Development and Validation of LC-ESI-MS/MS Method for the Determination of Alfuzosin in Human Plasma

Journal of Analytical Chemistry - A new liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method has been developed and validated for alfuzosin quantification in...     

Capillary gas chromatography of amines with ammonia as carrier gas

The use of ammonia as a carrier gas for the chromatography of aliphatic and aromatic amines has been investigated. As compared to nitrogen, ammonia gave drastically improved peak symmetry and lower capacity factors (k′) for primary and secondary amines on polar (Polyethylene glycol) and medium Polar (methylphenylcyanopropylsilicone) stationary Phases. The effect of ammonia was more Pronounced at low column temperatures. Considerably better detection limits of primary and secondary amines were obtained with ammonia as carrier gas than with nitrogen. No detrimental effects of using ammonia were observed on the gas chromatograph or on the columns over a period of about one year.     

Colloidal stability of aqueous nanofibrillated cellulose dispersions

Cellulose nanofibrils constitute an attractive raw material for carbon-neutral, biodegradable, nanostructured materials. Aqueous suspensions of these nanofibrils are stabilized by electrostatic repulsion arising from deprotonated carboxyl groups at the fibril surface. In the present work, a new model is developed for predicting colloidal stability by considering deprotonation and electrostatic screening. This model predicts the fibril-fibril interaction potential at a given pH in a given ionic strength environment. Experiments support the model predictions that aggregation is induced by decreasing the pH, thus reducing the surface charge, or by increasing the salt concentration. It is shown that the primary mechanism for aggregation upon the addition of salt is the surface charge reduction through specific interactions of counterions with the deprotonated carboxyl groups, and the screening effect of the salt is of secondary importance.     

Mössbauer analysis of Fe−N austenites

Analysis of transmission Mössbauer spectra for high nitrogen Fe?N austenites is done in terms of five iron environments dealing with first and second nearest neighbour shells. The similar analysis for Fe?C austenites which displays only three iron environments led to the conclusion that carbon atoms are ordered whereas nitrogen atoms are more randomly distributed.     

Some convergence results for asynchronous algorithms

Resumé Nous présentons dans cet article des résultats de convergence des algorithmes asynchrones basés essentiellement sur la notion classique de contraction.Nous généralisons, en particulier, tous les résultats de convergence de ces algorithmes qui font l'hypothèse de contraction en norme vectorielle qui récemment a été très souvant utilisée.Par ailleurs, l'hypothèse de contraction en norme vectorielle peut se trouver difficile, voire impossible à vérifier pour certains problèmes qui peuvent être cependant abordés dans le cadre de la contraction classique que nous adoptons.

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Some convergence results for asynchronous algorithms

Summary In this paper we present convergence results for the asynchronous algorithms based essentially on the notion of classical contraction.We generalize, in particular, all convergence results for those algorithms which are based on the vectorial norm hypothesis, in wide spread use recently.Certain problems, for which the vectorial norm hypothesis can be difficult or even impossible to verify, can nontheless be tackled within the scope of the classical contraction that we adopte.

     

Finite Difference Approximations for Stochastic Control Systems with Delay

Abstract

This article considers the computation issues of the infinite dimensional HJB equation arising from the finite horizon optimal control problem of a general system of stochastic functional differential equations with a bounded memory treated in [2 Chang , M.H. , Pang , T. , and Pemy , M. accepted. Optimal control of functional stochastic differential equations with a bounded memory. Stochastics 80 ( 1 ): 69 – 96 . [Google Scholar]]. The finite difference scheme, using the result in [1 Barles , G. , and Souganidis , P.E. 1991 . Convergence of approximative schemes for fully nonlinear second order equations . J. Asymptotic Analysis 4 : 557 – 579 . [Google Scholar]], is obtained to approximate the viscosity solution of the infinite dimensional HJB equation. The convergence of the scheme is proved using the Banach fixed point theorem. The computational algorithm also is provided based on the scheme obtained.     

Liouville Theorems for a General Class of Nonlocal Operators

In this paper, we study the equation \(\mathcal {L} u=0\) in \(\mathbb {R}^{N}\), where \(\mathcal {L}\) belongs to a general class of nonlocal linear operators which may be anisotropic and nonsymmetric. We classify distributional solutions of this equation, thereby extending and generalizing recent Liouville type theorems in the case where \(\mathcal {L}= (-{\Delta })^{s}\), s ∈ (0, 1) is the classical fractional Laplacian.