Stable isotope quality assurance using the ‘Calibrated IRMS’ strategy†

Procedures in our laboratory have always been directed towards complete understanding of all processes involved and corrections needed etc., instead of relying fully on laboratory reference materials. This rather principal strategy (or attitude) is probably not optimal in the economic sense, and is not necessarily more accurate either. Still, it has proven to be very rewarding in its capability to detect caveats that go undiscovered in the standard way of measurement, but that do influence the accuracy or reliability of the measurement procedure. An additional benefit of our laboratory procedures is that it makes us capable of assisting the International Atomic Energy Agency (IAEA) with primary questions like mutual scale assignments and comparison of isotope ratios of the same isotope in different matrices (like δ¹⁸O in water, carbonates and atmospheric CO₂), establishment of the ¹⁷O–¹⁸O relation, and the replenishment of the calibration standards. Finally, for manual preparation systems with a low sample throughput (and thus only few reference materials analysed) it may well be the only way to produce reliable results.     

Oxygen surface exchange kinetics of erbia-stabilized bismuth oxide

The surface oxygen exchange kinetics of bismuth oxide stabilized with 25 mol% erbia (BE25) has been studied in the temperature and pO₂ ranges 773–1,023 K and 0.1–0.95 atm, respectively, using pulse-response ¹⁸O–¹⁶O isotope exchange measurements. The results indicate that BE25 exhibits a comparatively high exchange rate, which is rate determined by the dissociative adsorption of oxygen. Defect chemical considerations and the observed pO₂^1/2 p{{\hbox{O}}_2}^{1/2} dependence of the rate of dissociative oxygen adsorption suggest electron transfer to intermediate superoxide ions as the rate determining step in surface oxygen exchange on BE25.     

PIKfyve,a Class III PI Kinase,Is the Target of the Small Molecular IL-12/IL-23 Inhibitor Apilimod and a Player in Toll-like Receptor Signaling

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Experimental quantum teleportation of arbitrary quantum states

Received: 1 July 1998/Revised version: 2 October 1998     

Development and validation of single particle ICP-MS for sizing and quantitative determination of nano-silver in chicken meat

The application of nanomaterials is leading to innovative developments in industry, agriculture, consumer products, and food and related sectors. However, due to the special properties of these materials there are concerns about their safety, especially because of our limited knowledge of human health effects and the fact that constantly new nanomaterials and applications thereof are being produced. The development of analytical techniques is a key element to understand the benefits as well as the risks of the application of such materials. In this study, a method is developed and validated for sizing and quantifying nano-silver in chicken meat using single particle inductive coupled plasma mass spectrometry (ICP-MS). Samples are processed using an enzymatic digestion followed by dilution of the digest and instrumental analysis of the diluted digest using single particle ICP-MS. Validation of the method in the concentration of 5–25 mg/kg 60-nm silver nanoparticles showed good performance with respect to trueness (98–99 % for size, 91–101 % for concentration), repeatability (<2 % for size, <11 % for concentration), and reproducibility (<6 % for size, <16 % for concentration). The response of the method is linear, and a detection limit as low as 0.1 mg/kg can be obtained. Additional experiments showed that the method is robust and that digests are stable for 3 weeks at 4 °C. Once diluted for single particle ICP-MS analysis, the stability is limited. Finally, it was shown that nano-silver in chicken meat is not stable. Silver nanoparticles dissolved and were transformed into silver sulfide. While this has implications for the form in which nano-silver will be present in real-life meat samples, the developed method will be able to determine the presence and quantity of nanoparticle silver in such samples.     

Wachstumsverhalten zufÄlliger Potenzreihen

Summary Using the theorems collected in Chapter 2 the paper discusses growth and divergence properties of random power series (rps's) with — generally — independent coefficients a _n. In Chapter 3 assertions about rps's with a _n symmetric relative to 0 are transferred to rps's for which the medians a _n of a _n are 0. Chapter 4 treats analogies between rps's with symmetrized coefficients a _s ⁿ and rps's with centered coefficients a _n -a _n ; they concern growth of random entire functions defined by rps's with arbitrarily dependent coefficients, and local behaviour near the circle of convergence. For some kinds of singular behaviour, e.g. unboundedness of characteristic in every sector of the circle of convergence, Chapter 5 gives necessary and sufficient conditions in connection with the notion of essential divergence. The theorems hold also for -quantiles a _n ( fixed, 0<<1) instead of medians a _n .Herrn Professor Dr. F. Lösch zum 65. Geburtstag gewidmet.     

Über den Einfluß der Anharmonizität auf die thermische Röntgenstreuung an Kristallen

Work already published under the above topic by W.Ludwig and the author was limited to crystal temperatures above the Debye temperature, as it treated the lattice vibrations by classical statistics. In this paper, a complete quantum-statistical treatment is presented. The essential features of the high temperature results remain unchanged: New, temperature dependent dispersion curves may be introduced which, for long waves, are determined by theisothermal elastic constants.     

Nonlinear interferometry via Fock-state projection

We use a photon-number-resolving detector to monitor the photon-number distribution of the output of an interferometer, as a function of phase delay. As inputs we use coherent states with mean photon number up to seven. The postselection of a specific Fock (photon-number) state effectively induces high-order optical nonlinearities. Following a scheme by Bentley and Boyd [Opt. Express 12, 5735 (2004).10.1364/OPEX.12.005735], we explore this effect to demonstrate interference patterns a factor of 5 smaller than the Rayleigh limit.     

Observation of bunching of two bell states

The bunching of two single photons on a beam splitter is a fundamental quantum effect, first observed by Hong, Ou, and Mandel. It is a unique interference effect that relies only on the photons' indistinguishability and not on their relative phase. We generalize this effect by demonstrating the bunching of two Bell states, created in two passes of a nonlinear crystal, each composed of two photons. When the two Bell states are indistinguishable, phase-insensitive destructive interference prevents the outcome of fourfold coincidence between the four spatial-polarization modes. For certain combinations of the two Bell states, we demonstrate the opposite effect of antibunching. We relate this result to the number of distinguishable modes in parametric down-conversion.