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We used density functional theory calculation (DFT) to optimize the crystal structure of Fe doped Li3SO at different concentrations. Using the relaxation method, the optimized lattice parameters were obtained, and the stability of the doped systems was analyzed in comparison with pure host material. The results show that Fe doping can significantly alter the structural and optical properties of the antipervskite. And that the introduction of delocalized iron impurities induces changes in the lattice parameters, electron densities and energy gaps of Li3SO, which can have an impact on the absorption and emission properties of electromagnetic radiation in the visible light range. Also, it was observed that the concentration of Fe doping influences the structural and optical properties, suggesting that controlled Fe doping can be a strategy to tune the physical properties of this materials for better use in optoelectrical applications.

The theoretical and analytical models for studying the mechanical behavior of composite materials have a great importance due to the innumerable applications in new technological developments. The use of these models requires a field of knowledge in the elastic properties of composite materials. In this paper, an inverse method is applied to obtain the average elastic constants of orthotropic composite laminates and the constants of orthotropic plies. The method uses the experimental strain analysis and the constitutive models obtained by applying classical laminate theory to three laminate composite materials formed by the orthotropic plies of reinforced epoxy resin with glass. In addition, through experimental axial loading tests and the state of strain measuring with strain gages, the global stresses and the elastic constant averages as well as the orthotropic constants of plies are determined. Finally, these elastic constants show consistency when evaluated.

To assess the ergonomic risk level in work systems involving tasks performed with hands or fingers, it is necessary to know the exerted triaxial forces. To address this need, a prototype of a triaxial load cell based on principles of linear elasticity theory and mechanical problems of torsion, bending and axial load is presented. This work includes an analytical strain model for each instrumented point and its solution regarding the applied force to a triaxial load cell. The proposed load cell was calibrated and validated by performing different static experimental tests. As a case study, the applied force in three directions while the thumb activates a cigarette lighter was measured. Triaxial forces and resultant forces were obtained and compared with the parameter of 10 N established by the ergonomic standards as reference values for pressing down with the thumb, finding that the applied forces in eight tests were 23.73 N, 43.51 N, 12.69 N, 14.50 N 20.35 N, 21.67 N, 39.74 N and 46.02 N, exceeding the reference values and establishing a direct relationship with Quervain syndrome. In conclusion, the developed load cell is a valid and reliable alternative to measure many forces that cannot be obtained with commercial devices, allowing the level of ergonomic risk to be determined with great precision.

Quaternions are used in various applications, especially in those where it is necessary to model and represent rotational movements, both in the plane and in space, such as in the modeling of the movements of robots and mechanisms. In this article, a methodology to model the rigid rotations of coupled bodies by means of unit quaternions is presented. Two parallel robots were modeled: a planar RRR robot and a spatial motion PRRS robot using the proposed methodology. Inverse kinematic problems were formulated for both models. The planar RRR robot model generated a system of 21 nonlinear equations and 18 unknowns and a system of 36 nonlinear equations and 33 unknowns for the case of space robot PRRS; both systems of equations were of the polynomial algebraic type. The systems of equations were solved using the Broyden–Fletcher–Goldfarb–Shanno nonlinear programming algorithm and Mathematica V12 symbolic computation software. The modeling methodology and the algebra of unitary quaternions allowed the systematic study of the movements of both robots and the generation of mathematical models clearly and functionally.

This paper presents a methodological scheme to obtain the maximum benefit in occupational health by attending to psychosocial risk factors in a company. This scheme is based on selecting an optimal subset of psychosocial risk factors, considering the departments’ budget in a company as problem constraints. This methodology can be summarized in three steps: First, psychosocial risk factors in the company are identified and weighted, applying several instruments recommended by business regulations. Next, a mathematical model is built using the identified psychosocial risk factors information and the company budget for risk factors attention. This model represents the psychosocial risk optimization problem as a Multidimensional Knapsack Problem (MKP). Finally, since Multidimensional Knapsack Problem is NP-hard, one simulated annealing algorithm is applied to find a near-optimal subset of factors maximizing the psychosocial risk care level. This subset is according to the budgets assigned for each of the company’s departments. The proposed methodology is detailed using a case of study, and thirty instances of the Multidimensional Knapsack Problem are tested, and the results are interpreted under psychosocial risk problems to evaluate the simulated annealing algorithm’s performance (efficiency and efficacy) in solving these optimization problems. This evaluation shows that the proposed methodology can be used for the attention of psychosocial risk factors in real companies’ cases.

We fabricated a ZnO-based Schottky diode via the deposition of a ZnO film co-doped with Al + In (4 at.%) on a boron-doped ZnO film (8 at.%). Each film was prepared by layering coatings (2, 3, 4, and 5 layers) by sol–gel deposition. The finished diode consists of the combination of seven layers (each layer with a thickness of around 90 nm). The total thickness of the diode is around 700 nm. The films were previously studied and structurally, optically and electrically characterized. Additionally, for comparative purposes, we fabricated and characterized un-doped ZnO films. The energy bandgap values of the un-doped films, mono-doped films, and co-doped films were 3.30 eV, 3.32 eV, and 3.34 eV, respectively. X-ray diffraction did not show traces of different phases from hexagonal Wurtzite-type ZnO. The electrical resistivity values obtained were 386, 4.44 × 104, and 3.37 Ω-cm, respectively. The junction diodes were built by depositing layers of the high-resistivity material (ZnO:B) on ITO conductor substrates, followed by the deposition of layers of the low-resistivity material (ZnO:Al + In) on the same substrate. The I–V characteristics of these diodes were analyzed in terms of the number of the deposited layers (or the different thickness of the films). The results show a Schottky-type behavior in the dark and under light (spot lamp of 160 W), which is controlled by the thickness of the resistive layer. From the I–V curves, the characteristic parameters including barrier height, ideality factor, and series resistance were calculated. From the transconductance (gm=dI/dV), it was possible to identify the presence of all the layer–layer interfaces. Depending on the thickness of the resistive ZnO:B film, we found a region of negative differential resistance and a region of visible light detection.

Metal clusters stabilized in zeolites have emerged as promising candidates for optoelectronic applications due to their remarkable luminescent properties. These optical properties have been exploited to develop fast and highly sensitive methods for optical sensing in environmental monitoring. However, to date, these materials have not been proposed as a detection method based on their luminescent response for sensing toxic metal ions. In this report, we synthesized luminescent lead (Pb) clusters into the cavities of synthetic F9-NaX zeolites, which were used as scaffolds to confine and detect Pb 2+ ions in water through a fluorimetric mode. These Pb-F9 samples display an intense cyan emission in dehydrated form. Also, a correlation between the luminescence intensity of the materials and the lead loadings was observed, obtaining a low limit of detection of 1.248 ppb and a limit of quantification of 3.782 ppb. The results clearly demonstrate the potential of luminescent lead-exchanged F9 zeolites as one-step method for lead monitoring in water using a rapid and low-cost strategy.

We used density functional theory calculation (DFT) to optimize the crystal structure of Fe doped Li 3 SO at different concentrations. Using the relaxation method, the optimized lattice parameters were obtained, and the stability of the doped systems was analyzed in comparison with pure host material. The results show that Fe doping can significantly alter the structural and optical properties of the antipervskite. And that the introduction of delocalized iron impurities induces changes in the lattice parameters, electron densities and energy gaps of Li 3 SO, which can have an impact on the absorption and emission properties of electromagnetic radiation in the visible light range. Also, it was observed that the concentration of Fe doping influences the structural and optical properties, suggesting that controlled Fe doping can be a strategy to tune the physical properties of this materials for better use in optoelectrical applications.