SummaryA scanning-less single-photon counting system for FLIM and fluorescence anisotropy wide-field imaging is described and characterized in this paper. The two polarizations of the fluorescence are divided by a Glan prism and acquired at the same time by the Q A detector. Fluorescence decay profiles can be reconstructed for any desired area up to each pixel and used to calculate time-resolved fluorescence anisotropy decays.

The incorporation of guest molecules into the cavities of molecular sieves leads to a large variety of highly interesting materials. Zeolite L—an aluminosilicate with one‐dimensional channels of open diameter 7.1 Å—is a very versatile material for building highly organized host–guest systems. We present materials where organic dye molecules have been incorporated into the channels of zeolite L by means of diffusion, to build artificial photonic antenna systems. The channel entrance can be plugged by adding closure molecules that then connect the guest molecules inside with materials or molecules outside of the zeolite channels, since they can act as extensions of the interior of the zeolite crystal. The photophysical processes taking place in such dye‐loaded zeolite L antennae can be studied either on single‐micrometer‐ or submicrometer‐sized crystals or on crystals dispersed in a solvent or coated as thin layers on a support. The energy‐transfer process occurring is of the Förster‐type, and its transfer rate can be tuned by separating the donor dyes and the acceptor dyes locally by varying amounts of spacer molecules. The distribution of the dye molecules and empty sites within a zeolite crystal has been modeled by means of a Monte Carlo simulation. The Förster energy migration and transfer steps are described as a random walk.

ABSTRACT:The equilibrium volume change and the elastic modulus of poly(N-isopropylacrylamide) (PNIPA) gels containing styrene-butadiene latex were investigated. It is considered that the presence of latex particles restricts the space for polymerization and which also affects on the elastic contribution of PNIPA gels. It was found that the swelling behavior of these gels was very similar to those found in the case of dependence of cross-link density. On the other hand, tensile modulus of the gels increased drastically, although these gels seem to be swelling enough. This anomalous increment of the elasticity is assumed to depend on the way to bind two elastic components, which are the highly dense PNIPA gel phase around the latex particles and the usual PNIPA gel network. It appears that the increment of elasticity against latex concentration could be classified into two mechanisms. The first, in the low latex concentration range, the dense gel phases are dispersed apart each other, the second, in the range of high latex concentration, C ≥ 12.0 wt%, the elasticity of the gel obeyed parallel model because of the formation of macro network with dense gel phases overlapped whole volume of gels.KEY WORDS Poly(N-isopropylacrylamide) (PNIPA) Gel / Volume Phase Transition / Elastic Modulus / Latex / Macro Network / The equilibrium volume change of poly(N-isopropylacrylamide) (PNIPA) gel was generally explained by Flory-Rehner's theory. [1][2][3][4] The gist of this theory is based on the integration of thermodynamics for polymer solution and statistical mechanics for rubber elasticity. These effects act on gel to dissolve its chains into solvent, on the other hand, to tug them together, thus they are called mixing and elastic contribution, respectively. The volume of gel, i.e., concentration of polymer, is determined by the equilibrium condition of mixing and elastic contribution to the osmotic pressure of gels.As far as the application to homogeneous polymer network is concerned, the conventional theory is useful semi-quantitatively. However, it is considered that the actual gel might be formed inhomogeneous network depending on the condition of polymerization or crosslinkage. 5-8 Therefore, manifold experiments in different conditions of polymerization remain as an important research to be discussed further.In this report, we would like to propose PNIPA gel containing styrene-butadiene latex as an available gel to vary only the elastic contribution. It is expected that the latex particles would not affect on the mixing contribution to PNIPA chain like as the change of solvent composition. Moreover, the presence of latex particles restricts the space for polymerization and which also affect on the elasticity of the gels. Thus, the artificial inhomogeneity induced by latex seems to be a valid method to study the nature of inhomogeneous network of gels. EXPERIMENTAL SampleSample gels were prepared by usual free radical copolymerization in latex-aqueous solution. Latex beads, kindly supplied by Nippon Zeon Co., Ltd., is ...