Design of the Apparatuses

Further improvements in the design of the apparatus and optimization of the deposition conditions are expected to remove the remaining discrepancies. 

The hydrogen pressure and the design of the apparatus are not critical any apparatus in common use is satisfactory. The checkers used an apparatus having a magnetically stirred reaction flask as described by Wiberg.3... 

Each data point should be carried out in at least triplicate. This allows for a maximum of 16 data points per chemotaxis chamber (48 wells in total). The design of the apparatus ensures that there is little cross-contamination between wells. In addition, the wells are arranged to ensure that it is easy to orientate the filter and identify individual wells. 

The distinguishing characteristic of each reported study is, usually, the physical design of the apparatus involved. In Table I, a brief outline of the published information on power requirements in one-liquid-phase systems is presented. This table gives the significant mechanical characteristics of the systems studied the range of liquid viscosities and the range of values for the impeller Reynolds number, which will be discussed below. In most of these studies the general objective was to relate the power consumption to tank diameter, impeller type and diameter, rotational speed, and liquid properties. Other variables studied are also indicated in the table. The major features of this work will now be reviewed. 

In new laboratory planetary mills, the jars rotate due to frictional clutch with the cylindrical housing of the mill. A scheme and the design of the apparatus are shown in Fig. 4.1 [5]. The apparatus consists of the housing 1, carrier 2, jars 3, guiding rim 4, sheave 5, channels in the center and at the periphery of the carrier for cooling water. The diameter of the jars is 70 mm, the working volume is 150 cm, ball mass is 200 g, the mass of the substance under treatment is 10 g. 

The toxicity and odor of the solvent warrant consideration. Proper design of the apparatus and careful handling of the solvent make these properties less objectionable. 

Direct elution techniques involve the collection of the eluate by a continuous stream of buffer, which is then fed to a fraction collector, by way of an ultraviolet monitor if desired. Some examples of successful applications will be given in ch. 9. In principle this type of technique can be scaled up considerably, to the milligram level, but great care in the design of the apparatus is required if the separations are not to be vitiated by heating in the thick gels that are used, and if there is not to be distortion of the zones. Some loss of resolution, as we have remarked, appears inescapable. 

Shinomiya, K. Menet, J.-M. Fales, H.M. Ito, Y. Studies on a new cross-axis coil planet centrifuge for performing counter-current chromatography. I. Design of the apparatus, retention of the stationary phase, and efficiency in the separation of proteins with polymer phase systems. J. Chromatogr. 1993, 644, 215. 

Ito, Y. Oka, H. Slemp, J.L. Improved high-speed counter-current chromatograph with three multilayer coils connected in series. I. Design of the apparatus and performance of semipreparative columns in DNP amino acid separation. J. Chromatogr. 1989, 475, 219-227. 

Ito, Y. Kitazume, E. Bhatnagar, M. Trimble, F. Crossaxis synchronous flow-through coil planet centrifuge (Type XLL). I. Design of the apparatus and studies on retention of stationary phase. J. Chromatogr. 1991, 538, 59. 

The time required for complete extraction varies from twenty-four to fifty hours. It depends on the design of the apparatus and the rate of distillation of the ether. The extraction can be followed by observing the decrease in volume of the aqueous layer containing the glycol. The extraction is complete when the evaporation of a small amount of the supernatant ether on a watch glass leaves no residue. Benzene may be substituted for ether in the extraction step. 

The T-junction, depicted in Fig. 4, is one of the most common geometries used in microfluidic chips to create discrete segments of immiscible fluids. The design of the apparatus is extremely simple - a main, straight channel, that carries the continuous fluid is joined from the side, usually at a right angle, by a channel that supplies the fluid-to-be-dispersed. 

When the density of the sample varies with hydrogen uptake, Eq. (7.14) makes it clear that, because the measured value scales with sample mass and volume in the same way, nothing can be done with the design of the apparatus to lessen the effect of the changing sample density. The only recourse is to independent measurements by diffraction, for instance, or to the very detailed interpretation of a suite of data on a hopefully realistic physical model, such as that of Dreisbach et al. (2002). Independent measurements may be the only way to reliably know that the sample density is not constant anyway. It seems likely that there are published studies in which this effect has led to the wrong interpretation of the results. 

Sometimes the operator s proximity to the adjustment knobs will affect the tuning condition. This condition should have been avoided in the design of the apparatus. An unsightly but quick-and-sure fix is to extend the adjustment shaft with an Insulator. Standard diameter shafts, e.g., 0.125" and 0.250" diameter, can be extended with plastic shafts of the same diameter using commercial shaft couplers. Insulated shafts can also be adapted for various screwdrivers and similar tuning tools, either commercial or homemade. We have seen insulated shaft extensions as long as one meter, which attests to the practicality of some NMR people. 

A considerable potential difference (i.e. voltage) must be applied to the gas before any current can be detected. The exact value of the minimum voltage depends on the gas used and on the design of the apparatus. 

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