Fluorescent Brighteners as Visible LED‐Light Sensitive Photoinitiators for Free Radical Photopolymerizations

The photochemical and electrochemical investigations of commercially available, safe, and cheap fluorescent brighteners, namely, triazinylstilbene (commercial name: fluorescent brightener 28) and 2,5‐bis(5‐tert‐butyl‐benzoxazol‐2‐yl)thiophene, as well as their original use as photoinitiators of polymerization upon light emitting diode (LED) irradiation are reported. Remarkably, their excellent near‐UV–visible absorption properties combined with outstanding fluorescent properties allow them to act as high‐performance photoinitiators when used in combination with diaryliodonium salt. These two‐component photoinitiating systems can be employed for free radical polymerizations of acrylate. In addition, this brightener‐initiated photopolymerization is able to overcome oxygen inhibition even upon irradiation with low LED light intensity. The underlying photochemical mechanisms are investigated by electron‐spin resonance‐spin trapping, fluorescence, cyclic voltammetry, and steady‐state photolysis techniques.

     

Hadamard's variational formula for a mixed problem and an application to a problem related to a signorini-like variational inequality

We give a variational formula for the solution of a Mixed Boundary Value Problem when the geometrical domain is perturbed (Hadamard's Variational Formula) ; we show that this formula contains singularities ; the result is used to construct a new approach to the optimal control problem for a problem related to a Signorini-like Elliptic Variational Inequality.     

Incomplete financial markets model with nominal assets: Variational approach

We deal with the analysis of the general equilibrium model with incomplete financial markets and nominal assets. We assume that there are 2 periods of time, say today and tomorrow. We define a consumption, portfolio holding, commodity and asset price vector as an equilibrium vector associated with a given economy if at those prices and economies households maximize utility under a budget constraints and markets clear. While the path breaking proofs of existence by Cass [6] and Werner [25] use a fixed point argument, we provide an independent existence proof in terms of variational inequalities (about the variational approach for the analysis of general equilibrium models see for example [9] and [10]). The analysis presented in this paper indicates that the variational inequality approach promises to be applicable in many specifications of the incomplete market model.     

Structural analysis of an unusual bioactive N-acylated lipo-oligosaccharide LOS-IV in Mycobacterium marinum

Although lipo-oligosaccharides (LOSs) are recognized as major parietal components in many mycobacterial species, their involvement in the host-pathogen interactions have been scarcely documented. In particular, the biological implications arising from the high degree of structural species-specificity of these glycolipids remain largely unknown. Growing recognition of the Mycobacterium marinum-Danio rerio as a specific host-pathogen model devoted to the study of the physiopathology of mycobacterial infections prompted us to elucidate the structure-to-function relationships of the elusive end-product, LOS-IV, of the LOS biosynthetic pathway in M. marinum. Combination of physicochemical and molecular modeling methods established that LOS-IV resulted from the differential transfer on the caryophyllose-containing LOS-III of a family of very unusual N-acylated monosaccharides, naturally present as different diastereoisomers. In agreement with the partial loss of pathogenecity previously reported in a LOS-IV-deficient M. marinum mutant, we demonstrated that this terminal monosaccharide conferred to LOS-IV important biological functions, including macrophage activating properties.     

Tandem facial amphiphiles for membrane protein stabilization

We describe a new type of synthetic amphiphile that is intended to support biochemical characterization of intrinsic membrane proteins. Members of this new family displayed favorable behavior with four of five membrane proteins tested, and these amphiphiles formed relatively small micelles.     

Short, asymmetric synthesis of epi-morphine ACNO analogues

A concise and efficient asymmetric synthesis of ACNO analogues of morphine is reported.     

An existence result of a quasi-variational inequality associated to an equilibrium problem

In this paper we consider a Walrasian pure exchange economy with utility function which is a particular case of a general economic equilibrium problem, without production. We assume that each agent is endowed with at least of a commodity, his preferences are expressed by an utility function and it prevails a competitive behaviour: each agent regards the prices payed and received as independent of his own choices. The Walrasian equilibrium can be characterized as a solution to a quasi-variational inequality. By using this variational approach, our goal is to prove an existence result of equilibrium solutions.     

Simultaneous ion transfer across the microhole ITIES: an example of ternary electrodiffusion

Ternary electrodiffusion at the immiscible liquid liquid interface (ITIES) is considered in the case where a univalent cation is transferring from the water to the organic phase through a microhole, and simultaneously a univalent anion is transferring in the opposite direction. The process is assumed to take place at steady-state. If the separation between the formal transfer potentials of these ions is large enough, a limiting current corresponding to the electrodiffusion of the ion with the lower formal transfer potential is observed. Thereafter, the current begins to rise again as a linear function of the cell potential because the Galvani potential across the interface has reached its limiting value and the potential is expended in the form of ohmic loss in the diffusion boundary layers. The Galvani potential across the interface cannot overcome the average value of the formal transfer potentials due to the electroneutrality condition. The present case is analogous to a redox reaction at the ultramicroelectrode with sign reversal (K.B. Oldham, J. Electroanal. Chem. 337 (1992) 91) but no suitable experimental system has yet been found with which to test this prediction. Experiments without supporting electrolytes seem to have only little value in quantitative analysis of ion transfer.     

Synthesis and characterization of a hyperbranched hydrogen bond acidic carbosilane sorbent polymer

Sorbent polymers can be designed to target molecular interactions with a variety of hazardous chemicals including explosives, chemical agents, narcotics, and toxic industrial chemicals. Applications of functionalized sorbent polymers include preconcentrator devices, SPME fibers, membrane introduction systems, chromatographic stationary phases and coatings for chemical sensors. One common feature of a wide range of hazardous chemicals is their hydrogen bond (h‐b) basicity. In this work, we report on the synthesis and characterization of a h‐b acidic hyperbranched carbosilane fluoroalcohol based sorbent polymer (poly(methyldi(1,1,1‐trifluoro‐2‐trifluoromethyl‐2‐hydroxypent‐4‐enyl)silane; HCSFA2), which is suitable for sorbing these hazardous h‐b basic analytes. Multiple batches of HCSFA2 were characterized with routine composition, spectroscopic, thermal analysis, and inverse gas chromatography (iGC) to evaluate polymer physicochemical properties. In comparison with previously developed h‐b acidic polymers (e.g., FPOL and SXFA), HCSFA2 exhibits a sorption improvement of 10–15 fold for h‐b basic analytes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3000–3009, 2010