Towards a new definition of EPOC parameters for anionic electrochemical catalysts: case of propene combustion

The electrochemical promotion of catalysis (EPOC) of propene combustion was investigated using Pt sputtered thin film on an O²⁻ conductor, 8 mol% Y₂O₃-stabilized-ZrO₂ (YSZ). In order to separate the influence of the thermal migration of the O²⁻ oxide ions from the electrolyte to the catalyst surface and the impact of an electrical polarization on the catalytic activity, several light-off experiments (cool down and heat up procedures) were successively performed under different polarizations, i.e. OCV, +2 and −2 V. These experiments have clearly shown that the presence of O²⁻ (thermally or electrochemically induced) inhibits the catalytic activity of the platinum for the propene deep oxidation. These results demonstrate the importance to define a normalized rate enhancement ratio, ρ _n , from a reference value of the catalytic rate corresponding to a Pt surface state free of O²⁻ ions.     

Catalysis, the turntable for a clean future

Upgrading the bottom of the barrel for clean fuel production, developing new engines with optimized catalytic posttreatments, implementing clean catalytic combustion technologies, improving the overall CO₂ balance via catalytic processes and, lastly, developing new water purification techniques represent major upheavals in catalysis linked to refining and environmental protection. This paper, thus, will focus on the determining contribution of catalysis to the most recent achievements in these domains. A technico-economic approach will follow, underlining their main incentives and drawbacks within the framework of future environmental constraints.     

As Hangs the Flexible Line: Equilibrium of Masonry Arches

In 1675, English scientist Robert Hooke discovered “the true... ...manner of arches for building,” which he summarized with a single phrase: “As hangs the flexible line, so but inverted will stand the rigid arch.” In the centuries that followed, Hooke’s simple idea has been used to understand and design numerous important works. Recent research at MIT on the interactive analysis of structural forces provides new graphical tools for the understanding of arch behavior, which are useful for relating the forces and geometry of masonry structures. The key mathematical principle is the use of graphical analysis to determine possible equilibrium states.     

Partial or total silylation of dextran with hexamethyldisilazane

The silylation reaction of dextran with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) in DMSO was studied as the first step of the synthesis of new amphiphilic polyester-grafted dextrans. According to the experimental conditions, i.e. dextran molar weight, medium temperature and reaction time, HMDS/OH ratio, addition of a catalyst and co-solvent, partially or totally silylated dextrans were recovered. The highest silylation yields were obtained with the lowest molecular weight dextrans. The increase in temperature medium and/or reaction time, the presence of catalyst or co-solvent favored the protection yield. Whatever the dextran used, complete silylation of the polysaccharide chain could be achieved by adequate selection of the experimental conditions. The thermal properties of resulting silylated polysaccharides were investigated by temperature modulated DSC. It was observed that T_g values of partially silylated dextran were maintained between 120 and 140 °C, independently of the dextran molecular weight. Interestingly, DMSO proved to behave as an efficient plasticizer of (partially) silylated dextrans. The partially silylated dextrans were efficiently used as multifunctional macroinitiators for the controlled ring-opening polymerization (ROP) of lactone. The ROP was then promoted from the remaining hydroxyl groups in the presence of tin or aluminium activator. After polymerization and ultimate deprotection of the silylated dextran backbone, amphiphilic polyester-grafted dextrans were readily recovered.     

Selectors Make Set-Based Analysis Too Hard

A set-based program analysis establishes constraints between sets of abstract values for all expressions in a program. Solving the system of constraints produces a conservative approximation to the program's runtime flow of values. Some practical set-based analyses use explicit selectors to extract the relevant values from an approximation set. For example, if the analysis needs to determine the possible return values of a procedure, it uses the appropriate selector to extract the relevant component from the abstract representation of the procedure. In this paper, we show that this selector-based approach complicates the constraint solving phase of the analysis too much and thus fails to scale up to realistic programming languages. We demonstrate this claim with a full-fledged value flow analysis for case-lambda, a multi-branched version of lambda. We show how both the theoretical underpinnings and the practical implementation become too complex. In response, we present a variant of set-based closure analysis that computes equivalent results in a much more efficient manner.     

Radiosity with Well Distributed Ray Sets

In this paper we present a new radiosity algorithm, based on the notion of a well distributed ray set (WDRS). A WDRS is a set of rays, connecting mutually visible points and patches, that forms an approximate representation of the radiosity operator and the radiosity distribution. We propose an algorithm that constructs an optimal WDRS for a given accuracy and mesh. The construction is based on discrete importance sampling as in previously proposed stochastic radiosity algorithms, and on quasi Monte Carlo sampling. Quasi Monte Carlo sampling leads to faster convergence rates and the fact that the sampling is deterministic makes it possible to represent the well distributed ray set very efficiently in computer memory. Like previously proposed stochastic radiosity algorithms, the new algorithm is well suited for computing the radiance distribution in very complex diffuse scenes, when it is not feasible to explicitly compute and store form factors as in classical radiosity algorithms. Experiments show that the new algorithm is often more efficient than previously proposed Monte Carlo radiosity algorithms by half an order of magnitude and more.     

Review of Cliniques de thérapie comportementale.

Reviews the book, Cliniques de thérapie comportementale/Clinical behavioral therapy edited by O. Fontaine, J. Cottraux, and R. Ladouceur (1985). This book is a work which seeks to fill a vacuum while proposing to illustrate in a concrete manner how the behaviorist acts in his daily practice. It comprises 25 chapters which frequently illustrate this pragmatic prospect within the framework for pathologies used in behavioral private clinics, from infantile autism to dementia in old age, while passing by depression, alcoholism, chronic pain, etc. This book is the result of the collaboration of about thirty specialists of reputation: Beligian, Canadian, French and Swiss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)