Highly selective transport of mercury(II) ion through a bulk liquid membrane

In this work carrier-facilitated transport of mercury(II) against its concentration gradient from aqueous 0.04 M hydrochloric acid solution across a liquid membrane containing isopropyl 2-[(isopropoxycarbothiolyl)disulfanyl]ethane thioate (IIDE) as the mobile carrier in chloroform has been investigated. Sodium thiocyanate solution (1.6 M) was the most efficient receiving phase agent among several aqueous reagents tested. Various parameters such as investigated. Under optimum conditions the transport of Hg(II) across the liquid membrane is more than 97% after 2.5 h. The carrier, IIDE, selectively and efficiently could able to transport Hg (II) ions in the presence of other associated metal ions in binary systems.

Instabilities in electrochemical systems with a rotating disc electrode

Polarization curves experimentally obtained in the electro-dissolution of iron in a 1 M H2SO4 solution using a rotating disc as the working electrode present a current instability region within the range of applied voltage in which the current is controlled by mass transport in the electrolyte. According to the literature (Barcia et. al., 1992) the electro-dissolution process leads to the existence of a viscosity gradient in the interface metal-solution, which leads to a velocity field quantitatively different form the one developed in uniform viscosity conditions and may affect the stability of the hydrodynamic field. The purpose of this work is to investigate whether a steady viscosity profile, depending on the distance to the electrode surface, affects the stability properties of the classic velocity field near a rotating disc. Two classes of perturbations are considered: perturbations monotonically varying along the radial direction, and perturbations periodically modulated along the radial direction. The results show that the hydrodynamic field is always stable with respect to the first class of perturbations and that the neutral stability curves are modified by the presence of a viscosity gradient in the second case, in the sense of reducing the critical Reynolds number beyond which perturbations are amplified. This result supports the hypothesis that the current oscillations observed in the polarization curve may originate from a hydrodynamic instability.

Public management, policy capacity, innovation and development

In this paper we discuss the question of what factors in development policy create specific forms of policy capacity and under what circumstances developmentoriented complementarities or mismatches between the public and private sectors emerge. We argue that specific forms of policy capacity emerge from three interlinked policy choices, each fundamentally evolutionary in nature: policy choices on understanding the nature and sources of technical change and innovation; on the ways of financing economic growth, in particular technical change; and on the nature of public management to deliver and implement both previous sets of policy choices. Thus, policy capacity is not so much a continuum of abilities (from less to more), but rather a variety of modes of making policy that originate from co-evolutionary processes in capitalist development. To illustrate, we briefly reflect upon how the East Asian developmental states of the 1960s-1980s and Eastern European transition policies since the 1990s led to almost opposite institutional systems for financing, designing and managing development strategies, and how this led, through co-evolutionary processes, to different forms of policy capacity.