In vivo quantitation of water content in muscle tissues by NMR imaging.

The water contents of phantoms and muscle tissues were determined directly from NMR imaging experiments. The method involves the calculation of corrected proton densities using relaxation time determinations and suitable calibration phantoms. Comparison with the values obtained from the oven-dry method yields good agreement in normal rat skeletal tissue and in rats injected with red blood cells from sickle cell patients.     

A unified analysis for a class of long-step primal-dual path-following interior-point algorithms for semidefinite programming

We present a unified analysis for a class of long-step primal-dual path-following algorithms for semidefinite programming whose search directions are obtained through linearization of the symmetrized equation of the central pathH _P (XS) [PXSP ^–1 + (PXSP ^–1) ^T ]/2 = I, introduced by Zhang. At an iterate (X,S), we choose a scaling matrixP from the class of nonsingular matricesP such thatPXSP ^–1 is symmetric. This class of matrices includes the three well-known choices, namely:P = S ^1/2 andP = X ^–1/2 proposed by Monteiro, and the matrixP corresponding to the Nesterov—Todd direction. We show that within the class of algorithms studied in this paper, the one based on the Nesterov—Todd direction has the lowest possible iteration-complexity bound that can provably be derived from our analysis. More specifically, its iteration-complexity bound is of the same order as that of the corresponding long-step primal-dual path-following algorithm for linear programming introduced by Kojima, Mizuno and Yoshise. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.Corresponding author.This author's research is supported in part by the National Science Foundation under grants INT-9600343 and CCR-9700448 and the Office of Naval Research under grant N00014-94-1-0340.This author's research was supported in part by DOE DE-FG02-93ER25171-A001.     

Modification and validation of the pyromellitic acid electrolyte for the capillary electrophoretic determination of anions

For the determination of inorganic and organic anions, the pyromellitic acid (PMA) electrolyte is widely used. The pH adjustment of the self-prepared electrolyte was very challenging to satisfy the pH of specification of pH 7.8 +/- 0.1. A modification was proposed to provide a more simple electrolyte by buffering the PMA electrolyte with triethanolamine (TEA) only instead of adjusting the pH by NaOH and TEA. Thus, the proposed electrolyte consisted of 2.25 mmol l(-1) PMA, 0.75 mmol 1(-1) hexamethonium hydroxide and 12 mmol 1(-1) TEA. The performance of the PMA electrolyte buffered by TEA only was compared to a commercial available PMA and statistically validated in accordance with the methodology of Taguchi. No statistically significant difference could be found for both electrolytes assessing the performance and detection limits of hydrodynamic, stacking and electrokinetic injection with transient isotachophoretic preconcentration as well as repeatability of migration times, peak resolutions and peak symmetries.     

NASICON type ionic conductors for alkali ion sensing

NASICON type ionic conductors can be used as the sensitive membrane of alkali ion sensors. The main advantages compared to the classical glass electrodes are the better selectivity and lower impedance. The mechanism of response of this type of ionic sensors is presented. The sensitivity results from a direct ionic exchange between the ceramic electrolyte and the solution which has been characterized by impedance spectroscopy. The origin of the selectivity in the NASICON framework is discussed in terms of structural and ionic exchange properties. The performance characteristics of sodium and lithium ion sensing devices are presented. Examples of biomedical applications such as the measurement of sodium concentration in the crevicular fluid and the determination of lithium in artificial serum are described. Paper presented at the 6th Euroconference on Solid State Ionics, Cetraro, Calabria, Italy, Sept. 12–19, 1999.     

Temperaturabhängigkeit der Gleichgewichtsspreitungsdrucke homologer Lezithine an der Grenzfläche n-Heptan/0,1 M NaCl

Ohne ZusammenfassungMit 1 Abbildung und 1 Tabelle     

Novel methods of TXRF analysis for silicon wafer surface inspection

TXRF became a standard, on-line inspection tool for controlling the cleanliness of polished Si wafers for semiconductor use. Wafer makers strive for an all-over metallic cleanliness of < 10¹⁰ atoms · cm^–2. The all-over cleanliness can be analyzed using VPD/TXRF. For VPD preparation and scanning we have developed an automatic system coupled with TXRF. With synchrotron radiation TXRF we were able to detect 13 fg of Ni in a residual microdroplet, i.e.10⁵ atoms · cm^–2. Received: 8 January 1998 / Revised: 13 July 1998 / Accepted: 30 July 1998     

Das Atomgewicht des Nebuliums

Ohne Zusammenfassung     

Light-mediated heterogeneous cross dehydrogenative coupling reactions: metal oxides as efficient, recyclable, photoredox catalysts in C-C bond-forming reactions

Let there be light: A heterogeneous photocatalytic system based on easily recyclable TiO(2) or ZnO allows cross dehydrogenative coupling reactions of tertiary amines. The newly developed protocols have successfully been applied to various C-C and C-P bond-forming reactions to provide nitro amines as well as amino ketones, nitriles and phosphonates.