Einfluß einiger Legierungselemente auf die Festigkeitssteigerung von Stählen durch eine Austenitformhärtung

Zugversuche mit Ermittlung der üblichen Kennwerte und teils auch der 0,01-Grenze an austenitformgehärteten, anschlieβend bis zu 700°C angelassenen und an nach der gleichen Temperatur-Zeit-Folge “lediglich” vergüteten Proben aus fünf Stählen mit jeweils rd. 0,35% C, 5% Cr und dazu Legierungsanteilen in wechselnder Kombination von 1,6% Si, 3,0 bis 3,25% Co und 3,15 bis 3,3% Ni. Erörterung der Ergebnisse vor allem mit Folgerungen über die bei unterschiedlichem Umformgrad der Austenitformhärtung im Gefüge maβgeblichen Verfestigungsvorgänge.     

Enhancing interference rejection of preamplified electrodes by automated gain adaption

The use of preamplified electrodes in electrocardiography (ECG) or electroencephalography (EEG) has a numbe of benefits, most importantly, the noise reduction through preamplification and the interference reduction through buffering (Fernandez and Pallas-Areny, 1997). Normally, preamplified electrodes are not used because the mismatch in amplification due to component tolerances leads to a reduced common mode rejection ration (CMRR) (Pallas-Areny and Webster, 1991). In this paper, we introduce a new technique to restore the CMRR. We do this by adapting the gain of the differential amplifier (DA) following the preamplified electrodes. The technique is based on measuring the transfer function of a chosen common mode signal. The gain of the DA is adjusted by a closed loop controller to maximize the CMRR. With this technique, there is no adverse effect on the ECG or EEG. In this way, the control loop can be operated continuously if needed.     

Accuracy of continuous ice-core trace-element analysis by inductively coupled plasma sector field mass spectrometry

Trace elements trapped in glaciers are important indicators for the characterization of past biogeochemical cycles, the identification of numerous sources and their varying strength, and thus indirectly provide insight into past climate variations. However, this necessitates highly resolved and continuous records of trace elements in ice. To obtain records corresponding to these requirements, a continuous ice-core melting (CIM) device was coupled to an inductively coupled plasma sector field mass spectrometer (ICP-SFMS). Accuracy of this newly developed method was tested by replicate analysis of longitudinally cut ice-core sections (reproducibility) and by comparing results of the continuous method with the conventional decontamination and analysis procedure. The new, fast method is suited to accurately determine concentrations of a number of elements, such as Li, Na, Mg, Ca, Mn, Co, Br, Sr, Mo, and Tl. However, for 18 elements (including Al and lanthanides) observed concentrations were underestimated when analyzed using the continuous method. Possible explanations of these low concentrations are (i) incomplete dissolution of mineral dust particles contained in the ice resulting from a delayed acidification step and/or (ii) adsorption of dissolved trace elements or mineral dust particles on the surface of the ice melting device.