Search results for "solution"
showing 10 items of 5638 documents
Fiber-Optic Aqueous Dipping Sensor Based on Coaxial-Michelson Modal Interferometers
2009
Fiber-optic modal interferometers with a coaxial-Michelson configuration can be used to monitor aqueous solutions by simple dipping of few centimeters of a fiber tip. The fabrication of these sensors to work around 850 nm enables the use of compact, robust, and low-cost optical spectrum analyzers. The use of this type of portable sensor system to monitor sewage treatment plants is shown.
A sequence of positive solutions for sixth-order ordinary nonlinear differential problems
2021
Infinitely many solutions for a nonlinear sixth-order differential equation are obtained. The variational methods are adopted and an oscillating behaviour on the nonlinear term is required, avoiding any symmetry assumption.
Application of sequential injection analysis to pharmaceutical analysis.
2005
Sequential injection analysis is a well established tool for automation of pharmaceutical analysis. A short historical background of this technique is given as well as a brief discussion on the basic principles and potentials. The current applications of SIA in the pharmaceutical analysis are also described and discussed. The manifolds developed offer good analytical characteristics and are suitable for analysis of drug formulations, process analysis, drug-dissolution, drug-release testing and functional assays for screening potential drugs. The results obtained are in good agreement with those furnished by the application of the reference methods presented in the pharmacopoeias.
Risedronate complexes with Mg2+, Zn2+, Pb2+, and Cu2+: Species thermodynamics and sequestering ability in NaCl(aq) at different ionic strengths and a…
2021
Abstract In this paper, potentiometry and calorimetry were used to determine the thermodynamics of interaction between risedronate and four bivalent metal cations, namely: Mg2+, Zn2+, Pb2+, and Cu2+ in aqueous NaCl solutions at different ionic strengths and at T = 298.15 K. The data analysis allowed us to ascertain that the main species formed were the MLH2, MLH, ML and M2L; however scarcely soluble species precipitated at acidic pH values, between 4 and 7 depending on the metal cation involved, probably due to the formation of the neutral M2L(s) species. Comparison of the stability constants with other similar ligands suggests that metal complexation occurs through the phosphonate with an …
Sequestering ability of polyaminopolycarboxylic ligands towards dioxouranium(VI) cation
2006
Abstract In the present paper, some results of an investigation (at t = 25 °C by potentiometry, ISE-H+ glass electrode) on the sequestering ability of five different polyaminopolycarboxylic ligands [Nitrilotriacetate (NTA), ethylenediamine-N,N,N′,N′-tetraacetate (EDTA), ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetate (EGTA), diethylenetriamine-N,N,N′,N″,N″-pentaacetate (DTPA), triethylenetetraamine-N,N,N′,N″,N′′′,N′′′-hexaacetate (TTHA)] towards dioxouranium(VI) cation in sodium chloride aqueous solutions, at I = 0.7 mol L−1 are reported. Calculations performed on potentiometric data gave evidence of the formation of the following species (log β in parenthesis): UO2(NTA)H0 (12…
Sequestration of (CH3)Hg+ by amino‐polycarboxylic chelating agents
2012
Abstract The speciation of mono-methylmercury(II) cation (MeHg+) in the presence of Nitrilotriacetate (NTA), Ethylenediamine-N,N,N′,N′-tetraacetate (EDTA), diethylenetriamine-N,N,N′,N″,N″-pentaacetate (DTPA) and (S,S)- Ethylenediamine-N,N′-disuccinic acid (S,S-EDDS) was investigated at I = 0.1 mol L− 1 (NaCl) with the aim to assess a trend of sequestering capacity of the amino‐polycarboxylic (APCs) ligand class towards this cation in aqueous solution. The results obtained gave evidence for the formation of a mononuclear [MeHg(APC)] complex species, differently protonated MeHg(HiL) species (i = 1 to 3, depending on the APC considered), a mixed hydroxo species [MeHg(APC)(OH)] and a binuclear …
Time Series Corrections and Analyses in Thermal Remote Sensing
2013
The time span of surface thermal data bases now reaches a few decades. However, studies using surface thermal time series are seldom, due to the difficulty of obtaining temporally coherent estimations for this parameter. Applications for surface thermal multitemporal analysis range from climate change studies and modeling to anomaly detection for natural or industrial hazard detection. This chapter presents methods to improve the temporal coherence of temperature time series, through data reconstruction of atmospheric and cloud contaminated observations, and through the correction of the orbital drift effect which hinders the use of the longest data sets. Then, methods for the analysis of t…
Episodios térmicos extremos analizados con productos MODIS durante el invierno boreal (2000-2016)
2016
<p>The beginning of the XXI century is characterized by the intensification of the existing global warming situation and for a series of drastic global meteorological events. Particularly, during the winter season a series of extreme temperature episodes affecting large areas of the northern hemisphere have been produced. In this paper, these episodes are studied by analyzing the thermal anomalies spatial distribution and temporal evolution in the period 2001-2016 from Land Surface Temperature (LST) products obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. The study regions considered in this investigation are eight of the northern hemisphere. The result…
Development of predictive retention-activity relationship models of tricyclic antidepressants by micellar liquid chromatography.
1999
The distribution of tricyclic antidepressants from plasma to brain, where these drugs exert their main clinical action, and other organs is related to transport events across the cell membranes of the different tissues. It could be expected that all the molecular features that condition the transport processes (mainly hydrophobicity and molar total charge) also control the pharmacokinetic and biochemical behavior. Micellar liquid chromatography (MLC) has been proposed to emulate in vitro the partitioning process in the biomembranes. The use of micellar solutions of Brij35 as mobile phases in reversed-phase liquid chromatography has proven to be valid to predict the biological activities of …
Solution-Processed Ni-Based Nanocomposite Electrocatalysts: An Approach to Highly Efficient Electrochemical Water Splitting
2021
In this study, we report an up-scalable and low-cost solution-processed method to in situ synthesize an earth-abundant non-stoichiometric NiOx-based electrocatalytic film for water oxidation. The catalytic activity was found to be inversely proportional to the baking temperature, which varied from 50 to 500 °C. We found the formation of a hybrid nanocomposite thin film of NiOx nanocrystals (<2 nm size) inside an acetate-based organic matrix at low temperatures (<200 °C). The defective and short-range structural order of the NiOx-based nanocomposite electrocatalysts, compatible with lattice stress, low electrical conductivity, and high density of catalytically active surface species, and hig…