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Electrophysiology
Published in A. Bakiya, K. Kamalanand, R. L. J. De Britto, Mechano-Electric Correlations in the Human Physiological System, 2021
A. Bakiya, K. Kamalanand, R. L. J. De Britto
The concentration of the ions in the solution changes during the electron and ion interaction. Hence, the charge neutrality is inconsistent in this region, and hence, the electrolyte surrounding the conducting metal is at a different electrical potential from the rest of the solution. This potential difference is called a half-cell potential (Bronzino, 2000). The half-cell potential is most important when using the electrodes for DC measurement (Albulbul, 2016; Bronzino, 2000).
Methods of Protein Iodination
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
Half cell denotes an electrode dipping into a solution and connected with a potentiometer and a battery for the measurement of electric energy generated by chemical reactions. Two half cells combined constitute an electrochemical cell.
Designing a Low-Cost ECG Sensor and Monitor: Practical Considerations and Measures
Published in Daniel Tze Huei Lai, Rezaul Begg, Marimuthu Palaniswami, Healthcare Sensor Networks, 2016
Ahsan H. Khandoker, Brian A. Walker
The best materials to use for electrodes minimize the half cell potential (which causes DC baseline offsets and drifts), are easy to manufacture and are not highly reactive. Materials which produce low half cell potentials increase electrode stability. For example, lithium would not be used for the electrodes as its half cell potential is −3 V, and its reactivity is enough to burn the skin. Another problem to consider is that the half cell potential could vary depending on the amount of current flowing through the electrode. This is known as an overpotential (Hinz 2002). Electrodes which do not have overpotentials are known as nonpolarizable electrodes. Examples of nonpolarizable electrodes include those made from copper and silver chloride (Allaby and Allaby 1999). Normally, commercial electrodes are made from silver with a coating of silver chloride (Amer 2008). The half cell potential of silver chloride is very low, 223 mV, and is ideal for ECG measurement. Copper can also give satisfactory results; it has a half cell potential of 342 mV (Hinz 2002).
Artificial membranes in combination with selected natural oils for in vitro drug passive diffusion screening in Ussing type chamber apparatus applied to gastro-retentive systems
Published in Pharmaceutical Development and Technology, 2020
Mark Fensham, Jan Steenekamp, Adriaan Jacobs, Josias Hamman
All the in vitro permeation studies were conducted in a Sweetana-Grass diffusion chamber apparatus (Harvard NaviCyte apparatus, Warner Instruments, USA). The permeation of R6G (5 µg/ml) from the donor chamber (7 ml) into the acceptor chamber (7 ml) was determined. Each artificial membrane with and without oil impregnation was mounted between the half-cells of 3 diffusion chambers and tested individually. Carbogen (5% CO2/95% O2) gas was bubbled through the permeation medium continuously at both sides of the mounted artificial membrane. The temperature was maintained at 37 ± 0.5 °C by placing the assembled half-cells onto a heating block. Samples of 180 µl were collected from the acceptor chamber and replaced with equal amounts of pre-heated medium (i.e. KRB or 0.1 N HCl) every 20 min for the duration of the experiment (120 min).
Formulation and investigation of pilocarpine hydrochloride niosomal gels for the treatment of glaucoma: intraocular pressure measurement in white albino rabbits
Published in Drug Delivery, 2020
Neelam Jain, Anurag Verma, Neeraj Jain
Freshly excised whole cow eyeball was procured from a slaughter house and transported to the laboratory in cold condition. They were maintained in normal saline at 4 °C. The cornea was then carefully removed along with a 5–6 mm of surrounding scleral tissue and washed with cold saline. The washed cornea was preserved in freshly prepared phosphate buffer (pH 7.4) and stored under refrigeration until the time of the study. The preserved cornea was mounted on Franz diffusion cell by sandwiching between the donor and receptor compartment. It was positioned on the donor half-cell such that the epithelial surface was facing the donor solution. The receptor half-cell was positioned symmetrically opposing the donor half-cell. The half-cells were secured together with a clamp. This procedure prevents any leaks (Rasool et al., 2014).
Permeation-enhancing effects and mechanisms of O-acylterpineol on isosorbide dinitrate: mechanistic insights based on ATR-FTIR spectroscopy, molecular modeling, and CLSM images
Published in Drug Delivery, 2019
Yan Li, Chunyan Wang, Jian Wang, Tianzhe Chu, Linlin Zhao, Ligang Zhao
Skin permeation experiments were performed according to the previous report (Zhao et al., 2008a). A diffusion cell consisting of two half-cells with a water jacket connected to a water bath at 32 °C was used. Each half-cell had a volume of 2.5 ml and an effective area of 0.95 cm2. The dermis side of the skin was in contact with the receiver compartment and the SC with the donor compartment. The donor compartment was filled with the drug suspension and the receiver compartment with pH 7.4 PBS. During all the experiments, excess drug was maintained in the donor compartment. Both donor and receiver compartments were stirred with a star-head bar driven by a constant speed synchronous motor at 600 rpm. In the patch application study, the dermis side of the skin was attached to one-half of the side-by-side diffusion cells. The ISDN patch was applied to the SC side of the skin, and pH 7.4 PBS was used as the receptor medium. In both application studies 2.0 ml of receiver solution was withdrawn at predetermined intervals for measurement of the permeated drug, and fresh receptor medium was added to maintain a constant volume. The solution in the donor or receiver compartment was stirred with a star-head bar driven by a constant speed synchronous motor at 600 rpm.