts, it is found that if downcycling and recycling capabilities are fully utilized, GHG emissions will decrease by 35%. Furthermore, if demand for recycled PET reaches 10,000 tons, this reduction will exceed 47%, reaching $177,861MtC{O}_{2}e$. Full article