Contamination artificielle des cuves chromatographiques. Effets qualitatifs et quantitatifs.

Résumé Nous avons montré que la contaminationartificielle de la cuve chromatographique est un moyen simple et efficace pour agir sur les dimensions des taches, comme sur leurs vitesses de migration. L'effet peut affecter les résultats du dosage des taches chromatographiées comme il a été démontré pour les dosages de chromate et de tungstate. L'erreur de dosage est passée de 20 à 3% sur 10 microgrammes. Douze couples de saturants et développants ont été utilisés avec divers contaminants. L'effet de contamination a été suivi qualitativement sur le développement de huit éléments.Les actions conjuguées sur l'atmosphère de la cuve chromatographique et sur la composition du développant peuvent être efficaces lorsque l'on est à la recherche des meilleures conditions chromatographiques de séparation.L'action sur le saturant présente l'avantage de permettre l'intervention de solvants non miscibles ou non solubles l'un dans l'autre.

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Summary It has been shown that the artificial contamination of the chromatographic cell is a simple and efficient means for learning the dimensions of stains, such as their migration velocities. The effect may affect the determination of chromatographic stains as has been shown in the case of chromate and tungstate. Twelve pairs of saturants and developers have been employed with various contaminants. The effect of the contamination has been followed qualitatively in the development of eight elements.The conjugated actions on the atmosphere of the chromatographic cell and on the composition of the development may be effective when the object is to discover better chromatographic conditions of separation.The action on the saturant presents the advantage of allowing the intervention of solvents which are not miscible or not soluble in each other.

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Zusammenfassung Wir konnten zeigen, daß Zumischungen zu der Atmosphäre in Chromatographie-Gefäßen ein einfaches und wirksames Mittel zur Beeinflussung der Fleckengröße und der Wanderungsgeschwindigkeit darstellen. Diese Wirkung kann die Resultate bei der Auswertung chromatographischer Flecken verbessern, wie an der Bestimmung von Chromat und Wolframat gezeigt werden konnte. Der Analysenfehler ging bei Verwendung von 10 g von 20% auf 3% zurück. Zwölf Paare von Sättigungs- und Entwicklungsflüssigkeiten wurden mit verschiedenen Zusätzen verwendet. Die Wirkung der Zumischung auf die Chromatogrammentwicklung wurde qualitativ bei acht Elementen verfolgt.Die gleichzeitige Veränderung der Atmosphäre und der Zusammensetzung der beweglichen Phase kann sich bei der Suche nach geeigneten Versuchsbedingungen für die chromatographische Trennung erfolgreich auswirken.Die Veränderung der Zusammensetzung des Sättigungsmittels bietet den Vorteil der gegenseitigen Einwirkung miteinander nicht mischbarer oder ineinander nicht löslicher Lösungsmittel.

     

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Milliwatt-peak-power pulse characterization at 1.55 microm by wavelength-conversion frequency-resolved optical gating

A novel wavelength-conversion configuration based on four-wave mixing in an optical fiber has been used to generate a frequency-resolved optical gating (FROG) trace identical to that obtained from second-harmonic generation (SHG). The use of an optical fiber waveguide permits enhanced measurement sensitivity compared with that of conventional SHG-FROG and has been used for complete characterization of 1-mW peak-power picosecond pulses at 1.55 microm from an unamplified semiconductor laser diode gain switched at 10 GHz.     

Neutron dosimetry at low and high fluences with CR-39

In the Laboratory of Nuclear Microanalysis, we have developed two techniques for neutron dosimetry; the first for low fluence, the second for high fluence. These two techniques use a Solid State Nuclear Track Detector (SSNTD): the CR-39. The low fluence technique is based on the measurement of etched tracks resulting from a neutron-proton conversion. A Monte Carlo code performs a simulation of the (n,p) collision in the detector, and a numerical computer code of latent track etching allows the evaluation of the etched track parameters. The object of this is to obtain characteristics of a neutron fluence from the measured etched track parameters. When there is a high fluence and high doses, CR-39 is unsuited for optical microscopy analysis. This is because of track overlapping which makes it impossible to carry out counting and exploitation. We have therefore developed a new method permitting the reading of samples based on the measurement of the angular distribution of coherent light (He---Ne laser) transmitted through the irradiated etched SSNTD. We present these two techniques and our initial results.     

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Transmission d'images et d'hologrammes par une nappe de fibres optiques au moyen d'un codage chromatique

A new method of addition of 2-D complex optical signals is proposed. The addition is performed by suitably matched spatial filtering. For that purpose the effect of compacting of periodic objects images is employed.     

Construction of an interferometric gauge system for thickness measurement in white light

A thickness gauge based on channelled spectrum phenomena is described. Compared with other interferometric systems, the instrument is characterized by its low cost while retaining a high sensitivity and a wide range of measurement. Its use can be extended to the determination of any absolute optical delays; applications dealing with surface roughness testing and control of the dimensional stability of silicon rubbers are mentioned.     

Contribution au microdosage titrimétrique de l'iode organique

Simultaneous microdetermination of carbon, hdrogen and iodine in organic substances is practically possible on a five milligramme sample. The two first mentioned elements are gravimetrically deetermined, iodine being titrated. The available results are quite good.New calibration technique of capillary instruments enables precise titration of very small quantities of Iodine. It will help to improve precision of this determination.     

Une microburette horizontale automatique perfectionnée

Sans résuméAvec 4 figures.