Ultrathin cells

Two new technologies have reduced the cost of alkali fuel cells to the point where a European company markets taxis that use them. One is the use of CO2 scrubbers to purify the air supply, making it possible to use atmospheric O2 rather than purified oxygen. The other is the development of ultrathin films of platinum so that a tiny mass of this expensive metal can provide the catalytic surface area needed for efficient fuel-cell operation. 

Figure 14.7 (a) A schematic diagram of the experimental set-up for the generation of an ultrathin electrolyte film and for electrodeposition. The cell for electrodeposition shown here has two parallel electrodes. 

The CLM method is a new technique, developed by Nagatani and Watarai [61]. This method produces a stable, ultrathin two-phase liquid membrane by the centrifugal force due to the rotation of a cylindrical cell, using the arrangement shown in Fig. 11. The inner diameter and inner height of the cylindrical cell were 19 and 29 mm, respectively. The rotation speed was controlled in the range 6000-7500 rpm. The summation of the absorption spectra of both interfacial and bulk organic phase species was measured in the direction perpendicular to the rotation axis with a diode array spectrophotometer. 

Nielsen, M.H., Bastholm, L., Chatterjee, S., Koga, J., and Norrild, B. (1989) Simultaneous triple-immunogold staining of virus and host cell antigens with monoclonal antibodies of virus and host cell antigens in ultrathin cryosections. Elistochemistry 92, 89-93. 

Frey B, Brunner I, Walther P, Scheidegger C, Zierold K. Element localization in ultrathin cryosections of high-pressure frozen ectomycorrhizal spruce roots. Plant Cell Environ 1997 20 929-937. 

Geuze H, Slot J, Van Der Ley P, Scheffer R. Use of colloidal gold particles in doublelabeling immunoelectron microscopy of ultrathin frozen tissue sections. J Cell Biol 1981 89 653-665. 

Cha, S. Y., and Lee, W. M. Performance of proton exchange membrane fuel cell electrodes prepared by direct deposition of ultrathin platinum on the membrane surface. Journal of the Electrochemical Society 1999 146 4055 060. 

The total swelling time for a dried SPH in aqueous solution is determined by two factors q and t2- h is the time for water to reach all the surface of the pores in the SPHs. It is determined by the effectiveness of the capillary action in a SPH. 2 is the actual swelling time of the polymer matrix, which is determined by the thickness of the cell walls and struts. Because the cell walls and stints of SPHs are very thin, they have very short characteristic swelling times. For SPHs, t2 is comparable to that of a ultrathin hydrogel film. The capillary action is mainly determined by the availability of capillary channels and the wettability of the channels. Various approaches have been attempted to maintain good capillary action (i.e., to decrease q) by maintaining open intercellular channels and good surface wettability. 

These bands were a matter of discussion for a long time until in 1954, for the first time, Sjostrand and Andersson used electron microscopy to investigate intercalated disks in ultrathin osmium tetroxide-fixed sections of the mouse heart revealing that the disks were indeed transverse cell boundaries. Subsequently, several investigators reproduced their finding [Lindner, 1957 Moore... 

More recently, TiCVCuSCN heterostructures have been used in multilayer solid-state cells characterized by a broader spectral response. It has been shown that the electron injection from a photoexcited dye can occur through ultrathin layers... 

In general, details of cell structure in vitrinite are distinguished only with great difficulty in ultrathin sections in the electron microscope, probably because of insufficient contrast between cell parts. If cell spaces are filled with another component the cellular structure becomes evident. 

Prismatic 9 V three-cell batteries, and 6 V two-cell ultrathin batteries are also manufactured. The former is designed as a high capacity replacement for aqueous zinc primaries and the latter for smart cards. 

Mitochondria are present in all eukaryotic cells that use oxygen in respiration, but the number per cell and the form and size vary.1-4 Certain tiny trypanosomes have just one mitochondrion but some oocytes have as many as 3 x 105. Mammalian cells typically contain several hundred mitochondria and liver cells5 more than 1000. Mammalian sperm cells may contain 50-75 mitochondria,6 but in some organisms only one very large helical mitochondrion, formed by the fusion of many individual mitochondria, wraps around the base of the tail. Typical mitochondria appear to be about the size of cells of E. coli. However, study of ultrathin serial sections of a single yeast cell by electron microscopy has shown that, under some growth conditions, all of the mitochondria are interconnected.7... 

Ribosomes were discovered by electron micros-copists examining the structure of the endoplasmic reticulum using ultrathin sectioning techniques. Their presence in cells was established by 1956, and the name ribosome was proposed in 1957. At first it was difficult to study protein synthesis in vitro using isolated ribosomes. No net synthesis could be detected until Hoagland and associates measured the rate of incorporation of 14C-labeled amino acids into protein.26 This sensitive method permitted measurement of very small amounts of protein synthesis in cell-free preparations from rat liver and paved the way toward studies with ribosomes themselves. 

After glutaraldehyde fixation (Section 3.1 1 2., step 8), fix the cells further with 1% osmium tetroxide, saturated uranyl acetate, dehydrate in an ascending series of ethanol (70, 90, 100%), and embed in epoxy resin. Ultrathin sections of the block, stained with 1% methanolic uranyl acetate and lead citrate, will reveal immunolabeling on the outer surface of the cells... 

Fig. 5.3 Immunogold labeling of human A i ARs on ultrathin sections of transfected CHO cells, (a) Small aggregates of gold particles (arrow) on the plasma membrane after a 60-min incubation with 10 nM agonist NECA at 4°C. (b) After a 15-min incubation with agonist at 37°C A3 ARs are visible in uncoated vesicle at level of the cortical cytoplasm (Trincavelli et al. 2000)...

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