The general packed column: an analytical solution

The transient behaviour of a packed column is considered. The column, uniformly packed on a macroscopic scale, is multi-structured on the microscopic level: the solid phase consists of particles, which may differ in incidence, shape or size, and other relevant physical properties. Transport in the fluid phase happens by convective flow and longitudinal diffusion. The adsorptionrate in the column is determined by the combined effects ofmass transfer through a thin liquid film around the particles,diffusion into the particles and first-order loss in the particles.An analytical solution to the problem is given in the formof an infinite integral. The solution method is worked outin detail for three special cases, each with only one typeof particle in the solid phase, in the shape of a sphere, ora finite cylinder, or a rectangular parallelepiped. Received 7 September, 1998. Revised 4 March, 2000. ⁺ E-mail: jo.gielen@ztw.wk.wau.nl     

New mass spectrometric approaches to structural analysis in mixtures

Structural analysis of minor components in mixtures is a vital requirement in the development of any pharmaceutical compound. Mass spectrometry is uniquely able to give this kind of information on the trace amounts of material present as minor impurities in a drug substance. In this study we show that a combination of mass spectrometric analysers with different characteristics is an even more powerful approach with a higher chance of establishing a potential structure. In particular the advent of analysers capable of accurate mass measurement on small amounts of material has enabled structures to be proposed in situations where previously no real conclusions could be made. Copyright 1999 John Wiley & Sons, Ltd.     

Rational matrix approximation with a priori error bounds for non-symmetric matrix Riccati equations with analytic coefficients

In this paper the exact solution of the non-symmetric matrixRiccati equation with analytic coefficients is approximatedby a rational matrix function with a prefixed accuracy. Thisrational matrix function is locally defined as the exact solutionof a Riccati problem with matrix polynomial coefficients obtainedby truncation of the Taylor expansions of the matrix coefficientsof the original problem.     

In vitro antitumour activity of some organogermanium radioprotectors

Four germanium derivatives of 2,2′‐oxydiethanethiol and 2,2′‐thiodiethanethiol have been synthesized and characterized by ¹H and ¹³C NMR, mass spectroscopy and elemental analysis. The antitumour activity of one of them is comparable to those of cis‐platin and etoposide. Copyright © 2003 John Wiley & Sons, Ltd.     

Combined compact difference method for solving the incompressible Navier–Stokes equations

This paper presents a numerical method for solving the two‐dimensional unsteady incompressible Navier–Stokes equations in a vorticity–velocity formulation. The method is applicable for simulating the nonlinear wave interaction in a two‐dimensional boundary layer flow. It is based on combined compact difference schemes of up to 12th order for discretization of the spatial derivatives on equidistant grids and a fourth‐order five‐ to six‐alternating‐stage Runge–Kutta method for temporal integration. The spatial and temporal schemes are optimized together for the first derivative in a downstream direction to achieve a better spectral resolution. In this method, the dispersion and dissipation errors have been minimized to simulate physical waves accurately. At the same time, the schemes can efficiently suppress numerical grid‐mesh oscillations. The results of test calculations on coarse grids are in good agreement with the linear stability theory and comparable with other works. The accuracy and the efficiency of the current code indicate its potential to be extended to three‐dimensional cases in which full boundary layer transition happens. Copyright © 2011 John Wiley & Sons, Ltd.     

In vitro antitumour activities of a novel 2:3 condensation product of salicylaldoxime with di-n-butyltin(IV) oxide

The antitumor activities of three novel condensation products of salicylaldoxime with di-n-butyltin(IV) oxide (compound 1), di-t-butyltin oxide (compound 2) and diphenyltin oxide (compound 3) are presented. Against MCF-7, a human mammary tumor cell line, compounds 1 and 2 are characterized by inhibition doses ID₅₀ in vitro of 67 and 49 ng cm^?3 respectively, whereas cis-platin, an antitumor drug used clinically, has an ID₅₀ of 850 ng cm^?3. Against WiDr, a colon carcinoma, they also score better than cis-platin: 215 and 121 ng cm^?3 versus 624 ng cm^?3. In contrast, the diphenyltin compound, 3, is inactive against both tumor cell lines. The results of a pre-screening performed on compound 1 by the National Cancer Institute (NCI) on a panel of 60 human tumor cell lines show that two of the selectivity parameters calculated by the NCI for that compound are statistically significant, namely D_G150 (51.9>50) and MGD_H (80.1>75). One is almost satisfactory (D_H = 72.4 = ca75). The other two, D_TGI (40.0<50) and D_LC50 (16.7<50) are not. (Abbreviations are explained in the text and in Gielen, M. and Willem, R. Anticancer Res., 1992, in press).