The nanocellulose biorefinery: woody versus herbaceous agricultural wastes for NCC production

In the present work two agricultural residues (apple tree pruning and pea stalks) were studied as sources of nanocellulose. Different pretreatments that might be used in a biorefinery were applied to these lignocellulosic materials: autohydrolysis, organosolv (acetosolv) and alkaline pretreatments. After conventional bleaching, the resulting cellulosic fractions were submitted to a classical acid hydrolysis for nanocellulose crystal (NCC) production. The results showed that after applying different pretreatments, the resulting NCCs had different lengths (from 300 to 676 nm), surface charges (from 17 to 98 μmol acid groups/g NCC), purity (from 0.3 to 11.6% w/w of inorganics), crystallinity indexes and even allomorphism. These results highlighted the importance that cellulose source and particularly the applied pretreatments have on nanocrystal properties and suggest how biorefining pathways for lignocellulosic materials could customize such NCC features as surface reactivity or suitability for chemical modification.     

Action des Enamines Sur Les Allenes Phosphores: Synthese de 1-( N -morpholino ou N -pyrrolidino)-phosphomethylenbicycloalcanes

In this work we studied the reaction of enamines 1 with allenylphosphonates and -phosphine oxides 2 which lead to the 1-( N -morpholino or N -pyrrolidino)-phosphomethylen-bicyclolkanes 3 . The structure of compounds 3 was confirmed by NMR-( 1 H, 13 C, and 31 P) and IR spectroscopy.     

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.     

A post-optimization method for the routing and wavelength assignment problem applied to scheduled lightpath demands

We consider here a NP-hard problem related to the Routing and Wavelength Assignment (RWA) problem in optical networks, dealing with Scheduled Lightpath Demands (SLDs). An SLD is a connection demand between two nodes of the network, during a certain time. Given a set of SLDs, we want to assign a lightpath, i.e. a routing path and a wavelength, to each SLD, so that the total number of required wavelengths is minimized. The constraints are the following: a same wavelength must be assigned all along the edges of the routing path of any SLD; at any time, a given wavelength on a given edge of the network cannot be used to satisfy more than one SLD. To solve this problem, we design a post-optimization method improving the solutions provided by a heuristic. The experimental results show that this post-optimization method is quite efficient to reduce the number of necessary wavelengths.     

Numerical simulation of the wave equation with discontinuous coefficients by nonconforming finite elements

The goal of this article is to apply the mortar finite element method to the numerical simulation of (electromagnetic and/or acoustic) waves propagating in an inhomogeneous support. This approach allows us to use meshes well adapted to the local physical parameters of the media without any conformity constraints. A complete mathematical study is supplied providing the expected optimal convergence rate. Numerical performances of such a technique, as well as its advantages, are also discussed. © 1999 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 15: 637–656, 1999