Encontrados 30 documentos, a visualizar página 1 de 3

Determination of the parameters affecting electrospun chitosan fiber size distr...

The production of chitosan nanofiber mats by electrospinning presents serious difficulties due to the lack of suitable solvents and the strong influence of processing parameters on the fiber properties. Two are the main problems to be solved: to control the properties of the solution in order to obtain large area uniform fiber mats by having a stable flow rate and to avoid sparks during the process, dam...

Synthesis and evaluation of thermal, electrochemical and nonlinear optical prop...

Materials exhibiting large optical nonlinearities continue to be the subject of intense studies because of their potential applications in modern communication technologies involving optical data processing, transmission, or storage, where they are gradually replacing classical electronic devices.[1] Earlier we reported on the synthesis and evaluation of thermal, redox and NLO properties of donor-acceptor subst...

Electrocatalytic oxidation of oxalic and oxamic acids in aqueous media at carbo...

The electrochemical oxidation of oxalic and oxamic acids on multiwalled carbon nanotubes (CNT) and on monometallic (Pd and Pt) and bimetallic (Pd-Cu, Pt-Cu) catalysts supported on multiwalled carbon nanotubes was investigated using cyclic voltammetry. The electrodes were prepared by dispersion of the catalytic material on Toray carbon (CT) using a Nafion/water solution. The kinetic parameters of the reactions w...

Highly efficient and thermally stable NLO organic materials based on pyrrole an...

A series of novel donor-acceptor chromophores designed to have good second order nonlinear optical responses has been synthesized and characterized. This series of compounds was designed to explore the consequence of using different electron accepting moieties which were linked through an arylthiophene bridge to a pyrrole heterocycle that plays the role of an auxiliary donor group. These new push-pull chromopho...

Synthesis and evaluation of NLO properties of π-conjugated donor‐acceptor syste...

Two series of novel push-pull heterocyclic azo dyes have been synthesized and characterized. The two series of compounds were based on different combinations of π-conjugated bridges (bithiophene and thienylpyrrole) which also act simultaneously as donor groups, together with diazo(benzo)thiazolyl as acceptor moieties. Their thermal stability and electrochemical behavior were characterized, while hyper-Rayleigh ...

Push-pull bithiophene azo-chromophores bearing thiazole and benzothiazole accep...

Three series of bithiophene azo dyes functionalized with thiazol-2-yl or benzothiazol-2-yl-diazene acceptor moieties were synthesized through azo coupling reaction using 2,2´-bithiophene, 5-alkoxy-2,2´-bithiophenes, 5-N,N-dialkylamino-2,2´-bithiophenes and thiazolyl and benzothiazolyl diazonium salts as coupling components. The 5-alkoxy-2,2´-bithiophene precursors yielded the 5-thiazolylazo-5´-alkoxy-2,2´-bithi...

Design, synthesis and characterization of the electrochemical, nonlinear optica...

Two series of related donor-acceptor conjugated heterocyclic azo dyes based on the thienylpyrrole system, functionalized with benzothiazol-2-yl (5-6) or benzothiazol-6-yl acceptor groups (7) through an N=N bridge, have been synthesized by azo coupling using 1-alkyl(aryl)thienylpyrroles (1) and benzothiazolyl diazonium salts (2-4) as coupling components. Their optical (linear and first hyperpolarizability), elec...

Synthesis and characterization of novel diazenes bearing pyrrole, thiophene and...

Two series of novel thermally stable second-order nonlinear optical (NLO) and photochromic chromophores have been designed and synthesized. The two series of compounds were based on different combinations of donor groups (pyrrole or thienylpyrrole) which act simultaneously as Π-conjugated bridges, together with diazoaryl or diazothiazolyl as acceptor moieties. Their photochromic and electrochemical behavior wer...

Comparative study of the tarnishing resistance of several coloured base gold al...

The stability of coloured gold alloys may be dependent on the environment that involves them. This paper is concerned with the effect of an artificial sweat solution in the stability of several gold base alloys with different colours. The changes in the samples physical properties, colour, brightness, and reflectance were measured for several periods of immersion. Two types of alloys (purple and blue coloured a...

Synthesis and evaluation of NLO properties of π-conjugated donor‐acceptor syste...