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Chapter 15 Audiology
Published in B H Brown, R H Smallwood, D C Barber, P V Lawford, D R Hose, Medical Physics and Biomedical Engineering, 2017
In order to limit the current which can flow a constant current as distinct from a constant voltage stimulus is usually used. The constant current stimulus also has the advantage that the threshold to stimulation does not depend upon electrode impedance and so will not change with time as the electrode interface changes. In addition to limiting the charge which can be delivered it is important to avoid electrode polarization and the release of toxic products from electrochemical reactions by preventing any DC current flow. This is usually done by using a charge-balanced bipolar stimulus with both positive and negative phases.
Acetaminophen degradation in aqueous solution by the UV-LED-EC/Cl2 process
Published in Environmental Technology, 2023
Na Sun, Xianglian Wang, Zhanmeng Liu
The experiments were conducted in a recirculation flow system consisting of an EC reactor and a circulating water system, as plotted in Figure 1. The working volume of the electrolytic cell is 100 mL. In the electrolytic cell, a RuO2-IrO2/Ti plate anode (3.0 cm × 3.0 cm) and a stainless steel mesh cathode with the same dimension were adjusted parallel at a distance of 2.0 cm. The reference electrode is an Ag/AgCl electrode. A LED-UV lamp (10 W, main wavelength 275 nm) was installed on the centre of the reactor lid. The solution temperature was kept at about 20 ± 2°C using a circulating water bath. The solution was well homogenized by a magnetic stirrer, and a direct current power supply was employed to perform the experiments under constant current conditions. 100 mL 2 μM AAP solution (spiked with 14C-AAP at a level of 1.0 µCi/L) was introduced into this system and then recirculated through the system by a peristaltic pump at a flow rate of 10 mL/min. During the experiments, solution pH was adjusted using H2SO4 or NaOH solution (both at 0.1 M), and tests were conducted in phosphate buffer saline (PBS, 5–20 mM). Solution samples were collected for analysis at a pre-selected time interval. Effects of key parameters (i.e. anodic potential, solution pH, NaCl concentration and PBS concentration) on AAP degradation were investigated detailed by batch tests. All samples were quenched with sodium thiosulfate before the measurement.
The continued development of multilayered and compositionally modulated electrodeposits
Published in Transactions of the IMF, 2022
The literature on multilayer coatings has traditionally been dominated by very thin (nanometre thick) films produced by dry, vacuum deposition techniques (PVD and CVD including PECVD) together with the physical and materials physics properties of the films. Electroplating has a long, distinguished history as a technology for the controlled deposition of single metal and alloy coatings.4,5 Following suitable pretreatment of the metal substrate to facilitate good nucleation, a constant current, I is normally applied to a known area of cathode, A using a smooth, direct current power supply. If the current density, J over the cathode is uniform and the current efficiency, ψ is constant, metal deposition takes place at a predictable rate. If deposition is uniform, the average coating thickness, x may be controlled by adjusting the deposition time, t according to Faraday’s laws of electrolysis:6where M is the molar mass of the depositing metal, ρ is its density, z is the electron stoichiometry and F is the Faraday constant. The current efficiency, ψ is the ratio of the current used to deposit metal, IM to the total current, I:
Coupling of the optimized electro-Fenton-like process with pulsed laser ablation method to produce bimetallic nanoparticles of Fe°/Cu° and Fe°/Zn° in treatment of thiophene aqueous samples
Published in Environmental Technology, 2022
Hamid Reza Pouretedal, Mohammad Mehdi Amooshahi, Sajjad Damiri
A cylindrical glass beaker containing 1000 mL solution was used as a reactor (see Figure 1). One pair of graphite coin-shaped plates (OD 5 cm) as anode and cathode was positioned in the reactor at a distance of 1 cm from each other. The Q-smart 850 pulsed Nd:YAG laser (from Quantel by LUMIBIRD/ France) was used for pulsed laser ablation in liquid. The target pill was fixed with a clamp and exposed to Nd:YAG pulsed laser radiation (λ = 1064 nm, 300 mJ energy per pulse with 5 ns pulse duration) within 10 min. The generated nanoparticles were dispersed in the sample by a mechanical mixer. Electrolysis were carried out at a constant current (I) using a DC power supply (Iran electronics, Model 8303). The conductivity of the samples was checked using conductivity Meter (model S30-K SevenEasy, Mettler Toledo Switzerland). A digital pH meter (model 691, Metrohm AG Switzerland) was used to control pH of the samples.