A complete treatment of a steady-state four-level model for the interpretation of OH laser-induced fluorescence measurements in atmospheric pressure flames

In order to obtain OH concentration measurements in atmospheric pressure flames from saturated fluorescence signal, we have developed a stationary four-level model. A general relationship between the measured upper state population and the total number density has been derived. The effects of the imbalance between the rotational transfer rates in the upper and ground states is analyzed. We show that in the case of comparable rotational rates, the results of our treatment are similar to the ones obtained with the balanced cross rate model. A set of complementary data which should facilitate absolute OH concentration measurements is also pointed out.     

The subvariety of commutative residuated lattices represented by twist-products

Given an integral commutative residuated lattice L, the product L × L can be endowed with the structure of a commutative residuated lattice with involution that we call a twist-product. In the present paper, we study the subvariety ${\mathbb{K}}$ of commutative residuated lattices that can be represented by twist-products. We give an equational characterization of ${\mathbb{K}}$ , a categorical interpretation of the relation among the algebraic categories of commutative integral residuated lattices and the elements in ${\mathbb{K}}$ , and we analyze the subvariety of representable algebras in ${\mathbb{K}}$ . Finally, we consider some specific class of bounded integral commutative residuated lattices ${\mathbb{G}}$ , and for each fixed element ${{\bf L} \in \mathbb{G}}$ , we characterize the subalgebras of the twist-product whose negative cone is L in terms of some lattice filters of L, generalizing a result by Odintsov for generalized Heyting algebras.     

Glivenko like theorems in natural expansions of BCK‐logic

The classical Glivenko theorem asserts that a propositional formula admits a classical proof if and only if its double negation admits an intuitionistic proof. By a natural expansion of the BCK‐logic with negation we understand an algebraizable logic whose language is an expansion of the language of BCK‐logic with negation by a family of connectives implicitly defined by equations and compatible with BCK‐congruences. Many of the logics in the current literature are natural expansions of BCK‐logic with negation. The validity of the analogous of Glivenko theorem in these logics is equivalent to the validity of a simple one‐variable formula in the language of BCK‐logic with negation. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A reliable source of very small amounts of hydrogen chloride for analytical purposes

Sources of small quantities of hydrogen chloride (nmol s^-1 and pmol s^-1), based on molecular diffusion through a membrane from a reservoir of strong hydrochloric acid, are described. Accurate procedures of standardizing and checking the sources are reported. Extension to other reagents is possible. This standardized source provides a reliable means for the preparation of gaseous reference mixtures as well as standard solutions of hydrochloric acid.     

Free MVn-algebras

In this note we characterize free algebras in varieties of MV-algebras generated by a finite chain L _n as algebras of continuous functions from the spectrum of the Boolean skeleton of the free algebra into L _n . Received May 9, 2006; accepted in final form May 15, 2007.     

Spectral effects in laser induced incandescence application to flame-made titania nanoparticles

Particle size is a crucial parameter in nanopowder use and production. A method to obtain information about this during the particle synthesis would be very valuable in order to optimize the process. In the field of nanoparticles flame synthesis, an extension of the techniques used in soot diagnostics sounds rather obvious, but it is far from being easily accomplished. In this paper investigations on the application of the laser induced incandescence to TiO₂ nanoparticles in a flame reactor are reported. The work basically concerns the effects of laser fluence on the spectral structure of the laser-excited radiation emitted from the particles. It will be shown that in many cases such a radiation cannot be plainly assumed as an incandescence signal. Measurements of the signal time decay are reported and interpreted in the light of the spectral indications. Finally, the dependence of such a time decay on the particle size is experimentally demonstrated.