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The anodic oxidation process of Fe-Ni alloys containing various components as anodes in 48.2NaF-43.8AlF 3 -8.0Al 2 O 3 (wt%) molten salts at 980°C was characterized using linear sweep voltammetry. The anodic polarization curves of all of the Fe-Ni alloys, which displayed a typical active-passive-transpassive feature, are similar to that of Fe. Based on the dissolution-precipitation mechanism, an initial passivation film comprised of FeO was formed at a passivation potential. Subsequently, FeO was oxidized to Fe 2 O 3 , resulting in the formation of an outer film overlying the FeO film, which corresponded with the scanning electron microscopy and energy-dispersive X-ray spectrometry results, showing that the main components of the passivation film were iron oxides. Because of the chemical dissolution of oxides, oxides are continuously formed to resist chemical dissolution and protect the alloy matrix. The passivation film was broken down during oxygen evolution because of a lack of alumina. No passive behavior was observed on Ni. In addition, the preoxidized alloys possessed superior corrosion resistance to that of the nonoxidized alloys. The preoxidized 43Fe-57Ni alloy was observed to be stable during constant-current electrolysis based on a chronopotentiometric study, indicating that the preoxidized 43Fe-57Ni alloy had a good corrosion resistance to the cryolite-alumina molten salts.

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In this work, the results on using biosensor composed from quantum dots as transducer and acetylcholinesterase enzymes (AChE) to detect pesticides optically are presented. The used quantum dots were CdTe, CdSe/ZnS 10 monolayer (ML) and CdSe/ZnSe2ML/ZnS 8 ML – the brand new thick-shell quantum dots (QD). The study results pointed out that the CdSe/ZnS 10 ML and CdSe/ZnSe 2ML/ZnS 8ML quantum dots best fit for the role of transducers in biosensors. In the biosensor, acetylthiocholine (ATCh) is used as indicator for the AChE enzymes to work, since it is a very powerful hydrolyte with the presence of AChE enzymes. Moreover, the organophosphorus (OP) pesticides are the inhibitors for the AChE enzymes, thus, by the biosensors that we designed, we can detect pesticides by the change in photoluminescence (PL) intensity of QDs, with the detection of OP like parathion methyl is 0.05 ppm, and acetamiprid is 2.5 ppm.