Search results for "passiv"
showing 10 items of 512 documents
Zerstörungsfreie Phasenanalyse dünner Oberflächenschichten mittels Konversionselektronen
1987
By use of an appropriate gamma radiation, conversion electrons may be produced by Mossbauer effect also in a depth below the sample surface deeper than the free path for inelastic electron scattering. Because the Mossbauer spectrum of the conversion electrons reflects the local phase composition, the recording of all electrons escaping from the surface allows an integral phase analysis of a layer of some 10–100 nm thickness. If only electrons within a narrow range of energy are recorded, a depth selective phase analysis is possible. The applicability of these two techniques of conversion electron spectroscopy is demonstrated by a few examples concerning oxidation and passivation of steel. C…
Determination of time dependence of passive layer on nickel from instantaneous mass/charge function F(dm/dQ) in competitive passivation/dissolution c…
2006
Nickel metal deposited on gold electrodes was studied in the passivity range of potentials under potentiostatic conditions and in a weakly acid sulphate medium. Mass and current variations during electrochemical experiments were analysed with the help of the instantaneous mass/charge ratio (Fdm/dQ). This analysis allows to obtain the intensity current component associated to the formation of a passive layer of Ni(OH)2, and, in this way, the experimental thickness growth. These experimental findings have been fitted to a theoretical model based on the point defect model theory for obtaining the time dependence of the thickness of the passive layer during the first stages of growth of the pas…
Air movement representation as a tool for urban and architectural environmental quality
2017
Air movement is a measurable physical phenomenon that produces indirectly measurable effects on people and on the environment. It is an essential prerequisite for the comfort and the hygiene of the built environment and it is highly relevant to the passive cooling strategies. The relationships between air movement and built environment have to be analysed under a multi-scale vision. They fall within the field of urban and architectural design because they can be influenced by artificial expedients, although they are always caused by natural factors. This paper discusses the need for a complete and objective representation of different kinds of air movement, to improve the urban and architec…
A Proposed Methodology to Control Body Temperature in Patients at Risk of Hypothermia by means of Active Rewarming Systems
2014
Hypothermia is a common complication in patients undergoing surgery under general anesthesia. It has been noted that, during the first hour of surgery, the patient’s internal temperature (Tcore) decreases by 0.5–1.5°C due to the vasodilatory effect of anesthetic gases, which affect the body’s thermoregulatory system by inhibiting vasoconstriction. Thus a continuous check on patient temperature must be carried out. The currently most used methods to avoid hypothermia are based on passive systems (such as blankets reducing body heat loss) and on active ones (thermal blankets, electric or hot-water mattresses, forced hot air, warming lamps, etc.). Within a broader research upon the environment…
Passive Transport of Ionic Drugs through Membranes with pH-Dependent Fixed Charges
2001
We have studied both theoretically and experimentally the passive transport of ionic drugs through membranes with pH-dependent fixed charge. The system considered constitutes a simplified model for pH-controlled drug delivery through membranes of biochemical and pharmaceutical interest. The theoretical approach employed is based on the Nernst-Planck flux equations and all of the species present in the system (the neutral or ionic drug and the hydrogen and hydroxide ions) have been taken into account together with a Langmuir-type isotherm for the adsorption of the ionic drug onto the membrane surface. The membrane permeabilities of cationic, anionic, and neutral drugs through porous membrane…
Determinants of self-reported smoking and misclassification during pregnancy, and analysis of optimal cut-off points for urinary cotinine: a cross-se…
2013
10 p. Objectives: To estimate the prevalence and factors associated with smoking and misclassification in pregnant women from INMA (INfancia y Medio Ambiente, Environment and Childhood) project, Spain, and to assess the optimal cut-offs for urinary cotinine (UC) that best distinguish daily and occasional smokers with varying levels of second-hand smoke (SHS) exposure.-- Design: We used logistic regression models to study the relationship between sociodemographic variables and self-reported smoking and misclassification (self-reported non-smokers with UC >50 ng/ml). Receiver operating characteristic (ROC) curves were used to calculate the optimal cut-off point for discriminating smokers. The…
El rol cambiante de los recursos personales en la empleabilidad percibida de los jóvenes en diferentes condiciones del mercado de trabajo
2020
Personal resources and labor market are factors that contribute to perceived employability. However, how changing labor market conditions affect the relationship between personal resources like career enhancing strategies, personal initiative, and career passivity with self-perceived employability remains unclear. Recent events in Spain give an opportunity to examine if personal resources predict perceived employability differently during normal and harsh labor conditions. Two representative samples of young people were surveyed during a normal labor condition (in 2008, before the big recession, n = 1,992) and a harsh condition (in 2011, with 46% young unemployment rate, n = 1,208). …
Design of Implanted RFID Tags for Passive Sensing of Human Body: The STENTag
2012
Numerical processing of passive UHF-RFID tags' response may provide physical insight about the hosting object or about the nearby environment. This idea is here extended to implanted antennas with the purpose to sense the evolution of some human physiological and pathological process involving a local change of effective permittivity inside the body. The goal is to understand how master the design of this class of devices taking into account both communication and sensing capabilities. An ad hoc design methodology is here presented and discussed by means of a realistic medical case concerning the modification of an endo-vascular device to achieve a STENTag able to sense the state of the ves…
Retention-activity relationship studies of benzodiazepines by micellar liquid chromatography
1999
Solute partitioning into lipid bilayers of biological membranes is the basis for drug and metabolite uptake, passive transport across membranes and bioaccumulation. In order to emulate in vitro the partitioning process in the biomembranes, different approaches have been proposed. The use of micellar solutions as mobile phases in reversed-phase liquid chromatography (micellar liquid chromatography, MLC) has proven to be valid in the prediction of the biological activities of local anesthetics, catecholamines and barbiturates. In this paper we focus our attention on benzodiazepines. The retention of benzodiazepines using different concentrations of Brij35 as micellar mobile phase in modified …
Development of predictive retention-activity relationship models of antipsychotic drugs by micellar liquid chromatography
1999
The predictive and interpretative capability of quantitative chromatographic retention-biological activity models is supported by the fact that in adequate experimental conditions the solute partitioning into the chromatographic system can emulate the solute partitioning into lipid bilayers of biological membranes, which is the basis of drug and metabolite uptake, passive transport across membranes and bioaocumulation. The use of micellar solutions of Brij35 as mobile phases in reversed liquid chromatography has proven to be valid in predicting some biological activities of different kinds of drugs. In this paper, the correlations between the logarithm of capacity factors and pharmacokineti…