Modeling of fixed-bed adsorption of Cs+ and Sr2+ onto clay–iron oxide composite using artificial neural network and constant–pattern wave approach

A low-cost, non-toxic and effective adsorbent constituted by a montmorillonite coated by iron oxides (montmorillonite–iron oxide composite) was prepared to assess its effectiveness in the removal of Cs⁺ and Sr²⁺ from aqueous solution. Dynamic adsorption experiments were carried out at room temperature under the effect of various operating parameters such as bed depth Z (5–15 cm), initial cation concentration C ₀ (2–50 mg L^?1) and volumetric flow rate Q (0.5–8 mL min^?1). Column performance has been modeled with constant-pattern wave approach combined to the Freundlich isotherm model and artificial neural network (ANN) models. The time, initial cation concentration, bed depth and volumetric flow rate were chosen as the input variables whereas, the outlet concentration C _t was considered as the output variable. The developed network was found to be useful in predicting the breakthrough curves. Experimental data for the used system were well fitted with ANN than the combined constant–pattern wave approach.     

Sufficiency and Duality in Multiobjective Variational Problems with Generalized Type I Functions

Recently Hachimi and Aghezzaf introduced the notion of (F,α,ρ,d)-type I functions, a new class of functions that unifies several concepts of generalized type I functions. Here, we extend the concepts of (F,α,ρ,d)-type I and generalized (F,α,ρ, d)-type I functions to the continuous case and we use these concepts to establish various sufficient optimality conditions and mixed duality results for multiobjective variational problems. Our results apparently generalize a fairly large number of sufficient optimality conditions and duality results previously obtained for multiobjective variational problems.     

Convergence faible vers une classe de processus Gaussiens en norme de Besov anisotropique

We prove an approximation result of Donsker's type in anisotropic Besov spaces for a class of two parameter Gaussian processes. The particular case of the fractional Brownian sheet was considered in [X. Bardina, C. Florit, Approximation in law to the d-parameter fractional Brownian sheet based on the functional invariance principle, Preprint, 2003] for the Banach space of continuous functions.     

1,2,4‐Triazolo­[2,3‐h]‐7,9‐thi­aza‐11‐crown‐4

The title compound, 4,7‐dioxa‐10‐thia‐1,12,13‐tri­aza­bi­cyclo­[9.3.0]­tetra­deca‐11,13‐diene, C₈H₁₃N₃O₂S, contains an 11‐membered ring, which appears in a chair conformation and has approximate mirror symmetry. It may be used for the complexation of metal atoms.     

Necessary conditions for optimality in relaxed stochastic control problems

In this paper, we are concerned with optimal control problems where the system is driven by a stochastic differential equation of the Ito type. We study the relaxed model for which an optimal solution exists. This is an extension of the initial control problem, where admissible controls are measure valued processes. Using Ekeland's variational principle and some stability properties of the corresponding state equation and adjoint processes, we establish necessary conditions for optimality satisfied by an optimal relaxed control. This is the first version of the stochastic maximum principle that covers relaxed controls.     

Luminescence decay and the absorption cross section of individual single-walled carbon nanotubes

The absorption cross section of highly luminescent individual single-walled carbon nanotubes is determined using time-resolved and cw luminescence spectroscopy. A mean value of approximately 1 x 10(-17) cm2 per carbon atom is obtained for (6,5) tubes excited at their second optical transition, and corroborated by single tube photothermal absorption measurements. Biexponential luminescence decays are systematically observed, with short and long lifetimes around 45 and 250 ps. This behavior is attributed to the band edge exciton fine structure with a dark level lying a few meV below a bright one.     

Synthesis and X‐ray structures of unexpected 2‐O‐(5‐deoxy‐1,2‐O‐isopropylidene‐α‐D‐glucofuranos‐5‐yloxy)quinoxalines

Reaction of 3‐methyl‐2(1H)‐quinoxalinone ( 4) and 2(1H)‐quinoxalinone ( 5) with 5,6‐anhydro‐1,2‐O‐isopropylidene‐ α‐D ‐glucofuranose 6 gives the unexpected O‐glucoquinoxalines derivatives by the intermediary novel intramolecular rearrangement of 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D ‐glucofuranose to the corresponding 3,6‐anhydro form. The obtained O‐glucoquinoxalines 7,8 were identified by NMR spectroscopy. The X‐ray crystal structures have been determined at room temperature. Moreover, a solid–solid phase transition has been detected at 198.9 K for O‐glucoquinoxalines 7 and the structure of the low‐temperature phase has been solved at 188 K. Copyright © 2009 John Wiley & Sons, Ltd.     

On the well-posedness of coupled forward–backward stochastic differential equations driven by Teugels martingales

We deal with a class of fully coupled forward–backward stochastic differential equations (FBSDEs), driven by Teugels martingales associated with a general Lévy process. Under some assumptions on the derivatives of the coefficients, we prove the existence and uniqueness of a global solution on an arbitrarily large time interval. Moreover, we establish stability and comparison theorems for the solutions of such equations. Note that the present work extends known results proved for FBSDEs driven by a Brownian motion, by using martingale techniques related to jump processes, to overcome the lack of continuity.