Extraktionsapparate

Ohne Zusammenfassung     

Determination of 13CO2/12CO2 Ratio by IRMS and NDIRS

Abstract

Breath tests using ¹³C-labelled substrates require the measurement of ¹³CO₂/¹²CO₂ ratio in breath gas samples. Next to isotope ratio mass spectrometry (IRMS), which is very sensitive but also complex and expensive, alternatively isotope selective nondispersive infrared spectrometry (NDIRS) can be used to determine the ¹³CO₂/¹²CO₂ ratio in expired breath. In this study we compared NDIRS- with IRMS-results to investigate whether the less expensive and very simply to operate NDIRS works as reliable as IRMS. For this purpose we applicated 1-¹³C-Phenylalanine to patients with advanced liver cirrhosis and healthy volunteers and took duplicated breath samples for IRMS and NDIRS at selected time points. Our data show a good correlation between these two methods for a small number of samples as required for simple breath tests. Longer series, where repeated measurements are required on the NDIRS instrument lead to a decreasing correlation. This indicates the superiority of IRMS concerning ¹³CO₂-kinetics over longer time periods.     

用于ECR离子源的超导磁体——设计与制造

Superconducting magnets are widely used in ECR ion sources.The intensity and form of the magnetic field plays an important role in the way towards higher performance sources.During the development steps,the design principles and geometries had to be adapted to reach higher fields using state-of-the-art technologies and design tools.Production,assembly,and tests of these superconducting magnets are presented and a short outlook on possible future developments is given.     

Running time experiments on some algorithms for solving propositional satisfiability problems

Satisfiability problems are of importance for many practical problems. They are NP-complete problems. However, some instances of the SAT problem can be solved efficiently. This paper reports on a study concerning the behaviour of a variety of algorithmic approaches to this problem tested on a set of problems collected at FAW. The results obtained give a lot of insight into the algorithms and problems, yet also show some general technical and methodological problems associated with such comparisons.     

Further results on small-angle elastic proton-proton scattering at very high energies

This work extends our previous investigations at the CERN Intersecting Storage Rings, with improved statistics at three different energies, wider angular range and a better control over systematic errors. Values for the (diffraction) shape parameter b are given.     

Element analysis without standards in spark source mass spectrometry with low voltage vacuum arc discharge and automatic photoplate evaluation

Summary With a system for automatic evaluation of photographic plates in spark source mass spectrometry, the complete information on the photographic plate is used for the concentration procedure, i.e. all isotopes of singly and multiply charged ions contribute to the analytical results. Experiments show that the ion intensities of elements in their various ionization states lie on parabolas. The position of the parabola of impurity elements within a matrix depends mainly on that matrix and shows a characteristic relation to the analytical result.Systematic investigations lead to a significant parameter, the mean charge number Z _i , which forms a common link between the very different parabola positions of all elements within a matrix. This knowledge is the basis of a new evaluation procedure which, without using a calibration standard, leads to an essential improvement of the analytical result. Experiments in practical analysis in the analytical service of the central department demonstrate that this method, applied to many different matrices, shows a maximum deviation from the certificate value by a factor of 2 (in many cases <1.5).Determinations of the major components of alloys yield accuracies between 10 and 20% (deviations of the analytical result from the certificate value). For the relative standard deviation of the analysis results an upper limit of 15 % was reached.

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Leitprobenfreie Elementanalyse in der Funken-Massenspektrometrie mit Vakuumbogen und automatischer Photoplattenauswertung

Zusammenfassung Mit Hilfe einer automatischen Photoplattenauswertung für die Funken-Massenspektrometrie wird der gesamte Informationsgehalt der Photoplatte für die Konzentrationsbestimmung herangezogen. Experimentelle Untersuchungen zeigen, daß die-Intensitäten der Ionen eines Elements als Funktion der Ladung auf Parabeln liegen. Die Lage der Parabeln aller enthaltenen Elemente wird vom Matrixelement bestimmt und beeinflußt charakteristisch das Analysenergebnis.Systematische Untersuchungen führten zu einer neuen Kenngröße, dem gewichteten Ladungsschwerpunkt Z _i , der ein gemeinsames Bindeglied zwischen den sehr unterschiedlichen Parabellagen aller enthaltenen Elemente innerhalb einer Matrix darstellt. Diese Erkenntnis bildet die Grundlage eines Auswerteverfahrens, das ohne Verwendung von Eichstandards zu einer wesentlichen Verbesserung des Analyseergebnisses führt. Die experimentelle Überprüfung dieser Methode an sehr unterschiedlichen Matrices innerhalb des Routineeinsatzes über 4 Jahre im Analysendienst der Zentralabteilung für Chemische Analysen zeigt Abweichungen des Analysewertes vom Sollwert bis maximal zum Faktor 2. Dieses Ergebnis wurde für eine Niedervolt-Vakuumbogenentladung erzielt.Bei der Bestimmung der Hauptbestandteile von Legierungen wurden Richtigkeiten zwischen 10 und 20% erzielt (Abweichungen der Ergebnisse von den zertifizierten Werten). Die relative Standardabweichung beträgt bis zu 15%.

     

An optimal software debugging model

This paper deals with the question of optimal debugging times for large-scale computer programs, given certain assumptions concerning the distribution of error within the program, the cost that is incurred whenever a fault occurs, and the cost of debugging. Modeling takes place within the framework of independent Poisson processes describing faults caused by errors. The optimization aim is to minimize the long-run total expected discounted cost. Some general results concerning the optimal polity are presented.This research has been supported by NATO Grant No. RG.86/0024, by the Alexander von Humboldt Foundation, and by the University of Passau, Germany.     

φ production in In–In collisions at 158 A GeV

The NA60 experiment has measured muon pair production in In–In collisions at 158 AGeV at the CERN SPS. This paper presents a high statistics measurement of φ→μ μ meson production. Differential spectra, yields, mass and width are measured as a function of centrality and compared to previous measurements in other colliding systems at the same energy. The width of the rapidity distribution is found to be constant as a function of centrality, compatible with previous results. The decay muon polar angle distribution is measured in several reference frames. No evidence of polarization is found as a function of transverse momentum and centrality. The analysis of the p _T spectra shows that the φ has a small radial flow, implying a weak coupling to the medium. The T _eff parameter measured in In–In collisions suggests that the high value observed in Pb–Pb in the kaon channel is difficult to reconcile with radial flow alone. The absolute yield is compared to results in Pb–Pb collisions: though significantly smaller than measured by NA50 in the muon channel, it is found to exceed the NA49 and CERES data in the kaon channel at any centrality. The mass and width are found to be compatible with the PDG values at any centrality and at any p _T : no evidence for in-medium modifications is observed.     

First measurement of the ϱ spectral function in nuclear collisions

The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A GeV In–In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size close to 400000 events and the good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution from π⁺π^-→ϱ→μ⁺μ^- annihilation. The associated ϱ spectral function exhibits considerable broadening, but essentially no shift in mass. The p_T-differential mass spectra show the excess to be much stronger at low p_T than at high p_T. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to the chiral condensate. PACS 25.75.-q; 12.38.Mh; 13.85.Qk