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1.
Int J Biol Macromol ; 265(Pt 1): 130757, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38462107

RESUMO

In this study, an easy and low-cost production method for a cellulose acetate-based gel polymer containing lithium perchlorate and propylene carbonate is described, as well as the investigation of its properties for potential use as an electrolyte in electrochemical devices. Cellulose acetate, a biopolymer derived from natural matrix, is colourless and transparent, as confirmed by the UV-Vis spectroscopy, with 85 % transparency in visible spectrum. The gels were prepared and tested at different concentrations and proportions to optimise their properties. Thermogravimetry, XRD, and FTIR analyses revealed crucial characteristics, including a substantial 90 % mass loss between 150 and 250 °C, a semi-crystalline nature with complete salt dissociation within the polymer matrix, and a decrease in intensity at 1780 cm-1 with increasing Li+ ion concentration, suggesting an improvement in ionic conduction capacity. In terms of electrochemical performance, the gel containing 10 % by mass of cellulose acetate and 1.4 M of LiClO4 emerged as the most promising. It exhibited a conductivity of 2.3 × 10-4 S.cm-1 at 25 °C and 3.0 × 10-4 S.cm-1 at 80 °C. Additionally, it demonstrated an ideal shape of cyclic voltammetry curves and stability after 400 cycles, establishing its suitability as an electrolyte in electrochemical devices.


Assuntos
Celulose/análogos & derivados , Eletrólitos , Polímeros , Condutividade Elétrica
2.
Polymers (Basel) ; 15(22)2023 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-38006106

RESUMO

The radiological protection has the purpose of safeguarding the physical well-being of the user, preventing exposure to detrimental levels of ionizing radiation. This study introduces a novel, cost-effective category of lead-free elastomeric material designed for radiation shielding. The filler compounds utilized are notably lighter than conventional lead-based materials, enhancing user ergonomics during application. They comprise of a blend of barium sulfate combined or not with magnesium oxide with addition-cure liquid silicone rubber. To ensure the effectiveness of the radiation shielding, X-ray transmission measurements were performed for the different thicknesses of the materials and the results compared with Monte Carlo simulations. Additionally, the physical properties of the new materials, such as density, homogeneity, tensile strength, viscosity, and wettability, were also evaluated. The findings indicate that both materials fulfill the requirement for application in radiation protection garments.

3.
Nanoscale ; 14(6): 2266-2276, 2022 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-35080562

RESUMO

The fabrication of a flexible supercapacitor with state-of-the-art performance is described, based on a facile and low-cost fabrication method that encompasses aligned carbon nanotube arrays (ACNTA)-polyaniline/polydimethylsiloxane electrodes (ACNTA-PANI/PDMS). The ACNTA were partially embedded in PDMS to ensure excellent adhesion and integration whilst PANI was electrodeposited on its surface to improve energy storage properties. The supercapacitor structure and morphology were investigated by Raman spectroscopy and scanning electron microscopy (SEM), respectively. The energy storage properties of the electrodes were evaluated in two and three-electrode configurations. The maximum value of specific capacitance was 408 mF cm-2 (265 F g-1) at 1 mA cm-2, and a high energy density of 20 µW h cm-2 (25.5 W h kg-1) was achieved at a power density of 100 µW cm-2 (126.6 W kg-1) for a symmetric two-electrode device. The device showed a good capacitance retention of 76% after 5000 cycles and was able to maintain 80% of its electrochemical properties while being measured at different bending angles, demonstrating excellent mechanical agility performance under extreme conditions and some of the highest carbon-based energy storage properties.

4.
J Biomed Mater Res B Appl Biomater ; 108(4): 1559-1567, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31617960

RESUMO

Tissue engineering aims to regenerate and restore damaged human organs and tissues using scaffolds that can mimic the native tissues. The requirement for modern and efficient biomaterials that are capable of accelerating the healing process has been considerably increased. In this work, a novel electrospun poly(lactic acid) (PLA) nanoporous membrane incorporated with niobium pentoxide nanoparticles (Nb2 O5 ) for biomaterial applications was developed. Nb2 O5 nanoparticles were obtained by microwave-assisted hydrothermal synthesis, and different concentrations (0, 1, 3, and 5% wt/wt) were tested. Chemical, morphological, mechanical, and biological properties of membranes were evaluated. Cell viability results demonstrated that the membranes presented nontoxic effects. The incorporation of Nb2 O5 improved cell proliferation without impairing the wettability, porosity, and mechanical properties of membranes. Membranes containing Nb2 O5 nanoparticles presented biocompatible properties with suitable porosity, which facilitated cell attachment and proliferation while allowing diffusion of oxygen and nutrients. This study has demonstrated that Nb2 O5 nanoparticle-loaded electrospun PLA nanoporous membranes are potential candidates for drug delivery and wound dressing applications.


Assuntos
Teste de Materiais , Membranas Artificiais , Nanopartículas/química , Nióbio/química , Óxidos/química , Poliésteres/química , Tecidos Suporte/química , Animais , Camundongos , Células NIH 3T3 , Porosidade
5.
ACS Omega ; 5(51): 33007-33016, 2020 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-33403262

RESUMO

The development of efficient advanced functional materials is highly dependent on properties such as morphology, crystallinity, and surface functionality. In this work, hierarchical flowerlike nanostructures of SrTiO3 have been synthesized by a simple template-free solvothermal method involving poly(vinylpyrrolidone) (PVP). Molecular dynamics simulations supported by structural characterization have shown that PVP preferentially adsorbs on {110} facets, thereby promoting the {100} facet growth. This interaction results in the formation of hierarchical flowerlike nanostructures with assembled nanosheets. The petal morphology is strongly dependent on the presence of PVP, and the piling up of nanosheets, leading to nanocubes, is observed when PVP is removed at high temperatures. This work contributes to a better understanding of how to control the morphological properties of SrTiO3, which is fundamental to the synthesis of perovskite-type materials with tailored properties.

6.
Data Brief ; 18: 150-155, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29896504

RESUMO

These data and analyses support the research article "Production of cellulose nanoparticles from blue agave waste treated with environmentally friendly processes" Robles et al. [1]. The data and analyses presented here include fitted curves for selected carbons of the 13C CP-MAS NMR analysis; SEM images of the raw and bleached fibers, graphics with chemical composition and visual images of the fibers throughout the process.

7.
Carbohydr Polym ; 183: 294-302, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-29352888

RESUMO

Tequila elaboration leaves two main byproducts that are undervalued (bagasse and leaves). Organosolv pulping and Total Chlorine Free bleaching were integrated to obtain cellulose fibers from agricultural waste which consisted of blue agave bagasse and leaf fibers; together they represent a green process which valorizes biomass waste. The obtained celluloses were characterized by FT-IR, colorimetry, and SEM and their extraction yields were evaluated. These celluloses were used to produce cellulose nanocrystals and cellulose nanofibers. First, an acid hydrolysis was performed in a sonication bath to induce cavitation during the reaction to produce cellulose nanocrystals. Then a high-pressure homogenization was selected to produce cellulose nanofibers. These nanocelluloses were characterized by powder XRD, Nanosizer, zeta potential, NMR, and electronic microscopy. Results showed that cellulose from organosolv pulps bleached with TCF bleaching is suitable for nanocellulose production. Moreover, the use of a new step to separate cellulose nanocrystals resulted in yields almost doubling traditional yields, while the rest of the properties remained within the expected.

8.
Calcif Tissue Int ; 101(4): 341-354, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28612084

RESUMO

The aim of this study was to evaluate the morphological bone response in animal experiments by applying hydroxyapatite grafts in critical and non-critical size bone defects. Current report followed the guidelines established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Animal experiments were selected by assessing repair of bone defects with hydroxyapatite as bone graft and with blood clot only as control. Eight articles were identified in specialized literature and included in the meta-analysis. Statistical analysis was carried out with a random-effect model (p = 0.05). Subgroup analyses were further performed to investigate bone repair in critical and non-critical bone defects. Comprehensive analysis of bone repair outcome showed a statistically significant difference between hydroxyapatite and blood clot control (p < 0.05). Subgroup analyses showed statistically significant difference for critical bone defects (p < 0.05). No statistically significant difference was reported in non-critical bone defects (p > 0.05). Although animal studies revealed a high risk of bias and results should be interpreted with caution, the literature suggests that non-critical bone defects may heal spontaneously and without the need of a bone graft. Conversely, when critical-size defects are present, the use of hydroxyapatite bone graft improves the bone repair process.


Assuntos
Substitutos Ósseos , Transplante Ósseo/métodos , Durapatita , Animais
9.
Materials (Basel) ; 9(12)2016 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-28774122

RESUMO

In this work, cellulose nanocrystals (CNCs) were obtained from flax fibers by an acid hydrolysis assisted by sonochemistry in order to reduce reaction times. The cavitation inducted during hydrolysis resulted in CNC with uniform shapes, and thus further pretreatments into the cellulose are not required. The obtained CNC exhibited a homogeneous morphology and high crystallinity, as well as typical values for surface charge. Additionally, CNC membranes were developed from CNC solution to evaluation as a drug delivery system by the incorporation of a model drug. The drug delivery studies were carried out using chlorhexidine (CHX) as a drug and the antimicrobial efficiency of the CNC membrane loaded with CHX was examined against Gram-positive bacteria Staphylococcus aureus (S. Aureus). The release of CHX from the CNC membranes is determined by UV-Vis. The obtaining methodology of the membranes proved to be simple, and these early studies showed a potential use in antibiotic drug delivery systems due to the release kinetics and the satisfactory antimicrobial activity.

10.
J Cosmet Sci ; 54(6): 527-35, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-14730369

RESUMO

Hair hydration is one of the effects that consumers most expect when using a cosmetic hair product. The purpose of this study was to combine differential scanning calorimetry (DSC) and gas chromatography (GC) techniques for a precise evaluation of the water content in hair fiber. DSC allowed determination of the bonding strength of water to hair fibers by quantifying the amount of energy required to remove the water. The amount of water thus removed was determined by GC. Post-treatment sensory evaluations of hair tresses were conducted to determine whether the values obtained with these techniques correspond to the moisturizing sensation perceived by consumers.


Assuntos
Varredura Diferencial de Calorimetria/métodos , Cromatografia Gasosa/métodos , Cabelo/química , Água/química , Humanos , Termodinâmica
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