Sandwich configuration

Pandey et al. [183] employed this idea of a sandwich configuration to transfer substances from one TLC plate to another for two- or multidimensional separations. 

Valepotriates are detected by placing the chromatogram 0.3 mm from a TLC plate sprayed with cone, ammonia solution (sandwich configuration layer to layer), fastening with clips and heating to 110°C in a drying cupboard for 10 min [12]. 

Related to the linear development chamber is the Vario-KS chamber [8,195]. The plate is also developed in the horizontal position in a sandwich configuration. However, this chamber is... 

Mainly, three approaches have been used to immobilize the enzyme on transducer or electrode surface, single layer, bilayer, and sandwich configurations [69, 98], In some studies enzymes are covalently linked with sol-gel thin films [99], Sol-gel thin films are highly convenient for fast, large, and homogeneous electron transfer [17]. With an increase in gel thickness the signal decays and diffusion of analytes to biomolecule active site becomes difficult eventually these factors lead to poor response. By employing thin films various biosensors such as optical and electrochemical biosensors have been reported. 

Chandross and Ferguson64 find that the absorption spectra of dimers, produced65 by photolytic cleavage of photodimers of anthracene and mono-derivatives in a rigid methylcyclohexane glass at 77°K, are consistent with a symmetrical sandwich configuration these dimers also emit the characteristic excimer fluorescence. On the other hand, it is necessary to assume a 60° rotation of one component about the intermolecular axis of the 9,10-di-chloroanthracene dimer (as in the crystalline compound) to account for the observed resonance splittings of both absorption bands.64... 

Under normal conditions the catacondensed hydrocarbons of molecular formula C4n+2H2n+4 adopt a crystal lattice104 shown schematically as Type A in Figure 13 in which the (rotational and translational) displacement of adjacent molecular planes to produce a symmetric sandwich configuration is prohibited by the interaction of neighboring molecules. These crystals exhibit a structured ( molecular ) fluorescence spectrum red-shifted by 100 cm-1 from the molecular spectrum observed in dilute solutions. 

Thorgeirsson, S.S., Hepatic stem cells in liver regeneration. FASEB J. 10,1249,1996. Dunn, J., Tompkins, R., and Yarmush, M. Long term in vitro function of adult hepatocytes in a collagen sandwich configuration Biotechnol. Prog. 7.237,1991. Allen, J., Hassanien, T, and Bhatia, S. Advances in bioai tificial liver devices, Hepatology 34,447, 2001. 

The system considered above has been extended to a multilayered metal/expl open-faced sandwich (Ref 21). Here the effects of rarefactions at the metal/air boundary have to be considered since they lead to separation of the metal layers. According to Jones (Ref 21) the velocity of the innermost layer of the open-faced sandwich configuration of N layers is given by ... 

LeCluyse EL, Audus KL, Hochman JH. Formation of extensive canalicular networks by rat hepatocytes cultured in collagen-sandwich configuration. Am J Physiol 1994 266 0764-0774. 

Dunn JC, Yarmush ML, Kowbe HG, et al. Hepatocyte function and extracellular matrix geometry long-term culture in a sandwich configuration. FASEB J 1989 3 174-177. 

Fig. 13.18. Sandwich configuration of phosphoric acid fuel cells developed by United Technologies. (Reprinted from J. O M. Bock-ris and S. Srinivasan, Fuel Cells, p. 179, copyright 1993, McGraw-Hill. Reproduced with permission of The McGraw-Hill Companies.)...

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