Experimental and Theoretical Studies of Hyperthermal N + O2 Collisions Caracciolo, Adriana; San Vicente Veliz, Juan Carlos; Lu, Dandan ...
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
10/2023, Letnik:
127, Številka:
42
Journal Article
Recenzirano
The dynamics of hyperthermal N(4S) + O2 collisions were investigated both experimentally and theoretically. Crossed molecular beams experiments were performed at an average center-of-mass (c.m.) ...collision energy of ⟨E coll⟩ = 77.5 kcal mol–1, with velocity- and angle-resolved product detection by a rotatable mass spectrometer detector. Nonreactive (N + O2) and reactive (NO + O) product channels were identified. In the c.m. reference frame, the nonreactively scattered N atoms and reactively scattered NO molecules were both directed into the forward direction with respect to the initial direction of the reagent N atoms. On average, more than 90% of the available energy (⟨E avl⟩ = 77.5 kcal mol–1) was retained in translation of the nonreactive products (N + O2), whereas a much smaller fraction of the available energy for the reactive pathway (⟨E avl⟩ = 109.5 kcal mol–1) went into translation of the NO + O products, and the distribution of translational energies for this channel was broad, indicating extensive internal excitation in the nascent NO molecules. The experimentally derived c.m. translational energy and angular distributions of the reactive products suggested at least two dynamical pathways to the formation of NO + O. Quasiclassical trajectory (QCT) calculations were performed with a collision energy of E coll = 77 kcal mol–1 using two sets of potential energy surfaces, denoted as PES-I and PES-II, and these theoretical results were compared to each other and to the experimental results. PES-I is a reproducing kernel Hilbert space (RKHS) representation of multireference configurational interaction (MRCI) energies, while PES-II is a many-body permutation invariant polynomial (MB-PIP) fit of complete active space second order perturbation (CASPT2) points. The theoretical investigations were both consistent with the experimental suggestion of two dynamical pathways to produce NO + O, where reactive collisions may proceed on the doublet (12A′) and quartet (14A′) surfaces. When analyzed with this theoretical insight, the experimental c.m. translational energy and angular distributions were in reasonably good agreement with those predicted by the QCT calculations, although minor differences were observed which are discussed. Theoretical translational energy and angular distributions for the nonreactive N + O2 products matched the experimental translational energy and angular distributions almost quantitatively. Finally, relative yields for the nonreactive and reactive scattering channels were determined from the experiment and from both theoretical methods, and all results are in reasonable agreement.
Experimental and Theoretical Studies of Hyperthermal N + O 2 Collisions Caracciolo, Adriana; San Vicente Veliz, Juan Carlos; Lu, Dandan ...
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
10/2023, Letnik:
127, Številka:
42
Journal Article
School climate is related to a wide variety of positive results at the school level; however, its relationship with the construct of values has received little attention, despite being a key variable ...in the development of personality. This study aimed to examine the direct and indirect relationships between school climate, attitudes towards authority, and values. The participants in this study were 2683 students (51.2% men and 48.8% women) from 32 schools aged between 12 and 20 years (M = 15.78 years, SD = 1.35). Two models of structural equations were estimated, and the model that best fit the data confirmed that school climate was indirectly related to values through attitudes towards authority. The reciprocal and interactive relationships between school climate, attitudes towards authority, and values are also discussed.
The prediction of product translational, vibrational, and rotational energy distributions for arbitrary initial conditions for reactive atom + diatom collisions is of considerable practical interest ...in atmospheric re-entry. Because of the large number of accessible states, determination of the necessary information from explicit (quasi-classical or quantum) dynamics studies is impractical. Here, a machine-learned (ML) model based on translational energy and product vibrational states assigned from a spectroscopic, ro-vibrational coupled energy expression based on the Dunham expansion is developed and tested quantitatively. All models considered in this work reproduce final state distributions determined from quasi-classical trajectory (QCT) simulations with R 2 ∼ 0.98. As a further validation, thermal rates determined from the machine-learned models agree with those from explicit QCT simulations and demonstrate that the atomistic details are retained by the machine learning which makes them suitable for applications in more coarse-grained simulations. More generally, it is found that ML is suitable for designing robust and accurate models from mixed computational/experimental data which may also be of interest in other areas of the physical sciences.
School climate is a highly relevant variable that is associated with a series of positive results. However, there are still few studies that have statistically modelled the simultaneous influence of ...structural variables at the school level on the individual perception of the school climate and identification. This study had two objectives: (1) Identify school climate and school identification profiles at the individual and school levels. (2) Relate school climate and school identification profiles to factors located at the individual and school levels. The participants were selected from a probabilistic and stratified sample, n = 2070 adolescents (40.6% men, 59.4% women), aged between 13 and 18 years (M = 14.64, SD = 0.718), from 28 secondary schools in Chile. The results allowed us to identify four clusters at the student level and two classes of school climate at the school level. The explanatory factors at the individual level were Cognitive engagement (p < 0.001), Academic Expectations (p < 0.001), Positive Attitude to Authority (p < 0.001) and Family Conflict (p < 0.001). The explanatory factor at the school level was the school vulnerability index (p = 0.031). Finally, the explanatory effects of factors at individual and school levels on school climate are theoretically discussed.
College dropout proves to be a critical problem in undergraduate programs that directly affects students and the related community, due to direct economic losses and significant social costs. This ...article addresses a systematic review of the literature on predictors of student dropout intention in higher education, focusing on scientific production in Q1 and Q2 journals from 2018 to 2023, performing a bibliometric review and analyzing the available empirical and theoretical data on the phenomenon of college dropout intention and its affecting factors. The bibliometric results and those related to predictors of dropout intention introduced in previous studies are presented. The largest number of researchers studying this phenomenon are from Germany, however, the United Kingdom is the country with the largest number of publications. Previous research can be grouped into two categories: studies analyzing psychological factors of dropout intention and those related to academic and social integration.
Entre las múltiples variables que condicionan el rendimiento en pruebas de natación resalta la fuerza explosiva y la potencia, ambos predictores confiables de la velocidad del nadador. El objetivo ...del presente estudio fue determinar la relación de la fuerza, potencia y variables antropométricas con el tiempo mínimo en nadadores jóvenes. La muestra estuvo constituida por 27 nadadores de Santiago de Chile, 14 de sexo masculino (51,9%) y 13 de sexo femenino (48,1%), con edades entre 13 y 21 años. Los datos de antropometría se obtuvieron con el protocolo ISAK, utilizando una balanza digital Tanita modelo HD 357 y el kit Rosscraft Centurion. Para medir la altura de salto se utilizó la plataforma de contacto DmJump®. La medición de fuerza a través del press banco, prensa horizontal y pull down se llevó a cabo con una repetición máxima. Finalmente, la medición de la fuerza de prensión manual se realizó con un dinamómetro digital baseline®. Los resultados muestran que los tiempos obtenidos en 50 metros de nado libre presentan relaciones inversas con cuatro variables antropométricas, con la altura del Abalakov Jump y con cuatro pruebas de fuerza. La prueba de 50, 100 y 200 metros estilo pecho solo se relacionan con la fuerza de prensión de la mano. La prueba de 200 metros combinado se relaciona con cinco variables antropométricas, con la altura de salto del CMJ y con las cinco pruebas de fuerza. Son necesarias nuevas investigaciones donde se evalué un mayor número de deportistas, con mayores rangos etarios y diversos tiempos y tipos de entrenamiento que puedan ayudar a entender de mejor forma la incidencia de estas variables sobre el rendimiento deportivo.Abstract. Explosive force and power stand out among the multiple variables that condition performance in swimming tests, both being reliable predictors of swimmers' speed. The aim of this study was to determine the relationship of force, power, and anthropometric variables with the shortest performance time in young swimmers. The sample consisted of 27 swimmers from Santiago de Chile, 14 male (51.9%) and 13 female (48.1%) with ages between 13 and 21 years old.The anthropometric data were obtained with the ISAK protocol, using a digital scale Tanita model HD 357 and the Rosscraft Centurion kit. To measure the jump height, the contact platform DmJump® was used. Force was measured through press bench, horizontal press, and pull down, using the one maximum repetition method.Finally, measurement of manual grip force was carried out with a digital dynamometer baseline®. The results show that the times obtained in 50 meters of free swimming have inverse relationships with four anthropometric variables, with the height of the Abalakov Jump and with four force tests.The 50, 100 and 200-meter breaststroke tests only correlate with hand grip force. The combined 200-meter test is associated with five anthropometric variables, jump height in CMJ, and the five force tests. In future research, a greater number of athletes should be evaluated, with higher age ranges and different training times and types, which could help better understand the influence of these variables on sports performance.
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