El efecto del cloruro de N-cetilpiridina sobre la absorción de un colorante reactivo sobre Leacril. Potencial zeta y termodinámica de absorción.

Se ha efectuado una investigación de tipo experimental sobre la absorción y potencial de flujo de Remazol Blue R (RBB-R) con fibras Leacril tratadas y sin tratar con 10^-3 M de cloruro de N-cetilpiridina (N-CP-CI). Los modelos de haces decapilares utilizados son los de Goring y Mason, Biefer y Mason, y Chang y Roberston. El comportamiento cualitativo del potencial zeta es similar en los tres modelos usados. El aumento observado del potencial zeta, en Leacril sin tratar, entre 10^-6 M y 10^-5 de RBB-R en solución se debe probablemente a las atracciones hidrofóbicas entre la fibra y la parte hidrofóbica del colorante. A concentraciones mayores a ca. 10^-5 de colorante, las reacciones químicas entre los grupos -NH2, y NH del colorante y el sulfato y los grupos de terminales de sulfato del Leacril podrían probablemente ser la causa de la disminución observada del potencial zeta en la gama de concentración mencionada. La cantidad de RBB-R absorbida en el Leacril sin tratar se ve favorecida por el aumento de la temperatura de adsorción. Se debe ello a los enlaces químicos implícitos en el proceso de absorción. Los valores del potencial zeta negativos, en fibra tratada, son más elevados que los valores del potencial zeta para fibras sin tratar en toda la gama de concentración ensayada en RBB-R. Este hecho viene a demostrar un aumento de la fortaleza de las interacciones entre la fibra de Leacril tratada y RBB-R. También se presentan datos sobre la cinética y termodinámica de absorción de Remazol Brillant Blue R, en fibras Leacril tratadas y sin tratar a diferentes temperaturas, habiéndose obtenido los valores de las constantes de velocidad de la reacción tiempo de media tintura y coeficientes de difusión del colorante en los mencionados procesos de absorción. De forma similar, se han obtenido los cambios de entalpia y entropía en relación con el proceso de tintura del Leacril. Los resultados ponen de manifiesto la presencia de fuertes enlaces químicos entre los sistemas, tratados y no tratados, de Leacril/Remazol Brilliant Blue.An experimental investigation on the streaming potential and sorption of Remazol Brilliant Blue R (RBB-R) on both wtreated and treated Leacril fibres with 10^-3 M of N-cetylpyridinium chloride (N-CP-CI) has been carried out. The models of bundle of capillaries employed in the determination of zeta potential of Leacril are the models of Goring and Mason, Biefer and Mason and Chang and Robertson. The qualitative behaviour of zeta potential is similar in the three models employed. The increasing of zeta potential observed, by untreated Leacril, between and 10^-5 M and ca. 10^-5 M of RBB-R in solution is probably due to the hydrophobic attractions between the fibre and the hydrophobic part of the dye. At concentrations higher than ca 10^-5 of dye, the chemical reactions between both -NH2, and the -NH groups of the dye and the sulphonate and sulfate end-groups of the Leacril, respectively, could possibly cause the observed decreasing in the zeta potential, at the mentioned concentration range. The amount of RBB-R absorbed on untreated Leacril is favoured by the increasing in adsorption temperature. This fact is due to the chemical bonds involved in the absorption process. The values of the negative zeta potential, by treated fibre, are higher than of zeta potential by untreated fibres in all the concentration range tested of RBB-R. This fact shows an increasing in the strength of the interactions between the treated Leacril fibre and the RBB-R. Data of the kinetics and thermodynamics of absorption of Remazol Brilliant Blue R on both untreated and treated Leacril at different temperatures are presented, obtaining both the values for the rate constant of the reaction, the half-dyeing time and the diffusion coefficients of the dye in the above processes of absorption. They have also been obtained the changes of enthalpy and entropy related to the process of dyeing of Leacril. Results reveal the presence of strong chemical bonds between both the untreated and treated Leacril/Remazol Brilliant Blue systems.Nous avons entrepis des recherches de type expérimentel sur l'absorption et le potentiel de flux de Remazol Blue R (RBB-R) avec des fibres Leacril traitées et non traitées avec 10^-3 M de chlorure de N-cétylpyridine (N-CP-CI). Les modèles de faisceaux capillaires utilisés sont ceux de Goring et Mason, Biefer et Mason, et Chang et Roberston. Le comportement qualitatif du potential zêta est similaire dans les trois modèles utilisés. L'augmentation observé du potentiel zêta, sur du Leacril non traité, entre 10^-6 M et 10^-5 de RBB-R en solution, est probablement dû aux attractions hydrophobiques entre la fibre et la partie hydrophobique du colorant. À des concentrations de colorant supérieures a 10^-5 ca, les reactions chimiques entre les groupes -NH, et NH du colorant et le sulfonate et les groupes terminaux de sulfate du Leacril pourraient probablement expliquer la diminution observée du potentiel zêta dans la gamme de concentration mentionnée. La quantité de RBB-R absorbée dans le leacril non traité est favorisée par l'augmentation de la température d'adsorption. Cela est dû aux liaisons chimiques implicites dans le processus d'absorption. Les valeurs négatives du potentiel zêta, pour la fibre traitée, sont supérieures aux valeurs du potentiel zêta pour des fibres non traitées dans toute la gamme de concentration testée en RBB-R. Ce fait démontre l'augmentation de la robustesse des interactions entre la fibre de Leacril traitée et RBB-R. Nous apportons aussi des données sur la cinétique et la thermodynamique d'absorption de Ramazol Brillant Blue R, sur des fibres Leacril traitées et non traitées, à différentes températures, puisque nous avons obtenu les valeurs des constantes de vitesse de la réaction temps de demi-teinture et des coefficients de diffusion du colorant dans les processus d'absorption cités. De même, nous avons obtenu les changements d'enthalpie et d'entropie par rapport au processus de teinture du Leacril. Les résultats mettent en évidence la présence de fortes liaisons chimiques entre les systèmes, traités et non traités, de Leacril/Remazol Brillant Blue.Peer Reviewe

Functional-bandwidth kernel for Support Vector Machine with Functional Data:An alternating optimization algorithm

Functional Data Analysis (FDA) is devoted to the study of data which are functions. Support Vector Ma- chine (SVM) is a benchmark tool for classification, in particular, of functional data. SVM is frequently used with a kernel (e.g.: Gaussian) which involves a scalar bandwidth parameter. In this paper, we pro- pose to use kernels with functional bandwidths. In this way, accuracy may be improved, and the time intervals critical for classification are identified. Tuning the functional parameters of the new kernel is a challenging task expressed as a continuous optimization problem, solved by means of a heuristic. Our experiments with benchmark data sets show the advantages of using functional parameters and the ef- fectiveness of our approach

Effect of the nature of exogenous organic matter on pesticide sorption by the soil

A study was carried out on the sorption of two sparingly water-soluble pesticides (diazinon and linuron) by a sandy loam soil modified with different exogenous organic materials (EOMs) containing humic like substances: city refuse compost (CRC), peat (P), commercial humic acid (HA), liquid humic acid (LHA) extracted from leonardite and two (non humic) model compounds (surfactants): tetradecyltrimethylammonium bromide (TDTMA) and sodium dodecyl sulphate (SDS) before and after 2 and 8 months incubation periods with the soil. In all cases, the isotherms fitted the Freundlich sorption equation (x/m=KCen), generally with r2 values greater than 0.99. The value of the sorption constant K for the natural soil was 8.81 for diazinon and 2.29 for linuron. These values increased significantly for EOM modified soils with respect to natural soil, with the exception of the samples modified with SDS and LHA, in which cases they decreased, possibly due to the micellar properties of these compounds. Incubation of EOMs with soil increased their sorption capacity: the Koc values were increased proportionally to the incubation time for both pesticides and for all treatments carried out. Accordingly, the sorption capacity of hydrophobic pesticides increases with the degree of evolution in the soil of EOMs with humic type compounds, possibly due, among other causes, to the increase in the EOMs colloidal properties and the modifications occurring in the hydrophobic- hydrophilic characteristics of the soil surfaces. The main conclusion is that application to the soil of solid carbon rich wastes, especially those with a high degree of maturity, may offer an important strategy for reducing pesticide leaching, and for eliminating pesticide residues from soil with the use of liquid humic acids.Peer reviewe

Effect of the nature of exogenous organic matter on pesticide sorption by the soil

A study was carried out on the sorption of two sparingly water-soluble pesticides (diazinon and linuron) by a sandy loam soil modified with different exogenous organic materials (EOMs) containing humic like substances: city refuse compost (CRC), peat (P), commercial humic acid (HA), liquid humic acid (LHA) extracted from leonardite and two (non humic) model compounds (surfactants): tetradecyltrimethylammonium bromide (TDTMA) and sodium dodecyl sulphate (SDS) before and after 2 and 8 months incubation periods with the soil. In all cases, the isotherms fitted the Freundlich sorption equation (x/m=KCen), generally with r2 values greater than 0.99. The value of the sorption constant K for the natural soil was 8.81 for diazinon and 2.29 for linuron. These values increased significantly for EOM modified soils with respect to natural soil, with the exception of the samples modified with SDS and LHA, in which cases they decreased, possibly due to the micellar properties of these compounds. Incubation of EOMs with soil increased their sorption capacity: the Koc values were increased proportionally to the incubation time for both pesticides and for all treatments carried out. Accordingly, the sorption capacity of hydrophobic pesticides increases with the degree of evolution in the soil of EOMs with humic type compounds, possibly due, among other causes, to the increase in the EOMs colloidal properties and the modifications occurring in the hydrophobic- hydrophilic characteristics of the soil surfaces. The main conclusion is that application to the soil of solid carbon rich wastes, especially those with a high degree of maturity, may offer an important strategy for reducing pesticide leaching, and for eliminating pesticide residues from soil with the use of liquid humic acids.Peer reviewe

Transactional Links between Teacher-Adolescent Support, Relatedness, and Aggression at School: A Three-Wave Longitudinal Study

This study examines the reciprocal effects between two school-based relationships within the classroom-namely, perceived teacher support and relatedness with classmates-and school aggression (overt and relational) across two courses of secondary education. Participants were 654 adolescents (48% boys), who were assessed in three waves: first, at the beginning of the academic year (T0), second, at the end of the same academic year (T1), and third, at the beginning of the next academic year (T2) (Mage wave 1 = 13.98 years). Autoregressive cross-lagged modeling was applied. Results show a protective effect of relatedness against relational aggression in both genders. Moreover, we observed a protective effect of perceived teacher support at the beginning of the course for later school aggression as well as a risk effect if this perceived teacher support is maintained throughout the course. These effects were observed in relation with gender-atypical forms of aggression (overt in girls and relational in boys). Finally, aggression had negative consequences for relatedness in girls and for teacher support through the mediation of relatedness in boys. Gender differences and practical implications of these findings are discussed

Choosing Expected Shortfall over VaR in Basel III Using Stochastic Dominance

Bank risk managers follow the Basel Committee on Banking Supervision (BCBS) recommendations that recently proposed shifting the quantitative risk metrics system from Value-at-Risk (VaR) to Expected Shortfall (ES). The Basel Committee on Banking Supervision (2013, p. 3) noted that: “a number of weaknesses have been identified with using VaR for determining regulatory capital requirements, including its inability to capture tail risk”. The proposed reform costs and impact on bank balances may be substantial, such that the size and distribution of daily capital charges under the new rules could be affected significantly. Regulators and bank risk managers agree that all else being equal, a “better” distribution of daily capital charges is to be preferred. The distribution of daily capital charges depends generally on two sets of factors: (1) the risk function that is adopted (ES versus VaR); and (2) their estimated counterparts. The latter is dependent on what models are used by bank risk managers to provide for forecasts of daily capital charges. That is to say, while ES is known to be a preferable “risk function” based on its fundamental properties and greater accounting for the tails of alternative distributions, that same sensitivity to tails can lead to greater daily capital charges, which is the relevant (that is, controlling) practical reference for risk management decisions and observations. In view of the generally agreed focus in this field on the tails of non-standard distributions and low probability outcomes, an assessment of relative merits of estimated ES and estimated VaR is ideally not limited to mean variance considerations. For this reason, robust comparisons between ES and VaR will be achieved in the paper by using a Stochastic Dominance (SD) approach to rank ES and VaR

Linezolid: idoneidad de prescripción y afectación de la función renal y hematológica

The objective of the study was to evaluate the suitability of linezolid prescription, incidence of thrombocytopenia incritically ill patients and its infl uence on critical ill patients with renal disorder before the linezolid treatment. Weobserved that the 37.5% of linezolid prescriptions were in Non-Approved Indications in Spain (NAIS). The incidenceof thrombocytopenia was 5.9%. We observed a signifi cant improvement in renal function of patients after two weeks oflinezolid treatment (p=0.024). The incidence of thrombocytopenia was similar to describe in bibliography. It seems tobe necessary approved news indications in Spain.El objeto de este estudio fue evaluar la idoneidad de prescripción de linezolid y si ésta se ajusta a las indicacionesaprobadas en España (IAE), la incidencia de trombocitopenia en pacientes críticos y la infl uencia de linezolid eneste tipo de pacientes con función renal alterada previamente a la instauración del tratamiento con dicho antibiótico.Se recogieron retrospectivamente datos clínicos y analíticos, observando que el 37.5% de las prescripcionesde linezolid eran en indicaciones no aprobadas en España (INAE), una incidencia de trombocitopenia del 5.9% yuna mejora signifi cativa de la función renal (p=0.024) tras dos semanas de tratamiento con linezolid. La incidenciade trombocitopenia en nuestro estudio fue similar a la descrita en la bibliografía. Parece necesario replantearse laampliación de las INAE