Search results for "LIGHT"

Contribution à l'étude des « goûts de lumière » dans le vin de champagne *. 1. Aspects analytiques - Dosage des mercaptans et des thiols dans les vins

1977

<p style="text-align: justify;">Plusieurs accidents appelés « goûts de lumière » ou « goûts de réduit » ont été observés dans les vins de champagne au cours de ces dernières années. Dans ce travail, nous avons mis au point une méthode d'appréciation de ces goûts par dosage des groupements thiols ou mercaptans dans les vins. L'analyse comparative montre une bonne concordance entre la concentration en groupements thiols et l'appréciation gustative.</p><p style="text-align: justify;">+++</p><p style="text-align: justify;">For some years, accidents called « light tastes » or « reduced tastes » have been occured in Champagne wines; a method for thiols and mercaptans…

Dye-sensitized nanostructured TiO2 film based photoconductor

2008

Grooves were etched in a conductive layer of a conductive, transparent glass, and a nanoporous TiO2 film was deposited on both the conductive and nonconductive area. The width of the grooves was 100 $\mu$m and 150 $\mu$m. A transparent TiO2 film was dye-sensitized, covered with an electrolyte, and sandwiched with a cover glass. The conductivity of the dye-sensitized TiO2 film permeated with electrolyte was studied in the dark and under illumination, and was observed to be dependent on light intensity, wavelength and applied voltage. This study shows that dye-sensitized nanoporous films can be used as a wavelength dependent photoconductor.

Levy flights in confining environments: Random paths and their statistics

2013

We analyze a specific class of random systems that are driven by a symmetric L\'{e}vy stable noise. In view of the L\'{e}vy noise sensitivity to the confining "potential landscape" where jumps take place (in other words, to environmental inhomogeneities), the pertinent random motion asymptotically sets down at the Boltzmann-type equilibrium, represented by a probability density function (pdf) $\rho_*(x) \sim \exp [-\Phi (x)]$. Since there is no Langevin representation of the dynamics in question, our main goal here is to establish the appropriate path-wise description of the underlying jump-type process and next infer the $\rho (x,t)$ dynamics directly from the random paths statistics. A pr…

Silver Nanoparticles in Heterogeneous Plasmon Mediated Catalysis

2015

Metallic nanoparticles are considered a new class of heterogeneous photocatalysts due to their ability to absorb solar light and convert it into chemical energy. Here, we focus on the use of silver nanoparticles in light driven catalytic processes. This chapter will start with a brief introduction to the currently available nanocomposites that contain silver nanoparticles. Then, the mechanisms behind the photocatalytic activity of those nanocomposites will be discussed.

From Spherical Mesopores to Worm-Shaped Mesopores : Morphology Transition in Titania–Polystyrene-b-poly(ethylene oxide) Composite Films with Increasi…

2013

A morphology transition from spherical mesopores to worm-shaped mesopores within titania block copolymer composite thin films has been observed by varying the sol–gel reaction time from 40 min to 48 h in the four-component templating system of polystyrene-$\mathit{b}$-poly(ethylene oxide) (PS-$\mathit{b}$-PEO), 1,4-dioxane, concentrated HCl, and titanium tetraisopropoxide (TTIP) with a PS-$\mathit{b}$-PEO mass concentration of 0.25 wt.-%. The impact of the sol–gel reaction time on the local structure, long-range lateral structure, and vertical structure of the as-prepared, calcined, and UV-degraded thin films as well as the structural changes in solution have been systematically investigate…

Supramolecular assembly using helical peptides

1997

Abstract We investigated supramolecular assemblies of various hydrophobic helical peptides. The assemblies were formed at the air/water interface or in aqueous medium. The hexadecapeptide, Boc-(Ala-Aib)8-OMe (BA16M), was reported to take α-helical structure by X-ray analysis. Several derivatives were prepared, which have the repeating sequence of Ala-Aib, Lys(Z)-Aib or Leu-Aib, or have the terminal chemically modified. CD spectra of the peptides indicated helical conformation in ethanol solution. The surface pressure-area isotherms of the peptide monolayers showed an inflection at the surface area corresponding to the cross section along the helix axis, and the monolayers were collapsed by …

The Influence of the Proton Gradient on the Activation of Ferredoxin-NADP+-oxidoreductase by Light

1988

Ferredoxin-NADP+-oxidoreductase (FNR, EC 1.18.1.2) has been shown to be activated by light within a few seconds during dark-light transitions and inactivated in the dark. In previous papers this could be pointed out by the correlation of cytochrome f induction kinetics to the rate of NADP-photoreduction and the variable fluorescence. The present study deals with the role of the proton gradient during the activation process. The transition from an inactive to an active form is followed continuously in an in situ system. The steady-state rate of NADP-photoreduction is affected only by ionophores which inhibit a formation of the proton gradient, but not by inhibitors of the electric field. It …

Double Laser LIBS and micro-XRF spectroscopy applied to characterize materials coming from the Greek-Roman theater of Taormina

2009

The laser-induced breakdown spectroscopy (LIBS) is an applied physical technique that has shown, in recent years, its great potential for rapid qualitative analysis of materials. The possibility to implement a portable instrument that perform LIBS analysis makes this technique particularly useful for in situ analysis in the field of cultural heritages. The aim of this work is to compare the results, obtained by LIBS measurements with X-Ray Fluorescence (XRF) ones, on calcareous and refractory materials coming from the Greek-Roman theater of Taormina. Calibration curves for LIBS and XRF were obtained by measuring certified reference materials and using them as standards. LIBS measurements we…

1982

Mass measurements of very high accuracy by time-of-flight ion cyclotron resonance of ions injected into a penning trap

1989

Abstract The possibility of absolute mass measurements using time-of-flight detection of ion cyclotron resonance on ions injected into a Penning trap has been demonstrated. Resolving powers of 2 million have been achieved, with accuracies of about 0.5 ppm. Absolute accuracy is obtained by direct observation of the sum frequency of the cyclotron and the magnetron motions through the use of an azimuthal quadrupole r.f. field to transform initial magnetron motion into cyclotron motion. Imperfections of the Penning trap leading to systematic errors are discussed. The system has been designed specifically to measure the masses of radionuclides produced at the on-line isotope separator ISOLDE. Wi…