1,721,067 research outputs found
Controlled Release and Antibacterial Properties of Quercetin-Loaded Silica Hybrids for Drug Delivery
No full textNatural products from plants are valuable alternatives to synthetic drugs for treating cancers and bacterial infections. However, their low solubility and absorption pose challenges, necessitating a biocompatible system for controlled release at the target site. Hybrid materials, such as silica (SiO2) encapsulating quercetin (Qu), offer a solution by protecting the organic compound and maintaining its anticancer and antibacterial properties. Two synthesis methods for quercetin-encapsulated silica were explored: one with an acid catalyst (SiO2-HNO3+Qu5%) and one without a catalyst (SiO2+Qu5%), aiming for an eco-friendly approach. The encapsulation efficiency of the silica matrix was analyzed, and release studies were carried out using UV–visible spectroscopy under physiological (pH = 7.4) and cancer (pH = 5.0) conditions. The release of quercetin was found to be pH-dependent, with the SiO2+Qu5% system demonstrating superior release capacity. However, the system synthesized with the acid catalyst exhibited better antibacterial activity, likely due to the release of nitrate ions. The study highlights the potential of these hybrid materials in drug delivery applications, balancing efficient quercetin release, and enhanced antibacterial effects
Effect of Water Sorption on the Mechanical Properties of a CNT-Based Epoxy Resin
No full textThis study aims to assess the impact of water absorption on the mechanical properties of CNTs-composite using dynamic mechanical analysis (DMA). Water absorption results in a decrease in mechanical properties, such as storage modulus and Tan δ, due to swelling and plasticization effects. Specifically, the presence of water in the matrix causes the Tan δ peak to broaden. Following an approach that considers the Tan δ peak as comprising multiple relaxation mechanisms activated at different temperatures, an average glass transition temperature reduction of 20 °C was observed, along with a decrease in “network homogeneity” from 0.95 to 0.62 as water absorption increased
Thermal investigation of tetrafunctional epoxy resin filled with different carbonaceous nanostructures
No full textArticle a food-grade resin with ldh–salicylate to extend mozzarella cheese shelf life
No full textMozzarella cheese can be considered by far the world’s most popular Italian dairy product. Extending the shelf life of mozzarella cheese is an important issue in the dairy industry due to the high risk of contamination by several bacteria species, including spoilage pseudomonads. In this work, active packaging was prepared by coating traditional polyethylene terephthalate (PET) containers of “ovoline” mozzarella cheese with a food-grade resin mixed with a layered double hydroxide (LDH) in which salicylate anion was intercalatedby ionic exchange.. This antimicrobial molecule is listed in EC-Directive 10/2011/EC of 14 January 2011. Morphological arrangement of the molecule into the LDH layers was evaluated by X-ray diffraction (XRD) and controlled release followed by UV spectroscopy. Then, active trays were used to pack the mozzarella cheeses stored for 20 days at 4◦ C and under thermal abuse (15◦ C). Samples from both conditions showed coliform reduction (by ca. 2 log CFU/g) throughout the storage period. Depending on temperature, total mesophilic aerobic bacteria, Pseudomonas spp., yeasts, and mold loads were reduced in the first 3 days; at 4◦ C. Slower acidification and lower proteolysis were also found in treated samples in comparison to control ones. The fitting of the Gompertz function to coliforms and spoilage pseudomonads highlighted an increase in the shelf life of mozzarella cheese of ca. 2 days at 4◦ C. These results suggest that salicylate–LDH-coated PET may be applied to extend the shelf-life of mozzarella cheese and also counteract its spoilage if accidental interruptions to refrigeration occur
Design of multifunctional composites: New strategy to save energy and improve mechanical performance
No full textIn this paper, an alternative curing strategy, based on the application of an electric field, is proposed to harden nano-filled multifunctional resins. The resin is obtained through the dispersion of carbon nanotubes, which act as nanometric heater elements in the epoxy matrix. The electro-curing is activated by applying an external electric voltage, which allows tunable cross-linking within the epoxy matrix entrapped between the nanotubes. The electro-curing method allows reaching higher curing degrees with respect to the conventional ones and, consequently, higher glass transition temperatures. This is a direct consequence of the fact that the curing reactions start directly in the regions at the interphase between carbon nanotubes, acting as heater nano-filaments, and the polymeric matrix. The proposed method is able to give composites better properties, making the curing process fast and energy-saving
Experimental evaluation and modeling of thermal conductivity of tetrafunctional epoxy resin containing different carbon nanostructures
No full textElectrical Behavior of Nanocomposites Exposed to Water Sorption
No full textThe present study examines the electrical response of nanocomposites to water uptake. Specifically, an electrical signal was employed to detect the amount of water absorbed in a carbon nanotube-based epoxy composite. The investigation focused on changes in the electrical resistance of the composite with a filler content (0.1% by weight) near the electrical percolation threshold. Water penetration results in “non-Fickian” diffusion behavior due to the composite's viscoelastic nature and plasticization effects. The variation in time of the resistance change ratio, similar to that of water absorption, allows associating the electrical resistance measurement for the amount of the absorbed water by the use of a sensitivity factor
Evaluation of zein/halloysite nano-containers as reservoirs of active molecules for packaging applications: Preparation and analysis of physical properties
No full textDamping assessment of new multifunctional epoxy resin for aerospace structures
No full textThe increasing demand for more advanced materials, particularly in the aerospace field, has led to the development of carbon-fiber-reinforced composite manufactured employing different kinds of nanoparticles. The reinforcement with Carbon Nanotubes (CNTs) allows the modulation of several characteristics of the composite, which becomes suitable for more extreme operating conditions. Furthermore, the incorporation of CNTs in polymeric matrices of composite materials allows them to be electrically conductive, and hence suitable for developing self-responsive/self-protective materials characterized by a combination of properties strongly requested for replacing the traditional composites. In addition, detection of specific electrical properties can be used to develop self health-monitor composites subjected to damages due to static and dynamic loads. For instance, damage detection through conductivity measurements offers many advantages when compared to traditional glass fiber optic sensors. In fact, because of their high cost, it is not possible to create a dense network of these fibers to inspect large parts of the composite and especially if the damage spreads in the material without crossing the fiber. Therefore, the use of carbon nanotubes may provide an effective solution to overcome the described limitation. As part of an intensive research activity aimed at studying the performance of innovative smart resins, in this article, the authors show the outcomes related to some of the dynamic properties of the developed resins. Relevant results related to the enhancement of dissipative phenomena have been found in formulation modified with elastomeric phase e CNTs
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