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Naturalism as a literary current has been associated with Émile Zola (Paris, 1840-1902), who, after publishing the saga Les Rougon Macquart, was the main promoter of the "experimental novel", a narrative seen as a sociological experiment, to the which is not interested in projecting reality, as happened with the realistic novel. On the contrary, the objective was to identify the root of social problems based on the principles of positivism: the medium, progress, in order to collaborate in their conversion and restoration.

En el presente artículo se presenta la propuesta para la implementación de un laboratorio de redes con la aplicación de servidores virtuales, mediante de un software especializado. Para lograr esta meta se propuso hacer uso de la tecnología de virtualización. El objetivo principal es proveer un laboratorio para el desarrollo de las competencias académicas de los estudiantes a través de prácticas y configuraciones de servicios de red en un entorno controlado y seguro. Además, se pretende hacer el uso de tecnologías actuales y más utilizadas en el ambiente empresarial y laboral, con el fin de introducir a un entorno real de trabajo a los estudiantes. Se aplica una nueva metodología híbrida para poder cumplir con el objetivo del desarrollo de la propuesta, que se denominó casvim, en referencia a la Metodología Cascada propia de la ingeniería de Software y a la Metodología de Infraestructura Virtual.

This review summarizes recent advances in the development of pyrolyzed M–N–C catalysts for the oxygen reduction reaction, focusing on activity, stability, and the reactivity descriptors proposed for the rational design of pyrolyzed M–N–C catalysts. We discuss the last advances in achieving high catalytic activity and stability and the new insights into the characterization of FeN4 active sites by Mossbauer spectroscopy in combination with Density Functional Theory (DFT) calculations of the Fe–N–C catalysts. In addition, we present the different reactivity descriptors proposed in the literature for the rational design of Fe–N–C pyrolyzed materials: (i) structural descriptors determined by X-Ray Photoelectron Spectroscopy (XPS) and Mossbauer spectroscopy and (ii) the redox potential of the active center MNx.

En el tratamiento del dolor cervical se emplean equipos y técnicas que no miden la intensidad del dolor del paciente, sino que únicamente permiten observar los daños estructurales de dicha región. Sin embargo, la evaluación de éste dolor se puede llevar a cabo al analizar las variables cinemáticas de los tres movimientos de la articulación cervical: flexo-extensión, flexo-lateral y rotación. En este trabajo estudiaremos la fiabilidad de la técnica de fotogrametría, mediante el uso de una cámara de bajo costo, denominado Kinect V1. La cámara Kinect adquirirá los parámetros cinemáticos del movimiento de flexo-extensión de la articulación del cuello y, técnicas de visión artificial y de procesamiento de imágenes de profundidad/color del sensor Kinect serán empleadas para obtener las trayectorias de los marcadores anatómicos y técnicos. Se utilizará un filtro de Kalman para corregir el seguimiento continuo de las trayectorias de los marcadores técnicos y, consecuentemente, las coordenadas espaciales de cada marcador. Los datos fueron obtenidos de siete sujetos de prueba, entre hombres y mujeres, físicamente sanos. Las edades de los sujetos están comprendidas entre 17 y 40 años. Asociados a las coordenadas de cada marcador técnico, calculamos los parámetros cinemáticos de velocidad angular, aceleración angular y desplazamiento angular, para obtener los parámetros de fiabilidad y correlación entre pruebas. Esto último se realizó al analizar el error estándar medio, el índice de correlación múltiple y los índices de correlación de Pearson, empleados para análisis clínico. El alto índice de correlación entre los ensayos realizados nos permite ratificar la fiabilidad de nuestra metodología.

15 pags., 9 figs., 2 tabs., Pyrolyzed non-precious metal catalysts have been proposed as an alternative to substitute the expensive and scarce noble metal catalysts in several conversion energy reactions. For the oxygen reduction reaction (ORR), the pyrolyzed catalyst M−N−C (M: Fe or Co) presents remarkable catalytic activity in acid and alkaline media. These pyrolyzed materials show a high heterogeneity of active sites being the most active in the MNx moieties. The activity and stability of these catalysts are also conditioned by other structural parameters such as the area, the N-doping, and by the presence of metal particles. In this study, we explore the use of FeO nanoparticles as templates and as iron sources to synthesize Fe−N−C. The best performance for the ORR in acidic media was reached with the catalysts using nanoparticles covered by PANI and iron salts as the precursor, with an onset potential of 0.85 vs. RHE and a direct 4-electrons mechanism. We corroborated the use of the catalysts’ redox potential as reactivity descriptors and discussed the detrimental role of the presence of FeC metallic particles in the mechanism. Based on the experimental results, we performed DFT calculations to explore the influence of N-doped species on the electronic density of the iron centers of FeN4 active sites, and we propose a theoretical model for increasing the activity based on the distance and ratio of N-doping to iron center., This work was supported by Fondecyt Regular Project 1161117, Conicyt Scholarship 21160212, Fondecyt Postdoctoral Projects 3180509 and 3170330, and Anillo Project ACT-192175. By MICIN grant PGC2018-095642-B-I00, MCIN/AEI/10.13039/501100011033 RTI2018-095303-B-C51, by ERDF A way to making Europe, and by CISC grant 2021AEP056.

The oxygen reduction reaction (ORR) is essential for energy conversion devices such as fuel cells and metal-air batteries. The use of expensive and scarce noble metal materials to catalyze the ORR is a limitation for the massification of these energy conversion technologies. Copper molecular catalysts that mimic the active sites of metalloenzymes such as laccase are under continuous development. In this minireview, we present the strategies to increase the activity and stability of the copper catalysts for the ORR. The flexibility, lability, and electronic character of the ligands are crucial to promote the ORR. In addition, the use of polymers as backbone for multicopper catalysts and the synthesis of copper carbon-based pyrolyzed catalysts present remarkable results with promissory applications, This work has been supported by FONDECYT 11221073, FONDECYT 1221798, FONDECYT Postdoctoral Project 3170330 and Anillo Project ACT-192175

This paper provides a multicriteria evaluation model, based on the AHP methodology for the evaluation of the Circular Economy 4.0’s, which develops the metric called “Circularity indicator for urban road projects (CIROAD)”. The main contribution of this work is to provide a measurement scale specifically designed for urban road infrastructure projects. It is a useful tool to assess the degree of implementation of the principles of the Circular Economy (CE) and the Fourth Industrial Revolution (I4.0) in an integrated manner in these types of projects, generating valuable information for all stakeholders and contributing to the objective of accelerating the transition towards a Circular Economy 4.0 model in the construction industry. The model is defined with twenty-five sub-criteria and seven general criteria, which are: (1) Circular Materials; (2) Circular Design Approaches; (3) Circular Construction Approaches; (4) Circular Operation Approaches; (5) Approaches to Deconstruction and Resource Recovery; (6) Social Value Creation; and (7) Economic Performance. The developed CIROAD model was applied to three projects in the urban transport area of the Chilean Ministry of Housing and Urbanism (MINVU/SERVIU) in the Santiago Metropolitan Region (RM). In these three projects, low performance was observed in terms of CIROAD scores (between 21% and 28% of a maximum of 100%); that is, there is a significant opportunity for improvement by incorporating more circular practices in the development of projects by the studied organization. To accelerate the transition to a circular economy model in the development of its projects, it is proposed that the organization prioritize improving the following circular practices (in order of importance): (1) the design of pavements with environmental criteria; (2) preserving value; (3) conducting cost–benefit analysis (CBA) of waste management; (4) environmental declaration of materials (EPD); (5) the used of recycled materials; and (6) BIM-based design. Finally, the suggestion for the organization in charge of these projects is to use the developed CIROAD model as a tool to support decision making regarding the prioritization of its project portfolio. That is, the organization should use CIROAD to generate a ranking score for each project and allocate resources for investment in the initiatives that show the best circularity performances, as estimated by CIROAD.

Bioinspired transition-metal catalysts seek to mimic the specific active site of metalloenzymes, as the multicopper oxidase, that can efficiently reduce dioxygen to water via a complete 4-electrons mechanism at low overpotential. However, the multicopper oxidase enzymes lack stability under operando conditions, hampering their application in fuel cell electrodes. Bioinspired multicopper catalysts present a remarkable electrocatalytic activity for the oxygen reduction reaction (ORR), where the structure and electronic properties of the ligands play a fundamental role. In this work, we explore the instantaneous catalytic activity and its evolution under operando conditions of two multicopper catalysts with different ligand flexibility, pyridyl ligand (CuL1), and pyridylmethyl ligand (CuL2), by conventional electrochemical techniques and scanning electrochemical microscopy (SECM). Both catalysts present similar instantaneous electrocatalytic activity with no significant role of the ligand, but there is a change in the mechanism. While the rigidity of CuL1 reduces the dioxygen via direct 4e-, the catalyst with higher flexibility (CuL2) follows a 2e−x 2e− mechanism. The production of H2O2 as ORR byproduct evaluated by rotating ring-disk electrode (RRDE) and stability test evaluated under ORR operating conditions by SECM imaging of both catalysts demonstrated a higher decrease in catalytic activity and higher H2O2 production in CuL2 than in CuL1, which evidences a ligand structure-reactivity correlation. These results contribute to the rational design of next generation of copper catalysts and open the door to a new methodology to evaluate the activity evolution under operando conditions by SECM, This work has been supported by ECOS Sud-Chile CONICYT program (Project C17E10/170037), FONDECYT Project 1161117, FONDECYT Project 11221073, FONDECYT Postdoctoral Project 3170330, and ACT192175.

We have systematically studied the catalytic activity of a series of substituted bisphenanthroline Cu complexes adsorbed on glassy carbon electrodes for the oxygen reduction reaction (ORR) in aqueo...

5 pags., 2 figs., 2 tabs., The study of non-precious metal catalysts (NPMCs) as alternatives to platinum for oxygen reduction is crucial if the use of fuel cells is to become more widespread. Among NPMCs, pyrolyzed catalysts (Fe-N-C) are particularly promising in both basic and acid media. The characterization of active sites and the understanding of the oxygen reduction reaction (ORR) mechanism are crucial for the design of active Fe-N-C catalysts. In this study, we have tested the involvement of the metal centre in the ORR process at pH 13 for two pyrolyzed iron porphyrins. The pyrolyzed catalysts present a FeN4 active site structure similar to that of the porphyrin precursors. Regarding the mechanism, we have found evidence for the crucial role of the Fe(II) centres. There is a direct relation between the Fe(III)/(II) redox transition of the catalysts and the onset potential of the ORR, showing that the electrogeneration of Fe(II) from Fe(III)OH– controls the catalysis. The poisoning of iron centres with CN− induces a decrease in the ORR activity. However, the onset potential for H2O2 generation remains unchanged. The Tafel plots show two different slopes at high and low overpotentials. Based on these results, we propose two different mechanisms, both dependent on the redox potential of the catalysts and the FeO2 binding energy., This work was supported by Fondecyt Regular Projects 1161117,1181037. Fondecyt Postdoctoral Projects 3170330, 3180509, and Conicyt Scholar ships 1160955,21160212

En el articulo 93 N° 6 de la constitucion se consagran una accion de inaplicabilidad por inconstitucionalidad propia o concreta, en que se ejerce un control de constitucionalidad mixto, facultativo, preventivo, concreto, con efecto relativo y que tiene por objeto a las sentencias judiciales de tribunales ordinarios o especiales, y una accion de inaplicabilidad por inconstitucionalidad impropia o abstracta en que se ejerce un control de constitucionalidad concentrado, facultativo, represivo, abstracto, con efecto relativo y que tiene por objeto a los preceptos legales. En la primera el Tribunal Constitucional obra como juez correctivo de equidad constitucional; en la segunda, como legislador negativo singular.

9 pags., 6 figs., 2 tabs., Pyrolyzed non-precious metal catalysts (NPMCs) are promising materials to replace platinum-based catalysts in the cathode of the fuel cells. These catalysts present high catalytic activity both in alkaline and acid media for the oxygen reduction reaction (ORR). These catalysts are essentially heterogeneous as they can present different types of active sites. MNx structures have been proposed as the most active for the ORR, similar to those of the MN4 structures of metal porphyrins and phthalocyanines. Several parameters have been proposed as reactivity descriptors to correlate the structure of these materials with their catalytic activity, such as the amount of MNx and of pyridinic nitrogens in the graphitic structure. In this study, we have explored the metal center redox potential of the catalyst as an overall reactivity descriptor. We have investigated this descriptor for pyrolyzed and intact catalysts for the ORR in acid and basic media. We have found that for all catalysts tested, there is a linear correlation between the redox potential of the catalyst and the catalytic activity expressed as (log i)). The activity increases as the redox potential becomes more positive. The correlation gives a straight line of slope close to +0.12 V/decade which agrees with the theoretical slope proposed in a previous publication assuming the adsorbed M − O follows a Langmuir isotherm and that the redox potential is directly linked to the M − O binding energy. The Tafel plots present two slopes, at low and high overpotentials. Based on these results, we proposed two different mechanisms. The low Tafel slopes of −60 mV appear at potentials where the surface concentration of M(II) active sites is potential dependent (close to the onset potential). At higher overpotentials the surface coverage of M(II) becomes constant and the slope changes to −0.120 V/decade., This work was supported by Fondecyt Regular Projects 1161117,1181037, Fondecyt Postdoctoral Projects 3170330 and 3180509, andConicyt Scholarship 21160955.

Following previous studies where the metal-centered redox potentials of MN4 complexes are proposed as a reactivity descriptor for different electrochemical reactions, in the present work we expand this idea to a series of substituted Cu(I)-phenanthrolines adsorbed on glassy carbon electrodes as catalysts for the hydrogen peroxide reduction reaction (HPRR) in aqueous media. As the foot of the wave for HPRR on Cu-based modified electrodes is closely related to the Cu(II)/Cu(I) formal potential, we have found a linear correlation between the catalytic activity expressed as (log i)E and the E°'Cu(II)/Cu(I) redox potential of the complexes with a slope (dE°/dlogi)E close to +0.120 V dec−1, showing that the catalytic activity increases with the shift of E°'Cu(II)/Cu(I) to more positive potentials as a result of the electron-withdrawing nature of the substituents on the ligands. Moreover, the theoretical differences in the calculated chemical potentials (Δμ) of the reactive species follow a similar trend with the E°'Cu(II)/Cu(I) where a positive shift of this parameter is related with a higher Δμ and in consequence, with high catalytic activity. Furthermore, this strategy can be used for the smart design of biosensors as it was shown by the electroanalytical results.

MN 4 macrocyclic metal complexes have been studied for many years as potential catalysts for the O 2 reduction reaction (ORR) in order to replace costly Pt and Pt group metals from the cathode of fuel cells. These macrocyclic complexes lack the necessary stability over long periods of time required for fuel cell operation especially in acidic electrolytes. However, they have provided very good models for establishing reactivity descriptors. The activity plotted with the M–O binding energy describes a volcano correlation. For Mn and Fe complexes, the onset for ORR occurs at potentials very close to the M(III)/(II) redox potential of the complexes in contrast to Co complexes. In general, the more positive the M(III)/(II) redox potential, the highest the activity. This is also true for MN 4 catalysts dispersed on carbon nanotubes using different strategies. MN x catalysts obtained by pyrolysis of MN 4 complexes show higher activity and stability and are more promising for fuel cell applications. The M(III)/(II) transition is a reactivity descriptor for these materials as observed for intact MN 4 complexes.

Steel reinforcement in concrete is protected from corrosion by passivation due to the high alkalinity of the cement pore solution, but the presence of aggressive ions as Cl− could induce pitting corrosion processes thus decreasing the durability of the structure. This also occurs for prestressing concretes but the risk to suffer pitting corrosion in presence of aggressive ions, and hence stress corrosion cracking (SCC), increases due to the external mechanical load. The study of the corrosion processes by classical methods involves the determination of pitting potential (E pit) or the polarization resistance monitoring during long periods (i corr). However, the large number of parameters, which could potentially influence the determination of the E pit or the i corr values, result in a great variety of results in literature. The present study proposes a simple and reliable method to evaluate the susceptibility to suffer pitting corrosion process and stress corrosion cracking by the induction of pitting corrosion process by cyclic voltammetry. The pitting corrosion intensity is evaluated by means of the charge during the corrosion process, and related with the weight loss and the decrease of the mechanical properties of the steel under external load. The results show a linear and a volcano trend when pitting corrosion process and stress corrosion cracking are respectively evaluated.

We have compared the electrocatalytic activity of several substituted and unsubstituted Co and Fe N4-macrocyclic complexes (MN4) for the electro-reduction of oxygen with the complexes directly adsorbed on the edge plane of pyrolytic graphite or adsorbed on carbon nanotubes (CNTs). In the presence of CNTs, one order of magnitude higher surface concentrations of MN4 catalysts per geometric area unit could be adsorbed leading to a lower overpotential for the oxygen electro-reduction and activities in the same order of magnitude as the commercially available Pt/C catalysts in basic pH. From Koutecky-Levich regression analysis, the total number of electrons transferred was approximately 2 for all the Co complexes and 4 for all the Fe ones, both in the presence and in the absence of the carbon nanotubes. Furthermore, the Tafel slopes did not vary due to the presence of the CNTs and presented values in the range of -0.06 V decade

An efficient and inexpensive catalyst for the oxygen reduction reaction (ORR) is the key missing component for large-scale development of fuel cells. Bio-inspired tethered electrocatalysts could be the solution to this problematic reaction. Either unsubstituted Fe phthalocyanine (FePc) or Fe hexadecachloro-phthalocyanine (16(Cl)FePc) was anchored to carbon nanotubes (CNTs) via a pyridine axial ligand. The results show that the fifth coordination plays a major role in increasing the catalytic activity of FePc and 16(Cl)FePc for the ORR. The coordination also allows the decoupling of the metal centre from the carbon support, thus changing the geometrical and electronic structure and hindering the production of HO. The pentacoordinated catalysts were stable in acidic pH according to the rotating disk analysis, but the activity of the hexadecachloro compound was not higher than that of the unsubstituted phthalocyanine. Cl atoms reduced the coupling between O and Fe, mismatching the energy of the frontier orbitals and lowering the activity towards the reduction of O.

La cultura de innovación promueve acciones, normas, valores y actitudes estrechamente ligadas a la mejora continua y la creación de nuevos conocimientos en el marco de una cultura organizacional sustentable y, a la vez, innovadora que permita generar valor para la empresa y para el cliente. Este estudio prioriza las dimensiones que conforman la cultura de innovación de las empresas productoras de la minería de mediana escala. En base al juicio de expertos, se desarrolló un modelo utilizando la metodología multicriterio AHP para identificar las distintas dimensiones en las cuales se debe focalizar los recursos para una gestión sustentable. Los resultados demuestran que, el estilo de la dirección y las competencias y habilidades del capital humano, determinan en gran medida el potencial de innovación de las empresas así como su capacidad para establecer una sustentabilidad de tipo corporativo. Se concluye que es necesario potenciar estos factores en el sistema organizacional así como otros procesos culturales para generar concepciones creativas y una cultura innovadora. The culture of innovation promotes actions, norms, values and attitudes that are related to continuous improvement process and, also, it has an impact in the knowledge creation within a sustainable organizational culture context. These conditions can generate innovative value to the company and to the customers. This study prioritizes the elements that explain the concept behind the culture of innovation in medium-scale mining in Chile weighting these factors based on expert judgment. AHP multicriteria methodology was used in order to identify the different dimensions, components and resources that are relevant for sustainable management developed. Results demonstrate that leadership style and the competencies and skills of human capital, largely determine the innovation path of a firm as well as its ability to establish a corporate sustainability process. Conclusions suppose that it is necessary to enhance these factors inside the organizational structure along with other cultural processes in order to generate a culture of innovation.

The M(II)/(I) formal potential of MN4 macrocyclic complexes dictates their electrocatalytic activity for many reactions and L-cysteine oxidation is not an exception. In this work we review the literature related to this reaction and propose a semi-empirical model that can describe the catalytic activity of these chelates in terms of their formal potential. A correlation of log i (at constant potential) versus the M(II)/(I) formal potential for M= Fe,Co) of the catalysts gives a volcano curve. Our results clearly show that the M (II)/(I) formal potential of N 4 -macrocyclic complexes needs to be adjusted to values around -1.0 V vs. SCE to obtain the highest catalytic activity for the oxidation of L-cysteine. When comparing chelates of different metals (M= Cr, Mn, Fe, Co) of tetrasulphonated phthalocyanines only a linear correlation is obtained.

In this paper we compare the catalytic activitites of untouched metal macrocyclic and pyrolyzed catalysts for ORR in acid versusthe formal potential of the catalyst and find in general that the catalysts reported in the literature exhibiting more positive formalpotentials are more active for ORR. These trends observed could serve as a hint for the development more active non-precious metalcatalysts for fuel cells.©2012 The Electrochemical Society. [DOI: 10.1149/2.032206esl] All rights reserved.Manuscript submitted January 16, 2012; revised manuscript received April 13, 2012. Published April 27, 2012.

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