The use of proton transfer reaction mass spectrometry for high throughput screening of terpene synthases

In this work, we introduce the application of proton transfer reaction mass spectrometry (PTR-MS) for the selection of improved terpene synthase mutants. In comparison with gas chromatography mass spectrometry (GC-MS)-based methods, PTR-MS could offer advantages by reduction of sample preparation steps and analysis time. The method we propose here allows for minimal sample preparation and analysis time and provides a promising platform for the high throughput screening (HTS) of large enzyme mutant libraries. To investigate the feasibility of a PTR-MS-based screening method, we employed a small library of Callitropsis nootkatensis valencene synthase (CnVS) mutants. Bacterial cultures expressing enzyme mutants were subjected to different growth formats, and headspace terpenes concentrations measured by PTR-Qi-ToF-MS were compared with GC-MS, to rank the activity of the enzyme mutants. For all cultivation formats, including 96 deep well plates, PTR-Qi-ToF-MS resulted in the same ranking of the enzyme variants, compared with the canonical format using 100 mL flasks and GC-MS analysis. This study provides a first basis for the application of rapid PTR-Qi-ToF-MS detection, in combination with multi-well formats, in HTS screening methods for the selection of highly productive terpene synthases.     

Strong Universal Pointwise Consistency of Recursive Regression Estimates

For semi-recursive and recursive kernel estimates of a regression of Y on X (d-dimensional random vector X, integrable real random variable Y), introduced by Devroye and Wagner and by Révész, respectively, strong universal pointwise consistency is shown, i.e. strong consistency P _X -almost everywhere for general distribution of (X, Y). Similar results are shown for the corresponding partitioning estimates.     

Methane activation on a La0.6Sr0.4Co0.8Fe0.2O3 perovsksite; catalytic and electrocatalytic results

The catalytic and electrocatalytic behaviour of the La_0.6Sr_0.4Co_0.8Fe_0.2O₃ (LSCF) perovskite deposited on yttria stabilized zirconia (YSZ), was studied during the reaction of methane oxidation. Experiments were carried out at atmospheric pressure, and at temperatures between 600 and 900 °C. When, instead of cofeeding with methane in the gas phase, oxygen was electrochemically supplied as O²⁻, considerable changes in the methane conversion and product selectivity were observed. The non-faradaic effects (NEMCA) were also studied and compared to those observed with metal catalysts. Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland, Sept. 13–19, 1997     

Comprehensive inter‐laboratory calibration of reference materials for δ18O versus VSMOW using various on‐line high‐temperature conversion techniques

Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high‐temperature conversion techniques (HTC) a in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference materials, which span more than 125‰, an artificially enriched reference water (δ¹⁸O of +78.91‰) and two barium sulfates (one depleted and one enriched in ¹⁸O) were prepared and calibrated relative to VSMOW2 b and SLAP reference waters. These materials were used to calibrate the other isotopic reference materials in this study, which yielded:

Pulsed laser deposition of PZT/Pt composite thin films with high dielectric constants

PbZr_0.53Ti_0.47O₃ (PZT) thin films containing nanoparticles of Pt (3–10 nm) were produced using pulsed laser deposition (PLD). The Pt content can be tuned by varying the energy density of the laser beam. Phase and microstructure analysis of the thin films was performed using XRD, SEM, TEM and AFM. The electrical properties were investigated by C–V and I–V measurements. The effective dielectric constant of the composite films increased substantially through the Pt dispersion. These films are promising candidates, for instance, for high-density dynamic random access memory (DRAM) devices. PACS 77.22.Ch; 77.84.Lf; 81.15.Fg     

Eine Mandelbrojtsche Formel zur Bestimmung von Punkten aus dem Spektrum eines beschränkten Operators

Ohne ZusammenfassungHerrnGottfried Köthe zum 60. Geburtstag am 25. 12. 1965 gewidmet     

Randeigenschaften zufälliger Potenzreihen und eine damit zusammenhängende Verallgemeinerung des Satzes von Fatou und Nevanlinna

Ohne Zusammenfassung     

Über Eigenwerte und Eigenlösungen symmetrisierbarer finiter Operatoren

Ohne Zusammenfassung