Oh, Lazarus…Whom God Has Helped, WALA KA BANG HIYA!

Art as a means and a vehicle towards a higher form of consciousness, and state of awareness to communicate complex issues and a way of healing. Within the context of the decolonization process

Mechanical models in computational form finding of bending-active structures

[EN] This article reviews the different aspects involved in computational form finding of bending-active structures based on the dynamic relaxation technique. Dynamic relaxation has been applied to form-finding problems of bending-active structures in a number of references. Due to the complex nature of large spatial deformations of flexible beams, the implementation of suitable mechanical beam models in the dynamic relaxation algorithm is a non-trivial task. Type of discretization and underlying beam theory have been identified as key aspects for numerical implementations. References can be classified into two groups depending on the selected discretization: finite-difference-like and finite-element-like. The first group includes 3- and 4-degree-of-freedom implementations based on increasingly complex beam models. The second gathers 6-degree-of-freedom discretizations based on co-rotational three-dimensional Kirchhoff¿Love beam elements and geometrically exact Reissner¿Simo beam elements. After reviewing and comparing implementation details, the advantages and drawbacks of each group have been discussed, and open aspects for future work have been pointed out.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The financial support from the Spanish Ministry of Economy and Competitiveness through grant BIA2015-69330-P (MINECO) is gratefully acknowledged.Lazaro, C.; Bessini-Muñoz, JG.; Monleón Cremades, S. (2018). Mechanical models in computational form finding of bending-active structures. International Journal of Space Structures. 33(2):86-97. https://doi.org/10.1177/0266351118794277S869733

A form-finding method based on the geometrically exact rod model for bending-active structures

[EN] In the field of bending-active structures, the complexity of finding beforehand the equilibrium configuration and the non-linearity of the structural response are main issues during the conceptual phase. The use of tools based on classical form-finding procedures as dynamic relaxation is the main trend today; different mechanical models with 3, 4 or 6 degrees of freedom have been implemented for modelling the bending effect. However, there is a well-established class of mechanical models which has been specifically designed to reproduce the behaviour of very flexible structures and has not been used so far in form-finding of bending-active structures. These are derived from the so-called geometrically exact (or Reissner-Simo) beam theory, and they are able to treat arbitrarily large rotations and displacements. In this paper, we present the development of a form-finding tool based on Reissner-Simo¿s theory and the dynamic relaxation method, in order to find the static equilibrium of the system. The choice of form-finding parameters as the target curve length and the kinematic constraints at beam ends will determine the shape of the final structure in the `design-oriented¿ process. Several numerical examples on a range of structures are tested to validate the formulation.The financial support from the Spanish Ministry of Economy and Competitiveness through grant BIA2015-69330-P (MINECO) is gratefully acknowledged.Bessini-Muñoz, JG.; Lazaro, C.; Monleón Cremades, S. (2017). A form-finding method based on the geometrically exact rod model for bending-active structures. Engineering Structures. 152:549-558. https://doi.org/10.1016/j.engstruct.2017.09.045S54955815

Gestión de talento humano y el desempeño laboral de los trabajadores de la empresa el Tumi 2022

La investigación que se realizó la cual parte del objetivo de determinar la relación que se da entre entre la gestión del talento humano y el desempeño laboral de los trabajadores de la empresa el Tumi, 2022, metodológicamente fue de enfoque cuantitativo, de diseño no experimental en el cual se trabajó con una muestra conformada por 80 trabajadores a los cuales se les encuesto aplicándoles un instrumento que previamente han pasado por procesos de validación por juicio de expertos y de confiabilidad mediante el estadístico de Alpha de Cronbach. Los resultados procesados permitieron concluir que existe relación significativa entre la gestión del talento humano y el desempeño laboral de los trabajadores de la empresa el Tumi, 2022, al tenerse que el valor de p= ,000 < 0,05 y con un valor de Rho Spearman fue de =,984. Por lo que se concluye que existe una influencia entre la gestión del talento humano y el desempeño labora

Evaluación de las patologías del pavimento flexible del tramo Marcará hasta desvío Ullmay del Centro Poblado Vicos, Carhuaz, 2021

El presente trabajo de estudio se realizó en el distrito de Marcará en la carretera de Marcará al Centro Poblado Vicos, teniendo como población 4.5km para la obtención del índice de condición del pavimento. Esta investigación tiene como objetivo general determinar el índice de condición superficial del pavimento flexible del tramo Marcará hasta desvío Ullmay del Centro Poblado Vicos, aplicando el método Pavement Condition Index (PCI). Tras la obtención de los resultados se propusieron alternativas de rehabilitación, mantenimiento preventivo y conservación del mismo para alargar la vida útil. Como resultado se obtuvo 11 clases de daños de los 19 que se tiene según la norma ASTM D 6433, de los cuales en la UM-03 y UM-06 se encontró los daños de Piel de Cocodrilo y Desprendimiento de Agregados de buena consideración los cuales necesitan una intervención inmediata. En conclusión, se tiene que en la Unidad de Muestra 03 (UM-03) se necesita realizar trabajos de sobrecarpeta, en la Unidad de Muestra 06 (UM-06) se necesita realizar trabajos de reconstrucción previo un estudio y diseño estructural del pavimento flexible, en general en toda la longitud considerado para el estudio se requiere la limpieza general de las cunetas por ser una zona de lluvias y presentar sedimentos

Shape generation of bending-active braced arches based on elastica curves

[EN] The active bending concept provides a new perspective for a well-established structural type which has been used at various scales: the beam-string, consisting of a beam with an attached lower tie in tension and bracing struts balancing the forces between them. The idea goes back to the gutter beams of the Crystal Palace and has been widely used to the present for large-scale structures. When a slender beam is used, the tension in the tie induces curvature in the beam and increases the structural depth of the system; this opens new formal possibilities and results in lightweight structures at the expense of increasing their overall flexibility. Systems of this kind fall within the realm of active bending. We name them bending-active braced arches. The target shape of the system follows the tensioning process and needs to be pre-determined by means of a specific analysis, typically involving dynamic relaxation or optimization-based methods. In this paper, we propose an analytical method to generate shapes for bending-active braced arches. It assumes that each segment of the activated rod between deviators behaves as a segment of elastica; this enables the use of closed-form expressions to evaluate the shape and induced stress level in the active member. Taking advantage of this idea, it is possible to devise a procedure to carry out the shaping process in a sequential way by adequately choosing the design parameters. When alternative choices for the parameters are selected, the problem becomes non-linear and can be solved using suitable techniques. Some examples with different design constraints have been reproduced to illustrate the possibilities of the method.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness through grant BIA2015-69330-P (MINECO).Bessini, J.; Monleón Cremades, S.; Casanova Colón, J.; Lazaro, C. (2021). Shape generation of bending-active braced arches based on elastica curves. Journal of the International Association for Shell and Spatial Structures. 62(2):138-152. https://doi.org/10.20898/j.iass.2021.016S13815262

Magnetism and multiferroic properties at MnTiO3 surfaces: A DFT study

The present study illustrates how density functional theory calculations can rationalize the surface structure and magnetism for the low-index (1 1 0), (1 0 1), (1 0 0), (0 0 1), (1 1 1), and (0 1 2) surfaces of MnTiO3. A simple procedure, without surface reconstructions or chemical adsorptions in which the stability, magnetism and the morphological transformations is presented in detail to clarify the control of their multiferroic nature. The surface stability was found to be controlled by the octahedral [MnO6] and [TiO6] clusters formed by the Mn2+ and Ti4+ cations - i.e., their local coordination at the surfaces, respectively- with nonpolar (1 1 0) being the most stable. Enhanced superficial magnetism was found for (0 1 2), (0 0 1), and (1 1 1) surfaces in agreement with the more undercoordinated [TiOn]′ and [MnOn]• complex clusters at the surface plane. Our calculation suggests the existence of magnetic [TiOn]′ species for unstable (0 0 1) and (1 1 1) surfaces, explained by the unusual crystal-field associated with the surface environment. The crystal morphology has been predicted to determine the most likely terminations to be present as well as the intrinsic magnetization density associated with morphologies. Moreover, the (0 0 1) surface plane plays a key role in the enhancement of the magnetic properties for shape-oriented MnTiO3 nanoparticles, suggesting a superior magnetoelectric coupling due to the presence of uncompensated spins and polar distortions perpendicular to the surface plane

A DFT investigation of the role of oxygen vacancies on the structural, electronic and magnetic properties of ATiO3 (A = Mn, Fe, Ni) multiferroic materials

In order to achieve deep insight into the multiferroic behavior and electronic properties of intrinsic oxygen vacancies in ATiO3 (A = Mn, Fe, Ni), first-principles calculations based on hybrid density functional theory were carried out for bulk and non-polar (110) surface models. We found that the formation of an oxygen vacancy is accompanied by structural and electronic disorders in the constituent clusters of [TiO6] and [AO6] in ATiO3, that become [TiO5] and [AO5], respectively. This perturbation contributes to the generation of intermediary energy levels in the band gap region, thus narrowing the required excitation energy. In addition, the remaining electrons are mainly trapped in the empty 3d orbitals of the Ti cations neighboring the oxygen vacancy, generating [TiO5] 0 (3d1 ) that mediates an antiferromagnetic to ferromagnetic transition in MnTiO3 and FeTiO3 materials. In particular, MnTiO3 surfaces show exposed [TiO4] 0 species that are responsible for its half-metallic behavior. The present work provides compelling evidence that controlling oxygen vacancies can be a valuable strategy to tailor the multiferroic properties of ATiO3 materials

Colostomía endoscópica percutánea como tratamiento de un vólvulo de sigma recidivante en paciente casi centenario

Presentamos el caso de un varón de 96 años, institucionalizado, con deterioro cognitivo avanzado y sin intervenciones quirúrgicas previas, que ingresa por vólvulo a nivel de sigma. Tras realizar descompresión endoscópica con éxito y sin incidencias, el paciente presentó dos recidivas más en las siguientes 76 horas que requirieron nueva descompresión. Tras presentar nuevo episodio y desestimar cirugía por importante comorbilidad, se decide la realización de una colostomía endoscópica percutánea mediante la técnica habitual de colocación de una gastrostomía. El manejo inicial del vólvulo de sigma consiste en la descompresión endoscópica, siendo su recurrencia muy frecuente. El tratamiento definitivo es la sigmoidectomía, que suele implicar un elevado riesgo quirúrgico en pacientes de edad avanzada y comorbilidad asociada. La colostomía endoscópica percutánea podría suponer una alternativa eficaz y segura en el manejo del vólvulo de sigma en el paciente senil, con importante comorbilidad y por lo tanto no candidato a cirugía

Sulfanilic acid-modified chitosan mini-spheres and their application for lysozyme purification from egg white

A cation exchange matrix with zwitterionic and multimodal properties was synthesized by a simple reaction sequence coupling sulfanilic acid to a chitosan based support. The novel chromatographic matrix was physico-chemically characterized by ss-NMR and ζ potential, and its chromatographic performance was evaluated for lysozyme purification from diluted egg white. The maximum adsorption capacity, calculated according to Langmuir adsorption isotherm, was 50.07 ± 1.47 mg g-1 while the dissociation constant was 0.074 ± 0.012 mg mL-1 . The process for lysozyme purification from egg white was optimized, with 81.9% yield and a purity degree of 86.5%, according to RP-HPLC analysis. This work shows novel possible applications of chitosan based materials. The simple synthesis reactions combined with the simple mode of use of the chitosan matrix represents a novel method to purify proteins from raw starting materials.Fil: Hirsch, Daniela Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; ArgentinaFil: Baieli, María Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; ArgentinaFil: Urtasun, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; ArgentinaFil: Lazaro Martinez, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; ArgentinaFil: Glisoni, Romina Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; ArgentinaFil: Miranda, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; ArgentinaFil: Cascone, Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; ArgentinaFil: Wolman, Federico Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; Argentin