Jacques Reisse

Is it Useful to Have a Clear-cut Definition of Life? On the Use of Fuzzy Logic in Prebiotic Chemistry

Many scientists, including one of the authors of the present paper, have devoted time to try to find a definition for life (Bersini and Reisse 2007). It is clear that a consensus will never be reached but, more importantly, it seems that the issue itself could be without major interest. It is indeed impossible to define a “natural” frontier between non-living and living systems and therefore also impossible to define dichotomic criteria which could be used in order to classify systems in one of these two classes (living or non-living). Fuzzy logic provides a natural way to deal with problems where class membership lacks sharply defined criteria. It also offers the possibility to avoid losing time with unnecessary controversies such as deciding whether a virus is, or is not, a living system.

Binding of Ru(II) polyazaaromatic complexes to DNA: A 23Na NMR spin-lattice relaxation study

The possibility of using sodium-23 spin-lattice relaxation rate measurements to probe the interaction modes of Ru11 polyazaaaromatic complexes with DNA is investigated. The following complexes are considered: Ru(phen)3(2+) (phen = 1.10-phenanthroline), Ru(phen)2HAT2+ (HAT = 1,4,5,8,9,12-hexaazatriphenylene), and Ru(diMeTAP)3(2+) (diMeTAP = 2,7-dimethyl-1,4,5,8-tetraazaphenanthrene). The addition of Ru(diMeTAP)3(2+) to a solution of NaDNA leads to a decrease in the sodium-23 spin-lattice relaxation rate (R1) similar to the effect observed upon addition of Mg2+. This indicates that Ru(diMeTAP)3(2+) interacts like Mg2+ with DNA and consequently that the electrostatic interaction dominates the association with DNA, Ru(phen)3(2+) and Ru(phen)2HAT2+ diminish R1 more efficiently than Mg2+, in a manner similar to ethidium bromide, which is known for its intercalation properties. Thus interactions other than electrostatic occur between these two complexes and DNA. These results are in agreement with data obtained from other techniques, according to which Ru(phen)3(2+) and Ru(phen)2HAT2+ are located partially inside the DNA double helix, in contrast to Ru(diMeTAP)3(2+) which remains in the ionic atmosphere around the phosphate backbone.

Correlation between sonoluminescence, sonochemistry and cavitation noise spectra

The acoustic signal from the sonochemical production of H2O2 in water, as measured by the intensity and the width of the second harmonic, show a sensitive and correlated dependence to the presence of small amounts (millimolar range) of an anionic surfactant (SDS) in water. The graphic shows the link from the ultrasonic reaction to the measurable quantities. New possibilities to reliably control such processes is therefore opened.

On the Quantitative Measure of a Sonochemical Effect in Heterogeneous Sonochemistry

The measurement of a sonochemical effect (SE) requires the definition of the reference conditions for the so-called “silent reaction”. It is shown that it is impossible to define SE correctly in the case of heterogeneous reactions, due to the dramatic effect of the agitation on reaction rates. This is true not only from the quantitative point of view (effect of ultrasound on reaction rates) but also from the qualitative perspective (change of reaction pathway when ultrasound is applied). The first, and most dramatic, example of chemical switching described in the literature, and claimed to be due to ultrasound, is proven also to be observable under efficient agitation conditions.

The potential of 129Xe NMR relaxation measurements for the study of heme proteins

Monoatomic xenon can be complexed in the proximal cavity of metmyoglobin. This study highlights the potential of 129Xe relaxation rate measurements to obtain information on the xenon–metmyoglobin interaction.

Some Physico-Chemical Aspects of So-Called “Homogeneous Sonochemistry”

This paper is essentially devoted to the discussion of some physico-chemicals concepts, laws and formulae which are of interest in quantitative “homogeneous sonochemistry”. Only a few examples of sonochemical reactions will be given. Those interested by specific data will find many examples in books and review articles. A non-exhaustive list of references is given in the bibliography under the heading “general bibliography”.