Simultaneous strain and coherent imaging using coupled photorefractive holography and shearography through scattering media.

The direct simultaneous acquisition of coherent imaging and strain information is of particular importance in the biomechanical characterization of biological tissue. This type of simultaneous information acquisition can be accomplished using a coupled photorefractive holography and shearography system for imaging and strain measurements, respectively. Optical scattering in a conventional speckle shearing interferometer rapidly reduces the contrast of the shearing fringes, thereby limiting the use of such interferometers with opaque surfaces.

Simultaneous coherent imaging and strain measurement using coupled photorefractive holography and shearography.

By coupling photorefractive holography with speckle shearography, it is possible to simultaneously perform both coherent imaging and strain measurement. Use of the photorefractive effect, which is insensitive to incoherently scattered light, is a significant advantage in coherent imaging as described. Experimental results obtained from a centrally loaded steel plate are presented.

High transmission efficiency for surface plasmon resonance by use of a dielectric grating.

The efficiency of the transmission of surface plasmon waves by use of a dielectric diffraction grating is discussed. The Kretschmann device allows us to obtain a surface plasmon resonance that consists of an absorption peak in the reflection spectrum. When surface plasmon resonance occurs, the TM-polarization mode of the incident electromagnetic wave is neither transmitted nor reflected.

Characterization of dupont photopolymer: determination of kinetic parameters in a diffusion model.

We investigate the recording dynamics of Omnidex photopolymer film from DuPont. We use a reviewed version of the diffusion model proposed by Zhao and Mouroulis [J. Mod.

Disk-growing algorithm for phase-map unwrapping: application to speckle interferograms.

Interferometric techniques combined with phase shifting allow computation of the phase that is linked to the displacement of the object under study. The phases before and after displacement are computed from three or more interferograms (called specklegrams when speckle is used as the information carrier). Subtraction of these two phase patterns leads to a raw phase map.

Design for polarizing holographic optical elements.

We present results of the application of a three-dimensional rigorous-vector coupled-wave theory to the design of polarizing holographic optical elements. Two different cases have been selected giving rise to two types of element, one of which is completely original. Experimental realizations were performed.

Measurement of chromium content in dichromated gelatin by x-ray fluorescence.

X-ray fluorescence was applied to the determination of the chromium-ion content in developed dichromated gelatin after exposure. It was found that the Cr(3+) ions irreversibly linked to the gelatin molecules do not exceed one half of the original concentration of the ions. A similar study was carried out on the hardening of dichromated gelatin during dark reaction: as long as the degree of hardening of the gelatin allowed the chromium ions to migrate out of the film during development, the final Cr(3+) content was less than or equal to one half the original concentration.

Measure of the diffraction efficiency of a holographic grating created by two Gaussian beams.

We present a methodology for analyzing the characteristics of a photosensitive material for holography. When two Gaussian beams of equal intensities are exactly superimposed on the recording material, the modulation of the interference pattern is equal to unity. When they are no longer exactly superimposed, this modulation varies from one to zero depending on the analyzed point.

Adriamycin and derivatives interaction with the mitochondrial membrane: O2 consumption and free radicals formation.

Adriamycin induces the formation of semiquinone free radicals, O(2) and OH. species, in beef heart intact mitochondria, submitochondrial particles and complex I-III containing proteoliposomes. Free radicals were detected by the use of Electron Spin Resonance (ESR) spectroscopy with the spin trapping method.

Potentiation of oxygen toxicity by menadione in Saccharomyces cerevisiae.

The cytotoxicity of molecular oxygen can be sharply increased in the yeast Saccharomyces cerevisiae by the use of redox compounds capable of shunting electrons in vivo and of spontaneous reoxidation under aerobic conditions. Among these redox compounds, menadione (Vitamin K3) is particularly able to stimulate the cyanide-resistant respiration of the yeast cells. Under steady-state conditions, the efficiency of menadione is modulated by the physiological state of the yeast cells and also depends on the availability of reducing agents within the cell.

E.s.r. of spin-trapped radicals in gamma-irradiated polycrystalline DL-alanine. A quantitative determination of radical yield.

The quantitative aspects of determining free radicals in polycrystalline amino acids gamma-irradiated at room temperature and subsequently dissolved in spin-trap solutions were investigated. The deamination radical in DL-alanine was used for detailed studies and 2-methyl-2-nitrosopropane (MNP) was employed as the spin-trap. The spin-trapping efficiency (the number of radicals spin-trapped in solution divided by the number of radicals initially present in the gamma-irradiated solid) was found to be in the range 1 to 10 per cent for aqueous solutions depending on the experimental conditions.

Visible-light-induced OH radicals in DNA-proflavine complexes: an e.p.r. and spin trapping study.

Using the spin-trapping technique, irradiation with visible light of complexes between DNA and proflavine was shown to generate OH radicals. The characteristic spectra were not obtained when proflavine or DNA were irradiated alone, nor when oxygen was absent. Using DMPO as a spin trap we found that the intensity of the DMPO-OH e.

E.S.R. of spin-trapped radicals in aqueous solutions of 5-halo derivatives of nucleic acid constituents: reactions of hydrated electrons, hydroxyl radicals and U.V. photolysis.

In order to obtain information concerning the mechanism of radio- and photosensitization due to 5-halogen substituted nucleic acid constituents, the free radicals produced in iodo-, bromo-, chloro- and fluoro-derivatives of uracil, uridine and deoxyuridine by reaction with hydrated electrons and with hydroxyl radicals and by direct U.V. photolysis have been studied by e.

E.S.R. of spin-trapped radicals in gamma-irradiated polycrystalline nucleic acid constituents and their halogenated derivatives.

Free radicals in gamma-irradiated polycrystalline nucleic acid constituents and their 5-halogenated derivatives have been studied by e.s.r.

[Photosensitization of consitutents of nucleic acids by proflavine. Mechanism of formation of hydrogen addition radicals in frozen aquenous solutions (author's transl)].

It is shown that the insertion of nucleotides between proflavine molecules is favourable to photosensitization. Furthermore (1) each molecule of proflavine gives at the most one free radical in the substrate, (2) the chromophore is largely restored when oxygen is not present, (3) superoxide radicals are observed in the presence of oxygen, and (4) formyl radicals are detected. The scheme elaborated for the mechanism gives an explanation for all these observations.

Indirect EPR evidence for the production of singlet oxygen in the photosensitization of nucleic acid constituents by proflavine.

EPR spectroscopy is used to analyse the influence of D2O and NaN3 on the free radicals induced in frozen aqueous solutions of 5'-thymidine monophosphate photosensitized (lambda greater than 320 nm) by proflavine at 205 K. The results can be explained if the production of singlet oxygen during the process is assumed.

Triplet state population study in relation to the aggregation of proflavine in frozen solutions.

The evolution of the proflavine triplet state population with the extent of aggregation is examines, by ESRmeasurements, as a function of organic solvents and mineral salts, well known for their ability to influence the aggregation process. The intensity of the triplet state population has also been investigated as a function of pH. The insertion of aromatic molecules like DNA's nucleotides between dye molecules is shown to increase the intensity of the triplet state.