Combinatorial screening

Apart from such process optimization issues, it may be desired to conduct combinatorial screening in micro channels. Here, specific micro-channel geometries for both liquid serial [110] and parallel [23] screening in organic chemistry have already been described. 

Warrington, B., Wong, S., The design of a continuous flow combinatorial screening micro-reactor system with on-chip detection, in van den Berg, A.,... 

The experimental results are in complete agreement with the predictions of our computational screening approach the annealed BiPt sample shows enhanced HER activity compared with pure Pt. As mentioned above, this result is rather counterintuitive, given that Bi itself is a notoriously poor electrocatalyst for the HER [Trasatti, 1972]. Hence, it appears that our computational, combinatorial screening procedure is capable of identifying improved catalysts for electrochemical reactions that are not immediately apparent from simple intuitive arguments. 

Harris RF, Nation AJ, Copeland GT, Miller SJ (2000) A polymeric and fluorescent gel for combinatorial screening of catalysts. J Am Chem Soc 122 11270-11271... 

Martin, L.J., Sculimbrene, B.R., Nitz, M., and Imperial/ B. (2005) Rapid combinatorial screening of peptide libraries for the selection of lanthanide-binding tags (LBTs). QSAR Combin. Sci. 24(10), 1149-1157. 

Nitz, M., Franz, K.J., Maglathlin, R.L., and Imperiali, B. (2003) A powerful combinatorial screen to identify high-affinity Terbium(III)-binding peptides. Chem. Bio. Chem. 4, 272-276. 

An ELSD converts the HPLC eluent into a particle stream and measures the scattered radiation. It offers universal detection for nonvolatile or semivolatile compounds and has higher sensitivity than the RI detector (in the low ng range) in addition to being compatible with gradient analysis. ELSD is routinely used in combinatorial screening. Response factors are less variable than that of other detectors. An ELSD consists of a nebulizer equipped with a constant temperature drift tube where a counter-current of heated air or nitrogen reduces the HPLC eluent into a fine stream of analyte particles. A laser or a polychromatic beam intersects the particle stream, and the scattered radiation is amplified by a photomultiplier. Manufacturers include Alltech, Polymer Laboratories, Shimadzu, Waters, Sedere, and ESA. 

CombiSep (Ames, lA) MCE 2000 Combinatorial screening amino acids pKa 96 capillaries, UV detector... 

The combinatorial screening experiment generated six distinct substrate sequences for FAR FTP, each of which contained at least two acidic residues in three variable positions. These results indicate that acidic residues on the N-termi-nal site of pY are important for binding and catalysis. 

L. Ma, X. Gong, E. S. Yeung Combinatorial screening of enzyme activity by using multiplexed capillary electrophoresis. Anal Chem 2000, 72, 3383-3387. 

Lucas LA, DeLongchamp DM, Vogel BM, Lin EK, Fasolka MJ, Fischer DA, McCulloch I, Heeney M, Jabbour GE (2007) Combinatorial screening of the effect of temperature on the micro structure and mobility of a high performance polythiophene semiconductor. Appl Phys Lett 90 012112... 

Lima, W.F., Brown-Driver, V., Fox, M., Hanecak, R. and Bruice, T. (1997) Combinatorial screening and rational optimization for hybridisation to folded Hepatitis C virus RNA of oligonucleotides with biological antisense activity J. Biol. Chem., 272, 626-638. 

Combinatorial screening, at first glance, might appear superficial as a number of identical experiments are executed under the same conditions in parallel fash-... 

Symyx, one of the pioneers in combinatorial screening, presented a chemical processing microsystem in 2000 for the screening of 256 catalysts on a silicon or quartz glass wafer [44]. The reactant flow was distributed by a microstructured manifold etched into a silicon wafer (see Bergh, Chapter 3). 

The diverse combinatorial screening described in the previous sections revealed active Pt-Ru-Co methanol oxidation catalysts, especially near Pt20Co6oRu2o. A second primary screening cycle (Fig. 11.8) focused on a more limited compositional space to isolate the active region in more detail. Figs. 11.15 and 11.16 show the design and the sampled compositional space of a Pt-Ru-Co ternary library. The design contains a pure Pt catalyst, Pt-Co binaries (row A), Pt-Ru binaries (column 1)... 

Combinatorial screening at first glance might appear superficial as a number of identical experiments are executed under the same conditions in a parallel fashion. This is certainly too simple an interpretation. As soon as fluid dynamic information is added to the pure experimental data, more complex aspects of catalysis are derivable from overall conversion data. This is a different approach to established screening methods, which normally concentrate purely on the experimental collection of data about the conversion or the selectivity of a certain catalyst. 

The rapid development of combinatorial screening methods has been accompanied by the development of ever more efficient high-throughput analysis technologies. These not only enable analysis of catalytic activity but also the determination of enantiomeric excess [2, 21]. Taking these developments together, research in this field can be expected to yield highly active and selective catalysts with structures that could have not been predicted by conventional means. 

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