FOURIER TRANSFORM INFRARED SPECTRAL STUDIES ON THE SCHIFF BASE MODE OF ALL-trans BACTERIORHODOPSIN and ITS PHOTOINTERMEDIATES,K and L*

Abstract– Difference Fourier transform infrared spectra were recorded for bacteriorhodopsin upon irradiation at 230, 170 or 77 K, which gave, respectively, the spectrum of the M, L or K intermediate minus unphotolyzed all-trans bacteriorhodopsin (denoted as BR). By replacement of the Schiff base nitrogen with ¹⁵N, or of either its hydrogen at N or C₁₅ with deuterium, the vibrational bands related to the Schiff base were identified and the isotope-shifts evaluated for BR, K and L. The 1348 cm^?l band of BR and K and the 1400 cm^?1 band of L were sensitive to each of these isotope substitutions. The 1254 cm^?1 band of BR, the 1245 cm^?1 band of K and the 1301 cm^?1 band of L were sensitive to either N- or C₁₅-deuteration but not to ¹⁵N-substitution. The N—D in-plane bending vibration of K and L appeared at 969 and 997 cm^?1, respectively, upon substitution with D₂O. All the results show that L is larger in frequencies related to the N—H in-plane bending vibration than K or BR and suggest that L has the strongest interaction with the protein. Among the bands containing an N—H bending vibration, the 1348 cm^?1 band of K was more intense than the corresponding band of L at 1400 cm^?1. The C₁₅-deuteration-induced upshift of the 1245 cm^?1 band of K was unobservable for the 1301 cm^?1 band of L. Such differences between L and K might be brought about by a distortion in the retinal moiety close to the protonated Schiff base of the 13-cis chromophore.     

Optical microscopy to study single nanoparticles electrochemistry: From reaction to motion

Nanoparticles (NPs)-based electrochemical devices are generating a growing interest and optical microscopy has recently proven to be a powerful tool to apprehend their electrochemical behavior. Through several striking examples, this review demonstrates how label-free optical imaging coupled to an electrochemical actuation can be used to probe operando the physical and electrochemical properties of single NPs, with high resolution and sensitivity and without additional emitters. Such an approach can be particularly relevant to establish clear structure-motion/reactivity relationships required to optimize NPs exploited as electrode materials.     

Vinyl nosylates as partner in copper and silver co-catalyzed Sonogashira cross-coupling reactions

Vinyl nosylates, readily obtained from β-dicarbonyl derivatives, could be efficiently engaged in Sonogashira cross-coupling reactions, either cocatalyzed by copper or silver salts. The para-nitrobenzenesulfonate (nosylate) group allows this coupling to be performed under very mild conditions (room temperature). These new leaving group and mild conditions could be applied to the synthesis of acetylenic coumarinyl derivatives and to the total synthesis of an acetylenic monoterpene natural product, named cleviolide.     

A new non-parametric detector of univariate outliers for distributions with unbounded support

The purpose of this paper is to construct a new non-parametric detector of univariate outliers and to study its asymptotic properties. This detector is based on a Hill’s type statistic. It satisfies a unique asymptotic behavior for a large set of probability distributions with positive unbounded support (for instance: for the absolute value of Gaussian, Gamma, Weibull, Student or regular variations distributions). We have illustrated our results by numerical simulations which show the accuracy of this detector with respect to other usual univariate outlier detectors (Tukey, MAD or Local Outlier Factor detectors). The detection of outliers in a database providing the prices of used cars is also proposed as an application to real-life database.     

Intégrales oscillantes stochastiques: Estimation asymptotique de fonctionnelles caractéristiques

A general method for estimating E(exp(iNΦ)) for N → + ∞ is given using a stationary phase method in Wiener space and stochastic variational calculus.     

On the probability that n and [n c] are coprime

We prove that for any positive real number which is not an integer, the density of the integers which are coprime to , a result conjectured by Moser, Lambek and Erd Hs. This revised version was published online in June 2006 with corrections to the Cover Date.     

Closure laws for a two-fluid two-pressure modelLois de fermeture pour un modèle à deux pressions d'écoulement diphasique

Closure laws for interfacial pressure and interfacial velocity are proposed within the frame work of two-pressure two-phase flow models. These enable us to ensure positivity of void fractions, mass fractions and internal energies when investigating field by field waves in the Riemann problem. To cite this article: F. Coquel et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 927–932.