ABSTRACT Nowadays, the use of the CubeSat standard for satellites design has become a strong appliance in space industries and universities because of its low cost. In its simpler model a CubeSat , consists of a cubic nanosatellite with less than 1,33 kg and 10 cm of edge. The present work was done computational simulations using the finite element method since computational simulations are cheaper to do vibration tests. It was carried out modal analyses comparing five CubeSat structures, where it was evaluated the presence of electronic board (without electronic elements), static loads, two different aluminum alloys, and the influence of additional mass in the PCB (Printed Circuit Board). CAD software was used for the structures' design following the CubeSat specifications, and all the simulations were carried out in a finite element software, in a range of 0 to 1000 Hz. It was designed one structure to do initial simulations, followed by the design of 4 structures more adjusted to the CubeSat requirements. In the end, results showed the influences of each present condition on the satellite. It was noticed that influences of the load in the vibration shape and less than 2% in other results. The material available to build a CubeSat for tests was validated concerning the recommended aluminum alloy.

RESUMEN Hoy en día, el uso del estándar CubeSat para el diseño de satélites se ha convertido en un instrumento fuerte tanto en las industrias espaciales como en las universidades debido a su bajo costo. Un CubeSat, en su modelo más simple, consiste en un nanosatélite cúbico con menos de 1,33 kg y con 10 cm de borde. En el presente trabajo se realizaron simulaciones computacionales utilizando el método de elementos finitos ya que las simulaciones computacionales son una forma más barata de hacer pruebas de vibración. Se realizaron análisis modales comparando cinco estructuras CubeSat, donde se evaluó la presencia de placa electrónica (sin elementos electrónicos), las cargas estáticas, dos aleaciones de aluminio diferentes y la influencia de la masa adicional en el PCB (Printed Circuit Board). Se utilizó un software CAD para el diseño de estructuras siguiendo las especificaciones de CubeSat, y todas las simulaciones se llevaron a cabo en un software de elementos finitos, en un rango de 0 a 1000Hz. Se diseñó una estructura para hacer simulaciones iniciales, seguido del diseño de 4 estructuras más ajustadas a los requisitos de CubeSat. Al final se encontraron resultados que muestran las influencias de cada condición presente en el satélite. Se notaron influencias de la carga en la forma de vibración y menos del 2% en otros resultados. El material disponible para construir un CubeSat para las pruebas fue validado en relación con una aleación de aluminio recomendada.

Abstract Environmental friendliness and cost demand the development of lignin-modified phenolic (LPF) resins for application as a binder for carbon-containing refractories (CCRs) production. Moreover, the in-situ graphitization of such resins can produce crystalline carbon, which is an essential component of CCRs. Consequently, this study investigated LPF resins graphitization using ferrocene, boron oxide and boric acid. The modified resins were synthesized using thermally treated kraft lignin based on 1.5 formaldehyde to phenol molar ratio and with up to 30 wt.% lignin as phenol replacement. The resins chemical composition and the structural organization and oxidation resistance of carbons derived from the plain resins and those containing the graphitizing additives were determined. The results showed that ferrocene and the boron compounds could induce graphitic carbon generation when carbonizing LPF resins at 1500 °C for 5 hours. The best graphitization level (73%) was achieved when 10 wt.% boric acid was added to the resin produced with 20 wt.% lignin. Regarding the formulations containing ferrocene, the highest amount of graphitic carbon (48%) was generated when 5 wt.% of this additive was added to the resin synthesized with 10 wt.% lignin. The carbons derived from the formulations containing boron oxide presented the best oxidation resistance.

ABSTRACT Propolis, is a bee product collected from exudates and flower buds of several plants, has strong aroma and several biological applications. This study aimed at evaluating the chemical composition and in vitro antioxidant, antibacterial and cytotoxic properties of volatile oil from Brazilian brown propolis. It was extracted by hydrodistillation and analyzed by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. Volatile oil from brown propolis exhibited strong antibacterial activity against H. pylori (MIC 3.25 µg/ml), Mycobacterium tuberculosis (MIC 50 µg/ml) and M. avium (MIC 62.5 µg/ml). It was evaluated in vitro for antioxidant activity by DPPH (IC50 25.0 µg/ml) and ABTS (IC50 30.1 µg/ml) methods. Its cytotoxic property was evaluated in normal (human fibroblasts, GM07429A) and tumor (MCF-7-human breast adenocarcinoma; HeLa-human cervical adenocarcinoma and M059J-human glioblastoma) cell lines. IC50 values were 81.32 µg/ml for GM07429A and 85.00, 129.40 and 84.12 µg/ml for MCF-7, HeLa and M059J cells, respectively. Three major dereplicated components of volatile oil from brown propolis were acetophenone (15.2%), nerolidol (13.3%), and spathulenol (11.6%). Our results contribute to a better understanding of the chemical and biological properties of Brazilian brown propolis and provide evidence for its potential medicinal use.