Fluorescence measurements with

The transient absorption spectrum of DMABN-F4 in acetonitrile, recorded at 1-ps delay shows an absorption band near 360 nm (Fig. 3a). This band can be attributed to the CT state by comparison with that reported for DMABN in acetonitrile at lOOps (Fig. 3b). For the latter, both the LE state decay and CT state risetime were found to be 6 ps in time-resolved fluorescence measurements with a 4-ps time-resolution streak-camera [6]. From various studies, the CT formation time is now well known to be 4-6 ps [1] so that, at 100 ps, only the CT state is present. Fig. 3a shows that, for DMABN-F4, the CT state is populated in less than 1 ps in acetonitrile. We can thus conclude from the present observation that the access to the CT state for DMABN-F4 is significantly faster than for DMABN in acetonitrile. 

Additional binding experiments conducted by fluorescence measurements with C76A mutant and D- and L-isopropylhydantoin and L-ethylhydantoin (D-ethylhydantoin is an inhibitor) showed that this mutant is unable to bind the D-isomers of the substrates. The same experiments carried out with C181A mutant proved that this mutant was not able to bind the L-isomers. These results indicate that cysteine 76 is responsible for the recognition of D-isomers of the 5-monosubstituted hydantoins, whereas cysteine 181 recognizes the L-isomers. 

High intensity and monochromaticity, resulting in a high spectral intensity, are ideal tools for spectroscopic investigations, especially for fluorescence measurements with low quantum yields, for the study of multi-photon processes and excited states, and for Raman spectroscopy. For example, important biomolecules like nucleic acids have an extremely low fluorescence quantum yield at room temperature. 

The following volumes of a solution containing 1.10 ppm of Zn- were pipetted into separatory funnels each containing 5.00 mL of an unknown zinc solution 0.00, 1.00, 4.00, 7.00, and 11.00. Each was extracted with three 5-mL aliquots of CCI4 containing an excess of 8-hydroxyquinoline. The extracts were then diluted to 25.0 mL and their fluorescence measured with a fluorometer. The results were as follows ... 

Figure 1. Instrumental configuration for fluorescence measurements with an intensified...

In biological samples local fluorescence measurements with PSTM do not have the deleterious effects of staining [78],... 

In particular, by means of fluorescence measurements with the use of 4 -(aminomethyl) fluorescein-labeled PMANa and PS- -PMANa (PMA Na and PS-ft-PMA Na, respectively) they studied the following polyion interchange reactions ... 

These criteria limit the applicahility of fluorescent dye-based sensors to only a handful of analytes. If a fluorescence-based method does not exist or is Incompatible with an optical sensor, an absorption sensor is the only alternative. There exist a large number of different absorbing dyes that are sensitive, selective and absorb in convenient regions of the spectrum. Several absorbance-based fiber-optic sensors have been described (8,25.26). Unfortunately, a major drawback with absorption spectroscopy is its inherent insensitivity. We decided to explore the possibility of using other optical techniques that can be used with indirect methods. A successful example has been presented which combines the sensitivity of the fluorescence measurement with the specificity of an absorbing dye and is based on an energy transfer mechanism (15). 

Estimating SO2 Stress by Chlorophyll Fluorescence Measurements with an Active System... 

The state of the reaction centres was monitored during all measurements by noting the Qy-band absorption and fluorescence maxima. Steady state absorption measurements were made using a Perkin-Elmer 554 spectrophotometer and fluorescence measurements with a Perkin-Elmer MPF-4 fluorimeter. Samples were maintained at 4 C while all measurements were taken and during time-resolved fluorescence experiments, the samples were also... 

The recovery of the photochemistry of PS2 was studied by fluorescence measurements with the same criterion of light and dark treatments . D-plants showed a dark value of Fo higher than in C-plants probably due to... 

ESTIMATING S0 STRESS BY CHLOROPHYLL FLUORESCENCE MEASUREMENTS WITH ACTIVE SYSTEM USED IN THE REMOTE SENSING MODE... 

While these initial experiments provided good evidence in support of this "molecular accordion" mechanism, many issues remained to be clarified. Here we examine the mechanism of the adsorption and docking of the polymers as they are added, below the LCST, to aqueous liposome suspensions. Special attention was paid to the role of the alkyl pendent groups during the adsorption process and to the importance of the physical state of tne lipid bilayer. These questions were addressed primarily through the use of fluorescence measurements with labeled polymers. Supportive evidence was provided by microcalorimetric studies. 

SEHiER et al. [110] describe a direct quantitative determination of anthranilic acid and some indole derivatives, without elution. Layers on 5 X 20 cm plates were chromatographed using solvent XIV, Table 89, sprayed with the Prochazka reagent (No. 123, Table 88), illuminated with UV light of wave-length 365 nm and the fluorescence measured with a slightly modifled Zeiss-Spektralphotometer PMQ II (Firm 155). The surface areas under the lines registered with a recorder were found to be directly proportional to the amount of material between 10 and 2000 ng. A TLC-attachment for the Zeiss Spektralphotometer has been developed with which direct routine qualitative and quantitative measurements on normal TLC-plates have become possible [41, 42]. 

Since the lifetime of the excited state is also characteristic of individual substances, and particularly of the environment of the molecule, time-dependent fluorescence measurements with polarized light, with variation of the excitation and polarization wavelength, can be performed. They give important information about the orientation and dynamics of the sample. Many of these methods are successfully applied in bio.sensing and bioanalytics [159],... 

Fluorescence measurements with A -(dodecanoyl)aminofluorescein (DAF) [40] bound in polystyrene-6Z )cA -poly(methacrylic acid) (PS-PMAA) micelles in... 

We found that excitation and emission maxima were 525 nm and 585 nm respectively, although the peaks were broad. The peak widths suggest that an Instrument with a filter-based optical system could be used to make fluorescence measurements with Nile Red. Using the protocol described above, we demonstrated that for coffeaeformls, lipid ml l (L) culture was linearly correlated (r 0.950) to fluorescence (F) (flow cytometer data) by the relationship F 3.59 L - 1.89. Cultures of A. coffeaeformls were sampled with time over a period of 270 hr., when cell lysis was detected. A similar relationship was found when a fluorometer was used In place of the flow cytometer, however. In these experiments the Independent variable was the number of cells x 10 (N) of a particular lipid composition. The relationships were... 

It avoids considering the selective dissolution of the IM which in fact will lead to the increase in copper concentration it explains the choice of the deposition of copper islands. The authors verified by fluorescence measurements with a confocal scanning laser microscope that pH is increasing above the individual copper islands. Unfortunately they did not observe local dissolution around Cu islands (Fig. 26) which could be used for vahdating the proposed simulation. 

Two modified membranes and one immodified membrane has been used for getting die results. The static protein adhesion was done by dipping the membrane into physiological protein solution at different times. For d5mamic protein adhesion measurement the modified Baumgartner chamber was used as a perfusion system with the labelled plasma proteins in physiological Tris-buffer. To reduce the influence of the surface of the tube, an artificial surface in the chamber, the system was preadsorbed with the protein that should be measured. Then fluorescence measurements with membranes were done as described above. 

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