QRS detection using S-Transform and Shannon energy.

This paper presents a novel method for QRS detection in electrocardiograms (ECG). It is based on the S-Transform, a new time frequency representation (TFR). The S-Transform provides frequency-dependent resolution while maintaining a direct relationship with the Fourier spectrum.

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization.

In the present paper, the photoredox catalysis is presented as a unique approach in the field of photoinitiators of polymerization. The principal photocatalysts already reported as well as the typical oxidation and reduction agents used in both reductive or oxidative cycles are gathered. The chemical mechanisms associated with various systems are also given.

Study of water absorption in Raffia vinifera fibres from Bandjoun, Cameroon.

The study is focused on the water diffusion phenomenon through the Raffia vinifera fibre from the stem. The knowledge on the behavior of those fibres in presence of liquid during the realization of biocomposite, is necessary. The parameters like percentage of water gain at the point of saturation, modelling of the kinetic of water absorption, and the effective diffusion coefficient were the main objectives.

Ordered hybrids from template-free organosilane self-assembly.

Despite considerable achievements over the last two decades, nonporous organic-inorganic hybrid materials are mostly amorphous, especially in the absence of solvothermal processes. The organosilane self-assembly approach is one of the few opportunities for creating a regular assembly of organic and inorganic moieties. Additionally, well-established organosilicon chemistry enables the introduction of numerous organic functionalities.

Squarylium-triazine dyad as a highly sensitive photoradical generator for red light.

New dyads, based on squarylium dye and substituted-triazine, were synthesized that exhibit an intramolecular photodissociative electron-transfer reaction. The compounds were used as a red-light photoradical generator. The photochemical activity of the dyad was compared to the corresponding unlinked systems (S+T) by determining the rate constant of electron transfer.

High-performance photoinitiating systems for free radical photopolymerization. Application to holographic recording.

The photoinitiating systems (PIS) usable in free radical photopolymerization are briefly reviewed. Apart conventional Type I and Type II photoinitiators, three-component PIS exhibiting a photocyclic behavior are discussed. The mechanisms of photoreaction are presented, highlighting the role of a redox additive which reacts with the photoinitiator photoproduct.

Multi-site study of surgical practice in neurosurgery based on surgical process models.

Surgical Process Modelling (SPM) was introduced to improve understanding the different parameters that influence the performance of a Surgical Process (SP). Data acquired from SPM methodology is enormous and complex. Several analysis methods based on comparison or classification of Surgical Process Models (SPMs) have previously been proposed.

Block copolymer stabilized nonaqueous biocompatible sub-micron emulsions for topical applications.

Polyethylene glycol (PEG) 400/Miglyol 812 non-aqueous sub-micron emulsions were developed due to the fact that they are of interest for the design of drug-loaded biocompatible topical formulations. These types of emulsions were favourably stabilized by poly (2-vinylpyridine)-b-poly (butadiene) (P2VP-b-PBut) copolymer with DPBut>DP2VP, each of these sequences being well-adapted to the solubility parameters of PEG 400 and Miglyol 812, respectively. This type of block copolymers, which might limit the Ostwald ripening, appeared to be more efficient stabilizers than low molecular weight non-ionic surfactants.

Micellization of pH-stimulable poly(2-vinylpyridine)-b-poly(ethylene oxide) copolymers and their complexation with anionic surfactants.

The micellization behavior was examined for a series of 3 pH-stimulable poly(2-vinylpyridine)-b-poly(ethylene oxide) (P2VP-b-PEO) copolymers, with a constant composition of 67.5±1.5wt% PEO and increasing molecular weight.

Quantification of the 16S-23S rRNA internal transcribed spacers of Burkholderia xenovorans strain LB400 using real-time PCR in soil samples.

This study establishes a new real-time PCR assay (using SYBR Green™ detection) for the identification and the direct quantification of specific individual Burkholderia xenovorans strain LB400 from DNA samples of soil and sediment. Specific primers were designed to amplify a 190-bp fragment of the 16S-23S rRNA internal transcribed spacers (ITS) from LB400. The specificity of primers was evaluated using 21 strains.

Block copolymer self-assembly in mesostructured silica films revealed by real-time FTIR and solid-state NMR.

Over the past ten years, understanding the self-assembly process within mesostructured silica films has been a major concern. Our characterization approach relies on two powerful and complementary techniques: in situ time-resolved FTIR spectroscopy and ex situ solid-state NMR. As model systems, three silica/surfactant films displaying various degrees of mesostructuration were synthesized using an amphiphilic block copolymer (PEO-b-PPO-b-PEO) via a UV light induced self-assembly process.

Optimization of a photopolymerizable material based on a photocyclic initiating system using holographic recording.

A set of photoinitiating systems (PIS) for free radical photopolymerization was studied using time-resolved spectroscopic experiments, real-time FTIR and holographic recording. It is shown that the efficiency of the photoinitiating system can be drastically increased when a redox additive is added to the conventional dye/coinitiator system by virtue of photocyclic behaviour. The homogeneous photopolymerization process was found to reach a fast vitrification, limiting the conversion at about 55%.

Photopatterning of multilayer n-alkylsilane films.

Surface photopatterning of organosilane self-assembled monolayers (SAM) has received increasing attention since its introduction 20 years ago. Herein we report for the first time a cost-efficient soft photopatterning technique affording amplified 3D multilayer structures. The essential chemistry relies on a spatially controlled photoacid-catalyzed hydrolysis and polycondensation of n-alkyltrimethoxysilane precursors (n-C(12)H(25)Si(OCH(3))(3),).

Insights into photoinduced sol-gel polymerization: an in situ infrared spectroscopy study.

Photoacid-catalyzed sol-gel polymerization is now recognized as a powerful single-step synthetic approach to the synthesis of hybrid films, which can be distinguished from conventional sol-gel methods by higher reactivity and a solvent-free process. Despite its utility, the mechanism is not yet understood, in particular what chemical, physical, and photochemical parameters determine the precise sequence, kinetics, and advancement of this UV inorganic photopolymerization. Here, using mainly transmission real-time Fourier transformed infrared (RT-FTIR) spectroscopy, we characterize in situ the hydrolysis-condensation reactions of oligomeric silicon alkoxides and the formation of byproducts.

Iridium Photocatalysts in Free Radical Photopolymerization under Visible Lights.

A series of iridium(III) complexes was designed and investigated as new potential photocatalysts for radical polymerization reactions. The photocatalytic reduction cycle involves the combination of an iridium complex with an amine (e.g.

Organic Photocatalyst for Polymerization Reactions: 9,10-Bis[(triisopropylsilyl)ethynyl]anthracene.

A new organic photocatalyst (9,10-bis[(triisopropylsilyl)ethynyl]anthracene, ) is proposed here for the formation of free radicals under very soft irradiation conditions under air through a photoredox catalysis. It works according to an oxidative cycle that uses the combination of , a diphenyl iodonium salt along with a silane. This behavior is highlighted through an investigation of its excited state and redox properties.

Depth characterization of photopolymerized films by confocal Raman microscopy using an immersion objective.

The depth characterization of photopolymer films by confocal Raman microscopy is often troublesome due to refraction effects. To minimize these effects, we used an oil immersion objective and a method was developed to avoid penetration of the oil without damaging the sample surface. Since the surface may be sticky if oxygen in the air inhibits the photopolymerization, a protective layer could not be put onto the film.

Self-organized poly(n-octadecylsilsesquioxane) films via sol-gel photopolymerization.

We describe a novel solvent- and water-free sol-gel process for n-octadecyltriclorosilane (C(18)H(37)SiCl(3)) film catalyzed by photogenerated Brönsted acids. Driven by hydrophobic van der Waals interactions, a photoinduced self-assembly process occurs to afford a long-range ordered lamellar mesostructure, characterized by X-ray diffraction and transmission electron microscopy. Real-time Fourier transform IR spectroscopy was instrumental to probe the fast hydrolysis kinetics and assess the change of conformational behavior of the alkyl chains during UV irradiation.

Photodissociation rate constants of new light sensitive alkoxyamines.

The photochemical properties of two new photocleavable alkoxyamines bearing a benzophenone-derived chromophore were studied by electron spin resonance (ESR). The CO bond cleavage has been demonstrated and the photolysis rate constants (k(d) ) determined over a large range of light intensity through the monitoring of the nitroxide concentration in aerated conditions. The obtained kinetic data highlight for the first time the linear dependence of k(d) on the light intensity for alkoxyamines: this should be a driving factor for nitroxide mediated radical photopolymerization (NMP(2) ).

A novel photopolymerization initiating system based on an iridium complex photocatalyst.

The use of a photocatalyst (tris(2-phenylpyridine)iridium [Ir(ppy)(3)]) being able to generate both radicals and cations to initiate free radical polymerization and ring opening polymerization is presented. Remarkably, under soft irradiations (fluorescence bulb, sunlight), excellent cationic polymerization profiles and final conversions are obtained. The involved mechanisms are investigated by ESR experiments.

Decatungstate (W10O32(4-))/silane: a new and promising radical source under soft light irradiation.

The use of decatungstate (W10O32(4-)) in combination with silanes to generate silyl radicals under green fluorescence bulb irradiation as well as sunlight exposure is described. The mechanisms are investigated by ESR and laser flash photolysis experiments. The high potential of this reaction is evidenced here when using a decatungstate/silane/diphenyl iodonium salt combination as an initiating system for the ring opening photopolymerization of epoxides.

Dyes as Photoinitiators or Photosensitizers of Polymerization Reactions.

A short but up-to-date review on the role of dyes in the photoinitiation processes of polymerization reactions is presented. Radical and cationic reactions are largely encountered in the radiation curing and the imaging areas for use in traditional coating applications as well as in high tech sectors such as nanofabrication, computer-to-plate processing, laser direct imaging, manufacture of optical elements, etc. Recent promising developments concerned with the introduction of the silyl radical chemistry that enhances the polymerization efficiency are also discussed.

New boryl radicals derived from N-heteroaryl boranes: generation and reactivity.

Recently, boryl radicals have been the subject of revived interest. These structures were generated by hydrogen-abstraction reactions from the corresponding boranes (i.e.

Automated screening of 2D crystallization trials using transmission electron microscopy: a high-throughput tool-chain for sample preparation and microscopic analysis.

We have built and extensively tested a tool-chain to prepare and screen two-dimensional crystals of membrane proteins by transmission electron microscopy (TEM) at room temperature. This automated process is an extension of a new procedure described recently that allows membrane protein 2D crystallization in parallel (Iacovache et al., 2010).

Bis(germyl)ketones: Toward a New Class of Type I Photoinitiating Systems Sensitive Above 500 nm?

The ability of a bis(germyl)ketone Ph(3) GeCOGePh(3) to act as a photoinitiator of free radical polymerization under visible light is investigated. The results suggest that this compound could be the starting point of a new high performance class of photoinitiators. The excited state processes, as well as the generation and the reactivity of the germyl radicals, are studied by laser flash photolysis, ESR spin trapping experiments, and molecular orbital calculations; they are compared to the results obtained on a mono- (germyl)ketone CH(3) COGePh(3) .