Frequency chirp in W-band pulsed IMPATT oscillators

An analytical device-circuit interaction model to compute the frequency chirp bandwidth in W-band pulsed DDR IMPATT diodes is presented. The measured chirp agrees reasonably well with the calculated values.     

Beiträge zur Chemie der Silicium-Stickstoff-Verbindungen. 163. Untersuchungen über einige Verbindungen mit BNSi-Struktureinheiten

Chemistry of Silicon-Nitrogen Compounds. 163. Investigation of Some Compounds with BNSi Structure Fragments Some formerly unknown compounds with BNSi structure fragments were prepared (or obtained on a not expected way), confirmed in their structure and described in their properties: (EtO)₂BN(SiMe₃)₂ ( V ), FB[N(SiCl₃)₂]₂ ( XIII ), the derivatives IV, XVI – XIX of the six-, five- and four-membered ring systems cyclotriazatriborane, cyclodisilaboradiazane, and cyclosilaboradiazane and XXIII of a [3, 4]-spiro system. Br₂BN(SiMe₃)₂ ( III ), already known, was prepared by a different method.     

Routinem?\ige Fluorbestimmung mit Hilfe der R?ntgenfluorescenzanalyse

Ohne Zusammenfassung

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Routine determination of fluorine by XRF-analysis

     

Negative-ion mass spectrometry of substituted adenine bases and adenosine nucleosides

The negative-ion chemical ionization (ammonia, 5 Pa source pressure) mass spectra of a series of substituted adenine bases, adenosine nucleosides, and the trimethylsilyl derivatives of the nucleosides are described. Selected ions from these spectra were subject to collisionally activated dissociation with mass-analysed ion kinetic energy (CAD/MIKE) analysis of the products and the spectra assessed for information content. In addition to observing strong peaks due to quasimolecular ions and heterocyclic-base ions, it proved possible to differentiate between 2'-, 3'- and 5'-deoxy and between 2'- and 3'-O-methyl isomers. The negative-ion chemical ionization spectra of four methyladenines are essentially identical, but could be clearly distinguished from each other by CAD/MIKE analysis.     

A sequential technique for the control of traffic intensity in Markovian queues

A sequential parameter control technique previously introduced by the author is modified in this paper so as to make it simple in practice. The detailed procedure involving two phases, a warning phase with control limits and a testing phase using an appropriate test is illustrated for a queueing system with an embedded Markov chain. Operating characteristics of the procedure are also examined.     

Compounds of arsenic,antimony, and tin in mollusc shells

Inorganic arsenic(III) and arsenic(V), methyl-arsenicals, antimony(III), and antimony(V), and butyltin derivatives are present in the shells of molluscs found in the coastal waters of British Columbia.     

Combined supercritical-fluid chromatography/mass spectrometry in the analysis of diuron in plasma using on-line phase-system switching

On-line sample pretreatment by means of the phase-system switching approach is an interesting technique for the analysis of aqueous samples, e.g., plasma, by means of supercritical-fluid chromatography. In order to analyse plasma samples the following analytical procedure is used. The plasma sample is injected on to a short precolumn, which is washed with water and subsequently dried with nitrogen. Next, the solutes are desorbed with the supercritical mobile phase, analysed with packed-column supercritical-fluid chromatography and detected with either a UV detector or a mass spectrometer, equipped with a moving-belt interface. The herbicide diuron is selected as a test compound to study the feasibility of this approach. Using a selective detector the procedure is sufficiently sensitive to detect diuron in plasma, but not appropriate to detect the diuron metabolites in a post-mortem plasma sample. These have been identified with liquid chromatography/mass spectrometry. The detection limit of diuron in plasma using the procedure described is about 30 ng/mL.     

Exact and approximate results for the Anderson impurity model

This paper provides exact and rigorous upper and lower bounds to the ground state energy of the Single Impurity Anderson Model in the limit of infiniteU. The upper bound approximates the ground state energy very well and the corresponding state may be used as a starting point for further investigations. The energy spectrum of the Single Impurity Anderson Model is calculated exactly for a special non-trivial model density of states describing the bare band electrons. All approaches introduced here are compared to this exact result and to other ground state energy calculations.