A Dual-Engine for Early Analysis of Critical Systems

This paper presents a framework for modeling, simulating, and checking properties of critical systems based on the Alloy language -- a declarative, first-order, relational logic with a built-in transitive closure operator. The paper introduces a new dual-analysis engine that is capable of providing both counterexamples and proofs. Counterexamples are found fully automatically using an SMT solver, which provides a better support for numerical expressions than the existing Alloy Analyzer. Proofs, however, cannot always be found automatically since the Alloy language is undecidable. Our engine offers an economical approach by first trying to prove properties using a fully-automatic, SMT-based analysis, and switches to an interactive theorem prover only if the first attempt fails. This paper also reports on applying our framework to Microsoft's COM standard and the mark-and-sweep garbage collection algorithm.Comment: Workshop on Dependable Software for Critical Infrastructures (DSCI), Berlin 201

Chemische Untersuchung von Glasrohstoffen und Gläsern. Sammelreferat über die einschlägigen Beiträge zum 2. Internationalen Glas-Kongreß (London und Sheffield 1936)

[no abstract available

Beiträge zur mikrochemischen Analyse der Gläser.

[no abstract available

Beiträge zur mikrochemischen Analyse der Gläser. IV.

4. Der Nachweis des Fluors im Glase. Nachweis kleiner FIuormengen durch mikrochemische Kristallreaktionen (Barium- bzw. Natriumfluorsilikat) und durch einige Farbreaktionen (Molybdänblau-Probe und Alizarin-Zirkon-Probe). - Vergleichende Prüfung der einzelnen Reaktionen. - Ihre Anwendbarkeit und Leistungsfähigkeit für die praktische Glasanalyse. - Empfindliche und schnelle Vorprüfung auf FIuor durch Borsäureschmelze und Nachweis des aus dem Silikat verflüchtigten Borfluorides mit Alizarin-Zirkon-Papier

Organic Reference Materials for Hydrogen, Carbon, and Nitrogen Stable Isotope-Ratio Measurements: Caffeines, n-Alkanes, Fatty Acid Methyl Esters, Glycines, L-Valines, Polyethylenes, and Oils

An international project developed, quality-tested, and determined isotope−δ values of 19 new organic reference materials (RMs) for hydrogen, carbon, and nitrogen stable isotope-ratio measurements, in addition to analyzing pre-existing RMs NBS 22 (oil), IAEA-CH-7 (polyethylene foil), and IAEA-600 (caffeine). These new RMs enable users to normalize measurements of samples to isotope−δ scales. The RMs span a range of δ^2H_(VSMOW-SLAP) values from −210.8 to +397.0 mUr or ‰, for δ^(13)C_(VPDB-LSVEC) from −40.81 to +0.49 mUr and for δ^(15)N_(Air) from −5.21 to +61.53 mUr. Many of the new RMs are amenable to gas and liquid chromatography. The RMs include triads of isotopically contrasting caffeines, C_(16) n-alkanes, n-C_(20)-fatty acid methyl esters (FAMEs), glycines, and L-valines, together with polyethylene powder and string, one n-C_(17)-FAME, a vacuum oil (NBS 22a) to replace NBS 22 oil, and a ^2H-enriched vacuum oil. A total of 11 laboratories from 7 countries used multiple analytical approaches and instrumentation for 2-point isotopic normalization against international primary measurement standards. The use of reference waters in silver tubes allowed direct normalization of δ2H values of organic materials against isotopic reference waters following the principle of identical treatment. Bayesian statistical analysis yielded the mean values reported here. New RMs are numbered from USGS61 through USGS78, in addition to NBS 22a. Because of exchangeable hydrogen, amino acid RMs currently are recommended only for carbon- and nitrogen-isotope measurements. Some amino acids contain ^(13)C and carbon-bound organic ^2H-enrichments at different molecular sites to provide RMs for potential site-specific isotopic analysis in future studies

Beiträge zur mikrochemischen Analyse der Gläser. VII. Der Nachweis und die Bestimmung des Goldes.

Aufschluß des Glases. - Abtreiben des Bleis. - Bestimmung des Goldes durch Ausmessen des feingetriebenen Goldkornes oder durch kolorimetrische Bestimmung mit o-Tolidin. - Leistungsfähigkeit des Verfahrens zur quantitativen Bestimmung und zum qualitativen Nachweis

Beiträge zur mikrochemischen Analyse der Gläser. V und VI. Der Nachweis kleinster Kobalt- und Nickelmengen im Glase.

a) Der Nachweis des Kobalts: 1. Der Nachweis als Kobalt-Quecksilberrhodanid Co[Hg(CNS)4]. 2. Der Nachweis in der Borax- bzw. Phosphorsalzperle. - Die Anreicherung durch Elektrolyse. - Arbeitsvorschrift für den Nachweis kleinster Kobaltmengen in einfachen Alkali-Kalk-Gläsern. - Empfindlichkeit des beschriebenen Kobalt-Nachweises. - Nachweis größerer Kobaltmengen. - Nachweis ohne Verletzung der Gläser. - Störende Elemente und deren Unschädlichmachung. b) Der Nachweis des Nickels. - Störungen des Nickelnachweises. - Kolorimetrische Nickelbestimmung. - Anwendung zur Ni-Bestimmung in Gläsern. - Zusammenfassung

Optimization of on-line hydrogen stable isotope ratio measurements of halogen- and sulfur-bearing organic compounds using elemental analyzer–chromium/high-temperature conversion isotope ratio mass spectrometry (EA-Cr/HTC-IRMS)

RATIONALE: Accurate hydrogen isotopic analysis of halogen- and sulfur-bearing organics has not been possible with traditional high-temperature conversion (HTC) because the formation of hydrogen-bearing reaction products other than molecular hydrogen (H 2 ) is responsible for non-quantitative H 2 -yields and possible hydrogen isotopic fractionation. Our previously introduced, new chromium-based EA-Cr/HTC-IRMS (Elemental Analyzer – Chromium/High Temperature Conversion – Isotope-Ratio Mass Spectrometry) technique focused primarily on nitrogen-bearing compounds. Several technical and analytical issues concerning halogen- and sulfur-bearing samples, however, remained unresolved and required further refinement of the reactor systems. METHODS: The EA-Cr/HTC reactor was substantially modified for the conversion of halogen- and sulfur-bearing samples. The performance of the novel conversion setup for solid and liquid samples was monitored and optimized using a simultaneously operating dual- detection system of IRMS and ion trap MS. The method with several variants in the reactor, including the addition of manganese metal chips, was evaluated in three laboratories using EA-Cr/HTC-IRMS (on-line method) and compared with traditional uranium-reduction-based conversion combined with manual dual-inlet IRMS analysis (off-line method) in one laboratory. RESULTS: The modified EA-Cr/HTC reactor setup showed an overall H 2 -recovery of more than 96 % for all halogen- and sulfur-bearing organic compounds. All results were successfully normalized via 2-point calibration with VSMOW-SLAP reference waters. Precise and accurate hydrogen isotopic analysis was achieved for a variety of organics containing F-, Cl-, Br-, I-, and S-bearing heteroelements. The robust nature of the on-line EA-Cr/HTC technique was demonstrated by a series of 196 consecutive measurements with a single reactor filling. CONCLUSIONS: The optimized EA-Cr/HTC reactor design can be implemented in existing analytical equipment using commercially available material and is universally applicable for both heteroelement-bearing and heteroelement-free organic-compound classes. The sensitivity and simplicity of the on-line EA-Cr/HTC-IRMS technique provide a much needed tool for routine hydrogen-isotope source tracing of organic contaminants in the environment