The copper ion reduction and oxidation cycle during the cathodic process of gold thiosulfate leaching

Author(s):  
Canyu Zhang ◽  
Qiang Wang ◽  
Yanhe Nie ◽  
Zhiguo Han ◽  
Yifan Su

2019 ◽  
Vol 328 ◽  
pp. 135079
Author(s):  
Yanhe Nie ◽  
Lei Yang ◽  
Qiang Wang ◽  
Changliang Shi ◽  
Futing Zi ◽  
...  


2019 ◽  
Author(s):  
Nobutaka Fujieda ◽  
Sachiko Yanagisawa ◽  
Minoru Kubo ◽  
Genji Kurisu ◽  
Shinobu Itoh

To unveil the activation of dioxygen on the copper centre (Cu<sub>2</sub>O<sub>2</sub>core) of tyrosinase, we performed X-ray crystallograpy with active-form tyrosinase at near atomic resolution. This study provided a novel insight into the catalytic mechanism of the tyrosinase, including the rearrangement of copper-oxygen species as well as the intramolecular migration of copper ion induced by substrate-binding.<br>



2018 ◽  
Vol 69 (1) ◽  
pp. 112-115
Author(s):  
Ana Maria Popescu ◽  
Virgil Constantin

The cathodic behavior of Ce3+ ions in LiF-NaF-BaF2, LiF-NaF-NaCl and NaCl-KCl molten salts at 730� C has been studied using different electrochemical techniques. The decomposition potential (Ed) and the cathodic overvoltage were determined by introducing NaCeF4 as electrochemical active species using steady-state potential-current curves recorded under galvanostatic conditions. The values of |Ed| were 1.85 V in LiF-NaF-BaF2, 2.114 V in LiF-NaF-NaCl and 2.538 V in NaCl-KCl, respectively. It was also found that the ohmic drop potential in melt is not dependent on NaCeF4 concentration and it rises as the current intensity increases. The Tafel slopes and other kinetic parameters were calculated on the assumption that the cathodic process consisted of direct discharge of Ce3+, with no solvent-solute interaction. In order to elucidate the mechanisn of cathodic process the cyclic voltammetry technique was finally used. From the evolution of the voltammograms we conclude that the electrochemical reduction of Ce3+ ion is actually a reversible process on the molybdenum electrode and cathodic reduction of Ce3+ takes place in one single step involving three electron exchange. Our study adds to the accumulating data and confirms available results of electrodeposition of metalic cerium from molten salts using NaCeF4 as solute.



Author(s):  
Mozhgan Ghorbani ◽  
Atefeh Araghi ◽  
Nabi Shariatifar ◽  
Seyed Hooman Mirbaha ◽  
Behrokh Marzban Abbasabadi ◽  
...  

Aims: The aim of this study was to investigate the toxic effect of Echium amoenum plants on the liver and kidney of animal model. Background: Echium amoenum is one of the medicinal plants containing pyrrolizidine alkaloids with several properties which has widely consumed among different communities. Objective: The toxic effects of Echium amoenum on the liver and kidney were investigated in this study. Methods: Sixty mice were kept for 28 days under the appropriate laboratory conditions. Echium amoenum extract (25, 12.5, 50 mg / kg, ip.) was administered for 28 days. At the end of experiment, blood samples were drawn and liver and kidneys were removed for evaluating hepatotoxicity and nephrotoxicity of extract. Additionally, experiments were conducted to assay the enzymatic and oxidative activities. Results: There was no significant difference in the levels of copper ion in the liver and kidneys among all groups. There was a significant difference in the levels of lipid peroxidation in the liver of treated groups versus control group. The significant difference was not observed in the levels of glutathione of the liver of all groups. However, the levels of glutathione of the kidney significantly decreased in the treated groups versus control group. There was no significant difference in the liver enzymes including ALP, SGOT, and SGPT between all groups. This indicates that damage increase with enhancing the time and concentrations of extract. Biochemical analysis showed the creatinine and urea levels did not change in the treated groups versus control group. Conclusion: According to the present findings, it is suggested that Echium amoenum causes hepatotoxicity and nephrotoxicity effects in dose and time dependent manner.





Author(s):  
Abhinav Kumar ◽  
Rajaram Bal ◽  
Rajendra Srivastava

Furfural (FAL) and 5-hydroxymethylfurfural (HMF) are important and sustainable platform chemicals. They are produced from lignocellulose biomass and attract significant attention as precursors for producing value-added chemicals and fuels. The...



Toxics ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Roshni Patel ◽  
Michael Aschner

Alzheimer’s disease, a highly prevalent form of dementia, targets neuron function beginning from the hippocampal region and expanding outwards. Alzheimer’s disease is caused by elevated levels of heavy metals, such as lead, zinc, and copper. Copper is found in many areas of daily life, raising a concern as to how this metal and Alzheimer’s disease are related. Previous studies have not identified the common pathways between excess copper and Alzheimer’s disease etiology. Our review corroborates that both copper and Alzheimer’s disease target the hippocampus, cerebral cortex, cerebellum, and brainstem, affecting motor skills and critical thinking. Additionally, Aβ plaque formation was analyzed beginning from synthesis at the APP parent protein site until Aβ plaque formation was completed. Structural changes were also noted. Further analysis revealed a relationship between amyloid-beta plaques and copper ion concentration. As copper ion levels increased, it bound to the Aβ monomer, expediting the plaque formation process, and furthering neurodegeneration. These conclusions can be utilized in the medical community to further research on the etiology of Alzheimer’s disease and its relationships to copper and other metal-induced neurotoxicity.





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