Effect of reinforcing submicron SiC particles on the wear of electrolytic NiP coatings Part 2: Bi-directional sliding

As-plated and heat-treated electrodeposited NiP and composite NiP-SiC coatings were investigated in bi-directional ball-on-disc sliding tests. All tests were performed under gross slip conditions. Heat treatment decreases the wear volume loss during fretting in ambient air for all coatings investigated. Heat-treated NiP coating has a lower wear volume loss compared to composite NiP-SiC coatings for all sliding tests. The wear rate at the bi-directional sliding test was found to be lower relative to the wear rate at uni-directional sliding test

Effect of reinforcing submicron SiC particles on the wear of electrolytic NiP coatings Part 1. Uni-directional sliding

As-plated and annealed NiP coatings and composite NiP-SiC coatings were investigated in uni-directional ball-on-disc sliding tests. Abrasive wear was noticed in the case of composite NiP coatings containing submicron SiC particles, whereas in NiP coatings oxidational wear was active. The addition of submicron SiC particles not only increases the hardness of these electrolytic coatings but also hinders the formation of an oxide film in the sliding wear track. As a consequence, the wear loss on as-plated NiP coatings is not markedly reduced by the addition of SiC particles. On the contrary, a heat treatment at 420 °C for 1 h decreases the wear loss on both pure NiP and composite NiP-SiC coatings. During that heat treatment, Ni3P precipitates are formed in the NiP matrix and owing to this fact, the hardness of both pure NiP and composite NiP-SiC coatings increases. However, the heat treatment of composite NiP-SiC coatings induces the sensitivity for crack formation in the NiP matrix around these SiC particles. As a result, the pull out of SiC particles in the wear track occurs easily during sliding, and the wear loss of composite NiP-SiC coatings remains above the wear loss on NiP coatings

Evaluation of an organo-layered double hydroxide and two organic residues as amendments to immobilize metalaxyl enantiomers in soils: A comparative study

Many pollutants released into the environment as a result of human activities are chiral. Pollution control strategies generally consider chiral compounds as if they were achiral and rarely consider enantiomers separately. We compared the performance of three different materials, an organically-modified anionic clay (HT-ELA) and two organic agro-food residues (ALP and ALPc), as amendments to immobilize the chiral fungicide metalaxyl in two soils with different textures, addressing the effects of the amendments on the sorption, persistence, and leaching of each of the two enantiomers of metalaxyl (R-metalaxyl and S-metalaxyl) separately. The effects of the amendments were both soil- and amendment-dependent, as well as enantiomer-selective. The organo-clay (HT-ELA) was much more efficient in increasing the sorption capacity of the soils for the two enantiomers of metalaxyl than the agro-food residues (ALP and ALPc), even when applied at a reduced application rate. The enhanced sorption in HT-ELA-amended soils reduced the bioavailability of metalaxyl enantiomers and their leaching in the soils, mitigating the particularly high leaching potential of the more persistent S enantiomer. The immobilizing capacity of the agro-food residues was more variable, mainly because their addition did not greatly ameliorate the sorption capacity of the soils and had variable effects on the enantiomers degradation rates. HT-ELA showed potential to reduce the bioavailability and mobility of metalaxyl enantiomers in soil and to mitigate the contamination problems particularly associated with the higher leaching potential of the more persistent enantiomer. 11 páginas.-- 5 figuras.-- 2 tablas.-- referencias.-- Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.jenvman.2016.06.019This work has been financed by the Spanish Ministry of Economy and Competitiveness (MINECO Projects AGL2011-23779 and AGL2014-51897-R) and Junta de Andalucía (JA Research Group AGR-264), co-financed with FEDER-FSE funds. The authors thank B. Gamiz for her help in the design of the experiments and L. Cox for kindly supplying the organic residues. R. Lopez-Cabeza also thanks MINECO for a pre-doctoral fellowship linked to the Project AGL2011-23779 (Grant BES-2012-059945)Peer Reviewe

Fairness-Aware Ranking in Search & Recommendation Systems with Application to LinkedIn Talent Search

We present a framework for quantifying and mitigating algorithmic bias in mechanisms designed for ranking individuals, typically used as part of web-scale search and recommendation systems. We first propose complementary measures to quantify bias with respect to protected attributes such as gender and age. We then present algorithms for computing fairness-aware re-ranking of results. For a given search or recommendation task, our algorithms seek to achieve a desired distribution of top ranked results with respect to one or more protected attributes. We show that such a framework can be tailored to achieve fairness criteria such as equality of opportunity and demographic parity depending on the choice of the desired distribution. We evaluate the proposed algorithms via extensive simulations over different parameter choices, and study the effect of fairness-aware ranking on both bias and utility measures. We finally present the online A/B testing results from applying our framework towards representative ranking in LinkedIn Talent Search, and discuss the lessons learned in practice. Our approach resulted in tremendous improvement in the fairness metrics (nearly three fold increase in the number of search queries with representative results) without affecting the business metrics, which paved the way for deployment to 100% of LinkedIn Recruiter users worldwide. Ours is the first large-scale deployed framework for ensuring fairness in the hiring domain, with the potential positive impact for more than 630M LinkedIn members.Comment: This paper has been accepted for publication at ACM KDD 201

Evidence for the effect of sorption enantioselectivity on the availability of chiral pesticide enantiomers in soil

8 páginas.-- 4 figuras.-- 4 tablas.-- referencias.-- Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.envpol.2016.03.052.Although enantioselective sorption to soil particles has been proposed as a mechanism that can potentially influence the availability of individual chiral pesticide enantiomers in the environment, environmental fate studies generally overlook this possibility and assume that only biotic processes can be enantioselective, whereas abiotic processes, such as sorption, are non-enantioselective. In this work, we present direct evidence for the effect of the enantioselective sorption of a chiral pesticide in a natural soil on the availability of the single pesticide enantiomers for transport. Batch sorption experiments, with direct determination of the sorbed amounts, combined with column leaching tests confirmed previous observations that from non-racemic aqueous solutions the sorption of the chiral fungicide metalaxyl on the soil appeared to be enantioselective, and further demonstrated that the enantiomer that was sorbed to a greater extent (R-metalaxyl, Kd = 1.73 L/kg) exhibited retarded leaching compared to its optical isomer (S-metalaxyl, Kd = 1.15 L/kg). Interconversion and degradation of the pesticide enantiomers, which are potential experimental artifacts that can lead to erroneous estimates of sorption and its enantioselectivity, were discarded as possible causes of the observed enantioselective behavior. The results presented here may have very important implications for a correct assessment of the environmental fate of chiral pesticides that are incorporated into the environment as non-racemic mixtures, and also of aged chiral pesticide residues that have been transformed from racemic to non-racemic by biologically-mediated processes. © 2016 Elsevier Ltd. All rights reserved.This work was financed by the Spanish Ministry of Economy and Competitiveness (MINECO Project AGL2014-51897-R) and Junta de Andalucía (Research Group AGR-264), with European FEDER funds (Operative Program 2014–2020).Peer reviewe

Tricyclazole-clay complexes as potential smart delivery systems: release in water and environmental fate in alluvial and sandy soils

Natural mineral clays (SWy-2, CTI and SH) were modified with natural inorganic cation (Fe3+) and the biopolymer (chitosan (ch)) to increase the adsorption capacity for tricyclazole. Three ways to prepare tricyclazole-clay complexes (ground mixing, GM, weak complex, WC and strong complex, SC) were assayed with the aim to develop possible components for controlled release formulations (CRFs) of this fungicide. The greatest adsorption (> 93%) was measured in the natural clays modified with Fe3+. The release of tricyclazole in water was higher for GMs of SWch6 (77%), SWch4 (84%) and CTIFe (85%). No significant differences were observed in the dissipation in soil of tricyclazole applied as commercial product or as formulation. However, the leaching of the fungicide depended on the type of soil: tricyclazole was not detected in any leachate from the soil with higher clay content (alluvial) whereas the SWch6 weak complex (WC) reduced the leaching of tricyclazole (65%) as compared to the commercial formulation (75%) in a sandy soil after 60 days. This last tricyclazol-clay complex could be considered as appropriate component for CRF, to be used in sandy soils. The other modified clays assayed, showing very high, strong and irreversible adsorption could find application as filters to eliminate tricyclazole from contaminated waters. Clay-fungicide interaction mechanisms are discussed and related to their soil and water behavior.CSIC (JAE-Doc program), MINECO (AGL2011-23779 project) and Junta de Andalucía (P11-AGR-7400), co-funded by EU FEDER-FSE (OP 2009-2013) funding.Peer Reviewe

Adsorción-desorción de los metales pesados Pb(II) y Hg(II) por modelos de partículas coloidales del suelo

4 páginas, 2 figuras, 1 tabla, 3 referencias.-- Publicado en el Capítulo IV: Contaminación y Medio Ambiente.-- Trabajo presentado a la XVII Reunión Científica de la Sociedad Española de Arcillas, celebrada en Elche (Alicante) y Castellón, del 27-29 de noviembre de 2002.El destino de los metales pesados en el medio ambiente está controlado por las reacciones de adsorción a los coloides del suelo. Por otro lado, las interacciones entre los constituyentes del suelo pueden alterar significativamente la cantidad y naturaleza de la superficie expuesta por los coloides del suelo para la adsorción de contaminantes. Por tanto, las predicciones sobre la extensión de la adsorción basadas en la suma de las capacidades adsorbentes de los constituyentes individuales del suelo pueden desviarse de lo que ocurre en la naturaleza (1). En la bibliografia han sido poco estudiadas las interacciones entre contaminantes y adsorbentes polifásicos, aunque en la última década ha aumentado la atención dada al estudio del comportamiento de modelos de asociaciones coloidales para obtener una interpretación más realista del proceso de adsorción en el suelo (2). En este trabajo se han determinado las capacidades adsorbentes de modelos de partículas coloidales binarias y ternarias que contienen montmorillonita (SW), ferrihidrita (Fh) y ácido húmico (AH) para dos contaminantes inorgánicos, los metales pesados Pb(lI) y Hg(II), Y se compararon con las capacidades de adsorción de los constituyentes individuales. Las partículas modelos se prepararon en el laboratorio y se caracterizaron por análisis elemental, espectroscopía infrarroja, difracción de rayos X y medidas de superficie específica. Se estudió la adsorción-desorción de Pb(lI) y Hg(ll) por parte de los diferentes adsorbentes y se utilizaron las técnicas de espectroscopía infrarroja y difracción de rayos X para analizar los mecanismos de interacción.Este trabajo ha sido financiado por el proyecto del MCYT REN2001-1700-C02- 01/TECNO y por el grupo RNM124 del PAI de la Junta de AndalucíaPeer reviewe