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).     

Biotransformation of butyltin compounds using pure strains of microorganisms

The debutylation of tributyltin chloride by several strains of fungi, yeasts and bacteria is described. Under standard conditions and with low initial concentration of substrate, significant biotic degradation of tributyltin (6–32%) was detected after five days at 28°C. Dibutyltin and monobutyltin were formed in all cases, with higher yields of the latter. Two microorganisms catalysed the transformation of monobutyltin to dimethyltin and trimethytin whereas all microorganisms were able to methylate inorganic tin(IV) to trimethyltin. Our results suggest that tributyltin biodegradation by microorganisms is generally possible, provided sufficiently low concentrations of substrate are used.     

Resolving differences of parameter extraction methods for integrated inductor design and model validation

This work analyses different parameter extraction methods for on-chip integrated inductors and their impact on inductor design. The relationship between extracted single-ended and differential parameters is investigated through the use of theoretical network models that support the calculation equations. Experimental results from a test chip are presented and a lumped model, which adequately simulates the inductor performance with and without ground shield, is validated.     

Periodic unfolding and homogenizationÉclatement périodique et homogénéisation

A novel approach to periodic homogenization is proposed, based on an unfolding method, which leads to a fixed domain problem (without singularly oscillating coefficients). This method is elementary in nature and applies to cases of periodic multi-scale problems in domains with or without holes (including truss-like structures). To cite this article: D. Cioranescu et al., C. R. Acad. Sci. Paris, Ser. I 335 (2002) 99–104.     

Comparative evaluation of adsorption energy distribution functions obtained by analytical and numerical methods

The adsorption energy distributions derived from the Adamson and Ling (AL), and the House and Jaycock HILDA numerical methods are compared with the Sips analytical solution, which is used as a benchmark for these numerical methods. Excellent agreement between the analytical and numerical methods is achieved provided that the isotherm data are measured over a wide range of adsorbate partial pressures, extending to near the saturation capacity. While a lack of accurate low-pressure data will merely result in an inaccurate energy distribution in the high-energy range, a lack of these high-pressure data may result in an entirely wrong energy distribution.     

Optical anisotropy of polymer chains and Markov processes. II. Polyoxyethylene

A comparative study of the average molecular optical anisotropy 〈γ²〉 of the polyoxyethylene chain, \documentclass{article}\pagestyle{empty}\begin{document}${\rm R} \hbox{---} {\rm O}\rlap{--} ({\rm CH}_2 {\rm CH}_2 {\rm O}\rlap{--} )_n {\rm R}$\end{document} where R = CH₃, H and n is the degree of polymerization of the molecule, was carried out for the different internal rotational models considered in Part I of this series. In particular, the results obtained show that the condition of interdependence between internal rotational angles of nearest-neighboring bonds increases the average molecular optical anisotropy by about 4% (n ? 1), compared with the case of independent rotations. This increase is much weaker than in polyethylene chains, for which it is about 20% under analogous conditions.     

Progress toward a practical skywave sea-state radar

Recent advances in propagation modeling, ionospheric diagnostics, and signal processing have helped overcome the limitations the ionosphere imposes on sea-state measurements with HF skywave radar. Wind-direction fields in tropical storms can be routinely mapped under most ionospheric conditions, but waveheight and wave-spectrum extraction is more sensitive to ionospheric distortions and requires care in signal processing and in selecting an ionospheric path. Spot measurements with a high-resolution radar have verified its ability to measure (in order of increasing difficulty) wind-direction fields, rms waveheight, and the scalar ocean-wave spectrum at ranges up to 3000 km using one ionospheric hop. Although such a radar can in principle map these quantities over millions of square kilometers of an ocean area, the time required to do so under various ionospheric conditions remains to be determined. A minimum objective of one map of rms waveheight per day seems attainable.