Abstract: An apparatus for performing photochemical measurements on a liquid or liquid-containing sample includes a light generating system, an optical system configured for directing light from the light generating system towards the sample and a sensing system for measuring at least one optical property of the sample, wherein the light generating system is configured for generating light with intensity levels adjustable within a range, spanning at least three and preferably at least five orders of magnitude; and in that the optical system is configured for directing light from the light generating system towards the sample so as to generate a substantially uniform light intensity level, within a cylindrical region of the sample having a height larger than or equal to five time its radius.

Abstract: A method for detecting a reversibly photoswitchable chemical species in a sample, includes the steps of: a) illuminating the sample with light suitable to be absorbed by the chemical species triggering a reaction affecting an optical property of the chemical species, the first light being periodically-modulated at a fundamental modulation frequency; b) measuring the evolution of the optical property; c) extracting at least one of an in-phase component at a frequency which is an even multiple of the fundamental modulation frequency; and a quadrature component at a frequency which is an odd multiple of the fundamental modulation frequency of a signal representing the evolution; and d) using the extracted component or components for detecting the chemical species. An apparatus for carrying out the method is also provided.

Abstract: A method for detecting a photochemically active chemical species in a sample, comprising the steps of: a) illuminating the sample with light at a wavelength suitable to trigger a reaction affecting an optical property of the chemical species according to an illumination sequence, such that: in at least a first time window, the kinetics of the first reaction is limited by a photochemically-activated step of the reaction; and in at least a second time window, the kinetics of the first reaction is limited by a thermally-activated step; b) measuring the evolution of the optical property during the first and the second time windows; c) determining at least a first and a second time constant representing the kinetics of the first reaction in the first and the second time windows, respectively; and d) using the determined time constants for identifying the chemical species. An apparatus for carrying out such a method.

Abstract: The method according to the invention includes choosing a reaction presumed reaction mechanism; selecting, for said mechanism, at least one first function characteristic of a thermokinetic property that is invariant with the periodic variation frequency of a control parameter influencing said reaction, the first characteristic function being calculated at least from first-order oscillation amplitudes of the concentration of at least one of the species involved in said reaction. The method includes calculating a plurality of values of the first characteristic function from first-order oscillation amplitudes obtained experimentally and analyzing the calculated values of the first characteristic function to determine whether the first characteristic function is constant based on the calculated values, and if the first characteristic function is constant, assigning the presumed mechanism to said reaction.

Abstract: A method for separating a chemical or biological compound present in a mixture of similar compounds by diffusion in a medium, the method comprising reacting the compounds of the mixture with a component (P) present in the medium to obtain products (Qi), wherein the reactions Ci+P?Qi are reversible and have kinetic constants k1 and k2, and applying to the medium a varying field to which the compounds are sensitive, wherein the period of the field and the concentration of component (P) in the medium are determined from the kinetic constants (k1,k2) of the compound (C) to be separated in order to establish resonance condition between said reactions and the field and for giving compound C an apparent diffusion coefficient (Da) in the medium that is maximum.

Abstract: The invention relates to a novel grey gold alloy essentially without whitening element such as nickel, palladium and cobalt, characterized in that it contains in addition to the gold, copper, silver and manganese, according to the following proportions in percentages by weight, of: gold 75-78  silver 1-10 manganese  7-15; and remainder of copper to 100. This alloy is particularly advantageous for manufacturing jewels, notably by the disposable wax casting technique.

Abstract: A method for separating a chemical or biological compound present in a mixture of similar compounds by diffusion in a medium, the method comprising (i) introducing a mixture of compounds into said medium (ii) reacting the compounds (Ci) of the mixture in the medium with a component (P) present in the medium to obtain products (Qi), wherein the reactions Ci+P→Qi are reversible and have kinetic constants k1,I in the direction of production of products (Qi) and (k2,i) in the reverse direction; and (iii) applying to the medium a field that varies periodically with time and to which compounds (Ci) are sensitive, wherein the period of the field and the concentration of component (P) in the medium are determined as a function of the kinetic constants (k1,k2) of the compound (C) to be separated to establish resonance condition between said reactions and the field, for which compound C has an apparent diffusion coefficient (Da) in the medium that is a maximum value.

Abstract: The invention relates to a novel grey gold alloy essentially without whitening element such as nickel, palladium and cobalt, characterized in that it contains in addition to the gold, copper, silver and manganese, according to the following proportions in percentages by weight, of: 1 gold 75-78  silver 1-10 manganese  7-15; and remainder of copper to 100.