The manufacture of medical and aerospace components made of titanium alloys and other difficult-to-cut materials requires the parallel development of high performance cutting tools coated with materials capable of enhanced tribological and resistance properties. In this matter, a thin nanocomposite film made out of AlCrN (aluminum–chromium–nitride) was studied in this research, showing experimental work in the deposition process and its characterization. A heat-treated monolayer coating, competitive with other coatings in the machining of titanium alloys, was analyzed. Different analysis and characterizations were performed on the manufactured coating by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDXS), and X-ray diffraction (XRD). Furthermore, the mechanical behavior of the coating was evaluated through hardness test and tribology with pin-on-disk to quantify friction coefficient and wear rate. Finally, machinability tests using coated tungsten carbide cutting tools were executed in order to determine its performance through wear resistance, which is a key issue of cutting tools in high-end cutting at elevated temperatures. It was demonstrated that the specimen (with lower friction coefficient than previous research) is more efficient in machinability tests in Ti6Al4V alloys. Furthermore, the heat-treated monolayer coating presented better performance in comparison with a conventional monolayer of AlCrN coating.

Surface-enhanced Raman scattering (SERS) is a powerful tool with high potential for detection of dilute analytes. Nanofibers functionalized by metal nanostructures and particles are exploited as effective flexible substrates for SERS analysis. SERS-active substrates of silice-titania-silver (SiO2-TiO2-Ag) nanofibers were prepared using a simple approach involving electrospinning. We report a simple method for quantitative SERS analysis using SiO2-TiO2-Ag nanofibers as the SERS substrate. Precursors SiO2 and TiO2 were synthetized through the sol-gel method and then incorporated into a polymeric PVP matrix; later they were processed by coaxial electrospinning to obtain fibers with an average diameter of 250 nm. The SiO2-TiO2-Ag structure was demonstrated by Raman, XRD, IR, SEM and EDX. Through infrared spectroscopy it was possible to evaluate the thermal evolution of the sol-gel process. The Titania phase transformation was observed around 800 °C and the hydroxyl group loss was detected between 500 and 800 °C. The presence of two Titania phases, anatase and rutile were analized with DRX. Using Pyridine (1 nM) as probe molecule the SERS effect of the scaffold was evaluated and it was determined that the vibration modes 8a, 8b, and 15 were the most amplified signals with a 3 orders of magnitude factor. With this it was concluded that the Silica-Titania-Silver Scaffold is a feasible as a SERS enhancer. Keywords: Electrospinning, Sol-gel, SER

In this perspective article, we emphasize the combination of Surface-Enhanced Raman Spectroscopy (SERS) and Microfluidic devices. SERS approaches have been widely studied and used for multiple applications including trace molecules detection, in situ analysis of biological samples and monitoring or, all of them with good results, however still with limitations of the technique, for example regarding with improved precision and reproducibility. These implications can be overcome by microfluidic approaches. The resulting coupling Microfluidics – SERS (MFSERS) has recently gained increasing attention by creating thundering opportunities for the analytical field. For this purpose, we introduce some of the strategies developed to implement SERS within microfluidic reactor along with a brief overview of the most recent MF-SERS applications for biology, health and environmental concerns. Eventually, we will discuss future research opportunities of such systems.

We propose an experimental technique for the estimation of quality parameters of post-mortem human bone samples with signs of osteoporosis. Since we were interested in characterizing bone microstructure by evaluating porosity, trabecular thickness, and space, we obtained reference values of those parameters for some of our samples through micro-computerized tomography (micro-CT). Nevertheless, as such technology is not widely available, here we used a 2D imaging approximation of those quality parameters. We based our estimation on simple digital microscopy and calibrated to ensure a percentage of similarity higher than 95% in comparison to those values achieved through micro-CT. Additionally, we subjected our samples to mechanical testing to obtain a complete characterization of our samples and to provide a preliminary assessment of the possible relationship between clinical tests of bone mineral density (BMD) and bone quality parameters. Our results show that BMD may have very low specificity in the assessment of the authentic microstructure of bone, then a broader analysis of quality parameters is required to enhance the reliability of future osteoporosis diagnosis technologies.

We present in here a simple and low cost continuous segmented-flow process for the synthesis of Ag and Au spherical-shaped nanoparticles. Different residence times (RT) were used to perform the nanoparticle synthesis, observing that at low RT, the Ag nanoparticles production, which uses a fast reduction reaction with NaBH ₄ , is improved due to an enhancement in the mixing of the reactants. However, the flow conditions have an opposite effect in the case of Au nanoparticles synthesis. Indeed, since the chemical reduction process (Turkevich method) exhibit a much slower kinetics, high RT (low flowrates) improve the synthesis yield and the quality of the nanoparticles. The Ag and Au nanoparticles were characterized by UV-Vis spectrophotometry (UV-Vis) and Transmission Electron Microscopy (TEM). The Ag spherical-shaped nanoparticles presented a LSPR at 400 nm (size ≈ 4 nm), while the synthesized Au nanoparticles exhibit LSPR and sizes in the range 520 - 550 nm and 14 - 17 nm, respectively.