Proposed calendar of conferences of ECLAC for the period 2008-2010. Note by the Secretariat

Includes bibliography

Calendario de conferencias intergubernamentales de la CEPAL propuesto para el período 1984-1986 = Proposed calendar of intergovernmental conferences of ECLA for the period 1984-1986

Incluye Bibliografía

Photo-Fenton degradation kinetics of low ciprofloxacin concentration using different iron sources and pH

The aim of the present study was to compare the degradation kinetics of low (1 mg L-1) and high (25 mg L-1) concentrations of ciprofloxacin (CIP) aiming to decrease the concentration of additives and evaluate the pH limitation by the use of low iron concentrations and organic ligands. A parameterized kinetic model was satisfactorily fitted to the experimental data in order to study the performance of photo-Fenton process with specific iron sources (iron citrate, iron oxalate, iron nitrate) under different pH medium (2.5, 4.5, 6.5). The process modeling allowed selecting those process conditions (iron source, additives concentrations and pH medium) which maximize the two performance parameters related to the global equilibrium conversion and kinetic rate of the process. For the high CIP concentration, degradation was very influenced by the iron source, resulting in much lower efficiency with iron nitrate. At pH 4.5, highest TOC removal (0.87) was achieved in the presence of iron citrate, while similar CIP conversions were obtained with oxalate and citrate (0.98 after 10 min). For the low CIP concentration, much higher conversion was observed in the presence of citrate or oxalate in relation to iron nitrate up to pH 4.5. This behavior denotes the importance of complexation also at low dosages. Appropriate additives load (320 μM H 2O2; 6 μM Fe) resulted in a CIP conversion of 0.96 after10 min reaction with citrate up to pH 4.5. © 2013 Elsevier B.V. All rights reserved.

Calendario de conferencias de la CEPAL propuesto para el período 1986-1988 = Proposed calendar of conferences of ECLAC for the period 1986-1988

Incluye Bibliografía

Calendario de conferencias de la CEPAL propuesto para el período 1988-1990 = Proposed calendar of conferences of ECLAC for the period 1988-1990 = Calendrier de conférences de la CEPALC proposé pour la période 1988-1990

Incluye Bibliografía

Deposition and photo-induced electrical resistivity of dip-coated NiO thin films from a precipitation process

Thin films of the semiconductor NiO are deposited using a straightforward combination of simple and versatile techniques: the co-precipitation in aqueous media along with the dip- coating process. The obtained material is characterized by gravimetric/differential thermal analysis (TG-DTA) and X-ray diffraction technique. TG curve shows 30 % of total mass loss, whereas DTA indicates the formation of the NiO phase about 578 K (305 C). X-ray diffraction (XRD) data confirms the FCC crystalline phase of NiO, whose crystallinity increases with thermal annealing temperature. UV-Vis optical absorption measurements are carried out for films deposited on quartz substrate in order to avoid the masking of bandgap evaluation by substrate spectra overlapping. The evaluated bandgap is about 3.0 eV. Current-voltage (I-V) curves measured for different temperatures as well as the temperature-dependent resistivity data show typical semiconductor behavior with the resistivity increasing with the decreasing of temperature. The Arrhenius plot reveals a level 233 meV above the conduction band top, which was attributed to Ni2+ vacancy level, responsible for the p-type electrical nature of NiO, even in undoped samples. Light irradiation on the films leads to a remarkable behavior, because above bandgap light induced a resistivity increase, despite the electron-hole generation. This performance was associated with excitation of the Ni 2+ vacancy level, due to the proximity between energy levels. © 2012 Springer Science+Business Media New York.

El desarrollo social de América Latina en la postguerra = The social development of Latin America in the post-war period

Publicado sólo en español por Solar/Hachette de Buenos Aires

Calendario provisional de conferencias del sistema de la CEPAL en el bienio 1990-1992 = Proposed calendar of conferences of ECLAC for the period 1990-1992 = Calendrier de conférences de la CEPALC proposé pour la période 1990-1992

Contiene anexos con: Estructura intergubernamental y funciones de la CEPAL; principales órganos y reuniones del Sistema; Resolución 44/228 de la Asamblea General sobre la Conferencia de las Naciones Unidas sobre Medio Ambiente y Desarrollo; Resolución 40/243 también de la Asamblea General sobre el Plan de Conferencias; y Calendario de Conferencias Intergubernamentales de la CEPAL para el período 1990-1992.