Plate tests drawbacks

The sessile drop method has several drawbacks. Several days elapse between each displacement, and total test times exceeding one month are not uncommon. It can be difficult to determine that the interface has actually advanced across the face of the crystal. Displacement frequency and distance are variable and dependent upon the operator. Tests are conducted on pure mineral surfaces, usually quartz, which does not adequately model the heterogeneous rock surfaces in reservoirs. There is a need for a simple technique that gives reproducible data and can be used to characterize various mineral surfaces. The dynamic Wilhelmy plate technique has such a potential. This paper discusses the dynamic Wilhelmy plate apparatus used to study wetting properties of liquid/liquid/solid systems important to the oil industry. 

Another major drawback to this test is that a sensitive material must be energetic enough so that when a sample of 40 cc. is initiated it can blow a hole in a 3/8-inch steel plate mounted atop the sample container. This criteria for detonation is not useful in those cases of low order detonation where considerable energy would be released, but the test plate would indicate that no detonation had occurred. 

Unfortunately, both the fluorescence spectrometer and LSCM suffer from the same drawback, the inability to repeat measurements at the same position. The samples tested in this study were gradient compositions. The fluorescence spectrometer gathered spectra at a single point on the plate then the plate was moved to collect spectra at a different position of the plate, which had a different... 

In a similar approach, Burgess et al. investigated a C-H-insertion reaction with different metal-ligand combinations on microtiter plates [14]. By these means it was possible to test 96 catalyst systems at a time, indeed in single reactions, but still faster than by conventional methods. The uncertainty of the results due to the small scale of the experiments is a drawback of this screening procedure, as was (laudably) revealed by the authors themselves. Other approaches for screening catalysts in parallel have also been successful [15]. 

Each of these assays has drawbacks associated with them. The major obstacle for developing rapid screens for inhibitors of cytochrome c release from mitochondria is that enriched mitochondria have a finite time in which they can be used. We are in the process of testing mitochondria preparations to determine the stability of the mitochondria with respect to use in the cytochrome c release assay. Mitochondria stored on ice for 4 h (the longest time we have tested at the time of this writing) can be used in the cytochrome c release assay. Therefore, it is possible to run multiple assay cycles with one preparation of mitochondria. The short format cytochrome c release assay is not affected by cell permeability, makes no assumptions about the mechanism of action, does not use cultured cells, is targeted at the process to be inhibited (i.e., cytochrome c release from mitochondria), and is a colormetric assay easily monitored by spectrophotometric plate readers. This assay would, therefore, increase the chances of detecting lead compounds to be subsequently modified to increase potency, cell permeability, and pharmacological efficacy. 

Many concepts were developed to overcome one of the main drawbacks of the lead-acid system the heavy supporting lead structures (grids, connectors, etc.). Lead foam [89], lead-plated carbon rods [90], electroplated vitreous carbon [91], flexible-graphite grids [92], or graphite foams [93] were tested, also lead-plated materials like titanium [94], Ebonex [95], copper mesh [96], polymeric structures [97], polymer foam [98], or glass fiber mesh [99]. Warlimont and Hofmann [100] describe the development of multilayer composite grids. 

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