The interaction of two ligand containing electroplating solutions. Final decontamination

We suggested previously a cheap and simple way to decontaminate two ligand-containing rinsing waters of metal finishing. Both copper diphosphate containing rinsing wastewater and acidic zinc ammonium containing rinsing wastewater may be decontaminated by mixing with each other, which results in precipitation of solid solutions of copper-zinc-potassium-ammonium diphosphates. This way of decontamination requires no expensive reagents since only a small amount of H2SO4 is needed for pH adjustment. 80-99.5 % of environmentally dangerous substances, viz. zinc, copper and diphosphate, are removed from the mixture. However, Cu2+ and Zn2+ amounts in filtrates significantly exceed discharge consent level (DCL). Moreover, high concentrations of undesirable diphosphate and ammonium ions, which cause the eutrophication of natural water reservoirs, are present in the filtrates. Depending on the waste water composition of the specific plant and the environment protection requirements the goals of the decontamination may be as follows: 1.) To remove Cu2+ and Zn2+ ions below DCL, 2.) To remove Cu2+ and Zn2+ ions below DCL and additionally to lower the amount of phosphates, 3.) To remove Cu2+ and Zn2+ ions below DCL and additionally to lower the amount of phosphates and ammonium. Our investigation has shown, that goal 1 can be easily and cheaply achieved in industry by using lime, goal 2 – by using lime and spent steel etching solution or phosphogypsum. Goal 3 was achieved by precipitating barely soluble fine crystalline MgNH4PO4 .6H2O. It has been determined, that at optimal conditions as much as 95% of NH4 + ions are precipitated, both residual c Cu2+ and c Zn2+ < DCL, and the concentration of soluble phosphates is reduced 5-40 fold

Cataract-associated mutant E107A of human γD-crystallin shows increased attraction to α-crystallin and enhanced light scattering

Several point mutations in human γD-crystallin (HGD) are now known to be associated with cataract. So far, the in vitro studies of individual mutants of HGD alone have been sufficient in providing plausible molecular mechanisms for the associated cataract in vivo. Nearly all the mutant proteins in solution showed compromised solubility and enhanced light scattering due to altered homologous γ–γ crystallin interactions. In sharp contrast, here we present an intriguing case of a human nuclear cataract-associated mutant of HGD—namely Glu107 to Ala (E107A), which is nearly identical to the wild type in structure, stability, and solubility properties, with one exception: Its pI is higher by nearly one pH unit. This increase dramatically alters its interaction with α-crystallin. There is a striking difference in the liquid–liquid phase separation behavior of E107A–α-crystallin mixtures compared to HGD–α-crystallin mixtures, and the light-scattering intensities are significantly higher for the former. The data show that the two coexisting phases in the E107A–α mixtures differ much more in protein density than those that occur in HGD–α mixtures, as the proportion of α-crystallin approaches that in the lens nucleus. Thus in HGD–α mixtures, the demixing of phases occurs primarily by protein type while in E107A–α mixtures it is increasingly governed by protein density. Analysis of these results suggests that the cataract due to the E107A mutation could result from the instability caused by the altered attractive interactions between dissimilar proteins—i.e., heterologous γ–α crystallin interactions—primarily due to the change in surface electrostatic potential in the mutant protein