A subdomain boundary element method for high‐Reynolds laminar flow using stream function‐vorticity formulation

The paper presents a new formulation of the integral boundary element method (BEM) using subdomain technique. A continuous approximation of the function and the function derivative in the direction normal to the boundary element (further ‘normal flux’) is introduced for solving the general form of a parabolic diffusion‐convective equation. Double nodes for normal flux approximation are used. The gradient continuity is required at the interior subdomain corners where compatibility and equilibrium interface conditions are prescribed. The obtained system matrix with more equations than unknowns is solved using the fast iterative linear least squares based solver. The robustness and stability of the developed formulation is shown on the cases of a backward‐facing step flow and a square‐driven cavity flow up to the Reynolds number value 50 000. Copyright © 2004 John Wiley & Sons, Ltd.     

Perturbed recurrence relations II the general case

In this paper, we give some new explicit relations between two families of polynomials defined by recurrence relations of all order. These relations allow us to analyze, even in the Sobolev case, how some properties of a family of orthogonal polynomials are affected when the coefficients of the recurrence relation and the order are perturbed. In a paper we have already given a method which allows us to study the polynomials defined by a three-term recurrence relation. Also here some generalizations are given.     

Characterisations of function spaces of generalised smoothness

We investigate function spaces of generalised smoothness of Besov and Triebel–Lizorkin type. Equivalent quasi-norms in terms of maximal functions and local means are given. An atomic decomposition theorem for this type of spaces is proved. Mathematics Subject Classification (2000) 46E35     

High-throughput purification of combinatorial libraries I: a high-throughput purification system using an accelerated retention window approach

We have developed a high-throughput purification system to purify combinatorial libraries at a 50-100-mg scale with a throughput of 250 samples/instrument/day. We applied an accelerated retention window method to shorten the purification time and targeted one fraction per injection to simplify data tracking, lower QC workload, and simplify the postpurification processing. First, we determined the accurate retention time and peak height for all compounds using an eight-channel parallel LC/UV/MS system, and calculated the specific preparative HPLC conditions for individual compounds. The preparative HPLC conditions include the compound-specific gradient segment for individual compounds with a fixed gradient slope and the compound-specific UV or ELSD threshold for triggering a fraction collection device. A unique solvent composition or solvent strength was programmed for each compound in the preparative HPLC in order to elute all compounds at the same target time. Considering the possible deviation of the predicted retention time, a 1-min window around the target time was set to collect peaks above a threshold based on UV or ELSD detection. Dual column preparative instruments were used to maximize throughput. We have purified more than 500 000 druglike compounds using this system in the past 3 years. We report various components of this high-throughput purification system and some of our purification results.     

Studium und Anwendung eines neuen Komplexes von Kupfer mit Salicylsäure

Microchimica Acta - Eine empfindliche spektrophotometrische Methode zur Bestimmung von Kupfer mit Salicyls~iure wurde beschrieben (Molarextinktion ε = 2,4 · 9 105). Die nachweisbaren...     

Monitoring degradation processes of explosives by HPLC analysis with UV- and amperometric detection

 The impact of spilled explosives, their by-products and degradation products on human beings and the environment has been recognised as a serious problem at areas of existing and former ammunition plants. In nature, aerobic and anaerobic degradation processes of explosives and their accompanying compounds yield polar contaminants with relatively high water solubilities. Most are potentially carcinogenic and mutagenic. An HPLC method applying UV-detection for nitroaromatic compounds and amperometric detection for aminoaromatic and phenolic compounds was used for monitoring the degradation of explosives in a polluted groundwater sample under natural conditions. Analysis was performed by direct injection of aliquots of the sample after exposition to daylight for different periods of time. Received: 6 January 1996/Revised: 7 March 1996/Accepted: 13 March 1996     

Bestimmung der molaren Masse und der Ladungszahl von Polymerelektrolyten mit der Ultrazentrifuge

Zusammenfassung In der vorliegenden Arbeit wird das Sedimentationsgleichgewicht der Systeme Na₆[H₂W₁₂O₄₀]—NaCI—H₂O und Na₆[H₂W₁₂O₄₀]—NaClO₄— H2O untersucht. Die scheinbare molare Masse Mapp des Natriummetawolframats wird in beiden Systemen als Funktion der Natriummetawolfrarnat-Anfangspartialdichte ₀ ^PX _z gemessen. Durch lineare Extrapolation der Funktion Mapp = Mapp (PP,, ) auf die Polymerelektrolyt-Anfangspartialdichte Null können die Grenzwerte der scheinbaren molaren Masse (Mapp)o ermittelt werden. Aus den (Mapp)o-Werten wird die Abhängigkeit der Größe (ln _PXz /m _BX ) _mPXz von der NaCI- bzw. NaClO₄-Molalität berechnet.Die Bestimmung der molaren Masse und der (stöchiometrischen) Ladungszahl eines Polymerelektrolyten aus den experimentell ermittelten (Mapp)o-Werten unter Anwendung der Lamm-Williams-Gleichung wird diskutiert. Zur Ermittlung der beiden Größen müssen mehrere Versuchsreihen mit zwei verschiedenen Fremdelektrolyten durchgeführt werden. Externe Messungen sind nicht erforderlich.Man erhält auf diese Weise verläßliche Werte so-wohl der molaren Masse als auch der (stächiometrischen) Ladungszahl.

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Summary The sedimentation equilibria of the systems sodium metatungstate-sodium chloride-water and sodium metatungstate-sodium perchlorate-water are investiated. In both systems the apparent molecular mass Mapp of sodium metatungstate (PX _z) is measured in dependence on partial density ₀ ^PX _z before centrifugation. By linear extrapolation of the function Mapp = Mapp ( ₀ ^PX _z the limiting value (Mapp)o for ₀ ^PX _z = 0 is obtained. The variation with sodium chloride and sodium perchlorate molality of the quantity (ln _{PX z} ^m _BX )mPX_z is calculated from (Mapp)o data.The determination of the molecular mass and the algebraic valency of a polymeric ion by means of the (Mapp)o values calculated by Lamm-Williams equation is discussed. In order to obtain these two quantities at least two series of experiments are required, each of which using a different supporting electrolyte. External measurements are not necessary. In this way reliable values for the molecular mass as well as for the stoichiometric valency are obtained.

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Mit 5 Abbildungen und 3 Tabellen     

Trace-Aktivitätskoeffizienten und Ionenassoziation von Natriummetawolframat im System Natriummetawolframat-Natriumperchlorat-Wasser

Zusammenfassung In der vorliegenden Arbeit wird das Sedimentations-gleichgewicht des Systems Na₆[H₂W₁₂O₄₀]-NaClO₄-H₂O bei 25 °C untersucht. Die scheinbare Ladungszahl des Natriummetawolframats wird als Funktion der NaClO₄-MolalitätmNaClO₄ ermittelt. Aus dieser Abhängigkeit kann für die summarische Dissoziation des NatriummetawolframatsNa₂[H₂W₁₂O_4o] 6Na⁺ + [H₂W₁₂O₄₀]^6– die DissoziationskonstanteK in Gegenwart von NaClO₄ als Fremdelektrolyt zuK=0,08 mol⁶·kg^–6 bestimmt werden.Der Kreuzdifferentialquotient ( _PXz , ist der Trace-Aktivitätskoeffizient des Natriummetawolframats) wird ebenfalls als Funktion der NaClO₄-Molalität ermittelt.Die Konzentrationsabhängigkeit des Trace-Aktivitätskoeffizienten zeigt einen Verlauf, wie er unseres Wissens nach noch nicht von anderen Autoren beobachtet wurde.

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Summary An ultracentrifugal study of the sedimentation equilibrium of the system Na₂[H₂W₁₂O₄₀]-NaClO₄-H₂Oat 25 °C is presented. The dependency of the apparent charge of the sodium metatungstate on NaClO₄-molality is investigated. From these data the dissociation constant for the dissociation of the sodium metatungstate in the presence of NaClO₄ according to the equationNa[H₂W₁₂O₄₀] 6Na⁺ + [H₂W₁₂O₄₀]^6– is calculated toK=0.08 mol⁶·kg^–6. The cross differential quotient ( _PXz is the trace activity coefficient of the sodium metatungstate) shows a behavior in its dependence on NaClO₄-molality which to our knowledge has not yet been reported by other authors.

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Mit 5 Abbildungen und 1 Tabelle     

Monitoring degradation processes of explosives by HPLC analysis with UV- and amperometric detection

The impact of spilled explosives, their by-products and degradation products on human beings and the environment has been recognised as a serious problem at areas of existing and former ammunition plants. In nature, aerobic and anaerobic degradation processes of explosives and their accompanying compounds yield polar contaminants with relatively high water solubilities. Most are potentially carcinogenic and mutagenic. An HPLC method applying UV-detection for nitroaromatic compounds and amperometric detection for aminoaromatic and phenolic compounds was used for monitoring the degradation of explosives in a polluted groundwater sample under natural conditions. Analysis was performed by direct injection of aliquots of the sample after exposition to daylight for different periods of time. Presented as a poster at the Anakon ’95 Conference in Schliersee, April 24–26, 1995     

A literature survey of mineral-specific sorption data on radionuclides with relevance to the disposal of radioactive waste

A comparative review of mineral-specific radionuclide sorption databases created for performance assessment and reported in both the open literature and grey literature (e.g. technical reports) has in part shown poor quality of documentation describing the database selection procedures. Inadeguate information is available on the chemical species of the radionuclide under consideration and the laboratory conditions for determining K_d-values. Sorption data derived from literature are neither comparable nor generally applicable due to the wide range in the composition of the aqueous and the solid phases applied in migration experiments. Subsequently, standardized characterization and determination procedures are needed. To improve the reliability of a mathematical model for the prediction of radionuclide sorption on cementitious and ash-type binder materials, determination of mineral-specific sorption coefficients is indispensable.