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Electric,magnetic and microstructural features of the La_(2)CofeO_(6) lanthanide ferrocobaltite obtained by the modified Pechini route

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Journal of Advanced Dielectrics 2021年第3期11卷 16-25页

作者： J.A.Jaramillo Palacio K.A.Munoz Pulido J.Arbey Rodríguez D.A.Landínez Téllez J.Roa-Rojas grupo de física de nuevos materiales Departamento de Física Universidad Nacional de ColombiaBogotáDCColombia Laboratório de Magnetismo e Materiais Magnéticos departamento de física Universidade Federal de Santa Maria Rio Grande do Sul Brazil grupo de Estudios de materiales Departamento de Física Universidad Nacional de ColombiaBogotáDCColombia

In the search for new materials with applicable magnetic properties in spintronic devices,the aim of this work is to report the synthesis of the lanthanide ferrocobaltite La_(2)CofeO_(6) using the modified Pechini route;the experimental study of structural,morphological and magnetic properties,and the analysis of the electronic structure and bands are obtained in the framework of the density functional *** refinement of experimental X-ray diffraction patterns revealed the crystallization of this oxide material in a perovskite-like monoclinic structure,space group P2_(1)/n(#14).Scanning electron microscopy and atomic force microscopy images revealed that the surface morphology is essentially polycrystalline,with mean grain sizes between 177 and 188 *** dispersive X-ray spectroscopy suggests that the material obtained contains La,fe,Co and O in the stoichiometric proportions expected by up to 98%.The magnetic susceptibility curves as a function of temperature indicated that the material is ordered ferromagnetically,showing strong irreversibility effects due to the disorder of the fe and Co cations in the three crystallographic directions of the structure and to the strong distortions in the feO_(6) and CoO_(6) *** hysteresis curves confirmed the ferromagnetic character of the material for all temperatures evaluated,up to room temperature.I-V response curves revealed a semiconductor-like behavior with a figure of merit exponent 1.53 of the varistor *** ferromagnetic semiconductor behavior suggests the potential applicability of the material in spintronic technological devices.

关键词： Double perovskite Pechini method crystalline structure ferromagnetic response semiconductor behavior

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design of multilayer hybrid sol-gel coatings with bifunctional barrier-bioactive response on the Elektron 21 magnesium alloy for biomedical applications

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Journal of Magnesium and Alloys 2021年第6期9卷 2097-2112页

作者： K.S.Durán N.Hernández L.M.Rueda C.A.Hernández-Barrios A.E.Coy f.Viejo grupo de Investigación en desarrollo y Tecnología de nuevos materiales(GIMAT) Universidad Industrial de Santander9 Cra.27Colombia grupo de Investigación de las Ciencias de las Ingenierías(GICI) Universidad de San BuenaventuraCartagenaCalle Real de TerneraDiagonal 32#30-966Colombia

The present study aims to develop multilayer barrier-bioactive hybrid sol-gel coatings from a mixture of the silane precursors tetraethylorthosilicate(TEOS)and glycidoxypropyltriethoxysilane(GPTMS)deposited on the Elektron 21 magnesium *** purpose of the inner layer(barrier coating)was to provide corrosion protection to the magnesium alloy,whereas the outer layer(bioactive coating)was doped with different Ca and Mg contents to produce a bioactive *** coatings were characterised using scanning electron microscopy(SEM)and their corrosion behaviour was evaluated by anodic polarisation and electrochemical impedance spectroscopy after immersion in simulated body fluid(SBf)at 37±0.5°*** experimental results showed that the multilayer coatings increased the corrosion resistance of the alloy up to three orders of magnitude during immersion in SBf *** the other hand,the presence of Ca and Mg in the bioactive coating promoted the growth of apatite-like ***,an increment of salt content favoured the formation of porous coatings,which allowed the access of the electrolyte to the substrate leading to their rapid *** the latter,this research endorses the premise that the TEOS-GPTMS hybrid system represents a promising alternative to produce bifunctional barrier-bioactive coatings.

关键词： Magnesium bioactivity coating sol-gel EIS corrosion

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Electronic Tongue and Neural Networks, Biologically Inspired Systems Applied to Classifying Coffee Samples

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American Journal of Analytical Chemistry 2014年第4期5卷 266-274页

作者： álvaro A. Arrieta Almario Rosa L. Tarazona Cáceres grupo de Investigación DANM/desarrollo y Aplicación de nuevos materiales Universidad Pontificia Bolivariana Montería Colombia grupo de Investigación GIE Universidad Pontificia Bolivariana Montería Córdoba

In this paper, the possibility to use an electronic tongue based on a polypyrrole sensor array in classifying coffee samples has been studied. Each sensor shows a distinguished electrochemical response when exposed to the studied solutions, providing signals with a high degree of cross-selectivity. The sensor array electrochemical response is related to the interaction of the ionic and non-ionic solution compounds and to the surface of the sensors polymeric matrix. furthermore, the electronic tongue was used to perform an analysis on coffee samples. In this case, each sensor showed a particular response to each coffee sample. Data obtained from the registered signals were used to perform a discrimination of the samples. The analysis with neural networks of the principal components (NNPC) done on the electronic tongue response to five types of commercial coffee, allows to achieve a clear differentiation of samples.

关键词： Electronic Tongue Coffee Electrochemical Sensors

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Polymeric Nanohydrogels of Poly(N-Isopropylacrylamide)Combined with Others functionalized Monomers:Synthesis and Characterization

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Journal of Biomaterials and Nanobiotechnology 2014年第1期5卷 31-38页

作者： Lissette Aguero Luztono Yuneivy Cepero Donates Luis Guillermo Guerrero Ramirez Addys Gonzalez Palomo Dionisio Zaldivar Silva Issa Katime departamento de Quimica Macromolecular Centro de BiomaterialesUniversidad de La HabanaHabanaCuba grupo de nuevos materiales y Espectroscopia Supramolecular Facultad de Ciencias y TecnologiaBilbaoEspana departamento de Biologia de Sistemas Centro de Inmunologia MolecularHabanaCuba

Nanohydrogels from inverse microemulsion (w/o) polymerization, at 25°C, of N-isopropylacrylamide (NIPA) and functionalized monomers are described. The functionalized monomers were: N-(pyridine-4-ylmethyl) acrylamide (NP4MAM) and tert-butyl 2-acrylamidoethyl carbamate (2AAECM). The polymeric nanohydrogel obtained was characterized by attenuated total reflectance fourier-transformed infrared spectroscopy (ATR-fTIR) and proton nuclear magnetic resonance spectrometry (1HNMR), while their morphology and particle size was assessed by scanning electron microscopy (SEM) and dynamic light scattering. Their thermal properties were studied by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). As a preliminary measure of biocompatibility, in vitro evaluations of the nanohydrogels were carried out by cellular toxicity (colon carcinoma cells, CT-26) and hemocompatibility tests. These evaluations showed that these nanohydrogels were not toxic in the examined concentration range and exhibited preliminary blood compatibility;therefore they could be used in biomedical applications.

关键词： N-Isopropylacrylamide Nanohydrogels Inverse Microemulsion Polymerization In Vitro Biocompatibility

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