Elastic Property Evaluation of Fiberglass and Epoxy Resin Composite Material Using Digital Image Correlation.

This study focused on evaluating the sensitivity and limitations of the simplified equipment used in the Digital Image Correlation (DIC) technique, comparing them with the analog extensometer, based on the mechanical property data of a composite made of fiberglass and epoxy resin. The objectives included establishing a methodology based on the literature, fabricating samples through manual lamination, conducting mechanical tests according to the ASTM D3039 and D3518 standards, comparing DIC with the analog extensometer of the testing machine, and contrasting the experimental results with classical laminate theory. Three composite plates with specific stacking sequences ([0]3, [90]4, and [±45]3) were fabricated, and samples were extracted for testing to determine tensile strength, modulus of elasticity, and other properties. DIC was used to capture deformation fields during testing. Comparisons between data obtained from the analog extensometer and DIC revealed differences of 11.1% for the longitudinal modulus of elasticity E1 and 5.6% for E2. Under low deformation conditions, DIC showed lower efficiency due to equipment limitations. Finally, a theoretical analysis based on classical laminate theory, conducted using a Python script, estimated the longitudinal modulus of elasticity Ex and the shear strength of the [±45]3 laminate, highlighting a relative difference of 31.2% between the theoretical value of 7136 MPa and the experimental value of 5208 MPa for Ex.

Characterization of Porous Scaffolds Fabricated by Joining Stacking Based Laser Micro-Spot Welding (JS-LMSW) for Tissue Engineering Applications.

A novel manufacturing approach was used to fabricate metallic scaffolds. A calibration of the laser cutting process was performed using the kerf width compensation in the calculations of the tool trajectory. Welding defects were studied through X-ray microtomography. Penetration depth and width resulted in relative errors of 9.4%, 1.0%, respectively. Microhardness was also measured, and the microstructure was studied in the base material. The microhardness values obtained were 400 HV, 237 HV, and 215 HV for the base material, HAZ, and fusion zone, respectively. No significant difference was found between the microhardness measurement along with different height positions of the scaffold. The scaffolds' dimensions and porosity were measured, their internal architecture was observed with micro-computed tomography. The results indicated that geometries with dimensions under 500 µm with different shapes resulted in relative errors of ~2.7%. The fabricated scaffolds presented an average compressive modulus ~13.15 GPa, which is close to cortical bone properties. The proposed methodology showed a promising future in bone tissue engineering applications.

Treated residue from aluminium lamination as adsorbent of toxic reactive dyes - a kinetic, equilibrium and thermodynamic study.

The residue generated in the aluminium cold lamination (TTR) was submitted to a direct burning and then it was calcined at 500°C. BET, FTIR, SEM with EDX and TGA techniques were performed to characterize the adsorbent before and after the adsorption. BET analysis showed that TTR specific surface area was 55.37 m2 g-1 and there were no significant changes after the adsorptive process. Afterwards, the TTR was applied as adsorbent of the reactive Drimaren Blue (DB), Drimaren Red (DR) and Drimaren Gold (DG). Its employment consists in a sustainable alternative for the treatment of textile wastewater, once the TTR was used as low-cost adsorbent of textile dyes. Kinetic studies showed that the process reached the equilibrium state between 5 and 10 min. The pseudo-second-order model better fitted the adsorption kinetics, with kinetic rate constants 10.51, 34.71 and 31.51 mg min g-1 for DB, DR and DG respectively. The equilibrium experiments were performed to obtain the adsorption parameters for each dye; moreover, the maximum adsorption capacity was 6.27, 0.42 and 1.23 mg g-1 for DB, DR and DG, respectively. Thermodynamics studies allowed to obtain the values of enthalpy for DB, DR and DG, -7.90, 14.03 and -17.75 kJ mol-1, respectively. Furthermore, the negative values of Gibbs free energy confirmed the spontaneity of the adsorption. The results point to the physisorption characteristic of the process, in which the temperature negatively influenced the adsorption for the DB and DG; the opposite result was observed for the DR.

Xurography as a Rapid Fabrication Alternative for Point-of-Care Devices: Assessment of Passive Micromixers.

Despite the copious amount of research on the design and operation of micromixers, there are few works regarding manufacture technology aimed at implementation beyond academic environments. This work evaluates the viability of xurography as a rapid fabrication tool for the development of ultra-low cost microfluidic technology for extreme Point-of-Care (POC) micromixing devices. By eschewing photolithographic processes and the bulkiness of pumping and enclosure systems for rapid fabrication and passively driven operation, xurography is introduced as a manufacturing alternative for asymmetric split and recombine (ASAR) micromixers. A T-micromixer design was used as a reference to assess the effects of different cutting conditions and materials on the geometric features of the resulting microdevices. Inspection by stereographic and confocal microscopy showed that it is possible to manufacture devices with less than 8% absolute dimensional error. Implementation of the manufacturing methodology in modified circular shape- based SAR microdevices (balanced and unbalanced configurations) showed that, despite the precision limitations of the xurographic process, it is possible to implement this methodology to produce functional micromixing devices. Mixing efficiency was evaluated numerically and experimentally at the outlet of the microdevices with performances up to 40%. Overall, the assessment encourages further research of xurography for the development of POC micromixers.

Laminated ceramics with elastic interfaces: a mechanical advantage?

OBJECTIVES: As CAD/CAM technologies improve we question whether adhesive lamination of ceramic materials could offer mechanical advantages over monolithic structures and improve clinical outcomes. The aim was to identify whether an adhesive interface (a chemically cured resin-cement) would influence the biaxial flexure strength (BFS) and slow-crack growth in a machinable dental ceramic. METHODS: Monolithic and adhesively laminated (with a chemically cured dimethacrylate resin-cement) feldspathic ceramic discs of identical dimensions were fabricated. BFS testing was performed on the Group A monolithic specimens (n = 20), on Group B laminated specimens with the adhesive interface positioned below the neutral bending axis (n = 20) and Group C laminated specimens with the adhesive interface positioned above the neutral bending axis (n = 20). To study subcritical crack growth additional laminated specimens received controlled indentations and were exposed to thermo-mechanical fatigue. BFS data was analysed using parametric statistics (α = 0.05). Fractographic analyses were qualitatively assessed. RESULTS: No significant differences between the mean BFS data of Groups A and B were observed (p = 0.92) but the mean BFS of Group C was slightly reduced (p < 0.01). Lamination reduced the stiffness of the structure and fractographic analysis demonstrated that energy consuming crack deflection occurred. Thermo-mechanical fatigue caused subcritical extension of radial cracks associated with indentations adjacent to the adhesive interface. Crack growth was limited to parallel to the interface and was arrested or deflected in a direction normal to the interface. CONCLUSIONS: Ceramic lamination increased the damage tolerance of the structure and could limit or arrest subcritical crack growth at regions near the 'interlayer'. CLINICAL SIGNIFICANCE: Lamination of a dental ceramic with a polymeric 'interlayer' could offer toughening effects which could potentially delay or arrest sub-critical crack growth at regions near the interface and thereby improve restoration longevity.

Inoculação de silagens de grãos úmidos de milho, em diferentes processamentos

Two experiments were run to evaluate the pattern of fermentation, the chemical composition and in vitro digestibility of dry matter (IVDDM) of high moisture corn grain silages, with or without microbial inoculation, in different processing. Experiment 1 dealt with inoculation of high moisture corn triturated grain silages, in completely randomized experimental design. Experiment 2 dealt with inoculation of high moisture corn triturated and laminated grain silages, in completely randomized experimental design, in 2 x 2 factorial arrangement. The material was ensiled in experimental silos of PVC (50cm length and 100mm diameter). Samples were taken before and after ensilage. In the experiment 1, the IVDDM of inoculated silages was major than control silages, with averages of 80.67 and 79.80%, for inoculated and control silages, respectively. pH and NH3-N (% total N) and DM losses were not influenced by inoculation, with 3.91, 1.19% total N and 1.18% DM, respectively. In the experiment 2, there was not influence by inoculation and processing on IVDDM, mean of 74.59%. pH and NH3-N were influenced by inoculation, 3.89 vs 3.94 and 0.63 vs 0.72% total N, by inoculated and control silages, respectively. The microbial inoculation of high moisture corn grain does not promote alterations either in the fermentative pattern, chemical composition or in the DM losses in corn high moisture silages, independent of processing. There was an improvement of 1.09% in IVDMD of high moisture corn silages inoculated.

Objetivou-se avaliar os parâmetros fermentativos, a composição química e a digestibilidade in vitro da matéria seca (DIVMS) de silagens de grãos úmidos de milho, confeccionados com ou sem o uso de inoculante microbiano, em diferentes processamentos. No experimento 1, avaliou-se a inoculação de silagens de grãos úmidos de milho triturados, em delineamento inteiramente casualizado. No experimento 2, avaliou-se a inoculação de silagens de grãos úmidos de milho, triturados e laminados, em delineamento inteiramente casualizado, em esquema fatorial 2 x 2. O material foi ensilado em silos experimentais de PVC (50cm de comprimento e 100mm de diâmetro) e amostras foram tomadas antes e após a ensilagem. No experimento 1, a DIVMS de silagens inoculadas foi superior à de silagens controle, com médias de 80,67 e 79,80%, respectivamente. O pH, N-NH3 (% N-total) e perdas de MS não foram influenciados pela inoculação, com médias de 3,91, 1,19% N-total e 1,18% MS, respectivamente. No experimento 2, não houve influência da inoculação e do processamento sobre a DIVMS, com média de 74,59%. O pH e N-NH3 foram influenciados pela inoculação, com médias de 3,89 vs 3,94 e 0,63 vs 0,72% N-total, para silagens inoculadas e controle, respectivamente. De maneira geral, a inoculação microbiana não altera o padrão de fermentação, composição química e perdas da MS nas silagens de grãos úmidos de milho, independente do processamento. Houve melhoria de 1,09% na DIVMS de silagens inoculadas de grãos úmidos de milho.