Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 82
Filtrar
Más filtros











Intervalo de año de publicación
1.
Chemosphere ; 362: 142805, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38996979

RESUMEN

This study presents the green synthesis and multifunctional properties of Cu/NiO nanocomposites (NCs) fabricated with varying ratios (90:10, 80:20, and 70:30) using Commelina benghalensis leaf extract. X-ray diffraction (XRD) analysis confirmed the polycrystalline nature of the NCs, revealing crystallite sizes of 13.62, 13.22, and 7.14 nm. Scanning electron microscopy (SEM) showed rod-shaped and agglomerated particles with sizes ranging from 17.64 to 22.97 nm. Energy-dispersive X-ray spectroscopy (EDX) verified the elemental composition of copper, nickel, oxygen, and carbon. UV-visible spectroscopy determined the energy band gaps to be in the range of 1.24-1.56 eV. Fourier-transform infrared spectroscopy (FT-IR) indicated the presence of bioactive compounds responsible for the reduction of precursor metal salts. The Cu/NiO NCs exhibited remarkable antimicrobial activity, with the 90:10 ratio showing the highest zones of inhibition at 32.76 ± 0.23 mm, 18.66 ± 0.33 mm, and 14.36 ± 0.32 mm against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli, respectively. Additionally, the 70:30 Cu/NiO NCs demonstrated superior antioxidant activity, with a radical scavenging efficiency of 83.22%, closely approaching that of ascorbic acid (96.98%). Photocatalytic evaluations revealed that the NCs were highly effective in degrading environmental pollutants, achieving 97.69% degradation of malachite green and 96.52% of congo red under UV light irradiation. The novelty of this work lies in the use of Commelina benghalensis leaf extract as a sustainable and eco-friendly reducing and stabilizing agent for synthesizing Cu/NiO NCs, offering a green alternative to conventional methods. The synergistic effects between Cu and NiO in the different compositions (90:10, 80:20, and 70:30) enhanced the overall antimicrobial and photocatalytic activities, highlighting their potential for environmental remediation applications.


Asunto(s)
Cobre , Tecnología Química Verde , Nanocompuestos , Níquel , Extractos Vegetales , Hojas de la Planta , Cobre/química , Nanocompuestos/química , Hojas de la Planta/química , Extractos Vegetales/química , Níquel/química , Bacillus subtilis/efectos de los fármacos , Antibacterianos/farmacología , Antibacterianos/química , Staphylococcus aureus/efectos de los fármacos , Antioxidantes/química , Antioxidantes/farmacología , Difracción de Rayos X , Espectroscopía Infrarroja por Transformada de Fourier
2.
Sci Rep ; 14(1): 17479, 2024 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-39080290

RESUMEN

It is known that Copper's (Cu) electrical conductivity makes it a desirable material for use in industry. Due to poor properties such as hardness, thermal expansion, and corrosion resistance, its applications are limited. This manuscript solves these problems while maintaining no breakdown in electrical conductivity. In this study, high-strength ceramics (SiC nanoparticles and graphene nanosheets) were used as reinforcements in the manufacture of Cu-based hybrid nanocomposites using powder metallurgy technique. X-ray diffraction analysis (XRD) was used to investigate phase composition and crystal size of the milled powders. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM), respectively examined the microstructure of the prepared powder powders and sintered nanocomposites. Then, various properties of the sintered samples are measured, including physical, electrical and thermal properties and wear resistance. The obtained XRD technique and TEM images showed decreases in the crystal and particle size of milled samples reaching up to 14.08 and 28.30 nm, respectively for the sample contained 8 vol. % SiC + 0.8 vol. % graphene (SG8). A surprising improvement in the mechanical properties of up to 809.15, 341.84 MPa and 336.56 GPa for microhardness, strength and longitudinal modulus for the sample containing the highest reinforcements, achieving an improvement of up to 122, 61.37 and 41 percent compared to the Cu matrix. Moreover, there was a noticeable improvement in the coefficient of thermal expansion (CTE) and wear rate values of the samples by increasing the percentages of hybrid reinforcements in the examined sintered nanocomposite samples. The Sample SG8 recorded the lowest value, decreasing by about 50.2 and 76.5% compared to the SG1 sample. Finally, adding reinforcements to the Cu matrix had a negative effect on the relative density and electrical conductivity, and the lowest values was 92.94% and8.59 × 106 S/m, respectively for the SG sample.

3.
Drug Dev Ind Pharm ; 49(12): 723-733, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37906615

RESUMEN

INTRODUCTION: Bacterial infections caused by different strains of bacteria still one of the most important disorders affecting humans worldwide. Polymers nanocomposite systems could be considered as an alternative to conventional antibiotics to eradicate bacterial infections. SIGNIFICANCE: In an attempt to enhance the antibacterial performance of silver and iron oxide nanoparticles, decrease their aggregation and toxicity, a polymeric hybrid nanocomposite system combining both nanoparticles is produced. METHODS: Magnetic Ag-Fe3O4@polymer hybrid nanocomposites prepared using different polymers, namely polyethylene glycol 4000, ethyl cellulose, and chitosan were synthesized via wet impregnation and ball-milling techniques. The produced nanocomposites were tested for their physical properties and antibacterial activities. RESULTS: XRD, FT-IR, VSM, and TEM results confirmed the successful preparation of hybrid nanocomposites. Hybrid nanocomposites have average crystallite sizes in the following order Ag-Fe3O4@CS (8.9 nm) < Ag-Fe3O4@EC (9.0 nm) < Ag-Fe3O4@PEG4000 (9.4 nm) and active surface area of this trend Ag-Fe3O4@CS (130.4 m2g-1) > Ag-Fe3O4@EC (128.9 m2g-1) > Ag-Fe3O4@PEG4000 (123.4 m2g-1). In addition, they have a saturation magnetization in this order: Ag-Fe3O4@PEG4000 (44.82 emu/g) > Ag-Fe3O4@EC (40.14 emu/g) > Ag-Fe3O4@CS (22.90 emu/g). Hybrid nanocomposites have a pronounced antibacterial action against Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus intermedius compared to iron oxide nanoparticles and positive antibacterial drug. In addition, both Ag-Fe3O4@EC and Ag-Fe3O4@CS have a lower MIC values compared to Ag-Fe3O4@PEG and positive control. CONCLUSION: Magnetic Ag-Fe3O4 hybrid nanocomposites could be promising antibacterial nanomaterials and could pave the way for the development of new materials with even more unique properties and applications.


Asunto(s)
Infecciones Bacterianas , Nanopartículas del Metal , Nanocompuestos , Humanos , Polímeros , Espectroscopía Infrarroja por Transformada de Fourier , Antibacterianos/farmacología , Fenómenos Magnéticos
4.
Nanomaterials (Basel) ; 13(17)2023 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-37686935

RESUMEN

This study focuses on epoxy hybrid systems prepared by incorporating multi-wall carbon nanotubes (MWCNTs) and graphene nanosheets (GNs) at two fixed filler amounts: below (0.1 wt%) and above (0.5 wt%), with varying MWCNT:GN mix ratios. The hybrid epoxy systems exhibited remarkable electrical performance, attributed to the π-π bond interactions between the multi-wall carbon nanotubes and the graphene layers dispersed in the epoxy resin matrix. The material's properties were characterized through dynamic mechanical and thermal analyses over a wide range of temperatures. In addition to excellent electrical properties, the formulated hybrid systems demonstrated high mechanical performance and thermal stability. Notably, the glass transition temperature of the samples reached 255 °C, and high storage modulus values at elevated temperatures were observed. The hybrid systems also displayed thermal stability up to 360 °C in air. By comparing the mechanical and electrical performance, the formulation can be optimized in terms of the electrical percolation threshold (EPT), electrical conductivity, thermostability, and mechanical parameters. This research provides valuable insights for designing advanced epoxy-based materials with multifunctional properties.

5.
Biomolecules ; 13(8)2023 07 30.
Artículo en Inglés | MEDLINE | ID: mdl-37627257

RESUMEN

Predicting the mechanical properties of multiscale nanocomposites requires simulations that are costly from a practical viewpoint and time consuming. The use of algorithms for property prediction can reduce the extensive experimental work, saving time and costs. To assess this, ternary poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)-based bionanocomposites reinforced with graphene oxide (GO) and montmorillonite nanoclay were prepared herein via an environmentally friendly electrochemical process followed by solution casting. The aim was to evaluate the effectiveness of different Machine Learning (ML) models, namely Artificial Neural Network (ANN), Decision Tree (DT), and Support Vector Machine (SVM), in predicting their mechanical properties. The algorithms' input data were the Young's modulus, tensile strength, and elongation at break for various concentrations of the nanofillers (GO and nanoclay). The correlation coefficient (R2), mean absolute error (MAE), and mean square error (MSE) were used as statistical indicators to assess the performance of the models. The results demonstrated that ANN and SVM are useful for estimating the Young's modulus and elongation at break, with MSE values in the range of 0.64-1.0% and 0.14-0.28%, respectively. On the other hand, DT was more suitable for predicting the tensile strength, with the indicated error in the range of 0.02-9.11%. This study paves the way for the application of ML models as confident tools for predicting the mechanical properties of polymeric nanocomposites reinforced with different types of nanofiller, with a view to using them in practical applications such as biomedicine.


Asunto(s)
Algoritmos , Polihidroxialcanoatos , Aprendizaje Automático
6.
Wiad Lek ; 76(6): 1347-1358, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37463367

RESUMEN

OBJECTIVE: The aim: To investigate the effect of application sorbent based on ornidazole with nanosilicon in experiment and clinic. PATIENTS AND METHODS: Materials and methods: In order to study the effectiveness of the Ornidasil application sorbent for the treatment of purulent wounds, we conducted an experimental study in rats. Also, we studied the effectiveness of the Ornidasil in the clinic for the treatment of patients with diabetic foot syndrome and to prevent the suppuration of postoperative wounds in patients with purulent peritonitis in toxic and terminal stages. RESULTS: Results: The formation of active substance complexes with hydroxylated matrices is due to hydrogen bonds between the oxygen atom of the silanol group of the silica surface and the hydrogen atom of the alcohol group of the ornidazole molecule. This promotes the gradual release of ornidazole from the surface of such a matrix into the wound exudate. Thus, on day 13, 9 experimental rats of group I healed completely, 11 rats had a small wound surface, complete healing occurred on day 15. We also investigated the effectiveness Ornidasil in the clinic. In the comparison group, postoperative wound suppuration occurred in 6 patients (31.6%), and in the main group - in 3 patients (12.5%). CONCLUSION: Conclusions: A study of the effectiveness Ornidasil in the complex treatment of Diabetic foot syndrome showed that in the experimental groups, wound healing occurred 1.6 -1.9 times faster. The use of polyurethane wound protector in combination with Ornidasil reduced the suppuration of postoperative wounds in patients of the main group by 2.5 times relative to patients in the comparison group.


Asunto(s)
Antiinfecciosos , Pie Diabético , Ornidazol , Ratas , Animales , Pie Diabético/tratamiento farmacológico , Ornidazol/farmacología , Cicatrización de Heridas , Supuración , Síndrome
7.
Int J Mol Sci ; 24(13)2023 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-37446124

RESUMEN

Hybrid nanocomposite materials Bu4NBF4-MgO were obtained using a nanocrystalline MgO with a specific surface area of 324 m2/g and the grains size of 5.1 nm. As a result of the strong adhesion, the salt transforms into an interface-stabilized amorphous state within the thin layer near the interface. The analysis of the DSC data allowed one to estimate the concentration and the thickness of this amorphous layer as 4.8 nm. The amorphous interface phase has an enhanced ionic conductivity. As a result, conductivity of the nanocomposite increases with the concentration of the amorphous phase and reaches 1.1 × 10-3 S/cm at 150 °C at a concentration of the MgO additive x = 0.90 corresponding to the maximum content of the amorphous phase. The conductivity of the nanocomposite is by three orders of magnitude higher than the conductivity of pure Bu4NBF4. The nanocomposites are electrochemically stable up to 2.5 V. At high concentrations of MgO when the total volume of the salt is small the composites become nano- and mesoporous.


Asunto(s)
Óxido de Magnesio , Nanocompuestos , Óxido de Magnesio/química , Nanocompuestos/química , Electrólitos/química , Iones
8.
J Colloid Interface Sci ; 650(Pt B): 1833-1841, 2023 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-37515973

RESUMEN

The combination of chemo- and biocatalysts to perform one-pot synthetic route has presented great challenges for decades. Herein, glutamate oxidase (GLOX) and trimanganese tetraoxide (Mn3O4) nanocrystals were combined for the first time by one-step biomineralization to construct a mimic multi-enzyme system (GLOX@Mn3O4) for chemoenzymatic synthesis of α­ketoglutaric acid (α­KG). Mn3O4 not only served as a support for the enzyme immobilization, but also contributed its catalytic activity to co-operate with natural enzymes for the cascade reactions. The as-synthesized chemo-enzyme catalysts with directly contacted catalytic sites of the enzyme and inorganic catalyst maximizes the substrate channeling effffects for in situ rapid decomposition of the oxidative intermediate, H2O2, during the enzymatic oxidation of sodium glutamate, thus relieving the inhibition of H2O2 accumulation for GLOX. Benefiting from the excellent stability and reusability of GLOX@Mn3O4, a nearly 100% conversion (99.7%) of l-glutamate to α-KG was achieved, over 4.7 times higher than that of the free GLOX system (21.2%). This work provides a feasibility for constructing a high-performance chemo-enzyme catalyst for cascade catalysis, especially for those reactions with toxic intermediates.


Asunto(s)
Biomimética , Ácidos Cetoglutáricos , Peróxido de Hidrógeno/química , Catálisis , Glutamatos
9.
Chemosphere ; 336: 139227, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37327825

RESUMEN

We report on the synthesis of silver oxide/reduced graphene oxide nanocomposites (Ag/rGO NCs) using a hydrothermal technique. This paper presents a simple method for synthesizing Ag/rGO hybrid nanocomposites, which can be used for environmentally treating hazardous organic pollutants. The photocatalytic degradation of model artificial Rhodamine B dye and bisphenol A was assessed under visible light illumination. The crystallinity, binding energy, and surface morphologies of the synthesized samples were determined. The silver oxide loading sample resulted in a decrease in the rGO crystallite size. SEM and TEM images demonstrate strong adhesion of the Ag NPs to the rGO sheets. XPS analysis validated the binding energy and elemental composition of the Ag/rGO hybrid nanocomposites. The objective of the experiment was to enhance the photocatalytic efficiency of rGO in the visible region using Ag nanoparticles. The synthesized nanocomposites in the visible region exhibited good photodegradation percentages of approximately 97.5% and 98.6% after 120 min of irradiation for pure rGO, Ag NPs, and Ag/rGO nanohybrid, respectively. Furthermore, the Ag/rGO nanohybrid maintained their degradation ability for up to three cycles. The synthesized Ag/rGO nanohybrid demonstrated enhanced photocatalytic activity, expanding their potential for environmental remediation. Based on the investigations, Ag/rGO nanohybrid proved to be an effective photocatalyst and holds promise as an ideal material for future applications in preventing water pollution.


Asunto(s)
Nanopartículas del Metal , Nanopartículas del Metal/química , Plata , Luz , Agua
10.
Polymers (Basel) ; 15(6)2023 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-36987179

RESUMEN

This article presents a review on the recent advances in the field of ternary diglycidyl ether of bisphenol A epoxy nanocomposites containing nanoparticles and other modifiers. Particular attention is paid to their mechanical and thermal properties. The properties of epoxy resins were improved by incorporating various single toughening agents, in solid or liquid states. This latter process often resulted in the improvement in some properties at the expense of others. The use of two appropriate modifiers for the preparation of hybrid composites, possibly will show a synergistic effect on the performance properties of the composites. Due to the huge amount of modifiers that were used, the present paper will focus mainly on largely employed nanoclays with modifiers in a liquid and solid state. The former modifier contributes to an increase in the flexibility of the matrix, while the latter modifier is intended to improve other properties of the polymer depending on its structure. Various studies which were carried out on hybrid epoxy nanocomposites confirmed the occurrence of a synergistic effect within the tested performance properties of the epoxy matrix. Nevertheless, there are still ongoing research works using other nanoparticles and other modifiers aiming at enhancing the mechanical and thermal properties of epoxy resins. Despite numerous studies carried out so far to assess the fracture toughness of epoxy hybrid nanocomposites, some problems still remain unresolved. Many research groups are dealing with many aspects of the subject, namely the choice of modifiers and preparation methods, while taking into account the protection of the environment and the use of components from natural resources.

11.
Biosensors (Basel) ; 13(3)2023 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-36979610

RESUMEN

Cancer is one of the major public health issues in the world. It has become the second leading cause of death, with approximately 75% of cancer deaths transpiring in low- or middle-income countries. It causes a heavy global economic cost estimated at more than a trillion dollars per year. The most common cancers are breast, colon, rectum, prostate, and lung cancers. Many of these cancers can be treated effectively and cured if detected at the primary stage. Nowadays, around 50% of cancers are detected at late stages, leading to serious health complications and death. Early diagnosis of cancer diseases substantially increases the efficient treatment and high chances of survival. Biosensors are one of the potential screening methodologies useful in the early screening of cancer biomarkers. This review summarizes the recent findings about novel cancer biomarkers and their advantages over traditional biomarkers, and novel biosensing and diagnostic methods for them; thus, this review may be helpful in the early recognition and monitoring of treatment response of various human cancers.


Asunto(s)
Técnicas Biosensibles , Neoplasias Pulmonares , Masculino , Humanos , Biomarcadores de Tumor , Biomarcadores , Neoplasias Pulmonares/diagnóstico , Técnicas Biosensibles/métodos
12.
Molecules ; 28(4)2023 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-36838591

RESUMEN

The appearance and increasing number of microorganisms resistant to the action of antibiotics is one of the global problems of the 21st century. Already, the duration of therapeutic treatment and mortality from infectious diseases caused by pathogenic microorganisms have increased significantly over the last few decades. Nanoscale inorganic materials (metals and metal oxides) with antimicrobial potential are a promising solution to this problem. Here we discuss possible mechanisms of pathogenic microorganisms' resistance to antibiotics, proposed mechanisms of action of inorganic nanoparticles on bacterial cells, and the possibilities and benefits of their combined use with antibacterial drugs. The prospects of using metal and metal oxide nanoparticles as carriers in targeted delivery systems for antibacterial compositions are also discussed.


Asunto(s)
Antiinfecciosos , Enfermedades Transmisibles , Nanopartículas del Metal , Humanos , Antibacterianos/uso terapéutico , Nanopartículas del Metal/uso terapéutico , Enfermedades Transmisibles/tratamiento farmacológico , Metales , Óxidos
13.
ACS Appl Mater Interfaces ; 15(4): 5744-5759, 2023 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-36651701

RESUMEN

The paper presents a study concerning the role of ferroelectric filler size and clustering in the dielectric properties of 20%BaTiO3-80%PVDF and of 20% (2%Ag-98%BaTiO3)-PVDF hybrid nanocomposites. By finite element calculations, it was shown that using fillers with ε > 103 does not provide a permittivity rise in the composites and the effective dielectric constant tends to saturate to specific values determined by the filler size and agglomeration degree. Irrespective of the ferroelectric filler sizes, the addition of metallic ultrafine nanoparticles (Ag) results in permittivity intensification and the effect is even stronger if the metallic nanoparticles are connected to a higher degree with the ferroelectric particles' surfaces. When using coarse ferroelectric fillers, the probability of clustering is higher, thus favoring the permittivity increase by field concentration in small regions close to the interfaces separating dissimilar materials. The modeling results were validated by an experimental dielectric analysis performed in a series of PVDF-based thick films with the same amount of BaTiO3 fillers or with Ag-BaTiO3 hybrid fillers. Similar trends as predicted by simulations were found experimentally but with slightly higher permittivity values which were assigned to the modifications of the polymer phase composition due to the presence of nanofillers and the local sample inhomogeneity (the presence of clustering, in particular for coarse BaTiO3 grains), which create regions with enhanced local fields.

14.
Environ Res ; 216(Pt 3): 114749, 2023 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-36356667

RESUMEN

Development of hybrid graphitic carbon nitride (GCN) nanocomposite is an emerging research area in wastewater treatment. Herein, hybrid visible light active photocatalyst of silver decorated polymeric graphitic carbon nitride and (Ag-GCN) with cerium oxide (CeO2) nanocomposite was prepared and characterized in detail. The Ag-GCN/CeO2 photocatalyst has successfully prepared by an electrostatic self-assembly approach. The synthesized Ag-GCN/CeO2 NCs photocatalysts are characterized by various physio-chemical techniques. Using the Ag-GCN/CeO2 catalyst, the excellent photodegradation efficiency of Acid yellow-36 (AY-36) and Direct yellow-12 (DY-12) dye solution were achieved 100% within 150 min sun light irradiation. The Ag-GCN/CeO2 rate constant values of 0.048 and 0.046/min has been determined for AY-36 and DR-12 dyes, respectively. The extraordinary photocatalytic activity is due to incorporation of CeO2 with Ag-GCN which play a significant role in visible light absorption, superior reactive oxygen generation (ROS) and excellent pollutant catalyst interaction. The toxicity of the photocatalytically degraded AY-36 and DR-12 dyes were measured using the soil nematode Caenorhabditis elegans, a well-established in vivo model in biology, by analyzing survival, physiological functions, intracellular ROS levels, and stress-protective gene expressions.


Asunto(s)
Nanocompuestos , Plata , Plata/toxicidad , Plata/química , Especies Reactivas de Oxígeno , Nanocompuestos/toxicidad , Nanocompuestos/química , Luz , Colorantes/química
15.
Environ Sci Pollut Res Int ; 30(15): 42575-42586, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-35233667

RESUMEN

In the present study, we hypothesized that novel nanocomposites of chitosan-coated cerium oxide (CS/CeO2 NCs) derived from aqueous extracts of tea polyphenols would be stabilized and reduced by using green chemistry. The UV-visible spectrum of the synthesized material revealed an SPR peak at 279 nm, and the morphological characteristics of nanoparticles (NPs) as a uniformly distributed spherical shape with a size range of 20 nm were confirmed by field emission scanning electron microscopy (FESEM). The Fourier transform infrared spectroscopy (FTIR) spectrum illustrated the amino groups of chitosan-coated with CeO2 NPs on the surface. While, the hydrodynamic size (376 nm) and surface charge (+ 25.0 mV) of particles were assessed by dynamic light scattering (DLS), and the existence of oxidation state elements Ce 3d, O 1 s, and C 1 s was identified by employing X-ray photoelectron spectroscopy (XPS). A cubic fluorite polycrystalline structure with a crystallite size of (5.24 nm) NPs was determined using an X-ray Diffractometer (XRD). The developed CS/CeO2 NCs demonstrated excellent antibacterial and antifungal efficacy against foodborne pathogens such as Escherichia coli, Staphylococcus aureus, and Botrytis cinerea with zone of inhibition of 13.5 ± 0.2 and 11.7 ± 0.2 mm, respectively. The results elucidated the potential of biosynthesized CS/CeO2 NCs could be utilized as potent antimicrobial agents in the food and agriculture industries.


Asunto(s)
Antiinfecciosos , Cerio , Quitosano , Nanopartículas del Metal , Nanocompuestos , Polifenoles , Quitosano/química , Antiinfecciosos/química , Antibacterianos/química , Cerio/química , Nanocompuestos/química , , Espectroscopía Infrarroja por Transformada de Fourier , Nanopartículas del Metal/química
16.
Polymers (Basel) ; 16(1)2023 Dec 30.
Artículo en Inglés | MEDLINE | ID: mdl-38201796

RESUMEN

The incorporation of rare earth oxides and nano-silica has been found to significantly enhance the mechanical and tribological characteristics of phenolic-based hybrid nanocomposites. In this work, the impact of these additives was investigated through single-factor experiments. The study revealed that cerium oxide and yttrium oxide were the primary factors influencing changes in the impact strength, shear strength, coefficient of friction, and wear rate. Additionally, the content of nano-silica exerted the most substantial influence on the hardness and compressive strength of the specimens. Furthermore, the material ratios of the phenolic-based hybrid nanocomposites were optimized using an orthogonal experimental design and a fuzzy comprehensive evaluation method. The optimal material ratio for these nanocomposites was determined to be 2% cerium oxide, 2.5% yttrium oxide, and 3% nano-silica, based on their mechanical, frictional, and wear properties. This research provides valuable insights for the development of new brake friction materials with low friction and high wear resistance and contributes to meeting the demand for polymer composites with superior mechanical performance in diverse applications.

17.
Polymers (Basel) ; 15(23)2023 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-38231902

RESUMEN

Diabetic foot ulcers (DFUs) are considered one of the most severe chronic complications of diabetes and can lead to amputation in severe cases. In addition, bacterial infections in diabetic chronic wounds aggravate this scenario by threatening human health. Wound dressings made of polymer matrices with embedded metal nanoparticles can inhibit microorganism growth and promote wound healing, although the current clinical treatments for diabetic chronic wounds remain unsatisfactory. In this view, this research reports the synthesis and characterization of innovative hybrid hydrogels made of carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) chemically crosslinked by citric acid (CA) functionalized with silver nanoparticles (AgNPs) generated in situ using an eco-friendly aqueous process. The results assessed through comprehensive in vitro and in vivo assays demonstrated that these hybrid polymer hydrogels functionalized with AgNPs possess physicochemical properties, cytocompatibility, hemocompatibility, bioadhesion, antibacterial activity, and biocompatibility suitable for wound dressings to support chronic wound healing process as well as preventing and treating bacterial infections. Hence, it can be envisioned that, with further research and development, these polymer-based hybrid nanoplatforms hold great potential as an important tool for creating a new generation of smart dressings for treating chronic diabetic wounds and opportunistic bacterial infections.

18.
Polymers (Basel) ; 14(22)2022 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-36432944

RESUMEN

Polymer matrix nanocomposites are widely studied because of the versatility of their physical and mechanical properties. When these properties are present simultaneously, responding at relative stimuli, multifunctional performance is achieved. In this study, hybrid nanocomposites of SrFe12O19 and BaTiO3 ceramic particles dispersed in an epoxy resin matrix were fabricated and characterized. The content of SrFe12O19 was varying, while the amount of BaTiO3 was kept constant. The successful fabrication of the nanocomposites and the fine dispersion of the ceramic particles was verified via the morphological and structural characterization carried out with X-ray Diffraction patterns and Scanning Electron Microscopy images. Dielectric response and related relaxation phenomena were studied by means of Broadband Dielectric Spectroscopy. Dielectric permittivity augments with filler content, while the recorded relaxations, with descending relaxation time, are: (i) interfacial polarization, (ii) glass-to-rubber transition, (iii) intermediate dipolar effect, and (iv) re-orientation of polar-side groups of the main polymer chain. SrFe12O19 nanoparticles induce magnetic properties to the nanocomposites, which alter with the magnetic filler content. Static and dynamic mechanical response improves with filler content. Thermogravimetric analysis shown that ceramic particles are beneficial to the nanocomposites' thermal stability. Glass transition temperature, determined via Differential Scanning Calorimetry, was found to slightly vary with filler content, in accordance with the results from dynamic mechanical and dielectric analysis, indicating the effect of interactions occurring between the constituents. Examined systems are suitable for energy storing/retrieving.

19.
Polymers (Basel) ; 14(17)2022 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-36080519

RESUMEN

Cross-linked polyethylene (XLPE) is one of the most popular insulation materials used in the production of medium and high voltage cables (MV, HV). This article presents the results of research carried out on two types of commercially used insulation materials, modified with the addition of organophilic phyllosilicate (CLOISITE C20A)and halloysite nanotubes (HNTs). The influence of fillers on the mechanical properties of insulating materials is discussed as a potential mechanism for increasing their resistance to the phenomenon of water-tree. SEM and XRD analyses were performed to investigate the morphology and DSC for comparing phase transitions. Mechanical and functional properties for different concentrations of nanofillers, such as their hybrids, were also investigated.

20.
Polymers (Basel) ; 14(18)2022 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-36145926

RESUMEN

In this work, we report the obtaining of new hybrid nanocomposites with catalytic activity formed by nanofibers of polymer blends and gold nanoparticles. The nanofibers were obtained by electrospinning blends of a poly (ionic liquid) (PIL) and its precursor polymer, poly (4-vinyl pyridine) (P4VPy). The characteristics of the nanofibers obtained proved to be dependent on the proportion of polymer in the blends. The nanofibers obtained were used to synthesize, in situ, gold nanoparticles on their surface by two-step procedure. Firstly, the adsorption of precursor ions on the nanofibers and then their reduction with sodium borohydride to generate gold nanoparticles. The results indicated a significant improvement in the performance of PIL-containing nanofibers over pure P4VPy NFs during ion adsorption, reaching a 20% increase in the amount of adsorbed ions and a 6-fold increase in the respective adsorption constant. The catalytic performance of the obtained hybrid systems in the reduction reaction of 4-nitrophenol to 4-aminophenol was studied. Higher catalytic conversions were obtained using the hybrid nanofibers containing PIL and gold nanoparticles achieving a maximum conversion rate of 98%. Remarkably, the highest value of kinetic constant was obtained for the nanofibers with the highest PIL content.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA