THE “WORLD’S GREATEST MINERAL LOCALITY”: HAIǁOM, NDONGA, HERERO, AND THE EARLY COLONIAL HISTORIES OF TSUMEB, NAMIBIA

The Tsumeb copper mine in the Otavi Mountains of Namibia is famous both for its spectacular mineral specimens and for its unparalleled diversity of mineral species. The site was mined for nearly 100 years, first by Anglo-German and then by multinational companies; however, prior to that, the site was central to the economies of the Ndonga, Haiǁom, and Herero, who mined, smelted, crafted, and traded the copper. This paper attempts to fill a major gap in the early history of Tsumeb: how did control of Tsumeb’s copper transfer from local communities to Germany? By synthesizing a wide variety of sources, this paper tells pre-colonial and early colonial histories of copper in the Tsumeb area, focusing on the Haiǁom who mined the copper, the Ndonga who smelted and crafted it, and the Herero who had historical relationships with the land. Throughout, the paper attempts to connect Tsumeb’s local history with the larger regional context of South West Africa (now Namibia), and to provide a more in-depth account of the communities whose roles, in previous mineralogic histories of Tsumeb, have been reduced to: ‘trouble with the natives.’

An investigation on the tribological behaviors of steel/copper and steel/steel friction pairs via lubrication with a graphene additive

In this study, the tribological behaviors of graphene as a lubricant additive for steel/copper and steel/steel friction pairs were compared. For the steel/copper friction pair, the graphene sheets remarkably decreased the coefficient of friction and wear scar depth under low loads, but these slightly increased under high loads. The steel/steel friction pair showed excellent tribological properties even under high loads. Severe plastic deformation on the copper surface reduced the stability of the graphene tribofilm because of a rough copper transfer film on the steel during the running-in period. The results provide a better understanding of the mechanism of graphene as a lubricant additive.

Structural basis and mechanism for metallochaperone-assisted assembly of the CuA center in cytochrome oxidase

The mechanisms underlying the biogenesis of the structurally unique, binuclear Cu1.5+•Cu1.5+ redox center (CuA) on subunit II (CoxB) of cytochrome oxidases have been a long-standing mystery. Here, we reconstituted the CoxB•CuA center in vitro from apo-CoxB and the holo-forms of the copper transfer chaperones ScoI and PcuC. A previously unknown, highly stable ScoI•Cu2+•CoxB complex was shown to be rapidly formed as the first intermediate in the pathway. Moreover, our structural data revealed that PcuC has two copper-binding sites, one each for Cu1+ and Cu2+, and that only PcuC•Cu1+•Cu2+ can release CoxB•Cu2+ from the ScoI•Cu2+•CoxB complex. The CoxB•CuA center was then formed quantitatively by transfer of Cu1+ from a second equivalent of PcuC•Cu1+•Cu2+ to CoxB•Cu2+. This metalation pathway is consistent with all available in vivo data and identifies the sources of the Cu ions required for CuA center formation and the order of their delivery to CoxB.

Cu transfer from amyloid-β4–16 to metallothionein-3: the role of the neurotransmitter glutamate and metallothionein-3 Zn(ii)-load states

Copper transfer from Cu(ii)amyloid-β4–16 to human Zn7-metallothionein-3 can be accelerated by glutamate and by lowering the Zn-load of metallothionein-3 with EDTA.

Kinetic analysis of copper transfer from a chaperone to its target protein mediated by complex formation

Rate of Cu(i) transfer between chaperone and target protein is enhanced dramatically by complex formation.