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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 13 (1957), S. 104-105 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Measurements of the radiogenic87Sr/87Rb ratio of the chondritic meteorite Forest City are discussed in the light of a new determination of the half-life of87Rb. Earlier conclusions are confirmed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 54 (1992), S. 451-466 
    ISSN: 1432-0649
    Keywords: 32.80.-t ; 42.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study the influence of spontaneous emission on atom diffraction by a standing wave laser field. We characterize, analytically, the major regimes of the near-resonant Kapitza-Dirac effect and study, numerically, the influence of spontaneous emission. In particular, we discuss in some detail two important classes of two-beam resonances which are major candidates to develop effective atom beam splitters, the so-called Bragg and Doppleron resonances.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 68 (1977), S. 449-460 
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The use of adsorption effects at the electrode surface is exemplified to find out the end point of a reaction. Electrodes are distinctly polarized due to their surface defects in very dilute solutions. When both the negative and positive ions are adsorbed, the potential changes radically. The radical change of colloidal charge causes potential change of inert electrodes due to a field effect. The overpotential of polarizable electrodes is influenced by the different adsorbed species. The given examples hold good for microanalysis and trace analysis due to the lack of diaphragm and the unusual sharp end point.
    Notes: Zusammenfassung Anhand von Beispielen warden verschiedene Möglichkeiten gezeigt, Adsorptionseffekte an Elektroden zur Indikation auszunutzen: Unpolarisierbare Elektroden zeigen, wenn sie oberflachengestört sind, bei kleiner Meßionenkonzentration eine deutliche Adsorptionspolarisierung. Werden beide Reaktionspartner adsorbiert, erfolgt eine Umladung. Solumladungen können über einen Feldeffekt auf inerte Metallelektroden erkannt werden. Die Überspannungen polarisierbarer Elektroden werden durch unterschiedliche adsorbierte Schichten beeinflußt. Allen beschriebenen Methoden ist gemeinsam, daß sie wegen des fehlenden Diaphragmas im Mikromaßstab und wegen der ungewöhnlichen Schärfe der Indikation im Spurenbereich Vorteile gegenüber herkΩmlichen Indikationsmethoden bringen.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 42 (1979), S. 365-373 
    ISSN: 1432-1246
    Keywords: Experimental Cadmium-poisoning ; Lipophilic chelating agents ; ICRF 159 and ICRF 154 ; Stability constants ; Urinary excretion of cadmium ; Kidney ; Experimentelle Cadmium-Vergiftung ; lipophile Chelatbildner ICRF 159 und ICRF 154 ; Stabilitatskonstanten ; Cadmium-Ausscheidung im Urin ; Niere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 24 Std. nach einmaliger ip Injektion von 0,02 mMol Cd (als CdS04)/kg Körpergewicht wurden männliche Ratten täglich mit 0,08 mMol ICRF 159 und ICRF 154/kg Körpergewicht 10 Tage lang behandelt. Die Wirkung dieser Substanzen, lipophiler Derivate der Äthylendiamintetraessigsäure (ÄDTE) wurde im Vergleich zur hydrophilen Verbindung CaNa2ÄDTA (CalciumedetatR) bei äquimolarer Dosierung untersucht. Die mit flammenloser Atomabsorptionsspektrometrie (AAS) bestimmte Cd-Ausscheidung im Rattenurin stieg nach ICRF 159-Behandlung auf das 50-fache, nach ICRF 154 auf das 6-fache des Kontrollwertes unbehandelter Tiere an. ICRF 159 and CalciumedetatR zeigten gleiche Wirkung. Nephrotoxische Effekte der Chelatbildner werden nach histologischen und biochemischen Untersuchungen nicht beobachtet. Im Gegensatz zu ÄDTE bildeten ICRF 159 and ICRF 154 mit Cd in vitro nur schwache Komplexe. Im Hinblick auf die Wirkung der Bis-dioxopiperazine in vivo kann daher gefolgert werden, daß ausscheidungsfahige, stabile Cd-Komplexe erst nach intrazellulärer Hydrolyse der lipophilen Verbindungen gebildet werden. Die Befunde lassen es aussichtsreich erscheinen, die Wirkung der Bis-Dioxopiperazine als neue lipophile Chelatbildner bei der experimentellen Cd-Vergiftung eingehender zu untersuchen.
    Notes: Summary Twenty-four hours after single i. p. injection of 0.02 mMol Cd (as CdS04) per kg body weight, male Wistar rats received daily injections of 0.08 mMol ICRF 159 and ICRF 154 per kg body weight over 10 days. The effect of ICRF 159 and ICRF 154, which are lipophilic derivates of ethylenediaminetetraacetic acid (EDTA), were tested by comparison with CaNa2EDTA in equimolar dosage. Urinary cadmium excretion in rats was determined with flameless atomic absorptionspectrometry (AAS). After ICRF 159, the values of urinary cadmium excretion rose to 50fold, after ICRF 154 to 6fold that of untreated controls. ICRF 159 and CaNa2EDTA showed the same effect. No nephrotoxic effects of the chelating agents were assessed in histological and biochemical investigations. In contrast to their strong reactions in vivo, ICRF 159 and ICRF 154 showed poor complex formation in vitro, compared to EDTA. It was concluded that the formation of excretable stable Cd-complexes requires previous intracellular hydrolysis of the lipophilic compounds ICRF 159 and ICRF 154. The mode of action of the Bis-dioxopiperazines as new chelating agents in experimental Cd-poisoning therefore should be subjected to further investigation.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 257 (1995), S. 178-185 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 352-355 
    ISSN: 1618-2650
    Keywords: Best. von Cadmium, Zink ; Amperometrische Titration ; ÄGTA, Kohlepasteelektrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Cadmium and zinc can be determined in a single titration in the following manner: To the sample solution an ammonia/ammoniumchloride buffer is added to make the ammonia concentration 1,0–1,2 M (pH ca. 10). The titration is performed with amperometric indication using a carbon paste electrode and EGTA [ethyleneglycol-bis-(2-aminoethylether)-tetra acetic acid] as the titrant. After the end point for cadmium, excess amount of calcium-EDTA complex is added, and zinc is successively titrated with EGTA. The influences of iron(III), copper(II), lead(II) and manganese(II) have been examined. The conditions for carbon paste electrode indication have also been studied.
    Notes: Zusammenfassung Cadmium und Zink können in einer einzigen Titration folgendermaßen bestimmt werden: Zu der Probelösung wird Ammoniak-Ammoniumchlorid-Puffer zugesetzt. Die Ammoniakkonzentration in der Endlösung sollte 1,0–1,2 M (pH ca. 10) betragen. Die Titration erfolgt mit ÄGTA [Äthylenglycolbis-(2-Aminoäthyläther)-tetraessigsäure] und wird amperometrisch mit der Kohlepasteelektrode indiziert. Nach dem Endpunkt für Cadmium wird ein Überschuß an CaÄDTA zugesetzt. Danach wird auch Zink mit ÄGTA titriert. Die Störungen durch Fe(III), Cu(II), Pb(II) und Mn(II) werden untersucht. Ebenso werden die Bedingungen für die Indikation mit der Kohlepasteelektrode untersucht.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 18-22 
    ISSN: 1618-2650
    Keywords: Best. von Calcium und Magnesium in Wasser ; Amperometrische Titration ; Substitutiontitration, ÄGTA, ÄDTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary It is demonstrated that magnesium can be titrated with EGTA in the presence of CaEDTA complex. On the basis of this substitution reaction, calcium and magnesium are successively titrated with EGTA, if an appropriate amount of CaEDTA is added after having reached the end point for calcium. Both end points are indicated amperometrically using a thallium oxide anode. The method has been tested for analysis of tap and mineral water. Larger amounts of manganese(II) render the calcium result too high. Moreover, the indication of both end points is affected by the electrode position of an inactive MnO2-layer onto the Tl2O3-layer. Reducing agents destroy the Tl2O3-layer. These interferences can be overcome by addition of an appropriate amount of manganate(VII) to the sample.
    Notes: Zusammenfassung Magnesium kann mit ÄGTA in Gegenwart des CaÄDTA-Komplexes titriert werden. Auf der Grundlage dieser Substitutionstitration können Calcium und Magnesium nacheinander mit ÄGTA titriert werden, wenn nach dem Endpunkt für Calcium eine ausreichende Menge CaÄDTA zugesetzt wird. Beide Endpunkte werden amperometrisch mit Hilfe einer Thalliumoxidelektrode angezeigt. Die Methode wurde an Leitungswasser und Mineralwasser geprüft. Größere Mengen Mangan(II) bewirken zu hohe Calciumwerte. Darüber hinaus wird die Indikation beider Endpunkte dadurch beeinträchtigt, daß sich eine inaktive MnO2-Schicht auf der Tl2O3-Schicht elektrolytisch abscheidet. Reduzierende Stoffe zerstören die Tl2O3-Schicht. Diese Störungen können durch Zugabe von Permanganat vermieden werden.
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  • 8
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-8951
    Keywords: Transition metal complexes ; nickel(II)-complexes ; liquid crystals ; magnetism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis, characterization, thermal behavior and magnetic properties of a number of bis[2′-(4-alkyloxyphenyl)malondialdehyde] nickel(II) complexes are reported. X-ray studies of the nickel(II) complexes were performed. It was found that the nickel(II) complexes show liquid-crystalline smectic A phases over a broad temperature range with low melting points. The temperature-dependent magnetic susceptibility measurements of the bis[2′-(4-decyloxyphenyl)malondialdehyde] nickel(II) complex were carried out in the range of 4.2–480 K. The temperature dependent magnetic susceptibilities and magnetic moments of this compound (μeff=3.27 μ B at 300 K) indicate that the nickel centers are octahedrally coordinated. Models for the molecular arrangement in the crystalline and liquid-crystalline phases are discussed on the basis of the magnetic data. In spite of the oxygen bridge between the nickel centers, no exchange interactions were found in the crystalline and liquid-crystalline phases.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 13 (1989), S. 171-178 
    ISSN: 1434-6079
    Keywords: 35.20.V ; 35.20.W ; 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Distinct temperature effects could be observed in the threshold regions of photoionisation efficiency (PIE) measurements of sodium clusters. Simulations of the PIE thresholds at various temperatures were carried out with a simple, semiclassical model. Fitting the simulations to the experimental data allows to correct ionisation potential assignments for thermal effects and estimate internal temperatures of polyatomic sodium clusters.
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