ABSTRACT Currently, the presence of spurious microwave radiation is increasing in the environment, which has caused concern due to possible health problems in living beings and electromagnetic interference in electronic systems. To control this problem, studies in the materials area are taking place, aiming to attenuate the spurious radiation and meet requirements of good performance in broadband, low cost and low weight. The present work aimed to study Cu and Ni nanometric films with thicknesses of 65 and 200 nm, deposited on polyethylene terephthalate substrate by magnetron sputtering. Scanning electron microscopy with a field emission gun (FEG-SEM) showed that the films produced have different morphological textures, due to the parameters used in the sputtering process and also the free energy of metals. Impedance spectroscopy measurements showed that the films have low conductivity values, due to the metallic oxides formed on the film surfaces, confirmed by X-ray diffraction, and also to the presence of defects. Electromagnetic characterization (8.2 – 12.4 GHz) showed that the Cu and Ni thin films had low performance, except the Ni_200 nm film, which showed a total shielding efficiency of about 30% in broadband. This result is promising considering the nanometric thickness of the Ni film.

Pharmaceutical, cosmetic and personal care products are mainly based on emulsions and their rheological behavior can be a critical factor for successful use. Thus, rheological analysis is a promising tool, since the stability, sensory aspects and processing parameters can be assessed. This work presents the rheological analyses of 39 samples of emulsions and the use of data obtained in a tool based on artificial neural networks (ANN), in order to predict the sensory performance of cosmetic emulsions. The storage (G’) and loss (G”) moduli, yield stress and thixotropy were measured experimentally and used in the ANN model. The correlation of the results obtained in the simulations with sensory tests performed with consumers showed accuracy of 60-84%. The reported results demonstrate that the prediction of sensory perception based on rheological analyses offers a very useful strategy for further studies and can support the development of new products in less time.

RESUMO O carbono vítreo reticulado (CVR) é um material carbonoso, rico em átomos de carbono ligados por ligações sp2, obtido pelo tratamento térmico (TT) de carbonização (a pelo menos 1000 ºC, sob atmosfera inerte) de resinas termorrígidas. A sua obtenção pode se dar por diferentes metodologias, usualmente pelo uso de um material de sacrifício, que se degrada durante o TT e gera poros de transporte. Este trabalho teve como objetivo avaliar a influência de diferentes tempos de patamar (2, 8, 12, 24 e 36 h) a 1000 ºC nas características estruturais, morfológicas e condutividade elétrica de amostras de CVR obtidas a partir de uma espuma de poliuretano (PU, material de sacrifício), impregnada com resina furfurílica (PFA). A espuma de PU/PFA foi caracterizada por espectrofotometria de infravermelho com transformada de Fourier (FT-IR) e análises termogravimétricas, as amostras de CVR por difração de raios X (DRX), microscopias óptica (MO) e eletrônica de varredura (MEV), e condutividade elétrica por 2 pontas. Os resultados de FT-IR e DRX confirmam a conversão da espuma de PU/PFA no CVR, com um rendimento de ~44%. As análises de DRX também evidenciam mudanças no ordenamento estrutural das amostras de CVR em função dos diferentes tempos de patamar, devido à provável expulsão de heteroátomos ainda presentes na estrutura do referido material carbonoso. As medidas de condutividade elétrica corroboram com essa observação, com um aumento significativo a partir de 8 h de patamar (de 1,71 x 10-1 para 1,17 x 104 S.cm-1), como uma consequência da diminuição de defeitos na estrutura do CVR. As micrografias mostram a estrutura alveolar da espuma de PU/PFA, rica em poros de transporte, que é preservada no CVR, após a carbonização.

ABSTRACT Reticulated vitreous carbon (RVC) is a carbon material, rich in carbon atoms linked by sp2 bonds, obtained by the thermal treatment (TT) of carbonization (at least 1000 ºC, under inert atmosphere) of thermoset resins. It can be obtained by different methodologies, usually through the use of sacrifice material, which degrades during TT and generates transport pores. This work aimed to evaluate the influence of different threshold times (2, 8, 12, 24, and 36 h) at 1000 ºC on the structural, morphological, and electrical conductivity characteristics of RVC samples obtained from a polyurethane foam (PU, sacrifice material), impregnated with polyfurfuryl alcohol resin (PFA). The PU/PFA foam was characterized by infrared spectrophotometry with Fourier transform (FT-IR) and thermogravimetric analyzes and CVR samples by X-ray diffraction (XRD), optical microscopy and scanning electron microscopy (SEM), electrical conductivity by 2 points. The FT-IR and XRD results confirm the conversion of PU/PFA foam to RVC, with a carbon yield of ~44%. The XRD analyzes also show changes in the structural ordering of the RVC samples due to the different threshold times, due to the probable expulsion of heteroatoms still present in the carbon material structure. The electrical conductivity measurements corroborate this observation, with a significant increase after 8 h of threshold (from 1.71 x 10-1 to 1.17 x 104 S.cm-1), as a consequence of the decrease of defects in the RVC structure. The micrographs show the alveolar structure of the PU/PFA foam, rich in transport pores, which are preserved in the RVC after carbonization.

Nanobiomaterials based on superhydrophilic vertically-aligned multi-walled carbon nanotubes (VAMWCNT-O2) are promising for their properties and bone tissue biocompatibility. VAMWCNT-O2 films with nanohydroxyapatite (nHAp) aim to improve mechanical properties and biocompatibility of this new nanocomposite due to its resemblance to bone matrix structure. This study aimed to produce in vitro biomineralized nHAp/VAMWCNT-O2 nanocomposites using simulated body fluid (SBF) with two different pHs (6.10 and 7.40) during 7 days to obtain a new surface design with higher crystalinity and better morphology of nHAp/VAMWCANT-O2 nanocomposites. The objective is to obtain biomineralized nanobiomaterials to enable its applicability as "scaffold" to cellular support and consequent bone tissue formation, accelerating the osseointegration. Layer densification has been achieved due to polycrystalline nanoapatites deposition on surface and between the biomineralized nHAp/VAMWCNT-O2 nanocomposites, without any heat treatment. Therefore, through its characteristics and properties these nanocomposite applications can be considered extremely viable for acceleration of in vivo regenerative processes.

Nanocomposites based on superhydrophilic vertically aligned multi-walled carbon nanotubes (VAMWCNT-O2) and nanohydroxyapatite (nHAp) are of great interest in bone regenerative medicine. The biomineralization using simulated body fluid (SBF) has been extensively studied to evaluate the bioactivity of biomaterials. Thus, the combination of nHAp and VAMWCNT-O2 is attractive and promising. The aim of this study was to evaluate the in vitro calcification of nHAp/VAMWCNT-O2 nanocomposites before and after the period of biomineralization in SBF. In vitro calcification of the extracellular matrix (ECM) of HOB cells in culture after 24 hours was investigated through the assay of alkaline phosphatase. These promising in vitro results validate biomineralized nHAp/VAMWCNT-O2 as possible scaffolds for bone tissue regeneration.

For the first time, the growth mechanism of biominerals formed on plate-like nanohydroxyapatite (nHAp) electrodeposited on superhydrophilic vertically aligned multi-walled carbon nanotubes (VAMWCNT-O2) is presented and a model for the specific growth preference is discussed. VAMWCNT-O2 films were obtained by microwave-assisted chemical vapor deposition method and funcionalized by oxygen plasma. nHAp/VAMWCNT-O2 nanocomposites were fabricated with a direct electrodeposition of the thin nHAp films onto the VAMWCNT-O2 films. The biomineralized "scaffolds" were obtained by soaking nHAp/VAMWCNT-O2 in simulated body fluid for 7, 14 and 21 days. Results show that the carboxyl functional groups directly attached onto VAMWCNT tips after oxygen plasma treatment were essential for the acceleration of the OH- formation and the deposition of plate-like nHAp crystals.