Enrichment assessment

Once a proper validation database has been generated, the enrichment of actives caused by a pharmacophore model can be predicted by different methods. It can be either expressed as a single value or as a graph providing an overview of the enrichment for all possible hit list cutoffs. All enrichment-assessing methods are based on the following assumption  

---

Pvaluation of the performance of 3D virtual screening protocols RMSD comparisons, enrichment assessments, and decoy selection what can we learn from earlier mistakes Journal of Computer-Aided Molecular Design, 22 (3-4), 213-228. 

The only large-scale use of deuterium in industry is as a moderator, in the form of D2O, for nuclear reactors. Because of its favorable slowing-down properties and its small capture cross section for neutrons, deuterium moderation permits the use of uranium containing the natural abundance of uranium-235, thus avoiding an isotope enrichment step in the preparation of reactor fuel. Heavy water-moderated thermal neutron reactors fueled with uranium-233 and surrounded with a natural thorium blanket offer the prospect of successful fuel breeding, ie, production of greater amounts of (by neutron capture in thorium) than are consumed by nuclear fission in the operation of the reactor. The advantages of heavy water-moderated reactors are difficult to assess. 

Individuals, regardless of gender, race, sexual orientation or socio-economic level, seek mentors for many of the same reasons. This may be for resources, visibility, enhanced skill, and counsel. However, each individual or mentee brings different expectations. Successful mentors assess where a mentee is, not where the mentee should be. The mentor provides ample opportunity for expectation discussions to take place, which in turn will guide and enrich the experience. 

Traps with Bio-Sep beads amended with [ Cg]-benzene and [ C]-toluene were used to assess biodegradation in an aquifer (Geyer et al. 2005). Beads were lyophilized after exposure, lipids were extracted with chloroform-methanol, and the fatty acids and values analyzed. High enrichment of was observed in several fatty acids, which showed that the label from the substrates had been incorporated. In addition, there were differences in the abundance of the fatty acids in beads amended with benzene or toluene that suggested the existence of different microbial degradative populations. 

Mass spectrometry can be specific in certain cases, and would even allow on-line QA in the isotope dilution mode. MS of molecular ions is seldom used in speciation analysis. API-MS allows compound-specific information to be obtained. APCI-MS offers the unique possibility of having an element- and compound-specific detector. A drawback is the limited sensitivity of APCI-MS in the element-specific detection mode. This can be overcome by use of on-line sample enrichment, e.g. SPE-HPLC-MS. The capabilities of ESI-MS for metal speciation have been critically assessed [546], Use of ESI-MS in metal speciation is growing. Houk [547] has emphasised that neither ICP-MS (elemental information) nor ESI-MS (molecular information) alone are adequate for identification of unknown elemental species at trace levels in complex mixtures. Consequently, a plea was made for simultaneous use of these two types of ion source on the same liquid chromatographic effluent. 

Encinar et al. [128] used a spike containing 119Sn enriched mono-, di-, and tributyltin to determine butyltin compounds in seawater GC-ICPMS. Reverse spiking was used to assess species transformation during derivativisation. 

Handy, R.D. 1992. The assessment of episodic metal pollution. II. The effects of cadmium and copper enriched diets on tissue contaminant analysis in rainbow trout (Oncorhynchus mykiss). Arch. Environ. Contam. Toxicol. 22 82-87. 

---