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Static Mode (static + mode)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Copper Ion Selective Membrane Electrodes Based on Some Schiff Base Derivatives

ELECTROANALYSIS, Issue 15-16 2003
S. Sadeghi
Abstract A series of Schiff base derivatives were studied to characterize their abilities as a copper ion carrier in PVC membrane electrodes. The electrode based on 2,2,-[4,4,diphenyl-methanebis(nitrilomethylidyne)]-bisphenol exhibits a Nernstian response for copper ions over the activity range 8.0×10,6,1.0×10,1 mol L,1 with detection limit of about , mol L,1 of copper ion in comparison with two other Schiff bases. The response time, pH effect and other characteristics of the electrodes were studied in a static mode. The effect of the methyl group substitute on Schiff base structure with SO2 bridging group in different positions with respect to OH group was studied. The results show that behavior of the electrodes is not considerably influenced by the position of methyl substitute. The selectivity coefficients were determined with modified fixed interference method (FIM) and matched potential method (MPM). The proposed electrodes comparatively show good selectivity with respect to alkali, alkaline earth and some transition metal ions. The electrodes were used for the determination of copper in black tea, multivitamin and mineral capsule and as an indicator electrode in potentiometric titration of copper ion. [source]

Laser Ablation (193 nm), Purification and Determination of Very Low Concentrations of Solar Wind Nitrogen Implanted in Targets from the GENESIS Spacecraft

GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2 2009
Laurent Zimmermann
azote; ablation laser; purification; spectrométrie de masse; mission GENESIS The GENESIS space mission recovered ions emitted by the Sun during a 27 month period. In order to extract, purify and determine the very low quantities of solar nitrogen implanted in the GENESIS targets, a new installation was developed and constructed at the CRPG (Nancy, France). It permitted the simultaneous determination of nitrogen and noble gases extracted from the target by laser ablation. The extraction procedure used a 193 nm excimer laser that allowed for surface contamination in the outer 5 nm to be removed, followed by a step that removed 50 nm of the target material, extracting the solar nitrogen and noble gases implanted in the target. Following purification using Ti and Zr getters for noble gases and a Cu-CuO oxidation cycle for N2, the extracted gases were analysed by static mode (pumps closed) mass spectrometry using electron multiplier and Faraday cup detectors. The nitrogen blanks from the purification section and the static line (30 minutes) were only 0.46 picomole and 0.47 picomole, respectively. La mission GENESIS a récupéré des ions émis par le soleil pendant une période de 27 mois. Afin d'extraire, purifier et analyser de très faibles quantités d'azote solaire implantés dans des cibles GENESIS, une nouvelle installation a été développée et construite au CRPG. Elle a permis l'analyse simultanée de l'azote et des gaz nobles extraits de la couche d'or par ablation. La procédure d'extraction a utilisé un laser Excimer 193 nm qui a permis une étape d'extraction à 5 nm pour éliminer la pollution à la surface, suivie d'une étape qui a extrait jusqu'à une profondeur de 50 nm l'azote et les gaz rares solaires implantés dans la cible. Après une purification à l'aide de getters Ti et Zr pour les gaz rares et un cycle d'oxydation Cu-CuO pour N2, les gaz extraits ont été analysés en mode statique (pompage fermé) par spectrométrie de masse à l'aide d'un multiplicateur d'électrons et d'une cage de Faraday. Les blancs d'azote provenant de la partie purification et de la ligne en statique (30 minutes) étaient de seulement 0.46 et 0.47 picomole, respectivement. [source]

Continuous recording of accommodation and pupil size using the Shin-Nippon SRW-5000 autorefractor

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 2 2001
J. S. Wolffsohn
Summary A newly released commercial autorefractor, the Shin-Nippon SRW-5000 (Japan), has been found to be valid compared to subjective refraction and repeatable over a wide prescription range. Its binocular open field-of-view allows the accommodative state to be monitored while a natural environment is viewed. In conventional static mode, the device can take up to 45 readings in 1 min using digital image analysis of the reflected retinal image of a measurement ring. Continuous on-line analysis of the ring provides high (up to 60 Hz) temporal resolution of the refractive state to an accuracy of <0.001 D. Pupil size can also be analysed to a resolution of <0.001 mm. The measurement of accommodation and pupil size was relatively unaffected by eccentricity of viewing up to ±10° and instrument focusing inaccuracies of ±5 mm. The resolution properties of the analysis are shown to be ideal for measurement of dynamic accommodation and pupil responses. [source]

A continuous flow mass spectrometry technique of argon isotope measurement for K/Ar geochronology,

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2009
Alexander V. Ignatiev
A new method for the measurement of argon isotope composition in a continuous flow of helium for potassium/argon geochronology is described. Extraction of argon from geological samples in multiple-sample holders was carried out in a chamber by heating with a continuous Nd-YAG laser. The extracted and pre-concentrated argon is passed through a chromatographic capillary column in a flow of helium. Argon is separated from possible contaminants in the column and is injected through an open split into the ion source of an isotope ratio mass spectrometer. Measurement of the 36Ar, 38Ar and 40Ar isotopes was carried out in dynamic mode, using a triple-collector ion detector. These experiments have shown that continuous flow mass spectrometry can be used for the analysis of radiogenic argon in picogram quantities with an accuracy that is satisfactory for the solution of many geochronological problems. The method of argon isotope measurement in a continuous flow of helium is an alternative to the measurement of argon isotopes in the static mode. The sensitivity and accuracy of argon measurement by this method are comparable with those provided by the classical static method. The measurement of argon isotopes in a continuous flow of helium is simpler and more reliable than measurement in the static mode. Copyright © 2009 John Wiley & Sons, Ltd. [source]