Fluorescence investigation of model compounds for light-emitting alternating copolymers in heterogeneous environments.
In this paper, the fluorescence spectra of the model compounds M(TPA-PPV) and M(TPA-PAV) of novel light-emitting alternating copolymers, were studied and the effect of KNO3 on the interaction between the model compounds and the ionic micelle-water interface was also investigated. The following is found: (i) the fluorescence changes of M(TPA-PPV) are related to the state of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) solution: (ii) an aggregated state can be formed in M(TPA-PAV) solution at low concentration of CTAB; (iii) higher concentrations of KNO3 may affect the interaction between the model compounds and the ionic micelle-water interface.
Thermodynamic study on the effects of beta-cyclodextrin inclusion with anilinonaphthalenesulfonates.
Thermodynamic parameters and stoichiometries for the binding of anilinonaphthalenesulfonates to beta-cyclodextrin are obtained from steady-state fluorescence intensity and anisotropy measurements. Specifically, formation constant, enthalpy, and entropy values are obtained for complexes of beta-cyclodextrin with eight different substrate molecules at five different temperatures and six different pH values, and their associated errors are given. We propose an explanation of the relative magnitudes of the values obtained with regard to the geometry of the substrate and the importance of the various noncovalent interactions responsible for the complexation.
THE IRON-ACETOCARMINE METHOD OF FIXING AND STAINING CHROMOSOMES
A short description of this procedure was given in Vol. 55 of the American Naturalist, pp. 573â€”574. The method has now been used almost daily for five years, and certain improvements have suggested themselves. The solution can be prepared by mixing about equal volumes of glacial acetic acid and water. To this is added powdered carmine in excess. The liquid is then â€ ? just brought to boil, cooled, and decanted. To the red solution there are then added a few drops of a solution of ferric hydrate in 50 per cent. acetic acid, to act as a mordant. The amount of iron varies with different objects. Too much produces a precipitate in a short time. The more