The Rise and Fall of the « Fourth Empire of the St. Lawrence » : the Québec-Labrador Iron Ore Mining Region

Le présent article porte sur la naissance et le déclin de l'industrie de l'extraction du minerai de fer de la fosse du Labrador. La croissance de l'exploration minière, le développement de la région, l'expansion de l'industrie et finalement son déclin sont considérés pour la période s'étendant des environs de 1950 jusqu'à 1984. Plus particulièrement, il sera question d'un cas de développement économique régional basé sur une industrie unique et de l'absence de croissance industrielle à long terme.This paper is based upon a discussion of the rise and fall of the iron ore mining industry in the Labrador trough of the Québec-Labrador region. The growth of exploration, development, expansion and decline phases are noted over the period between 1950 (circa) to 1984. Reference is made to the single industry nature of the industrialization process in the region and to the absence of long-term industrial growth

Organic chemistry for the laboratory

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The influence of carbonate complexation on lanthanide/actinide sorption on montmorillonite

The safety case for radioactive waste repositories is, to a large extend based on the physical and chemical retention of radionuclides on clay minerals which are important constituents in both the man-made engineered barriers and in argillaceous host rock formations. The presence of carbonate, one of the most important inorganic ligands for lanthanide and actinide ions in groundwaters and clay porewaters, can have a significant influence on their sorption behaviour on clay minerals. The sorption of Eu(III) on Na-montmorillonite in the absence and the presence of carbonate was investigated in batch sorption experiments. In the presence of carbonate two sets of experimental conditions were investigated. Eu(III) sorption measurements were performed as a function of pH in equilibrium with atmospheric pCO2 (=10−3.5bar) and at a variable pCO2 (=10−1.4 to 10−3.4bar). The sorption data were modelled using the 2 site protolysis non-electrostatic surface complexation and cation exchange model. Both experimental data sets in the presence of carbon could be quantitatively modelled by including in the sorption model two additional surface complexation reactions on the strong sites forming ≡SSOEuCO30 and ≡SSOEuOHCO3− surface complexe

High precision quantum control of single donor spins in silicon

The Stark shift of the hyperfine coupling constant is investigated for a P donor in Si far below the ionization regime in the presence of interfaces using Tight-binding and Band Minima Basis approaches and compared to the recent precision measurements. The TB electronic structure calculations included over 3 million atoms. In contrast to previous effective mass based results, the quadratic Stark coefficient obtained from both theories agrees closely with the experiments. This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control. It is also shown that there is a significant linear Stark effect for an impurity near the interface, whereas, far from the interface, the quadratic Stark effect dominates. Such precise control of single donor spin states is required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work.Comment: 5 pages, 2 figure