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Ions and membranes

Cardiotoxicity Assessment of human cardiotoxicity potential - human embryonic stem cell derived cardiomyocytes and ion and membrane potential dyes (also neurotoxicity, nephrotoxicity, myelotoxicity potential)... [Pg.341]

J.S. D Arrigo, Strontium ions and membranes screening versus binding at charges surfaces, in S.C. Skoryna (Ed.), Handbook of Stable Strontium, Plenum, New York, 1981, pp. 167-182. [Pg.274]

The environment for the phospholipid synthesizing enzymes plays a major role In their activity. By environment I refer to pH, Ion, and membrane lipid requirements. I previously have discussed the pH and Ion requirements. In particular the dichotomy of requirements for magnesium and manganese by the DAG and CDP-DAG pathways of phospholipid synthesis Calcium plays a role In exchange reactionsand has been described as... [Pg.269]

Most potentiometric electrodes are selective for only the free, uncomplexed analyte and do not respond to complexed forms of the analyte. Solution conditions, therefore, must be carefully controlled if the purpose of the analysis is to determine the analyte s total concentration. On the other hand, this selectivity provides a significant advantage over other quantitative methods of analysis when it is necessary to determine the concentration of free ions. For example, calcium is present in urine both as free Ca + ions and as protein-bound Ca + ions. If a urine sample is analyzed by atomic absorption spectroscopy, the signal is proportional to the total concentration of Ca +, since both free and bound calcium are atomized. Analysis with a Ca + ISE, however, gives a signal that is a function of only free Ca + ions since the protein-bound ions cannot interact with the electrode s membrane. [Pg.489]

The relative measurement error in concentration, therefore, is determined by the magnitude of the error in measuring the cell s potential and by the charge of the analyte. Representative values are shown in Table 11.7 for ions with charges of+1 and +2, at a temperature of 25 °C. Accuracies of 1-5% for monovalent ions and 2-10% for divalent ions are typical. Although equation 11.22 was developed for membrane electrodes, it also applies to metallic electrodes of the first and second kind when z is replaced by n. [Pg.495]

Potentiometric electrodes are divided into two classes metallic electrodes and membrane electrodes. The smaller of these classes are the metallic electrodes. Electrodes of the first kind respond to the concentration of their cation in solution thus the potential of an Ag wire is determined by the concentration of Ag+ in solution. When another species is present in solution and in equilibrium with the metal ion, then the electrode s potential will respond to the concentration of that ion. Eor example, an Ag wire in contact with a solution of Ck will respond to the concentration of Ck since the relative concentrations of Ag+ and Ck are fixed by the solubility product for AgCl. Such electrodes are called electrodes of the second kind. [Pg.532]

The preparation of an ion-selective electrode for salicylate is described. The electrode incorporates an ion-pair of crystal violet and salicylate in a PVC matrix as the ion-selective membrane. Its use for the determination of acetylsalicylic acid in aspirin tablets is described. A similar experiment is described by Creager, S. E. Lawrence, K. D. Tibbets, C. R. in An Easily Constructed Salicylate-Ion-Selective Electrode for Use in the Instructional Laboratory, /. Chem. Educ. 1995, 72, 274-276. [Pg.533]

Chloiine is pioduced at the anode in each of the three types of electrolytic cells. The cathodic reaction in diaphragm and membrane cells is the electrolysis of water to generate as indicated, whereas the cathodic reaction in mercury cells is the discharge of sodium ion, Na, to form dilute sodium amalgam. [Pg.482]

Separation of the anode and cathode products in diaphragm cells is achieved by using asbestos [1332-21 -4] or polymer-modified asbestos composite, or Polyramix deposited on a foraminous cathode. In membrane cells, on the other hand, an ion-exchange membrane is used as a separator. Anolyte—catholyte separation is realized in the diaphragm and membrane cells using separators and ion-exchange membranes, respectively. The mercury cells contain no diaphragm the mercury [7439-97-6] itself acts as a separator. [Pg.482]

Removal of brine contaminants accounts for a significant portion of overall chlor—alkali production cost, especially for the membrane process. Moreover, part or all of the depleted brine from mercury and membrane cells must first be dechlorinated to recover the dissolved chlorine and to prevent corrosion during further processing. In a typical membrane plant, HCl is added to Hberate chlorine, then a vacuum is appHed to recover it. A reducing agent such as sodium sulfite is added to remove the final traces because chlorine would adversely react with the ion-exchange resins used later in the process. Dechlorinated brine is then resaturated with soHd salt for further use. [Pg.502]

The vinyl ether in the latter part of the equation is copolymetized with tetrafluoroethylene, and then the sulfonyl fluoride group is hydrolyzed under basic conditions in order to produce the ion-exchange membrane (44—46). [Pg.316]

The porous electrodes in PEFCs are bonded to the surface of the ion-exchange membranes which are 0.12- to 0.25-mm thick by pressure and at a temperature usually between the glass-transition temperature and the thermal degradation temperature of the membrane. These conditions provide the necessary environment to produce an intimate contact between the electrocatalyst and the membrane surface. The early PEFCs contained Nafton membranes and about 4 mg/cm of Pt black in both the cathode and anode. Such electrode/membrane combinations, using the appropriate current coUectors and supporting stmcture in PEFCs and water electrolysis ceUs, are capable of operating at pressures up to 20.7 MPa (3000 psi), differential pressures up to 3.5 MPa (500 psi), and current densities of 2000 m A/cm. ... [Pg.578]

That is, hydrogen dissociates in the presence of the catalyst, forming hydrogen ions and giving up electrons to the anode. The hydrogen ions are transported across the membrane to the cathode. At the cathode, hydrogen ions react with oxygen to form H2O. [Pg.462]

Membranes and Osmosis. Membranes based on PEI can be used for the dehydration of organic solvents such as 2-propanol, methyl ethyl ketone, and toluene (451), and for concentrating seawater (452—454). On exposure to ultrasound waves, aqueous PEI salt solutions and brominated poly(2,6-dimethylphenylene oxide) form stable emulsions from which it is possible to cast membranes in which submicrometer capsules of the salt solution ate embedded (455). The rate of release of the salt solution can be altered by surface—active substances. In membranes, PEI can act as a proton source in the generation of a photocurrent (456). The formation of a PEI coating on ion-exchange membranes modifies the transport properties and results in permanent selectivity of the membrane (457). The electrochemical testing of salts (458) is another possible appHcation of PEI. [Pg.14]


See other pages where Ions and membranes is mentioned: [Pg.29]    [Pg.377]    [Pg.142]    [Pg.212]    [Pg.391]    [Pg.299]    [Pg.29]    [Pg.377]    [Pg.142]    [Pg.212]    [Pg.391]    [Pg.299]    [Pg.131]    [Pg.397]    [Pg.1109]    [Pg.1284]    [Pg.493]    [Pg.532]    [Pg.541]    [Pg.575]    [Pg.200]    [Pg.493]    [Pg.493]    [Pg.494]    [Pg.499]    [Pg.499]    [Pg.500]    [Pg.349]    [Pg.316]    [Pg.578]    [Pg.579]    [Pg.585]    [Pg.586]    [Pg.150]    [Pg.477]    [Pg.75]    [Pg.61]    [Pg.391]    [Pg.102]    [Pg.163]    [Pg.252]   
See also in sourсe #XX -- [ Pg.2 ]




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