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1.
Polymers (Basel) ; 13(4)2021 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-33557420

RESUMO

In this work, we report the synthesis of graphene oxide (GO) nanohybrids with starch, fructose, and micro-cellulose molecules by sonication in an aqueous medium at 90 °C and a short reaction time (30 min). The final product was washed with solvents to extract the nanohybrids and separate them from the organic molecules not grafted onto the GO surface. Nanohybrids were chemically characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy and analyzed by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray diffraction (XRD). These results indicate that the ultrasound energy promoted a chemical reaction between GO and the organic molecules in a short time (30 min). The chemical characterization of these nanohybrids confirms their covalent bond, obtaining a grafting percentage above 40% the weight in these nanohybrids. This hybridization creates nanometric and millimetric nanohybrid particles. In addition, the grafted organic molecules can be crystallized on GO films. Interference in the ultrasound waves of starch hybrids is due to the increase in viscosity, leading to a partial hybridization of GO with starch.

2.
Carbohydr Polym ; 255: 117349, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33436191

RESUMO

Normal and high amylose corn starches were modified using HMDSO plasma at different time treatments. Changes in functional properties of starch granule, film-forming solutions (FFS) and films were investigated. SEM analysis revealed HMDSO coating deposition on the granule surface, which limited the amylopectin leach out from the granules to the continuous matrix, affecting the rheological properties of the FFS. The amylopectin restriction resulted in a low reinforcement of the network decreasing the viscosity as indicated by n and k values. Also, a gel-like behavior (G' > G″) was observed when the amylose and time treatment increased, suggesting that the matrix becomes less elastic with softer entanglement. This behavior was confirmed by creep test and Burger model parameters. The plasma treatments allowed obtaining FFS with low viscosity, suitable for developing soft and hydrophobic films with low flexibility, as indicated by the decrease of the maximum stress, Hencky strain and permeance values.

3.
Sensors (Basel) ; 20(23)2020 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-33256037

RESUMO

Industry 4.0 and the Internet of Things have significantly increased the use of sensors and electronic products based on flexible substrates, which require electrical energy for their performance. This electrical energy can be supplied by piezoelectric vibrational energy harvesting (pVEH) devices. These devices can convert energy from ambient mechanical excitations into electrical energy. In order to develop, these devices require piezoelectric films fabricated with a simple and low-cost process. In this work, we synthesize ZnO nanorod film by a solvothermal method and deposit by spraying on ITO (indium-tin-oxide)/PET (polyethylene terephthalate) flexible substrate for a pVEH microdevice. The results of the characterization of the ZnO nanorod film using X-ray diffraction (XRD) confirm the typical reflections for this type of nanomaterial (JCPDS 36-145). Based on transmission electron microscopy (TEM) images, the size of the nanorod film is close to 1380 nm, and the average diameter is 221 ± 67 nm. In addition, the morphological characteristics of the ZnO nanorod film are obtained using atomic force microscopy (AFM) tapping images. The pVEH microdevice has a resonant frequency of 37 Hz, a generated voltage and electrical power of 9.12 V and 6.67 µW, respectively, considering a load resistance of 107.7 kΩ and acceleration of 1.5 g. The ZnO nanorod film may be applied to pVEH microdevices with flexible substrates using a low-cost and easy fabrication process.

4.
Int J Biol Macromol ; 135: 196-202, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31121235

RESUMO

In this study, surface, chemical, physicochemical and barrier properties of films treated with hexamethyldisiloxane (HMDSO) cold plasma were investigated. Normal and high amylose starches were gelatinized at different level to obtain films with different amount of free amylopectin. The obtained films were subjected to HMDSO plasma treatment. XPS analysis indicated chemical changes including substitution and crosslinking of the starch molecule, as reflected by the CSi bond increasing and the C-OH bonds reduction on treated films. These changes modified the thermal transitions (Tm and ΔH). The highest amount of CSi bonds was more noticeable in the TF50 film, suggesting a better interaction between active species of plasma and the free amylopectin released into the continuous phase of the film. Moreover, active species of plasma increased the crystallinity in all films. These results suggested that a higher helical packaging, crosslinking and hydrophobic blocking groups (CSi) of starch molecules resulted in films with improved barrier performance against water molecules.


Assuntos
Gelatina/química , Gases em Plasma/química , Amido/química , Vapor , Amilopectina/química , Varredura Diferencial de Calorimetria , Gelatina/ultraestrutura , Microscopia de Força Atômica , Permeabilidade , Análise Espectral
5.
Int J Biol Macromol ; 124: 651-658, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30476514

RESUMO

In this study, the effect of amylose content and cold plasma treatment on starch films properties was investigated. Films from normal (30%) and high amylose (50 and 70%) starches were subjected to hexamethyldisiloxane (HMDSO) cold plasma treatment. Morphological, structural, mechanical and barrier properties of the films were evaluated. The amount of remnant starch granules (RSG) in the films depended on the amylose content and on the gelatinization extent of the starch. This behavior was corroborated on the films from starch with 50% amylose, where the loss of RSG resulted in poor barrier properties and high hydrophilicity. Moreover, HMDSO cold plasma treatment incorporated methyl groups improving the hydrophobic properties and favored the helix ordering of the starch components resulting in a limited water-film interaction. Furthermore, the simultaneous effect of HMDSO coating and the ordering of the structures reinforced the surface of the films, improving the mechanical properties.


Assuntos
Amilose/química , Gases em Plasma/química , Siloxanas/química , Amido/química , Gases em Plasma/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Amido/ultraestrutura , Resistência à Tração , Difração de Raios X
6.
Rev. cuba. cir ; 49(2)abr.-jun. 2010.
Artigo em Espanhol | LILACS, CUMED | ID: lil-584306

RESUMO

El secuestro pulmonar es una afección congénita que consiste en la presencia de una masa quística de tejido pulmonar afuncional que puede carecer de una obvia comunicación con el árbol traqueobronquial y recibe toda o la mayor parte de su irrigación sanguínea de vasos anómalos provenientes de la circulación sistémica. Teniendo en cuenta que la presentación de esta afección resulta rara comparada con otras afecciones pulmonares (entre 1 y 2 por ciento de todas las resecciones pulmonares) y que además lo más frecuente resulta su tratamiento definitivo antes de la edad adulta, se presenta el caso de un hombre de 44 años que acudió a consulta por presentar episodios frecuentes de neumonías desde hacía más de 10 años, que fueron diagnosticados como bronquiectasias. Se discuten los hechos más significativos del origen embriológico de esta afección, características anatomopatológicas, clasificación, diagnóstico imaginológico, detalles del tratamiento quirúrgico y evolución posoperatoria(AU)


Pulmonary sequestration is a congenital affection consisting in the presence of a cystic mass of no-functional pulmonary tissue without an obvious communication with tracheobronchial tree and that receives all or most of its bloodstream of the anomalous vessels from systemic circulation. Taking into account that presentation of this affection is rare compared to other pulmonary affections (between the 1 percent and the 2 percent of all pulmonary resections) and that also the more usual is its definitive treatment before adulthood. The case of man aged 44 is presented coming to consultation due to frequent episodes of pneumonias from more 10 years ago diagnosed as a bronchiectasis. The more significant facts of embryology origin of this affection including: anatomical and pathological features, imaging diagnosis, surgical treatment details, and postoperative course(AU)


Assuntos
Humanos , Masculino , Adulto , Sequestro Broncopulmonar/diagnóstico por imagem , Pneumonectomia/métodos , Pulmão/anormalidades , Sequestro Broncopulmonar/cirurgia
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