4,259 research outputs found
HRTEM and Molecular Modeling of the MoS 2-Co9 S 8 Interface: Understanding the Promotion Effect in Bulk HDS Catalysts
As environmental regulations increase, more selective transition metal sulfide (TMS) catalytic materials for hydrotreating applications are needed. Highly active TMS catalysts become more and more desirable triggering new interest for unsupported Co-promoted MoS2-based systems that have high volumetric activity as reported here. Contrary to the common observation for alumina-supported MoS2-based catalysts, we found in our previous studies with dibenzothiophene (DBT) hydrodesulfurization (HDS) that the catalytic activity is directly proportional to the increase of surface area of the sulfide phases (Co9S8 and MoS2) present in Co-promoted MoS2 unsupported catalysts. This suggests that activity is directly connected with an increase of the contact surface area between the two sulfide phases. Understanding of the nature of the possible interaction between MoS2 and Co9S8 in unsupported catalytic systems is therefore critical in order to get a more generalized overview of the causes for synergy. This has been achieved herein through the detailed characterization by XRD, XPS, and HRTEM of the highly active Co9S8/MoS2 catalyst resulting in a proposed model for a Co9S8/MoS2 interface. This model was then subjected to a DFT analysis to determine a reasonable description of the surface contact region between the two bulk phases. Modelling of the interface shows the creation of open latent vacancy sites on Mo atoms interacting with Co and formation of direct Co-Mo bonds. Strong electron donation from Co to Mo also occurs through the intermediate sulfur atom bonded to both metals while an enhanced metallic character is also found. These changes in coordination and electronic properties are expected to favor a synergetic effect between Co and Mo at the proposed localized interface region between the two bulk MoS2 and Co9S8 phases.CONACYT, Mexico 207997MRTI of UTEP, Cotton Trust UTEPMicrolectronics Research Lab of UT-Austin and Departamento de Educacion y Cultura of Gobierno del Estado de ChihuahuaMicroelectronics Research Cente
Semimetal transition in curved MoS/MoSe Van der Waals heterojunction by dispersion-corrected density functional theory
We present a theoretical study for MoS/MoSe Van der Waals heterojunction in the armchair direction, and periodicity in the y-direction, under the mechanical deformation process to explore electronic structure vs. curvature angle. Our findings reveal that the heterojunction maintains chemical stability, even under high deformation, and the bandgap of the heterojunction is inversely proportional to curvature angle; the shift from semiconductor—with a bandgap of 0.8 eV—to semimetal occurs at deformation angles as low as 5°, having a gapless material. The mentioned transition corresponds mainly to distortion of half-filled molybdenum d-orbitals and chalcogen–chalcogen p-orbitals overlapping near the Fermi level
Overview of ASDEX Upgrade results
The ASDEX Upgrade (AUG) programme is directed towards physics input to critical
elements of the ITER design and the preparation of ITER operation, as well as addressing
physics issues for a future DEMO design. Since 2015, AUG is equipped with a new pair of
3-strap ICRF antennas, which were designed for a reduction of tungsten release during ICRF
operation. As predicted, a factor two reduction on the ICRF-induced W plasma content could
be achieved by the reduction of the sheath voltage at the antenna limiters via the compensation
of the image currents of the central and side straps in the antenna frame. There are two main
operational scenario lines in AUG. Experiments with low collisionality, which comprise
current drive, ELM mitigation/suppression and fast ion physics, are mainly done with freshly
boronized walls to reduce the tungsten influx at these high edge temperature conditions. Full
ELM suppression and non-inductive operation up to a plasma current of Ip = 0.8 MA could
be obtained at low plasma density. Plasma exhaust is studied under conditions of high neutral
divertor pressure and separatrix electron density, where a fresh boronization is not required.
Substantial progress could be achieved for the understanding of the confinement degradation
by strong D puffing and the improvement with nitrogen or carbon seeding. Inward/outward
shifts of the electron density profile relative to the temperature profile effect the edge stability
via the pressure profile changes and lead to improved/decreased pedestal performance.
Seeding and D gas puffing are found to effect the core fueling via changes in a region of high
density on the high field side (HFSHD).
The integration of all above mentioned operational scenarios will be feasible and
naturally obtained in a large device where the edge is more opaque for neutrals and higher
plasma temperatures provide a lower collisionality. The combination of exhaust control
with pellet fueling has been successfully demonstrated. High divertor enrichment values of
nitrogen EN 10 have been obtained during pellet injection, which is a prerequisite for the
simultaneous achievement of good core plasma purity and high divertor radiation levels.
Impurity accumulation observed in the all-metal AUG device caused by the strong neoclassical
inward transport of tungsten in the pedestal is expected to be relieved by the higher
neoclassical temperature screening in larger devices.European Commission (EUROfusion 633053
La paz transformadora: una propuesta para la construcción participada de paz y la gestión de conflictos desde la perspectiva sociopráxica (Transformative peace: a participatory peace building and conflict management proposal from the sociopraxic perspective)
En el artículo se expone un marco epistemológico y teórico-metodológico para la ciencia de la paz y el conflicto. Esta propuesta, desarrollada desde la perspectiva sociopráxica, plantea una conceptualización del conflicto social y la paz como procesos vivos y activos cuyos principales protagonistas son los seres humanos y las redes de relaciones sociales constituidas por y constituyente de las mismos. De acuerdo con el marco enunciado, los modelos convivenciales violentadores son sustituidos por modelos convivenciales sinérgicos con los que atender las necesidades. | The article presents an epistemological, theoretical/methodological framework for peace and conflict. This proposal, developed from the sociopraxic perspective, raises a conceptualization of social conflict and peace as living and active processes whose main protagonists are human beings and the networks of social relations constituted by and constituent of them. In accordance with the proposed framework, convivial models responsible for violence are replaced by synergic convivial models with which to attend needs
Influence of Teaching Style on Physical Education Adolescents’ Motivation and Health-Related Lifestyle
According to various WHO reports in 2018, a large number of adolescents worldwide are either overweight or obese. This situation is the result of not following a healthy and balanced diet, combined with a lack of practice of physical activity. In this sense, Physical Education classes could help to solve the problem. The present study seeks to analyze the relationship between the role of the teacher in relation to the structural dimensions of the PE teaching environment and the basic psychological needs and self-motivation of adolescents as determinants of their behaviors related to eating habits and the practice of physical activity. A total of 1127 secondary school adolescents between the ages of 13 and 18 participated in this study. Questionnaires were used: Perceived Autonomy Support Scale, Psychologically Controlling Teaching Scale, Basic Psychological Needs in Physical Education, Frustration of Psychological Needs in PE context, Physical Activity Class Satisfaction Questionnaire, Perceived Locus of Causality Revised, and WHO’s Global school-based student health survey. A structural equations model was elaborated to explain the causal relationships between the variables. The results showed that autonomy support positively predicted the three structural dimensions of PE classes, while, in contrast, they were negatively predicted by psychological control. The three structural dimensions positively predicted the satisfaction of psychological needs and negatively predicted the thwarting of psychological needs. Self-determined motivation was positively predicted by the satisfaction of psychological needs and negatively predicted by the thwarting of psychological needs. Finally, self-determined motivation positively predicted healthy eating habits and the practice of physical activity and negatively predicted unhealthy eating habits. Certainly, the results obtained in this study support the postulates of the self-determination theory, demonstrating the predictability of PE class context towards the adoption of healthy lifestyle habits, such as a proper diet and the regular practice of physical activity
Validation of the Satisfaction Scale of Basic Psychological Needs in Physical Education with the Incorporation of the Novelty in the Spanish Context
The purpose of the study was to validate to the physical education context, the Spanish version of the Scale of the Satisfaction of Psychological Needs toward the Physical Education classes of Menéndez and Fernández-Rio, with the incorporation of the novelty, since they contemplated its inclusion. In this study, 1444 students participated (mean = 15.34, standard deviation = 1.12) from several schools in Almeria. To analyze the psychometric properties of the scale, several analyses were carried out. The results offered support for both the four-factor structure and the higher-order model called satisfaction. The analysis of invariance with respect to gender showed that the factor structure of the questionnaire was invariant. The Cronbach alpha values were higher than 0.70 in the subscales. The results of this study demonstrated the reliability and validity of the Scale of the Satisfaction of Psychological Needs, with the incorporation of novelty in the Spanish context of Physical Education
Market orientation and the synergistic effect of mediating and moderating factors on performance : the case of the fashion cluster
It is commonly accepted that a market-oriented behaviour has a positive impact on organizational performance. This study provides additional support for the classical relationship between market orientation and organizational performance and goes further by not only including in the model the mediating role of both the organizational learning and organizational innovation, but also examining the potential moderating impact of the environmental conditions in the previous relationship.The analysis is based on data collected from a sample of 130 Portuguese SME operating in the fashion cluster. Implications and future research questions based on the findings are offered at the conclusion of the paper
Determining the Electronic Structure and Thermoelectric Properties of MoS₂/MoSe₂ Type‐I Heterojunction by DFT and the Landauer Approach
The electronic structure and thermoelectric properties of MoX2 (X = S, Se) Van der Waals heterojunctions are reported, with the intention of motivating the design of electronic devices using such materials. Calculations indicate the proposed heterojunctions are thermodynamically stable and present a band gap reduction from 1.8 eV to 0.8 eV. The latter effect is highly related to interactions between metallic d-character orbitals and chalcogen p-character orbitals. The theoretical approach allows to predict a transition from semiconducting to semi-metallic behavior. The band alignment indicates a type-I heterojunction and band offsets of 0.2 eV. Transport properties show clear n-type nature and a high Seebeck coefficient at 300 K, along with conductivity values (σ/τ) in the order of 1020. Lastly, using the Landauer approach and ballistic transport, the proposed heterojunctions can be modeled as a channel material for a typical one-gate transistor configuration predicting subthreshold values of ≈60 mV dec−1 and field–effect mobilities of ≈160 cm−2 V−1 s−1
CONTEXTO DE LA INNOVACIÓN EN LA RURALIDAD ESPAÑOLA: EL CASO DEL ARROZAL ANDALUZ
This article presents a descriptive statistical analysis on the relationship of rice growing and the retention of the rural population on the territory in Spain. Data provided by FAOSTAT (Food and Agriculture Organization of the United Nations), the National Statistics Institute (Instituto Nacional de
Estadística, INE) and the Statistics and Cartography Institute of Andalusia were used. Results show that technological and non-technological innovation based on sustainable production has facilitated the increase in yield of paddy rice production, avoiding processes of rural depopulation in the municipalities of study
ANÁLISIS COMPARATIVO DE CONSUMIDORES DE VERDURAS Y FRUTAS ECOLÓGICAS EN ESPAÑA Y PORTUGAL
Presently, new patterns of food consumption associated to the so-called organic foods have been detected. The spread of post-materialist values, ecological awareness, environmental conservation, as well as the recent economic crisis that has impacted most European countries have fostered the emergence of new forms of consumption of organic products based on a model of sustainable production. In this context, the production and consumption of organic vegetables and fruits proves to be a strategy for quality in food consumption and also as a way of saving in the acquisition of fresh and healthy foods. The following scientific contribution makes a comparative descriptive statistical study of the sociodemographic characteristics of the different types of consumers of organic fruits and vegetables in Spain and Portugal. A description of the pro-environment practices in this typology of consumers is also shown. We resort to a quantitative strategy through the use of data that belongs to the ISSP Environment (2010, Portugal) and ISSP (2010, Spain) surveys. The technique used is the bivariate analysis and the tree segmentation analysis through the CHAID algorithm. The main results show the influence of education, income and environment in the characterization of the different types of consumers of organic fruits and vegetables in Spain and Portugal
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