Electrochemical Impedance Spectroscopy (EIS) Explanation of Single Crystal Cu(100)/Cu(111) in Different Corrosion Stages.

Copper and its alloys are used widely in marine environments, and anisotropic corrosion influences the corrosion kinetics of copper. Corrosion of copper in an electrolyte containing Cl- is described as a dissolution-deposition process, which is a prolonged process. Therefore, it is laborious to clarify the corrosion anisotropy in different stages. In this paper, electrochemical impedance spectroscopy (EIS) following elapsed open circuit potential (OCP) test with 0 h (0H), 24 h (24H) and 10 days (10D) was adopted. To exclude interruptions such as grain boundary and neighbor effect, single crystal (SC) Cu(100) and Cu(111) were employed. After 10D OCP, cross-sectional slices were cut and picked up by a focused ion beam (FIB). The results showed that the deposited oxide was Cu2O and Cu(100)/Cu(111) experienced different corrosion behaviors. In general, Cu(100) showed more excellent corrosion resistance. Combined with equivalent electrical circuit (EEC) diagrams, the corrosion mechanism of Cu(100)/Cu(111) in different stages was proposed. In the initial stage, a smaller capacitive loop of Cu(111) suggested preferential adsorption of Cl- on air-formed oxide film on Cu(111). Deposited oxide and exposed bare metals also played an important role in corrosion resistance. Rectangle indentations and pyramidal structures formed on Cu(100)/Cu(111), respectively. Finally, a perfect interface on Cu(100) explained the tremendous capacitive loop and higher impedance (14,274 Ω·cm2). Moreover, defects in the oxides on Cu(111) provided channels for the penetration of electrolyte, leading to a lower impedance (9423 Ω·cm2) after 10D corrosion.

Electrochemical migration behavior of moldy printed circuit boards in a 10 mT magnetic field.

In the electrochemical migration behavior (ECM) of printed circuit boards containing mold under a static magnetic field (SMF), the role of the field perpendicular to the electrodes is discussed; the B field inhibits the growth and metabolism of mold, while controlling electrochemical diffusion and nucleation. The field indirectly affects the function of mold as a transmission bridge between two electrodes. In this work, the water drop test was used to simulate the adhesion and growth of mold on the circuit board in a humid and hot environment; confocal laser scanning microscopy, scanning electron microscopy, energy dispersive spectroscopy, Raman spectra, and a scanning Kelvin probe were used to analyze the mechanism of static magnetic field and mold on the electrochemical migration.

Effects of mould on electrochemical migration behaviour of immersion silver finished printed circuit board.

The role played by mould in the electrochemical migration (ECM) behaviour of an immersion silver finished printed circuit board (PCB-ImAg) under a direct current (DC) bias was investigated. An interesting phenomenon is found whereby mould, especially Aspergillus niger, can preferentially grow well on PCB-ImAg under electrical bias and then bridge integrated circuits and form a migration path. The cooperation of the mould and DC bias aggravates the ECM process occurring on PCB-ImAg. When the bias voltage is below 15V, ECM almost does not occur for Ag coating. Mechanisms that explain the ECM processes of PCB-ImAg in the presence of mould and DC bias are proposed.

[Simultaneous analysis of 4 non-steroidal anti-inflammatory drug residues in mutton muscle using high performance liquid chromatography assisted by ultrasonic-microwave extraction].

A method for the simultaneous determination of 4 non-steroidal anti-inflammatory drug (NSAID) residues, including flunixin meglumine, meloxicam, diclofenac sodium and ketoprofen, in mutton muscle was developed using high performance liquid chromatography assisted by ultrasonic-microwave extraction. The NSAIDs were extracted with acidified ethanol and purified by a diatomite column. The subsequent analysis of NSAIDs was achieved on a Hypersil C18 column (250 mm x 4.6 mm, 5 microm) with the mobile phase of acetonitrile-0.2% triethylamine (40 : 60, v/v, pH 3.5 adjusted by phosphoric acid) at a flow rate of 0.8 mL/min at 30 degrees C. The detection wavelength was set at 255 nm. The 4 NSAIDs were well separated within 20 min. The correlation coefficients for 4 NSAIDs were from 0.999 3 to 0.999 8 with the limits of detection (LOD, S/N = 3) of 5-10 microg/kg and the limits of quantification (LOQ, S/N = 10) of 15-30 microg/kg. The recoveries were in the range of 65.3% - 99.6% with the relative standard deviations (RSDs) less than 15%. This method is simple, rapid and highly sensitive, and can meet the requirement for the qualitative and quantitative analysis.