SYNOPSISNatural and modified polyflavonoid tannin extracts have been shown to behave as superplasticizers of cement and concrete mixes, improving fluidity without any significant retardation of the onset of hardening. This was shown by applied tests, by conduction calorimetry, and by X-ray diffraction analysis. The tannin extracts' behavior was ascribed to the balance of different effects, namely, (1) their increase in molecular mass induced by the presence of the silicate and aluminate component of cement, (2) the decrease first and then stabilization of the molecular mass and improved solubility induced by introduction of sulfonic groups in the structure of the tannin, and ( 3 ) the stabilization in the molecular mass induced by urea through its hindrance to tannin autocondensation and its decrease of tannin extract colloidal association in a water solution. 0 1996 John Wiley & Sons, Inc. I NTRO DU CTl ONPlasticizers/dispersion agents are additives which are incorporated into concrete to improve its workability, reduce its water content needs, and to improve its strength development. Unfortunately, these properties are usually mutually exclusive. Thus, all plasticizers cause also a retardation in the setting and early strength development of concrete. Superplasticizers instead are comparatively newer products and far more effective in decreasing the viscosity and improving the workability of a fresh concrete mix than are ordinary plasticizers. This improved workability without addition of extra water does not entail a loss of final strength. It is also important that use of such additives does not result in gross retardation of concrete setting or initial low strength.' Superplasticizers can turn doughlike mixes into free flowing fluids and are generally based on sulfonated melamine-formaldehyde resins or naphtalene sulfonate-formaldehyde resins and

The adjective ἱερός is a central term in Greek religion and is used in various contexts. Generally translated ‘sacred’, it indicates that an object has been conceded to the gods and is now in relation with them (relation of belonging, protection, etc.). It appears frequently in Greek inscriptions in the expression τὰ ἱερά, to designate sacred objects or, in a more abstract meaning, sacred matters.

have kindly contributed to the improvement of my English. Any remaining error is mine. 1 See in particular ps. Aristotle, Virtues and vices, 1251a: "There are three types of offence (iδικ‰α): impiety, greediness (πλεονεξ‰α) and outrage (Ûβρις). Impiety is a fault (πλη † †•λεια) regarding gods, daemons or deceased persons, parents or homeland", and Polybius, XXXVI, 9: "Impiety means committing a wrong (• †αρτoνειν) in respect of what is related to gods, parents and deceased persons". A common point between these elements is that normally they should all be granted a certain amount of honour (τι †n). }σ•βεια can thus be seen as a lack of τι †n. 2 On this dialogue, see L. BRUIT ZAIDMAN, Le commerce des dieux : eusebeia, essai sur la piété en Grèce ancienne, Paris, 2001, p. 154 157. One could object to my statement that not much could easily be defined with an interlocutor such as Socrates. 3 It is however not certain that these trials took place, and scholars have different positions on the matter. E. DERENNE, Les procès d'impiété intentés aux philosophes à Athènes au Vme et au IVme siècles avant J.7C., Liège/Paris, 1930, provides a quite obsolete though inescapable overview of these trials. More recently, on Protagoras, see D. LENFANT, "Protagoras et son procès d'impiété : peut on soutenir une thèse et son contraire ?", Ktema 27 (2002), p. 135 154, which rightly casts doubt on the historicity of this trial and criticizes anachronistic concepts, such as "intellectual freedom" or "tolerance";

No abstract

No abstract