Mini-cell

Fundamentally, the eel is simply a living battery. The tips of its head and tail represent the poles of the eel s battery . As much as 80 per cent of its body is an electric organ, made up of many thousands of small platelets, which are alternately super-abundant in potassium or sodium ions, in a similar manner to the potentials formed across axon membranes in nerve cells (see p. 339). In effect, the voltage comprises thousands of concentration cells, each cell contributing a potential of about 160 mV. It is probable that the overall eel potential is augmented with junction potentials between the mini-cells. 

Gel electrophoresis (XcellSurelock Mini-Cell with NuPage gel, 10% Bis-Tris, Invitrogen, Carlsbad, California). 

The monoclonal antibodies (MAh) are purified by protein A-affinity chromatography from culture media or bioreactor fiuid (20). Purity of the monoclonal antibody is assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (XcellSurelock Mini-Cell with NuPage gel, 10% Bis-Tris, Invitrogen, Carlsbad, California). 

Summary. We describe the design, constroction, and operation of two types of nuclear magnetic resonance (NMR) sample probes for use in electrocatalysis/surface NMR studies. The first is an electrochemical NMR cell, which permits observation of NMR signals of surface-adsorbed species under external potential control. This cell also permits conventional voltammograms to be recorded fi-om the actual NMR sample. The second or mini-cell has a long, thin sample region and better sensitivity than the electrochemical NMR cell, but is not capable of voltammetry. Spectra have been obtained for CO, CN and adsorbed on polycrystalline platinum black, as a fimction of applied potential, demonstrating the feasibility of multinuclear NMR studies at electrified interfaces. 

The second type of cell we have used for our studies of species adsorbed onto platinum black is the mini-cell (Fig. 2) [9]. 

Fig. 2. A. Diagram of the mim-cell. A, Sample chamber B, electrolyte reservoir C, ports for coimter and reference electrodes D, platinum wire for contact with the platinum black sample. (B) Mini-cell probehead set for NMR data acquisition.

Both the electrochemical NMR cell and the mini-cell require a custom-built probe (Fig. 

A typical spectrum of CO derived from the decomposition of C-enriched methanol on PC platinum black is shown in Fig. 5(A). Fig. 5(B) shows the first electrochemical cycle after methanol decomposition, followed by rinsing, without circuit interruption. The voltammogram is used to determine surface coverage from the CO CO2 oxidation peak at around 400 mV (versus a Ag/AgCl reference electrode, in 1.0 M NaCl). Typical mini-cell NMR spectra for C- and -labeled CN" on Pt black are shown in Fig. 6. 

Fig. 6. (A) A spectrum of CN-Pt black in the mini-cell, 3000 transients, S/N ratio = 36.2 1.

XCeU SureLock Mini-Cell apparatus and power supply 96% Ethanol... 

The Wilks Mini-Cell liquid sample holder is available from the Foxboro Company, 151 Woodward Avenue, South Norwalk, CT 06856. We recommend the AgCI cell windows with 0.10-mm depression rather than the 0.025-mm depression. 

Fig. 11-3. Mini-prep continuous elution electrophoretic cell.

Fig. 11-4. UV trace of piperoxan enantiomers eluting from mini-prep electrophoresis cell.

Phase Type in Struk-turbericht Character Atoms per unit cell (mini mum) 0 B2 and Z,20 body- centered cubic 2 /3-Mn A13 complex cubic 20 7 D81, 82, 83 84 complex cubic 52 e hexagonal close packed, c/a <(8/3) 2 ... 

Accordingly, serious commercially oriented attempts are currently being made to develop special gas-phase micro and mini reactors for reformer technology [91, 247-259], This is a complex task since the reaction step itself, hydrogen formation, covers several individual processes. Additionally, heat exchangers are required to optimize the energy balance and the use of liquid reactants demands micro evaporators [254, 260, 261], Moreover, further systems are required to reduce the CO content to a level that is no longer poisonous for a fuel cell. Overall, three to six micro-reactor components are typically needed to construct a complete, ready-to-use micro-reformer system. 

Such bimetallic alloys display higher tolerance to the presence of methanol, as shown in Fig. 11.12, where Pt-Cr/C is compared with Pt/C. However, an increase in alcohol concentration leads to a decrease in the tolerance of the catalyst [Koffi et al., 2005 Coutanceau et ah, 2006]. Low power densities are currently obtained in DMFCs working at low temperature [Hogarth and Ralph, 2002] because it is difficult to activate the oxidation reaction of the alcohol and the reduction reaction of molecular oxygen at room temperature. To counterbalance the loss of performance of the cell due to low reaction rates, the membrane thickness can be reduced in order to increase its conductance [Shen et al., 2004]. As a result, methanol crossover is strongly increased. This could be detrimental to the fuel cell s electrical performance, as methanol acts as a poison for conventional Pt-based catalysts present in fuel cell cathodes, especially in the case of mini or micro fuel cell applications, where high methanol concentrations are required (5-10 M). 

The collected sample at -196°C was isolated from the flow of the GC s helium gas stream and then the loop was warmed to ambient temperature for GC-mass spectroscopic analyses. The gas cell, which contained the isotopic CO2 and the C2Hg standard in helium at one atmosphere, was placed in the injection helium flow of the GC-mass spectrometer for ten minutes, before the mini-switching valve was turned to inject the vapor contents into the instrument. After three minutes, the CO2 peak eluted. The superimposed peaks were sampled ten times during their elution and the relative isotopic quantities of - C02 C02 and C02 were determined. 

The deposition of CBD CdS as a junction layer for solar cell devices has proven to be a very successful industrially acceptable technique. Kessler et al.13 reported on copper indium gallium diselenide (CIGS) mini-modules (area = 16cm2) with a conversion efficiency of 16.6%, wherein CBD CdS was used as a junction layer. Basol et al.14 fabricated 9.3% active-area efficient thin-film flexible CuInSe2 (CIS) solar cells (specific power >1 kW/kg) on lightweight, flexible metallic, and polymeric (polymide-based) substrates using CBD CdS. 

Kessler, J. Wennerberg, J. Bodegard, M. Stolt, L. 2003. Highly efficient Cu(In,Ga)Se2 mini-modules. Sol. Energy Mater. Solar Cells 75 35-46. 

Figure 8.1 Exploded view of an electrophoresis cell. The components of the Bio-Rad Mini-PROTEAN 3 are shown. The inner chamber can hold one or two gels. It contains an electrode assembly and a clamping frame. The interior of the inner assembly constitutes the upper buffer compartment (usually the cathode compartment). The chamber is placed in the tank to which buffer is added. This constitutes the lower (anode) buffer compartment. Electrical contact is made through the lid.

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