Cyanides and Their Attenuation in Wastewaters Using Green Chemistry

Cyanides, though naturally occurring, are environmental pollutants when not treated properly. Some methods used to attenuate cyanides in waste waters from industrial processes are based simply on changing the physico-chemical properties of the waste water such as the pH and temperature. The effectiveness of these methods are based on hydrolysis of the cyanide and volatilization of the hydrogen cyanide formed. Another reaction which takes place simultaneously is ultraviolet-catalysed oxidation which converts the cyanide to bicarbonates and carbonates.The changes in the cyanide degradation rate approaches a minimum faster if the cyanide solution is maintained at a higher than ambient constant temperature.

Oxidative Stress Conditions Result in Trapping of PHF-Core Tau (297–391) Intermediates

The self-assembly of tau into paired helical filaments (PHFs) in neurofibrillary tangles (NFTs) is a significant event in Alzheimer’s disease (AD) pathogenesis. Numerous post-translational modifications enhance or inhibit tau assembly into NFTs. Oxidative stress, which accompanies AD, induces multiple post-translational modifications in proteins, including the formation of dityrosine (DiY) cross-links. Previous studies have revealed that metal-catalysed oxidation (MCO) using Cu2+ and H2O2 leads to the formation of DiY cross-links in two misfolding proteins, Aβ and α-synuclein, associated with AD and Parkinson’s disease respectively. The effect of MCO on tau remains unknown. Here, we examined the effect of MCO and ultra-violet oxidation to study the influence of DiY cross-linking on the self-assembly of the PHF-core tau fragment. We report that DiY cross-linking facilitates tau assembly into tau oligomers that fail to bind thioflavin S, lack β-sheet structure and prevents their elongation into filaments. At a higher concentration, Cu2+ (without H2O2) also facilitates the formation of these tau oligomers. The DiY cross-linked tau oligomers do not cause cell death. Our findings suggest that DiY cross-linking of pre-assembled tau promotes the formation of soluble tau oligomers that show no acute impact on cell viability.

Unveiling the catalytic potential of the Fe(IV)oxo species for the oxidation of hydrocarbons in the solid state

We present the computational study of the ferryl-catalysed oxidation of methane into methanol in a solid-state system, the metal-organic framework MOF-74 with Fe(IV)O moieties in its cavities. We use spin-polarised...

Protein Formulations Containing Polysorbates: Are Metal Chelators Needed at All?

Proteins are prone to post-translational modifications at specific sites, which can affect their physicochemical properties, and consequently also their safety and efficacy. Sources of post-translational modifications include oxygen and reactive oxygen species. Additionally, catalytic amounts of Fe(II) or Cu(I) can promote increased activities of reactive oxygen species, and thus catalyse the production of particularly reactive hydroxyl radicals. When oxidative post-translational modifications are detected in the biopharmaceutical industry, it is common practice to add chelators to the formulation. However, the resultant complexes with metals can be even more damaging. Indeed, this is supported here using an ascorbate redox system assay and peptide mapping. Ethylenediaminetetraacetic acid (EDTA) addition strongly accelerated the formation of hydroxyl radicals in an iron-ascorbate system, while diethylenetriaminepentaacetic acid (DTPA) addition did not. When Fe(III) was substituted with Cu(II), EDTA addition almost stopped hydroxyl radical production, whereas DTPA addition showed continued production, but at a reduced rate. Further, EDTA accelerated metal-catalysed oxidation of proteins, and thus did not protect them from Fe-mediated oxidative damage. As every formulation is unique, justification for EDTA or DTPA addition should be based on experimental data and not common practice.

Interaction of Hydrogen with Actinide Dioxide (011) Surfaces

<p>The hydrogen catalysed oxidation of nuclear materials has led to containment vessel failure. The interaction of hydrogen with actinide dioxide (AnO₂, An = U, Np, Pu) (011) surfaces has been completed by DFT+U; where, spin-orbit interactions and noncollinear 3k antiferromagnetic behaviour have been included. The energy of atomic hydrogen adsorption for UO₂ (0.44 eV), NpO₂ (-0.47 eV), and PuO₂ (-1.71 eV) has been calculated, where the subsequent formation of an OH group is shown to distort the surface structure. The dissociation of hydrogen on the PuO₂ (011) surfaces has been found; however, UO₂ (011) and NpO₂ (011) surfaces are relatively inert. The recombination of hydrogen ions on the UO₂ (011) and NpO₂ (011) surfaces is highly-probable; whereas, hydroxide formation on the PuO₂ (011) surface has been shown. The results have consequences for fuel storage management.</p>