Relationship between polypyrrole morphology and electrochemical activity towards oxygen reduction reaction

The relationship between the morphology of polypyrrole and their electrocatalytic performances towards the oxygen reduction reaction (ORR) in alkaline media is described; annealed polypyrrole with granular- and tubules-like morphology exhibited different catalytic efficiencies.     

Exponential Stability for Discrete Time Linear Equations Defined by Positive Operators

In this paper the problem of exponential stability of the zero state equilibrium of a discrete-time time-varying linear equation described by a sequence of linear positive operators acting on an ordered finite dimensional Hilbert space is investigated. The class of linear equations considered in this paper contains as particular cases linear equations described by Lyapunov operators or symmetric Stein operators as well as nonsymmetric Stein operators. Such equations occur in connection with the problem of mean square exponential stability for a class of difference stochastic equations affected by independent random perturbations and Markovian jumping as well us in connection with some iterative procedures which allow us to compute global solutions of discrete time generalized symmetric or nonsymmetric Riccati equations. The exponential stability is characterized in terms of the existence of some globally defined and bounded solutions of some suitable backward affine equations (inequalities) or forward affine equations (inequalities).     

Doi–Hopf Modules Associated to Comodule Coalgebras

To any right comodule coalgebra C over a Hopf algebra H we associate a left H-comodule algebra A. Under certain conditions, in particular in the case where H has nonzero integrals, we show that the category of right C, H-comodules is isomorphic to a certain subcategory of the category of Doi–Hopf modules associated to A. As an application, we investigate the connection between C and the smash coproduct C ? H being right semiperfect.     

Almost-periodic solutions for Riccati equations of stochastic control

We consider an average quadratic cost criteria for affine stochastic differential equations with almost-periodic coefficients. Under stabilizability and detectability conditions we show that the Riccati equation associated with the quadratic control problem has a unique almost-periodic solution. In the periodic case the corresponding result is proved in [4].     

Syntheses of 2-alkylamino- and 2-dialkylamino-4,6-diarylpyridines and 2,4,6-trisubstituted pyrimidines using solid-phase-bound chalcones

Several substituted 2- and 4-hydroxyacetophenones are linked to Wang resin via a modified Mitsunobu protocol. These resin-bound acetophenones are condensed with aromatic aldehydes, and the resulting chalcones 5 are used for the synthesis of 2-dialkylamino- (9a-d) and 2-alkylamino-4,6-diarylpyridines (11a-f), and 2-alkyl-4,6-diaryl- (14a) and 2,4,6-triarylpyrimidines (14b,c) in a manner suitable for combinatorial applications.     

The synthesis of multi-walled carbon nanotubes (MWNTs) by catalytic pyrolysis of the phenol-formaldehyde resins

A series of carbon nanomaterials, particularly multi-walled carbon nanotubes (MWNT), are obtained as products from catalytic pyrolysis of the cross-linked phenol-formaldehyde resins with different ferrocene under inert atmosphere. The morphology and structure of the samples were evaluated by TEM and XRD techniques. CNTs morphology is dependent on the iron nanoparticles and their forms (Fe, Fe₃C) resulted from ferrocene decomposition. The amount of nanotubes increases with iron content released from ferrocene catalyst during the pyrolysis process. Fe₃C nanoparticles drive the nucleation and the growth of carbon nanotubes during the pyrolysis process. Long (up to microns) well-defined MWNTs with small defects, ropes and disordered carbon are representatives in the pyrolyzed resins composition.     

Quasistatic Crack Growth in Nonlinear Elasticity

In this paper, we prove a new existence result for a variational model of crack growth in brittle materials proposed in [19]. We consider the case of n-dimensional nonlinear elasticity, for an arbitrary n1, with a quasiconvex bulk energy and with prescribed boundary deformations and applied loads, both depending on time.