From Steam Engines to Chemical Reactions: Gibbs’ Contribution to the Extension of the Second Law

The present work analyzes the foundations of Gibbs’ thermodynamic equilibrium theory, with the general aim of understanding how the Second Law—as formulated by Clausius in 1865—has been embodied into Gibbs’ formal system and extended to processes involving chemical reactions. We show that Gibbs’ principle of maximal entropy (and minimal energy) is the implicit expression of Clausius’ Second Law. In addition, by making explicit some implicit passages of Gibbs logical path, we provide an original formal justification of Gibbs’ principle. Finally we provide an analysis of how Gibbs’ principle—conceived for homogeneous isolated systems with fixed chemical composition—has come to be applied to systems entailing chemical transformations

Clausius’ Disgregation: A Conceptual Relic that Sheds Light on the Second Law

The present work analyzes the cognitive process that led Clausius towards the translation of the Second Law of Thermodynamics into mathematical expressions. We show that Clausius’ original formal expression of the Second Law was achieved by making extensive use of the concept of disgregation, a quantity which has subsequently disappeared from the thermodynamic language. Our analysis demonstrates that disgregation stands as a crucial logical step of such process and sheds light on the comprehension of such fundamental relation. The introduction of entropy—which occurred three years after the first formalization of the Second Law—was aimed at making the Second Law exploitable in practical contexts. The reasons for the disappearance of disgregation, as well as of other “pre-modern” quantities, from the thermodynamics language are discussed

Can estrogenic radicals, generated by lactoperoxidase, be involved in the molecular mechanism of breast carcinogenesis?

Mutations of regulatory genes, which perturb the mechanism of cell replication resulting in abnormal cell proliferation, are the main cause of cancer. Many endogenous and exogenous chemicals (including estrogenic hormones) are known to represent a major carcinogenic risk for humans. 2-OH- and 4-OH-derivatives of estrogenic molecules have been shown to form stable adducts with purine DNA bases and act as 'depurinating' agents, thus altering gene transcription (Cavalieri EL, Stack DE, Devanesan PD et al. Proc Natl Acad Sci USA 1997; 94: 10937-10942). Lactoperoxidase (LPO), which is produced by mammary glands, is likely to be involved in breast carcinogenesis, because of its ability to interact with estrogenic hormones and oxidise them through two one-electron reaction steps. We investigated the reactivity of LPO towards five molecules: 17-beta-estradiol (a natural hormone), diethylstilbestrol (a synthetic drug, supplied to pregnant women for preventing spontaneous abortion), exestrol (a synthetic antigonadotropic estrogen), 2-OH- and 4-OH-estradiol (catabolic products of estradiol). Enzymatically generated radical derivatives of such molecules were stabilized by spin-trapping or by chelation of a diamagnetic metal ion and characterized with EPR spectroscopy. A kinetic study of the oxidation process was carried out using EPR and UV-visible spectroscopy