Search results for "Solid"
showing 10 items of 3575 documents
El G-8 y las Naciones Unidas
2001
Equity of Public Pension System
2020
Fairness is an important feature of pension systems, but it is a wide concept with multiple sides. In this chapter, we try to distinguish some of them with the aim of using the terms in a proper manner. More specifically, we have observed at least five meanings for the notion of fairness when applying to a pension system: justice, equity, neutrality, solidarity and integrity. We explain each sense of fairness and other related concepts. We also provide, when possible, a way to measure each of them, with some figures for a selected European countries.
Analysis of perfluorinated compounds in sewage sludge by pressurized solvent extraction followed by liquid chromatography–mass spectrometry
2011
Perfluorinated compounds (PFCs) are widely used in everyday life and one of the main recipients of these compounds is waste water treatment plants (WWTPs). Due to the structure and physicochemical properties of PFCs, these compounds could be redistributed from influent water to sludge. This work reports a new validated protocol for the analysis of 13 perfluorinated acids, 4 perfluorosulfonates and the perfluorooctanesulfonamide. The present work has been focused to develop a sensitive and robust method for the analysis of 18 PFCs in sewage sludge, based on pressurized solvent extraction (PSE) followed by solid phase extraction (SPE) clean-up, analytes separation by liquid chromatography and…
The composition of near-solidus melts of peridotite in the presence of CO2 and H2O between 40 and 60 kbar
2009
Abstract Partial melting experiments at 40, 50 and 60 kbar pressure on three peridotite compositions with 0.5–0.63 wt.% H2O and 2.0–3.2 wt.% CO2 added indicate melting temperatures only marginally above continental geotherms. Most experiments were performed on a composition with 1.5 wt.% K2O added, which causes a further decrease of about 40 °C in melting temperature. Melts progress gradually from carbonate-rich to carbonated silicate in composition: near-solidus melts have Ca/(Ca + Mg) of 0.46–0.53, which fall to 30 wt.%) and Al2O3 ( 9 wt.%) and concomitant decrease in CaO (> 20 to Partial melts of peridotite with CO2 and H2O are too low in MgO to resemble kimberlites, but will act as ef…
Dielectric Properties of the 0.05PZN–0.95PSN Ferroelectric Ceramics at Low and Infra-Low Frequencies
2005
Manifestations of relaxor properties similar to those observed in lead magnesium niobates are reported in the 0.05PZN–0.95PSN ceramic solid solution system. Behaviour of the effective dielectric permittivity and dielectric loss with temperature at frequencies between 0.1 and 10 Hz at different field amplitudes are examined in ceramic samples of 0.05PZN–0.95PSN. The temperature T m of the dielectric permittivity maximum is observed to decrease with the increase of the measuring field amplitude E o . Dependence of T m on frequency at strong and weak fields is observed to follow the Fogel-Fulcher law, and the Fogel-Fulcher temperature is found to decrease with the increase of E o . Results of …
Dependence of dielectric permittivity on bias field in Pb1−xBaxSc0.5Nb0.5O3
2001
Abstract Bias field effect on the dielectric permittivity is studied in Badoped lead scandium niobate ferroelectric ceramics (PBSN-x) prepared by conventional technology. Results of this work allow to analyse the mechanism of possible formation and motion of domain and/or phase boundaries in the explored ferroelectric ceramics.
<title>Dielectric polarization in <emph type="1">x</emph>PbZn<formula><inf><roman>1/3</roman></inf>&l…
2005
Manifestation of relaxor properties in the x PbZn1/3Nb2/3O3-(1-x )PbSc1/2Nb1/203 ceramic solid solution system, similar to those observed in lead magnesium niobates, are reported. Dependence of the effective dielectric permittivity and dielectric loss on the temperature at frequencies of 0.1-10 Hz and different measuring field amplitudes E 0 are examined ceramic samples of 0.05PbZn1/3Nb2/3O3-0.95PbSc1/2Nb1/203. It is demonstrated that the temperature at which the dielectric permittivity has a maximum, T m, decreases with the increase of E 0. The dependence of T m on the frequency in both strong and weak fields is shown to follow the Vogel-Fulcher law, with Voger-Fulcher temperature decreasi…
New ferroelectric materials on the basis of PbSc1/2Nb1/2O3–PbLu1/2Nb1/2O3 solid solutions
2004
Abstract Original binary solid solutions PbSc 1/2 Nb 1/2 O 3 –PbLu 1/2 Nb 1/2 O 3 (PSN-PLuN) have been produced. First of all nominally pure PSN and PLuN were synthesized by solid state reaction from oxides and carbonates. These compounds were mixed in different proportions to obtain (1− x )PSN− x PLuN solid solutions. Ceramic samples were hot-pressed at gradual change of the temperature. Solid solutions have the perovskite structure and are completely soluble in each other. Differential thermal analysis and X-ray diffraction were used to examine the synthesis and phase constitution. Dielectric properties—dielectric permittivity e and dielectric loss tan δ of ceramic samples of originally s…
Dielectric spectroscopy measurements of the sub-Tg relaxations in amorphous ethyl cellulose: A relaxation magnitude study
2005
Amorphous ethyl cellulose exhibits three secondary relaxations at temperatures below its glass transition. The fitted parameters that describe these processes and the comparison with other polysaccharides allow to ascribe the relaxations to lateral groups on one hand and to local main chain motion on the other hand. Their contributions to the dielectric constant overlap and induce a broad dielectric losses peak. The amplitude of one of these relaxations is found to decrease regularly with time. It is believed it comes from a gradual change of the polar groups chemical environment that constrains their motion.
Influence of Unaxial Pressure on Electric Properties of (1-x)PSN-xPLuN Solid Solutions (0.75 ≤ x < 1)
2007
(1-x)PSN-xPLuN ceramics with single phase perovskite structure and rhombohedral symmetry at room temperature were prepared by solid-state reaction method. The influence of unaxial pressure (0–1500 bars) on dielectric properties of these compounds were studied. It is found that these materials are sensitive to external stress. This includes the shift of phase transitions, diffuseness of dielectric permittivity characteristics and the decrease of the thermal hysteresis of the permittivity and field-polarization hysteresis. These changes of properties could be connected with the change in domain structure, the elastic change of distances between ions and the change in defects density.