Reversions-Gas-Chromatographie, Me?technik, Anwendung

Zusammenfassung Das kennzeichnende Merkmal der Reversions-Gas-Chromatographie ist eine integrierende Wirkung auf Spurenmengen geringster Konzentration. Durch den Gradientenofen wird eine scharfe Trennung der Substanzen und damit ein sehr hohes Verhältnis der Konzentrationssteigerung erreicht. Es wird ein FID mit besonders kurzem Weg zwischen Trennsäule und Brennerdüse beschrieben. 3 Schaltanordnungen mit Regelvorrichtungen zeigen die Möglichkeit auf, auch strömungsabhängige Detektoren bis zu ihrer Nachweisgrenze voll auszunutzen. Die Eigenschaften einer RVGC/GC-Kopplung werden an einem Beispiel gezeigt, wobei besonders auf die Möglichkeit hingewiesen wird, diese Anordnung zur Peakidentifizierung der RVGC-Trennung heranzuziehen.

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Reversion gas-chromatography, measuring technique and application

The attribute of reversion gas-chromatography is an integrant efficiency to trace amounts of lowest concentrations. By means of the gradient-oven a sharp separation and with it an exceptional raising in concentration is obtained. A FID with an especially short way between column and burner-jet is described. Three circuit diagrams with control units show the possibility to use also flow-dependent detectors up to their detection-limit. The properties of a RVGC/GC-coupling are demonstrated with special regard to the possibility to use this arrangement to identify the peaks of the RVGC-separation.

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An dieser Stelle möchte ich meinen Mitarbeitern besonderen Dank sagen. Herrn M. Klobe danke ich besonders für seine Arbeiten über die RVGC-GC-Kopplung.     

Caractéristiques des dispositifs réglabes ou régulateurs du débit de gaz; un générateur de pression moderne

Sommaire Les equations de la dynamique des gaz permettent d'élaborer quatre méthodes différentes qui sont utilisées pour maintenir constante la vitesse des gaz. Aux plus hautes exigences en matière de régulation de débit seuls répondent les systèmes régulateurs en série et les écrans, à principe adiabatique, travaillant par mesure de pression réglable. Seule cette methode peut être étalonnée et permet un contrôle quantitatif de l'étanchéite des systèmes hermétiques.     

Ratchets, power strokes, and molecular motors

We present a method for determining the effective driving potential for a molecular motor from measurements of its stochastic position versus time. In developing the method we can make precise the previously vague notions of ‘Brownian ratchet’ and ‘power stroke’, and suggest means to experimentally distinguish between the two. In particular, we distinguish between two kinds of ratchets: ratchets that rectify large fluctuations and ratchets that bias small fluctuations. Received: 24 October 2001 / Accepted: 11 February 2002 / Published online: 22 April 2002     

Automatisierung und Genauigkeit

Ohne Zusammenfassung     

Thermally and optically stimulated luminescence in LiF:Mg,Ti: Application to mixed high/low ionization density radiation dosimetry

The viability of the concepts of using existing molecular nanostructures in LiF:Mg,Ti as solid-state nanodosimeters has been demonstrated. The concepts are based on mimicking radiobiology (specifically the ionization density dependence of double strand breaks in DNA) by using the similar ionization density dependence of electron-hole capture in spatially correlated TC/LC in the thermoluminescence and the identification of OSL with the “two-hit” F₂ center.     

Reevaluation of the half-lives of87mSr,90mY and109mPd

The half-lives of^87mSr,^90mY and^109mPd have been determined more accurately, as compared to previous measurements.     

The partial molal volume and compressibility change for the formation of the calcium sulfate ion pair at 25°C

The apparent molal volumes (_v) and compressibilities (_K) of CaSO₄ solutions have been determined at 25°C from precise density and sound-speed measurements. The large deviations of the values of _v and _K from the limiting law and various additivity estimates for the free ions (Ca²⁺, SO ₄ ^2– ) have been used to estimate the partial molal volume ( ) and compressibility ( ) for the formation of the CaSO ₄ ⁰ ion pair. Values of = 25 ± 3 cm³-mole^–1 and = (54±21)×10^–4 cm³-mole^–1-bar^–1 were found. Since these values are larger than the value for the formation of MgSO ₄ ⁰ , the results indicate that more inner-sphere ion pairs are formed when SO ₄ ^2– complexes with Ca²⁺ than with Mg²⁺. Using a simple model for ion-water interactions, the percent of inner-sphere or contact ion pairs in CaSO₄ solutions is estimated to be 36 to 37%.