Spectrophotometric determination of manganese in steels by on-line electrochemical oxidation

The aim of this work is to propose a flow spectrophotometric procedure for manganese determination in steel based on electrochemical oxidation of Mn(II) to Mn(VII) at a Pt electrode surface by means of the catalytic effect of Ag(I). The on-line oxidation step was obtained by injecting sample and electrolyte solution directly into an electrolytic cell. After electrolysis, the injectate was homogenized by bubbling air. The permanganate ions produced were passed through the spectrophotometer where absorbance was monitored at 545 nm. Effects of direct current, silver concentration, timing, flow rates, concentration and composition of support electrolyte were investigated. Direct current and silver content manifested themselves as the most relevant parameters. For determination of manganese in the 5.00 - 150 mg L -1 range (r=0,9998) and 60 s electrolysis time, the sample throughput was 20 h -1. Accuracy was assessed by analyzing ten steel standard reference materials. Results are precise (R.S.D. <3%) and in agreement with certified values of reference materials and with standard methods at 95% confidence level.

Solid mass falling into the reservoirs shallow water equations validity from the engineering point of view

Water waves generated by a solid mass is a complex phenomenon discussed in this paper by numerical and experimental approaches. A model based on shallow water equations with shocks (Saint Venant) has developed. It can reproduce the amplitude and the energy of the wave quite well, but because it consistently generates a hydraulic jump, it is able to reproduce the profile, in the case of high relative thickness of slide, but in the case of small relative thickness it is unable to reproduce the amplitude of the wave. As the momentum conservation is not verified during the phase of wave creation, a second technique based on discharge transfer coefficient α, is introduced at the zone of impact. Numerical tests have been performed and validated this technique from the experimental results of the wave's height obtained in a flume.

Economic profiles of Caribbean countries

Includes bibliography

Inflation and the variability of relative prices in the Caribbean: evidence from panel threshold models

Includes bibliography

Economic Survey of the Caribbean 2011-2012: positive growth amidst lingering downside risks

Includes bibliography

A arquitetura espontânea de Niki de Saint Phalle: o jardim de tarô

Pós-graduação em Artes - IA

Aspectos ultrassonográficos, biometria e dopplerfluxometria ocular de primatas-Alouatta fusca (BUGIO RUIVO-Geoffroy Saint-Hilaire, 1812)

Pós-graduação em Medicina Veterinária - FMVZ

Relations between CARICOM and Central America and the Dominican Republic: a window of opportunity for trade and investment

Includes bibliography

Study of gender mainstreaming in the Caribbean

Includes bibliography

Development social policy for youth with special reference to young men in Saint Lucia

Includes bibliography

Trade and investment flows between the Caribbean and the rest of the hemisphere in the context of the FTAA

Includes bibliography

Caribbean policy response to the information age: a review of government information and communications technology policy and services in selected Caribbean countries

Includes bibliography

Developments in relation to the proposal for securing the international recognition of the Caribbean sea as a special area in the context of sustainable development

Includes bibliography

Report of the Grenada national yachting consultation

The Economic Commission for Latin America and the Caribbean (ECLAC); Subregional Headquarters for the Caribbean embarked on a project "Development of a Subregional Marine-based Tourism Strategy" in 2001. The project, co-funded by the Government of the Netherlands, is aimed at the development of sustainable yachting tourism in the Eastern Caribbean and focuses on the island arc from the British Virgin Islands in the north to Trinidad and Tobago in the south. The project includes the conduct of national studies in the British Virgin Islands, St. Maarten, Antigua and Barbuda, Saint Lucia, Saint Vincent and the Grenadines, Grenada and Trinidad and Tobago. In all countries the national studies were preceded by consultations with the private and public sector and, following completion of the national reports, the findings were similarly discussed through a private and public sector consultation. On 26 March 2003, as part of the project's activities, a national consultation on yachting in Grenada was convened by the Ministry of Tourism, Civil Aviation, Culture, Social Security, Gender and Family Affairs in collaboration with the Marine and Yachting Association of Grenada (MAYAG); and ECLAC. One of the objectives of the consultation was to review the report "Grenada, Carriacou and Petit Martinique: The Yachting Sector" that was prepared by the ECLAC Subregional Headquarters of the Caribbean and co-sponsored by the Government of the Netherlands. A second objective included the provision of a forum for a private sector-government discussion on yachting and the pleasure boat industry and its contribution to Grenada. The final objective was the identification of ways and means to increase the contribution of yachting as a viable component of the tourism industry in Grenada.

Challenges in meeting the monitoring requirements of the Millennium Development Goals (MDGs): an examination of selected social statistics for four Caribbean small island developing states

Includes bibliography