Innovative Metallic Microfluidic Device for Intensified Biodiesel Production

We present a strategy for intensified biodiesel production in a novel metallic microdevice. Additive manufacturing using Selective Laser Melting (SLM) was employed to build the metallic device consisting of multiple micro reactors monolithically integrated with multiple micro heat exchangers. This device allows high conversion rate of biodiesel production with concomitant use of the rejected heat from external source to enhance the reaction temperature and, thereby, its output. The biodiesel production was carried out using soybean oil, ethanol and NaOH as the catalyst. The influences of the reaction temperature and the residence time in the biodiesel production was examined. Biodiesel yield increased with the reaction temperature and a rate of conversion of 99.6% was achieved with a reactor residence time of less than 35 seconds. The work opens up a pathway to exploit waste heat to intensify biodiesel production and contribute significantly to global sustainability

Comparison of five different fixation techniques of sagittal split ramus osteotomy using three-dimensional finite elements analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The aim of this study was to compare the mechanical stress over hemimandible substrate and hardware after sagittal split ramus osteotomy (SSRO) fixed with five different techniques using three-dimensional (3D) finite element analysis. A 3D finite element model of a hemimandible was created and a 5 mm advancement SSRO was simulated on a computer model. The model was fixed with five different techniques: 3 linear 60 degrees screw arrangement; 3 linear 90 degrees screw arrangement; 3 inverted L screw arrangement; 1 conventional miniplate; and I locking miniplate with four monocortical screws. Load was applied until 3 mm displacement was reached and the results were compared with previous mechanical and photoelastic tests, thus analysing the mechanical stresses developed, in the proximity of miniplates and screws and within the fixation system itself. The maximum principal stress values demonstrate a lower mechanical stress rate in bone and in the fixation system with the inverted L arrangement, followed by the linear 90 degrees and linear 60 degrees arrangements. The locking miniplate/screw system presented lower maximum principal stress and better stress distribution compared with the conventional system. Under the conditions tested, the reversed L arrangement provided the most favourable stress dissipation behaviour.418934941Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [141231/2008-4

Surface methods for monitoring the densification of parts in the selective laser sintering process

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Purpose - The purpose of this paper is to characterize polyamide parts prepared by the SLS process using techniques that are dependent on surface properties and compare the results to density measurements in order to assess which technique better reflects the degree of densification achieved using different laser power levels. Design/methodology/approach - Fabrication of Nylon 12 (Duraform PA) samples and their characterization by apparent density measurements, perfilometry, Raman spectroscopy, scanning electron microscopy, specific surface area and contact angle measurements. Findings - Methods dependent on surface analysis are not suitable indicators of the degree of sample densification. Among the surface methods, the results from Raman spectroscopy are the ones with the best performance. Incipient sintering of the superficial layers and raw material powder on the surface, inherent to the parts made by the SLS process, strongly interfere with the characterization. Originality/value - Quantitative comparison of a number of surface probing methods for monitoring densification of SLS parts. Characterization of sample surfaces with and without raw material powder.202157163Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq