Microalgae, including cyanobacteria, represent a valuable source of natural compounds that have remarkable bioactive properties. Each microalga species produces a mixture of antioxidants with different amounts of each compound. Three aspects are important in the production of bioactive compounds: the microalga species, the medium composition including light supplied and the photobioreactor design, and operation characteristics. In this study, the antioxidant content and productivity performance of four microalgae were assessed in batch and continuous cultures. Biomass productivity by the four microalgae was substantially enhanced under continuous cultivation by 5.9 to 6.3 times in comparison with batch cultures. The energetic yield, under the experimental conditions studied, ranged from 0.03 to 0.041 g biomass kJ⁻¹. Phenols, terpenoids, and alkaloids were produced by Spirulinaplatensis, Isochrysisgalbana, and Tetraselmissuecica, whereas tocopherols and carotenoids were produced by the four microalgae, except for phycocyanin and allophycocyanin, which were only produced by S. platensis and Porphyridiumcruentum. The findings demonstrate that the continuous cultivation of microalgae in photobioreactors is a convenient method of efficiently producing antioxidants.

This paper evaluates the biodiesel produced by a biodiesel plant located in the Mexican Centre for Cleaner Production (CMP + L by its acronym in Spanish) of the National Polytechnic Institute of Mexico. Pollutant emissions from two types of engines were studied: a low power monocylinder engine and a 30-kW electric generator diesel engine. The tests were performed with the following blends: B5, B10, B15, B20, B30, B40, and B50. Parameters such as carbon monoxide, nitrogen oxide, hydrocarbons, and combustion efficiency were analyzed, as well as sulfur dioxide, oxygen, and combustion temperatures. It was demonstrated that NOx increases as the percentage of biodiesel increases, while CO decreases slightly using the monocylinder engine. In the case of the electric generator diesel engine, the B5 mixture had the highest trend for NOx and the lowest trend for CO. Likewise, combustion efficiency was found to be severely affected by the biodiesel blends, i.e., from B5 to B20. An analytical study and experimental thermography tests of the combustion process with biodiesel blends were carried out, and the technical problems of operation when incorporating biodiesel blends are presented.

This work presents a design for an automatized multiposition dynamic wheelchair used to transport quadriplegic patients by reconfiguring a manual wheelchair structure. An electric actuator is attached to a four-bar mechanism fixed to each side of a wheelchair’s backrest to reach multiposition. The entire device is actuated through a PID controller. An experimental test is carried out in a simplified wheelchair structure. Finally, the structure of the wheelchair is evaluated through the Dynamic analysis and Finite Element Method under the payload computed with the most critical position reached by the mechanism.

A breakthrough in peritoneal dialysis (PD) therapy occurred in 1977 with the development of continuous ambulatory peritoneal dialysis (CAPD). Its simplicity, low cost, and ease with which CAPD could be performed on patients at home contributed to the popularity of this procedure. However, there is a need for continuous improvement in building optimal systems for incident chronic kidney disease (CKD) patients. This research showed the design and construction of a simplified prototype of low-cost automated peritoneal dialysis (APD) equipment that meets international standards to automatically regulate infusion and fluid drainage in and out of a patient with low margins of error. Experimental tests allowed the adjustment of the RPM values concerning the flow rate provided. In addition, thanks to the pressure sensor, it was possible to observe a fluctuation ranging from 9 to 13 kPa, which is within the permissible average specified in the catalogs of medical instruments and equipment. Furthermore, a turbidity sensor was added to decrease the possibility of presenting peritonitis. The results showed absolute values of flow, angular velocity, and pressure that it could deliver for use in APD therapies. Finally, the construction of the APD equipment is presented generally, showing the electronic and mechanical components that constitute it.

Interspinous spacers are a minimally invasive surgical device for treating degenerative lumbar diseases, limiting spinal extension, and decreasing pressures within the disc and facets, relieving symptoms caused by lumbar spinal stenosis. This work uses the finite element method to calculate the stresses and deformations of an interspinous spacer with steel wire clamping. The cables also provide an easier way to set up the device. The reconstruction of the model was undertaken by computerized tomography, considering a person with average Mexican height (1.64 m) and a mass index grade of 2 (108 kg). The maximum movements reported in the literature were used for the range of motion. The interspinous spacer increases in a ratio of 2.7 times the stresses. Still, these stresses are generated in the prosthesis, which causes the vertebrae to be relieved since the forces and pressures are reduced. Deformations decrease by 53% with the reduction of the range of motion. Therefore, the prosthesis provides excellent stability for the vertebrae.