Courants positifs à supports dans une bande

Let T be a positive current of bidimension $(p,p)$ on ${\mathbb{C}}^n$ with support in a strip. If T is closed, S. Giret has proved that T admits a well defined lifting through a blow up with smooth center. The class of positive closed currents with bidimension $(1,1)$ in the unit bidisc ${\Delta }^2$ and with support in a strip, plays a central role in the study of the dynamics of some holomorphic maps. In this note, we prove some estimates of the trace measure of T when $d{d}^{c}T?0$, we prove in particular that if T is closed, then it is algebraic. We then prove two support theorems; the first one in the case where the degree of T is finite and the second in the case where T is positive closed and with tubular support. The latter result generalizes the case $p=n?1$ proved by M. Blel, S.K. Mimouni and G. Raby, which is also a generalization of the case when T is the current of integration on an hypersurface as proved by M.T. Togni. To cite this article: F. Elkhadhra, S.K. Mimouni, C. R. Acad. Sci. Paris, Ser. I 341 (2005).     

Modelling the trade‐offs between farm income and the reduction of erosion and nitrate pollution

Water is a very limited resource in Tunisia, both in quantity and in quality. Problems of quality are related to urban, industrial and agricultural activity. Erosion is causing dams to silt up and is leading to phosphorus accumulation in water. The use of agrochemicals, primarily nitrogen and phosphorus, is causing problems of eutrophication. This paper presents the results of a study of sediment and nitrate pollution. The methodology used is based on the EPIC simulation model and a multiobjective programming model (MOPM). The data generated by EPIC are input for the MOPM together with the economic variables. These tools are applied to a 486 ha farm located in northern Tunisia which includes an irrigated area of 300 ha. The study considers three objectives: maximization of gross margin, minimization of erosion, and minimization of nitrate losses. The noninferior set estimation method is implemented to generate the tradeoff curves between the objectives. Results show that nitrate losses are important for both rainfed and irrigated land. The same conclusion is valid for erosion. It is shown that the farmer can reduce the environmental burden without decreasing gross margin, since he is operating below the efficiency curve.     

Cytotoxic effect and electrophysiological study on human MRC-5 fibroblasts of R-irniine, a natural alkylpyrrolidine alkaloid

R-irniine is a natural 2-alkylpyrrolidine alkaloid extracted from Arisarum vulgare Targ., a species belonging to the Araceae family known in Morocco for its toxicity. Cytotoxic and electrophysiological studies of this compound on human MRC-5 fibroblasts were carried out. Cytotoxic potential of R-irniine was detected on MRC-5 fibroblasts at 40 microg/mL. We carried out the electrophysiological study of this compound on MRC-5 cells by using the technique of patch-clamp in "Whole cell" configuration. R-irniine showed no effect on the outward potassium current of the MRC-5 fibroblasts.     

A simple and tailor‐made fabrication of porous silicon carbide from functionalized kraft pulp paper

Porous silicon carbide (SiC) materials were fabricated using the polymer‐derived ceramics method with kraft pulp papers (KPP) and a commercial polycarbosilane, the allylhydridopolycarbosilane (AHPCS), as starting materials. For this, KPP, propargylated KPP, or phosphorylated KPP were used to be impregnated by the AHPCS, with or without Karstedt catalyst. The pyrolysed materials were characterized at different stages, by using thermogravimetric analysis (TGA) coupled with mass spectrometry, X‐ray diffraction (XRD), and scanning electron microscopy (SEM). Depending on the nature of the initial template, various architectured SiC ceramics were successfully obtained with adjustable porosities. The key role of the previous functionalization of the papers was highlighted in terms of interactions at the interface between the polymer and the lignocellulosic handsheets. It led to either replica or sacrificial template methods. Thus, it was possible to tune the open porosity of the porous carbon and β‐SiC materials between 14.8% and 92.9%, with ceramic yields varying from 12% to 71%.     

1-Dodecanethiol self-assembled monolayers on cobalt

Cobalt and its alloys are used in a broad range of application fields. However, the use of this metal is especially limited by its strongly oxidizable nature. The use of alkanethiol self-assembled monolayers (SAMs) is a very efficient way to protect against such oxidation and/or to inhibit corrosion. This surface modification method has been particularly applied to oxidizable metals such as copper or nickel, yet the modification of cobalt surfaces by alkanethiol SAMs received limited attention up to now. In this work, we study the influence of parameters by which to control the self-assembly process of 1-dodecanethiol monolayers on cobalt: nature of the surface pretreatment, solvent, immersion time, and concentration. Each of these parameters has been optimized to obtain a densely packed and stable monolayer able to efficiently prevent the reoxidation of the modified cobalt substrates. The obtained monolayers were characterized by X-ray photoelectron spectroscopy (XPS), polarization modulation infrared reflection-absorption spectroscopy, and contact angle measurements. The stability of the optimized 1-dodecanethiol monolayer upon air exposure for 28 days has been confirmed by XPS.     

Exergy-Based Multi-Objective Optimization of an Organic Rankine Cycle with a Zeotropic Mixture

In this paper, the performance of an organic Rankine cycle with a zeotropic mixture as a working fluid was evaluated using exergy-based methods: exergy, exergoeconomic, and exergoenvironmental analyses. The effect of system operation parameters and mixtures on the organic Rankine cycle’s performance was evaluated as well. The considered performances were the following: exergy efficiency, specific cost, and specific environmental effect of the net power generation. A multi-objective optimization approach was applied for parametric optimization. The approach was based on the particle swarm algorithm to find a set of Pareto optimal solutions. One final optimal solution was selected using a decision-making method. The optimization results indicated that the zeotropic mixture of cyclohexane/toluene had a higher thermodynamic and economic performance, while the benzene/toluene zeotropic mixture had the highest environmental performance. Finally, a comparative analysis of zeotropic mixtures and pure fluids was conducted. The organic Rankine cycle with the mixtures as working fluids showed significant improvement in energetic, economic, and environmental performances.     

Polymer‐Derived Silicoboron Carbonitride Foams for CO2 Capture: From Design to Application as Scaffolds for the in Situ Growth of Metal–Organic Frameworks

A template‐assisted polymer‐derived ceramic route is investigated for preparing a series of silicoboron carbonitride (Si/B/C/N) foams with a hierarchical pore size distribution and tailorable interconnected porosity. A boron‐modified polycarbosilazane was selected to impregnate monolithic silica and carbonaceous templates and form after pyrolysis and template removal Si/B/C/N foams. By changing the hard template nature and controlling the quantity of polymer to be impregnated, controlled micropore/macropore distributions with mesoscopic cell windows are generated. Specific surface areas from 29 to 239 m² g^?1 and porosities from 51 to 77 % are achieved. These foams combine a low density with a thermal insulation and a relatively good thermostructural stability. Their particular structure allowed the in situ growth of metal–organic frameworks (MOFs) directly within the open‐cell structure. MOFs offered a microporosity feature to the resulting Si/B/C/N@MOF composite foams that allowed increasing the specific surface area to provide CO₂ uptake of 2.2 %.     

What if the Higgs mass violates unitarity?

A model for a super heavy Higgs based on a non-perturbative method is discussed. It is shown that the dispersion relations approach gives new insights for the strong interactions effects and a way to derive a new unitarity bound.     

Electrocatalytic oxidation of <Emphasis Type="SmallCaps">l</Emphasis>-tyrosine at carboxylic acid functionalized multi-walled carbon nanotubes modified carbon paste electrode

The electrocatalytic oxidation of l-tyrosine (Tyr) was investigated on a carboxylic acid functionalised multi-walled carbon nanotubes modified carbon paste electrode using cyclic voltammetry and amperometry. The surface morphology of the electrodes was studied using field emission (FE)-SEM images, and the interface properties of bare and modified electrodes were investigated by electrochemical impedance spectroscopy (EIS). The influence of the amount of modifier loading and the variation of the pH of the solution on the electrochemical parameters have been investigated. Cyclic voltammetry was carried out to study the electrochemical oxidation mechanism of Tyr, which showed an irreversible oxidation process at a potential of 637.0 mV at modified electrode. The anodic peak current linearly increased with the scan rate, suggesting that the oxidation of Tyr at modified electrode is an adsorption-controlled process. A good linear relationship between the oxidation peak current and the Tyr concentration in the range of 0.8–100.0 μM was obtained in a phosphate buffer solution at pH 7.0 with a detection limit of 14.0?±?1.36 nM (S/N?=?3). The practical utility of the sensor was demonstrated by determining Tyr in spiked cow’s milk and human blood serum. The modified electrode showed excellent reproducibility, long-term stability and antifouling effects.