Breakdown of Kinetic Compensation Effect in Physical Desorption

The kinetic compensation effect (KCE), observed in many fields of science, is the systematic variation in the apparent magnitudes of the Arrhenius parameters $E_a$, the energy of activation, and $\nu$, the preexponential factor, as a response to perturbations. If, in a series of closely related activated processes, these parameters exhibit a strong linear correlation, it is expected that an isokinetic relation will occur, then the rates $k$ become the same at a common compensation temperature $T_c$. The reality of these two phenomena continues to be debated as they have not been explicitly demonstrated and their physical origins remain poorly understood. Using kinetic Monte Carlo simulations on a model interface, we explore how site and adsorbate interactions influence the Arrhenius parameters during a typical desorption process. We find that their transient variations result in a net partial compensation, due to the variations in the prefactor not being large enough to completely offset those in $E_a$, both in plots that exhibit a high degree of linearity and in curved non-Arrhenius plots. In addition, the observed isokinetic relation arises due to a transition to a non-interacting regime, and not due to compensation between $E_a$ and $\ln{\nu}$. We expect our results to provide a deeper insight into the microscopic events that originate compensation effects and isokinetic relations in our system, and in other fields where these effects have been reported.Comment: 11 pages, 17 figures, 3 table

The influence of individual characteristics and parenting behaviors on adolescent academic performance

The purpose of this study was to discover the effects of adolescent autonomy, parental academic involvement and parental academic expectations as they link gender, age, ethnicity, and immigrant generation to adolescent academic performance. A selected sample from the National Longitudinal Study of Adolescent Health data set (Add Health) was used to examine these relationships specifically for Latino/as with comparisons drawn to White, African American, and Asian adolescents. Special emphasis was also placed on gender differences for each ethnic/racial group. The outcome variable of adolescent academic performance was assessed using the adolescent\u27s reported grade point average (GPA). The sample was analyzed as a whole using a four-stage hierarchical regression model controlling for single versus dual-parent homes, the adult-to-child ratio in the home, parent education, mental and learning disabilities, depression, and self-esteem.;It was discovered that adolescent autonomy, parental involvement and parental expectations do not mediate the relationship between the independent variables (gender, age, ethnicity, and immigrant generation) and GPA but rather serve as additional explanatory variables. All three variables had a positive influence on academic performance regardless of gender or ethnicity. Most notably, parental involvement was the single strongest predictor of Latino/a adolescent performance, especially for Latino males. In addition, many of the relationships observed and the explanatory strength of the variables examined were ethnic- and gender-specific. Educational recommendations are made for working with ethnic minority males, as well as their parents, specifically those who are not native to the United States

LPS-Induced iNOS mRNA and the Pro-Apoptotic Signaling Pathway in Leukocytes of Fit and Unfit Males

Overexpression of the enzyme iNOS induces apoptotic cellular death by increasing indices of pro-inflammation and oxidative stress. Aerobic physical activity has been known to have anti- inflammatory benefits and reduce oxidative stress. Purpose: Therefore, this study aimed to examine the impact of aerobic fitness on LPS-induced iNOS mRNA expression and the relationship of this expression with indices of oxidative stress, pro-inflammation and apoptosis in isolated leukocytes. Methods: Whole blood samples from aerobically fit and unfit males were stimulated with and without LPS. Thereafter, iNOS mRNA expression and MDA, TNF-α and p53 concentrations were analyzed. Results: iNOS mRNA expression levels following LPS stimulation were not increased in both groups, and correlational analyses were not consistent with mechanistic predictions. Discussion: Numerous factors including timing of sample quantification, the high level of health of the subject population, and alternative intracellular mechanisms impacting biomarkers analyzed, may have influenced leukocyte iNOS mRNA expression levels

Nevirapine- and efavirenz-associated hepatotoxicity under programmatic conditions in Kenya and Mozambique.

To describe the frequency, risk factors, and clinical signs and symptoms associated with hepatotoxicity (HT) in patients on nevirapine- or efavirenz-based antiretroviral therapy (ART), we conducted a retrospective cohort analysis of patients attending the ART clinic in Kibera, Kenya, from April 2003 to December 2006 and in Mavalane, Mozambique, from December 2002 to March 2007. Data were collected on 5832 HIV-positive individuals who had initiated nevirapine- or efavirenz-based ART. Median baseline CD4+ count was 125 cells/μL (interquartile range [IQR] 55-196). Over a median follow-up time of 426 (IQR 147-693) days, 124 (2.4%) patients developed HT. Forty-one (54.7%) of 75 patients with grade 3 HT compared with 21 (80.8%) of 26 with grade 4 had associated clinical signs or symptoms (P = 0.018). Four (5.7%) of 124 patients with HT died in the first six months compared with 271 (5.3%) of 5159 patients who did not develop HT (P = 0.315). The proportion of patients developing HT was low and HT was not associated with increased mortality. Clinical signs and symptoms identified 50% of grade 3 HT and most cases of grade 4 HT. This suggests that in settings where alanine aminotransferase measurement is not feasible, nevirapine- and efavirenz-based ART may be given safely without laboratory monitoring

MECHANISTIC STUDY OF A RUTHENIUM HYDRIDE COMPLEX OF TYPE [RuH(CO)(N-N)(PR3)2]+ AS CATALYST PRECURSOR FOR THE HYDROFORMYLATION REACTION OF 1-HEXENE

Indexación: Web of Science; Scopus; Scielo.The catalytic activity of systems of type [RuH(CO)(N-N)(PR3)(2)](+) was evaluated in the hydroformylation reaction of 1-hexene. The observed activity is explained through a reaction mechanism on the basis of the quantum theory. The mechanism included total energy calculations for each of the intermediaries of the elemental steps considered in the catalytic cycle. The deactivation of the catalyst precursors takes place via dissociation of the polypyridine ligand and the subsequent formation of thermodynamically stable species, such as RuH(CO)(3)(PPh3)(2) and RuH3(CO)(PPh3)(2), which interrupt the catalytic cycle. In addition, the theoretical study allows to explain the observed regioselectivity which is defined in two steps: (a) the hydride migration reaction with an anti-Markovnikov orientation to produce the alkyl-linear-complex (3.1a), which is more stable by 19.4 kJ/mol than the Markovnikov orientation (alkyl-branched-complex) (3.1b); (b) the carbon monoxide insertion step generates the carbonyl alkyl-linear specie (4.1a) which is more stable by 9.5 kJ/mol than the alternative species (4.1b), determining the preferred formation of heptanal in the hydroformylation of 1-hexene. Palabras clavehttp://ref.scielo.org/db4yc

Rio Bravo: A bilingual journal of international studies Fall 1991 v.1 no.1

Río Bravo: An Introduction -- Mexican Labor is Not Cheap / by George Baker -- Enfoques teóricos para el estudio de la cultura en la frontera de Mexico con Estados Unidos / José Carlos Lozano -- Los locos del barrio o la ostentación del estigma: Identidad social y frontera en una pandilla de Matamoros, Tamaulipas / by Victor Zúñiga -- English as a Second Language: The Teachers\u27 Perspective / by Pamela McCurdy -- Decentralization Works: China and Mexico Make it Happen in Health Care Delivery / by Paul Villas, Janet L. Lile, and Hector Pérez-Coronado --U.S. Prisoners in Border Prisons in Tamaulipas, Mexico / by J. Michael Olivero --Lampazos and the Mexican Revolution / by Ward S. Albro IIIhttps://scholarworks.utrgv.edu/riobravojournal/1000/thumbnail.jp

Rio Bravo: A bilingual journal of international studies Fall 1992 v.2 no.1

Usos del Suelo y Configuración de la Estructura Urbana en Ciudad Juárez, Chih., (1960-1990) / by Cesar M. Fuentes -- César Chávez, the United Farm Workers and Mexican Immigration / by Richard Griswold del Castillo -- Texas Higher Education and Border Funding Inequities: Implication for Border Universities and Transborder Cooperation / by Ellwyn R. Stoddard -- Texas Discovers Its Mexican Neighbors: Border-State Governmental Relations, 1978-1991 / by E. V. Niemeyer, Jr. -- The Mexican Crisis and the Segmented Labor Market of the Lower Rio Grande Valley of Texas / by Joseph Spielberg Benitez -- Medicalization of the U.S.-Mexico Border: Is it Really Needed / by Paul Villas and Erin Frew -- Reviews / Reseñas -- Guia para los Autores / Author\u27s Guidelines.https://scholarworks.utrgv.edu/riobravojournal/1002/thumbnail.jp