Search

The world's shortage of raw materials favoures the interest towards mineral waste materials as a potential source of valuable metals and minerals. In the past century, mining and metallurgical activities of copper mines and smelters in Albania (Kurbnesh, Reps, Gjegjan, Kukës, Rubik, Lac, Rreshen) storaged various waste materials as waste rocks, flotation tailings, metallurgical slags and residues. To date, these "environmental hotspots" occur in old abandoned tailings storage facilities in Albania and present a serious risk of environmental damages and disasters like dam failures, ground water and surface water pollution. Even displacements of dry fine materials containing heavy metals by wind, could result in a permanent pollution of the surrounding area and finally of the Adriatic Sea. This research presents the characterisation and processing of tailings material from abandoned tailings from Kurbnesh (Albania) using mineralogical, physical and chemical methods. The processed tailings mainly consist of sulfides (10 wt %), Mg, Ca, Fe silicates (46 wt %) and quartz (40 wt %). Copper (0.15 wt %) and cobalt (0.03 wt %) were determined as major valuable metals and are distributed in chalcopyrite, cobaltite and cobaltiferous pyrite. These sulfide minerals were recovered by a collective flotation, followed by a selective flotation of the copper minerals. The recovery of the sulfide minerals in a desulfurization route results in obtaining of reprocessed tailings with a low acid-generating potential. Additionally, the magnetic separation was tested to separate accompanied valuable minerals—complex Mg, Ca, Fe silicates from quartz—to recover them as a by-product and to minimize the storaged volume of reprocessed tailings. Finally, a possible usage of the obtained mineral products is suggested. [ABSTRACT FROM AUTHOR]

We study the Ricci iteration for homogeneous metrics on spheres and complex projective spaces. Such metrics can be described in terms of modifying the canonical metric on the fibers of a Hopf fibration. When the fibers of the Hopf fibration are circles or spheres of dimension 2 or 7, we observe that the Ricci iteration as well as all ancient Ricci iterations can be completely described using known results. The remaining and most challenging case is when the fibers are spheres of dimension 3. On the 3-sphere itself, using a result of Hamilton on the prescribed Ricci curvature equation, we establish existence and convergence of the Ricci iteration and confirm in this setting a conjecture on the relationship between ancient Ricci iterations and ancient solutions to the Ricci ow. In higher dimensions we obtain sufficient conditions for the solvability of the prescribed Ricci curvature equation as well as partial results on the behavior of the Ricci iteration. [ABSTRACT FROM AUTHOR]

In order to study interferon regulatory factor (IRF) family mediation of cell growth regulation, we established U937 cell lines stably transfected with a truncated form of IRF-2 lacking the transcriptional repressor domain. The truncated IRF-2 contained the DNA binding domain (DBD) and bound the ISRE. Phenotypically, the IRF-2 DBD transfectants exhibited reduced cell growth, altered morphology and increased cell death. Consistent with alterations in growth characteristics, the IRF-2 DBD transfectants constitutively expressed higher levels of the cyclin dependent kinase inhibitor p21WAF1/Cip1 than did control clones. The level of p21WAF1/Cip1 expression was positively correlated with the level of DBD expressed, as well as with the level of growth inhibition in these clones. DBD expression also correlated with expression of other members of the growth regulatory complex, cyclin dependent kinase 2 and cyclin A, but not proliferating cell nuclear antigen. These results imply active repression by IRF-2 to keep p21WAF1/Cip1 transcriptionally silent. Oncogene (2000) 19, 1411–1418 [ABSTRACT FROM AUTHOR]