Applications frontal

Radial-Inflow Turbine The radial-inflow turbine, or inward-flow radial turbine, has been in use for many years. Basically a centrifugal compressor with reversed-flow and opposite rotation, the inward-flow radial turbine is used for smaller loads and over a smaller operational range than the axial turbine. Radial-inflow turbines are only now beginning to be used because little was know about them heretofore. Axial turbines have enjoyed tremendous interest due to their low frontal area, making them suited to the aircraft industiy. However, the axial machine is much longer than the radial machine, making it unsuited for certain vehicular and helicopter applications. Radial turbines are used in turbochargers and in some types of expanders. 

The complex distribution system that results from the frontal analysis of a multicomponent solvent mixture on a thin layer plate makes the theoretical treatment of the TLC process exceedingly difficult. Although specific expressions for the important parameters can be obtained for a simple, particular, application, a general set of expressions that can help with all types of TLC analyses has not yet been developed. One advantage of the frontal analysis of the solvent, however, is to produce a concentration effect that improves the overall sensitivity of the technique. 

FTND Fagerstrom test for nicotine dependence, M mean NR not reported NA not applicable ACC anterior cingulate cortex PCC posterior cingulate cortex OFC orbitofrontal cortex SFG superior frontal gyrus DLPFC dorsal lateral prefrontal cortex DRD4L dopamine receptor 4 variable number tandem repeat Data shown for FTND and pack-years are means for the smokers Pack-years = packs of cigarettes smoked per day x number of years smoked... 

Kasai, K Oligosaccharide specificity of galectins a search by frontal affinity chromatography. Biochim Biophys Acta 2002, 1572, 232-254. Hirabayashi, J., Arata, Y, Kasai, K. Glycome project concept, strategy and preliminary application to Caenorhabditis elegans. Proteomics 2001, 1, 295-303. 

P. J., Kelly, M. A., Schriemer, D. C. Frontal affinity chromatography-mass spectrometry assay technology for multiple stages of drug discovery applications of a chromatographic... 

J. D. Protein-doped monolithic silica columns for capillary liquid chromatography prepared by the sol-gel method applications to frontal affinity chromatography. Anal Chem... 

Pasternak, A., Reid, N. Global kinase screening. Applications of frontal affinity chromatography coupled to... 

Fig. 6 Simulation of concentration distribution in frontal analysis capillary lenth 50 cm injection length 12.5 cm, corresponding 245 nL at 50-/j,m i.d. of capillary association constant 5000 M 1 initial concentration substrate 0.11 mM, ligand 0.1 mM mobility of substrate 10, of complex 40, of ligand 40 X 10-5 cm2V 1 B is 50 seconds after application of 25 kV.

A Shibukawa. Development of high-performance frontal analysis and application to drug-plasma protein binding study. Yakugaku Zasshi 118 554-565, 1998 (in Japanese). 

Kraak et al. (38) reported the first ACE application to study drug binding to a plasma protein. They used the model system warfarin-human serum albumin (HSA) to compare the suitability of the Hummel-Dreyer, frontal analysis, and vacancy peak methods. A more methodologically intended paper from Erim and Kraak (39) used VACE to study the displacement of warfarin from bovine serum albumin (BSA) by furosemide and phenylbutazone. They concluded that VACE is especially suited to examining competitive properties of simultaneously administered compounds toward a given protein-drug system. 

Shibukawa et al. (40) discussed the frontal analysis method, also called high-performance frontal analysis (HPFA) or high-performance capillary electrophoresis/frontal analysis (HPCE/FA), compared it to conventional methods, and focused on the application to stereoselective protein binding. The affinity of the drugs warfarin, verapamil, and carbamazepine and the drug candidate BOF-4272 to HSA was investigated. 

SUMMARY. The frontal technique does not lend itself to many analytical applications because of the overlap of the bands and the requirement of a large amount of sample. However, it may be used to study phase equilibria (isotherms) and for preparative separations. (Many of the industrial chromatographic techniques use frontal analysis.) Displacement development has applications for analytical LC (e.g. it may be used as an initial concentrating step in GC for trace analysis). This technique may also be used in preparative work. The outstanding disadvantage of both of these techniques is that the column still contains sample at the conclusion of the separation. Thus, regeneration of the column is necessary before it can be used again. 

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