1“ MIP

The procedure is computationally efficient. For example, for the catalytic subunit of the mammalian cAMP-dependent protein kinase and its inhibitor, with 370 residues and 131 titratable groups, an entire calculation requires 10 hours on an SGI 02 workstation with a 175 MHz MIPS RIOOOO processor. The bulk of the computer time is spent on the FDPB calculations. The speed of the procedure is important, because it makes it possible to collect results on many systems and with many different sets of parameters in a reasonable amount of time. Thus, improvements to the method can be made based on a broad sampling of systems. 

Vendors such as SUN and MIPS introduced lines of computers based on RISC (reduced iastmction set computer) chips. These computers offered significant performance advantages over the CISC (complex iastmction set computer) minicomputers, at least for CPU-bound work. Although there are stiU active debates about what RISC and what CISC are, the essence of RISC is simplicity. 

The RISC versus CISC conundmm has led to the much abused and ultimately extremely confusiag term MIPS (millions of iastmctions per second). Measures of performance that can be more directiy related to a computer s abiUty to perform usehil work should always be preferred over machine MIPS. The throughput of a computer is a function of the number of iastmctions to be executed, the average number of iastmctions that can be executed per clock cycle, and the time per clock cycle. 

The development of highly selective chemical sensors for complex matrixes of medical, environmental, and industrial interest has been the object of greate research efforts in the last years. Recently, the use of artificial materials - molecularly imprinted polymers (MIPs) - with high recognition properties has been proposed for designing biomimetic sensors, but only a few sensor applications of MIPs based on electrosynythesized conductive polymers (MIEPs) have been reported [1-3]. 

The intrinsic drawback of LIBS is a short duration (less than a few hundreds microseconds) and strongly non-stationary conditions of a laser plume. Much higher sensitivity has been realized by transport of the ablated material into secondary atomic reservoirs such as a microwave-induced plasma (MIP) or an inductively coupled plasma (ICP). Owing to the much longer residence time of ablated atoms and ions in a stationary MIP (typically several ms compared with at most a hundred microseconds in a laser plume) and because of additional excitation of the radiating upper levels in the low pressure plasma, the line intensities of atoms and ions are greatly enhanced. Because of these factors the DLs of LA-MIP have been improved by one to two orders of magnitude compared with LIBS. 

The analytical capabilities of LIBS and LA-MIP-OES were recently noticeably improved by use of an advanced detection scheme based on an Echelle spectrometer combined with a high-sensitivity ICCD (intensified charge-coupled device) detector. 

Methyl-l-methoxyethyl Ether (MIP-OR) ROC(OCH3)(CH3)2 (Chart 1) Formation... 

In general, the MIP ether is very labile to acid and silica gel chromatography, unless some TFA is used as part of the eluting solvent. The acid in the NMR solvent, CDCI3, is sufficient to cleave the MIP ether. 

Recently, molecularly imprinted polymers (MIPs) have gained attention as new, selective sorbents for chromatography and SPE. The cavities in the polymer... 

Recently, an in-depth review on molecular imprinted membranes has been published by Piletsky et al. [4]. Four preparation strategies for MIP membranes can be distinguished (i) in-situ polymerization by bulk crosslinking (ii) preparation by dry phase inversion with a casting/solvent evaporation process [45-51] (iii) preparation by wet phase inversion with a casting/immersion precipitation [52-54] and (iv) surface imprinting. 

Fig. 5-5. Schematic representation of the preparation procedure of molecular imprinted polymers (MIP).

Fig. 5-6. Chiral separation by MIP membranes a combination of sieving and selective transport [44],...

Several selective interactions by MIP membrane systems have been reported. For example, an L-phenylalanine imprinted membrane prepared by in-situ crosslinking polymerization showed different fluxes for various amino acids [44]. Yoshikawa et al. [51] have prepared molecular imprinted membranes from a membrane material which bears a tetrapeptide residue (DIDE resin (7)), using the dry phase inversion procedure. It was found that a membrane which contains an oligopeptide residue from an L-amino acid and is imprinted with an L-amino acid derivative, recognizes the L-isomer in preference to the corresponding D-isomer, and vice versa. Exceptional difference in sorption selectivity between theophylline and caffeine was observed for poly(acrylonitrile-co-acrylic acid) blend membranes prepared by the wet phase inversion technique [53]. 

Possible applications of MIP membranes are in the field of sensor systems and separation technology. With respect to MIP membrane-based sensors, selective ligand binding to the membrane or selective permeation through the membrane can be used for the generation of a specific signal. Practical chiral separation by MIP membranes still faces reproducibility problems in the preparation methods, as well as mass transfer limitations inside the membrane. To overcome mass transfer limitations, MIP nanoparticles embedded in liquid membranes could be an alternative approach to develop chiral membrane separation by molecular imprinting [44]. 

Molecularly imprinted polymers (MIPs) can be prepared according to a number of approaches that are different in the way the template is linked to the functional monomer and subsequently to the polymeric binding sites (Fig. 6-1). Thus, the template can be linked and subsequently recognized by virtually any combination of cleavable covalent bonds, metal ion co-ordination or noncovalent bonds. The first example of molecular imprinting of organic network polymers introduced by Wulff was based on a covalent attachment strategy i.e. covalent monomer-template, covalent polymer-template [12]. 

Fig. 6-2. Preparation of MIPs using L-phenylalanine anilide (L-PA) as template. The L-PA model system.

Fig. 6-3. Principle of the chromatographic evaluation of the recognition properties of MIPs.

Table 6-1. Examples of racemates successfully resolved on MIPs. ...

Table 6-2. Examples of highly selective recognition by MIPs.

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