Studies of the voltammetric behavior and determination of diazo reactive dyes at mercury electrode

The electrochemical reduction of two reactive dyes: Procion Red HE-3B 9 (RR120) and Procion Green HE-4BD (RG19) was investigated using cyclic voltammetry, differential pulse and DC, polarography, chronoamperometry and controlled potential electrolysis at mercury electrodes. The bis-azo groups of the RR120 dye are reduced together in one single step of four electrons, the bis-azo groups of the RG19 dye are reduced in two steps owing to the difference in the electron densities promoted by the different substituents in the benzene rings adjacent to the azo groups. The bis-monochlorotriazine reactive groups in both dyes are reduced only in acidic medium in their protonated form, leading to the reduction of the triazine groups. The reduction mechanism of both reactive dyes is discussed. Both dyes can be quantified in aqueous medium by differential pulse polarography in the concentration range of 1 x 10(-7) mol L-1 to 1 x 10(-5) mol L-1 by monitoring the reduction of the chromophore group or the reactive group.

La participación popular y los principios de desarrollo de la comunidad en el desarrollo económico y social = Popular participation and principles of community development in relation to the acceleration of economic and social development

Incluye Bibliografía

Rationalizing social policy: evaluation and viability

Includes bibliography

The social sciences without planning or revolution?

Includes bibliography

Lista de las principales resoluciones relacionadas con la Estrategia Internacional del Desarrollo y el Programa de Acción Regional aprobadas por la Asamblea General y el Consejo Económico y Social de las NU, la CEPAL y el CDCC = List of main resolutions adopted with regard to the International Development Strategy and the Regional Programme of Action by the General Assembly, United Nations Economic and Social Council, ECLA and CDCC

Contiene el título de las resoluciones y su número.

Antecedentes, organización y programas del Centro Latinoamericano de Documentación Económica y Social = Background, organization and programmes of the Latin American Centre for Economic and Social Documentation

Incluye Bibliografía

Reestructuración y revitalización de las Naciones Unidas en las esferas económica y social: papel y funciones de la CEPAL = Restructuring and revitalization of the United Nations in the economic and social fields: role and functions of ECLAC = Restructuration et revitalisation de l'Organisation des Nations Unies dans les domaines économique et social: rôle et fonctions de la CEPALC

Incluye Bibliografía

Environmental ageing studies of chemically modified micro and nanofibril phenol formaldehyde composites

Cellulose micro and nano fibrils were extracted from banana macro fibres and chemically modified using sodium hydroxide, formic acid, 3-methacryloxy propyltrimethoxy silane. These untreated and chemically treated fibrils were incorporated into PF resin and the specimens were prepared. The composites were subjected to long-term water ageing, thermal ageing soil burial and outdoor weathering. The mechanical properties are reduced under all ageing conditions. The present study investigates the effects of different types of ageing on macro fibre, microfibril and nanofibril reinforced PF composites. The effect of chemical modifications of fibres on the degradability of the composites at different environments also has been analysed. © 2013 Elsevier B.V.