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Heteroatoms in multiwalled carbon nanotubes modify their chemical reactivity and electronic properties. Nitrogen as a doping element changes the morphology by boosting the surface area, the density of defects, electronic states, and chemically actives sites that improve the electrocatalytic activity and other properties. Nitrogen defects create mainly the pyridinic, pyrrolic, and quaternary-N configurations presenting different localized electronic configurations. This work outlined and studied the distribution and physicochemical properties of N-doped multiwalled carbon nanotubes as a function of the temperature profile along a CVD reactor. X-ray photoelectron spectroscopy demonstrated that the nitrogen content is maximal in the second furnace high-temperature zone, and the pyrrolic-N doping predominate. The ID/IG ratio from Raman spectroscopy increases in this zone, revealing a defective graphitic material. The cyclic voltammetry showed that the specific capacitance increases for pyrrolic-N from the last three-quarters of the reactor due to the augment of active carbon atoms associated with pyrrolic-N defects and the chemical decomposition of nitrogen precursor alongside the reactor. Theoretical calculation on the electronic properties and potential electrostatic surface of carbon nanotubes suggests the surface metallicity when pyridinic-N and quaternary-N are dominant and active sites for possible hydrogen or oxygen binding when pyrrolic-N are prevalent.

This work includes the search for the development of a composite of a WPU (waterborne polyurethane), β-CD (β-Cyclodextrin), PZnO (zinc oxide particles), and the presence of CaCO3, to obtain new properties such as adhesion to multiple substrates of organic and inorganic origin. Therefore, a development sequence was proposed: Computational development: conformation of the polymeric matrix (with the intermediary polymers) and simulation of the interaction between β-CD and PZnO and Ca+2 and CO3-2 ions, as well as insertions in β-CD, computational simulations were carried out with the help of ACD LABS™ (free version) software and by molecular dynamics with GROMACS™. With the above, we were able to determine properties such as interfacial tensions, surface tensions, and contact angles, and degrees of solvation and stability in waterborne emulsions. Therefore, it is important to point out that one of the main contributions of this research proposal is that there are no studies that combine these materials.

Magnetic nanoparticles have been used to confer better properties to materials, particularly to polymers. Due the properties of the polymer, such as flexibility and lightness, combined, white nanoparticles provide other properties such as microhardness, corrosion resistance, among others. In this study, three types of nanoparticles were elaborated: magnetite, cobalt ferrite and nickel ferrite, through the coprecipitation method used in the elaboration of skin-like polyurethane (PU) -based composites. Specimens were made at different nanoparticle weights (0.1%, 0.3%, 0.5% and 1.0%). Likewise, the hardness was measured by means of a phase II Model PHT-2500 portable digital hardness tester and the tension tests were carried out on an Autograph Shimadzu universal machine. The stress results were plotted using the Jupyter Notebook for interpretation. Finding some improvements in the materials manufactured using the different ferrites already mentioned.

The combination of different nanomaterials to achieve particular applications is a topic with an increasing impact on diverse areas of nanotechnology. In particular, the material of La2Zr2O7 (LZO) and NiO could be employed as a source of catalyst for carbon nanotube fabrication. In this work, the Ni/LZO material was utilized to fabricate nitrogen-doped multiwalled carbon nanotube (N-MWCNTs). The N-MWCNTs were produced at 850 °C by the aerosol assisted catalytic chemical vapor deposition method using benzylamine as the sole carbon and nitrogen precursor. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and vibrating sample magnetometry. Before the synthesis of N-MWCNTs, NiO was reduced to Ni to act as a catalyst and LZO as support. N-MWCNTs exhibited the typical feature bamboo shape morphology with small nanoparticles anchored inside and on its surface. The electrochemical studies show interesting results about charge capacity and a hydroquinone/quinone redox process of oxygen functionalities. The magnetic properties of N-MWCNTs showed a ferromagnetic behavior with a saturated magnetization of 43 emu/g at 0.2 T.

The creation of films formed by the incorporation of ZnO or TiO2 in poly(methylmethacrylate) PMMA matrices was proposed in order to improve their properties as resistance to high temperatures. ZnO and TiO2 nanoparticles were synthesized by the sol-gel method, which does not require the use of surfactants and is easily scalable. In the present work, zinc oxide (ZnO) or titanium oxide (TiO2) incorporations were carried out in a polymeric matrix of Poly(methylmethacrylate) PMMA. Both oxides were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD) and diffuse reflectance UV-Vis spectroscopy. PMMA was obtained by the suspension free radical polymerization method and PMMA composites containing ZnO or TiO2 were obtained. Polymer characterization was performed using Fourier transform infrared spectroscopy (FTIR). The composites were analyzed by thermogravimetric analysis (TGA) and its thermal resistance was found to be the best incorporation of TiO2 in 1%.

Objective. Different types of nanoparticles, including carbon ones, were tested for a variety of biological applications. Alongside with promising results, some undesired side effects were disclosed. Most biological studies were performed on highly functionalized carbon nanospheres, so the main objective of this study was to assess cytotoxicity of unfunctionalized carbon nanospheres synthetized by sol-gel method. We hypothesize that unfunctionalized material will present different cytotoxic pattern on cell culture. Methodology. 3 carbon nanosphere materials were synthetized by sol-gel method. Particles shape, size and functionalization were assessed. Cytotoxic effect of synthesized materials was evaluated on SH-SY5Y cell line using XTT and crystal violet assays and imaging. Contribution. In this work we have demonstrated that cytotoxic effect of carbon nanospheres can be attenuated by varying the conditions of synthesis.

Due to continuous use and environmental factors (humidity and continuous exposure to the sun), the leather upholstery experiences cracking, discoloration and possible yellowing. The above factors significantly decrease the life of leather upholstery in cars. The objective of this work is to synthesize zinc oxide nanoparticles, which have optical properties that allow it to absorb UV radiation and then incorporate them into a polymeric matrix to develop a coating with UV protection for leather finishing in the automobile industry. The particles of zinc oxide were synthesized by the sol-gel method to obtain a nanometric particle size, the method represent a low-cost synthesis method, without the use of surfactants and easily scalable. With monoethylene glycol was formed a stable colloid with the zinc oxide nanoparticles and the polymer matrix. Finally, the final leather finishing obtained for the automotive industry has greater resistance to bending, also thermal stability was improved. In consequence, the lifetime of the leather finishing has improved.

The objective of the present article is to introduce nanoparticles of a ferromagnetic material (magnetite) to the polymer matrix. We will make some study to verify that the coupling of the nanoparticles in the material was carried out. The present work describes the self-assembly of nanocomposite in suspensión polymerization of PS/PMMA block copolymer, containing magnetite (Fe3O4) which is sonicated with the monomer mixture, with percentages of 0.25% and 0.5% in proportion of the weight of mixture. Photographs were taken with the microscope to verify the coupling of the ferromagnetic material to the polymer matrix, and to verify that couplig, we made characterization by infrared spectroscopy. Also describes the process of nanocomposite synthesis using co-precipitation method, in which ferric chloride and ferrous chloride are combined in an excess basic medium, to subsequently induce the precipitation of the material with a magnet.

The creation of films constituted by semiconductor oxides of zinc oxide (ZnO) incorporated into a polar polymer matrix was proposed, looking for such films to be easy to apply, friendly to the environment and compatible with materials. Within the experimental process, the synthesis of styrene copolymers with a polar monomer (methyl methacrylate) was carried out through the suspension and emulsion polymerization processes.

The production of artificial polymers is, today, one of themost important activities of the chemical industry, polymersare widely used in everyday life, as, there are different types of polymers, they can be used for different uses. These polymeric materials have unique mechanical, physical and chemical properties, which most other materials do not possess, not to mention that its cost is lower than the other materials. The present research work focuses on the determination of optimal operating conditions for the polymerization of styrene and methyl methacrylate in a Batch reactor, as well as the influence of inorganic salt in this case NaCl in the performance of reaction and in the size of the material polymer, through the process of suspension using a synthetic route of polymerization by radical free conventional (FRP), where viscometry to the polymeric material testing was performed for this way characterize it, and to determine factors of interest such as the molecular weight, etc.

Currently, the polymers industry has gained increasing importance due to the versatility of its properties. In this work were synthesized copolymers of styrene with vinyl acetate at different concentrations through a process polymerization of suspension, which are the starting points for obtaining of composites with polyaniline synthesized PANI chemical oxidative polymerization process, used for doping HCl at a concentration of 1.5 M and ammonium persulfate 0.5 M in a mass radio of 1:1. The conductivity was evaluated by means of cyclic voltammetry and impedance spectroscopy, in order to determine the effect of the concentration of the polar monomer in the composite founded that increase concentration of polar comonomer the conductivity also too.

In this work, electrochemical sensors were developed for the detection of artificial sweeteners such as D-sorbitol and Maltitol in aqueous solutions. These compounds are classified as polyalcohols and are widely used in the food and beverage industry to replace common sugar. However, their consumption is not currently regulated, and excessive use leads to consequences in the body such as increased blood glucose levels. Graphene oxide (OG) inks were prepared, which were deposited on vitreous carbon (CV) electrodes, followed by enzymatic immobilization. The detection capacity of the biosensors was evaluated applying electrochemical techniques. The biosensor with the best levels of detection, reproducibility and durability for the analytes under study for the detection of D-Sorbitol turned out to be that measured at a working voltage of 0.86 V vs Ag / AgCl / KCl (3 M), depositing 20 μL of OG ink and using a dilution of 0.5 μL / 100 μL of (alcohol oxidase / PBS). In the case of Maltitol the best designed biosensor was worked at 1.06 V vs Ag / AgCl / KCl (3 M), depositing 20 μL of OG ink and using a dilution of 2.0 μL / 100 μL of (alcohol oxidase / phosphate buffer).

The research aims were to construct an air-breathing paper-based microfluidic fuel cell (paper-based μ FC) and to evaluated it with different soft drinks to provide energy for their prospective use in portable devices as an emergency power source. First, in a half-cell configuration, cyclic voltammetry showed that glucose, maltose, and fructose had specific oxidation zones in the presence of platinum-ruthenium on carbon (PtRu/C) when they were individual. Still, when they were mixed, glucose was observed to be oxidized to a greater extent than fructose and maltose. After, when a paper-based μ FC was constructed, PtRu/C and platinum on carbon (Pt/C) were used as anode and cathode, the performance of this μ FC was mostly influenced by the concentration of glucose present in each soft drink, obtaining maximum power densities at room temperature of 0.061, 0.063, 0.060, and 0.073 mW cm − 2 for Coca Cola ® , Pepsi ® , Dr. Pepper ® , and 7up ® , respectively. Interestingly, when the soft drinks were cooled, the performance was increased up to 85%. Furthermore, a four-cell stack μ FC was constructed to demonstrate its usefulness as a possible power supply, obtaining a power density of 0.4 mW cm − 2 , using Coca Cola ® as fuel and air as oxidant. Together, the results of the present study indicate an alternative application of an μ FC using soft drinks as a backup source of energy in emergencies.

Polyfluorene materials have demonstrated to be important components in the fabrication of organic solar cell devices, in both: the active and electron transport layers. The oxidative synthesis as well as optical and electrical properties of new polyfluorene copolymers containing 2,2′-(9,9-dioctyl-9H-fluorene-2,7-diyl) bistiophene and 3-alkylthiophene, alkyl = hexyl (PA1) and octyl (PA2) or 3,4-ethylenedioxythiophene (EDOT) (PM) were investigated. Changes in the HOMO–LUMO energy gap promoted for the insertion of EDOT ring were studied in thick film by using cyclic-voltammetry measurements and compared with the optical properties analyzed by UV–Visible spectroscopy. DFT calculations were used to investigate the possible electronic density distribution and conformational parameter for repetition units into the polymeric structure. Finally, these polymer were preliminary evaluated as donor materials into organic solar cells with architecture ITO/PEDOT:PSS/co-polymer:PC71BM/Field’s metal. Photovoltaic devices showed a very acceptable open circuit voltage (Voc) value, up to 0.92 V.

Objectives. The electrical impedance spectroscopy (EIS) is relatively new technique used in medicine. The main problems that should be solved are its low resolution and that it fails to distinguish between tissue types, so some kind of the contrast should be applied. Magnetical nanoparticles have been used for imaging and other medical applications. For that reason, our research group decided to analyse the changes of electrical properties of chicken muscle tissue caused by three different types of metal nanoparticles at 50KHz. Methodology. Bio-Logic Science Instruments SP-150 was used as EIS device. Three different particles were analysed: two types of nanomagnetite (NM1 and NM2) and one of Gold particles (GNP). NM1 and NM2 samples were synthetized by coprecipitation and combustion method, respectively. GNP were synthetized by Turkevich method. Nanoparticles were characterized by SEM and RAMAN spectroscopy. Four needles were placed in each chicken breast to connect the EIS device. Measurements were obtained from each chicken breast at basal stage and after being injected with nanoparticles. Data was analyzed by bode graphics (module and phase). Contribution. The major changes of electrical properties of tissue were evidenced by using NM1 and GNP.

Objectives. Contamination with heavy metals has augmented in last decades due to several factors. So, scientific community has a challenge to develop new and more efficient methods for contaminants removal. Electroadsorption is one of investigated techniques with promising results. The main challenge with this technique is determination of optimal parameters, such as electrode material, time and conditions of adsorption. Material for electrode for electroadsorption must fulfil some criteria: high electroactive area, low electrical resistance and environmental compatibility. For that reason, our research group decided to synthetize a set of new carbon materials with high surface area and features than make them interesting to test them as an electrode material. Methodology. 3 carbon materials were synthetized by sol-gel method using different time and temperature conditions. All materials were characterized by scanning electron microscopy and other techniques. FTO glasses were modified with synthetized materials separately. Electroadsorption of Cu (II) was conducted at room temperature. Contribution. In this work we demonstrate an easy synthesis of 3 carbonaceous materials with high surface area capable to remove Cu (II) from water solution by electroadsorption.

Objectives. Electrical impedance spectroscopy (EIS) is a harmless non-invasive technique that allows to measure and monitor different physiological parameters. One of the problems with establishing new procedures based on EIS is difficulty to distinguish between tissue types. For that reason, our research group have decided to assess a possibility to use nanomagnetite as a contrast medium in EIS procedures. In this work we present characterization the electrical properties of a porcine heart tissue by EIS using a magnetite particles suspension as contrast medium. Methodology. SP-150 from BioLogic Science Instruments was used as EIS equipment. Porcine heart tissue was used as biological tissue. Nanomagnetite particles were synthetized by coprecipitation and combustion methods and named NM1 and NM2, respectively. EIS device was connected at each ventricle through four hypodermic needles (38mm). Left and right ventricle was injected with NM1 and NM2 particles, respectively. Impedance measurements were acquired for each ventricle before and after the injection. Contribution. Both samples of magnetite nanoparticles were able to change electrical properties of heart tissue. Studies in vivo must be performed in order to confirm the conclusion.

We investigated the effects of long-time thermal oxidation (LTO) of nitrogen-doped multiwalled carbon nanotubes (N-MWCNTs) at 330 °C in air. By scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, Raman spectroscopy and cyclic voltammetry we characterize the oxidized N-MWCNTs (Ox-NMWCNTs). SEM and TEM characterizations revealed that LTO promoted structural damages driven by Fe-based nanoparticles, producing holey N-MWCNTs. The XRD patterns showed that short times of oxidation process, encapsulated Fe3C, and α-Fe nanoparticles in N-MWCNTs cut or perforate their graphite layers. For LTO (>300 h), Fe3C and α-Fe nanoparticles are transformed into Fe3O2 (hematite structure). Deconvolution analysis of the (0 0 2) crystallographic planes allows us to monitor the graphitization evolution of the Ox-NMWCNTs. XPS characterization demonstrated that the surface composition of Ox-N-MWCNTs is influenced by the LTO, while carbon and nitrogen decrease in percentage, the oxygen increases. We have found that LTO favored the formation of pyrrolic nitrogen doping. The holey N-MWCNTs are a porous material with a moderate surface area. According to the voltammetry studies, when the Ox-N-MWCNTs are acid-treated, the surface area is doubled and presents a double layer capacitance that could be advantageous for energy applications.

Natural catalysts are important for the low-cost and large-scale production of carbon nanostructures. In this study, we used a natural material obtained from thin bands of sedimentary rocks known as Banded Iron Formation (BIF). BIF powders (pristine and ball-milled) were used as catalysts for the large-scale production of nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) via an aerosol-assisted catalytic chemical vapor deposition (AACCVD) experiment. The morphology and composition profiles of the BIF powders and N-MWCNT samples were analyzed by scanning and transmission electron microscopies, X-ray diffraction, X-ray photoelectron (XPS) and Raman spectroscopies, and thermogravimetric analysis. XRD characterizations revealed that the BIF powders were mainly composed of quartz and hematite. This result was also confirmed by Raman spectroscopy. The production efficiency of 340% wt./wt. of the N-MWCNTs was obtained by 1 h ball-milled BIF powders. The specific surface area of the N-MWCNTs reached 37.87 m2/g. The type of nitrogen doping, oxygen functional groups, silicon, and carbon species (sp2 and sp3) hosted at the surface of the N-MWCNTs were quantified by XPS. The electrochemical response of electrodes composed of the N-MWCNTs were studied via cyclic voltammetry, electrochemical impedance, and coulombic efficiency determination to assess the possible applications of our synthesized materials as energy storage or sensor systems. The magnetic properties and effects of acid and thermal treatments on the morphology of the N-MWCNTs are also presented.

The chemical synthesis of the copolymers poly(3-HT-co-EDOT-co-fluorene) and poly(3-HT-co-EDOT-co-TDR1) is reported. The first copolymer is derived of 3-hexylthiophene (3-HT), 3,4-ethylenedioxythiophene (EDOT) and 2,2'- (9,9-dioctyl-9H-fluorene-2,7-diyl) bisthiophene (fluorene). The second copolymer is derived of 3-hexylthiophene (3-HT), 3,4-ethylenedioxythiophene (EDOT) and (E)-2-(ethyl(4-((4-nitrophenyl)diazenyl)phenyl)amino)ethyl 2-(thiophen-3-yl)acetate (TDR1). Their physicochemical characterization by 1H NMR, FT-IR, DSC-TGA, GPC, UV-vis, cyclic voltammetry was carried out. These copolymers combine the high electron density and low oxidation potential of EDOT with the high charge mobility and processability of 3-HT. These are candidates for applications as active or barrier layer in electronic devices (bulk heterojuntion organic solar cells) or as functional membranes (e.g., sensors).

Nickel ferrite nanoparticles (NiFe 2 O 4 ) were synthesized by electrochemical method and used as catalyst for direct oxidation of glucose, NADH and methanol. Characterization of these nanoparticles was carried out by X-ray diffraction, Mossbauer spectroscopy, and colloidal properties such as hydrodynamic radius and Zeta potential. To evaluate the catalytic properties of these nanoparticles against the oxidation process, paste graphite electrodes mixing nickel ferrites and different conductive materials (graphite, carbon nanotubes) and binders agents (mineral oil, 1-octylpyridinium hexafluorophosphate ( n OPPF6)) were used. The results prove good catalytic properties of these materials, with an oxidation potential around 0.75, 0.5 and 0.8 V for glucose, NADH, and methanol, respectively.

In this work a new route for preparation of nickel ferrites nanoparticles has been developed. The synthesis is carried out in an electrochemical cell using three electrodes, a sheet of iron was employed as cathode and two sheets of iron and nickel were used as sacrificial anodes. The obtained nanoparticles were washed several times with distilled water, separated magnetically and dried under vacuum with constant temperature for 12 h. The characterization of the nanoparticles was carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Inductively coupled plasma mass spectrometry (ICP–MS). Magnetic measurements were carried out using a vibrating sample magnetometer (VSM). To evaluate the catalytical properties of these nanoparticles against the oxidation of glucose a graphite paste electrode (GPE) was made. The proportions of the nanoparticles in GPE were 5, 10, 20 and 50% in weight. The electrode shows promising properties for its use as catalyst in the glucose oxidation.

We evaluated the performance of glucose/O2 fuel cells, constructed as fluidic chips with controllable fuel flow and comprising a maghemite (γ-Fe2O3) nanoparticle/GOx-coated anode and Pt nanoparticles as the cathode. Maghemite is a biocompatible material that mediates electron transfer during glucose oxidation. The open-circuit voltage of the cell was 0.30 V, with a maximum power density of 30 μW cm−2 at pH 7.4. The voltage cell and power density were compared with those of other microfluidic fuel cells. During continuous operation, the current density of the cell decreased to 50%, likely due to swelling of the enzyme bilayer.

The management of the vaccination program is part of nursing competences. The main goal of this program is to vaccinate the whole population. There are some age groups in which vaccination coverage is represented by very low rates. Several methods can be used in order to increase such coverage and each professional shall use them according to the work environment. This article presents a simple and effective intervention applicable in any rural area--and probably in any environment--through schools, where all children regularly go. This program has been very useful for us to increase the vaccination coverage of children aged 6.