Influence of Fluorescence

Fixler, D., Namer, Y., Yishay, Y. and Deutsch, M. (2006). Influence of fluorescence anisotropy on fluorescence intensity and lifetime measurement theory, simulations and experiments. IEEE Trans. Biomed. Eng. 53, 1141-52. 

Sodium nitroprusside has long been known to degrade under the influence of fluorescent lighting or sunlight [ 13]. Initial reaction [ 14] follows the equation ... 

Hummel, M.A., Tracy, T.S., Hutzler, J. M., Wahlstrom, J.L., Zhou, Y. and Rock, D.A. (2006) Influence of fluorescent probe size and cytochrome b5 on drug-drug interactions in CYP2 C9. Journal of Biomolecular Screening, 11 (3), 303-309. 

Figure 2-21 Effect of Temperature on Rate of Oxidation of Illuminated Corn Oil. Source From M.H. Chahine and J.M. deMan, Autoxidation of Corn Oil under the Influence of Fluorescent Light, Can. Inst. Food Sci. Technol. J., Vol. 4, pp. 24—28, 1971.

Membrane fouling characterization of protein/dextran mixtures has also been studied [29]. The first step of this work was addressed to examine the influence of fluorescent labeling on membrane fouling. Permeate fluxes of BSA/dextran... 

As would be expected, ds,trans isomerization was accompanied by a shift in absorption maximum to a longer wavelength, from 265 to 270 mp, with a concomitant rise in molecular extinction coefiBcient (see Table II). Ingeniously Dechene (1964) developed a spectrophotometric determination of vitamin D based upon this isomerization reaction. Solutions of ergocalciferol and cholecalciferol in hexane were allowed to react widi iodine of various concentrations under the influence of fluorescent light. He obtained an optimum ratio of iodine to vitamin... 

Protein adsorption has been studied with a variety of techniques such as ellipsome-try [107,108], ESCA [109], surface forces measurements [102], total internal reflection fluorescence (TIRE) [103,110], electron microscopy [111], and electrokinetic measurement of latex particles [112,113] and capillaries [114], The TIRE technique has recently been adapted to observe surface diffusion [106] and orientation [IIS] in adsorbed layers. These experiments point toward the significant influence of the protein-surface interaction on the adsorption characteristics [105,108,110]. A very important interaction is due to the hydrophobic interaction between parts of the protein and polymeric surfaces [18], although often electrostatic interactions are also influential [ 116]. Protein desorption can be affected by altering the pH [117] or by the introduction of a complexing agent [118]. 

Accuracy The accuracy of a fluorescence method is generally 1-5% when spectral and chemical interferences are insignificant. Accuracy is limited by the same types of problems affecting other spectroscopic methods. In addition, accuracy is affected by interferences influencing the fluorescent quantum yield. The accuracy of phosphorescence is somewhat greater than that for fluorescence. 

The aim of this work was to study the influence of a second ligand, the concentration and nature of surfactants on flumequine-sensitized fluorescence of lanthanides and the usage of such a mixed-ligand complex for fluorimetric determination of flumequine in hen meat tissues. 

Several methods were reported for the analysis of histamine, but the fluorimetric determination with o-phthaldialdehyde (OPA) the most widely used. It was shown that adducts, formed in the reaction of histamine with OPA in the presence of reducing agent, is more stable and gives high relative fluorescence intensity. The influences of different tiols on the fluorimeric determination histamine with OPA have been investigated. 

We detenuined the influence of oxy- and ketocarboxylic acids (succinate, fumarate, adipinate, a-ketoglutarate, isocitrate, tartrate, E-malate) on the luminescence intensity of the Eu-OxTc complex. These substances interact as polydentate ligands similarly to citrate with the formation of ternary complexes with Eu-OxTc. As to succinate, fumarate, adipinate and a-ketoglutarate this they cannot effectively coordinate with EiT+ and significant fluorescence enhancement was not observed. 

Further examples pf fluorescence stabilization and intensity augmentation as a result of treatment of the chromatogram with viscous, lipophilic liquids are listed in Table 22. The alteration of the pH [293] or the addition of organic acids or bases [292] have also been found to be effective. Wintersteiger [291] has also described the effect that the TLC layer itself (binder) can influence the fluorescence intensity. 

The simplest polymer-based EL device consists of a single layer of semiconducting fluorescent polymer, c.g., PPV, sandwiched between two electrodes, one of which has to be transparent (Fig. 1-1). When a voltage or bias is applied to the material, charged carriers (electrons and holes) are injected into the emissive layer and these earners arc mobile under the influence of the high (> 105 V enr1) elec-... 

Experiments on transport, injection, electroluminescence, and fluorescence probe the spatial correlation within the film, therefore we expect that their response will be sensitive to the self-affinity of the film. This approach, which we proved useful in the analysis of AFM data of conjugated molecular thin films grown in high vacuum, has never been applied to optical and electrical techniques on these systems and might be an interesting route to explore. We have started to assess the influence of different spatial correlations in thin films on the optical and the electro-optical properties, as it will be described in the next section. 

Fig. 3.2.2 Influence of pH on the initial light intensity of euphausiid luminescence when the fluorescent compound F and protein P are mixed in 25 mM sodium phosphate buffers of various pH values, each containing 1M NaCl, at near 0°C. Both F and P were obtained from Meganyctiphanes norvegica. From Shimomura and Johnson, 1967, with permission from the American Chemical Society.

In general compounds with heteroatoms (N, O, S and P) are more amenable to fluorescence reactions" than pure hydrocarbons. Under the influence of the catalytic sorbents substances rich in Jt-electrons are formed, that conjugate to rigid reaction products that are fluorescent when appropriately excited. The formation of fluorescent derivatives is frequently encouraged by gassing with nitrogen or carbon dioxide. 

At elevated temperatures and possibly under the catalytic influence of the sorbent surface there is probably elimination of functional groups to yield aromatic ring systems that are excited to fluorescence under long-wavelength UV light (X = 365 nm). 

Several studies were performed on the optimization of expression levels of ELP proteins in E. coli. In a recent example, the expression protocol was optimized for an ELP fusion with green fluorescent protein (GFP). This fusion protein was expressed and purified in a yield of 1.6 g/L of bacterial culture, which finally yielded 400 mg GFP/L bacterial culture. This extremely high yield was found after uninduced expression in nutrient-rich medium supplemented with phosphate, glycerol and certain amino acids, such as proline and alanine [234]. The influence of fusion order was also examined and it was found that positioning the ELP at the C-terminus of target protein resulted in significantly higher expression levels [35]. 

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