This work aims to determine the influence of fused deposition modeling (FDM) printing parameters on the mechanical properties of parts fabricated on an Ultimaker2 printer with acrylonitrile butadiene styrene (ABS). The effect of several parameters such as interlayer cooling time (ILCT), nozzle diameter, infill density, raster angle and layer thickness on the ultimate tensile strength, yield strength, and elastic modulus of produced parts was evaluated. Two independent studies were conducted: a first study dedicated to the ILCT and a second study where the influence of other parameters was evaluated through a design of experiments (DoE) approach. Both studies were carried out through the execution of standard tensile tests. The statistical analysis of tensile tests results was processed with the ANOVA methodology. The obtained results indicate that a reduced ILCT improves the tensile strength of parts. It is shown that nozzle diameter and infill density are the parameters that most influence the mechanical properties of ABS, with the upper range selected values improving the studied mechanical properties. The raster angle configuration of (−45 o /45 o ) benefits UTS and yield strength of ABS samples. Interactions of nozzle diameter onlayer thickness were detected. It was observed that smaller layer thickness promotes a higher elastic modulus and UTS; however, for thinner layers (0.06-0.10 mm), no significant differences were found on strength of samples due to potential high distortion levels.

An integrated photonic‐on‐a‐chip device based on a single organic‐inorganic di‐ureasil hybrid was fabricated for optical waveguide and temperature sensing. The device is composed by a thermal actuated Mach‐Zehnder (MZ) interferometer operating with a switching power of 0.011 W and a maximum temperature difference between branches of 0.89 ºC. The MZ interferometer is covered by a Eu3+/Tb3+ co‐doped di‐ureasil luminescent molecular thermometer with a temperature uncertainty of 0.1ºC and a spatial resolution of 13 µm. This is an uncommon example in which the same material (an organic‐inorganic hybrid) that is used to fabricate a particular device (a thermal‐actuated MZ interferometer) is also used to measure one of the device intrinsic properties (the operating temperature). The photonic‐on‐a‐chip example discussed here can be applied to sense temperature gradients with high resolution (10−3 ºC·µm−1) in chip‐scale heat engines or refrigerators, magnetic nanocontacts and energy‐harvesting machines.

Neste trabalho, descrevemos uma experiência simples e pedagógica para medir a energia livre de superfície (SFE) queé um tema dominante no ensino da Física, a nível de estudos de graduação e pós-graduação. A vantagem desta experiência baseia-se na simplicidade dos materiais utilizados, ou seja, produtos de baixo custo e não prejudiciais, comoágua, glicerol, etileno glicol e propanol, que oferecem uma boa oportunidade para discutir pedagogicamente conceitos básicos, mas relevantes sobre fenómenos de superfície. Como exemplo, medidas dê angulo de contacto foram utilizadas para estimar a SFE e a molhabilidade de diferentes superfícies sólidas, tais como o vidro e o politetrafluoretileno (PTFE, TeflonPalavras-chave: práticas pedagógicas, energia livre de superfície,ângulo de contacto.In this paper we describe a simple and pedagogical experiment to measure surface free energy (SFE), which is a mainstream subject to teach undergraduate and graduate level Physics science. Beyond this, the advantage of this work relies on the simplicity of the materials used, namely non-harmful and low cost products such as water, glycerol, ethylene glycol and propanol, offering a useful pedagogical opportunity to discuss basic but relevant concepts regarding surface science phenomena. As example, contact angle measurements were used to estimate SFE and the wetting behavior of distinct solid surfaces such as glass and polytetrafluoroethylene (PTFE, Teflon R ⃝ ).

Abstract:The applicably of multi-objective optimization to ellipsometric data analysis is presented and a method to handle complex ellipsometric problems such as multi sample or multi angle analysis using multi-objective optimization is described. The performance of a multi-objective genetic algorithm (MOGA) is tested against a single objective common genetic algorithm (CGA). The procedure is applied to the characterization (refractive index and thickness) of planar waveguides intended for the production of optical components prepared sol-gel derived organicinorganic hybrids, so-called di-ureasils, modified with zirconium tetrapropoxide, Zr(OPr n ) 4 deposited on silica on silicon substrates. The results show that for the same initial conditions, MOGA performs better than the CGA, showing a higher success rate in the task of finding the best final solution. ©2010 Optical Society of America