Optimierung spektrometrischer Verfahren durch ein Datenverarbeitungssystem

Einsatz von Prozeßrechnern in Laboratorien. Aufbau eines Systems zur Produktionsüberwachung eines Sauerstoffaufblasstahlwerkes. Beschreibung des Rechners und der Programmgestaltung. Ablauf der emissionsspektrometrischen und röntgenfluoreszenzspektrometrischen Roheisen-, Stahl- und Schlackenanalysen. Erste Ergebnisse und Erfahrungen.     

Einfluß von Werkstoffzusammensetzung und Ferritkorngröße auf die Konstanten der Ludwik-Gleichung

Beschreibung der Spannung-Dehnung-Kurve ferritischer und ferritisch-perlitischer Stähle mit der Ludwik-Gleichung. Einfluß der Korngröße auf den Vorfaktor der Ludwik-Gleichung. Anstieg des Vorfaktors mit zunehmendem C- und Mn-Gehalt sowie mit steigendem Perlitanteil am Gefüge. Korngrößenunabhängigkeit des Verfestigungsexponenten. Einfluß des C- und Mn-Gehaltes auf den Verfestigungsexponenten.     

Entschwefelung von Eisenschmelzen über die Schlackenphase unter oxidierenden Bedingungen

Darstellung und Eigenschaften der festen Oxidsulfide. Das Oxid-Sulfid-System Fe–FeO_n–CaO–CaS–FeS. Schwefelverteilung zwischen dicalciumsilicatgesättigten Schlacken und der Eisenphase. Sulfide und Oxidsulfide in erstarrten dicalciumsilicatgesättigten Schlacken. Metallurgische Schlußfolgerungen.     

Effects of atmospheric ozone on microarray data quality

A data anomaly was observed that affected the uniformity and reproducibility of fluorescent signal across DNA microarrays. Results from experimental sets designed to identify potential causes (from microarray production to array scanning) indicated that the anomaly was linked to a batch process; further work allowed us to localize the effect to the posthybridization array stringency washes. Ozone levels were monitored and highly correlated with the batch effect. Controlled exposures of microarrays to ozone confirmed this factor as the root cause, and we present data that show susceptibility of a class of cyanine dyes (e.g., Cy5, Alexa 647) to ozone levels as low as 5-10 ppb for periods as short as 10-30 s. Other cyanine dyes (e.g., Cy3, Alexa 555) were not significantly affected until higher ozone levels (> 100 ppb). To address this environmental effect, laboratory ozone levels should be kept below 2 ppb (e.g., with filters in HVAC) to achieve high quality microarray data.     

Formaldehyde in human cancer cells: detection by preconcentration-chemical ionization mass spectrometry

A rapid and highly sensitive method for the detection of formaldehyde utilizing selected ion flow tube-chemical ionization mass spectrometry is reported. Formaldehyde in aqueous biological samples is preconcentrated by distillation and directly analyzed using gas-phase thermal energy proton transfer from H30+; this procedure can be performed in 30 min. The method detection limit for formaldehyde based on seven replicate measurements of reference water samples (2.5 mL) is 80 nM at the 99% confidence level. Detection is linear up to 130 microM. This technique allows the first measurement of natural formaldehyde levels in human cancer cells in vitro. Elevated levels of formaldehyde relative to the reference water are observed for doxorubicin-sensitive cells (MCF-7 breast cancer, K562 leukemia, HeLa S3 cervical cancer) with estimated intracellular formaldehyde concentrations ranging from 1.5 to 4.0 microM, whereas formaldehyde in doxorubicin-resistant MCF-7/Adr breast cancer cells is essentially at reference level. This trend is inverted for prostate cancer cells LNCaP (sensitive) and DU-145 (resistant). Correlation of natural formaldehyde level with doxorubicin cytotoxicity is a function of the expression of enzymes that neutralize oxidative stress and the drug efflux pump, P-170 glycoprotein.     

Brazing of metallic conductors onto ceramic plates in solid oxide fuel cells Part 1 Attaching a current collector

Furnace brazing to attach metallic plates to LaCrO₃ end plates in solid oxide fuel cell (SOFC) was investigated. The metallic plates act as a current collector to which a few conducting wires made of conventional heat-resisting alloys can be attached. The alloy CrFe5Y₂O₃1 was found to be a suitable material for the current collector because its thermal expansion coefficient matches that of LaCrO₃ better than heat-resisting nickel- or iron-based alloys. Among various filler alloys tested, SCP6 (Cu with 18 wt% Pd) enables the best wetting of LaCrO₃ and CrFe5Y₂O₃1 plates, leading to good adhesion between them. Several approaches were successfully pursued to reduce the bending of brazed LaCrO₃/SCP6/CrFe5Y₂O₃1 joints. The area specific resistance of some LaCrO₃/SCP6/CrFe5Y₂O₃1 joints increased slightly during annealing (1000°C in air for 2400 h) due to oxidation in the filler alloy. Nevertheless, it remained below the target limit of 0.2 · cm².     

Counting and Integrating Readout for Direct Conversion X-ray Imaging: Concept, Realization and First Prototype Measurements

A novel signal processing concept for X-ray imaging with directly converting pixelated semiconductor sensors is presented. The novelty of this approach compared to existing concepts is the combination of charge integration and photon counting in every single pixel. Simultaneous operation of both signal processing chains extends the dynamic range beyond the limits of the individual schemes and allows determination of the mean photon energy. Medical applications such as X-ray computed tomography can benefit from this additional spectral information through improved contrast and the ability to determine the hardening of the tube spectrum due to attenuation by the scanned object. A prototype chip in 0.35-micrometer technology has been successfully tested. The pixel electronics are designed using a low-swing differential current mode logic. Key element is a configurable feedback circuit for the charge sensitive amplifier which provides continuous reset, leakage current compensation and replicates the input signal for the integrator. This paper will discuss measurement results of the prototype structures and give details on the circuit design