Cell pair

Commercial membranes have typical thicknesses of ca 0.15—0.5 mm the compartments between the membranes have typical thicknesses of ca 0.5—2 mm. The thickness of a cell pair is therefore in the 1.3—5.0 mm range, commonly about 3.0 mm. One hundred cell pairs have a combined thickness of about 300 mm. The effective area of a cell pair for current conduction is generally on the order of 0.2—2 m. ... 

The power consumption W may be estimated from where R the electrical resistance of a cell pair per unit area (n-cm ), is given by ... 

Process Configuration Figure 22-56 shows a basic cell pair. A stack is an assembly of many cell pairs, electrodes, gaskets, ana manifolds needed to supply them. An exploded schematic of a portion of a sheet-flow stack is shown in Fig. 22-60. 

The membranes are supported and kept apart by feed spacers. A typical cell gap is 0.5-2 mm. The spacer also helps control solution distribution and enhances mass transfer to the membrane. Given that an industrial stack may have up to 500 cell pairs, assuring uniform flow distribution is a major design requirement. 

Figure 21.2a shows a sample/reference half-cell pair for measurement of the standard reduction potential of the acetaldehyde/ethanol couple. Because electrons flow toward the reference half-cell and away from the sample half-cell, the standard reduction potential is negative, specifically —0.197 V. In contrast, the fumarate/succinate couple and the Fe /Fe couple both cause electrons to flow from the reference half-cell to the sample half-cell that is, reduction occurs spontaneously in each system, and the reduction potentials of both are thus positive. The standard reduction potential for the Fe /Fe half-cell is much larger than that for the fumarate/ succinate half-cell, with values of + 0.771 V and +0.031 V, respectively. For each half-cell, a half-cell reaction describes the reaction taking place. For the fumarate/succinate half-cell coupled to a H Hg reference half-cell, the reaction occurring is indeed a reduction of fumarate. 

Cell-pair, in ED technology Cementite Cenospheres Centrifugal pumps Ceramic membranes Cerium... 

The cell construction provides (i) a uniform internal distribution of up to four separate electrolytes, (ii) cooling and heating facilities (useful temperature range ca. - 40 °C up to -I- 250 °C), (iii) gas supply, and (iv) different turbulent promotors to improve transport performances. The versatility of off-the-shelf cells, paired with increasing experience of integrating electrolytic cells into industrial processes thus reduces the obstacles and risks for the scale-up. Furthermore, electrochemical units lend themselves well to modular construction, thus CPI plant expansion is a chance for this new technique. 

MObius HJ, StOffler A (2002) New approaches to clinical trials in vascular dementia memantine in small vessel disease. Cerebrovasc Dis 13 (Suppl 2) 61-66 Montgomery JM, Madison DV (2002) State-dependent heterogeneity in synaptic depression between pyramidal cell pairs. Neuron 33 765-777 Montgomery JM, Pavlidis P, Madison DV (2001) Pair recordings reveal all-silent synaptic connections and the postsynaptic expression of long-term potentiation. Neuron 29 691-701... 

The third channel found in heart muscle is the Cx45 channel. This was reported to exhibit an overall conductance of 3.1 +0.4 nS in cell pairs [Kwak et al., 1995a] with a mean single-channel conductance of 36.5+ 6.5 pS or... 

Similarly, De Mello [1989] reported on an improvement in intercellular coupling by the P-adrenoceptor agonist isoproterenol in cardiac cell pairs. Thus, stimulation of P-adrenoceptors can be assumed to result in enhancement of intercellular coupling, at least in some preparations. However, on the basis of the hndings of Kwak and Jongsma [1996] on a lack of the effect of PKA to alter gap junction conductance in rat cardiomyocytes, caution seems necessary and species variability or tissue variability seems to play an important role. 

In addition to the modulators of the autonomic nervous system, angiotensin II was found to be effective in regulating cardiac gap junction conductance. In adult ventricular cell pairs De Mello [1992] observed a 55% reduction in gap junction conductance gj within 20 s following the administration of... 

Cultured embryonic chick heart cells often form coupled cell pairs or aggregates which may be studied using the double-cell voltage-clamp technique. In the following an isolation and culture protocol is given as used in the author s laboratory. Besides this, other protocols may also suit. 

Following these steps, the solution is centrifuged a last time for 1 min at 600 rpm and the resulting pellet is either resuspended in 20 ml solution (with additional Ca2+) or in Tyrode solution, if the cells are to be used immediately for an experiment, or the pellet is dissolved in solution E for cultivating the cells. For this purpose 2 ml of the cell-containing solution are dissolved with 5 ml solution E in Petri dishes (3 cm diameter) and kept in the incubator for a maximum of 3 days. However, it should be noted that the content of cell pairs gradually declines with time and is maximum shortly after isolation. 

De Mello WC Effect of isoproterenol and 3-isobutyl-1-methylxanthine on the junctional conductance in heart cell pairs. Biochim Biophys Acta 1989 1012 291-298. 

Maurer P, Weingart R Cell pairs isolated from guiea pig and rat hearts Effects of [Ca2+ on nexal membrane resistance. Pfliigers Arch 1987 409 394 102. 

Rudisuli A, Weingart R Electrical properties of gap junction channels in guinea pig ventricular cell pairs revealed by exposure to heptanol. Pflugers Arch 1989 415 12. 

Veenstra RD Voltage dependent gating of gap junction channels in embryonic chick ventricular cell pairs. Am J Physiol 1990 258 C662-C672. 

Weingart R Electrical properties of the nexal membrane studied in rat ventricular cell pairs. J Physiol (Lond) 1986 370 267-284. 

Weingart R, Maurer P Cell-to-cell coupling studied in isolated ventricular cell pairs. Experientia 1987 43 1091-1094. 

Weingart R, Maurer P Action potential transfer in cell pairs isolated from adult rat and guinea pig ventricles. Circ Res 1988 63 72-80. 

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