Search results for "support"
showing 10 items of 2310 documents
Alteration of the Mitochondrial Effects of Ceria Nanoparticles by Gold: An Approach for the Mitochondrial Modulation of Cells Based on Nanomedicine
2020
Ceria nanoparticles are cell compatible antioxidants whose activity can be enhanced by gold deposition and by surface functionalization with positive triphenylphosphonium units to selectively target the mitochondria. The antioxidant properties of these nanoparticles can serve as the basis of a new strategy for the treatment of several disorders exhibiting oxidative stress, such as cancer, diabetes or Alzheimer&rsquo
Comparative study to predict toxic modes of action of phenols from molecular structures.
2013
Quantitative structure-activity relationship models for the prediction of mode of toxic action (MOA) of 221 phenols to the ciliated protozoan Tetrahymena pyriformis using atom-based quadratic indices are reported. The phenols represent a variety of MOAs including polar narcotics, weak acid respiratory uncouplers, pro-electrophiles and soft electrophiles. Linear discriminant analysis (LDA), and four machine learning techniques (ML), namely k-nearest neighbours (k-NN), support vector machine (SVM), classification trees (CTs) and artificial neural networks (ANNs), have been used to develop several models with higher accuracies and predictive capabilities for distinguishing between four MOAs. M…
Influence of Teacher and Family Support on University Student Motivation and Engagement
2021
Although many studies endorse the notion that the way students perceive support influences their engagement, very few have explored the possible mediator role of intention to learn between these variables. The present work provides new evidence to the existing literature because it analyses the work of intention to learn (measured with expectancy–value beliefs and achievement goals) as a mediating motivational variable in the relation between university students’ external support (teacher and family) and their engagement. The Educational Situation Quality Model (MOCSE, its acronym in Spanish) has employed as a theoretical framework to perform this analysis. A sample of 267 Spanish universit…
Proyectos educativos multidisciplinares y ayuda a la comunidad
2019
This paper relates an experience carried out at a higher education setting, specifically involving 3rd-year students in the Early Childhood Education degree programme. In relation to this, the paper presents an educational model that takes into account the need to develop ethical and social competences and gives importance to interdisciplinary education in real contexts. To this aim, all the academic modules that form part of this degree programme devote 25% of their teaching time and evaluation to the development of an interdisciplinary project. This paper will describe one of these projects, entitled "Solve a real problem", the design of which is informed by service-learning and problem-b…
Facilitated SLM extraction of peptides with D2EHPA as a carrier
2004
Abstract The extraction of short peptides through a supported liquid membrane containing di-2-(ethylhexyl)phosphoric acid (D2EHPA) as a carrier was investigated. The extraction was carried out from the aqueous donor phase with pH 3 to amore acidic acceptor phase. The proton gradient between the donor and the acceptor phase was the main driving force of the mass transfer in this system. The influence of various parameters such as diluent of the carrier, pH of the donor and acceptor phase, peptide structure and concentration on the extraction efficiency was presented.
On the Existence of Different Zeolite-Associated Topological Redox Isomers. Electrochemistry of the Y Zeolite-Associated Mn(Salen)N3 Complex
2002
The electrochemical properties of Y zeolite-associated MnIII(salen)N3 (salen = trans-(R,R)-1,2-bis(salicyldeneamino)cyclohexane) has been investigated using polymer film electrodes immersed into neutral aqueous solutions. Zeolite Y-associated Mn(III)−salen complexes are reduced in one-electron reversible process at −0.25 V versus SCE. The electrochemical response is discussed in terms of the existence of two topological redox isomers: a weakly boundary-associated Mn(salen) complex, whose electrochemical response corresponds to a reversible one-electron transfer controlled by diffusion of the positive ions of the supporting electrolyte through the zeolite surface windows and channels, and a…
Chromia on silica and zirconia oxides as recyclable oxidizing system: structural and surface characterization of the active chromium species for oxid…
2004
Chromium oxide samples supported over silica and zirconia were prepared by wet impregnation of the supports with aqueous solution of CrO3. In order to investigate the influence of the preparation method on the chromium dispersion and oxidation state, one sample was prepared by sol-gel technique. The materials were structurally characterized by XRD analysis. The oxidation states of chromium species were investigated by XPS, DRS and TPR/TPO techniques. EPR analyses were also carried out for the sample Cr/SiO2, that due to the low crystalline state exhibits broad XPS signals. In this case, particular attention was paid to the presence of Cr(V) and Cr (III) species and their concentration. The …
Electrochemical conversion of pressurized CO2 at simple silver-based cathodes in undivided cells: study of the effect of pressure and other operative…
2020
Abstract Electrochemical reduction of pressurized CO2 is proposed as an interesting approach to overcome the main hurdle of the CO2 electrochemical conversion in aqueous solution, its low solubility (ca. 0.033 M), and to achieve good faradaic efficiency in CO using simple sheet silver cathodes and undivided cells, thus lowering the overall costs of the process. The effect on the process of CO2 pressure (1–30 bar), current density, nature of the supporting electrolyte and other operative conditions, such as the surface of the cathode or the mixing rate, was studied to enhance the production of CO. It was shown that pressurized conditions allow to improve drastically the current efficiency o…
Influence of chloride anions on the electrodeposition and electroactivity of the polymer matrix in polypyrrole, poly( N -methylpyrrole) and polypyrro…
2004
We report electrochemical studies on the influence of a small concentration of chloride ions on the electroactivity of the polymer matrix of polypyrrole (PPy), poly(N-methylpyrrole) [p(N-MePy)] and a poly(titanocene-propyl-pyrrole) derivative, p(Tc3Py) [Tc(CH2)3NC4H4; Tc=CpCp′TiCl2; Cp=C5H5; Cp′=C5H4] in acetonitrile (AN), tetrahydrofuran (THF) and N,N-dimethylformamide (DMF). The polymer films were obtained on Pt disc electrodes from AN solutions of the monomers containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte and then transferred to the corresponding monomer-free solution. Studies in Cl−-containing solutions have shown that the p(Tc3Py) matrix…
Uranium(VI) sequestration by polyacrylic and fulvic acids in aqueous solution
2011
Stability data on the formation of dioxouranium(VI) species with polyacrylic (PAA) and fulvic acids (FA) are reported with the aim to define quantitatively the sequestering capacity of these high molecular weight synthetic and naturally occurring ligands toward uranium(VI), in aqueous solution. Investigations were carried out at t = 25 °C in NaCl medium at different ionic strengths and in absence of supporting electrolyte for uranyl–fulvate (\( {{\text{UO}}_{2}}^{2+} \)–FA) and uranyl–polyacrylate (\( {{\text{UO}}_{ 2}}^{ 2+ } \)–PAA, PAA MW 2 kDa) systems, respectively. The experimental data are consistent with the following speciation models for the two systems investigated: (i) UO2(FA1),…