5,899 research outputs found
Encuentros con Elena Poniatowska
No full textThe author analyzes testimonial literature from the perspective of female literature through his meeting with Elena Poniatowska. An analysis of reality vs. Fiction in Elena, Jesusa and Tinisima.El autor analiza, desde su encuentro con Elena Poniatowska, la vertiente de la literatura testimonial como literatura de mujeres. Un análisis interior de la relación entre realidad y ficción, entre Elena, Jesusa o Tinísima
In situ ATR/FTIR studies of protein adsorption on polymeric materials: effectiveness of surface heparinisation
No full textThe adsorption of two proteins from human plasma (human serum albumin (HSA) and human fibrinogen (HFG) onto six different polymeric surfaces (two of which are heparinized), has been studied by in situ ATR/FTIR spectroscopy. The different surface characteristics are reflected by different interfacial behaviours of the two proteins, but while both proteins unfold upon adsorption on all the different non-heparinized materials, they maintain the native conformation once adsorbed on the heparinized surfaces. These findings emphasize the effectiveness of surface heparinization. © 1994 Chapman & Hall
The biodegradation of Aromatic pollutants by heme protein-H2O2 systems: an EPR spin trapping study
No full textPAH are known to be important xenobiotic pollutants. The study of their oxidation reaction in
simple systems, such as the hemoprotein-H2O2, may permit the development of new methods
of biodegradation. An understanding of the reaction mechanisms involved can lead to models
for synthesis of new catalyzers
Influence of the headgroup molecular structure on the anionic surfactant-PVP interaction studied by Electron Paramagnetic Resonance of a cationic nitroxide
No full textIn the present work the mixtures water–sodium decylsulfate (C10OS)-poly(vinylpyrrolidone) (PVP) and water–sodium decylsulfonate (C10S)–PVP have been investigated by electron paramagnetic resonance (EPR) spectroscopy employing 4-(N,N-dimethyl-N-(2-hydroxyethyl)) ammonium-2,2,6,6-tetramethyl-piperidine-1-oxyl chloride (TEMPO-choline, TC) as spin probe. TC cations condense on the surface of the aggregates formed by anionic surfactants, acting as counterions, and fit their NO moiety in the outer shell of the hydrophobic core. In water–C10OS–PVP mixtures the nitrogen isotropic hyperfine coupling constant of TC (〈AN〉), reported as a function of the surfactant molality at constant PVP composition, shows two breakpoints: the former (critical aggregation concentration, c.a.c.) corresponds to the formation of surfactant–polymer clusters while the latter (c2) corresponds to the formation of free surfactant micelles. The trend of the correlation time (τC) of the nitroxides in the same system shows that the electrostatic repulsion among the clusters formed onto the PVP macromolecules favours a broadening of the polymer coil and a stiffening of its chain. In contrast, in water–C10S–PVP mixtures no surfactant–polymer interaction could be detected. The effect of the molecular structure of the surfactant headgroup on the surfactant–polymer interaction has been discussed in terms of charge density distribution. In order to further highlight the importance of the headgroup molecular structure on the surfactant association behaviour, the micellisation process of the sodium alkylsulfates (CnOS, n = 6,8,10) has been investigated by the same experimental approach, and the results have been compared with those, previously reported (A. M. Tedeschi, G. D'Errico, E. Busi, R. Basosi and V. Barone, Phys. Chem. Chem. Phys., 2002, 4, 2180, ref. 46), relative to the sodium alkylsulfonates (CnS). CnOS micelles are more ordered and compact with respect to the CnS ones. For the former class of surfactants the electrostatic interaction with TC is stronger and the hydrophobic behaviour of the TC solubilization site is higher
A novel environmental indicator for monitoring of pesticides
No full textThe identification of an indicator for monitoring pesticides is a very effective analytical approach because it allows one to schedule and simplify the analytical routine. In this study, a new indicator has been designed, which has to be able to define a scale of priorities in the pesticides monitoring. A starting equation was developed involving the escaping tendency of a given substance from a phase (based on the Mackay model I level). The reliability of the indicator was tested by application to a model system, consisting of a defined and limited area, choosing water as matrix over a period of 6 years. A group of marker compounds was also defined to implement the predictive efficacy of the indicator. The results obtained by modeling were compared to those obtained by experimentation of the same model system. The indicator was subsequently and appropriately modified creating a new equation, including a kinetic factor, which considers the environmental degradation processes. The effect of the rectified indicator was consistent with the sales data list of compounds, when applied to the markers. The indicator developed in this study, tested as a model on specific area-phase-period (Province of Siena, water phase, 2000-2006), is applicable to any other area-phase-period, adjusting the partition value of the Mackay model for the case under study. © 2010 Springer Science+Business Media B.V
Reachability Analysis in Boxed Ambients
No full textThe decidability of reachability for pure public Mobile Ambients (i.e. without communication and restriction) has been recently investigated in [5], where a characterization of a maximal deacidable fragment is provided. A peculiar feature of such a fragment is the absence of the open capability for ambient dissolution. In this paper we analyse reachability in Boxed Ambients [2], the most relevant variant of Mobile Ambients in which the open capability is dropped and replaced by a sophisticated parent/child form of communication.
The main novelties with respect to [5] are: (i) the definition of a more general notion of reachability (called target reachability); (ii) the proof of the decidability of target reachability for a richer calculus also comprising parent/child communication
Bio-bibliografía de y sobre Elena Poniatowska Amor
No full textThe objective of this article is to collect and present: I. the chronology of the life and work of Elena Poniatowska; II. the complete works (as principal and secondary author), and III. the bibliography on the author (books, chapters, and articles).El objetivo de este artículo es reunir y presentar: I. los datos cronológicos fundamentales de la vida y la obra de Elena Poniatowska; II. El compendio de sus obras (como autora principal y como secundaria); y III. la bibliografía sobre la escritora (libros, capítulos de libros y artículos)
EPR and O2- Scavenger Activity: Cu(II)-Peptide Complexes as Superoxide Dismutase Models
No full textA variety of copper(lI) complexes with di-, tri- and tetra-peptides containing only glycine residues (GG, GGG
and GGGG) and others containing a histidyl residue in different positions (HGG, GHG, GGH and GGHG) have been investigated. EPR parameters obtained by extensive use of computer simulation of spectra lead to reliable spin Hamiltonian EPR parameters at both room
temperature and in frozen solution. The molecular orbital coefficients computed from the anisotropic EPR data and the d-d electronic energies are used to characterize different arrangements of the complexes. Estimation of the scavenger activity of the complexes due to the particular environment created by the ligands around copper is discussed in the frame of the structure-activity relationship
El Tlacuache Núm. 698 (2015). 698 Año 13 (2015) noviembre. El Tlacuache
No full textLa mujer vista por cronistas en tiempos novohispanos por Laura Elena Hinojosa. - El Códice Mauricio de la Arena forma parte de Los códices de Tlaquiltenango por Laura Elena Hinojosa
Simulation of EPR spectra as a tool for interpreting the degradation pathway of hyaluronan
No full textElectron paramagnetic resonance (EPR) spin trapping is one of the
choice techniques for identifying free radicals and is often used in the study of
biological systems. However, its sensitivity can result in a typical complicated EPR
spectrum. The accurate simulation of these systems is essential for correct identification
of the radical species, whenever more than one species contributes to the
spectrum. Programs implementing the linear combination of single simulations
allow the interpretation of EPR spectra without modifying experimental conditions.
In this study, this approach was used to investigate the influence of the ferrous ion
and the role of oxygen, as well on the formation of transient radical species, in the
whole mechanism of hyaluronan degradation. Degradation was carried out under
different environmental conditions (air, O2, Ar, N2, N2 ? CO2) and EPR spin
trapping studies were performed. The advantages of the simulation of multiple
species EPR spectra were applied to the obtained results and some aspects of
hyaluronan degradation mechanism were elucidated. The depolymerization reaction
pathway has been defined according to two possible subsequent steps: the first is
consistent with formation of an amidyl radical that induces a series of strand
scissions, which stabilize at two different levels of molecular weight. The second
step occurs when the molecular weight is lower than before and two different
adducts are generated
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