Eine colorimetrische Methode zur Bestimmung der Phosphors?ure in Gras und ?hnlichem Material nach dem Verfahren von Fiske und Subbarow

Ohne Zusammenfassung     

Investigation of the flow physics in the human pharynx/larynx region

This experimental study was carried out to investigate the flow field in the human extra-thoracic airway using the particle image velocimetry technique. The purpose of this study is to understand the physics of the turbulent flow in the pharynx/larynx region. The flow rate was 9?l/min, and the corresponding Reynolds number, based on the inlet condition, was 670. Two thousand images were acquired at each location at a framing rate of 2?Hz. The mean turbulence intensity, turbulent kinetic energy and Reynolds stress fields were calculated. Moreover, the proper orthogonal decomposition method and quadrant analysis were also used for investigating the flow in the pharynx/larynx region. The results showed that the flow is strongly three dimensional and is characterised by re-circulation, jet-like and sink-like mean flows. The pharynx/larynx region is characterised by bursting events (e.g. ejection, sweep and interaction events) particularly in the epiglottal region. These events appear to be responsible for deforming and/or tearing apart the vortical structures. In addition, the major contribution to the Reynolds shear stress comes from the events that mainly burst with or against the flow direction which, in some cases, exceeded 100?% of the inlet velocity.     

NEAR ULTRAVIOLET INACTIVATION STUDIES ONESCHERICHIA COLI TRYPTOPHANASE AND TRYPTOPHAN SYNTHETASE

Abstract— –The response of two pyridoxal-phosphate-requiring enzymes of E. coli, tryptophanase and tryptophan synthetase, to near UV light (320–400 nm) has been studied. Tryptophanase is inactivated both in vivo and in vitro, but tryptophan synthetase is resistant to near UV under both conditions. This shows that near UV inactivation is not general for pyridoxal-phosphate-requiring enzymes. Substrate protection against light inactivation is demonstrated for tryptophanase. It is furthermore shown that pyridoxal phosphate is required for inactivation of this enzyme. However, the action spectrum for this inactivation does not coincide with the absorption spectrum of tryptophanase or of pyridoxal phosphate.     

Spectroscopic evidence for bonding coordination defects in amorphous as

Spectroscopic evidence for four-fold and possibly, two-fold coordinated defects in amorphous As is presented. Structure in Raman scattering and infrared absorption measurements is interpreted using force-constant models and the cluster-Bethe-lattice method. The positions and intensities of certain peaks suggest that these defects may be the analogues of valence alternation pairs in amorphous chalcogenide glasses.     

A review and tutorial discussion of noise and signal-to-noise ratios in analytical spectrometry—I. Fundamental principles of signal-to-noise ratios

This review consists of two parts which discuss signal-to-noise in a tutorial manner. The sources of noise, the mathematical representation of noise, and the major types of noises in emission and luminescence spectrometry are discussed. An extensive treatment of noise and signal-to-noise ratios of paired readings is given using the relation between the auto-correlation function and the spectral noise power. These signal-to-noise expressions under optimized measurement conditions are given in terms of currents and count rates as well as in terms of charge and counts for the cases of d.c. and a.c. measurements; the present treatment is limited to the cases when the background shows only either shot noise or flicker noise. Finally, the consequences of the combination of these noise sources is considered. Signal expressions for optical spectrometry are also given. Tables give the expressions for signal-to-noise ratios in the various cases.     

Turbulent pipe flow manipulation: some experimental and computational results for single manipulator rings

The effect on developing turbulent pipe flow of blade manipulator devices has been investigated both experimentally and computationally with a view towards reducing pipeline transmission losses. Wall pressure and mean axial velocity profiles have been obtained for nine manipulator configurations. Numerical calculations have been performed for two of these manipulator configurations using a finite volume method that incorporates a low Reynolds number model of turbulence. The results suggest that nett drag reduction may be possible in this flow although at present this seems unlikely. It remains to be answered whether any benefit can be achieved in fully developed flow for which both experimental and computational studies are now underway.