Héctor Herrera-Hernández

Synthesis and Characterization of Zn-Nix Advanced Alloys Prepared by Mechanical Milling and Sintering at Solid-State Process

Mechanical ball milling assisted by sintering in the solid state was used in this research to produce the Zn-Nix system alloy. The derivative powder compositions of Zn-Nix (x = 0, 5, 10, 15, and 20 wt.%) were obtained to study the Ni effects on the microstructural and mechanical properties. It is worth remarking that conventional methods are not appropriate for the manufacture of the Zn-Nix system alloy. The morphological structure and phases were examined by optical microscopy, X-ray diffraction, and SEM/EDS elemental mapping, whereas the mechanical behavior was accomplished by means of a diamond indentation print (Hardness Vickers). The results showed that the intermetallic γ-ZnNi phase did not form during milling time (<4 h); it appears after the sintering process, which is associated with atomic diffusion mechanism through grain boundary at the minimum interfacial energy (ΔG256°C = −13.83 kJ·mol−1). The powder Zn-Ni10 was found to have better properties. Semispherical coarser particles were seen into the metal matrix (Zn δ-hcp structure) as segregates; however, each particle contains an intermetallic compound Zn-Ni that encloses the Ni (α-fcc structure) pure phase. The Ni-α phase was then transformed into a γ-ZnNi intermetallic compound which shifts to higher values of mechanical hardness from about 60 HV to 400 HV units.

Keratinocytes Growth Using Polyvinylidenefluoride (PVDF) Fiber Mats by Electrospun

There is a growing demand for skin transplants; however, immunological incompatibility to such transplants remains as an unsolved issue. It is necessary to improve the current production methods for epidermal originated tissue. PVDF-based membranes have the potential to be used as an appropriate scaffold for skin cell growth. There are a wide range of medical applications and potential medical applications of PVDF. Keratinocytes on PVDF scaffolds had the greatest alkaline phosphatase activity and early mineralization. The results demonstrate the potential for the use of PVDF scaffolds for keratinocytes growth applications.)

A PLZT Novel Sensor with Pt Implanted for Biomedical Application: Cardiac Micropulses Detection on Human Skin

Advances in sensors for biomedical applications have been a great motivation. In this research, a PLZT (lead lanthanum zirconate titanate) novel sensor with platinum wire implanted in its longitudinal section was developed through of the synthesis process based on powder technology. The raw materials as lead (PbO), lanthanum (La2O3), zircon (ZrO2), and titanium (TiO2) were used in the formation of the chemical composition (62.8% PbO, 4.5% La2O3, 24.2% ZrO2, and 8.5% TiO2). Then, these powders were submitted to mix-mechanical milling at high energy; cylindrical samples with the implant of the platinum wire were obtained with the load application. Finally, the compacted samples were sintered at 1200°C for 2 hours, then followed by a polarization potential of 1500 V/mm at 60°C to obtain a novel sensor. The density and porosity were evaluated using the Archimedes’ principle, while the mechanical properties such as fracture toughness value and Young’s modulus were determined by indentation and ultrasonic methods, respectively. A microscopic examination was also carried out to investigate the structural properties of the material. The PLZT novel sensor is electronically arranged for monitoring the cardiac pulses through a data acquisition system. The results obtained in this research are analyzed and discussed.